Abstract
In comparison with port fuel injection (PFI) engines, gasoline direct injection (GDI) engines have higher fuel efficiency. However, there are more particulate matters (PMs) including soot in the exhaust gas. Then, we need gasoline particulate filters (GPFs) with high filtration efficiency for the future stringent PM emission regulations. In this study, we simulated the filtration process on the pore-scale of the filter wall by a lattice Boltzmann method (LBM). The structure of filter wall was obtained by an X-ray CT technique. We discussed pressure drop and initial filtration efficiency, which are important characteristics of GPFs, by changing the inlet velocity of exhaust gas and soot particle size. Results show that, as the soot particle size is smaller, the thicker soot cake layer is formed on the surface of the filter wall, resulting in the smaller pressure drop. The initial filtration efficiency is higher as the particle size is smaller due to the Brownian diffusion. Moreover, when the particle size is larger, the interceptional effect is dominant, and the initial filtration efficiency is higher. As the inlet velocity is smaller, the thicker soot cake is formed on the surface of the filter wall due to the higher filtration efficiency. The pressure drop decreases as the inlet velocity is smaller.
