307 SEM観察と初期PM捕集過程の検討(大気環境保全・改善技術(2))

概要

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In recent years, environmental regulation tends to become strict rapidly, and the further highly performance of DPF is demanded, which mainly consists of surface filtration and depth filtration. Generally, if the wall thickness is thin, the soot in diesel exhaust gas may break through and leak the filter, because the depth filtration doesn't work enough. However, most of filtration efficiency depends on surface filtration, because the soot layer forms on the surface of ceramic filter, and the soot layer takes part in highly performance of the filter. In this study, we pay attention to the surface roughness of ceramic filter with soot layer forming. We observed the micro-porous structure of the filter based on SEM images, and measured surface roughness of initial PM filtration of DPF. Also, we measured particle number concentration and particle size distribution at the DPF exit. Results show that, as the soot layer is formed on the filter surface, the filtration efficiency becomes high and the surface roughness becomes smooth. Thus, it is confirmed that there is a relationship between filtration efficiency and surface roughness.
2010-06-26