Abstract: In this study, microcosmic capturing mechanism of single unit on diesel engine particles is firstly studied，then, macroscopical filtration model of single porous medium bed and trap model of monolithic wall-flow diesel particulate filter (DPF) on particulate matter (PM) are developed and formulated. Effects of main DPF structural parameters on filtration performance of different size particles from diesel engines are studied. The results show that the trap efficiency of 10 nm diameter particles is highest, and the efficiency descends while the particle diameter increases. The trap efficiency will be lowest near 500 nm diameter particles, and the trap efficiency ascends with particles diameter increasing to 1μm continuously. This indicates the complex effects of diffusion, inertia and interception mechanisms on particle trap. With increasing cell density, wall thickness, diameter and length of filters, the filtration efficiencies of different size particles ascend with different extents. The trap efficiencies rapidly increase with decreasing porosity and mean pore size of filter substrates. These results are valuable for matching DPF structural parameters and improving filtration performance of DPF.

Key words: Diesel engine, Filter, Filtration performance, Particle size, Particulate matter, Structural parameter