氧化銅奈米流體及水應用於閉迴路型脈動式熱管之研究

A Study of Cuo Nanofluid and Water on Closed-loop Pulsating Heat pipe

游博淮(Bo-Huai Yu)

指導教授 ： 黃博全

國立臺北科技大學/機電學院/冷凍空調工程系所/碩士(2006年)

摘要

近代電子產品面臨微小化後散熱不易的嚴重問題，導致需要尋求一種更快速有效的散熱技術。一種名為脈動式熱管(Pulsating Heat Pipe，PHP)的新熱傳裝置，藉助液/汽兩相系統的脈動作動原理，可將熱由熱管的ㄧ端有效傳至另ㄧ端，可滿足上述高散熱量的需求。由於脈動式熱管構造簡單、有超越傳統熱管的優良特性，已被發現可廣泛的應用(特別是在微電子冷卻應用上)。本研究目的以實驗方法對封閉迴路式脈動式熱管的熱傳性能進行有系統的研究探討。研究過程除以實作方式研製封閉迴路式脈動熱管，進行液汽柱獨立共存的兩相流裝填，以可視化流場觀測外，並探討不同設計參數如工作流體(水、甲醇、Cuo奈米流體)、填充比、輸入熱量負荷及傾斜角對脈動式熱管傳熱性能的影響。
研究結果顯示(1)PHP運作時管內流場的型態會隨熱負荷的多寡而改變，及流場之流動模式可分為震盪期、過渡期與穩定期。(2)PHP系統之總熱阻值會隨負荷之增加而遞減。(3)工作流體之填充比會影響PHP之熱傳特性，Cuo奈米流體和水在填充比為30%，甲醇為50%時，PHP之性能最佳。(4)於傾斜角30°≦β≦90°之間，填充濃度1.0 %wt Cuo氧化銅之PHP性能最佳，但傾斜角β=0°(即水平擺置時)，填充甲醇之PHP，在低負荷下(20W以下)亦能順利作動。值得一提的是Cuo奈米流體於高溫運作時，奈米金屬粒會凝結貼附於PHP管壁上，導致濃度降低，性能接近水，影響PHP熱傳性能。

關鍵字

閉迴路型脈動式熱管 ； 兩相流 ； 毛細管 ； 填充比 ； 奈米流體

並列摘要

Modern microelectronics thermal management is facing considerable challenges in the wake of miniaturizing of components leading to higher demands on net heat flux dissipation. A new heat transfer device (called pulsating heat pipe (PHP)), which can transfer effectively the heat from one of its end to the other end by a pulsating action of the liquid-vapor system, can fit to the above need. Due to the simple design, cost effectiveness and excellent thermal performance may find wide applications (especially using in the electronic cooling). In this project, an experimentally investigation is conducted to explore the thermal performance of PHP. Several closed-loop pulsating heat pipes filled with slug-plug-train two-phase flow field are developed by implementation for the purpose of flow pattern visualization. In addition, the effects of various design parameters, e.g., working fluid (Cuo nanofluid, water, and methanol), filling ratio, input heat flux, and inclined angle on the thermal performance of PHP, are also analyzed.
The experimental results show that (1) The input heat flux will change the flow pattern inside the PHP tube, which can be divided into three periods-oscillating, transitional and stable periods; (2) The PHP heat resistance decreases with increasing heat load; (3) The PHP exhibits the best thermal performance when FR=30% for CuO nanofluid or water, and when FR=50% for methanol; (4) The PHP filling with 1.0 %wt CuO nanofluid presents the better thermal performance compared to other fluid when 30°≦β≦90°. While PHP filling with methanol can start to work at lowest heat load (20W) when β=0°. It should be noted that the CuO particles may precipitate from the nanofluid and stick on inner surface of tubes during PHP operation, which reduces the CuO concentration and changes the heat transport performance of PHP.

並列關鍵字

closed-loop pulsating heat pipe ； two phase flow ； capillary ； filling ratio ； nanofluid

參考文獻

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