Thermo-hydraulic characteristics of molten salt NaNO3-KNO3 using numerical simulations

Nowadays most of research in nuclear engineering is on safety of nuclear reactor. Passive cooling attracts most of researchers to use low melting point and high boiling point fluid. Molten salts exhibit low melting and high boiling points at normal atmospheric pressure condition. These qualities make molten salts useful in a variety of applications as a coolant or heat transfer fluid. In this study, Three-dimensional (3D) Computational Fluid Dynamics (CFD) simulations have been used to examine the hydraulic properties and heat transfer characteristics of molten salt NaNO3+KNO3 (60:40 wt ratio) in a horizontal pipe. Analytical data has been used to validate computed results. A comparative analysis has been conducted between the computational results and several correlations. This helps to understand the heat transfer characteristics. Using computational data, the local Nusselt number in the heater region is determined and compared to different correlations. The thermal-hydraulic properties of molten salt obtained from CFD results are compared with existing heat transfer correlations. The most appropriate correlations for obtaining the molten salt's thermal-hydraulic properties have been discussed. Shah and London's correlation to determine Nusselt number predicts very well in thermally developing region compared to Churchill and Oze's correlation. CFD results are helpful to understand the hydraulic behavior of the fluid.