Effect of Synthesis Protocol in Enhancing Heat Capacity of Molten Salt Nanofluids

Abstract

Concentrated solar power (CSP) incorporated with thermal energy storage (TES) is an appealing solar energy generation technology. TES stores heat during the daytime and releases it in the nighttime. As a result, CSP can produce continuously even at night. Storing heat by TES makes CSP a unique technology among various renewable energy sources which often suffer from the intermittency of energy supply (e.g., wind turbines without wind, photovoltaics at night, etc.). The energy conversion efficiency of CSP is directly related to the properties of the TES medium. Binary or ternary mixtures of molten salts (Solar Salt) are commonly used as the TES in CSP due to its high-temperature stability. Enhancing the thermophysical properties of the molten salt medium can significantly improve TES performance. Various studies have reported the anomalous specific heat enhancement of molten salt-based nanofluids. However, the underlying mechanism for this enhancement was yet discovered. In this study, the effect of different synthesis conditions on the resultant specific heat capacity of molten salt-based nanofluids was investigated. Several molten salt nanofluids (NaNO3–KNO3 with SiO nanoparticles at 1 wt. % concentration) were prepared at different thermal cycling conditions and their thermal performance was characterized by a differential scanning calorimeter (DSC).