Research On Simulation Analysis Of Hydrogen Leakage And Diffusion In Hydrogen Supply System Of Fuel Cell Truck

With the increasingly serious resource and environmental problems,hydrogen as an environmentally friendly new energy source has become a hit in various countries.Fuel cell vehicle is an important application of hydrogen energy in the field of transportation.Hydrogen is flammable and explosive gas,and it is easy to leak and can quickly diffuse in the air.Once hydrogen is accidentally leaked from the hydrogen system of a fuel cell vehicle,it is likely to burn or explode,causing harm and damage to the driver and the surroundings.Therefore,this paper conducts a numerical simulation study on the hydrogen leakage and diffusion process of fuel cell vehicles.It has certain theoretical significance and engineering application value for the understanding of hydrogen leakage and diffusion characteristics and the safety warning of hydrogen leakage and diffusion of fuel cell vehicles.This paper takes fuel cell semi-trailer truck as the research object,analyzing the composition and characteristics of fuel cell vehicles and on-board hydrogen supply systems.In addition,this study establishes a mathematical model of the hydrogen leakage and diffusion process,and completes the simulation model of the hydrogen leakage and diffusion process of fuel cell vehicles.Based on the established simulation model,a simulation study was carried out on the hydrogen leakage and diffusion process and influencing factors of fuel cell vehicles in open and closed spaces.In open space,the leakage process and diffusion concentration distribution of hydrogen were analyzed when hydrogen leaking to the rear,the front and the upper part of the space.Simulation analysis shows that when hydrogen leaks to the rear of the vehicle and to the upper part of the space,the distribution of hydrogen mainly expands in the direction of the leakage,but when hydrogen leaks to the front of the vehicle,it will accumulate behind the cab,which is not conducive to driver safety.In addition,taking the hydrogen volume fraction in the leakage direction down to the lower flammable limit of 0.04 as a reference,this article gives the safe distance for hydrogen diffusion under various leakage scenarios.The effects of leakage rate,wind speed and wind direction on hydrogen leakage and diffusion in open space are discussed.The results show that the leakage rate significantly affects the hydrogen distribution range,the ambient wind mainly affects the hydrogen diffusion process,and the hydrogen diffusion effect is better under cross wind.This paper analyzes the diffusion process and concentration changes of hydrogen in closed space under various leakage scenarios,finding that when hydrogen leaks to the rear of the vehicle,the hydrogen mainly diffuses around the back wall of the space,and the hydrogen concentration mainly increases along the height of the space when it leaks to the front of the vehicle and upwards of the space.The influence of the area and location of the vents on the hydrogen concentration in the space is studied.Under the scenario of hydrogen leaking backwards,setting up vents with different areas on the top does not significantly change the diffusion process of hydrogen in the space,and the impact on the hydrogen concentration in the space is limited to the vicinity of the vents.The comparison results of setting vents at two different positions at the top and the rear of the space show that the rear vents can allow hydrogen to diffuse to the outside environment faster,and significantly reduce the hydrogen concentration and rise rate in the space.