Experimentally validated analytical expressions for the thermal efficiencies and thermal resistances of porous metal foam-fins

Abstract

Novel, analytical expressions are developed for the thermal efficiency and thermal resistance associated with forced convection and conduction within a cylindrically shaped, open porous medium that is attached concentrically to a circular tube. Using the new analytical expression in conjunction with a two-temperature porous medium numerical model, a companion semi-analytical expression for the thermal efficiency of a cubical foam block attached on-center to a circular tube is also developed. Heat rates predicted with the semi-analytical model are verified through comparison with experimentally measured heat transfer rates using open-cell metal foam. Foam thermal resistances are also quantified over a range of operating conditions. The recommended ranges of application of the analytical and experimentally verified semi-analytical expressions for the thermal efficiency of both annular and square-shaped foams are also presented.