Analysis and design for ensuring release safety of Multi-Hydrogen cylinder bundles under real fire experiment

During a fire incident, onboard hydrogen storage cylinders in fuel cell vehicles (FCVs) pose a risk of explosion or deflagration, and the risk may be greater for multi-hydrogen cylinder bundles (MHCB). To explore the safety issues associated with the simultaneous release of hydrogen from multiple cylinders, this study for the first time publicly reports a real fire experiment on an actual high-pressure hydrogen-filled MHCB of four hydrogen cylinders. The experiment obtains the hydrogen temperature and pressure changes inside each tank from the start of the fire until the complete release of hydrogen. During the releasing process, the hydrogen release pipeline (HRP) experiences serious plastic deformation due to the jet recoil force, so that hydrogen cannot be discharged in the prescribed direction, which brings significant safety hazards for real FCV applications. To address this issue, a stress simulation of the thermal pressure relief device (TPRD) hydrogen-releasing process is performed. By analyzing the forces at the fracture locations of the HRP, several potential optimization structures are proposed. The stress and strain conditions of these optimized HRPs are also discussed, which can provide guidance for the structural safety design of HRPs.