Study On Pressure Drop And Hydrogen Utilization Of Proton Exchange Membrane Fuel Cell

The water management is the main factor affecting its operating performance and life in Proton Exchange Membrane Fuel Cell?PEMFC?.And it can reduce the effect of flooding and keep the balance of water management on PEMFC.In recent years,the problems of cathode flooding and anode water shortage have been effectively solved during the processing of researching about PEMFC on vehicles.However,the problems of anode flooding and coupling mechanism between parameters have been ignored.In this paper,we establish a water transfer model on basis of the calculation formula of mass conservation and water vapor properties in PEMFC.Furthermore,we use this model to clarify the water transfer mechanism inside the anode,and it can be verified by testing of symmetrical humidification and asymmetrical humidification.Firstly,we propose models of relative humidity-pressure drop?RHPD?and hydrogen utilization coefficient?HUC?.Considering the influence of related parameters such as net migration coefficient and water permeability,we derive the calculation formula for anode pressure drop and the hydrogen utilization coefficient.Secondly,we set up a fuel cell test system.And we propose an optimization scheme for the flow channel and make a comparative analysis.Thirdly,we set up 3D models of serpentine and straight channel and then obtain the simulation parameters and internal component contours of PEMFC using the software of fluid mechanics such as Gambit and Fluent.Finally,the change law of anode pressure drop is obtained by analyzing the effect of relative humidity on anode pressure.The changes of internal pressure,water content and hydrogen content of PEMFC channel under different relative humidity are discussed combined with the internal component distribution contours.And we explore the variation of hydrogen utilization coefficient under different relative humidity and propose a novel control strategy for optimizing the utilization coefficient of hydrogen.The results shown that:1)During the loading processing,the anode pressure drop always show law of change which have three stages.The pressure drop curve shifts downward as a whole as the anode relative humidity increases.2)During the loading processing,the growth coefficient of hydrogen utilization changes slowly with the increasing of anode relative humidity.3)The current density is 100 mA cm^-2 which is the inflection point of the growth rate.Based on the inflection point,we propose a novel control strategy for optimizing hydrogen utilization coefficient and verified by experiments:when the anode relative humidity is 75%,the cathode relative humidity is 25%,and the current density is 491.989 mA cm^-2.The maximum value of hydrogen utilization is 93.867%,and the optimization coefficient of Hydrogen utilization is 1.806%.