Dual-Stage Boosting Systems: Modeling of Configurations, Matching and Boost Control Options by Byungchan Lee A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Mechanical Engineering) in The University of Michigan 2009 Doctoral Committee: Professor Dionissios N. Assanis, Co-Chair Assistant Professor Dohoy Jung, Co-Chair Research Professor Zoran S. Filipi Assistant Professor Matthias Ihme © Byungchan Lee All right reserved 2009 ACKNOWLEDGEMENTS I would like to acknowledge the technical and financial support of the Automotive Research Center (ARC) by the National Automotive Center (NAC) located within the US Army Tank-Automotive Research, Development and Engineering Center (TARDEC) in Warren, Michigan. The ARC is a U.S. Army Center of Excellence for Automotive Research at the University of Michigan, currently in partnership with 6 other Universities. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................................................................................ ii LIST OF TABLES ............................................................................................................. vi LIST OF FIGURES .......................................................................................................... vii LIST OF ABBREVIATIONS ............................................................................................. x CHAPTER 1. Introduction.................................................................................................. 1 1.1. Overview .................................................................................................................... 1 1.2. Literature Review on Air Charging Systems ............................................................. 6 1.2.1. Positive displacement supercharger ..................................................................... 6 1.2.2. Centrifugal compressor as a supercharger ........................................................... 8 1.2.3. Electrically driven supercharger .......................................................................... 9 1.2.4. Single-stage turbocharging .................................................................................. 9 1.2.5. Dual-stage turbocharging ................................................................................... 11 1.3. Motivation and objectives ........................................................................................ 13 CHAPTER 2. SIMULATION OF TURBOCHARGED DIESEL ENGINE .................... 16 2.1. Introduction .............................................................................................................. 16 2.2. Description of the simulation model ........................................................................ 17 2.2.1. Air filter model ...................................................................................................19 2.2.2. Turbocharger model ............................................................................................20 2.2.3. Intake/Exhaust manifold model ..........................................................................21 2.2.4. In-cylinder process ..............................................................................................23 2.2.5. Valve flow ...........................................................................................................25 iii 2.2.6. Fuel injection control ..........................................................................................26 2.2.7. Vehicle system model .........................................................................................27 2.3. Engine Model Calibration ...................................................................................29 CHAPTER 3. DUAL-STAGE TURBOCHARGER MATCHING .................................. 32 3.1. Matching procedure ................................................................................................. 32 3.2. Turbomachinery scaling ........................................................................................... 44 CHAPTER 4. BOOST CONTROL OPTIONS ................................................................ 46 4.1. Introduction .............................................................................................................. 46 4.1.1. Dual-stage turbocharger with wastegate .............................................................47 4.1.2. Dual-stage turbocharger with bypass valve ........................................................48 4.1.3. Early Intake Valve Closure (EIVC) cycle ..........................................................49 4.2. Simulation results..................................................................................................... 57 4.2.1. The effect of the ratio of each stage pressure ratios ............................................57 4.2.2. Fuel injection rate and timing .............................................................................60 4.2.3. Steady state results ..............................................................................................63 4.2.4. Transient results ..................................................................................................67 4.3. Summary .................................................................................................................. 70 CHAPTER 5. HYBRID DUAL-STAGE BOOSTING SYSTEMS ................................. 72 5.1. Introduction .............................................................................................................. 72 5.2. Hybrid dual-stage boosting systems ........................................................................ 74 5.2.1. Hybrid dual-stage boosting system with screw type supercharger .....................74 5.2.2. Hybrid dual-stage boosting system with electrically driven supercharger .........76 5.2.3. Hybrid dual-stage boosting system with variable geometry turbine ..................77 5.3. Fuel injection rate and timing .................................................................................. 78 5.4. Steady state simulation results ................................................................................. 81 iv 5.5. Transient simulation results ..................................................................................... 84 5.6. Fuel economy ........................................................................................................... 87 5.7. Summary .................................................................................................................. 94 CHAPTER 6. Summary and conclusion .......................................................................... 95 APPENDIX ....................................................................................................................... 98 BIBLIOGRAPHY ........................................................................................................... 100 v LIST OF TABLES Table 1. Engine Specification ........................................................................................... 19 Table 2. Vehicle Specification .......................................................................................... 28 Table 3. Engine Specification ........................................................................................... 29 Table 4. Data used for Engine Calibration ........................................................................ 30 Table 5. Fuel-air equivalence ratio when the electric compressor is turned off ............... 88 vi LIST OF FIGURES Figure 1. Diesel Engine System Model ............................................................................ 17 Figure 2. Intake/Exhaust manifold model ......................................................................... 21 Figure 3. Heat transfer in intake/exhaust manifold ........................................................... 22 Figure 4. Valve effective flow area ................................................................................... 26 Figure 5. Vehicle system model ........................................................................................ 27 Figure 6. Pressure traces ................................................................................................... 31 Figure 7. Dual-Stage turbocharger configuration ............................................................. 33 Figure 9. Dual-stage turbocharger with wastegate ........................................................... 48 Figure 10. Dual-stage turbocharger with bypass valve ..................................................... 49 Figure 11. EIVC vs. LIVC ................................................................................................ 50 Figure 12. Cylinder temperature ....................................................................................... 51 Figure 13. Peak cylinder temperature and pressure .......................................................... 53 Figure 14. BSFC with varying intake valve closing timing.............................................. 55 Figure 15. Dual-stage turbocharging system without bypass valve utilizing EIVC ......... 56 Figure 16. Effect of ratios of each stage pressure ratios on compressor performance ..... 59 Figure 17. Effect of ratios of each stage pressure ratios on brake torque and BSFC ....... 59 vii Figure 18. Cylinder pressure at 2000 rpm full load condition .......................................... 60 Figure 19. Peak cylinder pressure