研修感想与收获

Example1CalculationbyManualDesignanexchangertosubcoolcondensatefromamethanolcondenserfrom95DegCto40DegC.Flowrateofmethanol100,000kg/hr.Brackishwaterwillbeusedasthecoolant,withatemperaturerisefrom25DegCto40DegC.HotfluidMethanolFlowrate100000kg/hrInletT195DegCOutletT240DegCColdfluidWaterInlett125DegCOutlett240DegCPhysicalproperty:Methanolmeantemp.67.5DegCHeatcapacitymethanol2.84kJ/kgCMethanoldensity750kg/m3viscosityofmethanol0.34mNs/m2Methanolthermalconductivity0.19W/mCWatermeantemp.32.5DegCHeatcapacitywater4.2kJ/kgCWaterdensity995kg/m3Viscosityofwateru0.8mNs/m2Waterthermalconductivitykf0.59W/mCHeatLoad4339kWCoolingwaterflow69kg/s247937kg/hrDeltaTm=Ft*DetlaTlmDeltaTlm30.78621useoneshellpassandfourtubepassesR=3.67S=0.21fromfigure12.19Ft=0.85DeltaTm26DegCSupposeUo600W/m2CRequiredheattransferareaA276m2TubeGeometryTypePlainOD19.05mmThickness1.651mmID15.75mmLength4877mmTubeeffectivelength4826mmOneTubeOutsideArea0.29m2Requredtubenumber958#Tubeangle30DegreePitchPt23.81mmK1andn1fromfigure12.3Bundlediameter824mmFromfigure12.10Shell-bundleclearance17mmShelldiamter:Ds841mmTubesidecoefficientcalcMeanwatertemp.32.5DegCDensity995kg/m3Linearvelocity1.48m/shi*di/kf=jh*Re*Pr^0.338(u/uw)^0.14Re29069Pr5.7Negletc(u/uw)L/di306Fromfigure12.23jh0.0036hi7059Usesimplecalculationhi6638hi6638w/m2CShellsidecoefficientcalchs=hoc*Fn*Fw*Fb*FLhoc*do/kf=jh*Re*Pr^0.33*(u/uw)^0.14ChoosebafflespacinglB360mmAreaforcrossflowAs0.102545ShellsidemassvelocityGs672kg/sm2us0.90m/sEquivalentdiameterde0.023722mRe46860Pr5.08Chosse35%bufflecutFromfigure12.30jh0.0043Neglect(u/uw)hoc2760w/m2CTuberowcorrectionfactorFnTubeverticalpitchPt'21mmBafflecutheightHc294mmHeightbetweenbaffletips252mmNcv12Fromfigure12.34Fn1.01WindowscorrectionfactorFwHb286mmBundlecut0.35Fromfigure12.43Ra'0.32Tubeinonewindowsarea307Tubeincross-flowarea345Rw0.64Fromfigure121.35Fw0.83BypasscorrectionFbAb0.0061m2As0.1025m2Ab/As0.060Fb0.92LeakagecorrectionfactorFL'Clearancetubletobaffle0.8mmClearancebaffletoshell8.5mmAtb0.016m2Fromfigure12.43,35%cutqb2.54radsAsb0.013m2AL0.030m2AL/As0.290Fromfigure12.37bL0.24FL'0.65Shellsidecoefficienths1392w/m2CFoulingcoefficientofmethanol5000W/m2CFoulingcoefficientofwater3000W/m2CThermalcondutivityof304SS16W/m2C1/Uo=1/ho+1/hod+do*ln(do/di)/(2*kw)+do/di*1/hi+do/di*1/hid1/ho0.000744.43%1/hod0.000237.30%do*ln(do/di)/(2*kw)0.00017.01%do/di*1/hi0.000211.27%do/di*1/hid0.00041/Uo0.0016Uo618W/m2CRequiredheattransferareaAreq268m2Overdesign3.05%Designanexchangertosubcoolcondensatefromamethanolcondenserfrom95DegCto40DegC.Brackishwaterwillbeusedasthecoolant,withatemperaturerisefrom25DegCto40DegC.ShellsideTubesideQ=C*m*DeltaTDeltaTlm=((T1-t2)-(T2-t1))/ln((T1-t2)/(T2-t1))R=(T1-T2)/(t2-t1)S=(t2-t1)/(T1-t1)304stainlesssteel0.75inch0.065inch16feet1inchtubesheetthicknesseachsideuseevennumber1.25timestubeODUsefixedtubeTubeLength/ShellID5.805~100.069217m3/s0.046638m2eachpassarea1.484153m/shi=4200*(1.35+0.02t)*ut^0.8/di^0.2usethelowerfigureSpacing/Shelldiameter0.430.2~1As=(Pt-do)*Ds*lB/Ptde=1.27*(pt^2-0.785do^2)/do(forsquarepitch)de=1.10*(pt^2-0.917do^2)/do(fortriangularpitch)Re=density*velocity*diameter/viscosityPr=Cp*u/kfPt'=Pt(square)or0.87*Pt(triangular)Ab=lB*(Ds-Db)1/32inchFL=1-bL*((Atb+2Asb)/AL)1/Uo=1/ho+1/hod+do*ln(do/di)/(2*kw)+do/di*1/hi+do/di*1/hidshellfoulingmetaltube