Hydrogen related risks within a private garage: Concentration measurements in a realistic full scale experimental facility

The next generation of hydrogen energy based vehicles is expected to come into widespread use in the near future. Various topics related to hydrogen including, production, storage, and application of hydrogen as an energy carrier, have become subjects of discussion in the framework of various European and international projects. Safety information is vital to support the successful introduction into mainstream and public acceptance of hydrogen as an energy carrier. One of such issues, which is seeking major attention is related to hydrogen powered vehicles parked inside a confined area (such as in a private garage). It is of utmost importance to predict, if uncontrolled release of hydrogen from a vehicle parked inside a confined area can create an explosive atmosphere. Subsequently, how preventive measures can be implied to control these explosive atmospheres, if present inside a confined area? There is little guidance currently developed for confined areas accommodating hydrogen fuelled vehicles. It is essential that mitigation measures for such conditions become established.The present work is developed in the framework of ‘European Network of Excellence HySafe’ and the French national project DRIVE (experimental data for the evaluation of hydrogen risks onboard vehicles, the validation of numerical tools and the edition of guidelines). This paper investigates the possible non-catastrophic scenarios that may arise in a real situation from a hydrogen fuelled vehicle parked inside a garage. The studied test cases evaluate the influence of injected volumes of hydrogen and the initial conditions at the leakage source on the dispersion and mixing characteristics in an unobstructed confined environment. The mixing process and build-up of hydrogen concentration are measured for the duration of 24 h. Due to safety reasons, helium is used instead of hydrogen.