Mechanism Reduction and Generation Using Analysis of Major Fuel Consumption Pathways for n-Heptane in Premixed and Diffusion Flames
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- 作者：Hongzhi R. Zhang ; Eric G. Eddings ; Adel F. Sarofim ; Charles K. Westbrook
- 刊名：Energy & Fuels
- 出版年：2007
- 出版时间：July 2007
- 年：2007
- 卷：21
- 期：4
- 页码：1967 - 1976
- 全文大小：224K
- 年卷期：v.21,no.4(July 2007)
- ISSN：1520-5029
文摘
Reaction pathway analyses were conducted for three mechanisms (designated as the Pitsch, Utah, andLawrence Livermore National Lab) for a normal heptane premixed flame (
= 1.9) and a normal heptaneopposed diffusion flame, in order to identify the relative importance of the major fuel consumption pathwaysin the two flame classes. In premixed flames, hydrogen abstraction is found to be the major fuel consumptionroute although it is surpassed by thermal decomposition when the flame temperature exceeds 1400-1500 K.At the higher temperatures, however, little fuel remains in a premixed flame so that thermal decompositionprovides a minor pathway for overall fuel decomposition. The principal abstractor is the hydrogen radical inall three mechanisms with the hydroxyl radical having a secondary role. In opposed diffusion flames, thermaldecomposition competes with hydrogen abstraction in providing the major pathway for fuel consumption.Thermal decomposition becomes important when a large fraction of the fuel reaches the high-temperaturezone in a flame. By understanding the relative importance of competing fuel consumption pathways, mechanismscan be tailored to each specific application by eliminating or lumping insignificant reactions. The results obtainedin this study for n-heptane may be used to guide the reduction of existing mechanisms for a particular applicationor the generation of mechanisms for the combustion of larger paraffins that are major components of liquidaviation and transportation fuels.
= 1.9) and a normal heptaneopposed diffusion flame, in order to identify the relative importance of the major fuel consumption pathwaysin the two flame classes. In premixed flames, hydrogen abstraction is found to be the major fuel consumptionroute although it is surpassed by thermal decomposition when the flame temperature exceeds 1400-1500 K.At the higher temperatures, however, little fuel remains in a premixed flame so that thermal decompositionprovides a minor pathway for overall fuel decomposition. The principal abstractor is the hydrogen radical inall three mechanisms with the hydroxyl radical having a secondary role. In opposed diffusion flames, thermaldecomposition competes with hydrogen abstraction in providing the major pathway for fuel consumption.Thermal decomposition becomes important when a large fraction of the fuel reaches the high-temperaturezone in a flame. By understanding the relative importance of competing fuel consumption pathways, mechanismscan be tailored to each specific application by eliminating or lumping insignificant reactions. The results obtainedin this study for n-heptane may be used to guide the reduction of existing mechanisms for a particular applicationor the generation of mechanisms for the combustion of larger paraffins that are major components of liquidaviation and transportation fuels.