Numerical Study on Flow and Heat Transfer Characteristics of the Molten Salt Single Tank Heat Storage Process

Aimed at the application of heat storage technology in the field of new energy consumption, a molten salt single tank integrating the heat storage and the heat exchange was proposed. The single tank heat storage characteristics and molten salt heat transfer laws during the heat storage process were numerically simulated and analyzed. The effects of spiral tube spacings and inlet/outlet layout positions on the heat storage process were discussed. The results show that, the molten salt temperature increases gradually in the heat storage process, while the molten salt density decreases and the natural convection forms in the tank. The spiral structure of the tube makes 3 vortices be formed in the flow field of the molten salt. With the spiral tube positioned at the bottom of the tank, the heat storage completion time can be shortened by 34.1% due to a stronger natural convection, compared with the cases at the center and the top of the tank. The increase of the spiral tube diameter may enlarge the heat transfer area and speed up the heating rate of the molten salt. With the increase of the spiral tube spacing, the heating range of the molten salt will be larger, and the heat storage completion time will be shortened slightly. The natural convection of the molten salt is stronger in the inletdown and outletup case since the inlet position is closer to the tank bottom.