Thermal characterization of a stratifying molten salts storage tank with integrated steam generator in real operating conditions

In the last years, ENEA proposed a new concept of thermocline thermal energy storage system based on a single storage tank containing a binary mixture of molten salts (working both as heat storage medium and heat transfer fluid in the solar field), and a once-through steam generator integrated in it. This component works like a steam generator of a fast nuclear reactor, exploiting the temperature difference of the mixture of salts stratified in the tank between a hot layer (550°C) and a cold one (290°C) to produce superheated steam. In the present paper, are shown the experimental tests carried out to characterize and to assess the performance of the temperature stratification of the molten salts in such a system. The tests have been carried out with the storage tank of the PCS Facility, at Casaccia Research Centre of ENEA (Rome, Italy), and a 300kWth shell-and-tube once-through steam generator integrated in it. The experimental activities verified that the thermal stratification conditions of the molten salts contained in the storage tank are stable over time, and the integrated once-through steam generator is the active element that triggers and maintains over time the stratification of the molten salts. © 2018 Author(s).