Computational modelling of the local structure and thermophysical properties of ternary MgCl2-NaCl-KCl salt for thermal energy storage applications

Abstract

Molten salts as heat transfer fluids (HTF) for concentrated solar power (CSP) plant application are considered as the best thermal storage medium, and more precisely molten chlorides, presenting a wide operating range and coupled with competitive cost. Furthermore, MgCl2-NaCl-KCl (MgNaK) mixture appeared as the most promising one but need further studies to better understand its thermophysical properties. Indeed, its hydrated form leads to the formation of corrosive compounds. In this research, two different methods are used to model the ternary mixture. The dehydration process is evaluated by thermodynamical calculations with Thermocalc software. Then, the local structure, thermal conductivity and viscosity are estimated by means of molecular dynamics simulation, with LAMMPS package. The results were close to past simulations studies and experimental references, but discrepancies need to be further minimized regarding some variable fluctuations.