temperature dependence in transformer oil-based ferrofluid

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1、IntJThermophys(2011)32:795–806DOI10.1007/s10765-010-0895-5TemperatureDependenceofParticleSizeDistributioninTransformerOil-BasedFerrofluidArkadiuszJózefczak·TomaszHornowski·AndrzejSkumielReceived:31March2010/Accepted:20November2010/Publishedonline:7December2010©TheAuthor(s)2010.Thisarticleispublished

2、withopenaccessatSpringerlink.comAbstractThetemperaturedependenceoftheparticlesizedistribution(PSD)ofatransformeroil-basedferrofluidwasstudiedusinganultrasoundmethod.Themeasurementsoftheultrasoundvelocityandattenuationwerecarriedoutintheabsenceofanexternalmagneticfieldasafunctionofthevolumeconcentrat

3、ionofmagnetiteparticlesattemperaturesrangingfrom10◦Cto80◦C.TheexperimentalresultsofultrasoundmeasurementswereanalyzedwithintheframeworkoftheVinog-radov–Isakovichtheorywhichtakesintoaccountcontributionstoacousticalparame-tersduetofrictionandheatexchangebetweenmagneticparticlesandthesurroundingcarrie

4、rliquid.Fromthebestfitoftheexperimentalresultsandtheoreticalpredictions,theparameterscharacterizingthePSDatdifferenttemperaturesweredetermined.Inordertoanalyzeultrasonicdata,thedensityandviscosityofferrofluidsamplesandthetransformeroilwerealsomeasured.KeywordsMagneticfluid·Nanoparticles·Particlesized

5、istribution·Velocityandabsorptionofultrasound1IntroductionFerrofluidsarecolloidalsuspensionsofnano-sizedmagneticparticlesdispersedinacarrierliquidandstabilizedbythesurfactantlayerthatproducesentropic(steric)repulsionpreventingagglomerationofparticles.Ferrofluidsexhibitspecialpropertiesthatmakethemsui

6、tedformanytechnicalapplications.ExperimentalresearchisnowfocusedonusingmagneticparticlesofnanometersizetoimprovethethermalandA.Józefczak(B)·T.Hornowski·A.SkumielInstituteofAcoustics,FacultyofPhysics,AdamMickiewiczUniversity,Umultowska85,61-614Pozna´n,Polande-mail:aras@amu.edu.pl123796IntJThermophy

7、s(2011)32:795–806dielectricpropertiesoftransformeroils.Typically,transformersoilshavealowther-malconductivity,andthereforetheyexhibitratherpoorcoolingbehavior.Toimproveremovalofheatgeneratedbythelargepowert