## Fundamentals of Thermal-Fluid Sciences, Sixth Edition

By Yunus A. Çengel, John M. Cimbala, and Afshin J. Ghajar

**Contents:**

Preface xiv

Chapter One

INTRODUCTION AND OVERVIEW 1

1–1 Introduction to Thermal‑Fluid Sciences 2

Application Areas of Thermal‑Fluid Sciences 2

1–2 Thermodynamics 3

1–3 Heat Transfer 4

1–4 Fluid Mechanics 5

1–5 Importance of Dimensions and Units 7

Some SI and English Units 8

Dimensional Homogeneity 10

Unity Conversion Ratios 12

1–6 Problem-Solving Technique 12

Step 1: Problem Statement 13

Step 2: Schematic 13

Step 3: Assumptions and Approximations 13

Step 4: Physical Laws 13

Step 5: Properties 13

Step 6: Calculations 13

Step 7: Reasoning, Verification, and Discussion 13

**Engineering Software Packages** 14

Equation Solvers 15

A Remark on Significant Digits 16

Summary 17

References and Suggested Readings 17

problems 17

PART 1 THERMODYNAMICS 19

Chapter Two

BASIC CONCEPTS OF THERMODYNAMICS 21

2–1 Systems and Control Volumes 22

2–2 Properties of a System 23

Continuum 23

2–3 Density and Specific Gravity 24

2–4 State and Equilibrium 25

The State Postulate 25

2–5 Processes and Cycles 26

The Steady-Flow Process 27

2–6 Temperature and the Zeroth Law of Thermodynamics 27

Temperature Scales 28

2–7 Pressure 31

Variation of Pressure with Depth 32

2–8 Pressure Measurement Devices 35

The Barometer 35

The Manometer 38

Other Pressure Measurement Devices 40

Summary 41

References and Suggested Readings 42

Problems 42

Chapter Three

ENERGY, ENERGY TRANSFER, AND GENERAL ENERGY ANALYSIS 49

3–1 Introduction 50

3–2 Forms of Energy 51

Some Physical Insight into Internal Energy 52

More on Nuclear Energy 54

Mechanical Energy 55

3–3 Energy Transfer by Heat 57

Historical Background on Heat 58

3–4 Energy Transfer By Work 59

Electrical Work 61

3–5 Mechanical Forms Of Work 62

Shaft Work 62

Spring Work 63

Work Done on Elastic Solid Bars 63

Work Associated with the Stretching of a Liquid Film 64

Work Done to Raise or to Accelerate a Body 64

Nonmechanical Forms of Work 65

3–6 The First Law Of Thermodynamics 65

Energy Balance 67

Energy Change of a System, ΔEsystem 67

Mechanisms of Energy Transfer, Ein and Eout 68

3–7 Energy Conversion Efficiencies 72

Efficiencies of Mechanical and Electrical Devices 76

Summary 79

References and Suggested Readings 80

Problems 80

Chapter Four

PROPERTIES OF PURE SUBSTANCES 87

4–1 Pure Substance 88

4–2 Phases of a Pure Substance 88

4–3 Phase-Change Processes of Pure Substances 89

Compressed Liquid and Saturated Liquid 89

Saturated Vapor and Superheated Vapor 90

Saturation Temperature and Saturation Pressure 90

Some Consequences of Tsat and Psat Dependence 92

4–4 Property Diagrams for Phase-Change Processes 93

1 The T-v Diagram 93

2 The P-v Diagram 94

Extending the Diagrams to Include the Solid Phase 95

3 The P-T Diagram 97

The P-v-T Surface 97

4–5 Property Tables 98

Enthalpy—A Combination Property 98

1a Saturated Liquid and Saturated Vapor States 99

1b Saturated Liquid–Vapor Mixture 100

2 Superheated Vapor 103

3 Compressed Liquid 104

Reference State and Reference Values 106

4–6 The Ideal-Gas Equation of State 107

Is Water Vapor an Ideal Gas? 109

4–7 Compressibility Factor—A Measure of Deviation from Ideal- Gas Behavior 110

Summary 114

References and Suggested Readings 114

Problems 115

Chapter Five

ENERGY ANALYSIS OF CLOSED SYSTEMS 123

5–1 Moving Boundary Work 124

Polytropic Process 127

5–2 Energy Balance for Closed Systems 129

5–3 Specific Heats 133

5–4 Internal Energy, Enthalpy, and Specific Heats of Ideal Gases 134

Specific Heat Relations of Ideal Gases 136

5–5 Internal Energy, Enthalpy, and Specific Heats of Solids and Liquids 140

Internal Energy Changes 141

Enthalpy Changes 141

Summary 144

References and Suggested Readings 145

Problems 145

Chapter Six

MASS AND ENERGY ANALYSIS OF CONTROL VOLUMES 157

6–1 Conservation of Mass 158

Mass and Volume Flow Rates 158

Conservation of Mass Principle 159

Mass Balance for Steady-Flow Processes 161

Special Case: Incompressible Flow 162

6–2 Flow Work and the Energy of a Flowing

Fluid 164

Total Energy of a Flowing Fluid 165

Energy Transport by Mass 165

6–3 Energy Analysis of Steady-Flow Systems 167

6–4 Some Steady-Flow Engineering Devices 170

1 Nozzles and Diffusers 170

2 Turbines and Compressors 173

3 Throttling Valves 175

4a Mixing Chambers 176

4b Heat Exchangers 178

5 Pipe and Duct Flow 180

6–5 Energy Analysis of Unsteady-

Flow

Processes 181

Summary 186

References and Suggested Readings 187

Problems 187

Chapter Seven

THE SECOND LAW OF THERMODYNAMICS 203

7–1 Introduction to the Second Law 204

7–2 Thermal Energy Reservoirs 205

7–3 Heat Engines 205

Thermal Efficiency 207

Can We Save Qout? 208

The Second Law of Thermodynamics: Kelvin–Planck

Statement 210

7–4 Refrigerators and Heat Pumps 210

Coefficient of Performance 211

Heat Pumps 212

Performance of Refrigerators, Air Conditioners, and Heat

Pumps 213

The Second Law of Thermodynamics: Clausius

Statement 215

Equivalence of the Two Statements 215

7–5 Reversible and Irreversible Processes 216

Irreversibilities 217

Internally and Externally Reversible Processes 218

7–6 The Carnot Cycle 218

The Reversed Carnot Cycle 220

7–7 The Carnot Principles 220

7–8 The Thermodynamic Temperature Scale 221

7–9 The Carnot Heat Engine 223

The Quality of Energy 225

7–10 The Carnot Refrigerator and Heat Pump 225

Summary 228

References and Suggested Readings 229

Problems 229

Chapter Eight

ENTROPY 239

8–1 Entropy 240

A Special Case: Internally Reversible Isothermal Heat Transfer

Processes 242

8–2 The Increase of Entropy Principle 243

Some Remarks About Entropy 245

8–3 Entropy Change of Pure Substances 246

8–4 Isentropic Processes 249

8–5 Property Diagrams Involving Entropy 250

8–6 What is Entropy? 252

Entropy and Entropy Generation in Daily Life 254

8–7 The T ds Relations 255

8–8 Entropy Change of Liquids and Solids 256

8–9 The Entropy Change of Ideal Gases 259

Constant Specific Heats (Approximate Analysis) 260

Variable Specific Heats (Exact Analysis) 260

Isentropic Processes of Ideal Gases 262

Constant Specific Heats (Approximate Analysis) 262

Variable Specific Heats (Exact Analysis) 263

Relative Pressure and Relative Specific Volume 263

8–10 Reversible Steady-Flow Work 266

Proof that Steady-Flow Devices Deliver the Most and

Consume the Least Work When the Process Is

Reversible 269

8–11 Isentropic Efficiencies of Steady-Flow

Devices 269

Isentropic Efficiency of Turbines 270

Isentropic Efficiencies of Compressors and Pumps 271

Isentropic Efficiency of Nozzles 273

8–12 Entropy Balance 275

Entropy Change of a System, ΔS system 276

Mechanisms of Entropy Transfer, Sin and Sout 276

1 Heat Transfer 276

2 Mass Flow 277

Entropy Generation, Sgen 277

Closed Systems 278

Control Volumes 279

Summary 284

References and Suggested Readings 285

Problems 285

Chapter Nine

POWER AND REFRIGERATION CYCLES 301

9–1 Basic Considerations in the Analysis of Power Cycles 302

9–2 The Carnot Cycle and its Value in Engineering 304

9–3 Air-Standard Assumptions 305

9–4 An Overview of Reciprocating Engines 307

9–5 Otto Cycle: The Ideal Cycle for Spark-Ignition Engines 307

9–6 Diesel Cycle: The Ideal Cycle for Compression-

Ignition Engines 314

9–7 Brayton Cycle: The Ideal Cycle for Gas-Turbine

Engines 317

Development of Gas Turbines 319

Deviation of Actual Gas-Turbine Cycles from Idealized

Ones 321

9–8 The Brayton Cycle with Regeneration 323

9–9 The Carnot Vapor Cycle 325

9–10 Rankine Cycle: The Ideal Cycle for Vapor Power Cycles 326

Energy Analysis of the Ideal Rankine Cycle 327

9–11 Deviation of Actual Vapor Power Cycles

From Idealized Ones 329

9–12 How Can We Increase The Efficiency of The

Rankine Cycle? 331

Lowering the Condenser Pressure (Lowers Tlow,avg) 331

Superheating the Steam to High Temperatures (Increases

Thigh,avg) 332

Increasing the Boiler Pressure (Increases Thigh,avg) 332

9–13 The Ideal Reheat Rankine Cycle 335

9–14 Refrigerators and Heat Pumps 339

9–15 The Reversed Carnot Cycle 340

9–16 The Ideal Vapor-Compression Refrigeration

Cycle 341

9–17 Actual Vapor-Compression Refrigeration

Cycle 343

9–18 Heat Pump Systems 345

Summary 346

References and Suggested Readings 348

Problems 348

PART 2 FLUID MECHANICS 361

Chapter Ten

INTRODUCTION AND PROPERTIES OF FLUIDS 363

10–1 The No-Slip Condition 364

10–2 Classification of Fluid Flows 364

Viscous Versus Inviscid Regions of Flow 365

Internal Versus External Flow 365

Compressible Versus Incompressible Flow 365

Laminar Versus Turbulent Flow 366

Natural (or Unforced) Versus Forced Flow 366

Steady Versus Unsteady Flow 366

One-, Two-, and Three-Dimensional Flows 368

Uniform Versus Nonuniform Flow 369

10–3 Vapor Pressure and Cavitation 369

10–4 Viscosity 371

10–5 Surface Tension and Capillary Effect 375

Capillary Effect 378

Summary 381

References and Suggested Reading 381

Problems 381

Chapter Eleven

FLUID STATICS 387

11–1 Introduction to Fluid Statics 388

11–2 Hydrostatic Forces on Submerged Plane Surfaces 388

Special Case: Submerged Rectangular Plate 391

11–3 Hydrostatic Forces on Submerged Curved Surfaces 393

11–4 Buoyancy and Stability 396

Stability of Immersed and Floating Bodies 399

Summary 401

References and Suggested Reading 401

Problems 401

Chapter Twelve

BERNOULLI AND ENERGY EQUATIONS 409

12–1 The Bernoulli Equation 410

Acceleration of a Fluid Particle 410

Derivation of the Bernoulli Equation 411

Force Balance Across Streamlines 412

Unsteady, Compressible Flow 413

Static, Dynamic, and Stagnation Pressures 413

Limitations on the Use of the Bernoulli Equation 414

Hydraulic Grade Line (HGL) and Energy Grade Line

(EGL) 415

Applications of the Bernoulli Equation 417

12–2 Energy Analysis of Steady Flows 421

Special Case: Incompressible Flow with No Mechanical Work

Devices and Negligible Friction 423

Kinetic Energy Correction Factor, α 424

Summary 428

References and Suggested Reading 428

Problems 428

Chapter Thirteen

MOMENTUM ANALYSIS OF FLOW SYSTEMS 437

13–1 Newton’s Laws 438

13–2 Choosing a Control Volume 439

13–3 Forces Acting on a Control Volume 440

13–4 The Reynolds Transport Theorem 442

An Application: Conservation of Mass 446

13–5 The Linear Momentum Equation 446

Special Cases 448

Momentum-Flux Correction Factor, β 448

Steady Flow 450

Flow with No External Forces 451

Summary 457

References and Suggested Reading 457

Problems 458

Chapter Fourteen

INTERNAL FLOW 465

14–1 Introduction 466

14–2 Laminar and Turbulent Flows 467

Reynolds Number 467

14–3 The Entrance Region 468

Entry Lengths 469

14–4 Laminar Flow in Pipes 470

Pressure Drop and Head Loss 472

Effect of Gravity on Velocity and Flow Rate in Laminar Flow 474

Laminar Flow in Noncircular Pipes 475

14–5 Turbulent Flow in Pipes 478

Turbulent Velocity Profile 478

The Moody Chart and Its Associated Equations 478

Types of Fluid Flow Problems 480

14–6 Minor Losses 486

14–7 Piping Networks and Pump Selection 493

Series and Parallel Pipes 493

Piping Systems with Pumps and Turbines 494

Summary 499

References and Suggested Reading 501

Problems 501

Chapter Fifteen

EXTERNAL FLOW: DRAG AND LIFT 511

15–1 Introduction 512

15–2 Drag and Lift 514

15–3 Friction and Pressure Drag 517

Reducing Drag by Streamlining 518

Flow Separation 519

15–4 Drag Coefficients of Common Geometries 521

Biological Systems and Drag 522

Drag Coefficients of Vehicles 524

Superposition 525

15–5 Parallel Flow Over Flat Plates 527

Friction Coefficient 529

15–6 Flow Over Cylinders and Spheres 531

Effect of Surface Roughness 533

15–7 Lift 535

Finite-Span Wings and Induced Drag 539

Summary 542

References and Suggested Reading 543

Problems 543

PART 3 HEAT TRANSFER 551

Chapter Sixteen

MECHANISMS OF HEAT TRANSFER 553

16–1 Introduction 554

16–2 Conduction 554

Thermal Conductivity 555

Thermal Diffusivity 559

16–3 Convection 561

16–4 Radiation 563

16–5 Simultaneous Heat Transfer Mechanisms 565

Summary 569

References and Suggested Reading 570

Problems 570

Chapter Seventeen

STEADY HEAT CONDUCTION 579

17–1 Steady Heat Conduction in Plane Walls 580

Thermal Resistance Concept 581

Thermal Resistance Network 582

Multilayer Plane Walls 584

17–2 Thermal Contact Resistance 588

17–3 Generalized Thermal Resistance Networks 593

17–4 Heat Conduction in Cylinders and Spheres 595

Multilayered Cylinders and Spheres 597

17–5 Critical Radius of Insulation 601

17–6 Heat Transfer from Finned Surfaces 603

Fin Equation 604

Fin Efficiency 608

Fin Effectiveness 611

Proper Length of a Fin 613

Summary 617

References and Suggested Reading 618

Problems 618

Chapter Eighteen

TRANSIENT HEAT CONDUCTION 635

18–1 Lumped System Analysis 636

Criteria for Lumped System Analysis 637

Some Remarks on Heat Transfer in Lumped Systems 638

18–2 Transient Heat Conduction in Large Plane

Walls, Long Cylinders, and Spheres with Spatial

Effects 640

Nondimensionalized One-Dimensional Transient Conduction Problem 641

Approximate Analytical Solutions 643

18–3 Transient Heat Conduction in Semi-Infinite Solids 650

Contact of Two Semi-Infinite Solids 654

18–4 Transient Heat Conduction in Multidimensional Systems 657

Summary 662

References and Suggested Reading 663

Problems 663

Chapter Nineteen

FORCED CONVECTION 675

19–1 Physical Mechanism of Convection 676

Nusselt Number 678

19–2 Thermal Boundary Layer 678

Prandtl Number 679

19–3 Parallel Flow Over Flat Plates 679

Flat Plate with Unheated Starting Length 681

Uniform Heat Flux 682

19–4 Flow Across Cylinders and Spheres 685

19–5 General Considerations for Pipe Flow 688

Thermal Entrance Region 689

Entry Lengths 691

19–6 General Thermal Analysis 693

Constant Surface Heat Flux ( q • s = constant) 693

Constant Surface Temperature ( T s = constant) 694

19–7 Laminar Flow in Tubes 697

Constant Surface Heat Flux 697

Constant Surface Temperature 698

Laminar Flow in Noncircular Tubes 698

Developing Laminar Flow in the Entrance Region 699

19–8 Turbulent Flow in Tubes 701

Developing Turbulent Flow in the Entrance Region 703

Turbulent Flow in Noncircular Tubes 703

Flow Through Tube Annulus 703

Heat Transfer Enhancement 704

Summary 707

References and Suggested Reading 708

Problems 710

Chapter Twenty

NATURAL CONVECTION 723

20–1 Physical Mechanism of Natural Convection 724

20–2 Equation Of Motion and the Grash of Number 726

The Grashof Number 728

20–3 Natural Convection Over Surfaces 729

Vertical Plates (Ts = constant) 730

Vertical Plates ( q • s = constant) 730

Vertical Cylinders 732

Inclined Plates 732

Horizontal Plates 732

Horizontal Cylinders and Spheres 733

20–4 Natural Convection Inside Enclosures 736

Effective Thermal Conductivity 737

Horizontal Rectangular Enclosures 737

Inclined Rectangular Enclosures 738

Vertical Rectangular Enclosures 738

Concentric Cylinders 739

Combined Natural Convection and Radiation 740

Summary 743

References and Suggested Reading 744

Problems 745

Chapter Twenty one

RADIATION HEAT TRANSFER 757

21–1 Introduction 758

21–2 Thermal Radiation 759

21–3 Blackbody Radiation 760

21–4 Radiative Properties 766

Emissivity 767

Absorptivity, Reflectivity, and Transmissivity 770

Kirchhoff’s Law 772

The Greenhouse Effect 773

21–5 The View Factor 773

21–6 View Factor Relations 776

1 The Reciprocity Relation 777

2 The Summation Rule 779

3 The Superposition Rule 780

4 The Symmetry Rule 782

View Factors Between Infinitely Long Surfaces: The Crossed- Strings Method 783

21–7 Radiation Heat Transfer: Black Surfaces 785

21–8 Radiation Heat Transfer: Diffuse, Gray Surfaces 787

Radiosity 787

Net Radiation Heat Transfer to or from a Surface 787

Net Radiation Heat Transfer Between Any Two Surfaces 788

Methods of Solving Radiation Problems 789

Radiation Heat Transfer in Two-Surface Enclosures 790

Radiation Heat Transfer in Three-Surface Enclosures 792

Summary 795

References and Suggested Reading 796

Problems 797

Chapter Twenty Two

HEAT EXCHANGERS 809

22–1 Types of Heat Exchangers 810

22–2 The Overall Heat Transfer Coefficient 813

Fouling Factor 815

22–3 Analysis of Heat Exchangers 819

22–4 The Log Mean Temperature Difference Method 821

Counterflow Heat Exchangers 822

Multipass and Crossflow Heat Exchangers: Use of a Correction Factor 823

22–5 The Effectiveness–Ntu Method 829

Summary 839

References and Suggested Reading 839

Problems 840

Appendix 1

PROPERTY TABLES AND CHARTS (SI UNITS) 851

TABLE A–1 Molar mass, gas constant, and criticalpoint properties 852

TABLE A–2 Ideal-gas specific heats of various common gases 853

TABLE A–3 Properties of common liquids, solids, and foods 856

TABLE A–4 Saturated water—Temperature table 858

TABLE A–5 Saturated water—Pressure table 860

TABLE A–6 Superheated water 862

TABLE A–7 Compressed liquid water 866

TABLE A–8 Saturated ice–water vapor 867

FIGURE A–9 T-s diagram for water 868

FIGURE A–10 Mollier diagram for water 869

TABLE A–11 Saturated refrigerant-134a—Temperature table 870

TABLE A–12 Saturated refrigerant-134a—Pressure table 872

TABLE A–13 Superheated refrigerant-134a 873

FIGURE A–14 P-h diagram for refrigerant-134a 875

TABLE A–15 Properties of saturated water 876

TABLE A–16 Properties of saturated refrigerant- 134a 877

TABLE A–17 Properties of saturated ammonia 878

TABLE A–18 Properties of saturated propane 879

TABLE A–19 Properties of liquids 880

TABLE A–20 Properties of liquid metals 881

TABLE A–21 Ideal-gas properties of air 882

TABLE A–22 Properties of air at 1 atm pressure 884

TABLE A–23 Properties of gases at 1 atm pressure 885

TABLE A–24 Properties of solid metals 887

TABLE A–25 Properties of solid nonmetals 890

TABLE A–26 Emissivities of surfaces 891

FIGURE A–27 The Moody chart 893

FIGURE A–28 Nelson–Obert generalized compressibility chart 894

Appendix 2

PROPERTY TABLES AND CHARTS (ENGLISH UNITS) 895

TABLE A–1E Molar mass, gas constant, and criticalpoint properties 896

TABLE A–2E Ideal-gas specific heats of various common gases 897

TABLE A–3E Properties of common liquids, solids, and foods 900

TABLE A–4E Saturated water—Temperature table 902

TABLE A–5E Saturated water—Pressure table 904

TABLE A–6E Superheated water 906

TABLE A–7E Compressed liquid water 910

TABLE A–8E Saturated ice–water vapor 911

FIGURE A–9E T-s diagram for water 912

FIGURE A–10E Mollier diagram for water 913

TABLE A–11E Saturated refrigerant-134a—Temperature table 914

TABLE A–12E Saturated refrigerant-134a—Pressure table 915

TABLE A–13E Superheated refrigerant-134a 916

FIGURE A–14E P-h diagram for refrigerant-134a 918

TABLE A–15E Properties of saturated water 919

TABLE A–16E Properties of saturated refrigerant-134a 920

TABLE A–17E Properties of saturated ammonia 921

TABLE A–18E Properties of saturated propane 922

TABLE A–19E Properties of liquids 923

TABLE A–20E Properties of liquid metals 924

TABLE A–21E Ideal-gas properties of air 925

TABLE A–22E Properties of air at 1 atm pressure 927

TABLE A–23E Properties of gases at 1 atm pressure 928

TABLE A–24E Properties of solid metals 930

TABLE A–25E Properties of solid nonmetals 932

Index 933

Nomenclature 947

Conversion Factors and Some Physical Constants 950