不同生質柴油液滴撞擊熱板現象與引擎燃燒特性關連分析

Investigation of the Relationship between the Collision Behaviors of a Biodiesel Drop Impinging on a Hot Surface and Engine Combustion Characteristics

陳明鴻(Ming-Hong Chen)

指導教授 ： 吳澤松

崑山科技大學/工程學院/機械工程研究所/碩士(2010年)

摘要

摘 要

本研究探討油滴撞擊熱板表面之動態行為，實驗在固定油滴高度下改變參數有熱板溫度、四種油品以及平滑表面與積碳粗糙表面，並以高速攝影機擷取油滴撞擊熱板影像實驗，再來以超級柴油摻配生質柴油之方式，透過引擎試驗分析引擎性能與廢氣排放之數據，將與油滴撞擊進行實驗結果比對。
由實驗結果顯示，油滴撞擊在沸點溫度下時，油滴動態過程如:擴散、回縮、分裂、震盪、沸騰、穩定等現象；當油滴撞擊在沸點溫度上時，此時油滴動態較劇烈，則會產生擴散、沸騰、汽化、飛濺、彈跳直到離開表面等現象。在比較不同生質柴油性質時，以棕櫚油與生質廢食用油在高溫熱板上爆裂效果為較佳，生質大豆油之情況較差。同時油品在高溫時會因黏度與表面張力下降，而使得油滴之擴散直徑增加。比較生質柴油在不同粗糙度表面情況，於平滑熱板表面上熱傳遞效率較快且摩擦力也小，使油滴在回縮現象也較為迅速且明顯；於積碳粗糙熱板表面上，因表面粗糙關係，使油附著在熱板上而形成分裂現象。
引擎試驗則探討摻配30%高含量生質柴油進行測試，以在高溫熱板上爆裂效果最差之生質大豆油其黑煙排放最高，而生質棕櫚油之黑煙排放較低，同時NOx排放部份，則也以生質大豆油之NOx排放量最少，以生質廢食用油之NOx排放量較高。

關鍵字

油滴撞擊熱板 ； 積碳表面 ； 高速攝影 ； 引擎試驗 ； 生質柴油

並列摘要

Abstract
The collision behaviors of a biodiesel drop impinging on a hot surface and engine experiment were investigated. Liquid drops impinging on a hot plate were tested under smooth and deposit surfaces, different biodiesel and surface temperature. The influence of the soybean biodiesel, palm biodiesel and cooking oil biodiesel on the impact behavior of a drop was considered. The drop impinging on a hot plate and under the Leidenfrost temperature and the observation was achieved by using high speed digital camera. The engine combustion characteristics, heat release rate, engine performance, exhaust emission were measured by biodiesel engine tested. The relationship between the collision behaviors of a biodiesel drop impinging on a hot surface and engine combustion characteristics were investigated.
The experimental results showed that when the plat temperature was under Leidenfrost temperature, the dynamic behavior of oil droplets was spread, recoiling, split, shock, boiled, stable phenomenon; the plat temperature was above Leidenfrost temperature, the dynamic behavior of oil droplets was more intense and would produce spread, boiling, evaporation, splashing, jumping up from the surface and so on. The explosive phenomena of Palm biodiesel and waste cooking used oil biodiesel droplet were better than soybean biodiesel. When the biodiesels were under high temperature, the viscosity and surface tension would be decreased﹐ the size of diffusive diameter of droplet were increased. The influences of the plate roughness on drop impinging tests showed that shrinkage of droplet were rapid and conspicuousness on smooth plate. The fuel drop on deposited hot plate would be separated occurring from the effect of roughness.
The engine tests were conducted on super diesel blending with 30% biodiesel. Experimental results showed that the smoke exhaust was higher and NOx was lower of soybean biodiesel than other biodiesels. It was evidently that the impact behavior of a drop impinging on hot plate would affect the combustion characteristics of engine test.

並列關鍵字

Drop Impinging on Hot Plate ； Deposit Surfaces ； High Speed digital camera ； Engine Test ； Biodiesel

參考文獻

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