A Numerical Study Of The Accidental Leakage And Diffusion Law Of High Pressure Hydrogen In Hydrogen Refueling Station

As a clean,efficient and renewable secondary energy source,hydrogen has great application prospects.Due to the unique properties of hydrogen,there are great hidden dangers in high-pressure storage and transportation,and the leakage of hydrogen in hydrogen refueling stations is a major safety hazard.Therefore,it is crucial to accurately predict the accidental leakage and diffusion of high-pressure hydrogen.This paper analyzes the influence of hydrogen refueling canopy structure and external environment on the flow field of high-pressure hydrogen leakage,which provides a theoretical basis for the safe construction of hydrogen refueling stations.In this paper,a numerical simulation study is conducted for the high-pressure hydrogen leakage problem.A high-pressure underexpanded jet model modified by the virtual nozzle model is used,in which the deviation of the high-speed jet from the ideal gas properties is considered and the Abel-Noble gas equation of state is introduced.Based on the model,the numerical calculation method of high-pressure underexpanded hydrogen diffusion and the leakage boundary conditions are established,and the experimental data are compared and analyzed with the simulation calculation results to verify the accuracy of the model calculation.A physical model is established based on an actual hydrogen refueling station.Fluent software is employed to simulate the leakage and diffusion process of high-pressure hydrogen gas.The effects of hydrogen leak stagnation pressure,stagnation temperature and leak hole diameter on the flow field structure in a flat canopy structure are investigated by virtual nozzle size,Mach disk position and hydrogen concentration.Meanwhile,the transport characteristics of the jet and hydrogen concentration distribution driven by momentum and buoyancy are investigated.Based on the diffusion law of the flat canopy structure,a "V" canopy structure with different angles is proposed to facilitate the diffusion of hydrogen.The concentration distribution and diffusion law of hydrogen of the "V" canopy structure with different angles are studied.Furthermore,the vortex structure formed by the interaction of hydrogen with the wall at the top of the canopy and the fluid dynamics are investigated.In addition,the influence of external environment on hydrogen leakage is considered.It is found that the influence of ambient wind speed on the flow and dissipation of clouds of combustible gas is significant,and the wind speed increases the degree of turbulence between air currents,which has a better effect on the dilution of hydrogen concentration.However,excessive wind speed causes near ground hazards.On this basis,it is proposed to add a ventilation system to reduce the hydrogen concentration in areas prone to gas accumulation.The process of high-pressure hydrogen leakage and diffusion is analyzed by numerical simulation,and the hazardous area caused by hydrogen leakage is evaluated to propose strategies that can reduce the concentration of flammable gas hydrogen.The relevant research findings have reference significance for predicting the flow field characteristics of hydrogen leakage and provide theoretical support for the design and planning of hydrogen refueling stations.