Total water production capacity inversion phenomenon in multi-stage direct contact membrane distillation: A theoretical study

Jung Gil Lee, Ahmad S. Alsaadi, Ayman M. Karam, Lijo Francis, Sofiane Soukane, Noreddine Ghaffour

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The low thermal efficiency and low water production are among the major challenges that prevent membrane distillation (MD) process from being commercialized. In an effort to design an efficient multi-stage direct contact MD (DCMD) unit through mathematical simulation, a new phenomenon that we refer to as total water production capacity inversion (WPI) has been detected. It is represented by a decrease in the total water production beyond a number of stages or a certain module length. WPI phenomenon, which was confirmed by using two different mathematical models validated experimentally, was found to take place due to the decrease in water vapor flux across the membrane as well as the increase in heat loss by conduction as the membrane length increases. Therefore, WPI should be considered as a critical MD design-criterion, especially for large scale units. Investigations conducted for a simulated multi-stage DCMD process showed that inlet feed and permeate temperatures difference, feed and permeate flow rates, and feed salinity have different effects on WPI. The number of stages (or module length at constant width) that leads to a maximum water production has been determined for different operating parameters. Decreasing inlet feed and permeate temperatures difference, or inlet feed and permeate flow rates and increasing inlet feed temperature at constant temperature difference or inlet feed salinity cause the WPI to take place at lower number of stages. Even though the feed salinity affects negligibly the mean permeate flux, it was clearly shown that it can affect WPI. The results presented herein unveil a hidden phenomenon that is likely to occur during process scale-up procedures and should be considered by process engineers for a proper choice of system design and operating conditions.

Original languageEnglish
Pages (from-to)126-134
Number of pages9
JournalJournal of Membrane Science
Volume544
DOIs
Publication statusPublished - 1 Jan 2017

Fingerprint

Distillation
distillation
Theoretical Models
inversions
membranes
Membranes
Water
water
Salinity
salinity
temperature gradients
Temperature
flow velocity
Hot Temperature
modules
Flow rate
Fluxes
thermodynamic efficiency
Steam
Heat losses

Keywords

  • Conduction heat loss
  • DCMD module scale-up
  • Thermal equilibrium
  • Total heat flux
  • Total water production

ASJC Scopus subject areas

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

Cite this

Total water production capacity inversion phenomenon in multi-stage direct contact membrane distillation : A theoretical study. / Lee, Jung Gil; Alsaadi, Ahmad S.; Karam, Ayman M.; Francis, Lijo; Soukane, Sofiane; Ghaffour, Noreddine.

In: Journal of Membrane Science, Vol. 544, 01.01.2017, p. 126-134.

Research output: Contribution to journalArticle

Lee, Jung Gil ; Alsaadi, Ahmad S. ; Karam, Ayman M. ; Francis, Lijo ; Soukane, Sofiane ; Ghaffour, Noreddine. / Total water production capacity inversion phenomenon in multi-stage direct contact membrane distillation : A theoretical study. In: Journal of Membrane Science. 2017 ; Vol. 544. pp. 126-134.
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