Effects of Gasoline Composition on Vehicle Engine-Out and Tailpipe Hydrocarbon Emissions - The Auto/Oil Air Quality Improvement Research Program

Leppard, William R.; Rapp, Larry A.; Burns, Vaughn R.; Gorse, Robert A.; Knepper, Jay C.; Koehl, William J.

doi:10.4271/920329

Cited by 48 publications

(20 citation statements)

References 13 publications

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“…A summary of the most abundant compounds in liquid gasoline, headspace vapors, and tunnel emissions is shown in Table 2. In subsequent analyses, tunnel and liquid fuel weight fractions were averaged together because of collinearity of these profiles: ∼50% of VOC mass in tailpipe emissions consists of unburned gasoline [ Leppard et al , 1992].…”

Section: Resultsmentioning

confidence: 99%

Temperature dependence of volatile organic compound evaporative emissions from motor vehicles

Rubin¹,

Kean²,

Harley³

et al. 2006

J. Geophys. Res.

125

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[1] A chemical mass balance approach is used to determine the relative contributions of evaporative versus tailpipe sources to motor vehicle volatile organic compound (VOC) emissions. Contributions were determined by reconciling time-resolved ambient VOC concentrations measured downwind of Sacramento, California, in summer 2001 with source speciation profiles. A composite liquid fuel speciation profile was determined from gasoline samples collected at Sacramento area service stations. Vapor-liquid equilibrium relationships were used to determine the corresponding headspace vapor composition. VOC concentrations measured in a highway tunnel were used to define the composition of running vehicle emissions. The chemical mass balance analysis indicated that headspace vapor contributions ranged from 7 to 29% of total vehicle-related VOC depending on time of day and day of week, with a mean daytime contribution of 17.0 ± 0.9% (mean ± 95% CI). A positive association between the headspace vapor contribution and ambient air temperature was found for afternoon hours. We estimate a 6.5 ± 2.5% increase in vapor pressure-driven evaporative emissions and at least a 1.3 ± 0.4% increase in daily total (exhaust plus evaporative) VOC emissions from motor vehicles per degree Celsius increase in maximum temperature.

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Section: Resultsmentioning

confidence: 99%

Temperature dependence of volatile organic compound evaporative emissions from motor vehicles

Rubin¹,

Kean²,

Harley³

et al. 2006

J. Geophys. Res.

125

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“…There is uncertainty with the extent that fuel composition can be used as a proxy for SOA precursors in vehicle exhaust, which is also discussed in the following approach and the synthesis section as the predicted SOA based on fuels does not always match observations. Fuel-based SOA precursors that are emitted unburnt in exhaust are compositionally consistent with fuels, but there are enhancements in benzene, cyclohexane and cyclopentane that are intermediate species formed during the combustion of larger molecules. ,,, Large differences tend to occur with products of incomplete combustion. However, it has been suggested that the composition of organics in exhaust can also be skewed by the enrichment of larger compounds with the lowest combustion efficiency. , …”

Section: Bottom-up Methods #1: Understanding Soa Formation Potential ...mentioning

confidence: 93%

“…Commonly measured products of incomplete combustion (e.g., light alkanes, alkenes, small oxygenated species) comprise a significant fraction (30–50%) , of exhaust emissions, but based on the current state of knowledge they have only minor direct implications on SOA formation via gas-phase chemistry. , This has been shown for gasoline exhaust, both historically , and more recently. , In addition to small alkane/alkene products of incomplete combustion, diesel exhaust also contains a significant fraction of carbonyls as byproducts of pyrolysis, the prominent smaller species of which are not known to form SOA via gas-phase chemistry. ,,, A key standing question is quantifying the potential SOA production from combustion or exhaust aftertreatment byproducts. However, they have not been characterized, only inferred based on individual vehicle tests (next section).…”

Section: Bottom-up Methods #1: Understanding Soa Formation Potential ...mentioning

confidence: 99%

Review of Urban Secondary Organic Aerosol Formation from Gasoline and Diesel Motor Vehicle Emissions

Gentner

Jathar

Gordon

et al. 2017

Environ. Sci. Technol.

401

315

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Secondary organic aerosol (SOA) is formed from the atmospheric oxidation of gas-phase organic compounds leading to the formation of particle mass. Gasoline- and diesel-powered motor vehicles, both on/off-road, are important sources of SOA precursors. They emit complex mixtures of gas-phase organic compounds that vary in volatility and molecular structure-factors that influence their contributions to urban SOA. However, the relative importance of each vehicle type with respect to SOA formation remains unclear due to conflicting evidence from recent laboratory, field, and modeling studies. Both are likely important, with evolving contributions that vary with location and over short time scales. This review summarizes evidence, research needs, and discrepancies between top-down and bottom-up approaches used to estimate SOA from motor vehicles, focusing on inconsistencies between molecular-level understanding and regional observations. The effect of emission controls (e.g., exhaust aftertreatment technologies, fuel formulation) on SOA precursor emissions needs comprehensive evaluation, especially with international perspective given heterogeneity in regulations and technology penetration. Novel studies are needed to identify and quantify "missing" emissions that appear to contribute substantially to SOA production, especially in gasoline vehicles with the most advanced aftertreatment. Initial evidence suggests catalyzed diesel particulate filters greatly reduce emissions of SOA precursors along with primary aerosol.

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“…Separate emission factors were determined for cars and light-duty trucks (pickups, vans, and sport utility vehicles) of each model year, except for pre-1975 models where vehicle type was often not specified in registration records. [Lonneman, 1998].…”

mentioning

confidence: 99%

Analysis of motor vehicle emissions during the Nashville/Middle Tennessee Ozone Study

Harley¹,

McKeen²,

Pearson³

et al. 2001

J. Geophys. Res.

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Abstract. On-road gasoline and diesel-powered vehicle emissions in Nashville, Tennessee, were characterized using fuel sales as a measure of vehicle activity, and emission factors derived from infrared remote sensing, ambient air concentration ratios, and roadway tunnel measurements. On-road vehicle emissions of carbon monoxide (CO), nonmethane hydrocarbons (NMHC), and oxides of nitrogen (NOx) on weekdays during summer 1995 were estimated to be 270 _+ 60, 43 _+ 13, and 53 _+ 9 metric tons per day, respectively. Diesel engines were a minor source of CO and NMHC, but were responsible for --•50% of NO x emissions from on-road vehicles. The Environmental Protection Agency's MOBILE 5B emission model predictions were similar to fuel-based estimates for all pollutants, except for NOx where the MOBILE model predicted a smaller contribution to total on-road vehicle emissions from diesel engines. Chemical composition profiles for hydrocarbon emissions were developed based on tunnel air and fuel samples collected in Nashville during summers 1995 and 1999. More than half of the tunnel NMHC mass was liquid fuel that escaped combustion; the remaining mass came from products of incomplete combustion such as ethane, acetylene, C2-C 4 alkenes, and 1,3-butadiene. No major changes in the composition of vehicle-related NMHC emissions were observed between 1995 and 1999 in Nashville. IntroductionComprehensive air quality field studies were conducted in the Nashville, Tennessee, area during the summers of 1994, 1995, and 1999 to study the formation of photochemical air pollution (for an overview of the study, see Meagher et al.

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Effects of Gasoline Composition on Vehicle Engine-Out and Tailpipe Hydrocarbon Emissions - The Auto/Oil Air Quality Improvement Research Program

Cited by 48 publications

References 13 publications

Temperature dependence of volatile organic compound evaporative emissions from motor vehicles

Temperature dependence of volatile organic compound evaporative emissions from motor vehicles

Review of Urban Secondary Organic Aerosol Formation from Gasoline and Diesel Motor Vehicle Emissions

Analysis of motor vehicle emissions during the Nashville/Middle Tennessee Ozone Study

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