管式薄膜模組中超過濾之效能可經由軸心處置入不鏽鋼棒柱獲得改善。進一步地，可利用撓以固定角度之螺線棒柱來提升流體速度，以改善模組中超過濾之濾速。此外，濾速效能亦可藉由固體棒柱模組中棒柱半徑沿管軸方向漸增或藉由撓線棒柱模組中撓線角度沿管軸方向漸增的方式來獲得提升。由於濃度極化層的厚度係沿著掃流通道而增加，而透膜壓差係沿掃流通道而衰退。如此，於撓線模組中，進口端利用較小的撓線角度與較小的流體速度提升，足以降低該處較低的濃度極化層阻力，而於出口端仍夠保留有效的透膜壓差。理論分析乃以阻力串聯模式為分析核心，並且結合動量平衡之應用加以探討。藉此分析方法，所得理論之濾速值與相關實驗所測得數據，趨勢相當吻合。 The performance of ultrafiltration in tubular membranes could be improved by concentrically inserting a steel rod, and further improved by wrapping a wired spiral of uniform angles on the entire rod, to increase fluid velocity. Considerable enhancement of performance was also achieved by gradually increasing the rod radius in solid−rod device, or by gradually increasing the wire angle in wired−rod device. This is because that the thickness of the concentration polarization layer increases along the cross−flow channel and transmembrane pressure decreases. Thus, the smaller inclined angle of wire spiral, as well as smaller increment in fluid velocity, around the inlet region, is sufficient to reduce the lower concentration polarization resistance, while still preserving the effective transmembrane pressure around outlet region. Theoretical analysis was based on the resistance−in−series model coupled with the application of momentum balance. Correlation predications are qualitatively agreement with the experimental results.
