Experimental and Simulation Study on Thermomechanical Coupling Behavior During the Filling and Cooling Process of Vertical Cryogenic Storage Tanks

Abstract Non-uniform cooling behavior during the filling and pre-cooling process of cryogenic liquefied gas storage tanks is prone to induce thermal stress concentration, a critical factor leading to structural failure. However, current research primarily focuses on laboratory-scale bottom-inlet-top-outlet tanks, with insufficient attention paid to thermomechanical coupling behavior in structural discontinuity regions, limiting their engineering guidance value. This paper establishes a temperature field prediction model for the filling process of a vertical liquid nitrogen storage tank by integrating experimental and numerical simulation methods. Validated by experimental data, the model was applied to simulate three industrial tanks of different capacities, systematically revealing the influence of filling rate and aspect ratio (length-to-diameter ratio) on the thermomechanical evolution. The results indicate that the tank body cools down first from the bottom, with a significant temperature difference persisting long-term between the tie rods and the tank wall. Notably, the junction between the liquid nitrogen inlet pipe and the top head endures the most drastic thermal stress variation; the stress value continuously rises with increasing filling rate until the temperature difference limit is reached, and the temperature drop in the lower section is particularly sensitive to changes in aspect ratio. These findings elucidate the synergistic regulatory mechanisms of filling parameters and structural dimensions on the temperature and stress fields, providing a theoretical basis for optimizing the filling operation of industrial storage tanks and preventing local stress risks.