thermal engineering
Sadhu Singh
Former Professor and Head Mechanical Engineering Department and
Dean, Faculty of Engineering and Technology
Govind Ballabh Pant University of Agriculture and Technology, Uttarakhand and
Former Director (Colleges), Punjab Technical University, Jalandhar, Punjab
Sukumar Pati
Assistant Professor Department of Mechanical Engineering
National Institute of Technology Silchar, Assam
Copyright © 2018 Pearson India Education Services Pvt. Ltd
Published by Pearson India Education Services Pvt. Ltd, CIN: U72200TN2005PTC057128.
No part of this eBook may be used or reproduced in any manner whatsoever without the publisher’s prior written consent.
This eBook may or may not include all assets that were part of the print version. The publisher reserves the right to remove any material in this eBook at any time.
ISBN 978-93-528-6668-7
eISBN 9789353063320
Head Office: 15th Floor, Tower-B, World Trade Tower, Plot No. 1, Block-C, Sector 16, Noida 201 301, Uttar Pradesh, India.
Registered Office: 4th Floor, Software Block, Elnet Software City, TS 140, Block 2 & 9, Rajiv Gandhi Salai, Taramani, Chennai - 600 113, Tamil Nadu, India.
Fax: 080-30461003, Phone: 080-30461060
Website: in.pearson.com, Email: companysecretary.india@pearson.com
Dedicated to my Parents
Dedicated to my beloved Parents
Late Sakti Pada Pati and Usha Rani Pati
—Sadhu Singh
—Sukumar Pati
This page is intentionally left blank
Preface
Chapter 1 Fuels and Combustion
1.1 Introduction 1
1.2 Classification of Fuels 1
1.3 Solid Fuels 2
1.3.1 Primary Fuels 2
1.3.2 Secondary Fuels 3
1.3.3 Desirable Properties of Coal 3
1.3.4 Ranking of Coal 4
1.3.5 Grading of Coal 4
1.4 Liquid Fuels 4
1.4.1 Advantages and Disadvantages of Liquid Fuels Over Solid Fuels 5
1.4.2 Calorific Value of Liquid Fuels 5
1.4.3 Desirable Properties of Liquid Fuels 5
1.5 Gaseous Fuels 6
1.5.1 Calorific Value of Gaseous Fuels 6
1.5.2 Advantages and Disadvantages of Gaseous Fuels 7
1.5.3 Important Properties of Gaseous Fuels 7
1.6 Liquefied Gases 7
1.6.1 Liquefied Petroleum Gas 8
1.6.2 Liquefied or Compressed Natural Gas 8
1.7 Biofuels 8
1.8 Analysis of Fuels 9
1.8.1 Proximate Analysis 9
1.8.2 Ultimate Analysis 9
1.9 Calorific Value of Fuels 9
1.10 Combustion of Fuels 10
1.11 Combustion of Hydrocarbon Fuel 11
1.12 Minimum Air Required for Complete Combustion of Solid/Liquid Fuels 11
1.13 Conversion of Volumetric Analysis to Mass (or Gravimetric) Analysis and Vice-Versa 12
1.14 Determination of Air Supplied 13
1.14.1 Percentage of Carbon by Mass in Fuel and Volumetric Analysis is Known 13
1.14.2 Excess Air Supplied 14
1.15 Determination of Percentage of Carbon in Fuel Burning to CO and CO2 14
1.16 Determination of Minimum Quantity of Air Required for Complete Combustion of Gaseous Fuel 15
1.17 Determination of Excess Air Supplied for Gaseous Fuel 15
1.18 Flue Gas Analysis 16
1.18.1 Orsat Apparatus Construction 16
1.19 Bomb Calorimeter 17
1.19.1 Construction 17
1.19.2 Working 17
1.19.3 Cooling Correction 19
1.20 Boys Gas Calorimeter 19
1.20.1 Construction 19
1.20.1 Working 20
Summary for Quick Revision · Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 2 Properties of Steam 51
2.1 Pure Substance 51
2.2 Constant Pressure Formation of Steam 51
2.3 Properties of Steam 52
2.4 Steam Tables 55
2.5 Temperature−Entropy Diagram for Water and Steam 55
2.6 Enthalpy−Entropy or Mollier Diagram of Steam 56
2.7 Various Processes for Steam 57
2.7.1 Constant Volume Process 57
2.7.2 Constant Pressure Process 58
2.7.3 Isothermal Process 59
2.7.4 Hyperbolic Process 59
2.7.5 Reversible Adiabatic or Isentropic Process 60
2.7.6 Polytropic Process 61
2.7.7 Throttling Process 62
2.8 Determination of Dryness Fraction of Steam 62
2.8.1 Barrel Calorimeter 63
2.8.2 Separating Calorimeter 64
2.8.3 Throttling Calorimeter 65
2.8.4 Combined Separating and Throttling Calorimeter 66 Summary for Quick Revision · Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 3
Steam Generators 87
3.1 Introduction 87
3.2 Classification of Steam Generators 87
3.3 Comparison of Fire Tube and Water Tube Boilers 88
3.4 Requirements of a Good Boiler 89
3.5 Factors Affecting Boiler Selection 89
3.6 Description of Boilers 89
3.6.1 Fire Tube Boilers 89
3.6.2 Water Tube Boilers 93
3.7 High Pressure Boilers 94
3.7.1 Boiler Circulation 95
3.7.2 Advantages of Forced Circulation Boilers 95
3.7.3 LaMont Boiler 96
3.7.4 Benson Boiler 97
3.7.5 Loeffler Boiler 97
3.7.6 Schmidt-Hartmann Boiler 98
3.7.7 Velox Boiler 98
3.7.8 Once-through Boiler 99
3.8 Circulation 99
3.9 Steam Drum 100
3.9.1 Mechanism of Separation of Moisture in Drum 100
3.10 Fluidised Bed Boiler 102
3.10.1 Bubbling Fluidised Bed Boiler (BFBB) 102
3.10.2 Advantages of BFBB 103
3.11 Boiler Mountings 103
3.11.1 Water Level Indicator 104
3.11.2 Pressure Gauge 104
3.11.3 Steam Stop Valve 105
3.11.4 Feed Check Valve 105
3.11.5 Blow-Down Cock 106
3.11.6 Fusible Plug 106
3.11.7 Safety Valves 107
3.11.8 High Steam and Low Water Safety Valve 108
3.12 Boiler Accessories 109
3.12.1 Air Preheater 110
3.12.2 Economiser 111
3.12.3 Superheater 112
3.13 Steam Accumulators 113
3.13.1 Variable Pressure Accumulator 113
3.13.2 Constant Pressure Accumulator 114
3.14 Performance of Steam Generator 115
3.14.1 Evaporation Rate 115
3.14.2 Performance 115
3.14.3 Boiler Thermal Efficiency 116
3.14.4 Heat Losses in a Boiler Plant 116
3.14.5 Boiler Trial and Heat Balance Sheet 117
3.15 Steam Generator Control 130
3.16 Electrostatic Precipitator 131
3.17 Draught 136
3.17.1 Classification of Draught 136
3.17.2 Natural Draught 136
3.17.3 Height and Diameter of Chimney 137
3.17.4 Condition for Maximum Discharge Through Chimney 138
3.17.5 Efficiency of Chimney 139
3.17.6 Advantages and Disadvantages of Natural Draught 140
3.17.7 Draught Losses 140
3.17.8 Artificial Draught 140
3.17.9 Comparison of Forced and Induced Draughts 142
3.17.10 Comparison of Mechanical and Natural Draughts 142
3.17.11 Balanced Draught 142
3.17.12 Steam Jet Draught 143
Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 4 Steam Power Cycles 161
4.1 Introduction 161
4.2 Carnot Vapour Cycle 161
4.2.1 Drawbacks of Carnot Cycle 163
4.3 Rankine Cycle 165
4.3.1 Analysis of Rankine Cycle 166
4.3.2 Effect of Boiler and Condenser Pressure 168
4.4 Methods of Improving Efficiency 170
4.4.1 Reheat Cycle 170
4.4.2 Effect of Pressure Drop in the Reheater 171
4.5 Regeneration 174
4.5.1 Regenerative Cycle with Open Heaters 176
4.5.2 Regenerative Cycle with Closed Heaters 177
4.6 Reheat-Regenerative Cycle 182
4.7 Properties of an Ideal Working Fluid 183
4.8 Binary Vapour Cycles 184
4.9 Combined Power and Heating Cycle-Cogeneration 187
Summary for Quick Revision · Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 5 Steam Engines 214
5.1 Introduction 214
5.2 Classification of Steam Engines 214
5.3 Constructional Features of a Steam Engine 215
5.3.1 Steam Engine Parts 216
5.4 Terminology Used in Steam Engine 217
5.5 Working of a Steam Engine 218
5.6 Rankine Cycle 219
5.7 Modified Rankine Cycle 221
5.8 Hypothetical or Theoretical Indicator Diagram 222
5.9 Actual Indicator Diagram 223
5.10 Mean Effective Pressure 224
5.10.1 Without Clearance 224
5.10.2 With Clearance 225
5.10.3 With Clearance and Compression 227
5.10.4 With Clearance and Polytropic Expansion and Compression 228
5.11 Power Developed and Efficiencies 230
5.11.1 Indicated Power 230
5.11.2 Brake Power 231
5.11.3 Efficiencies of Steam Engine 232
5.12 Governing of Steam Engines 232
5.13 Saturation Curve and Missing Quantity 243
5.14 Heat Balance Sheet 244
5.15 Performance Curves 246
Summary for Quick Revision · Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 6 Flow Through Steam Nozzles
6.1 Introduction 253
6.2 Continuity Equation 254
6.3 Velocity of Flow of Steam Through Nozzles 254
6.3.1 Flow of Steam Through the Nozzle 255
6.4 Mass Flow Rate of Steam 255
6.5 Critical Pressure Ratio 256
6.6 Maximum Discharge 257
6.7 Effect of Friction on Expansion of Steam 258
253
6.8 Nozzle Efficiency 259
6.9 Supersaturated or Metastable Flow Through a Nozzle 260
6.10 Isentropic, One-Dimensional Steady Flow Through a Nozzle 269
6.10.1 Relationship between Actual and Stagnation Properties 270
6.11 Mass Rate of Flow Through an Isentropic Nozzle 273
6.11.1 Effect of Varying the Back Pressure on Mass Flow Rate 274
6.12 Normal Shock in an Ideal Gas Flowing Through a Nozzle 277 Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 7 Steam Turbines
7.1 Principle of Operation of Steam Turbines 316
7.2 Classification of Steam Turbines 316
7.3 Comparison of Impulse and Reaction Turbines 318
7.4 Compounding of Impulse Turbines 319
7.5 Velocity Diagrams for Impulse Steam Turbine 321
7.5.1 Condition for Maximum Blade Efficiency 324
7.5.2 Maximum Work Done 325
7.5.3 Velocity Diagrams for Velocity Compounded Impulse Turbine 325
7.5.4 Effect of Blade Friction on Velocity Diagrams 327
7.5.5 Impulse Turbine with Several Blade Rings 328
7.6 Advantages and Limitations of Velocity Compounding 329
7.6.1 Advantages 329
7.6.2 Limitations 329
7.7 Velocity Diagrams for Impulse-Reaction Turbine 330
7.8 Reheat Factor 333
7.9 Losses in Steam Turbines 335
7.10 Turbine Efficiencies 335
7.11 Governing of Steam Turbines 336
7.12 Labyrinth Packing 338
7.13 Back Pressure Turbine 339
7.14 Pass Out or Extraction Turbine 340
7.15 Co-Generation 341
7.16 Erosion of Steam Turbine Blades 355 Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 8 Steam Condensers
8.1 Definition
8.3 Elements of Steam Condensing Plant 387
8.4 Types of Steam Condensers 388
8.4.1 Jet Condensers 388
8.4.2 Surface Condensers 390
8.5 Requirements of Modern Surface Condensers 393
8.6 Comparison of Jet and Surface Condensers 393
8.6.1 Jet Condensers 393
8.6.2 Surface Condensers 394
8.7 Vacuum Measurement 394
8.8 Dalton’s Law of Partial Pressures 395
8.9 Mass of Cooling Water Required in a Condenser 396
8.10 Air Removal from the Condenser 397
8.10.1 Sources of Air Infiltration in Condenser 397
8.10.2 Effects of Air Infiltration in Condensers 397
8.11 Air Pump 398
8.11.1 Edward’s Air Pump 398
8.12 Vacuum Efficiency 399
8.13 Condenser Efficiency 399
8.14 Cooling Tower 399
Summary for Quick Revision · Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 9 Gas Power Cycles
9.1 Introduction 423
9.2 Piston-cylinder Arrangement 423
9.3 Carnot Cycle 425
9.4 Stirling Cycle 426
9.5 Ericsson Cycle 427
9.6 Atkinson Cycle 428
9.7 Otto Cycle (Constant Volume Cycle) 429
9.8 Diesel Cycle 431
9.9 Dual Cycle 434
9.10 Brayton Cycle 436
9.11 Comparison Between Otto, Diesel, and Dual Cycles 438 Fill in the Blanks · Answers · True or False · Answers · Multiplechoice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 10 Internal Combustion Engine Systems
10.1 Introduction 485
10.2 Classification of Internal Combustion Engines 485
10.3 Construction Features 487
10.4 Working of IC Engines 489
10.4.1 Four-stroke Spark-ignition Engine 489
10.4.2 Four-stroke Compression-ignition Engine 490
10.4.3 Two-stroke Spark-ignition Engine 491
10.4.4 Two-stroke Compression-ignition Engine 491
10.5 Comparison of Four-stroke and Two-stroke Engines 492
10.6 Comparison of SI and CI Engines 493
10.7 Merits and Demerits of Two-stroke Engines Over Four-stroke Engines 494
10.7.1 Merits 494
10.7.2 Demerits 494
10.8 Valve Timing Diagrams 495
10.8.1 Four-stroke SI Engine 495
10.8.2 Four-stroke CI Engine 495
10.8.3 Two-stroke SI Engine 495
10.8.4 Two-stroke CI Engine 497
10.9 Scavenging Process 498
10.10 Applications of IC Engines 499
10.11 Theoretical and Actual p-v Diagrams 500
10.11.1 Four-stroke Petrol Engine 500
10.11.2 Four-stroke Diesel Engine 501
10.11.3 Two-stroke Petrol Engine 503
10.11.4 Two-stroke Diesel Engine 504
10.12 Carburetion 505
10.12.1 Simple Carburettor 506
10.12.2 Compensating Jet 506
10.12.3 Theory of Simple Carburettor 507
10.12.4 Limitations of Single Jet Carburettor 510
10.12.5 Different Devices Used to Meet the Requirements of an Ideal Carburettor 511
10.12.6 Complete Carburettor 511
10.13 Fuel Injection Systems in SI Engines 527
10.13.1 Continuous Port Injection System (Lucas Mechanical Petrol Injection System) 527
10.13.2 Electronic Fuel Injection System 528
10.13.3 Rotary Gate Meter Fuel Injection System 530
10.14 Fuel Injection in CI Engines 531
10.14.1 Types of Injection Systems 531
10.14.2 Design of Fuel Nozzle 535
10.15 Fuel Ignition 540
10.15.1 Requirement of Ignition System 540
10.15.2 Ignition Systems 541
10.16 Combustion in IC Engines 552
10.16.1 Stages of Combustion in SI Engines 553
10.16.2 Ignition Lag (or Delay) in SI Engines 556
10.16.3 Factors Affecting the Flame Propagation 557
10.16.4 Phenomena of Knocking/Detonation in SI Engines 561
10.16.5 Factors Influencing Detonation/Knocking 562
10.16.6 Methods for Suppressing Knocking 564
10.16.7 Effects of Knocking/Detonation 564
10.17 Combustion Chambers for SI Engines 565
10.17.1 Basic Requirements of a Good Combustion Chamber 565
10.17.2 Combustion Chamber Design Principles 565
10.17.3 Combustion Chamber Designs 566
10.18 Combustion in CI Engines 567
10.18.1 Stages of Combustion 567
10.18.2 Delay Period or Ignition Delay 568
10.18.3 Variables Affecting Delay Period 569
10.19 Knocking in CI Engines 570
10.19.1 Factors Affecting Knocking in CI Engines 571
10.19.2 Controlling the Knocking 571
10.19.3 Comparison of Knocking in SI and CI Engines 572
10.20 Combustion Chambers for CI Engines 574
10.21 Lubrication Systems 577
10.21.1 Functions of a Lubricating System 577
10.21.2 Desirable Properties of a Lubricating Oil 577
10.21.3 Lubricating Systems Types 577
10.21.4 Lubricating System for IC Engines 579
10.21.5 Lubrication of Different Engine Parts 581
10.22 Necessity of IC Engine Cooling 584
10.22.1 Types of Cooling Systems 584
10.22.2 Precision Cooling 591
10.22.3 Dual Circuit Cooling 591
10.22.4 Disadvantages of Overcooling 591
10.23 Engine Radiators 592
10.23.1 Radiator Matrix 592
10.23.2 Water Requirements of Radiator 593
10.23.3 Fans 594
10.24 Cooling of Exhaust Valve 595
10.25 Governing of IC Engines 596
10.26 Rating of SI Engine Fuels-Octane Number 597
10.26.1 Anti-knock Agents 598
10.26.2 Performance Number 599
10.27 Highest Useful Compression Ratio 599
10.28 Rating of CI Engine Fuels 601
10.29 IC Engine Fuels 601
10.29.1 Fuels for SI Engines 602
10.29.2 Fuels for CI Engines 603
10.30 Alternative Fuels for IC Engines 603
10.30.1 Alcohols 604
10.30.2 Use of Hydrogen in CI Engines 604
10.30.3 Biogas 605
10.30.4 Producer (or Water) Gas 605
10.30.5 Biomass-generated Gas 605
10.30.6 LPG as SI Engine Fuel 605
10.30.7 Compressed Natural Gas 606
10.30.8 Coal Gasification and Coal Liquefaction 606
10.30.9 Non-edible Vegetable Oils 607
10.30.10 Non-edible Wild Oils 607
10.30.11 Ammonia 607
Summary for Quick Revision · Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 11 Performance of Internal Combustion Engines 622
11.1 Performance Parameters 622
11.2 Basic Engine Measurements 624
11.3 Heat Balance Sheet 626
11.4 Willan’s Line Method 626
11.5 Morse Test 627
11.6 Performance of SI Engines 627
11.6.1 Performance of SI Engine at Constant Speed and Variable Load 629
11.7 Performance of CI Engines 630
11.8 Performance Maps 631
11.9 Measurement of Air Consumption by Air-box Method 636
11.10 Measurement of Brake Power 638
11.11 Supercharging of IC Engines 658
11.11.1 Thermodynamic Cycle 658
11.11.2 Supercharging of SI Engines 659
11.11.3 Supercharging of CI Engines 660
11.11.4 Effects of Supercharging 660
11.11.5 Objectives of Supercharging 661
11.11.6 Configurations of a Supercharger 661
11.11.7 Supercharging of Single Cylinder Engines 662
11.12 SI Engine Emissions 663
11.12.1 Exhaust Emissions 665
11.12.2 Evaporative Emission 666
11.12.3 Crankcase Emission 666
11.12.4 Lead Emission 666
11.13 Control of Emissions in SI Engine 666
11.14 Crank Case Emission Control 669
11.15 CI Engine Emissions 669
11.15.1 Effect of Engine Type on Diesel Emission 670
11.15.2 Control of Emission from Diesel Engine 673
11.15.3 NOx−Emission Control 674
11.16 Three-Way Catalytic Converter 676
11.16.1 Function of a Catalyst in a Catalytic Converter 676
11.17 Environmental Problems Created by Exhaust Emission from IC Engines 677
11.18 Use of Unleaded Petrol 678
11.18.1 Use of Additives 678
Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 12 Reciprocating Air Compressors 690
12.1 Introduction 690
12.2 Uses of Compressed Air in Industry 691
12.3 Working Principle of Single-stage Reciprocating Compressor 691
12.4 Terminology 691
12.5 Types of Compression 692
12.5.1 Methods for Approximating Compression Process to Isothermal 692
12.6 Single-Stage Compression 693
12.6.1 Required Work 693
12.6.2 Volumetric Efficiency 696
12.6.3 Isothermal Efficiency 697
12.6.4 Adiabatic Efficiency 699
12.6.5 Calculation of Main Dimensions 699
12.7 Multi-Stage Compression 699
12.7.1 Two-stage Compressor 700
12.7.2 Heat Rejected to the Intercooler 702
12.7.3 Cylinder Dimensions 703
12.7.4 Intercooler and Aftercooler 703
12.8 Indicated Power of a Compressor 705
12.9 Air Motors 705
12.10 Indicator Diagram 706
12.11 Heat Rejected 707
12.12 Control of Compressor 707
Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter
13
Rotary Air Compressors 735
13.1 Introduction 735
13.2 Working Principle of Different Rotary Compressors 735
13.2.1 Roots Blower or Lobe Compressor 735
13.2.2 Vanes Type Blower 737
13.2.3 Lysholm Compressor 737
13.2.4 Screw Compressor 738
13.3 Comparison of Rotary and Reciprocating Compressors 740 Summary for Quick Revision · Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 14 Centrifugal Air Compressors
14.1 Introduction 744
14.2 Constructional Features 744
14.3 Working Principle 745
14.4 Variation of Velocity and Pressure 745
14.5 Types of Impellers 745
14.6 Comparison of Centrifugal and Reciprocating Compressors 746
14.7 Comparison of Centrifugal and Rotary Compressors 746
14.8 Static and Stagnation Properties 747
14.9 Adiabatic and Isentropic Processes 748
14.9.1 Isentropic Efficiency 749
14.10 Velocity Diagrams 749
14.10.1 Theory of Operation 750
14.10.2 Width of Blades of Impeller and Diffuser 753
14.11 Slip Factor and Pressure Coefficient 754
14.12 Losses 755
14.13 Effect of Impeller Blade Shape on Performance 755
14.14 Diffuser 756
14.15 Pre-Whirl 757
14.16 Performance Characteristics 757
14.17 Surging and Choking 760
Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 15 Axial Flow Air Compressors
15.1 Introduction 789
15.2 Constructional Features 789
15.3 Working Principle 790
15.4 Simple Theory of Aerofoil Blading 790
15.5 Velocity Diagrams 792
15.6 Degree of Reaction 794
15.7 Pressure Rise in Isentropic Flow Through a Cascade 794
15.8 Polytropic Efficiency 795
15.9 Flow Coefficient, Head or Work Coefficient, Deflection Coefficient, and Pressure Coefficient 797
15.10 Pressure Rise in a Stage and Number of Stages 798
15.11 Surging, Choking, and Stalling 799
15.12 Performance Characteristics 800
15.13 Comparison of Axial Flow and Centrifugal Compressors 802
15.14 Applications of Axial Flow Compressors 802
15.15 Losses in Axial Flow Compressors 802
Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 16 Gas Turbines 840
16.1 Introduction 840
16.2 Fields of Application of Gas Turbine 840
16.3 Limitations of Gas Turbines 840
16.4 Comparison of Gas Turbines with IC Engines 841
16.4.1 Advantages 841
16.4.2 Disadvantages 841
16.5 Advantages of Gas Turbines Over Steam Turbines 841
16.6 Classification of Gas Turbines 842
16.6.1 Constant Pressure Combustion Gas Turbine 842
16.6.2 Constant Volume Combustion Gas Turbine 843
16.7 Comparison of Open and Closed Cycle Gas Turbines 844
16.8 Position of Gas Turbine in the Power Industry 845
16.9 Thermodynamics of Constant Pressure Gas Turbine: Brayton Cycle 845
16.9.1 Efficiency 845
16.9.2 Specific Output 847
16.9.3 Maximum Work Output 848
16.9.4 Work Ratio 849
16.9.5 Optimum Pressure Ratio for Maximum Specific Work Output 849
16.10 Cycle Operation with Machine Efficiency 850
16.10.1 Maximum Pressure Ratio for Maximum Specific Work 850
16.10.2 Optimum Pressure Ratio for Maximum Cycle Thermal Efficiency 851
16.11 Open Cycle Constant Pressure Gas Turbine 853
16.12 Methods for Improvement of Thermal Efficiency of Open Cycle Constant Pressure Gas Turbine 854
16.12.1 Regeneration 854
16.12.2 Intercooling 857
16.12.3 Reheating 861
16.12.4 Reheat and Regenerative Cycle 863
16.12.5 Cycle with Intercooling and Regeneration 865
16.12.6 Cycle with Intercooling and Reheating 867
16.12.7 Cycle with Intercooling, Regeneration and Reheating 869
16.13 Effects of Operating Variables 890
16.13.1 Effect of Pressure Ratio 891
16.13.2 Effect of Efficiencies of Compressor and Turbine on Thermal Efficiency 892
16.14 Multi-Shaft Systems 894
16.15 Multi-Shaft System Turbines in Series 895
16.16 Gas Turbine Fuels 895
16.17 Blade Materials 895
16.17.1 Selection 895
16.17.2 Requirements of Blade Material 896
16.18 Cooling of Blades 896
16.18.1 Advantages of Cooling 896
16.18.2 Different Methods of Blade Cooling 896
Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 17 Jet Propulsion 922
17.1 Principle of Jet Propulsion 922
17.2 Jet Propulsion Systems 922
17.2.1 Screw Propeller 922
17.2.2 Ramjet Engine 923
17.2.3 Pulse Jet Engine 924
17.2.4 Turbo-jet Engine 925
17.2.5 Turbo-Prop Engine 926
17.2.6 Rocket Propulsion 927
17.3 Jet Propulsion v’s Rocket Propulsion 927
17.4 Basic Cycle for Turbo-jet Engine 928
17.4.1 Thrust 930
17.4.2 Thrust Power 930
17.4.3 Propulsive Power 931
17.4.4 Propulsive Efficiency 931
17.4.5 Thermal Efficiency 931
17.4.6 Overall Efficiency 931
17.4.7 Jet Efficiency 932
17.4.8 Ram Air Efficiency 932
17.5 Thrust Work, Propulsive Work, and Propulsive Efficiency for Rocket Engine 932
Summary for Quick Revision · Multiple-choice Questions · Explanatory Notes · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 18 Introduction to Refrigeration 961
18.1 Introduction 961
18.2 Refrigeration Systems 961
18.3 Methods of Refrigeration 962
18.3.1 Vapour Compression Refrigeration System 962
18.3.2 Vapour Absorption System 963
18.3.3 Ejector-Compression System 963
18.3.4 Electro-Lux Refrigeration 964
18.3.5 Solar Refrigeration 964
18.3.6 Thermo-electric Refrigeration 964
18.3.7 Vortex Tube Refrigeration 965
18.4 Unit of Refrigeration 965
18.5 Refrigeration Effect 965
18.6 Carnot Refrigeration Cycle 966
18.7 Difference Between a Heat Engine, Refrigerator and Heat Pump 967
18.8 Power Consumption of a Refrigerating Machine 969
18.9 Air Refrigeration Cycles 970
18.9.1 Open Air Refrigeration Cycle 971
18.9.2 Closed (or dense) Air Refrigeration Cycle 971
18.10 Reversed Carnot Cycle 971
18.10.1 Temperature Limitations for Reversed Carnot Cycle 972
18.10.2 Vapour as a Refrigerant in Reversed Carnot Cycle 973
18.10.3 Gas as a Refrigerant in Reversed Carnot Cycle 975
18.10.4 Limitations of Reversed Carnot Cycle 977
18.11 Bell-Coleman Cycle (or Reversed Brayton or Joule Cycle) 977
18.11.1 Bell-Coleman Cycle with Polytropic Processes 979
18.12 Refrigerants 988
18.13 Classification of Refrigerants 988
18.14 Designation of Refrigerants 989
18.15 Desirable Properties of Refrigerants 989
18.16 Applications of Refrigerants 990
18.17 Eco-friendly Refrigerants 993
18.18 Refrigerant Selection 995
Multiple-choice Questions · Review Questions · Exercises · Answers to Multiple-choice Questions
Chapter 19 Vapour Compression and Vapour Absorption Systems 999
19.1 Introduction 999
19.2 Comparison of Vapour Compression System with Air Refrigeration System 999
19.3 Simple Vapour Compression Refrigeration System 1000
19.4 Vapour Compression Refrigeration System 1001
19.5 Use of T-s and p-h Charts 1004
19.6 Effect of Suction Pressure 1014
19.7 Effect of Discharge Pressure 1015
19.8 Effect of Superheating of Refrigerant Vapour 1016
19.8.1 Superheat Horn 1017
19.9 Effect of Subcooling (or Undercooling) of Refrigerant Vapour 1017
19.10 Vapour Absorption System 1020
19.11 Working Principle of Vapour Absorption Refrigeration System 1021
19.11.1 Working 1022
19.12 Advantages of Vapour Absorption System Over Vapour Compression System 1022
19.13 Coefficient of Performance of an Ideal Vapour Absorption System 1023
19.14 Ammonia-Water (or Practical) Vapour Absorption System (NH3 – H2O) 1025
19.15 Lithium Bromide-Water Vapour Absorption System (LiBr-H2O) 1026
19.15.1 Working Principle 1027
19.15.2 Lithium Bromide-Water System Equipment 1028
19.16 Comparison of Ammonia-Water and Lithium Bromide-Water Absorption Systems 1029 Exercises
Chapter 20 Air-Conditioning and Psychrometrics 1034
20.1 Introduction 1034
20.2 Principles of Psychrometry 1034
20.3 Psychrometric Relations 1036
20.4 Enthalpy of Moist Air 1038
20.5 Humid Specific Heat 1039
20.6 Thermodynamic Wet Bulb Temperature or Adiabatic Saturation Temperature (AST) 1043
20.7 Psychrometric Chart 1046
20.8 Psychrometric Processes 1048
20.8.1 Sensible Heating or Cooling Process 1048
20.8.2 Humidification or Dehumidification Process 1049
20.8.3 Heating and Humidification 1050
20.8.4 Sensible Heat Factor-SHF 1051
20.8.5 Cooling and Dehumidification 1051
20.8.6 Air Washer 1052
20.8.7 Cooling with Adiabatic Humidification 1054
20.8.8 Cooling and Humidification by Water Injection (Evaporative Cooling) 1056
20.8.9 Heating and Humidification by Steam Injection 1057
20.8.10 Heating and Adiabatic Chemical Dehumidification 1057
20.9 Adiabatic Mixing of Two Air Streams 1058
20.10 Thermal Analysis of Human Body 1065
20.10.1 Factors Affecting Human Comfort 1066
20.10.2 Physiological Hazards Resulting from Heat 1066
20.11 Effective Temperature 1067
20.11.1 Comfort Chart 1067
20.11.2 Factors Affecting Optimum Effective Temperature 1070
20.12 Selection of Inside and Outside Design Conditions 1070
20.12.1 Selection of Inside Design Conditions 1070
20.12.2 Selection of Outside Design Conditions 1071
20.13 Cooling Load Estimation 1072
20.13.1 Heat Transfer Through Walls and Roofs 1072
20.13.2 Heat Gain from Solar Radiation 1073
20.13.3 Sol Air Temperature 1073
20.13.4 Solar Heat Gain Through Glass Areas 1074
20.13.5 Heat Gain due to Infiltration 1074
20.13.6 Heat Gain from Products 1074
20.13.7 Heat Gain from Lights 1075
20.13.8 Heat Gain from Power Equipments 1075
20.13.9 Heat Gain Through Ducts 1075
20.13.10 Empirical Methods to Evaluate Heat Transfer Through Walls and Roofs 1075
20.14 Heating Load Estimation 1077
20.15 Room Sensible Heat Factor (RSHF) 1077
20.15.1 Estimation of Supply Air Conditions 1078
20.16 Grand Sensible Heat Factor 1078
20.17 Effective Room Sensible Heat Factor 1079
