Surface Profile and Internal Structure of Particle Bed Formed by Deposition of Aerosol Particles

Abstract

Aerosol particles flowing in a circular duct deposit on the inside wall and form a loosely packed particle bed. These particle beds have been investigated for both unipolarly charged and uncharged aerosol particles, with particular attention to surface profile and internal structure. It was found that the surface roughness of the particle bed increased with the mass of particles deposited per unit area (dust load). The roughness was greater for unipolarly charged particles than for uncharged particles. Scanning electron micrographs revealed that the particle bed was formed by aggregates, and was packed more loosely for charged particles than for uncharged particles. Packing fractions of these particle beds increased with increasing dust loads and gradually approached their respective maximum values. Differences in the structure of the particle beds were qualitatively explained by a simple computer simulation where the electrical polarization of charged particles was taken into consideration.