Study on influence mechanism of vacuum multi-layer insulation coupled with vapor-cooled shield on self-pressurization process of liquid hydrogen storage tank

Based on MATLAB program, a transient simulation model considering the vacuum multi-layer insulation, the vapor-cooled shield and the internal fluid domain of liquid hydrogen storage tank is constructed, which can be used to simulate the state change of the storage tank during the full cycle. The dimensionless vapor consumption factor ηc, dormancy extension factor ηs and unit factor η are introduced. ηc represents the vapor consumption of vapor-cooled shield during the full cycle of storage, ηs represents the extension of the dormancy period with vapor-cooled shield opened relative to that with vapor-cooled shield closed, and η is the ratio of ηs to ηc, representing the ability of vapor-cooled shield in shielding heat leakage. The effects of the dimensionless position of vapor-cooled shield, ηc, vapor flow rate and start-up time on ηs and η are investigated. The results show that the optimal position of vapor-cooled shield that maximizes ηs is 0.622 when the starting-up time of vapor-cooled shield is constant. Decreasing ηc helps to increase η. When the position of vapor-cooled shield is 0.622, and ηc decreases from 0.0640 to 0.0128, η increases by 34.7%. However, when the setting of the cooling screen deviates further from the optimal position, decreasing makes the increase smaller. When ηc and the duration time of vapor-cooled shield are fixed, ηs firstly increases then decreases with the delay of the start-up time. When the position of vapor-cooled shield is 0.622, the starting-up time that maximizes ηs is 23.26 d. © 2023 Chemical Industry Press. All rights reserved.