THESIS
2017
xii, 90 pages : illustrations (some color) ; 30 cm
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; s...[
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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.
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