| Proton Exchange Membrane Fuel Cell(PEMFC)has the advantages of high efficiency,safety,simple structure,clean and environmentally friendly.It is an ideal way of hydrogen energy utilization,which has broad market prospects and high research value.The flow channel of a PEM fuel cell is the path through which reactants enter and reaction products discharge.It directly determines the reactant transfer and distribution and is a key factor affecting fuel cell performance.In order to develop a high-performance PEM fuel cell,this thesis combines numerical simulation and genetic algorithm to cleverly design and optimize the flow channel structure for the fuel cell,including the shape of the flow channel and the arrangement of the flow field,so that it can show an excellent comprehensive performance at output power,flow power consumption,uniformity of current density distribution and water discharge.First,inspired by the fins of cuttlefish,this thesis designs a PEM fuel cell with a bio-inspired wave-like flow channel shape.The wavy blocks in the flow channel can change the magnitude and direction of the gas velocity,enhance the mass transfer of the reactants to the diffusion layer,accelerate the reaction rate,and increase the output power.At the same time,the bio-inspired wave-like structure reserves sufficient flow area on the two sides of the flow channel,which reduces interference with gas flow.Therefore,it has a lower flow resistance,causing lower power consumption.The genetic algorithm is used to optimize the waveform of the bio-inspired wave-like channel,and the results show that when the center amplitude and the number of wave cycles are 0.305 mm and 3.52,respectively,the fuel cell achieves the best comprehensive performance.Secondly,the flow channel structure of PEM fuel cell with a parallel flow field is optimized,and the width and interval of each flow channel are rearranged.In the optimization model,the flow velocity distribution in each flow channel is more uniform,and the relationship between flow distribution and resistance characteristics is more balanced,therefore the reaction gas flows more smoothly and is more thoroughly consumed.When at the operating voltage of 0.5V,compared with the basic model,the output power of the optimized model is increased by 2.19%,and the flow power consumption is reduced by 10.29%.Finally,a new three-dimensional flow field PEM fuel cell is designed to improve the mass transfer performance of the fuel cell.In the three-dimensional flow field,the fluid velocity is accelerated,beneficial to the transport of reactants and the increase of the reaction rate,and also the water drainage performance is enhanced.The fluid in the three-dimensional flow field is repeatedly mixed and redistributed,which improves the uniformity of the fuel cell current density distribution.When the operating voltage is0.5V,0.45 V,and 0.4V,the output performance of the three-dimensional flow field model is improved by 9.95%,12.07%,and 13.94%,respectively,compared to the parallel flow field model. |
