Numerical study on flow and pressure drop characteristics of a novel type asymmetric wall-flow diesel particulate filter

Abstract

In order to reduce the pressure drop and regeneration cost of diesel particulate filters (DPFs), and improve the power and economic performance of the diesel engines, a novel type of asymmetric channel wall-flow filter was proposed, including the regular hexagonal and triangular channels, as well as the rectangular channels. A one-dimensional mathematical model was built to study the flow characteristics, especially pressure drop performance, for this type of particulate filter, as well as a square symmetric and a square asymmetric channel filter for comparison. The effects of exhaust gas flow rate, cell density, wall thickness, and aspect ratio were numerically accessed. The results show that the novel asymmetric channel filter can effectively reduce the lifetime pressure drop by increasing the utilization ratio of the filtration wall and the filtration area. Specially, with the novel asymmetric channel structure, the wall pressure drop is considerably reduced owing to a lower mean wall penetration velocity. Furthermore, the depth layer and soot layer pressure drops of the novel type filter are much lower than those of the square symmetric channel filter owing to the smaller penetration velocity and thinner thickness of the soot layer, nearly the same as those of the square asymmetric channel filter. Additionally, the filter with a smaller aspect ratio can slightly reduce the pressure drop, so it can be practically applied if the distribution of the inlet gas is uniform. The novel asymmetric channel filter can meet the current and future demand for miniaturization and light-weighting of particulate filters, and has excellent market adaptability.