Experimental Study on the Transient Thermodynamic Behavior of Gas–Liquid Flow in a Cryogenic Zero Boil-Off Storage Tank

Abstract Zero boil-off (ZBO) storage technology that integrates passive insulation with active refrigeration serves as the fundamental technical basis for the long-term and stable storage of cryogenic liquids. To explore the transient thermodynamic behavior of the gas–liquid flow within the storage tank and research the optimal coupling forms between the refrigerator and the tank during the ZBO storage process, a ZBO experimental setup was constructed. Initially, the mechanisms of thermal stratification and the tank pressurization during the self-pressurization phase were investigated. Subsequently, a comparative analysis was carried out regarding the power consumption of the refrigerator and the internal transient thermodynamic behavior under various coupling forms between the refrigerator and the tank. The results indicated that the refrigerator power consumption under the cooling liquid form was decreased by 29.4% in comparison to that under the recondensing gas form. Moreover, the cooling liquid form significantly enhanced the convection of the fluids, effectively alleviating the thermal stratification phenomenon. Furthermore, the effects of storage pressure and initial filling rate on the refrigerator power consumption and the internal thermodynamic behavior were analyzed. The setup provides valuable insights for the development of a measuring device that couples multiple parameters of temperature and pressure.