Molecular dynamics simulation of thermophysical properties of NaCl-KCl phase change materials applied to concentrating solar power

Given the current research prospects for the next generation of Concentrated Solar Power (CSP) plants based on the Supercritical carbon dioxide Brayton cycle, NaCl-KCl binary molten salt is a kind of material with application value. In this paper, NaCl-KCl with a Na+ molar concentration of 30–60 was studied based on Molecular Dynamics (MD) method. The thermophysical properties such as latent heat, specific heat and thermal conductivity were simulated and analyzed in molten state. The unit price of energy storage was calculated and discussed. The results showed that when the Na+ content was 36%, the latent heat was the highest with the value of 363.60 J/g. The specific heat capacity and thermal conductivity increased as Na+ molar concentration increased. The unit price of energy storage was the lowest when Na+ content was 60% with the value of 0.043 ¥/kJ. It can be a reference to choose materials for thermal energy storage (TES) system in CSP. •The NaCl-KCl molecular model is constructed using the LAMMPS method.•The highest latent heat is 363.60 J/g while Na+ is 36 mol%.•The physical parameters of the molten state are quantitatively given.•The highest thermal conductivity is 0.52 W/m·K with Na+ of 60 mol% at 1000 K.•Unit heat storage cost is only 0.043 ¥/kJ with Na+ of 60 mol%.