Process Heat Transfer Principles and Applications

770 Pages·2008·7.18 MB·English

Process HeatTransfer
Dedication
ThisbookisdedicatedtoC.C.S.
Process Heat Transfer
Principles and Applications
R.W. Serth
DepartmentofChemicalandNaturalGasEngineering,
TexasA&MUniversity-Kingsville,
Kingsville,Texas,USA
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BritishLibraryCataloguinginPublicationData
Serth,R.W.
Processheattransfer:principlesandapplications
1. Heat-Transmission 2. Heatexchangers 3. Heatexchangers-Design
4. Heat-Transmission-Computerprograms
I.Title
621.4022
′
LibraryofCongressCatalognumber:2006940583
ISBN:978-0-12-373588-1
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06 07 08 09 10 11 10 9 8 7 6 5 4 3 2 1
Contents
Preface viii
ConversionFactors x
PhysicalConstants xi
Acknowledgements xii
1 Heat Conduction 1
1.1 Introduction 2
1.2 Fourier’sLawofHeatConduction 2
1.3 TheHeatConductionEquation 6
1.4 ThermalResistance 15
1.5 TheConductionShapeFactor 19
1.6 Unsteady-StateConduction 24
1.7 MechanismsofHeatConduction 31
2 Convective Heat Transfer 43
2.1 Introduction 44
2.2 CombinedConductionandConvection 44
2.3 ExtendedSurfaces 47
2.4 ForcedConvectioninPipesandDucts 53
2.5 ForcedConvectioninExternalFlow 62
2.6 FreeConvection 65
3 Heat Exchangers 85
3.1 Introduction 86
3.2 Double-PipeEquipment 86
3.3 Shell-and-TubeEquipment 87
3.4 TheOverallHeat-TransferCoefficient 93
3.5 TheLMTDCorrectionFactor 98
3.6 AnalysisofDouble-PipeExchangers 102
3.7 PreliminaryDesignofShell-and-TubeExchangers 106
3.8 RatingaShell-and-TubeExchanger 109
3.9 Heat-ExchangerEffectiveness 114
4 Design of Double-Pipe Heat Exchangers 127
4.1 Introduction 128
4.2 Heat-TransferCoefficientsforExchangerswithoutFins 128
4.3 HydraulicCalculationsforExchangerswithoutFins 128
4.4 Series/ParallelConfigurationsofHairpins 131
4.5 Multi-tubeExchangers 132
4.6 Over-SurfaceandOver-Design 133
4.7 Finned-PipeExchangers 141
4.8 Heat-TransferCoefficientsandFrictionFactorsforFinnedAnnuli 143
4.9 WallTemperatureforFinnedPipes 145
4.10 ComputerSoftware 152
vi CONTENTS
5 Design of Shell-and-Tube Heat Exchangers 187
5.1 Introduction 188
5.2 Heat-TransferCoefficients 188
5.3 HydraulicCalculations 189
5.4 FinnedTubing 192
5.5 Tube-CountTables 194
5.6 FactorsAffectingPressureDrop 195
5.7 DesignGuidelines 197
5.8 DesignStrategy 201
5.9 Computersoftware 218
6 The Delaware Method 245
6.1 Introduction 246
6.2 IdealTubeBankCorrelations 246
6.3 Shell-SideHeat-TransferCoefficient 248
6.4 Shell-SidePressureDrop 250
6.5 TheFlowAreas 254
6.6 CorrelationsfortheCorrectionFactors 259
6.7 EstimationofClearances 260
7 The Stream Analysis Method 277
7.1 Introduction 278
7.2 TheEquivalentHydraulicNetwork 278
7.3 TheHydraulicEquations 279
7.4 Shell-SidePressureDrop 281
7.5 Shell-SideHeat-TransferCoefficient 281
7.6 TemperatureProfileDistortion 282
7.7 TheWills–JohnstonMethod 284
7.8 ComputerSoftware 295
8 Heat-Exchanger Networks 327
8.1 Introduction 328
8.2 AnExample:TC3 328
8.3 DesignTargets 329
8.4 TheProblemTable 329
8.5 CompositeCurves 331
8.6 TheGrandCompositeCurve 334
8.7 SignificanceofthePinch 335
8.8 ThresholdProblemsandUtilityPinches 337
8.9 FeasibilityCriteriaatthePinch 337
8.10 DesignStrategy 339
8.11 Minimum-UtilityDesignforTC3 340
8.12 NetworkSimplification 344
8.13 NumberofShells 347
8.14 TargetingforNumberofShells 348
8.15 AreaTargets 353
8.16 TheDrivingForcePlot 356
8.17 SuperTargeting 358
8.18 TargetingbyLinearProgramming 359
8.19 ComputerSoftware 361
CONTENTS vii
9 Boiling Heat Transfer 385
9.1 Introduction 386
9.2 PoolBoiling 386
9.3 CorrelationsforNucleateBoilingonHorizontalTubes 387
9.4 Two-PhaseFlow 402
9.5 ConvectiveBoilinginTubes 416
9.6 FilmBoiling 428
10 Reboilers 443
10.1 Introduction 444
10.2 TypesofReboilers 444
10.3 DesignofKettleReboilers 449
10.4 DesignofHorizontalThermosyphonReboilers 467
10.5 DesignofVerticalThermosyphonReboilers 473
10.6 ComputerSoftware 488
11 Condensers 539
11.1 Introduction 540
11.2 TypesofCondensers 540
11.3 CondensationonaVerticalSurface:NusseltTheory 545
11.4 CondensationonHorizontalTubes 549
11.5 ModificationsofNusseltTheory 552
11.6 CondensationInsideHorizontalTubes 562
11.7 CondensationonFinnedTubes 568
11.8 PressureDrop 569
11.9 MeanTemperatureDifference 571
11.10 Multi-componentCondensation 590
11.11 ComputerSoftware 595
12 Air-Cooled Heat Exchangers 629
12.1 Introduction 630
12.2 EquipmentDescription 630
12.3 Air-SideHeat-TransferCoefficient 637
12.4 Air-SidePressureDrop 638
12.5 OverallHeat-TransferCoefficient 640
12.6 FanandMotorSizing 640
12.7 MeanTemperatureDifference 643
12.8 DesignGuidelines 643
12.9 DesignStrategy 644
12.10 ComputerSoftware 653
Appendix 681
AppendixA ThermophysicalPropertiesofMaterials 682
AppendixB DimensionsofPipeandTubing 717
AppendixC Tube-CountTables 729
AppendixD EquivalentLengthsofPipeFittings 737
AppendixE PropertiesofPetroleumStreams 740
Index 743
Preface
ThisbookisbasedonacourseinprocessheattransferthatIhavetaughtformanyyears.Thecourse
has been taken by seniors and first-year graduate students who have completed an introductory
courseinengineeringheattransfer.Althoughthisbackgroundisassumed,nearlyallstudentsneed
somereviewbeforeproceedingtomoreadvancedmaterial.Forthisreason,andalsotomakethe
bookself-contained,thefirstthreechaptersprovideareviewofessentialmaterialnormallycovered
in an introductory heat transfer course. Furthermore, the book is intended for use by practicing
engineersaswellasuniversitystudents,andithasbeenwrittenwiththeaimoffacilitatingself-study.
Unlikesomebooksinthisfield,noattemptismadehereintocovertheentirepanoplyofheattrans-
ferequipment.Instead,thebookfocusesonthetypesofequipmentmostwidelyusedinthechemical
processindustries,namely,shell-and-tubeheatexchangers(includingcondensersandreboilers),
air-cooledheatexchangersanddouble-pipe(hairpin)heatexchangers.Withintheconfinesofasin-
glevolume,thisapproachallowsanin-depthtreatmentofthematerialthatismostrelevantfroman
industrialperspective,andprovidesstudentswiththedetailedknowledgeneededforengineering
practice.Thisapproachisalsoconsistentwiththetimeavailableinaone-semestercourse.
Designofdouble-pipeexchangersispresentedinChapter4.Chapters5–7compriseaunitdealing
withshell-and-tubeexchangersinoperationsinvolvingsingle-phasefluids.Designofshell-and-tube
exchangers is covered in Chapter 5 using the Simplified Delaware method for shell-side calcula-
tions.Forpedagogicalreasons,moresophisticatedmethodsforperformingshell-sideheat-transfer
andpressure-dropcalculationsarepresentedseparatelyinChapter6(fullDelawaremethod)and
Chapter 7 (Stream Analysis method). Heat exchanger networks are covered in Chapter 8. I nor-
mallypresentthistopicatthispointinthecoursetoprovideachangeofpace. However, Chapter
8isessentiallyself-containedandcan,therefore,becoveredatanytime.Phase-changeoperations
arecoveredinChapters9–11.Chapter9presentsthebasicsofboilingheattransferandtwo-phase
flow. The latter is encountered in both Chapter 10, which deals with the design of reboilers, and
Chapter11,whichcoverscondensationandcondenserdesign.Designofair-cooledheatexchang-
ersispresentedinChapter12.Thematerialinthischapterisessentiallyself-containedand,hence,
itcanbecoveredatanytime.
Since the primary goal of both the book and the course is to provide students with the knowl-
edgeandskillsneededformodernindustrialpractice,computerapplicationsplayanintegralrole,
and the book is intended for use with one or more commercial software packages. HEXTRAN
(SimSci-Esscor),HTRIXchangerSuite(HeatTransferResearch,Inc.)andtheHTFSSuite(Aspen
Technology, Inc.) are used in the book, along with HX-Net (Aspen Technology, Inc.) for pinch
calculations.HEXTRANaffordsthemostcompletecoverageoftopics,asithandlesalltypesofheat
exchangers and also performs pinch calculations for design of heat exchanger networks. It does
not perform mechanical design calculations for shell-and-tube exchangers, however, nor does it
generatedetailedtubelayoutsorsettingplans.Furthermore,themethodologyusedbyHEXTRAN
isbasedonpubliclyavailabletechnologyandisgenerallylessrefinedthanthatoftheothersoftware
packages. TheHTRIandHTFSpackagesuseproprietarymethodsdevelopedbytheirrespective
research organizations, and are similar in their level of refinement. HTFS Suite handles all types
of heat exchangers; it also performs mechanical design calculations and develops detailed tube
layoutsandsettingplansforshell-and-tubeexchangers. HTRIXchangerSuitelacksamechanical
design feature, and the module for hairpin exchangers is not included with an academic license.
NeitherHTRInorHTFShasthecapabilitytoperformpinchcalculations.
Asofthiswriting,AspenTechnologyisnotprovidingtheTASCandACOLmodulesoftheHTFS
Suite under its university program. Instead, it is offering the HTFS-plus design package. This
packagebasicallyconsistsoftheTASCandACOLcomputationalenginescombinedwithslightly
modifiedGUI’sfromthecorrespondingBJACprograms(HETRANandAEROTRAN),andpackaged
withtheBJACTEAMSmechanicaldesignprogram.Thispackagediffersgreatlyinappearanceand
tosomeextentinavailablefeaturesfromHTFSSuite.However,mostoftheresultspresentedinthe
textusingTASCandACOLcanbegeneratedusingtheHTFS-pluspackage.
PREFACE ix
Software companies are continually modifying their products, making differences between the
text and current versions of the software packages unavoidable. However, many modifications
involveonlysuperficialchangesinformatthathavelittle,ifany,effectonresults.Moresubstantive
changesoccurlessfrequently,andeventhentheeffectstendtoberelativelyminor.Nevertheless,
readers should expect some divergence of the software from the versions used herein, and they
shouldnotbeundulyconcernediftheirresultsdiffersomewhatfromthosepresentedinthetext.
Indeed, even the same version of a code, when run on different machines, can produce slightly
different results due to differences in round-off errors. With these caveats, it is hoped that the
detailedcomputerexampleswillprovehelpfulinlearningtousethesoftwarepackages,aswellas
inunderstandingtheiridiosyncrasiesandlimitations.
I have made a concerted effort to introduce the complexities of the subject matter gradually
throughout the book in order to avoid overwhelming the reader with a massive amount of detail
atanyonetime.Asaresult,informationonshell-and-tubeexchangersisspreadoveranumberof
chapters,andsomeofthefinerdetailsareintroducedinthecontextofexampleproblems,including
computerexamples.Althoughthereisanobviousdownsidetothisstrategy,Ineverthelessbelieve
thatitrepresentsgoodpedagogy.
BothEnglishunits,whicharestillwidelyusedbyAmericanindustry,andSIunitsareusedinthis
book.StudentsintheUnitedStatesneedtobeproficientinbothsetsofunits,andthesameistrue
of students in countries that do a large amount of business with U.S. firms. In order to minimize
theneedforunitconversion, however, workingequationsareeithergivenindimensionlessform
or,whenthisisnotpractical,theyaregiveninbothsetsofunits.
I would like to take this opportunity to thank the many students who have contributed to this
effortovertheyears,bothdirectlyandindirectlythroughtheirparticipationinmycourse.Iwould
also like to express my deep appreciation to my colleagues in the Department of Chemical and
NaturalGasEngineeringatTAMUK,Dr.AliPilehvariandMrs.WandaPounds.Withouttheirhelp,
encouragementandfriendship,thisbookwouldnothavebeenwritten.