Three-dimensional Simulation And Optimization Of Water And Thermal Management Of PEMFC

PEMFC is currently most popular,one of the most promising new energy vehicles,which has a low noise,almost zero pollution,high energy density advantages.Factors currently restrict the commercialization of PEMFC major cost,service life and performance,and Reasonable thermal management scheme can improve life and performance of PEMFC.Built a three-dimensional model of water and heat management,come to the following findings:1.A two-channel three-dimensional full battery simulation model was built,and the parameters in the models in a variety of literature were referenced and modified to compare with the experimental results,and the most accurate modified model was selected,which laid a theoretical foundation for the research on water and heat management.2.Based on the revised mathematical model,a three-dimensional six-channel serpentine flow field isotherm model is built,which mainly studies the distribution of liquid water in porous media.The following conclusions are drawn:in this flow field,the liquid water saturation at the outlet is greater than the liquid water saturation at the inlet,and the liquid water saturation under the ribs is higher than that under the flow channel.The distribution of oxygen concentration is opposite to that of the inlet area.In the outlet area,the lower part of the runner is higher than the lower part of the ribs.As the voltage decreases,the saturation of the liquid water increases,and its growth rate is the largest between 0.4V and 0.6V,and then it becomes flat.As the humidity of the intake air decreases,the saturation of the liquid water decreases significantly,and the oxygen concentration increases significantly.The porosity will affect the mass transfer process in the porous area.Porosity affects mass transfer resistance and ultimately leads to changes in liquid water saturation and oxygen concentration.When the porosity is greater than 0.6,the decrease of liquid water saturation under the rib becomes faster.The thinner the gas diffusion layer,the lower the saturation of the liquid water,which facilitates drainage and prevents the occurrence of‘water flooding’.3.Based on the revised mathematical model,a three-dimensional dual-channel full battery model with cooling water channels was built,and the influence of different flow rates and different cooling channel geometric designs on the performance of PEMFC was studied,and relevant optimization suggestions were put forward.The results show that the faster the flow rate,the smaller the difference between the membrane temperature of the fuel cell and the water content in the membrane,the higher the battery output performance and the greater the flow rate,the less obvious the change.The influence of different cooling channel cross-sectional shape design schemes on the battery performance was studied,and it was found that the design with rounded corners on the cross-section can achieve better cooling effect,and the rounded trapezoid can achieve the best battery performance.The influence of design schemes with different flow channels on the battery performance was studied.It was found that as the number of flow channels increases,the overall temperature of the battery decreases.However,when the number of flow channels is three,the most uniform temperature distribution and water content distribution in the membrane can be obtained.The battery output performance is the highest at this time.