Solar Salt Doped with Nano Additive Expanded Graphite as a Promising Phase Change Material for Thermal Energy Storage Systems

In solar thermal power generation plants, solar salt (a combination of KNO3 and NaNO3) is utilized as a thermal storage medium, thanks to its optimal phase change temperature, high heat storage density, and cost-effectiveness. The applications of few organic and inorganic storage materials are found to be limited, due to its low thermal conductivity during heat absorption and release process. Expanded graphite (EG) can be used as an additive to compensate for the solar salt's low thermal conductivity. The ultrasonic smashing method was used to prepare the binary nitrate in the weight ratio of 6:4 for NaNO3:KNO3. In this study, EG with weight percentage of 3%, 5%, 7%, and 9% were used to improve the thermal conductivity of solar salt. Thermal behaviors of the prepared sample were investigated with the help of differential scanning calorimeter (DSC). Scanning electron microscope (SEM) with EDX and X-ray diffraction (XRD) were utilized to characterize the morphology and chemical composition of pure EG, nitrate/EG composite phase change materials (PCM's) and binary nitrates. FT-IR spectroscopy is used to confirm the composite formation. In order to determine the thermal conductivity hot disk method was used. The binary nitrates/EG composite materials have been discovered to promise the reliable PCM for high temperature solar energy storage applications. (c) 2025 Jordan Journal of Mechanical and Industrial Engineering. All rights reserved