Study On Hydrogen Leakage Diffusion And Air Distribution In Underground Garage

Hydrogen energy and fuel cell technology is an important way to achieve carbon neutralization and a major strategic direction for the transformation and development of the world’s energy industry and power industry.Hydrogen fuel cell has the advantages of zero emission,high efficiency and renewable energy.It is known as the ultimate goal of the development of new energy power.It is an important strategic measure to deal with global energy shortage and environmental pollution.The development of fuel cell technology has become a breakthrough in the transformation and upgrading of global energy and power.As the "root technology" in the field of energy,fuel cell technology has become a hot spot in the research and development of automotive power.However,as hydrogen is flammable and explosive,once it leaks,it will threaten the safety of people or property,especially in small closed or semi closed spaces such as garages.Space limitation is not conducive to diffusion and will aggravate H2 accumulation.However,whether the ventilation of existing garages can meet the ventilation requirements after hydrogen leakage has not been studied in depth.Therefore,the extensive promotion of hydrogen fuel cell vehicles and the optimization of garage in the new situation need to be deeply studied.In this paper,a computational fluid dynamics model of hydrogen leakage and diffusion in a real garage is established,which consists of a near-field jet model and a far-field diffusion model.In order to accurately describe the thermophysical properties of high pressure hydrogen,Peng Robinson equation of state of real gas is embedded in the near-field jet model.Compared with the experimental results,the reliability of the model is verified.The airflow expands rapidly at the nozzle exit and forms a Mach disk.The study of near-field provides the basic boundary conditions for the far-field diffusion simulation.Then,the leakage and diffusion characteristics of H2 in the closed garage under different leakage positions are simulated,and the distribution of H2 concentration under different leakage conditions is studied.The results show that hydrogen diffusion is strongly affected by buoyancy,and the diffusion speed is fast and the diffusion area is large.The buoyancy driven gas plume reaches the ceiling and diffuses in all directions,forming a flammable layer along the ceiling.This paper also discusses the influence of garage ventilation on hydrogen diffusion.The exhaust mode of hydrogen is suitable for the top exhaust,and try to make the flow field more uniform,so as to facilitate the dispersion of hydrogen.At the same time,the natural ventilation mode of large area exchange with the outside air is conducive to the dilution of hydrogen and reduces the risk of accumulation.The research results of this paper have reference significance to promote the application of hydrogen fuel vehicles and the improvement of garage ventilation in the new form.