Thermophysical Characterization and Molecular Dynamics Simulation of Low Melting Nitrate Molten Salts for Concentrating Solar Power

Their thermophysical properties were systematically tested, and the microstructure-property relationship was analyzed by molecular dynamics simulation under NPT ensemble.

Results showed NKC had a melting point of 119.54℃ and decomposition temperature of 534.66℃, while LNKC-1 was 117.32℃ and 579.94℃, with a broader operating temperature range. Their average specific heat capacities were 1.035 and 1.041 J·g-1·℃-1 at 150~450℃, with viscosities of 1.8 and 2.3 mPa·s at 500℃, and the sharp rise in viscosity below 200℃ was the main performance shortcoming. Simulations confirmed the molten salts had a short-range ordered and long-range disordered structure, metal cations coordinated with O in NO₃⁻, and the anion-cation interaction strength followed Ca2+>Li+>Na+>K+, with the evolution of microstructure highly consistent with the change of macroscopic thermophysical properties.