A DFT based equilibrium study of a chemical mixture Tachyhydrite and their lower hydrates for long term heat storage

7th European Thermal-Sciences Conference

Pathak, A.D.^1 ; Nedea, S.V.^1 ; Zondag, H.A.^1 ; Rindt, C.C.M.^1 ; Smeulders, D.M.J.^1

Energy Technology, Eindhoven University of Technology, Netherlands^1

关键词: Different operating conditions;    Entropic contributions;    Ground-state energies;    Harmonic frequency;    Optimum operating conditions;    Product concentration;    Seasonal heat storages;    Temperature and pressures;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/745/3/032003/pdf
DOI  :  10.1088/1742-6596/745/3/032003

来源: IOP

【 摘 要 】

Chloride based salt hydrates are promising materials for seasonal heat storage. However, hydrolysis, a side reaction, deteriorates, their cycle stability. To improve the kinetics and durability, we have investigated the optimum operating conditions of a chemical mixture of CaCl2and MgCl2hydrates. In this study, we apply a GGA-DFT to gain insight into the various hydrates of CaMg2Cl6. We have obtained the structural properties, atomic charges and vibrational frequencies of CaMg2Cl6hydrates. The entropic contribution and the enthalpy change are quantified from ground state energy and harmonic frequencies. Subsequently, the change in the Gibbs free energy of thermolysis was obtained under a wide range of temperature and pressure. The equilibrium product concentration of thermolysis can be used to design the seasonal heat storage system under different operating conditions.