Thermodynamic modeling and simulation of subcooled liquid hydrogen refueling for transport applications

Refueling liquid hydrogen in a subcooled state can enhance efficiency and reduce refueling time by minimizing gas venting. Since subcooled liquid entering the tank induces ullage condensation, a thermodynamic refueling model needs to account for this effect. We propose a model using a parameter representing the interaction between the entering liquid and the gas phase to account for ullage condensation. The model is applied to refueling scenarios for heavy-duty trucks and airplanes. Results show that ullage condensation reduces the pressure change during refueling, enabling vent-free refueling when the inlet temperature is sufficiently low, and the interaction between the entering liquid and the gas phase is sufficient. These requirements become more demanding at lower tank pressures. Overall, subcooled liquid hydrogen refueling can eliminate gas venting if the refueling system and the inlet geometry are designed to allow for low inlet temperatures and strong interaction between entering liquid and the gas phase.