Deduction of Boundary Values of Variables for a Membrane System in Desalination Unit

The present study is a theoretical one interesting the evaluation the local values of variables in a reverse osmosis system during desalination. From practical observations; scale formation on membrane module leafs forms a main technical problem in desalination by reverse osmosis. This situation is accompanied by the high salinity feed. The purpose of the present study is to deduce the values of residue steam concentration at the boundary points of a membrane leaf in spiral-wound module. These were obtained through mathematical modeling where simultaneous variation of other system variable were considered. The obtained model consisted of a set of partial differential equations describing both residue and permeate pressures, concentrations and velocities. Being implicit, the model was solve dnumerically with special emphasis on the values at the corners of membrane sheet. The influence of operating pressure beside feed concentration were considered. Two limiting values of pressure were used 40 x 105 and 80 x 105 Pa, beside the nominal mean value. With respect to concentration; 20,000 and 40,000 ppm in addition the base value of 35,000 ppm were used. The study showed that that the most probable point for scale formation is the end point in both x-y domains of the membrane leaf. Greater increasing rate in feed flow direction was observed. Perpendicularly; permeate concentration showed slight ascent in passing through its channel. = = = = = = = =