根據修正型阻力串聯模式，考慮濃度極化現象沿著薄膜管增加並透膜壓差、體積流率隨之下降，一組估算管式薄膜超過濾器局部和平均濾速之關係式可透過質量與動量平衡求得。在各種進料濃度、透膜壓差及體積流率等操作條件變化下，以Dextran T500水溶液在陶瓷薄膜管中的超過濾實驗為例，由10個濾液出口局部濾速的實驗數據證實了估算式的正確性，並進而討論濃度極化遞增造成濾速沿薄膜管的衰退。 接下來，我們在薄膜管中插入一鋼棒，於其上繞環，觀察改變繞環密度並沿管軸改變繞環間距對濾速的影響，並進行理論分析。結果顯示適當地調整繞環間距，藉以消除濃度極化的影響，並維持有效的透膜壓差，將可大大改善超過濾的操作效率。 The correlation equations for predicting local and average permeate fluxes in tubular-membrane ultrafilters was derived from mass and momentum balances by the modified resistance-in-series model with the consideration of concentration polarization along the membrane tube. Ultrafiltration of Dextran T500 aqueous solution in a tubular microporous ceramic module has been carried out under various operation conditions, in which experimental data of ten local permeate fluxes along the tube were obtained to confirm the correlation predictions. The increment of concentration polarization, as well as the decline of permeate flux, along the tube was also discussed. The theoretical predictions and experimental study were also carried out for ultrafiltration in a tubular module inserted concentrically with a steel rod wrapped by rings with various ring distances also the flow channel. Considerable improvement in performance was obtained by properly adjusting the ring distance, so that the undesirable concentration polarization resistance is suppressed while still preserving the effective transmembrane pressure.
