Heat transfer enhancement of nano-encapsulated phase change material (NEPCM) using metal foam for thermal energy storage

This study provides a new shape-stabilized phase change material (PCM) composite for enhanced thermal energy storage with nano-encapsulated phase change material (NEPCM) embedded in copper metal foam since it combines the characteristics of high latent heat of core PCM(octadecane), shape stable from encapsulation (polystyrene) and high thermal conductivity and high area/volume ratio of copper metal foam. We experimentally investigate phase change heat transfer of Foam/NEPCM composite with the consideration of foam porosity effect and foam/NEPCM thermal non-equilibrium heat transfer. Compared with pure NEPCM, foam/NEPCM composite provides maximum wall temperature reduction of 47 °C and more uniform internal temperature due to thermal enhancement of metal foam and latent heat absorption of NEPCM. The molten PCM convection is fully constrained in NEPCM shell, which makes heat conduction the solitary heat transfer mechanism in foam/NEPCM composite during phase change. Attributed to its higher thermal conductivity and area/volume ratio, the lower porosity foam/NEPCM composite obtains lower heated wall temperature and internal temperature near the heated wall than the higher porosity composite does. Moreover, the thermal non-equilibrium is more obvious at the location near the heated wall inside foam/NEPCM composite than that farther away.