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  • 1.
    Fors, Jonathan
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Modeling and OpenFOAM simulation of streamers in transformer oil2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Electric breakdown in power transformers is preceded by pre-breakdown events such as streamers. The understanding of these phenomena is important in order to optimize liquid insulation systems. Earlier works have derived a model that describes streamers in transformer oil and utilized a finite element method to produce numerical solutions. This research investigates the consequences of changing the numerical method to a finite volume-based solver implemented in OpenFOAM. Using a standardized needle-sphere geometry, a number of oil and voltage combinations were simulated, and the results are for the most part similar to those produced by the previous method. In cases with differing results the change is attributed to the more stable numerical performance of the OpenFOAM solver. A proof of concept for the extension of the simulation from a two-dimensional axial symmetry to three dimensions is also presented.

  • 2.
    Lundberg, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Impact of increased production on TOC to the Waste Water Treatment Plant: Piteå 7502017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today there are strict demands regarding emissions to water and air from the Swedish industries. This degree project, conducted at Smurfit Kappa Piteå, will focus on the emissions of organic material in waste water from the paper mill. The overall goal was through dynamic simulations predict the Total Organic Carbon (TOC) emissions from the paper mill at the time a foreseen increase of production is implemented. The recovery boiler is currently a bottleneck in the process and the production of sulphate pulp has today its maximum capacity. This means that production growth will occur exclusively by increasing the intake of recycled fiber. The work started with a comprehensive mapping of TOC, in which ingoing pulps in pulp towers, head boxes and effluent flows were mapped. This was done over a period of two weeks and thus covered a whole production cycle. A TOC method evaluation was conducted where the most suitable analysis method was determined.

    Mapped data were thereupon evaluated and significant variables were identified. It was determined that use of recycled fiber was the single most important variable to TOC load from paper machine 1 (PM1), but also starch addition to paper machine 2 (PM2) was found to be significant.

    The work then continued with the simulation phase, consisting of two main parts. The first part consisted of preparatory work where the model was developed to be able to accurately measure TOC load to the waste water treatment plant. This part also included work to identify necessary process changes as a result of an increased production. The second part consisted of the simulation. Three different scenarios were simulated for each paper machine plus two scenarios for the recycled fiber plant. The dynamic simulation model was successively calibrated with respect to TOC concentration and trends followed the ones expected by experience. In the production increase scenario simulated, TOC load distribution between PM1, PM2 and recycled fiber plant will more evenly distributed compared to current production. The largest increase of TOC load will come from the recycled fiber plant, which according to the simulation will increase with about 30 %.

  • 3.
    Saarinen, Gabrielle
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Development of Synthetic Routes for Preparation of 2,6-Disubstituted Spiro[3.3]heptanes.2009Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    2,6-Disubstituted spiro[3.3]heptanes were synthesized to investigate and develop synthetic methods for preparation of these compounds. Possibilities for introducing different functionalities like nitriles and sulfonamides were also investigated.

     

    Synthetic routes presented describe successive [2+2] cycloadditions between dichloroketene and olefins to give the sought after spiro compounds with low to moderate yields throughout the multi-step synthesis. [2+2] Cycloadditions offered low turnovers and chromatography was required for purification.

     

    A synthetic route with cyclisations through double substitution reactions between di-electrophiles and di-nucleophiles resulting in a 2,6-disubstituted spiro[3.3]heptane is also described. This multi-step synthesis offered higher turnover and yields and often there was no need for purification through chromatography.

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