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

Author:
Ushak, Svetlana, Suárez, Miriam, Véliz, Sussy, Fernández, Angel G., Flores, Elsa, Galleguillos, Héctor R.
Source:
Renewable energy 2016 v.95 pp. 213-224
ISSN:
0960-1481
Subject:
calcium, calcium chloride, differential scanning calorimetry, energy, heat, ions, lithium chloride, melting point, phase transition, potassium chloride, renewable energy sources, sodium chloride, temperature, thermodynamic models, viscosity
Abstract:
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 °C-60 °C. We also determined the density and viscosity of molten calcium chloride tetrahydrate in the temperature range of 40 °C-65 °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 CaCl2·4H2O + 1 mass % of LiCl exhibited higher values (174 J/cm³) than pure CaCl2·4H2O (156 J/cm³), and the CaCl2·4H2O + 1 mass % of NaCl (151 J/cm³).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 CaCl2·4H2O.
Agid:
6080089