Effect of membranes in exhaust particulate filtration

This chapter describes results of an experimental and simulation study on the influence of material properties like porosity and pore size on filtration efficiency and back pressure behavior, comparing both substrates made of porous LPS-SiC and membrane coated samples. A test rig was deployed which contains two sample holders for both honeycomb segments and flat disc shaped samples, as well as a dust disperser to produce loaded air with a specified content of particles. The simulation results can be used in reversed order to test virtual materials and material combinations. The attempt was to find a membrane/substrate combination that may avoid particle penetration into the wall as well as too much initial pressure drop penalty by the membrane. Pressure drop increases linearly with loading, falling below the pressure drop of the substrate sample very fast. This behavior corresponds perfectly to the predicted behavior by simulation. Porosity and pore size of filter ceramics influence the evolution of the back pressure increase and the filtration efficiency with fine particle loading. Measurements on substrates made of LPS-SiC filter ceramics and simulation on micro- and mesoscale confirm this known behavior. Membranes with very fine porosity increases filtration efficiency.