Porous Glass Composite as Diesel Particulate Filter and the Microwave Regeneration LEE Chang Chuan1,a *, YOSHIKAWA Noboru 2,b and TANIGUCHI Shoji 2,c 1
School of Manufacturing Engineering, Universiti Malaysia Perlis, Kampus Tetap Ulu Pauh, 02600 Arau, Perlis, Malaysia 2
Graduate School of Environmental Studies, Tohoku University, 6-6-02 Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-9879 Japan. a
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Keywords: microwave regeneration, porous composite, diesel particulate filter
Abstract:In this study, porous SiO2 polyurethane sponge replica method. Porous samples obtained through sintering consist of well dispersed and distributed stainless steel particles within the glass matrix. Such microstructure is desired for the purpose as a soot particulate filters (DPF) utilizing microwave rapid and selective heating characteristic, especially during the cold start phase of an engine. Results of microwave heating ability and diesel soot regeneration tests shows that, the fabricated porous composite material is proven to be reliable for rapidly microwave assisted regeneration. Both the regeneration temperature and O2 composition in the supplied gas played an important role in the regeneration process. Introduction Diesel engines are superior to conventional gasoline engines with regard to fuel consumptions, which reduces CO2 emissions and helps suppress global warming. These engines, however, produce more NOx as well as particulate matter (PM) [1]. In response to the environmental and health concern from the emission of diesel particulate matter (DPM), governments over the world have continued to impose more stringent regulations restricting its emissions. Among techniques that have been designed to reduce the particulate emission, diesel particulate filters (DPF s) have been considered as the best option. However, with accumulation of the DPM in the filter media, the pressure drop across the filter increase which in-turn exerts a back pressure on the engine exhaust, resulting in gradually poorer engine performance. Therefore, effective regeneration of the filter by continuously or periodically burning off the trapped DPM is of important. Self regeneration of DPM is not possible due to high ignition temperature, typically 500 650 oC [2], and low engine exhaust temperature, generally lower than 400 oC. Therefore, an additional measure is needed to get rid of the trapped soot. Few studies utilizing microwave power for the regeneration of trapped filter has been reported in the literature [3-7]. Microwave heating significantly differs from conventional heating, as the energy is strongly concentrated in the material itself. Microwaves penetrate the material at a depth depending on the dielectric permittivity, resulting in a heating from the inside out. Microwave heating is very rapid and selective. With the choice of proper material as filter substrate, it can easily provide high temperature needed for DPM combustion and DPF regeneration [6-8]. In additional, microwave energy can be deposited directly to the DPM which is collected in the DPF. However, microwave assisted DPF regeneration has been experienced with uneven energy distribution which result in hotspots during DPM oxidation reaction [9]. The primary aim of the present work was to fabricate a filter material which can be heated up evenly by microwave for DPM regeneration. A porous glass-metal composite has been developed to serve as the DPF instead of using cordierite honeycomb ceramics. Experiments have been conducted in a 2.45 GHz (2 kW) single mode applicator to measure the efficiency of regeneration of the fabricated filter by varying the regeneration temperature and oxygen content.
