Engineering Heat Transfer

692 Pages·2018·32.929 MB·English

by  Janna, William S.

ENGINEERING
HEAT TRANSFER
Third Edition
HEAT TRANSFER
A Series of Reference Books and Textbooks
S E
ERIES DITOR
Afshin J. Ghajar
Regents Professor
School of Mechanical and Aerospace Engineering
Oklahoma State University
Engineering Heat Transfer: Third Edition, William S. Janna
Upcoming titles include:
Conjugate Problems in Convective Heat Transfer, Abram S. Dorfman
Introduction to Thermal and Fluid Engineering, Allan D. Kraus,
James R. Welty, Abdul Aziz
ENGINEERING
HEAT TRANSFER
Third Edition
WILLIAM S. JANNA
Boca Raton London New York
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Library of Congress Cataloging-in-Publication Data
Janna, William S.
Engineering heat transfer/ William S. Janna. -- 3rd ed.
p. cm. -- (Heat transfer)
Includes bibliographical references and index.
ISBN 978-1-4200-7202-0 (alk. paper)
1. Heat--Transmission. 2. Heat exchangers. I. Title. II. Series.
TJ260.J36 2008
621.402’2--dc22 2008043509
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Dedication
To Him who is our source of love and knowledge
To Marla who transforms His love into strength
And to the reader for whom knowledge becomes wisdom

Contents
Preface .....................................................................................................................xv
Acknowledgments .................................................................................................xvii
Author .....................................................................................................................xix
1
Fundamental Concepts
1.1 Introduction .....................................................................................................................................1-1
1.2 Mechanisms of Heat Transfer .......................................................................................................1-1
1.3 Dimensions and Units ...................................................................................................................1-3
1.4 Fourier’s Law of Heat Conduction ...............................................................................................1-5
1.5 Th ermal Conductivity ....................................................................................................................1-8
1.6 Convection Heat Transfer ...........................................................................................................1-13
1.7 Convection Heat-Transfer Coeffi cient .......................................................................................1-16
1.8 Radiation Heat Transfer ..............................................................................................................1-18
1.9 Emissivity and Other Radiative Properties ..............................................................................1-20
1.10 Combined Heat-Transfer Mechanisms ......................................................................................1-21
1.11 Summary ........................................................................................................................................1-23
1.12 Problems .........................................................................................................................................1-24
1.12.1 Introduction to Conduction .........................................................................................1-24
1.12.2 Introduction to Convection ..........................................................................................1-26
1.12.3 Introduction to Radiation .............................................................................................1-27
1.12.4 Combined Mechanism Problems ................................................................................1-29
2
Steady-State Conduction in One Dimension
2.1 Introduction ....................................................................................................................................2-1
2.2 One-Dimensional Conduction Equation ...................................................................................2-2
2.3 Plane Geometry Systems ..............................................................................................................2-5
2.3.1 Th ermal Circuit ..................................................................................................................2-7
2.3.2 Materials in Series ...........................................................................................................2-10
2.3.3 Materials in Parallel ........................................................................................................2-13
2.3.4 Plane Wall with Heat Generation .................................................................................2-16
2.3.5 Overall Heat-Transfer Coeffi cient .................................................................................2-18
2.4 Polar Cylindrical Geometry Systems ........................................................................................2-21
2.4.1 Pipe and Tube Specifi cations.........................................................................................2-24
2.4.2 Materials in Series ..........................................................................................................2-26
2.4.3 Cylinder with Heat Generation .....................................................................................2-29
2.4.4 Overall Heat-Transfer Coeffi cient .................................................................................2-31
2.4.5 Critical Th ickness of Insulation ...................................................................................2-34
vii
viii Contents
2.5 Spherical Geometry Systems ......................................................................................................2-37
2.6 Th ermal Contact Resistance .......................................................................................................2-39
2.7 Heat Transfer from Extended Surfaces ....................................................................................2-44
2.7.1 General Diff erential Equation for Extended Surfaces ...............................................2-45
2.7.2 Analysis of Pin Fin ..........................................................................................................2-48
2.7.3 Analysis of Straight Fin of Rectangular Profi le .........................................................2-58
2.7.4 Straight Fins of Triangular and Parabolic Profi le ......................................................2-61
2.7.5 Circular Fin of Rectangular Profi le..............................................................................2-65
2.8 Summary ........................................................................................................................................2-70
2.9 Problems ........................................................................................................................................2-71
2.9.1 One-Dimensional Planar Conduction..........................................................................2-71
2.9.2 One-Dimensional Conduction in Polar Coordinates ................................................2-75
2.9.3 Internal Heat Generation ...............................................................................................2-76
2.9.4 One-Dimensional Conduction in Spherical Coordinates ........................................2-77
2.9.5 Contact Resistance ..........................................................................................................2-77
2.9.6 Pin Fins ..............................................................................................................................2-79
2.9.7 Straight Fins .....................................................................................................................2-81
2.9.8 Circular Fins ....................................................................................................................2-84
3
Steady-State Conduction in Multiple Dimensions
3.1 Introduction ....................................................................................................................................3-1
3.2 General Conduction Equation .....................................................................................................3-1
3.2.1 Cartesian Coordinates .......................................................................................................3-1
3.3 Analytical Method of Solution .....................................................................................................3-3
3.4 Graphical Method of Solution ....................................................................................................3-10
3.5 Conduction Shape Factor ............................................................................................................3-15
3.6 Solution by Numerical Methods (Finite Diff erences) ............................................................3-24
3.6.1 Normalization of Equations ..........................................................................................3-25
3.6.2 Numerical Method of Solution for One-Dimensional Problems ............................3-26
3.7 Numerical Method of Solution for Two-Dimensional Problems ..........................................3-37
3.8 Methods of Solving Simultaneous Equations .........................................................................3-47
3.9 Summary .......................................................................................................................................3-52
3.10 Problems ........................................................................................................................................3-53
3.10.1 Analytical Methods ......................................................................................................3-53
3.10.2 Field Plotting: Graphical Method ...............................................................................3-54
3.10.3 Shape Factor Method: Charts ....................................................................................3-58
3.10.4 Normalization/Transformation of Equations ..........................................................3-61
3.10.5 Numerical Methods for One-Dimensional Problems .............................................3-63
3.10.6 Numerical Methods for Two-Dimensional Problems .............................................3-64
4
Unsteady-State Heat Conduction
4.1 Introduction ....................................................................................................................................4-1
4.2 Systems with Negligible Internal Resistance .............................................................................4-2
4.3 Systems with Finite Internal and Surface Resistances ............................................................4-8
4.4 Solutions to Multidimensional Geometry Systems ................................................................4-26
4.5 Approximate Methods of Solution to Transient-Conduction Problems ............................4-35
4.5.1 Numerical Methods ........................................................................................................4-35
4.5.2 Graphical Method ..........................................................................................................4-46
4.6 Summary .......................................................................................................................................4-50
Contents ix
4.7 Problems........................................................................................................................................4-50
4.7.1 Lumped Capacitance Method .......................................................................................4-50
4.7.2 Chart Solutions: Slabs, Cylinders, Spheres .................................................................4-51
4.7.3 Semi-Infi nite Slabs ..........................................................................................................4-53
4.7.4 Multidimensional Problems ..........................................................................................4-53
4.7.5 Numerical Methods ........................................................................................................4-54
4.7.6 Graphical Methods .........................................................................................................4-54
4.7.7 Project Problems .............................................................................................................4-55
5
Introduction to Convection
5.1 Introduction .....................................................................................................................................5-1
5.2 Fluid Properties ...............................................................................................................................5-1
5.2.1 Absolute Viscosity ..............................................................................................................5-2
5.2.2 Pressure ................................................................................................................................5-3
5.2.3 Density .................................................................................................................................5-3
5.2.4 Kinematic Viscosity ..........................................................................................................5-4
5.2.5 Surface Tension .................................................................................................................5-5
5.2.6 Internal Energy ..................................................................................................................5-5
5.2.7 Enthalpy ..............................................................................................................................5-5
5.2.8 Specifi c Heat .......................................................................................................................5-6
5.2.9 Compressibility Factor ......................................................................................................5-7
5.2.10 Volumetric Th ermal-Expansion Coeffi cient .................................................................5-8
5.3 Characteristics of Fluid Flow .......................................................................................................5-9
5.4 Equations of Fluid Mechanics .....................................................................................................5-10
5.4.1 Continuity Equation ........................................................................................................5-10
5.4.2 Momentum Equation (or Equation of Motion) ...........................................................5-11
5.5 Th ermal-Energy Equation ...........................................................................................................5-17
5.6 Applications to Laminar Flows ..................................................................................................5-20
5.7 Applications to Turbulent Flows ................................................................................................5-23
5.8 Natural-Convection Problem ....................................................................................................5-24
5.9 Dimensional Analysis ..................................................................................................................5-28
5.9.1 Internal Flows ....................................................................................................................5-31
5.9.2 External Flows..................................................................................................................5-32
5.9.3 Natural Convection ..........................................................................................................5-33
5.10 Summary .......................................................................................................................................5-34
5.11 Problems ........................................................................................................................................5-36
5.11.1 Fluid Properties ..............................................................................................................5-36
5.11.2 Momentum Equation ....................................................................................................5-36
5.11.3 Th ermal-Energy Equation .............................................................................................5-37
5.11.4 Dimensional Analysis ...................................................................................................5-39
5.11.5 Miscellaneous Problems ...............................................................................................5-40
6
Convection Heat Transfer in a Closed Conduit
6.1 Introduction .....................................................................................................................................6-1
6.2 Heat Transfer to and from Laminar Flow in Circular Conduit ..............................................6-1
6.2.1 Constant Heat Flux at Wall .............................................................................................6-3
6.2.2 Constant Wall Temperature ...........................................................................................6-11
6.2.3 Th ermal Entry Length .....................................................................................................6-17
6.2.4 Combined-Entry-Length Problem for Laminar Flow in Circular Duct ................6-26
6.3 Heat Transfer to and from Turbulent Flow in Circular Conduit ..........................................6-31