Improving alternative fuel utilization: detailed kinetic ......Chemical kinetic model chemical...
Transcript of Improving alternative fuel utilization: detailed kinetic ......Chemical kinetic model chemical...
Lawrence Livermore National Laboratory
Improving alternative fuel utilization: detailed kinetic combustion modeling & experimental testing
Salvador Aceves, Daniel Flowers, Bill Pitz, Charlie Westbrook, Emma Silke, Olivier Herbinet, Lee Davisson, Bruce Buchholz, Nick Killingsworth
DOE National Laboratory Alternative Fuels R&D Merit Review and Peer Evaluation
Washington, DCThis presentation does not contain any proprietary or confidential information
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Goals/Objectives: Enable efficient utilization of alternative fuelsthrough detailed chemical kinetic and fluid mechanics analysis
H3C
C CH3
H2C
H3C
CH
CH2O
.O
H2C
C CH3
H2C
H3C
CH
H3C
O
HOH3C
CH
H2C
H3CCH
H2C
OO.
O
OH
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H2C
C CH3
H2C
H3C
CH2
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O.
O
HO
H2C
C CH3
H2C
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C
H3C
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HO
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CH3 O.
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H3C
CH C
H3CCH2
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O
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OH
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HO
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O
OHO
O.
H3C
C CH3
H2C
H3C
C
H3CO
CH3 OH
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High fidelity engine analysis and
Chemical kinetic model chemical kinetic model testing at
high stratification
no stratification
medium stratification
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-10 -5 0 5 10 15 20crank angle, degrees
pre
ssu
re, b
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ExperimentalMulti-zoneNeural network
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development and validation engine conditions
FY2007 Reviewer’s Comments and Response
Understand if indeed methyl decanoate is a representative surrogate for biodiesel. Another project indicated deficiencies.Our work has demonstrated good agreement betweennumerical results for methyl decanoate and experimental results for rapeseed oil
Can the combustion kinetic modeling be combined with flowreactor studies to get better validation data and a deeperunderstanding? Much of our validation is conducted at flow reactor conditions.
Some of the tasks and data were also presented in thecombustion session. There is overlap between the “Combustion” and the “Alternative Fuels” part of our work. Weminimize overlap in the presentations by clearly distinguishingresults most relevant to the combustion session from those most relevant to the alternative fuels session.
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FCVT Barriers: our work is sharply focused on addressingtechnical barriers that limit applicability of alternative fuels
Inadequate data and predictive tools for property effects on combustion and engine optimization: Our detailed models
enable high fidelity analysis for engine optimization
Inadequate data and predictive tools for fuel effects on emissions and emission control system impacts: Our high
fidelity chemical kinetic models are applicable to emissions
predictions (HC, CO, NOx and PM) in HCCI and other low
temperature combustion regimes
Inadequate knowledge base on the technical and economic impacts of non-petroleum fuels: Our analysis tools enable
clean and efficient utilization of alternative fuels such as
biodiesel
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Approach: We are developing high fidelity surrogate modelsthrough testing and tuning with our innovative engine analysis codes
5.88 mm
(0.2314 in)
5.23 mm
(0.206 in)
9.01 mm
(0.355 in)
0.305 mm
(0.0120 in)
102 mm
(4.02 in)
testing
tuning
Detailed kinetics of High fidelity
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gasoline surrogates engine models
Technical accomplishment summary: developing high fidelity surrogatechemical kinetic models for practical fuels (diesel, gasoline, biodiesel)
Surrogate fuel palette for gasoline
cyclohexane
methylcyclohexane
iso-pentanes
iso-hexanes
iso-octane
toluene
Xylene
pentenes
hexenes
CH3
n-butane n-pentanen-hexane n-heptane
CH3
Our gasoline surrogate model includes
n-alkane branched alkane olefins cycloalkanes aromatics
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We have proposed and tested three gasoline surrogate mechanisms
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Mixture 1: average gasoline
composition
Mixture 2: similar octane
number as gasoline
Mixture 3: enhanced reactivity
We have recruited LLNL’s analytical chemistry groupfor detailed evaluation of small hydrocarbon species in HCCI exhaust
Tedlar bags
Purge and Trap Gas chromatographymass spectrometer (GC-MS)
Sandia Engine
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Our innovative numerical techniques have enabled fast, high fidelity
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crank angle, degrees.
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kP
a.
!=0.26
!=0.24
!=0.22
!=0.20
!=0.18
!=0.16
!=0.12
!=0.08
!=0.04
!=0.10
!=0.14
!=0.06
Solid lines: experimentalDashed lines: numerical
analysis of homogeneous and partially stratified combustion
5.88 mm
(0.2314 in)
5.23 mm
(0.206 in)
9.01 mm
(0.355 in)
0.305 mm
(0.0120 in)
102 mm
(4.02 in)
Unprecedented level of agreement obtained between
experimental (Sandia) and numerical (LLNL) results
We have demonstrated unprecedented modeling fidelityaccurately predicting exhaust composition of 50 species
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Isooctane Formaldehyde 2-Methyl-1-propene
Acetone Methane Ethene
We are combining our chemical kinetics codes, engine models, andanalytical chemistry to deliver high fidelity surrogate models
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High quality HCCI
engine experiments
(Sandia)
Analytical chemistry for
detailed exhaust speciation
Extensively validated
chemical kinetic models
High fidelity engine analysis
Lawrence Livermore National Laboratory
We have conducted detailed speciation experimentsat Sandia HCCI engine with Chevron-Phillips reference gasoline
• Conducted both phi-sweep and
stratified charge experiments
• 18 samples collected in triplicate
• Emission bench and detailed species in
good agreement
• 70 individual exhaust species
identified and quantified
• 11 different authentic standards used
for quantification
• >1000 individual analyses reported
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We are developing chemical kinetic mechanisms forrepresentative & surrogate diesel/biodiesel species
N-hexadecane
• Diesel primary reference fuel
• Representative of diesel fuel
O
O
2,2,4,4,6,8,8 heptamethylnonane
• Diesel primary reference fuel
methyldecanoate
• Biodiesel surogate
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n-Hexadecane model agrees well with experimentsand it is ready for detailed diesel engine analysis
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In stirred reactor at 1 atm and 1000-1250K
Curves: Model
Symbols: Ristori et al. 2001
Biodiesel surrogate methyl decanoate accurately predictsignition chemistry relative to rapeseed oil combustion
Experiment: Rapeseed methyl esters
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1.E-05
1.E-04
1.E-03
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Temperature (K)
Mol
e Fr
actio
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O2 CO2 CO CH4 C2H4
methyl decanoate
O
O
Biodiesel fuels contribute to lower HC, CO and PM emissions,but increase the level of NO emissionsx
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Source: NREL
Is there a chemical reason for the increase in NO with biodiesel?x
25-50%
5-10%
2-5%
20-40% 20-40%
50-70%
15-40% 0-5%
Main species in biodiesel Representative molecules in
diesel fuel (Farrell et al., 2007)
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Conclusion: biodiesel burns hotter because it has multiple double bondsHotter burn increases NOx
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Technical Publications during FY08 C. K. Westbrook, W. J. Pitz, O. Herbinet, H. J. Curran and E. J. Silke, "A Detailed Chemical Kinetic Reaction Mechanism For n-
Alkane Hydrocarbons From n-Octane to n-Hexadecane," Combust. Flame (2008) Submitted.
E. J. Silke, W. J. Pitz, C. K. Westbrook, M. Sjöberg and J. E. Dec, “Understanding the Chemical Effects of Increased Boost Pressure under HCCI Conditions”, 2008 SAE World Congress, Detroit, MI, SAE 2008-01-0019, 2008.
R. P. Hessel, D. E. Foster, S. M. Aceves, M. L. Davisson, F. Espinosa-Loza, D. L. Flowers, W. J. Pitz, J. E. Dec, M. Sjöberg and A. Babajimopoulos, Modeling Iso-octane HCCI using CFD with Multi-Zone Detailed Chemistry; Comparison to Detailed Speciation Data over a Range of Lean Equivalence Ratios, SAE 2008-01-0047, 2008.
Sakai, Y., Ozawa, H., Ogura, T., Miyoshi, A., Koshi, M. and Pitz, W. J., "Effects of Toluene Addition to the Primary Reference Fuel at High Temperature," SAE Commercial Vehicle Engineering Congress & Exhibition, Chicago, IL, 2007.
Y. Sakai, A. Miyoshi, M. Koshi and W. J. Pitz, “A Kinetic Modeling Study on the Oxidation of Primary Reference Fuel–Toluene Mixtures Including Cross Reactions between Aromatics and Aliphatics”, Proc. Combust. Inst., Montreal, Canada, submitted, 2008.
K. Seshadri, T. Lu, O. Herbinet, S. Humer, U. Niemann, W. J. Pitz and C. K. Law, "Ignition of Methyl Decanoate in Laminar Nonpremixed Flows," Proceedings of The Combustion Institute (2008) Submitted.
C. K. Westbrook, W. J. Pitz, P. R. Westmoreland, F. L. Dryer, M. Chaos, P. Osswald, K. Kohse-Hoinghaus, T. A. Cool, J. Wang, B. Yang, N. Hansen and T. Kasper, “A Detailed Chemical Kinetic Reaction Mechanism for Oxidation of Four Small Alkyl Esters in Laminar Premixed Flames”, Proc. Combust. Inst., Montreal, Canada, submitted, 2008.
Joel Martinez-Frias, Salvador M. Aceves, Daniel L. Flowers, “Improving Ethanol Life Cycle Energy Efficiency by Direct Utilization of Wet Ethanol in HCCI Engines,” Journal of Energy Resources Technology, Vol. Vol. 129, No. 4, pp. 332-337, 2007.
George A. Ban-Weiss, J.Y. Chen, Bruce A. Buchholz, Robert W. Dibble, “A Numerical Investigation into the Anomalous Slight NOx Increase when Burning Biodiesel: A New (Old) Theory,” Fuel Processing Technology, Vol. 88, pp. 659-667, 2007.
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Collaboration: We have long standing partnershipswith industry, national labs, and academia
Industry Partners: • Collaborative modeling and analysis of experiments
National Labs and Universities: • Modeling tools, experiments, analysis
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Other collaborative activities Ongoing participation at MOU meetings with vehicle and engine
manufacturers
Fuels for Advanced Combustion Engines (FACE) working group
Surrogate fuel working group with representatives from industry (Exxon,Caterpillar, Chevron, United Technologies)
Basic Energy Sciences panel on advanced combustion
SAE HCCI symposium, Lund, Sweden, 2 invited seminars
Chalmers University, Opponent in Ph.D. exam
8 PhD and >15 MS through collaboration and direct support
Several collaborative publications involving National Laboratoriesand Universities in the US and abroad:
• SAE
• The Combustion Institute
• International Journal of Engine Research
• Combustion Theory and Modeling
• Journal of Energy Resources Technologies
• IEEE Control Systems Technology
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Future plans: We will deliver high fidelity surrogate modelsfor gasoline and diesel fuels
n-hexadecane
2,2,4,4,6,8,8 heptamethylnonane
O
O
methyldecanoate
gasoline surrogate diesel/biodiesel surrogate
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Summary: We are combining our chemical kinetics codes, engine models,and analytical chemistry to deliver high fidelity surrogate models
Detailed chemical kinetics
testing
tuning
High fidelity
5.88 mm
(0.2314 in)
5.23 mm
(0.206 in)
9.01 mm
(0.355 in)
0.305 mm
(0.0120 in)
102 mm
(4.02 in)
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Lawrence Livermore National Laboratory
engine models