Engineering Thermodynamics by M. David Burghardt PDF

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Engineering Thermodynamics FOURTH EDITION, , M. David Burghardt Hofstra University James A. Harbach U.S. Merchant Marine Academy =t.: HarperCollinsCollegePublishers Engineering Thermodynamics FOURTH EDITION · · " . ·· · To Linda and Phyllis Sponsoring Editor: John Lenchek Project Editor: Randee...

Description

Engineering Thermodynamics FOURTH EDITION,

,

M. David Burghardt Hofstra University

James A. Harbach U.S. Merchant Marine Academy

=t.: HarperCollinsCollegePublishers

Engineering Thermodynamics FOURTH EDITION ·

·

"

.

·· ·

To Linda and Phyllis

Sponsoring Editor: John Lenchek Project Editor: Randee Wire/Carol Zombo Art Director: Julie Anderson Cover Design: Julie Anderson C.over Illustration: Rolin Graphics Production Adininistrator: Brian Branstetter Compositor: Progressive Typographers, Inc. Printer and Binder: R. R. Donnelley & Sons Company Cover Printer: The Lehigh Press, Inc.

Engineering Thermodynamics•.Fourth Edition ,. Copyright © 1993 by HarperCollins College Publishers All rights reserved . .Printed in the United States of America. No part of this bopk may be uSed or reproduced in any manner whatsoever without written permission, except in the case of brief quotations emb,odied in critical articles and reviews. For information address HarperCollins Colle,ge Publishers, 10 East 53rd Street, New York, NY 10022. Library of Congress Cataloging-in-Publication Data

Burghardt, M. David. Engineering thermodynamics. --..4th ed./M. David Burghardt, James A. Harbach. p. em. Rev. ed. of: Engineering thermodynamics with applications. 3rd ed. © 1986. Includes index. ISBN 0-06-041049-3 1. Thermodynamics. I. Harbach, James A. II. Burghardt, M. David Engineering thermodynamics with applications. Ill Title

TJ265.887 1992 621.402' 1-dc20

92-30663 CIP

92

93

94

95

9 8 7 6 5 4 3 2 1

Contents

Preface xiii

Chapter 1

lntroducticm

Chapter 2

Definitions and Units

2.1 Macroscopic and Microscopic Analysis 16 • 2.2 Substances 16 2.3 Systems- Fixed Mass and Fixed Space 16 2.4 Properties, Intensive and Extensive 19 2.5 Phases of a Substance 20 2.6 Processes and Cycles 20 2. 7 Unit Systems 21 2.8 Specific Volume 30

Chapter 3 3.1 3.2 3.3 3.4 3.5

4.1 4.2 4.3 4.4 4.5

70

48

3.6 Further Examples of Energy Analysis 83 Concept Questions 89 Problems (51) 90 Problems (English Units) 96 Computer Problems 100

Properties of Pure Substances

The State Principle 102 Liquid-Vapor Equilibrium 103 Saturated Properties 103 Critical Properties 104 Solid-Liquid-Vapor Equilibrium 105 4.6 Quality 107

15

2.9 Pressure 31 2.10 Equality of Temperature 35 2.11 Zeroth Law of Thermodynamics 35 2.12 Temperature Scales 36 2.13 Guidelines for Thermodynamic Problem Solution 39 Concept Questions 41 Problems (51) 41 Problems (English Units) 45 Computer Problems 47

Conservation of Mass and Energy

Conservation of Mass 49 Energy Forms 51 First Corollary of the First Law Energy as a Property 74 Second Corollary of the First Law 75

Chapter 4

1

4.7 Three-Dimensional Surface 107 4.8 Tables of Thermodynamic Properties 109 Concept Questions 120 Problems (51) 121 Problems (English Units) 125 Computer Problems 128

101

Chapter 5

Ideal and Actual Gases

5.1 Ideal-Gas Equation of State 129 5.2 Nonideai·Gas Equations of State 132 5.3 Specific Heat 140 5.4 Kinetic Theory- Pressure and Specific Heat of an Ideal Gas 145

Chapter 6

Chapter 7

Chapter 9

236 8.9 Heat and Work as Areas 257 8.10 The Second law for Open Systems 258 8.11 Third law of Thermodynamics 262 8.12 Further Considerations 262 Concept Questions 264 Problems (51) 265 Problems (English Units) 270 Computer Problems 274

Availability Analysis

9.1 Introduction 275 9.2 Availability Analysis for Closed Systems 277

207

7.8 Second Corollary of the Second law 226 7.9 Thermodynamic Temperature Scale 226 Concept Questions 229 Problems (51) 229 Problems (English Units) 2 33 Computer Problems 235

Entropy

8.1 Clausius Inequality 237 8.2 Derivation of Entropy 239 8.3 Calculation of Entropy Change for Ideal Gases 241 8.4 Relative Pressure and Relative Specific Volume 245 8.5 Entropy of a Pure Substance 248 8.6 Further Discussion of the Second law for Closed Systems 251 8. 7 Equilibrium State 255 8.8 Carnot Cycle Using T-5 Coordinates 256

160

6.6 Transient Flow 187 Concept Questions 194 Problems (51) 194 Problems (English Units) 201 Computer Problems 205

The Second Law of Thermodynamics and the Carnot Cycle

7.1 Introduction and Overview 208 7.2 The Second Law of Thermodynamics 208 7.3 The Second Law for a Cycle 210 7.4 Carnot Cycle 212 7.5 Mean Effective Pressure 216 7.6 Reversed Carnot Engine 223 7. 7 First Corollary of the Second Law 225

Chapter 8

5.5 Gas Tables 148 Concept Questions 154 Problems (51) 154 Problems (English Units) 157 Computer Problems 158

Energy Analysis of Open and Closed Systems

6.1 ,Equilibrium and Nonequilibrium Processes 160 6.2 Closed Systems 162 6.3 Open Systems 168 6.4 Polytropic Process 179 6.5 Three-Process Cycles 185

129

9.3 Flow Availability 287 9.4 Second-Law Efficiency 293

275

9.5 Available Energy-A Special Case of Availability 298 Concept Questions 304

Chapter 10

Thermodynamic Relationships

10.1 Interpreting Differentials and Partial Derivatives 316 10.2 An Important Relationship 318 10.3 Application of Mathematical Methods to Thermodynamic Relations 320 .1 0.4 Maxwell's Relations 322 10.5 Specific Heats, Enthalpy, and Internal Energy 322 10.6 Clapeyron Equation 327

Chapter 11

Problems (51) 305 Problems (English Units) 310 Computer Problems 314

10.7 Important Physical Coefficients 331 10.8 Reduced Coordinates for Van Der Waals Equation of State 335 Concept Questions 337 Problems (51) 337 Problems (English Units) 339 Computer Problems 340

Nonreacting Ideal-Gas and Gas-Vapor Mixtures

Chapter 12 Reactive Systems Hydrocarbon Fuels 372 Combustion Process 372 Theoretical Air 374 Air /Fuel Ratio 375 Products of Combustion 381 Enthalpy of Formation 386 First-Law Analysis for Steady· State Reacting Systems 387 12.8 Adiabatic Flame Temperature 394 12.9 Enthalpy of Combustion, Heating Value 396

Chapter 13

371

12.10 Second-Law Analysis 399 12.11 Chemical Equilibrium and Dissociation 406 12.12 Steam Generator Efficiency 416 12.13 Fuel Cells 416 Concept Questions 421 Problems (51) 421 Problems (English Units) 427 Computer Problems 430

Internal Combustion Engines

13.1 Introduction 432 13.2 Air Standard Cycles 433 13.3 Actual Diesel and Otto Cycles 453 13.4 Cycle Comparisons 455 13.5 Engine Performance Analysis 456 13.6 Engine Performance Analysis 464

341

Problems (51) 364 Problems (English Units) 367 Computer Problems 370

11.1 Ideal-Gas Mixtures 342 11.2 Gas-Vapor Mixtures 353 11.3 Psychrometer 361 Concept Questions 364

12.1 12.2 12.3 12.4 12.5 12.6 12.7

315

13.7 Wankel Engine 465 13.8 Engine Efficiencies 466 13.9 Power Measurement 468 Concept Questions 474 Problems (51) 475 Problems (English Units) 480 Computer Problems 482

432

Chapter 14 Gas Turbines 14.1 Fundamental Gas Turbine Cycle 483 14.2 Cycle Analysis 484 14.3 Efficiencies 487 14.4 Open-Cycle Analysis 494 14.5 Combustion Efficiency 498 14.6 Regeneration 498

Chapter 15 15.1 15.2 15.3 15.4

15.5 15.6 15.7 15.8 15.9

483 14.7 Reheating and lntercooling 507 14.8 Aircraft Gas Turbines 512 Concept Questions 519 Problems (51) 520 Problems (English Units) 525 Computer Problems 527

Vapor Power Systems

Vapor Power Plants 530 The Carnot Cycle 531 The Ideal Rankine Cycle 532 Factors Contributing to Cycle lrreversibilities and Losses 538 Improving Rankine Cycle Efficiency 542 The Ideal Rankine Reheat Cycle 545 The Ideal Regenerative Rankine Cycle 550 Reheat-Regenerative Cycle 559 Binary Vapor Cycles 565

15.10 Bottoming Cycles and Cogeneration 565 15.11 Combined Gas-Vapor Power Cycles 574 15.12 Steam Turbine Reheat Factor and Condition Curve 579 15.13 Geothermal Energy 581 15.14 Second Law Analysis of Vapor Power Cycles 583 15.15 Actual Heat Balance Considerations 586 Concept Questions 588 Problems (51) 589 Problems (English Units) 597 Computer Problems 603

Chapter 16 Refrigeration and Air Conditioning Systems 16.1 Reversed Carnot Cycle 606 16.2 Refrigerant Considerations 607 16.3 Standard Vapor-Compression Cycle 608 16.4 Vapor Compression System Components 611 16.5 Compressors without Clearance 614 16.6 Reciprocating Compressors with Clearance 615 16.7 Compressor Performance Factors 617 16.8 Actual Vapor Compression Cycle 620 16.9 Multistage Vapor Compression Systems 622

529

16.10 Multievaporators with One Compressor 631 16.11 Capillary Tube Systems 635 16.12 Absorption Refrigeration Systems 637 16.13 Heat Pump 645 16.14 Low Temperature and Liquefaction 646 16.15 Air Conditioning and Refrigeration 648 16.16 Psychrometric Chart 649 16.17 Air Conditioning Processes 650 Concept Questions 660 Problems (51) 661 Problems (English Units) 669 Computer Problems 674

605

Chapter 17

Fluid Flow in Nozzles and Turbomachinery

17.1 17.2

Conservation of Mass 677 Conservation of Momentum 677 17.3 Acoustic Velocity 680 17.4 Stagnation Properties 682 17.5 Mach Number 683 17.6 First Law Analysis 685 17.7 Nozzles 686 17.8 Supersaturation 696 17.9 Diffuser 700 17.10 ShockWaves 703 · 17. 11 Flow Across a Normal Shock 704

Chapter 18

Turbomachine 716 17.15 Fluid-Rotor Energy Transfer 724 Concept Questions 735 Problems (SI} 736 Problems (English Units) Computer Problems 742

Heat Transfer and Heat Exchangers

18.1 Modes of Heat Transfer 744 18.2 Laws of Heat Transfer 744 18.3 Combined Modes of Heat Transfer

17.12 Flow Measurement 712 17.13 Wind Power 713 17.14 Energy Transfer in a

751

18.4 Conduction through a Composite Wall 753 18.5 Conduction in Cylindrical Coordinates 753

18.6 Critical insulation Thickness 758 18.7 Heat Exchangers 759 Concept Questions 773 Problems (SI} 773 Problems (English Units) Computer Problems 777

References List of Symbols Appendix Tables A. 1

A.2

A.3 A.4

A.5 A.6 A.7

A.8

Gas Constants and Specific Heats at Low Pressures and 25'C (77'F) 785 Properties of Air at Low Pressures (51 Units) 786 Products-400% Theoretical Air- at Low Pressures 789 Products- 200% Theoretical Air- at Low Pressures 790 Saturated Steam Temperature Table (51 Units) 792 Saturated Steam Pressure Table (51 Units) 794 Superheated Steam Vapor Table (51 Units) 796 Compressed Liquid Table (51 Units) 798

A.9 A.1 0 A.11 A.12

A.13 A.14

A.15 A.16

Saturated Ammonia Table (51 Units) 800 Superheated Ammonia Ta (51 Units) 802 Saturated Refrigerant 12 · (51 Units) 804 Superheated Refrigerant 1 Table (51 Units) 806 Properties of Air at Low Pressures (English Units) Saturated Steam Tempera Table (English Units} 81; Saturated Steam Pressure (English Units) 814 Superheated Steam Vapr (English Units) 816

A.17 Compressed Liquid Table (English Units) 819 A.18 Saturated Ammonia Table (English Units) 820 A.19 Superheated Ammonia Table (English Units) 821 A.20 Saturated Refrigerant 12 Table (English Units) 827 A.21 Superheated Refrigerant 12 Table (English Units) 829 A.22 Properties of Selected Materials at 20"C (68"F) 833 A.23 Physi.cal Properties of Selected Fluids 834 8.1 Mollier (Enthalpy- Entropy) Diagram for Steam 836 8.2 Temperature-Entropy Diagram for Steam (SI Units) 838 8.3(a) Ammonia-Water Equilibrium Chart (SI Units) 839 8.3(b) Ammonia-Water Equilibrium Chart (English Units) 840

8.4(a) Psychrometric Chart (SI Units)

841

8.4(b) Psychrometric Chart (English Units) 842 C.1

C.2

C.3

C.4

D

Enthalpies of Formation, Gibbs Function of Formation, and Absolute Entropy at 25"C and 1 atm Pressure 843 Ideal-Gas Enthalpy and Absolute Entropy at 1 atm Pressure 844 Enthalpy of Combustion (Heating Value) of Various Compounds 854 Natural Logarithm of Equilibrium Constant K 855 Solving Thermodynamics Problems with the Personal Computer 856

Answers to Selected Problems

863

Index

871

Preface

This text presents a comprehensive and comprehensible treatment of engineering thermodynamics, from its theoretical foundations to its applications in realistic situations. The thermodynamics presented will prepare students for later courses in fluid mechanics and heat transfer. In addition, practicing engineers will find the applications helpful to them in their professional work. The text is appropriate for an introductory undergraduate course in thermodynamics and for a subsequent course in thermodynamic applications. Many features of the text distinguish it from other texts and from previous editions of this text. They include • A systematic approach to problem solving; • An instructor's solutions manual that includes solutions to all problems and that uses the same systematic approach found in the examples; • Over 1500 problems in SI and English units, 90 requiring computer solution, plus 130 solved examples; • Chapter objectives highlighted at the start of each chapter; • Expanded and amplified development of the second law of thermodynamics, stressing availability analysis; • The integration of the use of the personal computer for solving thermodynamics problems based on the use of TK Solver~~> and spreadsheet software; • The inclusion of a disk of TK Solver~~> files that can be used as provided, or modified and merged into models developed to analyze new problems. We believe that this text breaks new ground in the presentation of thermodynamics to undergraduate engineering students. The integration of the use of TK Solver~~> and spreadsheet software is one important aspect of this advance. In addition to including files for determining properties of steam, refrigerant 12, and air, the disk xiii

XIV

PREFACE

supplied with the text includes models for analyzing many thermodynamic processes and cycles. Unlike most other available software, these TK Solver~~> models can be easily modified to analyze new problems. This provides the student with a powerful set of tools for applications in later design courses and in their professional careers. As an indication of the software's power, although it is a long trial-and-error process to determine the percentage and effect of only one product's dissociation in a combustion process, one of the TK Solver~~> models supplied can analyze combustion reactions with up to three simultaneous dissociation reactions. While we believe that the integration of the computer solutions enhances the thermodynamics course, the text is also written to be used without the software. Another key feature that elevates the text is the expanded discussion and analysis of thermodynamic fundamentals and applications. An underlying theme of the text is that understanding energy and energy utilization is vital to the well-being of an industrialized society. This is underscored when alternative energy sources such as solar, geothermal, and wind are discussed. Furthermore, the environmental effects of acid rain and global warming are discussed in the chapter on reactive systems. A new feature of the text is a systematic problem solution methodology that is adhered to in the text and the instructor's solutions manual. This methodology guides students into thinking about the problem before proceeding with its solution. It encourages students to approach the problems logically, to state assumptions used, to detail the step-by-step analysis, to explicitly include units and conversions when numerical values are substituted, and to note in conclusion key points in the solution. We encourage faculty to require their students to follow this format in their problem solutions. The end-of-chapter problems range in complexity from those illustrating basic concepts to more challenging ones involvingjudgment on the part of the student. In the applications chapters, open-ended problems allow the students to investigate alternative solutions. The provided software allows students .to model complex systems, vary parameters, and undertake parameter variation in seeking optimum solutions. In the chapter on refrigeration and air conditioning, the R 12 property models and the psychrometric chart models allow solution of sophisticated HVAC problems. Second-law analysis is ever more important in an era of heightened energy awareness and energy conservation. A thorough development of the second law of thermodynamics is provided in Chapters 7- 9. The concept of entropy production is developed in Chapter 8 and used throughout the application chapters, as are the availability concepts developed in Chapter 9. The ramifications of the second law receive thorough discussion; the student not only performs calculations but understands the implications of the calculated results. We would like to extend our gratitude to the following reviewers, who offered valuable suggestions for the fourth edition: Lynn Bellamy, Arizona State University; Alan J. Brainard, University ofPittsburgh; E. E. Brooks, University ofSaskatchewan; James Bugg, University of Saskatchewan; Clinton R. Carpenter, Mohawk Valley Community College; Daniel Fairchild, Roger Williams College; Walter R. Kaminski, Central Washington University; B. I. Leidy, University of Pittsburgh; Robert A. Medrow, University of Missouri -Rolla; Edwin Pejack, University ofthe Pacific;

PREFACE

XV

Julio A. Santander, Southern College ofTechnology; George Sehi, Sinclair Community College; E. M. Sparrow, University of Minnesota; Amyn S. Teja, Georgia Institute of Technology; Richard M. Wabrek, Idaho State University; and Ross Wilcoxon, South Dakota State University. We would like to acknowledge Todd Piefer of UTS for his assistance and suggestions on improving the TK Solver* models. It is our hope that the text will form a useful part of an educational program in engineering and be a useful reference for the practicing engineer. M. David Burghardt James A. Harbach

1 Introduction

Thermodynamics is the science that is devoted to understanding energy in all its forms, such as mechanical, electrical, chemical, and how energy changes forms, e.g. the transformation of chemical energy into thermal energy, for instance. Thermodynamics is derived from the Greek words therme, meaning heat, and dynamis, meaning strength, particularly applied to motion. Literally, thermodynamics means "heat strength," implying such things as the heat liberated by the burning of wood, coal, or oil. If the word energy is substituted for heat, one can come to grips with the meaning and scope of thermodynamics. It is the science that deals with energy transformations: the conversion of heat into work, or of chemical energy into electrical energy. The power of thermodynamics lies in its ability to be used to analyze a wide range of energy systems using only a few tenets, two primary ones being the First and Second Laws of Thermodynamics. Thermodynamics applies very simple yet encompassing laws to a wide range of energy systems that have major import in our society, for example, energy use in agriculture, electric power generation, and transportation systems. We will examine the following energy conversion systems in more detail: • A steam power plant, fundamental to the generation of electric power. • An inter...