二甲基醚/天然气双燃料均质压燃化学动力学数值模拟

使用零维详细化学反应动力学模型，研究了二甲基醚和天然气双燃料均质压燃燃烧的化学反应动力学过程，缸内压力计算值和实测结果相当一致，计算结果表明，双燃料燃烧过程分为低温反应和高温反应两个阶段，低温反应主要是二甲基醚燃烧氧化，而高温反应主要是天然气的氧化，低温反应二甲基醚生成了大量自由基加速了天然气的燃烧反应．混合气初始温度升高，放热率增大，燃烧持续期缩短；二甲基醚浓度主要影响低温燃烧过程，天然气浓度则主要影响高温燃烧过程；惰性气体(CO2)使燃烧反应推迟，燃烧反应速率降低．通过控制二甲基醚、天然气和惰性气体浓度可以有效控制均质压燃燃烧过程，拓宽运行范围。

Numerical Study on the Dimethyl Ether / Compress Natural Gas HCCI Combustion Using Chemical Kinetics Model

This paper discusses the chemical reaction kinetics processes in a homogenous charge compression ignition (HCCI) engine fueled with dimethyl ether / compress natural gas using a zero-dimensional detailed kinetic model. The calculated results agreed well with the experimental results and indicated that the combustion process experienced two stages: low-temperature reactions and high-temperature reactions. DME was oxidized first because of its low ignition temperature, and CNG was burned during the high-temperature reaction stage for its abundant radicals and high temperature produced by DME combustion. Increasing initial temperatures resulted in a higher heat release rate and shorter combustion duration. The DME concentration and the CNG concentration affected the two combustion stages separately. As the CO_2 concentration was increased, the combustion rate was slowed down and ignition was delayed. The HCCI operating range could be expanded if the concentration of DME, CNG and CO_2 would be adjusted correctly.