Thermocapillary effect on drying of a polymer solution under non-uniform radiant heating

Abstract

This theoretical investigation analyzes the two-dimensional heat and mass transfer characteristics arising from the cion-uniform radiant incidence in polymer solutions whose motion is governed by combined thermocapillary/ buoyancy laminar flow. Also considered herein is the evaporation of solvent at solution surface. The effects of various radiation input, external convective parameters, and important physical properties of solutions on the drying characteristics are investigated and results are presented in terms of flow, thermal, and concentration fields, and rate of water removal. In addition, the influence of thermocapillary effect on drying features is also examined. Numerical results indicate that absorbed energy and distribution of the solvent concentration dominate the drying rate. At larger surface tension Reynolds number, more mass concentration can be transferred by thermocapillary flow from the interior region to the surface, which then increases drying rate. Furthermore, removing the solid wall effect reduces the drying time required for a solution film with two sides of symmetric surfaces, which is irradiated by an array of infrared radiant heaters. (C) 2000 Elsevier Science Ltd. All rights reserved.