Resuspension of aerosols with influence of other fine particles by a centrifugal method

Abstract

Resuspension is an important phenomenon in many industrial and environmental processes. Previous studies of the resuspension of liquid droplets or solid particles have shown a deviation from actual situations. It is suspected that lack of consideration of the influences fine particles was as the major factor leading to the deviation. Many engineering or environmental processes, such as the spraying of pesticide and paint, disease transmission and filtration, involve not only a single type of particles. Understanding the detachment behavior can help us improve those engineering processes and reduce our exposure to air pollutants. This research studies the detachment behaviors of two common cases by a centrifugal method – Firstly, solid particles detachment from a dusty surface; secondly, droplets detachment with a fluid with nanoparticles suspended in it. For the first scenario, the detachment behavior of micron-sized polyethylene (PE) particles with the influence of fine dust particles on a surface was studied. The dusty surface was produced by settling Arizona test dust (ATD) on a cleaned Poly(methyl methacrylate) (PMMA) substrate by gravitational settling inside a deposition chamber. It was found that the adhesive force of PE particles decreased significantly with the increase of dust density. For the second scenario, the influence of the ultrafine particles suspension in micrometer-sized droplets was investigated by using a pure glycerol-water (pure fluid) and that with the addition of nanoparticles (nanofluid) on three different surfaces materials. It is found that nanofluid droplets detach by portion under normal force for all the substrate materials, and for tangential force, the droplets detach completely if the exerted force is sufficiently large. The threshold values are material dependent. The addition of nanoparticles results in a higher adhesive force when compared to the droplets of pure fluid within the same size range.

Date of Award	2017
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology