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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
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Overview
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
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Objectives Project relevance
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
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Milestones
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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)
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Approach Integration and Collaboration
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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)
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Technical accomplishmentsOverview
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
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Exhaust gas recirculation (EGR)Setup and goals
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
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60
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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
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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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-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
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
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Optimizing engine geometryBasics
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
35
40
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50
55
60
65
70
6 8 10 12 14 16 18 20
Effic
ienc
y
v[%
]
Compression ratio [-]
=1=1,2=1,4=1,6=1,8=2=2,5=3
=5=10
HydrogenConstant volume combustionAir-aspiratingp0=1 bara=1
Gasoline =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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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
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
[%]
Combustion phasing - 50%MFB [CA ATDC]
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 [-]
SOI=140 CA BTDCSOI=120 CA BTDCSOI=100 CA BTDCSOI=80 CA BTDC
2000 RPM 8 bar IMEP
Base engineOptimizedengine
Port fuel injectionLoad sweep atwide open throttle
Optimizing engine geometryEmissions results
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
]
Combustion phasing - 50%MFB [CA ATDC]
SOI=140 CA BTDCSOI=120 CA BTDCSOI=100 CA BTDCSOI=80 CA BTDC
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 (~0.32)
14.3 bar IMEP (~0.4)
3000 RPMSOI=140 CA BTDCpIntake=2 barpExhaust=1.8 bar
Optimizing combustion systemCurrent performance
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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)
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Optimizing combustion system3D-CFD optimization of injector
nozzle
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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)
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Optimizing combustion system3D-CFD optimization of injector
nozzle
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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Optimized nozzle (2 hole)Standard nozzle (5 hole)
CA = 4BTDC(Ignition Timing = 12BTDC)
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Collaboration and coordination
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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Collaboration with Sebastian Kaisers team at Sandia National
LaboratoriesCoordination of investigated operating
conditionsOptical results used for validation of 3D-CFD
simulation
Coordination with Dan Flowers 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
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Future work
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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
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Summary
Optimization of Direct-Injection H2 Combustion Engine
Performance, Efficiency, and Emissions
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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 EmissionsDOE Sponsor: Gurpreet Singh
OverviewObjectives Project relevanceMilestonesApproach Integration
and CollaborationTechnical accomplishmentsOverviewExhaust gas
recirculation (EGR)Setup and goalsExhaust gas recirculation
(EGR)Efficiency/emissions trade-offExhaust gas recirculation
(EGR)Comparison to water injectionOptimizing engine
geometryBasicsOptimizing engine geometryEfficiency
resultsOptimizing engine geometryEmissions resultsOptimizing
combustion systemCurrent performanceOptimizing combustion
system3D-CFD optimization of injector nozzleOptimizing combustion
system3D-CFD optimization of injector nozzleCollaboration and
coordinationFuture workSummarySupplementation slides
separatorResponse to previous years reviewers commentsJournal
papers and book chaptersPeer-reviewed publicationsCritical
assumptions and issues