| 摘要: | 本研究使用不同比例之異辛烷添加劑添加於市售無鉛汽油中，模擬實際機車行車狀況時之引擎排放多環芳香烴化合物（Polycyclic Aromatic Hydrocarbons, PAHs）之研究。其中燃料油品選用C公司及T公司市面上之92、95無鉛汽油（92無鉛汽油分別以原市售油品及添加10、30、50 vol.％之異辛烷；95無鉛汽油分別以原市售油品及添加10、30、50 vol.％之異辛烷）作為本實驗之實驗用油，利用底盤動力計模擬行車時引擎所排放之PAHs，行駛速度分為怠速惰轉（Idling）、30 km/hr及50 km/hr，分別在此三種不同之操作條件下，針對每種燃料油之引擎排放廢氣中21種PAHs進行三次之採樣，以GC/MS分析，並且探討不同油品及不同比例異辛烷添加後，機車引擎廢氣之PAHs排放係數、排放率及毒性當量之比較。
研究結果顯示，在92無鉛汽油中C92-LFG之總PAHs排放濃度為八種92油品中最高者（7750 μg/Nm3），其分別為C92-I10（7640 μg/Nm3）、C92-I30（1700 μg/Nm3）、C92-I50（2900 μg/Nm3）、T92-LFG（6030 μg/Nm3）、T92-I10（5490 μg/Nm3）、T92-I30（5180 μg/Nm3）、T92-I50（5020 μg/Nm3）之1.01、4.56、2.67、1.29、1.41、1.50、1.54倍；而95無鉛汽油中C95-LFG之總PAHs排放濃度為八種92油品中最高者（8060 μg/Nm3），其分別為C95-I10（7270 μg/Nm3）、C95-I30（7100 μg/Nm3）、C95-I50（6570 μg/Nm3）、T95-LFG（7550 μg/Nm3）、T95-I10（6900 μg/Nm3）、T95-I30（5380 μg/Nm3）、T95-I50（5330 μg/Nm3）之1.11、1.14、1.23、1.07、1.17、1.50、1.51倍。
比較92、95汽油之引擎單位耗油量之總PAHs排放係數，92無鉛汽油之高低排序為C92-I10＞C92-LFG＞T92-LFG＞T92-I10＞T92-I30＞T92-I50＞C92-I50＞C92-I30；而95無鉛汽油之高低排序為C95-LFG＞T95-LGH＞C95-I10＞C95-I30＞C95-I50＞T95-I10＞T95-I50＞T95-I30。
在引擎燃燒不同油品時，絕大多數之PAHs均在引擎之燃燒過程中被分解。而添加異辛烷添加劑後，對減少PAHs排放係數之BaPeq亦有相當的效果，對人體降康風險也降低釵h。
Single spark ignition motorcycles are employed as the major and popular transportation vehicles because of their more convenient and high fuel economy. Until July 2006, it exceed more 13 million motorcycles was used in Taiwan. However, the pollutants emitted from motorcycle engines are determined to as adverse health to living beings and have been recognized as the major air pollution source in urban areas. To improve the quality of vehicle gasoline, probably, may reduce the pollutants emission. Polycyclic Aromatic hydrocarbons was identified as hazardous air pollutants (HAPs) and have been evaluated for the emission from the exhaust of mobile sources in past years. In this investigation, the isooctane was used to be a gasoline additive which also to be called “perfect gasoline”. The various fraction of isooctane, 10% ~ 30% in volume, was added in two commercial gasolines include 92- and 95-Leadfree gasoline (92- and 95-LFG) provided by CPC and FPC in Taiwan. A new motorcycle was installed on a dynometer to simulate the real operation condition for Idling, 30 km/hr and 50 km/hr. A gas chromatograph/mass spectrometer (GC/MS) was employed to analyze 21 individual PAHs emitted from the exhaust of engines. The total PAHs and their BaPeq emission characteristics was also estimated and calculated by BaP toxic equivalent factor (TEF).
In this study, emitted by C92-LFG engine had highest total PAHs concentration for 7750 μg/Nm3 between the six gasolines with and two gasolines without adding isooctane additive. The other gasoline-powered engines had 7640 μg/Nm3 (C92-I10), 6030 μg/Nm3 (T92-LFG), 5490 μg/Nm3 (T92-I10), 5180 μg/Nm3 (T92-I30), 5020 μg/Nm3 (T92-I50), 2900 μg/Nm3 (C92-I50) and 1700 μg/Nm3 (C92-I30). The total PAHs emission from C95-LFG had highest concentration (8060 μg/Nm3). The PAH emission concentration of other 95- motorcycle engines had 7550 μg/Nm3 (T95-LFG), 7270 μg/Nm3 (C95-I10), 7100 μg/Nm3 (C95-I30), 6900 μg/Nm3 (T95-I10), 6570 μg/Nm3 (C95-I50), 5380 μg/Nm3 (T95-I30) and 5330 μg/Nm3 (T95-I50).
For the emission factor by fuel consumption, the rank of 92- gasoline powered motorcycle engines is C92-I10>C92-LFG>T92-LFG>T92-I10> T92-I30>T92-I50>C92-I50>C92-I30. However, the rank of mission factor of 95- gasoline powered motorcycle engines is C95-LFG>T95-LFG>C95-I10> C95-I30>C95-I50>T95-I10>T95-I50>T95-I30. For most different engines, the PAH was depleted during the processes of engine combustion.
Moreover, the isooctane additives will reduce the health risk caused by BaPeq, also has adverse effect for the use in the two gasolines. |
