本研究研究重點聚焦於燃料電池系統中的「重組器」單元。所分析之重組器幾何為一中空圓管結構，觸媒材料主要為 Ni/Al₂O₃，並以塗佈方式附著於圓管內壁。此次研究所採用之產氫方式為蒸汽甲烷重組反應（Steam Methane Reforming, SMR）。
本研究主要可分為三個部分：(1) 圓管中的非反應流場分析；(2) 二步驟 SMR 機制下於圓管中的反應流場分析；(3) 比較二步驟與三步驟 SMR 不同化學反應機制對圓管流場的影響。第一部分將針對單純流體流動與其邊界條件之間的關係進行詳細分析，以了解基本流場行為。第二部分則以第一部分建立的流場為基礎，加入二步驟 SMR 的化學反應模型，並進一步探討不同邊界條件變化對反應流場所造成的影響。第三部分則鑒於相關 SMR 應用文獻中，二步驟與三步驟 SMR 反應機構皆常被用於建構化學模型，故本研究進一步探討這兩種反應機制在圓管流場中所造成的差異與影響。
純流場模擬結果顯示，輸送不平衡會導致速度場出現過衝（overshooting）現象，使壁面附近的流體加速，其速度甚至高於流場中心的主流區域。另外在反應流的模擬結果顯示，增加H2O/CH4 (α)、表面體積比 (β)、流體停滯時間 (γ)、壁面溫度 (Twall) 以及流體入口溫度 (Tin) 皆有助於提升 SMR 中的甲烷轉化效率。其中，以壁溫 (Twall) 所提供的持續熱能影響最為顯著，可使XCH4達到90%至100%，顯示熱能供應對重組器具有高度的影響力。在800-1100 K的溫度範圍內，Model B 中的二步驟與三步驟SMR模型展現出一致的反應行為，並與同樣採用 Ni/Al₂O₃ 類型觸媒的Model A高度相似，證實兩種機制在此範圍內具有相近的趨勢。此外，在Twall = 1100 K條件下進行SMR時，壁面附近會出現CO₂濃度峰值，其成因為擴散速率超過生成速率，導致CO₂自壁面向軸心方向擴散，進而在壁面產生CO₂莫耳濃度的轉折現象。

This study focuses on the reformer unit within the solid oxide fuel cell (SOFC) system. The analyzed reformer features a hollow circular tube, with the catalyst material, primarily Ni/Al₂O₃, coated along the inner wall of the tube. The hydrogen production method adopted in this work is steam methane reforming (SMR). The research is divided into three main parts : (1) Analysis of non-reactive flow within a circular tube.(2) Reactive flow simulation in the tube based on a two-step SMR mechanism. (3) Investigation of the influence of different chemical mechanisms, namely the two-step and three-step SMR, on the flow field inside the tube.
The first part focuses on the relationship between pure fluid flow and boundary conditions to establish an understanding of fundamental flow behavior. In the second part, the two-step SMR reaction model is introduced based on the flow field developed in the first part, and the effects of varying boundary conditions on the reactive flow field are analyzed. The third part is motivated by the fact that both two-step and three-step SMR mechanisms are widely used in related literature. Therefore, this study further investigates the differences and influences these two mechanisms have on the reformer flow behavior.
The pure flow field simulation results indicate that transport imbalance can lead to an overshooting phenomenon in the velocity field, accelerating the fluid near the wall to a speed even higher than that in the central core region of the flow field. Furthermore, the reactive flow simulations reveal that increasing the H₂O/CH₄ ratio (α), surface-to-volume ratio (β), residence time (γ), wall temperature (Twall), and inlet temperature (Tin) all contribute to enhanced methane conversion efficiency in SMR. Among these, the continuous thermal input provided by Twall exhibits the most significant effect, enabling XCH4 to reach 90% to 100%, thus highlighting the reformer's high sensitivity to heat supply. Within the temperature range of 800-1100 K, the two-step and three-step SMR models in Model B exhibit consistent reaction behavior and closely resemble Model A, which also employs the same type of Ni/Al₂O₃ catalyst, confirming that both mechanisms follow similar trends under these conditions. Furthermore, under Twall = 1100 K, a concentration peak of CO₂ appears near the wall due to the diffusion rate exceeding the formation rate, causing CO₂ to diffuse inward and resulting in a turning point in the wall-side molar concentration profile.

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