請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/61907
標題: | 發熱體微振動之熱傳性能分析 Heat Transfer Analysis of Vibrating Heat Source |
作者: | Yao-Han Chang 張曜涵 |
指導教授: | 陳希立(Sih-li Chen) |
關鍵字: | 振動,微振動,熱傳,熱源振動,發熱體振動, Vibration,Micro Vibration,Heat Transfer,Heat Source Vibration, |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | 近年來電子產品幾乎都朝向輕薄短小的路線發展,而在產品中有許多電子元件因為發熱過多會造成損壞,需要散熱模組之輔助以排除廢熱。現今之散熱模組如風扇、鰭片或是熱管等等,在電子產品之中皆佔用了許多空間。因此本研究針對發熱體自身產生之振動以及超音波共振現象作出相關研究與探討,以期發展出不佔用過多體積之散熱方式。
本研究選擇了振盪器(Shaker)作為產生振動之機器,以150,250,...550mV之振動輸入電壓造成不同振幅之振動,並選用10,20,...160Hz作為操作頻率,再來對發熱體輸入三種不同瓦數之能量以造成三種與環境溫度之溫差,並且運用流場可視化分析作為結論驗證,最後再修正經驗公式及探討誤差。 在研究結果方面,得知振動熱傳可分為強制對流以及自然對流兩個部份,當振動幅度高於一定尺度後,才能越過熱邊界層,達到強制對流的效益。而當振動速度增快時,振盪體本身即可加速上方之自然對流速度。當固定振幅時,熱傳係數增益原則上隨著頻率上升而成線性升高,但是在低頻時則幾乎沒有熱傳增益。而當固定頻率時,熱傳增益基本上會隨著振幅而成線性向上增加,但是在低振幅時也幾乎沒有熱傳增益。再藉由流場可視化分析驗證會發現當振動速度達到一定幅度時,即使頻率不高,也能夠大幅增加流場擾動使流場產生紊流,因而增加熱傳效果。 In recent years, electronic products have become thinner and smaller. Many electronic components would be damaged by over-heating so that they need thermal modules to help them eliminate those heat loss. However, modern thermal modules such as fans, fins, or heat pipes take up a lot of space of electronic products. Therefore, this research aims at heat source’s heat transfer by vibrating itself and the ultrasonic resonance related studies, and trying to find a new thermal module, which would be space-saving. Shaker was used as the instrument to conduct this experiment. 150, 250,…550mV vibration input power was chosen to cause different amplitude of vibration. Also, 10,20,…160Hz was chosen for the manipulated frequency, then inputting three kinds of different power to heat source for causing three distinct temperature differences with ambient temperature. Visualization analysis was also conducted to verify the experimental results. At last, correlational equation was modified and the errors were analyzed. The results of this research are stated below. Vibration heat transfer was separated to two parts: force convection and natural convection. Only if vibration amplitude surpassed a criterion and broke the thermal boundary layer, the forced convection was worked. While the vibration velocity rose, the upper natural convection speed would enhance. When amplitude amount was fixed, the heat transfer enhancement was raised by frequency in linearized characteristic. But when the frequency was too low, there was no heat transfer enhancement. When frequency amount was fixed, heat transfer enhancement would be basically raised by amplitude in linearized characteristic. But when the amplitude was too low, there was also no heat transfer enhancement either. Visualization showed that when the velocity of vibration surpassed to a quantity, even the frequency amount was low, it would largely enhance the perturbation of flow. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/61907 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-102-1.pdf 目前未授權公開取用 | 4.34 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。