Examensarbeten för masterexamen
Länka till denna samling:
Browse
Senast publicerade
- PostComparison of CLC with existing CCS technologies: based on Energy, Exergy and Techno-economic analysisPramode, Avinash; Dhait, Abhie; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Leion, Henrik; Dattarao Surywanshi, GajananClimate change is an immediate global crisis that is driven by the accumulation of greenhouse gases, primarily carbon dioxide, in the Earth´s atmosphere. Carbon Capture and Storage (CCS) technologies play a pivotal role in reducing our carbon footprint as we move towards a more sustainable future. This study aims to compare four different carbon capture technologies and evaluate them based on techno-economic analysis, energy analysis and exergy analysis. The four technologies under evaluation are chemical looping combustion (CLC), oxy-fuel combustion, post-combustion, and pre-combustion. The process modelling of the four systems for a selected combined heat and power (CHP) plant is used to carry out this comparison, which is next followed by energy, energy-related, and economic analysis. The modelling of these four plants was conducted using Aspen Plus simulation software and validated using the results given in the literature. The study reveals that the CLC capturing technology outperforms other CCS processes regarding cost efficiency, CO2 capture rate and electrical efficiency. The highest overall efficiency was observed for Oxyfuel combustion but the CLC plant has the best net electric efficiency. For the CLC model, An almost pure stream of CO2 is extracted from the Fuel reactor which is then subsequently compressed after heat extraction. The CLC has the highest CO2 capture rate among the four models for this reason. From the exergy analysis, it becomes clear that the most exergy destruction takes place in the combustion process for all the cases and that it needs to be optimized to improve overall efficiency. The comparison of the overall exergy destruction of the models shows us that CLC has the least exergy destroyed and thus has the highest exergy efficiency, despite incurring higher initial expenses, CLC displays the lowest levelized cost of electricity (LCOE) and payback period when compared with all the other technologies. This indicates that CLC has been estimated to be the most economical choice over the long term, despite necessitating a more substantial initial expenditure. To sum up, this case study offers insightful information about the advancement of CLC technology and its advantage over competing carbon capture solutions. The results provide a useful manual for energy sector decision-makers, highlighting how important it is to select the appropriate carbon capture and combustion technology with the intent to optimise performance and economics
- PostHydrogen and battery storage for local power generation and supply: A feasibility study for Forsåker(2024) Wademyr, Marcus; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Palmqvist, Anders; Bodén, Andreas; Fredriksson, PeterSamhället står inför en stor omställning av energisystemet där fossila bränslen behöver fasas ut och ersättas av förnybar energiproduktion, vilket ställer nya krav på mobilitetstjänster, byggarbetsplatser och tunga fordon. Kraven på energieffektivitet i nya byggnader blir därmed strängare, intresset för fastighetsutvecklare att vara mer hållbara både i förvaltningsskede och under byggfasen ökar. Lokal produktion av värme och elektricitet samt mellanlagring blir viktigare för fastighetsutvecklaren. Att införa dessa nya tekniker i fastigheter ger nya möjligheter men också utmaningar. Arbetet handlar om att undersöka produktion och lagring av förnybar energi i fastighetsutvecklingsområdet Forsåker. Arbetet syftar till att öka kompetensen inom energihantering av energisystem bestående av lokal vätgas- och batterilagring, kombinerat med lokal produktion och konsumtion av elektricitet, samt sektorsintegration för fordon. Uppsatsen har genomförts parallellt med förstudien ScALES, ett konsortium av företag. Förstudien grundar sig på ett pågående utvecklingsprojekt i Västra Götalandsregionen, Forsåker i Mölndal. Projektet omfattar energibehovet för 245 000 m2 fastigheter, laddning av batteridrivna fordon samt lokal elproduktion bestående av vattenkraftverk, vindkraft, solpaneler på fasader och på tak, samt en solcellspark intill stadsdelen. Resultaten tyder på att Forsåker har möjlighet att uppnå en hög grad av självförsörjning. Vid en kris kan energilagringssystemet täcka stadsdelens energibehov och hålla den fungerande i timmar till veckor, beroende på omständigheter som tillgången till lokal produktion och årstiden. Detta kräver stora investeringar i solcellsparker, lokal vattenkraft och energilagringskomponenter utöver elproduktion på byggnader. På grund av osäkerhet kring många parametrar för 2031 då alla byggnader är färdigbyggda har studien undersökt olika scenarier för att ge vägledning för fastighetsägare, politiska beslutsfattare och andra intressenter som är involverade i beslutsfattandet kring stadsutvecklingsprojekt. Fler gröna investeringar skulle öka Sveriges möjligheter att nå sina klimatmål. För att öka attraktiviteten och viljan att investera i förnybar energiproduktion och lagringskomponenter för stadsdelar har studien identifierat två betydande parametrar. Det ena är att beslutsfattare bör tillåta energidelning för stadsdelar likt Forsåker, och det andra är att den ekonomiska hållbarheten i de undersökta scenarierna får behålla skattebefrielsen för elimporten som används i produktionen av grön vätgas genom elektrolys. Dessa två parametrar skulle inte bara öka investeringsviljan i området utan också underlätta övergången inom transportsektorn, eftersom energisystemet också kan tillhandahålla elektricitet och/eller vätgas för att driva framtida fordon. Att hitta en bra balans mellan de olika lagringskomponenterna är viktigt för att minimera kapitalkostnaderna (CAPEX). Ytterligare optimering av energisystemet är avgörande för att hitta en balans när och med vilken effekt de olika lagringskomponenterna ska starta och stoppa, när systemet ska köpa och sälja el till det regionala elnätet. Balansen i det undersökta systemet är fungerande men inte ännu optimerat.
- PostCyclic carbonates as green reactants for improving thermoplastic properties of lignocellulosic materials(2023) Tansatien, Rattanapon; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Larsson, Anette; Henrik-Klemens, Åke; Jonasson, KatarinaLignocellulosic materials are attractive raw materials for producing thermoplastics with more sustainable manufacturing. They come from a renewable source that can reduce the dependency on conventional fossil-based feedstock and has good tensile properties. However, their polymeric chains have poor mobility because of the multiple hydrogen bonds of their hydroxyl groups, which is an essential obstacle for thermoplastic processing. To improve their thermoplasticity, their hydroxyl groups can be converted by chemical modifications that introduce the side groups that can increase the flowability of their chains. In this study, unbleached softwood kraft pulp was oxyalkylated with cyclic carbonates (propylene carbonate and ethylene carbonate), acting as a reactant and medium. These two reactants create low environmental impacts because of their biodegradability and low toxicity. In addition, they are also safer compounds from their high boiling point, flash point, and vapor pressure. The influence of temperature, catalysts, and reaction time were investigated. The molecular structures, purity, and thermal properties of the modified products were also evaluated. The chemical modification with ethylene carbonate provides the highest yields and appears to be the most effective pathway to substitute hydroxyl groups with the alkyl side chains. In addition, the products from the chemical modifications with ethylene carbonate have a higher purity and are easier to separate than the products from the chemical modifications with propylene carbonate. Increasing the temperature and amount of catalyst promotes the substitutions on the hydroxyl group. Finally, the modified pulp from chemical modification with ethylene carbonate at a higher temperature and amount of catalyst has better thermal properties than the unmodified pulp. The glass-transition temperature (Tg) of the modified pulp can be detected at approximately 180 °C while the Tg of its raw material is above 220 °C, so the polymeric chains of modified pulp become more flowable.
- PostIn situ synthesis of gold nanorods on SiO₂-substrates(2023) Wilson, Sean; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Andersson, Martin; Hulander, Mats; Uusitalo, MajaThe implantation of a medical device introduces a high risk of infection and bacterial biofilm formation on the device surface. These biomaterials-associated infections (BAI) are difficult to treat using conventional methods, such as high dosages of antibiotic treatments, as the bacteria are protected by the biofilm. A promising treatment is to modify the implant surfaces with gold nanorods, which can photothermally eradicate bacteria beneath the biofilm with heat generated from localized surface plasmon resonance (LSPR). As such there is a need to develop methods that reliably produce gold nanorods of a size that produces LSPR at wavelengths within the biological window and that stably bind the particles to the material surface homogeneously. In this thesis, a method has been developed to grow gold nanorods in situ on SiO2-glass and silicon wafers by binding gold nanoparticle seeds to surfaces using (3-Mercaptopropyl)- trimethoxysilane (MPTMS) as a linking molecule. The seeds were then grown into rods using a modified growth solution. The method has also been adapted to surface sensitive analysis to demonstrate the increased possibility to study anisotropic nanoparticles this method brings. In situ quartz crystal microbalance (QCM-D) analysis was used to study the formation of the self-assembled monolayer of MPTMS, the chemisorption of gold nanoparticle seeds, and how the growth rates of the particles vary over time, possibly due to both their increasing size as well as variations in solution concentrations. The developed method produced nanorods with a demonstrated rod yield of ~69% directly on SiO2-glass surfaces. The rods had an aspect ratio (AR) that could be customised to tune the wavelength of LSPR. The ability to tune the optical properties of the rods could allow this method to be used to grow gold nanorods for other applications, such as sensing, as well. Here the tuning was used to demonstrate the effect of silver ions within the growth solution and to produce nanorods with LSPR at the near infrared (NIR) wavelength of ~800nm in the biological window.
- PostGoldfinger, Solvent extraction of gold(2023) Johansson, Richard; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Foreman, Mark; Foreman, MarkThis is a project about the purification of gold at 25 ºC during recycling by solvent extraction. The solvent extraction of gold from chloride media (slightly acidic sodium chloride, choline chloride and a combination of ethylene glycol and choline chloride) by solutions of Aliquat 336 in 3,7-dimethyloctanol was investigated. The 3,7-dimethyloctanol is a semisynthetic diluent which can be obtained by simple chemical processing of a terpene (geranyl acetate) obtained from plants. The behavior of potential impurity metals such as copper, lead, palladium, and zinc, in the solvent extraction purification was assessed. An impure gold solution obtained from scrap gold was successfully purified into a pure gold solution by using a deep eutectic solvent (DES) as the stripping agent made of choline chloride and ethylene glycol at a 1:2 ratio. There is an increasing interest in making solvent extraction more environmentally friendly by using new and green solvents. Deep eutectic solvents (DESs) are a new group of greener solvents that have similar properties as ionic liquids (ILs). The solvent extraction of gold was modelled mathematically, the work included estimations of the random errors. Pitzer and SIT theory was used in the modelling and the parameters for Pitzer and SIT equations were obtained.