The influence of the pressure drop on the driving force for pressure driven membrane processes

The influence of pressure drop on driving force for pressure driven membrane processes was investigated. Equations describing relations between the pressure drops in the retentate channel and the driving force under the assumption of incompressible fluid flows and constant pressure in the permeate channel, were derived. These equations, using values of membrane permeability and experimental data for the friction factor dependence on the Reynolds number in the spacer-filled channel, predict an adverse effect of the pressure drop in the retentate channel of membrane module on the driving force. For laminar flow, theoretically derived equations describing the pressure drops in the retentate channel with a spacer were experimentally verified. Practical applications of the results obtained with respect to the design of membrane module are discussed