Study on heat transfer characteristics and mechanical properties degradation of hydrogen storage cylinders under fire conditions

As the most common containers for hydrogen fuel cell vehicles, the development of hydrogen storage cylinders has attracted significant attention. However, due to the inherent flammability of hydrogen, fire incidents can lead to various forms of material damage and structural failure in these cylinders. In this study, a CFD model was established to simulate hydrogen storage cylinder exposed to fire, and a coupled thermal-fluid-structure FEA model of the cylinders was developed through module correlation. The models examined heat transfer characteristics, mechanical responses, and progressive failure mechanisms under fire conditions, providing predictions for burst pressure and fire resistance time. Results indicate significant temperature variations across different regions of the cylinder's outer surface, with distinct stratification of wall temperatures, particularly pronounced near the Pressure Relief Device (PRD) region. The cylinder experiences coupled effects of external fire thermal loads and internal hydrogen pressure loads, resulting in an increase in equivalent stress with prolonged exposure to fire, leading to an uneven distribution of stress throughout the cylinder. Under fire conditions, the primary failure modes of the cylinder's composite material layers include fiber fracture failure (pf) and matrix tensile failure (pmA), with delamination failure (pd) observed exclusively at the rear end of the cylinder.