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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
Overview
Optimization of Direct-Injection H2 Combustion Engine Performance, Efficiency, and Emissions
2
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
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
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)
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)
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
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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-3
-2
-1
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1
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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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-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
0
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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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0
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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
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
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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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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
%
0
1000
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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
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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
0
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6 8 10 12 14 16
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
Optimization of Direct-Injection H2 Combustion Engine Performance, Efficiency, and Emissions
13
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
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)
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 = 4°BTDC(Ignition Timing = 12°BTDC)
Collaboration and coordination
Optimization of Direct-Injection H2 Combustion Engine Performance, Efficiency, and Emissions
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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
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
Summary
Optimization of Direct-Injection H2 Combustion Engine Performance, Efficiency, and Emissions
18
‘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