Non-Equilibrium Liquid Hydrogen Tank Modeling When Thermal Insulation Fails

The failure of liquid hydrogen (LH2) tank thermal insulation can lead to excessive heating of the stored hydrogen, causing it to boil and triggering safety mechanisms such as a pressure relief valve or a burst disc to prevent catastrophic vessel failure. This study investigates the boil-off behavior inside LH2 tanks using lumped parameter modeling. A non-equilibrium storage tank equipped with a pressure relief valve or burst disc is modeled, accounting for convection and different boiling regimes, flash evaporation during pressure drop when rupture activated. The model is validated against NASA and BMW experimental data. Furthermore, the study analyzes the LH2 tank under various thermal scenarios, including normal operation, loss of vacuum due to air ingress or ice formation, and an engulfing fire scenario combined with vacuum failure. The findings provide critical insights and methodologies for the safety evaluation and robust design of cryogenic hydrogen tank.