A University Consortium on Efficient and Clean High ...
Transcript of A University Consortium on Efficient and Clean High ...
2012 DOE Merit Review - 1MITUCBUM Project ID: ACE019
A University Consortium on Efficient and CleanHigh-Pressure, Lean Burn (HPLB) Engines
University of Michigan (UM):Margaret Wooldridge (PI), Dennis N. Assanis (PI),
Aris Babajimopoulos, Stani V. Bohac, Zoran S. Filipi, Hong G. Im, George A. Lavoie
Massachusetts Institute of Technology (MIT):Wai Cheng
University of California, Berkeley (UCB):Jyh-Yuan Chen, Robert Dibble
DOE Merit ReviewWashington DC, May 2012
DOE Project DE-EE0000203
This presentation does not contain any proprietary, confidential, or otherwise restricted information
2012 DOE Merit Review - 2MITUCBUM Project ID: ACE019
Background
History:• 2002 – 2005 Consortium on HCCI – Basic
understanding• 2006 – 2009 Consortium on LTC – Beyond
HCCI: expanded to other combustion modes
• 2010 – 2012 High Pressure Lean/Dilute Burn – Focus on fuel economy
500
1000
1500
2000
2500
3000
500 1000 1500TB
(K)
TU (K) at TDC
1.00.8
0.6
0.4
0.2
0.0
Φ’
EARLYCOMB
KNOCKLIMIT
BULKQUENCH
AUTOIGN
SI
HCCI
NOx
SACI
FLAMELIMIT
HPLB
CURRENTSI AUTOS
Lavoie, G., Martz, J., Wooldridge, M., and Assanis, D., (2010) “A Multi-Mode Combustion Diagram for Spark Assisted Compression Ignition,” Combustion and Flame, 157, pp. 1106-1110.
2012 DOE Merit Review - 3MITUCBUM Project ID: ACE019
Overview
• TIMELINE– Start - Oct 2009– Finish – Dec 2012– 70% completed
• BARRIERS ADDRESSED– Improved fuel economy in light
duty gasoline engines– Fundamental knowledge of
advanced engine combustion
• BUDGET– Total Funding - $3,000k– Rec’d FY10 - $1,000k– Rec’d FY11 - $ 1,000k– Rec’d FY12 - $ 830k
• PARTNERS– Universities – UCB, MIT– Collaborations – SNL, LLNL,
ORNL, ANL– Industrial – GM, Conoco-
Phillips, Ford
2012 DOE Merit Review - 4MITUCBUM Project ID: ACE019
Objectives and Relevance
DOE VTP Technical Target:• Demonstrate path to achieve 45% peak engine efficiency with
25 - 40% potential vehicle fuel economy (FE) gain
Project Objectives:Explore advanced dilute, high pressure combustion modes and fuel properties as enablers to achieve FE targets
1. Develop analytical link between engine combustion results and potential in-vehicle FE gains
2. Investigate benefits of stratification3. Explore multi-mode combustion: Spark Assisted Compression
Ignition (SACI), and Microwave Assisted Spark Plug (MWASP)4. Determine potential of novel fuel properties for improved FE
2012 DOE Merit Review - 5MITUCBUM Project ID: ACE019
Approach
TASK 1.Fuel Efficiency of Advanced HPLB Cycles (UM)– Develop analytical link between combustion and fuel
economy benefits– Assess potential FE gains of advanced combustion cycles
TASK 2.Investigate the benefits of stratification (UM, MIT)– DNS and combustion subgrid scale modeling of mixing effects– RCM and engine experiments
TASK 3.Advanced multi-mode combustion (UM, UCB)– Metal engine, optical engine, RCF Experiments– SACI, MWASP– CFD – flamelet+AI TASK 4.
Fuel properties for optimal fuel economy (UM, MIT)– Metal and optical engine and RCF experiments– Explore NTC, ON, Gasoline/ethanol blends, alkanes, esters, etc.– Chemical kinetic models
Path to in-vehicleFE improvement
MODELS,EXPERIMENTS
ANALYTICALTOOLS
2012 DOE Merit Review - 6MITUCBUM Project ID: ACE019
Technical Accomplishments and Progress
Technical Accomplishmentsand Progress
2012 DOE Merit Review - 7MITUCBUM Project ID: ACE019
• Goals
– Develop analytical link between combustion and fuel economy benefits
– Assess potential FE gains of advanced combustion cycles
• Approach
– Use simple, thermodynamically consistent model of engine
– Assume combustion is possible at all conditions
– Evaluate 6 engine-combustion strategies to produce engine maps
– Estimate vehicle fuel economy with drive cycle simulation
Task 1. Fuel Efficiency of Advanced HPLB Cycles (UM)
20
30
40
50
0 10 20 30 40η _
brak
e (%
)BMEP (bar)
CR = 12; RPM = 2000
1.01.5
2.0 2.5 3.0
P_in (bar)
etab_v_bmep_AIR_TC50_EIVC_Throt
HCCI ADV.COMB
SI
4
SI–TC (Φ=1)
LEAN-SI-TC
SI–NA, Throttled (Φ=1)
ADV-NA
3
HCCI–TC
1
2
56
ADV–TC
INT EXH
I.C.
EGR
C TηC ηTηmech
GT-Power model of turbocharged engine
• Fixed burn duration (25°)
• Ideal T/C (OTE=50%)
2012 DOE Merit Review - 8MITUCBUM Project ID: ACE019
• Accomplishments/Results– Determined that the benefits
of advanced combustion and boosting with downsizing appear to be relatively independent
– Best results obtained by combining both strategies
– Fuel economy gains of up to 58% are possible
Task 1. Fuel Efficiency of Advanced HPLB Cycles (UM)
0
10
20
30
40
50
Stoich-SI NA 3.3L
Advanced NA
3.3 L
HCCI TC
3.3 L
Stoich-SI TC
1.4 L
Lean-SI TC
1.4 L
Advanced TC
1.4 L
Fuel
Eco
nom
y (M
PG)
Combined City/Hwy Fuel Economy
1 2 3 4 5 6
+ 58%+ 44%
+ 36%+ 23%+ 23%
+ 0%
GAIN OVER BASE
CASE CombustionMode
AirHandling Size City/Hwy
(mpg)FE
GAIN
1 Stoich-SI NA 3.3 L 25.4 BASE
2 Advanced NA 3.3 L 31.3 23%
3 HCCI TC 3.3 L 31.2 23%
4 Stoich-SI TC 1.4 L 34.5 36%
5 Lean-SI TC 1.4 L 36.7 44%
6 Advanced TC 1.4 L 40.3 58%
Impact• Analysis confirms advantages of
advanced (mid dilution) combustion strategies under high boost conditions
Lavoie, G. A., Ortiz-Soto, E., Babajimopoulos, A., Martz, J., Assanis, D.N. (2012) Thermodynamic sweet spot for high efficiency, dilute boosted gasoline engine operation, submitted to Int. J. Engine Res.
2012 DOE Merit Review - 9MITUCBUM Project ID: ACE019
High fidelity modeling: effects of small scale mixing on autoignition (UM)
– Understand effects of stratification in Φ, EGR and T on autoignition
– Incorporate effects in engine modeling– Guide interpretation of experimental
observations in RCF, RCM, and optical and metal engines
Task 2. Investigate the benefits of stratification (UM, MIT)
Experiments on large scale stratification (MIT)
– RCM ignition delay studies integrating heat transfer and using commercial fuels
– Experiments with gasoline in a small bore diesel engine under LTC conditions
2012 DOE Merit Review - 10MITUCBUM Project ID: ACE019
• Goals:
– Understand small scale (subgrid) turbulence and mixing effects
– Incorporate in CFD modeling– Interpret experimental data
• Accomplishments/Results:– Modeled H2-Air turbulent
combustion with prescribed T and Φ variation showing effect on heat release using DNS
– Developed subgrid models
Task 2. Modeling small scale turbulence effects on autoignition (UM)
Tem
pera
ture
(K)
Φ
Nor
mal
ized
Hea
t Rel
ease
Rat
e
Impact:• Bulk gas turbulent fluctuations affecting
heat release are not currently modeled by RANS calculations
Constant Φ
UncorrelatedT, Φ
Negativelycorrelated
T and Φ
CASE A
CASE B
CASE C
Φ
Φ
Gupta, S. Keum, S. H., Im, H. G., 2012, “Modeling of Scalar Dissipation Rates in Flamelet Models for HCCI Engine Simulation,” 50th AIAA Aerospace Sciences Meeting, Nashville, Tennessee, January 9-12, 2012.
2012 DOE Merit Review - 11MITUCBUM Project ID: ACE019
• Goals:– Acquire RCM ignition delay data for
gasoline for varying EGR and Φ– Apply to gasoline-fueled diesel engine
in stratified mode• Accomplishments/Results
– Rapid Compression Machine • Ignition delay measurements suggest
that the sensitivity to Φ and EGR depends on combustion regime; NTC regime is most sensitive
– Engine experiments• Outside NTC region: stratification
increases heat release, decreases maximum load
Task 2. Experimental studies of the benefits of large scale stratification (MIT)
0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.60.1
1
10
100
1100 1000 900 800 700 600
Φ=0.3
Igni
tion
Dela
y (m
s)
1000/T (oK-1)
Φ=0.5 Φ=0.7
Temperature (oK)
0.75 kmol/m3
(P=50 bar @T=800oK)No dilution
NTC Region Low THigh T
Ignition timerequirement
Boost
EGR
Impact:•
INCR. STRAT.
RCM DATA
DI GASOLINE IN DIESEL ENGINE
Stratification is most effective in NTC region; engine parameters (CR, EGR,…) need to be correctly configured
2012 DOE Merit Review - 12MITUCBUM Project ID: ACE019
SACI/HCCI in FFVA engine (UM)
– Study multi-mode combustion spark assisted compression ignition (SACI) in well controlled metal engine
Task 3. Advanced multi-mode ignition and combustion (UM, UCB)
Modeling of SACI (UM)
– Laminar flame speed correlations (submodel)
– Coherent flamelet + AI multi-zone (CFMZ) CFD model
– System level model development Microwave Assisted Spark Plug
(MWASP) experiments (UCB)
– Feasibility testing in combustion bomb
– Tests in CFR engine– Modeling of plasma/spark
behavior
Imaging studies of SACI (UM)
– Optical engine imaging and quantification
– RCF studies of spark + autoignition interactions
2012 DOE Merit Review - 13MITUCBUM Project ID: ACE019
Task 3: Load extension with multi-mode combustion (UM)
Coldest Case
Hottest Case
SPARK TIMING
Flame HR Auto-Ignited HRSpark
Auto-Ignition
• Accomplishments/Results– FFVA engine demonstrates use
of Spark Assisted Compression Ignition (SACI) to moderate HCCI heat release and increase maximum load
7 mg/cycle 150
250
350
450
550
650
750
0 5 10 15
NM
EP
[kP
a]
CA50 [dATC]
SACI
HCCI
24 mg/cycle
12.5 mg/cycle
11.5 mg/cycle
SACI
HCCI
10
20
30
40
50
0 2 4 6 8 10 12η B
RA
KE (%
)BMEP (bar)
Load control_etab_v_bmep_NA
0.3
0.4
0.6 1.0Φ ’
HCCI ADV.COMB SI
AIR DILUTION
EGR DIL. (Φ = 1)
EIVC (SI; Φ = 1)THROTTLED (SI; Φ = 1)
Impact:• Demonstrates that SACI can access the
advanced combustion regionManofsky, L., Vavra, J., Babajimopoulos, A., and Assanis, D. (2011) Bridging the Gap between HCCI and SI: Spark-Assisted
Compression Ignition. SAE Paper No. 2011-01-1179.Manofsky-Olesky, L., Martz, J.B., Lavoie, G.A., Assanis, D.N.,Babajimopoulos, A., "The Effects of Spark Timing and Pre-Ignition
Temperature on Burn Rates in Spark-Assisted Compression Ignition," in review, The Int. Symp. on Combustion.
2012 DOE Merit Review - 14MITUCBUM Project ID: ACE019
• Accomplishments/Results– UM Optical Engine
• SACI images show distinct flame propagation followed by rapid autoignition
– Image Analysis• Automated methodology
developed for quantifying apparent flame speeds.
Task 3: SACI measurements in optical engine (UM)
Impact:• Insight into early flame development
and best practices for SACI• Validation for turbulent flame model
Keros, P., Fatouraie, M., Assanis, Dim., Wooldridge, M. S., (2012) “Quantitative Analysis of High-Speed Optical Imaging of HCCI and Spark Assisted HCCI Events,” submitted to the ASME Journal of Engineering for Gas Turbine and Power, January 2012, in review.
Zigler, B. T., Keros, P. E., Helleberg, K. B., Fatouraie, M., Assanis, Dim., and Wooldridge, M. S., (2011) “An Experimental Investigation of the Sensitivity of the Ignition and Combustion Properties of a Single-Cylinder Research Engine to Spark-Assisted HCCI,” Int. J. Engine Res. 12, pp. 353-375.
2012 DOE Merit Review - 15MITUCBUM Project ID: ACE019
• Accomplishments/Results– Developed CFD model of SACI
• Coherent Flamelet Multi-Zone model
• Extended correlations flame speeds for highly dilute, high preheat flames
• Multi-zone auto-ignition model
– Results compare well with optical engine images and experimental heat release
Task 3: Modeling of multi-mode combustion (UM)
KIVA-CFMZ MODEL EXP
Autoignitionbegins
Spark
FLAME
UNBURNED (AUTOIGNITION)
BURNEDGAS
Impact:• Tool will enable detailed studies of
geometry, turbulence, mixing, combustion limits.
Martz, J. M., Simulation and Model Development for Auto-Ignition and Reaction Front Propagation in Low-Temperature High-Pressure Lean-Burn engines, Ph.D. Thesis, University of Michigan (2010).
Martz, J., Middleton, R., Lavoie, G., Babajimopoulos, A., and Assanis, D. (2011) A computational study and correlation of premixed isooctane-air laminar reaction front properties under spark ignited and spark assisted compression igntion conditions. Combustion and Flame, Vol. 158, No. 6, 1089-1096.
2012 DOE Merit Review - 16MITUCBUM Project ID: ACE019
• Goal:– Explore the use of a Microwave Assisted
Spark Plug (MWASP) with application to SACI combustion
• Accomplishments/Results– MWASP extends lean limit and lowers
COV of IMEP in CFR engine– Plasma modeling shows diminished
effects at high pressures
Task 3: Enabling advanced combustion with MWASP (UCB)
Impact:• Success with advanced combustion
will depend on testing at higher preheat, more dilution and higher pressures
DeFilippo, A., Saxena, S., Rapp, V.H., Ikeda, Y., Chen, J-Y, Dibble, R.W., (2011) Extending the lean flammability limit of gasoline using a microwave assistedsparkplug, SAE Paper no. 2011-01-0663
2012 DOE Merit Review - 17MITUCBUM Project ID: ACE019
• Goal:– Quantify flame + autoignition interactions
• Approach:– RCF experiments varying Φ and dilution in
premixed iso-octane/O2/N2 mixtures– Spark to ignite flames– High speed imaging to measure flame
speeds and autoignition time
Task 3: Understanding simultaneous flame + autoignition interactions
Assanis, Dim., Wagnon, S., Wooldridge, M. S., ”An Experimental Study of Flame Propagation into High Temperature High Pressure Premixed Fuel Lean Iso-Octane/AirMixtures,” 7th U.S. National Combustion Meeting, Atlanta, Georgia, March 2011.
Fundamental need to better understand flame propagation in low temperature (700-1100 K), high pressure (~10 atm), lean (Φ = 0.3 – 0.7) and dilute mixtures
2012 DOE Merit Review - 18MITUCBUM Project ID: ACE019
• Accomplishments/Results– Established limits for SACI in
range of:• Φ = 0.3 - 0.7 ± 0.025• T = 900-1000 K; P = 7.3-8.1 atm• Inert :O2 dilution = 3.6 to 7.5:1
(mole basis)
Task 3: Understanding simultaneous flame + autoignition interactions
Impact:• Vital missing link for theory and modeling• Fundamental limiting conditions for SACI identified for the first time,
including flame propagation rates
t = 14.11 ms
t = 38.31 ms
t = 34.11 mst = 28.91 mst = 19.91 mst = 16.41 ms
3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.50.00.10.20.30.40.50.60.70.80.91.0
no flames
φ
dilution: molar inert:O2 ratio
P = 7.5 atmT = 916-955 K
lean flammability limit
flames
2012 DOE Merit Review - 19MITUCBUM Project ID: ACE019
Fuel testing in FFVA engines (UM)
– Establish range of combustion with fuels of varying octane number
Task 4. Fuel properties for optimal fuel economy (UM)
Optical engine (UM)
– Investigate effects of alcohol blends,
– PRF blends
Rapid Compression Facility (UM)
– Ignition delay measurements– Detailed speciation– Fuels: (isooctane, esters,
alcohols and blends)
Correlations and Modeling
– RCF data used to develop ignition delay correlations for system level models
– Speciation assists development of improved detailed kinetic models
2012 DOE Merit Review - 20MITUCBUM Project ID: ACE019
• Goal:– Identify links between ignition and
combustion properties of ethanol + indolene blends and LTC engine performance
• Accomplishments/Results– Ethanol content affected power,
efficiency, stability, lean limits, and NOx emissions
– Performance was a strong function of the LTC fueling strategy
Task 4. Effects of Fuel Blends on LTC Combustion (UM)
Impact:• 30% ethanol cannot achieve power, stability and emissions of 100%
indolene, even after compensating for charge cooling effects. What is the role of ethanol chemistry?
Fatouraie, M., Keros, P., Wooldridge, M. S., (2012) “A Comparative Study of the Ignition and Combustion Properties of Ethanol-Indolene Blends during HCCI Operation of a Single Cylinder Engine,” Society of Automotive Engineers, SAE World Congress, Paper No. 2012-01-1124, pp. 1-17.
2012 DOE Merit Review - 21MITUCBUM Project ID: ACE019
• Goal:– Determine load limits for different
fuels in FFVA engine• Accomplishments/Results
– Differences in both load limit and burn rate observed
– Analysis underway to understand this behavior in terms of burn rate, phasing and charge composition
Task 4. Fuel properties for optimum fuel economy (UM)
270
290
310
330
350
370
390
410
430
450
470
-2 0 2 4 6 8 10 12 14
IMEP
g[k
Pa]
CA50 [deg ATDC]
Fuel Load Range Comparison
Ringing Limit
Stability Limit
Iso-Octane (RON=100)RD387 (RON=90.5)NH40 (RON=~53)
Impact:• Strategy to characterize and optimize ON • Results in controlled engine environment combined with Task 1
simulations to determine potential fuel economy effects
2012 DOE Merit Review - 22MITUCBUM Project ID: ACE019
• Goal:– Quantify autoignition of key reference fuels
• Rapid Compression Facility – Ignition delay data obtained for several
reference species (e.g. iso-octane, n-butanol, esters)
– Correlations integrated into engine models– Speciation results used to improve kinetic
mechanisms (with LLNL)
Task 4. Ignition studies in RCF (UM)
UM RCF data forP ≅ 3.0 atm
model results
SAMPLING SYSTEM
model resultssampling
experiments
etheneImpact:• Developed autoignition models spanning
levels of fidelity. • Identified areas of strengths and
weaknesses in rules of reaction chemistry
Karwat, D. M. A., Wagnon, S., Teini, P. D., Wooldridge, M. S., (2011) “On the chemical kinetics of n-butanol: ignition and speciation studies,” Journal of Physical Chemistry A, 115, pp. 4909-4921.
Wagnon, S. W., Karwat, D. M. A., Wooldridge, M. S., Westbrook., C. K., (2012) “On the Ignition Chemistry of Methyl trans-3-hexenoate,” submitted to the International Symposium on Combustion January 2012, in review.
2012 DOE Merit Review - 23MITUCBUM Project ID: ACE019
Collaborations and Coordination
• Working on boosted single cylinder HCCI studies with GM
• Working with Microwave Enhanced Ignition device supplied by Yuji Ikeda, Imagineering, Inc., Japan
• Collaborating on SACI and combustion stability with Robert Wagner (ORNL)
• Currently working with Ford to adapt our optical engine to direct injection.
• Working with Jacqueline Chen (Sandia National Laboratories), Ramanan Sankaran (ORNL), Mauro Valorani (University of Rome, La Sapienza), Chris Rutland (UWisc) on mixing effects on HCCI combustion.
• Collaborated with C. K. Westbrook and Bill Pitz (LLNL) on validating reaction mechanisms for long chain alkanes, small esters – now working on alcohols
• Working with Marco Mehl (LLNL) to apply new surrogate fuel kinetics to engine models
2012 DOE Merit Review - 24MITUCBUM Project ID: ACE019
Future Work FY12
• Task 1: System and FE analysis tools– Refine analysis with realistic combustion constraints and turbocharger characteristics. Explore
tradeoff between CR and T/C efficiency in determining optimal efficiency.
• Task 2: Stratification as a means to control combustion– Shift engine operating point from non-NTC region where Φ stratification is not effective to NTC
behavior where fuel stratification is expected to be important.– Develop advanced combustion and mixing submodels to capture stratification effects and mixed
mode turbulent combustion.
• Task 3: Multi-mode combustion– Complete study of partition of flame vs. autoignition heat release with SACI in FFVA engine– Implement a higher-energy microwave system for MWASP testing– Compare flame front model results vs. experimental images in optical engine and RCF– Use CFMZ model of SACI to investigate variables affecting details of heat release; sensitivity to
spark timing; and nature of limits by comparison to metal engine data.– Develop system level model of SACI for transient and controls work.
• Task 4: Fuel properties for optimum FE– Expand range of test fuels in HCCI load limit studies– Carry out RCF studies of ignition properties of fuel blends
2012 DOE Merit Review - 25MITUCBUM Project ID: ACE019
Summary
• Task 1: System and FE analysis tools– Thermodynamic analysis confirms HPLB strategy; shows importance of advanced combustion– System framework refined since last year and FE assessment carried out for additional boosting,
downsized strategies: demonstrated potential vehicle FE improvements from 23-58%
• Task 2: Stratification as a means to control combustion– Experiments carried out with stratified gasoline fueled diesel engine show fuel stratification
increases heat release rate, because combustion is in the non-NTC region.– DNS simulation showed multiple combustion/ignition modes in thermally stratified mixture
ranging from spontaneous ignition to deflagration front.– Provided a priori validation of improved mixing model for turbulent combustion.
• Task 3: Multi-mode combustion– SACI extends high load limit in naturally aspirated FFVA engine– MWASP ignition extends lean limit under NA conditions with potential gains for LTC combustion– Laminar flame correlations developed for high dilution / high preheat conditions– CFD model of SACI developed; good qualitative agreement with optical engine images
• Task 4: Fuel properties for optimum FE– Studies of low octane gasoline fuel shows potential for higher load operation in FFVA (NVO
enabled) HCCI operation– Initial studies on ignition of n-butanol and esters carried out in RCF; speciation results show need
for improvements to kinetic models