公交车燃用生物柴油的颗粒物排放特性

Particle Emission Characteristics of Diesel Bus Fueled with Bio-diesel

采用美国TSI公司的EEPS颗粒数量及粒径分析仪,对国Ⅳ排放柴油公交车燃用纯国Ⅳ柴油BD0,纯餐饮废油制生物柴油BD100及国Ⅳ柴油和生物柴油掺混体积比分别为5%、10%、20%、50%的混合燃料(BD5、BD10、BD20、BD50)的颗粒物排放特性进行了试验研究.结果表明,颗粒物数量及质量排放随车速加速度的增加均呈逐渐增加趋势,而随生物柴油掺混比例的增加而降低;不同车速区间下,颗粒物数量排放的粒径分布均呈双峰分布;不同加速度区间下,颗粒物数量排放的粒径分布由减速时的双峰分布逐渐过渡到加速时的单峰分布;随生物柴油掺混比例的增加,聚集态颗粒物数量下降显著,且峰值向小粒径方向移动,核态颗粒物数量变化不大,颗粒物几何平均粒径Dg变小.

With the use of the Engine Exhaust Particle Sizer （EEPS） , a study on the characteristics of particle emissions was carried out on a China-IV diesel bus fueled with blends of 5% , 10% , 20% , 50% bio-diesel transformed from restaurant waste oil and China- IV diesel （marked separately by BD5, BD10, BD20, BD50）, pure bio-diesel （BDIO0） and pure diesel （BD0）. The results indicated that particulate number （PN） and mass （PM） emissions of bio-diesel blends increased with the increase in bus speed and acceleration; with increasing bio-diesel content, particulate emissions displayed a relevant declining trend. In different speed ranges, the size distribution of particulate number emissions （PNSD） was bimodal; in different acceleration ranges, PNSD showed a gradual transition from bimodal shape to unimodal when bus operation was switched from decelerating to accelerating status. Bio-diesel blends with higher mixture ratios showed significant reduction in PN emissions for accumulated modes, and the particulate number emission peaks moved towards smaller sizes ; but little change was obtained in PN emissions for nuclei modes; reduction also occurred in particle geometric diameter （D.）.