STUDY OF AN ANALYTICAL MODEL FOR HOLLOW-FIBER REVERSE-OSMOSIS MODULE SYSTEMS

A number of investigators have made efforts to develop various analyti cal models for hollow fiber type reverse osmosis (RO) module systems s ince the 1970s. However, a perfect analytical model, which can precise ly explain the observed RO performances under a wide range of operatin g conditions has not been developed yet. The author previously propose d a precise analytical model called a friction-concentration-polarizat ion model (FCP model) [1], which used the Kimura-Sourirajan model for transport phenomena of solute and water transport through a membrane, taking a mass transfer coefficient as local variables and taking a fib er-bore side pressure drop into account. In the application of this mo del, fundamental transport parameters of hollow fiber membranes were n eeded, and they were initially determined by a U-tube membrane test wh ere the effect of concentration polarization could be neglected. Then a local mass transfer coefficient was estimated from experimental data using actual modules as a function of Reynolds and Schmidt numbers by a trial-and-error method for both brackish water and seawater desalin ation cases. Using all of the above results, behaviors of hollow fiber modules under various operating conditions were estimated and compare d with the results obtained from commercial size module experiments. C ompared to other previous models, the FCP model is verified to be the best one to predict actual module performances. This model will be fur ther extended to analyze a change of transport parameters during long- term runs.