- 學位論文
無鉛汽油添加醇類之油滴撞擊熱板現象分析
Analyses on the Collision Behaviors of Gashol Fuel Droplet Impinging on a hot surface
摘要
本研究探討無鉛汽油添加不同醇類(甲醇_methanol、乙醇_ethanol、丁醇_butanol各取3%、5%、10%、15%)之油滴撞擊熱板表面之動態行為，計有13種油品 (其中無鉛汽油採用95無鉛汽油，M3表示3%甲醇與97% 無鉛汽油之混合液，餘類推)，實驗在二種高度 (10cm、15cm)、二種熱板溫度 (100℃、200℃)下進行，並以高速攝影機擷取油滴撞擊熱板影像。 由實驗結果顯示， (1)油滴撞擊在100℃下進行時，動態過程為擴散、回縮、沸騰、穩定等現象；(2)當油滴撞擊在200℃下進行時，油滴動態較劇烈，會產生擴散、沸騰、汽化、飛濺、彈跳直到離開表面等現象；(3) 當油滴撞擊在不同高度時，相同濃度酒精汽油之反應情形亦明顯不同。當熱板於高溫、低韋伯數時，容易產生反彈情形；當熱板於高溫或較高的下降速度，則會產生汽化及飛濺情形。 另比較含不同濃度醇類之汽油性質時，以M3、E3及B3於200℃熱板上爆裂汽化較強烈。其次由實驗發現，於200℃溫度、10cm及15cm二種高度下，B15具有汽化現象，而M15及E15則無此現象。初步研判，此現象與丁醇之低蒸發熱有關，再加上丁醇之高能量密度、高比熱，或許可取代乙醇成為未來較好之汽油添加物或能源替代品。
並列摘要
The dynamic behaviors of alcohol fuel droplets impinging on the hot surface were investigated. The alcohol fuel were made from 85% to 97% of unlead gasoline and various concentration of alcohol , which were 3%，5%，10% and 15% of mathanol, ethanol or butanol. Alcohol Fuel droplets impinging on a hot surface were tested under a smooth surface, two altitudes (10cm and 15cm), two kinds of hot plate temperatures (100℃ and 200℃). The observation was achieved by using high speed digital camera. When the surface temperature was at 100℃, the experimental results showed that the phenomenon of fuel droplets were spread, recoiling, split, shock, boiling then stable. At 200℃, the fuel droplets were more intense and became spread, boiling, evaporating, splashing, and jumping up from the surface. We also found that M3, E3 and B3 had more strong evaporated phenomena than the others when the surfface temperature was at 200℃. At high surface temperature, the viscosity and surface tension of the alcohol fuel decreased and the diffusive diameter of droplets increased. At last, we found that the evaporating phenomena happened on B15 but M15 and E15 when the surface temperature reached 200℃. Comparing the physical properties of M15, E15 and B15, we found that butanol had higher energy density, low heat of vaporation and high specific energy as well. The low heat of evaporation might be the reason why B15 was easy to get evaporating. With the three physical properties, butanol might become better additive instead of ethanol or be the better energy substitute.