A Study of Enhanced Heat and Mass Transfer From Variable Height Fin Array Undergoing Natural Convection

A numerical study is performed on simultaneous heat and mass transfer from a shrouded vertical nonisothermal variable height fin array, representing dehumidification process under natural convection. Fluid properties are treated as uniform, and the fluid is assigned to comply with Boussinesq approximation to include the effect of density variation with temperature and concentration. Semi-implicit method for the pressure linked equations revised (SIMPLER) algorithm is adopted to resolve pressure and velocity coupling. A detailed parametric investigation of fin spacing, variable fin height, and fin tip to shroud clearance for a range of thermal and mass Grashof number is undertaken. Results indicate that in case of smaller fin spacing, involving fin length of 0.3 m, coefficients of sensible and latent heat transfer increase with the decreasing variable height $(H1*)$ of fin and become maximum at $H1*=0.5$⁠, for all thermal and mass Grashof numbers considered presently. Further, total heat transfer analysis on a particular base length due to sensible heat shows a maximum of 24.4% enhancement, whereas same due to the latent heat shows a maximum of 25.8% enhancement, depending on the values of clearance. Induced velocities also increase with the decreasing variable height of fin $(H1*)$⁠, which influences the heat and mass transport. The output parameters of this analysis, like induced velocities and overall Nusselt numbers due to the sensible and latent heat, are correlated with the governing parameters. The correlation coefficients are found to be in a range from 0.97 to 0.99.