正庚烷化学动力学简化模型的构建及优化

提出了一个新的适用于HCCI发动机燃烧模拟的正庚烷化学反应动力学简化模型(40种组分和62个反应)。由三个子模型组成: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。另外,采用遗传优化技术对模型动力学参数进行调整。计算表明,新模型能够在当量比0．2-1．2,温度从300-3000 K的范围内精确模拟正庚烷HCCI燃烧时冷焰和热焰反应过程,与详细模型(544种组分和2446个反应)计算结果吻合较好。

DEVELOPENT AND OPTIMIZATION OF A NEW REDUCED CHEMICAL KINETIC MODEL FOR n-HEPTANE COMBUSTION

The paper presented a new reduced chemical kinetic model for the Homogeneous Charge Compression Ignition (HCCI) combustion of n-heptane, which consists 40 species and 62 reactions. The new model is based on two previous reduced kinetic models for alkane oxidation, from which some reactions have been eliminated and with enhanced treatment of the oxidization of CO and CH3O. The key kinetic parameters of the new model were adjusted by using a genetic algorithm optimization methodology to improve ignition timings prediction. The results showed the reduced model could simulate the cool-flame and hot-flame combustion process of n-heptane in HCCI engines, and that the reduced model generally agreed well with those of the detailed model(544 species and 2446 reactions) within the range of equivalence ratios from 0.2-1.2, temperature from 300-3000 K.