Masters Theses

Date of Award

5-2002

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemical Engineering

Major Professor

George C. Frazier

Abstract

The primarily aim of this research work was to develop a better understanding of electrically driven drop-drop and drop-electrode interactions in an aerosol flow chamber. A particular application of this technology is for treatment processing of radioactive droplets generated in tank waste at Department of Energy sites. In this research, experimental studies were conducted to explore methods of enhancing the agglomeration of micron sized particles. In such studies, the removal of aerosols by means of DC electric fields was investigated. As a high strength electric field is of importance when building a full-scale agglomerator, agglomeration experiments were carried out with the use of a DC electric field. An experimental setup was designed and built in which to carry out various aerosol experiments to produce the needed data for this research. The experimental setup consisted of two parallel electrodes, a laser-light-scattering particle sizing system, a rectangular test chamber, dry-ice trap, and a variable high voltage DC power supply. The experimental data were used to accomplish the following tasks: • Quantify removal of drops from an air stream by an electric field. • Measure drop size distribution along the flow chamber and determine the effect of an electric field on drop coalescence. The data indicate that the droplet removal efficiency increases approximately linearly with voltage over the range of voltages investigated, except for one case. In this case, there was no appreciable increase in droplet removal efficiency in the range of 24-26 kV, suggesting a saturation effect may be occurring. The analysis also shows that in general the removal efficiency is a function of initial droplet concentration. For instance, for a concentration of 24.23 g/m3, the maximum removing efficiency is approximately 85.5 percent while for the concentration of 8.32 g/m3 the maximum removing efficiency is 65.0 percent under the same experimental conditions. The analysis of the droplet distribution reveals that the mean size of droplets does not always change with voltage; however, the distribution of the number of droplets does change. Appreciable changes in the number of droplets were observed for droplet sizes in a typical range of 4 to 10 µm. The overall experience and knowledge gained in this research will be useful in developing effective applications of superimposed electric fields for the elimination of mist from air or gaseous streams.

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