A heat transfer textbook

762 Pages·2003·5.883 MB·English

by  Lienhardt, Lienhardt.

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Phlogiston Press ISBN 0-9713835-0-2
PSB 01-04-0249

A Heat Transfer Textbook

A Heat Transfer Textbook
Third Edition
by
John H. Lienhard IV
and
John H. Lienhard V
Phlogiston
Cambridge
Press
Massachusetts
ProfessorJohnH.LienhardIV
DepartmentofMechanicalEngineering
UniversityofHouston
4800CalhounRoad
HoustonTX77204-4792U.S.A.
ProfessorJohnH.LienhardV
DepartmentofMechanicalEngineering
MassachusettsInstituteofTechnology
77MassachusettsAvenue
CambridgeMA02139-4307U.S.A.
Copyright©2003byJohnH.LienhardIVandJohnH.LienhardV
Allrightsreserved
PleasenotethatthismaterialiscopyrightedunderU.S.CopyrightLaw. The
authorsgrantyoutherighttodownloadandprintitforyourpersonaluseor
fornon-profitinstructionaluse. Anyotheruse,includingcopying,
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restrictionsofU.S.CopyrightLaw. Internationalcopyrightissubjecttothe
BerneInternationalCopyrightConvention.
Theauthorshaveusedtheirbesteffortstoensuretheaccuracyofthe
methods,equations,anddatadescribedinthisbook,buttheydonot
guaranteethemforanyparticularpurpose. Theauthorsandpublisheroffer
nowarrantiesorrepresentations,nordotheyacceptanyliabilitieswith
respecttotheuseofthisinformation. Pleasereportanyerratatotheauthors.
Lienhard,JohnH.,1930–
Aheattransfertextbook/JohnH.LienhardIVand
JohnH.LienhardV—3rded. —Cambridge,MA:
PhlogistonPress,c2003
Includesbibliographicreferencesandindex.
1.Heat—Transmission 2.MassTransfer
I.Lienhard,JohnH.,V,1961– II.Title
TJ260.L4452003
PublishedbyPhlogistonPress
Cambridge,Massachusetts,U.S.A.
ThisbookwastypesetinLucidaBrightandLucidaNewMathfonts(designed
byBigelow&Holmes)usingLATEXundertheY&YTEXSystem.
Forupdatesandinformation,visit:
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Thiscopyis:
Version 1.12 dated January 19, 2003
Preface
Thisbookismeantforstudentsintheirintroductoryheattransfercourse
—studentswhohavelearnedcalculus(throughordinarydifferentialequa-
tions)andbasicthermodynamics. Weincludetheneededbackgroundin
fluid mechanics, although students will be better off if they have had
an introductory course in fluids. An integrated introductory course in
thermofluid engineering should also be a sufficient background for the
material here.
Ourmajorobjectivesinrewritingthe1987editionhavebeentobring
thematerialuptodateandmakeitasclearaspossible. Wehavesubstan-
tially revised the coverage of thermal radiation, unsteady conduction,
and mass transfer. We have replaced most of the old physical property
data with the latest reference data. New correlations have been intro-
duced for forced and natural convection and for convective boiling. The
treatment of thermal resistance has been reorganized. Dozens of new
problemshavebeenadded. Andwehaverevisedthetreatmentofturbu-
lentheattransfertoincludetheuseofthelawofthewall. Inanumberof
places we have rearranged material to make it flow better, and we have
made many hundreds of small changes and corrections so that the text
will be more comfortable and reliable. Lastly, we have eliminated Roger
Eichhorn’s fine chapter on numerical analysis, since that topic is now
most often covered in specialized courses on computation.
This book reflects certain viewpoints that instructors and students
alike should understand. The first is that ideas once learned should not
be forgotten. We have thus taken care to use material from the earlier
parts of the book in the parts that follow them. Two exceptions to this
are Chapter 10 on thermal radiation, which may safely be taught at any
pointfollowingChapter2,andChapter11onmasstransfer,whichdraws
only on material through Chapter 8.
v
vi
Webelievethatstudentsmustdevelopconfidenceintheirownability
toinventmeansforsolvingproblems. Theexamplesinthetexttherefore
do not provide complete patterns for solving the end-of-chapter prob-
lems. Students who study and absorb the text should have no unusual
troubleinworkingtheproblems. Theproblemsvaryinthedemandthat
theylayonthestudent,andwehopethateachinstructorwillselectthose
that best challenge their own students.
The first three chapters form a minicourse in heat transfer, which is
applied in all subsequent chapters. Students who have had a previous
integrated course thermofluids may be familiar with this material, but
to most students it will be new. This minicourse includes the study of
heat exchangers, which can be understood with only the concept of the
overall heat transfer coefficient and the first law of thermodynamics.
Wehaveconsistentlyfoundthatstudentsnewtothesubjectaregreatly
encouragedwhentheyencounterasolidapplicationofthematerial,such
asheatexchangers,earlyinthecourse. Thedetailsofheatexchangerde-
sign obviously require an understanding of more advanced concepts —
fins, entry lengths, and so forth. Such issues are best introduced after
the fundamental purposes of heat exchangers are understood, and we
develop their application to heat exchangers in later chapters.
This book contains more material than most teachers can cover in
three semester-hours or four quarter-hours of instruction. Typical one-
semestercoveragemightincludeChapters1through8(perhapsskipping
some of the more specialized material in Chapters 5, 7, and 8), a bit of
Chapter 9, and the first four sections of Chapter 10.
We are grateful to the Dell Computer Corporation’s STAR Program,
theKeckFoundation,andtheM.D.AndersonFoundationfortheirpartial
support of this project.
JHL IV, Houston, Texas
JHL V, Cambridge, Massachusetts
August 2002
Contents
I The General Problem of Heat Exchange 1
1 Introduction 3
1.1 Heat transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Relation of heat transfer to thermodynamics. . . . . . . . . . 6
1.3 Modes of heat transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.4 A look ahead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.5 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2 Heatconductionconcepts, thermalresistance, andtheoverall
heat transfer coefficient 49
2.1 The heat diffusion equation . . . . . . . . . . . . . . . . . . . . . . . 49
2.2 Solutions of the heat diffusion equation. . . . . . . . . . . . . . 58
2.3 Thermal resistance and the electrical analogy . . . . . . . . . 62
2.4 Overall heat transfer coefficient, U . . . . . . . . . . . . . . . . . . 78
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3 Heat exchanger design 99
3.1 Function and configuration of heat exchangers . . . . . . . . 99
3.2 Evaluation of the mean temperature difference in a heat
exchanger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
3.3 Heat exchanger effectiveness . . . . . . . . . . . . . . . . . . . . . . 120
3.4 Heat exchanger design. . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
vii
viii Contents
II Analysis of Heat Conduction 139
4 Analysisofheatconductionandsomesteadyone-dimensional
problems 141
4.1 The well-posed problem . . . . . . . . . . . . . . . . . . . . . . . . . . 141
4.2 The general solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
4.3 Dimensional analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
4.4 Anillustrationofdimensionalanalysisinacomplexsteady
conduction problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
4.5 Fin design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
5 Transient and multidimensional heat conduction 193
5.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
5.2 Lumped-capacity solutions . . . . . . . . . . . . . . . . . . . . . . . . 194
5.3 Transient conduction in a one-dimensional slab . . . . . . . 203
5.4 Temperature-response charts . . . . . . . . . . . . . . . . . . . . . . 208
5.5 One-term solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
5.6 Transient heat conduction to a semi-infinite region. . . . . 220
5.7 Steady multidimensional heat conduction . . . . . . . . . . . . 235
5.8 Transient multidimensional heat conduction. . . . . . . . . . 247
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
III Convective Heat Transfer 267
6 Laminar and turbulent boundary layers 269
6.1 Some introductory ideas . . . . . . . . . . . . . . . . . . . . . . . . . . 269
6.2 Laminar incompressible boundary layer on a flat surface 276
6.3 The energy equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
6.4 The Prandtl number and the boundary layer thicknesses 296
6.5 Heattransfercoefficientforlaminar,incompressibleflow
over a flat surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
6.6 The Reynolds analogy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
6.7 Turbulent boundary layers . . . . . . . . . . . . . . . . . . . . . . . . 313
6.8 Heat transfer in turbulent boundary layers . . . . . . . . . . . 322
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338