GASON: A LEAN CNG COMBUSTION FOR HIGHEST ENGINE ...

GASON: A LEAN CNG COMBUSTION FOR HIGHEST ENGINE EFFICIENCIES ABOVE 43% UTILISING AN IGNITION CHAMBERM. Weißner, F. Beger, C. Klüting, G. Lucas, Volkswagen AGT. Hilfiker, Empa

SAE INTERNATIONAL

GasOn: Lean CNG Combustion with ignition chamberMotivation

CNG = eco-friendly / sustainable / cost effective mobility

Paper 18CO-0060 2

SAE INTERNATIONAL


3

State of the art:

• bivalent system• stoichiometric burn (λ=1) with TWC

GasOn:

• monovalent system• lean burn (λ>>1) to reach CO2 levels of 20% below best in class

(2015)

Paper 18CO-0060

SAE INTERNATIONAL


4

MOTIVATION Combustion Process

Monovalent CNG‐Combustion to exploit fuel advantages and reach maximum efficiency

Efficiency can be improved by using lean combustion for CNG with λ>>1 Target: λ=2Increased requirements for ignition system (mixture, pressure)Creating a suitable distribution of NG in the air locally and globally

Paper 18CO-0060

SAE INTERNATIONAL

GasOn: Lean CNG Combustion with ignition chamberEngine Design

5

Section view through cylinderhead

Detail: ignition chamberHardware: ignition chamber

Paper 18CO-0060

SAE INTERNATIONAL


6

Designs with different internal shapes

Ignition Chamber Designs

cylinderhead

Paper 18CO-0060

SAE INTERNATIONAL


7

Design 1

Check Valve

Design 4Design 3Design 2

Paper 18CO-0060

SAE INTERNATIONAL


8

Target: lowest CNG massflow (<1mg/stroke)

Dosing system to supply CNG into the ignition chamber

Dosing System

Overview gas supply system

Paper 18CO-0060

SAE INTERNATIONAL


9

Engine #1: spark plug Engine #2: ign. chamber

Reference Engine

Paper 18CO-0060

SAE INTERNATIONAL


10

Engine assy Engine on testrig Paper 18CO-0060

SAE INTERNATIONAL

GasOn: Lean CNG Combustion with ignition chamberResults

11

GasOn operating point K (2000 rpm / 220 Nm)

NO

x [g

/kW

h]0

2

4

6

8

10

12

14

16

Lambda [-]0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1

power loss /turbocharger limit

reference engine w/o prechamber engine w. scavenged prechamber

brak

e en

gine

effi

cien

cy [

%]

36

37

38

39

40

41

42

43

44

Lambda [-]0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1




- 14% bmep

- 30% bmep

- 2% bmep

- 9% bmep

Engine Efficiency NOx‐Emission

Engine efficiency over lambda NOx-emission over lambda

Paper 18CO-0060

SAE INTERNATIONAL


12


T af

ter t

urbi

ne [

°C]

250

300

350

400

450

500

550

600

650

Lambda [-]0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1




THC

[g/

kWh]

0

5

10

15

20

25

Lambda [-]0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1



HC Emission (Methane) Exhaust Gas Temperature

THC Emission over lambda Exhaust gas temperature over lambda

Paper 18CO-0060

SAE INTERNATIONAL


13

Later ignition/ faster combustion

‐505101520253035404550

‐30 ‐25 ‐20 ‐15 ‐10 ‐5 0 5 10 15 20 25 30

heat re

lease rate [J/°CA

]

crank angle [°CA]

spark plug engine prechamber engine

TDC

ignition timing

Paper 18CO-0060

SAE INTERNATIONAL


14

engine efficiency / lambda sweep NEFZ/WLTC VW operating points A,E,F,Kfuel: CNG / catalyst: none / scavenged prechamber operation / SOI pc: 300°CA b. TDC

brak

e en

gine

effi

cien

cy [

%]

20

22

24

26

28

30

32

34

36

38

40

42

44

46

Lambda [-]0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2

max. efficiency: lambda = 1.7

OP A (1400rpm/50Nm) / PC7 OP E (1200rpm/30Nm) / PC7 OP F (1500rpm/100Nm) / PC7 OP K (2000rpm/220Nm) / PC7

OP A (1400rpm/50Nm) / PC10 OP E (1200rpm/30Nm) / PC10 OP F (1500rpm/100Nm) / PC10 OP K (2000rpm/220Nm) / PC10

OP A (1400rpm/50Nm) / PC-C1 (straight nozzles) OP E (1200rpm/30Nm) / PC-C1 (straight nozzles) OP F (1500rpm/100Nm) / PC-C1 (straight nozzles) OP K (2000rpm/220Nm) / PC-C1 (straight nozzles)

OP A (1400rpm/50Nm) / PC-D2 (bigger volume) OP E (1200rpm/30Nm) / PC-D2 (bigger volume) OP F (1500rpm/100Nm) / PC-D2 (bigger volume) OP K (2000rpm/220Nm) / PC-D2 (bigger volume)

OP F Ref. passive prechamber / PC7 OP F Ref. passive prechamber / PC10 OP F Ref. passive prechamber / PC-C1 (straight nozzles) OP F Ref. passive prechamber / PC-D2 (bigger volume)

Engine efficiency with lambda sweep in relevant operating points

Paper 18CO-0060

SAE INTERNATIONAL

GasOn: Lean CNG Combustion with ignition chamber

Conclusions• Ignition chamber combustion increases

lean limit• Downscaling from large bore engines to

2.0l engine successful• Engine efficiency of 44% already shown• Challenging aftertreatment system

15Paper 18CO-0060

SAE INTERNATIONAL

GasOn: Lean CNG Combustion with ignition chamber

Thank you

Michael WeißnerVolkswagen AGPostbox 011/17780; 38436 Wolfsburg+49 5361 [email protected]

16Paper 18CO-0060

GASON: A LEAN CNG COMBUSTION FOR HIGHEST ENGINE ...

Documents

Transcript of GASON: A LEAN CNG COMBUSTION FOR HIGHEST ENGINE ...