Numerical Simulation of the Mixing Time and Pathlines of Lagrangian Tracer Particles of a Stirred Tank Reactor

For optimisation of aerated stirred tank reactors (STR) both experiments and simulations are conducted for STRs of lab and industrial scale. In the past most of the consideration was done experimentally. Also an investigation of an industrial scale STR was conducted simulatively via classical CFD. The following work focusses on the simulative investigation of a lab scale STR via the Lattice-Boltzmann-Method to achieve knowledge of the mixing time in the reactor. Additionally the behaviour of Lagrangian particles is considered. By investigating the pathlines of these Lagrangian particles it is possible to determine separated areas of different mixing behaviour, called Lagrangian Coherent Structures, to get the possibility to determine e.g. compartments and to get the knowledge if process parameter adjustment would be necessary to optimise the process itself.

Figure 1: Simulated tracer concentration over four seconds after tracer injection (injection at t = 40 s)

Numerical Simulation of the Fluid Dynamics of Gas-Liquid-Flows in Structured Internals

The aim of this project is to simulate the two phase fluid flow inside of structured internals. Validation occurs by experiments. The focus is to achieve knowledge about the velocity field, pressure drop, gas hold-up and bubble size distribution. For modelling the gaseous phase population balance models seem to be an attracitve possibility.

Figure 2: Typical velocity field in a structured internal

With the achieved knowledge internals shall be designed to force the observed process into a desired direction concerning yield, selectivity, energy efficiency, etc.

Undergraduate courses:

• Fundamentals of Fluid Mechanics (Fluid Mechanics I)
  

Graduate courses:

• Fluid Mechanics in Process Engineering (Fluid Mechanics II)
• Process Design Project (Projektierungskurs), Winter term 2020/2021

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• Nicht-invasive Bestimmung und Validierung des portosystematischen Druckgradienten nach TIPS-Implantation sowie Analyse von Einflussparametern mittels numerischer Strömungssimulation (working title), Eleonora Abu Rashed, Master's Thesis (in supervision coorperation with Dr.-Ing. Marko Hoffmann and close coorperation with Dr. med. Christoph Riedel (UKE))

• Geometrieoptimierung unter Nutzung numerischer Simulation mittels Verwendung des ANSYS Adjoint Solvers, Mona Abbas Sayed Omar, Project Work (in supervision coorperation with Claas Spille, M.Sc.), March 2021

• Numerische Simulation der Fluiddynamik unter Berücksichtigung der Mischcharakteristik eines nicht-newtonschen Fluides innerhalb einer industriellen Mischapparatur, Simon Abraha, Master's Thesis, July 2020
  

• Bewertung einer neuen Methode zur nichtinvasiven Messung von dynamischen Temperaturverläufen mittels numerischer Strömungssimulation, Hanno Hagenström, Master's Thesis, Dezember 2019

• Prediction of the Mass Transfer Coefficient Based on the Eddy Cell Model for an Aerated Stirred Tank Reactor under Multiple Operating Conditions, Hendrick Jansen, Master's Thesis, November 2019

• Weiland, C.; Fitschen, J.; Hoffmann, M.; Schlüter, M.:"Numerical Simulation and Validation of the Bubble Size Distribution in an Aerated Stirred Tank Reactor", ProcessNet Jahrestreffen Mehrphasenströmungen & CFD 2021, Paderborn/virtual, poster presentation