Practical trainings, student assistants and theses

Geometric characterization of wire mesh mist eliminators (Id 358)

Student practical training / Bachelor theses / Master theses / Diploma theses / Student Assistant / Compulsory internship / Volunteer internship

Foto: Mist eliminator in distillation columns ©Copyright: Alexander DößThermal separation processes (e.g. distillation) are key basic operations in process engineering plants. The mass transfer is thus dependent on intensive counterflow interaction between the vapor and the liquid. The resulting turbulent flow causes droplets to be torn from the liquid phase by the vapor phase. This reduces the separation efficiency (energy efficiency and product quality) of the process. Simultaneously, droplets carried over to downstream equipment lead to corrosion, polymerization or fouling and increase component maintenance requirements.
For this reason, wire mesh mist eliminators are frequently used in practice. These separate entrained droplets as they pass through the close-meshed wire mesh. Characterization of their separation efficiency, capacity and pressure drop are essential for design and application. The focus of the work is the experimental determination and mathematical description of the pressure drop for knitted wire mesh separators as a function of their geometric properties.

Department: Experimental Thermal Fluid Dynamics

Contact: Döß, Alexander

Requirements

  • Background in process engineering, chemical engineering, mechanical engineering or related disciplines.
  • Interest in experimental work
  • Independent and result-oriented working
  • Safe handling of MS Office software
  • Confident knowledge of German or English language

Conditions

  • Work in a multidisciplinary team
  • Remuneration according to HZDR-internal tariff
  • Scientific excellence and extensive opportunities for professional networking
  • Start from November 2022 or earlier

Online application

Please apply online: english / german

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Numerical simulation of particles in rising gas bubbles (Id 356)

Student practical training

The separation of aerosol particles by a moving gas-liquid fluidic interface is central to a wide variety of industrial and natural applications, among which stand out air purification systems and precipitation scavenging. The particle size significantly affects the separation rate. The diffusion of particles in the nanometer range is largely dominated by molecular diffusion. In this regime, predictive models accurately estimate the separation rates. Model inaccuracy increases, however, significantly when the particle size ranges from 0.1 μm to 2.5 μm. In this impaction-dominated regime, the complex interplay between the flow dynamics on both sides of the fluidic interface and the particle inertia makes it difficult to develop suitable models.
In this work, the student will numerically investigate whether enforcing bubble deformation into a non-spherical shape leads to a higher deposition rate, hereby making the particle separation process more efficient. The results will lead to the development of an improved and reliable separation model accounting for the deformation of the fluidic interface and the associated flow changes.

Department: Experimental Thermal Fluid Dynamics

Contact: Maestri, Rhandrey, Dr. Lecrivain, Gregory

Requirements

  • General interest in fluid mechanics
  • Preliminary experience in code development (C++) is desirable
  • Good written and oral communication skills in either English or German

Conditions

  • Either an immediate start or a start in 2022 is possible
  • Duration of the internship is anticipated to be 6 months but can be modified according to study regulations
  • Remuneration according to HZDR internal regulations

Online application

Please apply online: english / german

Druckversion


Development of a numerical model for the simulation of aerosol spread (Id 349)

Student practical training / Master theses / Diploma theses / Volunteer internship

As part of the CORAERO joint project (Airborne Transmission of SARS Coronavirus - From Fundamental Science to Efficient Air Cleaning Systems) funded by the Helmholtz Association, we are working on scientific issues relating to the formation of virus-laden aerosols, their thermodynamics and propagation in rooms, as well as strategies and technologies to prevent aerosol-borne infections.

In this context, we are looking for a highly motivated student (f/m/d) to work on the development of numerical models for the simulation of dynamic situations. Ideally, the model should reproduce the spread of exhaled aerosols while a person walks. An immersed boundary method is available in the group and will be further developed.

Institute: Institute of Fluid Dynamics

Contact: Dr. Lecrivain, Gregory, Cavagnola, Marco Alejandro

Requirements

  • General interest in fluid mechanics
  • Preliminary experience in code development (c++) is desirable
  • Good written and oral communication skills in either English or German

Conditions

  • Either an immediate start or a start in 2023 is possible
  • Duration of the internship is anticipated to be 6 months but can be modified according to study regulations
  • Remuneration according to HZDR internal regulations

Online application

Please apply online: english / german

Druckversion


Calculation of multi-phase flow using the GENTOP model with FLUENT (Id 346)

Student practical training / Master theses / Diploma theses

Foto: Fig. 1: Boiling pipe flow (left: disperse gas volume fraction, right: continuous gas volume fraction) from Setoodeh et al., Applied Thermal Engineering 204 (2022) 117962 ©Copyright: Dr. Thomas HöhneAs a member of the Helmholtz Association of German Research Centers, the HZDR employs about 1,400 people. The Center's focus is on interdisciplinary research in the areas energy, health and matter. The Institute of Fluid Dynamics is conducting basic and applied research in the fields of thermo-fluid dynamics and magnetohydrodynamics in order to improve the sustainability, the energy efficiency and the safety of industrial processes.

Multiphase flows are important part of many industrial applications, whereas modelling of them is a challenging and complex task. For flow situations with higher void fractions, HZDR developed a new generalized concept for the CFD-simulations including flow regime transitions. The GENTOP (Generalized Two-Phase Flow) approach is able to simulate co-existing large-scaled (continuous) and small-scaled (polydispersed) structures (Fig. 1). Previous results were performed with the CFD code CFX and compared against DEBORA validation data.

The goal of the thesis would be to apply and improving the existing state of the simulations in the Fluent GENTOP framework.

We offer an interesting task dealing with complex physical phenomena, work in an international team using state-of-the-art calculation and programming methods.

We are looking for a motivated student (f/m/d) (master thesis) able to perform CFD simulations, understand and program code to generalize/parametrize CFD simulations, work with experimental data sets, document and present the work in an appropriate manner. Useful but not required is a knowledge of the following software tools: CFD codes CFX and Fluent, Python, GIT.

The task is supervised by Framatome and HZDR.

FRAMATOME is a designer and supplier of nuclear steam supply system and nuclear equipment, services and fuel for high levels of safety and performance. Framatome is a major international player in the nuclear energy market recognized for its innovative solutions and value-added technologies for designing, building, maintaining, and advancing the global nuclear fleet. The company designs, manufactures, and installs components, fuel and instrumentation and control systems for nuclear power plants and offers a full range of reactor services. With 14,000 employees worldwide, every day Framatome's expertise helps its customers improve the safety and performance of their nuclear plants and achieve their economic and societal goals.

Department: Computational Fluid Dynamics

Contact: Dr. Höhne, Thomas, Dr. Lucas, Dirk

Requirements

  • Studies in Engineering, Computer Science or comparable
  • Interest in numerical work
  • Good communication skills in both written and spoken English
  • Useful but not required is a knowledge of the following software tools: CFD codes CFX and Fluent, Python, GIT.

Conditions

  • A vibrant research community in an open, diverse, and international work environment.
  • Scientific excellence and extensive professional networking opportunities.
  • Compensation as student researcher (working hours to be determined).
  • Working place will be Dresden and/or Erlangen Germany.

Online application

Please apply online: english / german

Druckversion


Motion tracking of autonomous sensor particles in industrial vessels (Id 335)

Master theses / Diploma theses / Compulsory internship

Foto: AutoSens_StirredReactor ©Copyright: fwdf (Mailgruppe)Data acquisition in large industrial vessels such as biogas fermenters or wastewater treatment plants is limited to local measurement points due to limited access to the vessel and the non-transparency of the fluid. To optimize these kinds of plants, the three-dimensional flow field and the spatial distribution of fluid properties such as temperature and electrical conductivity inside the vessel must be known. This can be achieved by the autonomous flow-following sensor particles developed by the HZDR. Equipped with a pressure sensor, an accelerometer, two gyroscopes and a magnetometer, the sensor particle can track the movement inside the vessels and derive the flow field from that. Additionally, the sensor particle gets position information by an ultra-wide-band based localization module (like GPS) as soon as it is on the fluid surface. The motion of the sensor particle is currently tracked with an error-state Kalman filter and yields a reliable tracking of the velocity and position, respectively. However, the tracking time is limited by the propagation of uncertainties of the inertial sensors through the filter. The objective of this master thesis is to extend this tracking time by the use of more advanced tracking algorithms like particle filter or other types of Kalman filters. This includes the following tasks:

  • Literature review of advanced filters for motion tracking
  • Theoretical comparison and implementing the most promising algorithm in Python
  • Verification and performance analysis based on experimental data

Department: Experimental Thermal Fluid Dynamics

Contact: Buntkiel, Lukas, Dr. Reinecke, Sebastian

Requirements

  • Studies in the area of electrical, mechatronic, mechanical engineering or similar
  • Basics of measurement uncertainty, digital signal processing
  • Data analysis in Python
  • Independent and structured way of working

Conditions

  • Start possible at any time
  • Duration according to the respective study regulations

Links:

Online application

Please apply online: english / german

Druckversion


Experimental investigation of influence of interfacial viscoelasticity on the dripping to jetting transition (Id 333)

School practical training / Student practical training / Bachelor theses / Master theses / Compulsory internship

Foto: Capillary with jetting liquid-liquid interface ©Copyright: Milad EftekhariLiquid jets are unstable and eventually form droplets to minimize the surface energy with the surrounding fluid. The transition from dripping to jetting and dynamics of the droplet pinch-off have been studied extensively for various systems, from pure Newtonian fluids to complex non-Newtonian liquids. The jetting process has received significant attention as it is a critical step in various three-dimensional (3D) printing techniques such as dropwise additive manufacturing and the direct ink writing method. In most of the applications surface active materials such as surfactants, nanoparticles, and polymers exist in the systems. The presence of surface-active materials reduces the liquid-fluid surface energies and in some cases generates a viscoelastic layer at the interface.
In this research, we aim to study the influence of interfacial viscoelasticity on the dripping to jetting transition. The study is conducted by the injection of an aqueous phase (nanoparticle dispersions) into an oil phase that contains surfactants over a wide range of flow rates. We tune the magnitude of interfacial viscoelasticity by changing the concentration of surfactants and nanoparticles.
Research question:
Does the dripping to jetting transition (critical flow rate) linearly increase by increasing the interfacial viscoelasticity?

Experiments:

1. Measurements of interfacial tension and surface elasticity for a range of particle and surfactant concentration using Profile analysis tensiometry, and Langmuir trough.
2. Dripping to jetting experiments for the selected systems using high-speed cameras and in-house setups.

Department: Transport processes at interfaces

Contact: Eftekhari, Milad, Dr. Schwarzenberger, Karin

Requirements

  • Field of study: chemical engineering, process engineering, fluid mechanics, or similar focus in chemistry or physics
  • Experience with laboratory work and imaging measurement techniques is beneficial

Conditions

  • Working in an international team
  • Duration: at least 6 months
  • Location: Dresden-Rossendorf

Online application

Please apply online: english / german

Druckversion


Techno-ökonomische Bewertung eines hybriden Energiespeichersystems basierend auf einem batteriegestützten Power-to-Methanol Prozess und erneuerbaren Energien (Id 331)

Master theses / Diploma theses

Das Institut für Fluiddynamik des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) beschäftigt sich unter anderem mit Fragen der Modellbildung und Simulation von verfahrenstechnisch eng gekoppelten Power-to-X-Systemen bestehend aus den Teilprozessen Hochtemperaturelektrolyse (Solid Oxide Electrolyzer Cells) und heterogen katalysierten Syntheseprozessen von synthetischen Energieträgern der Zukunft (Methanol, Methan, usw.) unter stofflicher Nutzung anthropogener Kohlenstoffdioxidemissionen und regenerativ produziertem Strom. Auf Basis eines bereits existierenden Modells eines Power-to-Methanol Prozesses und eines ebenfalls vorliegenden techno-ökonomischen Teilmodells (TEA) soll die Wirtschaftlichkeit der dezentralen Produktion von Methanol mit Hilfe von erneuerbarem Strom in Kopplung mit großen Batteriespeichern untersucht werden.
Zur Realisierung dieser Aufgabe bietet die Abteilung Experimentelle Thermofluiddynamik für Studenten der unten genannten Studiengänge studienbegleitende Tätigkeiten zur beschriebenen Thematik an. Die Voraussetzung ist die Anfertigung einer Diplom- oder Masterarbeit.

Folgende Teilarbeiten sind durchzuführen:

  • Literaturrecherche zu hybriden Energiespeichersystemen basierend auf Power-to-Methanol Prozessen und Batteriespeichern hinsichtlich Prozessdesign und Wirtschaftlichkeit,
  • Literaturrecherche zur mathematisch-physikalischen Modellierung von Batteriespeichern und Erstellung eines einfachen Batteriespeichermodells mittels Matlab,
  • Ermittlung der ökonomischen Randbedingungen für großskalige Batteriespeicher auf Basis von Literaturdaten,
  • Untersuchung der Wirtschaftlichkeit des hybriden Energiespeichersystems für ein vorgegebenes Anschlussszenario für den Betrieb mit erneuerbaren Energiequellen.

Department: Experimental Thermal Fluid Dynamics

Contact: Fogel, Stefan

Requirements

  • Student (w/m/d) der Studiengänge Wirtschaftsingenieurwesen, Chemieingenieurwesen, Verfahrenstechnik, Energietechnik, Maschinenbau oder ähnlicher fachlicher Ausrichtung,
  • Grundkenntnisse in Matlab wünschenswert,
  • Sorgfältige, kreative und selbstständige Arbeitsweise,
  • Gute Sprachfertigkeiten (oral/schriftlich) in englischer und deutscher Sprache,
  • Freude an der wissenschaftlichen und eigenständigen Arbeit.

Conditions

Bearbeitungszeit: 6 Monate (Beginn ab sofort)

Online application

Please apply online: english / german

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CFD simulation of gas-liquid flow in tray columns (Id 304)

Master theses / Diploma theses / Compulsory internship

Foto: Eye-Catcher ColTray-CFD ©Copyright: Dr. Philipp WiedemannTray columns are used for thermal separation of multicomponent mixtures in the chemical industry. Owing to increased energy supply from renewable sources a more flexible operation of such apparatuses is already demanded. However, enlarged over- and underload modes are challenging with respect to design. Basically, computational fluid dynamics provide a powerful support by predicting the complex two-phase flow on the tray and its application is hence investigated in a current research project.
For that purpose, a hybrid multiphase flow model was adapted for the present simulation task by implementing local mass and momentum sources to mimic the gas inlets from the tray into the froth zone. Additionally, a pre-processing tool was developed that allows for automatic generation of the computational domain and adjustment of boundary conditions.
Within the frame of a current research project we offer a student internship position for applying the developed multi-phase CFD model. The candidate needs to perform simulations and to evaluate the results by comparison with available experimental data. Special focus is put on the influence of different tray designs and operating conditions.

Department: Experimental Thermal Fluid Dynamics

Contact: Dr. Wiedemann, Philipp

Requirements

  • studies in chemical/process/energy/mechanical/computational engineering
  • substantiated knowledge in the field of CFD, preferably OpenFOAM
  • creativity and problem-solving skills
  • good written and oral communication skills in English and German

Conditions

  • start: from Oct. 2022
  • working in a multi-disciplinary team
  • remuneration according to HZDR internal regulations

Links:

Online application

Please apply online: english / german

Druckversion