Diesel engines have been developed to address global warming and improve air quality and health around the world. Although particles produced by combustion in the cylinders of a diesel engine are emitted into the atmosphere, they can be dramatically reduced by over 99.9% after being trapped by a diesel particulate filter (DPF) and through the use of a diesel oxidation catalyst (DOC) in after-treatment systems. However, the phenomena and mechanism of the formation of these particles in the cylinders and the exhaust phenomena of the particles after being trapped by the DPF have not yet been clearly explained and the effects of a DOC on the formation of these particles are still not clarified. Thus, this study analyzes particle distributions, particle number(PN), particle components, sizes of single particles and aggregated particles exhausted from diesel engine, using JIS2 diesel and bio-diesel Fuel (BDF), in order to understand the effects of the engine load and speed of diesel engine, focus on nano-particle. This study also analyzes how nano-particles are trapped and loaded in DPF after through DOC and analyzes exhaust phenomena of nano-particles from a DPF to the atmosphere, in the case of trapping and loading process of nano-particles in DPF and the case of DPF regeneration process. Then the amounts of nano-particles in DPF based on loading and emitting balance are analyzes, too. The types of DPF are SiC and Cordierite in this study. So, many interesting results are obtained, for example the cluster size of aggregated nano-particles through DPF is larger than cluster size of nano-particles produced by engine combustion and single nano-particle size trough DPF is same as size of production by engine combustion. Finally, this study proposes a formation process for nano-particles produced by combustion in the cylinders of a diesel engine and an exhaust process for nano-particles emitted following an after-treatment system. Namely, journey of diesel nano-particles through after-treatment system to the atmosphere is summarized in this paper.
Mr. Kazutoshi Mori, part-time lecture, Teikyo University