Light-Duty Motor Vehicle Exhaust Particulate Matter Measurement in the Denver, Colorado, Area.

A study of particulate matter (PM) emissions from in-use, light-duty vehicles was conducted during the summer of 1996 and the winter of 1997 in the Denver, CO, region. Vehicles were tested as received on chassis dynamometers on the Federal Test Procedure Urban Dynamometer Driving Schedule (UDDS) and the IM240 driving schedule. Both PM10 and regulated emissions were measured for each phase of the UDDS. For the summer portion of the study, 92 gasoline vehicles, 10 diesel vehicles, and 9 gasoline vehicles with visible smoke emissions were tested once. For the winter, 56 gasoline vehicles, 12 diesel vehicles, and 15 gasoline vehicles with visible smoke were tested twice, once indoors at 60 °F and once outdoors at the prevailing temperature. Vehicle model year ranged from 1966 to 1996. Impactor particle size distributions were obtained on a subset of vehicles. Continuous estimates of the particle number emissions were obtained with an electrical aerosol analyzer. This data set is being provided to the Northern Front Range Air Quality Study program and to the State of Colorado and the U.S. Environmental Protection Agency for use in updating emissions inventories.

The Effect of Ethanol Fuel on the Emissions of Vehicles over a Wide Range of Temperatures.

The emissions from a fleet of 11 vehicles, including three from the State of Alaska, were tested at 75, 0, and -20 °F with base gasolines and E10 gasolines, that is, gasolines with 10% by volume ethanol added. The data for the changes in emissions for the test run at 75 °F are included, since most other studies on the effects of E10 gasoline on emissions were run at that temperature. The three Alaskan vehicles were also tested at 20 °F. The testing followed the Federal Test Procedure, and regulated emissions-CO, total hydrocarbons (THC), and nitrogen oxides (NOx)-CO2, speciated organics, and fuel economy were measured. A total of 490 FTP tests were run. The data obtained indicated that with most vehicles, at the temperatures tested, improvements in both CO and THC emissions were obtained with the use of E10 fuel. At the lowest temperature used, -20 °F, most vehicles had an increase in NO emissions with the use of E10 fuel. At the other temperatures, however, more vehicles showed a decrease in NOx emissions with the use of E10. With all vehicles at all temperatures tested, the emissions of acetaldehyde increased significantly when E10 fuel was used. The highest increase was about 8 to 1. Benzene, formaldehyde, and 1,3 butadiene showed both increases and decreases in the emissions when using E10 fuel. Unexpected results were obtained with the fuel economy, with about half of the tests showing an increase in fuel economy with the use of E10 fuel.

Influence of Ethanol-Blended Fuels on the Emissions from Three Pre-1985 Light-Duty Passenger Vehicles.

Tailpipe and evaporative emissions from three pre-1985 passenger motor vehicles operating on an ethanol oxygenated and on a nonoxygenated (base) fuel were characterized. Emission data were collected for vehicles operating over the Federal Test Procedure at 90 °F, 75 °F, and 40 °F to simulate ambient driving conditions. The two fuels tested were a commercial summer-grade regular gasoline (the nonoxygenated base fuel) and an oxygenated fuel containing 8.8% ethanol, more paraffins and olefins, and less aromatics than the base fuel. The Reid vapor pressure (RVP) was adjusted to correspond to that of the base fuel. The emissions measured were total hydrocarbons (THCs), speciated hydrocarbons, spedated aldehydes, carbon monoxide (CO), and oxides of nitrogen (NOX). This study showed a general reduction in tailpipe emissions of THC, CO, benzene, and 1,3-butadiene when tested with the ethanol fuel. The ethanol fuel significantly reduced these emissions from the high emitting vehicle, MU098, at 90 °F, 75 °F, and 40 °F test temperatures. Additionally, the ethanol fuel reduced CO emissions from vehicle BU950, with and without catalyst, and from vehicle CI415 at 40 °F. Both formaldehyde and acetaldehyde emissions generally increased when tested with the oxygenated fuel. The acetaldehyde emissions were about double with this fuel. The limited data indicate that most emissions, including toxics, occur during the first 124 seconds of vehicle start-up. Diurnal evaporative emissions were less from the oxygenated fuel, while hot-soak evaporative emissions were greater from the oxygenated fuel (for all vehicles except MU098). Evaporative emissions were generally greatest at the 90 °F test temperature.

An Experimental Evaluation of Remote Sensing-Based Hydrocarbon Measurements: A Comparison to FID Measurements.

The purpose of this study was to intercompare hydrocarbon (HC) measurements performed by a number of different instruments: a gas chromatograph (GC), a flame ionization detector (FID), a fourier transform infrared spectrometer (FTIR), a commercially produced non-dispersive infrared analyzer (NDIR), and two remote sensors. These instruments were used to measure total HC concentrations in a variety of samples, including (1) ten different individual HC species, (2) 12 different vehicle exhaust samples, and (3) three different volatilized fuel samples. The 12 exhaust samples were generated by operating two different vehicles on a dynamometer. Each vehicle was operated at different times with three different fuels. The vehicles were operated fuel rich, i.e., with low air/fuel ratios to encourage elevated exhaust HC levels. Some of the exhaust samples were obtained while operating each vehicle at a stoichiometric air/fuel ratio with one spark plug wire disconnected. To quantify the degree to which the various instruments agreed with the FID, a parameter called the response factor was used, where the response factor was defined as the HC/CO2 ratio measured by each instrument divided by the HC/CO2 ratio measured by the dynamometer bench. Of the various instruments, only the GC yielded response factors that were consistently at or close to one. The other instruments typically had values at or below one. For the ten individual HC species studied, the NDIR and remote sensors obtained response factors between 0.05 and 1.0, with the highest response factors being obtained for the alkanes and the lowest response factors obtained for toluene and ethylene. For the exhaust samples, the NDIR and remote sensors obtained response factors between 0.23 and 0.68. For raw fuel samples, the response factors were between 0.44 and 0.68. NDIR and remote sensor measurements correlated very poorly with total HC in exhaust.