Enhanced thermal transport at metal/molten salt interface in nanoconfinement: A molecular dynamics study

Abstract

• Strong enhancement of heat transfer at molten salt-metal interface. • Ions form highly ordered and correlated structures at metal surface. • Enrichment of ions at the interface contributes to enhanced transfer. The molten chloride salts are excellent heat storage materials and heat transfer fluids in concentrating solar power (CSP) systems. The properties of the interface between the molten chloride and metal have great significance for practical applications in CSP such as heat transfer enhancement as well as corrosion prevention. This study combines equilibrium and non-equilibrium molecular dynamics simulations to explore the thermal transport and structural properties at the interface between molten sodium chloride and iron. Simulation results indicate that there is a strong enhancement of heat transfer at the metal-salt interface and such enhancement increases dramatically as the size of confinement increases. Such enhancement of heat transfer can be ascribed to the strong adsorption of molten salt ions on the iron surface via van der Waals interactions. The adsorbed ions at the solid-liquid interface formed highly ordered structures with strong correlations between ions, and such ordered structure also leads to slow down of mass transfer. Further investigation indicates that increasing the metal-salt interactions strength also can enhance the heat transfer rate. These finding have illustrated the enrichment of molten salt at the salt-metal interfaces is ubiquitous, which can be further utilized for enhancement of heat transfer performances in concentrating solar power.