熱管具有高傳熱量、熱響應迅速、構造簡單以及不需額外提供動力等特性，是目前在各種電子及衛星系統熱管理中極為重要之一散熱元件。因此，本文以修改KIVA-3程式所建立之三維熱管計算程式，採用Darcy-Brinkman-Forchheimer多孔性介質模式，模擬分析多孔性介質對熱管熱傳效能之影響。由模擬結果可知，有多孔性介質時會使氣體速度加快，降低熱管之壁面溫度、壓力及溫度，而且壁面溫度趨於穩定之時間也明顯地減少。熱傳導係數較高之材質其熱管內部之氣體及液體溫度、壓力、熱阻均會降低，但氣體速度卻會升上。較高之輸入熱量會導致較高之熱管管壁溫度、氣體之溫度、壓力及密度。當粒徑越小時，會降低其滲透率和增加液體從冷凝端到蒸發端之壓力差，但其結果不會影響溫度的變化。在不同粒徑相同排列之毛細結構下，粒徑之大小不會改變其有效熱傳導係數，但會改變其滲透率之大小，因此會影響其液體壓力和液體速度分布情形，但對於液、氣溫度和氣體壓力、氣體速度並不會造成其影響。在相同粒徑不同排列之毛細結構下，排列之方式不僅會改變其有效熱傳導係數，也會改變其滲透率之大小，而影響其壓力、速度和溫度，但是有效熱傳導係數還是影響熱管熱傳效能之主因。本文同時分析比較Darcy與Darcy-Brinkman-Forchheimer兩種不同多孔性介質模式對分析結果之影響，雖然Darcy-Brinkman-Forchheimer程式考慮慣性項之二階非線性項，但結果發現對於個別之速度、壓力、溫度，並無明顯之影響。

　The heat pipe is a simple and power-free device characterized by a high heat transfer capacity and a short thermal response time. It has been one of the most important heat-dissipation elements for the thermal management of various electronic and satellite systems. This thesis aims to present a study in which the porous-medium parameters on the heat transfer efficiency of the heart pipe are investigated. By adapting the KIVA-3 software and adopting the Darcy-Brinkman-Forchheimer model, a numerical simulation model for the three-dimensional, transient, and multi-phase flow is developed in order to conduct the investigation. Numerical results thus obtained show that the porous-medium increases the vapor flow velocity and meanwhile reduces the pressure and temperature of the heat pipe. It also patently shortens the time for the heat pipe to reach a steady state. A higher effective thermal conductivity of the material may reduce the temperature, pressure and the thermal resistance of the heat pipe. However, it will raise the velocity of the vapor flow. More heat input results in a higher temperature, pressure and density in the vapor flow. The resulted liquid temperature is also higher. A smaller diameter of the porous medium will reduce the permeability and increase the pressure difference of liquid from condenser section to evaporator section, but will not affect the temperature. When a capillary structure is organized by porous-medium of different diameters but with single arrangement, the effective thermal conductivity will not undergo change due to the size of porous-medium, but the permeability will be affected. Accordingly, the particle size of porous-medium will influence the distribution of both the liquid pressure and the velocity of the liquid flow, but it will not influence the temperature, the vapor pressure, and the vapor velocity. On the contrary, when the capillary structure with porous-medium of identical diameter but with different arrangements, both the effective thermal conductivity and the permeability will undergo change. Consequently, the pressure, the velocity and the temperature will be affected. However, the heat transfer efficiency of the heat pipe is still influenced primarily by the porosity. Furthermore, this thesis compares the numerical results predicted by two different porous-medium models of Darcy and Darcy-Brinkman-Forchheime to be insignificant. Although D-B-F model takes a non-linear type of second steps of inertia into account, the influences on the speed, pressure, and temperature are found respectively.

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