废气再循环对HCCI发动机UHC和CO排放的影响

在中、低温化学反应分解链的基础上阐明了内部废气再循环(EGR)的作用，试验了火花点火和稳定燃烧在高EGR水平时的可能性，证实了第一阶段着火之前预燃反应的重要性，分析了未燃碳氢化合物(UHC)和CO的来源，指出了降低UHC和CO排放的有效方法，将预燃反应和可靠的火花点火、稳定的火焰传播与减少UHC和CO排放有效地联系在一起。指出了UHC和CO主要来自燃烧室余隙中的燃料，证实了影响UHC和CO排放的主要因素不是燃烧温度。

Effect of Internal EGR on UHC and CO in HCCI Engines

This paper described the effects of internal exhaust gas recirculation (EGR) based on the low and intermediate temperature degenerate chain branching chemical mechanism, examined the possibility of spark ignition and stable combustion under high internal EGR conditions, demonstrated the importance of preignition reactions in advance of the first stage ignition,introduced a potential method to reduce UHC and CO, analyzed the sources of unburned hydrocarbon (UHC) and CO, key features of the study were that the connection between the preignition chemistry and reliable spark ignition, steady flame propagation, and reduction of UHC and CO emission has been established.Experimental and model results indicated that the main source of UHC and CO emission was the fuel trapped in crevices, and the combustion temperature was not the main factor affecting UHC and CO, instead, the critical factor was the extent of the preignition reactions that occur in the cylinder prior to the first stage of autoignition.