Thermal radiation contribution on humidification process in a cylindrical annular duct
A. Sakly, A. Mazgar, K. Slimi and F. Ben Nejma
The current study aims at presenting a numerical computation of combined forced convection and radiative heat transfer in humid air, supposed to be a perfect gas in a boundary layer approached laminar flow and confined between two coaxial cylinders. The inner cylinder, covered by a thin water film, is assumed to be adiabatic, while the outer is considered to be isothermal and dry. The classical finite volume method is used to solve numerically the governing set of conservation equations whereas the radiative part of the study is overcome by using the “Statistical Narrow Band Correlated–k” (SNBCK) model, in association with the “Ray Tracing” method. The effects of ambient conditions, channel dimensions, dry cylinder temperature and gas radiation are analyzed. The results show that even if it is not the dominant heat transfer mode, gas radiation plays a fairly important role in the evaporation process, contributing effectively to the dynamic and the thermal conditioning of the system and having a great effect on the saturating vapor temperature.
Keywords: thermal radiation, SNBCK4 model, non-grey gas, forced convection, evaporation