Visualization of droplet condensation in membrane distillation desalination with surface modification: hydrophilicity, hydrophobicity, and wicking spacers
Name
Lienhard- visualization of droplet.pdf
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1 MB
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Checksum (MD5)
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Author(s)
Warsinger, David Elan Martin
Swaminathan, Jaichander
Morales, Lucien L.
Bertoni, Margaret M.
Lienhard, John H.
Date Issued
2017
Journal
Proceedings of the 2nd Thermal and Fluid Engineering Conference (TFEC2017)
Publisher
American Society of Thermal and Fluids Engineers (ASTFE)
Citation
Warsinger, David M. et al. "Visualization of droplet condensation in membrane distillation desalination with surface modification: hydrophilicity, hydrophobicity, and wicking spacers." Proceedings of the 2nd Thermal and Fluid Engineering Conference (TFEC2017), April 2-5 2017, Las Vegas, Nevada, USA, American Society of Thermal and Fluids Engineers (ASTFE), 2017
Version
Author's final manuscript
Abstract
Condensation performance is a key target for improving the energy efficiency of thermal desalination technologies such as air gap membrane distillation (AGMD). This study includes the first visualization of condensation in AGMD, through the use of a high conductivity, transparent sapphire condenser surface. The study examines how flow patterns are affected by several novel modifications, including varied surface hydrophobicity, module tilt angle, and gap spacer design. The experimental results were analyzed with numerical modeling. While the orientation of the mesh spacer, which holds the air gap apart, was found to have no substantial effect on the permeate production rate, the surface's hydrophobicity or hydrophilicity did result in different rates. The hydrophobic surface exhibited fewer droplets bridging the gap, more spherical droplets, and better droplet shedding. For gap sizes less than ~3 mm, the hydrophilic surface frequently had regions of water pinned around the surface itself and the plastic spacer. While the flow patterns observed were more complex than the film condensation typically used to model the process, the simplified numerical modelling yielded good agreement with the data when an adjustment factor was used to account for the gap size.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Rohsenow Kendall Heat Transfer Laboratory (Massachusetts Institute of Technology)
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DOI of Published Version
http://dl.astfe.org/conferences/tfec2017,06b3954c652539c0,3c3f287b3ebd02a5.html
