Numerical Simulation Of Filling Process Of Marine Hydrogen Storage Tank

High pressure hydrogen storage is the most widely used and developed hydrogen storage method at present.It has the advantages of low cost,high reliability,low energy consumption and fast charging and discharging speed.Therefore,high pressure gaseous hydrogen storage may be the mainstream scheme of hydrogen storage technology in the early stage of the development of hydrogen fuel cell ships.Because the temperature of marine hydrogen storage tank will rise due to compression effect and Joule Thomson effect,which will affect the safety of the internal structure of hydrogen storage tank and the safety of hydrogen fuel cell ship,it is necessary to conduct a comprehensive study on the charging process of hydrogen storage tank.In this dissertation,the two-dimensional axisymmetric model and three-dimensional model of computational fluid dynamics(CFD)are used to simulate and analyze the filling process of 70 MPa,type III hydrogen storage tank,and the temperature rise and temperature distribution law in the filling process are obtained.In order to ensure the safety and efficiency of the filling process,the effects of structural parameters and filling parameters on the filling process of hydrogen storage tank are further studied.The main research contents of this dissertation are as follows:(1)The law of hydrogen flow and temperature rise in the filling process of hydrogen storage tank is analyzed.The heat generation and heat transfer of hydrogen in the process of filling are explored by using flow trace and temperature cloud diagram;The heat transfer between hydrogen and tank wall in hydrogen storage tank is studied,and the evolution law of temperature rise in each region is obtained;In order to simulate the real filling process,the numerical simulation results of CFD two-dimensional axisymmetric model and three-dimensional model are compared and analyzed,the influence mechanism of gravity on hydrogen and wall temperature distribution is obtained,and the technical suggestions on hydrogen precooling before hydrogen storage tank filling are put forward.(2)The influence of structural parameters of hydrogen storage tank on filling process is analyzed.The temperature rise of hydrogen storage tanks with different length diameter ratio,inlet diameter and inlet pipe length during filling is studied,and the influence laws of different structural parameters on hydrogen distribution are obtained.The larger the length diameter ratio of the hydrogen storage tank,the longer the hydrogen flows to the tank bottom after entering the hydrogen storage tank,and finally form a more obvious local high-temperature area in the tank bottom area.Reducing the length diameter ratio of the hydrogen storage tank as far as possible can improve the safety of the filling process of the hydrogen storage tank;Smaller inlet diameter can promote the disturbance of the filled hydrogen to the original hydrogen and avoid local heat accumulation;The longer the inlet pipe is,the more serious the heat accumulation in the shoulder area of the hydrogen storage tank is.Minimizing the length of the inlet pipe can effectively improve the safety of the filling process.(3)The influence of filling parameters on the filling process is analyzed.The effects of ambient temperature,inlet temperature,filling time and initial pressure on the temperature rise in the filling process were studied.For every 10 ℃ decrease in the inlet temperature,the average temperature of hydrogen at the end of filling can be reduced by about 7.0 ℃.Proper precooling of the filled hydrogen can ensure the safety of filling and improve the amount of hydrogen filled;The ambient temperature and filling time have little effect on the average temperature of hydrogen at the end of filling.Appropriately increasing the filling time in the actual filling process can prolong the time of wall heat dissipation and reduce the overall temperature of hydrogen storage tank;The higher the initial pressure in the hydrogen storage tank before charging,the lower the average temperature of hydrogen at the end of charging.based on the influence law of single charging parameters on temperature rise,the comprehensive influence analysis of multiple charging parameters on temperature rise is carried out,and the relevant correlation of multi parameters on temperature rise is obtained through nonlinear fitting,which can provide a certain reference for the actual hydrogen charging process.