CO_(2)模拟进气EGR对GDI发动机燃烧及排放影响

Effect of EGR Rate on Combustion and Emissions of a GDI Engine with CO_(2) as Simulated EGR

为探究EGR率对GDI发动机燃烧及排放的影响,基于一台2.0L涡轮增压GDI发动机,通过提高进气中CO_(2)的含量模拟进气EGR率,研究了EGR从0到20%对发动机燃烧及排放的影响。试验结果表明:当EGR率从0增加到20%,缸内燃烧压力峰值、放热率峰值及燃烧温度峰值均随EGR率增大而减小,且其对应的曲轴转角均随EGR率增大而增大;CA05及CA50均随EGR率增大而增大但CA05-90随EGR率增大而减小;当EGR率小于10%缸内燃烧循环变动系数随EGR率增大略微增大,当EGR率大于10%燃烧循环变动系数随EGR率增大显著增大。当EGR率从0增加到20%HC排放略微升高,但CO、NO_(X)及SOOT排放随EGR率增大而减小。

To study the effect of EGR rate on combustion and emissions of a GDI engine,in this study,CO_(2) was introduced to intake charge as a simulated EGR and the EGR rate from 0 to 20%base on a GDI engine.The results show that the peak of pressure、heat release rate and temperature will decrease as the EGR rate increase,while its crank angle will increase;the CA05、CA50 will increase as the EGR rate increase while the CA05-90 will decrease;the rate of combustion cycle variation will increase slightly as the EGR rate increase when the EGR rate is below 10%while it will increase obvious when the EGR rate exceed 10%.The emission of HC will increase slightly when the EGR rate increase from 0 to 20%,while the emission of CO、NO_(X)and SOOT will decrease as the EGR rate increase.