COMSOL simulation and experimental validation of promoter geometries facilitating citric acid transport in electrodialysis

Abstract

Citric acid transport facilitation in electrodialysis was investigated using different flow promoter geometries e.g. rod, twisted tape (TT), rectangular winglet (RW) shape vortex generator (VG) and helical screws at four different flow rates 5, 10, 15 and 20 LPH. Flow visualization of 39 promoters (shape, spacing and orientation) were performed using 3D simulation (COMSOL Multiphysics® 5.3a). Based on simulation results, 14 best promoters were selected for experimental determination of ion transport and power consumption from Sherwood number, Sh and Power number, Pn respectively. With increase in flow rate and reduced spacing, Sh increased along with Pn. Mesh type TT performed better than mono layer TT but pressure drop increased. Screw promoter placed parallel to flow showed higher Sh and Pn compared to rod, VG and TT. 50% rise in Sh was noted with helical screw (d/h = 1.33, α = 90°) relative to empty channel. 1.5 times rise in LCDs were noted with conducting TT compared to non-conducting TTs with barely 1.5% increase in Pn. LCDs with conducting TTs were 80% higher compared to empty channel. © 2019 Institution of Chemical Engineers