Analysis Of Laminar Film Condensation On The Porous Wall Of A Vertical Tube

Résumé: A numerical study of laminar film condensation by forced convection of steam-air mixtures in a vertical tube is presented. The internal face of the tube wall is coated with a thin porous layer. A set of complete boundary layer equations governing the conservation of momentum, heat and mass is used to describe the transfers in the liquid film and the mixture. The flow field in the porous medium is described by the Darcy-Brinkman-Forchheimer model. These three phases are related with the continuity of velocity, shear stress, temperature, heat and mass flux at the interfaces. The dimensionless transfer equations are discretized using an implicit finite difference scheme. The liquid film thickness is determined by solving the liquid mass balance equation. Results were obtained for a saturated steam-air mixture. Profiles of velocity, temperature in the three media and vapor mass fraction in the mixture are presented. The effects of main properties of the porous layer such as thickness and Darcy number are highlighted. Additionally, the influence of the inlet Reynolds number and inlet vapor mass fraction of the mixture on the evolution of heat flux and condensate flow rate is also investigated.

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