Abstract

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 heat
storage applications. By combining classical molecular dynamics and differential scanning calorimetry
experiments, we present a systematic study of all thermostatic, high temperature properties of pure
KNO3 and NaNO3 salts and their eutectic and ”solar salt” mixtures, technologically relevant. We first
study, in solid and liquid regimes, their mass densities, enthalpies, thermal expansion coefficients and
isothermal compressibilities. We then analyze the cP and cV specific heats of the pure salts and of
the liquid phase of the mixtures. Our theoretical results allow to resolve a long-standing experimental
uncertainty about the cP(T) thermal behaviour of these systems. In particular, they revisit empirical laws
on the cP(T) behaviour, extensively used at industrial level in the design of TES components employing
the ”solar salt” as main storage material. Our findings, numerically precise and internally consistent, can
be 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 energy
storage.