Co-simulation of thermal behavior in liquid hydrogen tanks under vacuum degradation

The duration of no-venting storage and transportation of liquid hydrogen (LH2) relies heavily on thermal insulation performance, which is fundamentally determined by the vacuum level within the insulation structure. When the vacuum level degrades, the LH2 tank will face the risk of severe heat leakage. However, the existing research only considers the impact of vacuum degradation on the insulation structure. The systemic effect of the vacuum degradation on the heat leakage and thermal behavior in the LH2 tank remains poorly investigated. To address this gap, this study proposes a novel co-simulation framework integrating computational fluid dynamics and a 1-D heat transfer model to investigate the thermal response characteristics of LH2 tanks under varying vacuum levels. The coupled model examines the impacts of thermal boundary temperature, initial filling ratio, insulation structure type, and tank size on heat leakage and self-pressurization dynamics. The results reveal that vacuum degradation significantly increases heat leakage and self-pressurization rates. Without taking the heat leakage through supports and pipelines into account, the tank size and thermal boundary temperature are identified as primary factors influencing heat leakage, while self-pressurization is predominantly affected by tank size, thermal boundary temperature, and initial filling ratio. This work provides critical guidance for the design of LH2 storage systems in safe and efficient long-term transportation.