Numeral Simulation For Flow And Regeneration Character Of Diesel Particulate Filter

As the diesel emission standards become stricter and stricter, diesel particulate filters(DPF) have attracted extensive attention from the academia as one of the most effective ways to reduce emission of PM(particular matter). The flow and regeneration characters of DPF have a significant impact on the pressure losses and efficiency, at the same time affecting the power performance and fuel efficiency of diesel engines. So the flows within the DPF and the regeneration characteristics have important theoretical significance and engineering application value. Through this research, the flow and regeneration character of Diesel Particulate Filter can be obtained, which laid a solid foundation to optimize the structure of DPF, as well as for the research and precise control for particulate filters regeneration process.Therefore, through the establishment of three-dimensional DPF channel calculation model, the distribution of velocity and pressure in the DPF channels under the condition of different wall permeabilitied and soot cake layer thicknesses were calculated in this article, as well as the pressure drop change under different inlet mass flow rate. The flow of air and PM in the channels were simulated and calculated using DPM(Discrete Phase Model) to study the trajectories and accumulation characters of soot. The results show that along the inlet channels of DPF, the velocity profile decreases. An increase of velocity is found along the outlet channels. Wall flow velocity also increases along the axial direction; The increase of permeability enhances the change of velocity and the static pressure decreases along the inlet channels at the same time,but no significant effect is found in outlet channels; The soot distribution is nonuniform along the channels and downstream half of the DPF contains a higher soot load than the front. As the soot cake thickness increases, the nonuniform distribution of soot is reduced and the pressure drop changes more significantly as a function of the inlet mass flow rate.The influence of channel structure and distribution character on pyrogenation regeneration were investigated by proposing a pyrogenation regeneration model of diesel particulate filter to prevent the damage of DPF caused by the large thermal stress. The simulation results show that asymmetric channel cell design with larger inlet channel width than outlet channel width can improve the regeneration process; More soot accumulated in the front of the diesel particulate filter results in faster regeneration velocity and has a little impact on the peak temperature; the influence of soot distribution on the regeneration process is more significant as the decrease of soot permeability; more ash accumulated in the front of the diesel particulate filter results in faster regeneration velocity and higher peak temperature.