增压直喷汽油机起动怠速及混合气浓度对微粒排放的影响  

Effect of Starting Idling Condition and Mixture Concentration of a Turbocharged GDI Engine on Particle Emission

作　　者：裴毅强[1] 张建业[1] 秦静[1,2] 李翔[1] 代玉利[1] 李云龙[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 [2]天津大学内燃机研究所,天津300072

出　　处：《天津大学学报（自然科学与工程技术版）》2014年第10期892-897,共6页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(50976076)

摘　　要：在一台增压直喷(GDI)汽油机上,使用快速微粒光谱仪(DMS500)对排气中微粒排放分布进行了实验研究.结果表明:在发动机起动后数秒内微粒排放较高,随着暖机进行积聚态微粒排放减少,热机怠速工况排气微粒主要以核模态为主.随着过量空气系数λ减小缸内峰值压力增加,燃烧持续期缩短,缸内平均温度升高,燃烧后期缸内温度下降幅度增加,混合气氧含量降低,这些均促进了碳烟排放.采用稀混合气时,循环变动升高.低负荷时,积聚态微粒对λ变化较敏感;增加负荷和转速后,积聚态微粒数浓度有所降低,表现为随λ减小而增加的趋势.采用浓混合气时,排气微粒质量迅速增加.在实验工况,排气微粒的几何平均直径(GMD)和中位直径(CMD)基本在10,nm以内,λ为0.8时微粒的GMD和CMD值较大.This is an experimental research on the distribution of particulate emissions in the exhaust gas of a turbo-charged gasoline direct injection（GDI） engine by using a fast particle spectrometer （DMS500）. The results showed high particulate emissions within a few seconds after startup. As the machine continued to warm up, the accumulation mode particulate emissions reduced. In hot idling condition, nucleation mode particulates were the dominant exhaust particulates . With the excess air ratio reduced, the peak cylinder pressure increased, the combustion duration short-ened, the average temperature inside the cylinder gradually increased, post-combustion cylinder temperature decreased and the oxygen content in the mixture lowered, which were conducive to soot formation and elevated cyclic variations when using lean gas. At low load, the accumulation mode particulates were sensitive to the change of the excess air ratio. After we increased load and speed, concentrations of accumulation mode particles decreased, which was demon-strated by the decreasing excess air ratio and increasing concentrations of accumulation mode particles. When using concentrated mixture, exhaust particulate mass rapidly increased. In the experimental conditions, the geometric mean diameter （GMD） and count median diameter （CMD） of exhaust gas particles were basically less than 10 nm. When the excess air ratio is 0.8, the values of GMD and CMD particulates were comparatively large.

关 键 词：GDI汽油机 缸内压力 放热率 微粒 

分 类 号：TK411.5[动力工程及工程热物理—动力机械及工程]