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Corrosion Assessment of Materials for a Chemical Looping Combustion Air Reactor Used for Carbon Capture and Storage
(2025) Ataia, Mohammad; Fuhrman, David
Chemical Looping Combustion (CLC) with Carbon Capture and Storage (CCS) has shown promising advancement regarding carbon negative emissions. To increase the electrical efficiency of CLC, optimized corrosion resistance of the superheaters is crucial. This study focused on the air reactor (AR) of the CLC system at 600 °C and its potential corrosion hot spots at the superheaters. Six different alloys were tested in a clean and an alkali slip (0.5 ppm KOH) laboratory environment. Through gravimetric measurements and scanning electron microscope micrographs, the results showed that the Ni-based alloys and the ferritic FeCrAl alloys performed best from a corrosion point of view. Ferritic steels and austenitic stainless steels strengthened the issue by showing poorer gravimetric and micrographic results.
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Assessment of Stormwater Pond Performance through Water Quality Analysis and Hydrodynamic Modeling
(2025) Wenning, Sophia; Wallgren, Felicia
Traffic-related pollutants in stormwater runoff pose growing risks to aquatic ecosystems and human health. While stormwater ponds are commonly used to retain sediments, their efficiency in capturing emerging pollutants, such as tire wear particles (TWP), is less understood. This thesis combines field sampling and 3D hydrodynamic modeling to investigate pollutant retention and particle transport in a stormwater pond. For a field sampling campaign at a pond in Sweden, ISCO samplers were used to col lect water samples at inlet and outlet. Flow meters which monitored inflow and out flow during rain events were used and connected to the ISCO samplers to trigger sam pling at specific water flows. Laboratory analysis included pH, conductivity, suspended solids, nutrients, metals, and organic carbon. Results show that most pollutant loads are reduced through the pond, with outlet concentrations generally below guidelines. However, exceedances of total organic carbon and total nitrogen after long dry periods suggest pollutant build up between events. To further explore transport mechanisms, a 3D model of the pond was developed in MIKE 3 FM, simulating six scenarios: three with constant flow and three based on ob served rain events. Velocity patterns throughout the entire pond were analyzed based on hydrodynamic behavior. Particle tracking of particles with sizes and density of TWP was conducted for three scenarios to assess the behavior of size-defined particle classes under different hydrodynamic conditions. These results however were deemed unreli able as great mass losses were discovered when performing mass balance calculations. Whilst unreliable, the result from the particle tracking does indicated a strong size dependent settling pattern with larger TWP (100 µm) settling rapidly near the inlet, while finer TWP (10 µm) showed higher mobility, particularly under sustained or high inflow conditions. The results also indicates that rain intensity and wind affects the settling near the inlet. Overall, the study highlights the ponds’ capacity to retain coarse traffic-related parti cles, but also points to the need for more detailed modeling of finer particles. Recom mendations regarding management of pond and further investigation into pond perfor mance include careful vegetation management, and performing modeling that includes antecedent conditions and current vegetation near inlet, and also sensitivity analyses of particle properties to have an even better understanding of transport and sedimentation of emerging pollutants like TWP and microplastics.
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Method Development of Multi-Layered Optical Skin Phantoms
(2025) Louise, Eckerström
The increasing research interest in and use of optical medical technologies has led to a growing need for synthetic testing materials with tissue-mimicking optical properties, known as optical phantoms. Many different materials and methods have been used to create such phantoms but the field currently lacks standardization and repeated results. Optical phantoms made for dark skin tones and for short wavelengths of light are also missing from research. This project tests and builds on previously established methods for creating optical phantoms made out of PDMS silicone. A method for creating a multi-layered skin phantom in which each layer mimics the thickness and absorption of one of the main layers of human skin is developed and presented. Four versions of this phantom are made: two of them mimic the absorption of fair skin and two of them the absorption of dark skin. For each skin colour, one of the phantoms mimic the absorption at a wavelength of 405 nm and the other the absorption at 630 nm. A correlation between the concentration of nigrosin (an absorbing agent) and the absorption coefficient of the resulting phantoms is determined using spectrometry. This correlation can work as a guide for how to reach a desired absorption coefficient.
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Undersökning av hydroxylapatits inverkan på magnesiumytor i kroppens miljö genom atomskaliga beräkningar
(2025) Forster, Ablai; Hansson, Tim; Jernstedt, Alexandra; Salminen, Emmy; Veit Berg, Anthony
Magnesium visar stor potential att användas som ett material i nedbrytbara implantat för benstabilisering. Då magnesium lätt korroderar är det aktuellt att öka korrosionsmotståndet genom legering eller ytbehandling. I detta arbete används density functional theory (DFT) för att undersöka om ytbehandlingen hydroxylapatit (HAp) binder till en Mg(0001)-yta, både med och utan legering, och om det påverkar korrosionsmotståndet. I vakuum binder HAp till magnesiumytan, och bindningen förstärks ytterligare vid zinkdopning samt när det översta lagret består av magnesiumhydroxid. Trovärdiga resultat i en simulerad vattenmiljö erhölls ej, men indikerar att vattenmiljön minskar bindningsstyrkan mellan HAp och magnesiumytan. I vakuum ökade bindningsstyrkan mellan HAp och Mg(0001)-ytan i närvaron av en Na+-jon, medan närvaron av en Cl– -jon minskade den. När Na+ och Cl– var närvarande i lika mängder band HAp starkare till ytan än utan joner närvarande. Bindningsstyrkan mellan flera lager av HAp och Mg(0001)-ytan visar att för många lager av HAp är mindre gynnsamt energimässigt och att två lager av HAp verkar vara en optimal gräns. Sammanfattningsvis är nästa steg att undersöka bindningsenergier i ett system som använder vattenmolekyler istället för ett potentialfält och ifall flera lager av HAp följer samma trend med ett utökat antal lager HAp.