CFD Investigation of the Effect of the Feed Spacer on Hydrodynamics in Spiral Wound Membrane Modules

Abstract

Spacers are designed to create a feed channel, but they are also obstacles to the flow in spiral wound membrane modules. The geometry of the feed spacer influences the flow pattern, which was investigated by using a three-dimensional Computational Fluid Dynamics (CFD) model. For the conventional feed spacer, unavoidable disadvantages were caused by its line contact with the membrane. The pillar-like feed spacer was designed to achieve area contact, which made it possible to enhance the porosity and minimize the adverse effects from the dead zone caused by the transverse filament. Through reductions in the connecting filament’s diameter, the channel porosity reached 0.979. Regarding the maximum porosity, the dimensionless power number was reduced by 47.31% at Reynolds number 150 in comparison with a previously studied commercial spacer. Furthermore, a modified friction factor, as a dimensionless parameter, was employed to investigate the shear stress at the membrane’s surface. At dimensionless power number 106, the enhancement of the modified friction factor increased by approximately 22.27% in comparison with the results of a previous study. Based on the numerical prediction, the homogenization of shear stress distribution, which changed the flow profile near the membrane, was featured through contour plots.

A Review of CFD Modelling and Performance Metrics for Osmotic Membrane Processes

“…In view of this, CFD modelling is often preferred over experimental tests for predicting the performance of novel spacer geometric designs. Hence, numerical studies of several complex spacer geometries can be found in the literature, such as the triply periodic minimal surface (TPMS) structure ( Figure 3 b) [ 52 , 60 , 63 , 64 , 65 ], perforated spacer geometries ( Figure 3 c) [ 55 ] and submerged spacers with column nodes ( Figure 3 d) [ 56 , 58 , 66 ]. Although a previous review [ 18 ] has discussed the criteria for optimising spacer design, most designs are still restricted to simple cylindrical or two-layer spacer geometries.…”

“…At the time of writing, CFD studies of RO processes have mainly focused on either 2D unsteady state [ 74 , 75 , 76 , 77 , 78 , 79 ] or 3D steady state [ 51 , 54 , 57 , 66 , 80 , 81 , 82 ]. It is worth noting that the ability of 2D and 3D CFD modelling for predicting mass transport and concentration polarisation has been well established in the literature [ 46 , 68 , 74 , 83 ].…”

Energy efficient 3D printed column type feed spacer for membrane filtration

“…Numerical studies have proposed efficient spacer designs, geometries, and arrangements (Amokrane et al, 2015;Han et al, 2018;Kavianipour et al, 2017;Koutsou et al, 2007;Saeed et al, 2015;Saeed et al, 2012). The circular and elliptical shaped filaments reduced the hydraulic resistance compared to the other spacer geometries while the triangular and square filaments increased the mass transfer (Ahmad and Lau, 2006).…”

Optimizing the Disinfection Inactivation Efficiency in Wastewater Treatment: A Computational Fluid Dynamics Investigation of a Full‐Scale Ozonation Contactor

“…The flows in the ozone contactor were considered isothermal, and the Grace Drag force model was applied for the interphase momentum transfer and turbulent dispersion [34]. The turbulence of the dispersed gas phase was modeled using a zero-equation model for the dispersed phase, and bubble-induced turbulence was considered based on [35]. The transport equation was also used to describe the evolution of ozone concentration and total coliforms in the fluid, and to account for any reactions that may occur.…”