The Danger Of Low Temperature Hydrogen Leakage In Open Environment And Diffusion Characteristics

Hydrogen production plants,filling systems and hydrogen refueling stations will cause hydrogen leakage under the influence of operational errors,maintenance errors and environmental factors.Hydrogen itself is lively,with a wide flammability limit,fast combustion speed,and small flame radiation heat 1.The flame is invisible and the flame temperature is high.When the surrounding environment has an ignition source,it is easy to burn or even explode,causing significant damage to the safety of surrounding equipment and personnel.Changes in environmental factors will make the hydrogen jet phenomenon more complicated,resulting in greater economic losses and casualties.This paper further improves the research on the characteristics of hydrogen ejection based on the predecessors,and provides certain guidance for the small-scale leakage of liquid hydrogen in the launch site,as well as the fire protection of chemical plants and hydrogen fueling stations.Practical significance.This paper uses theoretical analysis to find that the leakage pore size,leakage temperature,leakage pressure and other factors,as well as environmental factors such as wind speed and wind temperature,have a greater impact on the hydrogen leakage process The commercial software FLUENT is used to numerically simulate the hydrogen leakage diffusion process,and the research is different.Influence of factors on the behavior of low temperature hydrogen diffusionThe main content includes the following four aspects(1)According to previous studies,the causes of liquid hydrogen leakage are summarized,and the fault tree method is used to find out the cause of the leakage,and it is found that the storage tank pipeline is prone to low-temperature hydrogen leakage.Among them,the pore size of the leakage source,the leakage temperature and other parameters and environmental factors Changes will cause the low temperature hydrogen diffusion behavior to be different.(2)The behavioral characteristics of the low-temperature hydrogen jet process are explored by changing the influencing factors of the leakage source and the environmental factors.The simulation results show that the influence of the environmental wind,the size of the leakage hole and the leakage temperature are more significant,and the air is artificially blown upward from the ground side Incoming wind)is more conducive to the diffusion of hydrogen and protects the safety of surrounding equipment and personnel.The increase in the leakage pore size increases the range of hydrogen diffusion,and the decrease in leakage temperature is more conducive to the control of hydrogen diffusion behavior.(3)Comparing the results of leakage temperature and leakage pore diameter,the area of hydrogen danger zone decreases when the leakage temperature increases;the orthogonal experiment method is used to study the hydrogen diffusion behavior characteristics under the influence of three factors,and it is found that the leakage pore diameter significantly affects the low temperature hydrogen diffusion behavior.The optimal combination under the influence of factors is a leakage height of 0.2m,a lower wind speed of 5m/s and a leakage aperture of 1mm.Under this combination,the hydrogen leakage diffusion area is the smallest.(4)Summarize the distribution rule of the axial hydrogen mass fraction attenuation of the jet under the influence of multiple factors.The attenuation curve of the hydrogen mass fraction Ycl of the jet center with the axial distance z is 1/Ycl=0.21/d*-20,d*which is the dimensionless characteristic length,Introduce the influence of wind speed and modify d*,d*=dexit(ρexit(1+v)/8.74 ×10-3 ρ∞vexit)0.5,vexit is low-temperature hydrogen jet velocity,v is the forward wind speed Obtain the hydrogen axial mass fraction attenuation curve 1/Ycl=0.197z/d*1-9.07.