在氣候變遷與碳排放壓力日益加劇的背景下，碳捕捉與利用(Carbon Capture and Utilization, CCU)技術的應用與開發已成為永續發展的重要方向。藻類養殖因具備高碳固定效率與再生資源潛力，被視為CCU系統中極具價值的核心模組之一。本研究與華侖生技公司合作，針對其開發之CCU藻池內部導流裝置(flow inducer)，進行三維流場模擬與幾何配置優化，目標在於提升藻類養殖效率與碳固定效能。
　　本研究建立一座半徑1.8m、高度1.0m之三維藻池模型，採用凍結轉子法(Frozen Rotor Method)進行模擬，並搭配實測流速進行驗證以確保準確性。研究內容分為兩大主軸：其一為探討橢圓槳葉幾何(半軸 a、b與節距p)對流場效率與能耗表現之影響；其二為評估導流裝置於不同擺放配置下的效能，以對應實際操作需求。模擬結果顯示，華侖公司提供原始槳葉設計已接近最佳幾何組合，其中節距p為影響導流效率與功耗的主要敏感參數。配置分析方面，分為高度與水平方向兩個層面。在高度配置分析中，導流器固定於藻池中心，藉由調整其安裝高度觀察流場變化。根據操作目標不同，若需強化底部混合與抑制沉積，建議配置於高度約0.125m；若為促進表層循環與改善光照均勻性，則建議配置於約0.875 m；若以提升全池混合均勻性與動能擴散為目標，則高度0.5至0.625 m為最佳區間。水平配置方面，固定導流器於藻池底部並沿徑向方向調整位置，並依導流器徑向與移動方向相對關係區分為垂直與平行兩種調整方向。模擬結果顯示，導流器位於中心區域時具備最佳近場導流效果、較低的遞減效應與更均勻流場；其中平行調整對位置偏移的敏感度較低，於中心 ± 0.5m範圍內導流表現差異不大，具操作彈性。綜合高度與水平擺放分析結果，導流器安裝位置可依操作需求進行整合應用與調整。本研究成果可作為 CCU 系統中藻池流場設計與導流裝置優化之參考，並有助於後續碳固定模組之系統整合與產業推廣。

In response to the growing urgency of climate change and carbon emission control, carbon capture and utilization (CCU) technologies have emerged as pivotal approaches for sustainable development of the world. Meanwhile, with its high carbon fixation capacity and renewable potential, algae cultivation plays a vital biological role in CCU systems. Therefore, in this study—conducted in collaboration with ViolonBiotech—we focus on enhancing the performance of a flow inducer in an algae pond. Specifically, using a numerical software of computational fluid dynamics (CFD), here we investigate how the installation location and blade geometry of the flow inducer can be optimized.
Technically, a full-scale three-dimensional numerical model of a cylindrical algae pond (having a radius of 1.8 m and a depth of 1.0 m) is constructed. Moreover, the “frozen rotor method” is used for flow field simulations, and the numerical results are supported by some flow measurement data (supplied by ViolonBiotech) to validate the adequacy of our computational model. Our numerical study then centers on two primary aspects. First, we examine the effects of the blade geometry—characterized by the elliptical semi-axes a and b, and the helical pitch p of the blade profile—on the flow efficiency and power consumption. And, second, we compare the performance of the flow inducer at various installation locations.
For blad geometry optimization, our numerical results indicate that the helical pitch p is the most sensitive parameter affecting both the power requirement to run the flow inducer and the flow enhancement. Also, the original blade design provided by ViolonBiotech happens to be near-optimal already. For installation location optimization, when the flow inducer is placed at the center of the pool, the numerical results suggest different optimal placement depths for various pool operational objectives: namely, 0.125 m above the pool bottom to improve bottom mixing and prevent bottom sediment; 0.875 m above the bottom (i.e., 0.125 m below the surface) for enhanced surface circulation and light uniformity; and 0.5-0.625 m above the pool bottom for overall energy dispersion and flow uniformity. Moreover, when the flow inducer is placed on the bottom of the pool at different locations from the center, with its longitudinal parallel or perpendicular to the radius, the flow efficiency also is examined. And the results show that, when the flow inducer is placed at the pool center, the average flow speed in the central region can be maximized (as expected) and the average flow speed attenuation with radius also is slower. Meanwhile, when the flow inducer is placed off-center, the flow speed distribution is less sensitive to the radial distance of the flow inducer from the pool center when its longitudinal axis is parallel to the radius (as opposed to being perpendicular to the radius). It is expected that these findings would offer practical guidance for optimizing the flow field design in CCU algae pond systems, thereby supporting the future development of carbon fixation modules for industrial applications.

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