近年來隨著電子元件的高速發展，其總功率不斷增大，但尺寸卻越來越小，熱流密度因而持續增加，因此如何解決散熱來保持產品壽命成為一個重要的問題。但當電子元件尺寸小到微米或亞微米時，一些在常規大尺度流動中可以被忽略的因素如滑移邊界都可能在流力與熱傳中佔據主導地位，從而導致較為特殊的微尺度熱流現象，如滑移速度(Slip Velocity)、溫度跳躍(Temperature Jump)等。這些現象的出現通常會對熱傳有較大的影響，因而揭示其影響機制並改善熱傳增益變得非常必要，尤其當流體為脈動流時，更值得探討。本文使用晶格波茲曼法(Lattice Boltzmann Method，簡稱LBM)探討滑移與脈動效應對以空氣為工作流體之肋條微通道(高0.68-34μm) 熱傳增益之影響，由於變化參數較多，本文內文分為穩態流和脈動流兩部分。
穩態流部分，在固定肋條高度（〖H_r〗^*=0.25）等條件下，改變截距比(PR)、努森數(Kn)和雷諾數(Re)來觀察其熱傳增益( )與壓力損失( )的變化。模擬結果顯示， 會隨著PR增加而增加， 則隨著PR增加而減少； 和 均會隨著Kn增加而減少； 會隨著Re增加而減少， 隨著Re增加而增加。其中在PR=3，Kn=0.001，Re=0.1時擁有最佳的熱性能係數(Thermal Performance Factor, 簡稱TPF)，其為文獻中全展平滑管道與具肋條管道最佳值的2倍。此外為方便工程應用，本研究還提出 和 對PR、Kn、Re經驗關係式。
脈動流部分，為了進一步提升熱傳效果而將管道的穩態流入口改為三角形脈動入口並改變斯特勞哈爾數（St），在低Re下(1≤Re≤10)，因軸向熱傳導效應大於熱對流效應，其 和 隨St都沒有太大的變化。而在固定Kn=0.005，〖H_r〗^*=0.5，增加Re至80時， 和 均先隨著St增加而增加，且在St=1.0時為峰值((Nu) ̅⁄〖Nu〗_0 =1.67，f ̅⁄f_0 =19.69)，之後再下降, 在St=1.0時較穩態流(St=0.0)增加了30%。綜合前人文獻平滑管道與具肋條管道之滑移穩態流 - 數據，本研究以LBM模擬具肋條管道之脈動流未見先前文獻報導，其熱傳增益在f ̅⁄f_0 =3-20區間內最大值可達1.67。先前文獻及本文皆發現穩態流時，溫度滑移與速度滑移對熱傳壓損影響一致，然而本文於脈動流首度發現有相同趨勢。

With the rapid development of electronic devices in recent years, there is an increasing trend in their power consumption and decreasing trend in their sizes, which results in increasingly large heat flux generation. To maintain an acceptable product life, it becomes imperative to dissipate the heat efficiently. As the dimension of electronic devices approaches micrometer or sub-micrometer, some phenomena that can generally be neglected in the macroscale continuum flow, such as the slip boundary condition, may play a pivotal role in the microscale thermal flow. The typical impacts include considerable slip velocities and temperature jumps on the boundary wall which may significantly affect the heat transfer. This necessitates a thorough understanding of the heat transfer mechanism and heat transfer enhancement, especially in pulsatile flows. In this study, the lattice Boltzmann method (LBM) is used to investigate the effects of flow slip and pulsation on heat transfer enhancement in a ribbed microchannel (channel height from 0.68-34 μm) with air as the working fluid. Considering the various parameters examined, the main content of this work is divided into two parts: steady-state flow and pulsating flow.
For the steady-state flows in the microchannel with a fixed rib height (〖H_r〗^*=0.25), the heat transfer enhancement ( ) is observed to increase with increasing pitch ratio (PR) and Reynold number (Re) and decrease with increasing Knudsen number (Kn). In contrast, the pressure loss ( ) is found to decrease with increasing PR and Kn and increase with increasing Re. The highest thermal performance factor (TPF) occurs at PR=3, Kn=0.001 and Re=0.1, which is two times that of the best value for smooth and ribbed channels. In addition, for the convenience of engineering application, the empirical correlations of and versus PR, Kn and Re are proposed.
For the pulsating flows, the original steady flow inlet is changed to a pulsating velocity inlet with triangular waveform and the corresponding Strouhal number (St) is varied. At relatively low Re (1≤Re≤10), and are found insensitive to St since the axial heat transfer effect is much greater than that of the heat convection. However, as Re is increased to 80, and at Kn=0.005 and 〖H_r〗^*=0.5 both rise and fall with ascending St, with peak values 1.67 and 19.69 appearing at St=1.0. The peak is 30% higher than that of the steady-state flow (St = 0). Finally, compared with previous - data for steady slip flows in smooth and ribbed channels, the pulsating slip flows in present ribbed channels by LBM simulation have not been reported in the open literature, and improve to the highest value 1.67 for f ̅⁄f_0 =3-20. Furthermore, it is found for the first time that the effects of velocity slip and temperature jump on heat transfer and pressure loss in pulsating flows are similar to those reported in steady flows.
Keywords: Microchannel, Slip Flow, Pulsatile Flow, Microstructure, Conjugate Heat Transfer, Lattice Boltzmann Method

摘要 I
目錄 Ⅱ
表目錄 Ⅳ
圖目錄 Ⅵ
符號表 Ⅶ
第一章、前言 1
1.1研究動機 1
1.2研究背景 2
1.3文獻回顧 3
1.3.1壁面微結構增益熱傳回顧 3
1.3.2脈動流熱傳回顧 5
1.3.3滑移區熱傳回顧 6
1.3.4 LBM模擬方法回顧 9
1.4研究目的 11
1.4.1 LBM驗證 11
1.4.2穩態流 11
1.4.3脈動流 11
第二章、數值方法 20
2.1波茲曼方程式 20
2.2晶格波茲曼方法 21
2.2.1單鬆弛速度場模型 21
2.2.2熱流體動力學模型 22
2.3 邊界條件 24
2.3.1週期性邊界處理格式 24
2.3.2入口速度邊界處理格式 24
2.3.3外差邊界處理格式 25
2.3.4壓力邊界處理格式 26
2.3.5滑移邊界處理格式 26
2.3.6等溫邊界處理格式 28
2.4收斂標準 29
2.5 LBM計算步驟與程序結構圖 30
2.6模型驗證 31
2.6.1無滑移光滑微流道 31
2.6.2無滑移雙側微結構之流道 32
2.6.3滑移光滑微流道 32
2.6.4無滑移脈動微流道 33
第三章、滑移微結構管道穩態流 45
3.1模擬問題 45
3.1.1計算座標系統 45
3.1.2邊界條件 45
3.1.3計算參數 46
3.2網格獨立測試 47
3.3穩態流數據分析與比較 48
3.3.1滑移下PR對熱傳壓損的影響 48
3.3.2滑移下Kn對熱傳壓損的影響 50
3.3.3滑移下Re對熱傳壓損的影響 51
3.4熱傳關係式 52
3.5壓損關係式 53
3.6總體熱性能與前人數據比較 53
第四章、滑移微結構管道脈動流 64
4.1問題描述 64
4.1.1計算區域與座標系統 64
4.1.2邊界條件 64
4.1.3計算參數 65
4.2脈動流於低Re下的結果 66
4.3 Re於脈動下的影響與分析 68
4.4脈動下的速度場與溫度場 68
4.4.1速度場 68
4.4.2溫度場 69
4.5脈動下H_r^*和St對熱傳壓損的影響 69
4.6熱傳關係式 71
4.7壓損關係式 72
4.8總體熱性能與前人數據比較 72
第五章、結論與未來建議 86
5.1結論 86
5.1.1 LBM驗證 86
5.1.2 穩態流 86
5.1.3脈動流 87
5.2本研究重要成果 89
5.3未來工作 89
附錄A論文口試之補充答辯 91
參考文獻 95

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