3D CFD study on hydrodynamics and mass transfer phenomena for SWM feed spacer with different floating characteristics

•Effect of different degrees of “floating” characteristics of spacer are simulated.•Mass transfer is more sensitive to change in structure for 2-layer than for 3-layer.•Rf is not a determining factor that drives SWM mass transfer enhancement.•Middle spacer disrupts the formation of large streamwise...

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Bibliographic Details
Published in:Chemical engineering research & design 2020-07, Vol.159, p.36-46
Main Authors: Toh, K.Y., Liang, Y.Y., Lau, W.J., Fimbres Weihs, G.A.
Format: Article
Language:English
Subjects:
CFD
Computational fluid dynamics
Computer simulation
Design modifications
Filaments
Floating spacer
Fluid dynamics
Fluid flow
Heat transfer
Hydrodynamics
Mass transfer
Mathematical models
Membranes
Osmosis
Reverse osmosis
Shear stress
Simulation
Spiral wound module
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Summary:•Effect of different degrees of “floating” characteristics of spacer are simulated.•Mass transfer is more sensitive to change in structure for 2-layer than for 3-layer.•Rf is not a determining factor that drives SWM mass transfer enhancement.•Middle spacer disrupts the formation of large streamwise vortex at larger Reh.•Middle spacer significantly increase wall shear than for including woven structure. Enhancing the efficiency of reverse osmosis (RO) applications through the design and modification of spacer geometries for spiral wound membrane (SWM) modules remains a challenging task. In this work, four 3D feed spacer geometries with different degrees of “floating” characteristics are studied using computational fluid dynamics (CFD) simulations to investigate the mechanisms that result in shear stress and mass transfer enhancement. The modelled data reveal that the floating ratio (Rf) is not a determining factor for mass transfer enhancement, as the transport mechanism is more strongly dependent on other geometric characteristics, such as a 2- or 3-layer design. The λ2 analysis confirms our hypothesis, as the middle filament in a 3-layer design disrupts the formation of the large streamwise vortex located downstream of the intersection between the top and bottom filaments at Reh 200. This explains why 3-layer spacers (both woven and non-woven) show lower Sherwood number (Sh) than a 2-layer woven (2LW) spacer at Reh 200. However, at a smaller Reh (
ISSN:0263-8762
1744-3563
DOI:10.1016/j.cherd.2020.04.010