CFD Numerical Simulation And Structure Optimization Of Hydrogen Thermal Effect Of Hydrogen Storage Reaction Bed Alloys

The exhaustion of traditional fossil energy makes the development of new energy become the focus of attention of all countries,among them,the research on hydrogen energy has become a hotspot in many countries.The primary solution to the effective utilization of hydrogen energy is the storage of hydrogen energy,which is involved in the international thermonuclear fusion experimental reactor(ITER)and China nuclear fusion experimental reactor(CFETR).Hydrogen storage in alloy has become an important way of hydrogen storage due to its large hydrogen storage capacity and mild hydrogen storage conditions.ZrCo alloy,as a hydrogen storage alloy with low pressure hydrogen isotope capture capacity,is regarded as a hydrogen storage material that is likely to replace uranium as an important hydrogen storage material in ITER project.Other ZrCo hydrogen storage alloy is reversible exothermic chemical reactions happened in the exothermic reaction effect will react to hydrogen storage,hydrogen storage have affected the service life of reaction tank,so the deep understanding of the reactor temperature gradient distribution and thermal conductive effect for improving the service life of hydrogen storage reactor and the influence of it is very important to improve the hydrogen storage amount.Therefore,this paper relies on the project to establish a numerical model of the hydrogen storage process of ZrCo alloy containing chemical reaction source term and a numerical model of multi-field coupling analysis containing heat transfer.The UDF programming method was used to load the source program in Fluent flow field software.Considering the influence of multiple parameters on the temperature change and the distribution of temperature gradient in the hydrogen adsorption process of ZrCo hydrogen storage reactor bed,the structure of the reactor bed was optimized according to the influence of multiple parameters.Therefore,this paper carried out the following work:First,this paper first established a pair of ear type two-dimensional hydrogen adsorption reaction bed,then combined with Fluent’s energy control equation to establish a two-dimensional reactor numerical model containing hydrogen adsorption heat source term of chemical reaction,as well as a heat transfer numerical model,and used the UDF programming secondary development program to realize the compilation of the source term.Then,Fluent numerical analysis method was used to discuss the influence of different cooling medium velocity,cooling medium types,different wall materials,different aspect ratios in the reaction zone,and Al powder doping on the thermal conductivity and heat capacity of hydrogen storage materials.Finally,three optimization schemes were designed based on the relative optimal design parameters of the reactor based on five influencing factors.Finally,scheme 2 was determined: three heat transfer fins were added as the final scheme on the basis of adding the central cooling duct in scheme 1.Secondly,on the basis of the two-dimensional hydrogen adsorption numerical model,the three-dimensional hydrogen adsorption reaction zone numerical model is developed by using the related hydrogen storage theory.The hydrogen reservoir material was defined as porous medium region,and the penetration of hydrogen was defined by darcy’s law.According to the hydrogen absorption rate equation,the mass conservation equation,the momentum conservation equation and the energy conservation equation,the numerical model containing the chemical hydrogen absorption heat source term was established,and the three-dimensional hydrogen absorption heat source term was compiled by using the UDF program.Then the multi-field coupling numerical analysis is established and the structure network model of the three-dimension double-layer thin-wall reactor without heating device is established.Finally,the numerical analysis in Fluent updates the temperature change effect at the reaction layer of the calculation center and verifies it by comparison with the Kang’s experiment.The results show that the numerical model is effective.Thirdly,the influence of operating parameters of hydrogen absorption and bed parameters in a double-layer thin-wall reactor was investigated.Under the condition of hydrogen absorption parameters,we considered the influence of cooling water velocity,different initial reaction temperatures,and the influence of Cu powder doping on the thermal conductivity and heat capacity of hydrogen storage materials.For the bed parameters,the effects of different hydrogen storage materials and the thickness of different hydrogen storage layers are considered.On the basis of hydrogen adsorption operation parameters and the optimal solution of bed structure parameters to hydrogen adsorption reaction bed,two structural optimization plans were established: plan 1(30cooling channels)and plan 2(24cooling channels +heat transfer fins).