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An Introduction to Thermodynamic Cycle Simulations for Internal Combustion Engines

ISBN: 978-1-119-03756-9
384 pages
December 2015
An Introduction to Thermodynamic Cycle Simulations for Internal Combustion Engines (1119037565) cover image

Description

This book provides an introduction to basic thermodynamic engine cycle simulations, and provides a substantial set of results. Key features includes comprehensive and detailed documentation of the mathematical foundations and solutions required for thermodynamic engine cycle simulations. The book includes a thorough presentation of results based on the second law of thermodynamics as well as results for advanced, high efficiency engines. Case studies that illustrate the use of engine cycle simulations are also provided.

 

 

 

 

 

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Table of Contents

Preface xiii

1 Introduction 1

1.1 Reasons for Studying Engines 1

1.2 Engine Types and Operation 2

1.3 Reasons for Cycle Simulations 3

1.3.1 Educational Value 3

1.3.2 Guide Experimentation 3

1.3.3 Only Technique to Study Certain Variables 4

1.3.4 Complete Extensive Parametric Studies 4

1.3.5 Opportunities for Optimization 4

1.3.6 Simulations for Real ]time Control 4

1.3.7 Summary 5

1.4 Brief Comments on the History of Simulations 5

1.5 Overview of Book Content 6

2 Overview of Engines and Their Operation 9

2.1 Goals of Engine Designs 9

2.2 Engine Classifications by Applications 10

2.3 Engine Characteristics 11

2.4 Basic Engine Components 12

2.5 Engine Operating Cycles 12

2.6 Performance Parameters 12

2.6.1 Work, Power, and Torque 12

2.6.2 Mean Effective Pressure 15

2.6.3 Thermal Efficiencies 16

2.6.4 Specific Fuel Consumption 17

2.6.5 Other Parameters 17

2.7 Summary 18

3 Overview of Engine Cycle Simulations 19

3.1 Introduction 19

3.2 Ideal (Air Standard) Cycle Analyses 19

3.3 Thermodynamic Engine Cycle Simulations 21

3.4 Quasi ]dimensional Thermodynamic Engine Cycle Simulations 22

3.5 Multi ]dimensional Simulations 23

3.6 Commercial Products 24

3.6.1 Thermodynamic Simulations 24

3.6.2 Multi ]dimensional Simulations 25

3.7 Summary 26

Appendix 3.A: A Brief Summary of the Thermodynamics of the “Otto” Cycle Analysis 29

4 Properties of the Working Fluids 37

4.1 Introduction 37

4.2 Unburned Mixture Composition 37

4.2.1 Oxygen ]containing Fuels 40

4.2.2 Oxidizers 41

4.2.3 Fuels 41

4.3 Burned Mixture (“Frozen” Composition) 42

4.4 Equilibrium Composition 43

4.5 Determinations of the Thermodynamic Properties 46

4.6 Results for the Thermodynamic Properties 47

4.7 Summary 61

5 Thermodynamic Formulations 63

5.1 Introduction 63

5.2 Approximations and Assumptions 64

5.3 Formulations 65

5.3.1 One ]Zone Formulation 65

5.3.2 Two ]Zone Formulation 67

5.3.3 Three ]Zone Formulation 72

5.4 Comments on the Three Formulations 77

5.5 Summary 77

6 Items and Procedures for Solutions 79

6.1 Introduction 79

6.2 Items Needed to Solve the Energy Equations 79

6.2.1 Thermodynamic Properties 79

6.2.2 Kinematics 80

6.2.3 Combustion Process (Mass Fraction Burned) 82

6.2.4 Cylinder Heat Transfer 85

6.2.5 Mass Flow Rates 86

6.2.6 Mass Conservation 89

6.2.7 Friction 89

6.2.8 Pollutant Calculations 94

6.2.9 Other Sub ]models 94

6.3 Numerical Solution 94

6.3.1 Initial and Boundary Conditions 95

6.3.2 Internal Consistency Checks 96

6.4 Summary 96

7 Basic Results 99

7.1 Introduction 99

7.2 Engine Specifications and Operating Conditions 99

7.3 Results and Discussion 101

7.3.1 Cylinder Volumes, Pressures, and Temperatures 102

7.3.2 Cylinder Masses and Flow Rates 106

7.3.3 Specific Enthalpy and Internal Energy 108

7.3.4 Molecular Masses, Gas Constants, and Mole Fractions 110

7.3.5 Energy Distribution and Work 114

7.4 Summary and Conclusions 116

8 Performance Results 119

8.1 Introduction 119

8.2 Engine and Operating Conditions 119

8.3 Performance Results (Part I)—Functions of Load and Speed 119

8.4 Performance Results (Part II)—Functions of Operating/Design Parameters 129

8.4.1 Combustion Timing 129

8.4.2 Compression Ratio 131

8.4.3 Equivalence Ratio 133

8.4.4 Burn Duration 135

8.4.5 Inlet Temperature 135

8.4.6 Residual Mass Fraction 136

8.4.7 Exhaust Pressure 136

8.4.8 Exhaust Gas Temperature 140

8.4.9 Exhaust Gas Recirculation 142

8.4.10 Pumping Work 145

8.5 Summary and Conclusions 149

9 Second Law Results 153

9.1 Introduction 153

9.2 Exergy 153

9.3 Previous Literature 154

9.4 Formulation of Second Law Analyses 154

9.5 Results from the Second Law Analyses 158

9.5.1 Basic Results 158

9.5.2 Parametric Results 163

9.5.3 Auxiliary Comments 174

9.6 Summary and Conclusions 176

10 Other Engine Combustion Processes 179

10.1 Introduction 179

10.2 Diesel Engine Combustion 179

10.3 Best Features from SI and CI Engines 180

10.4 Other Combustion Processes 181

10.4.1 Stratified Charge Combustion 181

10.4.2 Low Temperature Combustion 181

10.5 Challenges of Alternative Combustion Processes 182

10.6 Applications of the Simulations for Other Combustion Processes 183

10.7 Summary 184

11 Case Studies: Introduction 187

11.1 Case Studies 187

11.2 Common Elements of the Case Studies 188

11.3 General Methodology of the Case Studies 189

12 Combustion: Heat Release and Phasing 191

12.1 Introduction 191

12.2 Engine and Operating Conditions 191

12.3 Part I: Heat Release Schedule 191

12.3.1 Results for the Heat Release Rate 197

12.4 Part II: Combustion Phasing 205

12.4.1 Results for Combustion Phasing 206

12.5 Summary and Conclusions 221

13 Cylinder Heat Transfer 225

13.1 Introduction 225

13.2 Basic Relations 226

13.3 Previous Literature 227

13.3.1 Woschni Correlation 228

13.3.2 Summary of Correlations 229

13.4 Results and Discussion 230

13.4.1 Conventional Engine 230

13.4.2 Engines Utilizing Low Heat Rejection Concepts 241

13.4.3 Engines Utilizing Adiabatic EGR 247

13.5 Summary and Conclusions 250

14 Fuels 253

14.1 Introduction 253

14.2 Fuel Specifications 254

14.3 Engine and Operating Conditions 255

14.4 Results and Discussion 255

14.4.1 Assumptions and Constraints 255

14.4.2 Basic Results 255

14.4.3 Engine Performance Results 259

14.4.4 Second Law Results 266

14.5 Summary and Conclusions 268

Appendix 14.A: Energy and Exergy Distributions for the Eight Fuels at the Base Case Conditions (bmep = 325 kPa, 2000 rpm, ϕ = 1.0 and MBT timing) 269

15 Oxygen ]Enriched Air 275

15.1 Introduction 275

15.2 Previous Literature 276

15.3 Engine and Operating Conditions 277

15.4 Results and Discussion 277

15.4.1 Strategy for This Study 278

15.4.2 Basic Thermodynamic Properties 278

15.4.3 Base Engine Performance 280

15.4.4 Parametric Engine Performance 283

15.4.5 Nitric Oxide Emissions 289

15.5 Summary and Conclusions 291

16 Overexpanded Engine 295

16.1 Introduction 295

16.2 Engine, Constraints, and Approach 296

16.2.1 Engine and Operating Conditions 296

16.2.2 Constraints 296

16.2.3 Approach 296

16.3 Results and Discussion 297

16.3.1 Part Load 297

16.3.2 Wide ]Open Throttle 304

16.4 Summary and Conclusions 309

17 Nitric Oxide Emissions 311

17.1 Introduction 311

17.2 Nitric Oxide Kinetics 312

17.2.1 Thermal Nitric Oxide Mechanism 312

17.2.2 “Prompt” Nitric Oxide Mechanism 312

17.2.3 Nitrous Oxide Route Mechanism 313

17.2.4 Fuel Nitrogen Mechanism 313

17.3 Nitric Oxide Computations 313

17.3.1 Kinetic Rates 315

17.4 Engine and Operating Conditions 316

17.5 Results and Discussion 317

17.5.1 Basic Chemical Kinetic Results 317

17.5.2 Time ]Resolved Nitric Oxide Results 320

17.5.3 Engine Nitric Oxide Results 324

17.6 Summary and Conclusions 329

18 High Efficiency Engines 333

18.1 Introduction 333

18.2 Engine and Operating Conditions 334

18.3 Results and Discussion 336

18.3.1 Overall Assessment 336

18.3.2 Effects of Individual Parameters 343

18.3.3 Emissions and Exergy 347

18.3.4 Effects of Combustion Parameters 351

18.4 Summary and Conclusions 353

19 Summary: Thermodynamics of Engines 355

19.1 Summaries of Chapters 355

19.2 Fundamental Thermodynamic Foundations of IC Engines 356

Item 1: Heat Engines versus Chemical Conversion Devices 356

Item 2: Air ]Standard Cycles 357

Item 3: Importance of Compression Ratio 357

Item 4: Importance of the Ratio of Specific Heats 359

Item 5: Cylinder Heat Transfer 360

Item 6: The Potential of a Low Heat Rejection Engine 360

Item 7: Lean Operation and the Use of EGR 361

Item 8: Insights from the Second Law of Thermodynamics 361

Item 9: Timing of the Combustion Process 362

Item 10: Technical Assessments of Engine Concepts 362

19.3 Concluding Remarks 362

Index 363

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