Transient solid/liquid phase change occurring in metal foams impregnated with phase change material (PCM) is investigated. Natural convection in the melt is considered. Volume-averaged mass and momentum equations are employed, with the Brinkman-Forchheimer extension to the Darcy law to model the porous resistance. Owing to the difference in the thermal diffusivities between the metal foam and the PCM, local thermal equilibrium between the two is not assured. Assuming equilibrium melting at the pore scale, separate volume-averaged energy equations are written for the solid metal foam and the PCM, and are closed using an interstitial heat transfer coefficient. The enthalpy method is employed to account for phase change. The governing equations are solved implicitly using a finite volume method on a fixed grid. The influence of Rayleigh number, Stefan number, and interstitial Nusselt number on the temporal evolution of the melt front location, temperature differentials between the solid and fluid, and the melting rate is documented and discussed. The merits of incorporating metal foam for improving effective thermal conductivity of thermal storage systems are discussed.

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