Inventory and Prediction of Heavy Duty Diesel Vehicle Emissions

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Inventory and Prediction of Heavy-Duty Diesel Vehicle EmissionsBy Justin M. Kern

A THESIS Submitted to The College of Engineering and Mineral Resources at West Virginia University

in partial fulfillment of the requirements for the degree of Masters of Science in Mechanical Engineering

Nigel N. Clark, Ph.D., Chair Christopher M. Atkinson, Sc.D. Gregory J. Thompson, Ph.D. Ralph D. Nine, MSME

Department of Mechanical and Aerospace Engineering

Morgantown, West Virginia 2000

Keywords: Emissions Inventory, Emissions Prediction, Heavy-Duty Vehicle Emissions

ABSTRACT INVENTORY AND PREDICTION OF HEAVY-DUTY DIESEL VEHICLE EMISSIONS By Justin M. Kern A vehicle emissions inventory is an account of emissions produced by all vehicles in an area. Many different factors can affect the emissions and the measurement of the emissions that are used to create an emissions inventory. These factors for heavy-duty diesel vehicles have been addressed and their relative affect on emissions was evaluated from test data and analytical analyses. These elements can affect the emissions by a factor of 15 depending on testing conditions. One purpose that an emissions database serves is to provide a source for predicting future emissions for a specific vehicle or many vehicles in a general area. Using a database directly for prediction is ideal, but no comprehensive data set currently exists that covers all of the different vehicle and component combinations that exist in current use. Numerical models can be used to take the existing information about vehicle emissions and calculate the emissions that would be produced by all the vehicles in an inventory. The Transportable Heavy-Duty Vehicle Emissions Testing Laboratories at WVU have collected emissions data from heavy-duty vehicles for approximately 8 years. This existing data were used in an analysis to develop a method that can produce emissions factors in grams per mile for all heavy-duty vehicles from a small database of measured emissions. The method developed categorizes the emissions

according to the vehicle speed and acceleration. The WVU emissions data were combined with truck activity data derived by Battelle Memorial Institute to create emissions factors in grams per mile that reflects actual driving patterns. These factors were then compared to measured

emissions from the THDVETL and errors were found to be as low as 5%.

Acknowledgements Many people deserve a lot of thanks and credit for helping me complete this research and thesis. First, I thank Nigel for giving me the opportunity to attend graduate school and for all the help and guidance provided during the course of my stay here. Next, I thank the rest of my committee, Chris Atkinson, Greg Thompson, and Ralph Nine for their help and the time theyve devoted to this. Special thanks goes to Ralph for teaching me how the system works, all the

technical help, and for being a good friend. The Los Alamos National Laboratory and the NCHRP research projects are responsible for funding the research that led to this monstrosity and they deserve thanks for that. Thanks to the mobile lab crew for their efforts in collecting the data used for this research, and thanks to the guys at the ERC for their technical assistance and cynical pessimism. I couldnt have endured the this ordeal without the support of the friends Ive made along the way, and for that I owe a special thanks to John, Dave, Marcus, Steve, Amy and many more Ive failed to mention. The heckling and guidance were both appreciated. My family has provided support in many ways and for that, thank you very much, Mom and Dad especially.

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Table of Contents Title Page..........................................................................................................................................i Abstract............................................................................................................................................ii Acknowledgements....................................................................................................................iii Table of Contents.......................................................................................................................iv List of Tables.............................................................................................................................vi First of Figures.........................................................................................................................viii Nomenclature .............................................................................................................................x 1. Introduction.........................................................................................................................1 1.1 Exhaust Emissions.......................................................................................................1 1.2 Origin of Data .............................................................................................................1 1.3 Technical Description of Laboratory............................................................................2 2. Objectives ...........................................................................................................................5 3. Literature Review: Previous Prediction Methods ................................................................6 3.1 Current EPA Heavy-Duty Inventory Method ...............................................................6 3.2 Other Variations of Heavy-Duty Prediction .................................................................8 3.3 Light-Duty Methods ....................................................................................................8 4. Factors Affecting Compression Ignition Engine Emissions..................................................9 4.1 Vehicle Class...............................................................................................................9 4.2 Driving Test Schedules..............................................................................................14 4.2.1 Review of Driving Schedules.................................................................................14 4.2.2 Test Cycle Emissions Comparison .........................................................................29 4.3 Vehicle Vocations, Weight, and Local Driving Activity.............................................37 4.4 Fuel Type ..................................................................................................................39 4.5 Exhaust Aftertreatment..............................................................................................42 4.6 Vehicle Age...............................................................................................................44 4.7 Terrain Traveled ........................................................................................................47 4.8 Injection Timing Variances........................................................................................50 4.9 Summary of Factors Affecting CI Emissions .............................................................52 5. Methods of Generating Emissions Factors.........................................................................55 5.1 Certification Data ......................................................................................................55 5.2 Chassis Dynamometer Data.......................................................................................58 5.3 Power-Based Emissions Factors ................................................................................61 5.4 NOX / CO2 Ratios ......................................................................................................68 5.5 Speed-Acceleration Based .........................................................................................69 6. Methodology of Producing Speed Acceleration Based Emissions Factors.......................72 6.1 Speed Acceleration Profiles of Test Schedules and Creation of the Kern Cycle.......72 6.2 Vehicle Class and Model Year Divisions ...................................................................76 6.3 Time Alignment ........................................................................................................76 6.4 Converting data from ppm to grams per second .........................................................77 6.5 Calculation of Axle Power.........................................................................................78 6.6 Proportioning PM to CO............................................................................................78 6.7 Speed Acceleration Tables and Methods Used to Fill Empty Cells..........................78 6.7.1 Linear Extrapolation ..............................................................................................81 6.7.2 Power-Based Extrapolation....................................................................................82

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6.8 Converting Emissions to Units of g/mile Using Speed-Acceleration Profiles .............82 7. Results of Emissions Prediction.........................................................................................86 7.1 Comparison of Results...............................................................................................86 7.2 Incorporation of Various Factors Effecting Emissions ...............................................90 7.2.1 Effect of Age/Mileage-Accumulation on Emissions...............................................90 7.2.2 Cold Start Emissions..............................................................................................91 7.2.3 Off-Cycle Operation ..............................................................................................93 7.3 Conclusions and Rec