Effect Of Structure And Operating Parameters Of Double-Headed Snake-Like Flow Field On Performance Of Hydrogen Fuel Cell

Since the Industrial Revolution,the massive exploitation and utilization of traditional energy such as fossil energy,energy exhaustion and environmental pollution have become two major problems facing the world today.Hydrogen fuel cells convert chemical energy directly into electrical energy and are generally considered as an excellent alternative to traditional energy because of their advantages such as high energy conversion efficiency,low noise in operating conditions and pollution-free reaction products.At present,hydrogen fuel cell has been paid enough attention in the automotive field,which has greatly improved the problems of slow charging speed,low safety performance and great influence on temperature of current lithium-ion battery vehicles.However,due to its insufficient output performance and other defects in the application of passenger cars,its widespread application has been hindered to some extent.In this paper,based on the model of a hydrogen fuel cell with double-head serpentine flow field,the influence of material distribution and geometry structure and different conditions(pressure,humidification rate,porosity of diffusion layer)on the outp ut performance of the cell under different output voltage was studied.The main contents of this paper are as follows: Firstly,based on the basic control equation of fuel cell fluid mechanics,fuel cell dynamics and thermodynamics theory,a steady-state calculation model of double-head serpentine flow field single fuel cell was established in COMSOL,and the physical parameters and boundary conditions were defined.Secondly,physical field settings were carried out,including secondary current distribution,dense material transfer,solid and fluid heat transfer,etc.Coupling solutions were carried out to calculate the distribution of fuel,oxidizer,water content and the current density when the battery was running at different voltages to verify the accuracy of the simulation model.Then,based on the relevant Design rules and fluid dynamics simulation results of response surface analysis in Design-Expert,a response surface analysis model was established for the relationship between structural parameters and output characteristics of the fuel cell with double snake-like flow field,taking the flow depth,flow width and fillet radius as test factors and the average current density as output results.Finally,the influence of working pressure,humidification rate and porosity of the diffusion layer on the performance of the battery was studied successively,and the influence rule of different parameters on the battery was obtained by comparing the material distribution cloud diagram and output polarization curve under different conditions.The results show that:(1)When the output voltage drops from 0.6V to 0.4V,the consumption and water content of the reactants in the battery gradually increase,and with the progress of the reaction,the current density increases,and the uneven distribution of the reactants increases.The established model has a certain accuracy.(2)The P-value of the model in the regression equation ANOVA table is 0.002,which proves that the regression equation has a good fitting ability and can be used for model prediction.The actual value and predicted value of R-Squared are 0.9256 and 0.7358 respectively,which are in good agreement with each other.The influence of the three factors on the average current density is as follows: channel depth > channel width > fillet radius.The optimized parameters are as follows: the width of the flow passage is 1.1mm,the depth of the flow passage is 0.6mm,and the fillet radius is1.1mm.(3)When the battery temperature is 60℃,the anode humidification rate is 100%,the cathode humidification rate is 60%,and the operating pressure is 1-2atm,the performance of the battery is obviously improved with the increase of the pressure.When the temperature of the battery is 60℃,the relative humidity of the anode is 100%,the operating pressure is 1atm,and the relative humidity of the cathode is 60%-80%,the performance of the battery is better with the increase of the humidification rate of the cathode,but the increase of the performance decreases and the increase of the moisture content of the gas leads to the increase of liquid water,blocking the flow path of the reaction gas,and the reaction rate decreases.Under the same parameter setting conditions,the mass transfer effect of the battery increases with the increase of the porosity of the diffusion layer,and the increase of the porosity of the diffusion layer can optimize the performance of the battery.