Modeling and improving liquid hydrogen transfer processes

Hydrogen will play a pivotal role in reducing global carbon emissions. Cryogenic liquid hydrogen -LH2- is a promising storage and transportation solution. However, LH2 transfer processes are complex, and the safe and efficient transfer operations of this fluid require deep and precise understanding. This study extends an existing physics-based model to simulate the dynamics of pressure difference-driven and pump-driven LH2 transfer operations between a supply and receiving LH2 storage tanks. A critical model output is the predicted LH2 boil-off and venting, which is crucial for evaluating system design, safety, efficiency, and environmental impacts. Results show that LH2 pressure-driven transfer processes evaporate up to 20 % of LH2 to pressurize the supply tank and deliver warmer LH2. Switching to a pump-driven transfer process reduces venting to 0 % to 16 % of total hydrogen transferred, where venting is lowest for slow transfer rates and when receiving tank initial pressure is low. Maximum transferred LH2 mass to a receiving tank can be increased by 6.5 % and 13 % versus flow rates that minimize transfer time or venting by manipulating flow rate and initial tank pressures.