目前各種能源系統的設計與應用，常會牽涉到多孔性介質或多孔性介質的假設，如地熱、密集式熱交換器、用過核燃料儲存、熱管設計等等。為了要達到高效率的能源使用需求，如何正確評估及計算多孔性介質的熱移除行為，是相當重要的研究課題。本研究以計算流力程式CFD（本研究採用的是CFX4.4）為基礎的分析工具，研究並建立一套可應用於用過核燃料儲存設施等類似能源系統的多孔性介質分析模式。
本研究的進行為先收集多孔性介質的流力、熱傳的基本定律，以及統御方程式，並針對CFX4.4內的多孔性介質分析模式加以瞭解並測試。

至於用過核燃料儲存，本研究將以中期儲存為主，針對直立式與水平式兩大類用過核燃料中期儲存設施，進行熱移除設計的分析。由於儲存設施內的密集核燃料棒與其空隙間的氦氣流體會顯現出多孔性介質的熱傳流力特性，因此我們利用CFX4.4所建立的多孔性介質分析模式來分析該設施，能得到比過去採用「燃料與流體均質化」假設的相關研究更為精確的熱移除設計。

由分析結果可以發現：對於用過核燃料中期儲存設施的熱設計分析方面，以該分析模式所得之系統溫度，整體來說比起均質化假設的分析結果來得低；孔度較大的燃料組件，散熱能力較好；多孔性介質分析模式的暫態解會很快地接近穩態。

Porous media exists in many kind of energy systems design and applications, such as geothermal usage, compact heat exchangers, spent nuclear fuel storage, heat pipe design. For higher thermal efficiencies requirement, it is important to determine system temperature as accurate as possible. The present investigation looks into the procedure to evaluate porous media heat removal behavior in energy system such as spent nuclear fuel storage using CFD methods.
First, investigation begins with understanding of the basic definitions and fundamental laws and governing equations in porous media approach. Next, we need to explore and test the porous media modeling in CFD code.

We will focus on the situations of spent nuclear fuel interim storage. There are two different designs for fuel rod orientation in interim storage, vertical and horizontal. In either design, the fine matrix of fuel rods and nature convecting cooling helium gas form a particular region that presents important porous media characteristics. With such special geometrical and physical arrangement and CFD porous model, it is expected that more accurate system temperature distributions will be obtained compared to traditionally “homogenization of fuel and gas” approach.

From our simulated results, we noticed that the temperature of porous model is lower than homogenization model in the spent nuclear fuel interim storage. The larger porosity of the fuel assembly, the better heat transfer capability. The steady state solutions are reached in relatively short transient times in porous model.

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