高低压废气再循环对直喷增压汽油机影响的实验研究

Experimental Studies into the Effects of High and Low Pressure Exhaust Gas Recirculation on a Turbocharged Gasoline Direct Injection Engine

在某型直喷增压汽油机上分别进行高压废气循环和低压废气循环实验研究。在中低转速部分负荷下对比了发动机燃烧、油耗、排放的相应变化并分析原因。结果表明,随着废气再循环率的上升,在两种不同废气再循环布置方式下,都出现了缸压峰值降低、相位滞后且爆燃裕度提高的情况。其中,低压废气循环对缸压峰值影响效果更明显,相较于高压废气循环进一步下降约20%。两种废气再循环布置方式对中低转速部分负荷下排放有改善,且趋势基本相同。CO排放基本不变。碳氢化合物排放增加,但随着转速的上升,该增加趋势减缓。转速越低,NOx排放降低越明显。

Experiments on high-pressure exhaust gas recirculation(EGR) and low-pressure exhaust gas recirculation were conducted on a gasoline direct injection(GDI) engine. The experiments compared the combustion characteristics, fuel consumption, and exhaust emissions at low-to-medium speed partial loads. The results indicate that with the increase of exhaust gas recirculation(EGR) rate, the peak cylinder pressure decreases, the phase lags, and the deflagration margin increases under two different EGR arrangements. Among them, the effect of low-pressure EGR on peak cylinder pressure is more obvious, which is about 20% lower than that of high-pressure EGR. Different EGR arrangements have improved the emission at low-to-medium speed, and the trend is basically the same. The emission of CO remains basically unchanged. The emission of total hydrocarbon increases, but the trend slows down at a higher speed. The lower the speed, the more obvious the reduction of NOx emission.