生質柴油之雙組份液滴於微重力場之燃燒研究

Binary Fuel of Diesels-Alkane Droplet Combustion under Microgravity Condition

李哲緯(Je-Wei Li)

指導教授 ： 潘國隆

國立臺灣大學/工學院/機械工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01708

摘要

本實驗主要以自由落體方式製造無重力場，利用電熱絲加熱點火方式，讓燃油液滴於無重力狀態下燃燒，研究其燃燒情形、火焰顏色、碳微粒(soot)之形成、燃燒速率以及火焰縮口之現象。主要燃油以生質柴油為主，分別與十二烷、十六烷與柴油預混後燃燒，就不同濃度比例、不同初始直徑與重力場燃燒之燃燒現象作探討。
實驗結果顯示，在無重力場下，生質柴油之碳殼(soot shell)強度很弱，燃燒時，碳微粒子(soot particles)不斷飄出。生質柴油與十二烷混合燃燒後，有提高燃燒速率與火焰縮口之現象；相較之下，加入十六烷時，燃燒速率並無太大的改變。另外，初始直徑較小之液滴燃燒速率較快；柴油加入生質柴油後，可有效減少碳的排放量；碳微粒生成越多之燃油，於無重力場下，燃燒速率下降越多，顯示碳微粒對於無重力場燃燒影響甚鉅。

關鍵字

無重力 ； 自由落體 ； 生質柴油 ； 燃燒 ； 碳微粒

並列摘要

The objective of this study is to investigate the burning characteristics of fuel droplets under a microgravity condition. The microgravity condition is made by a free-falling chamber and the fuel droplets are ignited by hot wires. The phenomena of flame shape, the formation of soot, burning rate and flame shrinkage are also observed in this experiment. We use bio-diesel as our main fuel and pre-mix it with n-dodecane, n-hexadecane and diesel, respectively. The result of burning phenomena is discussed in several aspects, such as different volume fraction of mixture, different original diameter of fuel droplet, and compares it with gravity condition.
It is found that the strength of the soot shell of biodiesel is weak, and the soot particles disperse incessantly during the burning process. Bio-diesel mixed with n-dodecane improves the burning rate and causes the flame shrunk, while the rate only changes a little to the mixture of biodiesel and n-hexadecane. Moreover, fuel droplet is easier to ignite when the original diameter of it is smaller than another. It is also found that adding some bio-diesel in diesel can effectively reduce the production of soot. Therefore, the formation of soot plays an important role in microgravity combustion.

並列關鍵字

microgravity ； free-falling body ； biodiesel ； combustion ； soot

參考文獻

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