Abstract
The melting heat transfer of CuO-coconut oil embedded in a non-uniform copper metal foam-was addressed. Copper foam is placed in a channel-shaped Thermal Energy Storage (TES) unit heated from one side. The foam is non-uniform with a linear porosity gradient in a direction perpendicular to the heated surface. The finite element method was applied to simulate natural convection flow and phase change heat transfer in the TES unit. The results showed that the porosity gradient could significantly boost the melting rate and stored energy rate in the TES unit. The best non-uniform porosity corresponds to a case in which the maximum porosity is next to a heated surface. The variation of the unit placement's inclination angle is only important in the final stage of charging, where there is a dominant natural convection flow. The variation of porous pore size induces minimal impact on the phase change rate, except in the case of a large pore size of 30 pore density (PPI). The presence of nanoparticles could increase or decrease the charging time. However, using a 4% volume fraction of nanoparticles could mainly reduce the charging time.