Hollow Fiber Reverse Osmosis Module Research Articles

Optimum operating condition of a hollow fiber reverse osmosis desalination system

A numerical simulation for an optimal operating condition of a hollow fiber reverse osmosis desalination system has been carried out by utilizing the membrane transport model based on the porous media theory. The validity of the present numerical simulation has been examined by comparing permeate salinity and flow rate obtained by the present method with the available experimental data. The three-dimensional numerical computations have revealed individual velocity and concentration distributions for brine, permeate and membrane phases in a hollow fiber reverse osmosis module containing a feeder core tube. Moreover, it has been found that optimal feed brine pressure exists in order to receive the maximum permeate flow rate under the same pumping power. The present numerical methods is useful to design a hollow fiber desalination module and find the operating conditions of a desalination system.

A Porous Media Approach for Hollow Fiber Transport Phenomena

A porous media approach based on the volume averaging theory has been proposed to investigate membrane transport processes associated with hollow fiber dialyzers and radial flow hollow fiber reverse osmosis module. A general set of macroscopic governing equations has been derived for the three individual phases, namely, the lumen side flow phase, shell side flow phase and membrane phase. Analytical and numerical solutions based on the present approach are found to agree well with available experimental data. Three-dimensional numerical models can be used for possible optimization of the hollow fiber membrane systems.

I111 多孔質体理論に基づく中空糸型逆浸透膜モジュールの数学モデル(OS-16: 多孔質体内の熱物質輸送と応用(1))

I111 多孔質体理論に基づく中空糸型逆浸透膜モジュールの数学モデル(OS-16: 多孔質体内の熱物質輸送と応用(1))

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.

Global optimal design of reverse osmosis networks for seawater desalination: modeling and algorithm

A novel global optimization algorithm to solve nonconvex problem is used to find the global optimal design of reverse osmosis networks for seawater desalination. The objective is to determine the optimal process design and operating conditions for a given water production. The networks were designed by using hollow fiber reverse osmosis modules. The Kimura–Sourirajan model was used for describing transport phenomena of solute and water transport through the membrane. The concentration polarization phenomenon has been taken into account. It was mathematically described using the film theory. The objective function to be minimized is the cost, which includes capital investment (membrane cost, pumping and energy recovery system, intake and pre-treatment systems, etc.) and operation and maintenance costs (membrane replacement, chemical treatment, spares, required and recovered energy, etc.). The proposed algorithm is deterministic and attains finite convergence to the global optimum. It is iterative and a main problem is solved each iteration. The main problem has convex constraints and a nonconvex objective function. The main problem solution indicates either a better solution for the original problem, or a region which can be discarded. Therefore, the feasible region to improve the objective function is reduced each iteration. The algorithm finishes when the whole region has been analysed and discarded. A bound reduction technique is performed in order to accelerate the convergence speed. The algorithm shows a good performance and efficient execution time. Different cases are solved in order to show the methodology and computational performance.

Seawater Desalination Technology by Hollow Fiber Reverse Osmosis Module.

Seawater Desalination Technology by Hollow Fiber Reverse Osmosis Module.

Newly Developed Economical Sea Water Desalination System by Hollow Fiber Reverse Osmosis Module

Newly Developed Economical Sea Water Desalination System by Hollow Fiber Reverse Osmosis Module

Analysis and Simulation of Hollow-Fiber Reverse-Osmosis Modules

Abstract The purpose of this work is to analyze the performance of hollow-fiber reverse-osmosis (HFRO) systems. First, the mass and momentum balances on the fluids inside and outside of the hollow fibers are derived. Consequently, these equations are coupled with the membrane transport expressions to provide a two-phase model for completely describing the hydrodynamic behavior of HFRO units. The model equations are solved numerically via discretization techniques. Experimental data are used for two objectives; transport-parameters estimation and model validation. Based upon optimization principles, a parameter-estimation technique is proposed for correlating the membrane-transport coefficients with the operating pressures and concentrations. The model validity is elucidated by comparing the theoretical predictions with the experimental data for different HFRO modules and over a wide range of operating parameters.

Study of an analytical model for hollow fiber reverse osmosis module systems

A number of investigators have made efforts to develop various analytical models for hollow fiber type reverse osmosis (RO) module systems since the 1970s. However, a perfect analytical model, which can precisely explain the observed RO performances under a wide range of operating conditions has not been developed yet. The author previously proposed a precise analytical model called a friction-concentration-polarization 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 fiber-bore side pressure drop into account. In the application of this model, fundamental transport parameter of hollow fiber membranes were needed, and they were initially determined by a U-tube membrane test where 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 Schimidt numbers by a trial-and-error method for both brackfish water and seawater desalination cases. Using all of the above results, behaviors of hollow fiber modules under various operating conditions were estimated and compared with the results obtained from commercial size module experiments. Compared to other previous models, the FCP model is verified to be the best one to predict actual module performances. This model will be further extended to anlyze a change of transport parameters during long-term runs.

Precise analytical model of hollow fiber reverse osmosis modules

A highly reliable and detailed analytical model for the hollow fiber reverse osmosis module is reported. The model introduced concentration polarization into the transfer equations, which are usually neglected, combined with the pressure drop in the fiber bore. In this model, friction-concentration-polarization model (FCP model), the membrane transport equations were derived from the solution-diffusion model and the concentration polarization model while the pressure drop in the fiber bore was introduced with the Hagen-Poiseuille equation. The membrane permeability constants in the solution-diffusion model were experimentally determined. The mass transfer coefficients in the concentration polarization model were calculated by previously derived equations. The model was verified by reverse osmosis using Toyobo's hollow fiber modules for both brackish water and seawater desalination, and showed good agreement.