COMBINED HEAT AND MASS TRANSFER IN NATURAL CONVECTION ON INCLINED SURFACES

Abstract

The combined heat and mass transfer characteristics of natural convection flow along inclined surfaces are studied analytically. The buoyancy forces arise from both temperature and concentration variations in the fluid. In the analysis, the diffusion-thermo and thermo-diffusion effects are neglected, as are the interfacial velocities resulting from mass diffusion. The surfaces are either maintained at a uniform temperature/concentration or subjected to a uniform heat/mass flux. The important parameters of the problem include Prandtl and Schmidt numbers, thermal and concentration Grashof numbers, the relative buoyancy force effect between species and thermal diffusion, and the angle of inclination from the vertical. Numerical results are presented for diffusion of common species into air and water. For both heating/diffusing conditions, the wall shear stress and the local Nusselt number are found to increase and decrease as the buoyancy force from species diffusion assists and opposes, respectively, the thermal buoyancy force. The mass transfer parameter or the local Sherwood number increases as the thermal buoyancy force increases. In addition, the net effect of the combined buoyancy forces on the surface heat and mass transfer diminishes as the angle of inclination from the vertical increases. Finally, a comparison is made between results from the uniform wall temperature/concentration and the uniform surface heat/mass flux.