Hydrogen Explosion Venting in Confined Spaces: A Review

Explosion venting is widely used to limit overpressure in confined systems, although its effectiveness depends on complex interactions between combustion, flow, geometry and external conditions. This review examines the phenomenology of vented hydrogen explosions, the main parameters governing their severity, recent experimental and numerical advances, and current design standards. The literature shows that hydrogen concentration, ignition position, vent characteristics, congestion, enclosure geometry and scale affect not only the maximum overpressure, but also the sequence and physical origin of the pressure peaks. Experimental studies highlight the importance of external cloud combustion, flame-acoustic coupling and obstacle-induced turbulence, while CFD models can reproduce overall pressure and flame-propagation trends but remain sensitive to modelling assumptions and validation conditions. Existing standards, particularly EN 14994:2007 and NFPA 68:2023, provide a valuable basis for preliminary design and engineering practice, although additional assessment may be required for highly reactive mixtures, congested layouts and non-standard geometries. Further large-scale testing, benchmark validation and integrated experimental-numerical approaches are needed to improve the reliability of explosion-venting design for hydrogen applications.