Continued Research in Combustion Chemistry Mechanisms
Technical Report,15 Nov 2015,15 May 2019
SRI International Menlo Park United States
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The objective of this research is to evaluate reaction kinetics inputs involving 1-4 carbon atom species for combustion modeling and optimization. Reactions, products, rate coefficient expressions and values, thermodynamics, and uncertainties must be selected. We updated and revised the first mechanism version covering species of up to two carbon atoms. Improvements include revised CH4 C2H4 and CO2 decomposition rates. Additional species and reactions were added and involved ethanol and many other R-OH intermediates, and peroxy species and chemistry. A key important change was made to incorporate pressure-dependent kinetics for chemical activation reactions such as 2CH3-HC2H5. Reactions involving C2H4O and C2H3O2 intermediates, and a larger number of C3 and C4 hydrocarbon intermediates, were theoretically addressed to accomplish this parameterization and avoid misleading model performance issues at high pressure. A new proposed reaction CH3O2O2-CH2OO2OH was investigated. Ignition sensitive molecular reactions with HO2 and O2 were examined for consistency. Selected chemistry was then added for important three- and four-carbon containing species kinetics based on existing mechanisms, and evaluated, updated, and augmented with attention given to providing a proper treatment of pressure dependence. Theoretical investigations on the butene system and others proved particularly valuable, as there is little data and many pathways for larger systems. The resulting evaluated thermodynamics and kinetics mechanism made available for use in producing optimized foundational fuel chemistry models has 89 active species and 990 reactions. Adding this model to real fuel pyrolysis parameterizations and limited aromatics chemistry will enable accurate chemical modeling of most fuel combustion.
- Physical Chemistry