Numerical simulation of dispersion and distribution behaviors of hydrogen leakage in the garage with a crossbeam

Abstract

A three-dimensional computational fluid dynamics simulation model resolved by the unsteady Reynolds-Averaged Navier–Stokes equations was developed to predict hydrogen dispersion in an indoor environment. The effect of the height of the crossbeam (Hc) on hydrogen dispersion and distribution behaviors in a four-car garage was numerically investigated under fully confined and natural ventilation conditions. For the fully confined condition, the garage was almost completely filled with a flammable hydrogen cloud at t=600 s. In addition, the volumetric ratio of the flammable region, thickness of the hydrogen stratification, and hydrogen mole fraction all increased as Hc increased. When two symmetric ventilation openings were set up, the volumetric ratio of the flammable region decreased by 50% at t=600 s. Moreover, Hc had evident influence on the vertical distribution of hydrogen mole fraction. In addition, there existed little explosion hazard under the height of 1.6 m. The results show that Hc was a non-negligible factor for the safety design of hydrogen in the garage and Hc=0.12 m was the optimal height of the crossbeam. Furthermore, the ventilation system in the present study cannot completely eliminate the risk of hydrogen explosion. The present risk assessment results can be useful to analyze safety issues in automotive applications of hydrogen.

Numerical Study on the Effects of Ventilation System on Hydrogen Dispersion in an Underground Garage with Smoke Barriers

“…In addition, smoke barriers are often installed in existing large underground garages to limit the spread of smoke, but in the event of hydrogen leakage it can cause a localized increase in hydrogen concentration [3]. Li et al [4] found that the volume ratio of the flammable region in a closed garage tends to increase as the beam height increases; after setting two symmetrical natural vents, the flammable volume ratio decreased by 50%. Merilo et al [5] found that mechanical ventilation resulted in a significant reduction in hydrogen concentration and overpressure from deflagration.…”

Dispersion analysis of hydrogen released from a fuel cell electric vehicles with ventilations

“…The number of the vents is crucial to the ventilation. The compartment with two vents were proposed to enhance the efficiency of ventilation [14][15][16][17][18]. Saikili et.…”

“…Nevertheless, the location of vents dominates partially the pattern of flow. Li et al [16] set up two symmetric ventilation openings to investigate the vertical dispersion and distribution behaviors of the hydrogen, and results showed that the volumetric ratio of the flammable region decreased by 50% at t=600 s.…”