Nowadays, Hydrogen production is an important piece in energy transition system and holds a significant place in various industries. This gas is precursor for producing valuable compounds in the chemical industry and serves as a clean fuel, enabling efficient electricity generation when used with fuel cells. However, majority of its production still relies on reforming and gasification of non-renewable sources. A sustainable pathway for Green Hydrogen production through water electrolysis already exists. However, scaling up and commercializing this technology represents challenge in meeting global demand, which was reported to be around 95 million tonnes in 2022. Commercially available water electrolysis done in acidic environment is robust, however rather expensive. Anionic Exchange Membrane Water Electrolysis (AEMWE) is available alternative, but still not fully developed to be used on big industrial scales. AEMWE offers reduced cost as this technology does not require usage of expensive noble metal catalysts used in acidic electrolysis. Focus of the AEMWE research area is Anionic exchange membrane (AEM) as high values of conductivity of hydroxide ions could lead to fair technical competitiveness of alkaline and acidic electrolysis. However, the majority of currently available AEMs lack the desirable properties, such as mechanical/alkaline stability as well as anionic conductivity.
One of the promising novel techniques for membrane fabrication consists of membrane casting with employing DC electric field, which enhances charged polymer channel orientation. Reports have shown that polymer ion channels in random direction may cause slower migration and consequently lower values for conductivity. On the other hand, it has been proven that DC treated membranes can yield up to three times higher values for conductivity of OH− ions. Therefore, researching optimal DC values for casting significantly impacts electrochemical cell performance.
This thesis report focuses on fabrication, characterisation and performance evaluation of the cast membranes with DC empolyment, prepared from cationic polymer kindly provided from industrial collaborator. Furthermore, an attempt will be made to assess competitiveness between produced and commercially available membranes. Finally, future suggestions for research directions and alternative membrane fabrication techniques will be provided, as these could offer valuable insights for further exploration in this field.

Green hydrogen produced by water electrolysis is one of the most promising technologies to realize the most effective way of utilizing intermittent renewable energy globally. Among the various electrolysis technologies, the emerging Anion-Exchange Membrane Water Electrolysis (AEMWE) shows promising potential for producing green hydrogen at a competitive price.

The low ion conductivity of the Anion Exchange Membrane (AEM) is found to be one of the major limitations of AEMWE. In this thesis, the AEM is aligned while casting using an alternating current electric field to improve the ion conductivity of AEMs. The stability of the electrically aligned membrane is tested using various characterisation techniques. The electrically aligned membranes showed a 300% increase in ion conductivity, with a slight decrease in mechanical stability.

Inkjet printing is a technology that has been widely studied and implemented. The liquids that are used for inkjet printing can vary. There is the traditional ink which can be found in almost every household printer. But it is also possible to use inkjet printing to deposit drugs, proteins and nanoparticles on substrates. Inkjet printing has the ability to precisely deposit picoliters of liquid onto the substrate. Thus, reducing cost and waste when the material being used is expensive and/or of limited quantity. This project works with a LP50 PIXDRO inkjet printer. Another interest that gained traction in the scientific community are the stimuli-responsive microgels. These microgels are able to change their dimensions depending on the external stimuli and if this stimuli is removed from the microgel, it changes back to its original shape, thus it is a reversible process. This project uses a suspension of the stimuli-responsive microgel; poly(N-isopropylacrylamide)-coacrylic acid (pNIPAm). This microgel is responsive to temperature and pH. To deposit the pNIPAm suspension on the substrate, inkjet technology will be used. The printability of the pNIPAm will be determined by characterizing the physical and rheological properties. Such as the density, surface tension, viscosity and particle size of the pNIPAm beads. These properties will be compared to the ideal liquid requirements given by the print cartridge that will be used, a Fuijifilm Dimatix. To influence the surface tension three surfactants will be tested. These surfactants are Triton X-114 (TRT), Sodium dodecyl sulphate (SDS) and Hexadecyltrimethylammonium bromide (CTAB). Based on the results the and comparison to the requirements the surfactant Triton X-114 is chosen because it lowers the surface tension the most. While it has minimal to no affect on the pNIPAm particles. The next phase of the project is testing the printability of the pNIPAm. This is done by adjusting the waveform on the LP50 PIXDRO inkjet printer. As a result it is indeed possible to deposit pNIPAm on a substrate with an inkjet printer. After this step a SEM is used to investigate if the printed pNIPAm particles will form a monolithic layer. This monolithic layer is important when it comes to having a functional etalon. The pNIPAm particles form indeed a monolithic layer on the substrate. The last step is to see if there is a peak shift in the wavelength when the temperature is increased. The microgel based etalons that used an inkjet printer to deposit the micrgol show a peak shift. Therefore, it can be concluded that it is possible to use an inkjet printer to deposit pNIPAm on a substrate and that the pNIPAm particles behave according to literature. All the results of this project show that using an inkjet printer is a viable alternative for fabricating microgel based etalons.

This master thesis introduces a recently surfaced method to produce hydrogen and oxygen using alkaline water electrolysis. A hydrophilic porous diaphragm is used that can feed electrolyte laterally to two porous electrodes that are placed against it. Consequently, hydrogen and oxygen are produced directly at the electrodes without any bubble formation. More specifically, this master thesis aims to investigate the thermal behaviour of such a capillary-fed electrolyzer and the limits to which capillary-fed electrolysis can be sustained.
A small scale capillary-fed cell and a larger segmented cell are manufactured during the project. Both cells are used to perform experiments at constant current. Capillary rise in diaphragms with and without compression deviate from the Lucas-Washburn model for capillary rise. Particularly the polyethersulfone material outperforms the diaphragms that were studied. It follows the Lucas-Washburn equation relatively well and exhibits two times deeper penetration under compression. Furthermore, experiments have been performed studying the relation between electrolytic concentration and capillary wicking. Although more highly concentrated KOH solutions for electrolytes increase conductivity over time, it has shown that for the utilised diaphragm a KOH solution surpassing 3 moles per litre shows problematic capillarity. Contact angle experiments with 6M KOH have shown a hydrophobic contact angle of ̄Θ=78.14° compared to complete imbibition, i.e Θ = 0°, for 1,2 and 3M KOH solutions. The origin of these extremely large contact angles on the polyethersulfone substrate is not fully understood. 
The study has culminated in performing experiments at constant current and low concentration KOH utilising flushing and dilution techniques to prevent precipitation at the electrodes. The small cell reached an overall heat transfer coefficient of h = 121 W/m²K, showing very large heat production for a relatively small surface area. For the segmented cell, electrolyte supply with a bottom-up feed resulted in h = 19.13 W/m²K in which precipitation occurred. The top-down feed showed that the top segment has the largest areal heat dissipation. The heat transfer coefficient equates to h = 25.73 W/m²K. A final enhancement has been made by introducing Nickel Felt Fiber conducting layers into the cell to improve electronic conductivity. This resulted in an increased range of current densities that could be reached at lower overpotentials compared to absence of these conductive layers. This resulted in the bottom most segment to exhibit the largest areal heat dissipation. The heat transfer coefficient here equates to h = 43.86 W/m²K.
This study takes another important step into the regime of capillary-fed electrolysis and alternative electrolysis methods in general. Introducing an alternative design, assessing this design from experimentation and reporting on subsequent steps that can be taken.

Current membrane fabrication processes are not sustainable as they are energy-intensive and require hazardous solvents. Additive manufacturing, due to its low waste production and the absence of harmful chemicals, can provide a more sustainable membrane manufacturing process. Up to this point, there was no way to 3D-print a membrane that meets the microfiltration pore sizes (1-10 μm) required in today’s industry. In this work, we showcase for the first time that membrane with pore size < 10 μm can be 3D-printed via a dual wavelength 3D printer. Polyethylene Glycol Diacrylate (PEGDA) hydrophilic membranes with cylindrical pores were designed and printed.

A dual-wavelength micro-stereolithography 3D printer has been employed to print the membranes. Photopolymerizable resins containing PEGDA monomers, were polymerized into membranes via a mixed projection of UV and blue light, creating unpolymerized pores and polymerized matrix respectively.

Using a pixel size of 1.4 μm, we could produce hydrophilic membranes with cylindrical pores and a diameter < 10 μm. These membranes were compared with benchmarking commercial PTFE membranes (JCWP14225, Merck, Germany) with the same pore size range. The resulting membranes exhibited good oil-repellent properties, indicated by the higher oil contact angle values under water. The permeability and filtration results also provide valuable insights into the material used for membrane printing. All in all, a successful microfiltration membrane has been produced via a fast, user-friendly and sustainable method.

We have introduced the next-generation 3D printing method for printing microfiltration membranes with precise pore size, shape, configuration, and arrangement. With further improvements, this technology will provide a new era in membrane manufacturing.

Organ-on-chips (OoCs) are micro-fabricated cell culture platforms that mimic the function and structure of human organs. Limitations arose in the use of OoCs when they lacked sensing abilities and real-time monitoring. Throughout this thesis, an attempt is being made to address these complications by developing an \textit{in situ} glucose sensor for OoCs in collaboration with Bi/ond. The foundation of this proof-of-concept is an etalon, consisting of two reflective layers separated by a dielectric layer that allows light to enter and resonate between the reflective layers. The dielectric layer for this purpose will be microgels, with particular emphasis on the biomedical potential of the thermoresponsive polymer poly-(N-isopropylacrylamide) (pNIPAAm).
This sensor was developed on silicon and PDMS substrate using evaporation of Cr/Au, spin-coating pNIPAAm-co-10%-AAc and pNIPAAm-co-10%, and mid or post process modification with APBA. Plasma treatment was employed to create a monolithic layer, resulting in a successfully completed fabrication process verified through SEM. Reflectance spectroscopy confirmed the functionality and response, along with an effective generation of a calibration curve for glucose for both substrates and modification processes. The post process approach emerged as more preferable while exhibiting resilience to sterilization procedures that even improved its response to glucose due to removal of unbound APBA during sterilization. Post process samples were used to detect changes in glucose levels in cell medium that had been in contact with C2C12 mouse myoblast cells over 1-, 3-, and 7-day periods. The results showed that the concentration of glucose declined approximately 16 mg/dL after day 1, 130 mg/dL after day 3 and 227 mg/dL after day 7, in comparison to the control measurement. Additionally, there was optical confirmation of the non-toxic effects of the microgel-beads on cell culturing. The investigation of this proof-of-concept of glucose responsive microgel-based etalons was successful, and the next stage would involve integrating this sensor into a chip of Bi/ond.

Supported liquid membranes have recently attracted a lot of attention in the field of gas separation. They are an innovation upon membranes, having improved separation performance over conventional membranes. Typically, membranes are infused with non-volatile liquids such as ionic liquids or deep eutectic solvents. The liquids chosen typically are good solvents for certain gases such as carbon dioxide, therefore attention is put towards using supported liquid membranes as a carbon capture technology. Most supported liquid membranes follow the solution-diffusion model, meanwhile conventional porous membranes follow the pore-flow model. However, in special cases of organic solvent nanofiltration, the
membranes are described by a combination of both models, the solution-diffusion with imperfections model. This work studies which model best applies to fluorinated liquid-infused membranes, known as slippery liquid-infused membranes, by measuring the permeability experimentally and comparing it with the theoretical permeability values obtained from experimental and theoretical solubility parameters.

The power plant, steel and petrochemical industries are large sources of carbon emissions worldwide. For meeting the climate goals of 2030 and 2050, efforts are underway towards pioneering novel technologies. Gas separation by supported liquid membranes is an attractive option for its energy-efficient, continuous and low cost of operation. The separation of gases takes via a solution diffusion mechanism where the gases are separated based on their
selectivity. Krytox oil is a high performance perfluoropolyether polymeric lubricant, originally aimed for its application to supersonic transport aircraft. The lubricant is known for its chemical and thermal stability leading to a longer usable life. The oil has shown an affinity for carbon dioxide (CO2) gas, a weak Lewis acid, owing to the fluorine and oxygen atoms in the polymeric oil which act as Lewis base and is thus envisioned for use in supported liquid membranes for gas separation.
Molecular dynamics simulations serve as a powerful tool of study, overcoming the shortcomings of experimental methods such as the difficulty of measurements at elevated temperatures, pressures or handling dangerous chemicals. This project covers the study of transport properties of Krytox oil namely the oil viscosity and diffusivity of CO2 in the oil for varying conditions of temperature, pressure and polymer chain length using equilibrium molecular dynamics simulations. The suitability of various atomistic force field models for this particular study has been tested, proceeding with the Universal force field (UFF) as the model of choice for studying the oil properties. To shorten the simulation time and study long time scales, coarse-grained simulations have been carried out using state-of-the-art MARTINI force field. In addition to transport properties, Henry’s constant for the solubility of CO2 in Krytox oil
has been predicted via alchemical free energy calculations by molecular dynamics simulations.

Gas turbines (GT) play a crucial role in the transition to fully sustainable energy. Conversely, the expected growth of the GT market is met with more stringent regulatory requirements. Clearly, an increasing turbine inlet temperature (TIT) is beneficial for the efficiency of GT cycles. With increasing TIT, however, the magnitude of the thermal loads becomes unbearable, causing thermal fatigue of the component in a transient setting such as GT start-up or shut-down. Therefore, it is crucial that the thermal loads are well managed, which is typically achievable only by adequate external and internal cooling. Generally, such cooling systems are modeled in the industry using an uncoupled heat transfer (HT) approach, assuming that the heat coefficients (HTCs) are only influenced by the aerodynamics of the flow field: HTCs are obtained in a separate computational fluid dynamics (CFD) simulation and are extracted and mapped on the solid domain of the component. Firstly, the report presents a comparison between the uncoupled approach and the increasingly popular conjugate heat transfer (CHT) approach, in which the fluid and solid domains are solved in a single simulation. To do so, the commercial code (STAR-CCM+) is first validated for both laminar flat plate and turbulent offset jet in a steady-state setting. The latter is done by comparing three Reynolds-Averaged Navier-Stokes (RANS) models. The popular wall treatment methods: blended and high-y+ wall functions (WFs) are also compared. The comparison between the two HT methodologies is done by a parameter sensitivity study, involving the thermal conductivity of the solid (for both laminar and turbulent cases), Turbulent Prandtl number, and turbulence intensity. It was concluded that the realizable k-epsilon model is the most accurate for this flow. Conjugation played a marginal role for all parameters. with only a considerable difference in the stagnation regions, when the solid conductivity is low. The results using a high-y+ WF displayed high numerical dissipation due to the coarse mesh size and hence the difference between the HT methodologies was artificially low. It is therefore advised that the study of the high-y+ WF is repeated on a different flow arrangement/setting (e.g. increased inlet velocity). Secondly, the thesis details a study around the internal cooling of Siemens GT transition piece (TP), using CHT. An introduction of perpendicular ribs into a fully developed turbulent channel flow can theoretically significantly increase the heat transfer coefficient through the introduction of large-scale vortices downstream. An optimization routine was run with a hybrid algorithm to study the effect of different rib configurations in a steady RANS simulation, aiming to minimize both mass flow and transition bond coat temperature. The performance is compared to the baseline smooth channels used in the Siemens TP. No better results were achieved for both objective functions in comparison to the baseline case mostly due to the length of the channels. However, a considerable decrease in the coolant consumption was present with a limited increase in the BC temperature. The study showed that the optimization of such ribs can minimize the effect of skin friction (which influences the amount of coolant), and presents a possible further improvement of the TP cooling, without relying solely on the experience of the designer.

Separation of particles from suspensions has been an integral part of many industrial, chemical and biological processes. Traditional methods such as sieving, flocculation, centrifugation etc. have many demerits. This has lead to an interest in unconventional separation methods that use physical properties of the particles. Acoustophoresis is one such method that has gained popularity in recent times. Acoustophoretic separation is based on the density contrast between the particles and the medium, as well as the size of the particles. A particle in a medium in which an acoustic field has been applied, experiences an acoustic force. This acoustic force is greater in standing waves than traveling waves, which is why acoustophoretic devices generally use standing wave fields. Particles with positive contrast factor are pushed to the pressure nodes; once the particles reach the nodes, they are trapped. If the medium is in flow, the particles also experience drag force. The interplay between the drag and the acoustic force forms the basis for separation. Standing wave fields can further be distinguished as static fields or dynamic acoustic fields (DAF). In a static field, the nodes are stationary, while in DAF, there is movement of the nodes, caused by variation of source frequency. Here, the tendency of different-sized particles to follow the nodal movement gives rise to separation. DAF devices seem preferable when separation needs to be done on a larger scale.In this thesis, two novel DAF devices were studied; one device works on the principle of frequency sweeping, while the other works on frequency modulation. Both devices are 3D printed, and have two inlets and two exits, with separation occurring in an acoustic chamber where the DAF acts. Both devices are multi-nodal & milli-fluidic. The samples to be separated consist of polyethylene particles of a continuous size distribution between 32-106 µm, dispersed in water. The devices were tested at a total channel flow rate of 1000 mlh-1 (Reynolds number of 20). The aim was to understand how varying the flow and acoustic field parameters affect the separation/filtration performance of the devices. This was done by defining a “threshold size” or the cut-off size at which the entire particle distribution is divided into two separate distributions. Flow and acoustic field parameters were adjusted to see how the threshold size increases/decreases.The analysis for each device was done by a parametric study using Design of Experiments (DOE). First the available features (both design and operation) were studied and suitable parameters and their values were selected. The DOE was then designed, having 27 combinations of parameters known as ‘runs’. Each run of the DOE was first simulated on an available 2D COMSOL model, followed by experimental validation. The DOE was then analysed using both theoretical and actual values, to find out the parameters that had the maximum effect on the threshold size, and their respective trends.