压缩比与EGR对二甲醚的HCCI特性影响的模拟研究

Simulation for the Effects of Compression Ratio and EGR on Combustion Characteristics of DME HCCI

应用单区燃烧模型和已建立的二甲醚氧化反应机理,对二甲醚的HCCI过程进行了模拟计算,研究了变压缩比和不同的冷却EGR率对二甲醚的HCCI特性的影响.结果表明:随着压缩比的升高,二甲醚的两阶段着火均有提前,且间隔减小,燃烧持续期缩短;冷却EGR率对二甲醚第一阶段着火时刻并无太大影响,第二阶段着火时刻随EGR率的增大逐渐延迟,缸内压力和温度均有所下降,燃烧持续期增大.

The chemical reaction mechanism of Dimethly Ether （DME） and single zone combustion model are used to investigate the effects of compression ratio and cold EGR rate on HCCI combustion characteristics. The results reveal that the increase of compression ratio advances the ignition timing of two stages, shortens the interval of the two stages and combustion duration. Moreover, as cold EGR rate increases, the ignition timing of the first comhustion stage has no rernarkable change, hut the ignition timing of the second stage delays, and as the cylinder pressure and temperature decreases, the combustion duration extends.