压缩比和CO_2对二甲醚燃料均质压燃燃烧的影响

Effects of Compression Ratio and CO_2 on the Process of HCCI Combustion Fueled with DME

在一台2-135柴油机上实现了纯二甲醚(DME)的均质充量压燃(HCCI)的燃烧方式.为了扩展发动机适用工况,控制HCCI着火,进一步通过调节试验发动机压缩比以及在优化的压缩比下在进气道中加入气体CO2的方法来改进和控制HCCI的燃烧.试验结果表明,DME的HCCI燃烧模式不但可以实现无烟燃烧,还可以有效控制发动机NOx排放,使其接近于零排放.在试验负荷范围内,CO排放随负荷增加而降低;HC的排放随负荷增加而减少.对DME的HCCI燃烧机理等进行研究表明,由于纯DME十六烷值高导致着火较早(上止点前28°左右),该发动机只能在中低负荷较小范围内运行.改进的燃烧方法可以有效地控制HCCI燃烧,拓展HCCI发动机运转范围.

A 2-135 C.I. engine was modified to a dimethyl ether (DME) homogenous charge compression ignition (HCCI) combustion. The experimental results show that DME HCCI combustion presents almost zero NOx emission and smokeless behavior. Within the engine load range, the emission of CO decreases with the increase of engine load, while the HC emission does not change much. The HCCI combustion of DME presents remarkable two-stage combustion characteristics. The first combustion stage starts at around 28°C. The way of increase fuel input to increase engine load range is very likely to lead to knock. In order to control the ignition and combustion phase of HCCI, the effects of change of compression ratio and diluent gas CO2 added to the engine intake flow on the combustion were evaluated. The experimental results show that both methods are quite effective in enlarging engine load range.