Effects of DOC and Metal-based DPF on the Nanostructure of Soot in Diesel Exhaust
This study investigated the effects of Diesel Oxidation Catalyst(DOC)and metal-based Diesel Particulate Filter(DPF)on the nanostructure of diesel exhaust soot.The results show that the raw soot that sampled at the pre-DOC site tends to exhibit larger average fringe length(Lp)at high engine load,while the values of Lp becomes smaller with the increased engine speed.However,the values of average separa-tion distance(Dp)and average tortuosity(Tp)show opposite trends as compared with the the Lp when varying the engine operating condition.The DOC treatment increases the Lp value and simultaneously decreases the values of Dp and Tp,all of which exhibit more significant variations at the higher engine load while ex-hibit smaller variations at higher engine speed.The DPF treatment has negligible effect on the soot nanos-tructure,as evidenced by the smaller variations in Lp,Dp and Tp when comparing the soot samples pre-and post-DPF.The soot oxidation reactivity apparent activity energy(Ea)possesses excellent correlations with the values of Lp,Dp and Tp.Specifically,the Tp value shows the strongest correlation with Ea.The DOC treatment improves the correlations between the soot oxidation reactivity and nanostructure because the determination coefficients of the Lp,Dp and Tp against E.increase after DOC treatment.
万方数据
维普
