Electromagnetic–mechanical desalination: Mathematical modeling

Abstract

A theoretical model is developed for electromagnetic–mechanical salt removal (EMSR) process and solved numerically to investigate the optimum operating parameters for separation. The fluid flow and charged particle motion under hydrodynamics, and electrostatic and magnetic forces are modeled using the CFD software ANSYS FLUENT. The Navier–Stokes equations are solved using Eulerian approach, while the discrete phase is modeled using a Lagrangian approach. A source term is added to the Navier–Stokes equation to account for the effect of electric and magnetic fields. The developed model is validated using results in the literature. Different important operating parameters, i.e. electrical and magnetic forces, charged particle diameter, and fluid velocity affecting separation process are examined using the developed model. It is shown that operating at a lower fluid velocity increases the residence time and increases the separation efficiency. Operating at a lower charged particle velocity in the axial direction is recommended even though it decreases the induced magnetic force. Doubling the induced electrical and magnetic forces increased the transverse velocity and decreased the capture time each by about 2 times. However, doubling the axial flow velocity increased the transverse velocity 25% only. It is clearly demonstrated that combining electrical and magnetic forces together can effectively be used to separate dissolved salts from seawater.