The experimental characterization of membrane behavior in two-phase gas extraction Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/v979v562s

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  • Understanding the behavior of hydrophobic membranes is important for applications where separating a gas from a liquid-gas mixture is beneficial. For example, in-situ vapor extraction can be used in microscale heat sinks to improve heat transfer and flow stability. In this study, gas is experimentally evaluated flowing through flexible polytetrafluoroethylene nanofiber membranes. The gas is extracted from liquid-gas combinations of liquid water, water vapor and air. For single-phase flow such as superheated vapor and air, an applied pressure difference across the membrane results in structural changes affecting properties including the membrane thickness, which restricts the flow rate. Two existing models predicting fluid transport in porous media are found to be insufficient to predict gas extraction flow rates from two-phase mixtures, even when accounting for membrane compaction and a proposed estimated reduced extraction area. The proposed estimated extraction area insufficiently accounts for bubble kinetic energy, bubble dynamics and the existence of thin liquid films. The thin liquid film must be ruptured to open membrane pores to extract the gas in the bubbles. At greater applied pressure differences, film rupture and three phase contact are accelerated and bubbles are extracted more quickly resulting in a reduced gas-membrane contact area. If the bubbles have too much energy associated with them, it may take multiple collisions with the membrane for the bubbles to establish stable three phase contact. To account for the hydrodynamics near the membrane surface, empirical parameters are developed as a function of thermophysical properties of the mixture near the membrane and the applied pressure differences across the membrane. In the case of liquid-air mixtures with high void fractions, bubbles are not completely extracted due to hydrodynamics near the membrane surface. For saturated liquid-vapor studies, full vapor extraction is achieved even at high void fractions due to different bubble energy and behavior than the liquid-air studies. One implication with liquid-vapor mixtures is that changes in the membrane flow resistance can be induced if the extraction vacuum pressure is cycled.
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  • description.provenance : Rejected by Julie Kurtz(julie.kurtz@oregonstate.edu), reason: Your ScholarsArchive@OSU submission has been rejected because you attached a CC0 or Public Domain License to your work. These licenses mean that you have "dedicated the work to the public domain by waiving all of your rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. Others can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission." We strongly suggest that you don't attach either of these licenses. We're assuming you probably meant to add a Creative Commons license to your work so that others could use it, but you intended to retain your copyrights. Please re-submit* your work and choose "Creative Commons License" from the License Type drop down box. You'll then be asked two questions about how you want people to use your work. You can also choose "No Creative Commons License". *To re-submit your work, log into ScholarsArchive@OSU. Your rejected submission will be in your Submissions & Tasks work file. You can just resume the submission. All your information will still be in the form; you need to change only the CC License page. If you have any questions or concerns, please contact Sue Kunda: sue.kunda@oregonstate.edu OR 541-737-7262. on 2013-08-27T15:59:28Z (GMT)
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  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2013-09-05T20:28:57Z (GMT) No. of bitstreams: 2 license_rdf: 1223 bytes, checksum: d127a3413712d6c6e962d5d436c463fc (MD5) CappelloNicholasC2014.pdf: 30128642 bytes, checksum: 1788b9fbf242f19e3cdd3677f3beb616 (MD5)

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