Visual Experiment And Simulation Of Soot Deposition And Distribution In DPF Channel

Diesel particulate filter is a device that can effectively remove diesel exhaust particulates.However,the particulates will deposit in the interchangeable blocked honeycomb channels of the trap due to its filtration mode,so it is necessary to regenerate periodically.Accurate determination of carbon load is the key to determine the timing of regeneration.Therefore,it is necessary to study the specific process of soot deposition in DPF,so as to provide theoretical guidance for accurately judging the amount of soot deposition in DPF and determining the reasonable regeneration time.In this paper,we design and fabricate a single-channel two-sided filtration visualization reactor which can reflect the internal flow of soot particles,build the corresponding experimental bench,and combine the laser displacement sensor to measure the thickness of soot deposition in real time,study the deposition distribution and deposition process of soot particles in the filtration process.At the same time,the pressure drop model of DPF is established in Fluent,and the permeability parameter alpha in the porous media model is modified to simulate the influence of different initial soot content and different deep/cake soot content on the pressure drop before and after DPF.The results show that: visual experiments show that soot mainly deposits near DPF outlet(end of filter channel).From DPF inlet to outlet,soot deposition height increases continuously.The deposition of soot particles in DPF channels can be divided into three stages: deep filtration,transition filtration and cake filtration.In deep filtration stage and cake filtration stage,soot deposition rate is slower and transition stage time is shorter,but soot particles deposition rate is faster during this period.The higher the soot concentration,the larger the gas flow rate,the more soot content in the air per unit time,and the earlier the transition phase occurs in the deposition process.Based on the modified model,the influence of different initial soot content on DPF pressure drop is simulated and analyzed.The results show that the pressure drop increases obviously when the initial soot content increases from 0 to 3 g/l,because most of the initial soot is in the deep soot deposition stage,and soot deposits inside the filter wall,resulting in a significant decrease in the permeability of the wall at the inlet surface.The pressure drop increases slowly with the increase of initial soot content,because the deep soot content is saturated and soot begins to deposit on the surface of the inlet channel,forming a cake layer,so the pressure drop curve slows down.Through the analysis of the influence of the proportion of deep soot on DPF pressure drop at different temperatures,the results show that the higher the temperature,the larger the proportion of deep soot,the greater the DPF pressure drop.