Study On Evaluation Method For Diesel Particulate Filter Reformation In In-use Heavy-duty Diesel

As the use of heavy duty diesel vehicles and non-road mobile machines,due to the poor quality of diesel fuel and lack of the proper maintenance for them,the emissions of particulate of diesel vehicles and machines are gradually deteriorating.To reduce the particulate emission of such diesel vehicles and machines,Diesel Particulate Filter(DPF)reformation for them is one of the most effective means.This paper mainly studies the matching method of DPF and diesel vehicles or machines.In the engine bench test,or during idle and free acceleration conditions,using Nano Met3 that is a particulate testing instrument to test particulate emission before and after DPF,then putting forward a set of evaluation method for DPF reformation which accords with the situation of our country.The main research contents and results of this paper are as follows.The purifying effect of DPF on diesel engine pollutants was verified by engine bench test.The maximum filtration efficiency of DPF for particulate matter(PM)is 96.33%,and the filtration efficiency for particulate number(PN)is greater than 99%,there is a good correlation between PM and PN emission.Meanwhile,DPF can significantly reduce the emission of CO and HC,but has little effect on NOx emission.The research on regeneration activation of DPF shows that,when the inlet temperature of DPF reaches 328℃,the pressure differential between the entrance and the exit of DPF is 95mbar,at this time,the DPF appears regenerative equilibrium state.The result of the research on diesel vehicles in shenzhen shows that,the amount of diesel trucks of country III stage accounts for the largest percentage of all diesel vehicle types,and the contribution to pollutant emissions is also the largest.Using on-line monitoring to monitor the distribution of exhaust temperature during vehicles driving,then we can select the DPF-three,DPF-four and DPF-five that the regenerative mode of them is passive regeneration to rebuild the post-treatment system of Postal trucks and Semi-trailer trucks,and the DPF-one and DPF-two that the regenerative mode of them is active regeneration to rebuild the post-treatment system of sanitation trucks.The comparison result of DPF filtration efficiency of different models is that,DPF-five>DPF-three>DPF-four>DPF-two>DPF-one.Finally,through the research of DPF reformation for vehicles and machines that we can conclude:the filtration efficiency of more than 90%DPF for PN is greater than 95%,and the maximum reaches 99.99%.For the vehicles and machines with the average concentration of PN after DPF that is greater than 1.0×10~6#/cm~3,the filtration efficiency of DPF is less than97%,meanwhile the DPF is prone to be clogged or burned during vehicle driving.For the vehicles and machines with the average concentration of PN after DPF that is less than 5.0×10~5#/cm~3,the filtration efficiency of DPF is greater than 98%,there isn`t going to happen that DPF doesn`t work.Therefore,according to the results of research,the evaluation method of DPF reformation in China can be determined:After DPF reformation for vehicles and machines,the initial filtration efficiency of DPF for PN must be greater than 95%,the initial emission of PN after filtering by DPF must be less than 5.0×10~5#/cm~3.When the durability of DPF is tested,the filtration efficiency of DPF must remain above 95%.