Study On Flow-field And Optimum Design Of Diesel Particulate Filters

With the development of national economy and the increase of automobile's quantity, the automobile's emission problems become more and more serious. Especially, the diesel particulate can hardly satisfy the new regulation of the automobile emission. It is seriously necessary to design an efficient, energy-saving and practical device, which is called diesel particulate filter (DPF).The design of the DPF was a complex process, primary involving the design of the filter body and its regeneration. In this paper, honeycomb wall-flow monolith was adopted as the DPF's filter body, in order to optimize the design of the DPF, the pressure loss and the filtration efficiency was investigated by analyzing the flow-field in the DPF. Firstly, on the basis of analyzing the physical model and the pressure loss in the honeycomb wall-flow monolith, the corresponding equations of the flow governing and the pressure loss were established. The velocity-field and the pressure-field of the flow in the DPF were researched by FLUENT for the first time in China, and it was found out that the wall of the porous ceramic was the main factor of the pressure loss. Secondly, the particulate trapping model of the porous wall of honeycomb wall-flow monolith was established; further more, the three kinds of particulate trap mechanism, diffusion trap, direct interception trap and inertia trap, and their filtration efficiency were analyzed in detail. At last, the relationships of honeycomb wall-flow monolith structure parameter with the pressure loss and the filtration efficiency was researched. And the conclusion that the filtration efficiency would be increased with the augment of the filtrating area was gained. The DPF was optimum designed for the aim of reducing the pressure loss and increasing the filtration efficiency.In conclusion, the development cycle and cost of the diesel particulate filter can be reduced effectively by using the technology of computer aided analyse and design. In this paper, the simulation results were consistent with experiments, which proved that the mathematical model and the method were correct, and point out a new direction for numerical simulation of the DPF. It is significant to further the investigation of the flow-field and the regeneration of the DPF.