Design And Optimization Of Flow Field Structure Of Harp Bipolar Plate In Hydrogen PEMFC

Proton exchange membrane fuel cell has been widely used in special power sources because of its characteristics of simple design and operation,rapid start-up,low-temperature operation,high power density and zero pollutant emission.Proton exchange membrane fuel cell generates lowvoltage DC through electrochemical reaction,and high-power supply can be realized by series and parallel connection of single fuel cell.With the mature development of fuel cell technology,proton exchange membrane fuel cell can be applied to portable power supply,automotive power system,distributed generation system and so on.The properties of bipolar plate in proton exchange membrane fuel cell have a great impact on the performance of the cell.High conductivity,high mechanical strength,corrosion resistance and good air tightness are the necessary conditions that bipolar plate needs to meet.The design and optimization of bipolar plate flow field is the key to meet the performance of fuel cell.The flow field can determine the flow characteristics of fuel and oxidant,affect the current density distribution of fuel cell,the distribution of humidified water and water produced by electrochemical reaction,electrochemical heat distribution,etc.,and then directly affect the performance of proton exchange membrane fuel cell.Because the material concentration,temperature and pressure in the fuel cell can not be analyzed through experiments,this paper uses numerical simulation to study the internal state of the fuel cell.Firstly,this paper summarizes the corresponding performance of traditional flow field,combined flow field and new bionic flow field in proton exchange membrane hydrogen fuel cell,and analyzes the advantages and disadvantages of different flow fields.In order to establish the mathematical model of hydrogen fuel cell,the conservation equation and electrochemical theory are introduced.Then,the mathematical model of proton exchange membrane fuel cell based on serpentine and parallel flow field is established,the electrochemical parameters and boundary operating conditions are set,and the CFD software COMSOL multiphysics is used to couple the physical fields such as heat,electricity and material transfer in proton exchange membrane fuel cell to simulate and analyze the concentration of reactants and products in the traditional flow field Temperature distribution and polarization curve.Secondly,in order to explore the influence of bionic flow field on the performance of proton exchange membrane fuel cell,a harp sponge shaped harp flow field is designed based on the bionic configuration principle and symmetry principle.The optimal channel parameters of harp flow field are obtained by studying the influence of channel height and ridge width on the performance of proton exchange membrane fuel cell.The effects of the differences in material concentration distribution,current density distribution,temperature distribution,drainage,pressure drop and polarization curve between proton exchange membrane fuel cells based on bionic flow field and traditional flow field on fuel cells are compared and analyzed.The polarization curve shows that at low current density,the design of different flow fields has little impact on the performance of fuel cells,but at high current density,it is concluded that the harp flow field can obtain better performance than the traditional flow field.Finally,in view of the common limitations of bionic flow field,this paper studies the influence of fractal series on the performance of harp flow field proton exchange membrane fuel cell,and comes to the conclusion that the performance of harp flow field proton exchange membrane fuel cell is better when the fractal series is less.Because with the increase of active area,the complex structure of bionic flow field will bring the loss of pressure drop and flooding,which will reduce the performance of hydrogen fuel cell.Finally,the paper briefly introduces the gas supply system,hydrothermal management system,humidification system,voltage detection system and power conversion system of proton exchange membrane fuel cell.