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Institute of Multiphase Flows
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Institute of Multiphase Flows
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Selma Iraqi Houssaini
Felix Kexel
Lotta Kursula
Marc Maly
Timo Merbach
Nicolas Nickel
Ryan Rautenbach
Noah von Schnitzler
Christian Weiland
Christoph Wigger
IMS > Institute > Staff > Felix Kexel

Dr.-Ing. Felix Kexel

Eißendorfer Str. 38

Building O, Room 1.008

21073 Hamburg

Phone +49 40 42878 - 4663

Mail Felix Kexel

Biography

Felix Kexel studied at Hamburg University of Technology (TUHH) from 2012 to 2016 in the bachelor's program Process Engineering. From 2016 on he attended the master’s program Process Engineering at TUHH and graduated in March 2019.

After graduating, he was employed at the IMS as a research fellow starting in April 2019, working on the DFG funded priority program Reactive Bubbly Flows. In December 2023 he received his PhD with his thesis "On the Influence of Wake Structures on Competitive Chemical Reactions at Taylor Bubbles". 

From May 2023 on, Felix Kexel has been the group leader of the working group Reactive Bubbly Flows, working on topics in the field of chemical reactions in gas liquid systems.

Research

How are the different timescales of fluid dynamic mixing, mass transfer and reaction kinetics impacting the yield and selectivity of competitive-consecutive gas-liquid reactions?

Applying measuring techniques as Particle Image Velocimetry (PIV), Particle Tracking Velocimetry (PTV), Laser Induced Fluorescence (LIF) or imaging UV-VIS Spectroscopy to obtain information on velocity and concentration fields around reactive bubbles to understand the complex interplay of fluid dynamics, mass transfer and chemical reactions.

Research Projects

  • CRC 1615 SMART Reactors, Project B04: Tailored transport processes in multiphase reactors

  • Mixing structures in bubble wakes of single bubbles and bubble swarms and their influence on gas-liquid mass transfer and chemical reaction

  • I3 Junior Project in collaboration with Hannah Buchholz (IPI) and Dr.-Ing. Jürgen Fitschen funded by the TUHH: Tomographic Reconstruction of Spherical and Irregularly Shaped Bubbles for Precise Determination of the Interfacial Area (Concluded)

  • DFG Priority Project 1740 – Reactive Bubbly Flows (Concluded)

Education

Graduate courses

  • Non-Invasive measurement techniques for multiphase flows (lecture & experiments) 

Supervised Theses

  • "Design of a transparent MRI ready setup for the determination of bubble surfaces", Ole Simmering, Master thesis, in collaboration with Hannah Buchholz (IPI)

  • "Vergleich von Strömungs- und Konzentrationsfeldern in einem Flachbettreaktor mittels Particle Image Velocimetry und Laserinduzierter Fluoreszenz", Rene Weglewski, Master thesis, 2023

  • "Experimentelle Untersuchung von Konzentrations- und Strömungsfeldern im Nachlauf einer reaktiven Taylor Blase", Anahita Radmehr, Master thesis, 2023

  • "Experimentelle Untersuchung der 3–dimensionalen Strömungsstrukturen in einer Blasenströmung mittels 4D–PTV", Yara Kappes, Master thesis, 2022

  • "Taylor Bubbles in Organic Solvents", Sina Bertram, Bachelor thesis, 2022

  • "Computation of Unsteady Mass Transfer in Bubble Wakes by Means of 2D Lagrangian Analysis", Lotta Kursula, Master thesis, 2022

  • "Anwendung der Penetrationstheorie auf lokale Stofftransportprozesse an Taylor Blasen", Benjamin Rahimian, Bachelor thesis, 2022

  • "Characterization of the fluid dynamic properties of a Methanol based chemical reaction", Noah von Schnitzler, Bachelor thesis, 2021

  • "Taylor Bubble Generation Using a Solenoid Valve", Tarlan Ramazanli, Project Work 2021

  • "Detailed investigations of bubble trajectories in clean and contaminated systems", Sam Dors, Bachelor thesis, 2020

  • "Determination of mass transfer coefficients from single Taylor bubbles in contaminated systems – a study for industrial applications", Aaron Kaulbarsch, Bachelor thesis, 2019

  • "Experimentelle Analyse des Einflusses von organischen Lösemitteln auf die Hydrodynamik von Taylorblasen am Bespiel von Acetonitril", Carolin Lohmann, Bachelor thesis, 2019

Oral and Poster Presentations

Lectures

  • Kexel, F.; von Kameke, A.; Hoffmann, M.; Schlüter, M.: "On the Influence of Wake Structures on Competitive Chemical Reactions at Taylor Bubbles" ProcessNet Jahrestreffen Mehrphasenströmungen, Partikeltechnologie  & CFD 2024, Bremen, oral presentation

  • Frey, T.; Kexel, F.; Hoffmann, M.; Schlüter, M.: " Local Characterization of the mixing performance of a cascade mixer in competitive reaction systems in aqueous and organic media" ProcessNet Jahrestreffen Mischvorgänge 2024, Schopfheim, oral presentation

  • Fitschen, J.; Kexel, F.; Hofmann, S.; Kuschel, M.; Hoffmann M.; Wucherpfennig, T.; Schlüter, M.:" Hydrodynamic Characterization and Identification of Heterogeneities in Stirred Tank Reactory by Means of 4D Particle Trajectories", 11th International Conference on Multiphase Flows, Kobe, Japan, 2023, oral presentation

  • Radmehr, A; Kexel, F.; von Kameke, A.; Hoffmann, M.; Schlüter, M.: "Local Velocity Fields at Taylor Bubbles in Methanol" 11th Workshop Chemical and Biological Mico Laboratory Technology 2022, Ilmenau, 2022, oral presentation

  • Kexel, F.; von Kameke, A.; Hoffmann, M.; Schlüter, M.: "Fluid Dynamics of Taylor Bubbles in Organic Solvents" ProcessNet Jahrestreffen Mehrphasenströmungen, Mechanische Flüssigkeitsabtrennung & Zerkleinern und Klassieren 2022, virtual, 2022, oral presentation

  • Kexel, F.; von Kameke, A.; Hoffmann, M.; Schlüter, M.: "Investigation on Velocity and Concentration Fields at Taylor Bubbles in a Reactive Bubbly Flow" Dispersed Two-Phase Flows 2021, virtual, 2021, oral presentation

  • Kexel, F.; von Kameke, A.; Hoffmann, M.; Schlüter, M.: "Influence of Fluid Dynamics on the Selectivity of Competitive Consecutive Gas Liquid Reactions" 13th European Congress of Chemical Engineering (ECCE13), virtual, 2021, oral presentation

  • Kexel, F.; von Kameke, A.; Colombi, R.; Rüttinger, S.; Hoffmann, M.; Schlüter, M.: "Inverstigation of Reactive Mass Transfer Processes at Single Rising Bubbles by Means of Time-Resolved Scanning Laser Induced Fluorescence" 12th European Congress of Chemical Engineering (ECCE12), Florence, Italy, 2019, oral presentation

  • Kexel, F.; Rüttinger, S.; Kastens, S.; von Kameke, A.; Oßberger, M.; Hoffmann, M.; Schlüter, M.: "Does the wake structure in bubbly flows affect yield and selectivity of a competitive consecutive reaction? – A Taylor-Bubble study" ProcessNet Jahrestreffen Reaktionstechnik & Mehrphasenströmungen 2019, Würzburg, 2019, oral presentation

Poster Presentations

  • Merbach,T.; Mockus, B.; Minamitani, K.; Kexel, F.; Schlüter, M.; Valluri, P.; Hayashi, K.; Tomiyama, A.:" Development of a Correlation for the Terminal Rising Velocity for 2D-Bubbles in Unconfined Domain", 11th International Conference on Multiphase Flows, Kobe, Japan, 2023, poster presentation

  • Kexel, F.; Bertram, S.; Merbach, T.; von Kameke, A.; Hoffmann, M.; Tomiyama, A.; Schlüter, M.: "Influence of Taylor Bubble Shapes on Wake Structures", 4th International Symposium on Multiscale Multiphase Process Engineering, Berlin, 2022, poster presentation

  • Kexel, F.; von Kameke, A; Hoffmann, M.; Schlüter, M.: "Optimization of Chemical Reactions with Tailored Flow Strucures" ProcessNet Jahrestreffen Reaktionstechnik 2021, virtual, 2021, poster presentation

  • Kexel, F.; von Kameke, A; Hoffmann, M.; Schlüter, M.: "Investigation of the influence of fluid dynamics on the selectivity of fast gas-liquid reactions by means of high speed imaging UV/VIS spectroscopy at a Taylor bubble setup" ProcessNet Jahrestreffen Mehrphasenströmungen & CFD 2021, virtual, 2021, poster presentation

Publications

[158051]
Title: Experimental Investigation of Reactive Bubbly Flows—Influence of Boundary Layer Dynamics on Mass Transfer and Chemical Reactions. <em>Reacticve Bubbly Flows</em>
Written by: Kexel, F.; Kastens, S.; Timmermann, J.; Kameke, A. v.; Schlüter, M.
in: (2021).
Volume: Number:
on pages: 267–307
Chapter:
Editor: In Schlüter, M.; Bothe, D.; Herres-Pawlis, S.; Nieken, U. (Eds.)
Publisher: Springer:
Series:
Address:
Edition:
ISBN: 978-3-030-72361-3
how published:
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Type:
DOI: https://doi.org/10.1007/978-3-030-72361-3_12
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ARXIVID:
PMID:

Note:

Abstract: Bubbly flows are extensively used processes in the chemical industry. Since the complex interaction of fluid dynamics, mass transfer and chemical reaction is not yet fully understood, a reliable prediction of yield and selectivity is not possible. Within this work different benchmark experiments are developed, allowing the investigation of the interplay of mixing and chemical reactions. For precise predictions of the chemical process, a detailed knowledge about the intrinsic kinetics is essential. Therefore, the guiding measure “SuperFocus Mixer” (SFM) has been developed and successfully tested by determining the kinetics of a model system and of the oxidation of a temperature sensitive copper complex. In a second step, the identified reaction is transferred into the Taylor bubble setup, marking the second benchmark system. Here the effect of mixing on the production of the products in consecutive and competitive-consecutive reaction is investigated. The conducted experiments show significant influence of the mixing intensity on the production of the first reaction product MNIC and the side product DNIC, favoring the first product at intensified mixing. Finally, the local mass transfer at freely ascending bubbles superimposed by a chemical reaction is determined by applying planar-LIF, and the influence of bubble–bubble bouncing is quantified. In addition, a novel method, the Time Resolved Scanning-LaserInduced Fluorescence (TRS-LIF) for the visualization of 3D concentration fields, is introduced and tested at single rising oxygen bubbles.

TU Hamburg
Institute of Multiphase Flows
Eißendorfer Straße 38
21073 Hamburg
E-mail : info@ims-tuhh.de
Phone : +49 (0) 40 42878 - 3252
Fax : +49 (0) 40 42731 - 4609
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