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@PHDTHESIS{Grtz:1017302,
author = {Görtz, Jonas Tim},
othercontributors = {Jupke, Andreas and Hlawitschka, Mark},
title = {{E}xperimental and model-based study of gas-liquid-solid
flows in p{H}-shift electrolyzers},
volume = {17},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2025-07292},
series = {Aachener Verfahrenstechnik - Fluidverfahrenstechnik -
Dissertationen},
pages = {1 Online-Ressource : Illustrationen},
year = {2025},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2025},
abstract = {In the context of the circular economy, electrochemical pH
shift techniques offer a promising alternative to
conventional pH management methods that rely on additives.
The transition away from fossil carbon sources leads to pH
management playing a central role in processes such as
biotechnological production and recycling processes for
carboxylic acids, as aqueous streams require processing. The
properties of the different acid species, which depend on
the pH value, are specifically utilized to enable their
separation. For example, electrochemical crystallization
takes advantage of the lower solubility of the fully
protonated acid species to perform reactive pH shift
crystallization. This work presents a detailed study of
fluid dynamics in electrochemical separation units. For this
purpose, the size and velocity of electrolytically generated
oxygen and hydrogen gas bubbles and the spatially resolved,
qualitative flow of the electrolyte are measured
experimentally. For this purpose, a specially developed
semi-transparent electrolyzer is used, which provides new
insights into the gas-liquid flow. Next, based on the state
of the art, a new Euler-Lagrangian model for the simulation
of the fluid dynamics of the gas-liquid flow is proposed,
which depicts the expansion of the gas bubble curtain
through bubble-bubble collisions. For this implemented
model, suitable parameters, e.g., grid size, drag
coefficient, and collision model, are selected through a
sensitivity study. These simulation parameters are then used
to simulate the novel electrolysis apparatus, and the model
is validated with experimental data. Finally, the model can
be used to analyze a new prototype for the electrochemical
crystallization of carboxylic acids. Here, the influence of
different current densities and electrolyte volume flows on
the flow profile and spatial distribution of the gas bubbles
can be investigated. Furthermore, the acid species
concentration, pH, and supersaturation profiles can be
determined by simulating the anodic and dissociation
reactions. This model-based analysis enables the
identification of dead zones and the study of different
electrode-membrane gaps, quantifying their influence on the
maximum local supersaturation. In the future, the
model-based analysis established in this work enables the
evaluation and development of new prototype designs for
electrochemical crystallization.},
cin = {416310},
ddc = {620},
cid = {$I:(DE-82)416310_20151215$},
pnm = {BioSC - Bioeconomy Science Center (BioSC) /
$BioökonomieREVIER_INNO:$ Entwicklung der Modellregion
BioökonomieREVIER Rheinland, TP A (031B0918A) / BMBF
031B1135B - Modellregion, BioRevierPLUS: InBio,
Innovationscluster Integrierte Bioraffinerie, TP2
(031B1135B)},
pid = {G:(DE-Juel1)BioSC / G:(BMBF)031B0918A / G:(BMBF)031B1135B},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2025-07292},
url = {https://publications.rwth-aachen.de/record/1017302},
}
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