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Heat Transfer Analysis of Vapor Chamber Filled with Nanofluid Al2O3 Applied in LED
|Authors: ||Teng-Chieh Chen|
|Contributors: ||NTOU:Department of Marine Engineering|
Nonofluid;light emitting diode (LED);vapor chamber;hydrophilic-lipophilic balance (HLB);dimensional analysis
|Issue Date: ||2011-06-30T08:34:36Z
|Abstract: ||本文以Al2O3之奈米流體作為均溫板內部工作流體以及運用於LED均溫板散熱之分析，內容探討市售非離子型之乳化劑、分散劑的HLB值對於奈米流體於懸浮穩定性、熱流特性之影響，之後將Al2O3奈米流體與水等兩種工作流體填充至均溫板內，利用因次分析方法討論各項實驗參數之函數關係，並求出均溫板之等效熱傳導係數經驗公式。實驗結果顯示HLB值12之情況下沉澱率與吸光值為最佳，熱傳導係數及黏度則為不添加任何界面活性劑有較優異的性質，但添加分散劑與HLB值12的乳化劑之Al2O3奈米流體隨靜置時間的熱傳導係數及黏度可維持14天之久，並且有良好懸浮。另外，由推導所得之經驗公式可得知，影響均溫板之等效熱傳導係數為工作流體的熱傳導係數、密度、黏度以及熱源之熱通量。本研究最後比較單顆4晶粒LED於均溫板散熱之特性，以銅基板、鋁基板及均溫板做為散熱基板，分別以實驗、理論、模擬比較各基板之熱阻值，當單顆4晶粒LED功率在5 Watt以上時，以均溫板做為散熱基板的熱阻值將優於銅、鋁基板。|
The heat transfer characteristics of a vapor chamber which contains nanofluid for removing heat flux from a light emitting diode (LED) were investigated in this study. The nanofluid is composed of nanoparticle Al2O3, deionized water and surfactant. The effects of the type of surfactants and hydrophilic-lipophilic balance (HLB) on the emulsification stability and thermofluid properties of the nanofluid were studied as well. An approach of dimensional analysis was used to derive an empirical formula of effective heat conduction coefficient. The experimental results revealed that the emulsion of nanofluid prepared with an emulsified agent with HLB = 12 produced the highest emulsification stability and the least fluctuation of heat conduction coefficient and absolute viscosity during the stayed time of 14 days. Moreover, the effective conduction coefficient was primarily dominated by the factors including density, viscosity, and heat conduction coefficient of the working fluid in the vapor chamber and heat flux of the heat source LED. In addition, after comparing the thermal resistance of the vapor chamber, copper plate and aluminum plate which were used to remove heat flux from a LED with 4 dies using experiment, calculation and simulation methods, it was found that the vapor chamber had the lowest thermal resistance, particularly when the heating rate of the LED was above 5 watts.
|Appears in Collections:||[輪機工程學系] 博碩士論文|
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