EXPERIMENTAL STUDY OF A LATENT HEAT THERMAL ENERGY STORAGE UNIT ENCAPSULATED WITH MOLTEN SALT/COPPER FOAM COMPOSITE SEEDED WITH NANOPARTICLES

Solar energy storage has vast applications in a wide range, and nanoparticles and metal foam can be used to improve energy storage density and heat transfer rate in a storage system. In this study, solar salt, nano-salt (solar salt seeded with 2 wt. % aluminium oxide (Al₂O₃) nanopowder) and nano-salt/copper foam composite were used as storage media, and the thermal performances during heat storage/retrieval processes were investigated with a pilot experimental rig. The temperature distributions of the PCMs at radial, theta, and axial locations were measured. The results show that Al₂O₃ nanopowder can slightly improve the heat transfer of the nano-salt, while the system encapsulated with the nano-salt/copper foam composite can be significantly enhanced, e.g. the time-duration of the charging process can be reduced by about 74.5%, compared to that of pure salt. Theoretical analysis also revealed the heat transfer domination by temperature distribution. The heat storage power can reach 200.27 kW/m³ when nano-salt/copper foam composite was used.