Dispersion of Aggregate Particles by Acceleration in Air Stream [Translated]†

Abstract

To clarify the dispersion mechanisms of aggregate particles in air, the dispersion of aggregate particles by acceleration in an air stream, which is a typical dispersion mechanism, was examined. In the experiment, aggregate PSL (polystyrene latex) particles (primary spherical particle diameters are: 5.2 and 2μm) were fed into an ejector, where aggregates were dispersed into smaller sizes by acceleration in a high-speed and high pressure (critical pressure higher than atmospheric pressure) air stream. Dispersed PSL particles were introduced into a sampling chamber and sampled on several slide glasses set on the bottom of the chamber by gravitational deposition. PSL particles thus sampled were observed with a microscope. This method allowed exact evaluation of the numbers of primary particles consisting of aggregates. It was suggested from the experiment that aggregate particles consisting of about 5μm primary particles were almost entirely dispersed into primary particles by acceleration of the particles in the ejector. The dispersion force acting on aggregate particles in an air stream at high Reynolds number was theoretically analyzed for a model aggregate particle and compared with the existing van der Waals adhesive force. It was found that the experimental results could be well explained by the theoretical comparison between the dispersion and adhesion forces.† This report was originally printed in KAGAKU KOGAKU RONBUNSHU 18(2), 233-239 (1992) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Chemical Engineers, Japan.