2传质与分离工程(双语)考试题

《传质与分离工程(双语)》试卷A第1页共7页诚信应考,考试作弊将带来严重后果！华南理工大学期末考试《传质与分离工程(双语)》试卷A注意事项：1.考前请将密封线内各项信息填写清楚；2.所有答案请直接答在试卷上；3．考试形式：闭卷；4.本试卷共六大题，满分100分，考试时间120分钟。题号123456总分得分评卷人1.Fillintheblanksorchoosethecorrectanswer(30points)(1)Whentotalpressureincreases,bubblepointwill,andrelativevolatilitywill,separationofthemixturewill.(2)Whenazeotropesareencountered,vaporandliquidcompositionsare,andtemperaturesofliquidandvaporphasesareaswell.(3)Forabinarymixture,whenthemolfractionofliquidphaseisx=0.6,thebubblepointist1,themolfractionofthecorrespondingequilibriumvaporphaseisy=0.7,dewpointist2.Therelationbetweent1andt2isthen().A.t1=t2;B.t1t2;C.t1t2;D.uncertain(4)Thereasonfor5~3sTfLHAistoensuretheseparationof.(5)Duringtheoperationofaplatecolumn,iftemperatureofreboilerandcolumnpressuredecreases,thepossiblereasonis.(6)Inthetotalrefluxoperationofadistillationcolumn,theslopeoftheoperatinglineinx-ydiagramis（）.A0；B0.5；C1；D∞.(7)Fortheundersaturatedmoistairwithcertainhumidity,whentemperaturedecreases,itsrelativehumiditywill,anditsdryingcapacitywill._____________________…姓名学号学院专业座位号(密封线内不答题)……………………………………………………密………………………………………………封………………………………………线……………………………………线………………………………………《传质与分离工程(双语)》试卷A第2页共7页(8)Inordertoincreasetherateofdryingofwetsolidsmainlycontainingboundwater,musttheairvelocitybeincreased?A.Yes；B.No.(9)IntheairwithC025,andrelativehumidity60%,theequilibriumwatercontentofthewoodis*1X.Iftheairrelativehumidityischangedinto40%underthesametemperature,theequilibriumwatercontentofthewoodbecomes*2X.Therelationshipoftheequilibriumwatercontentis().A.*2*1XX;B.*2*1XX;C.*2*1XX;D.uncertain.(10)Generallyspeaking,thediffusivitiesofgasesinliquidwaterarethaningasphases.2.Questions(7points)Whatisthecriticalwatercontent(XC)indryingprocess?DescribethefactorsthatinfluenceXC.《传质与分离工程(双语)》试卷A第3页共7页3.(15points)Acontinuousdistillationcolumnwithrefluxisusedfortheseparationofamixtureofheptaneandoctane(Heptaneisthemorevolatilecomponent).Itisrequiredthatthedistillateproductistocontain0.95(molefractionofheptane)andthebottomsproductnotmorethan0.02(molefractionofheptane).Thefeedisliquidatitsboilingpointandcontains0.45molefractionofheptane.Thevaporandliquidequilibriumdataaregivenintheattachedtable.Determine:(1)Theminimumnumberofidealplatesundertotalreflux.(2)Theoperatinglineequationforrectifyingsection.(3)Thenumberofidealplatesiftherefluxratiois2.5.AttachedtableVapor-liquidequilibriumdataforheptane-octanexyxy1.01.00.3110.4910.6560.810.1570.2800.4870.6730.0000.000yx10.90.80.70.60.50.40.30.20.1010.90.80.70.60.50.40.30.200.1Solution.(1)Drawtheequilibriumlineandtheoperatingline(diagonalline),thendrawstepsbetweenthesetwolines.Asshowninthefollowingfigure,Nmin=8.3idealplatesplusareboiler《传质与分离工程(双语)》试卷A第4页共7页0.020.95(2)IfRD=2.5,(3)RD=2.5,0.950.450.0216.316151413121110987654321N=15.3idealplatesplusareboiler11)2(1DDnDDnRxxRRy271.0714.015.295.015.25.21nnnxxy271.0714.015.295.015.25.21nnnxxy《传质与分离工程(双语)》试卷A第5页共7页4.(15points)Aporoussolidisdriedinabatchdryerunderconstantdryingconditions.Sevenhoursarerequiredtoreducethemoisturecontentfrom35to10percent.Thecriticalmoisturecontentsareonthedrybasis.Assumingthattherateofdryingduringthefalling-rateperiodisproportionaltothefree-moisturecontent,howlongshouldittaketodryasampleofthesamesolidfrom35to5percentunderthesamedryingconditions?《传质与分离工程(双语)》试卷A第6页共7页5.(15points)Experimentaldatahavebeenobtainedforaircontaining1.6%byvolumeSO2beingscrubbedwithpurewaterinapackedcolumnof1.5m2incross-sectionalareaand3.5minpackedheight.Enteringgasandliquidflowratesare0.062and2.2kmol/h,respectively.IftheoutletmolefractionofSO2inthegasis0.004andcolumntemperatureisnearambientwithm=35.48(thatis,theequilibriumrelationisy*=35.48x),calculatefromthedata:(a)TheoverallnumberoftransferunitsbasedongasphaseNoyforabsorptionofSO2(b)TheoverallheightofatransferunitbasedongasphaseHoyinmeters(c)Thevolumetricoverallmasstransfercoefficient,KyaforSO2inkmol/(m3s).《传质与分离工程(双语)》试卷A第7页共7页6.(18points)Somekindofwetsolidsisdriedinacontinuousdryerunderatmosphericpressure.Theoperationconditionsaregivenasfollows:Statesofair:Attheinletofthepre-heater,Airtemperatureandhumidityare:Ct0020,andairdrykgvaporwaterkgH/01.00,respectively.Attheinletofthedryer,Ct01120.Attheoutletofthedryer,airdrykgvaporwaterkgHCt/05.0,70202.Statesofwetsolids:Attheinletofthedryer,%20,30101wC(wetbasis).Attheoutletofthedryer,%5,50202wC(wetbasis).Specificheatofbone-drysolids,CkgkJCs0/5.1.Themassflowrateoffinalmoistsolids(product)is53.5kg/h.Calculate:(1)MassflowrateofdryairL,kgdryair/h;(2)HeattransferrateinputintothepreheaterQP,kJ/h;(3)SupplementaryheattransferrateintothedryerQD,kJ/h.Assumethatheatlossesofthedryingequipmentcanbeomitted.