Simulation And Experimental Research On Hydrogen Absorption And Desorption Performance Of Solid Hydrogen Storage Vessel

Metal hydride hydrogen storage（solid hydrogen storage）has the advantages of large hydrogen storage,simple storage conditions and long service life.However,the current research on the process of hydrogen absorption and desorption is mostly in the stage of simulation and numerical research,and lacks the experimental test of the heat transfer process inside the container and the type of structure suitable for metal hydrides.In view of the current research situation,the thesis first uses the multi-field coupling software COMSOL to simulate the hydrogen absorption and desorption process of the solid hydrogen storage container（filled with La Ni₅ hydrogen storage alloy）;After that,an experimental platform for hydrogen absorption and desorption was built to measure the hydrogen absorption and desorption performance of the solid hydrogen storage container and the internal temperature value;finally,the structure of the hydrogen storage container was improved to improve its comprehensive performance.The specific research content and results are as follows:Based on the conservation of energy,mass,momentum and reaction kinetics equations,a two-dimensional axisymmetric model of a tank-type hydrogen storage container was established and filled with La Ni₅ hydrogen storage alloy to simulate the hydrogen absorption and desorption process inside the solid hydrogen storage container.Research indicates:The change trend of the average hydrogen absorption temperature of the hydrogen storage vessel first increases and then decreases.The average temperature change trend of the hydrogen desorption is first decrease and then increase.The hydrogen absorption and desorption reactions start from the heat exchange wall,and the reaction zone moves to the center of the container over time.In the hydrogen absorption reaction,the pressure was increased from 1 MPa to 3MPa,the hydrogen absorption in the container was increased by 0.8%in 20000 s,and the average temperature of the container recovered faster;The initial temperature is increased from20°C to 40°C,the hydrogen absorption is reduced by about 10%,and the average temperature increases with the increase of the initial temperature;The convective heat transfer coefficient increased from 10 W·m^-2·K^-1 to 1652 W·m^-2·K^-1,the hydrogen absorption increased by about45.1%,and the average temperature decreased as the heat transfer coefficient increased.In the hydrogen evolution reaction,the initial temperature was increased from 20°C to 40°C,and the amount of hydrogen evolution increased by about 90.7%;The convective heat transfer coefficient increased from 10 W·m^-2·K^-1 to 1652 W·m^-2·K^-1,and the amount of hydrogen released increased by about 114.1%.Taking the simulated hydrogen storage container structure as a reference,the tank-type solid hydrogen storage container was processed and a test platform was built.The experimental performance of hydrogen absorption and desorption corresponding to different installation conditions,convective heat transfer coefficient and initial temperature is studied.Research indicates:During the hydrogen absorption process,the hydrogen absorption capacity of the container in the vertical and horizontal installation states is 6.78 g and 8.98 g,respectively,and the hydrogen absorption performance of the horizontal installation is increased by about 32%;Air and water exchange heat,and the hydrogen absorption capacity of the container is 8.98 g and 26.6 g,respectively.Increasing the convective heat transfer coefficient can increase the hydrogen absorption performance by about 196%;During the hydrogen desorption process,increasing the initial temperature from 20°C to 40°C can effectively increase the hydrogen desorption capacity.The amount of hydrogen released at 40°C is 37.2 g,which is about 33%higher than that at 20°C.Changing the conditions can increase the hydrogen absorption and desorption capacity of the container,but there is a big gap between the hydrogen absorption and desorption capacity of the container and the theoretical value,and the hydrogen absorption and desorption rate of the container is relatively slow.A multi-tubular hydrogen storage container was designed to increase the heat transfer area and mass transfer capacity under the same volume,and an experimental study on hydrogen absorption and desorption was carried out.Experimental results show:The overall performance of the multi-tube container has been greatly improved,and the average temperature of the hydrogen absorption process of the container is reduced by about 20°C;The total hydrogen absorption of the multi-tube container is 39.6 g,accounting for 84.46%of the theoretical value,which is 48.91%higher than the hydrogen absorption of the tank container（26.6 g）under the same conditions;The average rate of hydrogen discharge in multi-tube vessels is 16.9 L/min,which is about 3 times higher than the rate of hydrogen discharge in tank vessels（5.0 L/min）.Under the same process parameters（hydrogen supply pressure,initial temperature,convective heat transfer coefficient）,the improved hydrogen storage/desorption performance of the multi-tubular vessel has been greatly improved.