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Unformatted text preview: 66 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 34, NO. 1, JANUARY/FEBRUARY 1998 Modeling of Conductive Particle Behavior in Insulating Fluids Affected by DC Electric Fields Lucian Dascalescu, Senior Member, IEEE, Michaela Mihailescu, and Robert Tobaz´eon, Member, IEEE Abstract— Several electrostatic technologies, such as separation of granular mixtures, flocking, printing, or biological cell manip- ulation, are based on the accurate control of conductive particle motion in insulating gases or liquids by means of relatively high dc electric fields. This paper aimed at characterizing the behavior of such particles by numerical modeling of two aspects: 1) particle motion under the action of electric field forces and 2) insulation breakdown triggered by mobile particles. The equations of parti- cle motion were written by taking into account both gravitational and drag forces, as well as the rebound at particle impact with the electrodes. If the particles move in ionized air, their charge varies in time. In that case, the equation of particle charge should be added to the mathematical model. The output data of the programs for numerical simulation of particle behavior are in good agreement with the available experimental results. Particle movements were shown to be influenced by the intensity of the electric field, by the density of the space charge, by size and mass density of the particles, as well as by their coefficient of restitution at impact with the electrodes. The conclusions regard- ing the behavior of conductive particles in insulating fluids are useful for the development of improved electrostatic separation technologies; they are of particular interest to all manufacturers of high-voltage equipment. Index Terms— Corona, electric field, electrostatics, granular materials, insulating fluids, numerical methods, particle, space charge. I. INTRODUCTION V ARIOUS electrostatic technologies, such as separation of granular mixtures, precipitation of dust, spraying of powders, flocking of fibers, printing, or biological cell manipulation – make use of the electric forces in order to achieve accurate control of particle motion in insulating gases or liquids. The presence of mobile conductive particles in electrostatic separators, filters, sprayers, and printers, as well as in various types of high-voltage apparatus, was proved to Paper MSDAD 97–05, presented at the 1996 Industry Applications Society Annual Meeting, San Diego, CA, October 6–10, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Electrostatic Processes Committee of the IEEE Industry Applications Society. Manuscript released for publication August 1, 1997....
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This note was uploaded on 06/08/2011 for the course ELECTRICAL 124 taught by Professor Ghjk during the Spring '11 term at Institute of Technology.
- Spring '11