Handbook for Heat Exchangers and Tube Banks design

areconcerned, itshowsthevaluesoffactor ? whichisrequired forthistypeofcomputation. Thevaluesofthecorrectivefactorsforcoilsandtube banksarealsopresented. Milano,Italy DonatelloAnnaratone v Notation c=speci?cheat(J/kgK) d=diameter(m) E=ef?ciencyfactor h=enthalpy(kJ/kg) k=thermalconductivity(W/mK) M=mass?owrate(kg/s) m=massmoisturepercentage(%) q=heatpertimeunit(W) 2 S=surface(m ) ? t=temperature( C) 2 U=overallheattransfercoef?cient(W/m K) x=thickness(m) 2 ? =heattransfercoef?cient(W/m K) ? =characteristicfactor ? =characteristicfactor ? =ef?ciency ? =correctivefactor ? =correctivefactor ? =characteristicfactor ? ?t=temperaturedifference( C) vii viii Notation Superscripts =heating?uid =heated?uid Subscripts c=counter?ow e=exchanger i=inside l=logarithmic m=mean o=outside p=constantpressure(isobaric),parallel?ow w=wall 1=inlet(forheatingorheated?uid) 2=outlet(forheatingorheated?uid) Contents 1 Introduction to Computation . . . . . . . . . . . . . . . . . . . . . 1 1. 1 GeneralConsiderations . . . . . . . . . . . . . . . . . . . . . . 1 1. 2 MeanIsobaricSpeci?cHeat . . . . . . . . . . . . . . . . . . . . 3 1. 2. 1 WaterandSuperheatedSteam . . . . . . . . . . . . . . . 4 1. 2. 2 AirandOtherGases. . . . . . . . . . . . . . . . . . . . 4 2 Design Computation. . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. 2 FluidsinParallelFloworinCounterFlow . . . . . . . . . . . . 8 2. 3 TheMeanDifferenceinTemperatureinReality . . . . . . . . . 12 2. 3. 1 FluidsinCrossFlow. . . . . . . . . . . . . . . . . . . . 14 2. 3. 2 HeatExchangers. . . . . . . . . . . . . . . . . . . . . . 15 2. 3. 3 Coils. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2. 3. 4 TubeBankswithVariousPassagesoftheExternalFluid . 21 3 Veri?cation Computation . . . . . . . . . . . . . . . . . . . . . . . 25 3. 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3. 2 FluidsinParallelFloworinCounterFl