High-Efficiency, Ultra-Low Emission Combustion in … · High-Efficiency, Ultra-Low Emission Combustion in a Heavy-Duty Engine via Fuel Reactivity Control Rolf D. Reitz, Reed Hanson,

1

High-Efficiency, Ultra-Low Emission Combustion in a Heavy-Duty Engine via Fuel Reactivity Control

Rolf D. Reitz,Reed Hanson, Derek Splitter, Sage Kokjohn

Engine Research CenterUniversity of Wisconsin-Madison

http://reitz.me.wisc.edu

15th Diesel Engine-Efficiency and Emissions Research Conference August 3rd, 2009

Acknowledgements:Department of Energy/Sandia National Laboratory

• Contract DEFC26-06NT42628

Diesel Emission Reduction Consortium

UNIVERSITY OF WISCONSIN -

ENGINE RESEARCH CENTER

2

Outline

•

Motivation

•

Experimental Results–

Gasoline PPC

•

CFD Modeling –

Fuel reactivity

•


Dual-fuel PCCI

•

Conclusions



3

Motivation

• Emissions regulationsEPA 2010 on-highway HDEuro 5,6

LTC (MK,PCCI,HCCI, etc.)Advantages

Low NOx and PM emissionsHigh thermal efficiency

DisadvantagesLoad limits from high PRR No direct control of combustion timing

PPC

–

“hybrid”

between HCCI and diesel LTCKalghatgi

“Mixed enough”

combustion

• Concern for improved fuel efficiency –

GHG, economy

Park & Reitz, CST, 2007Low emissions window

4

Motivation

Partially Premixed Combustion–

Increase ignition delay to add mixing time

2 ways to achieve PPC

•

High EGR rates–

Reduce PM formation with low combustion temperatures

(Akihama SAE 2001-01-0655)•

Fuels–

Use low CN fuels and EGR to add ignition delay

(Kalghatgi

SAE 2007-01-0006)

–

Optimize fuel reactivity

(Bessonette SAE 2007-01-0191)

5

Engine heavy-duty, flat cylinder head, shallow bowl

Bore x Stroke [mm] 127 x 154Compression ratio 14.0

Diesel injector

Number of holes, diameter [m]

8, 200

Operating conditionsEngine speed [rpm] 1200

Swirl ratio 2.4

Intake temperature [C], Pressure [bar]

40, 2.0

Oxygen fraction @ IVC/EGR [%] 15.8/25

Pilot split ratio [%] 30

Kalghatgi: SAE Paper 2007-01-0006

Diesel vs. gasoline compression ignition

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 100 120 140 160

crank angle [deg atdc]

mor

mal

ized

inje

ctio

n ve

loci

ty

Injection profile

30%70%

6

Numerical models

Single Zone SimulationsSENKIN engine codeERC reduced PRF mechanism

41 species, 130 reactions –

Ra & Reitz CNF, 2008

Multi-Dimensional ModelingKIVA-3V code coupled with CHEMKIN IIRNG k-ε

turbulence model

KH-RT drop break up model Grid-independent spray modelsDrop collision and coalescenceERC reduced PRF mechanism

KIVA Modeling -

Ra, Yun, Reitz Int. J. Vehicle Design 2009

7

Start of injection: -137 and -6 (diesel), -9 (gasoline) deg atdc. -

Measured (Kalghatgi et al. SAE 2007)Model: ERC KIVA-CHEMKIN w/ PRF mechanism

Diesel vs. gasoline -

double injection

0

2

4

6

8

10

12

-50 -40 -30 -20 -10 0 10 20 30 40 50


pres

sure

[MPa

]-100

100

300

500

700

900

1100

HR

R [J

/deg

]

P, ExpP, CalHRR, ExpHRR, Cal

inj

Gasoline

0

2

4

6

8

10

12

-50 -40 -30 -20 -10 0 10 20 30 40 50


pres

sure

[MP

a]

-50

50

150

250

350

450

550

HR

R [J

/deg

]

P, ExpP, CalHRR, ExpHRR, Cal

inj

Diesel

Pre

ssu

re (

MP

a)

8

CA= tdc

CA= +4

CA= +6

CA= +12

Diesel SOI = -2

CA= -8

CA= tdc

CA= +10

Gasoline SOI = -11

CA= +12


ignition delay

9


emissions

Additional time for mixing of gasoline offers benefits for CIDI engines!

0

0.05

0.1

0.15

0.2

0.25

0.3

-30 -20 -10 0 10 20start of main injection

calc

ulat

ed s

oot [

g/kg

-f]

0

2

4

6

8

10

12

14

16

18

AVL

sm

oke

opac

ity [%

]

Gasoline, calDiesel, calGasoline, expDiesel, exp

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

-30 -20 -10 0 10 20start of main injection [deg atdc]

NO

x [g

/kg-

f]

Gasoline, calGasoline, expDiesel, calDiesel, exp

diesel

gasoline

Soot

NOx

10

Outline

•

Motivation

•


Gasoline PPC

•

CFD Modeling –

Fuel reactivity

•


Dual-fuel PCCI

•

Conclusions



11

ERC Caterpillar engine lab 3401E SCOTE

Displacement (l) 2.44

Geometric Comp. Ratio 16:1Bore (mm) 137Stroke (mm) 165

Number of Valves 4IVC (BTDC modified cam) 85/143Effective Comp. Ratio ~12-16

Swirl Ratio (stock) 0.7Piston Bowl Geometry Stock

Injection systems:Cat HEUI 315B, Bosch Gen 2 Common Rail1500 bar, 0.25 mm 6-hole

12

Gasoline experimental conditions

Double injection• A50

– EGR• Low Load (A25)

Single Injection

• A50 with 40% EGR

FTP Cycle Point A50 A25Speed [rpm] 1300 1300IMEP net [bar] 11 6.5

Pilot/Main % Split 30/70 30/70Pilot SOI [ATDC] -137 -137Injection Pressure [bar] 1500 1500

Intake Temp [°C] 40 40Intake Pressure [kPa] 200 152

EGR [%] 0-45 0-30

Baseline Operating Conditions

Hanson et al. "Operating a Heavy Duty DICI Engine with Gasoline for Low Emissions," SAE 2009-01-1442, 2009

13

Effect of EGR -

gasoline

A50 double injection EGR •

Simultaneous PM vs. NOx tradeoff can be achieved with sufficient EGR

EID=SOI-CA50

• Ignition Delay increases due to combination of EGR and low CN fuel

2010

• Approach EPA HD 2010 NOx

and PM emissions levels at 45% EGR

14

•

Combustion duration decreases with EGR

gasoline HCCI

(fixed CA50 requires earlier SOI)

•

Pressure rise rates increase (still lower than typical HCCI)

Effect of EGR -

gasoline

•

Net ISFC decreases: -

combustion phasing optimized

•

50% Indicated Thermal Efficiency approached

15

A50 Double Injection A50 Single Injection

Injection Strategy Double Single

EGR (%) 40.8 41

NOx (g/kWh) 0.41 0.37

HC (g/kWh) 2.68 1.39

PM (g/kWh) 0.021 0.026

CO (g/kWh) 6.76 5.53

ISFC net (g/kWh) 173.5 167.9

IMEP net (bar) 11.23 11.62

Max PRR (bar/deg) 12.4 9.0

Gasoline single injection -

A50

• Equivalence ratiostratificationcontrols ignitionand heat releaseprofile

50% indicated thermalEfficiency

16

Outline

•

Motivation

•


Gasoline PPC

•

CFD Modeling –

Fuel reactivity

•


Dual-fuel PCCI

•

Conclusions



17

10 20 30 40 50 60 70 80 900.000

0.002

0.004

0.006

0.008

0.010

0.012 = 0.5 = 1.0 = 1.5 = 2.0

Igni

tion

dela

y (s

)

Pressure (atm)

0

20

40

60

80

100

120

140

Cra

nk a

ngle

at 2

000

rev/

min

10 20 30 40 50 60 70 80 900.0000

0.0002

0.0004

0.0006

0.0008

0.0010

0.0012

0.0014

0.0016

0.0018

0.0020

Cra

nk a

ngle

at 2

000

rev/

min

Igni

tion

dela

y (s

)

Pressure (atm)

= 0.5 = 1.0 = 1.5 = 2.0

024681012141618202224

-

Constant volume combustion with Tinit

=800-900 K

iso-octanen-heptane

• n-heptane

(diesel) delay ~6 x shorter than iso-octane (gasoline)• Diesel delay much less sensitive to pressure and equivalence ratio• Gasoline fuel requires boosted operation and/or high intake temperature

and locally rich but “mixed enough”

(low swirl, low injection pressure)

Comparison of diesel vs. gasoline ignition delay

• CHEMKIN –

ERC PRF Mechanism

2 deg 12 deg

18

• Optimized operation requires different fuel reactivity for differentoperating conditions: Dual-fuel– Port fuel injection of gasoline– Direct injection of diesel fuel

Fuel reactivity control: Dual-fuel PCCI

•

Bessonette

(SAE 2007-01-0191) extended HCCI load range by varying fuel composition

–16 bar BMEP

required 27 cetane fuel: gasoline-like–3 bar BMEP

required 45 cetane fuel: diesel-like

Gasoline Diesel

Fuel blending in-cylinder

-

No DEF tank!DieselExhaust“Fuel”

19

-

6, 9, and 11 bar IMEP- 1300 rev/min

iso-octane

gasolinen-heptane

diesel

6 bar IMEP

0 10 20 30 40 50 600

20

40

60

80

100

250

180 g/kW-hr

MISFIRE

190g/kW-hr

PR

F [-]

EGR Rate [%]

10 bar/deg.

5.6 bar/deg.

Modeling used for PRF & EGR selection

190 g/kW-hr

180 g/kW-hr

10 bar/deg.

170

190

210

230240

Net ISFC [g/kW-hr]

9 bar IMEP

16 bar/deg.

230

220

180

MISFIRE

210

190

200

11 bar IMEP

gasoline

diesel

Experiments• SENKIN ERC-PRF simulations

• As load is increased, minimum ISFC cannot

be achieved with either neat diesel or neat gasoline

EGR

PRF

Kokjohn

& Reitz –

ICLASS-09

20

* Kokjohn

et al. SAE 09FFL-0107

Charge preparationKIVA GA optimization used to choose injection parameters*-

Gasoline port injection

-

Diesel DI

- SOI1 ~ -60°ATDC- SOI2 ~ -33°ATDC-

60% of diesel fuel in first injection

21

Outline

•

Motivation

•


Gasoline PPC

•

CFD Modeling –

Fuel reactivity

•


Dual-fuel PCCI

•

Conclusions



22

Experiments: Dual-fuel PCCI - 11 bar

-30 -20 -10 0 10 20 300

3

6

9

12

15

Crank [ATDC]

Pres

sure

[MPa

]

0

600

1200

1800

2400

85%

78%

82%

Hea

t Rel

ease

Rat

e [J

/]

SOI1 = -67ATDCSOI2 = -33ATDCInj. Pres. = 800 barIMEP (bar) 11

Speed (rpm) 1300

EGR (%) 45.5

Equivalence ratio (-) 0.77

Intake Temp. (°C) 32

Intake pressure (bar) 2.0

Gasoline (% mass) 78 82 85

Diesel inject pressure (bar) 800

SOI1 (°ATDC) -67

SOI2 (°ATDC) -33

Fract. of diesel in 1st

pulse 0.65

IVC (ºATDC) - 85

• Fuel reactivity controls ignition and heat release rate• Combustion phasing easily controlled with gasoline amount

161

168

175

78 79 80 81 82 83 84 850

7

14

Net

ISFC

[g/k

W-h

r]PR

R[b

ar/d

eg]

Gasoline [% of total fuel]

0.0

0.1

0.2

0.3

78 79 80 81 82 83 84 850.000

0.005

0.010

0.015N

Ox

[g/k

W-h

r] US 2010 HD Limit

Soot

[g/k

W-h

r]

Gasoline % of total fuel

23

-30 -20 -10 0 10 20 30 40 500

2

4

6

8

10

12

14

16

Crank [ATDC]

Pres

sure

[MPa

]

0

200

400

600

800

1000

1200

1400

1600

Hea

t Rel

ease

Rat

e [J

/]

SOI1 = -58ATDCSOI2 = -37ATDCInj. Pres. = 800 bar

Effect of Comp. Ratio: Dual-fuel PCCI

IMEP (bar) 9

Speed (rpm) 1300

EGR (%) 43



Intake pressure (bar) 2 1.74

Gasoline (% mass) 78 82


SOI1 (°ATDC) -58

SOI2 (°ATDC) -37


pulse 0.62

IVC (ºATDC) -85 -143

•

Stock CR (IVC 143) requires more gasoline to achieve similar combustion -

PRR controlled with gasoline fraction

-30 -20 -10 0 10 20 30 40 500

2

4

6

8

10

12

14

16

IVC 11579% Gas

IVC 14382% Gas

Crank [ATDC]

Pres

sure

[MPa

] IVC 8573% Gas

0

200

400

600

800

1000

1200

1400

1600

Hea

t Rel

ease

Rat

e [J

/]

SOI1 = -58ATDCSOI2 = -37ATDCInj. Pres. = 800 bar

IVC 85 (73% Gas) IVC 143 (82% Gas) IVC 143 (89% Gas) IVC 115 (79% Gas)

24

Effect of Comp. Ratio: Dual-fuel PCCI

•

PRR < 10 bar/deg and net ISFC of 158 g/kW-hr!

158159160161162163

Net

ISFC

[g/k

W-h

r]

82 83 84 85 86 87 88 898

10

12

14

PRR

[bar

/deg

.]Gasoline [% of total fuel]

IMEP (bar) 9

Speed (rpm) 1300

EGR (%) 43



Intake pressure (bar) 2 1.74

Gasoline (% mass) 78 82


SOI1 (°ATDC) -58

SOI2 (°ATDC) -37


pulse 0.62

IVC (ºATDC) -85 -143

• NOx

and soot similar for both cams

well below US 2010

82 83 84 85 86 87 88 890.000

0.005

0.010

0.015

Soot

[g/k

W-h

r]

Gasoline [% of total fuel]

0.0

0.1

0.2

0.3US 2010 HD Limit

NO

x [g

/kW

-hr]

25

•0

•10

•20

•30

•40

•50

•60

•70

•80

•90

•100

D-FPCCI

Gas.PPCI

Conv.Diesel LTC

•Per

cent

of F

uel E

nerg

y [%

]

Dual-fuel PCCI –

Thermal efficiency

Fuel-MEP

Q-MEPCL-MEP

HT-MEP

Ex-MEPI-MEPg

I-MEPn P-MEP

F-MEPBMEP

B F P Ex Ht C

I-MEPn

16% 14% 12% 11.7%

36% 37% 34% 31%

44% 45% 50% 53%

Conv. Diesel: Staples SAE 2009-01-1124; LTC: Hardy 2006-01-0026, 2006; Gas PPCI: Hanson SAE 2009-01-1442, 2009; D-F PCCI: Kokjohn

SAE 09FFL-0107

9–11 bar IMEP

26

Simulation results

-20 -15 -10 -5 0 5 10 15 201E-5

1E-4

1E-3

0.01

Crank [ATDC]

Mas

s Fr

actio

n [-]

0

400

800

1200

1600

2000

oh

ch2oco

ic8h18nc7h16

HRR

Tem

pera

ture

[K] a

nd H

RR

[J/]

Temp

Temperature (K) n-heptane (-) iso-octane (-) Formaldehyde (-)

Extended combustion duration even as load is increasedUncharacteristic of PCI

combustionSmall diesel quantity provides

improved control compared to gasoline HCCI

27

Conclusions•

PPC “Mixed enough”

Gasoline

-

No traditional PM/NOx tradeoff

-

Approach 2010 EPA HD on-highway truck emission standards

in-cylinder at 11 and 6 bar net IMEP-

Low ISFC and pressure rise rate

•

Dual-fuel PCCI concept used to control fuel reactivity-

Port fuel injection of gasoline (cost effective)

-

Direct injection of diesel fuel (moderate injection pressure)

-

Possibility of traditional diesel or SI (with spark plug) operation retained for full load operation

•

Dual-fuel operation at 6, 9, and 11 bar net IMEP achieved with near zero NOx and soot and reasonable Pressure Rise Rate

•

53% indicated thermal efficiency achieved

while

easily meeting US 2010 EPA standards in-cylinder

28

Wartsila-Sulzer

RTA96-C turbocharged two-stroke diesel is the most powerful and efficient prime-mover in the world. Bore 38”, 1820 L, 7780 HP/Cyl

at 102 RPM

Dual-fuel surpasses 50% Thermal Efficiency engines

• If technology could be applied to all US Truck and Auto engines, oil consumption could be reduced by 1/3 = oil imports from Persian Gulf

29

30

US Petroleum consumption: 20.7 Million Barrels of Oil per Day*65% used in transportation = 13.5 MBOD

Truck and Automotive fuel usage reduction by Dual Fuel:4.2 MBOD Diesel: 45%

53%= improvement of 18% = 0.6 million barrels saved

9.3 MBOD

Gasoline SI: 30%

53%= improvement of 77% = 4.1 million barrels saved

Total saved = 4.7 MBOD = 34% of US transportation oil(23% of total US petroleum used ~ $1 Billion saved / 2 days)

• Could reduce transportation oil consumption by 1/3 = US imports from Persian Gulf

-

while surpassing 2010 emissions regulations

• US DOE/EERE FreedomCar

& 21st Century Truck fuel efficiency goals:50% increase in light-duty, 25% increase in heavy-duty

Fuel Efficiency and US Oil Consumption

http://www.eia.doe.gov/*

Documents

High-Efficiency, Ultra-Low Emission Combustion in … · High-Efficiency, Ultra-Low Emission Combustion in a Heavy-Duty Engine via Fuel Reactivity Control Rolf D. Reitz, Reed Hanson,