PhD
The PhD student will work on the electrode morphology and the modelling of the electrode and the full battery. Fluid mechanics simulations will be done (80%), thereby using techniques based on the lattice-Boltzmann method. An experimental facility will be developed and used (20%), and functions as a validation case for the modelling.
More info on https://www.academictransfer.com/nl/328650/phd-student-on-transport-phenomena-in-a-zinc-air-flow-battery-for-electrochemical-energy-storage/
Free
Msc
Microfluidic multiphase flow is a topic of increasing interest because of its applications and the possibilities it offers in various fields. The major advantages of operating in the microscale include the large surface-volume ratios, control of fluid flow and lower costs. A method that is becoming increasingly popular for simulating multiphase flow is the Lattice Boltzmann method. There are numerous models available in this technique, and we use the colour-gradient or Rothman-Keller (RK) model. This model has the advantages of simplicity and can be easily implemented because no interface tracking is involved. It has proven to be effective when simulating flows at high Capillary numbers (Ba et al, 2016), however, at lower Capillary numbers, we observe problems. This is related to the implementation of surface tension in the RK model, which uses the Continuous Surface Force (CSF) method proposed by Brackbill et al (1992). The CSF method is known to generate spurious (numerical) velocities, and these velocities are observed to have an impact on the simulation results at low Capillary numbers. The Capillary number is the ratio of the viscous and surface tension forces, so spurious velocities associated with surface tension implementation are common when the surface forces are large at lower Capillary numbers. Since many applications, including radioisotope transfer, involve flows at lower Capillary numbers, modifications are necessary to enhance the capabilities of the RK model. This thesis thus seeks to improve the RK model by modifying the CSF method for surface tension. The student will work with an in-house code and survey the literature for previous modifications made to the CSF method using other numerical techniques. The case of a Y-Y channel will be considered, and the student will try to match the experimental results using the modified surface tension technique. Once this is implemented, the impact of the inlet angle of the Y-Y channel on the flow patterns can also be studied.
Free
Msc
Microfluidic multiphase flow is a topic of increasing interest because of its applications and the possibilities it offers in various fields. The major advantages of operating in the microscale include the large surface-volume ratios, control of fluid flow and lower costs. The flow patterns in such flows are influenced by a number of factors, of which inlet geometry is an important but less studied aspect. A recent paper by Lei et al (Experimental and numerical studies of liquid-liquid slug flows in micro channels with Y-junction inlets, 2022) studied droplet formation for four different inlet angles in a Y-Y channel, where they found that the inlet angle had an impact on the size of the droplet. This thesis seeks to extend the study by observing the impact of inlet angles on the overall flow patterns, while also looking to understand the influence of the inlet junction on the slug/droplet formation, shape and size. An in-house Lattice-Boltzmann code will be used to simulate these cases, with necessary modifications made by the student for different intersection junctions. The in-house code can also be improved by the student through grid refinement.
Free
Msc
The most innovative aspects of the Molten Salt Fast Reactor (MSFR), one of the six Generation IV nuclear reactors, are that the fuel is dissolved in a liquid salt, and that it can be passively drained in an Emergency Safety Tank placed underneath the core, via the melting of plugs made of frozen salt. Modeling solidification/melting phenomena is numerically challenging due to the presence of a moving solid-liquid interface.
In this project the freezing and melting under turbulent conditions is measurend by using Particle Image Velocimetry and possibly Laser Induced Fluorescence.
Occupied
Msc
During the operation of molten salt reactors valuable fission products are formed. Due to the extreme working environment, a removal of those particles is challenging. One promising technology to remove fission products is the separation via helium bubbling. Here, the fission particles are adhering to the helium bubbles, from which they are getting transported to the liquid surface, from where they can get separated. Part of the research is building up a setup for experiments with molten salts, in which the flow characteristics and particle removal are determined by methods like the Laser-Doppler-Anemometry and Particle Image Velocimetry. In a first step, experiments will be conducted at room temperature in water and a model system consisting of water/glycerol, which is well established to mimic the characteristics of the molten salt. From these results, operating conditions will be determined, which will be used in a later step with the molten salt setup at elevated temperatures. Moreover, numerical work in the form of CFD-simulations can be included to obtain additional information about the phenomena inside the reactor.
Occupied
Msc
LBM is mostly used for fluid flow and scalar transport (heat, species). A lesser known feature, however, is the fact that the method can also be used for neutron transport and be coupled to momentum and energy transport. Recently, researchers have extended the method for neutronics. In this project, the method will be applied to either a molten-salt reactor case or the DIPR, a reactor in which radio-isotopes can be produced. If you are interested, we can start a discussion on the exact topic to be done.
Occupied
Msc
Supercritical fluids are being used in a wide range of applications such as chemical processes (e.g. extration) and energy processes (e.g. heat removal, nuclear reactors). In this study, the student is going to use and extend the lattice-Boltzmann Method for supercritical fluids and study the phenomenon of natural convection under laminar (and perhaps) turbulent conditions.
Occupied
Msc
The most innovative aspects of the Molten Salt Fast Reactor (MSFR), one of the six Generation IV nuclear reactors, are that the fuel is dissolved in a liquid salt, and that it can be passively drained in an Emergency Safety Tank placed underneath the core, via the melting of plugs made of frozen salt. Modeling solidification/melting phenomena is numerically challenging due to the presence of a moving solid-liquid interface. In this project freezing of the salt in a natural circulation driven cavity is studied by using the lattice-Boltzmann method. The system that needs to be investigated is a laminar flow with one wall being colder that the melting temperature.
Occupied
Msc
The most innovative aspects of the Molten Salt Fast Reactor (MSFR), one of the six Generation IV nuclear reactors, are that the fuel is dissolved in a liquid salt, and that it can be passively drained in an Emergency Safety Tank placed underneath the core, via the melting of plugs made of frozen salt. Modeling solidification/melting phenomena is numerically challenging due to the presence of a moving solid-liquid interface. In this project freezing of the salt on a surface is studied by using the lattice-Boltzmann method. The system that needs to be investigated is a laminar flow through a channel, with one wall being colder that the melting temperature.
Occupied
MSc/BSc
This project is part of our goal to measure the viscosity of molten fuel salts at high temperature with the help of an ultrasonic guide. These properties are needed to predict turbulence and local melting and solidification of the salt. Ultrasonic waves propagating in a metal waveguide are possibly influenced by the temperature. In this project the measurement of the reology of a power-law fluid will be done, together with the development/use of an analytical model.
Occupied
MSc
In the molten salt reactor, metallic fission products need to be removed. Currently the idea is to remove these fission products by the introduction of helium bubbles which take these particles to the surface of the molten salt. In this project the extraction of particles is measured in a simulant fluid and with the help of laser techniques (Laser Induced Fluorescence). The set up has been established, and the first measurements have been done, but the technique needs to be improved. Moreover measurements have been done with polymeric particles, and an extension has to be made towards metallic particles.
Occupied
Martin Rohde (2023)