臺灣博碩士論文加值系統

近年來電子產品趨向輕薄化發展，散熱問題面臨更大的挑戰，壓電風扇具有體積小、噪音小、低耗能、頻率響應快速等優點，正好符合電子產品嚴格的散熱需求。壓電材料的逆電壓效應使壓電晶片產生高頻振盪，薄板上下擺動造成周圍流體流動產生對流效應，進而達到散熱效果。本研究將壓電風扇裝置於散熱鰭片間，使低溫流體更有效的導入散熱器內，將熱能於散熱鰭片間混合帶走，利用計算流體力學軟體ANSYS CFD/Fluent模擬，並以暫態流場探討各項參數下對於整體冷卻性能之差異，探討參數包括壓電風扇尖端至散熱器前端之距離(Lg)、鰭片列(n)、鰭片高度(Hf)與鰭片間距(G)等，經求解器計算後，以紐賽爾數(Nu)和熱阻值(Rth)等數值作為性能表現依據。研究結果顯示，當壓電風扇尖端放置於散熱器前端，其散熱效果較佳，隨著鰭片高度上升，有效增加散熱面積，提升散熱性能，而散熱器封閉與否取決於鰭片數與壓電風扇擺放位置。

The converse piezoelectric effects of piezoelectric material make piezoelectric chip bringing high frequency damping, plastic fan flapping fluid around bringing convection, and then achieve heat dissipation. This study discuss that piezoelectric fan enclose heat sink fins let cryogenic fluid into heat sink efficacious and heat is took away by heat sink fins. Using fluid dynamic software, ANSYS CFD/Fluent, calculate transient flow field in different parameters, it includes the distance between piezoelectric fan and heat sink(Lg), fin number(n), fin height(Hf), fin gap(G). The performance of standard depends on Nusselt number(Nu) and thermal resistance(Rth) by solver. As the result, when piezoelectric fan replace on front of heat sink, the heat dissipation is useful. According to fin height raised and heat dissipation area increased enhances cooling performance effective. Whether the heat sink confined depends on fin number and piezoelectric fan position.

摘 要 i
ABSTRACT ii
誌 謝 iii
目 錄 iv
表目錄 vii
圖目錄 viii
第一章 緒論 1
1.1 前言 1
1.2 研究動機 1
1.3 文獻回顧 2
1.3.1 壓電風扇散熱特性研究 2
1.3.2 各式散熱器之特性研究 6
1.4 研究架構 10
1.5 研究目的 11
第二章 壓電材料原理特性 13
2.1 壓電效應 13
2.2 壓電材料種類 15
2.3 壓電材料應用 16
2.4 壓電風扇 16
第三章 理論模式 18
3.1 統御方程式 18
3.2 層流模型 19
3.3 動態網格守恆方程式 20
3.3.1 動態網格更新方法 21
3.4 邊界條件 23
3.4.1 入口邊界條件 23
3.4.2 出口邊界條件 23
3.4.3 壁面邊界 23
3.4.4 其他邊界條件 24
3.5 離散化 24
3.6 薄膜溫度 24
第四章 數值方法與幾何模型 25
4.1 數值方法 25
4.1.1 前處理 25
4.1.2 數值模擬 25
4.1.3 後處理 26
4.1.4 格點獨立驗證 29
4.1.5 數值穩定驗證 31
4.2 幾何模型 33
4.2.1 平板型散熱器 35
4.2.1 壓電風扇設定參數 39
第五章 數值模擬結果與討論 43
5.1 壓電風扇流場特性 44
5.2 壓電風扇尖端至散熱器前端之距離(Lg) 52
5.3 散熱器鰭片數(n) 57
5.4 散熱器鰭片高度(Hf) 63
5.5 封閉型散熱器 68
第六章 結論與未來展望 78
6.1 結論 78
6.2 未來展望與建議 79
參考文獻 80
符號彙編 84
附錄 86

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