lawrence livermore national laboratory rate constant ... · development of chemical kinetic models...
TRANSCRIPT
Lawrence Livermore National LaboratoryLawrence Livermore National Laboratory
Rate Constant Estimation for Large Chemical Kinetic Models and Application to Biofuels
CC 2001ICCK 2001 MITJuly 28 2011
William J Pitz Henry J Curran Charles Westbrook Marco Mehl S MSarathy and Taku TsujimuraSarathy and Taku Tsujimura
Lawrence Livermore National Laboratory
LLNL-PRES-490531
Lawrence Livermore National Laboratory P O Box 808 Livermore CA 94551This work performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Development of chemical kinetic models for fuels
Ab initio calculationsFundamental experimental measurementsmeasurements
oh 713 0 rucich 1o 1 0 0g 300000 5000000 1710000 01
285376040e+00 102994334e-03-232666477e-07 193750704e-11-315759847e-16 2
369949720e+03 578756825e+00 341896226e+00 319255801e-04-308292717e-07 3
364407494e-10-100195479e-13 345264448e+03 254433372e+00 4c3h8+ohlt=gtnc3h7+h2o 1054e+10 0970 1586e+03
Detailed chemical kinetic Reaction rate rules
C1C2 base chemistry Thermodynamic database Reaction rate constants
model for practical fuelsReaction rate rules
High temperature mechanismReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerization
reactions
h+o2lt=gto+oh 965E+14 -0262 162E+04
o+h2lt=gth+oh 5080e+04 2670 6292e+03
oh+h2lt=gth+h2o 2160e+08 1510 3430e+03
o+h2olt=gtoh+oh 2970e+06 2020 1340e+04
h2+mlt=gth+h+m 4577e+19 -1400 1044e+05
h2 2 5 h2 12 1 9 2 3 8
2LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionReaction class 9 Olefin decomposition
h2 25 h2o 12 co 19 co2 38
o+o+mlt=gto2+m 6165e+15 -0500 0000e+00
h2 25 h2o 12 ar 83 co 19 co2 38 ch4 2 c2h6 3 he 83
o+h+mlt=gtoh+m 4714e+18 -1000 0000e+00
h2 25 h2o 12 ar 75 co 15 co2 2 ch4 2 c2h6 3 he 75
Need reaction rate rules for many chemical classes of fuels
AlkanesAlk Alkenes
Cycloalkanes Aromatics Aromatics Alcohols Methyl esters (biodiesel compounds)y ( p ) Carbenes (aldehydes ketenes) Special structures in intermediate species
OH
bull Alkylhydroperoxidesbull Alkylperoxy
OOH
3LLNL-PRES-490531
Lawrence Livermore National Laboratory
Need reaction rate rules for many types of reaction steps
HRbull
- RH
Fast High
Temperature CombustionLong Chain Alkanes
bull
ty
bull
+ O2OObull
Low T
Mechanism
Rea
ctiv
it Hi T
MechanismNTC
OO
OOHbull
Mechanism
+ HO2bull
O
Reactor TemperatureOOH
+ O2
+ bullOH
+ bullOH+
O
Degenerate Branching Path
bullOO
O- bullOH
O OH
4LLNL-PRES-490531
Lawrence Livermore National Laboratory
HOOO
bull
bullOH+ +
Assign reaction rate rules by reaction classes
High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition
5LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2
6LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules make the assignment of reaction rate constants manageable Class 2
H atom abstraction rate rules for alkanes
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 6 50 05 2 40 4 471
H- atom abstraction rate rules for alkanes
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 151E-01 365 7154
CH3 2 755E-01 346 5481
3 6 01E 10 6 36 8933 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
7LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of chemical kinetic models for fuels
Ab initio calculationsFundamental experimental measurementsmeasurements
oh 713 0 rucich 1o 1 0 0g 300000 5000000 1710000 01
285376040e+00 102994334e-03-232666477e-07 193750704e-11-315759847e-16 2
369949720e+03 578756825e+00 341896226e+00 319255801e-04-308292717e-07 3
364407494e-10-100195479e-13 345264448e+03 254433372e+00 4c3h8+ohlt=gtnc3h7+h2o 1054e+10 0970 1586e+03
Detailed chemical kinetic Reaction rate rules
C1C2 base chemistry Thermodynamic database Reaction rate constants
model for practical fuelsReaction rate rules
High temperature mechanismReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerization
reactions
h+o2lt=gto+oh 965E+14 -0262 162E+04
o+h2lt=gth+oh 5080e+04 2670 6292e+03
oh+h2lt=gth+h2o 2160e+08 1510 3430e+03
o+h2olt=gtoh+oh 2970e+06 2020 1340e+04
h2+mlt=gth+h+m 4577e+19 -1400 1044e+05
h2 2 5 h2 12 1 9 2 3 8
2LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionReaction class 9 Olefin decomposition
h2 25 h2o 12 co 19 co2 38
o+o+mlt=gto2+m 6165e+15 -0500 0000e+00
h2 25 h2o 12 ar 83 co 19 co2 38 ch4 2 c2h6 3 he 83
o+h+mlt=gtoh+m 4714e+18 -1000 0000e+00
h2 25 h2o 12 ar 75 co 15 co2 2 ch4 2 c2h6 3 he 75
Need reaction rate rules for many chemical classes of fuels
AlkanesAlk Alkenes
Cycloalkanes Aromatics Aromatics Alcohols Methyl esters (biodiesel compounds)y ( p ) Carbenes (aldehydes ketenes) Special structures in intermediate species
OH
bull Alkylhydroperoxidesbull Alkylperoxy
OOH
3LLNL-PRES-490531
Lawrence Livermore National Laboratory
Need reaction rate rules for many types of reaction steps
HRbull
- RH
Fast High
Temperature CombustionLong Chain Alkanes
bull
ty
bull
+ O2OObull
Low T
Mechanism
Rea
ctiv
it Hi T
MechanismNTC
OO
OOHbull
Mechanism
+ HO2bull
O
Reactor TemperatureOOH
+ O2
+ bullOH
+ bullOH+
O
Degenerate Branching Path
bullOO
O- bullOH
O OH
4LLNL-PRES-490531
Lawrence Livermore National Laboratory
HOOO
bull
bullOH+ +
Assign reaction rate rules by reaction classes
High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition
5LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2
6LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules make the assignment of reaction rate constants manageable Class 2
H atom abstraction rate rules for alkanes
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 6 50 05 2 40 4 471
H- atom abstraction rate rules for alkanes
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 151E-01 365 7154
CH3 2 755E-01 346 5481
3 6 01E 10 6 36 8933 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
7LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Need reaction rate rules for many chemical classes of fuels
AlkanesAlk Alkenes
Cycloalkanes Aromatics Aromatics Alcohols Methyl esters (biodiesel compounds)y ( p ) Carbenes (aldehydes ketenes) Special structures in intermediate species
OH
bull Alkylhydroperoxidesbull Alkylperoxy
OOH
3LLNL-PRES-490531
Lawrence Livermore National Laboratory
Need reaction rate rules for many types of reaction steps
HRbull
- RH
Fast High
Temperature CombustionLong Chain Alkanes
bull
ty
bull
+ O2OObull
Low T
Mechanism
Rea
ctiv
it Hi T
MechanismNTC
OO
OOHbull
Mechanism
+ HO2bull
O
Reactor TemperatureOOH
+ O2
+ bullOH
+ bullOH+
O
Degenerate Branching Path
bullOO
O- bullOH
O OH
4LLNL-PRES-490531
Lawrence Livermore National Laboratory
HOOO
bull
bullOH+ +
Assign reaction rate rules by reaction classes
High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition
5LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2
6LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules make the assignment of reaction rate constants manageable Class 2
H atom abstraction rate rules for alkanes
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 6 50 05 2 40 4 471
H- atom abstraction rate rules for alkanes
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 151E-01 365 7154
CH3 2 755E-01 346 5481
3 6 01E 10 6 36 8933 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
7LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Need reaction rate rules for many types of reaction steps
HRbull
- RH
Fast High
Temperature CombustionLong Chain Alkanes
bull
ty
bull
+ O2OObull
Low T
Mechanism
Rea
ctiv
it Hi T
MechanismNTC
OO
OOHbull
Mechanism
+ HO2bull
O
Reactor TemperatureOOH
+ O2
+ bullOH
+ bullOH+
O
Degenerate Branching Path
bullOO
O- bullOH
O OH
4LLNL-PRES-490531
Lawrence Livermore National Laboratory
HOOO
bull
bullOH+ +
Assign reaction rate rules by reaction classes
High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition
5LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2
6LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules make the assignment of reaction rate constants manageable Class 2
H atom abstraction rate rules for alkanes
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 6 50 05 2 40 4 471
H- atom abstraction rate rules for alkanes
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 151E-01 365 7154
CH3 2 755E-01 346 5481
3 6 01E 10 6 36 8933 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
7LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Assign reaction rate rules by reaction classes
High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition
5LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2
6LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules make the assignment of reaction rate constants manageable Class 2
H atom abstraction rate rules for alkanes
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 6 50 05 2 40 4 471
H- atom abstraction rate rules for alkanes
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 151E-01 365 7154
CH3 2 755E-01 346 5481
3 6 01E 10 6 36 8933 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
7LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2
6LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules make the assignment of reaction rate constants manageable Class 2
H atom abstraction rate rules for alkanes
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 6 50 05 2 40 4 471
H- atom abstraction rate rules for alkanes
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 151E-01 365 7154
CH3 2 755E-01 346 5481
3 6 01E 10 6 36 8933 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
7LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules make the assignment of reaction rate constants manageable Class 2
H atom abstraction rate rules for alkanes
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 6 50 05 2 40 4 471
H- atom abstraction rate rules for alkanes
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 151E-01 365 7154
CH3 2 755E-01 346 5481
3 6 01E 10 6 36 8933 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
7LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rule issues fuel decomposition reactionsClass 1
AlkanesS t b ti
C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction
Exothermic directionC C bond breaking most important
C-C-C-C lt=gt C-C + C-C
C-C bond breaking most important Some variations in forward rate constants even
though you think they should be all the same
8LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Reaction rate rules for H-atom abstraction from alkanesClass 2
C H A ( 3 l 1 1) E ( l)
Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)
C-H type A (cm3 mol-1 s-1) n EA (cal)
1 222E+05 254 6756
H 2 650e+05 240 4471
3 602E+05 240 2583
1 176E+09 097 1586
OH 2 234E+07 161 -35
3 573E+10 051 63
1 1 51E 01 3 65 7 1541 151E-01 365 7154
CH3 2 755E-01 346 5481
3 601E-10 636 893
1 680E+00 359 17160
HO2 2 316E+01 337 13720
3 650E+02 301 12090
9LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
1E-10
05 1 15 2 25 3 35 4 45
n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes
Sirvaramakrishnan et al 2009 (Argonne)
n-butane + OH = butyl + H2O
1E-11Droege and Tully 1986 (Sandia)
LLNL-NUIG Reaction rate rules
1E-12
10LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
h di l h
New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2
1 E ‐ 1 0
0 5 1 1 5 2 2 5 3 3 5 4 4 5
n‐propane+oh = radical+h2og
Si k i h 2009 i t
Sivaramakrishnan 2009 theory
1 E ‐ 1 1
LLNL‐NUIG reaction rate rule
Sivaramakrishnan 2009 experiments
Squares Droege and Tully 1986 experiments
Sirvaramakrishnan 2009
propane + OH = propyl + H2O
1 E ‐ 1 2
LLNL-NUIG rate rule (based on Tully)
11LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
n propane+oh= radical+h2o
Ab initio calculations show higher rates due to higher primary rate Class 2
n‐propane+oh = radical+h2o
LLNL primaryLLNL d
Argonnersquos calculated cross-over
1E+13
sec‐1
LLNL secondaryArgonne primaryArgonne secondary
(ab initio)
(ab initio)
3 mole‐
1 ‐s
Tully primaryTully secondary
(Experimental)
(Experimental)
Tullyrsquos measured
k cm
3 Tully s measured crossover
1E+12propane + OH = propyl + H2O
12LLNL-PRES-490531
Lawrence Livermore National Laboratory
05 10 15 201000T[K]
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2
C3H8+HO2 =gt iC3H7+H2O2Ignition very
sensitive to this rate constant
NUIG
CSM under RCM conditions
13LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2
H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine
20
25
30
[ms] Sensitivity Rate Constants x 2
H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O
50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125
Baseline New rate constant fit
10
15
Igni
tion
dela
y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2
Most sensitive reaction1E+13
1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005
Tsang and Hampson 1986
Ellingson 2007
Temperature of Sensivity analysis
(963 K)New fit
0
5
094 096 098 100 102 104 106
1Tc [1K]
H2O2+Hlt=gtH2+HO2
1E+12
Log
k
Baldwin and Walker 1967
Fit new H2 mechanism
N t d t Elli 2007
1E+10
1E+11
05 07 09 11 13 15 17
New computed rate Ellingson 2007Important branching sequence at high pressure
H2+HO2=gtH+H2O2
H2O2=gtOH+OH
Retarding reaction
14LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T[K]Retarding reaction
HO2+HO2=gtH2O2+O2
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Class 3 alkyl radical decomposition Improvements for iso-octane Class 3
1000
10 atm100
mes
[ms]
10 atm
Stoichiometric mixtures
10
ion
Del
ay T
i
55 atm
1Igni
t
Dashed Previous mechanism on website
Solid Updated version01
08 09 1 11 12 13 14 15 16
Solid Updated version
15LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000KT
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
More accurate estimate for iso-octyl radical decomposition rate constant Class 3
1E+12
1E+13
LLNL originalC l d S h l f Mi b i iti
cC8H17 =gt tC4H9 + iC4H8
1E+09
1E+10
1E+11
k
Colorado School of Mines ab initio
Klippenstein ab initio
1E+06
1E+07
1E+08
Log
k
1E+03
1E+04
1E+05Milano generic for alkyl radicals
16LLNL-PRES-490531
Lawrence Livermore National Laboratory
06 08 10 12 14 16
1000T[K]
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry
Class 10R+O2 RO2
Bond dissociation energy ( H ) R OO =gt R + O2
Values used in LLNL models
-10
-5
0
Bond dissociation energy ( H 298) R-OO =gt R + O2
-25
-20
-15
del H
-40
-35
-30
-45
17LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Low temperature chemistry ROO QOOH isomerizations Class 12
O
6 Member ring isomerization
OO
OOH
OO
H
K6 = 25E+10 exp(-20450RT)
OO
OOHO
O
5 Member ring isomerization
O OOH
18LLNL-PRES-490531
Lawrence Livermore National Laboratory
K5 = 20E+11 exp(-26450RT)
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)
Class 12
5-member TS 6-member TSOH
OHR
tertiaryprimary
RO O
secondary
primarytertiary
Activation energy depends on ring size and overall thermochemistry Amenable to rule generation
19LLNL-PRES-490531
Lawrence Livermore National Laboratory
g
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12
bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS
ndash Mainly due to higher A-factors (much higher than alkyl i i ti )
20LLNL-PRES-490531
Lawrence Livermore National Laboratory
isomerizations)bull Differences lead to significantly different reaction pathways
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size
Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions
Propane100 Species - 400 Reactions
CH4
CH3 O2
H2O2
OH
HO
HO
H2O
C H
3
CH3O
CH O
CH3OH
CH OH
2
C2H5
C2H6
C2H4
CH3OO
CH3OOH
HO2
HO2
H2O2 Aromatics
SootOH
HCO
CO
CO2
C2H3 CH2O CH2OHO2
C2H2
Soot CO2
21LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Fuels Size and Mechanism Size
C H
n-Alkane Mechanism Size
(Detailed Mechanism)C8H18
C10H22
700 Species
3150 Reactions
(Detailed Mechanism)
C12H26
950 Species
4050 Reactions
1250 Species
C14H30
1250 Species
5150 Reactions
1650 Species
C16H34
5150 Reactions
2100 Species
22LLNL-PRES-490531
Lawrence Livermore National Laboratory
8150 Reactions
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Application of rules to biofuels
BiodieselL th l tbull Large methyl esters
Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol
Aromatics
Olefins
23LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels
Biomass derived from algae and other single cell organisms
Algal pilot scale bioreactor in Lawrence Kansas
F S ith St d N ll d Billi T d E l E l (2010)
rapeseed
24LLNL-PRES-490531
Lawrence Livermore National Laboratory
From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Algal oil-derived fuels contain additional esters
From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523
25LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p
Methyl Palmitate (C160)
triglycerideOO
O
O
R R
+ 3 CH 3OH
Fatty acid methyl esters (FAMEs)
Methyl Stearate (C180)
methanolO
O
O
R OHO
70
Methyl Oleate (C181)methyl ester glycerol
OHOH
CH3OR
3 +
3040506070
SoybeanRapeseed Methyl Linoleate (C182)
0102030
Methyl Linolenate (C183)
26LLNL-PRES-490531
Lawrence Livermore National Laboratory
C160 C180 C181 C182 C183
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil
Built with the same reaction rate rules as our successful
th l d t d th l
methyl palmitate
methyl decanoate and methyl decenoate mechanismmethyl stearate
5 component mechanism
approximatelymethyl linoleate
methyl oleate
approximately
5000 species20000 reactions
methyl linoleate
methyl linolenatemethyl linolenate
27LLNL-PRES-490531
Lawrence Livermore National Laboratory
Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor
10 Methyl palmitate
0 6
08
on Stoichiometric fuelO2He
04
06
Con
vers
io
n-decane
Stoichiometric fuelO2He mixtures1 atm15 s residence time
02
Jet stirred reactor data H kk t l C b Fl00
500 600 700 800 900 1000 1100
Temperature - K
Hakka et al Comb Flame 2009
28LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Many of the predicted species profiles compare well with experiments eg 1-heptene
80E-05
60E-05
on
1-heptene
Jet stirred reactor data
40E-05
Mol
e fr
actio Jet stirred reactor data
Hakka et al Comb Flame 2009
20E-05
M
00E+00500 600 700 800 900 1000 1100
Temperature - K
29LLNL-PRES-490531
Lawrence Livermore National Laboratory
Temperature K
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Biodiesel components ignite in order of number of double bonds
100 Engine-like diti
ms
stearate
linoleate
palmitate
conditions135 barStoichiometric fuelair mixtures
10
on d
elay
-m
oleate
linolenate
1
Igni
tio
0108 1 12 14 16
30LLNL-PRES-490531
Lawrence Livermore National Laboratory
1000T - K
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions
methyl stearate CN101
Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)
1
Simulated conversions of biodiesel components
methyl stearate CN101
methyl oleate CN 59
06
08
rsio
n
St t 101
CN
C 23
methyl oleate CN 59CN101
CN 59
02
04
Con
ver Stearate 101
Oleate 59
Linolenate 23
CN 23
methyl linolenate
0500 600 700 800 900 1000 1100
Temperature - KD i d t b f K th (2010)
Jet stirred reactor
31LLNL-PRES-490531
Lawrence Livermore National Laboratory
Derived cetane numbers from Knothe (2010)
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
C = C double bonds reduce low T reactivity
s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -
s s a a s ss s a a s s
Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain
Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off
rapidly inhibiting low T reactivity
32LLNL-PRES-490531
Lawrence Livermore National Laboratory
rapidly inhibiting low T reactivity
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
We have seen the same effect in hydrocarbon fuels hexenes
Ignition delay times in a rapid compression machine of hexene isomers
80
100
[ms]
80
100
[ms]
machine of hexene isomers (086-109 MPa Φ=1)
C = C - C - C - C - C 1-hexene
3-Hexene
2-Hexene40
60
80
dela
y tim
e 3-Hexene
2-Hexene40
60
80
dela
y tim
e C - C = C - C - C - C 2-hexene
C - C - C = C - C - C 3-hexene
1-Hexene0
20
40
Igni
tion
d
1-Hexene0
20
40
Igni
tion
d
RO2 isomerization initiates low temperature reactivity
0650 700 750 800 850 900
T [K]
0650 700 750 800 850 900
T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005
Simulations Mehl Vanhove Pitz Ranzi Combustion
33LLNL-PRES-490531
Lawrence Livermore National Laboratory
and Flame 2008
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine
palmitate 7 7 7 4 23 10 13 28 46 11 8 4
stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1
oleate 19 13 19 49 20 38 72 47 40 49 25 60
linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21
linolenate 1 0 54 1 1 0 1 1 0 0 8 14
CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7
With models for all 5 major components we can now model all these types of biodiesel
34LLNL-PRES-490531
Lawrence Livermore National Laboratory
bull Not a surrogate model but a real biodiesel (B100) model
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp
50 bar=2Si l t d Di l PRF l i PSR
1
Diesel PRF mixtures
CN60
2fuel 200 ppm=005s
CN50Jet stirred reactor
(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR
05
075
nver
sion
CN50
CN40
CNCN20
CN40
0
025
500 600 700 800 900 1000 1100
Con CN60
CN20
500 600 700 800 900 1000 1100
Temperature - K
As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion
35LLNL-PRES-490531
Lawrence Livermore National Laboratory
has a greater extent of low T combustion
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources
Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels
08
1
onlinseedbeef tallowpeanut
CN60 (PRF)
Beef tallow (CN58)
04
06
Con
vers
io peanutolivesoyrapeseed
CN20(PRF)
Linseed (CN39)
(C )
0
02
500 600 700 800 900 1000 1100
Temperature K
pCN20CN60
Rapeseed (CN54)(PRF)(PRF)
Temperature - K
Jet stirred reactor
50 bar=2fuel 200 ppm
36LLNL-PRES-490531
Lawrence Livermore National Laboratory
Jet stirred reactor =005s
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Observations on reactivity of biodiesel fuels from different oils
Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity
Detailed composition of these biodiesel fuels determine their reactivityreactivity
Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds
We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism
The mechanisms still need refinements and testing and careful
37LLNL-PRES-490531
Lawrence Livermore National Laboratory
laboratory experiments would be very valuable
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is
one of biomass derived alcoholic fuel like Ethanol
httpwwwjbeiorg
The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of
httpwwwjbeiorg
(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester
Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol
38LLNL-PRES-490531
Lawrence Livermore National Laboratory
density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Approach
Development of Isopentanol reaction mechanismmechanism
Single-zone Simulations Validation
Study of the kinetics involved in the auto-ignition process
Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion
Compare with representative experimental ltresults
39LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel
by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane
has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo
Concerted elimination of HO H
C
OO
O
Concerted elimination of HO2 Concerted elimination forming aldehyde
and HO2 from RO2 is so fast that low
40LLNL-PRES-490531
Lawrence Livermore National Laboratory
2 2
temperature reactions would be slowed down
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Schematic Energy Diagram for the Concerted Elimination of HO2
+ O2H abstraction by radicals
H + RadicalsOH
H
OH
+ Radicals
OOH
II O
OOH
+ HO2
I
O
IOO O
C
OH
O
41LLNL-PRES-490531
Lawrence Livermore National Laboratory
OH
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Validations of Reaction Mechanism100000
c]
05
Pi i 07 2 MPa
100000
c]
10
Pi i 07‐08
1000
10000
ay time [
se
ST‐Exp P 20MPa
CV‐Cal P 20MPa
RCM E P 2 0MP
Pini 07 2 MPa
1000
10000
ay time [
se
ST‐Exp P 23MPaCV Cal P 2 0MPa
Pini 07 08
2‐23 MPa
100
Ignitio
n de
la RCM‐Exp P 20MPa
RCM‐Cal P 20MPa
ST‐Exp P 07MPa
CV‐Cal P 07MPa
RCM E P 0 7MP
100
Ignitio
n de
la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa
10
7 8 9 10 11 12 13 14 15
[ ]
RCM‐Exp P 07MPa
RCM‐Cal P 20MPa10
7 8 9 10 11 12 13 14 15
10 000T [1K]
RCM‐Exp P 07MPaRCM‐Cal P 07MPa
bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM
10000T [1K] 10000T [1K]
42LLNL-PRES-490531
Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)
tube and an RCM
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g
Iso-pentanol mechanism
HCCI engine experimentsYang and Dec Sandia SAE 2010
N ti bi f l d b
Reaction rate rules on successful iso-
New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)
Model development and application
octane because it has some similar structures
Model development and applicationLLNL visiting scientist
Dr Taku TsujimuraNational Institute of Advanced
43LLNL-PRES-490531
Lawrence Livermore National Laboratory
Industrial Science and Technology Japan
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g
Experiments and CalculationsRequired TBDC for constant combustion phasing
120
140
160
80
100
120
C[degC]
Exp CA10 368 6 deg CAwith EGR
Iso-pentanol
20
40
60
T BDC Exp CA10 3686 degCA
Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA
m 038
0
80 100 120 140 160 180 200 220
P [kPa]
Cal CA50 3715 degCA
44LLNL-PRES-490531
Lawrence Livermore National Laboratory
Pin [kPa]
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI
E i t C l l ti
Iso-pentanol
Experiments
TDC
Calculations
TDC
CA10 3686 degCA
m 038
CA50 3686 degCAm 038m 038
no EGR
no EGR
HCCI engine experiments
45LLNL-PRES-490531
Lawrence Livermore National Laboratory
Yang and Dec Sandia SAE 2010
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p
Flame speed measurements
butanol mechanism 4 isomers
Flame speed measurementsEgolfopoulos et al USC
OH
Iso-butanol is a new type of
biofuel that can be made directly
Twin premixed counterflow flames
be made directly from cellulose using bacteria
46LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data
Veloo Egolfopoulos et
40
50
60
ocity
(cms)
30
40
50
city (cms)
Veloo Egolfopoulos et al 2010 2011
fuelair mixtures
10
20
30
nar F
lame Velo
1‐Butanol10
20
30
ar Flame Velo
iso‐Butanol
1 atm
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lamin
Equivalence Ratio
30
40
50
elocity
(cms)
30
40locity (cms)
10
20
30
minar Flame Ve
2‐Butanol 10
20
inar Flame Ve
tert‐Butanol
47LLNL-PRES-490531
Lawrence Livermore National Laboratory
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
0
04 06 08 1 12 14 16 18
Lam
Equivalence Ratio
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines
1Symbolsexperimental dataSung et al
Rapid compression machine
0 1s)
AIAA paper 2011iso-butanol
tert-butanol
01
ay ti
me
(s
Rapid compression machineU i it f C ti t
001
nitio
n D
ela University of Connecticut
n-butanol
2-butanolbutanol isomers
00011 05 1 15 1 25 1 35 1 45
Ign butanol isomers
15 atm phi=1 in air
48LLNL-PRES-490531
Lawrence Livermore National Laboratory
105 115 125 135 1451000T (1K)
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Chemical kinetic mechanism for larger aromatics
CO
CO
The kinetic mechanism of the aromatics has an intrinsic hierarchical structure
49LLNL-PRES-490531
Lawrence Livermore National Laboratory
CO2
H2OA new module specific to C8 alkyl aromatics is now under development
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
p-Xylene mechanism well reproduces species profiles in jet stirred reactor
1E‐02
1E‐01
O2
p-Xylene 1E‐04
1E‐03
Toluene
1 E‐05
1E‐04
1E‐03p Xylene
COCO2
1E‐05
1E 04
Benzaldehyde
Benzene
Cyclopentadiene
Mol
e Fr
actio
n
Mol
e Fr
actio
n1E‐06
1E‐05
900 1000 1100 1200 1300 1400T [K]
CH2O
1E‐06
900 1000 1100 1200 1300 1400T [K]
y
1E‐02Jet stirred reactor
Experiments Gail and DagautCombustion and Flame 2005
P = 1 atm Ф = 1 τ = 01s
ract
ion
1 E‐04
1E‐03
H2
CH4
C2H4
Mol
e Fr
1E‐05
1E 04 2 4
C2H6
C2H4
50LLNL-PRES-490531
Lawrence Livermore National LaboratoryT [K]
1E‐06
900 1000 1100 1200 1300 1400
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines
100000
Ignition delay times in a shock tube for aromatics
10000
10 atm fuelair mixtures =1
Tim
es [micro
s]
Ortho xylene
1000
ion
Del
ay T
Ethylbenzene
Para-xyleneOrtho-xylene
Shock tube experimental data
10
100
Igni
t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009
07 08 09 1
1000KT
51LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Mechanisms are available on LLNL website and by email
httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion
52LLNL-PRES-490531
Lawrence Livermore National LaboratoryLLNL-PRES -427942
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Summary
Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants
Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels
Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics
53LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledgements
Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol
John Dec and Yi Yang iso-pentanol
54LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory
Acknowledge support from
DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh
bull Kevin Stork
DOE Office of Basic Energy Sciencesbull Wade Sisk
DOD Office of Naval Research
55LLNL-PRES-490531
Lawrence Livermore National Laboratory