A Simulation Study on Particle Deposition and Filtration Characteristics in Wall-Flow DPF with Inhomogeneous Wall Structure Using a Two-Dimensional Microcosmic Model

A new two-dimensional wall-flow DPF microstructure model has been developed in this paper to investigate the particle deposition distribution in DPF channels and the deep-bed filtration process of DPF. The substrate wall of the DPF having a thickness of L is divided into several layers with a uniform thickness of Δy along the cross-wall direction, and each layer has specific porosity and pore size. The pressure drop, particle deposition distribution and the dynamic deep-bed filtration process of the DPF with inhomogeneous wall structure are studied under various space velocities. Besides, the differences on DPF’s performance brought by the inhomogeneous wall structure are discussed by comparing with a homogeneous wall structure. The numerical results reveal that the macroscopic filtration characteristics including mass-based filtration efficiency, pressure drop and particle distribution at the wall surface are closely related to DPF’s porous wall property, space velocity and particle size. The through-wall velocity has direct relationships with DPF’s global filtration efficiency and particle deposition distributions along the wall surface. As for the deep-bed filtration process, an obvious difference can be observed between the heterogeneous and homogeneous wall structure DPF. More particles are deposited on the layers which have low porosity and small pore size rather than the top layer of the heterogeneous porous wall. While for the homogeneous wall structure DPF, the number of particles penetrating into the porous wall is much more, which results in different dynamic variations on porosity and permeability in DPF during the deep-bed filtration phase.