combustion phasing in dmecombustion phasing in dme-fuelled hcci...
TRANSCRIPT
2006 Asian DME conference
Engine Lab.
Combustion Phasing in DME fuelledCombustion Phasing in DME-fuelled HCCI Engine
Kitae Yeom, Hyeonsook Yoon and Choongsik BaeDepartment of Mechanical Engineering, KAIST
Combustion Engineering Research Center
ContentsEngine Lab.
Backgrounds
DME HCCI test with high CR (based on CI engine)DME HCCI test with high CR (based on CI engine)
Experimental results
DME HCCI test with low CR (based on SI engine)
Experimental resultsp
Conclusions
BackgroundsEngine Lab.
Homogeneous Charge Compression Ignition
Homogeneous Compression +Charge (SI engine) Ignition (CI engine)+
Homogeneous ChargeHomogeneous Charge Compression Ignition
(HCCI engine)
BackgroundsEngine Lab.
Problems of HCCI Engine
Problems
High Load• Early combustion
Combustion h
y o o
• Heavy knocking
• IMEP loss
phase controlIMEP loss
EGR, additivesEGR, additives and etc.
Research topics of KAIST DME HCCIEngine Lab.
Neat DME HCCI combustionDME HCCI combustion with LPG
DME HCCI combustion with gasolineDME HCCI combustion with hydrogen
DME HCCI b ti i PFIDME HCCI combustion using PFI
EGR rateIntake valve timing
Fuel quantityInjection timingFuel pressure
Establish the DME HCCI engine combustion D/BEstablish the DME HCCI engine combustion D/B
Engine Lab.
DME HCCI test with hi h CRhigh CR
(based on CI engine)(based on CI engine)
Experimental SetupEngine Lab.
Engine TypeEngine Type Single Cylinder, DISingle Cylinder, DI--diesel basediesel baseg ypg yp diesel basediesel base
Bore x Stroke Bore x Stroke 83 x 92 mm83 x 92 mm
VolumeVolume 498cc498cc
Compression Compression ratioratio 18.718.7
I j tI j tøø0.168mm*5holes 0.168mm*5holes
minimini sac typesac typeInjectorInjector minimini--sac typesac type(150(150°°, 100, 100°°))
DME HCCIEngine Lab.
4.0
2 5
3.0
3.5
800rpm 1200rpmMixing controlled combustion
region
1.5
2.0
2.5
IMEP
[ba
r]Homogeneous charge compression ignition region
0.0
0.5
1.0Stratified charge compression ignition region
0 50 100 150 200 250 300
SOI [CA BTDC]SCCI region can improve the IMEP with late combustion
Injection pressure 55 MPaInjection pressure 55 MPa
Engine speed 800, 1200 rpm
λDME 3
DME HCCI with hydrogenEngine Lab.
6080
[b
ar]
motoring RH2= 0% RH2= 5% RH2= 10%
AD
]
Low temperature oxidation
H + O → O + OH
Engine speed : 800 rpm, Tin : 30 ℃
0204060
80
er P
ress
ure[ RH2= 15%
RH2= 20% RH2= 25%
e ra
te[J
/CA H + O2→ O + OH
O + H2→ H + OH
020406080
Incy
linde
Hea
t rel
ease
H2 +OH → H2O +HCH3OCH3 + OH → CH3OCH2 + H2O
320 340 360 380 400 420
H
Crank angle degree[CAD]
Controlled the H dH d3.2
Controlled the ignition timing By HydrogenHydrogen
2 8
3.0
EP
[bar
]
hydrogen
2.6
2.8 IME hydrogen
combustion phase control
0 5 10 15 20 252.4
Fraction rates of hydrogen[%] IMEP increase
p
Engine Lab.
DME HCCI test with l CRlow CR
(based on SI engine)(based on SI engine)
Experimental SetupEngine Lab.
Engine Specification
Type Descriptions
Number of Cylinder 1
Displacement cc 494Displacement, cc 494
Bore, mm 82
Stroke, mm 93.5
Compression ratio 13
Intake duration 228
Exhaust duration 228Exhaust duration 228
DME injection pressure, MPa 5
I j t t Slit i j tInjector type Slit injector
Valve
Retard Advance
IVO, ATDC 11 -29Timing IVC, ABDC 59 19
DME HCCI using Direct InjectionEngine Lab.
5.0
5.5
6.0
MP
a]
Injection timing 22 CAD ATDC122 CAD ATDC No cool flame at 322 CAD ATDC
2.5
3.0
3.5
4.0
4.5
ion
Pre
ssu
re [
M 122 CAD ATDC 222 CAD ATDC 322 CAD ATDC
Mixing controlled combustion
300 310 320 330 340 350 360 370 380 390 4000.0
0.5
1.0
1.5
2.0
IVO timing was fixed at 11 CAD ATDC
Com
bust
i
1000 rpm, λDME=3
Mixing controlled combustion
300 310 320 330 340 350 360 370 380 390 400
Crank angle degree
6.0
Combustion retardation due to lower volumetric efficiency and
3.5
4.0
4.5
5.0
5.5 IVO timing -29 CAD ATDC -19 CAD ATDC -9 CAD ATDC 1 CAD ATDC11 CAD ATDCsu
re [
MP
a]
yinternal residual gas
IVO timings Volumetric efficiency
1.0
1.5
2.0
2.5
3.0
ombu
stio
n P
ress
-29 CAD 80.0%
-19 CAD 79.5%
-9 CAD 77.2%
decrease
300 310 320 330 340 350 360 370 380 390 4000.0
0.5Injection timing was fixed at 122 CAD ATDC
Crank angle degree
Co
1 CAD 70.8%
11 CAD 66.2%
e
Gasoline – DME HCCI combustionEngine Lab.
7
8
]
λTOTAL
IVO timing -29 ATDC
7
8
IVO timing ATDC λTOTAL
=2.12
300
350
400
2
3
4
5
6
e [
J/0
.17
6 C
AD
]
ress
ure
[M
Pa] 2.91
2.77 2.57 2.41 2.12
300
350
400
3
4
5
6
7 IVO timing, ATDC -29 -19 -9 1 11
[J/0
.17
6 C
AD
]
ssu
re [
MP
a]
TOTAL
50
100
150
200
250
0
1
2
eat
rele
ase
rate
Incy
linde
r pr
100
150
200
250
300
0
1
2
at r
elea
se r
ate
Incy
linde
r pr
es
300 310 320 330 340 350 360 370 380 390 4000
50
He
Crank angle degree [CAD]300 310 320 330 340 350 360 370 380 390 400
0
50 Hea
Crank angle degree [CAD]
Start of combustion timing was not changed due to same injection
quantity of DME
Combustion retardation due to reduced volumetric efficiency and
internal residual gas
Due to increased injection quantity of gasoline
Engine speed, rpm 1000
DME injection timing [ATDC] 110of gasoline [ATDC] 110
λDME 3.7
DME – LPG HCCI combustionEngine Lab.
7
8
λTOTAL
IVO timing -29 ATDC
7
8
]λTOTAL
=2.12IVO timing, ATDC
300
350
400
2
3
4
5
6
essu
re [
MP
a]
[J/
0.1
76
CA
D]TOTAL
2.91 2.77 2.57 2.41 2.12
300
350
400
2
3
4
5
6
ress
ure
[M
Pa]
[J/
0.1
76
CA
D]TOTAL -29
-19 -9 1 11
50
100
150
200
250
0
1
2
Incy
linde
r pr
e
eat
rele
ase
rate
50
100
150
200
250
0
1
2
Incy
linde
r pr
eat
rele
ase
rate
More retarded than gasoline-DME
300 310 320 330 340 350 360 370 380 390 4000
50
He
Crank angle degree [CAD]
300 310 320 330 340 350 360 370 380 390 4000
50
Crank angle degree [CAD]
He
gHCCI due to higher latent heat of
vaporization and octane number of LPG
Start of combustion timing was retarded due to increased injection
quantity of LPG
Due to increased injection quantity of LPG
Engine speed, rpm 1000
DME injection timing [ATDC] 110of LPG [ATDC] 110
λDME 3.7
IMEP of HCCI with LPG and gasoline
Engine Lab.
2 9
IMEP in Gasoline HCCI [bar]2 9
IMEP in LPG HCCI [bar]
2.3
2.4
2 52.7
2.8
2.9
2.902.852.802.752.702.652 60
2.3
2.4
2.7
2.8
2.9
3.73.63.53.43.33.22.5
2.6
2.7
2 8Lam
bda
tota
l
2.5
2.6
2.602.552.502.452.402.352.302.25
2.5
2.6
2.7
Lam
bda
tota
l
2.5
2.63.13.02.92.82.72.62.52.42.8
2.72.6
2.5
2.4
2 3
L
2.2
2.3
2.4 2.20 2.8
2.9
3 1
L
2.2
2.3
2.4 2.32.2
2.3
IVO timing-20 -10 0 10
Maximum IMEP region
3 3.1 3.2 3.3 3.4 3.5 3.6
IVO timing-20 -10 0 10
a u eg o
IMEP was decreased due to early b ti
Engine speed, rpm 1000
DME injection timing [ATDC] 110combustion [ATDC] 110
λDME 3.7
DME HCCI with hydrogenEngine Lab.
506070
re[b
ar] Inj.Timing BTDC300°
0% H2 add10%H2add
1500RPM
Fraction rates of hydrogen
01020304050
ylin
der P
ress
ur 10% H2 add 20% H2 add 30% H2 add 40% H2 add
Fraction rates of hydrogen
Retarded the combustion phase320 340 360 380 400 420 440
-100C
Ignition delay was increased asIMEP increase
Retarded the combustion phase
Ignition delay was increased as hydrogen fraction was increased
Knocking was observed
3.5
4.0
800rpm 1000rpm 1500rpm
g
1.0
1.5
2.0
2.5
3.0
IME
P[b
ar]
Incomplete combustion
0 10 20 30 400.0
0.5
R ate o f add ing H ydrogen[% ]
DME HCCI using PFIEngine Lab.
346.4
CA
D) IVO timing
1 CAD ATDC
344.0
344.8
345.6
λ = 2.5Star
t of
-ign
itio
n (C
2.0
- 19 CAD ATDC - 29 CAD ATDC
ar)
0 10 20 30 40 50 60343.2 1000 rpm
EGR rate (%)
auto
-
1.6
1.8
λ = 2.5
EPgr
oss (
ba
0 10 20 30 40 50 60
6
EGR rate (%)
IME
2.5 CAD retardation
• IVO timing
increased internal residual gas fraction
• 0.5 bar IMEP gain
EGR + IVO timing
• EGR
Dilution effects
• IMEP was increased due to late ignition as a results of EGR rate
ConclusionsEngine Lab.
DME HCCI combustion was tested to verify the combustion phase characteristics.
F ll i l i d f i tFollowing conclusions were drawn from experiments.
1. The reduced IMEP was observed due to negative work.
2. The addition of hydrogen was an effective way of phase control.y g y p
3. The combustion phase could be controlled by varying intake valve timing.
4. EGR can retard the combustion phase of DME HCCI engine.
This research is supported by CERC (Combustion Engineering Research Center), KAIST