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圆柱形壳体内牛顿型纳米流体的自然对流传热的实验研究（英文）.docx

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圆柱形壳体内牛顿型纳米流体的自然对流传热的实验研究（英文） ExperimentalStudyonNaturalConvectionHeatTransferofNewtonianNanofluidsInsideaCylindricalShell Introduction Theutilizationofnanofluids,whichareengineeredcolloidalsuspensionsofnanoparticlesandbasefluids,hasshownpromisingresultsinenhancingtheheattransferpropertiesoftraditionalcoolantfluids.Thehighthermalconductivityofnanoparticlesinnanofluidsisbelievedtoincreasetheheattransferbetweenthefluidandheattransfersurfaces,makingthemapromisingcandidateforfutureenergyapplications.ThisstudypresentsanexperimentalinvestigationofnaturalconvectionheattransferinacylindricalshellfilledwithaNewtoniannanofluid. ExperimentalSetup TheexperimentalsetupconsistsofacylindricalshellfilledwithaNewtoniannanofluid,whichisexposedtoasteadyheatfluxsuppliedbyanelectricheater.Thenanofluidusedwasamixtureofdistilledwaterandcopperoxidenanoparticleswithanominalparticlesizeof36nm.Thevolumefractionofnanoparticlesinthenanofluidwassetat0.2%.Thecylindricalshellwasmadeoftransparentacrylicmaterialwithaninnerdiameterof80mmandalengthof200mm.Theelectricheaterwaslocatedatthebottomofthecylindricalshell,andathermocouplewasplacednearthetoptomeasurethetemperaturedistributionofthenanofluid. ExperimentalProcedure Theexperimentwasconductedinacontrolledlaboratoryenvironmentwiththetemperatureandhumiditykeptconstant.Thenanofluidwascirculatedusingapumptopromotenaturalconvection.Acamerawasusedtocapturethetemperaturedistributionofthenanofluid,andimageprocessingtechniqueswereutilizedtoanalyzethedata.Theeffectsofheatfluxandvolumefractionofnanoparticlesonnaturalconvectionheattransferwereinvestigated,andtheresultswerecomparedwiththepredictionsofexistingcorrelations. ResultsandDiscussion Theresultsshowedthattheconvectiveheattransfercoefficientofthenanofluidincreasedwithanincreaseinheatfluxandvolumefractionofnanoparticles.Thethermalboundarylayerthicknessdecreasedwithanincreaseinheatflux,indicatinganincreaseintherateofheattransfer.Themaximumenhancementofheattransferwasobservedatavolumefractionof0.2%andaheatf