Study for Effects of Bio-Diesel Fuel and After-Treatment Systems on Formation and Reduction of Particles from Diesel Engines

摘要

Diesel engines are highly potential for better fuel economy due to a high thermal efficiency and fuel diversity. They are largely expected to contribute to a low carbon society in the future. Diesel engines have been developed for the purpose of controlling global warming and improving the air quality and health effects in the world. Although particles produced by combustion in cylinders of the diesel engines are emitted to the air, they are dramatically reduced by beyond 99.9% after being trapped by a diesel particulate filter (DPF) and a diesel oxidation catalyst (DOC) of the after-treatment systems. However phenomena of the formation of the particles in the cylinders and exhaust behaviors of the particles after being trapped by the DPF are not clearly explained yet (1)-(6) and effects of the DOC on the formation and the reduction of the particles are still not clarified (7)(8). This study analyzed particle distributions, particle number (PN) and particle components with diesel and bio-diesel fuel (BDF). First, this paper describes that the BDF more reduced the engine out PN concentration, comparing with the JIS#2 diesel fuel (9)(10). Further, this paper introduces how the particles were trapped by the DPF equipped on the diesel engine and were emitted through the DPF to the air, based on the detail measurement of the number of particles. Each particle size distribution was analyzed by DPF type, SiC-DPF and cordierite-DPF. In this study, effects of the DOC on behaviors of the particles with each type of the DPF are also described. This paper presents photographs of the particles generated by combustion of the JIS#2 diesel fuel and the BDF, and the particles in the tail pipe after through the DOC + SiC-DPF of after-treatment system.