二甲醚均质压燃燃烧化学反应动力学机理数值模拟

Numerical Simulation of Chemical Kinetics Mechanism in HCCI Combustion Fueled with Dimethyl Ether

应用单区燃烧模型对二甲醚(DME)均质压燃燃烧(HCCI)的化学反应动力学过程进行了数值模拟研究.通过分析在内燃机压燃燃烧边界条件下DME燃料氧化反应过程中的关键基元反应速度、关键中间产物以及自由基的浓度随曲轴转角的变化,得到了DME燃料燃烧氧化的反应途径.结果表明,DME燃料均质压燃燃烧具有明显的两阶段放热特性,即低温反应放热和高温反应放热;燃料脱氢产物的两次加氧反应是低温反应发生的关键;脱氢产物的第一次加氧反应转向脱氢产物的裂解反应是高温反应的主要途径.DME低温反应阶段的主要氧化产物包括甲醛(CH2O)和甲酸(HOCHO).

A numerical simulation study on chemical kinetics process of homogeneous charge compression ignition （HCCI） combustion fueled with dimethyl ether （DME） was performed by using single-zone model coupled with a detailed kinetic model. The overall reaction scheme of dimethyl ether oxidation was obtained by analyzing the reaction rates of the key elementary reactions, the key intermediate species and radicals. The results indicate that the HCCI combustion fueled with DME consists of a low temperature reaction （LTR） heat release period and a high temperature reaction （HTR） heat release period. Two times of O2 addition reactions of species produced by H-atom abstraction from DME are very important for the LTR stage. The decomposition reaction of the produced species by H-atom abstraction is the main path of DME consumption at high temperature. The main oxidation products in the LTR stage include formaldehyde （CH2O） and formic acid （HOCHO）.