Comparison of two types of flows (crossflow and swirling flow) in ultrafiltration modules - Influence of the wall constraint

This work consists of evaluating the performances of a new membrance separa tion process: an annular, swirling, decaying flow induced by a tangential i nlet. For this purpose, we have compared the permeation flux obtained in sw irling flow with that of a crossflow. We ultrafiltered a model suspension o f bentonite in order to compare the performances of the two modules for dif ferent operating conditions. Parameters such as flow rate, Reynolds number and wall velocity gradient were studied, and this last one appears to be a significant hydrodynamic parameter to compare the performances of the two c onfigurations. Indeed, this parameter takes into account the flow field nat ure and, more precisely, the shear stress at the membrane surface. improvem ent of the permeation flux induced by the swirling, decaying flow in compar ison with that observed in cross-flow can reach more than 30% under specifi c conditions. The study of the energy consumption of these two cells allows us to confirm the interest of the swirling, decaying flow in order to desi gn new types of membrane separation modules.