Numerical Study of Pore Size and Distribution Effects on Gasoline Particulate Filter Performance

The improved brake thermal efficiency of Gasoline Direct Injection (GDI) engines is accompanied by a significant increase in Particulate Matter (PM) mass and higher Particulate Number (PN) emissions as compared to (multi)Port Fuel Injected (PFI) engines. Gasoline particulate filters (GPFs) with high filtration efficiency and low backpressure will be required to meet the future, stringent PM/PN regulations. A two-dimensional (2D) CFD study was performed to determine the effects of pore size and distribution on the interdependent performance parameters of filtration efficiency and back-pressure for clean GPFs. Simulation results show an on linear change infiltration efficiency as the pore size distribution tightens and determine a recommended distribution range, controlling the quantity of small-sized pores. Pore size distributions beyond this recommended range can cause a filtration performance loss or intolerable backpressure penalty for the GPF. In addition, a recent collaborative publication from our group has demonstrated our ability to create a hierarchical porous filter, with variable pore size in each layer. Knowing that filtration efficiency and pressure drop increase as the average pore size decreases offers inspiration for a novel wall design with small pores comprising the top 40% of the wall layers and larger pores on bottom 60%. The model predicts that such a wall would result in an 8% increase in filtration efficiency.