Preparation and characterization of nanofluids based on molten salts with enhanced thermophysical properties for thermal energy storage at concentrate solar power

Abstract

In the recent years considerable interest of scientific and industrial communities in molten salts based nanofluids is evident. Such interest is motivated by the possibility of enhancement of thermophysical properties of molten salts by means of adding small concentrations of nanoparticles. This enhancement is particularly attractive for thermal energy storage systems at concentrated solar power plants, where molten salts are often used as a storage media as well as heat transfer fluid. Despite the high number of works reporting the effect of nanoparticles on thermophysical properties of molten salts, not only does the mechanism behind the observed enhancement remain mysterious, but the reported values are often contradicting. In this work we attempt to provide some guidelines for the preparation and characterization of nanofluids based on molten salts in order to avoid misleading interpretations regarding their thermophysical properties. We particularly focus on the importance of the preparation method and the stability of molten salt based nanofluids. We also discuss the formation of dendritic structures in molten salt doped with nanoparticles, which has been often related to thermophysical properties enhancement.