Comparative study of thermally stratified heat storage tank using different heat transfer fluids based on fluid-solid coupling method

Abstract The heat transfer fluid material can affect both the behaviors of a heat storage tank. Based on the Fluid-Solid Coupling method, the influences of five different heat transfer fluids on the thermal and mechanical behaviors of the thermally stratified tank are estimated in this paper, including the binary nitrate (KNO3+NaNO3), binary chloride (KCl + MgCl2), ternary nitrate (KNO3+Ca(NO3)2+LiNO3), liquid lead-bismuth eutectic (LBE) and liquid sodium. The simulation results demonstrate that for the charging process, the tank using the ternary nitrate has the best operation behavior, while for the discharging one, that utilizing the binary nitrate has relatively better operation behavior. The standby behavior comparison results indicate that the thermocline stability of the ternary nitrate is the best, but the tank employing the binary nitrate has the smallest cumulative total heat loss. The mechanical performance comparison results show that the binary nitrate salt and binary chloride salt can lead to the smallest and largest maximum mechanical stress of the tank, which are 96.6 MPa and 168.8 MPa. Therefore, the tank utilizing the binary nitrate has the best mechanical behavior.