Engineering Thermodynamics

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1 Basic Engineering Thermodynamics A Venkatesh Professor Emeritus, Mechanical Engineering Department East West Institute of Technology, Bangalore, India (Formerly Professor of Mechanical Engineering, IIT Madras) ^ Universities Press

$2 System and Control Volume 3; 1.2.1 System 3; 1.2.2 Control Volume 3; 1.3 Dimensions and Units 4', 1.3.1 Primary Dimensions 4; 1.3.2 Derived Dimensions 4\ 1.3.3 Force 5; 1.$

2 Constant Contents Chapter 1 Fundamental Concepts and Definitions Introduction 1; Thermodynamics 1; Scope of Thermodynamics 1; Microscopic and Macroscopic Thermodynamics 2; Engineering Thermo dynamics 2; 1.2 System and Control Volume 3; System 3; Control Volume 3; 1.3 Dimensions and Units 4', Primary Dimensions 4; Derived Dimensions 4\ Force 5; 1.4 Thermodynamic Properties 6; Intensive Properties 7; Extensive Properties 7; Specific Properties 7; Pressure 7; Specific Volume 11; Density 12; Temperature 12; 1.5 State, Path and Process 13; Thermodynamic State 13; State Diagram 13; State Point 13; Path and Process 13; Isolated System i^; Adiabatic System 14; Quasi-Static Process 14; Non- Cyclic Process 14; 1.5.9' Cyclic Process 14; 1.6 Equilibrium i^; Thermodynamic Equilibrium 14; Mechanical Equilibrium 15; Thermal Equilibrium 15; Chemical Equilibrium 15; 1.7 Illustrative Problems 15; Problems #i Chapter 2 Work Introduction 28; 2.2 Mechanics Definition of Work 28; Power 29; 2.3 Thermodynamic Definition of Work 29; Necessity 29; Definition 50; Sign Convention 30; 2.4 Displacement Work 33; Quasi-Static Processes 33; Evaluation of Displacement Work in Quasi-Static Processes 33; Path and Point Functions 35; 2.5 Displacement Work in Resisted Processes Undergone by Systems of Uniform Pressure 36; Constant Pressure Process 36; Constant Volume Process 37; Process p V 37; Process pvn = Constant 38; Piston Displacement Work 41', 2.6 Displacement Work in Unresisted Processes 44', 2.7 Other Modes of Work 44', Shaft Work 44; Electrical Work 46; 2.8 Illustrative Problems 4 7; Problems tfi Chapter 3 Temperature and Heat Introduction 70; 3.2 Temperature 70; Temperature Equilibrium 71; Zeroth Law of Thermodynamics 71; Significance of the Zeroth Law 72; Unit of Temperature 72; International Fixed Points 73; 3.3 Measurer ment of Temperature Thermometers 74; Constant Volume Gas Thermometer 74; Ideal Gas Temperature Scale 75; Constant Pressure Gas Thernw> meter 77; Mercury-in-Glass Thermometer 77 ; Resistance Thermometer 78; Thermocouple 79; 3.4 Heat 81; Sign Convention 81; Unit

viii Contents of Heat Transfer 82; 3.4.3 A Note of Caution on Heat Transfer 82; 3.5 Illustrative Problems 82; 3.

3 viii Contents of Heat Transfer 82; A Note of Caution on Heat Transfer 82; 3.5 Illustrative Problems 82; 3.6 Comparison between Work and Heat 85; Problems 86 Chapter 4 The First Law of Thermodynamics for Systems Pure Substances Introduction 90; 4.2 Joule's Experiments 90; Mechanical Equivalent of Heat 92; Joule as the Unit of Heat Transfer 92; 4.3 Statement of the First Law of Thermodynamics 93; 4.4 Extension of the First Law of Thermodynamics to Non- Cyclic Processes ENERGY 94; 4.5 More about Energy 95; Definition of Energy and Remarks 95; Energy is a Property of the System 95; The Nature of Energy 96; 4.6 Pure Substance 100; Two-Property Rule for Pure Substances 101; Energy of a Pure Substance 102; Specific Heats of a Pure Substance 102; 4.7 Illustrative Problems 105; Problems 111 Chapter 5 First Law of Thermodynamics for Control Volumes Introduction 115; 5.2 Extension of the First Law for a Control Volume 115; 5.3 Steady-State, Steady-Flow Energy Equation 118; SS, SFEE based on Unit Mass 118; SS, SFEE based on Unit Time 120; SS, SFEE for Control Volumes with Multi-Streams 121; Continuity Equation 123; 5.4 Application of SS, SFEE to some Specific Cases 124; Adiabatic Throttling Process 124; Turbines and Rotary Compressors 125; Heat Transfer Equipment 126; Heat Exchangers 127; Nozzles and Diffusers 129; 5.5 Unsteady Flow 131; 5.6 Illustrative Problems 135; Problems 138 Chapter 6 Heat Engines The Second Law of Thermodynamics Introduction 144', 6.2 Limitations of the First Law of Thermodynamics 144\ 6.3 A Steam Power Plant 146; 6.4 Closed-Cycle Gas Turbine Power Plant 149; 6.5 Refrigerator 150; 6.6 Heat Pump 152; 6.7 Heat Engine 155; Direct Heat Engine 155; Reversed Heat Engine 156; Symbolic Representation of Heat Engines 156; 6.8 The Second Law of Thermodynamics 157; The Kelvin Planck Statement of the Second Law 157; The Clausius Statement of the Second Law of Thermodynamics 158; Equivalence of the Kelvin Planck and Clausius Statements 159; 6.9 Key Points Discussed so Far 161; 6.10 Illustrative Problems 161; Problems 169 Chapter 7 Reversibility and the Thermodynamic Temperature Scale Introduction 171; 7.2 Reversible Heat Engine 172; Importance and Super iority of a Reversible Heat Engine 175; 7.3 Reversible Process 179; Defini tion of a Reversible Process 179; 7.4 Irreversible Process 179; Friction 180;

Contents ix 7.4.2 Unresisted Expansion 181; 7.4.3 Heat Transfer with Finite Temperature dif ference 181; 7.4.4 Combustion 182; 7.4.5 Mixing 182; 7.5 Carnot Heat Engine 182; 7.5.1 Remarks on Carnot's Engine 184; 7.

4 Contents ix Unresisted Expansion 181; Heat Transfer with Finite Temperature dif ference 181; Combustion 182; Mixing 182; 7.5 Carnot Heat Engine 182; Remarks on Carnot's Engine 184; 7.6 Internal and External Reversibil ities 185; 7.7 Thermodynamic Temperature Scale 186; The Concept 186; Definition of the Thermodynamic Temperature Scale 189; Unit of Thermo dynamic Temperature 189; 7.8 Illustrative Problems 192; Summary 199; Problems 200 Chapter 8 Entropy Available and Unavailable Energy Introduction 204; 8.2 Some Important Statements on 204 ; State ment 1: Clausius Inequality 205; Statement 2 207; Statement 3 208; 8.3 Entropy 209; Remarks on Entropy 210; Similarities between Energy and Entropy 210; Entropy as a Coordinate 213; Entropy as a Quanti tative test for Irreversibility 214; Reversible and Irreversible Adiabatic Processes 216; Principle of Increase of Entropy 219; Entropy as a Quantitative Test of Irreversibility 219; 8.4 Evaluation of Entropy Change 220; 8.5 Carnot Cycle on the T-S Diagram 227; 8.6 Available and Unavailable Energy 228; Relation between Increase in Unavailable Energy and Increase in Entropy 232; Summary 235; 8.7 Illustrative Problems 236; Problems 246 Chapter 9 Ideal Gas and Ideal Gas Mixtures Introduction 251; 9.2 Ideal Gas 251; Universal Gas Constant 252; Internal Energy and Enthalpy of an Ideal Gas 253; Specific Heats of an Ideal Gas 256; Relation among Specific Heats and Gas Constant 256; Perfect Gas and Semi-Perfect Gas 256; 9.3 Analysis of Some Reversible Processes 259; Reversible Constant Pressure Process 259; Reversible Constant Vol ume Process 260; Reversible Hyperbolic Process 261; Reversible Polytropic Process 262; Diagrammatic Representation of Processes 265; Relationship among p, V and T in a Reversible Polytropic Process 266; Calculation of Entropy 269; 9.4 Ideal Gas Mixture 273; Introduction 273; 9.5 Analysis of Gas Mix tures for their Composition 273; Gravimetric Analysis 273; Volumetric or Molar Analysis 274; Dalton's Law of Additive Pressures 275; Amagat's Law of Additive Volumes 276; Mole-Fractions and Volume-Fractions 277; Relation between Mass-Fraction and Mole-Fraction 277; 9.6 Properties of a Gaseous Mixture in terms of Properties of Individual Constituents 278; Apparent Molar Mass (M) and Gas Constant (R) 278; Specific Prop erties 281; 9.7 Properties of Gas Mixture Derived by Mixing Ideal Gases at Different Pressures and Temperatures 285; Adiabatic Mixing of Gases Initially Existing in Separate Containers 285; Non-Adiabatic Mixing 287; Mixing of Gases in Steady Flow 289; 9.9 Illustrative Problems 291; Problems 310

5 X Contents Chapter 10 Properties of Pure Substance Water Introduction 319; 10.2 Constant-Pressure Heating and Formation of Steam 320; Triple Point 324; Critical Point 324; Enthalpy Change during Constant-Pressure Heating 324; 10.3 Frequently Used Terms and their Definitions 325; 10.4 Phase Change Diagrams 327; p-v Diagram 327; Mollier Diagram 331; Dryness Fraction 332; Evaluation of Other Properties in the Mixture Region 334; Table of Properties for Water 334; How to Fix the States in Different Phase Regions and Evaluate other Prop erties 349; Experimental Determination of Dryness Fraction of Steam 356; 10.5 Analyses of Some Processes Undergone by Steam 359; 10.6 Illustrative Problems 364; Problems 387 Chapter 11 Real Gas Introduction 392; 11.2 Real Gas Compressibility Factor 392; 11.3 Reduced Properties Law of Corresponding States 394; H-4 Generalized Compressibility Chart 397; 11.5 Other Equations of State 399; van der Waals Equation of State 399; Redlich and Kwong Equation of State 405; Beattie-Bridgeman Equation 405; Virial Equations of State 406; Problems 408 Chapter 12 Fuels and Combustion Introduction 410; 12.2 Fuels 410; Fuel Analysis 411; 12.3 Com bustion 413; Complete Combustion 414', Incomplete Combustion 414j Stoichiometric Air 414', Dry Air 415; Estimation of Stoichiomet ric Air 415; Excess Air 417; % Theoretical Air 417; 12.4 Analysis of Combustion Products 419; The Orsat Apparatus ^19; Finding Actual Air using Orsat Analysis 421; 12.5 First Law of Thermodynam ics for a System Applied to Combustion 4%6; U t Diagram for a Combustion Process 4^7; Internal Energy of Reaction 429; 12.6 First Law of Thermody namics for a Control Volume Applied to Combustion 430; H t Diagram for a Combustion Process 430; Enthalpy of Reaction 431; 12.7 Relation between AH'pt and Af7^ 433; Effect of Phase on AH' and AU' 434; 12.8 Enthalpy of Formation 436; 12.9 Adiabatic Combustion Temperature 439; Calorific Value 442; Illustrative Problems 443; Problems 455 Objective Type Questions Bibliography Index

THERMODYNAMICS SSC-JE STAFF SELECTION COMMISSION MECHANICAL ENGINEERING STUDY MATERIAL THERMODYNAMICS THERMODYNAMICS THERMODYNAMICS

THERMODYNAMICS SSC-JE STAFF SELECTION COMMISSION MECHANICAL ENGINEERING STUDY MATERIAL THERMODYNAMICS THERMODYNAMICS THERMODYNAMICS 1 SSC-JE STAFF SELECTION COMMISSION MECHANICAL ENGINEERING STUDY MATERIAL 2 Syllabus: Thermal Engineering (Thermodynamics) Properties of Pure Substances : p-v & P-T diagrams of pure substance like H 2