the path to a 50% thermal efficient engine

1

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




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 %)



Aerodynamic Drag(171.7 kW; 24.6 %)

Rolling Res. (45.9 kW; 6.6 %)

CGIC HR (34.8 kW; 5.0 %)

Reciprocator


Heat Loss (58.9 kW; 8.4 %)

Indicated Power(327.0 kW; 46.8 %)

Pumping Power(11.0 kW; 1.6 %)

Engine System




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


Reduced Heat RejectionTurbo-Compound

NOxReduction

Combustion System Optimization

Improved Air System


Thermal Efficiency

9U.S. DOE



NOxReduction

Improved Air System



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



Improved Air System

NOxReduction



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.


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



Improved Air System

NOxReduction



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


• 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



Improved Air System

NOxReduction



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.


BaselineNOx


Reduced Heat

RejectionTurbo

Compound


22U.S. DOE



Improved Air System

NOxReduction



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.


BaselineNOx


Reduced Heat

RejectionTurbo

Compound

Combustion System

Optimization


26U.S. DOE



Improved Air System

NOxReduction



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

the path to a 50% thermal efficient engine

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