压燃式发动机燃用汽油/柴油混合燃料瞬变工况下燃烧及微粒排放特性分析  

Experimental Study on Combustion and Ultrafine Particle Emissions of CI Engine Fueled with Gasoline/Diesel Blends under Transient-State Conditions

作　　者：孙万臣[1] 杜家坤[1] 郭亮[1] 肖森林[1] 程鹏[1] 范鲁艳[1] 

机构地区：[1]吉林大学汽车仿真与控制国家重点实验室,吉林长春130025

出　　处：《内燃机学报》2016年第2期170-176,共7页Transactions of Csice

基　　金：国家自然科学基金资助项目(51176064)

摘　　要：针对压燃式发动机燃用汽油/柴油混合燃料稳态及瞬态工况下的燃烧及微粒排放粒度分布特征进行了试验研究,分析了汽油掺入比例及EGR对发动机稳态及不同瞬变率的恒转速增转矩瞬变工况超细微粒数量排放的影响规律.结果表明：在大负荷工况下采用高汽油掺入比例的汽油/柴油混合燃料能够在不引起NOx显著增加的前提下进一步降低排气烟度,有助于拓展预混合燃烧过程负荷工况范围;但较高汽油掺入比例易导致油气过度混合,对HC及CO排放有不利影响,尤其会导致小负荷工况下CO排放显著增加.综合考虑不同负荷工况下运行情况,认为汽油掺入比例在40%,～50%,左右较为适宜.燃用汽油/柴油混合燃料时排气颗粒物更趋于细化,其微粒几何平均粒径较柴油明显降低.瞬变工况增负荷过程中,各模态微粒数量浓度均有所升高,随汽油掺入比例增大积聚态微粒数量增加程度变缓,当汽油掺入比例达到50%,时,在高瞬变率工况时积聚态微粒数量无明显增加.高比例EGR条件下,瞬变过程中积聚态微粒数量浓度在增负荷初期便急剧增加,燃用汽油/柴油混合燃料有利于缓解瞬态工况积聚态微粒数量急剧增加的程度.Effects of gasoline/diesel blended fuels,composing of diesel fuel with gasoline as additives in volume basis,on combustion and particle size distribution were experimentally studied in a compression ignition engine.Effects of gasoline fraction and EGR（exhaust gas recirculation）on ultra-fine particle emissions under steady-state and transient-state operating conditions were evaluated experimentally for various fuels.Results show that with the increase of gasoline fraction in the blends,smoke is decreased without significant penalty on NOx.This indicates that high gasoline fraction is in favor of expanding the load limitation of premixed combustion.However,too much gasoline may lead to the ＂over-mixing＂,which causes more HC and CO emissions,especially at low loads.The suitable gasoline fraction is 40%-50%,,considering the various loads.The particles emitted tend to ultrafine with gasoline/diesel blended fuels and the GMD（geometrical mean diameter）is decreased at high gasoline fraction.All of the particles increase with the increase of load under the transient-state conditions.While the accumulation mode particles change slightly with the increase of gasoline fraction.There is no significant increase in accumulation mode particles with gasoline fraction up to 50%,.Under high EGR ratio,the accumulation mode particles increases sharply and they can be inhibited with the gasoline/diesel blended fuels under the initial stage of transient-state operating conditions.

关 键 词：压燃式发动机 汽油/柴油混合燃料 燃烧 排放 微粒排放粒度分布 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]