Study on the hydrogen leakage diffusion behavior by obstacles in confined spaces

Abstract

In this paper, a combination of experimental and numerical simulation is used to investigate the effects of obstacles and leakage hole shapes on the leakage diffusion pattern and hydrogen concentration. A small-size cubic geometry model of 0.47 m × 0.33 m × 0.20 m is used to calculate the concentration of the leakage model in the confined environment. The results show that the influence of the Q1-Turbulent Flow obstacle model on hydrogen leakage and diffusion is more serious than that of the Q2-Laminar Flow, the gas in the upper part of the model is easier to accumulate, the hydrogen concentration is higher, and it takes longer to finally reach a stable state. Rectangular leakage holes have a larger hydrogen diffusion range, faster diffusion rate, higher initial kinetic energy, and are more likely to exceed the lower flammability limit of hydrogen. Q1-Turbulent Flow obstacle modeling injection process, t = 0.3 s, the gas cloud just contacted the obstacle, initially spread along the obstacle. With the continuous leakage of hydrogen, a large amount of gas comes into contact with the obstacle, and at t = 0.5 s, the obstacle starts to block the normal diffusion of leaking hydrogen, causing initial kinetic energy loss under the effect of buoyancy and obstacle blocking, and the direction of motion of hydrogen changes. When t = 0.8 s, due to the blocking effect of the obstacle wall, aggregation and vortex area are generated. t = 1 s, the area of vortex area is further increased, at this time, the degree of danger is obviously higher than before, and it is very easy to asphyxiation, explosion and other accidents.