Study on regenerative exothermic process in ash containing DPF structure based on lattice Boltzmann method

Abstract

At present, diesel particulate filter (DPF) is the most effective method to reduce PM and PN in diesel engine exhaust. However, after a long period of operation, the DPF wall formed dense ash layer, which seriously affected the normal operation of the DPF. In this paper, Quartet Structure Generation Set is used to add the ash layer micro-structure, and the lattice Boltzmann method is used to explore the influence of ash layer in the ash containing DPF structure on its oxidation and regeneration process. In DPF, the active regeneration of O2 and particle (ΔH1 = −393.5 kJ/mol) and passive regeneration of NO2 and particulate matter (ΔH2 = −277.3 kJ/mol). This article combines the real microstructure of DPF and Arrhenius law to design two micro porous media structure models for DPF. The influence of ash layer on the heat release process of DPF regeneration was studied by analyzing the presence of ash stratification structure and the inlet velocities of structure I and II. It's found that the regeneration temperature of DPF structure with ash layer increases with the increase of exhaust gas inlet velocity, and the regeneration temperature of micro porous media structures at the same position varies greatly; With the increase of exhaust gas inlet velocity, the temperature distribution uniformity of the micro surface of the ash layer decreases, and the relative range increases; The optimal inlet velocity on the structural wall surface is obtained to be 0.15 m/s.