在本論文研究中，建立了一系列的實驗系統及實驗方法，來探討在水平渠道內空間中高性能散熱座在不同冷卻方法下之熱流特性。冷卻方法分為(一)自然對流與(二)水平渠道內之強制對流兩種。在研究中探討影響自然對流及水平渠道內之強制對流之相關參數分別列之如下：(一)自然對流－穩態格拉雪夫數(GrS)與散熱座高度與渠道高度比(H/HC)。這些參數的探討範圍是GrS=6.42x105~1.64x106與H/HC=0.47~1.0。(二)強制對流－穩態格拉雪夫數(GrS)、散熱座高度與渠道高度比(H/HC)與雷諾數(ReD)。這些參數的探討範圍是GrS=1.66x105~1.05x105，H/HC=0.47~1.0與ReD=7356-30767。
在水平渠道內高性能散熱座之流力特性方面，本研究探討的流力特性包括：局部流速分佈、局部紊流強度分佈與壓降變化。從實驗量測結果顯示：雷諾數對側向無因次化流速分佈之影響並不明顯；針對非高性能散熱座的所有實驗情形，局部紊流強度分佈在0.47□ H/HC □1.0與1.98m/s<Ui<8.02m/s的範圍內皆小於7.5%。本研究發展出一個理論模式，可以成功的預測散熱座在渠道內有旁通效應下的流速分佈以及壓力降，其預測與實驗量測結果相當吻合。
在無限制及限制空間中高性能散熱座之自然對流熱傳特性方面，分別針對暫態/穩態之局部和平均熱傳特性作探討。研究結果顯示：暫態/穩態之局部和平均紐賽數隨著GrS增加而增大，但其隨著H/HC的增加而減小；研究中亦針對無限制及限制空間中高性能散熱座之自然對流熱傳特性分別提出兩條新的經驗公式。
在水平渠道內高性能散熱座之強制對流熱傳特性方面，本研究先後針對暫態/穩態之局部和平均熱傳特性作探討。研究結果顯示：在相關影響參數的探討中，發現紐賽數會隨著GrS、H/HC與ReD的增加而增大。對於不同材質鰭片和基座所組成的散熱座也可以發現同樣的趨勢。研究中亦針對高性能散熱座在渠道內強制對流之熱傳特性提出新的經驗公式。
根據變異數分析F檢定法，本研究完成實驗相關參數之敏感度分析。經過與實驗數據的比對，確立熱阻與壓力降的反應曲面法二次方模型之準確度。同時，藉由反應曲面法建立了條件限制的分析模型並找出在中央合成設計中影響熱阻與壓力降的關鍵參數；進而應用連續二次規劃法有效的探討各種限制條件下的最佳化設計。最後，研究中亦針對四種不同限制條件情況下得到數值最佳化之結果，與實驗數據比對皆相當吻合。

ABSTRACT

A series of experimental studies on the fluid flow and heat transfer characteristics from non-compact/compact PPF heat sinks at unconfined and confined condition by using different cooling methods have been performed. Two types of cooling methods such as natural convection and forced convection due to channel flow are employed in the present study. The relevant parameters influencing fluid flow and heat transfer performance in natural convection and forced convection studies are listed, respectively. They are: (1) natural convection－the steady-state Grashof number (GrS) and ratio of heat sink height to channel height (H/HC). The ranges of these parameters studied are GrS=6.42x105~1.64x106 and H/HC=0.47-1.0; (2) forced convection－the steady-state Grashof number (GrS), ratio of heat sink height to channel height (H/HC)and Reynolds number (ReD). The ranges of these parameters studied are GrS =1.66x105~1.05x106 (or qC = 2486.56W/m2 ~ 15676.90W/m2), H/HC=0.47~1.0 and ReD=7356~30767. Their effects on fluid flow and heat transfer characteristics in natural convection and forced convection have been systematically explored.
In the hydrodynamic aspect for confined compact heat sinks in channel flow, the fluid flow characteristics including the spanwise velocity distribution, local turbulence intensity distribution, and pressure drop are investigated. From the results, the spanwise dimensionless velocity distributions are not significantly affected by Reynolds number. Besides, for all the cases of non-compact heat sinks, the turbulence intensities at all measuring locations are less than 7.5% for the cases with 0.47<H/HC< 1 and 1.98m/s<Ui<8.02m/s. A theoretical model to effectively predict the velocity and pressure drop for partially-confined heat sinks has been successfully developed. The results show good agreement between the predicted and the experimental data.
For unconfined/confined compact heat sinks in natural convection, the transient/steady-state local and average heat transfer characteristics are studied. The transient/steady-state local and average Nusselt number increases with increasing GrS, but decreasing with H/HC. In addition, two new correlations of steady-state average Nusselt numbers in terms of relevant influencing parameters for unconfined and confined compact PPF heat sinks in natural convection are proposed, respectively.
For confined compact heat sinks in forced convection, the transient/steady-state local and average heat transfer characteristics are successively explored. The transient/steady-state local and average Nusselt numbers increase with increasing GrS, H/HC ratio or ReD. Similar trend can be found for the cases at different heat sink fin and base materials. In addition, a new correlation of steady-state average Nusselt number in terms of relevant influencing parameters for confined compact PPF heat sinks in forced convection is proposed.
According to the results in ANOVA, a sensitivity analysis for the design factors is performed. The accuracies of the quadratic RSM models for both thermal resistance and pressure drop have been verified by comparing the predicted response values to the actual experimental data. The Response Surface Methodology is applied to establish analytical models of the thermal resistance and pressure drop constraints in terms of the key design factors with a CCD experimental design. By employing the Sequential Quadratic Programming technique, a series of constrained optimal designs can be efficiently performed. The numerical optimization results for four cases under different constraints are obtained, and the comparisons between these predicted optimal designs and those measured by the experimental data are made with a satisfactory agreement.

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