contents SECTION 1 Introduction to Particulate Emissions 1 CHAPTER 1 Gasoline Engine Particulate Emissions Introduction 3 References 7 About the Authors 8 CHAPTER 2 Health Impact of Particulates from Gasoline Engines 9 2.1 Air Pollution: A Brief Historical Survey 10 2.2 Interactions of Inhaled Air Pollutants with the Respiratory System 11 2.2.1 The Journey of an Inhaled Particle: Macro- and Microscopic Structure of the Respiratory System 12 2.2.2 Clearance Mechanisms 15 2.2.3 Mechanisms Underlying the Adverse Health Effects 16 2.3 Hazard and Risk Identification of Gasoline Exhaust 18 2.3.1 Epidemiological Findings 18 2.3.2 Findings from In Vivo Studies 19 2.3.3 Findings from Ex Vivo and In Vitro Studies 20 2.4 Conclusions and Future Recommendations 22 Acknowledgments 23 Glossary 23 References 24 About the Authors 31 v
vi CHAPTER 3 Regulations and Environmental Technologies 33 3.1 Why the Emphasis on Particulates from Modern Gasoline Engines? 33 3.1.1 Health Risks 34 3.1.2 Global Warming Considerations 36 3.1.3 Secondary Organic Aerosols (SOA) 37 3.2 Regulations on Vehicular Exhaust Particulate Emissions 37 3.2.1 United States and California 37 3.2.2 Europe 39 3.2.3 Test Procedures 39 3.2.4 China 42 3.2.5 India 44 3.3 Technology Pathways 45 3.3.1 In-Cylinder Methods 45 3.3.2 Fuel Considerations 48 3.3.3 Aftertreatment System 49 3.4 Summary 51 References 51 About the Author 60 SECTION 2 Fundamentals of Particulate Emissions 61 CHAPTER 4 Soot Formation in Combustion 63 4.1 Combustion-Generated Particles 63 4.1.1 Organic Fraction 65 4.1.2 Sulfate Fraction 65 4.1.3 Nitrate Fraction 65 4.1.4 Carbonaceous Fraction 65 4.1.5 Ash Fraction 65
vii 4.2 Soot Formation 66 4.3 Influencing Factors on Soot Formation in Gasoline Engines 68 4.3.1 Inhomogeneity 68 4.3.2 Tip Sooting 70 4.4 Soot Formation in Different Operating Points 72 4.4.1 Higher Specific Loads and Low Engine Speeds 72 4.4.2 Engine in Transient Operation Points 74 References 77 About the Authors 81 CHAPTER 5 Fuel Impact on Particle Formation 83 References 93 About the Author 100 SECTION 3 Particulate Emission Reduction Technologies 101 CHAPTER 6 Advanced Gasoline Combustion and Engine Controls 103 6.1 Gasoline Direct Injection 103 6.1.1 PN Formation Mechanisms 103 6.1.2 Operating Conditions 105 6.1.3 Engine Calibration 109 6.1.4 Summary Formation Mechanism 111 References 112 About the Authors 113
viii CHAPTER 7 Gasoline Particulate Filter Design, Fundamentals, and Function 115 7.1 Introduction 115 7.2 Aftertreatment Architectures Using GPF 116 7.3 General Filter Design and Application Requirements 117 7.4 Filter Design Fundamentals and Considerations 119 7.4.1 Material Selection 119 7.4.2 Filtration 120 7.4.3 Pressure Drop 124 7.4.4 Catalyst Functionality 129 7.4.5 Mechanical Robustness and Packaging 129 7.5 Application Fundamentals 130 7.5.1 Filtration over Different Emission Cycles 130 7.5.2 Ash Accumulation 132 7.5.3 Filter Design Based on Pressure Drop 135 7.5.4 Soot Oxidation and Regeneration 137 7.6 Summary 140 References 140 About the Author 144 CHAPTER 8 Gasoline Particulate Filter Application and Durability 145 8.1 Introduction 145 8.2 Filtration Efficiency in Practical Applications 146 8.2.1 Procedures for Particulate Emission Measurement 146 8.2.2 Effect of Application Conditions on Filtration Efficiency 148 8.2.3 Evolution of Filtration Efficiency over Initial Mileage 151 8.2.4 Evolution of Filtration Efficiency over Extended Mileage 152
ix 8.3 Ash Accumulation in Vehicle Applications 154 8.4 Soot Management in Vehicle Applications 158 8.4.1 Soot Load Monitoring 158 8.4.2 Examples of GPFs Operated in Purely Passive Applications 160 8.4.3 Examples of Severe Soot Regeneration 165 8.5 Thermal Robustness Requirements in Vehicle Applications 167 8.5.1 Thermal Stress Due to Transient Changes in the Boundary Conditions 167 8.5.2 Thermal Stress Due to Severe Soot Oxidation 169 8.6 Summary and Conclusions 173 References 174 About the Authors 176 CHAPTER 9 Three-Way Catalyst Integration into Particulate Filters 177 9.1 Introduction 177 References 189 About the Authors 190 CHAPTER 10 Three-Way Catalyst Gaseous Emissions: Gasoline Particulate Filter vs. Flow-Through Substrates 191 10.1 Introduction 191 10.2 Typical System Architectures 192 10.3 Design of Filter Coating and Effect on Gaseous Conversion 193
x 10.4 Examples of the Gaseous Emissions Conversion Performance of Coated GPFs 197 10.5 Summary 200 Reference 201 About the Authors 202 CHAPTER 11 Uncoated Gasoline Particulate Filter Integration and Examples 203 Summary 203 11.1 Introduction 204 11.2 GPF Design/Integration 204 11.2.1 Functional Requirements 205 11.2.2 GPF System Operation 206 11.2.3 Associated Test Procedures 208 11.3 Tuning Impact of the GPF 211 11.3.1 Engine Performance 211 11.3.2 GPF Monitoring Strategies 213 11.4 GPF System Validation 214 11.4.1 Filtration Efficiency Tests 214 11.4.2 Vehicle Road Tests 215 11.5 Conclusion 220 About the Author 221 CHAPTER 12 System Integration and Application for a Three-Way Catalyst-Coated Gasoline Particulate Filter 223 12.1 Design of TWC-Coated GPF 223 12.1.1 PN FE 224 12.1.2 Optimization of PN FE 225
xi 12.2 Soot Regeneration 226 12.2.1 Soot Regeneration with Respect to Oxygen Concentration 226 12.2.2 Soot Mass Limit 228 12.2.3 Soot Regeneration Rate 229 12.3 Durability Test 230 12.3.1 PN FE 230 12.3.2 Ash Effect on SML 231 12.4 Implementation of GPF in Mass Production Vehicles 233 References 233 About the Authors 234 SECTION 4 Measurement, Modeling and Control 235 CHAPTER 13 Measurement of Gasoline Particle Emissions: Laboratory and On-Board Vehicle 237 13.1 Background to the Development of Particle Number (PN) Counting 237 13.2 CPC Design 238 13.3 PN Counting System Design 240 13.4 Performance Criteria for Particle Counting Systems 241 13.5 Periodic Calibration and Validation 241 13.6 PN Limit Specified for EURO 5 Compression Ignition Vehicles 242 13.7 Other Legislative Applications of PN Limits 242 13.8 PN Counting Systems for Real Driving Emissions 242 13.9 Example: A PEMS-PN System Based on a CPC (HORIBA OBS-ONE-PN) 243 13.10 Example: A PEMS-PN System Based on an Advanced Diffusion Charger Design (TESTO NANOMET-3) 245
xii 13.11 Application of PEMS-PN to Other Automotive Exhaust Applications 246 13.12 Future of PN Measurement Within the EU 247 13.13 Future Applications of PN Counting for Non-exhaust Emissions 247 Acknowledgments 247 References 248 About the Author 249 CHAPTER 14 On-Board Diagnostics for Gasoline Particulate Filters 251 14.1 Introduction 251 14.2 Regulation Overview 252 14.3 GPF Failure Modes 254 14.3.1 Missing GPF Substrate 254 14.3.2 GPF Cracking and Channel Damage 254 14.4 GPF Sensing 255 14.4.1 DPS 256 14.4.2 Resistive PM Sensor 256 14.4.3 Ion Charge Sensor 257 14.4.4 Escaping Current PM Sensor 257 14.4.5 Radio Frequency Sensor 258 14.5 Algorithm Development 258 14.5.1 Flow Restriction 259 14.5.2 Differential Pressure Signal 260 14.5.3 Fault Criteria 260 14.5.4 System Identification 261 14.5.5 Monitor Enable Conditions, Calculations, and Thresholds 263 14.6 Algorithm Validation 263 14.6.1 Validation Strategies 263 14.6.2 Regulatory Requirements 266 References 266 About the Authors 267
xiii CHAPTER 15 Modeling of Gasoline Particulate Emission Control Systems and Components 269 15.1 Introduction 270 15.2 Wall-Scale Modeling 272 15.2.1 Wall Filtration 272 15.2.2 Effect of Accumulated Soot on Filtration 276 15.2.3 Pressure Drop 279 15.3 Channel-Scale Modeling 281 15.3.1 Mass-Momentum Balance 282 15.3.2 Pressure Drop 282 15.3.3 Energy Balance 286 15.3.4 Species Balance 287 15.3.5 TWC Reactions 291 15.3.6 Soot Reactions 295 15.4 Filter Scale Modeling 299 15.4.1 Filter Regeneration in Fuel Cut-Off Events 299 15.4.2 Ash Accumulation 300 15.5 Conclusions 307 Acknowledgments 308 Nomenclature 308 A. Latin Letters 308 B. Greek Letters 310 C. Subscripts and Superscripts 310 D. Acronyms 310 Reference 310 About the Authors 314 SAE Book Category Descriptions 317 Index 319