Analysis of a procedure for direct charging and melting of solar salts in a 14 MWh thermal energy storage tank

The use of molten salts as Heat Transfer Fluid (HTF) and storage medium in Concentrating Solar Power (CSP) plants and in particular for Parabolic Trough (PT) systems is an appealing approach for cost reduction, efficiency increase and process integration. Aim of this paper is the description and analysis of the charging and melting procedures facilitated initially by electrical heaters integrated in the storage tank, to optimize the design and commissioning procedures of plants adopting this kind of technology. A Thermal Energy Storage (TES) system has been installed in the MATS plant (Multipurpose Applications by Thermodynamic Solar), designed to store about 14 MWh of thermal energy up to 550°C, adopting the thermocline technology and integrated with steam generator inside the tank. Furthermore, these procedures permit to assess the thermal losses together with the melting and warming dynamics associated with the latent heat and thermal capacities on relevant (near-commercial) plant scale.