Influence of filling methods on the cool down performance and induced thermal stress distribution in cryogenic tank

Experiments were performed to investigate the cool down performance and thermal stress in an aluminum tank versus filling elapsed time with different liquid nitrogen filling methods, i.e., the bottom axial filling, top axial filling and top lateral sprayer filling. Among three filling methods, the top lateral sprayer filling obtained the fastest cool down of the entire tank, however accompanied with the greatest temperature gradient and the most serious thermal stress. Comparatively, axial filling methods led to more uniform temperature distributions and lower thermal stress levels. The peak value of thermal stress for a top axial filling was about 75% of that for a bottom axial filling under the same feeding rate, although the thermal stress distribution patterns were similar. The thermal stress for a top lateral sprayer filling had descending values in the lower part of the tank, while kept at a much higher level in the central and upper part. The peak value reached up to 50% higher than that of a bottom axial filling. This work could be beneficial to the selection and design of filling methods, which are significant to cryogenic tanks in consideration of filling efficiency and safety.