Effect of Fuel Composition on Amount and Reactivity of Evaporative Emissions

The Reactivities of Gasoline Vapors in Photochemical Smog

“…All experiments are conducted at a light intensity which gives a rate constant (Kd) for the photolytic decomposition of nitrogen dioxide (2 ppm) in nitrogen of 0.4 min" 1 . The chamber temperature before the lights are turned on is 22°C; after irradiation begins, the temperature of the glass chambers is maintained at 27 °C, and the contents of the steel chamber are held at 32° C. Samples removed from the chambers for analysis are immediately replaced by pure air, and we correct for the resultant dilution (no more than 10% for the larger chambers) in all calculations.…”

“…Thus, several laboratories and cooperative study groups (Coordinating Research Council and American Petroleum Institute) have investigated the ways in which fuel properties (especially the amounts and types of C4-C5 hydrocarbons) influence both the amount and the potential atmospheric reactivity of evaporative emissions. 1 "" 6 But fuel evaporation accounts for only a small portion of the total hydrocarbons emitted by automobiles, and gasoline modifications (such as volatility reductions) that reduce evaporative losses can lead to higher levels of hydrocarbons in automobile exhaust. 4 " 6 A joint undertaking by the California Air Resources Board, Los Angeles County Air Pollution Control District, and Western Oil and Gas Association recently evaluated the possibility of reducing photochemical smog in Los Angeles by either lowering gasoline volatility or by removing C4 and C 5 olefins from automotive fuels.…”