전자기기의효과적인열관리를위한투명복사냉각메타물질제작

Abstract

현대사회에서전자장비는우리삶과뗄레야뗄수없는관계가되었다.스마트폰,스마트워치,야외전광판등수많은전자장비들이우리의삶을윤택하게하기위해사용되고있다.하지만지속적인전자장비사용과야외에서의전자장비사용은발열문제로이어진다.특히,태양광을투과하여디스플레이하는장비나태양광을이용하는태양전지와같은장비는발열문제가더심각하다.이러한열이외부로방출되지못하고내부에축적되면전자장비의성능감소와수명감소로결과가나타난다.현재방열연구는대부분후면의히트싱크로의열전도향상에초점이맞춰져있고,전면을통한방열연구는시작단계에있어불투명함과소재적한계성이라는단점이있다.본연구에서는이러한문제를해결하여투명하며장비의전면을통해효과적인방열을구현하기위해투명한복사냉각소재구현개념을도입하였다. 실제전자장비로의적용성을위해,투명하여전자장비의전면부에적용하여도본래의목적을해치지않고,복사냉각성능을가져전자장비후면부의추가적인복잡한설계없이전면부를통해에너지를소비하지않고냉각이가능한투명한복사냉각메타물질제작공정을개발하였다.먼저,대기의창(8-13m)에서높은방사율을가지는실리카에어로겔마이크로입자를사용하여방열성능을확보한다.그후,가시광변조소재를통해실리카에어로겔마이크로입자의나노기공을채워산란과반사을억제해투명성을보장한다.또한투명복사냉각메타물질은특정소재에제한되는것이아니라,모재에따라가시광변조소재를다르게설정할수있어기계적성질의다양성을가져갈수있다.결과적으로,장비가요구하는특성에맞는모재를선정후방열성능을부여하여전면방열할수있는새로운플랫폼을제시하였다. 그후,앞서제작한투명한복사냉각메타물질의실제전자장비로의적용가능성을검증하였다.솔라시뮬레이터를이용해이상적인태양광스펙트럼을가해준실내환경과자연태양광환경에서모두우수한태양전지의온도상승억제효과를확인하였다.또한이러한온도상승억제효과가실제태양전지의효율감소억제로이어질수있음을실험적으로검증하였다.또한발광다이오드칩과디스플레이의자체발열에만의한온도상승이있는실내환경과자연태양광에의한추가적인열원이있는야외환경에서모두우수한온도상승억제효과를확인하였다.또한이러한온도상승억제효과가실제발광다이오드의광추출전력감소억제로이어질수있음을실험적으로검증하였다. 본연구를통해,투명하며전면으로복사냉각이가능한메타물질에의해실제전자장비가효율적인온도상승억제효과를쟁취하고,이에따른효율감소억제효과도확인하였다.이렇게광특성조절을통해제작된메타물질은전자장비의전면부를통해효율적인냉각이가능하므로효율적인전자장비열관리의새로운패러다임을제시할수있다. |Abstract

FabricationofTransparentRadiativeCoolingMetamaterialsforEffectiveThermalManagementinElectronicDevices

KangWonLee DepartmentofMechanicalConvergenceEngineering GraduateSchoolofHanyangUniversity

Inthemodernsociety,electronicdevicesareinseparablefromourlives.Manyelectronicdevicessuchassmartphones,smartwatches,andoutdoordisplaysarebeingusedtoenrichourlives.However,continuousandoutdooruseofelectronicdevicesresultsinheatgenerationproblems.Inparticular,thethermalizationproblemismoreseverefordevicesthattransmitanddisplayoutdoorsordevicessuchassolarcellsthatusesunlight.Whensuchheatisnotreleasedtotheoutsideandaccumulatesinside,performancedegradationandshortageoflifetimeofelectronicdevicesoccur.Thereisalsoasurveyresultthatshowsthattheheatgenerationproblemofelectronicdevicesisthebiggestcauseofequipmentfailure.Inordertosolvethisproblem,researchonvariousheatdissipationmethodsofelectronicequipmentisbeingconducted.Moststudiesonheatdissipationfocusedonimprovingheatconductiontotheheatsinkontherearofdevices,andheatdissipationthroughthefrontofdeviceshasthedisadvantagesofopacityandmateriallimitationinthebeginningstage.Themethodthatimprovesheatconductionwithheatsinkonthebackofelectronicdevicesandreleasesheattotheoutsidebyconvectionisineffectiveduetothelowthermalconductivityofthematerial.Evenifthethermalconductivityofthematerialisimprovedthroughanexpensiveprocess,theequipmentisthickenedbyheatsink,soitisnotsuitableforthelatesttrendofthinningelectronicequipment.Tosolvethisproblem,thispaperintroducesatransparentradiativecoolingplatformtotransmitvisiblelightandimplementeffectiveheatdissipationthroughthefrontofdevices.Whentheheatdissipationmaybeperformedthroughthefrontsurfaceoftheelectronicdevicesthroughradiativecooling,anenergysourceofaseparateenergysourceisnotrequired,andthusitmaybeofgreathelpintermsofeco-friendliness.Transparentradiativecoolingmetamaterialsweredevelopedutilizinganewlydesignedopticalmodulatorinfiltratedintorandomlydistributedsilicaaerogelmicroparticlesinadesiredbasematerial.Theopticalmodulator,whichisdeterminedbythebasematerial,controlstherefractiveindex,ensuringtransparencyevenifalargeamountofinfraredradiationmaterials,suchassilicaaerogelmicroparticles,isloaded.Withthisprinciple,itistransparentandsimultaneouslyhasheatemissionperformance,anddependingonthebasematerial,ametamaterialthatcanbeformedfromasofttorigidstatecanbemanufactured.Visiblelightmodulationmaterialscanbediversifieddependingonthebasematerialwithdesiredproperties,notlimitedtoonematerial,andheatdissipationperformancecanbegivenbyapplyingthemtocoversofvariouselectronicdevices.Theresearchedmetamaterialsareeasilyapplicabletodevicessuchaslight-emitting-diodedisplayswithself-heatgenerationorsolarcellswithoutself-heatgeneration,andthisresearchconfirmedthatmetamaterialscansuppressthetemperatureincreaseofelectronicdevices.Metamaterialscansuppressthetemperatureincreaseofdeviceseveninanoutdoorenvironmentwithsolarirradiance,whichcanpreventadecreaseintheperformanceandefficiencyofdevices,therebyextendingthelifespanofelectronicdevices. Thisstudydevelopedaprocessoffabricatingtransparentradiativecoolingmetamaterialstomaximizeheatemissionpropertiestoabasematerialwithsuitablemechanicalpropertiesaccordingtothecharacteristicsrequiredbyeachelectronicdevicewhilemaintainingtransparency.Notonlycanthetemperaturebereducedsimplyinanidealindoorenvironment,buttheeffectofthetemperaturereductionisconfirmedevenoutdoorstoconfirmthehighapplicabilityofthemetamaterial.Byconfirminganexcellenttemperaturereductioneffecteveninanenvironmentthatisunfavorableforradiativecoolingduetohighhumidity,itisshownthatthemetamaterialcanexhibitheatdissipationperformanceeveninaharshenvironment.Metamaterialsmanufacturedbyadjustingtheopticalcharacteristicsinthismannercanbeappliedasnewplatformsfortheeffectivethermalmanagementofelectronicdevicesbecauseenergy-freecoolingispossiblethroughthefrontsideoftheelectronicdevices.