CNG Technology for Heavy Duty Vehicles_Ulf Lundqvist

8/12/2019 CNG Technology for Heavy Duty Vehicles_Ulf Lundqvist

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CNG Technology for HD Vehicles,CNG Technology for HD Vehicles,Opportunities and ChallengesOpportunities and Challenges

Ulf LundqvistUlf Lundqvist

AVLMTC,AVLMTC, SwedenSweden

AVL ITC , 2007AVL ITC , 2007--0404--2424


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Contents of presentationContents of presentation

Market driversMarket drivers

Boundary conditionsBoundary conditions

CNG combustion conceptsCNG combustion concepts

CNG system requirementsCNG system requirements

Technology routesTechnology routes

EMSEMS

ConclusionsConclusions


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Drivers for gas as a fuel for HDDrivers for gas as a fuel for HD -- enginesengines

Emission legislationEmission legislation

Economical (Fuel cost, Incentives)Economical (Fuel cost, Incentives)

Environmental friendly (Company Image)Environmental friendly (Company Image)

Extremely low PM emissionsExtremely low PM emissions

Reduces COReduces CO22 --emissions by 20emissions by 20--25%25%

NoiseNoise


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Boundary conditions for HD CNGBoundary conditions for HD CNG -- enginesengines

CNGCNG engine based on a diesel engineengine based on a diesel engine

Thermal loadThermal load (Cylinder head, Exhaust manifold,(Cylinder head, Exhaust manifold,

Turbo)Turbo)

Throttled operationThrottled operation (Piston ring package, valve steam(Piston ring package, valve steamsealing)sealing)

Homogeneous combustionHomogeneous combustion (Top land clearance,(Top land clearance,squish area, combustion room, crevices)squish area, combustion room, crevices)

Spark plug installationSpark plug installation

Valve seat wear due to low soot combustionValve seat wear due to low soot combustion

Dedicated engine designDedicated engine designCommonality in partsCommonality in parts


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EmissionEmission targetstargets

Emission Standard in the ETC cycle

0,020,02

N.AN.A

N.AN.A

N.AN.A

PTPT

(g/kWh)(g/kWh)

5,05,01,61,60,780,785,455,45Euro3Euro3

2,02,00,650,650,400,403,03,0EEVEEV

2,02,01,11,10,550,554,04,0Euro5Euro5

3,53,51,11,10,550,554,04,0Euro4Euro4

NOxNOx

(g/kWh)(g/kWh)

CHCH44

(g/kWh)(g/kWh)

NMHCNMHC

(g/kWh)(g/kWh)

COCO

(g/kWh)(g/kWh)

RowRow


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The gas combustion systemThe gas combustion system

NONOxx HCHC

33--Way Cat.Way Cat.OxOx -- Cat.Cat.

LambdaLambda ~1.7~1.711


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Gas concepts for HD applicationsGas concepts for HD applications

MonoMono fuelfuel

Operates only on CNG (LPG)Operates only on CNG (LPG)

BiBi -- fuelfuel

Operates either on CNG or PetrolOperates either on CNG or Petrol

DualDual -- fuelfuel

Operates on CNG and Diesel or only DieselOperates on CNG and Diesel or only Diesel


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StoichiometricStoichiometric Lean BurnLean Burn

BiBi fuelfuel

HD TruckHD Truck

engines withengines withNOx < 1 g/kWhNOx < 1 g/kWh

Spark ignitedSpark ignited Compression ignitedCompression ignited

DualDual fuelfuelMonoMono fuelfuel

HD TruckHD Truck

engines withengines withNOx > 1 g/kWhNOx > 1 g/kWh


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Spark Ignited Stoichiometric MonoSpark Ignited Stoichiometric Mono -- fuelfuel

+ High performance in NA engines+ High performance in NA engines

+ Lambda 1 control strategies already developed for gasoline+ Lambda 1 control strategies already developed for gasoline

engines, however the strategy has to be adopted for gasengines, however the strategy has to be adopted for gas

+ Potential for very low emissions with 3+ Potential for very low emissions with 3--way catalyst, however theway catalyst, however the

catalyst need to be optimized for methanecatalyst need to be optimized for methane

+ High Octane number of CNG gives good fuel economy+ High Octane number of CNG gives good fuel economy

-- High thermal load on engine parts (compared to diesel)High thermal load on engine parts (compared to diesel)

-- Cooled EGR needed for high performanceCooled EGR needed for high performance

-- Hot EGR beneficial for good fuel economy at part loadHot EGR beneficial for good fuel economy at part load

-- Increased pumping losses at part load compared to lean burn.Increased pumping losses at part load compared to lean burn.--Spark plug durability is an issueSpark plug durability is an issue


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Spark Ignited Lean burn MonoSpark Ignited Lean burn Mono -- fuelfuel

++ Thermal load comparable with dieselThermal load comparable with diesel

+ Performance comparable with diesel engines+ Performance comparable with diesel engines

+ Low fuel consumption. (Comparable with diesel)+ Low fuel consumption. (Comparable with diesel)

+ Low part load fuel consumption.+ Low part load fuel consumption.

+ EEV potential with Ox+ EEV potential with Ox cat and advanced control algorithmscat and advanced control algorithms

-- High voltage ignition system requiredHigh voltage ignition system required

-- Need supercharging for high performanceNeed supercharging for high performance

-- Euro 6 emission level will require NOx aftertreatmentEuro 6 emission level will require NOx aftertreatment

--Spark plug durability is an issueSpark plug durability is an issue


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Compression Ignited Lean burn DualCompression Ignited Lean burn Dual -- fuelfuel

+ Flexible, can utilize diesel for long range and gas for+ Flexible, can utilize diesel for long range and gas for

environment and economy reasons.environment and economy reasons.

+ Potential for low emissions due to high lean limit+ Potential for low emissions due to high lean limit

+ Low fuel consumption at part load due to high lean limit+ Low fuel consumption at part load due to high lean limit

+ No issues with spark plug durability+ No issues with spark plug durability

-- If the engine is optimized for CNG operation, the need forIf the engine is optimized for CNG operation, the need for

lower compression ratio will give an increase in fuellower compression ratio will give an increase in fuel

consumption in diesel operating mode. This will also lead toconsumption in diesel operating mode. This will also lead tostartabilitystartability problems in the diesel mode.problems in the diesel mode.

-- Expensive engine compared to an SIExpensive engine compared to an SI engine.engine.

-- Requires control over diesel injection equipment by the EMSRequires control over diesel injection equipment by the EMS

-- Stratified direct injected gas gives high NOxStratified direct injected gas gives high NOx -- emissionsemissions


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The impact of lambda and ignition timing onThe impact of lambda and ignition timing onthermal efficiency, with lean burn at full loadthermal efficiency, with lean burn at full load

34

35

36

37

38

39

40

0 2 4 6 8 10 12 14

Specific NOx (g/kWh)

Thermale

fficiency(%)

Lambda1,65

Lambda1,60

Lambda1,55

Lambda1,50

PmeanPmean = 18 bar, N = 1500 rpm= 18 bar, N = 1500 rpm

IgnitionIgnition timingtiming


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The impact of EGR on thermal efficiency, with leanThe impact of EGR on thermal efficiency, with leanburn at full loadburn at full load

34,535

35,5

36

36,537

37,5

38

38,539

39,5

40

0 2 4 6 8 10 12 14


Thermale

fficiency(%)

Lambda 1,65 No EGR

3% EGR

8% EGR


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01

2

3

4

5

6

78

9

10

0 2 4 6 8 10 12 14


Instabilityofcombustion

(%)

Lambda 1,65 No EGR

3% EGR

8% EGR


The impact of EGR on combustion stability, withThe impact of EGR on combustion stability, withlean burn at full loadlean burn at full load


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0

1

2

3

4

5

6

0 2 4 6 8 10 12 14


SpecificHC(g/kWh) Lambda 1,65 No EGR

The impact of ignition timing on HC emissions,The impact of ignition timing on HC emissions,with lean burn at full loadwith lean burn at full load



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The impact of lambda and ignition timing onThe impact of lambda and ignition timing onthermal efficiency, with lean burn at part loadthermal efficiency, with lean burn at part load

PmeanPmean = 4,5 bar (25%), N = 1500 rpm= 4,5 bar (25%), N = 1500 rpm

23

24

25

26

27

28

29

30

0 2 4 6 8


Thermale

fficiency(%)

Lambda1,65

Lambda1,60

Lambda1,55

Lambda1,50


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The impact of lambda and ignition timing onThe impact of lambda and ignition timing oncombustion stability, with lean burn at part loadcombustion stability, with lean burn at part load

02

4

6

8

10

12

14

16

0 2 4 6 8 10


Instabilityofcombustion

(%)

Lambda1,65

Lambda1,60

Lambda1,55

Lambda1,50

PmeanPmean = 4,5 bar (25%), N = 1500 rpm= 4,5 bar (25%), N = 1500 rpm


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The impact of EGR on thermal efficiency, withThe impact of EGR on thermal efficiency, withlean burn at part loadlean burn at part load

PmeanPmean

= 4,5 bar (25%), N = 1500 rpm= 4,5 bar (25%), N = 1500 rpm

23

25

27

29

0 2 4 6


Thermale

fficiency(%)

Lambda 1,65 No EGR

3% EGR

8% EGR


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Fuel injection equipment for HD CNGFuel injection equipment for HD CNGenginesengines

Carburetor / MixerCarburetor / Mixer

+ Excellent mixing between gas and air+ Excellent mixing between gas and air

+ Low cost+ Low cost

+ Robust+ Robust

-- Poor transient controlPoor transient control

-- Deficient fuel cut capabilitiesDeficient fuel cut capabilities

-- Fuel quality adaptation complicatedFuel quality adaptation complicated


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Single Point injectionSingle Point injection

+ Good mixing between gas and air+ Good mixing between gas and air

+ Low demand on injector quantity range.+ Low demand on injector quantity range.(Multiple arrangement possible)(Multiple arrangement possible)

-- Transient controlTransient control

-- Fuel cut capabilitiesFuel cut capabilities


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Multipoint port fuel injectionMultipoint port fuel injection

+ Excellent fuel cut capabilities+ Excellent fuel cut capabilities

+ Excellent transient control+ Excellent transient control

-- Mixing of gas and air could be an issueMixing of gas and air could be an issue

-- Higher demand on injected quantity rangeHigher demand on injected quantity rangeof the injectorsof the injectors


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General requirements on gas injectorsGeneral requirements on gas injectors

Low pressure (approx. 2 bar) enables full usageLow pressure (approx. 2 bar) enables full usageof the CNG tank.of the CNG tank.

For port injection arrangements sufficientFor port injection arrangements sufficientinjected quantity range of the injector isinjected quantity range of the injector isessentialessential

DurabilityDurability

Operation in cold conditionsOperation in cold conditions


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General requirements on gas pressureGeneral requirements on gas pressureregulatorregulator

LowLow hysteresishysteresis

Precise pressure control (Can bePrecise pressure control (Can becompensated by the control system)compensated by the control system)

DurabilityDurability

Operation in cold conditionsOperation in cold conditions


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Spark ignition system for HD CNGSpark ignition system for HD CNGenginesengines

General requirements on ignition systems for HD enginesGeneral requirements on ignition systems for HD engines

Generally a commercial vehicle user expects longer serviceGenerally a commercial vehicle user expects longer serviceintervals than passenger car userintervals than passenger car user

CNG lacks cooling effect in rich mode unlike liquid fuels whichCNG lacks cooling effect in rich mode unlike liquid fuels whichleads to higher thermal load on the spark plug. (Stoichiometricleads to higher thermal load on the spark plug. (Stoichiometricengines)engines)

The high octane number of CNG permits a high compressionThe high octane number of CNG permits a high compressionratio which gives higher ignition voltage. This is somewhatratio which gives higher ignition voltage. This is somewhatcompensated with an earlier optimum ignition timing.compensated with an earlier optimum ignition timing.(Stoichiometric engine)(Stoichiometric engine)

In lean burn operation the torque loss is successfullyIn lean burn operation the torque loss is successfullycompensated withcompensated with turbochargingturbocharging. However the increased boost. However the increased boostpressure in combination with the required late spark timing forpressure in combination with the required late spark timing forlow NOx gives extremely high ignition voltage.low NOx gives extremely high ignition voltage.

S k i i i f HD CNG


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Spark ignition system for HD CNGSpark ignition system for HD CNGenginesengines

OC12 Tndspnning med olika gnistgap

fullast

0

5

10

15

20

25

30

35

40

45

50

0 500 1000 1500 2000 2500

Varvtal [n/min]

S

pnning

[V]

0,7 mm

0,6 mm

0,4 mm

Ignition voltage as function ofIgnition voltage as function of

engine speed and spark gapengine speed and spark gap

Engine speedEngine speed

Ignition

Ignitionvo

ltage

vo

ltage((kVkV))

f f C GE h t ft t t t f HD CNG


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Exhaust aftertreatment for HD CNGExhaust aftertreatment for HD CNGenginesengines

Spark Ignited Stoichiometric MonoSpark Ignited Stoichiometric Mono fuelfuel

ThreeThree way catalystway catalyst

Spark Ignited Lean burn MonoSpark Ignited Lean burn Mono fuelfuel

Oxidation catalyst at NOx > 1 g/kWhOxidation catalyst at NOx > 1 g/kWh

SCR at NOx < 1g/kWhSCR at NOx < 1g/kWh

Compression Ignited Lean burn DualCompression Ignited Lean burn Dual fuelfuel

Oxidation catalyst at NOx > 1 g/kWhOxidation catalyst at NOx > 1 g/kWh

SCR at NOx < 1g/kWhSCR at NOx < 1g/kWh


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Demands on after treatment systems forSpark Ignited Stoichiometric MonoSpark Ignited Stoichiometric Mono fuelfuel

HD gas engineHD gas engine

Adopted for Methane

High conversion rate for CH4

Low light off temperature

High durability

Wide lambda window

Three Way Catalyst for HC, CO and NOx


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Demands on after treatmentsystems Lean burn gas engineLean burn gas engine

High conversion rate

Low light off temperature

High durability

Oxidation catalyst for HC and CO

Selective Catalytic Reduction for NOx

Adopted for Methane

Wide temperature window

Combination with Ox cat


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Lean Burn CatalystLean Burn Catalyst

LIGHTLIGHT--OFF PERFORMANCE FOR 1000 h ENGINE AGED CATALYST (KEMIRA)OFF PERFORMANCE FOR 1000 h ENGINE AGED CATALYST (KEMIRA)

0

20

40

60

80

100

150 200 250 300 350 400 450 500

CO METHANE ETHANE PROPANE ACETALDEHYDE

CONVERSION, %CONVERSION, %

TEMPERATURE, CTEMPERATURE, C

CATALYST: KLN3 Pt:Pd 1:4 250 g/ftCATALYST: KLN3 Pt:Pd 1:4 250 g/ft


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Three Way Catalyst for gas engines

50

100

Con

versionEfficiency(%

)

1.00.96 1.04

Lean SideRich Side

0

CO

THCNOx

CNG Window

Gasoline Window


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Measures to decrease engine out HCMeasures to decrease engine out HC -- emissionsemissions

Measures to decrease engine out HCMeasures to decrease engine out HC emissionsemissions

Valve timingValve timing

Piston bowl geometryPiston bowl geometryOptimization of ring packageOptimization of ring package

Eliminating crevices and dead volumes.Eliminating crevices and dead volumes.


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Installation of the fast fid measuringInstallation of the fast fid measuringprobe in the exhaust port.probe in the exhaust port.


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PP

MHC

PP

MHC

TimeTime

Measurement of crank angel resolved HCMeasurement of crank angel resolved HC

emissions with 4 different camshaftsemissions with 4 different camshafts

Fast FIDFast FID

Std. CamStd. CamCam. 1Cam. 1 Cam. 3Cam. 3

Cam. 2Cam. 2

EVOEVO


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Fast catalyst deactivation in transient drivingFast catalyst deactivation in transient driving


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Reason for fast catalyst deactivationReason for fast catalyst deactivation

Misfiring during motoring conditionsMisfiring during motoring conditions

Measures for eliminating misfireMeasures for eliminating misfire

Fuel cut under a certain inlet manifold pressureFuel cut under a certain inlet manifold pressure

and over a certain engine speedand over a certain engine speed

Note:Note:

Fuel cut is also needed for good driving quality,Fuel cut is also needed for good driving quality,

but it requires multipoint injection system.but it requires multipoint injection system.

Fast catalyst deactivation in transient drivingFast catalyst deactivation in transient driving


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Technology routes for HD CNG enginesTechnology routes for HD CNG engines

Engine concept for Euro 3Engine concept for Euro 3

Lean burnLean burn

Oxidation catalyst requiredOxidation catalyst required

Closed loop control required to protect the catalyst fromClosed loop control required to protect the catalyst frommisfire during fuel quality variationsmisfire during fuel quality variations

Fuel cut during deceleration required in order to preventFuel cut during deceleration required in order to preventmisfire to damage the catalystmisfire to damage the catalyst

Wide band lambdaWide band lambda sondsond

High voltage ignition systemHigh voltage ignition system


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Engine concept for Euro 5 and EEVEngine concept for Euro 5 and EEV

Lean burnLean burn

Oxidation catalyst requiredOxidation catalyst required

Closed loop control required to protect the catalyst from misfirClosed loop control required to protect the catalyst from misfireeduring fuel quality variations. Due to the small margin towardsduring fuel quality variations. Due to the small margin towardslean out misfire, the lambda control is much more critical thanlean out misfire, the lambda control is much more critical thanin the Euro 3 case.in the Euro 3 case.

Fuel cut during deceleration required in order to prevent misfirFuel cut during deceleration required in order to prevent misfireeto damage the catalystto damage the catalyst




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Engine concept for Euro 6 (Stoichiometric)Engine concept for Euro 6 (Stoichiometric)

Stoichiometric combustionStoichiometric combustion

Cooled EGRCooled EGR

Closed loop lambda control with catalyst lightClosed loop lambda control with catalyst light--off strategies.off strategies.

ThreeThree way catalyst optimized for methaneway catalyst optimized for methane



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Engine concept for Euro 6 (lean burn)Engine concept for Euro 6 (lean burn)

Lean burnLean burn

SCR (Selective catalytic reduction)SCR (Selective catalytic reduction)

Closed loop control required to protect the catalyst fromClosed loop control required to protect the catalyst frommisfire during fuel quality variations.misfire during fuel quality variations.

Fuel cut during deceleration required in order to preventFuel cut during deceleration required in order to preventmisfire to damage the catalystmisfire to damage the catalyst




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EMS requirementsEMS requirements

The lean burn gas engine need an advanced EMS toThe lean burn gas engine need an advanced EMS to

Provide the engine with optimized lambda andProvide the engine with optimized lambda and

Ignition timing in the complete speed torqueIgnition timing in the complete speed torqueenvelope, in a closed loop mannerenvelope, in a closed loop manner

Compensate for different fuel qualities stillCompensate for different fuel qualities still

fulfilling performance and emission demandsfulfilling performance and emission demands Enhance drivability with EEnhance drivability with E--gas and boostgas and boost

controlcontrol

Enable fuel cut for enhanced drivability andEnable fuel cut for enhanced drivability andcatalyst handlingcatalyst handling

Torque control improvement with ignition andTorque control improvement with ignition andlambda strategieslambda strategies


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Gas engine EMSGas engine EMS

Fuel Injectors

WB O2 sensor

Engine

Engine Speed

Temperature inputs

Manualy PTO

Ignition Control

Fuel Control

ETC

Fuel

Control

Engine Speed

Mass Air Flow

WB O2 sensor

Ignition

Control

Engine Speed

Mass Air Flow

Knock sensor

Idle Control and PTO

Idle Control and PTO

6*Ignition coils

6*Fuel injectors

Ignition Coils

Lambda

Knock

Knock

Knock

ETC MAF

Crank position 58X

Electronic Throttle Control

Mass Air Flow

Engine Speed

Temperature sensors

Pressure sensors

CNG EMS for WT 615

CAM position

CAM

Idle

Control

& PTO

Gas engine EMSGas engine EMS

Gas engineGas engine

EMSEMSStd. engineStd. engine

EMSEMS


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With cooled EGR, temperature limit forWith cooled EGR, temperature limit for

turbocharger can be met even withturbocharger can be met even withstoichiometric operation at full load.stoichiometric operation at full load.

The higher temperature level, as compared toThe higher temperature level, as compared to

the diesel engine, requires special efforts to allthe diesel engine, requires special efforts to allexhaust gas related components. (Without EGR)exhaust gas related components. (Without EGR)

The ThreeThe Three--Way catalyst is available but need toWay catalyst is available but need to

be optimized for methane operation.be optimized for methane operation. The thermal efficiency with stoichiometricThe thermal efficiency with stoichiometric

operation using EGR is lower than with leanoperation using EGR is lower than with leanoperation, especially at part load.operation, especially at part load.

Conclusions (2)Conclusions (2)

Stoichiometric operationStoichiometric operation


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Gas Engine ServicesGas Engine Services

Design evaluation of existing gas enginesDesign evaluation of existing gas engines

Evaluation of different gas systems suppliersEvaluation of different gas systems suppliers

Development of a tailored gas EMSDevelopment of a tailored gas EMS

Conversion of existing diesel engine designsConversion of existing diesel engine designsfor operation on gaseous fuelsfor operation on gaseous fuels

Design of new gas enginesDesign of new gas engines

Design of high turbulence piston bowlsDesign of high turbulence piston bowls

Application of gas supply systemsApplication of gas supply systems

Manufacture of prototype enginesManufacture of prototype engines

Engine development and optimization onEngine development and optimization ontransient test bedstransient test beds


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Thank you for your attention!Thank you for your attention!

M.scM.sc. Ulf Lundqvist. Ulf LundqvistAVL MTCAVL MTC

Key Account ManagerKey Account Manager

Phone: +46 (0)8 500 65 696Phone: +46 (0)8 500 65 696

Mobile: +46 (0)70 8 26 79 11Mobile: +46 (0)70 8 26 79 11

Fax: +46 (0)8 500 283 28Fax: +46 (0)8 500 283 28

EE--mail:mail: [email protected]@avlmtc.com

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CNG Technology for Heavy Duty Vehicles_Ulf Lundqvist