Abstract
In this work, the results of a numerical code based on the porous media Local Thermal Non-Equilibrium (LTNE) and the apparent heat capacity methods, are compared with experiments aiming at a preliminary validation. The test cell consists in a 50 mm aluminum foam cube filled with a paraffin wax, heated and cooled on the same face. The heat flux is measured by two miniaturized sensors, while the temperature is measured in three different locations along the cube edge. Finally, one side is equipped with a Zinc Selenide window which is transparent to the long wave InfraRed. This system allows to track the paraffin melting front evolution together with the temporal trend of the whole temperature distribution simplifying the comparison with the numerical outputs at different time steps.The numerical model is then set with the same boundary conditions (heat flux) to predict the experimental temperature fields, considering both conduction in the solid domain and natural convection in the liquid domain. The preliminary validation shows that the numerical results match the experimental data with good agreement. Results are also presented for different gravity levels. This study can be a starting point for all those applications where gravity has a major role.
Highlights
Thermal energy storage systems are very important to achieve large amounts of heat, especially for renewable energies, in which the font availability might be an issue [1,2,3]
The results of a numerical code based on the porous media Local Thermal Non-Equilibrium (LTNE) and the apparent heat capacity methods, are compared with experiments aiming at a preliminary validation
Metallic foams based on highly conductive materials like aluminum or copper are promising since they consist into a sponge-like material that is filled with the phase change material, so that the overall thermal conductivity and melting times are respectively increased and reduced
Summary
Thermal energy storage systems are very important to achieve large amounts of heat, especially for renewable energies, in which the font availability might be an issue [1,2,3]. Latent storage systems are promising since they can store large amounts of heat with low temperature differences. Among various latent storage systems, Phase Change Materials (PCMs) seem to be one of the most promising in terms of efficiency and cost ratio. Depending on the desired application, the PCMs can be chosen based on melting/solidification temperatures. Despite their capability to store large amounts of heat, they present a low thermal conductivity that needs to be enhanced to melt the whole volume in reasonable times. Metallic foams based on highly conductive materials like aluminum or copper are promising since they consist into a sponge-like material that is filled with the phase change material, so that the overall thermal conductivity and melting times are respectively increased and reduced. Wang et al [5] showed that the equivalent thermal conductivity of a paraffin/copper foam can be 50 times the paraffin thermal conductivity
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