Thermostatic properties of nitrate molten salts and their solar and eutectic mixtures

Nitrate molten salts are extensively used for sensible heat storage in Concentrated Solar Power (CSP)plants and thermal energy storage (TES) systems. They are the most promising materials for latent heatstorage applications. By combining classical molecular dynamics and differential scanning calorimetryexperiments, we present a systematic study of all thermostatic, high temperature properties of pureKNO3 and NaNO3 salts and their eutectic and ”solar salt” mixtures, technologically relevant. We firststudy, in solid and liquid regimes, their mass densities, enthalpies, thermal expansion coefficients andisothermal compressibilities. We then analyze the cP and cV specific heats of the pure salts and ofthe liquid phase of the mixtures. Our theoretical results allow to resolve a long-standing experimentaluncertainty about the cP(T) thermal behaviour of these systems. In particular, they revisit empirical lawson the cP(T) behaviour, extensively used at industrial level in the design of TES components employingthe ”solar salt” as main storage material. Our findings, numerically precise and internally consistent, canbe used as a reference for the development of innovative nanomaterials based on nitrate molten salts,crucial in technologies as CSP, waste heat recovery, and advanced adiabatic compressed air energystorage.