A HEAT TRANSFER TEXTBOOK EDITION THIRD John H. Lienhard IV / John H. Lienhard V A Heat Transfer Textbook Lienhard & Lienhard 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 Professor John H. Lienhard IV Department of Mechanical Engineering University of Houston 4800 Calhoun Road Houston TX 77204-4792 U. Lienhard V Department of Mechanical Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139-4307 U. Copyright ©2004 by John H.
Lienhard IV and John H. Lienhard V All rights reserved Please note that this material is copyrighted under U. The authors grant you the right to download and print it for your personal use or for non-profit instructional use. Any other use, including copying, distributing or modifying the work for commercial purposes, is subject to the restrictions of U.
International copyright is subject to the Berne International Copyright Convention. The authors have used their best efforts to ensure the accuracy of the methods, equations, and data described in this book, but they do not guarantee them for any particular purpose. The authors and publisher offer no warranties or representations, nor do they accept any liabilities with respect to the use of this information. Please report any errata to the authors., 1930– A heat transfer textbook / John H.
Lienhard IV and John H. Lienhard V — 3rd ed. — Cambridge, MA : Phlogiston Press, c2004 Includes bibliographic references and index.L445 2004 Published by Phlogiston Press Cambridge, Massachusetts, U. This book was typeset in Lucida Bright and Lucida New Math fonts (designed by Bigelow & Holmes) using LATEX under the Y&Y TEX System.
For updates and information, visit: http://web.edu/lienhard/www/ahtt.html This copy is: Version 1.22 dated January 5, 2004 Preface This book is meant for students in their introductory heat transfer course — students who have learned calculus (through ordinary differential equa- tions) and basic thermodynamics. We include the needed background in 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. Our major objectives in rewriting the 1987 edition have been to bring the material up to date and make it as clear as possible.
We have substan- 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 problems have been added. And we have revised the treatment of turbu- lent heat transfer to include the use of the law of the wall. In a number of 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 point following Chapter 2, and Chapter 11 on mass transfer, which draws only on material through Chapter 8.
v vi We believe that students must develop confidence in their own ability to invent means for solving problems. The examples in the text therefore do not provide complete patterns for solving the end-of-chapter prob- lems. Students who study and absorb the text should have no unusual trouble in working the problems. The problems vary in the demand that they lay on the student, and we hope that each instructor will select those 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. We have consistently found that students new to the subject are greatly encouraged when they encounter a solid application of the material, such as heat exchangers, early in the course.
The details of heat exchanger de- 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- semester coverage might include Chapters 1 through 8 (perhaps skipping 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, the Keck Foundation, and the M. Anderson Foundation for their partial support of this project. JHL IV, Houston, Texas JHL V, Cambridge, Massachusetts August 2003 Contents I The General Problem of Heat Exchange 1 1 Introduction 3 1.2 Relation of heat transfer to thermodynamics .3 Modes of heat transfer. 46 2 Heat conduction concepts, thermal resistance, and the overall heat transfer coefficient 49 2.1 The heat diffusion equation .2 Solutions of the heat diffusion equation .3 Thermal resistance and the electrical analogy .4 Overall heat transfer coefficient, U.
96 3 Heat exchanger design 99 3.1 Function and configuration of heat exchangers .2 Evaluation of the mean temperature difference in a heat exchanger .3 Heat exchanger effectiveness .4 Heat exchanger design. 136 vii viii Contents II Analysis of Heat Conduction 139 4 Analysis of heat conduction and some steady one-dimensional problems 141 4.1 The well-posed problem .2 The general solution .4 An illustration of dimensional analysis in a complex steady conduction problem. 190 5 Transient and multidimensional heat conduction 193 5.2 Lumped-capacity solutions .3 Transient conduction in a one-dimensional slab .4 Temperature-response charts .5 One-term solutions .6 Transient heat conduction to a semi-infinite region .7 Steady multidimensional heat conduction .8 Transient multidimensional heat conduction. 265 III Convective Heat Transfer 267 6 Laminar and turbulent boundary layers 269 6.1 Some introductory ideas .2 Laminar incompressible boundary layer on a flat surface 276 6.3 The energy equation .4 The Prandtl number and the boundary layer thicknesses 296 6.5 Heat transfer coefficient for laminar, incompressible flow over a flat surface .6 The Reynolds analogy .7 Turbulent boundary layers .8 Heat transfer in turbulent boundary layers.
338 Contents ix 7 Forced convection in a variety of configurations 341 7.2 Heat transfer to and from laminar flows in pipes .3 Turbulent pipe flow .4 Heat transfer surface viewed as a heat exchanger .5 Heat transfer coefficients for noncircular ducts .6 Heat transfer during cross flow over cylinders .7 Other configurations. 393 8 Natural convection in single-phase fluids and during film condensation 397 8.2 The nature of the problems of film condensation and of natural convection .3 Laminar natural convection on a vertical isothermal surface .4 Natural convection in other situations. 452 9 Heat transfer in boiling and other phase-change configurations 457 9.1 Nukiyama’s experiment and the pool boiling curve .3 Peak pool boiling heat flux .5 Minimum heat flux .6 Transition boiling and system influences .7 Forced convection boiling in tubes .8 Forced convective condensation heat transfer .10 The heat pipe. 517 x Contents IV Thermal Radiation Heat Transfer 523 10 Radiative heat transfer 525 10.1 The problem of radiative exchange .3 Radiant heat exchange between two finite black bodies .4 Heat transfer among gray bodies.
592 V Mass Transfer 595 11 An introduction to mass transfer 597 11.2 Mixture compositions and species fluxes .3 Diffusion fluxes and Fick’s law .4 Transport properties of mixtures .5 The equation of species conservation .6 Mass transfer at low rates .7 Steady mass transfer with counterdiffusion .8 Mass transfer coefficients at high rates of mass transfer .9 Simultaneous heat and mass transfer. 686 VI Appendices 689 A Some thermophysical properties of selected materials 691 References. 694 B Units and conversion factors 721 References. 722 C Nomenclature 725 Citation Index 733 Subject Index 739 Part I The General Problem of Heat Exchange 1 1.
Introduction The radiation of the sun in which the planet is incessantly plunged, pene- trates the air, the earth, and the waters; its elements are divided, change direction in every way, and, penetrating the mass of the globe, would raise its temperature more and more, if the heat acquired were not exactly balanced by that which escapes in rays from all points of the surface and expands through the sky. The Analytical Theory of Heat, J.1 Heat transfer People have always understood that something flows from hot objects to cold ones. We call that flow heat. In the eighteenth and early nineteenth centuries, scientists imagined that all bodies contained an invisible fluid which they called caloric.
Caloric was assigned a variety of properties, some of which proved to be inconsistent with nature (e., it had weight and it could not be created nor destroyed). But its most important feature was that it flowed from hot bodies into cold ones. It was a very useful way to think about heat. Later we shall explain the flow of heat in terms more satisfactory to the modern ear; however, it will seldom be wrong to imagine caloric flowing from a hot body to a cold one.
The flow of heat is all-pervasive. It is active to some degree or another in everything. Heat flows constantly from your bloodstream to the air around you. The warmed air buoys off your body to warm the room you are in.
If you leave the room, some small buoyancy-driven (or convective) motion of the air will continue because the walls can never be perfectly isothermal. Such processes go on in all plant and animal life and in the air around us. They occur throughout the earth, which is hot at its core and cooled around its surface. The only conceivable domain free from heat flow would have to be isothermal and totally isolated from any other region.
It would be “dead” in the fullest sense of the word — devoid of any process of any kind.1 The overall driving force for these heat flow processes is the cooling (or leveling) of the thermal gradients within our universe. The heat flows that result from the cooling of the sun are the primary processes that we experience naturally. The conductive cooling of Earth’s center and the ra- diative cooling of the other stars are processes of secondary importance in our lives. The life forms on our planet have necessarily evolved to match the magnitude of these energy flows.
But while “natural man” is in balance with these heat flows, “technological man”1 has used his mind, his back, and his will to harness and control energy flows that are far more intense than those we experience naturally. To emphasize this point we suggest that the reader make an experiment.1 Generate as much power as you can, in some way that permits you to measure your own work output. You might lift a weight, or run your own weight up a stairwell, against a stopwatch. Express the result in watts (W).
Perhaps you might collect the results in your class. They should generally be less than 1 kW or even 1 horsepower (746 W).