Diesel HCCI Results at Caterpillar
Kevin Duffy, Jonathan KilkennyAndrew Kieser, Eric Fluga
DOE Contracts DE-FC05-00OR22806, DE-FC05-97OR22605
Contract Monitors – Roland Gravel, John Fairbanks
DEER ConferenceNewport, RI
August 27, 2003
Caterpillar Engine ResearchDiesel & Emissions Technology
Outline
n Review challengesn Development processn Recent progress
•Multi-cylinder engine•Operating range expansion• Advanced controls• Fuels effects
n Summaryn Future plans
Caterpillar Engine ResearchDiesel & Emissions Technology
n Proper air / fuel mixing
n Limited load range
n Combustion phasing and control
HCCI - The Challenge
HCCI Engine(Homogeneous ChargeCompression Ignition)
Low temperature combustionultra low emissions
Caterpillar Engine ResearchDiesel & Emissions Technology
SystemSimulation
CAT3DCombustion
Model
SprayVisualization
Design
Optical Engine
Single CylinderTesting
FEA
HCCI Development at Caterpillar
Multi Cylinder Testing
This project was undertaken pursuant to an agreement with theUnited States in connection with settlement of disputed claims in anenforcement action under the Clean Air Act
Caterpillar Engine ResearchDiesel & Emissions Technology
Ultra-Low Emissions
NOx (g/hphr)
Part
icul
ate
(g/h
phr)
0 0.5 1 1.5 2 2.5
0.025
0.05
0.075
0.1
2010 Regulations
2004 Regulations
Recent HCCI Results
Caterpillar Engine ResearchDiesel & Emissions Technology
n Proper air / fuel mixing
n Limited load range
n Combustion phasing and control
HCCI - The ChallengeHCCI Engine
(Homogeneous ChargeCompression Ignition)
Low temperature combustionultra low emissions
Caterpillar Engine ResearchDiesel & Emissions Technology
Mixture Preparation Optimization
HCCI Tip Progression
0
0.5
1
1.5
2
2.5
0 0.2 0.4 0.6 0.8 1
NOx (g/hp*hr)
Sm
oke
(A
VL
)
Tip 1
Tip 2
Tip 3
Additional 90% Smoke Reduction
Caterpillar Engine ResearchDiesel & Emissions Technology
Multi-Cylinder Engine Results
0
0.5
1
1.5
2
Main Timing
AV
L S
mo
ke
Tip A
Tip B
0
1000
2000
3000
4000
5000
Main Timing
HC
(pp
m)
Tip A
Tip B
0
2000
4000
6000
8000
10000
Main Timing
CO
(pp
m)
Tip A
Tip B
Main Timing
BS
FC
Tip A
Tip B
1200 RPM, ~1/4 Load @ <0.04 g/hphr NOx
Caterpillar Engine ResearchDiesel & Emissions Technology
n Proper air / fuel mixing
n Limited load range
n Combustion phasing and control
HCCI - The Challenge
HCCI Engine(Homogeneous ChargeCompression Ignition)
Low temperature combustionultra low emissions
Caterpillar Engine ResearchDiesel & Emissions Technology
Light Load HCCI Operation
n Dec and Sjoberg (2003) examined low load HCCI operationwith fully premixed iso-octane and a GDI system
n Found as load was reduced (phi<0.2), CO increased rapidlydue to bulk gas quenching, combustion efficiency decreasedto <50%
n Suggested there is a fundamental low load limit for HCCIdriven by these bulk gas quenching phenomena
Caterpillar Engine ResearchDiesel & Emissions Technology
HCCI Idle Operation
5.67.2IMEPcov
11401580HC (ppm)
386NOx (ppm)
36105358CO (ppm)
BL+5deg retardBLTiming
Caterpillar Engine ResearchDiesel & Emissions Technology
Expanding HCCI Load Range
0200400600800
100012001400160018002000
600 900 1200 1500 1800 2100Speed (rpm)
BM
EP
(kP
a)475 HP C15 Full Load Curve
Caterpillar Engine ResearchDiesel & Emissions Technology
n Proper air / fuel mixing
n Limited load range
n Combustion phasing and control
HCCI - The Challenge
HCCI Engine(Homogeneous ChargeCompression Ignition)
Low temperature combustionultra low emissions
Caterpillar Engine ResearchDiesel & Emissions Technology
Controlling Cylinder-to-Cylinder Variability
n Charge air temperature variability, outside cylinders get less“fresh” charge
n Intake valve actuation available on current ACERTTM engines
Back-flow During ValveTiming Strategies Fresh Charge
Inferred Temperature Distribution
Caterpillar Engine ResearchDiesel & Emissions Technology
Cylinder to Cylinder Balancing
n Intake valve actuator trim strategies used tophase combustion properlyn Allows for higher power levels to be achieved
Untrimmed Trimmed
Caterpillar Engine ResearchDiesel & Emissions Technology
Combustion Control – System Interaction
InjectionTiming
BoostPressure
VGTPosition
BackPressure
ManifoldTemp
CompressionRatio
A/F Ratio
BSFC
EmissionsCylinderPressure
Rise Rate
DesiredSpeed/Power
ExhaustTemperature
Heat Rejection
Caterpillar Engine ResearchDiesel & Emissions Technology
Controls Development Process
0
0.5
1
1.5
2
2.5
3
-2 0 2 4 6 8 10
BSNOx (g/hphr)
AV
L S
mo
ke
1200 rpm
1500 rpm
1800 rpm
1500 rpm, 1/4 load
0
50
100
150
200
250
-20 -15 -10 -5 0 5 10 15 20Crank Angle (Deg)
Hea
t R
elea
se R
ate
Performance/Emissions Data
In-Cylinder Pressure Data
Neural Network “learns” the interactions
Engine Settings
Rapid Prototype Controller
Optimum SettingsSensors
Trai
ning
Dat
a fo
r N
eura
l Net
wor
k
Actuators
Injection Timing
Boost Pressure
VGT Position
Back Pressure
Manifold Temp
Compression Ratio
A/F Ratio
BSFC
EmissionsCylinder Pressure
Rise Rate
Desired Speed/ Power
Exhaust Temperature
Heat Rejection Injection Timing
Boost Pressure
VGT Position
Back Pressure
Manifold Temp
Compression Ratio
A/F Ratio
BSFC
EmissionsCylinder Pressure
Rise Rate
Desired Speed/ Power
Exhaust Temperature
Heat Rejection
Caterpillar Engine ResearchDiesel & Emissions Technology
Sample Neural Net ModelsPmax from EC parameters
CO from ICP+EC parameters PM from ICP+EC parameters
NOx from ICP
Caterpillar Engine ResearchDiesel & Emissions Technology
Two-Stage Combustion with Diesel Fuel
Rate of cool flame chemistry varies with load. Inductiontime affected by residual content, IVA, boost, etc.
Amount of cool flame activity affects main combustiontiming and rise rate.
Question: Can fuel properties be manipulated in such amanner to advantageously effect cool flame chemistry
and combustion phasing?
Caterpillar Engine ResearchDiesel & Emissions Technology
Study Fuels Effects on HCCI Combustion
n Teamed with major oil industry partnern Developed matrix of 12 fuels
• Diesel and gasoline like fuels• Vary ignition quality and volatility• In stock or easily blended fuels
n Test in single cylinder (~1 wk/fuel)n Preliminary (CAT only in-house) results presented
here for high and low cetane # fuels
Caterpillar Engine ResearchDiesel & Emissions Technology
Effect of Cetane Number
Higher CN leads to:-earlier cool flame and main ignition-40% increase in peak cylinder pres-2x increase in cyl pres rise rate
1200 rpm, ~1/4 load, equal fuel mass, timing=NOx takeoff
0
2
4
6
8
10
12
14
16
-50 -40 -30 -20 -10 0 10 20 30 40 50
CAD
PC
YL
(MP
a)
0
50
100
150
200
250
300
Hea
t Rel
ease
(kJ/
m3)
Higher CNLower CN
1200 rpm, ~1/4 load, equal fuel mass, advanced timing
0
2
4
6
8
10
12
14
16
-50 -40 -30 -20 -10 0 10 20 30 40 50
CAD
PC
YL
(M
Pa)
0
50
100
150
200
250
300
Hea
t Rel
ease
(kJ/
m3)
Higher CNLower CN
Caterpillar Engine ResearchDiesel & Emissions Technology
1200 rpm, ~1/4 load
-0.1-0.05
00.05
0.1
0.15
0.20.25
0.30.35
0.40.45
40 50 60 70 80 90Injection Timing (deg btdc)
BS
NO
x (g
/hph
r)
Higher CNLower CN
Emissions and BSFC Impact
Timing Retard
AVL smoke < 0.05 all points
1200 rpm, ~1/4 load
270
280
290
300
310
320
330
340
350
360
40 50 60 70 80 90Injection Timing (deg btdc)
BS
FC
(g/k
Wh
r)
Higher CNLower CN
Timing Retard
0
0.2
Caterpillar Engine ResearchDiesel & Emissions Technology
Highly Competitive BSFC
235
250
265
280
295
310
325
340
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6NOx (g/hp-hr)
2003 ACERT2007 Demo2010 HCCI
BS
FC
(g/k
W-h
r)
220
230
240
250
260
270
280
290
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0NOx (g/hp-hr)
2003 ACERT2007 Demo2010 HCCI
BS
FC
(g/k
W-h
r)
Caterpillar Engine ResearchDiesel & Emissions Technology
Conclusionsn HCCI demonstrated up to 1600 bar BMEP
• Single and multi-cylinder engines running• Highly competitive thermal efficiencies
n Stable HCCI combustion obtained at idle, light load conditionsn Meeting controls issue on all fronts
• Full control system characterization under development usingneural network models with in-cylinder pressure sensing
• Cylinder variability observed, VVT appears to be viabletrimming mechanism
n Fuels effects (CN) can have significant impact onperformance/emissions, higher CN not right direction
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