Assessment of the Effects of Copper Oxide Nanoparticles Addition to Solar Salt: Implications for Thermal Energy Storage

The incorporation of conductive nanoparticles into thermal energy storage media is one of the strategies to increase their thermal conductivity. This work unravels the impact of the addition of CuO nanoparticles on the thermal properties of solar salt, a high-temperature thermal energy storage material. The resultant CuO enhanced solar salt (CuOeSS) exhibited a maximum thermal conductivity improvement of 14.4 % at 40 degrees C when the concentration of CuO nanoparticles was 1 wt%. The prevalence of CuO nanoparticles as isolated aggregates resulted in a moderate thermal conductivity enhancement. The CuO nanoparticles greatly influenced alpha-KNO3 to beta-KNO3 transition and reduced the expected positive influence on thermal conductivity at temperatures above 120 degrees C. The solid-phase specific heat was enhanced by 22.7 % for 2 wt% CuOeSS. Our results demonstrate the interplay between the different roles played by CuO nanoparticles, namely the thermal conductivity enhancement at lower temperatures and influencing the alpha-KNO3 to beta-KNO3 transition at higher temperatures. The CuOeSS with 0.5 wt% CuO, which showed enhancement in both thermal conductivity and energy storage capacity, is a suitable energy storage material for applications in the temperature range of 100-245 degrees C.

Automated summary

This study investigates the impact of adding CuO nanoparticles on the thermal properties of solar salt, revealing that the addition of CuO nanoparticles can enhance the thermal conductivity of solar salt at certain concentrations but can also influence the α-KNO3 to β-KNO3 transition at higher temperatures.