Effective thermal conductivity of open-cell metal foams' impregnated with pure paraffin for latent heat storage

The thermal conductivity of phase change material (PCM) significantly affects the thermal performance of latent heat thermal energy storage (LHTES) system, which is attractive for energy conservation and waste heat utilization. Metal foam can be applied to enhance the low thermal conductivity of pure PCM. In the present study, copper foam and nickel foam with various porosities and pore sizes were impregnated with pure paraffin with vacuum assistance. A steady-state test system which considered the thermal contact resistance (TCR) between the specimen and adjacent surfaces was constructed to measure the effective thermal conductivities of the composite PCMs. The thermal conductivities were also theoretically calculated based on the correlations and models from the literature. The results showed that the thermal conductivities measured with steady-state method showed good agreement with the theoretical predictions, and the thermal conductivities of the composite PCMs were drastically enhanced, e.g., the thermal conductivities of the paraffin/copper foam composite PCMs fabricated by the copper foams with the porosities of 96.95%, 92.31%, 88.89% and pore size of 25 PPI were about thirteen, thirty-one, forty-four times larger than that of pure paraffin, respectively. The ratios of TCR to the total thermal resistances of the composite PCMs with the thickness of about 20.0 mm were in the ranges of 15.0-50.0%. (C) 2014 Elsevier Masson SAS. All rights reserved.