The effects of oxygenate addition on emissions reduction in small utility engines

摘要

Oxygenates have been blended with gasoline for automotive use in the United States since the late 1970's as an octane enhancer. increased use of oxygenates in fuel was seen in the late 1980's in selected geographic areas in winter months to reduce carbon monoxide emissions. The 1990 US Clean Air Act Amendments introduced further requirements to increase th euse of oxygenated fuels in carbon monoxide nonattainment areas and reformulated fuels in ozone nonattainment areas. The oxygenated fuel program and reformulated fuel program both incorporate oxygenates with the objective of reducing carbon monoxide (the oxygenated fuel programs) directly and hydrocarbons and nitrogen oxides (the reformulated fuel programs) with the objective of reducing ground level ozone. Figure 1 illustrates the general trends in exhaust emissions concentration that result from oxygenate fuel blending. The predominate enleanment effect reduces hydrocarbon and carbon monoxide emissions while the effect of more complete comustion beneficially alters the carbon monoxide and nitrogen oxides emission relationships.