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.
Stark, J. R., Prasad, R., & Bergman, T. L. (2017). Experimentally validated analytical expressions for the thermal efficiencies and thermal resistances of porous metal foam-fins. International Journal of Heat and Mass Transfer, 111, 1286–1295. https://doi.org/10.1016/j.ijheatmasstransfer.2017.03.041