Numerical Calculation And Optimal Design Of Flow Field In Proton Exchange Membrane Fuel Cell

Proton exchange membrane fuel cell(PEMFC)has the advantages of fast response speed,high volume power density,long service life,simple structure,reliable operation,no noise reaction to gas chemical conversion rate,and is not restricted by carnot cycle.In PEMFC,the flow field design achieves uniform reaction gas distribution,which can improve cell performance.This paper investigates the influence of flow-field structure on fuel cell performance by numerical simulation around proton exchange membrane fuel cell flow-field design and optimization.The effects of different flow path cross-sections on cell output performance,reactive gas distribution,flow rate and pressure drop were investigated using numerical simulation methods.The results show that the reactive gas concentration decreases with the direction of the flow channel and the trapezoidal cross section has the best reactive gas distribution and water removal efficiency.Furthermore,the semicircular cross-section has the highest pressure drop in other flow characteristics and the most uniform pressure distribution in the spaced convex cross-section,the trapezoidal cross-section has the best cell performance and good performance in mass transfer.The relationship between different parameters and fuel cell performance is investigated by numerical simulation based on the trapezoidal cross section for different top widths and flow channel to rib width ratios.As the width decreases the uniformity of the reaction gas distribution and the pressure drop gradually increases,the gas mass transfer capacity is best at the lower upper end of the trapezoidal width.Because the diffusion coefficient of hydrogen is much larger than oxygen,when the width ratio increases,the anode reaction gas is less affected,the uniformity of the cathode oxygen distribution decreases sharply,the lower the oxygen concentration in the subcostal area farther away from the flow path and the large accumulation of water,which seriously affects the battery performance.In order to improve the utilization of the reaction gas,the anode can be closed in order to improve the utilization of the reaction gas during the experiment and operation.A novel flow field based on reinforced subcostal mass transfer is proposed,and the effect of different exit heights on its performance is analyzed by simulation.When lowered to 0.25 mm,due to the low height of the end of the runner,it is difficult to remove water inside the runner,leading to flooding at the end of the channel,resulting in a sudden drop in cell performance and uniformity of the gas distribution.The pressure and pressure drop in the flow channel increases with the lowering of the outlet height,but too high a pressure drop will seriously affect the water removal rate and the uniformity of the distribution of the reaction gas.Moreover,the 0.5mm channel outlet height for best cell performance and uniformity of reaction gas distribution.In this paper,different cross-sectional shapes,different cross-sectional parameters and different exit heights of the new flow field are analyzed by numerical simulation methods to optimize the design of fuel cell flow field and a guide for the design and optimization of the flow field structure of proton exchange membrane fuel cell.