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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Experimental and Numerical Investigations of Phase Change Heat Transfer Characteristics in Open-Cell Metal Foam Infiltrated with Eutectic Salt for Solar Energy Storage

Get access (open in a dialog) DOI: 10.1615/IHTC15.tst.008518
pages 9103-9116

Résumé

Eutectic salt as a phase change material (PCM) can be a potential media for solar energy storage application. The extensive utilization is however hampered by its poor thermal conductivity. In the present study, HITEC salt (40 wt% NaNO2, 7 wt% NaNO3, 53 wt% KNO3) was applied as the pure PCM, and copper foam with the porosity around 97% were used to improve the thermal conductivity. Heat storage and retrieval tests in a latent thermal energy storage (LTES) unit were conducted extensively both for pure salt and salt/copper foam composite. The wall and inner temperature distributions inside the LTES unit were measured. Temperature evolutions showed that both the melting and freezing processes were enhanced by the copper foam with high thermal conductivity. Natural convection played a crucial role in the heat transfer during heat storage process, and the existence of foam skeleton weakened the local natural convection to some extent, whereas heat conduction dominated the heat retrieval process. Therefore, the time-duration of the LTES unit with composite PCM during heat retrieval process was reduced more than that during heat storage process. A three-dimensional model considering the non-Darcy effect, local natural convection, and thermal nonequilibrium was adopted to further interpret the heat transfer characteristics inside the LTES unit. The velocity, temperature field, and evolutions of the solid-liquid interface positions at various times were obtained. The numerical predictions are in reasonable agreement with the experiment results.