DYNAMICS OF PYROGENOUS FUMES

Theoretical and experimental investigations of the dynamics of aggrega te aerosols have been conducted and led to the development of models t o describe the kinetics of agglomeration. The agglomeration rate is de termined by the mobilities of the agglomerate particles and by their c ollision cross sections. Agglomerate particles coagulate more rapidly than do dense particles due to their larger collision cross sections. Experimental studies have been conducted to explore a number of aspect s of the evolution of aggregate aerosols. The structure-drag relations hip has been explored by image analysis of transmission electron micro graphs of mobility classified aggregate particles. Structural rearrang ements during sintering of aggregates have been explored by heat treat ing aggregate particles while they are still entrained in the carrier gas. Particles are observed to retain the appearance of fractal cluste rs of smaller primary particles throughout coalescence that leads to m any primary particles from the original particle being incorporated in to a single primary particle in the sintered agglomerate. This observa tion raises serious questions about the inference of mechanisms of par ticle growth from structure measurements alone.