Volumetric Convective Heat Transfer Coefficient Model for Metal Foams

Abstract

ABSTRACTThis study investigates the heat transfer in metal foams assuming that all the foam cells are cubic. An improved model for the volumetric convective heat transfer coefficient of metal foam was obtained by considering the convective heat transfer and the thermal conduction in the connected foam ligaments. Numerical simulations of a metal foam-filled channel were performed using the local thermal non-equilibrium model to evaluate the model. The theoretical and experimental data agree better with the present model than with other models. The velocity gradient near the metal foam-filled channel wall is greater than in an empty channel, with the wall boundary layer becoming thinner. The temperature differences between the fluid and solid phases are predicted by the model with the pore density affecting the volumetric convective heat transfer coefficient more than the porosity. The volumetric convective heat transfer coefficient significantly increases as the pore density increases. However, the relationship between the volumetric convective heat transfer coefficient and the porosity is not linear. As the porosity increases, the volumetric convective heat transfer coefficient first increases and then decreases. The effect of the solid thermal conductivity on the volumetric convective heat transfer coefficient has an upper limit with a critical value of the solid thermal conductivity for the present conditions.