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  • 1.
    Abrahamsson, Linnéa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energianvändning vid pelletering: En undersökning av strömningsenergins betydelse för den totala energianvändningen vid pelletering2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Biofuels make up 25% of Sweden’s energy supply and the majority of biofuels used are made from wood. Wood pellets is one type of biofuel and in Sweden, 1.6 million tonnes of wood pellets were produced in 2018. Different pellet properties such as durability and energy use for production is often tested in a single pellet press. The total energy use for making a pellet in an industrial scale machine is the sum of the energy required for three different component sequences, compression, friction and flow. Flow is when the material that lies on the surfaces between the press channel openings is compressed and pushed downwards towards the coned openings and the materiel in the coned opening is deformed and pushed down to the press channel.

    Only compression and friction can be studied using a conventional single pellet press. Thus, this study focuses on the impact of the flow component on the total energy use for pelletizing. In order to do this, energy used for compression, friction and flow, as well as the power required for the material to enter the flow component, Fflow, has been studied for three different particle sizes.

    Fresh spruce with a moisture content of 10% has been pressed in different dies. With these pressings, the impact of the flow component, as well as the impact of pressing material located around the coned press channel opening on the total energy use was determined.

    Particle size did not affect energy use. Fflow was higher for pressings with material located on the surface around the coned opening, compared to pressings without. This resulted in an increased compression energy for pressings with material around the coned opening. The material located around the press channel opening affected the pelletizing so that the produced pellet was 1 mm shorter, which resulted in a lower energy use for the friction component. Energy used by the flow component made up over 43-57% of the total energy use. The part of the flow energy that is needed to compress the material around the press channel opening and move that material towards the opening stood for 35-52% of the total energy use for palletization.

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  • 2.
    Adolfsson, Antonia
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Off grid boende: Dimensionering samt värdering av möjliga system för hantering av avlopp och energiförsörjning2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Bostadsbristen är ett ständigt faktum i Sverige idag och i takt med att boendepriserna ökar så ökar också intresset för att bygga sin egen bostad. Arkitektfirman Tengbom i Karlstad har startat upp ett projekt, Portable Empowerment, som bygger på visionen om att skapa en portabel bostad som ska kunna fungera som en lösning när ett plötsligt behov av bostäder uppstår. För att bostäderna ska kunna flyttas runt krävs det att lösningar för energi- och avloppssystem finns integrerade i bostaden och ska kunna flyttas med för att göra bostaden portabel. För att detta ska vara möjligt krävs det avlopps- och energisystem som är off grid.

    Off grid betyder att systemet inte är kopplat till kommunalt avlopp eller elnät. Det finns sedan länge sätt att lösa både avlopp och energiförsörjning off grid och några exempel där det tillämpas är husvagnen och den klassiska sommarstugan, men de är allt som oftast inte anpassade för bruk året runt. Målet med denna studie är att identifiera samt värdera avlopps- och energisystem som kan tillgodose behoven i en liten bostad som brukas året runt av två personer. Bostaden har sin utgångspunkt i de ritningar som tagits fram av Tengbom för deras projekt Portable Empowerment.

    För att identifiera system som kan tillgodose behoven i bostaden har modeller byggts upp och simuleringar skett där system lämpade för off grid inkluderats. Lösningarna har sedan jämförts med varandra med hjälp av värderingsmatriser där portabilitet, kostnad, miljö och användarvänlighet för varje system värderats.

    Resultatet av studien visar att det finns flera system för både energi och avlopp som kan tillgodose behoven i bostaden året om. Flera av systemen uppfyller kraven för en portabel bostad och det är med andra ord möjligt att uppfylla Tengboms vision om ett fullständigt portabelt boende. Jämfört med en ”vanlig” bostad som är ansluten till vatten- och elnät är dock off grid-lösningarna betydligt mer tidskrävande. Genom att installera ett eget system med lösningar för enbart den egna bostaden tar brukaren också på sig det fulla ansvaret, något som kan tänkas vara en belastning för vissa brukare och en frihet för andra.

    Ur ekonomisk synpunkt visar studien att på energisidan är det svårt att hitta ett off grid-system som är billigare än on grid-systemet där en luftvärmepump installerats. Däremot är anslutningen till ett kommunalt avlopp betydligt dyrare, mellan 100 000-150 000 kronor mer, än att anlägga till exempel en egen infiltrationsanläggning i anslutning till den egna bostaden.

    För att utveckla denna studie bör möjligheten att bygga off grid-byar undersökas. Genom att bygga upp ett samhälle om ett stort bostadsbehov skulle uppstå kan energi- och avloppsanläggningar delas. Anläggningarna har större kapacitet och genom att dela på dessa kan både ansvar och kostnad minskas.

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  • 3.
    Almered Olsson, Gunilla
    et al.
    Norges Teknisk-Naturvitenskapelige Universitet, Trondheim, Norge.
    Bladh, GabrielKarlstad University, Division for Social Sciences.Månsson, BengtKarlstad University, Division for Engineering Sciences, Physics and Mathematics.Nyberg, LarsKarlstad University, Division for Environmental Sciences.
    Inte bara träd: hållbart mångbruk av skogslandskapet2004Collection (editor) (Refereed)
    Abstract [sv]

    Skogslandskapen - hur skall vi värdera dem? Ska de betraktas som rekreationsområden och kulturlandskap eller som arena för konflikter och dragkamp om olika resurser? Är skogsregionerna närande eller tärande? Vilka viktiga samband finns mellan skandinaviska och tropiska landskap?Detta är några av de teman som behandlas i denna spänannde bok om de många dimensionerna och resurserna som ryms i skogslandskapen. Boken ger nya och stimulerande aspekter på framtidsmöjligheterna för en hållbar utveckling för boreala skogslandskap. Den tar också upp det nödvändiga mångbruket av skogens resurser liksom den förändrade synen på människans roll i skogen. Och inte minst behandlas den ekologiska paradoxen att störningar behövs för att bevara skogens ekologiska mångfald.Boken är författad av samhällsvetare, miljöteknologer och ekologer inom den tvärvetenskapliga forskargruppen MiljöFocus vid Karlstads universitet.

  • 4. Anderson, L. G.
    et al.
    Björk, G.
    Holby, Ola
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kattner, G.
    Koltermann, P. K.
    Jones, E. P.
    Lindegren, R.
    Rudels, B.
    Swift, J.
    Water masses and circulation in the Eurasien Basin: Results from the Oden 91 expedition1994In: Journal of Geophysical Research, Vol 99, No. C2: 3273-3283Article in journal (Refereed)
  • 5. Anderson, Leif G.
    et al.
    Holby, Ola
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ohlson, Mats
    Lindegren, Roger
    The transport of anthropogenic carbon dioxid into the Weddell sea1991In: Journal of Geophysical Research, Vol 96, No. C9: 16,679-16,687Article in journal (Refereed)
  • 6.
    Andersson, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Energianvändning för att överkomma visköst motstånd i material vid pelleteringsprocesser: Metodutveckling för kontinuerlig pelletering i singelpelletpress2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att motverka global uppvärmning är det centralt att världen rör sig från fossila bränslen för energiproduktion och mot alternativa energiresurser som biobränslen. Industriella restprodukter – exempelvis sågspån – är ett bra alternativ för framställning av biobränslen då annars oanvändbara material kommer till användning. För att göra sådana material mer lätthanterliga komprimeras de ofta till pellets. Den globala pelletsmarknaden har ökat med ungefär 14 % årligen sedan 2010.

    Pelleteringsprocessen kan delas upp i tre faser: komprimering, strömning och friktion. Energianvändningen i pelleteringsprocessen går till komprimering av materialet; till att deformera materialet och överkomma det viskösa motståndet; och till att överkomma friktionen mellan materialet och presskanalväggarna. För att undersöka energianvändningen för pelletering på laboratorieskala används ofta singelpelletpressar.

    Syftet med den här studien är att öka kunskapen kring energianvändningen vid pelletering, med det huvudsakliga målet att vidareutveckla test- och beräkningsmetoder för att bestämma energianvändningen för att överkomma det viskösa motståndet i materialet vid pelletering i singelpelletpress.

    Materialet som pelleterades i studien var granspån. För att bestämma energianvändningen till att överkomma det viskösa motståndet i materialet etablerades ett jämviktssystem i singelpelletpressen, där presskraften stabiliserades med successiva pressningar – kallat kontinuerlig pelletering. Matrisuppställningen i singelpelletpressen inkluderade en kona, där materialet tvingas ner från en presskanal med en större diameter till en presskanal med en mindre diameter för att inkludera strömningsfasen. För att uppnå ett jämviktstillstånd kontrollerades friktionsmotståndskrafterna mot strömning av materialet genom att variera längden på den aktiva presskanalen (där det komprimerade materialet under konan har kontakt med presskanalväggen). Tillfället då strömning initierades undersöktes för att separera komprimeringsfasen från strömnings-/friktionsfasen. Separata komprimerings- och friktionsförsök gjordes för att subtrahera energianvändningen till komprimering och till att överkomma friktion från den totala energianvändningen – för att komma åt energianvändningen till att överkomma det viskösa motståndet.

    Jämviktstillståndet nåddes och kontinuerlig pelletering utfördes med en materialfukthalt på 17,5 % och en aktiv presskanallängd på 13 mm, där det högsta uppmätta presstrycket för varje successivt försök stabiliserades runt 154 MPa och pellets med densiteten 1200 kg/m3 producerades. Medelvärdet på trycket som krävdes för att initiera strömning blev 123 MPa. Den specifika energianvändningen som gick till att överkomma materialets viskösa motstånd blev 88 J/g material, vilket motsvarade 65 % av den totala energianvändningen.

    Motståndskrafterna mot presskraften från friktionen mellan pelleten och presskanalväggen ökade exponentiellt i förhållande till längden på pelleten i den aktiva presskanalen, vilket innebär svårigheter med att etablera önskade jämviktstillstånd genom en enbart teoretisk bestämning av den aktiva presskanallängden; experimentella försök behöver alltså göras.Den kontinuerliga pelleteringen i studien gjordes vid ett lägre presstryck än vid industriella processer för att inte överbelasta utrustningen. Densiteten för pelleten som tillverkades hamnade dock inom industriella intervall, vilket validerar metoden i studien. För att undersöka jämviktstillstånd vid högre presstryck kan längden på den aktiva presskanalen ökas.

    Metoden i studien förenklar vissa aspekter av kraftförhållanden och strömningens egenskaper. Vidare studier rekommenderas angående Poissoneffekten i konan, visköst motstånd i materialet i den aktiva presskanalen som konsekvens av en ojämn hastighetsprofil och en potentiell övergångsfas mellan komprimeringsfasen och strömnings-/friktionsfasen.

    Studien visar att kontinuerlig pelletering i singelpelletpress fungerar och för framtida studier på energianvändningen vid pelletering som använder singelpelletpressar rekommenderas att en uppsättning matriser med olika längder på den aktiva presskanalen konstrueras för att enkelt kunna upprätta ett jämviktstillstånd för kontinuerlig pelletering. Att andelen av den totala energianvändningen som gick till att överkomma det viskösa motståndet i materialet blev så hög belyser vikten av fortsatta studier kring det viskösa motståndet för att vidare kunna energieffektivisera pelleteringsprocessen.

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  • 7.
    Andersson, Hedda
    Karlstad University.
    El-och värmeenergibehov för skolor: Beräknade och uppmätta värden för 4 skolor i Stockholm2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As buildings are built more and more energy-efficient, precision of energy calculations needs to increase as the error decrease and the requirement to calculate “correctly” increases. At the beginning of a construction project, a builder must show that the building will comply with the National Board of Housing, Building and Planning's regulations when the project is completed in order to start the project. When the building is finished, it is tested through different feeds to investigate whether the building meets the requirements that the builder has claimed in the design step. The difficulty of calculating the energy requirement of a building so that it corresponds to the measured energy requirement is well known in the construction industry. In a school, heating of premises and tap water accounts for two thirds of the energy use and one third consists of lighting, kitchens and fans for ventilation. In a study with 7 newly built Swedish schools calculated and measured energy was examined, it was found that calculated and measured energy needs differed between -44% to + 28%. 

    To make it easier to produce calculations of schools energy needs that correspond to real energy needs, this report examines which parameters are important for a school's energy needs and which parameters that makes the calculated and measured energy needs differ profoundly. Two preschools and two primary schools were examined in this study. A calculation model was built to examine which parameters have the greatest impact on a school's energy needs and to calculate the schools' energy needs. 

    The measured and estimated heat energy requirements in the examined schools had a deviation of -3% and -16%. The measured and calculated electricity energy needs in the schools had a deviation of -2% and + 28%. The parameters that were important when calculating a school's energy needs turned out to be the efficiency of ventilation, tap water consumption, g-value, room temperature, supply air temperature, operating time of ventilation, operating time of commercial kitchens and electricity requirements for commercial kitchens. 

    The result showed that when making energy calculations and trying to adjust and match it as closely as possible to the real measured values, the parameters with the most impact on this were efficiency of ventilation, g-value, supply air temperature, electricity demand for the commercial kitchen and the operating times of both the ventilation and the commercial kitchen. 

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  • 8.
    Andersson, Ronja
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Energimärkning torktumlare: Utredning av energimärkningen på torktumlare samt möjliga förbättringsåtgärder vid körningar med liten last2016Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Different parts of the world use energy in different ways and for different purposes. In Sweden the subsector Laundry and Drying represented 6% of the country’s total electricity use in 2007. In the early 80s it was the big household appliances the dominated the increase of energy use in buildings whereas in recent years have been smaller home electronics and small kitchen appliances that have taken the lead. Due to that the need of energy is constantly increasing a more efficient energy use needs to occur. One step in the right direction was made when the publication of the Brundtland Commission and the term ”Sustainable Development” was born.

     

    In Europe the European Union has a goal that in 2020 the energy use shall be reduced by 20% compared to the forecasted use. To reach the goal they have among other things created the eco-design and the energy labelling directives. These directives are designed to improve the products environmental impact during their whole lifecycle and make it easier for the consumers to compare products from an energy perspective with the help of an energy label. For tumble dryers this energy label has been redesigned to more accurately reflect how much energy that is used when the appliances are running.

     

    In this thesis a comparison of the old and the new energy labelling has been made. Beyond this a consumer survey of how the tumble dryers actually are used in the Swedish households has been performed. Based on this, three suggestions of improvement measures when drying small loads have been investigated regarding to energy use, expenditure of time and final moisture content. A tumble dryer has been used to make the comparison between the two labels. Test runs with full and half loads has been run and the results have been used to calculate the energy efficiency classes for both labels. The three improvement measures were run at half load according to the new label, but with changes to external flow adjustment, internal flow adjustment and tennis ball in the drum separately.

     

    The old energy labelling resulted in energy efficiency class D, right on the border to C, and the new labelling in class C. Although the results seem to be equivalent they differ due to the different scales of the labels. According to the old label the dryer resulted at level 4 but according to the new it resulted at level 6 and is therefore less energy efficient when the runs with half load is taken into account.

     

    The consumer survey showed that the load sizes vary a lot from person to person but with an average load of 4,75 kg dry laundry.

     

    The investigation of the suggestions of improved measures showed a very small difference of the energy use, the expenditure of time was better but the textiles got a higher final moisture content compared to the results from the normal method of drying. These three suggestions of improvement are therefore considered to need further investigation or to be replaced.

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  • 9.
    Anukam, Anthony
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Henrikson, G.
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A review of the mechanism of bonding in densified biomass pellets2021In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 148, article id 111249Article in journal (Refereed)
    Abstract [en]

    The production of durable biomass pellets have always been challenged by several factors including the lack of understanding of the mechanism involved in how particles combine to form pellets under standard conditions of the pellet press. This is because contributing factors span several molecular, microscopic, and even nanoscopic levels as biomass undergoes pelleting. The characteristics of the bonds formed between the combining particles and their relevance to the quality of pellets remains vague, no matter how quality is defined. However, even though few researchers have attempted to explain the mechanism of bonding in densified biomass pellets using different theories, none of their hypotheses supports particle bonding from a structural chemistry perspective. There are still no clear explanations which consider the role of molecular structure and the interactions of substances as milled biomass undergo pelleting. In view of these arguments therefore, this review presents an in-depth analysis of a structural chemistry perspective of the mechanism of bonding and the use of additives in densified biomass pellets and helps identify research areas needed to facilitate better understanding of bonding in densified biomass pellets. The status of current research in biomass pelleting, types of materials suitable as additives and their structural characteristics, as well as the current technical specifications of using additives are also discussed.

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  • 10.
    Anukam, Anthony
    et al.
    Univ Ft Hare, South Africa.
    Meyer, Edson
    Univ Ft Hare, South Africa..
    Okoh, Omobola
    Univ Ft Hare, South Africa..
    Mamphweli, Sampson
    Univ Ft Hare, South Africa..
    Gasification characteristics of sugarcane bagasse2012In: PROCEEDINGS OF SAIP2012: THE 57TH ANNUAL CONFERENCE OF THE SOUTH AFRICAN INSTITUTE OF PHYSICS / [ed] J. J. VanRensburg, SOUTH AFRICAN INST PHYSICS , 2012, p. 464-471Conference paper (Refereed)
    Abstract [en]

    Sugarcane bagasse is a residue that results from the crushing of sugarcane in the sugar industry. Among the various agricultural crop residues, sugarcane bagasse is the most abundant lignocellulosic material in tropical and sub-tropical countries including South Africa. Bagasse is a renewable feedstock that can be used for power generation and manufacturing cellulosic ethanol In the sugarcane industries the bagasse is mainly burnt inefficiently in boilers that provide the heating for the industry. This project seeks to investigate the possibility of gasifying sugarcane bagasse as an efficient conversion technology. Proximate and ultimate analysis of sugarcane bagasse was conducted after which the results were used to conduct computer simulation of the mass and energy balance during gasification. This paper presents the proximate and ultimate analysis as well as the computer simulation results.

  • 11.
    Aupke, Phil
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Seema,
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Theocharis, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Archer, Dan-Eric
    CheckWatt AB, Sweden.
    PV Power Production and Consumption Estimation with Uncertainty bounds in Smart Energy Grids2023In: 2023 IEEE International Conference on Environment and Electrical Engineering and 2023 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), IEEE, 2023Conference paper (Refereed)
    Abstract [en]

    For efficient energy exchanges in smart energy grids under the presence of renewables, predictions of energy production and consumption are required. For robust energy scheduling, prediction of uncertainty bounds of Photovoltaic (PV) power production and consumption is essential. In this paper, we apply several Machine Learning (ML) models that can predict the power generation of PV and consumption of households in a smart energy grid, while also assessing the uncertainty of their predictions by providing quantile values as uncertainty bounds. We evaluate our algorithms on a dataset from Swedish households having PV installations and battery storage. Our findings reveal that a Mean Absolute Error (MAE) of 16.12W for power production and 16.34W for consumption for a residential installation can be achieved with uncertainty bounds having quantile loss values below 5W. Furthermore, we show that the accuracy of the ML models can be affected by the characteristics of the household being studied. Different households may have different data distributions, which can cause prediction models to perform poorly when applied to untrained households. However, our study found that models built directly for individual homes, even when trained with smaller datasets, offer the best outcomes. This suggests that the development of personalized ML models may be a promising avenue for improving the accuracy of predictions in the future.

  • 12.
    Axelsson, Tobias
    Karlstad University.
    Stöd till energi- och klimatrådgivnin: Solceller samt energilagring med batterier och svänghjul2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are many paths towards a more sustainable future. One way is to be more efficient with the use of energy in our daily lives. Another way is to work towards an increasing share of renewable energy in the energy mixture. The municipalities in Sweden has since the late 70s employed experts to provide the citizens with energy advice. This study was performed to provide additional information and inspiration for the benefit of these energy and climate advisors. In this article the author has conducted a literature compilation/review regarding the subject solar PV since the advisors deal with a lot of questions regarding this subject. The literature compilation also includes the subject energy savings and energy storage. An internet-based survey and a focus group discussion are also included to improve understanding of how the respondents think and feel about solar PV and their energy habits. It turns out to be hard to find information that eases the purchase and installation of solar panels. The advisors should make use of the people who already uses solar power in the municipally. These people can provide information regarding dealers and contractors as well as provide exposure for solar PV itself. The results also show that a lot of people cannot afford to invest in solar power. Therefore, it is important not to neglect advice regarding energy savings. Especially since it turns out that most respondents care about their environmental footprint and are willing to make changes, but are not always sure of what to do. This seems to indicate that general energy saving tips that reaches a lot of people would be effective. As an energy and climate advisor you should also try to help people to help themselves get more and better feedback regarding their energy usage. To remind the inhabitance of the municipally that regular maintenance should be performed on the home itself as well as on certain devices seems to be an effective strategy. Lastly people would benefit from simple statistics to help them get a better understanding for which devices uses the most energy. This would give them a knowledge foundation that would ease future device investments. To add further to this paper, a life-cycle costing analysis for a typical Swedish home equipped with solar PV and energy storage is used to determine if a hybrid energy storage system (mechanical and chemical) can rival more traditional storage solutions. The most promising hybrid system is 30 kWh divided in a 3:17 ratio between flywheel and batteries. However, from an economic standpoint battery storage still outperformed the system with a small margin.

  • 13.
    Ayedi, Omar
    Karlstad University, Faculty of Technology and Science, Avdelningen för energi-. miljö- och byggteknik.
    Energieffektiv torkning av kläder: en studie av torktumlare med varm- respektive kallvattenanslutning2011Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Tumble dryers and drying cabinets have to a large extent replaced the traditional way of drying clothes outdoors. They are faster, more convenient, require less space and can be operated regardless of weather conditions. This replacement has significantly increased residential energy consumption, due to the fact that tumbles dryers consume large amounts of electrical energy. In the USA 9 % of the households electric energy is consumed when drying clothes. Over 4 million tumble dryers are sold in Europe each year and 20 % of the residential electricity consumption in Sweden is used drying and washing clothes. Tumble dryers are also utilized in the industrial sector, but industrial dryers are not considered in this study.Increasing energy costs contributes to the public’s awareness and desire to cut their energy consumption. The aim of this study is to increase the energy efficiency and drastically reduce electric power use of tumble dryers.There are two main types of tumble dryers available on the market; the open cycle tumble dryer and the closed cycle tumble dryer. The open cycle tumble dryer is often attached to the ventilation system and thereby it evacuates its exhaust air. The closed cycle tumble dryer condenses the water from the air before it recirculates it.To increase the energy efficiency and reduce electric power use of tumble dryers, two separate studies were made. One on a water cooled closed cycle tumble dryer and one on a hot water heated open cycle tumble dryer. Both tumble dryers where rebuild and originated from the same tumble dryer. The tumble dryer that both studies originated from was a conventional air cooled closed cycle tumble dryer. The tumble dryer is made by Asko Cylinda AB.The results reveal that the water cooled closed cycle tumble dryer does not have greater energy efficiency than the conventional air cooled closed cycle tumble dryer. However the drying time was reduced by 37 %.The result also reveals that the hot water heated open cycle tumble dryer cuts the electric consumption by 93 % and improves the energy efficiency by 53 % compared to the conventional air cooled closed cycle tumble dryer. On the other hand the drying time increases by 9 %.

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  • 14.
    Azrak, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Ekonomisk optimering av en vätgasanläggning med sektorkoppling till ett fjärrvärmesystem2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Increased human activity and global population have led to an increased energy demand, with most of the energy coming from fossil fuels. Hydrogen is seen as an efficient energy carrier that can be produced using renewable resources and replace fossil fuels. However, hydrogen produced from renewable resources is still expensive compared to production from fossil fuels. There have been few previous studies that have examined the utilization of waste heat from hydrogen facilities and the impact it can have on economic profitability.This study, conducted in collaboration with Research Institutes of Sweden (RISE), aims to optimize a hydrogen production facility, with a predefined hydrogen demand, from an economic perspective and assess whether a sector coupling to a district heating network can improve the economic outcome. In this study, sector coupling means that waste heat is sent from the hydrogen facility to the district heating network. The hydrogen plant consists of an electrolyzer, a fuel cell, and a hydrogen storage. The system is designed to primarily produce a predetermined amount of hydrogen to be used as vehicle fuel. Additionally, the system can be used for electrical energy storage through hydrogen storage if it proves to be economically advantageous. The objectives are to optimize the price at which hydrogen needs to be sold for the facility to break even, sizing the electrolyzer, hydrogen storage, and fuel cell based on optimal operation, and study the factors that affect the optimal operation of the facility.The method used to optimize the hydrogen facility is linear programming in the MATLAB program. The optimization aims to calculate the lowest possible net cost (or highest net income) for the system. All costs and revenues are described linearly, and then all variables that affect costs and revenues are defined. These variables, in turn, depend on conditions as well as linear equalities and inequalities that restrict the values, they can take to influence the result. The optimization is carried out over a period of 1 year with a time step of two hours. Historical electricity prices for 2021 SE3 were used in the study. The variation in electricity prices is difficult to measure, so a simplified electricity price was also created to study the impact of the variation more closely.The results show that the hydrogen should be sold for approximately 36.6 SEK/kg to break even when the price is optimized, and waste heat is not utilized. The utilization of waste heat can reduce the price by 1.6-2.5 SEK/kg depending on whether the waste heat is utilized for parts or the entirety of the year. The electrolyzer and hydrogen storage should be dimensioned based on a predefined hydrogen demand, according to the factors of 4.9 MW/(ton of hydrogen/day) and 1.4 ton/(ton of hydrogen/day), respectively. The heat output that can be utilized from the hydrogen facility can be dimensioned based on a predefined hydrogen demand, according to the factor of 0.9 MW/(ton of hydrogen/day). The results show trends indicating that the electricity price affects the size of the electrolyzer, hydrogen storage, andthe hours during which the electrolyzer is active. Dimensioning the facility as a function of the electricity price has proven to be a complex question, and further studies are needed in that area. One trend indicates that the utilization of waste heat has a smaller impact on the hydrogen price at higher electrolyzer efficiency and a greater impact at lower efficiency. Waste heat that replaces heat from a district heating boiler reduces emissions by approximately 38 kg CO2e/MWh, depending on the existing boilers/fuels of the district heating producer. For investors, the results provide guidelines for the price of hydrogen, estimated dimensioning of the facility, the practical non-profitability of fuel cells, and insights into the economic value of waste heat. For the district heating company, the results mean reduced emissions of carbon dioxide equivalents, an additional heat source, and possibly reduced costs For the Swedish energy system, the results imply that the high variation in electricity prices can be utilized to produce hydrogen, leading to a potential decrease in the price of green hydrogen compared to current levels. Additionally, the utilization of waste heat can contribute to a more efficient energy system.

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  • 15. Barker Jørgensen, Bo
    et al.
    Nørh Glud, Ronnie
    Holby, Ola
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Oxygen distribution and bioirrigation in Artic fjord sediments (Svalbard, Barents Sea)2005In: Mar. Ecol. Prog. Ser. 292:85-95Article in journal (Refereed)
  • 16.
    Beiron, Jens
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Drifteffektivisering av installationssystem i fastigheter: Förstudie1997Report (Other academic)
    Abstract [sv]

    It is possible to improve the energy efficiency of HVAC (Heating, Ventilation and Air Conditioning) systems with the help of building energy management systems. Through deeper knowledge of the dynamics of the system the staff is able to choose a more effective management strategy. Statistics from the energy management system will inform about the system behaviour. It is possible to collect and present the statistics needed thanks to the fast development of information technology and the introduction of computer based building management system.

    A research project will investigate methods for creation of individual models of HVAC systems based on measurement data. Each system will then be simulated for different operating conditions. As a result of the simulation an optimal management strategy can be chosen. Different performance ratios will be used to evaluate the level of energy efficiency. The performance ratios should be defined so that they can be calculated from measurement data.

    This pilot study presents the background, purpose and method of the project. Some examples will be given to illustrate ineffective use due to a badly chosen management strategy.



    Sammanfattning



    Installationssystem kan drifteffektiviseras genom utnyttjande av driftstatistik. Genom att lära känna sin anläggning kan driftteknikern lättare fatta beslut om optimalaste driftstrategi. Med en förbättrad driftstatistik får teknikern många viktiga upplysningar om anläggningens dynamik och beteende. Som konsekvens av den snabba utvecklingen inom informationsteknologin samt införandet av datorstödda styr- och övervakningssystem finns möjligheter till omfattande datainsamling.

    Ett forskningsprojektet skall undersöka metoder att utifrån insamlad driftstatistik skapa individuella modeller av installationssystem. Modellen skall för varje enskild anläggning senare kunna utnyttjas för att simulera olika driftfall och därmed kunna optimera valet av driftstrategi. Olika nyckeltal kommer att användas för att utvärdera och följa upp effektiviseringsarbetet. Nyckeltalen skall definieras så att de kan beräknas utifrån insamlad driftstatistik.

    Denna förstudie beskriver bakgrund, syfte och metodval för projektet. Ett par exempel från utförda mätningar visar på typiska fall av energiineffektivitet som konsekvens av felaktigt vald driftstrategi.

  • 17.
    Bengtsson, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Kartläggning av energiförluster: gällande klimatskal och ventilation för Stora Enso Timbers Pelletsfabrik i Grums2013Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
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    Framsida/Sammanfattning
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    Examensjobb
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    Bilaga
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    Arkivfil
  • 18. Bengtsson, J.
    et al.
    Wikström, Fredrik
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Effects of whole-tree harvesting on the amount of soil carbon: model results1993In: New Zealand Journal of Forest Science 23: 380-389, 1993Article in journal (Refereed)
  • 19.
    Bengtsson, Peder
    et al.
    ASKO Appliances AB, Sockerbruksgatan 3, SE-53140 Lidkoping, Sweden.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Study of using a capillary tube in a heat pump dishwasher with transient heating2016In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 67, p. 1-9Article in journal (Refereed)
    Abstract [en]

    For competitive purposes, manufacturers of household appliances need to produce appliances that use less electricity. One way of doing this for a dishwasher is to add a heat pump system. Previous studies using R134a as refrigerant have shown that the addition of a heat pump can reduce total electricity consumption by about 24%. This paper reports on the use of a capillary tube in a heat pump dishwasher during the transient heating period. Working with an available compressor, the mass of R600a and the length of a 0.9 mm capillary tube were varied in order to find the configuration with the lowest electricity consumption. Three methods of calculating the length of the capillary tube were used to determine five lengths for evaluation. The results show that using a single capillary tube throughout the transient heating period yields similar electricity consumption to a variable expansion device which occurred by switching the capillary tube between two or three different lengths during the heating period.

  • 20.
    Bengtsson, Peder
    et al.
    ASKO Appliances AB, Lidköping, Sweden.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Renström, Roger
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Performance Study of a Closed-Type Heat Pump Tumble Dryer Using A Simulation Model and an Experimental Set-Up2014In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 32, no 8, p. 891-901Article in journal (Refereed)
    Abstract [en]

    In the interests of competitiveness, manufactures of tumble dryers are seeking to reduce both their electricity use and the drying time. This study examines how the cylinder volume of the compressor and the total heat transfer of the condenser influence the drying time and electricity use in a heat pump tumble dryer. A transient simulation model was developed and compared to an experimental set-up with good similarity. The simulations show that increasing the cylinder volume of the compressor by 50% decreases the drying time by 14% without using more electricity.

  • 21.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Improved Fluidized Bed Drying Technology for Wood Fuels2004Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis, I discuss experiences from designing, building and evaluating two research plants, which use circulating, atmospheric pressure superheated steam as drying medium for drying sawdust in a fluidized bed.



    The increased use of pellets has created a demand for new drying equipment at the Swedish pellet plants. The underlying cause is that almost all of the available dried material, such as wood shavings, is already in use. The remaining biofuel materials, primarily wet sawdust need drying before entering the pellet process.



    The primary demands on the drying process were an uncomplicated design and efficient energy use. A key aim was to improve the drying technique used in the Swedish wood fuel system with specially interest on the control system.



    Sawdust has been tested in both a full scale and a laboratory scale dryers. The tests were done in a spouted bed. The product of the steam mass flow and the enthalpy difference limits the drying capacity. The tests showed that it is possible to use the temperature after the dryer as a control parameter for the outgoing moisture content in a spouted bed dryer. The results and conclusions can be very useful when designing a similar full scale drying system.

  • 22.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Increased Capacity in an Existing Spouted Dryer Using a Heating Tube2008Conference paper (Refereed)
  • 23.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The Effect of Using a Heating Tube in an Existing Spouted Bed Superheated Steam Dryer2011In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 29, no 2, p. 183-188Article in journal (Refereed)
  • 24.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The gas to Particle Heat Transfer and Hydrodynamics in Spouted Bed Drying of Sawdust2005In: Drying Tecnology, Vol. Vol.23(5)Article in journal (Refereed)
  • 25.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The Heat Transfer Coefficients Dependency on Spouted Bed Heights, Material Flow and Mean Residence Time2002Conference paper (Refereed)
  • 26.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Beiron, Jens
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Olin, Malin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Individuell Examination i en Projektbaserad Kurs2000Conference paper (Other (popular science, discussion, etc.))
  • 27.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Brunzell, L.
    Bengtsson, P.
    Performance Analysis of a Tumble Dryer2004Conference paper (Refereed)
  • 28.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Eriksson, Bengt
    Biobränsletorkning: - torkning av rörflen1996Report (Other academic)
  • 29.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nordgren, Daniel
    Innventia, Box 5604, SE-11486 Stockholm, Sweden.
    Tomani, Per
    Innventia, Box 5604, SE-11486 Stockholm, Sweden.
    The effects of kraft lignin additives on wood fuel pellet quality, energy use and shelf life2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 112, no 0, p. 64-69Article in journal (Refereed)
    Abstract [en]

    In 2011, the total consumption of pellets in Sweden amounted to 1.9 million tons, which represents an energy value of 9 TWh. The pellets are used in large-scale as well as in small-scale applications, and increased demands on pellet quality are likely to force pellet producers to improve on the pellet properties. One way of increasing pellet quality is by using additives. The purpose of this article, therefore, is to examine kraft lignin as an additive. Pelletswere produced in a small industrial pellet press located at KarlstadUniversity, Karlstad, Sweden, and 1–4% of kraft lignin was added to the pellets. The results indicate that the addition of an increased amount of kraft lignin to the pellets increases their mechanical durability and their lengths. The results also indicate that dry kraft lignin yields pellets with higher durability as compared to wet kraft lignin. The energy demand was unaffected by the increased use of kraft lignin. The general results presented in this paper are useful for producers of lignin, pellet producers and end-users of pellets, who are interested in developing their products and/or improving the production processes.

  • 30.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nilsson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Particle mixing and residence time when drying sawdust in a continuous spouted bed2008In: Chemical Engineering and Processing, ISSN 0255-2701, E-ISSN 1873-3204, Vol. 47, no 8, p. 1252-1257Article in journal (Refereed)
  • 31.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Analysis of Superheated Steam Drying of Sawdust in Spouted Bed From Design Perspective2010Conference paper (Refereed)
  • 32.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Basic design criteria and corresponding results performance of a pilot-scale fluidized superheated atmospheric condition steam dryer2002In: Biomass and Bioenergy, Vol. Vol.23(2), p. 103-112Article in journal (Refereed)
  • 33.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Controllability of Product Moisture Content when Non-Screened Sawdust is Dried in a Spouted Bed2004In: Drying Tecnology, Vol. Vol.22(3)Article in journal (Refereed)
  • 34.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Design Criteria, Key Parameters and Performance Results of a Fluidized Bed1999Licentiate thesis, monograph (Other academic)
  • 35.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Shi yong dao liu guan dui lian xu pen dong gan zao qi de ying xiang: (Effects of using draft tubes in a continued spouted bed)2013In: Drying Technology & Equipment, ISSN 1727-3080, Vol. 1727-3080, no 3, p. 9-18Article in journal (Refereed)
  • 36.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Technical presentation of a 200kW Superheated Steam Dryer1998Conference paper (Other (popular science, discussion, etc.))
  • 37.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Temperature Measurement as Indicators of the Quality of the Spouting Bed when Non-screened Sawdust is Dried2004Conference paper (Other (popular science, discussion, etc.))
  • 38.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The Use of Temperature after The Spouting Bed as a Control Parameter of Outgoing Moisture Content When Sawdust is Dried2002Conference paper (Refereed)
  • 39.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Usefulness and significance of energy and mass balances of a superheated steam dryer2001In: Drying Tecnology, Vol. Vol.19(6), p. 1083-1098Article in journal (Refereed)
  • 40.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kullendorff,, Anders
    Biobränslen: - utvärdering av fluidiserad ångtorkprojektet fluidtork1997Report (Other academic)
  • 41.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kullendorff, Anders
    Biobränsletorkning - en lägesrapport projektet Fluidtork1996Report (Other academic)
  • 42.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kullendorff,, Anders
    Biobränsletorkning: - en lägesrapport projektet fluidtork1996Report (Other academic)
  • 43.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Stawreberg, Lena
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Integrating tumble dryer in the heating systems in block of flats2009Conference paper (Other (popular science, discussion, etc.))
  • 44.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Stawreberg, Lena
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Utveckling av energieffektivare kondenstumlare för en- och flerfamiljshus2008Report (Other academic)
  • 45.
    Beri, George
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Prediktering och styrning av värmesystem i flerbostadshus: Utvärdering av egenutformad MPC-regulator2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In 2012, 30% of the total energy consumption was used by apartments and buildings. Heating of apartment buildings and commercial buildings represents 60% (79.5 TWh) of that energy consumption. There is thus great potential for reducing energy use in the residential sector. Part of the overall efficiency work is to review the control of heating systems. Today's control often involves simple on / off systems where an upper and lower limit controls when to start and stop a process. This form of control is therefore best suited to systems where the change of state occurs quickly. When it comes to homes with high mass however, it takes time before a change takes effect. In some cases, it can take up to 24h before a change is noticed for buildings with high thermal inertia. An alternative to the traditional temperature based control is the so-called MPC controller which stands for Model Predictive Control. MPC is a control method that can take into account the thermal inertia and the dynamics of buildings. MPC controller also controls the system proactive rather than retroactive, which is the technique most of current control methods use. One problem with the MPC controller thou is that it requires large computational resources and technical knowledge of the building where it will be implemented. The aim of the thesis was to design a simple MPC controller and evaluate its performance. This was done by constructing a bench test model that can evaluate the function of the MPC controller. In addition to constructing a simple MPC-controller, a study has been done on how the current control method can be more energy efficient without having to invest in new equipment. The goal was to reduce the variations in indoor temperature and improve operating economics of the building. The study was conducted at Karlstad Bostads Aktiebolag (KBAB) that owns and manages 7,300 apartments in Karlstad. The Bench test model calculated indoor temperature using the weather conditions as solar radiation, cloud cover, outside temperature and wind speed. The study presents a number of simple MPC controllers that can be used to minimize indoor temperature variations and improving operating economy. It is estimated, however, that the MPC controller that only takes into account the outside temperature in its prediction is the most appropriate. The MPC controller has the potential to reduce heating requirements by 3.12 MWh (-4%) and reduce indoor temperature variations with 96%. The mean annual temperature would be 21.1 ° C and the energy consumption 113 kWh/m2 for the building. The study also presents an alternative to current control method that does not require any additional resources or investments. It has the potential to reduce heating requirements by 8.3 MWh (10%) and reduce indoor temperature variations by 65%. The energy consumption would then be 106 kWh/m2.

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    Beri George, Prediktering och styrning av värmesystem i flerbostadshus
  • 46.
    Björnsson, Lovisa
    et al.
    Lund University.
    Pettersson, Malin
    Lund University.
    Börjesson, Pal
    Lund University .
    Ottosson, Peter
    Kraftringen Energi AB.
    Gustavsson, Christer
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Integrating bio-oil production from wood fuels to an existing heat and power plant - evaluation of energy and greenhouse gas performance in a Swedish case study2021In: Sustainable Energy Technologies and Assessments, ISSN 2213-1388, E-ISSN 2213-1396, Vol. 48, article id 101648Article in journal (Refereed)
    Abstract [en]

    Combined heat and power (CHP) production in combination with a district heating (DH) grid gives an energy efficient use of wood fuels. The heat demand in the DH grid will, however, decline in the coming decades, and operators are seeking additional heat sinks. In this case study, the integration of a pyrolysis unit into an existing CHP plant was investigated as a possible solution. The retrofitted pyrolysis unit makes use of excess heat and yields a liquid bio-oil. Pyrolysis integrated with CHP production was shown to give a net energy yield of at least 80%, and to decrease the net heat output to the DH grid. The carbon footprint of the delivered heat was very low at maximum 1.6 g CO(2)eq/MJ. Prolonging the operation of the pyrolysis unit to periods without heat delivery to the DH grid would increase the use of existing installations, but at the cost of energy yields decreasing to 63-70%. Up to 2.8 PJ(LHV)/yr crude bio-oil could be produced at the investigated CHP plant. The bio-oil was shown to have a low carbon footprint, 1.7-4.0 g CO(2)eq/MJ(LHV), which makes it attractive for the rapidly expanding transport biofuel market.

    Download full text (pdf)
    fulltext
  • 47.
    Bock, Patricia
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Energianalys vid sprängmedelsfabriken Orica Sweden AB: Möjligheter att minska energibehovet i byggnad 2100 och 2100A2012Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Reducing the energy of a building is a way to reach the parliament aims to reduce energy use by 20% by 2020. This will also result in reduced emissions of greenhouse gases which is part of sustainable development. Orica Sweden AB in Gyttorp manufactures explosives and igniters to the civilian market. A survey on the energy usage performed by Sweco concludes that energy savings can be made, especially in the buildings located on the eastern parts of Oricas industrial area. This is where the buildings 2100, with the extension 2100A are situated.

    This study focuses on opportunities to reduce energy demand in buildings 2100 and 2100A at Orica Sweden AB in Gyttorp. The energy demand today is analyzed, and several proposed measures to reduce energy use are evaluated. The following measures are investigated:

    • A reduction in the supply air temperature in ventilation
    • Adapting runtime for ventilation
    • Connection of existing equipment for heat recovery
    • Investment of new air handling units with higher heat recovery efficiency of the recycling system and evaporative cooling where possible
    • A technical solution for heat recovery from the condenser of a chiller
    • A technical solution for heat recovery from two air compressors

    Detailed measurements and calculations underlying the suggestions result. Measurements of air flow in ducts were performed by hot wire thermometer. The volume flow of the condenser where measured by flowmeters and measurement of current was logged by an ampermeter. The total energy demand for heating, humidification, cooling and dehumidification of ventilation air for all handling units is calculated 2118 MWh / year. The measures introduced can reduce the energy demand to 1057 MWh /year, which represents 50% of the estimated energy needs today.

     

     

     

     

     

  • 48.
    Bogren, Linnéa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Torkning av gjutsand i en fluidiseradbädd.: Energioptimering, flödeshastighet, gastemperatur och klimateffekter.2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A study has been made to investigate the possibilities of drying casting sand in a fluidized bed. Sand is a finite material and in the casting process tons of casting sand are used annually. Volvo Powertrain Production has a foundry in Skövde where they are investigating if it is possible to reuse their casting sand. To be able to reuse the casting sand, it must first be washed clean of contaminants and then dried before it can be used in the process again. Foundry has large amounts of residual heat that could be used for the drying of foundry sand.

    The study is carried out to increase knowledge about drying casting sand in a fluidized bed at different gas temperatures and flows.

    The goal is to analyze the fluidizing properties of the casting sand and to calculatewhich temperature and which air flow generate the lowest energy requirement duringdrying. The casting sand must be dried from a moisture content of 12 % to a moisture content of 0,1 %. The wear of the casting sand is measured to ensure that the average grain size does not exceed 150 µm and that fines below 63 µm do not exceed 1 % of the total mass. The goal is also to design a dryer that can dry 10 000 tonnes of casting sand/year and to calculate the environmental improvement generated by recycling the casting sand in CO2-eq.

    The results of the study show that dry casting sand fluidizes at a speed of 0,09 m/s. The study also shows that the fluidization of casting sand does not have a significant wear on the size of the grains. The degree of wear of the sand is important because the sand must be reused many times and the result indicates that fluidization is a gentle process.

    Drying of 10 000 tonnes of casting sand/year requires a dryer of 22,2 m3. The size of the dryer is considered reasonable and to obtain a continuous drying, a fluidized belt dryer can be used.

    The results show that to dry as energy-efficiently as possible, the input volume flow on the air should be 0,028 m3/s. The incoming air temperature should be 100 °C when the casting sand bed is solid and 45 °C when the casting sand is fluidized. The foundry generates large amounts of residual heat and process streams up to 100 ° C can be seen as unlimited. This means that residual heat can be used to dry the casting sand.

    The results of the environmental calculations show that 226 to 244 tonnes of CO2-eq can be reduced by recycling 10 000 tonnes of casting sand per year.

    The drying effect is very low and it can be a problem if the residual heat decreases. To utilize a larger part of the supplied energy, a recirculating flow can be used. In today's process, however, it is not seen as necessary because the energy is unlimited and is not used for other purposes.

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  • 49.
    Bou-Rached, Patrik
    Karlstad University.
    Energieffektivisering av membranluftrengöring vid högflödesperioder: Studie på en storskalig MBR-pilot på Syvab Himmerfjärdsverket i samarbete med SUEZ Water Technologies and Solutions2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Membrane BioReactor (MBR) is a wastewater treatment method which combine both biological and physical cleaning. In the membrane tank there is membrane fibres which physically separate wastewater from containing organic material. This causes the membrane fibres to easily build fouling. A measure that can describe membrane fouling, is the pressure across the fiber membranes (transmembrane pressure). The higher the pressure, the dirtier the fiber membranes. Therefore the fiber membranes need to be cleaned frequently. A current applying cleaning method, membrane air scouring, works by releasing air bubbles from the bottom of the tank to remove organic fouling from the membrane fibres. Membrane air scouring accounts for a big part of the total energy consumption. Therefore research is needed to find development opportunities to counteract membrane fouling and to make membrane air scouring more energy efficient. In this master thesis, two different air scouring strategies are used in the membrane tank to reduce the development of the membrane fouling. The first aeration strategy, with lower air supply, was operated at a constant air supply of 5.04 m3air/m3permeate. The second aeration strategy, with higher air supply, varied instead the air supply linearly with increased incoming flow. The different aeration strategies were then compared with each other, and it was looked at which aeration strategy is the most energy efficient regarding energy consumption per permeate volume produced, to reduce membrane fouling.For three weeks, each aeration strategy was applied in the pilot plant at Himmerfjärdsverket. During the strategies, maintenance cleaning was done with oxalic acid, as the commonly used chemical sodium hypochlorite was not available. The transmembrane pressure in the membrane tank was analysed during the aeration strategies to investigate how the membrane fouling developed. The sludge properties of the water in the pilot plant were also analysed, to see if these had any influence on the membrane fouling. Energy calculations were also done to for quantify the energy consumption from the membrane air scouring.The thing that had the biggest impact on energy consumption was the size of the incoming flow. Then irreversible fouling of inorganic substances that clog the membrane pores. Finally, reversible fouling of organic material that forms cakelayers on the fibres. The investigation showed that the aeration strategy with the lowest air supply was enough to successfully suppress the membrane fouling and maintain a high permeability. In pilot-scale, consumed the air strategy with lower air supply 74 Wh/m3, while the higher air supply aeration strategy consumed 92 Wh/m3for the pilot-scale membrane air cleaning. At full scale, the aeration strategy with lower air supply is expected to consume 46 Wh/m3. In full scale, more frequent maintenance cleaning may need to be done, which means poorer filtration performance during washing periods. The recommendation is to test the aeration strategy with lower air supply and at the same time have more frequent maintenance cleaning, to investigate whether it is the most energy efficient option in the long term.

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    Energieffektivisering av membranluftrengöring vid högflödesperioder
  • 50.
    Brunzell, Lena
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Reducing the Energy Use for Textiles in a Closed Cycle Tumble Dryer2006Manuscript (preprint) (Other academic)
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