An ab initio molecular dynamics investigation of the thermophysical properties of molten NaCl-MgCl[formula omitted

Abstract

Molten salts have many applications in the nuclear and solar energy industries for thermal storage and heat transfer applications. However, there is a knowledge gap in molten salt thermophysical properties which hinders the technical readiness level of molten salt applications, especially in the nuclear industry. A common method of investigating new materials is through ab initio Molecular Dynamics (AIMD) simulations which is an effective tool to investigate structural and thermophysical properties at realistic temperatures. NaCl-MgCl2 is an inexpensive salt that is a good candidate for use as a heat transfer medium in solar power applications or in the secondary loop of a nuclear reactor. In this article, the thermophysical properties of NaCl-MgCl2 are computed via AIMD calculations to supplement the limited experimental studies in the literature. A wide range of compositions and temperatures for the pseudo-binary NaCl-MgCl2 were used to calculate the density, heat capacity, compressibility, enthalpy of mixing, and volumetric thermal expansion coefficient. AIMD is shown to accurately model the densities of molten NaCl-MgCl2 as there is good agreement with the available literature. This work observed a transition to a monotonic increase of the density with respect to MgCl2 composition occurring above 1100 K. The heat capacity values increase uniformly with respect to concentration of MgCl2 at a rate of 2.85 J/mol-K per 10 mol% of MgCl2. Select thermophysical properties are fit to a Redlich-Kister expansion for utilization in multiphysics simulations.