Generalized lumped-parameter modeling of the self-pressurization in liquid hydrogen tanks

The efficient storage of liquid hydrogen is challenged by heat inleak, which leads to evaporation, self-pressurization and potential venting losses. To analyze these processes, a lumped-parameter modeling approach is employed, accounting for non-equilibrium effects between the liquid and vapor phases, while capturing the essential physics. A particular challenge arises from the prediction of heat transfer across the phase boundary, as commonly available Nusselt number correlations do not directly reproduce the observed behavior for cryogenic hydrogen. This issue is addressed by introducing a single fitting parameter for each relevant tank geometry, namely vertical cylinder, horizontal cylinder, and sphere, with the values determined by fitting to experimental data. The resulting maximum deviations between simulation and experiment are within approximately 10 % for the vertical and horizontal cylinders and 15 % for the sphere, which confirms the capability of the model to capture the relevant pressurization dynamics. Overall, the proposed approach provides a computationally efficient and thermodynamically consistent tool for analyzing the self-pressurization and boil-off characteristics of liquid hydrogen storage systems across all relevant tank geometries. • Model reliably predicts pressure in LH2 tanks for all relevant geometries. • The developed lumped-parameter model requires only one single fitting parameter. • Efficient, thermodynamically consistent tool to model self-pressurization. • Simulation results show good agreement with experimental measurements.