Impact Evaluation of Cold Heat Transfer Fluid Temperature on Heat Storage and Mechanical Behaviours of an Energy Storage System Using Phase-Change Material

This study launches an impact evaluation of initial cold heat transfer fluid (HTF) temperature on heat storage and mechanical behaviours of a thermal stratification tank using phase change material (PCM) capsules and binary nitrate molten salt. A cyclic operation process of the tank is simulated under the condition with fixed parameters. The results show that the tank can operate stably and the durations of charging and discharging processes are 365.0 min and 264.0 min, respectively. The impact evaluation results of the initial cold HTF temperature on the thermal behaviour of the tank reveal that the initial cold HTF temperature has very small impact on the thermal and heat storage behaviours of the tank during charging processes, while a properly lower initial cold HTF temperature can improve the heat storage behaviour during discharging processes. The impact evaluation results of initial cold HTF temperature on the mechanical performance of the tank show that the peak mechanical stress of steel layer moves towards the higher height direction with the initial cold HTF temperature increased. When the initial cold HTF temperature is 506.0 K, the maximum mechanical stress of the steel layer is 111.8 MPa. The axial maximum mechanical stress of the steel layer can be reduced by increasing the initial cold HTF temperature.