Ionized gas-solid suspension in an electric field

Abstract

The present work deals with the interaction of particulate matter with an ionized gas by including an external electric field and non-equilibrium states. A gas-solid suspension was considered as a mixture held close to equilibrium. Microscopically, the mixture was treated, by analogy to the kinetic theory, as an assembly of four kinds of small particles--electrons, ions, atoms and solid particles--interacting with one another. Since the particles gain energy from the applied electric field, it is possible for the four components to exist in a nonequilibrium state, each at a different temperature. For simplicity, in this study we consider only the case where the ions, atoms and solid particles are at the same temperature when an electric field is applied, and the temperature of the electron may be higher than the rest. A model of the interaction between a heavy solid particle and gaseous phase was proposed. According to these mechanisms and assumptions, equations were derived. Let us consider a system where initially neutral micron-sized solid particles are injected into an ionized gas, we shall designate the initial equilibrium number density of gas atoms, ions and electrons by nm m2, and n,s respectively. After the injection of an amount of solid particles, corresponding to a final number density n4, gaseous number densities will become ni, n2 and na to reach a new equilibrium. Furthermore, we shall assume n4 to be small comparing with the total number density, nt. The interaction between a solid particle and a gaseous phase is fairly complicated, however, only the following predominating mechanisms are considered in the analysis of this study: 1. Electrons which are emitted from a solid particle to the gaseous phase due to high temperature are considered as a part of free electrons in the gas-solid suspension system. If the initial charge of a solid particle is z,4, an emitted electron from the solid particle contributes the charge of the particle changing to z,4 ÷ 1. Such emission is known as thermionic emission. 2. Either a free electron or a free ion in the gaseous phase is no longer considered as free when it collides with a solid particle and is absorbed by the solid particle. Each ion or electron captured by the solid particle changes the solid particle charge from z~4 to z~4 q1 or z ~ 4 1 respectively. 3. Neither ionization nor recombination occurs when an atom collides with a solid particle.