Effect of inner-layer thermal conductivity on flux enhancement of dual-layer hollow fiber membranes in direct contact membrane distillation

Minglue Su, May May Teoh, Kai Yu Wang, Jincai Su, Tai-Shung Chung*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

84 Scopus citations

Abstract

The thermal conductivity of hydrophobic/hydrophilic hollow fiber membranes is a key factor affecting flux in direct contact membrane distillation processes. In this paper both experimental work and mathematical modeling are performed to investigate the effect of the hydrophilic layer's thermal conductivity on vapor flux. Modeling predicts a significant increase in vapor flux from 31.4 to 78.5kgm-2h-1 under the feed and distillate temperatures of 80 and 20°C, respectively, when the thermal conductivity of the inner hydrophilic layer is varied from 0.2 to 1.4Wm-1K-1. To investigate this experimentally, graphite particles and multiwall carbon nanotubes (MWNT) were embedded for the first time into the hollow fiber hydrophilic layer to improve its thermal conductivity. It was found that incorporating graphite alone led to only a minor improvement in thermal conductivity. However, by incorporating both graphite and MWNT the thermal conductivity was increased from 0.59 to 1.30Wm-1K-1. This improvement is attributed to the conducting network formed by the MWNT which bridges the polymer nodules. The improved thermal conductivity led to a significant increase in vapor flux from 41.2 to 66.9kgm-2h-1, under the inlet feed and distillate temperatures of 80.4 and 15.3°C, respectively, in general agreement with the mathematical modeling.

Original languageEnglish (US)
Pages (from-to)278-289
Number of pages12
JournalJournal of Membrane Science
Volume364
Issue number1-2
DOIs
StatePublished - Nov 15 2010

Keywords

  • Dual-layer hollow fiber membranes
  • Hydrophobic-hydrophilic
  • Membrane distillation
  • Multiwall carbon nanotubes
  • Thermal conductivity

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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