乙醇汽油点燃压燃模式颗粒物排放特性试验-《内燃机学报》

文章信息/Info

Title:: Experiment on Particulate Number Emissions of Spark Ignition to Compression Ignition Combustion Mode for Ethanol Gasoline

Author(s):: Liu Shang; Fan Qinhao; Wang Wei; Zhang Hao; Xiao Jianhua; Wang Zhi; State Key Laboratory of Automotive Safety and Energy，Tsinghua University，Beijing 100084，China

Keywords:: ethanol gasoline; spark ignition to compression ignition; particulate number; lean combustion; exhaust gas recirculation

摘要:: 为了获得点燃压燃(SICI)模式下乙醇汽油颗粒物排放的规律，通过一台直列4 缸汽油缸内直喷(GDI)发动机，研究了空气稀释和废气稀释条件下SICI模式颗粒物数量(PN)的排放特性，探究了乙醇体积分数对PN排放的影响．结果表明：控制点火时刻可以直接调节爆震强度及燃烧相位；在过量空气系数为1.0 和1.2 工况下，使用体积分数少的乙醇汽油会导致核态PN 排放的大幅增加；强爆震会导致核态与凝聚态PN 排放急剧恶化，但其粒径分布向凝聚态偏移；中等负荷下废气稀释对燃烧的抑制作用占主导，爆震强度和PN 排放降低，小负荷下废气稀释对瞬时放热率和缸内压力影响相对较小，但核态PN 排放大幅增加；从降低PN 排放的角度，乙醇汽油更加适合一定程度稀燃、中等比例EGR策略调控下的SICI燃烧．

Abstract:: In order to obtain the particulate emissions law of ethanol gasoline in spark ignition to compression ignition( SICI)combustion mode，an experimental study on effect of air dilution and exhaust dilution on particulate number(PN)emission characteristics of SICI was conducted on an inline four-cylinder gasoline direct injection( GDI)engine. The effects of ethanol volume fraction on PN emissions were investigated. The results indicate that the knocking intensity and combustion phase can be adjusted directly by controlling the ignition timing. Under the condition of excess air ratio of 1.0 and 1.2，nucleation mode PN emissions increase significantly when low portion ethanol gasoline is utilized. Both nucleation and accumulation mode PN emissions increase sharply when the knocking intensity is too high，while the curves of particle size distribution shift to accumulation mode. Under medium load，both knocking intensity and PN emissions decrease because of the domination in inhibiting combustion of exhaust dilution. However，it has little effect on in-cylinder pressure and heat release rate under low load，while nucleation mode PN emissions increase significantly. From the perspective of reducing PN emissions，ethanol gasoline is more suitable for SICI combustion with a certain degree of lean combustion and moderate proportion EGR strategy regulation.