International Journal of Hydrogen Energy, Vol.45, No.11, 6848-6862, 2020
Analytical and numerical predictions of hydrogen gas flow induced by wall and corner leakages in confined space
This contribution addresses a newly developed semi-analytical model coupling the zone model, virtual point source buoyancy plume theory and mirror theory to predict the gas flow behaviors of leaked hydrogen restricted by a wall or a corner in confined space with an opening. The effects of leaked hydrogen mass flux, opening geometry and the leakage location on interface height, outflow velocity and hydrogen molar fraction in upper layer, were thoroughly investigated at steady stage. A computational fluid dynamics tool, FLACS, was employed to simulate the dispersion process in different leakage scenarios and validate the capability of the derived analytical model. The results show that in all center, wall and corner leakage circumstances, the interface height declines with larger leakage mass flux, whereas the outflow velocity and hydrogen molar fraction change inversely. The interface height, outflow velocity and hydrogen molar fraction are positively, negatively and negatively correlated with the opening dimension, respectively. The opening height plays a more important role in determining the interface height and hydrogen molar fraction but hardly affects the outflow velocity. The interface height keeps unchanged with varying leakage locations when other parameters remain constants. However, according to the mirror theory the outflow velocities in corner and wall leakage conditions are 0.63 and 0.4 times of those in center leakage case. Meanwhile, the hydrogen molar fractions of corner and wall leakages are 1.59 and 2.52 times of the ones in center leakage. All these ratios are validated by the corresponding analytical and numerical predictions. The credibility of the analytical model is verified by the good agreement with the numerical estimations. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.