Experimental investigation of an innovative thermochemical process operating with a hydrate salt and moist air for thermal storage of solar energy: Global performance

• A large scale thermochemical storage system working with moist air is experimented.
• High energy density (203 kW h/m3) and storage capacity (105 kW h) have been obtained.
• Hydration specific powers between 0.75 and 2 W/kg have been reached.
• The ways to control the storage system have been deeply investigated.
• Two important parameters (equilibrium drop and mass flowrate) have been identified.

This paper investigates an innovative open thermochemical system dedicated to high density and long term (seasonal) storage purposes. It involves a hydrate/water reactive pair and operates with moist air. This work focuses on the design of and experimentation with a large scale prototype using SrBr2/H2O as a reactive pair (400 kg of hydrated salt, 105 kW h of storage capacity and a reactor energy density of 203 kW h/m3). Promising conclusions have been obtained regarding the feasibility and performance of such a storage process. Hydration specific powers from 0.75 to 2 W/kg have been reached for a bed salt energy density of 388 kW h/m3. Moreover, two important parameters that control the storage system have been identified and investigated: the equilibrium drop and the mass flow rate of moist air. Both have a strong influence on the reaction kinetics and therefore on the reactor’s thermal power.