Abstract: A numerical study is described for combined forced convection and radiative heat transfer. The humid air supposed to be a perfect gas in a boundary layer approached laminar flow is confined between two coaxial cylinders. The inner cylinder, covered by a thin water film, is assumed to be adiabatic, while the outer is thermally insulated and dry. The numerical model, based on the finite volume technique is used to solve the one dimensional Navier-Stokes and energy equations. The radiative part of this study was solved using the “Ray Tracing” method, associated with the “Statistical Narrow Band Correlated–k” (SNBCK) model. This study has been made of the effect of gas radiation and the influence of dry surface emissivity are presented. Results showed that the gas radiation remains non negligible and acts as an influent factor in the humidification process. Also, increasing the dry surface emissivity results in a rising of the humid surface temperature and the evaporated flow rate.

Keywords: Film evaporation, forced convection, thermal radiation, non-grey gas, SNBCK4 model