Study On Limiting High Voltage Of Water Cooled Proton Exchange Membrane Fuel Cell

As the advantages of high power density,low noise,low working temperature,high starting speed,high energy efficiency,superior dynamic performance and environment friendly,Proton Exchange Membrane Fuel Cell(PEMFC)has aroused wide concern,and is an important direction of furture new energy applications.With PEMFC rapidly developed and gradually commercialized,the performance and lifetime of PEMFC stack hinders its large-scale application.There are many factors that affect the performance and lifetime of the stack,and the high voltage during the operation of the stack is main factor causing the stack performance degradation.In the presence of high voltage,the carbon carrier material is easily oxidized to generate CO2,CO and other gases,which weakens the adhesion of Pt particles and carbon carrier,leading to Pt particles to break off.Finally,the Pt particles are dissolved in the electrolyte,which seriously affacts the catalytic performance of the membrane electrode.Therefore,it is significant to study the high voltage during the operation of high-power water-cooled fuel cell to prolong the sevice lifetime.Firstly,based on the stable operation of high-power water-cooled fuel cell required auxiliary environment,a multi-functional PEMFC test platform was designed and built,and the structure of the platform system and selection of the key equipment were introduced in detail.According to the stack start-up,automatic operation and shutdown process,and on basis of USB7635BD data acquisition card and LabVIEW,the PC control software of the test platform was designed.And various operational parameters required by test can be set on the PC,also the running state of stack can be real-time monitored.Secondly,the start-up and shutdown conditions were studied in detail during which the high voltage most likely existed,and the primary cause of stack performance degradation caused by start-up and shutdown was analyzed.Besides,the experiment study on start-up and shutdown of high-power water-cooled fuel cell was presented,then the start-up and shutdown strategy was proposed to limit the occurrence of high voltage and greatly reduce the damage to stack during start-up and shutdown.Finally,in view of the high voltage of the high-power water-cooled fuel cell system during a series complete operating conditions and uniform consumption of residual gas during shutdown,this paper put forward a new method to put a hot wire in cooling water branch tank as protective resistance.The control strategy can make the stack pass high voltage phase quickly.Besides the residual gas can be consumed quickly and uniformly at shutdown time,thus the amount of downtime reduces.Because of avoiding the high voltage during the operation,the low-load operation time increases significantly,and the number of unnecessary start-up and shutdown reduces.In case of auxiliary equipment of fuel cell vehicle system has been very redundant,the study can easily and effectively solve the problem with stack running,and has important guiding significance for the practical application of fuel cell.