| Proton exchange membrane fuel cell(PEMFC)is a device that uses hydrogen and oxygen to generate electricity by electrochemical reaction.It has the characteristics of high efficiency,high reliability and no pollution.It is widely used in automobiles,ships and aerospace fields.As the core component of the fuel cell,the bipolar plate has the functions of supporting the membrane electrode,fluid distribution,cooling and heat dissipation,and its flow field design directly affects the heat and mass transfer performance of the battery.When the traditional flow field operates at high current density,there are often problems such as poor mass transfer effect,flooding and uneven temperature distribution,which lead to the decline of the power generation performance of the battery.In this paper,a new M-shaped flow channel is proposed,a mathematical model of the new M-shaped flow field is established,and its influence on the performance of the fuel cell is studied through numerical simulation and experimental analysis.Based on the principle of thermodynamic entropy increase,the optimal design of the fuel cell flow field was carried out,and a new type of M-shaped flow channel was proposed.A new Mshaped flow field mathematical model is established,and through numerical simulation calculation,the mass transfer effect and power generation performance of the new M-shaped flow field and the traditional flow field are compared and studied.The results show that the entropy of the new Mshaped flow field increases,and the mass transfer efficiency,oxygen distribution,drainage and power generation are improved.The maximum power densities of the M-shaped serpentine flow field and the M-shaped parallel flow field are 0.74(2/(88)and 0.73(2/(88),respectively.Through numerical simulation analysis,the structural parameters of the M-shaped flow field are optimized.The effects of different heights,widths and spacings of obstacles on the power generation performance,oxygen distribution,liquid water distribution,velocity and pressure drop of the flow field were studied.The results show that in the M-shaped serpentine flow field,the reduction of the height,width and spacing of obstacles is beneficial to the improvement of the comprehensive performance of the M-shaped serpentine flow field.Hour M-shaped parallel flow field performance is better.When the height is 0.2mm,the width is 0.1mm,and the spacing is0.1mm,the M-shaped serpentine flow field shows better performance,and the maximum power density is 0.8(2/(88).In the M-shaped parallel flow field,the obstacle has the best performance when the height is 0.4mm,the width is 0.2mm,and the spacing is 0.2mm,and the power density is0.79(2/(88).The M-shaped parallel flow field,the wave-shaped flow field and the traditional parallel flow field are tested and compared and analyzed to study the power generation performance of different flow fields under different working conditions.The test results show that the M-shaped parallel flow field has the best power generation performance when the temperature is 70 °C,the relative humidity is 1,the anode excess coefficient is 1.5,and the cathode excess coefficient is 2.5.At the same time,the reaction gas consumption experiment and the operation stability experiment were carried out on the above flow field.The results show that under the same power density,the Mshaped parallel flow field reaction gas consumption is the lowest,saving 24% of hydrogen and 25%of oxygen,respectively.In the galvanostatic current density stability experiment,the M-shaped parallel flow field maintains stable operation. |
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