Steady state and dynamic performance of proton exchange membrane fuel cells (PEMFCs) under various

Steady state and dynamic performance of proton exchange membrane fuel cells (PEMFCs) under various operating conditions and load changes

Steady state and dynamic performance of proton exchange membrane fuel cells (PEMFCs) under various

Steady state and dynamic performance of proton exchange membrane fuel cells (PEMFCs) under various

JournalofPowerSources161(2006)

Steady state and dynamic performance of proton exchange membrane fuel cells (PEMFCs) under various

492–502

Steadystateanddynamicperformanceofprotonexchangemembranefuelcells(PEMFCs)undervariousoperatingconditionsandloadchanges

QianguYana, ,H.Toghianib,HeathCauseya

a

CenterforAdvancedVehicularSystems(CAVS),Box5405,MississippiStateUniversity,MS39762-5405,UnitedStatesbDaveC.SwalmSchoolofChemicalEngineering,Box9595,MississippiStateUniversity,MS39762,UnitedStates

Received21January2006;receivedinrevisedform13March2006;accepted28March2006

Availableonline5May2006

Abstract

Thesteady-stateperformanceandtransientresponseforH2/airpolymerelectrolytemembrane(PEM)fuelcellsareinvestigatedinbothsinglefuelcellandstackcon gurationsunderavarietyofloadingcyclesandoperatingconditions.Detailedexperimentalparametersarecontrolledandmeasuredunderwidelyvaryingoperatingconditions.Inadditiontopolarizationcurves,feedgas owrates,temperatures,pressuredrop,andrelativehumidityaremeasured.Performanceoffuelcellswasstudiedusingsteady-statepolarizationcurves,transientI–Vresponseandelectrochemicalimpedancespectroscopy(EIS)techniques.Differentfeedgashumidity,operatingtemperature,feedgasstoichiometry,airpressure,fuelcellsizeandgas owpatternswerefoundtoaffectboththesteadystateanddynamicresponseofthefuelcells.Itwasfoundthatthehumidityofcathodeinletgashadasigni canteffectonfuelcellperformance.Theexperimentalresultsshowedthatadecreaseinthecathodehumidityhasadetrimentaleffectonfuelcellsteadystateanddynamicperformance.Temperaturewasalsofoundtohaveasigni canteffectonthefuelcellperformancethroughitseffectonmembraneconductivityandwatertransportinthegasdiffusionlayer(GDL)andcatalystlayer.Thepolarizationcurvesofthefuelcellatdifferentoperatingtemperaturesshowedthatfuelcellperformancewasimprovedwithincreasingtemperaturefrom65to75 C.Theairstoichiometric owratealsoin uencedtheperformanceofthefuelcelldirectlybysupplyingoxygenandindirectlybyin uencingthehumidityofthemembraneandwater oodingincathodeside.Thefuelcellsteadystateanddynamicperformancealsoimprovedastheoperatingpressurewasincreasedfrom1to4atm.Basedontheexperimentalresults,boththesteadystateanddynamicresponseofthefuelcells(stack)wereanalyzed.Theseexperimentaldatawillprovideabaselineforvalidationoffuelcellmodels.©2006ElsevierB.V.Allrightsreserved.

Keywords:PEMFCs;Performance;Transientresponse;Variousconditions

1.Introduction

Fuelcellshaveattractedgreatattentioninrecentyearsasapromisingreplacementfortraditionalinternalcombustionenginesduetotheirhighpowerdensityandultra-lowemissions[1–3].Thoughsigni cantimprovementsinpolymerelectrolytemembrane(PEM)fuelcelltechnologyhasbeenachievedoverthepastdecade,theperformance,stability,reliability,andcostfortoday’sfuelcelltechnologyisnotsuf cienttoreplacetheinternalcombustionengine[4–6].Anumberoffundamentalproblemsmustbeovercometoimprovetheirperformanceandreducetheircost.Theobjectivesforfurtherdevelopmentoffuelcellsinclude:toidentifycriticalissues,suchaswhatarethe

Correspondingauthor.Tel.:+16623255906;fax:+16623255433.E-mailaddress:yan@cavs.msstate.edu(Q.Yan).

effectsofstart-up,shut-down,andtransientresponse;toiden-tifykeyparametersforfuelcellperformanceandexaminehowtooptimizestackandsystemdesign;andexamineperformanceunderextremeconditions,suchassub-freezingtemperatures.Itisimportanttostudythedynamicbehavioroffuelcellstoobtainstableperformanceundervariousoperatingconditions.Inparticular,knowledgeofthedynamicbehavioriscriticaltotheengineeringanddesignofthefuelcells,stacks,andsys-tems[7].Acontrolsystemisneededtoensurethatthe owrateandtemperatureoffuelandairarewithinprescribedlim-itsduringnormaloperationatvariableloads,aswellasduringsystemstart-upandshut-down.Dynamicbehavioristhemostimportantaspectoffuelcelloperationthatshouldbestudiedunderwideoperatingconditions.Thecontrol,design,andopti-mumoperationoffuelcellsrequireanunderstandingoftheirdynamicswhentherearechangesincurrent,voltage,orpower[8].Fuelcelldynamicresponseisveryimportant;unfortunately,

0378-7753/$–seefrontmatter©2006ElsevierB.V.Allrightsreserved.doi:10.1016/j.jpowsour.2006.03.077

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