stoichiometric, ammonia and stoichiometric, ammonia and ... · stoichiometric, ammonia and...
Post on 19-Jun-2018
303 Views
Preview:
TRANSCRIPT
THE OPERATING FEATURES OF A THE OPERATING FEATURES OF A STOICHIOMETRIC, AMMONIA AND STOICHIOMETRIC, AMMONIA AND GASOLINE DUAL FUELED SPARK GASOLINE DUAL FUELED SPARK
IGNITION ENGINEIGNITION ENGINEByBy
Shawn Grannell Dennis AssanisShawn Grannell Dennis AssanisStanislav Bohac Don GillespieStanislav Bohac Don Gillespie
University of MichiganMechanical Engineering Dept. & Applied Physics Program
Supported by the Fannie and John Hertz Foundation.
OverviewOverview
Experimental EngineExperimental EngineBasic FeaturesBasic FeaturesFuel Mix MapFuel Mix MapRough and Knock LimitsRough and Knock LimitsThermal EfficiencyThermal EfficiencyEngine Out EmissionsEngine Out EmissionsPost Catalyst EmissionsPost Catalyst EmissionsConclusionsConclusions
(0.79 N(0.79 N22 + 0.21 O+ 0.21 O22) + 0.024b C) + 0.024b C66HH1111 + 0.28(1+ 0.28(1--b) NHb) NH33⇒⇒ (0.93 (0.93 –– 0.14b) N0.14b) N22 + (0.42 + (0.42 –– 0.288b) H0.288b) H22O + O + 0.144b CO0.144b CO22
Lower Heating Value (LHV) energy yield: (88.7 Lower Heating Value (LHV) energy yield: (88.7 –– 4b) kJ4b) kJb = fraction of the oxygen burned by gasoline. b = fraction of the oxygen burned by gasoline. 0 0 ≤≤ b b ≤≤ 11Stoichiometric ammonia/air mixture has 83% of energy Stoichiometric ammonia/air mixture has 83% of energy density of stoichiometric gasoline/air mixture.density of stoichiometric gasoline/air mixture.Gasoline is the combustion promoter. Other fuels Gasoline is the combustion promoter. Other fuels such as hydrogen could be used as combustion such as hydrogen could be used as combustion promoters.promoters.
Ideal Combustion EquationIdeal Combustion Equation
CFR Engine FeaturesCFR Engine Features
Variable compression ratio.Variable compression ratio.Supercharge Capability.Supercharge Capability.Cylinder pressure monitored with sensor.Cylinder pressure monitored with sensor.Rigorous, calibrated measurements during steady Rigorous, calibrated measurements during steady state operation.state operation.Single cylinder = 0.625 liters.Single cylinder = 0.625 liters.Ammonia used without decomposing any of it Ammonia used without decomposing any of it first.first.
Catalytic Converter
Engine Out Oxygen Sensor
Post Catalyst Oxygen Sensor
Spark Advance
Compression Ratio Crank
Work Definitions:Work Definitions:
IMEPIMEPgg = (gross) Indicated Mean Effective Pressure. = (gross) Indicated Mean Effective Pressure. ((kPakPa) The effective piston driving pressure for ) The effective piston driving pressure for compression/expansion.compression/expansion.IMEPIMEPnn = (net) Indicated Mean Effective Pressure. = (net) Indicated Mean Effective Pressure. ((kPakPa) Same, but also includes intake/exhaust processes.) Same, but also includes intake/exhaust processes.BMEP = Brake Mean Effective Pressure. The effective BMEP = Brake Mean Effective Pressure. The effective driving pressure for work available at the crankshaft.driving pressure for work available at the crankshaft.FMEP = Friction Mean Effective Pressure. For most FMEP = Friction Mean Effective Pressure. For most engines, this is about 1engines, this is about 1--1.5 bar.1.5 bar.BMEP = IMEPBMEP = IMEPnn -- FMEP.FMEP.
What is IMEPWhat is IMEPnn??Throttled Throttled
0
500
1000
1500
2000
0 0.2 0.4 0.6 0.8
Cylinder Volume (Liters)
Cyl
inde
r Pre
ssur
e (k
Pa) Intake
CompressionExpansionExhaust
Exhaust & Intake Pumping Loop
Gross Indicated Work
Net Indicated Work
+
=
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-30 -20 -10 0 10 20 30 40 50 60 70 80
Crank Angle (deg)
App
aren
t Mas
s Fr
actio
n B
urne
d fo
r 8:1
, 16
00 R
PM, I
MEP
n ~
550
kPa
87% Gas/13% NH3, COV = 0.7%35% Gas/65% NH3, COV = 2.8%24% Gas/76% NH3, COV = 16.6%
What happens at the rough limit?What happens at the rough limit?
What about Knock?What about Knock?
-20
-15
-10
-5
0
5
10
15
20
25
-5 0 5 10 15 20 25 30
Crank Angle (degrees)
Kno
ck S
igna
l (kP
a), G
asol
ine,
10:
1, p
eak
pres
sure
= 2
9 ba
r.
Knock Filter Output
-20
-15
-10
-5
0
5
10
15
20
25
-5 0 5 10 15 20 25 30
Crank Angle (degrees)
Kno
ck S
igna
l (kP
a), A
mm
onia
, 12
:1, p
eak
firin
g pr
essu
re =
100
bar
.
Ammonia doesn’t knock at 100 bar
Gasoline knocks at 20-30 bar
Cylinder Pressure and Mass Fraction BurnedCylinder Pressure and Mass Fraction Burned
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-30 -20 -10 0 10 20 30 40 50 60 70 80
Crank Angle (degrees)
App
aren
t Mas
s Fr
actio
n B
urne
d
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 5
1.6
1.8
2
2.2
2.4
0.2 0.4 0.6 0.8 1
Log10(Cylinder Volume)
Log 1
0(C
ylin
der P
ress
ure) Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-30 -20 -10 0 10 20 30 40 50 60 70 80
Crank Angle (degrees)
App
aren
t Mas
s Fr
actio
n B
urne
d
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 5
1.6
1.8
2
2.2
2.4
0.2 0.4 0.6 0.8 1
Log10(Cylinder Volume)
Log 1
0(C
ylin
der P
ress
ure)
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-30 -20 -10 0 10 20 30 40 50 60 70 80
Crank Angle (degrees)
App
aren
t Mas
s Fr
actio
n B
urne
d
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 5
1.8
2
2.2
2.4
2.6
0.2 0.4 0.6 0.8 1
Log10(Cylinder Volume)
Log 1
0(C
ylin
der P
ress
ure)
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 5
Rough Limit Smooth, MBT RetRough Limit Smooth, MBT Retarded Sparkarded Spark
Increasing gasoline input per cycle
Fuel Mix Sweep for 8:1, 1600 RPM, Fuel Mix Sweep for 8:1, 1600 RPM, IMEPnIMEPn = = 550 550 kPakPa
0
10
20
30
40
50
60
70
80
90
0 20 40 60 80 100LHV Basis (% Gasoline)
(Deg
rees
) or (
%) a
s sp
ecifi
edSpark Adv. (deg)Ign. delay (deg)Burn Duration (deg)Net Ind. Th. (%)COV (IMEPn) (%)
Rough limit
Knock limit
The Rough LimitThe Rough Limit
0102030405060708090
100
0 200 400 600 800 1000 1200 1400
IMEPn (kPa)
LHV
Bas
is (%
Gas
olin
e) 8:1
10:1
12:1
Throttled SuperchargedIdle
Normally aspirated road load
Ammonia Favored Here
Charge density at spark depends on load at Charge density at spark depends on load at rough limit sparkrough limit spark..
02468
1012141618
-80 -60 -40 -20 0 20 40 60 80
Crank Angle (degrees)
Inst
anta
neou
s C
ompr
essi
on R
atio 8:1
12:116:1
Rough Limit Spark Occurs Here
Rough limit behavior depends on charge Rough limit behavior depends on charge density @ sparkdensity @ spark
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5 6 7 8Compressed NH3 Density @ Spark (kiloJoules/Liter)
Com
pres
sed
Gas
olin
e De
nsity
@ S
park
(kJ/
L)8:110:112:1
Ammonia has nearly neutral effect on flammability
At high load and low speed, rough limit is hard to find
The Knock Limit and Knock/Rough Limit The Knock Limit and Knock/Rough Limit Crossover at 12:1Crossover at 12:1
0102030405060708090
100
0 200 400 600 800 1000 1200 1400
IMEPn (kPa)
LHV
Bas
is (%
Gas
olin
e) 8:1
10:112:114:116:1R.L.
Throttled SuperchargedIdle
Charge density depends on load and Charge density depends on load and compression ratio at incipient knockcompression ratio at incipient knock..
02468
1012141618
-80 -60 -40 -20 0 20 40 60 80
Crank Angle (degrees)
Inst
anta
neou
s C
ompr
essi
on R
atio 8:1
12:116:1
Knock Occurs Here
20
22
24
26
28
30
32
34
36
38
0 200 400 600 800 1000 1200 1400
IMEPn (kPa)
Net
Indi
cate
d Th
erm
al E
ffici
ency
%
7:18:19:110:1
Power and Efficiency for GasolinePower and Efficiency for Gasoline
Throttled Supercharged
Idle
Decreasing C.R.
Increasing C.R.
Efficiency for NHEfficiency for NH33/Gasoline, Rough Limit/Gasoline, Rough Limit
20
22
24
26
28
30
32
34
36
38
0 200 400 600 800 1000 1200 1400
IMEPn (kPa)
Net I
ndic
ated
The
rmal
Effi
cien
cy (%
)
8:110:112:1
Throttled Supercharged
Idle
20
22
24
26
28
30
32
34
36
38
0 200 400 600 800 1000 1200 1400IMEPn (kPa)
Net
Indi
cate
d Th
erm
al E
ffici
ency
(%)
8:110:112:114:116:1
Efficiency for NHEfficiency for NH33/Gasoline, Knock Limit/Gasoline, Knock Limit
Throttled Supercharged
Idle
0
5
10
15
20
25
30
35
0 100 200 300 400 500 600 700 800 900 1000 1100
BMEP (kPa)
Bra
ke T
herm
al E
ffici
ency
(%),
1000
RPM
Gas/NH3, 8:1Gas/NH3, 10:1Gas/NH3, 12:1Gasoline, 7:1 to 10:1
Brake Thermal EfficiencyBrake Thermal Efficiency
Throttled Supercharged
Idle
EngineEngine--Out Out Pollutant Pollutant
EmissionsEmissions
0
3000
6000
9000
12000
15000
18000
21000
24000
0 20 40 60 80 100
Ammonia ppm wet
0
2000
4000
6000
8000
10000
0 20 40 60 80 100LHV basis (% Gasoline)
Eng
ine-
Out
Pol
luta
nt E
mis
sion
s Ammonia ppm wetNitric Oxide ppm wetCarbon Monoxide ppm wetHC dry ppm (C1)
Gasoline turned OFF
0
500
1000
1500
2000
2500
-1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Equivalence Ratio Deviation from Stoich. (%)
Post
Cat
Pol
luta
nts
(ppm
) for
Gas
olin
e
CO ppm wet
HC ppm dry C1
NH3 ppm wet
NO ppm wet
N20 ppm x10, wet
Post Catalyst Emissions, Gasoline OnlyPost Catalyst Emissions, Gasoline Only
RichLean
0
500
1000
1500
2000
2500
-1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Equivalence Ratio Deviation from Stoich. (%)
Post
Cat
Pol
luta
nts
(ppm
) for
1/4
Gas
olin
e, 3
/4
NH 3
CO ppm wet
HC ppm dry C1
NH3 ppm wet
NO ppm wet
N20 ppm x10, wet
Post Catalyst Emissions, Post Catalyst Emissions, ¼¼ Gas., Gas., ¾¾ NHNH33
RichLean
0
1000
2000
3000
4000
5000
6000
7000
8000
-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5
Equivalence Ratio Deviation from Stoich. (%)
Post
Cat
Em
issi
ons,
100
% N
H3
NH3 ppm wet
NO ppm wet
N20 ppm x10, wet
Post Catalyst Emissions, Ammonia OnlyPost Catalyst Emissions, Ammonia Only
RichLean
Operating ConclusionsOperating Conclusions
The effect of compression ratio on the fuel mix at the The effect of compression ratio on the fuel mix at the rough limit was weaker than expected. rough limit was weaker than expected. An efficiency improvement is obtained for a modestly An efficiency improvement is obtained for a modestly increased compression ratio of 10:1 or perhaps 12:1. increased compression ratio of 10:1 or perhaps 12:1. Knock and diminished return on efficiency make Knock and diminished return on efficiency make compression ratios above 12:1 undesirable. compression ratios above 12:1 undesirable. The improved efficiency of the ammonia fueled engine The improved efficiency of the ammonia fueled engine is due mostly to the effective removal of the knock is due mostly to the effective removal of the knock constraint at modest compression ratios, which allows constraint at modest compression ratios, which allows the engine to operate with better mechanical efficiency the engine to operate with better mechanical efficiency and reduced pumping losses at arbitrarily high loads.and reduced pumping losses at arbitrarily high loads.
Emissions ConclusionsEmissions Conclusions
Engine out emissions of hydrocarbons and carbon Engine out emissions of hydrocarbons and carbon monoxide are replaced with ammonia when ammonia is monoxide are replaced with ammonia when ammonia is substituted for gasoline.substituted for gasoline.Lean operation must be absolutely avoided with Lean operation must be absolutely avoided with ammonia, otherwise post catalyst emissions of nitrogen ammonia, otherwise post catalyst emissions of nitrogen oxides can exceed the engine out values. oxides can exceed the engine out values. Emissions clean up with a catalyst at stoichiometric, as Emissions clean up with a catalyst at stoichiometric, as they also do for gasoline.they also do for gasoline.
top related