AnexperimentalinvestigationonthecriticalheatfluxenhancementbymechanicalvibrationinverticalroundtubeOriginalResearchArticle

Inordertogainanunderstandingoftherelationshipbetweencriticalheatflux(CHF)andflow-inducedvibration(FIV),anexperimentalinvestigationwascarriedoutwithverticalroundtubeattheatmosphere.Inthebothconditionofdeparturefromnucleateboiling(DNB)andtheliquidfilmdryout(LFD),CHFincreasesupto12.6%withvibrationintensity,representedbyvibrationalReynoldsnumber(Rev).CHFenhancementbytubevibrationseemstocomefromthereinforcedflowturbulentmixingandtheincrementofdepositionofdropletintotheliquidfilm.Basedontheexperimentalresults,anempiricalcorrelationisproposedforthepredictionofCHFenhancementratio.ThecorrelationpredictstheCHFenhancementratio(En)withreasonableaccuracy,withanaverageerrorrateof4.5and26.5%forRMS.VibrationisaneffectivemethodforheattransferenhancementaswellasCHF.Nonetheless,theriskofsystemfailurebyFIVhasmadeitverydifficulttotakeadvantageofvibrationinheattransferfacilities.Therefore,itisnecessarytofindoutoptimalfueldesignenhancingtheCHFbutpreventingFIVdamageinanacceptablevibrationrange.