稀释比对预混燃烧器排气中颗粒物粒径分布影响

Effect of dilution ratio on size distribution of particles in the emission of premixed burner

为测量柴油机发动机预混燃烧尾气中颗粒物数量浓度和粒径,研究了稀释比对尾气中颗粒物粒径分布的影响。利用小型引射式稀释器调节稀释比,使用扫描电迁移率颗粒物粒径谱仪测量甲烷、乙烯等预混燃烧尾气中颗粒物的粒径分布,使用透射电子显微镜观察观察细颗粒物的微观形貌以及处理粒径分布。结果表明:甲烷燃烧尾气颗粒物粒径主要在40 nm左右,其浓度最高可达到108/mL;乙烯燃烧尾气中颗粒物粒径在250 nm左右,其浓度达到107/mL。稀释比增大时,颗粒物数量浓度先增大后减小,粒径分布也会发生变化,从而会使测量结果与实际结果发生偏差。

The influences of the dilution ratio on the particle size distribution in the exhaust gas of diesel engines were investigated to measure the number concentration and the size of particulate matter in the premixed combustion exhaust.A small-size injection dilutor was used to control the dilution rate.The size distributions of nano particles in premixed combustion emission of methane and ethylene were measured by using the scanning mobility particle sizer.Transmission electron microscope was used to observe the microscopic morphology and analysis the size distribution.The results show that the particle size of methane combustion exhaust gas is mainly about 40 nm,and its concentration can reach up to 108/mL;the particle size of ethylene combustion exhaust gas is about 250 nm,and its concentration reaches 107/mL.When dilution rate increases,the particle number concentration first increases and then decreases,and the particle size distribution will also change,which will cause the measurement results to deviate from the actual results.