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Title	Optimized Chemical Kinetics for Modeling Natural Gas Combustion
Creator	Frenklach, M.; Wang, Hai; Goldenberg, M.; Bowman, C. T.; Hanson, Ronald K.; Smith, Gregory P.; Golden, D. M.; Gardiner, W. C.; Lissianski, V.
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1995
Spatial Coverage	presented at Monterey, California
Abstract	Improved understanding of natural gas combustion chemistry, leading to the formulation and validation of a detailed reaction mechanism capable of quantitatively accounting for and modeling high temperature natural gas ignition and flame phenomena, is needed to serve as a basis for designing improved combustion devices with respect to efficiency and emissions. We have carried out a systematic optimization procedure, starting from a critically evaluated set of 177 elementary reactions, to derive a thermochemical and kinetic parameter set (GRI-Mech 1.2) that successfully accounts for a set of laboratory combustion property measurements (47 flame speeds, shock tube ignition delay times, and species profiles) over wide temperature, pressure, and composition ranges. In our presentation we will describe this optimization procedure, and present the results of validation studies on the combustion of methane and related fuels. We will also report on the performance of reduced mechanisms, derived from the full one for specific conditions to use in applications requiring shorter kinetic parameterization, and on the results of extending the optimization procedure to a detailed mechanism describing NOx formation and reburning.
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Format	application/pdf
Language	eng
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ARK	ark:/87278/s61j9dcn
Setname	uu_afrc
ID	8634
Reference URL	https://collections.lib.utah.edu/ark:/87278/s61j9dcn

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Title	Page 9
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OCR Text	Show • optimization efforts. While we believe the newly evaluated model offers an improvement over previous descriptions of NO formation and reburning, we must view this first optimized version in the spirit of "beta testing" and as a stimulus to further experimental study. The optimized mechanism includes 9 adjusted rate constants, including only one from GRI-Mech 1.2 (CH + ~O) which did not affect the modeling results on any of the target or validation experiments for the hydrocarbon mechanism. To illustrate the paucity of target results available, the lowering of the rate constant for CH + N2, a reaction critical in prompt NO fonnation, results solely from the effort to match a single low pressure flame measurement. Some of the model results for target experimental data are illustrated in Figs. 9 and 10. More are available for visiting at the World Wide Web site. 8 3 l ""! 2 ~ :". ! ?j 0 0 1 DimIDce &om tJum.1 em Fig. 9. Measured[21] and calculated CN mole fraction profiles vs. distance for 10 torr premixed 0.19 CH4 - 0.38 O2 - 0.42 Ar flames seeded with 0.86% N20 (bottom) and NO(top). Profiles are normalized to the maxima for the N20 doped flame. CONCLUSIONS .J ~ $ 0 2;. 1.0 0.9 0 .. 0.7 5 ' 10 15 Distance from bumCl' I DUD Fig. 10. NO mole fraction vs. distance for a 35 torr premixed . 175CH4-·31 02-.495Ar-.02NO flame,[22] normalized to the initial value, compared to computed values. A detailed chemical model of methane combustion was derived by a systematic optimization procedure. Because it was derived from thennochemical and rate coefficient parameter sets taken from exhaustive critical examination of the literature, there is good reason to believe that it can be used with confidence to describe methane combustion under conditions of practical interest that may be well removed from the temperature and composition conditions used in the laboratory experiments that provided optimization target data values. Two approaches were successfully employed to produce reduced mechanisms 9
Setname	uu_afrc
ID	8631
Reference URL	https://collections.lib.utah.edu/ark:/87278/s61j9dcn/8631