Effect of feed spacer arrangement on flow dynamics through spacer filled membranes

Saeed, Asim; Vuthaluru, Rupa; Yang, Yanwu; Vuthaluru, Hari

doi:10.1016/j.desal.2011.09.050

Cited by 69 publications

(37 citation statements)

References 24 publications

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“…However, flow reattachment region appears for the spacers having L 2 > 3 which is in line with our previous study (Saeed et al, 2012) and other modeling studies (Shakaib et al, 2007(Shakaib et al, , 2009 involving flow through spacer-obstructed narrow feed channels when the top and bottom feed channel side spacers are oriented in axial and transverse direction to the main flow.…”

supporting

confidence: 84%

“…Moreover, in the flow direction, there is translational periodicity, that is, along the flow direction (x-direction) the flow patterns repeat itself after periodic intervals. It has been shown in our previous study (Saeed et al, 2012) that the entrance …”

Section: Computational Domain and Boundary Conditionsmentioning

confidence: 94%

“…However, there appears a need to change membrane or membrane secondary structures to alter the flow patterns associated with fluids within the membrane module. Schematic diagram of spiral wound module (SWM), in partly unwounded state, has been presented earlier in one of our articles (Saeed et al, 2012). In case of SWM, a number of flat membrane sheets are glued together, in pair arrangement, on three sides to form a pocket and a permeate spacer is introduced between the membranes pocket.…”

Section: Introductionmentioning

confidence: 99%

“…Our earlier work (Saeed et al, 2012) dealt with the impact of spacer filament orientation on hydrodynamics at fixed spacer mesh length. Although several modeling efforts are dealt with the prediction of flow behavior and concentration patterns for cross-flow membrane operations (Karode and Kumar, 2001;Li et al, 2004;Ghidossi et al, 2006;Santos et al, 2006Santos et al, , 2007Lau et al, 2009), the relative fouling propensities of top and bottom membrane surfaces are never addressed in any study.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Feed Spacer Filament Spacing on Mass Transport and Fouling Propensities of RO Membrane Surfaces

Saeed

Vuthaluru

2014

Chemical Engineering Communications

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Material build-up on membrane surfaces is one of the vital challenges faced by Reverse Osmosis operations, leading to many operational and maintenance issues. To date, several modeling studies are dealt with flow behavior and concentration patterns for cross-flow membrane operations. However, the relative fouling propensities of top and bottom membrane surfaces are never addressed in any study for narrow channels filled with ladder-type spacers. In the present work, fluid flow patterns through different spacer configurations are visualized using ANSYS FLUENT by varying the dimensionless filament spacing, L (ratio of top or bottom filament spacing and channel height). Results clearly indicate that the average shear stress values at the top membrane surface are always higher (3-8 times) than that at the bottom membrane surface, but the mass transfer coefficient for the two walls yielded approximately similar average values having low to moderate filament spacings of L 3 (SP22 and SP33), indicating similar fouling propensities of membrane surfaces. Further increase in filament spacing with L ! 4 (SP44 and SP66), the average mass transfer coefficient for the top membrane indicated a sharp decline, suggesting high fouling propensity compared to bottom membrane which is not a desirable feature. Among the four spacer arrangements studied, SP44 (with L ¼ 4) was found to be the optimal arrangement, yielding moderate pressure drop with nearly equal=higher area weighted values of mass transfer coefficient for the two walls and would lead to lower and equal fouling tendencies for top and bottom membrane surfaces, respectively.

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supporting

confidence: 84%

Section: Computational Domain and Boundary Conditionsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of Feed Spacer Filament Spacing on Mass Transport and Fouling Propensities of RO Membrane Surfaces

Saeed

Vuthaluru

2014

Chemical Engineering Communications

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“…Some studies have simulated fluid flow and mass transfer in simplified two-dimensional setups (Schwinge et al, 2002;Radu et al, 2010). However, in recent years, threedimensional (3-D) numerical models are becoming increasingly accessible, developed mainly with an emphasis on the effect of feed spacer on hydrodynamics and mass transfer in feed spacer channels (Koutsou et al, 2007(Koutsou et al, , 2009Saeed et al, 2012). Simplified cylindrical shapes have been used for representation of spacer filaments in most of the numerical studies.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical characterization of the water flow in spacer-filled channels of spiral-wound membranes

et al. 2015

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Micro-scale flow distribution in spacer-filled flow channels of spiral-wound membrane modules was determined with a particle image velocimetry system (PIV), aiming to elucidate the flow behaviour in spacer-filled flow channels. Two-dimensional water velocity fields were measured in a flow cell (representing the feed spacer-filled flow channel of a spiral wound reverse osmosis membrane module without permeate production) at several planes throughout the channel height. At linear flow velocities (volumetric flow rate per cross-section of the flow channel considering the channel porosity, also described as crossflow velocities) used in practice (0.074 and 0.163 m·s(-1)) the recorded flow was laminar with only slight unsteadiness in the upper velocity limit. At higher linear flow velocity (0.3 m·s(-1)) the flow was observed to be unsteady and with recirculation zones. Measurements made at different locations in the flow cell exhibited very similar flow patterns within all feed spacer mesh elements, thus revealing the same hydrodynamic conditions along the length of the flow channel. Three-dimensional (3-D) computational fluid dynamics simulations were performed using the same geometries and flow parameters as the experiments, based on steady laminar flow assumption. The numerical results were in good agreement (0.85-0.95 Bray-Curtis similarity) with the measured flow fields at linear velocities of 0.074 and 0.163 m·s(-1), thus supporting the use of model-based studies in the optimization of feed spacer geometries and operational conditions of spiral wound membrane systems.

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Design and Construction of Commercial Spiral Wound Modules

Johnson¹

2013

Encyclopedia of Membrane Science and Technology

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The spiral‐wound membrane module offers users of industrial‐scale reverse osmosis an economical combination of low cost, high membrane area density, and favorable mass transfer. The module combines flat‐sheet reverse osmosis membrane with spacer materials for conveying feed and permeate, engineered components for sealing and isolating the fluid streams, and structural members to protect the membrane and maintain integrity in severe environments. Considerations relevant to the design of commercial modules are reviewed on a component‐by‐component basis, drawing upon fundamental engineering principles and representative works from the scientific and applied literature. Future directions in module design and recent developments related to large‐diameter modules are also discussed.

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Effect of feed spacer arrangement on flow dynamics through spacer filled membranes

Cited by 69 publications

References 24 publications

Impact of Feed Spacer Filament Spacing on Mass Transport and Fouling Propensities of RO Membrane Surfaces

Impact of Feed Spacer Filament Spacing on Mass Transport and Fouling Propensities of RO Membrane Surfaces

Experimental and numerical characterization of the water flow in spacer-filled channels of spiral-wound membranes

Design and Construction of Commercial Spiral Wound Modules

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