废气再循环对均质压燃发动机燃烧的影响

Influence of Exhaust Gas Recirculation on Combustion of Homogenous Charge Compression Ignition Engine

废气再循环(EGR)技术对多缸均质混合气压燃(HCCI)发动机的燃烧有着重要影响.文中在优化热管理技术(OKP)型HCCI发动机上对EGR进行了实验研究.结果表明:EGR在OKP型HCCI发动机中可以推迟燃烧相位,降低燃烧速率,可以用于负荷的拓展;不同负荷下采取合适的EGR比例,可以提高平均指示压力;多缸发动机各缸存在固有差异,进气温度的差异导致各缸循环变动有差异;随着废气再循环率的升高,多缸的循环变动增加,各缸的循环变动差异进一步增大.

Exhaust gas recirculation （EGR） has a great influence on the combustion characteristics of ho- mogenous charge compression ignition （HCCI） engine. An experimental study was conducted on the EGR technology in an optimized kinetic process （OKP） HCCI engine. The results show that EGR can retard the combustion phase and reduce the combustion reaction rate in the OKP HCCI engine. EGR could be utilized for HCCI load expansion. EGR could improve indicated mean effective pressure. Different EGR rate should be optimized in different engine load. There are differences on temperature and air charge between cylinders in muhi-cylinder engine, which will lead to different characteristics in cycle-to-cycle variation. Cycle-to cycle variation will increase as EGR rate increases, and so will cylinder-to-cylinder variation.