Numerical Simulatin Of Electrochemical Properties And Thermal Stress Field Of Solid Oxide Fuel Cell

Green energy is the main trend of future development in the field of energy,and it is also one of the important means to effectively alleviate the problem of the shortage of traditional energy and environment pollution.Hydrogen energy is not only widely available,but also a source of clean energy,especially after the reaction,the product will not cause pollution to the environment.Therefore,hydrogen-fueled Solid Oxide Fuel Cell attracts extensive attention.In the thesis,based on the working principle of the planar anode-supported SOFC,the electrochemical performance and thermal stress field distribution were simulated by finite element analysis method.The influence of its operating parameters and flow field design on electrochemical performance with thermal stress field were studied to improve the output characteristics and structural performance of SOFC.And the main research contents of the thesis include:(1)A steady-state simulation model of the planar anode-supported SOFC was established,and the simulation analysis of the SOFC thermal stress-coupled electrochemical reaction was realized.The simulation results were consistent with the corresponding experimental results.(2)Due to the internal structure and electrochemical reaction of the SOFC,the temperature field,component distribution,and current density were unevenly distributed.Increasing the inlet rate of the oxidizing gas or increasing the intake mole fraction of fuel gas,and increasing the operating temperature of SOFC were all beneficial to the improvement of the electrochemical performance of SOFC.Under the same conditions,when using co-flow,the electrochemical performance of SOFC was better than that of counter-flow and cross-flow.Optimization of the size of the flow channal to improve the electrochemical performance of the SOFC includes: If channel height and the number of channels were fixed,increase the air flow width;or in the case that channel height and the total amount of air flow were fixed,it was appropriate to increase the channel number;and if the channel width and channel number were fixed,it was appropriate to increase the channel height.(3)The SOFC in the co-flow mode had a large equivalent stress in the PEN region and a small equivalent stress in the collector region,and the overall distribution of deformation displacement was a series of concentric circles centered on the symmetry center of SOFC.Appropriately increasing the inlet rate of the oxidizing gas on the cathode side would reduce the maximum equivalent stress value and the deformation displacement value of the fuel cell,the SOFC structure performance was better simultaneously.Increasing the intake air mole fraction of the fuel gas,or improving the operating temperature of the SOFC in a certain range,both of the maximum equivalent stress and the deformation displacement of the battery increased.Under the same working conditions,the equivalent stress and deformation displacement value of the three flow modes were different in the co-flow,counter-flow and cross-flow.The structural performance of SOFC was better when adopted the co-flow.Optimization of the size of the flow channal to improve the structural performance of the SOFC includes: If channel height and the number of channels were fixed,increase the air flow width;or in the case that channel height and the total amount of air flow were fixed,it was appropriate to increase the channel number;and if the channel width and channel number were fixed,it was appropriate to increase the channel height.The modeling and simulation in the thesis unified the electrochemical performance and thermal stress field of SOFC,optimized the operating parameters and flow field design of SOFC,provided a theoretical reference for further research and development in this field.