| Proton Exchange Membrane Fuel Cell(PEMFC)has the advantages of high efficiency,high reliability,low emission pollution,and light weight.It is very suitable for use as portable energy in the transportation field.The flow field in a PEMFC bipolar plate is the main place where reactants and products enter and exit.The flow channel structure plays a decisive role in the transport and distribution of reactants,and is a key factor affecting the performance of PEMFC.In addition to the significant impact of the flow path on the performance of PEMFC,the intake mode and operating conditions also have a significant impact on the performance of PEMFC.In order to design high-performance PEMFC,this paper uses numerical simulation to design and optimize the flow channel structure,and studies the impact of different intake methods and operating conditions on the performance of PEMFC,so that it has excellent comprehensive performance in terms of output power,gas distribution uniformity,and water distribution.Firstly,based on a single channel DC channel,a PEMFC with a bionic wavy channel shape was designed inspired by the streamlined shape of the bird’s abdomen.The wavy bosses in the flow path can change the size and direction of the airflow,promote forced convection,and allow more reactive gases to enter the gas diffusion layer to reach the catalytic layer for reaction,improving gas utilization.At the same time,the rear of the wave boss in the bionic wave shaped flow field is a slope,making the volume of the rear of the wave boss slowly increase.Therefore,the air flow reaching the rear of the wave boss will not drop rapidly due to the rapid expansion of the volume,causing less interference with the reaction gas,reducing the flow resistance,and ultimately reducing the pressure drop.Based on the maximum lifting ratio of the total power density,it is obtained that when the wave height is 0.6 mm and the number of wave periods is 5,the wave structure is optimal.Secondly,based on the advantages of the three-channel serpentine flow field,a basic three channel serpentine flow field model was established,and the intake method was changed to call the same side intake method a downstream strategy,while the diagonal side intake method a reverse flow strategy.Study the effect of air intake strategy on the performance of PEMFC.The countercurrent strategy can improve the ability of PEMFC’s self-humidification by promoting the transmission of net water flux within the membrane,making the water in the membrane more uniform,increasing the proton conductivity,and reducing the ohmic resistance.Finally,the output voltage at the same current density increases.Compared to the forward current strategy,at a current density of 1.4A/cm~2,the maximum output power density of the countercurrent strategy is increased by 2.07%.Finally,combining the bionic wave shaped flow channel with the three-channel snake shaped flow field to form a bionic wave shaped flow field to verify the applicability of the bionic wave shaped flow channel in the multi-channel situation.The addition of the bionic wave shaped flow channel further improves the performance of the three-channel snake shaped flow field.Compared to the basic three channel snake shaped flow field,the current density is 1.8A/cm~2,the total output power of the bionic wave shaped flow field increased by 1.645%;The effect of operating parameters on the performance of PEMFC in a bionic wavy flow field was studied.Under moderate intake humidity,the performance of PEMFC is higher,but with the increase of operating temperature,the performance of PEMFC decreases. |
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