一个新的用于HCCI发动机燃烧研究的正庚烷化学反应动力学简化模型

A New Reduced Chemical Kinetic Model of N-Heptane Combustion for HCCI Engine Simulations

提出了一个新的适用于HCCI发动机燃烧研究的正庚烷化学反应动力学简化模型,包含44种组分和72个反应。由四个子模型组成:低温反应子模型是在Li等人模型的基础上,定义具体的醛类(RCHO)产物和小分子碳氢产物(Rs)而构建;增加了用于链接低温反应向高温反应过渡的大分子直接裂解成小分子反应子模型;高温反应子模型是在Griffiths等人模型的基础上,去除了无关的基元反应,增加两个关于CO和CH3O的氧化反应而构建;此外,还采用了Golovitchev简化模型中NOx生成子模型。新模型能够模拟正庚烷HCCI燃烧的冷焰和热焰反应以及NOx生成的整个过程,与详细模型计算结果吻合较好。CPU计算时间是详细模型的1/1000,为CFD多维模型与化学反应动力学模型相耦合的燃烧计算提供了可行的途径。

The paper presented a new reduced chemical kinetic model for the Homogeneous Charge Compression Ignition(HCCI)combustion when using n-heptane as the fuel,This model consists of 44 species and 72 reactions.The reduced model includes four sub-models,in which the sub-model for low temperature reaction was established by determining particular aldehydes and small hydrocarbons in the Li-model,the sub-model for large molecules decomposing directly to small molecules was developed for linking the low-temperature reaction to the high-temperature reaction,the sub-model for high-temperature reaction was given through some modifications to Griffiths-model such as eliminating several reactions and adding two oxidization reactions of CO and CH_3O,the sub-model for NO_x formation from the Golovitchev reduced kinetic model was introduced into the reduced model.This reduced model could simulate the cool-flame and hot-flame combustion process of n-heptane as well as NO_x formation in HCCI engines,and the calculation results also agreed well with those from the detailed model.The computational time by using the reduced model is 1/1 000 to that using the detailed model.HCCI engine simulations using chemical reaction with CFD are attainable by using this reduced model.