Optimization of Direct-Injection H2 Combustion Engine ......Optimization of Direct-Injection H2...

Optimization of Direct-Injection H2 Combustion Engine Performance, Efficiency, and Emissions

DOE Sponsor: Gurpreet Singh

Thomas Wallner, Ph.D. (Principal Investigator)

Riccardo Scarcelli, Ph.D., Hermann ObermairArgonne National Laboratory

2010 DOE Merit Review June 8, 2010

Washington, D.C. Project ID: ACE009

This presentation does not contain any proprietary, confidential, or otherwise restricted information

Overview


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Timeline Project start: 2005

Project end: Ongoing project

Budget Funding in FY09: 500k$

Funding in FY10: 500k$

Funding for FY11: 500k$ request

Barriers Understand, characterize and

optimize hydrogen engines with focus on direct injection

Evaluate in-cylinder emissions reduction techniques

Improve injector design

Partners Industrial partners: Ford, Westport

Collaborator: Sandia and Lawrence Livermore National Laboratories

International team members: BMW, Graz University of Technology, Ghent University

Objectives – Project relevance


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Provide a clean and efficient, readily available tool for utilization of hydrogen as an energy carrier

Overcome the trade-off between engine efficiency and NOx emissions in hydrogen direct injection (DI) operation to reach 2010 peak brake thermal efficiency goal of 45% with minimal emissions penalty (Tier 2, Bin 5 or better)

Evaluate the NOx emissions reduction potential of in-cylinder measures (e.g. water injection, EGR) in hydrogen DI operation

Assess the impact of injector nozzle geometry and injector location/orientation and develop optimized configurations

Investigate the potential of multiple injection strategies

Milestones


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3-D CFD simulation validated using optical results from Sandia National Laboratories (03/2009)

NOx emissions reduction potential of EGR evaluated (07/2009)

Analysis of individual optimization measures completed (09/2009)

Upgrade to optimized engine geometry finished (12/2009)

Piezo-actuated DI injectors implemented (01/2010)

Baseline performance comparison of optimized engine geometry completed (03/2010)

Efficiency mapping of optimized engine configuration with Piezoinjectors started (04/2010)

Approach – Integration and Collaboration


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3-D CFDsimulation

H2 injector development

(Westport)

Opticalengine

(Sandia)

Injector nozzledesign

Single-cylinder research engine

Hydrogen vehicle program

(Ford)

Simulation, analysis(Livermore, Ghent)

Technical accomplishmentsOverview


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In-cylinder emissions reduction Efficiency/emissions trade-off with

exhaust gas recirculation (EGR)

Assessment of EGR versus water injection

Optimized H2 DI combustion engine Analysis of efficiency improvement with

optimized engine geometry

Impact of optimization on emissions

Improved injector design Validated 3D-CFD simulation used to

predict mixture stratification

Exhaust gas recirculation (EGR)Setup and goals


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Exhaust gas recirculation Setup using automotive EGR valve

Intake and exhaust pressure individually adjustable

Integrated automotive EGR cooler

Approach Evaluate EGR rate determination

strategies in hydrogen operation

Assessment of impact of EGR rates and temperatures on

NOx emissions

Engine efficiency

Combustion stability

0

15

30

45

60

75

90

-3

-2

-1

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1

2

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0 5 10 15 20 25 30 35 40

10 -

90 %

MFB

[oC

A]

CO

V IM

EP [%

]

EGR rate [%]

4 bar IMEP8 bar IMEP

2000 RPMUncooled EGR


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Exhaust gas recirculation (EGR)Efficiency/emissions trade-off

Increasing EGR rates lower peak cylinder pressures and maximum rate of heat release ultimately reducing combustion temperatures

Increasing EGR rates have negligible effect on combustion stability

Increasing EGR rates result in increased combustion duration

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140

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-20

-10

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-10 -5 0 5 10 15 20 25 30 Hea

t rel

ease

rate

[kJ/

m3°

CA

]

Cyl

inde

r pre

ssur

e [b

ar]

Crank angle [°CA]

0 % EGR16 % EGR20 % EGR25 % EGR

2000 RPM8 bar IMEP

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1000 2 4 6 8 10 12

NO

x em

issi

ons

redu

ctio

n [%

]

Indicated thermal efficiency loss [%]

EGR 4 barEGR 8 barH2O 4 barH2O 8 bar

2000 RPM

Exhaust gas recirculation (EGR)Comparison to water injection


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0 5 10 15 20 25 30 35 40

NO

x em

issi

ons

[ppm

]

Indi

cate

d th

erm

al e

ffici

ency

[%]

EGR rate [%]

4 bar IMEP8 bar IMEP

2000 RPMUncooled EGR 60 % NOx emissions reduction with

EGR with respective loss in indicated thermal efficiency below 1 %

NOx emissions in single digits achievable with efficiency penalty

EGR equally effective for NOx emissions reduction as water injection at medium load (40% with 1% efficiency loss)

50% emissions reduction with water injection results in 2% efficiency loss at high engine load - EGR is superior

Optimizing engine geometryBasics


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Influence of

Compression ratio

Bore/stroke ratio

Affecting

Combustion

Wall heat transfer

Parameter Unit Base engine

Optimized engine

Bore mm 89 89Stroke mm 79.5 105.8Bore/stroke ratio - 1.12 0.84Displacement l 0.5 0.66Peak cylinder pressure bar ~120 ~120-160

Compression ratio - 11.5:1 12.9:1

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6 8 10 12 14 16 18 20

Effic

ienc

y η

v[%

]

Compression ratio ε [-]

λ=1λ=1,2λ=1,4λ=1,6λ=1,8λ=2λ=2,5λ=3

λ=5λ=10

HydrogenConstant volume combustionAir-aspiratingp0=1 barλa=1

Gasoline λ=1

~2%

Compression ratio increase expected to improve efficiency by ~2%

Change in B/S ratio from 1.12 to 0.84 expected to increase efficiency by ~3%*

* Z.S. Filipi and D.N. Assanis ‘The Effect of the Stroke-to-Bore Ratio on Combustion, Heat Transfer and Efficiency of a Homogeneous Charge Spark Ignition Engine of Given Displacement ‘ International Journal of Engine Research, 1:2, 191-208, 2000.

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35

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45

4 6 8 10 12 14 16

Indi

cate

d th

erm

al e

ffici

ency

[%]

Combustion phasing - 50%MFB [°CA ATDC]

SOI=140° CA BTDCSOI=120° CA BTDCSOI=100° CA BTDCSOI=80° CA BTDC

2000 RPM 8 bar IMEPBase engine

Optimized engine

Optimizing engine geometryEfficiency results


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Indicated thermal efficiency results at 2000 RPM and different loads

Sweep of start of injection and spark timing (combustion phasing)

Significant efficiency improvement (~5-7%) with optimized geometry independent of engine load

Start of injection relevant for further optimization

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2 4 6 8 10 12 14 16

Indi

cate

d th

erm

al e

ffici

ency

[%]


SOI=140° CA BTDCSOI=120° CA BTDCSOI=100° CA BTDCSOI=~80° CA BTDC

2000 RPM 4 bar IMEPBase engine

Optimized engine

~5-7

%

~5-7

%

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7000

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9000

0.5 0.55 0.6 0.65 0.7 0.75

NO

x em

issi

ons

[ppm

]

Relative fuel/air ratio [-]


2000 RPM 8 bar IMEP

Base engineOptimizedengine

Port fuel injectionLoad sweep atwide open throttle

Optimizing engine geometryEmissions results


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0

500

1000

1500

2000

2500

3000

3500

4000

4500

4 6 8 10 12 14 16

NO

x em

issi

ons

[ppm

]



2000 RPM 8 bar IMEP

Base engine

Optimized engine

NOx emissions only critical emissions component in hydrogen operation

Tremendous NOx emissions reduction (~50%) with optimized geometry

Strong correlation of NOx emissions with relative fuel/air ratio

Start of injection critical for NOx emissions optimization

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NO

x em

issi

ons

[ppm

]

Indi

cate

d th

erm

al e

ffici

ency

[%]

Combustion phasing 50% MFB [°CA ATDC]

11 bar IMEP (ɸ~0.32)

14.3 bar IMEP (ɸ~0.4)

3000 RPMSOI=140 °CA BTDCpIntake=2 barpExhaust=1.8 bar

Optimizing combustion systemCurrent performance


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5-hole injector/central location

100 bar injection pressure

Simulated turbocharging based on hydrogen PFI turbo results

Operation limited due to peak cylinder pressure

Only early DI possible (SOI=140) – later, more efficient SOIs unstable

Brake thermal efficiency (BTE) estimated based on assumed friction of 0.70 bar (FEV data)

Optimizing combustion system3D-CFD optimization of injector nozzle


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Speed 3000 RPM Load 9 bar IMEPInjector type Piezo Injection pressure 100 barStart of injection 110 CA BTDC Injection duration 47 CA (2.6 ms)Intake pressure 2 bar Exhaust pressure 1.8 bar

Optimized nozzle (2 hole)Standard nozzle (5 hole)

Optimizing combustion system3D-CFD optimization of injector nozzle


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Optimized nozzle (2 hole)Standard nozzle (5 hole)

CA = 4°BTDC(Ignition Timing = 12°BTDC)

Collaboration and coordination


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Collaboration with Sebastian Kaiser’s team at Sandia National LaboratoriesCoordination of investigated operating conditionsOptical results used for validation of 3D-CFD simulation

Coordination with Dan Flower’s team at Lawrence Livermore National Laboratory

Currently evaluating/coordinating activities

Contract with Westport Innovations Inc.Subcontract to supply Piezo injectors, drivers and fabricate nozzles

Guidance and support from Ford Motor CompanyInput on test plan and activitiesIn-kind support (engine hardware)

International collaborationsBMW – Mutual updates on goals, progress and research directionsGraz University of Technology – Pre-Doctoral appointee currently working at ArgonneGhent University – Informal collaboration for data analysis

Future work


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Mixture formation and combustion optimization Finish performance mapping of upgraded engine configuration

Optimize injection parameters with 3D-CFD support

Test 1st generation of Piezo injector nozzles

Assess impact of multiple injection strategies employing Piezo-actuated injectors on performance, efficiency and emissions

Test further generations of CFD-optimized injector nozzle designs and injection strategies

Hydrogen engine system optimization Combine optimized injection parameters (e.g. multiple injection) with in-

cylinder emissions reduction measures (e.g. un-cooled EGR) Develop injection strategies for optimized system performance

Summary


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‘Optimization of Direct-Injection H2 Combustion Engine Performance, Efficiency, and Emissions’ project is focused on providing a clean and efficient, readily available tool for utilization of

hydrogen as an energy carrier

achieving 45% brake thermal efficiency with minimal NOx emissionsMajor accomplishments in FY2010 include

demonstration of 50% NOx emissions reduction with less than 1% efficiency penalty

5-7% efficiency improvement with simultaneous 50% NOx emissions reduction through optimized engine geometry and faster injectors

3D-CFD simulation established as powerful tool for efficient optimization 45% brake thermal efficiency achievable with turbo-charged H2 DI engine

Future work includes optimization of injection parameters (nozzle geometry, injection strategy) development of optimized hydrogen combustion engine system

Optimization of Direct-Injection H2 Combustion Engine Performance, Efficiency, and Emissions��DOE Sponsor: Gurpreet Singh OverviewObjectives – Project relevanceMilestonesApproach – Integration and CollaborationTechnical accomplishments�OverviewExhaust gas recirculation (EGR)�Setup and goalsExhaust gas recirculation (EGR)�Efficiency/emissions trade-offExhaust gas recirculation (EGR)�Comparison to water injectionOptimizing engine geometry�BasicsOptimizing engine geometry�Efficiency resultsOptimizing engine geometry�Emissions resultsOptimizing combustion system�Current performanceOptimizing combustion system�3D-CFD optimization of injector nozzleOptimizing combustion system�3D-CFD optimization of injector nozzleCollaboration and coordinationFuture workSummarySupplementation slides separatorResponse to previous years reviewers’ commentsJournal papers and book chaptersPeer-reviewed publicationsCritical assumptions and issues

Optimization of Direct-Injection H2 Combustion Engine ......Optimization of Direct-Injection H2...

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