Research on hydrogen leakage diffusion and safety analysis in hydrogen fuel cell vehicles with regard to leakage location and ventilation ports.

With the increasing popularity of hydrogen fuel cell vehicles (HFCV), the risk of hydrogen leakage is becoming increasingly prominent. The closed nature in the vehicle structure may lead to rapid accumulation of hydrogen in the cabin when a leak occurs, creating a high concentration that can threaten passengers' respiratory safety and even their lives, as well as potentially triggering an explosion accident. Therefore, this study focuses on hydrogen fuel cell vehicles (HFCVs) with a hydrogen storage pressure of 70 MPa, applying computational fluid dynamics (CFD) methods to simulate the diffusion of hydrogen leakage at different locations, and discusses the impact of leakage rates, leakage hole shapes, and ventilation conditions. This study reveals how hydrogen concentration and distribution change with time in the vehicle under different leakage scenarios, providing important theoretical support for improving the safety of HFCVs. The results indicate that hydrogen leaks at different positions lead to different concentration distributions. Specifically, leaks at position one can accumulate hydrogen between the driver and co-driver, increasing the flammable risks for the front seats. Leaks at position two gather around the seats and spread outward, with the area around the vehicle's roof edge prone to hydrogen accumulation. Leaks at position three, due to the confined space of the trunk, lead to a rapid increase in hydrogen concentration. Further analysis indicates that the higher the leakage rate, the faster the hydrogen diffuses, and the broader the range of concentration distribution becomes; the irregular rectangular shape of the leakage hole accelerates the diffusion speed of hydrogen in both horizontal and vertical directions, expanding the diffusion range. The location of the vent plays a significant role in controlling hydrogen diffusion under different leakage positions. At position one, the vent at the front of the car can effectively reduce the hydrogen concentration on the hood and driving position. At position two, the vents at the front and rear of the car can more rapidly decrease the hydrogen concentration inside the vehicle, reducing the time personnel are in danger. At position three, the vent at the rear can effectively promote the quick exhaust of hydrogen, lowering the concentration inside the car and reducing the risk of ignition. • Focusing on the hydrogen leakage at different positions in the car, the state of hydrogen leakage on the concentration distribution inside the car is analyzed. • The shape of the leak hole has a significant effect on hydrogen diffusion in the vehicle. The irregular rectangular shape of the leak hole spreads the fastest and most widely in both horizontal and vertical directions, increasing the risk of hydrogen explosion in the car. • The location of the vents is critical to controlling the spread of hydrogen leaks，and the position of the vent determines the path of hydrogen control and diffusion. • This paper analyzes the impact of different leakage rates on the speed and range of hydrogen diffusion. [ABSTRACT FROM AUTHOR]