Heat and Mass Transfer – Fundamentals and Application
Heat and Mass Transfer – Fundamentals & Applications
Fifth Edition
Yunus A. Cengel , Afshin J. Ghajar
Chapter O N E
Introduction and Basic Concepts 1
Chapter T W O
Heat Conduction Equation 67
Chapter T H R E E
Steady Heat Conduction 142
Chapter F O U R
Transient Heat Conduction 237
Chapter F I V E
Numerical Methods in Heat Conduction 307
Chapter S I X
Fundamentals of Convection 379
Chapter S E V E N
External Forced Convection 424
Chapter E I G H T
Internal Forced Convection 473
Chapter N I N E
Natural Convection 533
Chapter T E N
Boiling and Condensation 598
Chapter E L E V E N
Heat Exchangers 649
Chapter T W E L V E
Fundamentals of Thermal Radiation 715
Chapter T H I R T E E N
Radiation Heat Transfer 767
Chapter F O U R T E E N
Mass Transfer 835
Chapter F I F T E E N ( W E B Chapter )
Cooling of Electronic Equipment
Chapter S I X T E E N ( W E B Chapter )
Heating and Cooling of Buildings
Chapter S E V E N T E E N ( W E B Chapter )
Refrigeration and Freezing of Foods
A P P E N D I X 1
Property Tables and Charts (Si Units) 907
A P P E N D I X 2
Property Tables and Charts (English Units) 935
B R I E F C O N T E N T Spreface Xiii
Chapter O N E
Introduction and Basic Concepts 1
1–1 Thermodynamics and Heat Transfer 2
Application Areas of Heat Transfer 3
Historical Background 3
1–2 Engineering Heat Transfer 4
Modeling in Engineering 5
1–3 Heat and Other Forms of Energy 6
Specific Heats of Gases, Liquids, and Solids 7
Energy Transfer 9
1–4 the First Law of Thermodynamics 11
Energy Balance for Closed Systems (Fixed Mass) 12
Energy Balance for Steady-flow Systems 12
Surface Energy Balance 13
1–5 Heat Transfer Mechanisms 17
1–6 Conduction 17
Thermal Conductivity 19
Thermal Diffusivity 22
1–7 Convection 25
1–8 Radiation 27
1–9 Simultaneous Heat Transfer Mechanisms 30
1–10 Prevention Through Design 35
1–11 Problem-solving Technique 38
Engineering Software Packages 40
Engineering Equation Solver (Ees) 41
A Remark on Significant Digits 42
Topic of Special Interest:
Thermal Comfort 43
Summary 50
References and Suggested Reading 51
Problems 51
Chapter T W O
Heat Conduction Equation 67
2–1 Introduction 68
Steady versus Transient Heat Transfer 69
Multidimensional Heat Transfer 70
Heat Generation 72
2–2 One-Dimensional Heat Conduction
Equation 73
Heat Conduction Equation in a Large Plane Wall 73
Heat Conduction Equation in a Long Cylinder 75
Heat Conduction Equation in a Sphere 76
Combined One-Dimensional Heat Conduction Equation 77
2–3 General Heat Conduction Equation 79
Rectangular Coordinates 79
Cylindrical Coordinates 81
Spherical Coordinates 81
2–4 Boundary and Initial Conditions 82
1 Specified Temperature Boundary Condition 84
2 Specified Heat Flux Boundary Condition 84
Special Case: Insulated Boundary 85
Another Special Case: Thermal Symmetry 85
3 Convection Boundary Condition 86
4 Radiation Boundary Condition 88
5 Interface Boundary Conditions 89
6 Generalized Boundary Conditions 89
2–5 Solution of Steady One-Dimensional
Heat Conduction Problems 91
2–6 Heat Generation in a Solid 104
2–7 Variable Thermal Conductivity, k(T) 112
Topic of Special Interest:
A Brief Review of Differential Equations 115
Classification of Differential Equations 117
Solutions of Differential Equations 118
General Solution to Selected Differential Equations 119
Summary 121
References and Suggested Reading 122
Problems 122
C o n t e n t s
viiCONTENTS
viii
Chapter t h r e e
STEADY HEAT CONDUCTION 142
3–1 Steady Heat Conduction in Plane Walls 143
Thermal Resistance Concept 144
Thermal Resistance Network 146
Multilayer Plane Walls 148
3–2 Thermal Contact Resistance 153
3–3 Generalized Thermal Resistance
Networks 158
3–4 Heat Conduction in Cylinders and Spheres 161
Multilayered Cylinders and Spheres 163
3–5 Critical Radius of Insulation 167
3–6 Heat Transfer from Finned Surfaces 170
Fin Equation 171
Fin Efficiency 176
Fin Effectiveness 178
Proper Length of a Fin 181
3–7 Bioheat Transfer Equation 187
3–8 Heat Transfer in Common Configurations 192
Topic of Special Interest:
Heat Transfer through Walls and Roofs 197
Summary 207
References and Suggested Reading 209
Problems 209
Chapter f o u r
TRANSIENT HEAT CONDUCTION 237
4–1 Lumped System Analysis 238
Criteria for Lumped System Analysis 239
Some Remarks on Heat Transfer in Lumped Systems 241
4–2 Transient Heat Conduction in Large Plane
Walls, Long Cylinders, and Spheres with
Spatial Effects 244
Nondimensionalized One-Dimensional
Transient Conduction Problem 245
Exact Solution of One-Dimensional Transient Conduction
Problem 247
Approximate Analytical and Graphical Solutions 250
4–3 Transient Heat Conduction in Semi-Infinite
Solids 261
Contact of Two Semi-Infinite Solids 265
4–4 Transient Heat Conduction in
Multidimensional Systems 268
Topic of Special Interest:
Refrigeration and Freezing of Foods 276
Control of Microorganisms in Foods 276
Refrigeration and Freezing of Foods 278
Beef Products 279
Poultry Products 283
Summary 287
References and Suggested Reading 289
Problems 289
Chapter f i v e
NUMERICAL METHODS
IN HEAT CONDUCTION 307
5–1 Why Numerical Methods? 308
1 Limitations 309
2 Better Modeling 309
3 Flexibility 310
4 Complications 310
5 Human Nature 310
5–2 Finite Difference Formulation
of Differential Equations 311
5–3 One-Dimensional Steady Heat Conduction 314
Boundary Conditions 316
Treating Insulated Boundary Nodes as Interior Nodes:
The Mirror Image Concept 318
5–4 Two-Dimensional Steady Heat Conduction 325
Boundary Nodes 326
Irregular Boundaries 330
5–5 Transient Heat Conduction 334
Transient Heat Conduction in a Plane Wall 336
Stability Criterion for Explicit Method: Limitation on Dt 338
Two-Dimensional Transient Heat Conduction 347
Topic of Special Interest:
Controlling the Numerical Error 352
Discretization Error 352
Round-Off Error 353
Controlling the Error in Numerical Methods 354
Summary 355
References and Suggested Reading 356
Problems 357
Chapter s i x
FUNDAMENTALS OF CONVECTION 379
6–1 Physical Mechanism of Convection 380
Nusselt Number 382
6–2 Classification of Fluid Flows 384
Viscous versus Inviscid Regions of Flow 384
Internal versus External Flow 384
Compressible versus Incompressible Flow 384
Laminar versus Turbulent Flow 385Natural (or Unforced) versus Forced Flow 385
Steady versus Unsteady Flow 385
One-, Two-, and Three-Dimensional Flows 386
6–3 Velocity Boundary Layer 387
Wall Shear Stress 388
6–4 Thermal Boundary Layer 389
Prandtl Number 390
6–5 Laminar and Turbulent Flows 390
Reynolds Number 391
6–6 Heat and Momentum Transfer in Turbulent
Flow 392
6–7 Derivation of Differential Convection
Equations 394
The Continuity Equation 395
The Momentum Equations 395
Conservation of Energy Equation 397
6–8 Solutions of Convection Equations for a
Flat Plate 401
The Energy Equation 403
6–9 Nondimensionalized Convection Equations
and Similarity 405
6–10 Functional Forms of Friction and Convection
Coefficients 406
6–11 Analogies Between Momentum and Heat
Transfer 407
Topic of Special Interest:
Microscale Heat Transfer 410
Summary 413
References and Suggested Reading 414
Problems 415
Chapter s e v e n
EXTERNAL FORCED CONVECTION 424
7–1 Drag and Heat Transfer in External Flow 425
Friction and Pressure Drag 425
Heat Transfer 427
7–2 Parallel Flow over Flat Plates 428
Friction Coefficient 429
Heat Transfer Coefficient 430
Flat Plate with Unheated Starting Length 432
Uniform Heat Flux 433
7–3 Flow across Cylinders and Spheres 438
Effect of Surface Roughness 440
Heat Transfer Coefficient 442
7–4 Flow across Tube Banks 446
Pressure Drop 449
Summary 453
References and Suggested Reading 454
Problems 455
Chapter e i g h t
INTERNAL FORCED CONVECTION 473
8–1 Introduction 474
8–2 Average Velocity and Temperature 475
Laminar and Turbulent Flow in Tubes 476
8–3 The Entrance Region 477
Entry Lengths 479
8–4 General Thermal Analysis 480
Constant Surface Heat Flux (q
.
s 5 constant) 481
Constant Surface Temperature (Ts 5 constant) 482
8–5 Laminar Flow in Tubes 485
Pressure Drop 487
Temperature Profile and the Nusselt Number 489
Constant Surface Heat Flux 489
Constant Surface Temperature 490
Laminar Flow in Noncircular Tubes 491
Developing Laminar Flow in the Entrance Region 492
8–6 Turbulent Flow in Tubes 496
Fully Developed Transitional Flow Heat Transfer 497
Rough Surfaces 498
Developing Turbulent Flow in the Entrance Region 500
Turbulent Flow in Noncircular Tubes 500
Flow through Tube Annulus 500
Heat Transfer Enhancement 501
Topic of Special Interest:
Transitional Flow in Tubes 507
Pressure Drop in the Transition Region 508
Heat Transfer in the Transition Region 512
Pressure Drop in the Transition Region
in Mini and Micro Tubes 517
References 517
Summary 518
References and Suggested Reading 519
Problems 520
Chapter n i n e
NATURAL CONVECTION 533
9–1 Physical Mechanism of Natural Convection 534
9–2 Equation of Motion and the Grashof Number 537
The Grashof Number 539
9–3 Natural Convection over Surfaces 540
Vertical Plates (Ts 5 constant) 541
Vertical Plates (q
.
s 5 constant) 541
Vertical Cylinders 543
CONTENTS
ixCONTENTS
x
Inclined Plates 543
Horizontal Plates 544
Horizontal Cylinders and Spheres 544
9–4 Natural Convection from Finned Surfaces
and PCBs 548
Natural Convection Cooling of Finned Surfaces
(Ts 5 constant) 548
Natural Convection Cooling of Vertical PCBs
(q
.
s 5 constant) 549
Mass Flow Rate through the Space between Plates 550
9–5 Natural Convection Inside Enclosures 552
Effective Thermal Conductivity 553
Horizontal Rectangular Enclosures 553
Inclined Rectangular Enclosures 554
Vertical Rectangular Enclosures 555
Concentric Cylinders 555
Concentric Spheres 556
Combined Natural Convection and Radiation 556
9–6 Combined Natural and Forced Convection 562
Topic of Special Interest:
Heat Transfer through Windows 566
Edge-of-Glass U-Factor of a Window 570
Frame U-Factor 571
Interior and Exterior Surface Heat Transfer Coefficients 571
Overall U-Factor of Windows 572
Summary 577
References and Suggested Reading 578
Problems 579
Chapter t e n
BOILING AND CONDENSATION 598
10–1 Boiling Heat Transfer 599
10–2 Pool Boiling 601
Boiling Regimes and the Boiling Curve 601
Natural Convection Boiling (to Point A on the Boiling Curve) 601
Nucleate Boiling (between Points A and C) 602
Transition Boiling (between Points C and D) 603
Film Boiling (beyond Point D) 603
Heat Transfer Correlations in Pool Boiling 604
Nucleate Boiling 604
Peak Heat Flux 605
Minimum Heat Flux 607
Film Boiling 607
Enhancement of Heat Transfer in Pool Boiling 608
10–3 Flow Boiling 612
10–4 Condensation Heat Transfer 613
10–5 Film Condensation 614
Flow Regimes 616
Heat Transfer Correlations for Film Condensation 616
Effect of Vapor Velocity 622
The Presence of Noncondensable Gases in Condensers 622
10–6 Film Condensation Inside Horizontal
Tubes 626
10–7 Dropwise Condensation 628
Topic of Special Interest:
Non-Boiling Two-Phase Flow Heat Transfer 629
Application of Reynolds Analogy to Non-Boiling
Two-Phase Flow 634
References 635
Summary 636
References and Suggested Reading 637
Problems 638
Chapter e l e v e n
HEAT EXCHANGERS 649
11–1 Types of Heat Exchangers 650
11–2 The Overall Heat Transfer Coefficient 653
Fouling Factor 656
11–3 Analysis of Heat Exchangers 660
11–4 The Log Mean Temperature Difference
Method 662
Counter-Flow Heat Exchangers 664
Multipass and Cross-Flow Heat Exchangers:
Use of a Correction Factor 665
11–5 The Effectiveness–NTU Method 672
11–6 Selection of Heat Exchangers 685
Heat Transfer Rate 686
Cost 686
Pumping Power 686
Size and Weight 686
Type 687
Materials 687
Other Considerations 687
Topic of Special Interest:
The Human Cardiovascular System as a
Counter-Current Heat Exchanger 689
Summary 695
References and Suggested Reading 696
Problems 696
Chapter t w e l v e
FUNDAMENTALS OF THERMAL RADIATION 715
12–1 Introduction 716
12–2 Thermal Radiation 71712–3 Blackbody Radiation 719
12–4 Radiation Intensity 726
Solid Angle 726
Intensity of Emitted Radiation 727
Incident Radiation 729
Radiosity 729
Spectral Quantities 729
12–5 Radiative Properties 732
Emissivity 732
Absorptivity, Reflectivity, and Transmissivity 736
Kirchhoff’s Law 739
The Greenhouse Effect 742
12–6 Atmospheric and Solar Radiation 742
Topic of Special Interest:
Solar Heat Gain through Windows 747
Summary 754
References and Suggested Reading 755
Problems 756
Chapter t h i r t e e n
RADIATION HEAT TRANSFER 767
13–1 The View Factor 768
13–2 View Factor Relations 771
1 The Reciprocity Relation 772
2 The Summation Rule 775
3 The Superposition Rule 777
4 The Symmetry Rule 778
View Factors between Infinitely Long Surfaces:
The Crossed-Strings Method 780
13–3 Radiation Heat Transfer: Black
Surfaces 782
13–4 Radiation Heat Transfer: Diffuse, Gray
Surfaces 784
Radiosity 784
Net Radiation Heat Transfer to or from a Surface 785
Net Radiation Heat Transfer between Any Two
Surfaces 786
Methods of Solving Radiation Problems 787
Radiation Heat Transfer in Two-Surface Enclosures 788
Radiation Heat Transfer in Three-Surface Enclosures 790
13–5 Radiation Shields and the Radiation
Effects 796
Radiation Effect on Temperature Measurements 798
13–6 Radiation Exchange with Emitting and
Absorbing Gases 801
Radiation Properties of a Participating Medium 802
Emissivity and Absorptivity of Gases and Gas Mixtures 803
Topic of Special Interest:
Heat Transfer from the Human Body 810
Summary 814
References and Suggested Reading 815
Problems 816
Chapter f o u r t e e n
MASS TRANSFER 835
14–1 Introduction 836
14–2 Analogy Between Heat and Mass
Transfer 837
Temperature 838
Conduction 838
Heat Generation 838
Convection 839
14–3 Mass Diffusion 839
1 Mass Basis 839
2 Mole Basis 840
Special Case: Ideal Gas Mixtures 841
Fick’s Law of Diffusion: Stationary Medium Consisting
of Two Species 841
14–4 Boundary Conditions 845
14–5 Steady Mass Diffusion Through
a Wall 850
14–6 Water Vapor Migration in
Buildings 854
14–7 Transient Mass Diffusion 859
14–8 Diffusion in a Moving Medium 861
Special Case: Gas Mixtures at Constant Pressure and
Temperature 865
Diffusion of Vapor through a Stationary Gas:
Stefan Flow 866
Equimolar Counterdiffusion 868
14–9 Mass Convection 873
Analogy Between Friction, Heat Transfer, and Mass
Transfer Coefficients 877
Special Case: Pr < Sc < 1
(Reynolds Analogy) 877
General Case: Pr ? Sc ? 1
(Chilton–Colburn Analogy) 878
Limitation on the Heat–Mass Convection
Analogy 879
Mass Convection Relations 879
14–10 Simultaneous Heat and Mass Transfer 882
Summary 888
References and Suggested Reading 890
Problems 890
CONTENTS
xiCONTENTS
xii
Chapter f i f t e e n
( w e b Chapter )
COOLING OF ELECTRONIC EQUIPMENT
15–1 Introduction and History
15–2 Manufacturing of Electronic Equipment
15–3 Cooling Load of Electronic Equipment
15–4 Thermal Environment
15–5 Electronics Cooling in Different Applications
15–6 Conduction Cooling
15–7 Air Cooling: Natural Convection and Radiation
15–8 Air Cooling: Forced Convection
15–19 Liquid Cooling
15–10 Immersion Cooling
Summary
References and Suggested Reading
Problems
Chapter s i x t e e n
( w e b Chapter )
HEATING AND COOLING OF BUILDINGS
16–1 A Brief History
16–2 Human Body and Thermal Comfort
16–3 Heat Transfer from the Human Body
16–4 Design Conditions for Heating and Cooling
16–5 Heat Gain from People, Lights, and Appliances
16–6 Heat Transfer through Walls and Roofs
16–7 Heat Loss from Basement Walls and Floors
16–8 Heat Transfer through Windows
16–9 Solar Heat Gain through Windows
16–10 Infiltration Heat Load and Weatherizing
16–11 Annual Energy Consumption
Summary
References and Suggested Reading
Problems
Chapter s e v e n t e e n
( w e b Chapter )
REFRIGERATION AND FREEZING OF FOODS
17–1 Control of Microorganisms in Foods
17–2 Refrigeration and Freezing of Foods
17–3 Thermal Properties of Food
17–4 Refrigeration of Fruits and Vegetables
17–5 Refrigeration of Meats, Poultry, and Fish
17–6 Refrigeration of Eggs, Milk, and Bakery Products
17–7 Refrigeration Load of Cold Storage Rooms
17–8 Transportation of Refrigerated Foods
Summary
References and Suggested Reading
Problems
A p p e n d i x 1
PROPERTY TABLES AND CHARTS
(SI UNITS) 907
Table A–1 Molar mass, gas constant, and ideal-gas
specific heats of some substances 908
Table A–2 Boiling and freezing point
properties 909
Table A–3 Properties of solid metals 910–912
Table A–4 Properties of solid nonmetals 913
Table A–5 Properties of building
materials 914–915
Table A–6 Properties of insulating materials 916
Table A–7 Properties of common foods 917–918
Table A–8 Properties of miscellaneous
materials 919
Table A–9 Properties of saturated water 920
Table A–10 Properties of saturated
refrigerant-134a 921
Table A–11 Properties of saturated ammonia 922
Table A–12 Properties of saturated propane 923
Table A–13 Properties of liquids 924
Table A–14 Properties of liquid metals 925
Table A–15 Properties of air at 1 atm pressure 926
Table A–16 Properties of gases at 1 atm
pressure 927–928
Table A–17 Properties of the atmosphere at
high altitude 929
Table A–18 Emissivities of surfaces 930–931
Table A–19 Solar radiative properties of
materials 932
FIGURE A–20 The Moody chart for the friction
factor for fully developed flow in
circular pipes 933CONTENTS
A p p e n d i x 2
PROPERTY TABLES AND CHARTS
(ENGLISH UNITS) 935
Table A–1E Molar mass, gas constant, and
ideal-gas specific heats of some
substances 936
Table A–2E Boiling and freezing point
properties 937
Table A–3E Properties of solid metals 938–939
Table A–4E Properties of solid nonmentals 940
Table A–5E Properties of building
materials 941–942
Table A–6E Properties of insulating
materials 943
Table A–7E Properties of common
foods 944–945
Table A–8E Properties of miscellaneous
materials 946
Table A–9E Properties of saturated water 947
Table A–10E Properties of saturated
refrigerant-134a 948
Table A–11E Properties of saturated ammonia 949
Table A–12E Properties of saturated propane 950
Table A–3E Properties of liquids 951
Table A–14E Properties of liquid metals 952
Table A–15E Properties of air at 1 atm pressure 953
Table A–16E Properties of gases at 1 atm
pressure 954–955
Table A–17E Properties of the atmosphere at high
altitude 956
INDEX 957
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