INTERACTION OF SURFACE RADIATION WITH FREE-CONVECTION IN A SQUARE CAVITY

A numerical investigation of free convection in a rectangular enclosure has been carried out based on Gosman's finite volume method with a 21 x 21 nonuniform grid. A radiation model has been included in the analysis to study the effect of surface radiation on the heat transfer characteristics of the enclosure. The model is general since it takes into account different emissivities for the side walls and for the top and bottom walls. The nonuniform grids for convection have been retained for radiation, notwithstanding the fact that the evaluation of view factors becomes highly tedious. The view factors are evaluated by Hottel's crossed-string method. Nonuniform grids for both convection and radiation routines ensure grid compatibility and yield convergent solutions. The model has thrown light onto the importance of surface radiation even at low emissivities and temperature levels and provides an explanation of the discrepancies between the experimental and theoretical correlations. A parametric study of surface radiation effects is also presented.