The Influence of a Ceramic Particle Trap on the Size Distribution of Diesel Particles.
Proc Soc Automot Eng Int Congr &expo on Diesel Particulate Control detroit mi 1985 :12 pages
The Bureau of Mines sponsored research to determine the particle size distribution and concentration of submicrometer particles upstream and downstream of a ceramic particle trap mounted in the exhaust stream of a caterpillar 3304 diesel engine. Particle size distribution and mass were measured with an electrical aerosol analyzer, a diffusion battery-condensation nuclei counter combination, and filters. The engine was operated at 1,400 and 1,800 rpm and three load conditions at each speed. In general, the collection efficiency of the trap was high, ranging from 89% to 96%. Size distribution analysis revealed that the trap was generally more efficient at removing particles smaller than 0.1 Um diam than larger particles. However, under certain conditions formation of nuclei downstream of the trap took place. This is probably associated with the penetration of hydrocarbon vapors through the trap that nucleate to form very fine particles as the exhaust is diluted and cooled. Particle concentration measurements during regeneration revealed significant transient particle generation. A large concentration peak of accumulation mode size particles appeared shortly after the onset of regeneration, followed by a broader peak of nuclei mode size particles. It is believed that the accumulation mode particles result from oxidation and breakup of particles deposited on the trap while nuclei mode particles result from nucleation of hydrocarbon vapors driven from the trap during regeneration.
Proc. Soc. Automot. Eng. Int. Congr.& Expo. on Diesel Particulate Control, Detroit, Michigan, 1985, 12 Pp