Motor Vehicles & Air Quality

Transcription

1 Motor Vehicles & Air Quality Britt A. Holmén Civil & Environmental Engineering December 13, 2005 Presentation to ENGR Alumni

2 Ozone Nonattainment in the U.S.

3 Chiras (2001) Criteria Pollutant Sources (1997)

4 How Vehicles Affect Air Quality Big Picture: Transportation/Environment PM & How We Measure It PM vs. ultrafine/nano particles Why are they harmful? Observations from Some Field Studies Connecticut Hybrid Transit Bus Light-duty Vehicles (a professor s mini-van)

5 Trans/AQ Big Picture Transportation Network Vehicle Activity Reaction Dispersion Space/Time Allocation Vehicle Emissions Emission Factors Fleet Composition Human Health Urban,Regional,Local CONCENTRATIONS Environmental Health

6 LDV Vehicle Miles Traveled (VMT) & Gasoline Use 2%/yr VMT 24 mpg assumed

7 Tailpipe Emissions Gasoline Engines Diesel Engines CO NO x CO HC NO x soot HC After Jeffrey B. Burl and Duane Abata Michigan Tech University

8 Diesel Exhaust Particles Agglomerated spherules; chain aggregates Heywood, 1988

9 Diesel Particle Size Distribution Peak in Number Distribution ~ 20nm Normalized Particle Concentration Nanoparticles Dp < 50 nm Ultrafine Particles Dp < 100 nm Diameter (μm) Alveolar Deposition Fraction Number Weighting After D. Kittelson 1998

10 Particle Size & Lung Deposition The human lungs cannot easily reject ultrafine particles! Normalized Particle Concentration Nanoparticles Dp < 50 nm Ultrafine Particles Dp < 100 nm Diameter (μm) Alveolar Deposition Fraction Number Weighting Alveolar Deposition Fraction After D. Kittelson 1998

11 Transportation & Emissions Road Type Congestion Land-use Grade Vehicle Operating Mode DRIVER Signalization Emissions The transportation system and its environment are linked to tailpipe emissions via the vehicle-operating mode.

12 Two Key Models Spatial mode model how built environment affects driving mode (land use, road type, grade, traffic signalization and congestion) Vehicle modal emissions model vehicle operating parameters (mode, intensity, duration, frequency) relationships to emissions NO x soot CO HC

13 Measuring Vehicle Emissions Laboratory (traditional) Dynamometer Bag tests (driving cycles) e.g., Connecticut DMV emissions test Unrealistic for today s driving On-board Emissions Testing (New!) Real-world vehicle operation Allows linking emissions to location Limited vehicle sampling ($$); need robust emissions model

14 1997 Toyota Sienna Minivan Minivan Emissions Experiment Portable analyzers Gases Particle Number Scantool Accelerometers GPS Video Camera Battery power

15 Particle Number Instrument Particle Number nm Mini-dilution tunnel 1 Hz

16 Accelerometers, ScanTool,, GPS

17 Sample drawn from tailpipe Generator and Air Compressor Transit Bus On-Board Emissions Testing Experimental Setup

18 Modal Emissions Modeling Identify Operating Mode Parameters Affecting Emissions Ultrafine particles increase with %Load & acceleration from stop. 3.0x10 7 Particle Concentration Speed Load 100 Particle Concentration (#/cm 3 ) 2.5x x x x x Speed (MPH) and Engine Load (%) Time in Route (Second) 0 Aug 4 th, Farmington Ave. Outbound

19 Spatial Location of High Emissions Higher Concentrations: Intersections Bus Stops Maps by E. Jackson. UConn Civil Engineering

20 Personal: Walk, Bike Solutions! Carpool, Bus, Smaller Cars Reduce Driving Speed Avoid Quick Acceleration Technological: Aftertreatment Catalysts, Filters Cleaner Vehicles CNG, Hybrids

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22 Acknowledgments Financial support: National Science Foundation New England University Transportation Consortium Joint Highway Research Advisory Council CTTransit Field Testing & Data Analysis: Derek Vikara, Yingge Qu, Eric Jackson, Zhong Chen, Ruben Mamani-Paco, Aura Davila, Oliver Gao, Jason Lewandowski, Brad Harwood (UConn students & post-docs) John Warhola, Jimmy Dowd (CTTransit) Collaborators: Lisa Aultman-Hall (CEE) Baki Cetegen (ME)