Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations

As an extended exploration of process enhancing strategies, nine modified hollow fiber modules with various turbulence promoters were designed and modeled using a two dimensional computational fluid dynamic (CFD) heat-transfer model to investigate their potential in improving heat transfer and module p...

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Main Authors: Yang, Xing, Yu, Hui, Wang, Rong, Fane, Anthony Gordon
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2013
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Online Access:https://hdl.handle.net/10356/100900
http://hdl.handle.net/10220/10023
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1009002020-03-07T11:43:47Z Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations Yang, Xing Yu, Hui Wang, Rong Fane, Anthony Gordon School of Civil and Environmental Engineering Singapore Membrane Technology Centre DRNTU::Engineering::Environmental engineering::Water treatment As an extended exploration of process enhancing strategies, nine modified hollow fiber modules with various turbulence promoters were designed and modeled using a two dimensional computational fluid dynamic (CFD) heat-transfer model to investigate their potential in improving heat transfer and module performance for a shell-side feed direct contact membrane distillation (DCMD) system. With the aids of turbulence promoters, the feed heat-transfer coefficient hf of the modified modules generally showed much slower decreasing trends along the fiber length compared to the original (unmodified) module. A 6-fold hf enhancement could be achieved by a modified module with annular baffles and floating round spacers. Consistently, the temperature polarization coefficient (TPC) and mass flux distribution curves of these modified modules presented increasing trends and gained an optimal improvement of 57% and 74%, respectively. With the local flow fields and temperature profiles visualized in CFD simulations, it was confirmed that an appropriate selection of turbulence promoters could promote intense secondary flows and radial mixing to improve the shell-side hydrodynamics and enhance heat transfer. Moreover, an increase of flow velocity was used and compared as a conventional approach to improve hydrodynamics. It was found that a well-designed module could bring more significant enhancement for a liquid-boundary layer dominant heat-transfer process. Finally, the hydraulic energy consumption (HEC) caused by the insertion of turbulence promoters or the increase of circulating velocity was compared. Configurations with attached quad spacers or floating round spacers achieved a good compromise between enhanced permeation fluxes and modest HECs. Overall, the TPC decreases with increasing MD coefficient (C) values and operating temperatures; while the thermal efficiency increases dramatically with increasing C and operating temperatures in a MD system. Accepted version 2013-05-30T04:33:51Z 2019-12-06T20:30:17Z 2013-05-30T04:33:51Z 2019-12-06T20:30:17Z 2012 2012 Journal Article Yang, X., Yu, H., Wang, R., & Fane, A. G. (2012). Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations. Journal of Membrane Science, 415-416, 758-769. 0376-7388 https://hdl.handle.net/10356/100900 http://hdl.handle.net/10220/10023 10.1016/j.memsci.2012.05.067 172996 en Journal of membrane science © 2012 Elsevier. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of Membrane Science, Elsevier B.V. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [DOI: http://dx.doi.org/10.1016/j.memsci.2012.05.067]. 12 p. application/pdf
institution Nanyang Technological University
building NTU Library
country Singapore
collection DR-NTU
language English
topic DRNTU::Engineering::Environmental engineering::Water treatment
spellingShingle DRNTU::Engineering::Environmental engineering::Water treatment
Yang, Xing
Yu, Hui
Wang, Rong
Fane, Anthony Gordon
Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations
description As an extended exploration of process enhancing strategies, nine modified hollow fiber modules with various turbulence promoters were designed and modeled using a two dimensional computational fluid dynamic (CFD) heat-transfer model to investigate their potential in improving heat transfer and module performance for a shell-side feed direct contact membrane distillation (DCMD) system. With the aids of turbulence promoters, the feed heat-transfer coefficient hf of the modified modules generally showed much slower decreasing trends along the fiber length compared to the original (unmodified) module. A 6-fold hf enhancement could be achieved by a modified module with annular baffles and floating round spacers. Consistently, the temperature polarization coefficient (TPC) and mass flux distribution curves of these modified modules presented increasing trends and gained an optimal improvement of 57% and 74%, respectively. With the local flow fields and temperature profiles visualized in CFD simulations, it was confirmed that an appropriate selection of turbulence promoters could promote intense secondary flows and radial mixing to improve the shell-side hydrodynamics and enhance heat transfer. Moreover, an increase of flow velocity was used and compared as a conventional approach to improve hydrodynamics. It was found that a well-designed module could bring more significant enhancement for a liquid-boundary layer dominant heat-transfer process. Finally, the hydraulic energy consumption (HEC) caused by the insertion of turbulence promoters or the increase of circulating velocity was compared. Configurations with attached quad spacers or floating round spacers achieved a good compromise between enhanced permeation fluxes and modest HECs. Overall, the TPC decreases with increasing MD coefficient (C) values and operating temperatures; while the thermal efficiency increases dramatically with increasing C and operating temperatures in a MD system.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Yang, Xing
Yu, Hui
Wang, Rong
Fane, Anthony Gordon
format Article
author Yang, Xing
Yu, Hui
Wang, Rong
Fane, Anthony Gordon
author_sort Yang, Xing
title Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations
title_short Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations
title_full Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations
title_fullStr Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations
title_full_unstemmed Analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (CFD) simulations
title_sort analysis of the effect of turbulence promoters in hollow fiber membrane distillation modules by computational fluid dynamic (cfd) simulations
publishDate 2013
url https://hdl.handle.net/10356/100900
http://hdl.handle.net/10220/10023
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