Effect of a cryocooler on thermodynamic behavior of cryogenic liquid during storage

To probe effective control strategy of the pressure buildup for a tank equipped with a cryocooler during storage of cryogenic liquids, a time-dependent thermodynamic model is developed. Taking into account heat flux and initial filling ratio, the inhibitory effect of refrigerating capacity on pressure buildup is investigated. Furthermore, an experimental system is also constructed, and the validation results indicate that the vapor temperature obtained by the time-dependent thermodynamic model accurately reflects the temperature gradient in the vertical direction of the vapor space. These results exhibited maximum errors of less than 8.5 % for mean evaporation rate and less than 7 % for pressure, confirming the model's reliability. In addition, the analysis of refrigeration capacity's influence on cryogenic liquid thermodynamic behavior reveals that it effectively inhibits vapor temperature escalation, inducing more pronounced mean temperature fluctuations in vapor compared to liquid. The inhibitory effect of refrigerating capacity on evaporation is enhanced as the heat flux increases or the initial filling ratio decreases. Additionally, refrigeration capacity promotes liquid thermal expansion while simultaneously inhibits the upward trend of vapor density, thereby improving the effectiveness of pressure control measures. The refrigeration capacity exerts an inhibitory effect on both the vapor temperature and the evaporation rate, while the influence of liquid thermal expansion is notably delayed. Therefore, the interaction of the above three factors enables refrigeration capacity to exert significant regulatory influence on pressure buildup under various conditions.