Critical ventilation thresholds for hydrogen leakage of fuel cell vehicles in tunnels based on scaled experiment

With the increasing adoption of fuel cell vehicles (FCVs), the potential for hydrogen leakage and the associated significant risks in tunnel environments present a formidable challenge to tunnel ventilation and safety management. Existing research mainly focuses on the role of different ventilation speeds in reducing leakage risks but does not explore the ventilation requirements under various leakage conditions and control constraints. This study proposes a critical ventilation speed inversion method based on experimental approach, introducing “critical safe wind speed” and “critical effective wind speed” to consider marginal effects and safety control objectives. Based on a scaled tunnel model, 20 experiments are conducted under four leakage rates and five ventilation speeds, establishing a quadratic function relationship model between critical ventilation speed and leakage rate. Additionally, the ventilation requirements for FCV leakage pressure of 35 MPa, 1.5 MPa and 0.15 MPa in real tunnel scenarios are derived: the critical effective wind speeds are 15.51 m/s, 2.15 m/s and 1.08 m/s, and the critical safe wind speeds are 19.11 m/s, 3.48 m/s and 3.04 m/s respectively. A quantifiable, reliable and convenient guidance for tunnel ventilation under hydrogen leakage of fuel cell vehicles is provided.