氧化催化转化器对柴油机颗粒物排放特性的影响

以某高压共轨重型柴油机为样机,研究氧化催化转化器(Diesel Oxidation Catalyst,DOC)对柴油机颗粒排放规律的影响.研究结果表明,各工况下,DOC后测点颗粒物质量浓度相对于前测点均有所下降,降幅随转速升高而减小,随着负荷的增大变化不大;外特性下,DOC对总颗粒、核态颗粒和聚集态颗粒的转化率均随着转速增加而波动下降,其平均转化率分别为21.5%,26.2%和15.4%;最大转矩转速1 400r·min-1负荷特性下,DOC对总颗粒、核态颗粒、聚集态颗粒的转化率均随着负荷的增大先下降再上升,其平均转化率为34.6%,38.8%和27.3%;DOC对核态颗粒物的转化率高于聚集态颗粒物,在粒径为9~12nm的范围内转化率达到最高,其他粒径范围内转化率大多介于20%~40%之间.

Effects of Diesel Oxidation Catalyst Technology on Characteristics of Particle from a Diesel Engine

A heavy diesel engine was tested on the engine test bench to analyze the two different particulate emissions results of the engine with DOC equipment. Results show that Particle mass concentrations of before DOC testing point decrease compared to the after DOC testing point and the drop reduce with the increase of engine speed, but there is not evident difference between load points. Under the high speed and heavy load conditons, the drop of particle mass concentrations is small. Under engine external characteristic, with the engine speed increase, conversion rates of total particles, nucleation mode particles and accumulation mode particles decline, and their average conversion rate is 21.5%, 26.2% and 15.4%, respectively. Under the load characteristics of 1400r/min, with the engine load increase, the conversion rates of total particles, nucleation mode particles and accumulation mode particles decrease firstly and then increase and their average conversion rate is 21.5%, 26.2% and 15.4%, respectively. The conversion rates of particles whose size are between 9~12nm, are over 40% and the conversion rates of other particle size are between 20%~40%. The reduction effect of nucleation mode particles from DOC is better than accumulation mode particles.