混合燃料對機車引擎排放空氣污染物之影響

Abstract

機動車輛排放之污染物中對人體影響最大的莫過於懸浮微粒，台灣地區機車數量達一千三百八十餘萬輛，機車密度為世界之最，所以有效控制機車污染量能使空氣品質明顯改善。在台灣民營加油站普及，且因高油價時代來臨，所以有不肖商人在油品中添加溶劑賺取差價，因此本實驗使用機車引擎與兩家不同公司生產之95無鉛汽油，添加不同比例二甲苯，探討二甲苯添加比例對機車排放微粒與燃燒廢氣組成之影響。利用電子式低壓衝擊器(ELPI，Electrical Low-Pressure Impactors )與燃燒廢氣檢測儀進行微粒與廢氣檢測。由實驗結果顯示，添加二甲苯的比例越高確實造成廢氣微粒數量上升，但廢氣中微粒的峰值粒徑不隨著添加劑的改變產生變化，峰值出現在0.04∼0.2μm之間，微粒的數量隨著引擎轉速增加而上升，在同轉速下不同的檔位也會影響微粒排放數量，隨著引擎轉速的增加，適當的切換檔位可以減少微粒的產生。燃料中添加二甲苯比例越高，引擎越不容易啟動。引擎廢氣中的一氧化碳、二氧化硫含量極低，主要原因為引擎符合機車第四期排放法規與實驗採熱機測試之故，燃料燃燒完全，不易產生一氧化碳，加上95無鉛汽油含硫量極低，所以不易產生二氧化硫。

The most influence on human body is aerosol from motor vehicle emission. Taiwan motorcycle's quantity is up to more than 13,800,000, the density of motorcycle is the highest in the world. To control the emission from motorcycle can make air quality obviously improve. The private service gas station is popularized in Taiwan. Some unworthy businessman adds solvents to earn the price differential in the oil. This study used 95 unleaded gas of different companies, add different proportion of xylene. Utilize the Electrical Low-Pressure Impactors (ELPI) to measure particles number concentration and waste gas composition with Combustion Analyzers. Add the high proportion of the xylene really causes the quantity of particle of the waste gas to rise high concentration by the experimental result. The particle diameter of peak value is not changed with the change of the additive. The mode of aerosol is between 0.04~0.2μm. The number conceration of the particle rises as the rotational speed of the engine increases. Different gears will influence the quantity of particle with the same rotational speed. With the increase of the rotational speed of the engine , it can reduce the production of the particle in the proper change gears. Gasoline with high proportion xylene is harder to start an engine. Carbon monoxide and sulfur dioxide in the engine waste gas are extremely low. Because of the experiment use hot-engine test fuel can be burned completely and 95 unleaded gasoline almost have no sulfur.