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ENGINEERING THERMODYNAMICS THIRD EDITION SI Units Ve r s io n R. K. Rajput E N G I N E E R I N G S E R I E S ENGINEERING THERMODYNAMICS Also  available  : STEAM TABLES and MOLLIER DIAGRAM (S.I. UNITS) Edited  by R.K. RAJPUT Patiala DHARM M-therm\TITLE.PM5 i i ENGINEERING THERMODYNAMICS [For Engineer...

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ENGINEERING

THERMODYNAMICS THIRD EDITION SI Units Ve r s io n R. K. Rajput

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G

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E

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ENGINEERING THERMODYNAMICS

Also  available  : STEAM TABLES and MOLLIER DIAGRAM (S.I. UNITS)

Edited  by R.K. RAJPUT Patiala

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ENGINEERING THERMODYNAMICS [For Engineering Students of All Indian Universities and Competitive Examinations]

S.I. UNITS

By

R.K. RAJPUT M.E. (Heat Power Engg.) Hons.–Gold Medallist ; Grad. (Mech. Engg. & Elect. Engg.) ; M.I.E. (India) ; M.S.E.S.I. ; M.I.S.T.E. ; C.E. (India) Principal (Formerly)

Punjab College of Information Technology PATIALA, Punjab

LAXMI PUBLICATIONS (P) LTD BANGALORE l CHENNAI JALANDHAR

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KOLKATA

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COCHIN

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GUWAHATI

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HYDERABAD

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LUCKNOW

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MUMBAI

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RANCHI

NEW DELHI

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BOSTON, USA

Published by : LAXMI PUBLICATIONS (P) LTD 113, Golden House, Daryaganj, New Delhi-110002 Phone : 011-43 53 25 00 Fax : 011-43 53 25 28 www.laxmipublications.com [email protected] © All rights reserved with the Publishers. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher. ISBN: 978-0-7637-8272-6 3678

Price : Rs. 350.00 Only.

First Edition : 1996 Second Edition : 2003 Third Edition : 2007

Offices : India • • • • • • • • • •

Bangalore (Phone : 080-26 61 15 61) Chennai (Phone : 044-24 34 47 26) Cochin (Phone : 0484-239 70 04) Guwahati (Phones : 0361-254 36 69, 251 38 81) Hyderabad (Phone : 040-24 75 02 47) Jalandhar (Phone : 0181-222 12 72) Kolkata (Phones : 033-22 27 37 73, 22 27 52 47) Lucknow (Phone : 0522-220 95 78) Mumbai (Phones : 022-24 91 54 15, 24 92 78 69) Ranchi (Phone : 0651-230 77 64)

EET-0556-350-ENGG THERMODYNAMICS Typeset at : Goswami Printers, Delhi

USA • Boston 11, Leavitt Street, Hingham, MA 02043, USA Phone : 781-740-4487

C—12751/06/07 Printed at : Ajit Printers, Delhi

Preface to The Third Edition I am pleased to present the third edition of this book. The warm reception which the previous editions and reprints of this book have enjoyed all over India and abroad has been a matter of great satisfaction to me. The entire book has been thoroughly revised ; a large number of solved examples (questions having been selected from various universities and competitive examinations) and ample additional text have been added. Any suggestions for the improvement of the book will be thankfully acknowledged and incorporated in the next edition. —Author

Preface to The First Edition Several books are available in the market on the subject of “Engineering Thermodynamics” but either they are too bulky or are miserly written and as such do not cover the syllabii of various Indian Universities effectively. Hence a book is needed which should assimilate subject matter that should primarily satisfy the requirements of the students from syllabus/examination point of view ; these requirements are completely met by this book. The book entails the following features : — The presentation of the subject matter is very systematic and language of the text is quite lucid and simple to understand. — A number of figures have been added in each chapter to make the subject matter self speaking to a great extent. — A large number of properly graded examples have been added in various chapters to enable the students to attempt different types of questions in the examination without any difficulty. — Highlights, objective type questions, theoretical questions, and unsolved examples have been added at the end of each chapter to make the book a complete unit in all respects. The author’s thanks are due to his wife Ramesh Rajput for rendering all assistance during preparation and proof reading of the book. The author is thankful to Mr. R.K. Syal for drawing beautiful and well proportioned figures for the book. The author is grateful to M/s Laxmi Publications for taking lot of pains in bringing out the book in time and pricing it moderately inspite of heavy cost of the printing. Constructive criticism is most welcome from the readers. —Author

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Contents Chapter

Pages

Introduction to S.I. Units and Conversion Factors Nomenclature

1. INTRODUCTION—OUTLINE OF SOME DESCRIPTIVE SYSTEMS 1.1.

1.2. 1.3.

1.4.

1.5.

Steam Power Plant 1.1.1. Layout 1.1.2. Components of a modern steam power plant Nuclear Power Plant Internal Combustion Engines 1.3.1. Heat engines 1.3.2. Development of I.C. engines 1.3.3. Different parts of I.C. engines 1.3.4. Spark ignition (S.I.) engines 1.3.5. Compression ignition (C.I.) engines Gas Turbines 1.4.1. General aspects 1.4.2. Classification of gas turbines 1.4.3. Merits and demerits of gas turbines 1.4.4. A simple gas turbine plant 1.4.5. Energy cycle for a simple-cycle gas turbine Refrigeration Systems Highlights Theoretical Questions

2. BASIC CONCEPTS OF THERMODYNAMICS 2.1. 2.2. 2.3.

2.4. 2.5. 2.6. 2.7. 2.8.

Introduction to Kinetic Theory of Gases Definition of Thermodynamics Thermodynamic Systems 2.3.1. System, boundary and surroundings 2.3.2. Closed system 2.3.3. Open system 2.3.4. Isolated system 2.3.5. Adiabatic system 2.3.6. Homogeneous system 2.3.7. Heterogeneous system Macroscopic and Microscopic Points of View Pure Substance Thermodynamic Equilibrium Properties of Systems State

(xvi)—(xx) (xxi)—(xxii)

...

1—13

... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

1 1 2 3 4 4 4 4 5 7 7 7 8 8 9 10 10 12 13

...

14—62

... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

14 18 18 18 18 19 19 19 19 19 19 20 20 21 21

( vii )

Chapter 2.9. 2.10. 2.11. 2.12. 2.13. 2.14. 2.15.

2.16.

2.17. 2.18. 2.19.

2.20.

Pages Process Cycle Point Function Path Function Temperature Zeroth Law of Thermodynamics The Thermometer and Thermometric Property 2.15.1. Introduction 2.15.2. Measurement of temperature 2.15.3. The international practical temperature scale 2.15.4. Ideal gas Pressure 2.16.1. Definition of pressure 2.16.2. Unit for pressure 2.16.3. Types of pressure measurement devices 2.16.4. Mechanical type instruments Specific Volume Reversible and Irreversible Processes Energy, Work and Heat 2.19.1. Energy 2.19.2. Work and heat Reversible Work Highlights Objective Type Questions Theoretical Questions Unsolved Examples

3. PROPERTIES OF PURE SUBSTANCES 3.1. 3.2. 3.3. 3.4. 3.5. 3.6. 3.7. 3.8. 3.9. 3.10. 3.11. 3.12. 3.13. 3.14. 3.15. 3.16. 3.17.

Definition of the Pure Substance Phase Change of a Pure Substance p-T (Pressure-temperature) Diagram for a Pure Substance p-V-T (Pressure-Volume-Temperature) Surface Phase Change Terminology and Definitions Property Diagrams in Common Use Formation of Steam Important Terms Relating to Steam Formation Thermodynamic Properties of Steam and Steam Tables External Work Done During Evaporation Internal Latent Heat Internal Energy of Steam Entropy of Water Entropy of Evaporation Entropy of Wet Steam Entropy of Superheated Steam Enthalpy-Entropy (h-s) Chart or Mollier Diagram

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... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

21 22 22 22 23 23 24 24 24 31 33 33 33 34 34 34 45 46 46 46 46 48 58 59 61 61

...

63—100

... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

63 64 66 67 67 68 68 70 72 73 73 73 73 73 74 74 75

( viii )

Chapter 3.18.

Pages Determination of Dryness Fraction of Steam 3.18.1. Tank or bucket calorimeter 3.18.2. Throttling calorimeter 3.18.3. Separating and throttling calorimeter Highlights Objective Type Questions Theoretical Questions Unsolved Examples

4. FIRST LAW OF THERMODYNAMICS 4.1. 4.2. 4.3. 4.4. 4.5. 4.6. 4.7. 4.8.

4.9. 4.10. 4.11. 4.12.

4.13. 4.14. 4.15.

Internal Energy Law of Conservation of Energy First Law of Thermodynamics Application of First Law to a Process Energy—A Property of System Perpetual Motion Machine of the First Kind-PMM1 Energy of an Isolated System The Perfect Gas 4.8.1. The characteristic equation of state 4.8.2. Specific heats 4.8.3. Joule’s law 4.8.4. Relationship between two specific heats 4.8.5. Enthalpy 4.8.6. Ratio of specific heats Application of First Law of Thermodynamics to Non-flow or Closed System Application of First Law to Steady Flow Process Energy Relations for Flow Process Engineering Applications of Steady Flow Energy Equation (S.F.E.E.) 4.12.1. Water turbine 4.12.2. Steam or gas turbine 4.12.3. Centrifugal water pump 4.12.4. Centrifugal compressor 4.12.5. Reciprocating compressor 4.12.6. Boiler 4.12.7. Condenser 4.12.8. Evaporator 4.12.9. Steam nozzle Throttling Process and Joule-Thompson Porous Plug Experiment Heating-Cooling and Expansion of Vapours Unsteady Flow Processes Highlights Objective Type Questions Theoretical Questions Unsolved Examples

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... ... ... ... ... ... ... ...

89 89 92 93 96 97 99 99

... 101—226 ... ... ... ... ... ... ... ... ... ... ... ... ... ...

101 101 101 103 103 104 105 105 105 106 107 107 108 109

... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

109 150 152 155 155 156 157 157 158 159 159 160 161 162 183 210 215 216 219 219

( ix )

Chapter

Pages

5. SECOND LAW OF THERMODYNAMICS AND ENTROPY 5.1. 5.2. 5.3. 5.4.

5.5. 5.6. 5.7. 5.8. 5.9. 5.10. 5.11. 5.12.

5.13. 5.14. 5.15. 5.16. 5.17.

5.18. 5.19.

Limitations of First Law of Thermodynamics and Introduction to Second Law Performance of Heat Engines and Reversed Heat Engines Reversible Processes Statements of Second Law of Thermodynamics 5.4.1. Clausius statement 5.4.2. Kelvin-Planck statement 5.4.3. Equivalence of Clausius statement to the Kelvin-Planck statement Perpetual Motion Machine of the Second Kind Thermodynamic Temperature Clausius Inequality Carnot Cycle Carnot’s Theorem Corollary of Carnot’s Theorem Efficiency of the Reversible Heat Engine Entropy 5.12.1. Introduction 5.12.2. Entropy—a property of a system 5.12.3. Change of entropy in a reversible process Entropy and Irreversibility Change in Entropy of the Universe Temperature Entropy Diagram Characteristics of Entropy Entropy Changes for a Closed System 5.17.1. General case for change of entropy of a gas 5.17.2. Heating a gas at constant volume 5.17.3. Heating a gas at constant pressure 5.17.4. Isothermal process 5.17.5. Adiabatic process (reversible) 5.17.6. Polytropic process 5.17.7. Approximation for heat absorbed Entropy Changes for an Open System The Third Law of Thermodynamics Highlights Objective Type Questions Theoretical Questions Unsolved Examples

6. AVAILABILITY AND IRREVERSIBILITY 6.1. 6.2. 6.3. 6.4.

Available and Unavailable Energy Available Energy Referred to a Cycle Decrease in Available Energy When Heat is Transferred Through a Finite Temperature Difference Availability in Non-flow Systems

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227 227 228 229 229 229

... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

229 230 231 231 233 235 237 237 252 252 252 253 254 255 257 257 258 258 259 260 260 261 262 263 264 265 298 299 302 302

... 306—340 ... ...

306 306

... ...

308 310

(x)

Chapter 6.5. 6.6. 6.7. 6.8.

Pages Availability in Steady-flow Systems Helmholtz and Gibb’s Functions Irreversibility Effectiveness Highlights Objective Type Questions Theoretical Questions Unsolved Examples

7. THERMODYNAMIC RELATIONS 7.1. 7.2. 7.3. 7.4. 7.5. 7.6.

7.7.

General Aspects Fundamentals of Partial Differentiation Some General Thermodynamic Relations Entropy Equations (Tds Equations) Equations for Internal Energy and Enthalpy Measurable Quantities 7.6.1. Equation of state 7.6.2. Co-efficient of expansion and compressibility 7.6.3. Specific heats 7.6.4. Joule-Thomson co-efficient Clausius-Claperyon Equation Highlights Objective Type Questions Exercises

8. IDEAL AND REAL GASES 8.1. 8.2. 8.3. 8.4. 8.5. 8.6. 8.7. 8.8. 8.9. 8.10. 8.11. 8.12.

Introduction The Equation of State for a Perfect Gas p-V-T Surface of an Ideal Gas Internal Energy and Enthalpy of a Perfect Gas Specific Heat Capacities of an Ideal Gas Real Gases Van der Waal’s Equation Virial Equation of State Beattie-Bridgeman Equation Reduced Properties Law of Corresponding States Compressibility Chart Highlights Objective Type Questions Theoretical Questions Unsolved Examples

9. GASES AND VAPOUR MIXTURES 9.1.

Introduction

x

311 311 312 313 336 337 338 338

... 341—375 ... ... ... ... ... ... ... ... ... ... ... ... ... ...

341 341 343 344 345 346 346 347 348 351 353 373 374 375

... 376—410 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

376 376 379 379 380 381 381 390 390 391 392 392 407 408 408 409

... 411—448 ...

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411

( xi )

Chapter 9.2. 9.3. 9.4. 9.5. 9.6. 9.7.

Pages Dalton’s Law and Gibbs-Dalton Law Volumetric Analysis of a Gas Mixture The Apparent Molecular Weight and Gas Constant Specific Heats of a Gas Mixture Adiabatic Mixing of Perfect Gases Gas and Vapour Mixtures Highlights Objective Type Questions Theoretical Questions Unsolved Examples

10. PSYCHROMETRICS 10.1. 10.2. 10.3. 10.4. 10.5. 10.6.

Concept of Psychrometry and Psychrometrics Definitions Psychrometric Relations Psychrometers Psychrometric Charts Psychrometric Processes 10.6.1. Mixing of air streams 10.6.2. Sensible heating 10.6.3. Sensible cooling 10.6.4. Cooling and dehumidification 10.6.5. Cooling and humidification 10.6.6. Heating and dehumidification 10.6.7. Heating and humidification Highlights Objective Type Questions Theoretical Questions Unsolved Examples

11. CHEMICAL THERMODYNAMICS 11.1. 11.2. 11.3. 11.4. 11.5. 11.6. 11.7. 11.8. 11.9. 11.10. 11.11. 11.12. 11.13. 11.14. 11.15.

Introduction Classification of Fuels Solid Fuels Liquid Fuels Gaseous Fuels Basic Chemistry Combustion Equations Theoretical Air and Excess Air Stoichiometric Air Fuel (A/F) Ratio Air-Fuel Ratio from Analysis of Products How to Convert Volumetric Analysis to Weight Analysis How to Convert Weight Analysis to Volumetric Analysis Weight of Carbon in Flue Gases Weight of Flue Gases per kg of Fuel Burnt Analysis of Exhaust and Flue Gas

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... ... ... ... ... ... ... ... ... ...

411 413 414 417 418 419 444 444 445 445

... 449—486 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

449 449 450 455 456 458 458 459 460 461 462 463 463 483 483 484 485

... 487—592 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

487 487 488 489 489 490 491 493 493 494 494 494 494 495 495

( xii )

Chapter

Pages

11.16. 11.17. 11.18. 11.19.

Internal Energy and Enthalpy of Reaction Enthalpy of Formation (∆Hf) Calorific or Heating Values of Fuels Determination of Calorific or Heating Values 11.19.1. Solid and Liquid Fuels 11.19.2. Gaseous Fuels 11.20. Adiabatic Flame Temperature 11.21. Chemical Equilibrium 11.22. Actual Combustion Analysis Highlights Objective Type Questions Theoretical Questions Unsolved Examples

12. VAPOUR POWER CYCLES 12.1. 12.2. 12.3. 12.4. 12.5. 12.6.

Carnot Cycle Rankine Cycle Modified Rankine Cycle Regenerative Cycle Reheat Cycle Binary Vapour Cycle Highlights Objective Type Questions Theoretical Questions Unsolved Examples

13. GAS POWER CYCLES 13.1. 13.2. 13.3. 13.4. 13.5. 13.6. 13.7.

Definition of a Cycle Air Standard Efficiency The Carnot Cycle Constant Volume or Otto Cycle Constant Pressure or Diesel Cycle Dual Combustion Cycle Comparison of Otto, Diesel and Dual Combustion Cycles 13.7.1. Efficiency versus compression ratio 13.7.2. For the same compression ratio and the same heat input 13.7.3. For constant maximum pressure and heat supplied 13.8. Atkinson Cycle 13.9. Ericsson Cycle 13.10. Gas Turbine Cycle-Brayton Cycle 13.10.1. Ideal Brayton cycle 13.10.2. Pressure ratio for maximum work 13.10.3. Work ratio 13.10.4. Open cycle gas turbine-actual brayton cycle 13.10.5. Methods for improvement of thermal efficiency of open cycle gas turbine plant

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... ... ... ... ... ... ... ... ... ... ... ... ...

497 500 501 501 502 504 506 506 507 537 538 539 540

... 543—603 ... ... ... ... ... ... ... ... ... ...

543 544 557 562 576 584 601 601 602 603

... 604—712 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

604 604 605 613 629 639 655 655 655 656 657 660 661 661 663 664 665

...

667

( xiii )

Chapter

Pages 13.10.6. Effect of operating variables on thermal efficiency 13.10.7. Closed cycle gas turbine 13.10.8. Gas turbine fuels Highlights Theoretical Questions Objective Type Questions Unsolved Examples

14. REFRIGERATION CYCLES 14.1.

14.2.

14.3.

14.4.

14.5.

... ... ... ... ... ... ...

... 713—777

Fundamentals of Refrigeration ... 14.1.1. Introduction ... 14.1.2. Elements of refrigeration systems ... 14.1.3. Refrigeration systems ... 14.1.4. Co-efficient of performance (C.O.P.) ... 14.1.5. Standard rating of a refrigeration machine ... Air Refrigeration System ... 14.2.1. Introduction ... 14.2.2. Reversed Carnot cycle ... 14.2.3. Reversed Brayton cycle ... 14.2.4. Merits and demerits of air refrigeration system ... Simple Vapour Compression System ... 14.3.1. Introduction ... 14.3.2. Simple vapour compression cycle ... 14.3.3. Functions of parts of a simple vapour compression system ... 14.3.4. Vapour compression cycle on temperature-entropy (T-s) diagram ... 14.3.5. Pressure-enthalpy (p-h) chart ... 14.3.6. Simple vapour compression cycle on p-h chart ... 14.3.7. Factors affecting the performance of a vapour compression system ... 14.3.8. Actual vapour compression cycle ... 14.3.9. Volumetric efficiency ... 14.3.10. Mathematical analysis of vapour compression refrigeration ... Vapour Absorption System ... 14.4.1. Introduction ... 14.4.2. Simple vapour absorption system ... 14.4.3. Practical vapour absorption system ... 14.4.4. Comparison between vapour compression and vapour absorption systems ... Refrigerants ....