Thermophoresis of an Aerosol Sphere with Chemical Reactions
Abstract:The thermophoretic motion of a spherical aerosol particle undergoing a chemical reaction in a uniformly prescribed temperature gradient is studied theoretically in the quasisteady limit of negligible Peclet and Reynolds numbers. The chemical reaction taking place within the particle can be either endothermic or exothermic. The Knudsen number is assumed to be small (of the order 0.1) so that the fluid flow is described by a model with a thermal slip, a temperature jump, and a frictional slip at the surface of the particle. The energy and momentum equations governing the system are solved analytically, and explicit expressions for the thermophoretic velocity of the particle are obtained. Results of the effect of the chemical reaction inside the particle on its thermophoresis are presented for various distributions of the composition-dependent factor or heat generation parameter of the chemical reaction as well as the relative thermal and surface properties of the aerosol sphere. When the composition-dependent factor is not a function of position, the thermophoretic velocity of the particle is enhanced when the reaction is exothermic and reduced when the reaction is endothermic. In general, the effect of the chemical reaction on the thermophoretic velocity can be significant in appropriate situations.
Document Type: Research Article
Affiliations: Department of Chemical Engineering,National Taiwan University, Taipei,Taiwan, Republic of China
Publication date: March 1, 2012