Investigation on ettringite as a low-cost high-density thermochemical heat storage material: Thermodynamics and kinetics

Ettringite-based thermochemical energy storage has been recommended to be used in buildings for thermal supply because of its low material cost (<1000 €/m3), working temperature and high capacity. However, several physicochemical properties ettringite were still not clear, such as reversible reaction enthalpies, thermodynamic equilibrium, kinetics the dehydration/hydration reactions. In this study, dehydration was experimentally confirmed stepwise TGA-DSC, Ett30.6 ? Ett30 Met 17.8 Met11.7 Met7.5, which is consistent with inference according crystal structure. The equilibrium reactions presented impact water activity on stability at controlled temperatures vapor partial pressures. modeling based experiment results extrapolated model from literature. rehydration enthalpy about 1370 kJ/mol, equals an density 547 kWh/m3 under operating conditions 20 °C 90% RH.