Radiation heat transfer effect on natural convection in asymmetrically heated vertical channels

Heat and mass transfer in vertical channels with a heated ribbed wall is investigated numerically and the results coming from two different CFD codes are compared. The codes are based on finite volume (Fluent 6.2) and on finite element approach (COMSOL Multiphysics) respectively. The channel is two dimensional, is set in vertical position and it is bounded by a heated ribbed wall facing an adiabatic smooth wall. The effects of the aspect ratio, the temperature difference between the heated wall and the ambient, the thermal conductivity of the ribs and the emissivity of the heated wall are considered. The results show that small aspect ratios and low thermal conductivity ribs have a negative effect on heat and mass transfer. High temperature differences and high emission coefficients for the heated wall, on the contrary, lead to a strong enhancement of the channel heat and mass transfer.