本研究以數值方法模擬在不考慮熱輻射的自然對流情況下精簡型電腦的機殼開孔狀況對於內部垂直擺放鰭片熱沉自然對流散熱能力之影響，包括上殼開孔率、下殼開孔率、側殼開孔率、側殼不開孔區位置、及機殼材料的熱傳導係數等參數的效應。上殼開孔率影響熱沉出口高溫空氣滯留於機殼內部迴流區的範圍；下殼開孔率與進氣流阻有關。當採用高導熱的鋁機殼時，上方熱空氣迴流區的部分熱能回傳至機殼底部，並預熱下方進入的冷空氣，而降低了熱沉的效能；但採用低導熱的塑膠機殼時則無此現象。採用塑膠機殼時，降低側殼開孔率會增加熱沉底部與側面進入空氣之比率，進而增加熱沉鰭片通道內部的散熱，此增強的煙囪效應使熱沉自然對流散熱隨側殼開孔率下降而增加。如側殼有部分不開孔區域，則當此不開孔區域遮蔽熱沉位置時，因煙囪效應的作用，可具有較高的散熱量。

This study numerically investigates the effects of chassis perforations on natural convection from a vertical rectangular-fin heat sink. The considering parameters include free area ratios of the top, the bottom and the front of the chassis, the positions of a non-perforated region and the heat conductivities of chassis materials. The effect of the free area ratio of the top chassis is found to affect the size of the hot recirculation region within the upper part of the chassis, while the effect of the free area ratio of the bottom chassis affects the flow resistance for the entering air. With a high-conductivity chassis material, the entering air is preheated by the heat conducting from the hot recirculation region, leading to reduced heat sink performance. With a low-conductivity chassis material, improvement in heat sink performance manifests with decreasing free area ratio due to the chimney effect, especially when the heat sink is shrouded by a non-perforated region of the chassis.

摘要 i
誌謝 iii
目錄 iv
圖表目錄 vi
符號表 ix
第一章 緒論 1
1.1 研究背景 1
1.2 文獻回顧 2
1.3 研究動機與目的 4
第二章 模型建構與參數分析 15
2.1 物理模型 15
2.2 數學模型 16
2.2.1 The Boussinesq Model 16
2.2.2 統御方程式 16
2.2.3 邊界條件 17
2.3 數值方法 18
2.3.1 速度與壓力求解方式 18
2.3.2 其餘離散化方程式 19
2.3.3 相關參數 19
2.4 模擬參數 19
2.4.1 通用參數 20
2.4.2 變因參數 20
2.5 流固耦合計算之網格建立 20
2.5.1 流固耦合邊界層格點測試與進出口範圍 20
第三章 機體側殼開孔率與機殼材料對熱沉自然對流散熱之影響 27
3.1 塑膠機殼之上殼與下殼開孔率對鰭片熱沉自然對流散熱之影響 27
3.2 絕熱機殼之側殼開孔率對熱沉自然對流散熱之影響 28
3.3 不同機殼材料下流場變化對熱沉局部自然對流散熱影響 28
3.4 塑膠機殼於開孔側殼不同位置不開孔對熱沉自然對流散熱影響 30
第四章 結論與未來方向 42
4.1 結論 42
4.2 未來方向 43
參考文獻 44

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[13] B.Y. Guo, Q.F. Hou, A.B. Yu, L.F. Li, J. Guo, Nuh, Ru-Pd, Rh-Pd nanoparticles could be uniformly deposited in the channel of MCM-41, and the catalysts could be further applied in the hydrogenation of p-xylene. Moreover, the CFD prepared Ru/MCM-41 gave the highest reaction conversion since it had the smallest particle size, which was nearly 8 times of the activity of the conventional Ru/MCM-41 catalyst.
In Chapter 3, the hydrogenation of BPA by using water as solvent and the self-synthesized Ru/MCM-41 as catalyst was investigated. Comparing to the traditional organic solvents, the combination of water and Ru/MCM-41 showed several advantages such as hydrophilic effect, hydrogen bonding and on-water mechanism, which could benefit to the reaction. Although BPA is sparingly soluble in water, the results showed that the solubility is not the limitation. Besides, the catalytic activity and the durability of the Ru/MCM-41 catalyst were tested to be superior to a commercial carbon supported catalyst due to better dispersion and recyclability of silica in water. The results also suggested that this system could be further applied on various reactants such as bisphenol F and benzoic acid.
In Chapter 4, the possibility of hydrogenation in CXLs was evaluated. This chapter lists successful examples in the literature and gives a conjecture for CXLs by the inductive reasoning technique. Three points of view in CXLs including reactant, solvent and catalyst were fully discussed. The results suggested: (1) less activation energy such as the hydrogenation of NO2 to NH2; (2) higher hydrogen solubility such as CO2-expanded methanol and CO2-expanded cyclohexane; (3) less CO poison such as Ru, Rh and Pd metal catalyst would be benefited to CXLs system.
In Chapter 5, the hydrogenation of benzyl alcohol by using compressed CO2/water as solvent was reported. When CO2 dissolved in water, carbonic acid could disassociate and form protons and carbonates. These protons helped catalyzed both hydrogenation and hydrogenolysis reactions. In this chapter, several benzyl reactants with different functional group and protonation ability were also discussed. The results showed that compressed CO2/water is very suitable for aromatic hydrogenation and C-O hydrogenolysis. It is believed that applying this green solvent system into refinery process for bio and petroleum chemicals could be very promising.
In Chapter 6, the preparation of Pd-MS by direct synthesis was demonstrated. In this chapter, palladium nitrate dihydrate, cetyltrimethylammonium bromide, tetraethyl orthosilicate, 1,3,5-trimethylbenzene (TMB) were used as metal precursor, template, silica source and pore expanding agent, respectively. The pH value was a significant factor in the direct synthesis, influencing the size and loading of the Pd nanoparticles, the morphology of the Pd-MS and the catalytic activity toward p-chloronitrobenzene (p-CNB) hydrogenation. When TMB was added during the direct synthesis, the TMB-modified Pd-MS exhibited not only the highest catalytic reactivity, due to the increased rate of diffusion in the enlarged pores, but also high thermal stability after post-heating of catalyst at 700oC, due to enhanced anchoring between the silica and the Pd nanoparticles.
In Chapter 7, preparation of PAA and PI nanoparticles by a compressed fluid antisolvent precipitation was reported. Compressed CO2 was first used to precipitate the dissolved PAA in N-methyl-2-pyrrolidone (NMP), and followed by the thermal imidization process of PAA to obtain PI particles. Several operation variables including the temperature and pressure of antisolvent process, the CO2 liquid level, the temperature and pressure of drying process, the temperature of imidization process and the concentration of PAA were fully discussed, which could provide a facile and green process to manufacture PAA and PI nanoparticles.
In Chapter 8, a summary of previous chapters was provided. With the encouraging results in this study, it is believed that applying green solvents compressed CO2 and water into catalytic reactions and nanomaterial preparations could be very promising. It could also meet the purposes of process intensification, sustainable development and environmental protection.