John H. Lienhard IV, John H. Lienhard V. A Heat Transfer Textbook

A HEAT TRANSFERTHIRDTEXTBOOK EDITIONJohn H. Lienhard IV / John H. Lienhard VA HeatTransferTextbookLienhard& LienhardPhlogiston PressISBN 0-9713835-0-2PSB 01-04-0249A Heat Transfer TextbookA Heat Transfer TextbookThird EditionbyJohn H. Lienhard IVandJohn H. Lienhard VPhlogistonPressCambridgeMassachusettsProfessor John H. Lienhard IVDepartment of Mechanical EngineeringUniversity of Houston4800 Calhoun RoadHouston TX 77204-4792 U.S.A.Professor John H. Lienhard VDepartment of Mechanical EngineeringMassachusetts Institute of Technology77 Massachusetts AvenueCambridge MA 02139-4307 U.S.A.Copyright ©2008 by John H.

Lienhard IV and John H. Lienhard VAll rights reservedPlease note that this material is copyrighted under U.S. Copyright Law. Theauthors grant you the right to download and print it for your personal use orfor non-profit instructional use. Any other use, including copying,distributing or modifying the work for commercial purposes, is subject to therestrictions of U.S. Copyright Law. International copyright is subject to theBerne International Copyright Convention.The authors have used their best efforts to ensure the accuracy of themethods, equations, and data described in this book, but they do notguarantee them for any particular purpose. The authors and publisher offerno warranties or representations, nor do they accept any liabilities withrespect to the use of this information.

Please report any errata to the authors.Lienhard, John H., 1930–A heat transfer textbook / John H. Lienhard IV andJohn H. Lienhard V — 3rd ed. — Cambridge, MA :Phlogiston Press, c2008Includes bibliographic references and index.1. Heat—Transmission 2. Mass TransferI. Lienhard, John H., V, 1961– II. TitleTJ260.L445 2008Published by Phlogiston PressCambridge, Massachusetts, U.S.A.This book was typeset in Lucida Bright and Lucida New Math fonts (designedby Bigelow & Holmes) using LATEX under the Y&Y TEX System.For updates and information, visit:http://web.mit.edu/lienhard/www/ahtt.htmlThis copy is:Version 1.31 dated January 16, 2008PrefaceThis book is meant for students in their introductory heat transfer course— students who have learned calculus (through ordinary differential equations) and basic thermodynamics.

We include the needed background influid mechanics, although students will be better off if they have hadan introductory course in fluids. An integrated introductory course inthermofluid engineering should also be a sufficient background for thematerial here.Our major objectives in rewriting the 1987 edition have been to bringthe material up to date and make it as clear as possible. We have substantially revised the coverage of thermal radiation, unsteady conduction,and mass transfer.

We have replaced most of the old physical propertydata with the latest reference data. New correlations have been introduced for forced and natural convection and for convective boiling. Thetreatment of thermal resistance has been reorganized. Dozens of newproblems have been added. And we have revised the treatment of turbulent heat transfer to include the use of the law of the wall. In a number ofplaces we have rearranged material to make it flow better, and we havemade many hundreds of small changes and corrections so that the textwill be more comfortable and reliable.

Lastly, we have eliminated RogerEichhorn’s fine chapter on numerical analysis, since that topic is nowmost often covered in specialized courses on computation.This book reflects certain viewpoints that instructors and studentsalike should understand. The first is that ideas once learned should notbe forgotten. We have thus taken care to use material from the earlierparts of the book in the parts that follow them. Two exceptions to thisare Chapter 10 on thermal radiation, which may safely be taught at anypoint following Chapter 2, and Chapter 11 on mass transfer, which drawsonly on material through Chapter 8.vviWe believe that students must develop confidence in their own abilityto invent means for solving problems.

The examples in the text thereforedo not provide complete patterns for solving the end-of-chapter problems. Students who study and absorb the text should have no unusualtrouble in working the problems. The problems vary in the demand thatthey lay on the student, and we hope that each instructor will select thosethat best challenge their own students.The first three chapters form a minicourse in heat transfer, which isapplied in all subsequent chapters.

Students who have had a previousintegrated course thermofluids may be familiar with this material, butto most students it will be new. This minicourse includes the study ofheat exchangers, which can be understood with only the concept of theoverall heat transfer coefficient and the first law of thermodynamics.We have consistently found that students new to the subject are greatlyencouraged when they encounter a solid application of the material, suchas heat exchangers, early in the course. The details of heat exchanger design obviously require an understanding of more advanced concepts —fins, entry lengths, and so forth.

Such issues are best introduced afterthe fundamental purposes of heat exchangers are understood, and wedevelop their application to heat exchangers in later chapters.This book contains more material than most teachers can cover inthree semester-hours or four quarter-hours of instruction. Typical onesemester coverage might include Chapters 1 through 8 (perhaps skippingsome of the more specialized material in Chapters 5, 7, and 8), a bit ofChapter 9, and the first four sections of Chapter 10.We are grateful to the Dell Computer Corporation’s STAR Program,the Keck Foundation, and the M.D. Anderson Foundation for their partialsupport of this project.JHL IV, Houston, TexasJHL V, Cambridge, MassachusettsAugust 2003ContentsIThe General Problem of Heat Exchange1Introduction1.1 Heat transfer .

. . . . . . . . . . . . . . . . . . . . . . . . .1.2 Relation of heat transfer to thermodynamics .1.3 Modes of heat transfer . . . . . . . . . . . . . . . . . .1.4 A look ahead . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Problems . .

. . . . . . . . . . . . . . . . . . . . . . . . . . .References . . . . . . . . . . . . . . . . . . . . . . . . . . . .231...............................................................Heat conduction concepts, thermal resistance, and the overallheat transfer coefficient2.1 The heat diffusion equation . . . . . . .

. . . . . . . . . . . . . . . .2.2 Solutions of the heat diffusion equation . . . . . . . . . . . . . .2.3 Thermal resistance and the electrical analogy . . . . . . . . .2.4 Overall heat transfer coefficient, U . . . . . . . . . . . . . . . . . .2.5 Summary . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . .Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Heat exchanger design3.1 Function and configuration of heat exchangers . . . . . .

. .3.2 Evaluation of the mean temperature difference in a heatexchanger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.3 Heat exchanger effectiveness . . . . . . . . . . . . . . . . . . . . . .3.4 Heat exchanger design . . . . . . . . . . . . . . . . . . . . . . . . . . .

.Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .336103536374649495862788686969999103120126129136viiContentsviiiIIAnalysis of Heat Conduction4Analysis of heat conduction and some steady one-dimensionalproblems4.1 The well-posed problem . .

. . . . . . . . . . . . . . . . . . . . . . . .4.2 The general solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.3 Dimensional analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.4 An illustration of dimensional analysis in a complex steadyconduction problem . . . .

. . . . . . . . . . . . . . . . . . . . . . . . .4.5 Fin design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5III6Transient and multidimensional heat conduction5.1 Introduction . . . . . .