Enhanced sensible heat capacity of molten salt and conventional heat transfer fluid based nanofluid for solar thermal energy storage application

In concentrating solar power (CSP) systems, the thermo-physical properties of the heat transfer fluid (HTF) are key parameters for enhancing the overall system efficiencies. Molten salts, such as alkali nitrates, chlorides or carbonates, and their eutectics, are considered as alternatives to conventional HTF (such as water or oil) to extend the operational capabilities of CSPS. However, the usage of the molten salt as the HTF is limited, since the heat capacity of the molten salt is relatively lower than that of conventional HTF. Nanofluid is a mixture of a fluid and nanoparticles. Well dispersed nanoparticles can be used to enhance the thermo-physical properties of HTF. In this study, silicon dioxide nanoparticles were dispersed into a molten salt and into a conventional HTF (Therminol VP-1, Solutia Inc). The specific heat enhancement of each nanofluid was studied and the applicability of such nanofluid materials for solar thermal storage applications was explored.