Phase Transitions in Vycor Studied by Optical Techniques

Dupuis, Yannick

Phase Transitions in Vycor Studied by Optical Techniques

Dateien

Dupuis_0-410650.pdfGröße: 9.66 MBDownloads: 305

Datum

2014

Open Access-Veröffentlichung

Open Access Green

Sammlungen

Physik

Publikationstyp

Bachelorarbeit

Publikationsstatus

Published

Zusammenfassung

Wetting fluids condense in porous media for pressures smaller than their saturated vapor pressure. Unlike in bulk conditions, the transition from gas to liquid is strongly hysteretic. Drying the material requires to reduce the pressure well below the condensation pressure. Understanding the origin of this hysteresis, and the underlying evaporation mechanisms, is an active field of research.
In my Bachelor Thesis I examine this hysteretic cycle for n-hexane in the porous environment of Vycor. For that purpose, I built a new experimental set-up which allows simultaneously to obtain precise isotherms and to optically probe the sample. Specific attention was brought on the kink of the evaporation branch and small-angle light scattering was used to measure the fluid correlations at this point. The results show a recurring heterogeneity in the sample upon evaporation.

Zusammenfassung in einer weiteren Sprache

Benetzende Flüssigkeiten kondensieren in einem porösen Medium unterhalb des Dampfdrucks. Anders als in einer freien Umgebung, beschreibt die Kondensation darin eine Hysterese. Um das Material zu trocknen, muss der Druck weit unter den Kondensationsdruck gesenkt werden. Den Ursprung dieser Hysterese und den ihr zugrunde liegende Verdampfungsmechanismus zu verstehen, ist ein aktives Forschungsgebiet.
Meine Bachelorarbeit befasst sich mit diesem Hysteresezyklus für n-Hexane in dem porösen Material Vycor. Dafür habe ich einen experimentellen Aufbau erstellt, der es ermöglicht genaue Isothermen zu messen, sowie die Probe optisch zu untersuchen. Ein besonderes Augenmerk habe ich auf den Knick auf der Verdampfungskurve gerichtet. An dieser Stelle habe ich Kleinwinkelstreuung angewandt, um die Korrelationen in dem Fluid zu untersuchen. Das Ergebnis ist eine wiederkehrende Heterogenität in der Probe bei Verdampfung.

Fachgebiet (DDC)

530 Physik

Schlagwörter

vycor, hexane, condensation, evaporation, percolation, optical scattering

Zitieren

ISO 690

DUPUIS, Yannick, 2014. Phase Transitions in Vycor Studied by Optical Techniques [Bachelor thesis]. Konstanz: Universität

BibTex

@mastersthesis{Dupuis2014Phase-39304,
  year={2014},
  title={Phase Transitions in Vycor Studied by Optical Techniques},
  address={Konstanz},
  school={Universität},
  author={Dupuis, Yannick}
}

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Hochschulschriftenvermerk

Konstanz, Universität, Bachelorarbeit, 2014

Universitätsbibliographie

Nein