Characterization of calcium chloride tetrahydrate as a phase change material and thermodynamic analysis of the results

To study the feasibility of calcium chloride tetrahydrate as a phase-change material, we determined its melting point and heat of fusion using differential scanning calorimetry (DSC) in the temperature range of 0 degrees C-60 degrees C. We also determined the density and viscosity of molten calcium chloride tetrahydrate in the temperature range of 40 degrees C-65 degrees C and studied the effect of adding small quantities of LiCl, NaCl and KCl (1 mass %) on the resulting thermal and physical properties. Based on the determination of the thermophysical properties, the energy storage density was evaluated for the different systems. The CaCl2 center dot 4H(2)O + 1 mass % of LiCl exhibited higher values (174 J/cm(3)) than pure CaCl2 center dot 4H(2)O (156 J/cm(3)), and the CaCl2 center dot 4H(2)O + 1 mass % of NaCl (151 J/cm(3)). Some of the results were interpreted using thermodynamic models and functions, indicating that the addition of alkaline chlorides contributes to releasing water molecules from the hydration layer of Ca+2 ions, which appears to have a determining effect on the behavior of molten CaCl2 center dot 4H(2)O. (C) 2016 Elsevier Ltd. All rights reserved.