Study On The Charactertistics Of Continuous Regeneration For Wall-flow Diesel Particulate Filter

As the diesel emission standards become stricter and stricter, wall-flow dieselparticulate filters (WFDPF) are being the indispensable device for reducingparticulate emissions. Compared with Burner–type system, Microwave heating andother active regeneration technologies, the Continuous Regeneration Technology(CRT) does not require the additional control system and heat sources, which is oflow-cost, wider regeneration window and other advantages. Hence, CRT has become apredominant regeneration technique. However, the relevant research indicates thatthe performance of CR-DPF is still not ideal in the low-temperature regions. Theproblem not only directly affects the working life of the system, but also affects thedynamic performance and fuel economy of engine. How to improve the reliability ofCR-DPF in the low-temperature regions becomes a serious problem.Hence，this paper is supported by National863Program (2008AA11A116),National Natural Science Foundation of China(50876027) and National NaturalScience Foundation of China(51176045). Based on the physical models andnumerical simulation, the regeneration performance and regeneration characteristicsof CR-DPF were studied. The main work and innovations of this paper are asfollows:(1) The chemical kinetic model of oxidation catalytic converter (DOC) isdeveloped. The impact of emission parameters(the flow rate and temperature of theexhaust stream, O2concentration, NO2concentration) and the carrier structureparameters (volume, the ratio of length to diameter, pore density, the thickness ofpore)on the performance of DOC is studied based on numerical simulation，theresults provide some theoretical basis for the structural optimization andperformance improvement of the DOC.(2) A one-dimensional quasi-steady-state model of the wall-flow particulatefilter NO2assisted regeneration is developed. By changing the emission parametersand Structural parameters of the filter body, the regeneration properties and pressuredrop characteristics of DPF are analyzed; the results provide a certain basis forstructural optimization and performance improvement of DPF.(3) In this paper, the continuous regeneration “balance point” is proposed as theperformance evaluation of CR-DPF in the steady state. Weight analysis of the emission parameters on the regeneration “balance point” is discussed based on thesimulation results and grey relational theory. Besides, the influences of the volumeratio between the DOC and DPF on pressure drop and conversion efficiency of thesystem are obtained.