Towards a novel boil-off gas handling system for liquid hydrogen fuel cell vehicles

This study introduces a boil-off gas (BOG) handling system for fuel cell vehicles, incorporating a metal-organic framework (MOF) buffer storage tank to enhance the performance and safety of onboard liquid hydrogen (LH₂) storage. Unlike prior approaches focusing on insulation, cooling, or compression, this work explores a passive intermediate storage strategy that uses MOFs to temporarily adsorb and recycle boil-off hydrogen. Analysis indicates that the hydrogen recycling capacity improves by over 30 % at 0.8 MPa compared to 0.5 MPa, enabling smaller tank volumes at higher pressures. Although ambient heat transfer reduces performance, its impact is less pronounced at elevated pressures. Under 273–293 K conditions, the system can extend dormancy by one to several days depending on boil-off rate and MOF tank size. Additionally, the system assists with pressure stabilization and enables safer venting through auxiliary heating, facilitating emergency disposal. This work provides an early-stage feasibility assessment of a novel approach to managing BOG in vehicle-scale LH₂ systems.