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@PHDTHESIS{Flake:978118,
author = {Flake, Carsten},
othercontributors = {Bardow, André and Koß, Hans-Jürgen and Jupke, Andreas},
title = {{A}utomated measurement, modeling and interpretation of
diffusion coefficients in aqueous multicomponent mixtures;
1. {A}uflage},
volume = {46},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {Wissenschaftsverlag Mainz GmbH},
reportid = {RWTH-2024-01145},
isbn = {978-3-95886-516-7},
series = {Aachener Beiträge zur technischen Thermodynamik},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Druckausgabe: 2024. - Auch veröffentlicht auf dem
Publikationsserver der RWTH Aachen University; Dissertation,
RWTH Aachen University, 2023},
abstract = {Accurate models for transport properties are essential for
the operation and design of chemical processes. However,
only approximate and empirical models for liquids exist.
Experimental data to develop and test these models are
lacking. This work automates a measurement technique using
microfluidics and Raman microspectroscopy to measure
diffusion coefficients in liquid multicomponent mixtures
efficiently. Automation replaces the tedious and error-prone
manual sample preparation. Thus, an experiment including
sample preparation requires only one hour in total. The
automation also enables continuous measurements without
interruption. The automated setup was employed to measure
diffusion coefficients for the non-ideal system
water-acetone-toluene. Water has a weak Raman signal, which
is highly sensitive to the ambient conditions of the water.
New methods for evaluating spectra with water were developed
to still quantify even low water contents with Raman
spectroscopy. A new approach was tested with the measured
diffusion data to predict diffusion coefficients. Often,
Gibbs excess energy models calculate the wrong thermodynamic
factors to predict diffusion coefficients. Usually, these
models are parametrized with phase equilibrium data. In the
new approach, the parameters of an excess enthalpy model are
estimated with binary diffusion data. The prediction of
ternary diffusion data was improved compared to
parameterization with liquid-liquid equilibrium (LLE) data.
In addition, the model parameterized with binary diffusion
data can predict the ternary miscibility gap. Measurement
and prediction result in negative main diffusion
coefficients. The existence of negative main diffusion
coefficients is questioned in the recent literature. To
support the finding, necessary conditions are derived for
the negative main diffusion coefficients. The derived
conditions reveal that negative main diffusion coefficients
are possible but rare and only appear in highly non-ideal
systems.},
cin = {412110},
ddc = {620},
cid = {$I:(DE-82)412110_20140620$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2024-01145},
url = {https://publications.rwth-aachen.de/record/978118},
}
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