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 nanosalt/copper foam composite was used.
Keywords solar salt, aluminium oxide nanopowder, copper foam, latent thermal energy storage