臺灣博碩士論文加值系統

隨著科技的發展，電子設備的尺寸不斷縮小，導致單位面積的熱通量不斷上升。為了保持一定的使用壽命和良好的性能，電子設備的工作溫度必須保持在一定範圍以下。然而，傳統的散熱方法可能不適合用在日新月異的電子產品。因此，開發創新的冷卻技術已成為目前的趨勢。
近年來，使用壓電風扇進行冷卻的可行性已經被廣泛地研究。其優點包括低功耗、壽命長、低噪音。然而，單片壓電風扇所提供的散熱能力並不足以達到現今電子產品的散熱需求。因此，本研究基於先前的基礎開發了徑向流式多重壓電磁力連動風扇系統。該系統僅使用一片壓電材料和永久磁鐵來驅動多達二十片葉片，不僅大大降低了功耗，也提供了更大的散熱面積。實驗中設計了三種不同的葉片寬度以及三種不同的葉片數量，以找出最佳的配置。
九組不同尺寸設計的系統將會透過比較熱阻、熱阻改善率、無因次熱對流係數增強比、雷諾數、理查遜數等參數，以找出散熱能力最強的設計。此外，本研究定義了性能係數（Coefficient of Performance）來評估散熱能力與功耗之間的比率。散熱能力最佳之設計將與市售之旋轉風扇比較COP值，也會使用粒子圖像測速系統(PIV)，進一步瞭解周圍流場表現。
實驗結果表明，設計E因同時具有較大的共振頻率和振幅而有著最佳的散熱能力。其熱阻與熱阻改善率在35 W之熱通量下分別為0.86 K / W和36.9 ％，並且可將自然對流下之熱對流係數提升兩倍，而COP約為傳統旋轉風扇的3.5倍。比起傳統旋轉風扇，徑向流式出風多重壓電磁力連動風扇系統更能節能地散熱。

With manufacturing process advancements, the size of electronic devices keeps shrinking, which results in a higher heat flux. To maintain a desirable lifetime and good performance for electronic devices, it is necessary to maintain the operating temperature below a certain threshold. Traditional cooling techniques might be unsuitable for next generation electronic devices. Therefore, innovative cooling techniques must be developed.
Piezoelectric fans and their feasibility of cooling electronic devices have been widely studied. However, there are few studies that address using a single piezoelectric actuator to generate radial air flow. In this study, a radial-flow multiple fan system was developed.
This system only used one piezoelectric actuator and a magnetic repulsive force to activate up to 20 fans, which featured low power consumption and a large cooling area. To find the optimal design for the RMFS, the influence of some geometric parameters was investigated. Besides, the performance of different designs was compared with commercially available axial fan.
The results showed that the design E had the best thermal performance among the designs because of its relatively large frequency and amplitude. The thermal resistance and the percentage improvement under a 35 W heat flux were 0.86 K/W and 36.9 %, respectively. In addition, a coefficient of performance (COP) was defined. The COP of design E was approximately 3.5 times that of the rotary fan. For the power consumption aspect, the RMFS is more efficient than the rotary fan.

口試委員會審定書 I
致謝 II
摘要 III
Abstract IV
目錄 V
圖目錄 VIII
表目錄 XI
符號說明 XII
第一章 緒論 1
1.1研究背景 1
1.1.1被動式散熱技術 1
1.1.2主動式散熱技術 2
1.1.3未來散熱技術 4
1.2文獻回顧 5
1.2.1壓電風扇 5
1.2.2多片壓電風扇 7
1.2.3多重磁力連動風扇 8
1.3研究動機 9
1.4研究目標 10
第二章 實驗架構 11
2.1徑向流式多重壓電磁力連動風扇系統 11
2.2詳細規格 11
2.3實驗儀器 13
2.4實驗設置 15
2.5實驗步驟 15
第三章 理論分析 17
3.1共振頻率 17
3.2擺動振幅 18
3.3散熱能力 18
3.4無因次參數 19
第四章 結果與討論 21
4.1徑向流式多重壓電磁力連動風扇系統規格 21
4.1.1共振頻率與平均振幅 21
4.1.2消耗功率 22
4.1.3相位角 22
4.2散熱能力 23
4.2.1熱阻與熱阻改善率 23
4.2.2不同設計之雷諾數與熱對流係數增強比 23
4.2.3不同設計之理查遜數 24
4.3最佳設計之性能 25
4.3.1溫降曲線 25
4.3.2與市售旋轉風扇之比較 25
4.3.3PIV流場分析 25
第五章 結論 27
5.1研究結論 27
5.2未來展望 29
參考文獻 31
附圖 35
附表 68

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