化學(xué)英語證書考試(pec)化工技術(shù)術(shù)語解釋_第1頁
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1、化學(xué)英語證書考試化學(xué)英語證書考試(PEC)化工技術(shù)術(shù)語解釋化工技術(shù)術(shù)語解釋GasVolumeTheamountofairgasintakeinaparticulartimeunitm3min、CMM:gasvolumeper1minutem3h、CMH:gasvolumeper1hourm3min、CFM:gasvolumepermin=cubicfeet(usedofteninAmerica)1f3min=0.0283m3minNm3

2、min:gasvolumeundernmalconditions(0℃huity0%intakeabsolutepressure760mmHg)Convertintothegastemperature.CalculationisbelowQt:convertedgastemperaturet℃gasvolumeQN:requestedgasvolumeundernmalconditionsStaticPressuremmAq:Aunit

3、showninheightwhenthewaterpumpedinupAq=Aqua(water)abbreviation.Waterspoutinmillimeters(writtenasmmH2O)inH2O:Ifnotinmillimeterswrittenininches.(usedofteninAmerica)1inch=25.4mmPa:Pal(Internationalunitfmeasuringpressure)1mmA

4、q=9.80665Pakgfm2:1kgfm2=1mmAqbar:bar(Europeanunitfmeasuringpressure)1bar=10.197mAq、1mbar=10.197mmAqShaftPowerThemeasureofpowerusedattheshaftofthefan.ShaftpowerismeasuredinkW.RevolutionSpeedrpm、(RM)、min1:revolutionper1min

5、uteGasSpecificWeightkgm3:WeightperunitvolumeofgasGenerally1.2kgm3ismostcommonundernmalconditions(20℃relativehuity65%absolutepressures760mmHg)Thespecificweightofthegaschangesduetotemperaturevariations.Thechangeinthespecif

6、icweightofthegasduetotemperatureiscalculatedasfollows.N1:RotationspeedbefechangerpmN2:RotationspeedafterchangerpmQ1:Gasvolumebefechangeinrotationalspeedm3minQ2:Gasvolumeafterchangeinrotationalspeedm3minSp1:Staticpressure

7、befechangeinrotationalspeedmmAqSp2:StaticpressureafterchangeinrotationalspeedmmAqLB1:ShaftpowerbefechangeinrotationalspeedkWLB2:ShaftpowerafterchangeinrotationalspeedkWNaturalTypeNaturaldraughtwithoutusingablower.FcedDra

8、ftTypeAblowerisinstalledattheairintakeofthetowerInducedDraftTypeAblowerisinstalledattheairoutletofthetowerClosedTypeAnindirectcoolingmethodwherewaterpassesthroughapipetheairspayedwaterflowoutsideofthepipe.OpenTypeAirwate

9、rdirectcontactmethodWhatisacoolingtowerAnequipmentthatcoolscirculatingwaterwithair.Theprincipleofthecoolingtower:thecirculatingwaterlosesheatduringevapationthusloweringthetemperature.CavitationCavitationisthefmingsubsequ

10、entcollapseofbubblesinaliquidwhenwateratnmaltemperatureispumpedupmethan10mthesaturatedvappressurefallsbelowthestaticpressure.Itsaphenomenonthatoccurswhenthestaticpressuresbelowthesaturatedvappressureevapatescondensesthel

11、iquidthuscreatesbubbles.Whenthesebubblescollapseitcreatesashockwavenoisevibrationreducestheefficiencyofthemachinerysuchasscrewspumps.Theerosionofthemachinerycouldcausethemachinerytobedestroyedduringcavitation.Whentheavai

12、lableNPSHisgreaterthanthenecessaryNPSHdependingonthegivenconditionsofpipepumpinstallationcavitationwillnotoccur.AvailableNPSHThereisaneedfahigherstaticheadpressurewhenthetotalpressureattheimpellsuctionisequivalenthighert

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