Method for evaluating heat leakage in horizontal cryogenic vessels at any liquid level

Heat leakage into cryogenic vessels is a major parameter to reflect the thermal insulation performance as calculated by the loss product of a percentage in standard. If the loss product is tested at low liquid levels for a cryogenic vessel, considerable medium and time will be saved in the test process. However, heat leakages typically exhibit large errors and cannot properly reflect the thermal insulation performance. To solve this problem, the heat transfer process is analyzed for a test loss product to determine the reason for this failure and to realize heat leakage tested at any liquid level. Based on analysis, heat leakage can be divided into latent heat that caused by a portion of the liquid evaporating into gas and enthalpy rise that caused by a temperature increase in the evaporated liquid during its flow from the interface to outside the cryogenic vessel. Thus, a new method is then introduced, and the enthalpy rise is further analyzed and calculated to correct the tested heat leakage at different liquid levels. The corrected heat leakage results were found to be nearly consistent and thus properly reflected the thermal insulation performance. Therefore, the heat leakage can be tested at a low liquid level to save considerable medium and much time. In addition, the maximum difference of the corrected heat leakages was less than 5.0% as compared to the average and with the initial heat leakage of over 23%.

Automated summary

Heat leakage is an important parameter to evaluate the thermal insulation performance in cryogenic vessels. By analyzing and correcting the heat leakage test results, the thermal insulation performance can be accurately reflected.