DOC+CDPF对生物柴油燃烧颗粒排放特性的影响

以一台满足国五排放法规的车用柴油机为样机,研究加装氧化催化转化器DOC与催化型颗粒捕集器CDPF(DOC+CDPF后处理装置)前后,柴油机燃用B20燃料(燃料含20%体积掺混比的生物柴油)的颗粒排放特性.结果表明,在未加装该后处理装置时,该机排气颗粒数量浓度的粒径分布呈双峰形态,B20燃料的排气颗粒数量浓度的峰值粒径在10nm和50nm附近,纯柴油的排气颗粒数量浓度的峰值粒径在50nm和200nm附近.在颗粒粒径小于120nm的区域,该机燃用B20燃料的排气颗粒数量浓度大于纯柴油.加装该后处理装置后,该机排气颗粒数量浓度的粒径分布呈多峰形态,峰值粒径在10nm、20nm和60nm附近.加装DOC+CDPF后,不论是柴油还是B20燃料,与原机相比,柴油机排气颗粒总数量下降明显,其中60~200nm粒径范围的颗粒数量浓度降幅更为显著.在相同工况下,DOC+CDPF对柴油机燃用B20燃料的颗粒总数量净化效率高于纯柴油.

Effects of DOC+CDPF on particulate emission from a diesel engine with biodiesel fuel

Particulate matter (PM) emissions from a heavy duty diesel engine which meets the national V emission regulations were studied, and the engine was equipped with/without diesel oxidation catalyst (DOC) and catalyzed diesel particulate filter (CDPF), and the test fuels included 20% biodiesel fuel and pure diesel fuel. Results showed that the size distribution of exhaust particulate number from the engine without DOC+CDPF showed double-peak distribution, and the peak diameter of particulate number were about 10nm and 50nm when using B20 fuel, and about 50nm and 200nm when the engine using diesel fuel. The particulate number from the engine with B20 fuel was higher than diesel fuel at the area that particulate diameter was smaller than 120nm. The size distribution of particulate number from the engine with DOC+CDPF showed multi-peak distribution, and the peak diameters of particulate number were about 10nm, 20nm and 60nm respectively. Compared to the engine without exhaust gas aftertreatment, DOC+CDPF could evidently reduce particulate number whether the engine using B20 fuel or diesel fuel, the decreasing range was remarkable when the particulate diameter was between 60~200nm. The purification efficiency of total particulate number from the engine with B20 fuel was higher than that of diesel fuel at the same operating conditions.