Effect Of Extended Flow Channel On Mass Transfer And Performance Of Proton Exchange Membrane Fuel Cell

Energy is the foundation of modern society development and an important driving force for economic growth.Hydrogen,as a renewable and clean energy source,has the advantages of wide availability,high energy density,convenient storage and transportation,and no pollution,making it one of the best choices at present.Proton exchange membrane fuel cell is a device that directly converts chemical energy into electrical energy.It is not limited by Carnot cycle,and has higher efficiency and power density than traditional internal combustion engine,and only produces water,which is environmentally friendly.These characteristics make it widely concerned and have broad application prospects.In order to ensure the stable operation of proton exchange membrane fuel cells,the electrodes must obtain sufficient reaction gas everywhere and timely discharge the accumulated water in the cell.Improving the flow channel structure is an effective way to improve the mass transfer performance of proton exchange membrane fuel cells.This paper designs an expanded flow channel and studies proton exchange membrane fuel cells based on numerical simulation.The main work of this paper is as follows:Initially,a mathematical model based on proton exchange membrane fuel cell is established,and the simulation results are compared and analyzed with existing experimental results to verify the model’s reliability.Furthermore,the appropriate number of grids is determined through grid independence verification.Then,an expanded channel is designed to induce disturbance and lateral diffusion of the fuel flow,and the effects of the number and size of expanded channels on the performance of single straight channel cells are investigated.Numerical results indicate that the expanded channels enhance the uniformity of oxygen distribution in the flow field reduce the pressure loss,and have higher liquid water concentration and drainage performance than traditional flow fields,and the mass transfer effect is effectively improved;secondly,increasing the expanded channels makes the reaction gas flow in the direction of channel width,enhances the diffusion of reaction gas in the channel,and reduces the impact of concentration polarization on performance.Therefore,under similar expansion areas,increasing the number of expansion channels can improve output power,and selecting larger expansion channels can achieve lower pressure loss.Finally,the geometric structure of the expanded channel is arranged on the serpentine channel,and the effect of the expanded channel in different flow sections is examined.The simulation results show that when using full expansion channel arrangement,compared with conventional flow field,the net power of cell increased by 10.5%.By comparing the expansion channels arranged at different positions of serpentine channel,it is found that arranging expansion channels at rear of flow field had more obvious effect,which could make reactants,water and temperature distribution in cell more uniform while improving output efficiency.