ICEF2005-1240

Alternative Modes Combustion Study: HCCI Fueled With Heptane and Spark Ignition Fueled with Reformer Gas A Study of a Dual-Mode Combustion, Dual-Fuel Engine

Vahid Hosseini, M David Checkel Mechanical Engineering Department University of Alberta, Canada

Outline „

Introduction … HCCI

Combustion … Hydrogen-Fueled Spark Ignition (SI) Engine … Reformer Gas (RG) … HCLB-SI/HCCI Concept „

Experimental Setup … Engine

and DAQ System

… Fuels

„

Results … Heptane-Fueled

HCCI … RG-Enriched HCCI … RG-Fueled SI „

Conclusion

Outline „

Introduction …HCCI Combustion … Hydrogen-Fueled SI engine … Reformer Gas … HCLB-SI/HCCI Concept

„

Experimental Setup … Engine

and DAQ System

… Fuels

„

Results … Heptane-Fueled

HCCI … RG-Enriched HCCI … RG-Fueled SI „

Conclusion

HCCI: Homogenous Charge Compression Ignition

Spontaneous Multi-Site Combustion of an Air/Fuel Mixture

ICEF2005-1240

1

HCCI: Homogenous Charge Compression Ignition

Spontaneous Multi-Site Combustion of an Air/Fuel Mixture „

GOOD Low NOx … High Efficiency … No Throttle at Part-Load …

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HCCI: Homogenous Charge Compression Ignition

Spontaneous Multi-Site Combustion of an Air/Fuel Mixture „

GOOD Low NOx … High Efficiency … No Throttle at Part-Load …

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„

BAD High HC, CO … Limited Operating Range … Impossible Cold-start, Full-load …

1

HCCI: Homogenous Charge Compression Ignition

Spontaneous Multi-Site Combustion of an Air/Fuel Mixture „

„

GOOD Low NOx … High Efficiency … No Throttle at Part-Load …

„

High HC, CO … Limited Operating Range … Impossible Cold-start, Full-load …

UGLY … Difficult

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BAD

to Control Combustion Timing

1

HCCI / SI Engine Comparison:

Higher Peak Pressure, Higher Rate of Heat Release, Shorter Combustion Duration SI, CNG, λ=1, EGR = 0 % HCCI, Heptane,

HCCI, n-Heptane, λ = 2.81, EGR = 0 %

60

λ=2.81, EGR = 0 %

SI, CNG,

λ = 1.00,

EGR= 0 %

50

800

8.35 bar

Pressure (bar)

Total Net Heat Release (J)

1000

600

400

200

40

30

20

10

0

BD 0

-200 -120

-80

-40

0

CAD, aTDC

40

80

-40

0

80

CAD, aTDC

CAD= Crank Angle Degree

aTDC= after Top Dead Center ICEF2005-1240

40

2

Limited Operating Region

3

Low IMEP Boundary

2.5

λ

λ= Relative Air/Fuel Ratio

3.5

Knock Boundary 2

1.5

Misfire 1 0

10

20 30 EGR(%)

40

50

EGR= Exhaust Gas Recirculation ICEF2005-1240

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An Existing Solution to HCCI Disadvantages

A Dual Mode Engine:

/

Spark Ignition High Octane Number Fuel Low Compression Ratio Low Dilution Level

HCCI Low Octane Number Fuel High Compression Ratio High Dilution Level

Transient Condition

Variable Valve Timing

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Motivation for This Study „

HCCI is spontaneous and sensitive to fuel properties ; hence:

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Motivation for This Study „

HCCI is spontaneous and sensitive to fuel properties ; hence: Question: Is it possible to run a dual-mode SI/HCCI engine without altering geometry and by altering fuel properties ?

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5

An Existing Solution to HCCI Disadvantages

A Dual Mode Engine:

/

Spark Ignition High Octane Number Fuel Low Compression Ratio Low Dilution Level

HCCI Low Octane Number Fuel High Compression Ratio High Dilution Level

Variable Valve Timing

ICEF2005-1240

A New Solution to HCCI Disadvantages

A Dual Mode Engine:

/

Spark Ignition High Octane Number Fuel Low Compression Ratio Low Dilution Level

HCCI Low Octane Number Fuel High Compression Ratio High Dilution Level

HCLB-SI/HCCI (High Compression ratio Lean Burn-SI/HCCI) ICEF2005-1240

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Outline „

Introduction … HCCI

Combustion

…Hydrogen-Fueled

SI engine

… Reformer

Gas … HCLB-SI/HCCI Concept „

Experimental Setup … Engine

and DAQ System

… Fuels

„

Results … Heptane-Fueled

HCCI … RG-Enriched HCCI … RG-Fueled SI „

Conclusion

Previous Studies: „

Hydrogen as a fuel for SI engine: … Ultra-low

lean limit, high efficiency , no carbon emissions, less cyclic variation, and higher octane number

„

Hydrogen as an additive for dual-fuel SI engine: … Cold-start

enhancement, Combustion enhancement in adverse condition

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Outline „

Introduction … HCCI

Combustion … Hydrogen-Fueled SI engine

…Reformer

Gas

… HCLB-SI/HCCI

„

Concept

Experimental Setup … Engine

and DAQ System

… Fuels

„

Results … Heptane-Fueled

HCCI … RG-Enriched HCCI … RG-Fueled SI „

Conclusion

Reformer Gas „

Hydrogen can be stored in a vehicle as: … Compressed

gas … Cryogenic liquid … Liquid dissolved in metal hydride

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Reformer Gas „

Hydrogen can be stored in a vehicle as: … Compressed

gas … Cryogenic liquid … Liquid dissolved in metal hydride OR

„

It can be produced on-board: … Thermal

decomposition … Steam reforming … Partial oxidation ICEF2005-1240

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Reformer Gas „

Hydrogen can be stored in a vehicle as: … Compressed

gas … Cryogenic liquid … Liquid dissolved in metal hydride OR

„

It can be produced on-board: … Thermal

decomposition … Steam reforming … Partial oxidation ICEF2005-1240

Produces solid carbon Stationary and Industrial Applications Mobile Applications

8

Outline „

Introduction … HCCI

Combustion … Hydrogen-Fueled SI engine … Reformer Gas

…HCLB-SI/HCCI „

Concept

Experimental Setup … Engine

and DAQ System

… Fuels

„

Results … Heptane-Fueled

HCCI … RG-Enriched HCCI … RG-Fueled SI „

Conclusion

How does the HCLB–SI/HCCI Work? SI Compression Ratio

Fuel Control Method Load

ICEF2005-1240

HCCI

Constant, Relatively High SI RG

Diesel Type

Spark

Mixture Quality RG Enrichment

Startup, Idle, High Load

Part Load

9

Outline „

Introduction … HCCI

Combustion … Hydrogen-Fueled SI engine … Reformer Gas … HCLB-SI/HCCI Concept „

Experimental Setup …Engine

and DAQ System

… Fuels

„

Results … Heptane-Fueled

HCCI … RG-Enriched HCCI … RG-Fueled SI „

Conclusion

Experimental Setup

„

Waukesha CFR Engine … CR=11.5 … Constant

Speed =800 RPM … Manual Control EGR … Intake heater … Labview DAQ System … High speed pressure measurement with 0.1 CAD resolution

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Outline „

Introduction … HCCI

Combustion … Hydrogen-Fueled SI engine … Reformer Gas … HCLB-SI/HCCI Concept „

Experimental Setup … Engine

and DAQ System

…Fuels „

Results … Heptane-Fueled

HCCI … RG-Enriched HCCI … RG-Fueled SI „

Conclusion

Fuel Properties „ „

A mixture of 25% CO and 75% H2 was used as simulated RG n-Heptane was used as the low octane fuel

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Fuel Properties „ „

A mixture of 25% CO and 75% H2 was used as simulated RG n-Heptane was used as the low octane fuel Heptane

RG

Formula

C7H16

0.25 CO+0.75 H2

Octane

0

140 (H2), 106(CO)*

Molar Mass (kg/kmol)

100.203

8.514

LHV(KJ/Kg)

44,926

29,471

70**

210 (H2), 28(CO)

Laminar Burning Velocity (cm/s)***

* SAE Paper, 2004-01-0975 ** SAE Paper, 800103, P=6 atm, T=520 K ICEF2005-1240

*** P=1 atm, T=298 K, φ=1

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Outline „

Introduction … HCCI

„

„

Combustion … Hydrogen-Fueled SI engine … Reformer Gas … HCLB-SI/HCCI Concept Experimental Setup … Engine and DAQ System … Fuels

Results …Heptane-Fueled … RG-Enriched

HCCI … RG-Fueled SI „

Conclusion

HCCI

Operating Region 3.5

3

Low IMEP Boundary

λ

2.5

Knock Boundary 2

1.5

Misfire 1 0

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10

20 30 EGR(%)

40

50

12

Combustion Control by Combination of λ and EGR: Accumulated Net Heat Release (J)

Effect on Combustion Timing 1000

90% ANHR

800

600

400

SOC

200

10% ANHR

0

Combustion Duration

-200 -120

-80

-40

0

40

80

CAD, aTDC

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Combustion Control by Combination of λ and EGR:

Effect on Combustion Timing 45% EGR 35% EGR 0% EGR

cr ea s

es

16

R

In

14

EG

Start of Combustion (bTDC)

Retarded Combustion

18

12

10

8 1

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1.5

2

λ

2.5

3

3.5

14

Combustion Control by Combination of λ and EGR:

Effect on Combustion Duration Combustion Duration (CAD)

Shorter Combustion

32

28

20% EGR 25% EGR 35% EGR 40% EGR 45% EGR

24

20

16

12 1.2

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1.6

λ

2

2.4

2.8

15

Outline „

Introduction … HCCI

„

„

Combustion … Hydrogen-Fueled SI engine … Reformer Gas … HCLB-SI/HCCI Concept Experimental Setup … Engine and DAQ System … Fuels

Results … Heptane-Fueled

HCCI

…RG-Enriched … RG-Fueled

„

Conclusion

SI

HCCI

Effect of RG on Heptane-Fueled HCCI Combustion: Start of Combustion (CAD,aTDC)

Retarded Combustion 2

0

-2

-4

-6 0

10

20

30

Reformer Gas Mass(%) ICEF2005-1240

40

16

Effect of RG on Heptane-Fueled HCCI Combustion:

Faster Combustion Combustion Duration (CAD)

14

12

10

8

6

0

20

40

60

80

Reformer Gas Mass (%) ICEF2005-1240

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Effect of RG on Heptane-Fueled HCCI Combustion:

Higher Power 4.4

IMEP(bar)

4

3.6

3.2

2.8 0

20

40

60

80

Reformer Gas Mass Fraction(%) ICEF2005-1240

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Effect of RG on Heptane-Fueled HCCI Combustion:

Higher Exhaust Temperature

Exhaust Temp(oC)

340

320

300

280

260

240

220 0

20

40

60

80

Reformer Gas Mass Fraction(%) ICEF2005-1240

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Effect of RG on Heptane-Fueled HCCI Combustion: Indicated Specific NOx (gr/kW-hr)

Higher NOx 5

0.1 0.08 0.06

4

0.04 0.02 0

3

0

0.5

1

2

1

0 0

20

40

60

80

Reformer Gas Mass Fraction(%) ICEF2005-1240

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Effect of RG on Heptane-Fueled HCCI Combustion:

Indicated Specific HC (gr/kW-hr)

Lower HC 16

12

8

4

0 0

20

40

60

80

Reformer Gas Mass Fraction(%) ICEF2005-1240

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Outline „

Introduction … HCCI

„

„

Combustion … Hydrogen-Fueled SI engine … Reformer Gas … HCLB-SI/HCCI Concept Experimental Setup … Engine and DAQ System … Fuels

Results … Heptane-Fueled … RG-Enriched

HCCI

…RG-Fueled „

Conclusion

HCCI

SI

HCLB-SI/HCCI Comparison with CNG-Fueled SI

Power

8

Efficiency SI, CNG SI, Reformer Gas HCCI, n-Heptane

IMEP (bar)

7 36.68 37.1 6 35.53 43.52

5

44.15

4

43.72 43.71

3 1 ICEF2005-1240

1.5

2

λ

2.5

3

3.5

23

HCLB-SI/HCCI Comparison with CNG-Fueled SI Accumulated Net Heat Release (J)

Heat Release SI,CNG SI,Reformer Gas HCCI, n-Heptane HCCI, n-Heptane+15% Reformer Gas

1200

800

400

0 -40

-20

0

20

40

CAD (aTDC) ICEF2005-1240

60

80

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HCLB-SI/HCCI Comparison with CNG-Fueled SI Indicated Specific NOx (gr/kW-hr)

NOx 12

n-Heptane, HCCI HCCI, n-Heptane/RG SI, CNG SI, RG

8

4

0 0.8

ICEF2005-1240

1.2

1.6

λ

2

2.4

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HCLB-SI/HCCI Indicated Specific NOX (gr/kW-hr)

NOx-IMEP Map n-Heptane, HCCI HCCI, n-Heptane/RG SI, RG

5

4

3

2

1

0 2.8

3.2

3.6

4

IMEP (bar) ICEF2005-1240

4.4

4.8

26

HCLB-SI/HCCI Indicated Specific NOX (gr/kW-hr)

NOx-IMEP Map n-Heptane, HCCI HCCI, n-Heptane/RG SI, RG

5

4

3

2

1

0 2.8

3.2

3.6

4

IMEP (bar) ICEF2005-1240

4.4

4.8

26

HCLB-SI/HCCI Indicated Specific NOX (gr/kW-hr)

NOx-IMEP Map n-Heptane, HCCI HCCI, n-Heptane/RG SI, RG

5

4

3

2

1

HCCI 0 2.8

3.2

3.6

4

IMEP (bar) ICEF2005-1240

4.4

4.8

26

HCLB-SI/HCCI Indicated Specific NOX (gr/kW-hr)

NOx-IMEP Map n-Heptane, HCCI HCCI, n-Heptane/RG SI, RG

5

4

3

2

RG-Enriched HCCI 1

0 2.8

3.2

3.6

4

IMEP (bar) ICEF2005-1240

4.4

4.8

26

HCLB-SI/HCCI Indicated Specific NOX (gr/kW-hr)

NOx-IMEP Map n-Heptane, HCCI HCCI, n-Heptane/RG SI, RG

5

4

3

2

1

RG-Fueled SI

0 2.8

3.2

3.6

4

IMEP (bar) ICEF2005-1240

4.4

4.8

26

Heptane-Fueled HCCI Combustion Variability „

Heptane HCCI

IMEP=4.91 bar COVimep=1.04%

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RG-Fueled SI Combustion Variability „

RG, SI

IMEP = 5.03 bar COVimep=3.06 %

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CNG-Fueled HCCI Combustion Variability „

CNG, SI

IMEP= 7.33 bar COVimep=9.89 %

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Combustion Variability Comparison HCCI, Heptane

SI, RG

SI, CNG

IMEP (bar)

4.91

5.03

7.33

COVimep(%)

1.04

3.06

9.89

IMEP=4.91 bar COVimep=1.04%

ICEF2005-1240

IMEP = 5.03 bar COVimep=3.06 %

IMEP= 7.33 bar COVimep=9.89 %

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Outline „

Introduction … HCCI

„

„

Combustion … Hydrogen-Fueled SI engine … Reformer Gas … HCLB-SI/HCCI Concept Experimental Setup … Engine and DAQ System … Fuels

Results … Heptane-Fueled … RG-Enriched

HCCI

HCCI … RG-Fueled SI „

Conclusion

Conclusions „

„

Avoiding cost and complexity of VVT it is possible to run an engine with the concept of HCLB-SI/HCCI in startup, full load and part load without throttling. RG fueled SI engine produces less power and less cyclic variation but more EGR tolerability than CNG fueled same SI engine.

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Conclusions

„

HCCI combustion of a diesel type fuel can be controlled by dilution effects and by adding RG at different operating conditions. The combination of regulating EGR, regulating λ and/or addition of RG has the potential to provide fast response control mechanisms for HCCI combustion.

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Conclusions

„

The effect on combustion characteristics of RG addition with different base fuels and also the effect of different RG compositions requires further study.

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Acknowledgment

The authors gratefully acknowledge the contribution of the Auto21 National Center of Excellence to supporting this work.

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Thank you for your Attention

Questions ?

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Effect of RG on Minimum λ 1.5

λ

1.4

1.3

1.2

1.1 20

30

40

50

60

70

Reformer Gas Mass (%)

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