Theoretical estimation of temperature-dependent radiation properties of molten solar salt using molecular dynamics and first principles

The use of solar salt is important in modern solar energy utilization technology, i.e. concentrating solar power. However, there are few high-temperature-dependent radiation property data that can be used to accurately determine the temperature field, which hinders its further application. Thus, a theoretical approach using a combination of molecular dynamics and first principle methods is adopted to predict the radiation properties of molten solar salt from 525 to 875 K, which covers its working temperature range. According to the theoretical computation results, the main absorption region is observed when the wavelength is less than 500 nm. There are two absorption peaks located at approximately 130 and 250 nm, and there are also two refractive index peaks located at approximately 160 and 400 nm, which are slightly different from the absorption peaks. Moreover, increasing the working temperature subtly decreases the refractive index and extinction coefficient simultaneously. In addition, by investigating the effects of the simulation size, we found a 195-atoms system that satisfies the requirements for computations of related thermodynamic quantities. We believe that the results of this study show the significance of solar salt in the future applications.