Study of mass transfer characteristics for a hollow fiber reverse osmosis module

The reverse osmosis separation process has become important as an energy saving (no phase change) process for brackish water and seawater desalination. Several analyses on hollow fiber reverse osmosis modules in which permeate water flows from outer side to inner side of hollow fiber bore have been attempted over the past twenty years. An FCP Model (Friction Concentration Polarization Model) was previously presented that showed good fit with a wide range of actual performance data on a hollow fiber reverse osmosis module. However, this analytical model contained the anomaly that the simulated boundary layer thickness is larger than the apparent length of the clearance among hollow fibers. Here, we propose a hollow Fiber Group Model that is consistent with the features of the hollow fiber arrangement of the practical reverse osmosis module. As a result of verifying this model, it was confirmed that the boundary layer thickness on the surface of the fiber group is smaller than the length of clearance between the fiber groups. Consequently the anomaly was broken off by this Fiber Group Model.