Modeling analysis of moist air condensation on a plate under forced convection conditions

Abstract

A modeling analysis of the filmwise condensation for water steam outside a vertical plate under forced convective conditions was carried out in this study. The latent heat and sensible heat transfer under different moist air temperature, relative humidity, velocity, and wall temperature were theoretically analyzed. The model was developed based on the conservation equations of mass, momentum, energy, diffusion, and was solved numerically by finite difference methods. Meanwhile, the presence of condensate was neglected due to the low condensation load. Firstly, the results were compared with classical correlations and showed good agreement. Then the variation of latent and sensible heat transfer changing with operation conditions, such as moist air temperature, water steam mole fraction, wall temperature, and moist air velocity, were obtained and analyzed in detail. The results indicated that the latent heat transfer coefficient increased with the increase of relative humidity, moist air temperature, velocity, and cooling wall temperature. At the same time, the sensible heat transfer coefficient remains almost constant except under different moist air velocities, and latent heat transfer coefficient accounts for more than 70.3% in all the tested conditions of this study. The results obtained in this study can give a reference for the design of heat exchangers used in moist air condensation conditions.