Spreading of a Viscous Liquid Film over the Corrugated Surface and the Heat and Mass Transfer Calculations

摘要

There are a lot of industrial applications of structured packing. Distillation columns are one of theexamples where the liquid flows over the corrugated surface as a thin film to provide a good mass-transfer sur-face between the liquid and vapor phase. The purpose of the present paper is to study the hydrodynamics andthe heat-mass transfer of the liquid film spreading down the corrugated surfaces when the corrugation ampli-tude is comparable with Nusselt's film thickness (the amplitude corresponds to a small texture of the structuredpacking). As a result, a nonlinear type diffusion equation is obtained to describe the evolution of the film thick-ness profile. The nonlinear diffusion coefficient is obtained for three cases: a smooth inclined plate, a corrugatedplate with large ribs, and an inclined corrugated plate with small ribs. The equations are solved numerically. Asa result, it has been obtained that the small texture significantly increases the rate of the film thickness evolutionin comparison with a smooth plate. To obtain the nonlinear diffusion coefficient in the case of a small texture,the hydrodynamics of the film flow over an inclined corrugated surface are studied. The viscosity, inertia, andsurface tension forces are taken into account. The calculations were carried out on the basis of the Navier-Stokes equations. The influence of the microcorrugations on both the heat transfer from the wall and the masstransfer through the free surface was investigated.