正庚烷均质压燃燃烧反应化学动力学数值模拟研究

应用零维详细化学反应动力学模型，对正庚烷均质压燃燃烧反应的化学反应动力学过程进行了数值模拟研究，分析了在内燃机边界条件下影响其燃烧反应的关键基元反应、关键中间产物以及自由基。结果表明，正庚烷的燃烧过程由高温反应和低温反应两个阶段组成，高温反应阶段又可以分为蓝焰反应和热焰反应两个阶段。正庚烷氧化反应首先经过脱氢反应，第一次加氧异构化后的第二次加氧是低温反应的必经途径，其产物的两次分解是低温反应阶段OH自由基的主要来源；蓝焰反应阶段主要是甲醛氧化成CO的过程，H2O2的热分解是控制该阶段反应最重要的基元反应，也是OH自由基的主要来源；热焰反应主要是CO氧化成CO的过程；CO的生成途径是：低温反应生成的甲醛(CH2O)脱氢生成HCO，HCO氧化生成CO，OH是CO氧化为CO2和正庚烷脱氢反应最重要的自由基。

Numerical Study on the Chemical Reaction Kinetics of n-Heptane for HCCI Combustion Process

The auto-ignition and combustion mechanisms of n-heptane were investigated by using a zero-dimensional thermodynamic model coupled with a detailed kinetic model. The key elementary reactions, key intermediate species and key radicals were analyzed. The results indicated that n-heptane showed the two-stage auto-ignition, and heat release with low temperature reaction(LTR) and high temperature reaction(HTR), and heat release with HTR is consist of blue-flame reaction and hot flame reaction. At the low temperature, H-atom abstraction from n-heptane occurs primarily by OH and HO_2, then the first O_2 addition and isomerization. The second O_2 addition is the most important elementary reaction for the low temperature branching, and the successive decomposition of its production is the main source of OH radical at LTR. Blue-flame reaction is controlled by H_2O_2 decomposition, which is the main source of OH at HTR. In this stage, OH abstracts H-atom from CH_2O to generate HCO, and then HCO oxidation to CO. Hot-flame reaction is dominated by the oxidization of CO to CO_2. OH radical is the most important radical in the oxidation of CO and H-abstraction from n-heptane.