国Ⅵ GDI汽油车颗粒物排放特性与微观形貌特征

Emission Characteristics and Microscopic Morphology of Particles from a Gasoline Direct Injection Vehicle based on China Ⅵ Emission Regulation

试验研究了国ⅥGDI汽油车WLTC(world light vehicle test cycle)循环的颗粒物质量和固态颗粒物数量排放特性以及颗粒物微观形貌特征。结果表明,该车颗粒物质量与固态颗粒数量排放均低于国Ⅵ法规限值;固态颗粒数量累积呈3段变化形态,0~300s、600~800s与1500~1800s的累积量显著大于其他时间段。冷机起动时颗粒数量较多,仅有0~300s的累积量已大于热机起动时颗粒物数量总累积量。颗粒物主要由基本碳粒子堆积形成,形状不规则。基本碳粒子由大量微晶碳层组成,内核无序而外壳有序;重叠时有的形成大颗粒物,有的形成大碳粒子,基本碳粒子直径、碳晶长度等特征参数呈单峰分布;与GDI(gasoline direct injection)汽油机台架试验结果比较,整车试验基本碳粒子直径、碳晶长度和曲率分布相对集中且数值相对较小。

The mass,cumulative quantity and micromorphology of particulate matters from a ChinaⅥgasoline direct injection(GDI)vehicle during Worldwide Harmonized Light Vehicles Test Cycles(WLTC)have been researched experimentally.The results showed emission factors of particulate mass(PM)and particulate number(PN)were both lower than the regulation limits;The cumulative amount of particulate matters varied in three stages,which was significantly higher in the first 300s,the last 300s and 600~800s.The PN was much more when engine was started under cold condition;the accumulation from first 300s had been over the total amount of hot-engine operation.Particulate matters were mainly formed by basic carbon particles whose shapes were irregular.The basic carbon particles were composed of many microcrystalline carbon layers,the inner core was disordered while the outer shell was ordered;When basic carbon particles overlapped,some formed large particles and others formed large carbon particles.The characteristic parameters of basic carbon particles were all unmoral distribution,similar to the GDI engine;The distribution of basic carbon particles diameter,carbon crystal length and carbon crystal curvature were relatively concentrated and the values were all lower than test results of the engine bench.