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  • 351.
    Åkerström, Niklas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ackumulatortank i PiteEnergis fjärrvärmenät2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 352.
    Åslund, David
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    PVT-panelernas plats i samhället: En vidareutveckling av Evertechs ETX-paneler2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    To prevent that the climate influences reaches critical and irreversible levels in the near future, a change in our energy consumption and our energy sources is required. It will be a combination of multiple system solutions and several types of renewable sources, both at a personal and national levels. Every hour, the sun shines at the earth with the same amount that the world's population needs in a year. It is clearly a small part of this that we could use, but it is easy to see the potential.

    Evertech is a company in Umeå, whose strategy is to develop products to extract and recycle heat energy from the solar renewable resource. The company has several products and all are based on a heat exchange panel. Together with the company the possibility of combining a solar module with Evertech's solar panel was tested for a hybrid to get better effect on the solar cell by cooling. Hybrids are also called PVT-modules (photovoltaic thermal).

    A system setup was made with a simple prototype to measure surface temperature and power difference when the solar cell was cooled by the heat exchanger absorber. The measurement study showed an increased effect of 8 % on average and a maximum of 15 %. At the time of maximum, a surface temperature difference between the solar cell and the hybrid was determined to 20°C while the average was at 15°C. A temperature gradient at the cooled module was detected, which inhibited the power increase. This indicates that a future product would have the ability to obtain higher values. 

    By combining the solar hybrid with a geothermal heating system, one could secure both the own heat supply and the electricity supply and at the same time have the possibility of recharge the mountain. This and how the systems can benefit from each other were studied in the simulation program Polysun. The primary goal of using a hybrid system is to create as high efficiency as possible on the solar cells and to improve the SPF value of the heat pump by allowing the heat carrier to circulate through the hybrids. The difference between the SPF-value of a hybrid system in conjunction with a geothermal system was 4.2 against the geothermal system 2.7. To cover up the increased electricity consumption that the circulation meant and the heat losses against a solar collector system did not become a problem.

    The results of the simulations and the economic study show that a PVT-panel built on Evertech's ETX-panel together with geothermal heat has equally good conditions for managing as solar cells or traditional solar collectors. The repayment period for a PVT module was 13,8 years for a 20 % solvency payment. For a solar cell plant of the same size it became 14,5 years. The PVT had the best return on investment of 1,2 % and an annual gain of 2000 Swedish kronor of the compared systems.

  • 353.
    Åström, Amanda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Flerbostadshuset Vasa 2: Simulering i IDA ICE av energibesparande åtgärder2016Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
  • 354.
    Öberg, Malin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Optimerade material för optiska komponenter i koncentrerande solfångare2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The energy consumption continues to increase as the use of electronics and energy consuming equipment increases. The use of fossil fuels has to be phased out for this to be sustainable in the long run while the use of renewable energy continues to increase. A renewable energy source is solar energy but the production of heat and electricity are today very expensive compared to other energy sources and an important task for the solar energy market to grow is therefore to minimize the production cost of the solar collectors while increasing its efficiency to produce heat and/or electricity. One way to convert solar energy into heat is by using solar collectors and electricity can be produced by utilizing the produced heat, or by applying solar cells.

    This thesis aims to recommend a reflective material for the next generation solar collectors from Absolicon and to recommend a commercially available coating for the receiver tube of the solar collector. A market study has been carried out to investigate the cost-related aspects along with the optical and durable aspects for the optical material of the solar collector. Experimental evaluations have been performed to ensure that the optical materials meet the requirements that the supplier promises. The optical properties have been evaluated with advanced measuring equipment at the Ångströmlaboratoriet at Uppsala University and with an infrared camera. The measured values from the infrared camera were in turn used to theoretically calculate the thermal losses of the receiver tubes. To investigate the materials durability the materials were subjected to different climates in a climate chamber and all the tests that has been conducted in this thesis have been carried out both before and after the climate chamber simulation to investigate the materials optical and physical durability. An important aspect of the laminated films is that they should have good adhesive properties even when subjected to high temperatures and high humidity and a method to evaluate this has been developed.

    The result of the thesis shows that aluminum reflectors obtain the best optical results for concentrated solar collectors, but since aluminum is not suitable for the Absolicon solar collector TC160 the recommended reflector material is SF2, which showed good optical, adherent and durable properties which is desirable for a good solar collector and a total reflectance of 92.4 % was obtained. The material that is recommended as a receiver tube is R2 with a measured absorptance of 95.9 %, an emissivity of 17.7 % and the thermal energy loss was calculated to 1055 W. R2 is durable in high humidity and temperatures of 85°C for over 300 hours without the optical characteristics deteriorated. Based on the recommended materials, the next generation solar collectors from Absolicon obtained a theoretical calculated optical efficiency of 76 %. 

  • 355. Öhman, M.
    et al.
    Pommer, L.
    Nordin, A.
    Bed agglomeration characteristics and mechanisms during gasification and combustion of biomass fuels2005In: Energy & Fuels, Vol. 19, no 4, p. 1742-1748Article in journal (Refereed)
    Abstract [en]

    Controlled agglomeration tests, using six representative biomass fuels (bark, Lucerne, reed canary grass, bagasse, olive flesh, and cane trash) were performed in a bench-scale fluidized bed (5 kW) during both gasification and combustion conditions. The resulting bed materials were analyzed using scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), and chemical equilibrium calculations were performed to facilitate the interpretation of the experimental findings. Layers of fuel-ash-derived compounds were built up on the bed particles during processing of all studied fuels. The accumulated material was determined to consist of two layers: (i) an inner thicker and more homogeneous layer that consisted of mainly K-Ca-silicates and (ii) a thinner, particle-rich outer layer. For all fuels except Lucerne, no major differences in bed agglomeration tendencies or bed particle layer characteristics could be detected between gasification and combustion, which suggested no major difference in layer formation processes or bed agglomeration mechanisms between the two different operational modes. Thus, initial silicate layer formation followed by subsequent viscous flow sintering and agglomeration was identified as the bed agglomeration process in all cases except during the combustion of Lucerne. For combustion of the relatively sulfur-rich Lucerne fuel, the agglomeration was induced by a salt melt where the bed material particles were directly glued together by a separate ash-particle-derived melt.

  • 356.
    Öhman, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Hedman, H
    Jirjis, R
    Reasons for slagging during stemwood pellet combustion and some measures for prevention2004In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 27, no 6, p. 597-605Article in journal (Refereed)
    Abstract [en]

    Ash related problems have more than occasionally been observed in pellet burners during the last years. These problems lead to reduced accessibility of the appliances and also bad publicity for the pellet market. The objectives of the present work were therefore to: (i) determine the critical levels of the problematic ash components in stemwood pellets regarding slagging, (ii) document the variations of these problematic elements in the outgoing pellets from two pellet-mills during one operational season, (iii) determine how frequently these elements exceed the critical levels, (iv) determine how different sub-processes in the pelletising process (especially the dryer) effect the slagging properties of the pellet, and if possible (v) suggest some measures for prevention. A significant number of wood pellets reported to be problematic and problem-free, regarding slagging in ordinary residential pellet burners, were collected from the Swedish market. The ash compositions of these fuels were analysed and the results compiled in a database. Partial Least-Squares Discriminant Analysis (PLS-DA) and F-tests were used to statistically identify both the critical ash components and the critical levels of these components that separated the two reported classes. In addition, chemical equilibrium model calculations were used to interpret the findings. The variations of these elements in the in-going raw material and in the produced pellets were determined during one season in two pellet mills equipped with exhaust gas dryers. The results showed that the problematic wood-pellets had a significantly higher amount of Si, but also Al and Fe, in the fuel ash. The critical level of Si (given as SiO2) was about 20-25 wt% of the fuel ash, i.e. pellets with levels in or over this range resulted in slagging problems in residential burners. This critical Si content was exceeded once and twice for the analysed samples in the two studied pellet mills. In one of the studied mills, this was because of contamination by sand of the raw material during storage and handling, and in the other mill the reason was found to be contamination of the raw material by elutriated particles from the dryer fuel. The major conclusion of the work is that both raw materials and drying fuels/processes should be carefully treated to avoid mineral contamination, and an additional cyclone separator could potentially also be used to improve the pellet quality.

  • 357.
    Öhman, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lundholm, Karin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Hedman, Hedman
    Energy Technology Centre, Piteå.
    Lundberg, Margareta
    Kvaerner Pulping AB, Power Division, Göteborg.
    Ash Transformations during Combustion of Meat-, Bonemeal, and RDF in a (bench-scale) Fluidized Bed Combustor2003In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 17, no 5, p. 1153-1159Article in journal (Refereed)
    Abstract [en]

    Following the recent Bovine spongiform encephalopathy (BSE) experiences, thermal treatment of meat- and bonemeal (MBM) in existing fluidized bed combustion (FBC) plants for refuse-derived fuels (RDFs) has evolved as an interesting disposal and disintegration method. However, only a limited number of studies have previously been performed for combustion of MBM in fluidized beds. The objectives of the present work were, therefore, to determine the bed agglomeration tendencies of these materials during combustion in fluidized beds and to evaluate the effects of dolomite and kaolin addition to the fuel mix, as well as to elucidate the overall ash transformation mechanisms governing the potential bed agglomeration and fouling processes. By controlled agglomeration experiments in a 5 kW bench-scale fluidized bed reactor, the fuel-specific critical agglomeration temperatures in normal quartz bed material were determined for the different fuel/additive mixtures. All collected samples of bed materials, final bed agglomerates, and cyclone ashes were analyzed using SEM/EDS and XRD. The results indicated that the MBM fuels could be expected to be problematic concerning bed agglomeration in normal quartz beds, while kaolin and possibly dolomite addition could be used to reduce this risk to moderate levels. A significant elemental fractionation between the bed material and the cyclone ash was obtained. Apatite (Ca5(PO4)3(OH) or potentially some other calcium phosphates are elutriated from the bed and enriched in the fly ash, while sodium and potassium are enriched in the bed material. The characteristics and the corresponding melting behavior estimations of the necks formed between agglomerated bed particles suggest that silicate melts are responsible for the bed agglomeration. Results from XRD analysis of the fly ash formed from the fuels used in the present study indicated that the risk for melt-related fly ash problems seem relatively small.

  • 358.
    Östergren, Simon
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energiutredning av en hälsocentral samt förbättringsarbete av modulen Energi & Miljö i DeDU2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Byggnadssektorn är en av de tre största områdena inom världens energianvändning och den står för ungefär en tredjedel av den totala energianvändningen. Det är därför av stor vikt att byggnadssektorn effektiviseras för en mer hållbar framtid.

    I det här examensarbetet var syftet att utföra en energiutredning på en hälsocentral med hjälp av energistatistik från modulen Energi & Miljö i WSP:s egenutvecklade programvara DeDU. Den andra delen i arbetet var att med erfarenheter från energiutredningen undersöka hur modulen Energi & Miljö kan förbättras för att bättre uppmärksamma dess användare på energianvändning.

    Energiutredningen utfördes med hjälp av konstruktionsritningar och energistatistik från DeDU för total fjärrvärmeanvändning, total elanvändning samt timvärden för elanvändningen. Fördelning mellan fastighetsel och verksamhetsel togs fram med hjälp av statistik från studien STIL2 utförd av Energimyndigheten. Det visade sig att Hörnefors hälsocentral är relativt energieffektiv sett till andra liknande fastigheter. Byggnadens klimatskal visade sig vara bra med ett Umedel på 0,45 W/m2K. Av de energieffektiviseringsförslag som togs fram visade det sig att förslaget med störst besparingspotential är byte av 2-glasfönster till 3-glasfönster.

    Förbättringsarbetet av modulen Energi & Miljö i DeDU utfördes genom en enkätundersökning, en workshop samt en undersökning av befintliga energirapporter för att ta fram förslag på nya rapporter. Från enkätundersökningen framkom det att de tillfrågade kunderna generellt är nöjda med modulen Energi & Miljö men att det finns önskemål om en del förbättringsförslag. Tre förslag på nya energirapporter kopplade till DeDU togs fram. Huvudsakliga tanken bakom förslag 1 och 2 var att ge kunderna möjlighet att lättare göra jämförelser mellan olika fastigheter/byggnader samt jämförelse av energianvändningen för samma fastighet/byggnad. Tanken med förslag 3 var att ge möjlighet att uppskatta olika verksamheters fördelning mellan fastighetsel och verksamhetsel. Slutligen kan det konstateras att det är fördelaktigt att presentera färdig förbättringsförslag, då de flesta kunder inte själva vet vad de behöver eller vad som saknas.

  • 359.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energieffektivt byggande i kallt klimat2012In: Bygg & teknik, ISSN 0281-658X, Vol. 104, no 8, p. 39-42Article in journal (Other (popular science, discussion, etc.))
  • 360.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Evaluation of a Single Family Low Energy Building in Cold Climate2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 132, p. 9-14Article in journal (Refereed)
    Abstract [en]

    Verification of energy performance and indoor climate by detailed field measurements in buildings is of great importance and promotes an assurance in the process of constructing low energy buildings and enables to utilize the full potential of energy efficiency measures.

    In the present work a single family building with a heated living space area of 175 m2 has been monitored. The heating system has a wood pellet stove for space heating (SH) and domestic hot water (DHW) and on the roof there are solar collectors in a southerly direction contributing to SH and DHW. SH is distributed by the ventilation system and an under floor heating system which is connected to a heat storage water tank. The incoming outdoor air is pre-heated in an earth-to-air heat exchanger and the building has a measured specific energy usage of 54 kWh/m2year which is far lower than today’s regulation at 130 kWh/m2year in the actual climate zone. The low energy use in the building are due to thick thermal insulation (average Um = 0.18 W/°C m2), an air tight envelope (q50 = 0.165 l/sm2), heat recovery of exhaust air (average 74 % efficiency) and free heat from the ground pre-heating of supply air which is above 2°C even for outdoor temperatures down to -27°C. An essential factor was the low rate of air changes during the heating season about 40 % of the regulated requirement. Measurements of indoor air quality like carbon dioxide occasionally indicated insufficient ventilation.

  • 361.
    Östin, Ronny
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Eklund, Erik
    Johansson, Christer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energieffektivt byggande i kallt klimat2012Report (Other academic)
    Abstract [en]

    The project Energy efficient construction in cold climate is a study of six newly produced low energy buildings in the region of Umeå. Four buildings are houses and two residential buildings which are located from Sikeå up north to Nordmaling down south.

    The buildings have been equipped with wireless logger system for collecting data of energy performance for the entire building and for individual components of the energy system. Loggers for relative humidity and temperature have been placed in ventilation and the buildings construction shell. The later of the position of loggers have been placed in different depths of the constructions isolating shell.

    The purpose of this study is to investigate these buildings energy performance and what risks constructing energy efficient buildings in cold climate due to humidity. The relative humidity and temperature sensors located in the construction shell show no signs of risk for rotting and mold. Moisture migration is a slow process and to be certain longer measurements are required.

    With the method called energy signature the measured energy usage have been normal corrected by year and the average U-value calculated. Expected energy usage and average U-value is compared to our measured data in this report.

    Two buildings in the study are equipped with a buried pipe for supply air which is 36m and 10 m long. The longest (36m) shows a big increase of air temperature (from -25°C outside to +°2 at the inlet connecting to the heat exchanger). This by means no extra heat is required for the inlet air to reach comfortable temperature.

    The measurement of energy displays that constructing buildings with lower energy use then the Swedish Boverkets requirements are confirmed. The houses shows a specific energy usage as Boverkets definition (energy for heating and for domestic hot water per heated surface area) from 59.7 to 91.8 kWh/m2, year and the residential buildings from 68 to 75.5 kWh/m2, year which are lower than today regulations at 130 kWh/m2, year and 95 kWh/m2, year for electric heated.

  • 362.
    Östling, Ida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Life cycle analysis as a tool for CO2 mitigation in the building sector2018Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
  • 363.
    Östling, Ida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Life cycle analysis as a tool for CO2 mitigation in the building sector2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    After the Paris agreement 2015 the Energy Commission in Sweden proposed a goal for Sweden of net zero greenhouse gas emissions by 2045. The focus in this report has been on how buildings in Sweden could reduce their greenhouse gas emissions. Year 2017 the government gave a task for Boverket in Sweden (National Board of Housing, Building and Planning) to investigate the possibility to introduce a climate declaration on buildings. The idea is a life cycle analysis (LCA) should be performed on the building in order to get a building permit. An LCA include all CO2 emissions emitted from resources used for raw material extraction, production of materials, construction site operations, user phase and also the demolition and disposal in the end of life of the building. The first draft from Boverket was published in February 2018 where they recommended a simple declaration. They recommended in the beginning to only include a few components in the declaration, and to only include the production phase. The major interest in this report have been to gain more understanding on how to perform LCAs and also how the LCA result could be used to decrease CO2 emissions. A case study was made on a residential building project called Mården, in Umeå Sweden.

    The first part in this thesis was to determine the phase in the buildings life cycle with the largest potential for decreasing CO2 emissions. When the LCA was performed on case study building Mården it was difficult to use exact data, since only 20 % of the construction products where declared in an environmental product declaration (EPD). Therefore the other 80 % where approximated with similar products declared in an EPD, or with generic data (general data for a type of product). An EPD is an LCA on a single product and could therefore give exact information on CO2 emissions for a specific product. However, several improvements where implemented in the buildings life cycle and where compared with this reference case. The result from the LCA showed the energy use in the user phase emitted the largest amount of CO2 emissions, and therefore also where the phase with the largest potential for reducing CO2 emissions. When the Swedish district heating mix where replaced with an energy source with 50 % less CO2 emissions, the emissions for the whole life cycle could be decreased with 20 %. Smaller improvements such as more environmental friendlier concrete, shorter transport distance between manufacturer and construction site or less water usage resulted in a decrease by 1.6-7 %. It was though shown these smaller improvement could result in a large decrease of CO2 emissions if more buildings also would improve the same thing. 2.4 million tons of CO2 emissions could for example be reduced in Sweden if 50 % of Sweden’s all new building projects would improve their choice of concrete. To make sure buildings could reduce their CO2 emissions there is important LCAs are performed before the building is constructed, to make sure all phases in the life cycle can be improved. If an LCA will be performed when the building is constructed, it is only possible to improve a few parts in the user phase, since the other phases already have passed.

    The second part in this thesis was to compare the different LCA softwares; (i) One Click LCA (needs license, from Finland), (ii) e-tool (free, from Australia) and (iii) BM (free, from Sweden). When more exact data were tried to be used in e-tool and One Click LCA the results were similar for the CO2 emissions from the production phase. E-tool only resulted in 6 % higher CO2 emissions in the production phase than One Click LCA. The LCA in the eventual future climate declaration will probably be performed with generic data, since in an early stage the contractors will not have detailed information on their construction products. An LCA was thus performed in each software with generic data, and the result differed a lot. The CO2 emissions from the production phase resulted in 36 % and 23 % less CO2 emissions in BM and e-tool than in One Click LCA. If several softwares will be allowed in this eventual climate declaration, the judgment could be difficult since different generic data is used in each sofware. The generic data were also different for one type of product in a single software, where the CO2 emission could differ with as much as 50 % between two types of generic data for one type of products. This leads to a difficulty when choosing generic data since there will be lack of information on the construction products at the time when this eventual climate declaration should be performed. A main focus for the future development should be on evaluating a standard database that could be used in EU.

    If a future law will be implemented it could be valuable to declare detailed rules on how to perform the LCA. Since depending on who will perform the LCA different results could occur due to different data used or assumptions on things like products, boundaries or used resource. However, this master thesis has shown there is possible to use the LCA methodology to find solutions for decreasing the CO2 emissions for buildings.

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