Effects of Oxygen and Aromatic Content in Gasoline on Gaseous Pollutant Emissions from Four-stroke Motorcycles

• Main Authors: Kai-ChunChang, 張開駿
• Other Authors: Jiun-Horng Tsai
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/30782324938183718048

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 98 === This study has been conducted to investigate the effects of oxygen and aromatic content in gasoline on air pollutant emissions from four-stroke motorcycles. Two test fuels were used in this study. The first one was ethanol-gasoline blend which contains 15 vol% ethanol in gasoline (E15). The second test fuel was aromatic-lean gasoline which contained 15 vol% aromatics in fuel (A15). The results of all test fuels were compared to the commercial unleaded gasoline as reference fuel (RF), in which methyl tert-butyl ether (MTBE) was the oxygenated additive. The target pollutants included criteria air pollutants, volatile organic compounds (VOCs), carbonyls, and organic air toxics (benzene, toluene, ethylbenzene, xylene, formaldehyde, and acetaldehyde). Three test motorcycles with engine displacement of 125 cm3 and different accumulated millage were tested on a dynamometer with ECE test cycle. The results showed that CO and THC emissions decreased and NOx emissions increased when used E15 as the fuel compared to those of RF in the in-use motorcycles. THC emission from high-mileage motorcycle increased 2%. When using A15 as fuel, CO, THC, NOx emissions decreased as compared to those of RF, but THC emission increased 8% for high-millage motorcycle. The results implied a strong negative relationship between CO emission and fuel oxygen and olefins contents. Using E15 as the fuel reduced emissions of total VOCs, alkanes, alkenes, and aromatics groups. In contrast, the emissions of carbonyls group increasing about two folds as compared to the RF applied in the medium- and high-millage motorcycles. High emissions of acetaldehyde contributed high carbonyl group emission while using ethanol blend. The results showed that the total VOC emissions decreased as using A15 as fuel. The emissions of alkanes, alkenes, aromatics, and carbonyls groups decreased generally as compared to those from the RF, expect that high-mileage motorcycle showed a higher emission of alkenes and carbonyls. The correlation results implied a strong-negative relationship between the carbonyl emission and the fuel oxygen and olefins contents. The results of air toxics emissions, showed that E15 and A15 reduced the emissions of benzene, toluene, ethylbenzene, xylene (BTEX) from all test motorcycles compared to those from RF. Using E15 as fuel increases emissions of formaldehyde and acetaldehyde. Acetaldehyde emission increased about 9 times than that from RF. The ozone-forming potential (OFP) of VOCs in the engine exhaust showed that using E15 as fuel increased OFP about 6~16% for medium- and high-mileage motorcycles. Higher carbonyls emissions is the main reason that contributed high OFP while using ethanol blend. As using A15 OFP decreased 11~20%. Using ethanol-blended gasoline as fuel may reduce criteria pollutant emissions effectively than using A15 as fuel. On the other hand, using E15 as fuel may cause high carcinogenic and hazard impact because of higher acetaldehyde emissions. In summary, the criteria pollutant emissions may decrease when use E15 or A15 as fuel as compared those from the RF; the E15 also showed a higher emission reduction than those from A15. However, using E15 had the higher OFP and toxicity because of the higher emission of formaldehyde and acetaldehyde.