Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
An experimental study was performed to investigate the heat transfer characteristics of the convection flow through a rectangular air duct with aspect ratio of 10 (a/b=10) which is filled with metallic porous materials. All four walls of the duct are subjected to a constant and uniform heat flux. The Reynolds number based on the hydraulic diameter has been kept between 500-2000 in order to ensure the laminar flow through the duct. The effect of different parameters such as variable porosity and density of porous layers have been investigated. For different porous layers configuration, heat flux at the walls, wall temperatures and air mass flow rate has been measured and the Nusselt number has been calculated. The results are compared with the clear flow case where no porous material was used. It can be concluded that higher heat transfer rates can be achieved in porous media flow case at the expense of a reasonable pressure drop. Based on the experimental data new empirical correlations for both Nusselt number and friction factor have also been developed for such air duct, which gives a good agreement between predicted values and experimental values of Nusselt number and friction factor.