Natural convection in composite systems with phase change materials

In this study, we carried out a numerical simulation of transient heat transfer in a composite passive system consisting of air–phase change material–air, arranged as a rectangular enclosure. The vertical boundaries of the enclosure are isothermal and the horizontal ones adiabatic. The enthalpy formulation with a fixed grid is used to study the process of phase change with liquid–solid interface zone controlled by natural convection. The flow in this zone is simulated by a model based on the Darcy porous medium. The numerical solution of the mathematical model is done using finite difference–control volume algorithm. The influence of the geometrical and thermal parameters is studied. It is found that subcooling coefficient is the most important parameter influencing heat transfer, and for a given subcooling, there is an optimum phase change partition thickness.