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Effect of Oxygenates and Fuel Volatility on Vehicle Emissions at Seasonal Temperatures
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Abstract
This study examined the emissions characteristics of non-tampered, in-use vehicles when operated on premium fuels at seasonal temperatures typical of the Northeast United States. Two test vehicles representing different emission control systems were tested: a 1980 carburetion vehicle with an oxidation catalyst (C/OC), and a 1985 port fuel injection (PFI) vehicle with closed loop three way catalyst (TWC). The tests were performed at low and intermediate temperatures (20°F,35°F,50°F and 70°F) with premium fuels blended to meet volatility specifications which corresponded to these seasonal temperatures. Fuels containing methyl tertiary butyl ether (MTBE) and ethanol were included to investigate the relative effect of these oxygenates on exhaust emissions at different temperatures.
Results from the exhaust emissions tests showed that exhaust hydrocarbon and carbon monoxide emissions of the C/OC vehicle increased as temperature decreased. Below 50°F, the PFI/TWC vehicle also exhibited an increase in exhaust emissions with a decrease in test temperature. The temperature effect on exhaust emissions was greater than the differences due to fuel vapor pressure variances and/or fuel oxygen content. At higher temperatures, 50°F and 70°F, increased fuel volatility produced a slight increase in carbon monoxide emissions of both vehicles. Generally, the vehicles showed a downward trend in carbon monoxide emissions from fuel oxygen. Diurnal evaporative emissions increased with an increase in the fuel vapor pressure at the test temperature.
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Doherty, H. and Douthit, W., "Effect of Oxygenates and Fuel Volatility on Vehicle Emissions at Seasonal Temperatures," SAE Technical Paper 902130, 1990, https://doi.org/10.4271/902130.Also In
References
- Darlington T.L. Platte L. Shih C. “Effects of Fuel Volatility and Temperature on Vehicle Evaporative Emissions,” SAE Paper 860529 February 1986
- “Performance Characteristics of Oxygenated Fuels for Emission Reduction Programs,” Oxygenated Fuels Association, Inc. February 1990
- 40 Code of Federal Regulations, Part 86, Subpart B, Sections 86.101 through 86.145 “Emissions Regulations for 1977 and Later Model Year New Light-Duty Vehicles and Light-Duty Trucks; Test Procedures.”
- Doner J. P. “A Predictive Study for Defining Limiting Temperatures and Their Applications in Petroleum Product Specifications,” Coating and Chemical Laboratory Aberdeen Proving Ground Maryland November 1972
- Most W. J. “Coordinating Research Council Study of Winter Exhaust Emissions with Gasoline/Oxygenate Blends,” SAE Paper 89091 September 1989