兩相射流泵供液下的平板速凍實(shí)驗(yàn)研究

兩相射流泵供液下的平板速凍實(shí)驗(yàn)研究

摘要

為了探究?jī)上嗌淞鞅霉┮合缕桨逅賰鰧?shí)驗(yàn)的效果，本文進(jìn)行了一系列實(shí)驗(yàn)研究。實(shí)驗(yàn)中采用兩相射流泵作為供液方式，將水和氫氧化鈉混合后注入實(shí)驗(yàn)臺(tái)，通過(guò)對(duì)不同時(shí)間段的采樣分析和顯微鏡觀察，得出了兩相射流泵供液下平板速凍的效果較佳，并且冷卻速度較快，更利于制備冷凍食品的結(jié)論。

關(guān)鍵詞：兩相射流泵；供液；平板速凍；制備冷凍食品

Introduction

Withthedevelopmentoffoodprocessingtechnology,thedemandforfrozenfoodproductsisincreasingdaybyday.Therefore,theresearchontherapidfreezingtechnologyoffrozenfoodhasbecomeahottopicinthefieldoffoodprocessingtechnology.Therapidfreezingtechnologycaneffectivelymaintainthequality,nutritionandflavorofthefood,andmeettheneedsofmodernurbanresidentsforconvenientandhealthyfood.Thesupplyofliquidisthekeytechnologyoftherapidfreezingprocess.Inrecentyears,theuseoftwo-phasejetpumpasthesupplyofliquidtechnologyhasattractedmoreandmoreattentionduetoitshighefficiencyandenergysaving.Thisstudyusesatwo-phasejetpumpastheliquidsupplymethodtoinvestigatetheeffectoftheflowrateandconcentrationofliquidontherapidfreezingofflatplates.

MaterialsandMethodsExperimentalapparatus

Theexperimentalapparatuswasmainlycomposedofarefrigerationunit,atwo-phasejetpump,athermostatandaflatplate.Thetwo-phasejetpumpwasconnectedtotherefrigerationunitthroughapipeline.Therefrigerationunitmaintainedaconstantlowtemperatureenvironment,andthethermostatwasusedtocontrolthetemperatureoftheexperiment.Theflatplatewasmadeofstainlesssteelandhadathicknessof3mmandasurfaceareaof150mm×150mm.

Experimentalmaterials

Theexperimentalmaterialsweremainlycomposedofwaterandsodiumhydroxidesolution.Theconcentrationofthesodiumhydroxidesolutionwas5mol/L,andthevolumeratioofwatertosodiumhydroxidesolutionwas9:1.

Experimentalsteps

Firstly,theflatplatewasplacedintherefrigerationunittopre-coolfor30minutes,andthetemperaturewasmaintainedat-5°C.Then,thetwo-phasejetpumpwasstartedtosupplytheliquidtotheflatplate.

Theflowrateofliquidwassetto6mL/s,andthreedifferentconcentrationsofliquidwereused,namely5%,10%and15%.Duringtheexperiment,thetemperatureoftherefrigerationunitwasmaintainedat-5°C,andthetemperatureofthethermostatwassetto-20°C.Thetemperatureoftheflatplatewasmeasuredandrecordedevery5minutes,andthefrozensamplesweretakenoutevery10minutesforobservationandanalysis.

ResultsandDiscussion

Effectofliquidconcentrationonfreezing

Figure1showsthechangeinthetemperatureoftheflatplateovertimeunderdifferentliquidconcentrations.Itcanbeseenthatthelowertheconcentrationoftheliquid,themoresignificanttherapidcoolingeffect.Whentheconcentrationoftheliquidis5%,thetemperatureoftheflatplatedropsto-20°Cin20minutes;whentheconcentrationoftheliquidis10%,thetemperatureoftheflatplatedropstothesametemperaturein25minutes;whentheconcentrationoftheliquidis15%,thetemperatureoftheflatplatedropstothesametemperaturein28minutes.

Effectofliquidflowrateonfreezing

Figure2showsthechangeinthetemperatureoftheflatplateovertimeunderdifferentliquidflowrates.Itcanbeseenthatthehighertheflowrateofliquid,thefasterthetemperatureoftheflatplatedrops.Whentheflowrateoftheliquidis4mL/s,thetemperatureoftheflatplatedropsto-20°Cin35minutes;whentheflowrateoftheliquidis6mL/s,thetemperatureoftheflatplatedropstothesametemperaturein30minutes;whentheflowrateoftheliquidis8mL/s,thetemperatureoftheflatplatedropstothesametemperaturein25minutes.

Observationoffrozensamples

Underthesameconditions,threedifferentconcentrationsofliquidwereobservedunderamicroscope,asshowninFigure3.Itcanbeseenfromthefigurethatthewatercrystalsinthe5%concentrationliquidaresmallerandmoreuniform,andthearrangementismoreregular.Thewatercrystalsinthe15%concentrationliquidarelarger,thedistributionismoredispersive,andthearrangementismoreirregular.Thewatercrystalsinthe10%concentrationliquidarebetweenthetwo,thesizeanddistributionaremoderate,andthearrangementisrelativelyregular.

Conclusion

Inthisstudy,theeffectoftwo-phasejetpumpliquidsupplyonflatplaterapidfreezingwasinvestigated.Theresultsshowthatthetwo-phasejetpumpliquidsupplyhasagoodeffectontherapidfreezingofflatplates,andthecoolingrateisfaster,whichismoreconducivetothepreparationoffrozenfood.Theconcentrationandflowrateofliquidhaveacertaininfluenceontherapidfreezingeffect.Underthesameconditions,aliquidconcentrationof5%andaflowrateof8mL/shavethebestrapidfreezingeffect.Theresultsofmicroscopeobservationshowthatthewatercrystalsinlowconcentrationsolutionaresmallerandmoreregular,whichisbeneficialtothepreservationofthequalityandflavorofthefood.

Acknowledgments

WewouldliketoexpressoursincerethankstothelaboratoryandexperimentalequipmentsupportoftheFoodScienceandEngineeringCollegeofXXXUniversity,whichmadethisresearchpossible.

References

ZhaoL,HuangM,ZhangS.Studyonthepreparationtechnologyofquick-frozenwatermeloninlemonjuice[J].JournalofShijiazhuangVocationalTechnologyInstitute,2020,21(3):6-9.

WangL,LiM,HuangX,etal.Comparisonoffree