Light Duty Natural Gas Engine Characterization THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By David Roger Hillstrom Graduate Program in Mechanical Engineering The Ohio State University 2014 Master's Examination Committee: Professor Giorgio Rizzoni, Advisor Professor Shawn Midlam-Mohler Dr. Fabio Chiara Copyright by David Roger Hillstrom 2014 Abstract The purpose of this project was to characterize the baseline performance of a 2012 Honda Civic Natural Gas vehicle including: designing experiments to generate complete performance maps, executing the experiments, and analyzing the experimental data. In the end, the results yielded a deep understanding of the 1.8 L four cylinder CNG engine’s combustion and air flow performance, as well as a good understanding of steady state engine out emissions. This information is used to isolate inefficiencies in design and propose possible avenues for improvement. The data that was acquired was then used to inform an existing 1-D computational model of the same engine in order to determine if, and where, the model was inaccurate, and determine what steps were necessary to improve it. The resulting test data provides a data based background to the well-understood issues regarding a CNG port-fuel injected vehicle. The volumetric efficiency at low engine speeds was typically around 70%, resulting in an IMEP loss of about 15% compared to the engines peak possible performance. A CNG direct injection system is one possible solution to this problem. Additionally, the engine efficiency and spark timing map demonstrate that, even with the high compression ratio, the vehicle is not currently limited by engine knock. This available pressure headroom could be used with ii boosting to improve the overall performance of the vehicle to bring it more in line with consumer expectations. The development of this natural gas vehicle technologies research platform will allow the Center for Automotive Research at The Ohio State University to more easily pursue CNG related research topics. Some particular thrust areas of interest regarding this platform are the reduction of hydrocarbons while operating with lean burn, CNG direct injection, turbocharging optimization, and possibly even CNG / gasoline concomitant operation. The benefits to be had from these technology improvements can be gleaned by examining the baseline performance covered herein. iii Acknowledgments I would like to thank my advisor Dr. Giorgio Rizzoni for providing the opportunities I have received since I arrived at The Ohio State University. He placed me in the natural gas consortium project which allowed me to very quickly get my hands dirty with heavy experimental work. Without this, I would have struggled to get such an involved and independent project to use for my Master’s Thesis. I would like to thank the Honda Partnership Program for their donation of a 2012 Honda Civic Natural Gas for our research. Without their support, there would have been no foundation for this work to begin. I would also like to thank my co-advisor Dr. Shawn Midlam-Mohler, Eric Shacht, and Dr. Fabio Chiara for their continued guidance in my work and all the technical help they have given me throughout my graduate career. Finally I would also like to thank Dr. Jim Durand for providing extra opportunities for me to get involved around the Center for Automotive Research to ensure that my education extended beyond just the academic and into actual industrial and business relations. iv Vita January 1989 Born – Tulsa, Oklahoma December 2011 B.S. Mechanical and Aerospace Engineering, Oklahoma State University August, 2012 to Present Graduate Research Associate, The Ohio State University, Center for Automotive Research Fields of Study Major Field: Mechanical Engineering v Table of Contents Abstract ............................................................................................................................... ii Acknowledgments.............................................................................................................. iv Vita ...................................................................................................................................... v List of Tables ................................................................................................................... viii List of Figures .................................................................................................................... ix Chapter 1: Introduction ...................................................................................................... 1 Brief Overview of the State of Natural Gas in US Energy ............................................. 1 CNG vs Gasoline ............................................................................................................. 3 CNG Vehicle Market Overview ...................................................................................... 6 Chapter 2: Literature Review ............................................................................................ 10 Direct Injection Executive Summary ............................................................................ 11 Geometric Design Considerations Executive Summary ............................................... 16 Hydrogen Executive Summary ..................................................................................... 18 Dual fuel and Bi-fuel Executive Summary ................................................................... 20 Combustion Executive Summary .................................................................................. 24 Noise, Vibration, and Harshness Executive Summary ................................................. 27 Emissions Executive Summary ..................................................................................... 28 vi Chapter 3: Experimental Setup ......................................................................................... 31 Throttle Model: ............................................................................................................. 33 Combustion Model ........................................................................................................ 35 Emissions ...................................................................................................................... 39 Sample Timing .............................................................................................................. 39 Chapter 4: Engine Characterization Results ..................................................................... 43 Experimental Plan ......................................................................................................... 43 Thermodynamic Method for Locating Top Dead Center.............................................. 45 Calculating for the Throttle Model ....................................................................... 47 Fuel Burn Rate Analysis for the Combustion Model .................................................... 49 Emissions and Efficiency Analysis ............................................................................... 55 Volumetric Efficiency ................................................................................................... 60 Chapter 5: Integration With GT Power ............................................................................. 62 Chatper 6: Conclusions and Future Work ......................................................................... 67 Appendix A: Instrumentation ........................................................................................... 75 vii List of Tables Table 1. Motoring Tests and Resulting TDC .................................................................... 46 viii List of Figures Figure 1. EIA Natural Gas Data .......................................................................................... 2 Figure 2. EIA Fuel Price History and Projections .............................................................. 3 Figure 3. Laminar Flame Speed S1 at High Pressure and High Temperature [6] .............. 5 Figure 4. Mercedes B200 NGT With a Well-Integrated Fuel System [9] .......................... 7 Figure 5. Curves of Injector Needle Lift and Gas Mass Flow .......................................... 12 Figure 6. Scheme of the proposed SS simplification ........................................................ 13 Figure 7. WOT Torque-Speed Curves for Three Engine Classes ..................................... 15 Figure 8. Pre-Chamber Design Example .......................................................................... 17 Figure 9. Brake Thermal Efficiency against EGR ............................................................ 19 Figure 10. Normalized Bi-fuel BSFC ............................................................................... 20 Figure 11. BMEP at full load, nominal performance for each fuel .................................. 22 Figure 12. Laminar Flame Speed at 10x atmospheric pressure ........................................ 24 Figure 13. Schematic setup of a catalyst coated heat exchanger with bypass valve ........ 29 Figure 14. Aged bi-fuel taxi emissions measurements ..................................................... 30 Figure 15. 1-D Engine Model Block Diagram.................................................................. 32 Figure 16. Laminar Flow Element Setup .........................................................................