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Fluid behavior of supercritical carbon dioxide with water in a double-Y-channel microfluidic chip
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
KTH. (Fluid mechanics)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
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2014 (English)In: Microfluidics and Nanofluidics, ISSN 1613-4982, E-ISSN 1613-4990, Vol. 17, no 6, 1105-1112 p.Article in journal (Refereed) Published
Abstract [en]

The use of supercritical carbon dioxide (scCO2) as an apolar solvent has been known for decades. It offers a greener approach than, e.g., hexane or chloroform, when such solvents are needed. The use of scCO2 in microsystems, however, has only recently started to attract attention. In microfluidics, the flow characteristics need to be known to be able to successfully design such components and systems. As supercritical fluids exhibit the exciting combination of low viscosity, high density, and high diffusion rates, the fluidic behavior is not directly transferrable from aqueous systems. In this paper, three flow regimes in the scCO2–liquid water two-phase microfluidic system have been mapped. The effect of both total flow rate and relative flow rate on the flow regime is evaluated. Furthermore, the droplet dynamics at the bifurcating exit channel are analyzed at different flow rates. Due to the low viscosity of scCO2, segmented flows were observed even at fairly high flow rates. Furthermore, the carbon dioxide droplet behavior exhibited a clear dependence on both flow rate and droplet length.

Place, publisher, year, edition, pages
2014. Vol. 17, no 6, 1105-1112 p.
Keyword [en]
Two-phase flow, segmented flow, parallel flow, wavy flow droplet dynamics
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
URN: urn:nbn:se:uu:diva-207265DOI: 10.1007/s10404-014-1399-6ISI: 000345389900014OAI: oai:DiVA.org:uu-207265DiVA: diva2:655224
Funder
Swedish Research Council
Available from: 2013-10-10 Created: 2013-09-11 Last updated: 2017-12-06Bibliographically approved
In thesis
1. High-Pressure Microfluidics
Open this publication in new window or tab >>High-Pressure Microfluidics
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, some fundamentals and possible applications of high-pressure microfluidics have been explored. Furthermore, handling fluids at high pressures has been addressed, specifically by creating and characterizing strong microvalves and pumps.

A variety of microstructuring techniques was used to realize these microfluidic devices, e.g., etching, lithography, and bonding. To be able to handle high pressures, the valves and pumps need to be strong. This necessitates a strong actuator material. In this thesis, the material of choice is paraffin wax.

A new way of latching paraffin-actuated microvalves into either closed or open position has been developed, using the low thermal conductivity of paraffin to create large thermal gradients within a microactuator. This allows for long open and closed times without power consumption.

In addition, three types of paraffin-actuated pumps are presented: A peristaltic high-pressure pump with integrated temperature control, a microdispensing pump with high repeatability, and a pump system with two pumps working with an offset to reduce flow irregularities. Furthermore, the fundamental behavior of paraffin as a microactuator material has been explored by finite element modeling.

One possibility that arises with high-pressure microfluidics, is the utilization of supercritical fluids for different applications. The unique combination of material properties found in supercritical fluids yields them interesting applications in, e.g., extraction and cleaning. In an attempt to understand the microfluidic behavior of supercritical carbon dioxide, the two-phase flow, with liquid water as the second phase, in a microchannel has been studied and mapped with respect to both flow regime and droplet behavior at a bi-furcating outlet.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 53 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1085
Keyword
phase change, actuator, valve, pump, supercritical fluid
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-208915 (URN)978-91-554-8773-7 (ISBN)
Public defence
2013-11-29, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, 751 21, Uppsala, 09:30 (English)
Opponent
Supervisors
Funder
Swedish Research Council
Available from: 2013-11-07 Created: 2013-10-10 Last updated: 2014-01-23

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Ogden, SamBodén, RogerWu, ZhigangHjort, Klas

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