本文以單相與兩相模型模擬Al2O3/water奈米流體於均勻等熱通量三維微流道散熱器強制對流之數值計算。應用控制體積法數值求解強制對流奈米流體之橢圓、耦合、穩態之三維統御偏微分方程式。研究參數包含雷諾數(100≤Re≤400)、鰭片寬高比(0.375≤AR≤0.625)、奈米粒子體積濃度(0%≤φ≤4%)與進氣室的深度(0.8mm≤Lin≤1.2mm)。
首先以參考文獻中純水於微流道散熱器之數據做驗證，其結果相當吻合，平均誤差在4% 以內，更進一步延伸應用至奈米流體作為冷卻劑。文中比較兩種不同的微流道散熱器在等熱通量時的熱阻，模擬結果顯示B type微流道散熱器之熱阻較A type微流道散熱器來的好。在研究範圍內，微流道散熱器的熱阻隨著奈米粒子體積濃度 與雷諾數Re的增加而降低。另一方面，由奈米流體之壓降的結果顯示，寬高比對於壓降的影響較奈米粒子體積濃度的影響來得顯著。而且發現兩相模型在熱場上與單相模型有很大的差異，但流場方面和單相模型所得到曲線幾乎重合。
本研究以多目標函數並結合反應曲面法(RSM)實驗設計方法來設計目標參數，並於基因演算法(GA)耦合計算流體力學(CFD)作為最佳化的工具。三個設計參數包含鰭片長寬比、奈米粒子濃度和進氣室的深度以固定雷諾數來最佳化。以熱阻為目標函數，並與三設計參數產生關係式。此後利用迴歸函數預測A type微流道散熱器與 B type 微流道散熱器之熱阻，其結果與數值結果相當接近，其誤差分別在3.9% 和3.2%內，奈米流體最佳化後的寬高比是提升的代表著更窄的微流道以及更好的熱交換能力。經由形狀最佳化，目標函數相對於參考的幾何形狀下已成功獲得改進。

Numerical simulations by single-phase and two-phase models of Al2O3/Water nanofluid forced convection in a three-dimensional micro-channel heat sink (MCHS) with uniform heat flux are investigated. The parameters studied include fins aspect ratio, the particle volume fractions and the inlet plenum lengths. Two different types of MCHS are considered and their thermal resistances are compared. In the range of parameters in the study, the thermal resistance of MCHS considered is found to be decrease with the increase of the particle concentration and Reynolds number. The multi-parameter constrained optimization procedure integrating the design of experiments (DOE), response surface methodology (RSM), genetic algorithm (GA) and computational fluid dynamics (CFD) is proposed to design the geometric configuration for two different types of MCHS. The thermal resistances predicted by regression function for two different types of MCHS are in good agreement with numerical results of CFD by the difference within 3.9% and 3.2%, respectively. Through the shape optimization, the objective function is successfully improved with respect to the reference geometry.

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