COMPREHENSIVE ANALYSIS AND IMPROVEMENT OF EFFICIENCY, EMISSIONS AND ELECTRICAL POWER QUALITY OF A SMALL, PORTABLE, GASOLINE-FUELED GENERATOR SYSTEM by ANDREW GREFF PAULIUS PUZINAUSKAS, COMMITTEE CHAIR TIMOTHY HASKEW MARCUS ASHFORD JOSHUA BITTLE HWAN-SIK YOON A DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Mechanical Engineering in the Graduate School of The University of Alabama TUSCALOOSA, ALABAMA 2019 Copyright Andrew Greff 2019 ALL RIGHTS RESERVED ABSTRACT The goal of this dissertation is to explore the methods of improving a small portable gasoline-fueled generator by increasing the efficiency and power quality and also reducing emissions. Advanced engine control strategies and optimized after-treatment systems are employed to achieve the goals. The focus of all three papers is a single-cylinder engine with a low power output which EPA classifies as a non-road spark ignition engine with a power output less than 19 kW. Engines that produce more than 19 kW in the same field can be very similar as they have the same purpose, but have much more stringent emissions standards. Emissions standards drive research and development, so great advances have been made in the higher power engine class, but this development is practically non-existent for low power output engines. Low-power engines are typically single-cylinder which adds additional complexities that must be addressed with unique solutions that higher power, multi-cylinder engines do not experience. Small portable gasoline-fueled generators use purely mechanical control systems to control all aspects of the engine and have no after-treatment to reduce emissions. Almost every other classification of engine uses sophisticated electronic control systems to control fuel injection, spark ignition, and throttle position to allow for very precise running conditions. Combined with after-treatment systems, these advanced engines produce emissions that are magnitudes lower than the small generator in this study. These low-power engines are used in a multitude of devices such as lawnmowers, handheld garden and lawn equipment, and pressure ii washers. There are as many of these devices in the United States as there are vehicles, so by reducing emissions in this class a very large impact can be made. iii DEDICATION This dissertation is dedicated to my Dzia Dzia who started this odyssey of being an engineer for Greffs. Also to my parents who have supported me in every way possible without ever missing a step. iv ACKNOWLEDGEMENTS After what seems like a lifetime, I am beyond pleased to thank everyone that made getting to this point possible. I would like to start with Dr. Paul, my advisor, whom I have now known for 12 years, got me into graduate school, taught me everything about engines, and for some reason kept working with me. I would like to thank Dr. Haskew who showed me a whole new world of controls to expand my passions and would answer every question I had no matter how small or busy he was. The cross-disciplinary knowledge you have helped bestow upon me is beyond invaluable. I would like to thank Dr. Ashford for sharing my passion for racing and being able to talk about anything with me for hours. I cannot thank Dr. Bittle and Dr. Yoon enough for being so cooperative with my difficult schedule and working with me every step of the way. Outside of my committee, there is no one I could ever owe more than Megan Hathcock who for years would sit beside me and then would sit in the lab for hours a day while I was out of state to run my testing for me, generate code, and clean up my spaghetti of code. I would never have finished without you. I would like to thank two of the greatest friends I could have asked for, Chris New and Cole Frederick, for inspiring me every day through our conversations and for stepping up and assisting in testing and setup every time I was drowning. I would like to thank my family for believing in me and always pushing me. Thank you, Sergio, for sitting on a headset with me every day and always finding a way to make me laugh. I would like to thank all of my friends who joked about my graduate date never coming and for always being there for me. Finally, I would like to thank Led Zeppelin, The Who, Foo Fighters, Vivaldi, Miles Davis, and Hans Zimmer for providing an avenue of escape from reality. v CONTENTS ABSTRACT .................................................................................................................................... ii DEDICATION ............................................................................................................................... iv ACKNOWLEDGEMENTS ............................................................................................................ v LIST OF TABLES ........................................................................................................................ vii LIST OF FIGURES ..................................................................................................................... viii INTRODUCTION .......................................................................................................................... 1 DEVELOPMENT OF A PREDICTIVE AIRFLOW ALGORITHM BASED ON EMPIRICAL FLOW DATA TO REDUCE HYDROCARBON EMISSIONS ........................... 23 IMPACTS OF CATALYST SIZING AND EXHAUST PULSE FREQUENCY ON CATALYST EFFICIENCY ................................................................................................... 58 REDUCTION OF HEAT LOSS AND APPARENT POWER THROUGH GENERATOR FREQUENCY CONTROL ........................................................................................................... 84 CONCLUSION AND RECOMMENDATIONS ....................................................................... 104 REFERENCES ........................................................................................................................... 110 vi LIST OF TABLES Table 1. Emission standards for small nonroad engines by year .................................................... 1 Table 2. Emission standards for small nonroad engines by year .................................................. 24 Table 3. Flow chart for two cycles with flow prediction .............................................................. 43 Table 4. Test matrix ...................................................................................................................... 46 Table 5. Summary of lambda values for each section once steady-state is achieved ................... 56 Table 6. Emission standards for small nonroad engines by year .................................................. 59 Table 7. Comparison of key engine attributes .............................................................................. 70 Table 8. Summary of Field Brush Measurements ........................................................................ 96 Table 9. Power Factors of Typical Appliances (Schneider, 1996) ............................................... 97 vii LIST OF FIGURES Figure 1. Equivalent emissions for small engines .......................................................................... 4 Figure 2. Control schematic for centrifugal governor .................................................................... 6 Figure 3. Mechanical governor with proportional, integral, and derivative capabilities ................ 7 Figure 4. Simplified diagram for method of controlling voltage output of generator .................. 18 Figure 5. Schematic of generator with resistance load ................................................................. 20 Figure 6. Power phasor diagram ................................................................................................... 21 Figure 7. Equivalent emissions for small engines ........................................................................ 26 Figure 8. Control schematic for centrifugal governor .................................................................. 28 Figure 9. Mechanical governor with proportional, integral, and derivative capabilities .............. 29 Figure 10. Flow diagram of control system for electronic throttle controller .............................. 39 Figure 11. Flow coefficients at various throttle angles and backpressures ................................... 44 Figure 12. Test cycle used for all tests .......................................................................................... 45 Figure 13. Comparison between open loop (blue) and closed loop (green) fuel control on air-fuel ratio using a mechanical governor during load changes .................................................. 47 Figure 14. Integrated HC emissions for open loop and closed loop fueling. Solid represents pre-cat and dashed post-cat ........................................................................................................... 48 Figure 15. Effect on lambda by implementing electronic throttle. Green is electronic throttle and blue is mechanical governor ................................................................................................... 49 Figure 16. Speed traces for mechanical and electrical governors ................................................. 50 Figure 17. Integrated HC emissions for mechanical governor and electrical governor ............... 51 viii Figure 18. Lambda values for the flow prediction algorithm (green) and without (blue) ............ 52 Figure 19. FFT of section 3 without flow