Cargando…

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

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...

Descripción completa

Detalles Bibliográficos
Autores principales: Charlton, Alexander J., Lian, Boyue, Blandin, Gaetan, Leslie, Greg, Le-Clech, Pierre
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281554/
https://www.ncbi.nlm.nih.gov/pubmed/32466224
http://dx.doi.org/10.3390/membranes10050111
_version_ 1783543947614748672
author Charlton, Alexander J.
Lian, Boyue
Blandin, Gaetan
Leslie, Greg
Le-Clech, Pierre
author_facet Charlton, Alexander J.
Lian, Boyue
Blandin, Gaetan
Leslie, Greg
Le-Clech, Pierre
author_sort Charlton, Alexander J.
collection PubMed
description 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.
format Online
Article
Text
id pubmed-7281554
institution National Center for Biotechnology Information
language English
publishDate 2020
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-72815542020-06-17 Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics Charlton, Alexander J. Lian, Boyue Blandin, Gaetan Leslie, Greg Le-Clech, Pierre Membranes (Basel) Article 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. MDPI 2020-05-25 /pmc/articles/PMC7281554/ /pubmed/32466224 http://dx.doi.org/10.3390/membranes10050111 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Charlton, Alexander J.
Lian, Boyue
Blandin, Gaetan
Leslie, Greg
Le-Clech, Pierre
Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics
title Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics
title_full Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics
title_fullStr Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics
title_full_unstemmed Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics
title_short Impact of FO Operating Pressure and Membrane Tensile Strength on Draw-Channel Geometry and Resulting Hydrodynamics
title_sort impact of fo operating pressure and membrane tensile strength on draw-channel geometry and resulting hydrodynamics
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281554/
https://www.ncbi.nlm.nih.gov/pubmed/32466224
http://dx.doi.org/10.3390/membranes10050111
work_keys_str_mv AT charltonalexanderj impactoffooperatingpressureandmembranetensilestrengthondrawchannelgeometryandresultinghydrodynamics
AT lianboyue impactoffooperatingpressureandmembranetensilestrengthondrawchannelgeometryandresultinghydrodynamics
AT blandingaetan impactoffooperatingpressureandmembranetensilestrengthondrawchannelgeometryandresultinghydrodynamics
AT lesliegreg impactoffooperatingpressureandmembranetensilestrengthondrawchannelgeometryandresultinghydrodynamics
AT leclechpierre impactoffooperatingpressureandmembranetensilestrengthondrawchannelgeometryandresultinghydrodynamics