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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Evaluated Kinetics of the Reactions of H and CH3 with n-Alkanes: Experiments with n-Butane and a Combustion Model Reaction Network Analysis
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Evaluated Kinetics of the Reactions of H and CH3 with n-Alkanes: Experiments with n-Butane and a Combustion Model Reaction Network Analysis

机译：H和CH3与正构烷烃反应动力学的评估动力学：正丁烷实验和燃烧模型反应网络分析

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摘要

Presented is a combined experimental and modeling study of the kinetics of the reactions of H and CH3 with n-butane, a representative aliphatic fuel. Abstraction of H from n-alkane fuels creates alkyl radicals that rapidly decompose at high temperatures to alkenes and daughter radicals. In combustion and pyrolysis, the branching ratio for attack on primary and secondary hydrogens is a key determinant of the initial olefin and radical pool, and results propagate through the chemistry of ignition, combustion, and byproduct formation. Experiments to determine relative and absolute rate constants for attack of H and CH3 have been carried out in a shock tube between 859 and 1136 K for methyl radicals and 890 to 1146 K for H atoms. Pressures ranged from 140 to 410 kPa. Appropriate precursors are used to thermally generate H and CH3 in separate experiments under dilute and well-defined conditions. A mathematical design algorithm has been applied to select the optimum experimental conditions. In conjunction with postshock product analyses, a network analysis based on the detailed chemical kinetic combustion model JetSurf 2 has been applied. Polynomial chaos expansion techniques and Monte Carlo methods are used to analyze the data and assess uncertainties. The present results provide the first experimental measurements of the branching ratios for attack of H and CH3 on primary and secondary hydrogens at temperatures near 1000 K. Results from the literature are reviewed and combined with the present data to generate evaluated rate expressions for attack on n-butane covering 300 to 2000 K for H atoms and 400 to 2000 K for methyl radicals. Values for generic n-alkanes and related hydrocarbons are also recommended. The present experiments and network analysis further demonstrate that the C-H bond scission channels in butyl radicals are an order of magnitude less important than currently indicated by JetSurf 2. Updated rate expressions for butyl radical fragmentation reactions are provided.
机译：提出了H和CH3与正丁烷（一种典型的脂肪族燃料）反应动力学的组合实验和模型研究。从正构烷烃燃料中提取H会产生烷基自由基，该自由基在高温下会迅速分解为烯烃和子自由基。在燃烧和热解中，进攻伯​​氢和仲氢的支化比是初始烯烃和自由基库的关键决定因素，其结果会通过着火，燃烧和副产物的化学反应传播。确定冲击和氢的相对和绝对速率常数的实验是在859-1136 K的甲基自由基和890-1146 K的氢原子激波管中进行的。压力范围为140至410 kPa。在单独的实验中，在稀薄和定义明确的条件下，使用适当的前体热生成H和CH3。数学设计算法已被应用于选择最佳实验条件。结合震后产品分析，已经应用了基于详细化学动力学燃烧模型JetSurf 2的网络分析。多项式混沌扩展技术和蒙特卡洛方法用于分析数据和评估不确定性。本结果提供了在1000 K附近温度下H和CH3对伯氢和仲氢的进攻支化率的首次实验测量。对文献的结果进行了综述，并与现有数据结合以生成评估对n的进攻速率表达。 -丁烷的氢原子数为300-2000 K，甲基为400-2000K。还建议使用一般正构烷烃和相关烃的值。本实验和网络分析进一步证明，丁基自由基中的C-H键断裂通道比JetSurf 2当前指出的重要程度低一个数量级。提供了丁基自由基断裂反应的最新速率表达式。

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