Molecular dynamics simulations on the structure and thermal property of SiO2/(LiCl-KCl) nanofluids for high temperature thermal energy storage

Abstract

Chloride salt is the most suitable heat transfer and storage medium for the next generation concentrated solar power generation, but its low thermal properties limit its large-scale application. Doping nanoparticles to form nanofluids is an important way to enhance the thermal properties of chloride salt. In this paper, molecular dynamics method is used to investigate the thermal properties of SiO₂/(LiCl-KCl) nanofluids such as density, viscosity and thermal conductivity. Furthermore, the underlying strengthening mechanisms of nanoparticles on thermal properties of molten salt are also explored from the perspective of microstructure, energy and compress interface layers. The results show that the doped SiO₂ nanoparticles enhance the density, viscosity and thermal conductivity of molten salt. When the doping amount of SiO₂ nanoparticles is 6 wt%, the density, viscosity and thermal conductivity increase by an average of 1.22 %, 17.21 % and 6.30 %, respectively. The doped nanoparticles enhance the association between anions and cations, increase the collision frequency between ions and build a channel for heat transfer between nanoparticles and base salt ions, but weaken the diffusion ability of molten salt.