Molten Salts as High Temperature Fluids Carrier for Concentrated Solar Power Exploitation

This work presents the results of an experimental activity carried out to test the potentiality of Molten Salts (MS) to work as thermal carriers of an innovative parabolic dish collector (PDC) solar plant configuration. The developed prototype device allows a flexible exploitation of the thermal power available at the focus of the PDC. This has been achieved by the adoption of dedicated plant components suitable designed to support the high temperatures achieved by the adopted eutectic MS mixture made of NaNO3, NaNO2 and KNO3. The adopted technical solutions enhance the potentialities of MS to work both as High Temperature Fluids (HTF) carrier and Thermal Energy Storage (TES) by using two 50-liter tanks able to store 10 kWh of thermal energy. High temperatures, above 400°C at steady state conditions and up to 540 °C for transient conditions, have been achieved by selecting different MS flow rates covering the range from 0.19 to 0.48 l/min. The efficiency of the heat transfer process has been measured by monitoring in continuous the MS temperature at the inlet-outlet section of the receiver jointly with the availability of the solar radiation measurements obtained at the receiver. For the investigated tests this parameter ranges from 0.58 to 0.77. The obtained results confirm the feasibility of the proposed plant solution and look promising to encourage the use of different MS mixtures and other advanced fluids to exploit the potentialities of innovative solar plants configurations.