Challenges in Making Natural Gas Vehicles

8/6/2019 Challenges in Making Natural Gas Vehicles

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Materials Science &Technology

Challenges and Potential ofadvanced methane gas vehicles

Christian Bach

Internal Combustion Engine Laboratory


2/22

SATW Congress, 29.08.2008


Content

Methane gasIn future used for low temperature or high temperature application?Very suitable fuel for otto cycled combustion engines

The Clean Engine Vehicle project (CEV)

A natural gas Euro-4/SULEV with 30% reduced CO2 emissions

Impact of fuel quality on knock behavior

a) Propane (Methane number of about 33)b) Hydrogen (Methane number of 0)

OutlookDevelopment of a natural gas hybrid powertrain concept

Conclusions


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Gaseous fuels as one option for CO2reduction and motor fuel diversification

Natural gas / preprocessed biogas driven engines

- 20-25% red. CO2 emissions per MJ fuel used (methane vs. gasoline)- Add. engine efficiency potential of 10% (optimized gas engines)- Very low exhaust emissions are possible (incl. non-limited pollutants)- Possible to integrate preprocessed biogas (produced from waste)- Transition technology to hydrogen (incl. socio economic aspects)

Additional potential of reformulated methane gas fuels- Conversion of natural gas / biogas methane(increased know-resistance, extended range)

- Enrichment of methane with hydrogen (improved efficiency)


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Natural gas: a fuel for vehicles or furnaces?

High temperature heat vs. low temperature heat

Existing know-how in distributing naturalgas world wide

40% (in CH) is used for low temperatureheat (substitution potential for heatpumps)

Situation

If used as fuel for motor vehicles:

Direct CO2 reduction (lower C-content)

with significant lowering of air pollutants

Additional CO2 reduction due to:- less overpowered vehicles- more efficient vehicles (range!)- increased demand on fueling stations

but reduced demand on grid dispersion

Short term view

Important biogas potential available(75 PJ/a biomass, resp. 40 PJ/a methane)

Technical and socio economic bridge fromtodays fossil fuels to hydrogen

Mid and long term view


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Methane as fuel for otto cycled engines

Efficient and clean

Thermal efficiency:1

11

=

thn

where: = compression ratio

= adiabatic exponentv

p

cc

Fuel spec. Gasoline Methane

Octane number 95 98 130

Compression ratio 10 - 11 13 - 13.5

Reduced thermal NOx emissions(engine out)

Reduced CO2 emissions

Disadvantage!?

Calorific value 43 MJ/kg 50 MJ/kg

Flame temperature 2500 K 2150 K

H:C ratio 2 : 1 4 : 1

Spec. CO2 emissions 74 g/MJ 55 g/MJ

Energy density 30 MJ/dm3 7 MJ/dm3


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NGV roadmap

From conversion to optimized gas engines

ConversionDriving with natural gas

- Each vehicle modelavailable as NGV

- Low technical level- Unreliable

- Potential not used- Increased skepticism

Opt. gas enginesreal gas engines

- Efficient, clean, reliable- Near Zero Emissions- potential- Range limitation- forces high efficiency

- Overcome technical- backlog

OEM bifuelGas driven gasoline engines

- Clean, reliable

- Limited vehicle models- Range (300 km)

- Costs (2 fuels)


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Content







Conclusions


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Clean Engine Vehicle Project (CEV)

Project overview

Aim of project -30% CO2

Euro-4 and SULEV

Exhaust aftertreatment Catalytic converter concept Oxygen management

Engine Increased compression Controlled turbo charging Optimized engine control


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Clean Engine Vehicle Projekt (CEV)

CO2 reduction path

148.6159.0

116.5113.4

109.5

37.0

31.0

44.0 44.0

33.0

0

20

40

60

80100

120

140

160

180

BenzinBasismotor

ErdgasOhne nderung

ErdgasOptimierte

Verdichtung

ErdgasMit Downsizing

Benzin1.4 l

CO2-Emissioning/km

0

10

20

30

4050

60

70

80

90

Motorleistun

ginkW

CO2-Emission Leistung

CO2: -31%

Leistung: +20%

-21.6%

-16.2%

-2.7%

+6.5%

-3.4%

+33.3%


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Clean Engine Vehicle Project (CEV)

Zero NOx emissions

0.001

0.010

0.100

1.000

10.000

100.000

1000.000

0 200 400 600 800 1000 1200 1400

Zeit in s

NOxKonzentrat

ioninppmV

0

20

40

60

80

100

120

Geschwindigk

eitinkm/h

NOx Ansaugluft NOx TMessung 154 NOx Messung 151 NOx Messung 153 sch_speed

NOx-Konzentration in der Ansaugluft

NOx-Konzentration im Abgas

ca. 700 m


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Content







Conclusions


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Impact of gas quality

Investigated gas qualities

0 15%- - -- - -- - -Vol-%Hydrogen H2

- - -3.0- - -- - -Vol-%>C3 HCs

- - -1.0- - -- - -Vol-%Carbon Dioxide CO2

- - -2.014.0- - -Vol-%Nitrogen N2

- - -1.0- - -- - -Vol-%Propane C3H8

- - -4.0- - -- - -Vol-%Ethane C2H6

100 - 85%89.086.0100.0Vol-%Methane

Hydrogen enrichedmethane

Natural gas(Swiss grid)

G25G20

68104100- - -Methane number

15.97613.35917.173Kg/kgStoic A/F ratio

46.2738.6249.65MJ/kgCalorific value

0.8330.7900.716kg/m3Density (0C)


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90

95

100

105

110

115

120

5 10 15 20 25

Ignition point [KWvOT]

Torque[Nm]

Md G20

Md G25

Md NG

Eff G20

Eff G25

Eff NG

late

Impact of methane gas fuel quality

Ignition point (Engine rev. 2000 rpm, bmep = 2 bar)

30 35

30

31

32

33

34

35

36

37

38

39

40

Efficiency[%]

early

Natu

ralGasNG

MethaneG20

Methane/N2G2

5


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30 31 32 33 34 35 36 37 38 39 401.8

1.9

2

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

mU/m

tot(1-x

B) bei Klopfbeginn [%]

dQ/dLocMin

Max

[%/CA]

Relation between burn rate and knocking

Methane (G20) a


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Admixture of hydrogen (HCNG)

Comparison of laminar combustion velocity

4.07

9.50

29.58

concstoic[cm/s]

3346.04.2747.2Propane C3H8

10042.010.1743.0Methane CH4

0237.042.5346.0Hydrogen H2

MZSLstoic[cm/s]

concmax[cm/s]

SLmax[cm/s]


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330

332

334

336

338

0 5 10 15

Hydrogen in Fuel [vol%]

Opt.SparkTim.[Crank.

Deg.]

10

20

30

40

50

60

70

DistancetoST[Crank.

Deg.]

ST 2bar bmep M FB5, 2 bar bmep

M FB50, 2bar bmep M FB90, 2 bar bmep

Admixture of hydrogen (HCNG)

Impact on combustion

19

19.5

20

20.5

21

5 10 15 20

EGR rate [mass-%]

EngineFuelConv.

Efficiency[%]

no H2 DoE no H2 Meas.

5vol% H2 DoE 10vol% H2 DoE

15vol% H2 DoE 15vol% H2 Meas.

5% H2

10% H2

15% H2

0% H2


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CLEVER project

Downsized natural gas hybrid powertrain

Development of a newcombustion cycle (with

gas direct injection) Optimization of thermo

dynamic cycle (de-throttling)

Development of enhanceddownsizing concept(controlled turbo charging)

Hybridization (design ofconcept, recuperation,

starting torque, turbo lagcompensation)


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NG-hybrid vs. with EU-mix electric vehicle

Concawe, EUCAR, JRD Well-to-wheel Study 2006


20/22



Content




Impact of fuel quality on knock behaviora) Propane (Methane number of about 33)b) Hydrogen (Methane number of 0)


Conclusions


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Conclusions

Methane is a suited fuel for turbo charged engines Methane is a high temperature capable fuel and well suited for turbo

charged motor applications due to the high knock resistance.

Dedicated methane gas engines have the potential for increasedefficiency and reduced emissions. The compliance with futureemission regulations is much easier than for liquid fuels.

Preprocessed biogas can be added in all possible ratios without

modifications on the vehicle. Propane should be limited in the natural gas grid or reduced/

eliminated at the fueling station due to the knock increasing impact(low methane number)

The admixture of hydrogen (e.g. at the fueling station) could giveanother potential for increased efficiency, if the hydrogen is notproduced from fossil sources.


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Thank you for your attention!

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Challenges in Making Natural Gas Vehicles