Eutectic composition of selected phase change materials for thermal energy storage applications

Abstract

Latent heat storage in salt mixture has drawn so much attention because of the salt mixture’s capability of storing large quantity of heat when compared to single salt thereby, making it more feasible for use as phase change material. However it is worthwhile to find out among various combination of salts forming eutectic mixtures, the one that has the best energy storage capability by evaluating and comparing their melting points and latent heat storage. So in this research work, four different types of eutectic mixture of salts were prepared and experimentally investigated for the best thermal energy storage capability. The first eutectic mixture consists of 2.6g of LiNO3, 6.4g of NH4NO3 and 1g of NaNO3. The second eutectic mixture consists of1.75g of LiNO3, 3.9g of NH4NO3 and 1.1g of KNO3. The third one consists of 5.2g of LiNO3, 13.7g of NH4NO3 and 1g of NH4Cl) and the fourth one consists of 1.77g of LiNO3, 2.94g of NH4NO3, 1g of NaNO3 and 1g of NaCl. The latent heat and the melting point of the respective salt and their eutectic mixture were determined using digital differential scanning Apparatus. The results obtained showed that the melting points and latent heats of the first, second, third and fourth eutectic mixture were 79.50C and 112kJ/kg, 80.50C and 114kJ/kg, 81.40C and 109kJ/kg, 84.40C and 119kJ/kg respectively. In view of this, the eutectic mixture of 1.77g of LiNO3, 2.94g of NH4NO3, 1g of NaNO3 and 1g of NaCl with melting point of 84.40C and latent heat of 119KJ/Kg was found to possess the best thermal energy storage capability compared to others..Keywords—Eutectic mixture, Salts, Phase change materials (PCM), Latent heat storage