不同增压方式下EGR对高压共轨柴油机燃烧和排放的影响  

Effects of EGR on Combustion and Emissions of a Common-Rail Diesel Engine Based on Different Turbocharging Systems

作　　者：陈贵升[1] 郑尊清[1] 尧命发[1] 李彦飞[1] 赵令猛[1] 袁锋[1] 

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《燃烧科学与技术》2011年第6期512-520,共9页Journal of Combustion Science and Technology

基　　金：国家重点基础研究发展计划(973计划)资助项目(2007CB210002);国家国际科技合作基金资助项目(S2010GR0703)

摘　　要：在一台电控高压共轨柴油机上,采用单级增压、两级增压和可变几何截面增压3种增压方式,进行了高压冷却废气再循环(EGR)的燃烧与排放试验研究.结果表明,柴油机采用可变几何截面增压时,涡前与进气压差较低,泵气损失小,具有良好的燃油经济性;大负荷、等EGR率情况下,单级增压、两级增压和可变几何截面增压的缸内最大爆发压力和主燃烧期的瞬时放热率依次增加,燃烧持续期缩短.随着EGR率的增加,可变几何截面增压器的进气压力增加,导致缸内爆发压力保持较高值,两级增压和可变几何截面增压的烟度和CO排放较单级增压大幅度降低,并能明显改善NOx排放和烟度之间的trade-off关系;中小负荷时,单级增压的HC排放最高,两级增压的缸内最大爆发压力最大,但CO排放最低,可变几何截面增压的燃烧相位较单级增压和两级增压有所推迟,预混燃烧比例增加,烟度下降.Experimental studies on combustion and emissions were carried on an electronic control common-rail diesel engine which matched single-stage tubocharger（WGT）, two-stage turborcharger（2TC） and variable geometry turbocharger （VGT） respectively, and high pressure cooled exhaust gas recirculation （EGR） was employed to decrease NOx emission. The results show that VGT had lower differential pressure between exhaust outlet and engine intake, smaller pumping loss and better fuel economy. At high load with the same EGR rate, the peak cytmaer pressure and the heat release rate over the main combustion period increased in the order of WGT, 2TC and VGT, while the combustion duration reduced in the same order. With the increase of EGR rate, a higher intake pressure of VGT led to the higher peak cylinder pressure, and the smoke and CO emission of 2TC and VGT were substantially reduced compared with those of WGT, which could dramatically improve the NOx/soot trade-off. At medium or low-load, WGT produced the highest HC emission 2TC produced the highest peak cylinder pressure but the lowest CO emission, the combustion phase of VGT was later than that of WGT and 2TC, and its smoke decreased due to the higher ratio of premixed combustion.

关 键 词：柴油机 增压 废气再循环 燃烧 排放 

分 类 号：TK427[动力工程及工程热物理—动力机械及工程]