En tredjedel av Kirunas stad är på väg att flyttas och med det kommer nya möjligheter för en utveckling av den nya stadsdelen. Kiruna stad vill bygga ett attraktivt och hållbart samhälle som utnyttjar ny teknik för en energi- och resurssmart stadsmiljö. Fjärde generationens fjärrvärme eller 4GDH som det oftast förkortas är ett koncept som tagits fram för att öka fjärrvärmens konkurrenskraft samt öka dess attraktivitet för kunder. Detta projekt har genomfört en utredning för 4GDH i ett område i nya Kiruna där värmeprofiler har tagits fram med hjälp av CFD-programmet Comsol och en teknoekonomisk analys har utförts där olika alternativ på 4GDH jämförs mot varandra och mot den traditionella fjärrvärmen som finns idag. En ny teknik har undersökts som benämns samförläggning vilket innebär att flera tekniker förläggs i samma schakt. I rapporten redovisas viktiga resultat från simuleringar över nätet i Comsol, där hastigheter, temperaturfall och termiska förluster tas fram för flera olika varianter på nätets dimensionering för att sedan jämföras för att hitta det bästa alternativet. Den teknoekonomiska analysen visar att 4GDH är att föredra framför traditionell fjärrvärme med en besparing på drygt 3 miljoner kronor sett över rörens livslängd på 50 år.

This master thesis aims to develop an assessment tool for decision-making regarding future establishment of low-temperature district heating (LTDH). The tool is created as an indicator system on behalf of Södertörns Fjärrvärme AB (SFAB). SFAB is currently responsible for the distribution of high-temperature district heating (HTDH) to customers in the municipalities of Huddinge, Botkyrka, and Salem. The indicator system is designed to, in a first assessment step, examine the conditions that a delimited area has for conversion to lower system temperatures to be possible. Each indicator is quantified and graded. When using the system, a weighted final judgement is generated which indicates whether an area is suitable for LTDH or not. Furthermore, the purpose of this thesis is to also evaluate the tool by applying it to various areas within SFAB. This enables analysis and discussion regarding the tool's function in a real context. The development of the indicator system is the main result of the study. It consists of four indicators that take the following aspects into account: qualitative conditions (KA), conditions on the customer side (AA), the economic benefit (CRG), and the system condition (STA). The results from the implementation show that one out of five case-areas have good potential to be converted to LTDH, while the remaining cases fall below the limit for what is considered acceptable. No area from this project ends up over 75% of the maximum score, which would indicate very good potential. To validate the indicators, Pearson's correlation coefficient was calculated. The results show that there is a negligible to a weak correlation between all indicators, except KA & STA which has a strong correlation. For an HTDH area to be relevant for conversion to LTDH, the qualitative context of the area should be suitable, and the secondary side should be able to be supplied with lower temperatures. Furthermore, there should be an opportunity for increased system capacity and finally, a conversion should be economically beneficial. The application of the indicator system is an efficient and uncomplicated approach that makes it possible to identify areas that have the potential to develop district heating in a more sustainable direction. It is also possible for stakeholders to subsequently modify the indicator system if desired. In the longer term, the indicator system is an incentive for new business opportunities, increased energy efficiency, and increased economic benefits.

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.