Wall shear stress at the membrane surface and at the surface of plexiglas

Abstract

The wall shear stress is determined at the surface of a plane ceramic ultrafiltration membrane and at the plate of Plexiglas in a tangential ultrafiltration module. In a first time, the shear stresses are determined at the surface of a plate of Plexiglas mimicking a membrane and at the plane membrane surface without fouling particles with the aim to investigate the influence of permeation. In the second time, the wall shear stress is determined at the surfaceof the plane membrane during the ultrafiltration of spherical no compressible particles suspension inducting a deposit at the membrane surface. In order to study the influence of the concentration of the particles, two concentrations of particles were used for the experiments. The values of the mean wall shear stress and its fluctuations (turbulent intensity rate) were measured by using an electrochemical method. 20 microelectrodes, on which an electrochemical reaction occurs, are mounted flush to the plate of Plexiglas and to the surface of the membrane to determine the maps of shear stress and turbulent intesity rate for two inlet/outlet distributors' configurations.