稀燃条件下甲醇汽油混合燃料颗粒物排放特性

在1台GDI增压汽油机上,进行了稀燃发动机燃用M0,M10和M20(其中M0为汽油,M10为甲醇体积分数10%、汽油体积分数90%的混合燃料,以此类推)甲醇汽油混合燃料的试验,研究了在稀燃条件下甲醇汽油混合燃料对GDI发动机颗粒粒径分布特性、数量浓度特性和质量浓度特性的影响。试验结果表明:在稀燃条件下,随着甲醇比例的增加颗粒数量浓度峰值逐渐增大,颗粒数量浓度随粒径分布呈现出双峰分布;颗粒中的核态颗粒和积聚态颗粒的总数量都随甲醇比例的增加而增加,其中M20的积聚态和核态颗粒数量浓度最大;颗粒粒径峰值都随着甲醇比例的增加逐渐增大,并且核态颗粒粒径峰值主要集中在20.54~31.62nm,积聚态颗粒粒径峰值主要集中在56.23~100nm;颗粒质量浓度随甲醇比例的增加而增大,粒径分布在316~700nm的积聚态颗粒明显增多,积聚态颗粒质量浓度随粒径分布的范围明显增加,质量浓度也相应增加,而粒径分布在56.23~316nm范围内的颗粒质量浓度却在降低。

Particle Emission Characteristics of Methanol Gasoline Engine under Lean Burn Condition

The experiment was conducted on a GDI turbocharged engine fueled with methanol gasoline blends with 0％,10％ and 20％ volume fraction methanol.The effects of blended fuel on particle size distribution,particle number concentration and mass concentration were studied under lean burn condition.Experimental results showed that the peak of particle number concentration gradually increased and the particle size showed a bimodal distribution with the increase of methanol proportion.Nuclear mode particle and accumulation mode particle gradually increased and those of M20 blends were the largest.The peak particle size also increased.The peak size of nuclear mode particle was 20.54-31.62 nm and that of accumulation mode particle was 56.23-100 nm.In addition,the mass concentration increased with the increase of methanol proportion.The accumulation mode particle with a size of 316-700 nm obviously increased,the mass concentration of accumulation mode particle obviously increased with the increase of particle size,and hence the mass concentration increased.However,the mass concentration of 56.23-316 nm particle decreased.