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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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ÖVERTEMPERERAD FJÄRRVÄRME : En studie om Mälarenergis förluster på grund av förhöjd temperatur på fjärrvärmenätetKarlsson, Johan January 2023 (has links)
Mälarenergi AB is a company that produces district heating to many people in and around Västerås city in Sweden. The problem is that there is one customer, Lantmännen, who need 90℃ district heating when the rest of the district heating network only need 80℃, which creates losses. Previous research shows that lower temperatures in the supply temperature will reduce the losses. The main reason for this thesis is to understand how big the losses are due to the warmer supply temperature that Lantmännen need and if there is a solution for the problem. The main method that has been used is hour for hour values in excel, the values have been calculated to alfa-value, marginal cost, losses on the district heating network and loses in electricity sales due to higher supply temperature. The results have mostly been presented in diagrams, some results have been in numbers. The study has found that 2021 did Mälarnergi lose 954 000 kr and in 2022 4 962 000 kr in electricity sales due to the higher supply temperature in August to October. The extra losses on the district heating network system due to higher supply temperature was 2021 4 630 MWh and in 2022 6 600 MWh. The proposed solution is that when Lantmännen moves they need to be connected to the district heating line that goes to the underground storage, which is a separate line. The losses will therefore decrease on the whole district heating network.
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Simulering av vattenburen golvvärme med finita elementmetoden : värmeavgivning vid olika mönster för rörläggning / Simulation of Hydronic Underfloor Heating With the Finite Element Method : Heat Release From Different Heating Pipe Patterns in ConstructionNyberg, Joakim January 2023 (has links)
This report formulates the boundary conditions and discretization method for conducting a simulation of heat with liquids and solids through the finite element method. It introduces the reader to the movement that is due today with optimization of heat transport and mitigation generally described as the fourth generation of district heating. It presents the scope: calculating the heat release from pipes in hydronic underfloor heating, and presents the belonging question: how does heat release from different heating pipe patterns affect the body’s heat transfer? Simulation of the work is conducted with the delimitations of using a single boundary slip condition addressing friction and only using water as pipe flow medium. It focuses on the pattern’s ability to affect the heat to the body, of which characteristically manifests a square concrete slab in the running simulations. By using different cases, it analyses how patterns using the same length of pipes emit their average heat to the covering top surface differently, both as the heating level alternates, and duration for response changes. This meanwhile they are affected by analog boundary temperature conditions. A sensitivity analysis is done answering how the various patterns tested are affected by change of propagation speed for the flowing medium, showing that a spiral formed pattern with evenly spread piping is the least affected. The results show that the pattern with alternating pipe spacing gives the best average heat emission in the simulated cases. It also concludes that minor changes in the pattern area will have profound effect on the average transferred heat from the body’s top surface.
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