Numerical Analysis Of Large Proton Exchange Membrane Fuel Cell Stack Based On CFD

Proton exchange membrane fuel cell(PEMFC)is a device that mainly uses hydrogen energy to generate electricity.Hydrogen can be converted into electricity through electrochemical reaction in the fuel cell,and no harmful gas is produced in this process.As long as there is enough hydrogen,there will be a steady stream of electricity generated.Proton exchange membrane fuel cells are considered one of the most promising technologies in the future.Multiple fuel cells can form a stack,which can meet the power of higher power appliances.it is the main form of work of fuel cells.Computational fluid dynamics(CFD)can accurately simulate the stack operation,which can reduce the cost of stack development.At present,the simulation research on stacks mainly focuses on small and medium-sized stacks with less than 200 single cells,and is less involved in large stacks.The manifold of the reactor is an important factor affecting the performance of the stack.In this paper,the influence of the manifold structure of a large stack composed of 300 cells on the parameters in the stack was studied by CFD technology.For large stacks,it is very difficult to simulate the model that the full physical field coupling with the present computer technology.Therefore,this paper will use the simplified method to simulate the stack.The main research contents are as follows:Firstly,a three-dimensional,multi-component,steady-state,isothermal proton exchange membrane fuel cell model with an area of 327.6cm2 was established.Ansys/Fluent fluid simulation software was used to simulate the performance parameters of the single cell.The single cell model is reliable by experimental comparison.The single cell in the stack is simplified as a porous medium,and the cathode side and anode side are considered as decoupled models.The porous media is compared with a single cell,and the viscous resistance coefficient and component source terms of the porous media are modified according to the data obtained from a single cell,so that the loss of the porous media in the stack is approximately equivalent to that of a single cell.Then a simplified stack model is established in which the single cell is replaced by porous medium,and the parameters of porous medium in the stack are modified according to the data obtained from the single cell.Using Ansys/Fluent software for electric pile of cathode and anode gas distribution system for CFD simulation of the pile the pressure drop,velocity,mass flow rate of each single cell and reactant concentration change data,through the analysis to study the different processing these data into the exhaust manifold,respectively,the width of the pile in the cathode side and anode side distribution uniformity.Finally,the U-shaped reactor and Z-shaped stack are established,and the influence of the current pattern on the gas distribution of the stack is studied.Based on the above simulation,the variation trend of the pressure drop,gas velocity and reactant concentration distribution in the stack with different manifold widths and different flow patterns is analyzed.Finally,the variation law of the stack parameters with the manifold width is obtained.A smaller inlet manifold is beneficial to the uniformity of the stack distribution.The optimal width of the exhaust manifold is within a certain range,and the U-shaped stack is more excellent in uniformity.The results can provide a good reference for the design of inlet and exhaust manifolds in large stacks.