The effects of membrane and channel corrugations in forward osmosis membrane modules – Numerical analyses

Alshwairekh, Ahmed M.; Alghafis, Abdullah; Alwatban, Anas M.; Alqsair, Umar F.; Öztekin, Alparslan

doi:10.1016/j.desal.2019.03.003

Cited by 26 publications

(7 citation statements)

References 33 publications

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“…Shear strain rate analysis was performed to determine the strain rate exerted by the fluid on the membrane surface, as an indicator for the mitigation of fouling and ECP [36][37][38][39]. Complimentary to Reynolds number assessment, shear rate provides additional assessment needed when improving flux performance of FO systems [40]. Shear rate offers a more specific characterisation of the force on the membrane surface and is directly related to energy expenditure needed thus imperative to find an optimum between CP mitigation and cost.…”

Section: Assessment Of Channel Occlusion On Shear Ratementioning

confidence: 99%

Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics

et al. 2020

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In an effort to improve performances of forward osmosis (FO) systems, several innovative draw spacers have been proposed. However, the small pressure generally applied on the feed side of the process is expected to result in the membrane bending towards the draw side, and in the gradual occlusion of the channel. This phenomenon potentially presents detrimental effects on process performance, including pressure drop and external concentration polarization (ECP) in the draw channel. A flat sheet FO system with a dot-spacer draw channel geometry was characterized to determine the degree of draw channel occlusion resulting from feed pressurization, and the resulting implications on flow performance. First, tensile testing was performed on the FO membrane to derive a Young’s modulus, used to assess the membrane stretching, and the resulting draw channel characteristics under a range of moderate feed pressures. Membrane apex reached up to 67% of the membrane channel height when transmembrane pressure (TMP) of 1.4 bar was applied. The new FO channels considerations were then processed by computational fluid dynamics model (computational fluid dynamics (CFD) by ANSYS Fluent v19.1) and validated against previously obtained experimental data. Further simulations were conducted to better assess velocity profiles, Reynolds number and shear rate. Reynolds number on the membrane surface (draw side) increased by 20% and shear rate increased by 90% when occlusion changed from 0 to 70%, impacting concentration polarisation (CP) on the membrane surface and therefore FO performance. This paper shows that FO draw channel occlusion is expected to have a significant impact on fluid hydrodynamics when the membrane is not appropriately supported in the draw side.

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Section: Assessment Of Channel Occlusion On Shear Ratementioning

confidence: 99%

Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics

et al. 2020

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“…Another important observation is that most CFD studies of FO systems are restricted to only 2D analyses of spacer design [ 41 , 109 , 115 , 116 , 118 ], except few employing 3D simulations [ 36 , 119 ]. Hence, more research in these directions is required to shed insights into the development of improved spacers suited for FO.…”

Section: Existing Cfd Models and Their Challengesmentioning

confidence: 99%

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

et al. 2020

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Simulation via Computational Fluid Dynamics (CFD) offers a convenient way for visualising hydrodynamics and mass transport in spacer-filled membrane channels, facilitating further developments in spiral wound membrane (SWM) modules for desalination processes. This paper provides a review on the use of CFD modelling for the development of novel spacers used in the SWM modules for three types of osmotic membrane processes: reverse osmosis (RO), forward osmosis (FO) and pressure retarded osmosis (PRO). Currently, the modelling of mass transfer and fouling for complex spacer geometries is still limited. Compared with RO, CFD modelling for PRO is very rare owing to the relative infancy of this osmotically driven membrane process. Despite the rising popularity of multi-scale modelling of osmotic membrane processes, CFD can only be used for predicting process performance in the absence of fouling. This paper also reviews the most common metrics used for evaluating membrane module performance at the small and large scales.

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“…FO membrane moduled into traditional spiral wound and plate-and-frame configurations have been tested at pilot-scale with specific design modification of conventional RO membrane module [47]. As one of the main service providers in FO, Oasys Water has ventured into fully integrated FO system completed with thermally regenerated ammonium carbonate draw solution.…”

Section: Forward Osmosis Membranesmentioning

confidence: 99%

Recent Progresses of Forward Osmosis Membranes Formulation and Design for Wastewater Treatment

Goh

Ismail

et al. 2019

Water

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Production of potable water or reclaimed water with higher quality are in demand to address water scarcity issues as well as to meet the expectation of stringent water quality standards. Forward osmosis (FO) provides a highly promising platform for energy-efficient membrane-based separation technology. This emerging technology has been recognized as a potential and cost-competitive alternative for many conventional wastewater treatment technologies. Motivated by its advantages over existing wastewater treatment technologies, the interest of applying FO technology for wastewater treatment has increased significantly in recent years. This article focuses on the recent developments and innovations in FO for wastewater treatment. An overview of the potential of FO in various wastewater treatment application will be first presented. The contemporary strategies used in membrane designs and fabrications as well as the efforts made to address membrane fouling are comprehensively reviewed. Finally, the challenges and future outlook of FO for wastewater treatment are highlighted.

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The effects of membrane and channel corrugations in forward osmosis membrane modules – Numerical analyses

Cited by 26 publications

References 33 publications

Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics

Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics

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

Recent Progresses of Forward Osmosis Membranes Formulation and Design for Wastewater Treatment

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