Alternative Propulsion Systems and Energy CarriersAustrian, European and global R&D- and demonstration projects,

research institutions and funding programs

Vienna, 16.10.2009 in cooperation with

Emission Behavior and Efficiency of SI Engines Operated with Biogas

Heiko Pflaum, Bernhard Geringer, Peter Hofmann

2Rethinking Propulsion.

1. Introduction

2. Test engine

3. Comparison of Biogas with Eurosuper 95 and CNG

• Part Load

• Full Load

4. Comparison of different Biogas qualities (CO2-content)

5. Conclusions

Content

1. Introduction

2. Test engine

3. Comparison of Biogas with Eurosuper 95 and CNG

• Part Load

• Full Load

4. Comparison of different Biogas qualities (CO2-content)

5. Conclusions

3Rethinking Propulsion.

Almost Closed CO2-Cycle:further reductionof CO2-emissions

Motivation

EU Legislation:CO2-reduction

emission standardsindependence of fossil fuels

High Knock Resistance:advantage at fullload conditions

Lower C/H-Ratio:reduction of CO2-emissions

4Rethinking Propulsion.

CO2-content:Reduction of gas-quality

due to higher CO2-content

Motivation

Hydrogen-content:Increased gas-quality

due to higher H2-content

Biogas processing:Engine potential of

different processing steps

real Biogas,not simulated

5Rethinking Propulsion.

Composition of raw Biogas

<3mg/m3CFC

0 – 1Vol%Ammoniac

0 – 2Vol%Sulfide

0 – 2Vol%Oxygen

0 – 1Vol%Hydrogen

0 – 20Vol%Nitrogen

14 – 55Vol%Carbon dioxide

40 – 80Vol%Methane

GehaltEinheitcomponent

Composition for recovery from fermentative processes

Methane enrichment by separation of CO2Natural gas quality: CH4 ≥ 96% (AUT)

Separation during Biogas processing

Source: Mayer, T., Hofbauer, H., Vienna University of Technology 2008

6Rethinking Propulsion.

1. Introduction

2. Test engine

3. Comparison of Biogas with Eurosuper 95 and CNG

• Part Load

• Full Load

4. Comparison of different Biogas qualities (CO2-content)

5. Conclusions

Content

7Rethinking Propulsion.

Test engine and experimentation

Intake-manifold fuel injectionmixture preparation

12,5 : 1Compression ratio

135 / 4200Nm / rpmmax. torque / rpm

71 / 6200kW / rpmeffective power / rpm

79 x 81,5mmbore x stroke

1598cm3displacement

4 cylinder /in-line, 4 valves per cylindercylinder / alignment

high compression ratiofor gas operation

Separated injection valvesfor gas- and liquid fuel operation

All experiments carried out with stoichiometric air ratio (except assembly protection with Eurosuper 95)

All measurements of exhaust emissions in raw exhaust before oxidation catalyst

1,6 l engine,natural aspirated

8Rethinking Propulsion.

1. Introduction

2. Test engine

3. Comparison of Biogas with Eurosuper 95 and CNG

• Part Load

• Full Load

4. Comparison of different Biogas qualities (CO2-content)

5. Conclusions

Content

9Rethinking Propulsion.

Results for Eurosuper 95, CNG and Biogas,load point 2000 rpm – 2 bar BMEP

0

20

40

60

80

100

120

CO2Tank toWheel

CO2Well toWheel

HC CO NOx

spez

. raw

em

issi

ons

refe

renc

ed to

Euro

supe

r 95

[%]

CNGBiogas 97

Eurosuper 95 = 100%

engineoperation

path oflife*

CNG: Rest CxHyBiogas: Rest CO2

*Quelle: Edwards, R. et al, November 2008

-60% to -70%

band width

10Rethinking Propulsion.

Results for Eurosuper 95, CNG and Biogas,load point 2000 rpm – 2 bar BMEP

-30 -20 -10 -0 10 20 30 40 50 60 70 80 90Kurbelwinkel [Grad]

Bren

nrau

mte

mpe

ratu

r [K]

0

300

600

900

1200

1500

1800

2100

2400

2700

3000

Super 95Biogas 97

*Quelle: Edwards, R. et al, November 2008

Higher hydrogen content in gaseous fuelsmore H2O as combustion productreduced combustion temperatures

crank angle [degree]

Com

bust

ion

tem

pera

ture

[K]

11Rethinking Propulsion.

1. Introduction

2. Test engine

3. Comparison of Biogas with Eurosuper 95 and CNG

• Part Load

• Full Load

4. Comparison of different Biogas qualities (CO2-content)

5. Conclusions

Content

12Rethinking Propulsion.

6

7

8

9

10

11

12

1000 2000 3000 4000 5000 6000engine speed [rpm]

BM

EP [b

ar]

Super 95CNGBiogas 97

Results for Eurosuper 95, CNG and Biogasat full load conditions

Late combustion for Eurosuper 95High exhaust gas temperaturescatalyst overheating protection

up to -10%

13Rethinking Propulsion.

0

100

200

300

400

500

600

700

800

900

1000

1000 2000 3000 4000 5000 6000engine speed [rpm]

Ener

gy c

onte

nt in

com

bust

ion

cham

ber B

renn

raum

[kJ/

h]fo

r sto

ichi

omet

ric c

ombu

stio

n Super 95CNGBiogas 97

Results for Eurosuper 95, CNG and Biogasat full load conditions

Reduced mixture heat value with gas operation:

reduction of full load torque of up to 10%

-20%

14Rethinking Propulsion.

25

27

29

31

33

35

37

1000 2000 3000 4000 5000 6000engine speed [rpm]

effic

ienc

y [%

]

Super 95CNGBiogas 97

catalyst overheating protectionfor Eurosuper 95

+2,7%

Results for Eurosuper 95, CNG and Biogasat full load conditions

15Rethinking Propulsion.

0

5

10

15

20

25

30

35

1000 2000 3000 4000 5000 6000engine speed [rpm]

50%

mas

s fr

actio

n bu

rned

[°C

AaT

DC

]

Super 95CNGBiogas 97

Late combustion necessary toprevent knocking with ROZ 95

Results for Eurosuper 95, CNG and Biogasat full load conditions

16Rethinking Propulsion.

32,9

4,6

7,9

35,7

7,9

0,9

35,6

7,7

0,9

0

10

20

30

40

50

60

70

Super CNG Biogas

efficiency loss realcombustion

efficiency loss realcharge

efficiency losscombustion position

efficiency lossunburned

efficiency loss wallheat

efficiency loss gasexchange

efficiency lossfriction

efficiency(measured)

Thermal efficiency = 63,5%

Higher efficiencywith gaseous fuels

7% advantage for gas as result ofoptimum combustion timing

advantage of highoctane number

Late combustion with EurosuperResults in low gastemperatures (pmax drops)

reduction of wall heat losses

Results for Eurosuper 95, CNG and Biogasat 2000 rpm, full load

17Rethinking Propulsion.

1. Introduction

2. Test engine

3. Comparison of Biogas with Eurosuper 95 and CNG

• Part Load

• Full Load

4. Comparison of different Biogas qualities (CO2-content)

5. Conclusions

Content

18Rethinking Propulsion.

Results for different Biogas qualities (CO2-content), load point 2000 rpm – 2 bar BMEP

0

20

40

60

80

100

120

140

Efficiency CO2 HC CO NOxspez

. raw

em

issi

ons

and

effic

ienc

y re

fere

nced

toB

ioga

s (9

7% M

etha

ne) [

%]

Biogas 84% MethaneBiogas 80% Methane

Biogas 97% Methane = 100%

CO2 contained in fuel isemitted in the exhaust gas

Reduction of NOx-emissions due to higherCO2 content reduction of Temperature

19Rethinking Propulsion.

1. Introduction

2. Test engine

3. Comparison of Biogas with Eurosuper 95 and CNG

• Part Load

• Full Load

4. Comparison of different Biogas qualities (CO2-content)

5. Conclusions

Content

20Rethinking Propulsion.

Biogas proofed equal potential as CNG in the engine operationlife cycle Biogas reduces CO2 emissions by 60% to 70% compared to Eurosuperincreased efficiency at full load conditions as result of high knock resistance of Biogasdecreased full load torque for naturally aspirated engine, but same for turbocharged engineSame or even better emission level for lower Biogas qualities (CO2-content)

Requires changed logistic

Conclusions

21Rethinking Propulsion.

Contact

Heiko PflaumInstitute for ICE and Automotive Engineering

Address: Getreidemarkt 91060 Wien

Tel: +43-(0)1-58801 30015Fax: +43-(0)1-58801 31599web: www.ivk.tuwien.ac.atEmail: heiko.pflaum@ivk.tuwien.ac.at

22Rethinking Propulsion.

Thank you for your attention !

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