Simulation Study On The Filtration Performance Of Gasoline Particulate Filters With Inhomogeneous Porous Wall

Since there are less and smaller particulate generated from gasoline direct injection engine than diesel engine,it is less likely for gasoline particulate filter to form a soot cake on the surface of the porous wall and small particulate may penetrate into the porous wall.As a result,the filtration efficiency will drop significantly and the filtration efficiency will be sensitive to the filter’s microstructure.In order to study the influence of microstructure on the filter’s filtration performance,a model was developed by MATLAB based on the probability density function(PDF)-based heterogeneous multiscale filtration(HMF)model which was developed by Gong Jian.In this paper,the inhomogeneous porous wall was represented by introducing pore size distribution,porosity distribution and permeability distribution at the same time.The influences of different porosity distributions and pore size distributions on the filtration performance of GPF were investigated.The results show that:1.As filtration goes on,the peak value of the collector size PDF increases and the range of the collector diameter decreases.Porosity and permeability of the filter wall gradually decreases to a stable value with time.The overall filtration efficiency and pressure drop of the filter wall increases with time and finally tends to a stable value,the increase rate of pressure drop first rises then falls.2.The higher the central porosity is,the greater the initial filtration efficiency is,also,initial pressure drop first drops then rises.The filtration efficiency at the same time increases and reaches to a stable value faster.The pressure drop of the filter tends to a stable value faster,and the stable value is smaller.3.As the difference between the porosity near the surface and the porosity at the center of the filter increases,the initial filtration efficiency increases,and the initial pressure drop first drops then rises.The filtration efficiency of the filter at the same time increases and reaches to a stable value faster.The pressure drop of the filter tends to a stable value faster,and the stable value is smaller.4.The initial filtration efficiency increases and the initial pressure drop decrease as the decrease from the high surface porosity to the central porosity slows down.The filtration efficiency at the same time decreases and tends to a stable value slower.The pressure drop of the filter tends to a smaller stable value slower.5.The initial filtration efficiency and initial pressure drop decrease as the mean pore size of pore size distribution increases.The initial filtration efficiency and initial pressure drop decrease as the pore size variance increases.6.Most of particulate mass is deposited at the layer with the highest filtration efficiency which is close to the entrance wall.With the increase of porosity,permeability increases first and then decreases.