FILTRATION CHARACTERISTICS OF FUEL NEUTRAL PARTICULATES USING A HETEROGENEOUS MULTI-SCALE FILTRATION MODEL

Filtration characteristics of fuel neutral soot particulate were studied using a recently developed heterogeneous multi-scale filtration (HMF) model. In the HMF model, a PDF based pore size distribution and a porosity distribution across the filter wall are introduced to represent the heterogeneous multi-scale porous structure. The HMF model was validated by an exhaust filtration analysis (EFA) system, which was designed for fundamental experimental filtration studies. Various sources of particulates from combustion engines were used in the filtration studies. Some particulates were sampled from a spark ignited direct injection (SIDI) engine fueled with gasoline and ethanol blends. Particulates from a compression ignition engine fueled with diesel for conventional and advanced combustion regimes were investigated as well. The micro-structure of the porous wall was found to be more critical and necessary to simulate filtration of particulates from gasoline and advanced diesel combustion engines than those from conventional diesel combustion engines. The interactions between the porous wall and trapped particulates were investigated. The dynamic filtration characteristics including filtration efficiency, pressure drop and particulate distribution inside the wall are strongly dependent on total particulate volume rather than total particulate number concentration. The change of the filter structure as well as the shape of the particulate size distribution play important roles on particulate penetration.