Research on Thermal-Hydraulic Characteristics of Liquid Sodium Versus Molten Salt as A Fluid in Heat Exchanger

The synergistic theory and technology of efficient solar energy capture and energy conversion storage is a renewable energy technology with great application prospects. In this paper, the heat transfer medium (HTF) in the molten salt energy storage system of a solar power plant is studied and quantitatively evaluated. Numerical simulation is used to study three types of media including binary molten salt, ternary molten salt, and liquid sodium metal to investigate their thermal-hydraulic properties and mechanisms. The fluid medium is assumed to be isotropic and homogeneous, and the liquid phase is in local thermal equilibrium. The results show that liquid sodium as a heat transfer medium for tower solar collector systems has a more uniform temperature distribution on the tube wall and inside the tube, and has the potential to be more suitable as a heat transfer medium than conventional molten salt in terms of flow and heat transfer. Liquid sodium metal can obtain higher heat transfer coefficient by operating at high flow rate. The results of the study can provide reference and support for the development of advanced and efficient key technologies for photovoltaic energy storage.