外部热EGR对基于优化动力技术的汽油HCCI燃烧的影响

摘要

考察了外部热EGR对基于优化动力技术的汽油HCCI发动机燃烧的影响.试验结果表明:外部热EGR可以推迟HCCI燃烧的着火时刻,减缓放热速率,但对于高辛烷值燃料的HCCI燃烧,它对更高EGR率的兼容能力不强,需要提高进气温度来提高燃烧的稳定性；随着EGR率的增加,燃烧持续期延长,缸内温度和压力峰值均减小,指示热效率也随着减小；NOx排放随着EGR率的增加在经过一个“拐点”后始终维持在一个较低的水平,而CO和HC的排放随着EGR率的增加显著增加,燃烧恶化.%The effects of external hot exhaust gas recirculation (EGR) on gasoline homogeneous charge compression ignition (HCCI) engine were studied based on optimized kinetic process (OKP) technology. The results show that the external hot EGR can delay the HCCI combustion timing and slow the heat release. For the HCCI combustion of high-octane fuel, its compatibility with high EGR is not good and hence the inlet temperature need be increased to improve the combustion stability. With the increase of EGR rate, the combustion duration increases, the in-cylinder temperature and peak pressure decrease and the indicated thermal efficiency also decreases. The Nox emission keeps a low level after the inflection point, the HC and CO emissions evidently increase so that the combustion deteriorates.