Operating Parameters for Rotating Taylor-Couette Filtration

摘要

Filters consisting of an inner cylindrical filter rotating within a concentric outercylinder are widely used for collecting plasma from blood. The rotating inner filterproduces a centrifugal field and a high shear rate which, along with counter rotatingtorroidal vortices, reduce membrane fouling and plugging. These filters have potentialapplication in water filtration for long range space missions and other applications wherefilter replacement is an issue. In this work, we have developed guidelines for the optimaldesign of rotating filtration systems by performing a series of tests under a variety ofconditions and measuring the cake layer buildup on the filter surface. The fraction of theparticles entering the device that form a cake layer decreases substantially as therotational speed of the device increases from 0 to 500 rpm. Inlet suspensionconcentration, varying between 0.025% and 0.2% by volume, had minimal effect onmembrane fouling at moderate angular velocities. The cake layer is strongly dependenton the size of the particles used, with smaller particles causing more cake build up. Akey parameter characterizing the fouling prevention is the ratio of shear force to theStokes drag on the particle. As this ratio increases, the cake buildup decreases.