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The Path to a 50% Thermal Efficient Engine
W. L. Easley, A. Kapic, and D. M. Milam
DOE Contract DE-FC05-00OR22806Team Leader: Gurpreet Singh Prog. Mgr.: Roland GravelTech. Mgr.: Carl Maronde
August 23, 2005DEER Conference
2U.S. DOE
Outline
• Objectives
• First Law Analysis of Fuel Energy Distribution
• Review of Analysis for 45% Brake Thermal Efficiency at 2007 Emissions Levels
• 50% Brake Thermal Efficiency at 2010 Emissions Levels
• Summary and Conclusions
3U.S. DOE
Does improvement in fuel economy offset the cost and maintain durability?
• Diesel fueled engine capable of – 2010 emissions levels (0.20 g/hp-hr NOx, 0.01 g/hp-hr PM)– 50% thermal efficiency– >500,000 miles with only minor maintenance– Package must fit within class 8 truck
DOE HTCD Program Objectives
High Efficiency Building Blocks
Test Hardware Calibrate Models System Simulation
“Real” World BenefitSimulation
Results of Past Research
• Program Phasing– Phase 1: Analytical validation of 45% thermal efficiency at 2007 OHT emissions levels– Phase 2: System simulation of 50% thermal efficiency at 2010 OHT emissions levels
with focused component testing
4U.S. DOE
Control Volumes for First Law Analysis
Fuel Energy
Cylinder Heat Rej.
Indicated Power
Exhaust Energy
Reciprocator
CGI Heat Rejection
Engine System
FuelEnergy
Engine Heat Rejection
ExhaustEnergy
ATAAC Heat Rejection
Brake Power
Exhaust Energy
Fuel Energy
Eng. Heat Rej.
Aero Drag
Rolling Res.Drivetrain
Fan
Accessories
Excess Power
On-Highway Truck
ATAAC Heat Rej.
CGI Heat Rej.
5U.S. DOE
0
200
400
600
800
Fuel
Ene
rgy
(kW
)First Law Analysis
• 45% Thermal Efficient Engine (class VIII truck, 1200 RPM, peak torque, fully loaded, 70 MPH)
On-Highway Truck
Excess Power (65.2 kW; 9.3 %)
Exhaust Power(160 kW; 22.9 %)
Engine Heat Rej.(73.7 kW; 10.5 %)
ATAAC Heat Rej.(103.7 kW; 14.8 %)
Aerodynamic Drag(171.7 kW; 24.6 %)
Rolling Res. (45.9 kW; 6.6 %)
CGIC HR (34.8 kW; 5.0 %)
Reciprocator
Exhaust Power(302.3 kW; 43.2 %)
Heat Loss (58.9 kW; 8.4 %)
Indicated Power(327.0 kW; 46.8 %)
Pumping Power(11.0 kW; 1.6 %)
Engine System
ATAAC Heat Rej.(103.7 kW; 14.8 %)
Engine Heat Rej.(73.7 kW; 10.5 %)
Exhaust Power(160.0 kW; 22.9 %)
Brake Power(315 kW; 45 %)
CGIC HR (34.8 kW; 5.0 %)
Friction Power(12.0 kW; 1.7 %)
6U.S. DOE
0
200
400
600
800
Fuel
Ene
rgy
(kW
)First Law Analysis
• 45% Thermal Efficient Engine (class VIII truck, 1200 RPM, peak torque, fully loaded, 70 MPH)
On-Highway Truck
Excess Power (65.2 kW; 9.3 %)
Exhaust Power(160 kW; 22.9 %)
Engine Heat Rej.(73.7 kW; 10.5 %)
ATAAC Heat Rej.(103.7 kW; 14.8 %)
Aerodynamic Drag(171.7 kW; 24.6 %)
Rolling Res. (45.9 kW; 6.6 %)
CGIC HR (34.8 kW; 5.0 %)
Reciprocator
Exhaust Power(302.3 kW; 43.2 %)
Heat Loss (58.9 kW; 8.4 %)
Indicated Power(327.0 kW; 46.8 %)
Pumping Power(11.0 kW; 1.6 %)
Engine System
ATAAC Heat Rej.(103.7 kW; 14.8 %)
Engine Heat Rej.(73.7 kW; 10.5 %)
Exhaust Power(160.0 kW; 22.9 %)
Brake Power(315 kW; 45 %)
CGIC HR (34.8 kW; 5.0 %)
Friction Power(12.0 kW; 1.7 %)
Accessories (6.2 kW; 0.9%)
Fan (11.0 kW; 1.6%)
Drivetrain (15.0 kW; 2.1%)
7U.S. DOE
Phase 1: 2007 45% Thermal Efficiency
Improved Port Design
High Efficiency Air SystemReduced PRL Friction
High Efficiency Compact Cooling
System
Combustion System
Optimization
2007 Capable System at 45%
Thermal Efficiency
8U.S. DOE
Phase 2: 2010 50% Thermal Efficiency
Reduced Heat RejectionTurbo-Compound
NOxReduction
Combustion System Optimization
Improved Air System
2007 Capable System at 45%
Thermal Efficiency
9U.S. DOE
Phase 2: 2010 50% Thermal Efficiency
Reduced Heat RejectionTurbo-Compound
NOxReduction
Improved Air System
Combustion System Optimization
2007 Capable System at 45%
Thermal Efficiency
10U.S. DOE
NOx Reduction
• Industry is investigating several technologies for achieving 2010 system-out NOx levels– HCCI– High diluent
concentration– Urea SCR– NOx Adsorber
• For engine systems employing aftertreatment, engine-out emissions level is determined by conversion efficiency
0.00.51.01.52.02.53.03.54.04.55.0
80 85 90 95 100NOx Aftertreatment Conversion Efficiency (%)
Engi
ne-O
ut N
Ox
(g/h
p-hr
) 1998 Emissions Levels
2004 Emissions Levels
2007 Emissions
Levels
Assuming 0.2 g/hp-hr System-Out NOx
• Conversion efficiencies above 90% possible
11U.S. DOE
-5-4-3-2-1012345
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
NOx (g/hp-hr)
Ope
ratin
g C
ost I
ncre
ase
(%)
• Conversion of NOx requires additional operating cost in the form of urea, fuel for richening the exhaust stream, etc.
• At high conversion efficiencies system optimization more than compensates for operating cost penalty
NOx Reduction
Engine-Out Trade-Off
Curve89% Conversion
83% Conversion
2007 Engine Baseline
12U.S. DOE
BaselineNOx
Reduction
0
200
400
600
800
Fuel
Ene
rgy
(kW
)
ATAACHeat Rej.
EngineHeat Rej.
ExhaustPower
CGIC HR
Friction Power
699.2 kW45.0%
697.0 kW45.2%
BrakePower
Fuel Energy Distribution
• Production Challenges– long term degradation– replenishment of reductant– low temperature operation– packaging– cost
Thermal Efficiency Increase to: 45.2 %
NOx (g/hp-hr)
PM
(g/
hp-
hr)
0.2 1.2System-Out Emissions
13U.S. DOE
Phase 2: 2010 50% Thermal Efficiency
Reduced Heat RejectionTurbo-Compound
Improved Air System
NOxReduction
Combustion System Optimization
2007 Capable System at 45%
Thermal Efficiency
14U.S. DOE
Improved Air System
• Series turbochargers must be used in order to provide the optimum boost levels
• High efficiency compressor, turbine, and bearing designs continue to improve air system component efficiencies
• Intercooling can further improve the efficiency of the system
43
44
45
46
47
48
49
65 70 75 80 85 90 95 100 105ηcomponents (%)
Ther
mal
Effi
cien
cy (%
)
ATAAC w/ 35 C outlet temp.
ATAAC plus ATAIC w/ 35 Coutlet temp.
Syst
em T
her
mal
Eff
icie
ncy
(%
) Demonstrated on LE55 Engine
In Production (used for 45%)
15U.S. DOE
0
200
400
600
800
Fuel
Ene
rgy
(kW
)
ATAACHeat Rej.
EngineHeat Rej.
ExhaustPower
670.6 kW47.0%
CGIC HR
Friction Power
699.2 kW45.0% 697.0 kW
45.2%
BrakePower
ATAIC Heat Rej.
Fuel Energy Distribution
BaselineNOx
ReductionImproved Air System
Thermal Efficiency Increase to: 47.0 %
43
44
45
46
47
48
49
65 70 75 80 85 90 95 100 105ηcomponents (%)
Ther
mal
Effi
cien
cy (%
)
ATAAC w/ 35 C outlet temp.
ATAAC plus ATAIC w/ 35 Coutlet temp.
• Production Challenges:– packaging– cost– map width
Sys
tem
Th
erm
al E
ffic
ien
cy (
%)
16U.S. DOE
Phase 2: 2010 50% Thermal Efficiency
Reduced Heat RejectionTurbo-Compound
Improved Air System
NOxReduction
Combustion System Optimization
2007 Capable System at 45%
Thermal Efficiency
17U.S. DOE
46.0
46.5
47.0
47.5
48.0
165 170 175 180Total Heat Rejection (kW)
Syst
em T
herm
al E
ffici
ency
(%)
24.0
24.5
25.0
25.5
26.0
Exhaust Energy (%)
Thermal EfficiencyExhaust Energy
Reduced Heat Rejection
• Reducing heat rejection:– low thermal conductivity
components, coatings, or designs– selective cooling– higher coolant temperatures
• Reduced heat rejection increases exhaust energy more than thermal efficiency
Low Heat Rejection Components from ICC Program
• 3.5 mm TBC on Piston• 2.5 mm TBC on Head• 18% Increase in Oil and
Coolant Temperatures
18U.S. DOE
Fuel Energy Distribution
• Production Challenges:– durability– cost
BaselineNOx
AdsorberImproved Air System
Reduced Heat
Rejection
0
200
400
600
800
Fuel
Ene
rgy
(kW
)
ATAACHeat Rej.
EngineHeat Rej.
ExhaustPower
666.5 kW47.3%
670.6 kW47.0%
CGIC HR
Friction Power
699.2 kW45.0%
697.0 kW45.2%
BrakePower
ATAIC Heat Rej.
Thermal Efficiency Increase to: 47.3%
19U.S. DOE
Phase 2: 2010 50% Thermal Efficiency
Reduced Heat RejectionTurbo-Compound
Improved Air System
NOxReduction
Combustion System Optimization
2007 Capable System at 45%
Thermal Efficiency
20U.S. DOE
Turbo-Compound
• Turbo-compound consists of:– power turbine– power transfer to drive
train– spring or fluid coupling
Turbo-Compound on LBSFC Engine
• Production Challenges:– packaging– cost– operating range
47
48
49
0 10 20 30 40Turbo Compound Power (kW)
Syst
em T
herm
al E
ffici
ency
(%)
275
280
285
290
295
300
305
310
315
320
Power (kW
)
System Thermal EfficiencyReciprocator PowerSystem Power
21U.S. DOE
0
200
400
600
800
Fuel
Ene
rgy
(kW
)
ATAACHeat Rej.
EngineHeat Rej.
ExhaustPower
666.5 kW47.3%
670.6 kW47.0%
CGIC HR
Friction Power
653.3 kW48.2%
699.2 kW45.0%
697.0 kW45.2%
BrakePower
ATAIC Heat Rej.
Fuel Energy Distribution
BaselineNOx
AdsorberImproved Air System
Reduced Heat
RejectionTurbo
Compound
Thermal Efficiency Increase to: 48.2%
22U.S. DOE
Phase 2: 2010 50% Thermal Efficiency
Reduced Heat RejectionTurbo-Compound
Improved Air System
NOxReduction
Combustion System Optimization
2007 Capable System at 45%
Thermal Efficiency
23U.S. DOE
47
48
49
50
51
15 16 17 18 19 20 21 22 23 24 25Peak cylinder pressure (MPa)
Syst
em T
herm
al E
ffici
ency
(%)
47
48
49
50
51
15 16 17 18 19 20 21 22 23 24 25 26 27Compression Ratio (-)
Syst
em T
herm
al E
ffici
ency
(%)
System Optimization
• Optimize system operation for peak efficiency– peak cylinder pressure– compression ratio
Production Range
Production Range
Used for 45%
22 MPa PCP Limit
Curve for rc = 22:1
24U.S. DOE
49
50
51
-120 -110 -100 -90 -80 -70 -60 -50Intake Valve Closing (DATDC)
Syst
em T
herm
al E
ffici
ency
(%)
System Optimization
• Optimize system operation for peak efficiency– intake valve actuation– air system sizing for proper boost level
Typical IVC is -140 to -120
49
50
51
20 21 22 23 24 25 26 27 28 29Air Fuel Ratio (-)
Syst
em T
herm
al E
ff. (%
)
280
300
320
340
360
380
Int. Man. Pressure (kPa)
Thermal EfficiencyInt. Man. Pressure
-400 -350 -300 -250 -200 -150 -100
Crank Position (DATDC)
Valv
e Li
ft (-)
25U.S. DOE0
200
400
600
800
Fuel
Ene
rgy
(kW
)
ATAACHeat Rej.
EngineHeat Rej.
ExhaustPower
666.5 kW47.3%
670.6 kW47.0%
CGIC HR
Friction Power
653.3 kW48.2%
699.2 kW45.0%
697.0 kW45.2%
625.3 kW50.5%
BrakePower
ATAIC Heat Rej.
Fuel Energy Distribution
BaselineNOx
AdsorberImproved Air System
Reduced Heat
RejectionTurbo
Compound
Combustion System
Optimization
Thermal Efficiency Increase to: 50.5%
26U.S. DOE
Phase 2: 2010 50% Thermal Efficiency
Reduced Heat RejectionTurbo-Compound
Improved Air System
NOxReduction
Combustion System Optimization
2010 Capable System at 50%
Thermal Efficiency
27U.S. DOE
Summary and Conclusions
• Conducted first law analysis of fuel energy distribution
• Reviewed path to a 45% thermal efficient engine that meets 2007 emissions levels
• Identified path to 50% thermal efficiency while meeting 2010 emissions levels
• Discussed challenges to high efficiency components going into production
• Focused testing of high efficiency components continues through this final phase of our cooperative research program
28U.S. DOE
EGR vs. CGI
Clean Gas InductionClean Gas Induction
Particulate Trap
PM, NOx, CO, HC
Diesel Particulate Filter / Muffler
CGI
PM, NOx,
CO, HC
PM, NOx,
CO, HC
EGR NOx Solution
PM, NOx,
CO, HC
PM, NOx,
CO, HC
Oxidation Catalyst (“Oxicats”) Particulate Trap
PM, NOx, CO, HC
Diesel Particulate Filter / MufflerEGR
NOx , H2O, CO2
PM, NOx,
CO, HC
PM, NOx,
CO, HC
NOx , H2O, CO2
NOx , H2O, CO2