Hydrogen fuel-cell forklift vehicle releases in enclosed spaces

Sandia National Laboratories has worked with stakeholders and original equipment manufacturers (OEMs) to develop scientific data that can be used to create risk-informed hydrogen codes and standards for the safe operation of indoor hydrogen fuel-cell forklifts. An important issue is the possibility of an accident inside a warehouse or other enclosed space, where a release of hydrogen from the high-pressure gaseous storage tank could occur. For such scenarios, computational fluid dynamics (CFD) simulations have been used to model the release and dispersion of gaseous hydrogen from the vehicle and to study the behavior of the ignitable hydrogen cloud inside the warehouse or enclosure. The overpressure arising as a result of ignition and subsequent deflagration of the hydrogen cloud within the warehouse has been studied for different ignition delay times and ignition locations. Both ventilated and unventilated warehouses have been considered in the analysis. Experiments have been performed in a scaled warehouse test facility and compared with simulations to validate the results of the computational analysis.

► Consequences of hydrogen fuel-cell forklift vehicle releases in enclosed spaces were studied.
► Simulations were used to model the release of hydrogen from a vent on the forklift.
► The simulations were validated by performing tests in a scaled enclosure.
►  Results show that passive ventilation can mitigate deflagration overpressure.