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Senast inlagda

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Exploring the Viability of Using WtE Incineration Ash as a Cement Replacement in Concrete
Eriksson, Joel; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Baba Ahmadi, Arezou; Karlfeldt Fedje, Karin
The increasing importance of reducing greenhouse gas emissions demands new environmentally sustainable building materials. In the concrete industry most of the emissions comes from the production of cement. Research on materials that can be used as replacements for cement (SCMs) could help reduce the climate impact of the concrete industry. One of the possible SCMs that could be used are ash from WtE incineration. In this report the viability of the use of three different ash fractions from WtE incineration as cement replacement are be evaluated. These are a fly ash sample, an incinerator bottom ash sample and a mineral fraction incinerator bottom ash sample. Chemical and mechanical properties was evaluated using different techniques including a modified R3 method, compressive strength tests, PXRD and leaching tests with ICP-MS. It was found that all three of the ash fractions had chemical reactivity and the mechanical strength tests suggested that two of the ash fractions fly ash and MIBA had effect on the mechanical strength while the slag did not have ant effect. The results from the leaching tests were compared to thresholds on allowed limits of leaching from monolithic concrete samples and found to be below these thresholds. However, the limited knowledge and regulations on monolithic samples made the interpretation of these results difficult. The result from this thesis suggests that the use of WtE incineration ash a SCM is a possibility but that more research is needed. It is also concluded that the need for more and less complicated to understand regulations regarding leaching from monolithic concrete is needed in Sweden and that the current lack of regulations might be hindering the adoption of new sustainable building materials.
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Establishing photovoltaics in Sweden - A critical analysis of land use and win-win scenarios2024
(2024) Belzons Berthelemot, Oskar; Chalmers tekniska högskola / Institutionen för rymd-, geo- och miljövetenskap; Chalmers University of Technology / Department of Space, Earth and Environment; Berndes, Göran; Cederberg, Christel
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Life Cycle Thinking in Small and Medium Sized Enterprises A case study of SMEs in the renewable energy industry
(2024) Eriksson, Emil; Nyberg, Joanna; Chalmers tekniska högskola / Institutionen för teknikens ekonomi och organisation; Chalmers University of Technology / Department of Technology Management and Economics; Nyström Claesson, Anna; Rydberg, Maria
This thesis explored the adoption and learning process of Life Cycle Thinking (LCT) among small and medium-sized enterprises (SMEs) in the renewable energy sector. As environmental sustainability has become more imperative, SMEs, representing a significant portion of businesses and carbon emissions in the EU, faced unique chal- lenges in implementing sustainable practices due to limited resources. This study, conducted in collaboration with the Swedish Life Cycle Centre, aimed to identify key challenges and needs in the greening process of SMEs. Through two qualitat- ive methods, a literature review and a case study based on interviews, the research investigated how SMEs adopted LCT, the components involved in their learning process, and strategies to advance their learning. Findings indicated that while SMEs exhibited a range of greening activities, these varied significantly based on company size and resources. Key steps in the learning process included recognising internal ambition, targeting easily achievable improvements, and fostering collab- oration within the supply chain. The study highlighted the necessity of adopting standards and frameworks to streamline LCT adoption. The research underscored the importance of tailored support from stakeholders and a supportive organisational culture in fostering sustainable practices. SMEs could advance their learning by em- bracing a triple loop learning mindset, incorporating strategic work, and leveraging stakeholder support eectively.
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On the estimation of diesel particulate filter particulate load based on pressure difference
(2024) Munthahar, Sayid Achmad; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Sjöblom, Jonas; Della Vedova, Marco L.
Stricter particulate emission regulations have led to the use of Diesel Particulate Filters (DPF), which is one of the exhaust aftertreatment systems utilized to capture engine-out particulates. However, as particulates accumulate within the DPF, the exhaust pressure drop increases which in turn decreases the overall powertrain efficiency. This necessitates an estimation of particulate load for effective regeneration control–a process to oxidize the soot deposits. This thesis evaluates pressure dropbased particulate load estimation by utilizing recursive Least Squares method to estimate the normalized pressure drop. The study reveals the challenges in achieving high accuracy due to the complex nature of the micro-characteristics of the particulates. Moreover, the author explores alternative applications for pressure difference sensors beyond direct particulate load estimation.
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Optimization and evaluation of subsea cooling for the offshore wind industry
(2024) Täck, Elsa; Blomberg, Jonathan; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Ström, Henrik; Riström, Anton
With an expanding energy market and an increasing focus on developing green, reliable and sustainable energy, the demand has never been greater for new innovations meeting these criteria. Today, offshore wind stands as a front-runner amongst the renewable energy alternatives. For the technology to be truly competitive against fossil fuels, the method of transporting large amounts of generated power long distances must be improved. High Voltage Direct Current (HVDC) has proven to be a promising technology offering low transmission losses over greater distances. However, the conversion process from Alternating Current (AC) to Direct Current (DC) which takes place on offshore HVDC platforms is generating a significant amount of heat, resulting in a high cooling demand. Conventional cooling systems are energy consuming and utilize chemicals in the cooling process which are discharged to sea. This thesis has investigated an alternative cooling solution, utilizing subsea cooling and a closed loop. The alternative cooling solutions is free of chemicals and was found to be far more energy-efficient in terms of operating cost compared to conventional cooling. The thesis also screened the future market for HVDC platforms in the North Sea and its cooling demand, by conducting a progressive market screening. It was concluded that the market is set to triple in terms of amount of HVDC platforms to be established and seven-fold in terms of installed converting capacity over the next seven years. A passive subsea cooler, operating in a closed loop utilizes natural convection and has a unique design to withstand shallow water conditions and lower coolant temperatures. Computational fluid dynamics (CFD) simulations have been performed to evaluate different cases of pipe arrangement and chimney designs to investigate the performance of the proposed subsea cooler. Manufacturing possibilities and their implications were also investigated together with a techno-economic discussion which presents various design alternatives. The study has concluded that, compared to existing technologies in the market, the closed loop cooling system decreases overall operating energy consumption and removes chemical pollutants that previously have been the base case for cooling offshore HVDC platforms. CFD simulations were proven to be an important tool in testing the passive subsea cooler performance. It was identified that baffles and large temperature differences are crucial in enhancing a passive subsea cooler. The thesis also managed to reduce computational time for the full 3D simulation by 96%, to test the chimney design.