Publication Date
5-2002
Document Type
Technical Report
Organizational Units
College of Natural Science and Mathematics, Chemistry and Biochemistry
Keywords
Atmospheric chemistry, Emissions, Pollutants
Abstract
The University of Denver conducted a five-day remote sensing study in the Phoenix, AZ area in the fall of 2000. The remote sensor used in this study is capable of measuring the ratios of CO, HC, and NO to CO2 in motor vehicle exhaust. From these ratios, we calculate mass emissions per kg (or gallon) of fuel and the percent concentrations of CO, CO2, HC and NO in motor vehicle exhaust which would be observed by a tailpipe probe, corrected for water and any excess oxygen not involved in combustion. The system used in this study was also configured to determine the speed and acceleration of the vehicle, and was accompanied by a video system to record the license plate of the vehicle. Furthermore, a second FEAT unit was set up and measured vehicles at two other location on the ramp. Five days of fieldwork (November 13-17, 2000) were conducted on the uphill exit ramp from Hwy 202 / Sky Harbor Blvd. Westbound to Hwy 143 Southbound in Phoenix, AZ. A database was compiled containing 20,801 records for which the State of Arizona provided make and model year information. All of these records contained valid measurements for at least CO and CO2, and 20,700 contained valid measurements for HC and NO as well. The database, as well as others compiled by the University of Denver, can be found at www.feat.biochem.du.edu . The mean percent CO, HC, and NO were determined to be 0.37%, 0.0099%, and 0.045%, respectively. The fleet emissions measured in this study exhibit a gamma distribution, with the dirtiest 10% of the fleet responsible for 75%, 71%, and 53% of the CO, HC, and NO emissions, respectively. This year’s HC readings seem to contain a negative offset such that the average HC of the cleanest make and model years are negative. Comparisons include removal of this negative offset. This was the third year of a multi-year continuing study to characterize motor vehicle emissions and deterioration in the Phoenix area. However, because of the non-ideal driving mode at the site in the first year (1998), a new ramp similar to the Denver, Chicago and L.A. Basin sites had been used in 1999 and was again used this year. In 1999 measurements were made at two locations on the same ramp. Thus, this year a second instrument was used to measure at one of the locations while the main measurements were made throughout the week at the other more suitable location. Measurements were also made with the second instrument and a RSD3000 from ESP just upstream of the first instrument. A comparison of measurements made at three locations on the ramp used this year showed that correctly measured VSP can account for many of the emissions differences observed at the two locations in 1999. An intercomparison of three on-road remote sensing instruments indicated that the devices measured pollutants equivalently and that data from the instruments can be compared when binned by model year. Vehicle emissions as a function of vehicle specific power revealed that NO emissions show a positive dependence on specific power when speed and acceleration are measured before emissions. HC emissions show a negative dependence on specific power – the expected trends. Carbon monoxide emissions show a slight negative dependence on On-Road Remote Sensing of Automobile Emissions in the Phoenix Area: Year 3 2 specific power in the range from –5 to 25 kW/tonne. Using vehicle specific power, it was possible to adjust the emissions of the vehicle fleet measured in 2000 to match the vehicle driving patterns of the fleet measured in 1999 (at the two locations) and 1998. After doing so, it was seen that the emissions measured in the current year are not significantly different from those measured during the previous two years. Model year adjustments gave similar results. Tracking of model year fleets through three measurements indicated that the rate of emissions deterioration increases significantly after the vehicle has aged several years, though the analysis was somewhat confounded by alterations in measurement site. An analysis of high emitting vehicles showed that there is considerable overlap of CO and HC high emitters, for instance 2.7% of the fleet emit 20% of the total CO and 19% of the total HC. The noise levels in the CO, HC and NO measurement channels were determined to be minimal.
Copyright Statement / License for Reuse
Copyright Date
5-1-2002
Rights Holder
Sajal S. Pokharel, Gary A. Bishop, Donald H. Stedman
Provenance
Received from author
File Format
application/pdf
Language
English (eng)
Extent
41 pgs
File Size
676 KB
Publication Statement
Copyright is held by the authors. User is responsible for all copyright compliance.
This research was supported by the nonprofit Coordinating Research Council, Inc. (CRC). The final results of the research conducted by, or under the auspices of, CRC are available to the public.
Recommended Citation
Pokharel, S. S., Bishop, G. A., & Stedman, D. H. (2002). On-road remote sensing of automobile emissions in the Phoenix area: Year 3. Atlanta, GA: Coordinating Research Council.