Study of thermophysical properties of chloride salts doped with CuO nanoparticles for solar thermal energy storage

As heat storage and heat transfer medium, molten salt plays a vital role in achieving high heat transfer efficiency in concentrating solar power (CSP) plants. In this study, ternary chloride salts (NaCl–KCl–MgCl2) is considered as the base salt and the nanocomposites doped with different mass fractions of CuO are synthesized using the solution evaporation method. The thermophysical properties of the nanocomposites, including melting temperature, phase change enthalpy, specific heat, thermal diffusivity, and thermal conductivity are investigated. The experimental results indicated the melting temperature of the nanocomposites is very close to that of the base salt. The specific heat of the nanocomposite in the liquid phase region is 10.51% higher than that of the base salt when the mass fraction of CuO was 0.7%. The addition of CuO nanoparticles significantly increase the thermal diffusivity and thermal conductivity of the base salt. The thermal diffusivity and thermal conductivity of the nanocomposites are increased by 10.95–37.23% and 15.85–39.55% compared to the base salt, respectively. The nanocomposites doped with CuO nanoparticles exhibit good application prospects and excellent thermal energy storage performance for high-temperature CSP systems.