车用柴油机瞬态工况的排气颗粒数量

以一台轻型车用柴油机为样机,研究发动机定转速增转矩瞬态工况下的颗粒数量排放。所用燃料为纯柴油、纯生物柴油、B20和B50燃油。结果表明:瞬态工况期间,该机燃用柴油的核态颗粒数上升,且先缓后急;聚集态颗粒数由于瞬态工况初期进气滞后,呈先增后降的特点。总颗粒数整体上升,瞬态过程初期聚集态颗粒数起主要作用,而中后期核态颗粒数占主导地位。B20燃油的颗粒数动态变化特性与柴油类似;B50燃油和纯生物柴油的颗粒数动态特性与柴油差异较大,其中总颗粒数和核态颗粒数始终明显高于柴油,聚集态颗粒一直低于柴油,表明此时核态颗粒数在总颗粒数中的支配地位。纯生物柴油在该瞬态工况初期聚集态颗粒数就持续下降,而核态颗粒数快速上升并持续到工况过渡结束。

Exhaust Particle Number of Vehicle Diesel Engine during Transient Operating Conditions

Particle number emission from a vehicle diesel engine during transient operating conditions(Increasing torque at constant speeds) is studied.Test fuels are petroleum diesel fuel,pure biodiesel fuel,B20 and B50 biodiesel blend fuels.The results show the number of nucleation mode particles from the engine increases when using petroleum diesel during the transient operating condition.The number of accumulation mode particles increases at the initial stage of transient process,and then descends with increasing torque.The total particle number increases continuously during the transient operating condition,and accumulation mode particles play an important role in the beginning,and nucleation mode particles dominate the later stage of the transient operating condition.Dynamic characteristics of particle number using B20 biodiesel during the transient process is similar with the petroleum diesel,but B50 and pure biodiesel fuels show distinct difference,and the total particle number and nucleation mode particle number are obviously higher than pure diesel from beginning to end,and the accumulation mode particle number is lower.For the pure biodiesel fuel,the nucleation mode particle number ascends to the end of the transient process,and accumulation mode particle continuously descends.