Hydrogen fuel cell vehicles on highways: Leakage diffusion characteristics and safety assessment

With the rapid development of hydrogen fuel cell vehicles (HFCVs), the risk of hydrogen leakage and explosion on highways urgently requires in-depth research. This study systematically analyzed the impact of leak aperture (2 mm, 4 mm, 10 mm), leakage volume (64 L, 128 L, 192 L), environmental wind speed (0–8 m/s), and obstacle layout on hydrogen diffusion and explosion consequences by constructing a three-dimensional highway accident model and integrating computational fluid dynamics (CFD) with the TNO Multi-Energy method. The results indicate that in an open environment, the greater the leak aperture and leakage volume, the lower the environmental wind speed, and the higher the density of obstacles, the more significant the increase in explosion risk. For instance, under conditions of a 10 mm aperture, 192 L leakage volume, and 0 m/s wind speed, the peak overpressure reaches 68.9 kPa, corresponding to a 90 % tympanic membrane rupture distance of 1.65 m. This study further proposes a three-tier emergency evacuation strategy (core danger zone ≤1.65 m, secondary risk zone 1.65–6.86 m, peripheral monitoring zone 6.86–15 m), which can provide a scientific basis for emergency response to hydrogen vehicle accidents on highways. The findings fill the gap in hydrogen safety assessment in open environments and are of great significance for promoting the large-scale application of hydrogen energy transportation.