IMS: Lotta Kursula

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Lotta Kursula, M.Sc.

Eißendorfer Str. 38

Building O, Room 1.015

21073 Hamburg

Phone +49 40 42878 - 3293

Mail Lotta Kursula

Research

Fine Bubbles for Biocatalytic Processes: Microscale Phenomena and Novel Applications (DFG Project Number 501131738)

Due to the high volumetric mass transfer coefficients achieved by fine bubble aeration of reactors, the gaseous phase can be utilized more efficiently compared to macroscopic aeration. Furthermore, in biocatalytic processes, the reaction yield is increasing when using fine bubble aeration. However, the exact mechanisms causing these improvements are not fully understood yet. To gather knowledge in this regard, and therefore enable process optimization, the local mass transfer phenomena are studied in the scope of the project. This includes investigations of the interactions between enzymes and the concentration boundary layer of the fine bubbles on a microscale.

Unsteady Mass Transfer in Bubble Wakes Analyzed by Lagrangian Coherent Structures in a Flat Bed Reactor

As of today, there is limited understanding of dissolved gas and liquid interactions in turbulent bubble wakes crucial for process optimization in the field of reactive bubbly flows. Lagrangian Coherent Structures (LCS) define the most attracting and repelling material lines. Computation in forward time yields most repelling material lines, whereas attracting lines are obtained in backward time. They act as transport barriers and are therefore particularly interesting for studies on transport phenomena. Finite Time Lyapunov Exponents (FTLE) provide information about material lines without restrictions on single manifolds. We reveal how Lagrangian Coherent Structures govern the transport of dissolved gas in bubble wakes.

Education

Graduate Teaching Assistant

Strömungsmechanik II (WiSe 2024/2025)
Strömungsmechanik II (WiSe 2023/2024)
Grundlagen des Technischen Zeichnens (SoSe 2023)
Einführung in CAD (WiSe 2022/2023)

Committees

Deputy member of the Examination Committee for Process Engineering (Since 04/2023)

Poster and Oral Presentations

Oral Presentations

Lotta Kursula, Sayaka Takagi, Zeynep Perçin, Felix Kexel, Paul Bubenheim, Marko Hoffmann, Andreas Liese, Koichi Terasaka and Michael Schlüter: Experimental Study of Microscopic Mass Transfer Phenomena of Single Fine Bubbles, 16th International Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering, Dresden, Germany (2024), Oral Presentation
Lotta Kursula, Christian Weiland, Zeynep Perçin, Felix Kexel, Paul Bubenheim, Marko Hoffmann, Andreas Liese, Koichi Terasaka and Michael Schlüter: Experimental Quantification of Local Counterdiffusion Effects on the Gas-Liquid Mass Transfer Performance on a Microscale, 27th International Congress of Chemical and Process Engineering, Prague, Czech Republic (2024), Oral Presentation
Lotta Kursula, Zeynep Perçin, Felix Kexel, Paul Bubenheim, Marko Hoffmann, Andreas Liese, Koichi Terasaka and Michael Schlüter: Experimental Quantification of Local Counterdiffusion Effects on the Gas-Liquid Mass Transfer Performance on a Microscale, International Symposium on Chemical Reaction Engineering, Turku, Finland (2024), Oral Presentation
Lotta Kursula, Zeynep Perçin, Marko Hoffmann, Andreas Liese, Koichi Terasaka and Michael Schlüter: Local Mass Transfer Phenomena of Fine Bubbles in Biocatalytic Processes, 11th International Conference on Multiphase Flow, Kobe, Japan (2023), Oral Presentation
Lotta Kursula, Zeynep Perçin, Jürgen Fitschen, Sebastian Hofmann, Marko Hoffmann, Andreas Liese, Koichi Terasaka and Michael Schlüter: Local Mass Transfer Phenomena of Fine Bubbles in Biocatalytic Processes, Jahrestreffen Dechema-Fachgruppen AT, GAS, MPH, PMT, Paderborn, Germany (2023), Oral Presentation

Poster Presentations

Sayaka Takagi, Lotta Kursula, Felix Kexel, Marko Hoffmann, Koichi Terasaka and Michael Schlüter: Novel Experimental Set-up for Studies of Microscopic Transport Phenomena at Gas-Liquid Interfaces, 16th International Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering, Dresden, Germany (2024), Poster Presentation
Lotta Kursula, Felix Kexel, Jürgen Fitschen, Marko Hoffmann, Michael Schlüter and Alexandra von Kameke: Unsteady Mass Transfer in Bubble Wakes Analyzed by Lagrangian Coherent Structures, FTZ 3i Talk: Conference on intelligent - industrial - innovations, HAW Hamburg, Hamburg, Germany (2022), Poster Presentation
Lotta Kursula, Felix Kexel, Jürgen Fitschen, Marko Hoffmann, Michael Schlüter and Alexandra von Kameke: Unsteady Mass Transfer in Bubble Wakes Analyzed by Lagrangian Coherent Structures, 4th International Symposium on Multiscale Multiphase Process Engineering (2022), Poster Presentation

Publications

[178608]

Title: Unsteady Mass Transfer in Bubble Wakes Analyzed by Lagrangian Coherent Structures in a Flat-Bed Reactor.

Written by: Kursula, L.; Kexel, F.; Fitschen, J.; Hoffmann, M.; Schlüter, M.; Kameke, A.v.;

in: <em>Processes</em>. (2022).

Volume: <strong>10</strong>. Number: (12),

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DOI: https://doi.org/10.3390/pr10122686

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Abstract: To increase the yield and selectivity in reactive bubbly flows, the gas-liquid interactions have to be understood in depth. In the current fundamental study, flow and concentration data of the wakes of two-dimensional bubbles in an organic solvent are obtained experimentally in a flat-bed reactor. The unsteady mass transport phenomena in these turbulent wakes of two freely rising, two-dimensional bubbles with bubble Reynolds numbers Re=949 and Re=388 are evaluated by analyzing Lagrangian Coherent Structures (LCS). To reveal how LCS govern the transport of dissolved gas in bubble wakes, and therefore affect gas-liquid reactions, LCS in two-dimensional velocity fields are computed and compared with concentration fields of dissolved gas. The analysis of backward Finite Time Lyapunov Exponent (bFTLE) fields reveals coherent fluid dynamic structures for both bubble Reynolds numbers studied. In the higher bubble Reynolds number case, two types of coherent structures are found, which hinder the mixing of the dissolved gas and the liquid bulk. Repelling LCS are found to enclose parcels transported into the vortices, and indicate thus, which fluid parcels can possibly take part in chemical reactions. Due to higher mixing, unveiled by details from the LCS and FTLE analyses, and therefore increased contact area between dissolved gas and fresh liquid, higher yields of reaction products are suggested for the lower bubble Reynolds number case in this two-dimensional study. This is contradicting the rule of thumb that mixing increases for higher bubble Reynolds numbers.

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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