Novel spacers for mass transfer enhancement in membrane separations

Li, F.; Meindersma, Wytze; Haan, A.B. de; Reith, T.

doi:10.1016/j.memsci.2004.12.019

Cited by 161 publications

(84 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Significant work along these lines has been reported (focusing on small or intermediate spatial scales) aiming to understand the effect of spacer characteristics on flow and mass transfer (e.g., [12][13][14]) in order to optimize the feed-spacer geometry (e.g., [15][16][17]) and to study fouling, including bio-fouling (e.g., [18,19]) phenomena. These detailed studies of the flow field in the spacer-filled channels, focusing on a "unit cell" formed by the net-type spacers (also considering periodicity), have proven to be quite fruitful; in addition to improved basic understanding, they have yielded correlations of pressure drop and mass transfer applicable at "unit cell" scale [20,21].…”

Section: Introductionmentioning

confidence: 99%

Fluid Dynamics and Mass Transfer in Spacer-Filled Membrane Channels: Effect of Uniform Channel-Gap Reduction Due to Fouling

Koutsou

Karabelas

Kostoglou

2018

Fluids

View full text Add to dashboard Cite

Abstract:The time-varying flow field in spacer-filled channels of spiral-wound membrane (SWM) modules is mainly due to the development of fouling layers on the membranes that modify the channel geometry. The present study is part of an approach to tackling this extremely difficult dynamic problem at a small spatial scale, by uncoupling the fluid dynamics and mass transfer from the fouling-layer growth process. Therefore, fluid dynamics and mass transfer are studied for a spacer-filled channel whose geometry is altered by a uniform deposit thickness h. For this purpose, 3D direct numerical simulations are performed employing the "unit cell" approach with periodic boundary conditions. Specific thickness values are considered in the range 2.5-10% of the spacer-filament diameter D as well as other conditions of practical significance. The qualitative characteristics of the altered flow field are found to be very similar to those of the reference geometry with no gap reduction. For a given flow rate, the pressure drop, time-average wall-shear stresses and mass-transfer coefficients significantly increase with increasing thickness h due to reduced channel-gap, as expected. Correlations are obtained, applicable at the "unit cell" scale, of the friction factor f and Sherwood number Sh, which exhibit similar functional dependence of f and Sh on the Reynolds and Schmidt numbers as in the reference no-fouling case. In these correlations the effect of channel-gap reduction is incorporated, permitting predictions in the studied range of fouling-layer thickness (h/D) = 0-0.10. The usefulness of the new results and correlations is discussed in the context of ongoing research toward improved modeling and dynamic simulation of SWM-module operation.

show abstract

Section: Introductionmentioning

confidence: 99%

Fluid Dynamics and Mass Transfer in Spacer-Filled Membrane Channels: Effect of Uniform Channel-Gap Reduction Due to Fouling

Koutsou

Karabelas

Kostoglou

2018

Fluids

View full text Add to dashboard Cite

show abstract

“…In these works, various geometrical parameters of spacers made by overlapping two series of cylindrical filaments were investigated: angle between crossing filaments, filament spacing, filament size, and flow attack angle. Also multi-layer and non-conventional (different filament shapes) spacers were studied [33,[36][37][38]. However, it appears clear that the literature is almost void of results on pressure drop in woven spacer-filled channels.…”

Section: Introductionmentioning

confidence: 99%

Pressure drop at low Reynolds numbers in woven-spacer-filled channels for membrane processes: CFD prediction and experimental validation

Gurreri

Tamburini

Cipollina

et al. 2017

DWt

View full text Add to dashboard Cite

a b s t r a c tThe energy consumption due to pumping power is a crucial issue in membrane processes. Spacers provide mechanical stability and promote mixing, yet increasing pressure drop. Woven spacers and their behaviour at low Reynolds numbers are less studied in the literature. Nevertheless, they are typical of some membrane technologies, as reverse electrodialysis (RED). RED is a promising technology for electric power generation by the chemical potential difference of two salt solutions within a stack equipped by selective ion-exchange membranes. The mechanical energy required for pumping the feed solutions, can dramatically reduce the net power output. In this work computational fluid dynamics (CFD) simulations of spacer-filled channels at low Reynolds numbers were carried out in parallel with an experimental campaign focused on the collection of data for model validation. Woven spacers 280-480 μm thick were investigated at the flow rates typical of RED channels. The construction of the computational domain was based on measurements made by optical microscopy and micrometer. Fully developed flow conditions were assumed, thus, periodic boundary conditions were adopted (unit cell approach). The experiments were carried out in a flow cell with one channel. Pressure drops were measured with and without the spacer, in order to quantify the effect of inlet-outlet channel and identify the distributed pressure drops due to the woven nets. Experimental results showed that the distributed pressure drop along the spacer-filled channel for the cases investigated is around 40% of the overall pressure loss. The significant contribution of the manifolds is due to the relatively high velocity of the fluid entering and leaving the channel in radial direction in the inlet and outlet holes, as in the RED stacks commonly used. However, an improved geometry of the distribution and collection system can easily result in a significant reduction of hydraulic loss in this part of the stack. Therefore, the optimization of the spacer geometry is crucial. In this regard, a good agreement between CFD results and experimental data on hydraulic loss along the channel was found, thus confirming that a simple CFD model (as the one presented in this work) can be a powerful and cheap tool, able to efficiently evaluate the pressure drops within spacer-filled channels of any customised geometry.

show abstract

“…In the geometry analyzed, vortex shedding occurred for hydraulic Reynolds numbers greater than 662. In a later work [25] using the same mass transport model, they assessed different conventional spacer configurations, as well as novel spacer types, by comparing their Sherwood and power numbers. Based on work for heat transfer, they proposed that an optimal spacer mesh should promote both longitudinal and transversal vortices.…”

Section: Introductionmentioning

confidence: 99%

“…Analogies to extrapolate heat transfer concepts into the field of mass transfer are commonly cited [25,30]. Yuan et al [31] pointed out that for periodically disturbed duct flow with heat transfer, entrance effects are much shorter than for flows without the disturbances.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of mass transfer in three-dimensional spacer-filled narrow channels with steady flow

Weihs

Wiley

2007

Journal of Membrane Science

152

View full text Add to dashboard Cite

Novel spacers for mass transfer enhancement in membrane separations

Cited by 161 publications

References 32 publications

Fluid Dynamics and Mass Transfer in Spacer-Filled Membrane Channels: Effect of Uniform Channel-Gap Reduction Due to Fouling

Fluid Dynamics and Mass Transfer in Spacer-Filled Membrane Channels: Effect of Uniform Channel-Gap Reduction Due to Fouling

Pressure drop at low Reynolds numbers in woven-spacer-filled channels for membrane processes: CFD prediction and experimental validation

Numerical study of mass transfer in three-dimensional spacer-filled narrow channels with steady flow

Contact Info

Product

Resources

About