Research On The Momentum,Heat,Species,and Electrochemistry Coupling Processes Within The Proton Exchange Membrane Fuel Cell Optimization Design

Proton Exchange Membrane Fuel Cell(PEMFC)has gradually become an important terminal of hydrogen energy application industry in contemporary energy structure after a long period of development.Although hydrogen energy has not been widely promoted at present,the application design of proton exchange membrane fuel cell has spread to all aspects of electric energy application,so the requirements for its performance are increasing day by day.Among them,proton exchange membrane fuel cell,including flow field design,air intake management and pressure drop control,affects the distribution,drainage and heat transfer of reactants in fuel cell.Good flow field structure design can improve fuel efficiency,increase temperature and material distribution uniformity,and design of gas supply strategy for specific flow field can also affect the final performance.Thus,optimization design is always in an important position in the research of proton exchange membrane fuel cell.In the past few decades,the research methods of proton exchange membrane fuel cell mainly rely on the physical production and experimental measurement.In recent years,with the great improvement of computer computing power and the gradual maturity of commercial CFD software,the multi-physical field coupling simulation research method has become an important research method of proton exchange membrane fuel cell.In general fuel cell experiments,when studying the flow or mass transfer distribution of the cell,most of the internal flow characteristics are inferred through indirect measurement of various flow or temperature parameters.When using the numerical simulation method to study the proton exchange membrane fuel cell,the flow field distribution can be obtained intuitively and visualized from the simulation results,and various parameters statistics can be easily carried out through the post-processing.Numerical methods usually cost less than experimental methods and are more flexible and convenient,which has unique advantages of saving time and cost under the research requirements of diversified proton exchange membrane fuel cells today.Although the theory related to fuel cell numerical simulation is gradually improved,there are still many uncertainties in the actual use stage.One of the research emphases of this thesis is the analysis and research of the modular simulation theory of proton exchange membrane fuel cell,including: From the physical model to the real proton exchange membrane fuel cell mapping,mathematical model selection and multi-physical field coupling adjustment,as well as some of the use of parameters adjustment and discussion.Based on the above discussion,the numerical simulation results of the single-channel serpentine flow field were finally compared with the experimental results of literatures with experimental data to verify the correctness of the simulation research and adjustment of the proton exchange membrane fuel cell.The second research focus of this thesis is to comprehensively analyze the existing research results on the optimization design of proton exchange membrane fuel cell.It is concluded that excellent PEMFC should take into account the characteristics of material uniformity,low pressure loss and enhanced terminal drainage while ensuring high performance.According to the above requirements,two key points of optimization are summarized: cross-rib-rib flow and diverting and confluence characteristics.Then,three kinds of single-layer flow fields of proton exchange membrane fuel cell were designed according to the characteristics summarized in this thesis.Then,they were simulated by the numerical method verified above.Finally,the characteristics of the above good flow fields were analyzed for the three optimal flow fields.The results show that the optimized fuel cell design has its advantages and disadvantages in the above criteria,among which the PEMFC with serial enhanced flow field design has the best comprehensive performance,but it has some shortcomings in performance.By changing the strategy of diverging air intake and supply,the performance is improved and the liquid water content in porous media is further reduced under the condition of slightly increasing pressure drop.Thus,the comprehensive simulation results show that this kind of multi-inlet optimization design,which breaks the material linear variation,can enhance the end drainage under low pressure drop conditions,and the performance can be further improved by changing the shunt intake ratio.