Study of Organic Air Toxics for Vehicles Emission by using Ethanol-Blend Gasoline in Tainan Urban Area

• Main Authors: Shiang-WeiTien, 田湘薇
• Other Authors: Jiun-Hung Tsai
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/7k3bu7

碩士 === 國立成功大學 === 環境工程學系 === 102 === This study investigated the effect of ethanol-gasoline blends on organic air toxics emissions from on-road gasoline mobile sources and its influence on air quality by using MOBILE 6.2 model and AERMOD model, respectively. Three fuels were conducted as simulation scenarios, including one commercial gasoline (G95) and two ethanol-gasoline blends (E3 and E15). Tainan urban area was chosen as simulation area. Six major air toxics, including benzene, MTBE, 1,3-butadiene, formaldehyde, acetaldehyde, and acrolein, were selected as target air toxics. Health risk assessment of selected air toxics is also evaluate. The results showed that the estimated emission factors of target pollutant from MOBILE 6.2 are 1.1 to 8.9 folds those from field sampling data, except acetaldehyde and benzene. Formaldehyde represents the largest difference (7.9-8.9 times), following by acrolein (1.2-2.1 times). Using ethanol-gasoline blends as fuel showed that the emission reductions of benzene, MTBE, 1,3-butadiene, and acrolein emissions compared to those from G95, but increased carbonyl emissions. The results of sensitivity test showed that the ethanol, aromatics, and alkenes in fuel may result in different toxics emissions factor. The highest total air toxics emissions were contributed by four-stroke motorcycles and passenger cars in Tainan urban area, followed by two-stroke motorcycles, light-duty gasoline trucks, and taxis. The grid emissions (1 km × 1 km) showed that the highest toxics emissions area is located on Tainan East District; emissions from motorcycles are dominated source. Motorcycles account around 39-44% emission among all on-road gasoline vehicles. Total air toxics emissions showed a reduction by 21% and 46% for E3 and E15, respectively, compared with those of commercial gasoline. Ground concentrations of selected air toxics that simulated from AERMOD show that the high value of maximum hourly concentrations is located on the downwind area of highway or provincial road within the range of 1 km. The highest concentration is 2 times higher than the average concentration of this simulation area. Moreover, the maximum hourly concentrations of air toxics showed a reduction by 20% and 67% for E3 and E15, respectively, compared with those of G95. For annual average concentrations, the high value is located on the East District. The annual average concentrations of air toxics showed a reduction by 19% (E3) and 47% (E15) as compared with those of G95. The most sensitive factor among AERMOD parameters is half-life of species; it will affect the spatial distribution and average concentration of air toxics. The total maximum individual cancer risk (MICR) for target air toxics are 1.66×10-4, 1.20×10-4, and 9.94×10-5 for G95, E3, and E15, respectively, and the high emission and low cancer unit risk of 1,3-butadiene were responsible for this. The rankings for acute effects were the same as those for the carcinogenic effects as G95 (0.017) had the highest rankings, following by E3 (0.016) and E15 (0.012). The low chronic-effect values of acrolein may be responsible for the high acute effects of G95. The average total acute hazard index is 0.018 (G95), 0.019 (E3), and 0.019 (E15). The low acute-effect values of acrolein are responsible for this. In brief, ethanol-gasoline blends applied in on-road gasoline vehicles in Tainan urban area showed that the ground concentration reductions of total organic air toxics compared to those from G95. In addition, the MICR and chronic damage caused by target air pollution are also reduced while using ethanol-gasoline blends as fuel.