Numerical and Analytical Study of Exhaust Gases Flow in Porous Media with Applications to Diesel Particulate Filters

Abstract

Problem statement: The importance of diesel particulate filter has been increased later because of its ability in making emission reduction of the exhaust gasses. Diesel Particulate Filters (DPF) do two important jobs: gas emissions reduction and noise reduction, the pores spread inside the DPF store some gases and soot emissions and on the other side it prevents some sound or noise to be gone outside, so it works as a noise reduction device or unit. Diesel particulate filter is considered as a porous media, it's very important to study the flow behavior in such media in order to redesign dimensions, specifications and location of diesel particulate filter on the exhaust pipes. Approach: The flow of gasses through the Diesel Particulate Filters (DPF) unit is studied here analytically and numerically to reach for the best equation describes the real nature of flow behavior. The analytical model is built to find the velocity of flow, pressure drop and nature of flow-laminar or turbulent- at two conditions at cold conditions (25˚C) and hot conditions (500˚C). Also the problem is solved numerically using some appropriate software. A comparison was made between both analytical and numerical results especially the pressure drop effect. Some appropriate software used to describe the reality of the gasses flow through porous media. Results: It was found that the nature gases flow in DPF is laminar; a pressure drop through the DPF was occurred, gases axial velocity, vertical velocity, temperature are all decrease as such gases go through the filter. Vertical velocity's values were very small compared with the axial velocity's values. Conclusion/Recommendations: Gases pressure is decreased as such gases flow along the DPF unit and exhaust system, so there is a pressure drop. Temperature distribution and profiles showed that the values of temperature have a fluctuation along the DPF unit. Axial and vertical velocities were decreasing as the gases flow through the DPF unit and the exhaust system. It is recommended to study the flow as a non-linear 3D problem.