Membrane distillation. II. Direct contact MD

Lawson, Kevin W.; Lloyd, Douglas R.

doi:10.1016/0376-7388(96)00141-x

Cited by 291 publications

(152 citation statements)

References 17 publications

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“…The dominating mechanism is generally determined by the Knudsen number (K n ), which is defined by (11) 6 where λ is the mean free path of the transferred gas molecule and d pore is the mean pore diameter of the membrane (often in the range of 0.1~1.0 µm). The mean free path of a gas can be expressed by (12) where k B is the Boltzmann constant -1.38×10 -23 J/K; ζ is the collision diameter of the molecule (2.641Å for water vapor); P is the pressure in Pa [12].…”

Section: Mass Transfer Mechanisms Through a Porous Membranementioning

confidence: 99%

“…(11) and (13), Knudsen numbers of some typical porous membranes for MD at different temperatures are summarized in Table 1. It can be seen that Knudsen number increases gradually as evaporation temperature rises, but drops significantly as the membrane pore size increases.…”

Section: Mass Transfer Mechanisms Through a Porous Membranementioning

confidence: 99%

“…Heat and mass transfer in MD, particularly in DCMD, have been intensively studied since the 1980s [1,4,5,[9][10][11][12][13][14][15][16]. However, less than 5% of MD publications deal with SGMD [5].…”

Section: Introductionmentioning

confidence: 99%

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Condensation studies in membrane evaporation and sweeping gas membrane distillation

Zhao

Feron

Xie

et al. 2014

Journal of Membrane Science

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Vapor transfer is an important phenomenon in various thermally driven membrane processes such as membrane distillation (MD), membrane evaporation and membrane condensation. In this study, we explore the mass transfer phenomena in sweeping gas membrane distillation (SGMD) by systematically investigating the effects of operational parameters on the process performance. It is found that mass transfer in SGMD is principally determined by both the evaporation temperature and the sweeping gas flow rate, and is significantly influenced by the operational parameters (i.e. fluid velocities) through multiple effects, including the boundary layer effect on both sides of the membrane, and the temperature polarization effect. We also prove that at low gas flow rates (i.e. insufficient gas vapor-holding capacity) the sweeping gas becomes saturated and water vapor forms droplets due to condensation on the gas side of the membrane. To the best of our knowledge, this is the first study reporting the interesting mass transfer phenomena in terms of vapor condensation and droplet re-evaporation in SGMD, which are of great significance for the heat and mass transfer in many thermally driven membrane processes using stripping gas.

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Section: Mass Transfer Mechanisms Through a Porous Membranementioning

confidence: 99%

Section: Mass Transfer Mechanisms Through a Porous Membranementioning

confidence: 99%

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Condensation studies in membrane evaporation and sweeping gas membrane distillation

Zhao

Feron

Xie

et al. 2014

Journal of Membrane Science

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“…MD is a thermally driven process based on a vapour pressure gradient across a hydrophobic membrane [1,] [2]. The most commonly used configuration is Direct Contact Membrane Distillation (DCMD) in which a hydrophobic membrane acts as a barrier between a feed of hot seawater or brackish water and a permeate of cold freshwater (Figure 1Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…Firstly, in order to achieve efficient vapour transport from the hot to the cold side, the membrane needs to be highly porous and as thin as possible [4][5]. Secondly, the pores need to be large enough to facilitate vapour transport, while having sufficiently small dimensions to avoid membrane wetting and formation of a direct liquid bridge between the feed and the permeate sides [2][3][4][5][6]. Most previous studies have investigated membranes formed from Poly(propylene) (PP), Poly(vinylidene-fluoride) (PVDF) and Poly(tetrafluoroethylene) (PTFE) [7].…”

Section: Introductionmentioning

confidence: 99%

Characterization and evaluation of carbon nanotube Bucky-Paper membranes for direct contact membrane distillation

Dumée

Sears

Schütz

et al. 2010

Journal of Membrane Science

305

130

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Self-supporting carbon nanotube (CNT) Bucky-Papers have unique structural and surface properties which can be utilised in many applications. In this work we characterised pure selfsupporting CNT membranes, where CNTs were held together only by Van der Waals forces, and evaluated their potential and performance in direct contact membrane distillation. The membranes were found to be highly hydrophobic (contact angle of 113°), highly porous (90%), and to exhibit a thermal conductivity of 2.7 kW/m 2 •h. We demonstrate, as a proof of concept, that self-supporting CNT Bucky-Paper membranes can be used for desalination in a direct contact membrane distillation setup with 99% salt rejection and a flux rate of ~12 kg/m 2 *h at a water vapour partial pressure difference of 22.7kPa. Ageing of the membranes by delamination, factor limiting their performance, is also reported but work is currently done to address this issue by investigating composite material structures.

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