EGR和稀燃对GDI发动机性能和排放特性的影响  

Investigation on Performance and Emissions of a GDI Engine with EGR and Lean Burn

作　　者：赵立峰 苏向阳 于秀敏[2] Zhao Lifeng;Su Xiangyang;Yu Xiumin(School of Mechanical Engineering,University of Science and Technology Beijing,Beijing 100083,China;College of Automotive Engineering,Jilin University,Changchun 130022,China)

机构地区：[1]北京科技大学机械工程学院,北京100083 [2]吉林大学汽车工程学院,吉林长春130022

出　　处：《内燃机学报》2020年第2期126-132,共7页Transactions of Csice

基　　金：国家重点研发计划资助项目(2018YFC0604402);博士后基金资助项目(2013M540251);中央高校基本业务费资助项目(2302015FRF-BR-15-052A).

摘　　要：稀燃和废气再循环(EGR)技术由于可以改善汽油直喷(GDI)发动机的燃油经济性而成为内燃机重要发展方向之一.通过GDI发动机台架试验,研究了EGR稀释、过量空气稀释(稀燃)和两种技术复合作用对发动机性能和排放的影响.结果表明:稀释率相当的条件下,化学计量比混合气下的EGR对燃烧持续期(CA0-10、CA10-50)和循环变动率(COV)的影响比过量空气稀释更显著,过量空气稀释时发动机的热效率明显高于EGR稀释时的热效率,过量空气稀释率为21.9%时,热效率升高6.3%.EGR稀释时,部分新鲜充量被非反应气体代替,导致氧体积分数明显降低.EGR与过量空气复合稀释时,热效率与过量空气稀释条件下的热效率接近,NO_x排放大幅降低,颗粒物数量(PN)排放与过量空气稀释单独作用时相当,颗粒物表面积浓度排放较低,颗粒物粒径小于EGR稀释和过量空气单独稀释时的粒径.Lean burn and exhaust gas recirculation(EGR)have become two important technical measures for gasoline engines to reduce fuel consumption and emissions.The effects of EGR dilution and excess air dilution(lean burn)on performance and emissions were experimentally studied on a gasoline direct injection(GDI) engine.The experimental results show that under the condition of similar dilution rate,the effect of EGR dilution on the combustion duration(CA0-10 and CA0-50)and the COV is more significant than the effect of excess air dilution.The brake thermal efficiency(BTE)increases by 6.3% under the excess air dilution with the excess air ratio of 21.9%,significantly higher than that under EGR dilution.When EGR is introduced,the oxygen volume fraction of the incylinder mixture is lowered because part of fresh chargers are replaced by non-reactive gases.When EGR dilution is used together with excess air dilution,the BTE and PN emission are similar to those with only air dilution,but NO_x emissions are significantly reduced.On the other hand,the particulate surface area concentration is similar to that with EGR dilution,and the particle size is smaller than that with EGR or excess air dilution.

关 键 词：汽油直喷发动机 稀燃 废气再循环 燃烧 颗粒物 排放 

分 类 号：TK417.1[动力工程及工程热物理—动力机械及工程]