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Influence of flow rate, temperature and pressure on multiphase flows of supercritical carbon dioxide and water using multivariate partial least square regression
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.ORCID iD: 0000-0003-2445-4624
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.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
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2015 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 10, 105001Article in journal (Refereed) Published
Abstract [en]

Supercritical carbon dioxide (scCO2) is often used to replace harmful solvents and can dissolve a wide range of organic compounds. With a favorable critical point at 31 °C and 7.4 MPa, reaching above the critical point for scCO2 is fairly accessible. Because of the compressible nature of scCO2 and the large changes of viscosity and density with temperature and pressure, there is a need to determine the behavior of scCO2 in microfluidic systems. Here, the influence of how parameters such as flow rate, temperature, pressure, and flow ratio affects the length of parallel flow of water and scCO2 and the length of the created CO2 segments are investigated and modeled using multivariate data analysis for a 10 mm long double-y channel. The parallel length and segment size were observed in the laminar regime around and above the critical point of CO2. The flow ratio between the two fluids together with the flow rate influenced both the parallel length and the segment sizes, and a higher pressure resulted in shorter parallel lengths. Regarding the segment length of CO2, longer segments were a result of a higher Weber number for H2O together with a higher temperature in the channel. 

Place, publisher, year, edition, pages
2015. Vol. 25, no 10, 105001
Keyword [en]
Supercritical fluids, microfluidics, carbon dioxide, partial least square regression, principal component analysis, fluid dynamics, multiphase flow
National Category
Engineering and Technology Other Materials Engineering
URN: urn:nbn:se:uu:diva-253552DOI: 10.1088/0960-1317/25/10/105001ISI: 000366827400017OAI: diva2:815179
Swedish Research Council, 2011-5037Knut and Alice Wallenberg Foundation
Available from: 2015-05-29 Created: 2015-05-29 Last updated: 2016-01-21Bibliographically approved
In thesis
1. Microsystems for Harsh Environments
Open this publication in new window or tab >>Microsystems for Harsh Environments
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

When operating microsystems in harsh environments, many conventionally used techniques are limiting. Further, depending on if the demands arise from the environment or the conditions inside the system, different approaches have to be used. This thesis deals with the challenges encountered when microsystems are used at high pressures and high temperatures.

For microsystems operating at harsh conditions, many parameters will vary extensively with both temperature and pressure, and to maintain control, these variations needs to be well understood. Covered within this thesis is the to-date strongest membrane micropump, demonstrated to pump against back-pressures up to 13 MPa, and a gas-tight high pressure valve that manages pressures beyond 20 MPa.

With the ability to manipulate fluids at high pressures in microsystems at elevated temperatures, opportunities are created to use green solvents like supercritical fluids like CO2. To allow for a reliable and predictable operation in systems using more than one fluid, the behavior of the multiphase flow needs to be controlled. Therefore, the effect of varying temperature and pressure, as well as flow conditions were investigated for multiphase flows of CO2 and H2O around and above the critical point of CO2. Also, the influence of channel surface and geometry was investigated.

Although supercritical CO2 only requires moderate temperatures, other supercritical fluids or reactions require much higher temperatures. The study how increasing temperature affects a system, a high-temperature testbed inside an electron microscope was created.

One of the challenges for high-temperature systems is the interface towards room temperature components. To circumvent the need of wires, high temperature wireless systems were studied together with a wireless pressure sensing system operating at temperatures up to 1,000 °C for pressures up to 0.3 MPa.

To further extend the capabilities of microsystems and combine high temperatures and high pressures, it is necessary to consider that the requirements differs fundamentally. Therefore, combining high pressures and high temperatures in microsystems results in great challenges, which requires trade-offs and compromises. Here, steel and HTCC based microsystems may prove interesting alternatives for future high performance microsystems.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 50 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1263
Microsystems, harsh environments, high pressures, high temperatures, supercritical microfluidics
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
urn:nbn:se:uu:diva-253558 (URN)978-91-554-9272-4 (ISBN)
Public defence
2015-09-11, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Available from: 2015-08-19 Created: 2015-05-29 Last updated: 2015-09-07

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