Art:

Masterarbeit, Studienarbeit

Themenbereich

Simulativ

Thema

Art: 

Studienarbeit, Forschungsarbeit, Projektarbeit, Bacherlorarbeit

Themenbereiche: 

Experimentell

Thema:

Die Phosphatentfernung aus dem Abwasser in Kläranlagen ist essentiell, um eine Eutrophierung von Gewässern zu verhindern. Üblicherweise erfolgt dies durch Fällung, könnte jedoch auch durch eine Adsorption von Phosphat, bspw. in einem Festbettreaktor, realisiert werden. Dieser Adsorptionsprozess wird in seiner Effizienz maßgeblich von verschiedenen Betriebs- und Konstruktionsparametern (z. B. Geometrie der Säule, Volumenströme, Partikeldurchmesser etc.) beeinflusst. Auch die Eigenschaften des verwendeten Adsorbens spielen hinsichtlich der Kapazität sowie der Adsorptions- und Diffusionseigenschaften im Partikelinneren eine große Rolle. Der Einfluss dieser Parameter kann durch die Messung von Durchbruchskurven bestimmt werden.

Aus diesem Grund soll in dieser Arbeit das Adsorptionsverhalten von Phosphat für unterschiedliche geometrische und hydraulische Parameter untersucht werden. Es sollen unterschiedliche Säulengeometrien durch eine Variation des Verhältnisses von Länge zu Durchmesser getestet werden. Außerdem sollen die Leerrohrgeschwindigkeit und die Partikelgröße des Adsorbens variiert werden. Um den Einfluss der Porosität auf die Adsorption zu untersuchen, sollen unterschiedliche Packungstechniken für das Festbett angewandt werden. Des Weiteren soll die Strömungsführung variiert werden, um fluiddynamische Einflüsse zu untersuchen. Mit den gewonnenen Daten sollen anschließend Betriebspunkte für verschiedene Geometrien verglichen und bewertet werden.

Ziele: Ziel dieser Arbeit ist die experimentelle Untersuchung des Einflusses geometrischer und hydraulischer Parameter auf das Adsorptionsverhalten von Phosphat in Festbettreaktoren zur Identifikation optimaler Betriebsbedingungen.

Anforderungen: Laborerfahrung vorteilhaft.

Ansprechpartner:  Christina Zipp

Level:

Study project, Bachelor Thesis

Topic Area

Simulation

Topic

Level: 

Study project, Bachelor Thesis, Master Thesis

Topic Area: 

Experimental

Topic:

Citric acid is a major chemical commodity produced and consumed globally. Industrially, it is produced via fermentation using Aspergillus niger. To remove byproducts and other contaminants from the fermentation broth, the medium is first filtered to eliminate solids. Following this, a precipitation reaction is carried out in which citric acid reacts with calcium hydroxide to form insoluble tricalcium citrate, which can then be filtered out, separating it from dissolved impurities in the liquid phase.

As part of the Smart Batch Processes project, the flexible operation of this chemical reaction will be investigated. To simulate the process on an industrial scale, a reaction kinetic model is required. Therefore, a kinetic study of the system will be conducted in a 30 L batch stirred tank reactor, aiming to quantify the temperature and concentration dependence of the reaction rate.

The resulting kinetic data will be used to model the reaction as a system of ordinary differential equations (ODEs) using the Julia programming language. This will allow the flexible operation of the process to be explored through both experiments and simulations.

Goals: Measuring Kinetic Data of a Precipitation Reaction and Fitting a Kinetic Model to it.

Requirements: Experience in laboratory work is an advantage.

Contact:  

Thomas Grießer

Level:

• Master

Type:

• Modelling and Simulation

Topc:

Disperse multiphase flows often occur in process engineering. Knowledge of the size of the fluid particles is important for model-based design. The size influences the mass and heat exchange as well as the residence time of the dispersed phase in the apparatus. A thorough understanding of this is therefore necessary for the design of the apparatus in terms of yield, selectivity, separation efficiency, etc. To describe the change in size, the population balance equation is usually used, which can describe phenomena such as fluid particle breakage, coalescence, growth, and nucleation in a statistical manner. In PBE, the number is usually balanced, i.e., how many bubbles per size class and volume. However, millions of particles can occur in process engineering apparatus, making the numerical solution susceptible to rounding errors. Other balance variables such as mass or volume are also possible, but lead to a more complex formula for the PBE, which in turn has numerical disadvantages. For this reason, this thesis will examine the different balance quantities, e.g., number, mass, volume, with regard to different size types (length, volume, mass) in terms of different properties (efficiency, stability, conservation properties).

Goals

• Transformation of the PBE in mass, number and volume base with internal coordinates mass, volume and length.

Requirements:

• Experience in coding

Start:

• Now

Duration

• Six months

Ansprechpartner:

• ferdinand.breit(at)rptu.de

Level:

• Master

Type:

• Modelling and Simulation

Topc:

Disperse multiphase flows often occur in process engineering. Knowledge of the size of the fluid particles is important for model-based design. The size influences the mass and heat exchange as well as the residence time of the dispersed phase in the apparatus. A thorough understanding of this is therefore necessary for the design of the apparatus in terms of yield, selectivity, separation efficiency, etc. To describe the change in size, the population balance equation is usually used, which can describe phenomena such as fluid particle breakage, coalescence, growth, and nucleation in a statistical manner. In some processes, it is desirable that the dispersed phase is completely absorbed, meaning that the particles first shrink and then disappear due to mass transfer. In this work, a new model for describing the change in size due to mass transfer will be derived and implemented. Subsequently, the model predictions will be investigated with regard to sensitivity of the model parameters and compared with experimental data from the literature.

Goals:

• Modelling:
  • Derivation of a bubble shrinkage model based on a Lagrangian approach with curved interface and time-varying film model.
• Simulation:

  • Verification of model predictions using individual bubble experiments from the literature.

  • Implementation of the model in an existing PBE model.

Requirements:

• Experience in coding

Start:

• Now

Duration

• Six months

Ansprechpartner:

• ferdinand.breit(at)rptu.de

Art:

• Master thesis

Topic Area:

Mass transfer with chemical reaction in two-phase systems

Topic:

Gas-liquid reactors are widely used in industrial applications. Several processes, such as hydrogenation, halogenation, sulfonation, nitration, oxidation of organic and inorganic compounds, are performed in gas-liquid reactors where reactions between liquid and gaseous reactants take place [1]. These reactors have a crucial role in transforming raw materials into valuable products in industries such as pharmaceuticals, petrochemicals, and environmental engineering.

To optimize mass transfer in gas-liquid reactors, it is essential to have a comprehensive understanding of the reaction kinetics and carefully consider factors such as mixing, interfacial area, mass transfer coefficient, temperature, pressure, and more. By investigating these factors, we can enhance our understanding of the underlying mass transfer mechanisms and develop strategies to optimize reactor design and operation.

Aims:

In this work, sulphite oxidation is used to measure mass transfer coefficient in a gas-liquid mixing reactor, and the influence of different mixing intensities on mass transfer and hydrodynamic parameters such as bubble diameter, gas hold-up, and interfacial area is investigated. By studying these factors, useful insights can be gained into the dominant mass transfer mechanisms within the reactor.

Requirements:

• Basic knowledge of mass transfer and fluid mechanics.
• Ability to work independently.
• Independent problem solving.
• Experience with experimental equipment and/or laboratory experience is desirable.

Reference: [1] M. Pisu, A. Cincotti, G. Cao, F. Pepe, Studies in Surface Science and Catalysis, Volume 133, 2001, Pages 471-476.

Contact:Seyedeh-Saba Ashrafmansouri

Art: 

Level:

• Master

Type:

• Modelling and Simulation

Topc:

Disperse multiphase flows frequently occur in process engineering. They exhibit highly complex fluid dynamics that are still difficult to predict today. An Euler-Euler approach with interphase penetrating (pseudo-continuous) approach is commonly used to describe industry-scaled processes. By considering the dispersed phase as a continuum, almost all properties of the dispersed phase are lost (size, shape, etc.). This makes it difficult to predict the complex fluid dynamic behavior. In order to better represent the properties of the dispersed phase, the kinetic theory of fluid particle flow (KTFPF) was recently developed. In this work, a simplified version of the KTFPF for a 1D or 2D bubbly pipe flow is to be solved using a discontinuous Galerkin spectral element method (DGSEM) .

Goals

• DGSEM:
  • Implementation of a DGSEM for various problems, e.g., Pellet equation, heat conduction, Poisson equation, Stokes problem, Euler equation, etc., to verify the implementation of the solver.

• Solution of the KTFPF:

  • Implementation of a simplified time-dependent 1D (in space) solution of the KTFPF

  • Desirable: Implementation of a time-dependent  2D (in space) solution of the KTFP.

Requirements:

• Experience in coding

Start:

• Now

Duration:

• 6 months

Contact:

• ferdinand.breit(at)rptu.de

Level:

• Bachelor/Master

Type:

• Modelling and simulation

Topc:

In process engineering, ideal reactor models are typically used to design and optimize multiphase processes. All interacting phases are assumed to be pseudo-continuous, so that nearly all properties of the dispersed phase are averaged. This means that empirical correlations must be used to determine, for example, the phase fraction that results from the behavior of the dispersed phase. One way to more accurately capture the behavior of the dispersed phase is to include population balances in ideal reactor models. Such a model was developed at the LRF and has already been successfully validated for use in bubble columns in several studies. As part of this work, this validation will be continued with new data from a cooperation partner. The data provided includes bubble size distributions as well as global and local gas fractions. They extend the previous validation studies with regard to the material system used, the gas empty tube velocity, and the column diameter.

Goals:

• Data preparation:

  • Summary of data and development of methods for filtering, loading, and storing.

• Implementation & model validation:

  • Development of a calibration routine for the fit parameters (empirical parameters of the break and coalescence kernels) in Julia.

  • Comparison of model predictions with the new data – with and without recalibration of the fit parameters.

Requirements:

• Experience in coding

Start:

• Now

Duration:

• 6 months

Ansprechpartner:

• ferdinand.breit(at)rptu.de

Art:

Teamarbeit, Studienarbeit, Forschungsarbeit, Projektarbeit

Themenbereich

Konstruktiv, Experimentell

Thema

Art:

• Masterarbeit

Themenbereiche:

• Experimentell

Thema:

Wenn die Geschwindigkeit einer Reaktion extrem hoch ist, kann die Vermischung der Edukte eine große Rolle für die Selektivität spielen. Im Gegensatz zu kinetisch limitierten Reaktionen gibt es für diese mischungssensitiven Reaktionen keine einfachen Modellansätze, die den Einfluss verschiedener Prozessvariablen, wie z.B. der Feedeintrittsgeschwindigkeit oder der Lage der Feedpunkte, auf die Selektivität der Reaktion zuverlässig beschreiben können. Aus diesem Grund wird am Fraunhofer ITWM in Zusammenarbeit mit dem LRF eine CFD-basierte Methode entwickelt, die diese Zusammenhänge zuverlässig beschreiben soll. Um die Qualität der Modellvorhersage zu überprüfen, werden im Rahmen dieser Arbeit experimentelle Untersuchungen durchgeführt.

Dazu sollen zwei verschiedene Untersuchungen an einem einfachen einphasigen Reaktor durchgeführt werden. Zum einen sollen mittels Particle Image Velocimetry (PIV) Messungen die Strömungsverhältnisse im Einlaufbereich erfasst werden. Zum anderen sollen in diesem Reaktor umfangreiche Parameterstudien mit mischungssensitiven Testreaktionen durchgeführt werden.

Ziele:

• Aufbau einer Messapparatur und Durchführung von fluiddynamischen und reaktiven Studien von mischungssensitiven Reaktionen.

Anforderungen:

• Erfahrung im Labor vorteilhaft

Ansprechpartner:

• Erik von Harbou
• Seyedeh-Saba Ashrafmansouri