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  • 201.
    Norberg, Patrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utredning av övertonsproblematik vid Bolidens industriella nät2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Inside the industrial grid located in Boliden the presence of harmonic current is so high that It causes a total harmonic distortion of 12% in the voltage.  There is a large number of non-linear loads that can cause this distortion connected to the grid, furthermore there is phase compensating equipment connected that may enhance harmonic currents due to resonance. To investigate the cause and the consequences of harmonics in the grid measurements are conducted during four different modes of operation. Initially a large number of measurements are performed during normal operation to show the harmonic distribution. Then measurements at strategic places in the grid are performed while the phase compensating equipment is disconnected with the objective to show if this equipment is part of a resonance circuit. Finally, measurements are performed while the mills in the dressing plant are taken out of production and additional measurements while they are at standstill.

    The results of all these tests show that there is a high probability that the four mills at the dressing plant, regulated by inverters, causes large harmonic currents. A predominantly large portion of the harmonic current sources has been isolated in a small number of loads. The result also show that these harmonic currents are enhanced by resonance between the phase compensation equipment and inductive elements of the grid. The resulting distortion is of such gravity that it propagates to adjacent grids via the main grid.

    Since harmonics can cause breakdowns in rotating machinery, transformers and phase compensating equipment, the risk of this is investigated. Calculations show that at current levels the transformers connecting the industrial grid to the main grid can only be operated at 95,5%. The transformer is currently operating at a far lower rate and no risk of damage is at hand.

    The phase compensation equipment is exposed to large harmonic current. They are also part of a resonance circuit and the assessment is that they are at risk of breakdown.

    In the dressing plant, there is a 630kW induction motor connected directly to the grid. This motor Is subjected to large harmonic currents causing losses in copper wiring and the iron core but since this machine runs below rated power the assessment is that this does not put it at risk of breakdown. However, there are other ways that a machine of this kind can be damaged due to harmonics and further investigation into this may be warranted.

    There are plans of installing new, filtered, phase compensating equipment to the grid which most likely will reduce the harmonic content in accordance with the measurements in this report. However, the measurements also show that higher frequency harmonics in the voltage are enhanced when the phase compensation is disconnected, this may have to be taken in to account when the filters are designed. A number of alternative or additional solutions to the harmonic problem is presented in the report.

  • 202. Nordin, A
    et al.
    Nordwaeger, M
    Olofsson, I
    Pommer, L
    Sanström, E
    Countercurrent oxygen enhanced torrefaction2012Patent (Other (popular science, discussion, etc.))
  • 203.
    Nordin, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pommer, Linda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Ingemar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordwaeger, Martin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Biomass conversion through torrefaction2012In: Technologies for converting biomass to useful energy: combustion, gasification, pyrolysis, torrefaction and fermentation / [ed] Erik Dahlquist, CRC Press, 2012, p. 217-244Chapter in book (Refereed)
  • 204.
    Norgren, Viktor
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utredning av störningar i en trefastransformator: An investigation of the disturbance on a three-phase transformer2016Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [sv]

    Allt eftersom en mer sofistikerad och optimerad elektronik utvecklas går även mer störningar ut i elnätet som påverkar annan elektronik, som även den har blivit mer känslig för störningar. För att beskriva och kontrollera hur mycket störningar som påverkar ett elsystem används benämningen elkvalité. Elkvalitén beskriver kvalitén på elen efter bestämda gränsvärden när den påverkas av störningar. De vanligaste störningarna som förekommer i ett elnät är övertoner, transienter och spänningsvariationer. Det här projektet grundar sig i en transformator som man tror går varm på grund av störningar, den ligger ute på reningsverket på Rönnskär. Transformatorns uppgift är att koppla spänningen från ett IT-isolerat system till ett direktjordat system för att kunna driva den allmänna kraften. Målen med projektet var att mäta och utreda vilka störningar som förekom samt komma upp med åtgärder för att lösa problemet. För att erhålla en djupare kunskap inom området störningar på elnätet genomfördes en fördjupad inläsning av de olika störningar som ansågs vara potentiella källor till varmgången hos transformatorn. De störningar som behandlades var övertoner, transienter och spänningsvariationer. Den mest sannolika störningen som förekom bedömdes vara övertoner, därav genomfördes mätningar mot övertoner. Övertoner är störningar på ström– och spänningskurvan vilket bland annat kan leda till effektförluster, vagabonderande strömmar och resonansproblem. Ursprunget av övertoner genereras av olinjära laster som t ex. frekvensomriktaren. Vid mätningarna användes mätinstrumentet Fluke 1735 specialiserat för övertoner. Mätningarna visade på höga strömövertoner i fas 1 på primärsidan, men på övriga faser samt sekundärsidan kunde inga bevis på övertonshalter som var skadande redovisas. Därför kunde slutsatsen dras att det var en olinjär last utifrån som skickade ut störningarna. Vid ett av mätningstillfällena utfördes även en grundlig genomgång av anläggningen samt transformatorn. Där konstaterades det att det fanns en luftspalt i transformatorns kärna, orsakat av ett fel vid tillverkningen av transformatorn. Teorin kring konsekvenserna vid ett sådant problem medförde att slutsatsen drogs att huvudkällan till varför transformatorn gick varm var luftspalten i kärnan. Eftersom det även fanns övertoner på fas 1 konstaterades att det fanns två källor till värmeökningen i transformatorn där luftspalten i kärnan anses vara mer förödande. Rekommendationerna blir därför till en början att byta ut den nuvarande transformatorn mot en ny, se över frekvensomriktarna i anläggningen samt eventuellt installera ett aktivt filter mot övertoner om prioritering är att eliminera alla övertoner.

  • 205.
    Nylund, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sammanställning av tekniker och metoder för mätning av fukthalt i trädbränslen2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sammanfattar möjliga tekniker och metoder för att bestämma fukthalt i trädbränslen.

  • 206.
    Nyman, William
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Att arbeta med nyckeltal - Fjärrvärme2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The birth of district heating was during the late 1800s in the United States and Germany. The "real" start of the first municipal district heating plant in Sweden was on October 29 1948 in Karlstad. After the start in Karlstad everything moved really slowly until the mid-60s when the use of district heating doubled from five TWh/year to ten TWh/year. Despite the doubling during the 60:s came the real "explosion" of district heating after the oil crisis in 1973.

    In 1998 decided Municipality of Arvidsjaur that they had to do something about the current environment in the city. This was caused because most of the villas and industrial houses in the municipality had its own wood-fired or oil-fired heating systems. Six years later in 2004 started a company called Arvidsjaurs Energi AB, and the purpose for this company was to provide the city of Arvidsjaur with hot water and heat to the houses.

    Today’s supply for Arvidsjaurs Energi is 337 smaller houses and 109 bigger customers such as industrial houses. With three pellet boilers and a oilheater (as reserve) they provide heat during the peakload and the period when the main 8,4 MW woodchip hot water boiler is stopped due maintenance. A lot of money has been invested in the district heating, which has been proved to be a successful investment for the municipal.

    With district heating it follows many work opportunities, and one of that is working with statistics and key figures and that is what this project will be working with. The appearance of this work came when the workers at Arvidsjaurs Energi had noticed that the work with statistics and key figures where a lot time consuming.

    The result of this work will be a Excel sheet that will free some time for the workers. It will contain everything from line losses, used fuel, produced energy and sold energy.  

    The resulting Excel sheet contained all the various parameters mentioned above, but it was also much less than was thought in the beginning. The resulting product of this work is currently used by workers at Arvidsjaurs Energi AB and has proved to ease the work around statistics, which also was one of the goals with this work.

  • 207.
    Nyström, Malin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    En elmarknad i förändring: En fallstudie: Hur påverkas en underleverantör i elsystemet?2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    År 2009 antogs EU:s tredje inre marknadspaket för el och naturgas. Bland annat innehåller det förordningar för att ta fram gemensamma regler för elmarknaden. Det kommer krävas en harmonisering av nationella regler för att denna marknad ska fungera och det ska ske genom så kallade nätkoder och kommissions­riktlinjer som, när de träder i kraft, blir bindande i EU:s samtliga medlemsstater.

    Syftet för rapporten är att skapa förståelse för det komplexa elsystemet i förändring och hur nya krav på EU-nivå påverkar aktörer i flera led, från ansvariga myndigheter till kommersiella aktörer på elmarknaden. Genom en litteraturstudie har förändringar i elsystemet på olika nivåer belysts och genom en fallstudie har följderna av den förändrade elmarknaden påvisats.

    Litteraturstudien visar att mycket redan har förändrats på elmarknaden. Den har övergått från att styras på nationell/regional nivå till att styras från EU och fortsatta förändringar är att förvänta; ökad mängd förnybar energi, närmare samarbete mellan medlemsstaternas systemoperatörer och samordnade krav på funktioner i systemen. Det som inte förändras i elsystemet är det faktum att el måste användas i samma ögonblick som den produceras annars uppstår obalans. I och med att vi introducerar allt fler energislag som är beroende av variabler som vi inte kan styra, som solinstrålning och vindstyrka, blir balansen svårare att upprätthålla. Det visar att långsiktigt positiva förändringar kan påverka ett system som inte är anpassat negativt och medföra omfattande arbete. Men för att nå uppsatta klimatmål och säkra energiförsörjningen krävs de här förändringarna.

    Fallstudien åskådliggör konsekvenserna av nya krav för Eitech, en svensk underleverantör av bland annat elteknikutrustning, som planerar att göra en ny turbinregulator. Kraven omfattar frekvensreglering och hur man ska verifiera att en turbinregulator uppfyller kraven. Svenska kraftnät utformar kraven på den svenska elmarknaden i enlighet med EU:s regelverk, därför påverkar detta både producenter som måste ha utrustning som klarar kraven och underleverantörer som utformar den tekniska utrustningen. Studien antyder att underleverantörer av liknande utrustning som vill vara med och konkurrera på den svenska elmarknaden kommer möta liknande utmaningar som Eitech.

  • 208.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Design och utvärdering av en experimentell uppställning för humanexponeringsstudier med   emissioner från biobränsleförbränning.2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Leading European and U.S. researchers have concluded that fine particles in emissions from burning wood ("wood smoke") and emissions from small-scale biomass burning in general must be regarded as harmful to health, even in the low concentrations normally found in outdoor air. However, what is lacking is knowledge about how this health risk is changing, and may be affected, when modern technology is used and how different biofuels relate in this context. The reason it is so important to do research in the area is because it is decided in the European Union that in 2020, 20% of the member nations energy needs will come from renewable fuels. It is already known that large parts of PM2,5 derives from biomass combustion (mainly small scale) and hence the need for research on what technologies that have the least negative effects so that the correct technology is chosen on the way to the goal. An important method to explore these issues is through controlled human exposures where different kinds of air pollution components can be used, e g wood smoke and diesel exhaust. The objective with this master thesis was therefore to construct, evaluate and elucidate different component is such an exposure set-up at ETPC, Umeå university.es. The control system has been tested and evaluated over several exposures and have fulfilled all the requirements set at the beginning of the work.

    During the tests conducted at the end of the work it turned out that the system is working properly and that it is possible with a little experience of the system to conduct repeatable experiments in the setup in its entirety. One of the problems encountered was the dilution of flue gases but when the ejector SEC100 was found it passed the requirements and with regular maintenance, there are no indications that there will be any problems with future exposures when used under the same conditions as during this work. Mixing in the chamber is not perfect but on the conditions that existed it met the requirements set and the system as a whole has during repeated exposures shown that it also fulfills all the requirements set at the beginning.

  • 209.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Inverkan av förbränningsförhållanden på rökgaspartiklarnas sammansättning i en modifierad   pelletskamin2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In two review articles leading European and American researchers have stated that particles in emissions from residential wood combustion and emissions from small-scale biomass burning in general must be regarded as harmful to health during exposure, even in the low concentrations normally found in outdoor air. However, what is missing is knowledge about how this toxicity changes and may be affected when modern combustion technology is used and how different biomass fuels relate in this context.

    Because of this, the objective with this work was to determine the influence of combustion conditions in a modified pellet stove on the composition of particulate matter in the emissions with respect to the distribution of organic and elemental carbon. A further purpose was to investigate whether it is possible to generate a stable "sooty" burning state for longer periods of time to be used in future toxicological studies of biomass emission particles.

    The results showed that it is possible, by adjusting the parameters that was available, to generate stable conditions of different types of combustion in the currently used and modified pellet stove. Both the total mass concentration of particles and the distribution of organic and elemental carbon in the particulate matter varied. This is promising and shows that it is possible to create, in a controlled manner, incomplete combustion conditions where the particles have different characteristics and properties.

    In order to conduct more detailed studies, however, it is recommended that certain improvements and development of technology is implemented, to enable better control and flexibility. This can be done either with a rebuilt pellet stove or a completely new self-designed reactor. This should be applied to verify the results obtained before any comprehensive study on particle properties based on the results achieved in this work is performed.

  • 210.
    Nyström, Robin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Pagels, Joakim
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Evaluation of a novel chamber setup for human exposures of biomass combustion aerosolsManuscript (preprint) (Other academic)
    Abstract [en]

    Based on a vast number of epidemiological studies there is today a consensus that increased concentrations of ambient particulate matter air pollution cause adverse health effects such as mortality, hospitalizations, cardiovascular events, respiratory symptoms and reduced lung function. The use of controlled laboratory studies with human exposure chambers can give unique opportunities to directly examine specific exposure conditions and cause-effect relationship with relevant concentrations and particle types. In this paper, the design of a novel chamber setup for human exposures of biomass combustion aerosols is described with an evaluation of the systems function under different conditions (e.g. air exchange rates and target PM1 concentrations). Several different research biomass combustion systems are available in combination with extensive and advanced monitoring and characterization of the gaseous and particle emissions used for exposures. Examples, with data from three performed human exposure campaigns, are included and discussed as a basis for the evaluation of the whole setup, with the target to generate stable conditions in the chamber using different kinds of biomass combustion aerosols. Based on the evaluation of function and present exposure experiences it can be concluded that the chamber setup and biomass aerosol generation systems is able to produce a stable aerosol concentration in the chamber of different particle types.  Overall, the human exposure setup for biomass combustion aerosols together with the integrated biomass combustion laboratory gives extensive possibilities for designing different whole body human exposure studies for a variety of biomass combustion aerosols as well as other experimental aerosol research.

  • 211.
    Nyström, Robin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sadiktsis, Ioannis
    Ahmed, Trifa M.
    Westerholm, Roger
    Koegler, Johannes H.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Physical and chemical properties of RME biodiesel exhaust particles without engine modifications2016In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 186, p. 261-269Article in journal (Refereed)
    Abstract [en]

    A major contributor to ambient particulate air pollution is exhaust from diesel engines and other vehicles, which can be linked to different adverse health effects. During the last decades, a global drive towards finding sustainable and clean bio-based alternative fuels for the transport sector has taken place and biodiesel is one of the most established alternatives today. To better assess the overall effects on a public health level when introducing biodiesel and other renewable fuels, a better understanding of the detailed exhaust particle properties, is needed. In this work, the physical and chemical properties of biodiesel exhaust particles were studied in comparison to standard diesel exhaust emissions, in an existing engine without modifications, focusing on particulate carbonaceous matter and PAH/Oxy-PAH as well as fine particle size distribution. An older off-road engine, produced between 1996 and 2004, was used with three different fuels/fuel blends; (1) 100 wt% low-sulfur standard petro diesel (SD), (2) 100 wt% rapeseed methyl ester biodiesel (B100) and (3) a blended fuel – B30 consisting of 30 wt% RME and 70 wt% SD. The study focused mainly on emissions from transient engine operation, but includes also idling conditions. The gaseous emissions measured for the biodiesel fuel were in general in accordance with previous reported data in the literature, and compared to the standard petro diesel the emissions of CO was lower while NOx emissions increased. The particulate mass concentration during transient operation was almost halved compared to when petro diesel was used and this was associated with a decrease in average particle size. The shift in particle mass and size was associated with a higher fraction of organic matter in general, considerable less PAH’s but a relative higher fraction of Oxy-PAH’s, when shifting from petro diesel to biodiesel.

  • 212.
    Näslund, Erik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Mejtoft, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Effects of reducing the time spent on traditional lectures2015In: Proceedings of the 11th International CDIO Conference, Chengdu: Chengdu University of Information Technology , 2015Conference paper (Refereed)
    Abstract [en]

    This paper describes the outcome of a completely revised course implementation for the course Thermodynamics (15 ETCS), a standard physics course at basic level. Historically, this course has been taught in a traditional way, i.e. almost daily lectures combined with a week of lab classes and a written examination concluded the course. Hence, during the roughly 25-30 lectures during the course, most parts of the literature was covered. However, analyzing the results over a 10 year period, where different lecturers has been teaching the course, it can be observed that there are no significant differences in the examination results due to the teacher effort. This observation is not new and of course somewhat disappointing for an enthusiastic lecturer that has a belief in that he/she can make a big difference for the student. With these observations in mind, we set out to do something radically different where the key question is how we get the student to devote sufficient time to pass the exam. Thus, in the revised course implementation, only eight lectures of overview character were given, usually at the start of a week. After each lecture, the students were given eight assignments that they should prepare for, and be able to present, at a seminar that usually occurred at the end of the week. To increase the students’ willingness to actually fulfill the assignment, they were rewarded with a bonus that gave credit at the written exam. The student group performed roughly similar to previous groups on the written exam, but there were a number of differences in the overall performance that will be thoroughly discussed in the paper.

  • 213.
    Näslund, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energikartläggning av fastigheten Ålidhem Centrum2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 214.
    Näslund, Joel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Snökyla för Bosch Rexroth Group2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I detta examensarbete behandlas möjligheterna för Bosch Rexroth Group i Mellansel att sänka framledningstemperaturen till fabriken på befintlig sjökyla genom att den integreras med en snökylanläggning. Även andra kopplingslösningar behandlas.

    Med stigande el- och energipriser, och för den delen påverkan av miljön, finns det incitament för att hitta andra alternativ till kyla. Ett sätt är att utnyttja frikyla är genom att använda kallt bottenvatten från sjöar. Ett annat sätt är att utnyttja lagrad kyla från snö och is, så kallad snökyla.

    Den största delen av snöns kylenergi går att finna i den så kallade smältvärmen. Detta kallas även snöns latenta energi och är väldigt hög i förhållande till andra material. Att lagra snö och is för kylning under sommaren är en gammal och beprövad metod. I Sverige finns ett exempel på en anläggning som bygger på denna princip, Sundsvalls sjukhus snökylanläggning som varit i problemfri drift sedan början av 2000-talet.

    Målet är att ta reda på vilka temperaturer och flöden som kan hållas med tillgänglig snömängd samt vilken mängd snö som krävs för att hålla en viss temperatur. Ytterligare mål är att ta fram optimala dimensioner med avseende att minimera kostnad för snökylanläggningens bassäng och system.

    I rapporten beräknas kylenergibehov som snökylanläggningen måste täcka för att hålla specifika framledningstemperaturer. Kylbehovet jämförs med den, i området, tillgängliga snöns energiinnehåll. I det fall då den tillgängliga snön inte räcker till löses detta genom att låta framledningstemperaturen vara högre för att sedan komplettera de sista graderna med kylmaskin eller genom att transportera mer snö från närliggande samhälle.

    I arbetet behandlas två olika lösningar baserade på olika förutsättningar där varje systemkomponent dimensioneras för att ge bästa prestanda med de systemkrav som gäller. Beräkningar visar att en snökylanläggning, skräddarsydd för Bosch Rexroth, kostar mellan cirka 4,6-8,2 miljoner kronor beroende på vad man är villiga att satsa på för lösning. Priset för att utvinna kylenergi från snö beräknas hamna på cirka 0,30 kronor per kilowattimma, vilket är lägre än dagens energipris för fjärrkyla. Förhållandet mellan utvunnen och tillförd energi beräknades till mellan 10-15, men är i verligheten lägre. Dock inte lägre än en konventionell kylmaskin.

    Rapporten visar att för en framledningstemperatur på 11°C fram till de befintliga värmeväxlarna i fabriken, över hela sommaren krävs 54 900 m3 snö, motsvarande 35 700 ton inklusive de förluster som uppstår då delar av snövolymen smälter på grund av omgivningsfaktorer.

    Markförhållanden och geotekniska aspekter för konstruktion av bassäng behandlas endast översiktligt då rapportsyftets fokus bygger på system och energitekniska lösningar.

  • 215.
    Näslund, Madelene
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Underlag för BREEAM-certifiering: Kristianstad Nya Galleria2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 216.
    Näsström, Joakim
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    State-of-the-art development platform for hydropower turbine governors2017Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
    Abstract [en]

    Hydropower is a flexible energy source that is essential for balancing the electrical power system on all timescales, from seconds to years. In addition to intra-hour regulation, it provides frequency containment reserves (FCR-N,FCR-D) and frequency restoration reserves (mFRR, aFRR) to the grid. The turbine governor is a device responsible for controlling the power output and delivering frequency control to the system. The aim of this Master’s Thesis project is to develop a new hydropower turbine governor in MATLAB/Simulink, which contains all critical functionality from the existing governor and with the same performance. The new governor should as far as possible comply to the well-established communication standard IEC 61850.

    A working model of the turbine governor has been built in Simulink that supports normal operation with frequency control, start and stop, load rejection, operation mode as synchronous condenser and more. Validations of the model against data from Akkats powerplant shows that the model behaves as a real governor during normal operation. Validations of the start sequence showed deviations during sequence 3 and 4 which can be explained by usage of different PID parameters.

    Using IEC 61850 as a nomenclature and as a way of structuring functions in the governor has also been possible. Implementing the whole standard for communication, requires that the control system also is renewed according to IEC 61850. Certain functions, as sequencing has thus not been done according to the standard.

    MATLAB and Simulink provide tools for building, simulating and testing implementations of the turbine governor. The contributions this platform can provide are; ease of implementation, optimization and testing of control strategies. Simulink also provides a graphical interface, which reduce system complexity. An optimal implementation requires a hardware with support for Simulink to get a transparent platform.

    Ultimately, these benefits could result in better frequency quality at a lower cost, which is essential for successful and cost-effective integration of other renewable energy sources such as wind- and solar power.

  • 217.
    Näzelius, Ida-Linn
    et al.
    Luleå, Sweden.
    Fagerström, Jonathan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    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.
    Öhman, Marcus
    Luleå, Sweden.
    Slagging in fixed-bed combustion of phosphorus-poor biomass: critical ash-forming processes and compositions2015In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 2, p. 894-908Article in journal (Refereed)
    Abstract [en]

    Slagging in combustion facilities is not welcomed, because it may cause technical and operational problems, as well as extra costs. Increased understanding of the critical slagging subprocesses makes it easier to suggest semiempirical models and fuel indexes for predicting the slagging tendencies of different fuels. That could open the biomass market for potentially more troublesome raw materials. The objective of this work was to determine critical ash-forming processes and compositions in the fixed-bed combustion of phosphorus-poor biomass fuels. This was achieved by performing a systematic review of data and experience gathered from combustion experiments in a small grate burner of 36 different biomasses, as well as chemical analysis of their bottom ashes and slags. The paper presents a discussion of the slagging tendency in phosphorus-poor biomass by combining three different slagging classifications, culminating in a proposed starting point for a new slagging index. The slag (ash particles >3.15 mm in size) formed during the combustion experiments has been described according to the fraction of fuel ash that forms slag (expressed in terms of weight percent), the visual sintering category (1-4), and the viscosity predictions. The results explain that both the fraction of melt and its viscosity are critical for the slag formation process in phosphorus-poor biomasses. In addition, fuels with low Si/K ratio along with a higher Ca concentration may form a low viscous carbonate melt that is not prone to form slag. Increased Si and lowered Ca concentration will increase the amount of formed silicate melt formed, as well as its viscosity, thus resulting in a more sticky melt.

  • 218.
    Olofsson, Andreas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Investigation of Materials for Use in Exhaust Gas Condensate Environment with Focus on EGR systems2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    EGR (Exhaust Gas Recirculation) is a method for reducing NOx emissions for heavy-duty diesel engines. EGR works by introducing part of the exhaust gases back to the engine cylinders. Exhaust gases consists mainly of CO2, NOx, SO2 and H2O. As the temperature decreases, these gases form a corrosive condensate. The EGR components which are exposed to the condensate environment must therefore be of corrosion resistant materials. The objective of this Master's Thesis is to investigate suitable materials for use in exhaust condensate environment. The goal is to evaluate the pitting corrosion resistance for eight dierent commercial stainless steels and two commercial aluminium alloys in exhaust gas condensate environment. Furthermore, nitriding surface treatments on one martensitic stainless steel and anodising treatments on one aluminium alloy, were also included in this study.

    Five dierent exhaust gas condensates with dierent concentrations of sulphuric acid, nitric acid and chloride were chosen to perform electrochemical measurements. Two pH values 2.5 and 1.5; three chloride concentrations, 32 ppm, 200 ppm, 3300 ppm were included in the environmental parameters. The testing temperature was 60 oC, since it is the temperature which can still be expected to produce substantial amount of exhaust gas condensate in the EGR system. The electrochemical method used, was anodic polarisation measurements. This is a useful method to evaluate the pitting resistance for stainless steels in chloride containing solutions.

    The results show that the two aluminium alloys and the martensitic stainless steel were subjected to both general and pitting corrosion in a normal condensate solution at pH 2.5. The anodised film on the aluminium surface was not stable in condensate environments with low pH value. After twelve hours of exposure to a condensate at pH 2.5 at 60 oC, the protective eect of the lm became negligible.

    The austenitic, ferritic and duplex stainless steels show, however good resistance against both corrosion types. Increasing condensate acidity from pH 2.5 to 1.5 could not be observed to increase risk of pitting corrosion for the austenitic, ferric and duplex steel stainless steels.

    High concentrations of sulphuric acid, low pH value, but low chloride content (200 ppm) do not increase the risk for pitting corrosion for austenitic steels 1.4404 and 1.4301, duplex 2304 and ferritic 1.4521. However, chloride concentration of 3300 ppm, signficantly increased risk of pitting corrosion, especially for the austenitic stainless steels. Duplex stainless steel show better pitting resistance in high chloride environments, in addition to the good general corrosion resistance in low pH value environments.

    There is no dierence in corrosion resistance between the nitride coated 1.4112 steel and the steel without coatings. No dierences can be observed between the plasma and gas nitrided samples. Further investigation in less corrosive environment is recommended, since anodic polarisation is not a suitable method to study general corrosion behavior.

    The pitting corrosion resistance in condensates with high chloride concentrations at 60 oC follows the sequence 1.4301<1.4521<1.4404<duplex 2304<duplex LDX2404<duplex 2205. Clearly, duplex stainless steels have better pitting corrosion resistance in low pH environment when chloride concentration is increased. Considering the operating conditions of the EGR components, the element prices, it is probably more benecial to consider the duplex stainless steels for use in the EGR system.

  • 219. Olofsson, I
    et al.
    Nordwaeger, M
    Håkansson, K
    Nordin, A
    Pommer, L
    Method for cooling and increasing energy yield of a torrefied product2012Patent (Other (popular science, discussion, etc.))
  • 220. Olofsson, I
    et al.
    Sandström, E
    Nordwaeger, M
    Rudolfsson, M
    Larsson, S
    Lestander, T
    Kalén, G
    Samuelsson, R
    Pommer, L
    Brännström, M
    Nordin, A
    Torrefaction and compaction of eucalyptus and spruce wood2011Conference paper (Refereed)
  • 221.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A method for predicting the annual building heating demand based on limmited performance data1998In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 28, no 1, p. 101-108Article in journal (Refereed)
    Abstract [en]

    In this paper, we present an investigation of the possibility to use a neural network combined with a quasi-physical description in order to predict the annual supplied space heating demand (P) for a number of small single family buildings located in the North of Sweden. As a quasi-physical description for P, we used measured diurnal performance data from a similar building or simulated data from a steady state energy simulation software. We show that the required supplied space heating demand may be predicted with an average accuracy of 5%. The predictions were based on access to measured diurnal data of indoor and outdoor temperatures and the supplied heating demand from a limited time period, ranging from 10 to 35 days. The prediction accuracy was found to be almost independent of what time of the year the measurements were obtained from, except for periods when the supplied heating demand was very small. For models based on measurements from May and fo some buildings from April and September, the prediction was less accurate.

  • 222.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energy load predictions for buildings based on a total demand perspective1998In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 28, no 1, p. 109-116Article in journal (Refereed)
    Abstract [en]

    The outline of this work was to develop models for single family buildings, based on a total energy demand perspective, i.e., building-climate-inhabitants. The building-climate part was included by using a commercial dynamic energy simulation software. Whereas the influence from the inhabitants was implemented in terms of a predicted load for domestic equipment and hot water preparation, based on a reference building. The estimations were processed with neural network techniques. All models were based on access to measured diurnal data from a limited time period, ranging from 10 to 35 days. The annual energy predictions were found to be improved, compared to models based on only a building-climate perspective, when the domestic load was included. For periods with a small heating demand, i.e., May-September, the average accuracy was 7% and 4% for the heating and total energy load, respectively, whereas for the rest of the year the accuracy was on average 3% for both heating and total energy load.

  • 223.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Mahlia, TMI
    Modeling and simulation of the energy use in an occupied residential building in cold climate2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 91, no 1, p. 432-438Article in journal (Refereed)
    Abstract [en]

    In order to reduce the energy use in the building sector there is a demand for tools that can identify significant building energy performance parameters. In the work introduced in this paper presents a methodology, based on a simulation module and graphical figures, for interactive investigations of the building energy performance. The building energy use simulation program is called TEKLA and is using EN832 with an improved procedure in calculating the heat loss through the floor and the solar heat gain. The graphical figures are simple and are illustrating the savings based on retrofit measures and climate conditions. The accuracy of the TEKLA simulation was investigated on a typical single-family building in Sweden for a period of time in a space heating demand of relatively cold and mild climate. The model was found applicable for relative investigations. Further, the methodology was applied on a typical single family reference building. The climate data from three locations in Sweden were collected and a set of relevant measures were studied. The investigated examples illustrate how decisions in the early stages of the building design process can have decisive importance on the final building energy performance. (C) 2011 Elsevier Ltd. All rights reserved.

  • 224.
    Olsson, Björn
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Biooljeprojekt för Umeå Energi AB2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 225.
    Olsson, Magnus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Projektering av urban vindkraft2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report presents, on behalf of Umeå Energi, the planning of an urban wind turbine. The first part of the report describes briefly the theory of urban wind power and it differences with large-scale wind power. The second part presents the planning of a wind turbine placed on Strömpilen in Umeå. This work is planned to be part of the project Hållbara Ålidhem, a project which Umeå Energy have together with AB Bostaden and Umeå Kommun with the objective of creating a safer, more comfortable and energy-efficient residential.

    Urban wind power means that small-scale wind turbines are placed in built-up enviroment, a new and growing market. Small-scale wind turbines has an installed capacity of 100 kW or smaller, compared with today's large-scale wind turbines, which is rated at around 2 MW.

    The planning of urban wind power is problematic. The location of the wind turbine often determine whether the project will be profitable or not. Wind conditions are complex in an urban environment because there are often multiple barriers that affect the wind. This places high demands on the wind measurement, but an accurate wind measurement is disproportionately expensive in relation to the investment cost for small-scale works and also takes a long time. In addition, the software is for wind energy project suitable for large-scale wind power and uses assessment methods that do not give a good result for urban winds. CFD programs or wind tunnels should be used instead.

    Urban wind power is difficult to make profitable in Sweden today. The cost to install a small-scale wind turbine is estimated to be nearly twice as expensive when compared to a large-scale, calculated in SEK per kW installed. In addition, wind conditions is much worse partly because of obstacles but also because the turbine do not reach the same height above the ground as largescale wind turbines. Urban wind power is rather an investment that serves as a billboard for the designer and also affects the peoples attitude of additional wind power, as they tend to increase interest in wind power and renewable energy. This creates positive values which are not reflected in an economic evaluation.

    This study compares two wind turbines as possible investments. The turbines were selected to complement each other well in terms of appearance and size, which is important for those who ultimately chooses which turbine to invest in. Calculations in WindPRO gave the wind turbines yearly production, 4.9 and 22.7 MWh. Simple economic calculations then gave the pay-off time, 10 and 52 years.

  • 226.
    Palage, Victor
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energiutredning: Bioenergi i Luleå2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bioenergi i Luleå tillverkar pellets för privatpersoner och företag. För att torka sågspånet som sedan ska pressas till pellets använder man sig av spillvärmen som finns ute på Svartöstadens, men innan torkenergin kommer fram till Bioenergis stora roterande cylindertork ska den passera Luleås kraftvärmeverk, där Lukab producerar el och fjärrvärme innan den når Bioenergi. I dessa rökgaser finns energi bunden i form av vattenånga som i dagsläget bara släpps ut genom skorstenen, syftet med arbetet är att ta reda på hur mycket av den energi rökgasen innehåller som man kan återanvända. 

    Med hjälp antaganden ur tidigare arbeten och min handledare på universitetet har en återvunnen effekt beräknats som sedan använts för att ta reda vilka besparingar det medför. Beräkningarna har genomförts i Excel och tillvägagångssättet redovisas i rapporten.

    Beräkningarna visar att vid typisk drift kan man återvinna 4300 kW vid ett rökgasflöde av 18 m3/s som skulle leda till en minskad oljeanvändning vid Lukab. Med dessa siffror kan man dra slutsatsen att det viktigaste är inte till vad man återanvänder energin ut att den återanvänds, då Lukab slipper spetsa produktionen med olja är både ekonomiskt och miljömässigt försvarbart.

  • 227.
    Persson, Erik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Termiska lager för ångproduktion med koncentrerade solfångarfält: En studie om fasändringsmaterial och dess potential för lagring av värme till fjärrvärmenätet och processånga till industrin2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    All energy, wind, water, biofuel and fossil fuel besides nuclear- and tide power originates from the sun. It’s very hard to take full advantage of the huge amount of energy hitting the earth each day from the sun. The suns highest radiation appears often when the energy need reaches its lowest. That’s why it’s very important to be able to store energy over time when the sun doesn’t shine. A large part of energy storage is thermal energy storage, which can either be done sensible, latent or chemical. Another possible thermal storage is a combination of sensible and latent.

    This exam was aiming to investigate different types of energy storage methods available on the market and a much more detailed analysis for different storage methods with phase change materials (PCM). A new method was designed for a new storage tank suitable for Absolicon Solar Collector AB and their energy park in the city of Härnösand.

    The methods for this exam were to create a theoretical storage tank suitable to Absolicons Energy Park with some simple calculations. The criteria for the storage tank was to create a storage tank that could provide the district heat in Härnösand with 160 degrees pressurized water and create 160 degrees steam to the industry. The dimensions of the storage tank where chosen by the conditions in Härnösand and from the specific data of Härnösands district heat and from Absolicons new solar collectors. The work temperature of the system were set to 160 degrees which meant that the storage tank would be able to work in those conditions with high temperature. A suitable phase change material and methods for encapsulation of the phase change material suitable for this system was to be found. Small tests were made with a new type of encapsulation for phase change materials in higher temperature. Simple calculations of two types of storage tanks were made. The first storage tank was made with a PCM from PCM products named A164. This PCM was encapsulated with special bags that could handle temperature up to 200 degrees with surrounding rapeseed oil and a copper loop that handled the heat transfer. The second thank was made with the same PCM and encapsulation but with water glycol surrounding the PCM and two types of heat exchangers for the heat transfer.

    The results from the first tank were that it didn’t work with the district heat. Because a wrong calculation with the schematic of the system made it impossible to connect into the district heat of Härnösand. The only good thing was that it didn’t need to be pressurized because of the rapeseed oil but the bad heat transfer between oil and water made a pressurized tank of water more profitable. The results from the second tank showed that it could produce 160 °C to the district heat for 2 h and 7 minutes. The schematic connection worked and the tank would in the near future be able to connect into the district heat. The result for the encapsulation showed that the bags were able to stand temperatures up to 190 degrees for a short period of time.   

  • 228.
    Persson, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energikartläggning med energibesparingsåtgärder på Norrmejeriers mejeri i Umeå: Avdelningen för pulvertillverkning2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis estimates the energy required to manufacture two different powder types at Norrmejeriers dairy in Umeå. Some work has also been done trying to find improvements in the manufacturing process of the powder to reduce the energy consumption. Background to the work is Norrmejeriers participation in Swedish Energy Agency’s program for energy efficiency in large industries.

    The evaporation plant uses approximately 16,5 GWh per year associated to steam used in the drying process according to the energy audit that was made in 2013 by Sweco. The evaporation plant at the dairy is in the current situation the most significant energy aspect in terms of oil, electricity, biogas and water.

    These 16.5 GWh distributed in a number of different drying processes, two different types of evaporators and a spray drying process. These processes have in this thesis have been mapped over a number of days of production, where whey volumes, steam consumption and operating- and production time was noted. Thereafter, the specific energy per liter of concentrate or powder from each individual device is calculated. This is to see how the energy demand differs between the different production methods and powder types.

    The results showed that the specific energy use in powder manufacturing varies between 3,02 kWh/liter for whey powder and 4,60 kWh/liter for whey protein concentrate. The result, however, depends on the involved drying processes, when the specific energy use of the devices ranges from 0,28 kWh/liter and 3,62 kWh/liter. When these values was compared consideration should be taken of the whey volumes processed each year which is over 31 km3 for manufacturing whey powder and over 20 km3 for whey protein concentrate.

    In the thesis five different suggestions are presented to reduce the energy use in powder manufacturing. Three of these proposals are more energy economic but not possible due high investment costs.

    One of the five proposals presented and deemed feasible in the near future would mean an annual energy saving of 550 MWh. This means an annual saving of 275 tSEK with an assumed energy price of 500 SEK/MWh.

    The other proposal as deemed feasible and is presented is a number of engine replacements. This proposal shows that energy savings between 3-20 MWh/year can be done but is not economically justified as the repayment periods for engines exceeds its warranty periods.

    The fact that there are few flow meters in the steam system in the department and the equipment that stores the values of heat consumption is not calibrated in many years Norrmejerier have no clear picture of the powder manufacture's impact on the department's energy use.

    Further deemed an opportunity for energy savings exists in integrating the thinking of energy efficiency in product planning. Then unnecessary down time and idle runs can be avoided, thereby saving energy. This has no estimates have been made, but in consultation with staff at Norrmejerier are some savings.

  • 229.
    Persson, Johanna
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lufttäthetens inverkan på energiberäkningar för byggnader2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the rising energy prices and the increased awareness about our natural recourses the interest in energy efficiency in all areas has increased. One of the Swedish parliament’s environmental quality objectives states that energy consumption in residential and commercial buildings should be reduced by 20 % until 2020 compared to the consumption in 1995. Until today the consumption has rather increased than decreased, therefore an extensive reform is needed to reach the goal.

    Transmission is the most important factor in heat loss of buildings. Another loss factor is the unregulated flow of air through cracks in the building envelope. The air leakage is difficult to determine without a measurement of the building air tightness. Since this measurement is time consuming it would be a good thing to be able to estimate the leakage for energy calculations of buildings. The purpose of this project is to develop guidelines for how to choose input data for energy calculations. To find out how to determine or estimate the air leakage for use in energy calculations is also a part of the purpose. The project is divided in three parts; a literature study, a case study of a building where measured and calculated air leakage is compared and where an air tightness measurement is conducted and sensitivity analysis and comparison of two computer calculation programs, RIUSKA and IDA ICE.

    The results of the sensitivity analysis show that the air leakage plays a larger role in calculations in RIUSKA than in IDA ICE. The calculated heat consumption can increase by up to 30 % in RIUSKA when including air leakage. Thermal bridges can only be taken into account in calculations in IDA ICE and the sensitivity analysis show that thermal bridges has a significant impact on the calculated heat demand, up to 30 %. The air leakage in buildings should, if looking at the studied leakage data, normally be between 0,2 and 2,3 1/h or 0,2-1,5 l/s, m2 Aenv at 50 Pa pressure difference. To link the size of air leakage with type of construction is very hard, it might even be impossible. Some people think that the air leakage is more linked with how the building is built than what type of construction it is. But it seems to be a common view that concrete buildings have higher air tightness than wood constructions.

    More measurements and follow-ups of energy calculations would give a clearer picture of how realistic the present energy calculations are and how large the air leakage of different buildings is.

  • 230.
    Petersson, Frida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    LEK3 - Hållbar fastighetsanvändning genom samverkan: Mervärden vid energieffektiviseringar2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 231.
    Pettersson, Emil
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kombination av bergvärmepump och fjärrvärme som värmekälla: Utformning och drift av anläggning med fokus på driftkostnader2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The operating costs for multi-dwelling houses have steadily increased since the beginning of the 1990s and heating costs constitute the largest part of the operating costs. The most common way of heating multi-dwelling houses is by district heating which steadily increases in use. In 2016, 90 % of the energy for heating multi-dwelling houses came from district heating.

    While the use of district heating has increased, so have the prices. This has led property owners to look for other heating options in order to reduce operating costs. One alternative that is relatively uncommon presently, but that may be more important in the future, is heating buildings with a combination of a geothermal heat pump and district heating.

    The aim of this bachelor thesis is to investigate how a heating system combining a geothermal heat pump and district heating should be designed and operated to obtain low operating costs. To examine this the power and energy data from an actual building located in Umeå are analyzed and then applied on various fictitious alternatives based on varying proportion of heat output from the geothermal heat pump.

    The investigation is based on average climate in Umeå for the years 1981 to 2010, and variable and fixed costs are based on prices from March 2018 from the district heating and electricity supplier Umeå Energi. The fictitious systems have a dimensioned heat power of 300 kW and annual heat energy use of approximately 800 000 kWh. Cases where the power share from geothermal heat pump is 20, 40, 60 and 80 percent were analyzed. However, the domestic hot water in every option is supplied by district heating.

    The results showed that annual operating costs decreased with increased heat output from the geothermal heat pump. However, if the investment costs are taken into account, the results are less straight forward. According to the LCC (Life Cycle Cost) investment calculation method, the lowest life cycle cost is generally obtained when 40 % of the heat power requirement is covered by geothermal heat pump. This proportion of geothermal heat pump caters for 90,4 % of the energy use of the space heating system.

    In addition, the results showed that the operating costs can be further reduced by lowering the supply temperature to the space heating system. For each degree lowering of the supply temperature, within the range of 60 to 40°C, the Seasonal Coefficient of Performance (SCOP) of the heat pump increases with 0.062.

    However, there are limitations on how much the supply temperature can be lowered before the radiators ability to emit heat is impaired. In a space heating system dimensioned for a supply temperature of 60°C and return temperate of 40°C, the supply temperature can be lowered by 5°C (if the return temperature is increased) and still deliver enough heat.

  • 232.
    Pettersson, Eric
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energikartläggning av flerbostadshus i Bureå: Undersökning av åtgärder i IDA ICE2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis, I’ve investigated different energy efficient measures that can be done on a multifamily home in Bureå to reduce the total amount of energy used and perform a simpler economic calculation of the different measures. The investigation has been completed with the help of the software IDA ICE. Information about the building and its performance have been collected from Skebo.Data that is missing has been assumed to standard values.

    The different measures that have been investigated and simulated are: additional insulation on outside walls in different thicknesses, additional insulation on the attic floor, exchanging the double pane window to three pane windows, and installing a ventilation system with heat recovery.

    The results of the simulations reveal that additional insulation on the outer walls provide a decent reduction of energy up to 150 mm, which gives us a 12 % reduction. Skebo requested slightly less thickness to be used, therefore 70 mm has also been simulated in the case of combined measures.

    When the double pane windows are exchanged to three pane windows the effect is equal to the 150 mm additional insulation of the outer wall, giving a similar reduction in energy used.

    The largest reduction in energy is a change of ventilation system with heat recovery and increasing the air tightness of the building to reduce the amount of involuntary leakage of air. This measure reduce the district heating with 36 % alone. If ventilation system with heat recovery and increased air tightness is combined with the two other measures window change and additional insulation of the outer wall, the district heating is reduced up to 57 %.

    The smallest reduction in energy is additional insulation of the attic floor, a reduction of 2 %. This is because of its already well insulated state and no big improvements can be made.

    The result of the economic calculation shows that all measures have a higher life cycle cost than the reference case. Particularly expensive is the combination of change of ventilation system, window change and additional insulation on the outer walls.

  • 233.
    Pettersson, Esbjörn
    et al.
    Energy Technology Centre, Piteå, Sweden; Division of Energy Engineering, Luleå University of Technology, Luleå, Sweden.
    Lindmark, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Division of Energy Engineering, Luleå University of Technology, Luleå, Sweden.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Westerholm, Roger
    Department of Analytical Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Design Changes in a Fixed-Bed Pellet Combustion Device: Effects of Temperature and Residence Time on Emission Performance2010In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 24, no 2, p. 1333-1340Article in journal (Refereed)
    Abstract [en]

    The use of wood fuel pellets has proven to be well-suited for the small-scale market, enabling controlled and efficient combustion with low emission of products of incomplete combustion (PIC). Still! a potential for further emission reduction exists, and it thorough understanding of the influence of combustion Conditions oil the emission characteristics of air pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM), is important. The Objective of the present work was to determine the effect of design changes, i.e., increasing the temperature and/or residence time, on the emission performance and characteristics for a pellet combustion device using a laboratory fixed-bed reactor (< 5 kW) The temperature and residence time after the bed Section were varied according to statistical experimental designs (650-950 degrees C and 0.5-3.0 s) with file emission responses: CO, organic gaseous carbon (OGC), NO, volatile organic compounds (VOCs, 20 compounds), PAHs (43 compounds), PM(tot) mass concentration, fine particle mass/count median diameter (MMD and CMD), and number concentration. The temperature was negatively correlated with the emissions of all studied PIC, with limited effects of the residence time. The PM(tot) emissions of 15-20 mg/MJ were in all cases dominated by fine (< 1 mu m) particles of K, Na, S, Cl, C, O, and Zn. An increased residence time resulted in increased fine particle sizes (i.e., MMD and CMD) and decreased number concentrations. The Importance of a high temperature (> 850 degrees C in the bed zone with intensive, air-rich, and well-mixed Conditions was illustrated for wood pellets combustion with almost a total depletion Of all Studied PIC. The importance of the residence time was shown to be limited, and file results emphasize the need for further verification studies and technology development work.

  • 234.
    Phan, Duong Ngoc Chau
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boily, Jean-Francois
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Link between fly ash properties and polychlorinated organic pollutants formed during simulated municipal solid waste incineration2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 4, p. 2761-2769Article in journal (Refereed)
    Abstract [en]

    The relationship between the properties of fly ash generated during waste incineration and the thermal formation of persistent organic pollutants (POPs), such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and naphthalenes (PCNs), was investigated on two artificial wastes using a laboratory incinerator. Fly ash particles were sampled in the post-combustion zone at approximately 300 degrees C and were characterized with the following complementary techniques: X-ray diffraction (XRD), scanning electron microscopy energy-dispersive X-ray (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. Flue gas samples were collected at the same location and analyzed for Mo-OCDDs, Mo-OCDFs, Tri-DCBs, and Di-OCNs. A strong correlation between fly ash characteristics and waste composition exists for several of the elements considered in this work. For instance, the waste containing the highest levels of Al produced more abundant Al-bearing minerals and elemental Al in the resulting fly ashes. Copper, an especially important POP formation catalyst, was not detected in the top 10 nm surface of fly ash particles but rather occurred within the top 2 pm, indicating that surface copper of catalytic importance for POP formation reactions was not available. Important contributions of ferric iron present in the abundant fly ash-building hematite phase could have also played an important role, especially given its documented contributions in chlorination pathways. Orthogonal projections to latent structures (OPLS) modeling resolved the relationship between fly ash properties and the post-combustion POP formation. These efforts showed that low levels of ash-forming elements (i.e., Na, Mg, Fe, Ti, etc.) were associated with an increase in flue gas S levels, which, in turn, poison the Cl-2 production via the Deacon process. Wastes with depleted levels of fly-ash-building elements should therefore be favored for minimizing PCDD, PCDF, PCB, and PCN release caused by incineration.

  • 235.
    Philip, Ylinenjärvi
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Förvärma uteluften med bergvärme i ett FTX-system2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is commissioned by HSB Norr in Umeå. The thesis work is conducted in spring 2018. The principal HSB is a member-owned company that owns and manages real estate around Sweden.

    The property that the project includes is called Lyktgubben and is located on Tomtebo in Umeå. In the building there are 24 apartments, garage and shelters with an Atemp of 1780 sqm. The property has a heat demand of 146 kWh / sq.m. which is higher than the construction industry currently recommends for multi-family houses in Umeå. The heating system consists of district heating and in the ventilation system which consists of an FTX unit with a heating coil which is also powered by district heating.

    The project has evaluated the possibilities of implementing preheating of outdoor air with geothermal heat in an FTX-system, also known as HSB-FTX in the Lyktgubben property, to see if it is cost-effective and what climate savings this can lead to.

    The prerequisite for implementing HSB-FTX in the building is there. It is a good area for drilling for geothermal heat and there is room for attracting KB pipelines.

    This investment is good for cutting power peaks, a large part of the power peaks are used to heat the outdoor air to the desired supply air temperature at cold outside temperatures. The power subscription could potentially be reduced by up to 40-50 kW at cold outdoor temperatures around -20 degrees Celsius.

    The ventilation unit is old and a new one should be installed. With that said, the project has concluded that it is most profitable according to LCC is to drill three holes for HSB-FTX. As HSB-FTX is a costly investment, it results say that installing only a new unit has the lowest payback time.

  • 236.
    Piotrowska, Patrycja
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Rebbling, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lindberg, Daniel
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Waste gypsum board and ash-related problems during combustion of biomass: 1. Fluidized bed2015In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 2, p. 877-893Article in journal (Refereed)
    Abstract [en]

    This paper is the first in a series of two describing the use of waste gypsum boards as an additive during combustion of biomass. This paper focuses on experiments performed in a bench-scale bubbling fluidized-bed reactor (5 kW). Three biomass fuels were used, i.e., wheat straw (WS), reed canary grass (RC), and spruce bark (SB), with and without addition of shredded waste gypsum board (SWGB). The objective of this work was to determine the effect of SWGB addition on biomass ash transformation reactions during fluidized bed combustion. The combustion was carried out in a bed of quartz sand at 800 or 700 degrees C for 8 h. After the combustion stage, a controlled fluidizedbed agglomeration test was carried out to determine the defluidization temperature. During combustion experiments, outlet gas composition was continuously measured by means of Fourier transform infrared spectroscopy. At the same place in the flue gas channel, particulate matter was collected with a 13-stage Dekati low-pressure impactor. Bottom and cyclone fly ash samples were collected after the combustion tests. In addition, during the combustion tests a 6-h deposit sample was collected with an air-cooled (430 degrees C) probe. All ash samples were analyzed by means of scanning electron microscopy combined with energy dispersive X-ray spectrometry for elemental composition and with X-ray powder diffraction for the detection of crystalline phases. Decomposition of CaSO4 originating from SWGB was mainly observed during combustion of reed canary grass at 800 degrees C. The decomposition was observed as doubled SO2 emissions. No significant increase of SO2 during combustion of SB and WS was observed. However, the interaction of SWGB particles with WS and SB ash forming matter, mainly potassium containing compounds, led to the formation of K2Ca2(SO4)(3).

  • 237.
    Pohjanen, Alexander
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energibalans och inomhusklimat i ett parkeringshus under jord med behovsstyrd ventilation2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This graduate work was conducted in cooperation with the VVS-Consultants Skellefteå AB. It deals with the design of a parking garage regarding heat and ventilation and a comparison of ventilation systems in a parking garage that is scheduled to be ready 2019. The purpose of the work is to investigate how to design a parking garage ventilation and if you can save energy and expenses by using demand-controlled ventilation instead of constant ventilation. As it is more expensive to invest in demand- controlled ventilation, it will also investigate the repayment period for that investment. To do the studies, the IDA ICE program has been used to draw a model of the building and simulate its energy use to compare the results later and see the differences between the different ventilation systems. A proposal has been made on how ventilation can be drawn and how the radiators are to be installed and how the pipes are to be drawn. The result of the simulations resulted in total energy consumption decreased by 705,000 kWh / with demand-controlled ventilation compared to constant ventilation. The fan's energy consumption decreased by 75% and the heating energy decreased by 72%. The investment for controlled ventilation compared to constant flow ventilation is 600,000 kr more and, based on the calculations in this work the repayment period is 1 year. The life expectancy of the ventilation system is assumed to be 25-30 years.

  • 238. Pommer, L.
    et al.
    Olofsson, I.
    Borén, E.
    Nordwaeger, M.
    Nordin, A.
    Review and compilation of existing and new experimental data on torrefaction gas composition2013Conference paper (Refereed)
  • 239.
    Puttige, Anjan Rao
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Method to estimate the ground loads for missing periods in a monitored GSHP2019In: EUROPEAN GEOTHERMAL CONGRESS 2019: THE HAGUE, 11-14 JUNE 2019, 2019Conference paper (Other academic)
    Abstract [en]

    Monitoring a ground source heat pump can provide important insights into its working, but to study the behaviour of the borehole heat exchanger (BHE) we require monitored data for the whole period of operation. In practice, the monitored data often has periods of missing data. We propose a method to estimate the load during the periods of missing data based on the fluid temperature after that period. The method determined the missing load with negligible error, for the case of a BHE that behaves exactly like the model describing it. A sensitivity analysis showed that the estimated load is highly sensitive to errors in measured load and fluid temperature. The method was applied to a real monitored BHE, the magnitude of estimated loads were unreasonably high, but the overall deviation between the measured and simulated values of fluid temperature decreased. Therefore, the high magnitude of missing load compensates for the lack of agreement between the model and the measured data.

  • 240.
    Puttige, Anjan Rao
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Method to estimate the ground loads for missing periods in a monitored GSHP2019In: European Geothermal Congress 2019, 2019Conference paper (Other academic)
    Abstract [en]

    Monitoring a ground source heat pump can provide important insights into its working, but to study the behaviour of the borehole heat exchanger (BHE) we require monitored data for the whole period of operation. In practice, the monitored data often has periods of missing data. We propose a method to estimate the load during the periods of missing data based on the fluid temperature after that period. The method determined the missing load with negligible error, for the case of a BHE that behaves exactly like the model describing it. A sensitivity analysis showed that the estimated load is highly sensitive to errors in measured load and fluid temperature. The method was applied to a real monitored BHE, the magnitude of estimated loads were unreasonably high, but the overall deviation between the measured and simulated values of fluid temperature decreased. Therefore, the high magnitude of missing load compensates for the lack of agreement between the model and the measured data.

  • 241.
    Quick, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Snökyla i Umeå: Snowpower in Umeå2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Under flera hundra år användes den lagrade energin som finns i snö för att tillfredsställa de kylbehov som finns på sommarhalvåret. Det kalla klimatet i kombination med god nederbörd som finns i Norrland innebär goda förutsättningar för snö.

    Målet med denna rapport är att i samarbete med Umeå kommun se hur mycket energi som finns lagrad i de snömängder som helt outnyttjat smälter bort varje sommar. Den geografiska platsen är snötippen Kulla vid klockarbäcken i Umeå. Det är svårt att nyttja all energi som finns lagrad i snön då en del ofrivillig värmetransport kommer ske till omgivningen. För att beräkna värmetransporten samt den mängd energi som går att använda för kylning har en metod arbetats fram. Det är en energibalans där man förutsätter att hela snöhögen håller 0°C och att all energi som transporteras från snön innebär en minskad snömängd. De utförda beräkningarna gjordes i kalkylprogrammet Excel som har funktioner för att skapa grafiska bilder till resultatet. Detta utifrån de mängder data som behandlats. Beräkningarna är utförda månad för månad och behandlar väderdata för temperatur och nederbörd.

    Resultatet visar att en medelsäsong av naturlig snö genererar kring 4 GWh vilket motsvarade drygt 40% av den mängd fjärrkyla som Umeå Energi producerade 2016 till sitt centrala fjärrkylnät. De osäkerheter som noterats är att vädret är oberäkneligt och att de slutliga snömängderna kan skilja mycket från år till år. Däremot är mängden snö som försvinner på grund av ofrivillig värmetransport likartad mellan de olika säsongerna. De år som är snöfattiga kan det därför vara en god idé att göra konstgjord snö för att säkerställa att kyla kan levereras.

    Bedömningen som gjordes är att förutsättningar för att anlägga en snökylanläggning med god produktion finns. Den elektricitet som idag investeras för att kyla kan komma till bättre nytta om kylan istället kommer från naturligt producerad snö.

  • 242.
    Rebbling, Anders
    et al.
    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.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Luleå University of Technology, Department of Engineering Sciences & Mathematics, Energy Engineering.
    Understanding reactivity using fuel design - phosphorus vs kaolin in combustion of stem wood2016Conference paper (Other academic)
    Abstract [en]

    The fate of various ash-forming elements determine how well a fuel will perform in a given thermochemical energy conversion process. In order understand ash-related process problems it is particularly important in which compounds alkali metal ions, for biomass this primarily means K+ and Na+, are bonded. Their low charge and relatively large ionic radii leads to poor bond strengths in compounds where they provide the only Lewis acid component, i.e. electron acceptor. This can be remedied by trying to bond alkali metal ions to stronger, predominantly molecular Lewis bases which is the case in for instance arkanite, K2SO4 – the targeted reaction product when (NH4)2SO4 is added in the flue gas to reduce KCl formation. Another approach is to bond alkali in bottom or bed ash, by including Lewis base forming elements such as phosphorus or the additive kaolin which is dominated by kaolinite. This route attempts to promote formation of high-temperature melting compounds with at least one alkali metal ion per phosphate or other starting molecule.

    While the understanding of how phosphorus reacts in combustion process is increasing it is valuable to understand how it will react in presence of other elements or molecules that play an important role for alkali capture. This will be of interest in situations where the base fuels may be combusted with addition of sulphur or kaolin, for instance. If the base fuels has a high concentration of phosphorus the amount of additive may need to be adjusted according to what phosphates will form, and if they will form even in the presence of the amending additives. Using the inherent composition of the fuel to decide suitable strategies for additive choice or possibly co-combustion is a key component of fuel design.

    The aim of this study is to investigate the relative Lewis base potential for capture of alkali metal ions between phosphates and kaolin. This is made by adding highly available phosphorus in the form of di-ammonium hydrogen phosphate, (NH4)2HPO4, and kaolin, a mineral where kaolinite is the main constituent for capturing alkali to the fuel blend. The fuel chosen is stem wood where the amount of Lewis acid forming elements greatly surpass that of Lewis base forming elements found in the ash forming matter.

  • 243.
    Rebbling, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Näzelius, Ida-Linn
    Piotrowska, Patrycja
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    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.
    Ohman, Marcus
    Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 2. Fixed Bed2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 12, p. 10705-10713Article in journal (Refereed)
    Abstract [en]

    This paper is the second of two describing the use of shredded waste gypsum board (SWGB) as an additive during combustion of biomass. The focus of this paper is to determine whether SWGB can be used as a fuel additive providing CaO and SO2/SO3 for mitigation of ash-related operational problems during combustion of biomass and waste derived fuels in grate fired fixed bed applications. The former study in this series was performed in a fluidized bed and thus allow for comparison of results. Gypsum may decompose at elevated temperatures and forms solid CaO and gaseous SO2/SO3 which have been shown to reduce problems with slagging on the fixed bed and alkali chloride deposit formation. Three different biomasses, spruce bark (SB), reed canary grass (RG), and wheat straw (WS), were combusted with and without addition of SWGB in a residential pellet burner (20 kWth). Waste derived fuel with and without the addition of SWGB was combusted in a large scale grate-fired boiler (25 MWth). The amount of added SWGB varied between 1 and 4 wt %. Ash, slag, and particulate matter (PM) were sampled and subsequently analyzed with scanning electron microscopy/ energy dispersive spectroscopy and X-ray diffraction. Decomposition of CaSO4 originating from SWGB was observed as elevated SO2 emissions in both the large scale and small scale facilities and significantly higher than was observed in the fluidized bed study. Slag formation was significantly reduced due to formation of calcium-silicates in small scale application, but no conclusive observations regarding calcium reactivity could be made in the large scale application. In the small scale study the formation of K2SO4 was favored over KC1 in PM, while in the large scale study K3Na(SO4)(2) and K2Zn2(SO4)(3) increased. It is concluded that SWGB can be used as a source of CaO and SO2/SO3 to mitigate slag formation on the grate and chloride-induced high temperature corrosion and that fixed bed applications are likely more suitable than bubbling fluidized beds when using SWGB as an additive.

  • 244. Reinik, Janek
    et al.
    Heinmaa, I
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kordas, K
    Kirso, U
    Synthesis of calcium-alumino-silicate hydrates from oil shale ash in different alkaline media2010In: Gorûcie slancy, ISSN 0208-189X, E-ISSN 1736-7492, Vol. 27, no 1, p. 47-57Article in journal (Refereed)
    Abstract [en]

    Synthesis of Ca-Al-Si-hydrates from oil shale ash using NaOH, KOH and OH-substituted alkaline ionic liquid was carried out. The material from ionothermal activation was used in carbon dioxide fixation experiments. The influence of the alkaline medium on the activation of oil shale fly ash was studied using physisorption (BETN2), SEM/EDX, FESEM, XRD, and Si-29 high-resolution MAS-NMR measurement techniques. In the presence of strong alkali (8 M NaOH) the silicon in the original fly ash was completely converted into Ca-Al-Si-hydrates, mainly into tobermorite and katoite structure during 24-hour treatment at 160 degrees C. In similar reaction conditions, the hydrothermal activation with KOH converted fly ash into tobermorites only partially. The silicon was not converted into Ca-Al-Si-hydrates by ionothermal activation with OH-substituted alkaline ionic liquid, tricaprylylmethylammonium hydroxide, either with conventional or microwave heating. It was found that both the original material and ionothermally activated oil shale ash displayed similar CO2-adsorption capacity.

  • 245.
    Renman, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Modelling and simulation of Villa Falk: Trade-off between valve operations and the room temperature2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis has been carried out on behalf of Umeå University. The thesis has a dual objective. Firstly, an advanced energy simulation model of a real house, (Villa Falk), is developed with the software IDA ICE. Main focus of this model has been on the modelling of the whole house, the envelope with all the thermal zones and the Heating Ventilation Air Conditioning (HVAC) system. The second objective is to investigate how indoor temperature change in relation to different types of controls of the underfloor heating.

    Villa Falk was a part of CERBOF project "Energy-efficient construction in cold climates". The house has been monitored since year 2011. In particular, ventilation, heating, domestic hot water, solar panel system has been observed for providing energy meters during the years. These data have been used for developing input curves for the simulation model.

    The results of the energy simulation model of Villa Falk shows large discrepancies with the measured data. In particular, the position of the immersed heater and its operations, mostly affect the final outcomes of the model. Moreover a detail list of all the uncertain measured is ranked at section 5.2 of this report.

    The second objective is achieved by investigating several control strategies of the floor heating system. For this purpose, a simple house made by two adjacent zone is analyzed. Step response test of the underfloor heating system is carry out in order to apply Nichols-Ziegler heuristic theory for tuning the control. Several control has been tested and results are compared for showing the potential and difference among controls.

    The results of the control strategies applied to the underfloor heating is provided by covering different aspects. Firstly, the trade-off between indoor temperature and mass flow rate. The variation of latter parameter indicates how many operations the valve of the underfloor heating has to make in order to maintain a comfort temperature in the thermal zone. Secondly, the proportional control works best for the indoor climate, thus the comfort of the occupants with a PPD value of 12.6%. Whereas the ON/OFF control shows worsen results with a PPD of 22,3 %. Moreover, the results show how the slab thickness of the underfloor heating influence the indoor comfort.

  • 246. Rhén, Christofer
    et al.
    Öhman, Marcus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Gref, Rolf
    Wästerlund, Iwan
    Effect of raw material composition in woody biomass pellets on combustion characteristics2007In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 31, no 1, p. 66-72Article in journal (Refereed)
    Abstract [en]

    Char yield, char combustion time and char combustion rate of pellets made from different tree parts of Norway spruce and industrially made stem wood pellets of Norway spruce and Scots pine were studied. The pellets were incinerated in a laboratory scale oven at various temperatures, gas flows and oxygen concentrations. It was found that the combustion time for a single pellet mostly depended on the raw material composition and to a minor extent on the density. Pellets made of bark had up to a 50% longer char combustion time compared to that of stem wood pellets, due to differences in char yield. Industrially made stem wood pellets of pine and spruce sawdust were found to have small differences in combustion characteristics. The variations in combustion characteristics of pellets are discussed in relation to composition of raw material.

  • 247.
    Risberg, Ylva
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utvärdering av energiprojektering för Hedlunda passivhusförskola: Assessment of the projected energy demand for a passive house preschool at Hedlunda2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At Hedlunda in Umeå, there’s a building complex containing a combined preschool, canteen and catering kitchen. It was built in 2014 and the preschool started up the same year. Sweco projected the building to satisfy the requisites required for the international passive house certification. The building was also supposed to meet specific requirements for specialized pedagogy, and requirements for non-toxic building materials in preschools, amongst others. In this master thesis the building’s energy usage was studied to see if the building met the requested requirements, and how close the estimated energy demand was to the actual demand. The purchased energy was also compared to energy requirements used by other certification systems used in Sweden today.

    The building meets the international passive house requirement for the annual heating demand, but breaches the requirement for primary energy value by 4 %. The Swedish passive house requirement is met with a significant margin.

    The purchased energy per square meter was 43 kWh /m2 year , which differed only marginally from the projected value of 41 kWh /m2 year . It may seem as if it was a very good estimation of the purchased energy, but when the factors are studied individually there are differences among them that go up to 60 %. The purchased energy per square meter was lower than all of the other requirements in other energy certification systems which proves that this is a highly efficient building.

    The building was created with the main purpose of serving as a model for energy efficient buildings, and it has served its purpose since Vegaskolan in Vännäs was built within the same concept.

    All in all, Hedlunda preschool is a building with a very good energy performance. If all public buildings who gained building permit in 2015 in Sweden had been built with the same energy efficiency as Hedlunda preschool, then the total energy demand would be 392 GWh /year , whereas if they were built as the BBR-standard the corresponding energy demand would be 1098 GWh /year . This is just a rough estimation to give a hint of the amount of energy that can be saved.

  • 248.
    Rossing, Jonas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Solvärme i småskaligt fjärrvärmenät: Förutsättningar och möjligheter för Umeå Energi2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Renewable energy production is a central part of a sustainable society. Therefore it is today important with investments in new technology and solutions in this field. The sun provides constantly earth with energy. To obtain and utilize this energy is both environmental friendly and quite simple. This report aims to investigate the possibilities of integrating solar energy with district heating in the district heating grid in Hörnefors owned by Umeå Energi.

    Two alternatives for connection of solar thermal collectors to the district heating grid have been studied. In the first alternative, called primary connection, solar collectors are connected to the district heating primary pipe and are therefore able to deliver heat to the whole grid. In the second alternative, called secondary connection, solar collectors are connected to a single user on the district heating grid, in this case a swimming pool complex.

    Different types of solar thermal collectors were also investigated, including a flat plate collector, an evacuated pipe collector, a hybrid collector and a pool collector.

    The results revealed that up to 20 % of the total heat demand in the grid could be replaced by solar heating by using the primary connection and about 0,7 % by using the secondary connection. However are none of the alternatives cost-effective at the moment. The best alternative was the secondary connected pool collector. The present value ratio for this alternative was 0,43. The other alternatives had ratios from 0,11 to 0,22.

  • 249.
    Ruda, Ida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Upprättande av långsiktiga energimål för Västerbottens läns landsting2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete utfördes våren 2015 på uppdrag av Västerbottens läns landsting. Syftet med arbetet har varit att hjälpa landstinget inför implementeringen av energiledningssystemet ISO 50001, genom att ta fram mål för fastighetsbeståndets specifika energianvändning år 2050, utföra en omvärldsanalys av andra landstings energianvändning, samt ta fram nyckeltal relevanta för verksamheten. Målet 2050 har bestämts utifrån planerade åtgärder för energibesparing, och en simulering av klimatskalsförbättringar på byggnader med höga U-värden. Simuleringen utfördes i programmet IDA ICE med handledningshjälp från Sweco Systems AB i Umeå. Resultatet visade på att landstinget kan nå en specifik energianvändning på 215 kWh/m2 till år 2050, motsvarande en minskning av den totala energianvändningen med 23 % jämfört med år 2009. Då 2050 är så pass långt fram i tiden och det finns stora möjligheter för teknikutveckling och ytterligare energibesparande åtgärder kan detta mål höjas till 30 %, motsvarande 196 kWh/m2. Eftersom specifik energianvändning inte ger en rättvis bild av hur effektivt energin nyttjas har även nyckeltalen specifik energianvändning per vårdtillfälle och specifik energianvändning per länsinvånare analyserats.

  • 250.
    Råberg, Mathias
    Umeå University, Faculty of Science and Technology, Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Black liquor gasification: experimental stability studies of smelt components and refractory lining2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Black liquors are presently combusted in recovery boilers where the inorganic cooking chemicals are recovered and the energy in the organic material is converted to steam and electricity. A new technology, developed by Chemrec AB, is black liquor gasification (BLG). BLG has more to offer compared to the recovery boiler process, in terms of on-site generation of electric power, liquid fuel and process chemicals. A prerequisite for both optimization of existing processes and the commercialization of BLG is better understanding of the physical and chemical processes involved including interactions with the refractory lining. The chemistry in the BLG process is very complex and to minimize extensive and expensive time-consuming studies otherwise required accurate and reliable model descriptions are needed for a full understanding of most chemical and physical processes as well as for up-scaling of the new BLG processes. However, by using these calculated model results in practice, the errors in the state of the art thermochemical data have to be considered. An extensive literature review was therefore performed to update the data needed for unary, binary and higher order systems. The results from the review reviled that there is a significant range of uncertainty for several condensed phases and a few gas species. This resulted in experimental re-determinations of the binary phase diagrams sodium carbonate-sodium sulfide (Na2CO3-Na2S) and sodium sulfate-sodium sulfide (Na2SO4-Na2S) using High Temperature Microscopy (HTM), High Temperature X-ray Diffraction (HT-XRD) and Differential Thermal Analysis (DTA). For the Na2CO3-Na2S system, measurements were carried out in dry inert atmosphere at temperatures from 25 to 1200 °C. To examine the influence of pure CO2 atmosphere on the melting behavior, HTM experiments in the same temperature interval were made. The results include re-determination of liquidus curves, in the Na2CO3 rich area, melting points of the pure components as well as determination of the extent of the solid solution, Na2CO3(ss), area. The thermal stability of Na2SO3 was studied and the binary phase diagram Na2SO4-Na2S was re-determined. The results indicate that Na2SO3 can exist for a short time up to 750 °C, before it melts. It was also proved that a solid/solid transformation, not reported earlier, occurs at 675 ± 10 °C. At around 700 °C, Na2SO3 gradually breaks down within a few hours, to finally form the solid phases Na2SO4 and Na2S. From HTM measurements a metastable phase diagram including Na2SO3, as well as an equilibrium phase diagram have been constructed for the binary system Na2SO4-Na2S. Improved data on Na2S was experimentally obtained by using solid-state EMF measurements. The equilibrium constant for Na2S(s) was determined to be log Kf(Na2S(s)) (± 0.05) = 216.28 – 4750(T/K)–1 – 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as ΔfG°(Na2S(s))/(kJ mol–1) (± 1.0) = 90.9 – 4.1407(T/K) + 0.5415849(T/K) ln (T/K). The standard enthalpy of formation of Na2S(s) was evaluated to be ΔfH°(Na2S(s), 298.15 K)/(kJ mol–1) (± 1.0) = – 369.0. The standard entropy was evaluated to be S°(Na2S(s), 298.15 K)/(J mol–1 K–1) (± 2.0) = 97.0. Analyses of used refractory material from the Chemrec gasifier were also performed in order to elucidate the stability of the refractory lining. Scanning electron microscopy (SEM) analysis revealed that the chemical attack was limited to 250-300 μm, of the surface directly exposed to the gasification atmosphere and the smelt. From XRD analysis it was found that the phases in this surface layer of the refractory were dominated by sodiumaluminosilicates, mainly Na1.55Al1.55Si0.45O4.

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