Performance enhancement of solar collectors partially filled with a porous absorber

An innovative technique for improving heat transfer using metallic foams has been widely used during the last years. In this study, analysis of thermal performance of a flat plate solar collector partially filled with a porous metal foam is presented. The Forchheimer–Brinkman extended Darcy model was used to model fluid flow in the porous region taking into account the influence of inertial force. The effect of viscous heating due to viscous dissipation were taken into account in the thermal energy equation. The coupled nonlinear momentum and energy equations in the porous and free flow regions were solved numerically. The influence of key parameters on the velocity and the temperature distributions were illustrated. The predicted numerical results were compared with the analytical solution and good agreement was obtained. The results indicate that the presence of porous metal foam in the half of the collector duct, besides increasing the fluid temperature more than conventional collectors, reduces the flow resistance and conserves the pumping power.