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Title: | 全圓洞道內具單線性熱源之冰水管間接冷卻系統之自然對流熱傳研究 Experimental Study on Natural Convection Heat Transfer of Indirect Water Cooling System with Single Linear Heat Source in a Circular Tunnel |
Authors: | Hong-Huei Yang 楊鴻輝 |
Advisor: | 蘇金佳 |
Keyword: | 自然對流,圓形封閉空間,地下洞道,間接水冷,單線性熱源, natural convection,circular enclosure,underground tunnel,indirect water cooling,single linear heat source, |
Publication Year : | 2010 |
Degree: | 碩士 |
Abstract: | 封閉空間中自然對流之熱傳研究已經發展一段時間,常常被應用在實務工程上面,其中一項重要的應用是地下電纜洞道的冷卻系統,但是在台灣對地下電纜洞道的經驗不足,因此需要更多的文獻提供充足的資訊,使地下電纜洞道的設計與規劃更容易。對於地下電纜洞道而言,當電力在傳輸的過程中,必然會受到電阻的影響而產生熱能,故冷卻系統為不可或缺的部份;本研究使用大型圓形水泥管當作地下電纜洞道,以管狀加熱器模擬電纜線,由五支冰水管建構冷卻系統,本研究的目的在於使冷卻系統最佳化。
本實驗的操作變因包含冰水管五個位置(A,B,C,D,E)、加熱器的角度(30°, 60°,90°,120°)、加熱器的功率(1300,975,650 W)、冰水流量(4,8,12,15 LPM)以及冰水管管數;量測溫度方面使用T-type熱電偶線,架設於洞道下游近出口處之剖面,以取得較穩定的溫度。 在單支冰水管的實驗中,冰水管最靠近加熱器時具有最佳的冷卻效率,但此時局部高溫區比其他情況時都來的高,在工程應用上應針對此處加強冷卻效力;當冰水管位置固定,加熱器功率增大對剖面溫度分布影響不大;當冰水流量從4 LPM增加到15 LPM,平均溫度差形成一拋物曲線,先降後升,且高流量時入口處溫度出現不規則的跳動;另外,當加熱器水平高度越低,剖面整體溫度越均勻。 在多支冰水管的實驗中,大致上冰水管越多冷卻效率越佳,因為冰水吸熱表面積增大較增加冰水流量來的有效率,因此多支冰水管置於洞道上方,加熱器也置於洞道上方但在冰水管的下方,此時為最佳佈設。 Natural convection heat transfer in a circular enclosure has been developed for a long time. One of many applications is cooling system of underground cable tunnels. For Taiwan, We lack for experiences of building underground cable tunnels. We need more literatures to provide a lot of information for structuring underground cable tunnels. In underground cable tunnels, a part of electric energy is dissipated by electrical cable so the cooling-water system is needed. In this research the circular tunnel made of concrete was used to simulate underground cable tunnels. Tube-shaped heater was simulated electrical cables. Five pipes made of stainless structured indirect cooling water system. The purpose of this research is to optimize cooling efficiency. The effect of the position of cooling water pipes(A,B,C,D,E), the angle of the heat source(30°,60°,90°,120°), the power of the heat source(1300, 975, and 650 W), the flow rate of the cooling water(4, 8, 12, and 15LPM), the number of the cooling water pipes were discussed. T-type Thermocouples installed on cross section of downstream section of underground cable tunnel to measure air temperature. In the experiment of single pipe of cooling water, the smallest distance between single pipe of cooling water and heater was the highest efficiency but local relative high temperature was higher than any other case. When the position of single pipe of cooling water is fixed, the power of heater didn’t influence the distribution of temperature of air significantly. The average Temperature profile was like a parabolic line when the flow rate of cooling water increased from 4 LPM to 15 LPM and strong fluctuations of temperature of air occurred on the section of entrance of the tunnel as the flow rate of cooling water more than 12 LPM. The level of heat source was lower then the temperature of air was more uniform. In the experiment of number of pipes of cooling water, the result shows that more pipes of cooling water were activity then the temperature of cross section of the tunnel is lower due to increase the total area of cooling water pipes. The best layout is that Multi-pipes are arranged on the top of the tunnel and heater is the same but below the pipes. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/22591 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 機械工程學系 |
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File | Size | Format | |
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ntu-99-1.pdf Restricted Access | 6.46 MB | Adobe PDF |
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