Allowable hydrogen permeation rate from road vehicles

Dispersion and burning behavior of hydrogen released in a full-scale residential garage in the presence and absence of conventional automobiles

“…Proposed standards for these vehicles are designed to ensure that any hydrogen leaks are sufficiently slow that flammable mixtures can not develop in realistic garages. Nonetheless, concerns about potential accident scenarios that result in larger leak rates have led to numerous studies designed to characterize the mixing behavior of hydrogen (often helium is used as a surrogate) released into partially enclosed spaces typical of residential 5 Official contribution of the National Institute of Standards and Technology not subject to copyright in the United States.…”

“…Code bodies in the United States have recommended that minimum air exchange rates exceed 3 ACH [3,4], but there is evidence that the majority of garages in North America have ACH values greater than 0.25 h À1 but less than 3 h À1 [2]. Adams et al concluded that the vast majority of garages have ACHs, with most significantly, less than one [5].…”

Data for the evaluation of hydrogen risks onboard vehicles: Outcomes from the French project drive

“…Since permeation is related to the smallness of the hydrogen molecule, it can affect all materials. As mentioned by [9], the permeation rate can be considered negligible for metallic containers or containers with metallic liners (commonly known as Types 1, 2 or 3). However, hydrogen permeation could be an issue, and therefore requires attention, for containers with non-metallic liners (Type 4).…”

Assessment of an Innovative Way to Store Hydrogen in Vehicles

“…Reservoirs made of polymeric materials (type 4) must be subjected to permeation tests. In fact, polymeric materials have much higher permeability than metallic materials [39]. Moreover, the same regulation allows a maximum permeation flowrate of 6 Ncm 3 h −1 L −1 (NPT) per liter of inner volume of the reservoir at steady state.…”