Introduction to Thermodynamic Cycle Simulations for Internal Combustion Engines

Jerald A. Caton, Gulf Oil/Thomas A. Dietz Professorship at Texas A&M University, USAProfessor Caton has been at Texas A&M University since September 1979 in the Department of Mechanical Engineering. He is holder of the Gulf Oil/Thomas A. Dietz Professorship (2007). He teaches and conducts research in the area of IC engines, thermodynamics, cogeneration and power plans. He received his BS and MS degrees from the University of California, Berkeley, and his PhD from the Massachusetts Institute of Technology. Professor Caton is a Fellow of both ASME and SAE. He has been focusing on the development and use of engine cycle simulations since 1997.

• Preface xiii 1 Introduction 11.1 Reasons for Studying Engines 11.2 Engine Types and Operation 21.3 Reasons for Cycle Simulations 31.3.1 Educational Value 31.3.2 Guide Experimentation 31.3.3 Only Technique to Study Certain Variables 41.3.4 Complete Extensive Parametric Studies 41.3.5 Opportunities for Optimization 41.3.6 Simulations for Real]time Control 41.3.7 Summary 51.4 Brief Comments on the History of Simulations 51.5 Overview of Book Content 62 Overview of Engines and Their Operation 92.1 Goals of Engine Designs 92.2 Engine Classifications by Applications 102.3 Engine Characteristics 112.4 Basic Engine Components 122.5 Engine Operating Cycles 122.6 Performance Parameters 122.6.1 Work, Power, and Torque 122.6.2 Mean Effective Pressure 152.6.3 Thermal Efficiencies 162.6.4 Specific Fuel Consumption 172.6.5 Other Parameters 172.7 Summary 183 Overview of Engine Cycle Simulations 193.1 Introduction 193.2 Ideal (Air Standard) Cycle Analyses 193.3 Thermodynamic Engine Cycle Simulations 213.4 Quasi]dimensional Thermodynamic Engine Cycle Simulations 223.5 Multi]dimensional Simulations 233.6 Commercial Products 243.6.1 Thermodynamic Simulations 243.6.2 Multi]dimensional Simulations 253.7 Summary 26Appendix 3.A: A Brief Summary of the Thermodynamics of the “Otto” Cycle Analysis 294 Properties of the Working Fluids 374.1 Introduction 374.2 Unburned Mixture Composition 374.2.1 Oxygen]containing Fuels 404.2.2 Oxidizers 414.2.3 Fuels 414.3 Burned Mixture (“Frozen” Composition) 424.4 Equilibrium Composition 434.5 Determinations of the Thermodynamic Properties 464.6 Results for the Thermodynamic Properties 474.7 Summary 615 Thermodynamic Formulations 635.1 Introduction 635.2 Approximations and Assumptions 645.3 Formulations 655.3.1 One]Zone Formulation 655.3.2 Two]Zone Formulation 675.3.3 Three]Zone Formulation 725.4 Comments on the Three Formulations 775.5 Summary 776 Items and Procedures for Solutions 796.1 Introduction 796.2 Items Needed to Solve the Energy Equations 796.2.1 Thermodynamic Properties 796.2.2 Kinematics 806.2.3 Combustion Process (Mass Fraction Burned) 826.2.4 Cylinder Heat Transfer 856.2.5 Mass Flow Rates 866.2.6 Mass Conservation 896.2.7 Friction 896.2.8 Pollutant Calculations 946.2.9 Other Sub]models 946.3 Numerical Solution 946.3.1 Initial and Boundary Conditions 956.3.2 Internal Consistency Checks 966.4 Summary 967 Basic Results 997.1 Introduction 997.2 Engine Specifications and Operating Conditions 997.3 Results and Discussion 1017.3.1 Cylinder Volumes, Pressures, and Temperatures 1027.3.2 Cylinder Masses and Flow Rates 1067.3.3 Specific Enthalpy and Internal Energy 1087.3.4 Molecular Masses, Gas Constants, and Mole Fractions 1107.3.5 Energy Distribution and Work 1147.4 Summary and Conclusions 1168 Performance Results 1198.1 Introduction 1198.2 Engine and Operating Conditions 1198.3 Performance Results (Part I)—Functions of Load and Speed 1198.4 Performance Results (Part II)—Functions of Operating/Design Parameters 1298.4.1 Combustion Timing 1298.4.2 Compression Ratio 1318.4.3 Equivalence Ratio 1338.4.4 Burn Duration 1358.4.5 Inlet Temperature 1358.4.6 Residual Mass Fraction 1368.4.7 Exhaust Pressure 1368.4.8 Exhaust Gas Temperature 1408.4.9 Exhaust Gas Recirculation 1428.4.10 Pumping Work 1458.5 Summary and Conclusions 1499 Second Law Results 1539.1 Introduction 1539.2 Exergy 1539.3 Previous Literature 1549.4 Formulation of Second Law Analyses 1549.5 Results from the Second Law Analyses 1589.5.1 Basic Results 1589.5.2 Parametric Results 1639.5.3 Auxiliary Comments 1749.6 Summary and Conclusions 17610 Other Engine Combustion Processes 17910.1 Introduction 17910.2 Diesel Engine Combustion 17910.3 Best Features from SI and CI Engines 18010.4 Other Combustion Processes 18110.4.1 Stratified Charge Combustion 18110.4.2 Low Temperature Combustion 18110.5 Challenges of Alternative Combustion Processes 18210.6 Applications of the Simulations for Other Combustion Processes 18310.7 Summary 18411 Case Studies: Introduction 18711.1 Case Studies 18711.2 Common Elements of the Case Studies 18811.3 General Methodology of the Case Studies 18912 Combustion: Heat Release and Phasing 19112.1 Introduction 19112.2 Engine and Operating Conditions 19112.3 Part I: Heat Release Schedule 19112.3.1 Results for the Heat Release Rate 19712.4 Part II: Combustion Phasing 20512.4.1 Results for Combustion Phasing 20612.5 Summary and Conclusions 22113 Cylinder Heat Transfer 22513.1 Introduction 22513.2 Basic Relations 22613.3 Previous Literature 22713.3.1 Woschni Correlation 22813.3.2 Summary of Correlations 22913.4 Results and Discussion 23013.4.1 Conventional Engine 23013.4.2 Engines Utilizing Low Heat Rejection Concepts 24113.4.3 Engines Utilizing Adiabatic EGR 24713.5 Summary and Conclusions 25014 Fuels 25314.1 Introduction 25314.2 Fuel Specifications 25414.3 Engine and Operating Conditions 25514.4 Results and Discussion 25514.4.1 Assumptions and Constraints 25514.4.2 Basic Results 25514.4.3 Engine Performance Results 25914.4.4 Second Law Results 26614.5 Summary and Conclusions 268Appendix 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) 26915 Oxygen]Enriched Air 27515.1 Introduction 27515.2 Previous Literature 27615.3 Engine and Operating Conditions 27715.4 Results and Discussion 27715.4.1 Strategy for This Study 27815.4.2 Basic Thermodynamic Properties 27815.4.3 Base Engine Performance 28015.4.4 Parametric Engine Performance 28315.4.5 Nitric Oxide Emissions 28915.5 Summary and Conclusions 29116 Overexpanded Engine 29516.1 Introduction 29516.2 Engine, Constraints, and Approach 29616.2.1 Engine and Operating Conditions 29616.2.2 Constraints 29616.2.3 Approach 29616.3 Results and Discussion 29716.3.1 Part Load 29716.3.2 Wide]Open Throttle 30416.4 Summary and Conclusions 30917 Nitric Oxide Emissions 31117.1 Introduction 31117.2 Nitric Oxide Kinetics 31217.2.1 Thermal Nitric Oxide Mechanism 31217.2.2 “Prompt” Nitric Oxide Mechanism 31217.2.3 Nitrous Oxide Route Mechanism 31317.2.4 Fuel Nitrogen Mechanism 31317.3 Nitric Oxide Computations 31317.3.1 Kinetic Rates 31517.4 Engine and Operating Conditions 31617.5 Results and Discussion 31717.5.1 Basic Chemical Kinetic Results 31717.5.2 Time]Resolved Nitric Oxide Results 32017.5.3 Engine Nitric Oxide Results 32417.6 Summary and Conclusions 32918 High Efficiency Engines 33318.1 Introduction 33318.2 Engine and Operating Conditions 33418.3 Results and Discussion 33618.3.1 Overall Assessment 33618.3.2 Effects of Individual Parameters 34318.3.3 Emissions and Exergy 34718.3.4 Effects of Combustion Parameters 35118.4 Summary and Conclusions 35319 Summary: Thermodynamics of Engines 35519.1 Summaries of Chapters 35519.2 Fundamental Thermodynamic Foundations of IC Engines 356Item 1: Heat Engines versus Chemical Conversion Devices 356Item 2: Air]Standard Cycles 357Item 3: Importance of Compression Ratio 357Item 4: Importance of the Ratio of Specific Heats 359Item 5: Cylinder Heat Transfer 360Item 6: The Potential of a Low Heat Rejection Engine 360Item 7: Lean Operation and the Use of EGR 361Item 8: Insights from the Second Law of Thermodynamics 361Item 9: Timing of the Combustion Process 362Item 10: Technical Assessments of Engine Concepts 36219.3 Concluding Remarks 362Index 363