General Regulation Of Air Flow Distribution Characteristics Within Solid Oxide Fuel Cell Stacks

The solid oxide fuel cell(SOFC)is a promising power generation device due to its many favorable properties,including fuel flexibility,clean operation,compactness,high volumetric power,and density,and has become a focus of fuel cell research.In order to improve the working efficiency of fuel cells,researchers have carried out a lot of research work and proposed many methods to improve the work efficiency of SOFC stacks.However,almost all researchers are studying monolayers or conducting research on a specific stack.Although many new structures have been proposed to improve the working efficiency of cells,companies cannot choose a cell structure that suits their needs.In view of this phenomenon,the CFD model has been developed.Based on the plate SOFC of the German Jülich company,a three-dimensional large-scale modeling and analysis of the stack is carried out.The main research work are as follows:1.Through the analysis of the three-dimensional large-scale flow characteristics of two plate stacks designed by the German Jülich company,it is shown that even with the similar design of the stack structure,the reversed flow distribution between the cells of the stack may be obtained.The trend shows that there may be have key structural parameters that have an impact on stack.It is particularly important to obtain key influence factors through theory,numerical values,or even experimental means,and to obtain the general regulation of the key structural parameters and the internal flow distribution of the stack.2.For doubts in this paper,the actual work process are as possible as real in the model calculation process.The model is loaded with continuity,energy,momentum,composition,and quasi-electrochemical equations to study the work characteristics of the stack.Starting from the two stacks of U-shaped and Z-shaped stacks in the air flow path of the stack,the relationship between the pressure distribution characteristics,the flow resistance,and the fluid momentum,etc,and their influence on the stack are analyzed.The air flow characteristics of the stack were analyzed by changing the ratio of inlet and outlet sections of the same model,the diameter of the inlet and outlet manifolds,the cell number of the stacks,and the structure of the rib flow path and the intake and exhaust nodes of the cells.The position of the stack manifolds have a significant impact to the air flow characteristics.According to these analyses,the general regulation of air flow in a stack is proposed.This regulation does not depend on a specific stack structure and has universal applicability.This paper also uses the relevant knowledge of fluid mechanics to explain the physical laws of airflow in the stacks.3.Currently,there are very few reports on a planar stack with fuel/Air manifolds penetrated through plane zone and open outlet manifold features.Although a real model of the new structure has emerged,there has been a lack of theoretical research and the internal working characteristics of the stack.This paper research an 18-layer multiphysics model for this particular stack structure.By coupling "three passes and one reaction",the simulation of the numerical model is well completed.The flow and temperature distribution characteristics of this type of fuel cell stack design and its interaction with the structural characteristics are analyzed,and it is found that the flow characteristics completely match the general law of air flow in the stack proposed in this paper.Most of the conclusions obtained have very good help and reference value for practical experimental design of fuel cell stacks with these characteristics.4.Tubular solid oxide fuel cells(T-SOFCs)have advantages over other types of SOFCs in terms of structural sealability and structural stability.However,there are many unfavorable factors in cathode-supported SOFC stacks,and the anode-supported SOFC stack is extremely rare.This paper designs an anode-supported T-SOFC stack for this problem and analyzes the general air flow distribution characteristics within the stack.They are very useful for improving the performance of stacks and extending working life for anode-supported T-SOFC stacks.Through careful analysis of the 1in1 out and 2in2out-U stacks,a new type of stack structure has also been designed.The calculation results also show that compared with the above two traditional designs,the new design can greatly improve the air supply quality between the tubular cells and on the surface of each tubular cell,and the temperature gradient within the structure is the lowest.The research work of this paper provides detailed theoretical support for promoting the optimization of SOFC stack structure and improving the work efficiency of the stack,and it is great significance for practical application and practical guidance,laying an important foundation for further study of the working characteristics of the stack.