Study On Water And Thermal Management Characteristics Of PEMFC

With the rapid development of modern social economy,the energy consumption is also rising,clean energy has attracted more and more attention.As a renewable clean energy,hydrogen energy has the characteristics of wide sources,high energy density,convenient storage and transportation,clean and pollution-free,which makes it the best choice at present.The advantages of proton exchange membrane fuel cell(PEMFC),which is not limited by Carnot cycle,high energy conversion rate and low operating temperature,make it have broad prospects in transportation.The performance of proton exchange membrane fuel cell is limited by many factors.The large amount of water and heat generated during the operation of the cell are interrelated and affect with each other.Reasonable water and thermal management is a necessary condition to improve the output performance of the cell.In this paper,a mathematical model of proton exchange membrane fuel cell was established.The accuracy of the model was verified by comparing the simulation results with the existing experimental results,and the mesh independence verification was carried out to determine the appropriate number of grids.The research work is as follows:Firstly,a microporous layer was inserted between the catalytic layer and gas diffusion layer of the cathode of a small U-channel cell.The effects of microporous layer contact angle,porosity and thickness on cell performance,liquid water and temperature distribution in the cell were investigated.It is found that the liquid water content of cathode increases with the increase of contact angle,porosity and thickness of microporous layer.As the accumulation of liquid water in cathode catalyst layer affects the reaction rate of the cell,the performance of the cell decreases with the increase of contact angle,porosity and thickness of microporous layer.The heat generated by the electrochemical reaction is related to the current density of the cell,so the temperature inside the membrane electrode decreases with the increase of the contact angle,porosity and thickness.Secondly,the effects of the contact angle,thickness and polymer volume fraction of the cathode catalytic layer on cell performance,liquid water and temperature distribution in membrane electrode were studied.It is found that the liquid water content of the cathode decreases with the increase of the contact angle of the catalytic layer,and increases with the increase of the thickness of the catalytic layer and the volume fraction of the polymer,but it does not change when the contact angle is greater than 100° and the volume fraction of the polymer is greater than 0.7.The cell performance increases with the increase of catalytic layer contact angle and polymer volume fraction.The change of catalytic layer thickness has little effect on cell performance.Finally,five cell models with different flow channel structures were established.By changing the structural parameters of microporous layer in the cell with serpentine flow channel,it was verified that the law in U-shaped flow field is also applicable in other flow fields.The effects of different flow channel structures on cell performance,liquid water and temperature distribution were compared and analyzed.It was found that the liquid water content and temperature distribution in the interdigital flow channel were least affected by microporous layer parameters,and the cell performance was the highest.