Air Pollutant Emissions from a Four-Stroke Motorcycle Engine Influenced by Gasoline Aromatic Content

Yungchen Yao; Anlin Chang; Jiunhorng Tsai
Motorcycles are one of the dominant sources of air pollutants in many Asian countries. This study focuses on the effect of fuel aromatic content on motorcycle emissions. Two levels of aromatic content test-fuels were designed to investigate the criteria pollutant emissions [CO, total hydrocarbons (THCs), and NOx] and gaseous organic compounds in the exhaust from a non-catalyst four-stroke motorcycle engine. All experiments were operated in a cold start mode. The data indicate that lowering aromatic content in gasoline from 30 to 20% (by volume) reduced the CO and THC emission by 8-17% and 38%, respectively, especially in the cruising test. The NOx emission, however, showed an inverse correlation with the aromatic content in gasoline. Contrary to expectations, the emission factors of four organic groups and ozone formation potential showed that the low aromatic fuel with highest emission factors. While a reduction of aromatic content in gasoline may decrease emissions of benzene and toluene, it will increase the emission of aldehyde. Since the percentage changes of emission factor of THC and air toxics in the motorcycle were larger than those in passenger cars, the benefit of emission reduction due to fuel composition changes in motorcycles may have significant impacts in health risk analysis.
Motorcycle; Aromatic Contents; Criteria Air Pollutant; Organic Air Pollutants; Ozone Formation Potential
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