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Three types of after-treatment for reduction of diesel exhaust particulate are investigated mainly about their characteristics of filtration and regeneration. They are ceramic foam filter (CFF) and microwave regeneration (MR), stainless steel net trap with electrostatic collector (SSNTEC) and reverse jet regeneration (RJR) with high pressure gas, wall flow ceramic filter (WFCF) and infrared heating regeneration (IHR). With the data from experiments, the filtration efficiency of CFF is up to 60% and the efficiency of MWR reach 80% upward. The average efficiency of SSNTEC is about 60% and the efficiency of RJR is just 55%. WFCF and IHR have outstanding performance, the efficiency of WFCF reach 90% upward and its IHR is complete.

It is a new idea and beneficial attempt that the microwave heating technology is applied to regenerate the Diesel Exhaust Particulate Filters (DEPF). In this paper, the microwave regenerating mechanism of DEPF is studied and some laws in the process of microwave regeneration are found by experimental and theoretical analyses. Some basic measurements and calculations of microwave characteristic factors of three kinds of selected DEPF and the pure particulate are presented. A Microwave Regenerating Test System (MRTS) is set and the microwave regeneration of DEPF is tested. A mathametical model of two dimensional axi-symmetrical non-steady temperature field is set up which is suitable for microwave regenerating process of ceramic foam filters. The numerical calculation and practical analyses are stated. It is proved by these studies that the particulate in DEPF is selectively heated by microwave energy and moreover the microwave energy is less absorbed by the pure ceramic filters.