Hollow-fibre membrane module design: comparison of different curved geometries with Dean vortices

The performance of several designs of curved membrane modules with Dean vor tices was compared through experiments using a colloidal bentonite suspensi on and cellulose acetate hollow-fibre ultrafiltration (UF) membranes. The d ifferent module geometries were: straight, helically coiled, twisted and si nusoidal, or meander-shaped. The experiments show a remarkable increase in mass transfer in curved modules as compared to conventional straight ones. Comparisons were made for modules equipped with the same hollow fibres and the same Dean number (De) for a given Reynolds number (Re), At the same Dea n number all the curved geometries gave the same limiting permeate Aux. A m ass transfer correlation relating limiting UF flux with the mean wall shear stress has been obtained. (C) 2001 Elsevier Science B.V. All rights reserv ed.