Studies into the mass transfer and energy consumption of commercial feed spacers for RO membrane modules using CFD: Effectiveness of performance measures

Abstract

Highlights Power law performance correlations have been formulated for four commercial feed spacers  Different performance measures yield different spacer rankings at different flowrates  The DelStar 90 HDPE spacer has good performance and a weak response to changing flowrate  The SPMP performance measure does not show consistent behaviour with flowrate

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

“…SWMs consist of a sandwich of flat sheet membranes, spacer filaments and porous permeate flow material, wrapped around a central permeate collecting tube [ 49 ]. The presence of spacers in the feed channels of the SWM helps improve permeate flux by promoting fluid mixing that enhances mass transfer and reduces concentration polarisation [ 50 , 51 , 52 ], albeit at the cost of an increased pressure loss [ 53 , 54 , 55 ]. As spacer geometry has a large impact on the flow distribution (and hence on mass transfer), spacer modification remains an active and ongoing research field aiming to improve on three important issues: (1) flux enhancement [ 52 , 56 , 57 ], (2) pressure loss reduction [ 52 , 55 , 56 , 58 ], and (3) mitigating the fouling caused by the spacer whereby some regions experience low levels of fluid mixing [ 52 , 55 , 56 ].…”

“…The most commonly used spacer geometries in SWM modules comprise two layers of non-woven spacer filaments ( Figure 3 a) with differing cross section shapes, sizes and flow attack angles [ 51 , 59 , 60 ]. Given the current advances in CFD and 3D printing technologies, many hurdles in the design and manufacture of novel spacers with complicated configurations have been overcomed.…”

“…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 ].…”

“…Given that energy consumption remains an important issue for RO, many energy performance metrics have been proposed. These include (1) specific power consumption (SPC) [ 50 , 51 , 54 , 142 ], (2) spacer configuration efficacy (SCE) [ 51 , 54 , 142 ], (3) spacer performance ratio (SPMP) [ 51 , 143 ] and (4) specific energy consumption (SEC) [ 104 , 105 ]. Of these, SEC is the most commonly cited indicator for measuring SWM performance.…”

Numerical Simulations of Calcium Sulphate Scaling in Full-Scale Brackish Water Reverse Osmosis Pressure Vessels Using Computational Fluid Dynamics

“…Computational fluid dynamics (CFD) packages have been used to simulate 2D, 3D, unsteady and steady flows in RO modules [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Many models provide insights into the flow behaviour in spacer-filled channels, which can be used to understand mass transfer and concentration polarisation phenomena and to improve the design of the feed channel of RO membrane cells [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”