醇类汽油混合燃料EGR氛围下颗粒物排放特性研究

在一台缸内直喷(GDI)汽油机上,研究了部分负荷工况下引入EGR和添加醇类燃料对发动机颗粒物数量浓度和体积浓度排放特性的影响.实验结果表明,对于汽油、E20(乙醇在混合燃料中的体积比例为20%)、Bu20(正丁醇在混合燃料中的体积比例为20%)3种燃料而言,随着EGR率从0增加到20%,核态颗粒物数量浓度最大升幅为31.6%、110.0%、55.0%,积聚态颗粒物数量浓度最高降幅分别达21.9%、29.2%、40.9%,体积浓度最高降幅分别达45.0%、55.0%、36.6%.在EGR率为0工况下,相对于汽油燃料,E20与Bu20燃料核态颗粒物排放数量浓度降幅分别达82.4%、64.9%,积聚态颗粒物排放数量浓度降幅分别达77.0%、56.0%,体积浓度降幅分别达78.4%、52.0%,在降低颗粒物排放方面,乙醇要优于正丁醇.

Particle emission characteristics of alcohol-gasoline blends in combination with EGR

The effects of alcohol-gasoline blends on particle number and volume concentration emissions in combination with EGR were conducted on a GDI engine at part load condition. Results show that as EGR rate increases from 0 to 20%, the nucleation mode particle number concentration of gasoline, E20 (the volume fraction of ethanol in the blend is 20%) and Bu20 (the volume fraction of n-butanol in the blend is 20%) increases 31.6%, 110.0% and 55.0%, respectively, the accumulation mode particle number concentration decreases 21.9%, 29.2% and 40.9%, respectively, and the particle volume concentration declines 45.0%, 55.0% and 36.6%, respectively. Under the 0 EGR rate, the nucleation mode particle number concentration of E20 and Bu20 decreases 82.4% and 64.9%, respectively, the accumulation mode particle number concentration decreases 77.0% and 56.0%, respectively, and particle volume concentration decreases 78.4% and 52.0%, respectively compared with gasoline fuel. In terms of reduction of particle emission, ethanol is better than n-butanol.