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  • 1.
    Aasberg, Pål
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energilager i en överdimensioneradvindkraftspark: En linjäroptimering av batterilager i kombination medintermittenta förnybara energikällor2022Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A linear optimization has been made to examine the economic viabilityof incorporating battery storage in a wind farm in Sweden. The studyexamines a future wind farm with 10 10 MW turbines. An orographicmapping with height differences and vegetation has been used incombination with measured wind data with IEC-rated anemometersand wind direction sensors between 1997 and 2017 to create asimulated production in the windPRO software. This effect, togetherwith hourly prices from 2021 from Nord pool in SE1, SE2, SE3, SE4and in Estonia, has been used in a linear optimization in Matlab to findthe battery capacity that generates the most revenue. 3 Scenarios areinvestigated where scenario 1 is a wind farm without battery storagewhere all electricity produced is sold directly at the current price.Scenario 2 also lacks battery storage and has a power limit of 75 MWat the transformer whilst the farm still produces 100 MW. Scenario 3has a power limit of 75 MW at the transformer and the possibility ofbattery storage.

  • 2.
    Abrahamsson, Erika
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Gröna tak - potentialen för dagvattenreglering i Karlstad: Simuleringar i Mike Urban2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As urban areas become more populated and denser, stormwater management becomes an important matter. Since natural areas are becoming exploited and green areas in cities are removed the stormwater flow increases due to the conversion of impermeable surfaces into hard surface areas. The increase in stormwater flow can cause flooding if the pipeline system is insufficient.

    Change in climate caused by anthropogenic emissions will expose our communities to difficult challenges. Urban flooding from sewers is one of them, and may become more frequent in parts of the world where precipitation is predicted to increase in the future. In order to develop our cities in a sustainable manner and create resilience, the urban drainage system has to be a part of this development. Many of the techniques related to sustainable urban drainage systems, like storage reservoirs and open channels, require access to land space. However, about 40-50 % of the impermeable surfaces in cities consist of roof. Consequently, an interesting alternative to decrease stormwater flow is green roof due to its ability to reduce and attenuate the flow.

    The aim of this thesis is to demonstrate the benefits of green roof’s stormwater management through simulations in Mike Urban. The simulations are made over two neighborhoods in Karlstad with future climate changes. The simulations indicated that green roof in these neighborhoods show good potential to lower the risk of flooding and the numbers of flooded wells by a 10- and 2-year rain is decreased by 42 and 58 %.

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  • 3.
    Abrahamsson, Linnéa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energieffektivisering av fabrik inom tillverkande industri: Utvärdering av åtgärdsförslag2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    June 1st, 2014, the law on energy audits of large enterprises was introduces as a way of promoting energy efficiency and to help fulfil the demands from the EU energy efficiency directive. One company that this law applies to is Talent Plastics in Gothenburg. In 2017 an energy audit was conducted at the company by WSP in Karlstad. This audit has been used as a basis for this study. The purpose of this study has been to present solutions for reducing the energy use as Talent Plastics in Gothenburg.

    In this study, an energy balance for the facility has been modelled. This model has then been used in order to evaluate some of the different solutions presented in the previous energy audit as well as some new solutions that have been identified.

    The solutions that have been studied are:

    Heat recovery from the process cooling by installing a heating battery in

    ventilation systemsHeat recovery from the process cooling by pre-heating ventilation airUpdating old extruder machinesHeat recovery from the compressed air systemUsing outside air for the compressed air systemUpdate of the existing heat recovery system installed in the production

    ventilation system

    Based on the results presented in this report the system today is inefficient with a large need for heat whilst a lot of energy is cooled through process cooling. The energy balance presented showed a higher use of energy for heating of ventilation air compared to the results presented in the previous energy audit. This is a consequence of the assumptions made when conducting an energy audit. By underestimating the energy need for the heating of ventilation air, the potential energy savings from solutions including heat recovery in the ventilation systems has been underestimated.

    Out of the solutions investigated in this study, updating the heat recovery system in the ventilation system for production spaces resulted in the largest energy savings with savings of 192 MWh per year. The maximum energy savings using heat recovery from the process cooling were 202 MWh/year. This solution had a pay-off time of 0,7 years. The results showed that heat recovery from the compressed air system is not a suitable solution for the facility.

    When combining different solutions updating the existing heat recovery system installed in the production ventilation system combined with pre-heating and installation of a heating battery in the same ventilation system would result in energy savings of 323 MWh per year. This represents 14 % of the total energy use for the facility and savings of 226 thousand Swedish krona per year.

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    Energieffektivisering av fabrik inom tillverkande industri
  • 4.
    Almusaed, Amjad
    et al.
    Jonköping University, Sweden.
    Almssad, Asaad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Alasadi, Asaad
    University of Basra, Iraq.
    Yitmen, Ibrahim
    Jonköping University, Sweden.
    Al-Samaraee, Sammera
    Basrah University for Oil & Gas, Iraq.
    Assessing the Role and Efficiency of Thermal Insulation by the "BIO-GREEN PANEL" in Enhancing Sustainability in a Built Environment2023In: Sustainability, E-ISSN 2071-1050, Vol. 15, no 13, article id 10418Article in journal (Refereed)
    Abstract [en]

    The pressing concern of climate change and the imperative to mitigate CO2 emissions have significantly influenced the selection of outdoor plant species. Consequently, evaluating CO2's environmental effects on plants has become integral to the decision-making process. Notably, reducing greenhouse gas (GHG) emissions from buildings is significant in tackling the consequences of climate change and addressing energy deficiencies. This article presents a novel approach by introducing plant panels as an integral component in future building designs, epitomizing the next generation of sustainable structures and offering a new and sustainable building solution. The integration of environmentally friendly building materials enhances buildings' indoor environments. Consequently, it becomes crucial to analyze manufacturing processes in order to reduce energy consumption, minimize waste generation, and incorporate green technologies. In this context, experimentation was conducted on six distinct plant species, revealing that the energy-saving potential of different plant types on buildings varies significantly. This finding contributes to the economy's improvement and fosters enhanced health-related and environmental responsibility. The proposed plant panels harmonize various building components and embody a strategic approach to promote health and well-being through bio-innovation. Furthermore, this innovative solution seeks to provide a sustainable alternative by addressing the challenges of unsustainable practices, outdated standards, limited implementation of new technologies, and excessive administrative barriers in the construction industry. The obtained outcomes will provide stakeholders within the building sector with pertinent data concerning performance and durability. Furthermore, these results will enable producers to acquire essential information, facilitating product improvement.

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  • 5.
    Al-Qadri, Ali A.
    et al.
    King Fahd University of Petroleum and Minerals, Saudi Arabia.
    Ahmed, Usama
    King Fahd University of Petroleum and Minerals, Saudi Arabia.
    Ahmad, Nabeel
    King Fahd University of Petroleum and Minerals, Saudi Arabia.
    Abdul Jameel, Abdul Gani
    King Fahd University of Petroleum and Minerals, Saudi Arabia.
    Zahid, Umer
    King Fahd University of Petroleum and Minerals, Saudi Arabia.
    Naqvi, Salman Raza
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A review of hydrogen generation through gasification and pyrolysis of waste plastic and tires: Opportunities and challenges2024In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 77, p. 1185-1204Article, review/survey (Refereed)
    Abstract [en]

    The global annual production of plastics and tires exceeds 6.5 billion tons, with only 10% being recycled, leading to significant environmental problems. Thermochemical gasification of these waste materials offers a potential avenue for producing renewable hydrogen while harnessing underutilized carbon-based waste streams. This review highlights the research on thermochemical conversion of plastics and tires, providing key inferences regarding yield optimization, technical hurdles, and techno-economic viability. It indicates that strategic catalyst design and optimized integrated system configurations can significantly improve the hydrogen yields from plastic and tire pyrolysis/gasification. The key results of this work are that catalyzed gasification reactions show the most potential for maximizing hydrogen yield from plastic and tire waste. The related studies demonstrated that catalysts like Ni, Fe and Ce-doped mixtures can significantly increase hydrogen yield from plastic waste pyrolysis and gasification by suppressing coke formation and promoting reforming/shift reactions. Optimization of temperature, steam ratio and residence time also improves yield. Feedstock synergies exhibiting multiple reaction pathways likewise maximize yield. Computational modeling plays a valuable role by providing mechanistic insights through equilibrium and kinetic simulations. Integrated gasification with carbon/methane reforming shows potential to improve efficiency and lower costs. Techno-economic analyses indicate plastic/tire gasification may achieve cost parity with steam methane reforming through optimized integrated designs incorporating heat recovery. Integrated processes combining multiple conversion steps could further boost efficiency but require additional modeling and testing. A deeper understanding of reaction mechanisms, achieved through advanced modeling approaches, coupled with comprehensive lifecycle analyses of integrated solutions, can pinpoint optimized processing conditions and system designs capable of matching or surpassing the economic and environmental performance of conventional fossil fuel-based hydrogen production. The recommendations provided aim to guide future research prioritization, facilitating the realization of the large-scale potential inherent in waste-derived renewable hydrogen pathways. 

  • 6.
    Andersson, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Numerisk modellering av tvåfasströmning och syretransport i bubbelkolumner: Metodutveckling för att förutsäga syretransportshastigheten i rent vatten och surfaktantlösningar2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In connection with a global population increase and economic development, the consumption of freshwater and the production of wastewater is increasing. Wastewater needs to be treated to convert it into an effluent that can be safely released without negative environmental impacts. One of the most common wastewater treatment technologies is aerobic biological treatment, where bottom aeration – the procedure of pumping air through submerged diffusers which generate bubbles to oxygenate the wastewater – is the most energy demanding process. The oxygen transfer rate from air bubbles to wastewater is negatively affected by the presence of surfactants, a ubiquitous contaminant in both municipal and industrial wastewaters.

    To assure a sufficient treatment efficiency as energy efficiently as possible, an understanding of the oxygen transfer process in bottom aeration systems is necessary, and for designing of new systems and calibration of existing ones, tools facilitating prediction of the oxygen transfer rate are required. The purpose of this study was to develop a numerical tool to estimate the oxygen transfer rate for lab-scale bottom aeration systems and to contribute to the basis of knowledge regarding oxygenation of surfactant solutions. The primary goal of the study was to develop a CFD-model coupled with a mass transfer model to predict the oxygen transfer rate in bubble columns containing clean water, and the secondary goal was to apply the model to water-based solutions of the surfactant lauric acid (DDA) and identify options for further development of the model to make it applicable for surfactant solution systems.

    The model was developed with COMSOL Multiphysics 5.5 and included a two-dimensional axisymmetric geometry, URANS-equations and standard k-ε to for turbulence modelling, and an Euler-Euler mixture model for the two-phase flow. For oxygen transfer modelling the two-film theory, Higbies penetration theory and the advection-diffusion equation were used. Bubble diameter is an important parameter in several of the equations used and the Sauter Mean Diameter was calculated to represent the average bubble diameter, based on available experimental data for different combinations of air flow rate and DDA-concentration.

    Results of the simulations regarding the oxygen transfer rate in clean water fit well with experimental data at lower air flow rates, and the difference for the volumetric mass transfer coefficient was 0,7 % and 3,3 % for the air flow rates 0,1 l/min and 0,2 l/min, respectively. For the air flow rate 0,3 l/min the difference was 14 %; because of the flow regime being more heterogenous at higher air flow rates, the model tends to overestimate the oxygen transfer rate. In surfactant solutions the model overestimated the oxygen transfer rate due to surfactant adsorption on the bubble-water interface – and the consequent decrease of the mass transfer coefficient – not being modelled. Either a correction factor for the mass transfer coefficient – based on the difference between simulated results and experimental data – needs to be calculated and applied, or the underlying theories describing the oxygen transfer require revision. Potentially the mass transfer and interfacial adsorption of surfactants could be modelled to emulate reality more accurately.

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  • 7.
    Andersson, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Torkning integrerat med kraftvärmeverk: Påverkan av energibalanser i torksystem vid integrering till kraftvärmeverk2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    I Sveg finns ett pneumatiskt torksystem. Systemet har sedan 1989 torkat torv till briketter men har på senare tid torkat både trä och torv för produktion av bränsle i form av pellets och briketter. Idag består anläggningen av två symmetriska torklinjer. I torklinjerna används en värmepumpkrets för återvinning av råvaruånga. I värmepumpkretsen används en kompressor driven av inköpt elenergi. Planerna är att integrera en av linjernas nuvarande torkprocess till ett kraftvärmeverk genom installation av ångpanna med bränslet torv och således producera el istället för att köpa el. Integrationen till kraftvärmeverket ger torklinjens värmepumpkrets ett nytt utseende. Kompressorn tas bort i utvald torklinje och ersätts av två lågtrycksturbiner. Det nya utseendet av värmepumpkretsen kommer innebära ett samspel mellan torkning och kraftvärmeverk. I värmepumpkretsen används olika ångflöden beroende av vilket råvarumaterial som torkas. Därför beräknades och användes olika ångflöden beroende av olika fukthalter och inmatningar i torksystemet för att se hur el- och fjärrvärmeproduktionen i kraftvärmeverket påverkades. Samtidigt jämfördes nuvarande torksystem med torksystem integrerat med kraftvärmeverk ur ett energiperspektiv genom förändring av el, fjärrvärmeproduktion och biobränsle.

    Fjärrvärmeproduktionen i kraftvärmeverket ökade vid ångflödena 31,0 ton/h och 24,0 ton/h ”till kompressor” men på grund av större beräkningsosäkerhet bortsågs dessa. Detta gav en varierad sammanlagd fjärrvärmeproduktion av systemen mellan 23,0-23,8 MW respektive 22,0-22,5 MW vid torkning av torv respektive trä (bortseende av torvscenario 1 vid fukthalten 65 %). En fjärrvärmeproduktion i den storleken, jämfört med Svegs fjärrvärmebehov, kan sägas vara för stort. En stor problematik blir därför vad all spillvärme ska användas till, framförallt på sommaren.

    Vid integrering till kraftvärmeverk minskade ”bränsle” medan ”fjärrvärme” och ”el” ökade. Beroende av vilket råvarumaterial som torkades gav en integrering ett större resultat för ”el” men mindre ”fjärrvärme” och ”bränsle” vid torkning av trä. Därför rekommenderas torkning av trä eftersom större resultat av ”el” minskar inköpt elenergi samt mindre ”fjärrvärme” resulterar till mindre spillvärme.

    Vid beräkningarna användes Simulink, ett verktyg för grafisk lösning av differentialekvationer, som ingår i programvaran MATLAB från Mathworks. I Simulink formerades olika ekvationer i statiska beräkningsmodeller för beräkning av energibalanserna i nuvarande torksystem och torksystem integrerat med kraftvärmeverk. Energibalanserna i nuvarande torksystem undersökte svårplacerade effektförluster samt genom olika energibalanskontroller kontrollerade och bedömde trovärdigheten i beräkningsmodellen. Resultaten för energibalanskontrollerna kallades ”beräkningsosäkerhet” vilket var en av flera parametrar som framlade bevis för ett variabelberoende, känsligt, komplext och svårtydande torksystem där övriga effektförluster var svåra att placera. Ett mer korrekt resultat av nuvarande system kan därför möjligtvis uppnås vid användande av en dynamisk istället för statisk modell samt användande enbart av mätdata istället för dimensionerande värden och således göra effektförlusterna lättare att placera.

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  • 8.
    Andersson, Tim
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Computer Modeling of Thermodynamic Flows in Reactors for Activated Carbon Production2014Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    There's a big demand for activated carbon in Ghana, it's used for the country's mining industry as well as in a multitude of other applications. Currently all activated carbon is imported despite the fact that the country has a large supply of agricultural waste that could be used for its production. This study focuses on activated carbon production from oil palm kernel shells from the nations palm oil industry.

    Earlier research points to a set of specific conditions needed for the production. The pyrolysis process produces biochar from the biomass and the process is set to take place for 2 h at 600  °C after a initial heating of 10 °C/min. The activation process then produces the activated carbon from the biochar and is set to take place for 2 h at 850 °C with a heating rate of 11.6 °C/min.

    Two reactors are designed to meet the desired conditions. The reactors are both set up to use secondary gases from diesel burners to heat the biomass. The heating is accomplished by leading the hot gases in an enclosure around a rotating steel drum that holds the biomass. To improve the ability to control the temperature profile in the biomass two outlet pipes are set up on top of the reactor, one above the biomass inlet and one above the biomass outlet. By controlling how much gas that flows to each outlet both the heating rate and the stability of the temperature profile can be controlled. The secondary gas inlet is set up facing downwards at the transition between the heating zone (area of initial heating) and the maintaining zone (area of constant temperature).

    The two reactors are modeled the physics simulation software COMSOL Multiphysics. Reference operating parameters are established and these parameters, as well as parts of the design, are then changed to evaluate how the temperature profile in the biomass and biochar can be controlled. A goal area was set up for the profile in the biomass where it was required to maintain a temperature of between 571.5 and 628.5 °C after the initial heating to be seen as acceptable. Similarly a goal area was set for the biochar between 809 °C and 891 °C after the initial heating.

    It's found from the simulations that the initial design of the reactors work well and can be used to produce the desired temperature profiles in the biomass and biochar. Furthermore it's concluded that the initial design for the pyrolysis reactor can be improved by having the gas outlet pipe situated by the biomass inlet face downwards instead of upwards. The redesign improves the overall efficiency of the reactor by increasing the heating rate and maintained temperature.

    The evaluation of the operating parameters led to the conclusion that the secondary gas inlet temperature effects the temperature profile to a greater extent than the gas mass flow in both reactors thereby making them more energy efficient. The increase in efficiency comes with a drawback of more unstable temperature profile. If the temperature profile becomes too unstable it will include temperatures that are too high or too low to be seen as acceptable.

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  • 9.
    Andrésen, Albin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Att förutsäga temperatur, utgående fukthalt och tryckfall i en pneumatisk transporttork2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Användningen av pellets har ökat kraftigt de senaste åren och har blivit ett viktigt verktyg för att minska miljöpåverkan. I energibranschen är viktigt utreda möjligheten att effektivisera tillverkningsprocessen för att ligga i framkant av utvecklingen och göra bränslet till ett attraktivt val för konsumenterna. En stor del av pelletstillverkarnas utgifter går till att torka det råmaterial som pellets består av. Torkning och transport av material är två energikrävande processer som är nödvändiga i många industrier och kan ibland innebära stora utgifter såväl kostnadsmässigt som miljömässigt. Pneumatisk transporttorkning är ett sätt att kombinera torkning och transport av material och tekniken kan vara lämplig att använda vid pelletstillverkning. På Karlstads Universitet finns en pneumatisk transporttork vars syfte är att forska och utveckla torkning av råmaterial.I den här studien byggdes en modell för att hjälpa användaren att förutse vilket tryckfall och utgående fukthalt som kan förväntas vid torkning av sågspån. Modellen kan användas som ett hjälpmedel vid planering av försök i Karlstads Universitets pneumatiska transporttork.Modellen byggdes i beräkningsverktyget Excel. Dess resultat jämfördes med testserier genomförda i Karlstads Universitets pneumatiska transporttork. Totalt genomfördes trettiotre olika testserier då tryckfall och utgående fukthalt jämfördes. Testserierna skiljde sig ifrån varandra i fråga om massflödet luft, material och ingående lufttemperatur.Vid lägre lufttemperaturer förutsåg modellen en högre utgående fukthalt än vad som kunde uppmätas. När den ingående lufttemperaturen var 120 °C förutsågs ibland rätt, ibland högre och ibland lägre fukthalt i jämförelse med testserierna. Tryckfallet kunde med god noggrannhet förutsägas då lufthastigheten var låg. Då hastigheten var högre var differensen mellan mätdata och modellen större.Känslighetsanalysen visade att en möjlig förklaring till att modellen i vissa fall förutsåg en hög fukthalt kan vara att vissa materialegenskaper var felaktigt antagna. Störst påverkan hade antagandena angående partiklarnas densitet och antalet partiklar som flödar genom systemet per sekund. Det simulerade tryckfallet påverkades inte av ovan nämnda antaganden.Modellen har stor utvecklingspotential men vidare studier rekommenderas för att skapa en bättre förståelse för såväl den pneumatiska transporttorken som modellen. Studierna bör främst riktas mot att bestämma partikelegenskaper och att kontrollera hur väl tryckfallet överensstämmer men mätdata i hela torken. Om det genomförs finns goda möjligheter att modellen kan bli användbar för användare av Karlstads Universitets pneumatiska tork.

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    Andrésen Albin, pneumatisk torkning, tryckfall, fukthalt
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    Arkivfil
  • 10.
    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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  • 11.
    Anukam, Anthony Ike
    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).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Bosede Famewo, Elisabeth
    University of Fort Harare, South Africa.
    Nyamukamba, Pardon
    Cape Peninsula University, South Africa.
    Characterization of pure and blended pellets made from Norway spruce and pea starch: A comparative study of bonding mechanism relevant to quality2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 23, p. 1-22, article id 4415Article in journal (Refereed)
    Abstract [en]

    The mechanism of bonding in biomass pellets is such a complex event to comprehend, as the nature of the bonds formed between combining particles and their relevance to pellet quality are not completely understood. In this study, pure and blended biomass pellets made from Norway spruce and pea starch were characterized using advanced analytical instruments able to provide information beyond what is visible to the human eye, with intent to investigate differences in bonding mechanism relevant to quality. The results, which were comprehensively interpreted from a structural chemistry perspective, indicated that, at a molecular level, the major disparity in bonding mechanism between particles of the pellets and the quality of the pellets, defined in terms of strength and burning efficiency, were determined by variation in the concentration of polar functional groups emanating from the major organic and elemental components of the pellets, as well as the strength of the bonds between atoms of these groups. Microscopic-level analysis, which did not provide any clear morphological features that could be linked to incongruity in quality, showed fracture surfaces of the pellets and patterns of surface roughness, as well as the mode of interconnectivity of particles, which were evidence of the production of pellets with dissimilarities in particle bonding mechanism and visual appearance.

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  • 12.
    Anund Vogel, Jonas
    et al.
    KTH.
    Lind, Hans
    KTH.
    Holm, Cyril
    Oxford Univeristy, GBR.
    Incentivising innovation in the construction sector: the role of consulting contracts2019In: Australasian Journal of Construction Economics and Building, ISSN 1835-6354, E-ISSN 1837-9133, Vol. 19, no 2, p. 181-196Article in journal (Refereed)
    Abstract [en]

    The issue of whether contracts promote innovation and sustainability is an important but overlooked aspect for achieving energy and environmental targets, as well as for creating smart and sustainable cities. In this article, based on the principle/agent problem and Holmstrom and Milgrom's work on optimal contracts it is argued that the current general conditions of architectural and engineering consulting agreements in Sweden (ABK 09)-a standard type of contract often used in developer/consultant relations-may not incentivize choices that support the long-term goals of society. Furthermore, although this exploratory study specifically analyses a Swedish standard contract, the question of how contractual incentive structures can optimize real-world performance is a general one, and thus the article's findings have general applicability. This exploratory study also points to further research into how contractual structures impact climate-neutral buildings. In this way, Swedish consultants who use ABK 09 are incentivized to include low-risk, well-proven, and widely used technologies in order to minimize risks for themselves. This study contributes to resolving this dilemma by suggesting how ABK 09 could be restructured to change the balance between incentives and risk and incentivize innovation and sustainability. As mentioned above, the current study operates at a theoretical level. It discusses six possible changes that would better align the contract with the societal goals of innovation and sustainability.

  • 13.
    Arnberg, Johanna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013), Science, Mathematics and Engineering Education Research.
    Torrsubstansförluster vid lagring och hantering av träspån vid Härjeåns Energi AB2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Härjeåns Energi AB in Sveg is a company consisting a brand-new cogeneration plant and a biofuel plant where the company produces pellets out of wooden sawdust. Before pelleting, the sawdust is stored in a large stack. However, the company had noted that the amount of sawdust delivered to the stack minus the sawdust taken from the stack for pelleting did not add up to the sawdust left in the stack. At some point during storage and handling of the sawdust large quantities has disappeared. The purpose of this study was to investigate how and when the dry matter losses occur and the magnitude of the losses regarding two things: the dry matter losses associated with storing of the sawdust and the dry matter losses related to the handling of the sawdust. The most important goal of this study, for the company, was to create an equation that describes the amount of dry matter losses that reasonably should have disappeared from the stack depending on for how long the sawdust has been stored. Simply to be able to make a write-off of the sawdust inventory balances on a regular basis. The purpose and goals were answered by conducting a literature study on the subject, studying the company’s sawdust accounts and their way of handling the sawdust, and also by constructing two simulation models of the dry matter losses in the stack of sawdust.

    Dry matter losses resulting from the storage of biomass may occur through the decomposition mechanisms; respiration, biodegradation and thermal and chemical degradation. But the storage effect on fuel quality is complex. Time of storage, climatic conditions and the geometry and structure of the stacks are some factors that affect the change in biomass properties.

    This degradation, along with how the company manages the sawdust, contributes to dry matter losses. However, the largest contributing factor to the dry matter losses is the storage part. Some contributing factors are the size of the stack, if it’s been compacted and if the sawdust is stored open without coverage. When the models were built it turned out that the result was well in line with what actually had disappeared in the stack, according to the sawdust inventory, during the investigated years 2013-2017.

    For example, by reducing the maximum height of the stack to a maximum of 5-7 meters and apply the last-in-first-out-method on the spruce, while the pine can be stored for a longer time, would certainly contribute to reduced dry matter losses and, consequently, economic losses.

    In the future, however, more resources should be invested in research about storing the fraction of sawdust, as well as storing wood in stacks larger than a maximum height of 5-7 meters. Today there are no research at all within these two categories, but if there were, it could facilitate many energy-producing companies.

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  • 14.
    Arslan, Muhammad
    et al.
    University of Engineering and Technology, Pakistan..
    Farooq, Muhammad
    University of Engineering and Technology, Pakistan..
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Sultan, Umair
    MNS University of Agriculture, Pakistan..
    Tahir, Zia-ur-Rehman
    University of Engineering and Technology, Pakistan..
    Nawaz, Saad
    University of Engineering and Technology, Pakistan..
    Waheed, Nazim
    University of Engineering and Technology, Pakistan..
    Naqvi, Salman Raza
    National University of Sciences and Technology, Pakistan.
    Ali, Qasim
    University of Sargodha, Pakistan..
    Tariq, M. Suleman
    University of Engineering and Technology, Pakistan..
    Chaudhry, Ijaz Ahmad
    University of Management and Technology, Pakistan..
    Anderson, John M.
    Heriot-Watt University, Scotland..
    Anukam, Anthony
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Impact of Varying Load Conditions and Cooling Energy Comparison of a Double-Inlet Pulse Tube Refrigerator2020In: Processes, ISSN 2227-9717, Vol. 8, no 3, article id 352Article in journal (Refereed)
    Abstract [en]

    Modeling and optimization of a double-inlet pulse tube refrigerator (DIPTR) is very difficult due to its geometry and nature. The objective of this paper was to optimize-DIPTR through experiments with the cold heat exchanger (CHX) along the comparison of cooling load with experimental data using different boundary conditions. To predict its performance, a detailed two-dimensional DIPTR model was developed. A double-drop pulse pipe cooler was used for solving continuity, dynamic and power calculations. External conditions for applicable boundaries include sinusoidal pressure from an end of the tube from a user-defined function and constant temperature or limitations of thermal flux within the outer walls of exchanger walls under colder conditions. The results of the system's cooling behavior were reported, along with the connection between the mass flow rates, heat distribution along pulse tube and cold-end pressure, the cooler load's wall temp profile and cooler loads with varied boundary conditions i.e. opening of 20% double-inlet and 40-60% orifice valves, respectively. Different loading conditions of 1 and 5W were applied on the CHX. At 150 K temperature of the cold-end heat exchanger, a maximum load of 3.7 W was achieved. The results also reveal a strong correlation between computational fluid dynamics modeling results and experimental results of the DIPTR.

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  • 15.
    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.

  • 16.
    Aurell, Greta
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Analys av bergvärme och frikyla för uppvärmning och komfortkyla i kombination med fjärrvärme: En ekonomisk och miljömässig hållbarhetsoptimering utifrån social komfort2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study is based on a simulation model covering the heating and cooling system of the property. The model is created in Simulink, a graphical program for modelling multidomain systems. Data is collected from an internal data base. The model is verified based on differences and similarities between calculations and given data. 

    The overall purpose of the study is to investigate how the heating and cooling system of the property is affected by the change in operation of ground source heating and cooling compared to district heating, from a sustainability perspective. The purpose is also to optimize the operation of the heating and cooling system based on environmental and economical parameters. The goal of the study is to calculate the efficiency of the heat pumps and decide the heating and cooling demand of 2021. The goal also includes to construct a simulation model, that corresponds to measured operating data of 2021, to investigate three operating cases based on an economical and an environmental perspective. The cases shall investigate how the heating and cooling system works in the present, how it will work without the ability of ground source cooling, and how the operation of the system can be optimized based on the condition that the heating and cooling demand is fulfilled. 

    In 2021 the total heating demand of 2 714 MWh was met by 45 % district heating and 55 % ground source heating. The cooling demand of 2021 was 237 MWh. The total cost to satisfy the property’s heating and cooling demand is 1 439 tkr/year, which correlates to 50,02 öre/kWh. The emissions of carbon dioxide are 55 ton/year, which correlates to 19,13 g CO2-ekv/kWh.

    The result from the study shows that it is possible to reduce costs and carbon dioxide emissions by operational energy optimization actions. By reducing the operation time of heat pump two, it is possible to save up to 2 % in costs. If heat pump two is in operation during the whole year, the carbon dioxide emissions from the heating and cooling production of the property, can be reduced by 45 %.

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    Analys av bergvärme och frikyla för uppvärmning och komfortkyla i kombination med fjärrvärme
  • 17.
    Bengtsson, Peder
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Apply heat pump systems in commercial household products to reduce environmental impact: How to halve the electricity consumption for a household dishwasher2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the household appliance industry, heat pump systems have been used for a long time in refrigerators and freezers to cool food, and the industry has driven the development of small, high-quality, low-price heat pump components. In the last few decades, heat pump systems have been introduced in other household appliances, with the express purpose of reducing electricity consumption. Heat pump tumble dryers have been on the market since 2000 and dominate the market today. A heat pump dishwasher was introduced on the market in 2014 and a heat pump washing machine in 2016. The purpose of adding a heat pump system in these three products was to decrease electricity consumption.

    Papers I and II used a methodology where transient simulation models were developed and used to increase knowledge about how to decrease electricity consumption for a tumble dryer and a dishwasher by adding a heat pump system. Papers II to V showed that a lower electricity consumption and lower global warming potential together with an energy-efficient drying method, where no humid air evacuates to the kitchen, give a heat pump dishwasher competitive advantages compared to any conventional dishwasher currently on the market. Using simulations, this dissertation concludes that a future commercial heat pump dishwasher, using R600a as a refrigerant, will reduce electricity consumption and total equivalent warming impact (TEWI) by 50% compared to the conventional dishwasher.

    The willingness from the customer chain to pay extra for this heat pump dishwasher is because of the decreases electricity consumption and the fact that no humid air evacuates to the kitchen. This willingness makes the heat pump dishwasher to a variant which have possibility to succeed on the future market.

    The challenge for the manufacturer is to develop and produce a high-quality heat pump dishwasher with low electricity consumption, predict future willingness to pay for it, and launch it on the market at the right moment with the right promotion in order to succeed.

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  • 18.
    Bengtsson, Peder
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Increasing the value of household appliances by adding a heat pump system2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Historically, domestic tasks such as preparing food and washing and drying clothes and dishes were done by hand. In a modern home many of these chores are taken care of by machines such as washing machines, dishwashers and tumble dryers. When the first such machines came on the market customers were happy that they worked at all! Today, the costs of electricity and customers’ environmental awareness are high, so features such as low electricity, water and detergent use strongly influence which household machine the customer will buy. One way to achieve lower electricity usage for the tumble dryer and the dishwasher is to add a heat pump system.

    The function of a heat pump system is to extract heat from a lower temperature source (heat source) and reject it to a higher temperature sink (heat sink) at a higher temperature level. Heat pump systems have been used for a long time in refrigerators and freezers, and that industry has driven the development of small, high quality, low price heat pump components. The low price of good quality heat pump components, along with an increased willingness to pay extra for lower electricity usage and environmental impact, make it possible to introduce heat pump systems in other household products.

    However, there is a high risk of failure with new features. A number of household manufacturers no longer exist because they introduced poorly implemented new features, which resulted in low quality and product performance. A manufacturer must predict whether the future value of a feature is high enough for the customer chain to pay for it. The challenge for the manufacturer is to develop and produce a high-performance heat pump feature in a household product with high quality, predict future willingness to pay for it, and launch it at the right moment in order to succeed.

    Tumble dryers with heat pump systems have been on the market since 2000. Paper I reports on the development of a transient simulation model of a commercial heat pump tumble dryer. The measured and simulated results were compared with good similarity. The influence of the size of the compressor and the condenser was investigated using the validated simulation model. The results from the simulation model show that increasing the cylinder volume of the compressor by 50% decreases the drying time by 14% without using more electricity. 

    Paper II is a concept study of adding a heat pump system to a dishwasher in order to decrease the total electricity usage. The dishwasher, dishware and water are heated by the condenser, and the evaporator absorbs the heat from a water tank. The majority of the heat transfer to the evaporator occurs when ice is generated in the water tank. An experimental setup and a transient simulation model of a heat pump dishwasher were developed. The simulation results show a 24% reduction in electricity use compared to a conventional dishwasher heated with an electric element. The simulation model was based on an experimental setup that was not optimised. During the study it became apparent that it is possible to decrease electricity usage even more with the next experimental setup.

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  • 19.
    Bengtsson, Peder
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). ASKO Appliances AB, Lidköping, Sweden.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Concept Study of a New Method for Drying Dishware in a Heat Pump Dishwater2017In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 10, no 6, p. 1529-1538Article in journal (Refereed)
    Abstract [en]

    In a heat pump dishwasher, the whole dishwasher with the cabinet, dishware and process water is the heat sink, while a water tank, whose contents will freeze, is the heat source. The aim of the experimental concept study presented here was to evaluate a new drying method for a heat pump dishwasher. In this method, the drying of the dishware occurs as a fan circulates humid air in a closed system in which the water on the dishware evaporates inside the warm dishwasher cabinet and then condenses on a cold surface of the frozen water tank. The evaluation of drying performance was based on the European standard EN50242, which considers visible water drops left on the dishware after a completed dishwashing cycle. The results showed that this new closed drying method was more energy efficient compared to an existing open drying method, and that the drying start temperature and the drying time had a significant effect on the drying performance. Its lower electricity consumption and the fact that it does not vent humid air into the kitchen gives this heat pump dishwasher a competitive advantage over dishwashers using an open drying method.

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  • 20.
    Bengtsson, Peder
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Berghel, Jonas
    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.
    A household dishwasher heated by a heat pump system using an energy storage unit with water as the heat source2015In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 49, p. 19-27Article in journal (Refereed)
    Abstract [en]

    Electricity usage by a household dishwasher can be reduced by using a heat pump system to heat the dishwasher cabinet, dishware and washing water. The evaporator obtains the energy from an energy storage unit which consists of a container filled with water which freezes to ice. The majority of the heat transfer from the energy storage to the evaporator occurs when ice is created in the energy storage unit. A transient simulation model of a dishwasher with a heat pump system was developed and compared to an experimental setup with good agreement. A simulation study of the compressor cylinder volume and the compressor operating time was performed. The results showed a 24% reduction in total electricity use compared to a dishwasher cycle using a traditional electric element.

  • 21.
    Bengtsson, Peder
    et al.
    ASKO Appliances AB, Lidköping.
    Eikevik, Trygve
    Norwegian University of Science and Technology.
    Reducing the global warming impact of a household heat pump dishwasher using hydrocarbon refrigerants2016In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 99, p. 1295-1302Article in journal (Refereed)
    Abstract [en]

    In a heat pump dishwasher, the dishware and the dishwater constitute the heat sink and a water tank filled with water, which can freeze, the heat source. A simulation model developed and validated earlier was modified and used in a parameter study to determine the lowest total electricity usage for the refrigerants R134a, R290, and R600a with different cylinder volumes of the compressor. The total equivalent warming impact (TEWI) was calculated in three regions with different CO2 eq. emissions from electricity generation, i.e., Sweden, Europe (OECD), and Europe (Non-OECD), for small, medium-sized, and large households. In regions with low CO2 eq. emissions from electricity generation, the total TEWI of a heat pump dishwasher is the lowest with R600a and the highest with R134a, and in regions with high CO2 eq. emissions, the total TEWI is the lowest with R600a and the highest with the conventional electrical element.

  • 22.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    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.
    Lösningarna finns! Är pelletsproducenterna medvetna om problemen?2011In: Bioenergi: utmaningar och möjligheter / [ed] Delin, Karin, Persson, Lars, Wikström, Per-Arne, Gävle: Region Gävleborg , 2011, p. 25-29Chapter in book (Other academic)
    Abstract [sv]

    Sverige är inte längre världsledande som pelletsproducent. USA producerar allra mest pellets i världen. Kanada och Ryssland producerar också allt mer pellets. Ingen av dessa länder har någon omfattande inhemsk konsumtion. I stort sett all pellets exporteras och det sker huvudsakligen till Europa. Sannolikt kommer det att leda till att priset på pellets i Europa sjunker, med följd att lönsamheten för svenska pelletsproducenter minskar.

  • 23.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    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.
    Varför får inte villaägaren driva kvalitetsutvecklingen på bränslepellets?2011In: Bioenergi: utmaningar och möjligheter / [ed] K. Delin, L. Persson, P.-A. Wikström, Gävle: Region Gävleborg , 2011, p. 31-33Chapter in book (Other academic)
  • 24.
    Berghel, Jonas
    et al.
    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.
    From sawdust to pellets. Still a challenge...2012In: Public Service Review European Union, no 33, p. 398-399Article in journal (Other academic)
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  • 25.
    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.
    Effects of Using Draft Tubes in a Continued Spouted Bed Dryer2012Conference paper (Refereed)
  • 26.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Superheated steam drying of sawdust in continuous feed spouted beds: a design perspective2014In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 71, no 0, p. 228-234Article in journal (Refereed)
    Abstract [en]

    Spouted bed drying technology shows promising results for the drying of unscreened sawdust in superheated steam. In this paper, the experiences from designing, running and evaluating two spouted bed continuous feed dryers are presented. Stable running conditions and drying results have been achieved. This has been particularly important for sawdust that will be compressed into pellets or briquettes. The spouted bed superheated steam dryer also shows high potential for energy efficient integration into sawmills. Our recommendation is thus, to use the outlet steam temperature as the control parameter for the outlet moisture content. A drying rate above and one below the fibre saturation level, can be identified. Visual observations through the viewing glass in the drying zone in both the dryers clearly showed that not all of the material participated in the spout at all times; there were, however, no indications of dead zones. A heat transfer analysis indicated that only about 70% of the surface area of the material was in thermal contact with the steam. This paper sums up the experiences regarding drying properties, control and system properties obtained when sawdust is dried using superheated steam as the drying medium. Further work on standardised dryers in series or in parallel is necessary to increase the capacity in the spouted bed dryer.

  • 27.
    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)
  • 28.
    Berghel, Jonas
    et al.
    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).
    How residence time in the mixing conditioner affects the quality in wood fuel pellets2016Conference paper (Other academic)
  • 29.
    Berghel, Jonas
    et al.
    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).
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The amount of dust and rejects as well as the electricity consumption during production decreases with the use of adequate additives2017Conference paper (Other academic)
  • 30.
    Berghel, Jonas
    et al.
    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).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Pichler, Wilfried
    Holzforschung Austria, AUS.
    Weigl-Kuska, Martin
    Holzforschung Austria, AUS.
    A comparison of relevant data and results from single pellet press research is Mission Impossible: A review2022In: Bioresource Technology Reports, E-ISSN 2589-014X, Vol. 18, article id 101054Article in journal (Refereed)
    Abstract [en]

    A global increase in the wood fuel pellet market requires knowledge of new biomasses pelleting abilities. As large-scale industrial tests of new materials are costly, tests in e.g., a single pellet press (SPP) are desirable. SPPs have many different configurations and it typically produces one pellet at a time and can give results of its pelletability. This review has surveyed the research that has been carried out of SPPs to ascertain the feasibility of comparing their obtained data and the results. The results show that it is almost impossible to compare the data and results of the various different SPP studies, e.g., some information from the data used was missing, resulting in that only 27 out of 70 papers were comparable. One solution could be the introduction of a common SPP testing method using a determined set of data that enables a reference pellet to be produced in every study.

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  • 31.
    Berglund, Alfred
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Ackumuleringspotential av PHA  från restströmmar inom pappersbruk: En studie om PHA från Gruvöns, Bäckhammars och Skoghalls bruk2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Plastic is one of the most universal materials used today. With a good future view, with new implementations and applications, it makes a lot of time to look at the production and management of the plastic materials. Plastic materials that have been used in our daily lives cause serious environmental problems. Millions of tons of these non-degradable plastics accumulate in the environment every year. The basic problem is that plastic is not naturally occurring in nature since containers are usually made of polyethylene terephthalate. This means that microorganisms do not have the ability to break it down to the current cycle. It takes hundreds of years for plastic containers to break down, not biologically but only degenerate into smaller and smaller pieces. Plastic breaks down into smaller pieces that become smaller and smaller until we cannot see them with the naked eye, mainly through heat and UV light. Although we cannot see them, they are still present and become part of our nature forever. Bioplastics is the plastic industry's tool to try to reduce these little pieces of our nature that will remain forever so that they do not grow more. With today's plastic packaging, which is said to be bioplastic, additives of, for example, cobalt and nickel, which are said to make it easier for the polymers to break down over time, have proven to be not as effective as they thought.

    Polyhydroxyalkanoates (PHA) are polymers which are biodegradable as based on their composition have different physical properties. PHA is a family of natural polyesters synthesized from various microorganisms discovered in 1926. Once discovered, interest has been high due to their biodegradability and its production from renewable resources. The polymers can be described generally as production from microorganisms under controlled conditions, where they occur naturally in organisms that classify them as biopolymers. Some of these polymers are already industrially produced on a large scale today. However, many still apply to several new areas but must be optimized for commercial production.

    Biopolymers can be classified into four groups. Amino-acid-based polysaccharides from bacteria, polyphenol-based and polyesters that this study is looking at. Depending on what the microorganisms possess for character traits and what they give to the substrate to break down, it gives polyesters with different physical properties. This case is a short-chain polyester to be formed, more specifically P3HB which is a three-carbon PHB polyester in its polymer which can be up to 5-7 units long.

    To avoid ongoing problems, a solution is needed. A solution that has received much attention to reduce plastic residues in nature is the use of biodegradable plastics and among them polyhydroxyalkanoates. Polyhydroxyalkanoates (PHAs) are common intracellular compounds found in bacteria, archaea and in few eukaryotes such as yeast and fungi. PHA acts as an energy storage polymer that is produced in some microorganisms when the carbon source is abundant and other nutrients such as nitrogen, phosphorus, oxygen or sulfur are limited. These polymers accumulate intracellularly up to 90% of the dry weight of the cell under nutritional conditions and act as energy saving materials. It has resembled mechanical properties like the traditional oil-based plastic such as polypropylene or polyethylene that can be formed with other synthetic polymers. PHA plastics possess many more applications, in agriculture, packaging and in the medical industry. It is biodegradable and also immunologically compatible. What the PHAs plaster can cause is an ultimate decomposition from a non-fossil source, which is exactly why it is very attractive.

    The purpose of this study was that from a hypothesis see within a limited time frame of ten hours of bio sludge from Gruvön, Skoghall and Bäckhammar's use could accumulate PHA with the aid of added readily degradable substrate. The process of the study will be a small part of a current research project together with Paper Province, Promiko, Pöyry and RISE. The aim of their study is to use residues from the forest industry to make hydrogen as well as bioplastics. This study will help to look at a subprocess of their cascading process.

    The aim of the study is to be able to measure the amount of PHA that could accumulate and rank the potential of the different uses. Using chemical analysis methods and extractions, it will provide opportunities to measure the accumulation of PHA in the various bacterial cultures of biomass from the use. The methods involve soxhlet extraction to successfully extract PHA from the bacteria. Dosage of substrate is sodium acetate piped from egg-diluted solution at 600 mg per dosage. In order for the dosage to be added at the right time, DO and the pH of the reactors were measured and logged throughout the course. FT-IR is used to view the course of events during the experimental period, linked to known features that may indicate that PHA is present in the bio sludge. Nutrients like phosphorus and nitrogen are measured, along with SÄ, SS, TOC, several before and after the experiment to compile discussion of the results.

    The conclusion was based on the analysis methods that the bio sludge that yielded the best yield was from Gruvöns use. This also relates best to the hypothesis of celebration and starvation, the relationship to which the bio sludge is exposed. The mine has a slurry in its five-step process which causes the bio sludge to return from step five where there is a shortage of food for bacteria to step three where there is a lot of food to consume. The rankings of the different uses relate to the hypothesis that the use of mining was best and the worst was the use of Bäckhammar. Based on the analysis methods included in the study, it can be concluded that the bio sludge that yielded the best yield was Gruvöns use with 13.6% of PHA / VS from the soxhlet extraction, the practice was best matched to the hypothesis. The ranking of the different bio sludge of the use is based on the hypothesis that Skoghall's use was second best followed by Bäckhammar's use which was the worst in accumulating PHA in the bacterial culture.

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  • 32.
    Bergström, Jarl
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Utvärdering och driftplanering av Lidköpings värmeverk2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Lidköpings värmeverk har i uppgift att producera värme till Lidköpings invånare och företag. Distributionen sker via kommunens fjärrvärmenät. Värmeverket har förutom ren värmeproduktion även möjlighet att producera el och kyla bort ett visst effektöverskott sommartid.

    I dagsläget har värmeverket inga klara riktlinjer för hur elproduktionen och bortkylningen av värmen ska hanteras vilket är av betydande del för värmeverkets ekonomi. En ökad kunskap om hur man tar tillvara på förfogad energi har efterfrågats och är en del i att hjälpa Sverige som land att uppnå uppsatta miljö- och energimål.

    Med linjärprogrammering har en beräkningsmodell tagits fram för att utifrån givna förutsättningar optimera driften av värmeverket. Mot historiska lastdata har modellen använts för att:

    • Utreda hur väl värmeverket har tagit tillvara på förfogad energi. Parametrar som panndrift, rökgaskondensering, spillvärme, turbindrift och bortkylning av värme har studerats.
    • Driftplanerat värmeverkets pannor. Förutom tidigare nämnda parametrar tillkommer drifttid, total mängd bränsle och revisionsplanering.
    • Utrett typiska driftfall för vår, sommar, höst och vinter beroende på elpris och tillgång på olika typer av bränsle.

    Resultatet visar att:

    • Värmeverket har underutnyttjat möjligheten till elproduktion under större delen av året, men också producerat el på förlust under kortare perioder.
    • Köpt spillvärme på förlust under delar av året, men att spillvärmen som helhet har varit en god affär för värmeverket.
    • Det saknas tillförlitlighet hos mätutrustningen som hanterar bortkyld energi sommartid.
    • Värmeverket bör förbränna mer avfall än den mängd som är planerad sedan tidigare.
    • Bortkylning av värme för att hålla igång turbinerna sommartid har en väldigt liten påverkan för resultatet vilket innebär att värmeverket bör vara restriktivt med att kyla bort energi vid brist på avfall.
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  • 33.
    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
  • 34.
    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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  • 35.
    Bondesson, Carl
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    PHA-produktion och nerbrytning inom en industriell symbios.: Kan PHA produceras i en industriell symbios och har det rätt nedbrytningshastighet2023Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Sweden aims to be carbon dioxide neutral by 2045 and not increase the earth'saverage temperature by more than 2°C. In order to achieve this goal, fossil-basedproducts must be reduced or completely phased out of the Swedish market.Currently, the majority of all plastic produced is based on fossil raw materials. Theburning of fossil plastics leads to significant emissions of greenhouse gases into theatmosphere. The littering of fossil-based plastic on land and in the sea is at the sametime one of the most difficult environmental problems. An alternative is to replacefossil-based plastics with polyhydroxyalkanoates (PHA), which are renewable andfully biodegradable bioplastics. Bacteria produce PHA when they receive volatilefatty acids (VFA). In this project, bacteria were used in biosludge from a pulp andpaper mill treatment plant. The biosludge is rich in bacteria that can accumulate PHAand when VFA is added, the bacteria store these substances in their cells as a sourceof carbon and energy. The biggest challenge in PHA production is the lowprofitability due to the high production costs of VFA. There is an opportunity tolower costs by creating an industrial symbiosis where different industries utilize eachother's residual products and waste heat. Lixea is a company in Kristinehamn thatuses residual products from the forest industry to create new sustainable products.During their process, a reject water containing VFA is formed. Another companycould potentially combine the biosludge from a pulp mill and VFA from Lixea toproduce PHA. The PHA produced can then be used for a plastic film for Blue OceanClosures screw caps and the Tubesprout plant protection. Which in the end, anindustrial symbiosis between five companies has been created.n this thesis, some of the basic necessary processes in an industrial symbiosis areinvestigated. Is it possible to produce PHA within the symbiosis and does the PHAhave the right degradation rate to suit the products in the symbiosis? The goal of thethesis is to explore the use of PHA as a material for Tubesprout and a plastic film forBlue Ocean Closure, with special requirements for degradation time in differentenvironments. Develop an accelerated degradation method of biodegradablematerial. In the accumulation trials of PHA, biosludge from Stora Enso Skoghall'smill and VFA from Lixea are used. To analyze whether the biomass accumulatedPHA, the methods FT-IR and acetone extraction are used. PHA underwent adegradation test along with four other materials PE, PLA, Blue Ocean Closure screwcap and Tubesprout to investigate how quickly they degrade. The materials are testedin five different environments; compost, two pine forest lands where one is enrichedwith hydrocoal, the lake and a newly developed activated sludge. The new method,activated sludge, is microorganisms taken from a municipal treatment plant.Degradation rate was determined by measuring, the weight loss of the material,microscope images and images above material.The result shows that VFA from Lixea can accumulate PHA but that the bacteriadied during both experiments. The highest level of PHA accumulated in the biomasswas Lixea 2 which corresponded to 10.3 percent. PHA has a similar degradation rateas Tubesprout, which means the possibility of replacing PHA as material for a        Tubesprout. PHA to a plastic film would work from a degradation perspective wherethe requirement was that it degraded at nearly the same rate. In the degradation tests,activated sludge had the best degradation rate of all materials. Activated sludge is asimple method that can be used as a rapid test when examining biodegradablematerial.

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  • 36.
    Brunzell, Lena
    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 Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Recommendations for revising the energy label system for dishwashers: Supporting sustainable development and usage through the interaction of energy labels, technical improvements and consumer behaviour2019In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 13, no 1, p. 145-155Article in journal (Refereed)
    Abstract [en]

    Historically, domestic chores such as washing dishes were all done by hand. Today it is estimated that 44% of the households in the EU are equipped with a dishwasher. In this article, we discuss the connections between technical developments, consumer behaviour and the test standard for energy labels. The aim of this study is to provide recommendations for future work that would strengthen the role of the energy label in order to promote the more sustainable technical development of household appliances. Technical developments are compared with the consequences of different consumer behaviour. It was found that technical developments could reduce annual energy use, but depending on the implemented technology, this is often complex and requires additional components. On the other hand, a consumer can easily increase energy usage by 50% without being aware of doing so, when goods are pre-treated, appliances incorrectly loaded, or inappropriate programs selected. Our recommendation is first of all to encourage the use of dishwashers as they consume less energy and water compared with washing up manually. A holistic approach should be taken to updating the energy labelling system. Actual consumer behaviour must be taken into account and, perhaps most importantly, as dishwashers are becoming ever more energy efficient, consumers must be educated in using the machines in an environmentally friendly way. We conclude that the energy labelling system is outdated; it must be fundamentally revised and must take into account consumer behaviour.

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  • 37.
    Bäcklin, Daniel
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Energieffektiv kylning av frukt: Studier och simuleringar av forcerad luftkylning i en Californiatunnel för minskad elanvändning2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Every day people buy fruit and vegetables. A problem with these produces is that they are usually not locally grown, but they have often undergone long journeys. Because fruit is perishable, they easily become damaged and rot during a long transport. The most cost effective way to extend the shelf life of fruit is by cooling it. Since it is desirable that fruits are in the same state as if they were freshly harvested, it is important that they are cooled to their optimum temperature as quickly as possible after they have been harvested. The most common pre-cooling method is forced air cooling.

    The work has been done in collaboration with Billerud Fresh Services AB. The company's goal is to reduce wastage of fruits and vegetables through improved packaging solutions, with paper as raw material, thereby improving both the economic and environmental efficiency throughout the value chain, from harvesting and cooling until the fruit is on the store shelf.

    The purpose of this study is to investigate what effects the use of electricity in forced-air cooling and how it can be reduced. If the energy use during the air-cooling could be reduced, then carbon emissions and economical cost of the cooling process can be reduced. This allows growers to be able to afford a complete cooling process and the losses from fruit that has been damaged due to bad cooling will decrease. This increases the value of the fruit value chain and suppresses the increase of greenhouse gases.

    The aim of this study is to describe how the cooling homogeneity and the fan energy power during forced air cooling of fruits and vegetables depends on the box and the California Tunnel design.

    By simulations in COMSOL Multiphysics 4.3, the impact of the vent hole ratio on the pressure drop is studied. Simulation in COMSOL has also been made to estimate how the flow varies between boxes in a California Tunnel and how this tunnel can be modified to provide a more homogeneous cooling. Experiments have been conducted to compare the cooling homogeneity in an existing box and a new box designed to create a uniform air flow.

    The results of the experiment showed that the cooling homogeneity could be increased by changing the box design, thereby reducing electricity consumption. The simulation of the California tunnel showed that a modified tunnel arrangement could reduce the airflow difference between the boxes from that at a classic arrangement being 60 % to be less than 1 %. This allows the homogeneity to increase and electricity can be saved. The results of the simulations showed that if the vent hole ratio is halved, the fan energy demand will increase fourfold. Therefore it is important that, when designing a box, the vent hole ratio is high for electricity use to become low.

  • 38.
    Carlaby, Jesper
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ventilationsbuller: Teknik och ekonomi för ett tyst system2013Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Noise from the ventilation systems affects us more or less every day. There are some requirements on how much noise that’s allowed to generate from the ventilation system set by Karlstads Kommun based on Boverkets Byggregler. But how could a more silent system be constructed at a more stringent level of requirements?

    The aim is to investigate a reasonable sound level based on technology and economics. Based on Råtorps preschool, owned and operated by Karlstads Kommun, performed calculations using the existing calculation template and sound measurement according to a Swedish Standard. It is done to find out how the sound environment of preschool looks like today in relation to the requirements set. An analyze of the staff's perception of sound generation from ventilation to be able to consider what is an acceptable noise level. Subsequently, calculations are made to find out which theoretical improvements that can be done, especially technically and also financially, in order to reduce the noise level.

    According to the noise measurements that are made, the noise level at the preschool is below or at the same level as the requirements. The results are consistent with the calculations performed in addition to the room that previously was in line with the requirements, now is over the limit. The noise from the ventilation is perceived as disruptive in two of the four rooms, but the results of the theoretical improvements are showing that it is possible to reduce the noise to a more acceptable level. This can be done without major financial consequences, than the most costly and improvement measure that was tested found to be least effective in lowering the noise level.

    This work results in that even though the set requirements are followed as perceived ventilation to some extent as disturbing nonetheless. It would be possible to reduce noise generation with relatively small funds without excessive economic consequences and thus create a better working environment.

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  • 39.
    Carlén Bäckström, Ebba
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Design av en Pre-Swirl Stator för att öka framdrivningseffektiviteten hos ett chemfartyg - en CFD studie2024Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Inom den marina industrin har ett allt större fokus riktats mot att hitta lösningar för att minska fartygens energiförbrukning. Delvis till följd av globala trender såsom ökad miljömedvetenhet och högre bränslepriser, men framför allt på grund av nya internationella regelverk som begränsar de tillåtna utsläppen från fartyg. En åtgärd för att öka fartygs framdrivningseffektivitet är genom att installera energibesparande enheter (ESD). En Pre-Swirl Stator (PSS) är ett exempel på en sådan enhet, som består av ett antal statorblad som monteras framför propellern för att skapa en mer fördelaktig flödesregim och optimera propellerns arbetsmiljö.

    I denna studie genomförs en numerisk undersökning av en PSS som en potentiell lösning för att förbättra framdrivningseffektiviteten genom eftermontering på ett chemfartyg. Genom att analysera interaktionen mellan skrovets medströmsfält, statorbladen och propellern fås insikter kring hur olika designparametrar på PSS:n påverkar inflödet till propellern. Resultaten från CFD-analysen jämförs med och utan PSS i full skala för att avgöra om PSS:n har en positiv eller negativ effekt på propellerverkningsgraden. De designparametrar som undersökts är antal statorblad/designorientering, stigningsvinkel och NACA-profil. För designarbetet av PSS:n har CAD NX och CFD-programvaran STAR-CCM++ genom Kongsbergs egna HullProp Interface tillämpats.

    Resultaten visar att en PSS kan påverka chemfartygets framdrivningseffektivitet, där PSS:ns designparametrarna har en stor inverkan på om propellerverkningsgraden ökar eller minskar. Genom att installera en PSS kan framdrivningseffektiviteten förbättras och den största verkningsgradsökningen på 0,94 % erhölls för en asymmetrisk design. För att uppnå ökad framdrivningseffektivitet ska PSS:n kunna interagera med det inkommande flödet utan att skapa för stort motstånd. Samtidigt bör en jämn och stabil strömning av vatten genereras in mot propellern. Designparametrarna bör justeras för att undvika flödesseperation på statorbladen, eftersom detta leder till ökat motstånd och ojämn strömning in till propellern. Anfallsvinkeln mot propellerbladen får heller inte bli för stor till följd av statorbladen, då detta kan orsaka flödesseperation på propellerbladen, vilket resulterar i minskad tryckkraft och verkningsgrad. För vidare studier rekommenderas användning av mer avancerade CFD-metoder för att få en tydligare bild av den komplexa flödesdynamiken och verifiera resultaten. Detta kan leda till en bättre förståelse för flödet kring PSS och dess interaktion med propellern, innan en mer omfattande parameterstudie genomförs.

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  • 40.
    Case, Keith
    et al.
    Loughborough University, UK & University of Skövde, Sweden.
    Bäckstrand, Gunnar
    Loughborough University, UK, University of Skövde, Sweden, Volvo Powertrain, Sweden.
    Högberg, Dan
    University of Skövde, Sweden.
    Thorvald, Peter
    Loughborough University, UK & University of Skövde, Sweden.
    De Vin, Leo
    University of Skövde, Sweden.
    An assembly line information system study2008In: Advances in Manufacturing Technology – XXII: Proceedings of the 6th International Conference on Manufacturing Research (ICMR 2008) / [ed] Kai Cheng, Harris Makatsoris and David Harrison, Uxbridge: Brunel University , 2008, p. 181-188Conference paper (Refereed)
  • 41.
    Casemyr, Linnea
    Karlstad University, Faculty of Health, Science and Technology (starting 2013). Karlstads Universitet.
    Energieffektivisering av livsmedelsbutik2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The construction sector today accounts for 20 precent of Sweden's climate impact and 40 percent of energy use. This purpose of this study is to identify the most effective measures to reduce the grocery store's energy needs. The building is tempered primarily with district heating respectively district cooling that operates the air units' cooling and heating batteries. There are many efficiency measures that are feasible for grocery store's energy usage. This study calculates a under construction grocery store's energy needs and analyses which measures can reduce the total need for purchased energy. This study calculates both property energy and industry energy and then compare the economy and environmental impact of the various measures. This store has also been environmentally certified according to the Sweden Green Building Council system. The simulation program IDA ICE is an effective tool that allows information in the form of energy analysis to be evaluated. This study compares the retail chain's own energy solutions with new innovative solutions that can save energy and money. This study's focus is on energy saving measures from ventilation systems, cooling systems and heating systems.

    Measures examined in this study are:

    •         Solar cells on the property's roof

    •         Additional insulation of ceilings and floors

    •         Heat recovery of the grocery refrigeration system

    •         Heat recovery of the industry ovens

    The total property energy was 2,000 MWh or 150 kWh/m2. Heat recovery of the cooling system saves 500 MWh annually, which corresponds to 37 kWh/m2. Installation of 4,000 m2 of solar cells saves 480 MWh, which corresponds to 35 kWh/m2. The measure that is most optimal from an energy point of view is heat recovery from the refrigeration system. The measure that is most economically profitable is the installation of solar cells. The measure that saves the most carbon dioxide is heat recovery from the refrigeration system. The comparison showed that heat recovery is the most profitable measure. After the implementation of all measures, the store reaches Swedish environmental class "environmental building gold".

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  • 42.
    Corrigox, Adam
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Energianalys av rörledning med överhettad vattenånga2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heat transfer is an important physical phenomenon with many different industrial applications, where the transport of a fluid in a pipe is an important part. The main mechanism of heat transfer in flowing or stagnant fluids is convection. A better knowledge and understanding of the underlying physics would imply that the design of the systems could be optimized in order to obtain an economic process by minimizing energy losses and cost of materials.

    A steam turbine in a power plant produces electricity by superheated steam flowing through the turbine. The superheated steam is then transported from the turbine into a pipeline to be used for heating processes in a nearby pulp mill. In this work, an energy analysis was carried out on the pipeline with superheated steam in order to determine the temperature distribution. The choice of material in the pipeline is dependent on pressure and temperature, and with a lack of knowledge of the temperature distribution along the pipe, the construction could be unnecessarily costly.

    A mathematical model was set up with the energy balances acting on the pipeline. An analytical calculation was carried out to analyze how much the heat loss from the pipe is and how much the temperature of the steam decreases. A dynamic model was then built in Simulink to simulate the accumulation of heat in the pipe and the insulation over time, and the mass flow of cooling water. A literature study of the vaporization of the cooling water was carried out to find the parameters that affect evaporation and thus is important in determining the time it takes until all have vaporized.

    The results of the calculations show that the temperature drop of the superheated steam in the flow direction becomes very small. This is because the energy content of the flowing steam is very large compared to the heat loss through the pipe wall. The result from the dynamic simulation shows that the insulation has a larger time constant compared to steel pipe. This is presented in the form of the step response.

    The choice of material will be affected by the position of the desuperheater. In this system the desuperheater is not optimally placed since it is about 42 m after the inlet of the turbine. It would therefore be possible to place it closer to the turbine and then switch to a cheaper lower strength material. 

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  • 43.
    Edlund, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Energieffektiva åtgärder för flerbostadshus2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Energy is a hot topic in today's society. Both businesses and individuals are trying to reduce their spending costs by saving kWh. There are many various saving measures to reduce energy consumption. Reducing energy consumption leads to a reduced carbon footprint as less fuel is burned in facilities that generate emissions. This report will focus on heat pumps, solar technologies and interventions in the building envelope for a multi-dwelling house.

     

    How much energy can be saved from a measure? What impact does it have on the climate? Is it economically viable to invest in the measure? These issues are of importance both for the investor and future generations. In the report, these questions are answered and applied in a multi-dwelling house in Karlstad built in the 1960's with an energy consumption of 129 kWh/m2 and year. The study is a collaboration with HSB.

     

    The building was recreated in a simulation program, VIP-Energy, for a basic case to start from. Then the measure were simulated both individually and in combination to see how effective they are in the building. These measures may lead to an increased electricity consumption, which was taken into account in the calculations of the climate impact if it led to an increased or decreased amount of CO2 emissions. All these measures are designed to reduce energy consumption, leading to a decrease in energy cost.

     

    The results showed that these measures lead to a saving of energy consumption in all cases. The resulting reduction in energy consumption varies between 5-50% on the various measures individually, but the savings do not differ as much. The reason for this is the technical lifetime of the measures, which means that the total savings do not reflect the reduction in energy savings. Reduced CO2-emissions is much more difficult when the building is connected to a district heating plant that also produces electricity, known as a combined heat and power plant, which makes the reduced heat generation leads to reduced power generation. This means that the electricity has to be generated from another source, for Sweden this means imports of electricity from a coal condensing power plant. Electricity from the power plant is in this case CO2-compensated, which means that the fuel comes from a renewable source. In order to have reduced CO2-emissions, it requires that you have your own production of electricity from CO2-compensated or renewable sources.

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  • 44.
    Ekelöf, Henrik
    Karlstad University, Faculty of Technology and Science.
    Jämförelse av vattenburet och luftburet komfortkylsystem i ett kontor: Ur energi- och termisk konfortsynpunkt2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
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  • 45.
    Ekeroth, Jesper
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Effektivisering genom rengöring av kylbatterier och avgasning av köldbäraren2016Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Energy issues are a priority in today's society and will probably be for many years to come. In order to achieve progress in this struggle towards a more energy efficient world, global optimizations will be needed and new ways of thinking need to be realized.

    In the food industry, there is great potential for optimizations and new ways of thinking. One problem area is that many grocery stores do not open their refrigerators and freezers and clean them internally, they only clean the visible surfaces. Failure to clean inside refrigerated display may cause the burdening and dirt into the system that is adversely affected. These may include impacts on the cooling coil, reducing air flow and clog the drains. Impacts on the cooling coil and the air flow in turn could lead to the destruction of food due to high temperatures in refrigerators and freezers. Clogged drains can lead to water leakage, which then can run out on the shop floor.

    During this project, optimization efforts have been made and these include cleaning the cooling coils inside the refrigerator and freezer cabinets and degassing of the brine. The cleaning has been done with overheated steam to remove any burdening to the cooling coils and fans, and all surfaces in refrigerators and freezers. This has been done to see if energy can be saved by increasing the thermal conductivity of the cooling coil.

    The tests that have been done to see if it is possible to save energy by cleaning are ampere- , flow- and temperature measurement.

    Degassing of the coolant has been made on the basis of the same theory as cleaning. By degassing where the ambition that the brine could pick up more veil and thus increase the efficiency of the cooling system.

    Degassing the coolant provides improvements in the sustainability of the system with a reduced risk of corrosion, but what happens to the heat transfer capability is relatively unknown, it has been studied through power measurements on chiller compressor.

    After the test period the results of cleaning tests show that the power demand goes down, while degassing not had any impact. Degassing showed no efficiency of the system because the oxygen levels remained high.

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  • 46.
    Ekeroth, Jesper
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Effektivisering genom rengöring av kylbatterier och avgasning av köldbäraren2016Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
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  • 47.
    Enarsson, Malin
    Karlstad University, Faculty of Technology and Science.
    Ventilation hos TanumsFönster AB: Nulägesbeskrivning och åtgärdsförslag i en industribyggnad2012Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
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  • 48.
    Enström, Marcus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Energianalys av kompressordrivet kylsystem till mobilt energilager: Undersökning av luftburen och vätskeburen kyla av batterier2013Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
  • 49.
    Ericsson, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Biologisk vattenrening inom textilåtervinningsindustri: En utvärdering av Moving Bed Biofilm Reactor för att reducera BOD7 hos Renewcell2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The clothing industry is one of the major causes for negative environmental impacts. The “fast-fashion” needs to be phased out and a more climate-friendly way of using clothes implemented. The easiest ways to do this is to reuse or recycle clothes. Renewcell recycles used textiles and dissolve the cotton into pulp and makes a new material of it - Circulose®, which is sent to become new clothes and, in that way, helps to close the loop for textile industry. With the production of Circulose® a new kind of wastewater is produced which has not yet been thoroughly researched. A parallel to the textile industry’s wastewater can be drawn, and that is of heterogeneous nature and can change quickly from day to day. It is in Renewcell’s interest to reduce the organic matter in the wastewater, more than they do today with their current chemical and mechanic wastewater treatment plant does. This study wants to help fill the research gap that exists for purification technology in the textile recycling industry today. Since it is a new field of technology, it is of importance to thoroughly invest in how to treat the wastewater responsibly. The purpose of this study was to investigate, both experimentally and literary, whether the possibility to reduce BOD7 to 10 mg/l in the wastewater treatment plant. With an investigation of MBBR and by compare it with an MBR it was concluded that a MBBRis a better fit for Renewcell since it is considered to be more resistant to variations and hazardous substances. To strengthen that conclusion a MBBR in laboratory scale was built and wastewater directly from the recycling process treated. The reduction of BOD7 and how it would come to affect the chemical precipitation was analyzed. The results of the study concluded that Renewcells wastewater is heterogenous and manageable for microorganisms. However, the due to the variations in the process such as dosing of biologically harmful substances it might not be possible for Renewcell to implement a MBBR. Process variations as a stop in production of wastewater for a shorter time period is manageable. The wastewater contains enough organic matter, but an extra addition of nutrients is needed. For this project the MBBR-process fluctuated in reduction of organic matter and the highest amount achieved was 58 %. No fully developed biofilm was achieved either. Biologically treating the process effluent before the chemical precipitation gave positive results as the reduction of metal ions was improved. All in all, it is believed to be possible to implement a MBBR at Renewcell if the process is given the required conditions from the beginning and a biofilm can be fully developed. Hopefully, this pilot study can show the way for future research within the field.

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  • 50.
    Eriksson, Linnea
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    The impact of calculation methods on the gap between predicted and actual energy performance of buildings: Using a thermal simulation model of a building2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The building sector is responsible for almost a quarter of the total carbon dioxide emissions. The urgency to reduce the emissions is reflected in the stricter guidelines which have been set all over the world. To reduce the building sector’s emissions the energy consumption need to be reduced, which can be done in two ways: building new energy efficient buildings or retrofitting of current buildings. Due to the life expectancy of current building stock the largest savings before 2030 will be made through retrofits. For this reliable computational tools are required, and currently there is a gap between the predicted and actual performance of retrofitted buildings. This thesis is going to look into how the computational method is contributing to the performance gap. A building at the RMIT campus in Melbourne, Australia, which is going to be retrofitted through retrofits designed by Siemens, is used. A thermal simulation model of the building was built, and tuned to reflect the pre-retrofit building, and compared against the measured energy performance of the building. The retrofits were then implemented in the simulation model and the gap in the predictions between the simpler computational method used by Siemens in designing the retrofits, and the extensive simulation model was compared. The gap between the computational methods were analysed in order to see how Siemens calculation method contribute to the performance gap. The conclusions which have been drawn are that the simulation model is reflecting the energy use of the building well considering the access of data available during the study. Especially the electricity use is reflected well both in the total annual use, approximately 4 % gap to measured value, and the monthly variation over the year. The total natural gas use is under predicting the annual use, approximately 40 % gap to the measured value, but shows a good correlation to the monthly variation. The electricity use is relatively stable in the simulation model, where the natural gas was sensitive for direct changes to the heating system. The input parameters which have the largest impact in the electricity use are internal gain profiles and the electrical internal gains energy use. Siemens calculation method are contributing to the performance gap through the lack of interaction between the different retrofits, the light retrofit have a noticeable impact on the heating and cooling system of the building. To only use one single period in the regression models can also easily lead to incorrect predictions. The strength of the simulation model is its ability to see the retrofits influence on each other and the possibility for scenario analysis.

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