Ökad mänsklig aktivitet och global folkmängd har lett till ökat energibehov där största andelen av energin är från fossila bränslen. Vätgas ses som en effektiv energibärare som kan produceras med förnyelsebara resurser och ersätta fossila bränslen. Vätgas producerad med förnyelsebara resurser är dock fortfarande dyrt jämfört med produktion från fossila bränslen.Det finns få tidigare studier som har studerat utnyttjandet av spillvärme från vätgasanläggningar och vilken påverkan det kan ha på den ekonomiska lönsamheten.Den här studien som sker i samarbete med Research Institutes of Sweden (RISE), syftar till attoptimera en vätgasanläggning, med ett på förhand definierat vätgasbehov, utifrån ett ekonomiskt perspektiv och se om en sektorkoppling till ett fjärrvärmenät kan förbättra det ekonomiska resultatet. Sektorkoppling innebär i den här studien att spillvärme skickas från vätgasanläggningen in till fjärrvärmenätet. Systemet som studeras består utav en elektrolysör, en bränslecell och ett vätgaslager. Systemet är beskrivet så att i första hand producera en förutbestämd mängd vätgas som ska användas till fordonsbränsle. Därutöver kan systemet utnyttjas för elenergilagring via vätgaslagring, om det visar sig ekonomiskt fördelaktigt. Målen är att optimera fram ett pris för vad vätgasen behöver kosta för att anläggningen ska nå break-even, dimensionera elektrolys, vätgaslager och bränslecell utefter optimal drift ochstudera vad som påverkar den optimala driften av anläggningen.Metoden som används för att optimera vätgasanläggningen är linjärprogrammering i programmet MATLAB. I optimeringen ska den lägsta möjliga nettokostnaden (eventuella högsta nettointäkten) för systemet beräknas. Alla kostnader och intäkter beskrivas linjärt, sedan definieras alla variabler som påverkar kostnader och intäkter. Variablerna kommer i sin tur att bero på villkor, samt linjära likheter och olikheter som begränsar hur små eller stora värden de får anta för att påverka resultatet. Optimeringen sker över en tidsperiod på 1 år och med tidssteget två timmar. Historiskt elpris för 2021 SE3 användes i studien. Variationen i elpriset är svår att mäta, därför skapades även ett eget elpris som inte är så komplext för att närmare kunna studera variationens påverkan.Resultaten visar att vätgasen ska säljas för ungefär 36,6 kr/kg för att nå break-even när priset optimeras och spillvärmen inte utnyttjas. Utnyttjandet av spillvärme kan sänka priset med 1,6 - 2,5 kr/kg beroende på om spillvärmen utnyttjas delar av eller hela året. Elektrolysör och vätgaslager bör dimensioneras beroende på ett fördefinierat vätgasbehov, enligt dimensionsfaktorerna 4,9 [MW/(ton vätgas/dag)] respektive 1,4 [ton/(ton vätgas/dag)].Värmeeffekten som kan utnyttjas från vätgasanläggningen kan dimensioneras beroende på ett fördefinierat vätgasbehov, enligt dimensionsfaktorn 0,9 [MW/(ton vätgas/dag)]. Resultatet visar trender på att elpriset påverkar storleken på elektrolysör, vätgaslager och även vilka timmar som elektrolysen är aktiv. Att dimensionera anläggningen som funktion av elpriset har visat sig vara en komplex fråga, och fler studier behövs inom det området. En trend visar att utnyttjandet av spillvärme har en mindre påverkan på vätgaspriset vid högre verkningsgrad på elektrolysen, och ökad påverkan vid lägre verkningsgrad. Spillvärme som ersätter värme från fjärrvärmepanna minskar utsläppen med ungefär 38 kg CO2e/MWh beror på fjärrvärmeproducentens befintliga pannor/bränslen. För investerarna betyder resultaten en riktlinje för priset på vätgasen, uppskattad dimensionering av anläggningen, att det i praktiken aldrig är lönsamt med bränslecell och en inblick i det ekonomiska värdet av spillvärmen. För fjärrvärmebolaget betyder resultaten minskade utsläpp av koldioxidekvivalenter, en extravärmekälla och möjligen minskade kostnader. För energisystemet i stort betyder resultaten att den höga variationen på elpriset kan utnyttjas för att producera vätgas, att det gröna vätgaspriset kan sjunka från dagens nivåer och att spillvärmen kan bidra till ett effektivare energisystem. / Increased human activity and global population have led to an increased energy demand, with most of the energy coming from fossil fuels. Hydrogen is seen as an efficient energy carrier that can be produced using renewable resources and replace fossil fuels. However, hydrogen produced from renewable resources is still expensive compared to production from fossil fuels. There have been few previous studies that have examined the utilization of waste heat from hydrogen facilities and the impact it can have on economic profitability.This study, conducted in collaboration with Research Institutes of Sweden (RISE), aims to optimize a hydrogen production facility, with a predefined hydrogen demand, from an economic perspective and assess whether a sector coupling to a district heating network can improve the economic outcome. In this study, sector coupling means that waste heat is sent from the hydrogen facility to the district heating network. The hydrogen plant consists of an electrolyzer, a fuel cell, and a hydrogen storage. The system is designed to primarily produce a predetermined amount of hydrogen to be used as vehicle fuel. Additionally, the system can be used for electrical energy storage through hydrogen storage if it proves to be economically advantageous. The objectives are to optimize the price at which hydrogen needs to be sold for the facility to break even, sizing the electrolyzer, hydrogen storage, and fuel cell based on optimal operation, and study the factors that affect the optimal operation of the facility.The method used to optimize the hydrogen facility is linear programming in the MATLAB program. The optimization aims to calculate the lowest possible net cost (or highest net income) for the system. All costs and revenues are described linearly, and then all variables that affect costs and revenues are defined. These variables, in turn, depend on conditions as well as linear equalities and inequalities that restrict the values, they can take to influence the result. The optimization is carried out over a period of 1 year with a time step of two hours. Historical electricity prices for 2021 SE3 were used in the study. The variation in electricity prices is difficult to measure, so a simplified electricity price was also created to study the impact of the variation more closely.The results show that the hydrogen should be sold for approximately 36.6 SEK/kg to break even when the price is optimized, and waste heat is not utilized. The utilization of waste heat can reduce the price by 1.6-2.5 SEK/kg depending on whether the waste heat is utilized for parts or the entirety of the year. The electrolyzer and hydrogen storage should be dimensioned based on a predefined hydrogen demand, according to the factors of 4.9 MW/(ton of hydrogen/day) and 1.4 ton/(ton of hydrogen/day), respectively. The heat output that can be utilized from the hydrogen facility can be dimensioned based on a predefined hydrogen demand, according to the factor of 0.9 MW/(ton of hydrogen/day). The results show trends indicating that the electricity price affects the size of the electrolyzer, hydrogen storage, andthe hours during which the electrolyzer is active. Dimensioning the facility as a function of the electricity price has proven to be a complex question, and further studies are needed in that area. One trend indicates that the utilization of waste heat has a smaller impact on the hydrogen price at higher electrolyzer efficiency and a greater impact at lower efficiency. Waste heat that replaces heat from a district heating boiler reduces emissions by approximately 38 kg CO2e/MWh, depending on the existing boilers/fuels of the district heating producer. For investors, the results provide guidelines for the price of hydrogen, estimated dimensioning of the facility, the practical non-profitability of fuel cells, and insights into the economic value of waste heat. For the district heating company, the results mean reduced emissions of carbon dioxide equivalents, an additional heat source, and possibly reduced costs For the Swedish energy system, the results imply that the high variation in electricity prices can be utilized to produce hydrogen, leading to a potential decrease in the price of green hydrogen compared to current levels. Additionally, the utilization of waste heat can contribute to a more efficient energy system. / HyCoGen

Sweden has ambitious climate goals, such as the overarching goal, the 2045 goal. The goal is for Sweden to have zero net emissions of greenhouse gases by 2045 at the latest. In order to achieve the overall climate goal and the interim targets, electrification of society is an important component. The industrial sector and the transport sector each account for about a third of Sweden’s emissions, where the conversion to electricity is an important solution. The electrification of passenger cars and buses has meant that emissions from domestic transport have decreased every year, and in order to achieve the interim target of 70 percent lower emissions of greenhouse gases in 2030 compared to 2010, the electrification of heavy duty trucks is one of the key components. However, there are long-term challenges with the power grid and already today grid owners have capacity challenges. Regional grid owners cannot increase their power subscription, while local grid owners cannot grant new connections. Regarding the electrification of long-haul transportation, there are challenges in terms of charging infrastructure. Truck drivers operate on a strict schedule, and minimizing down time is crucial to keep costs down. By law, truck drivers must take a 45-minute break after 4.5 hours of driving time, which means that during this break it is desirable to recharge the vehicle before departure. This means that high power demands are placed on the charging infrastructure that exists to be able to transmit the desired energy.   A new standard, the Megawatt Charging System (MCS), which meets the high power requirements has been developed and is included in pilot projects. The maximum power that the charging standard can deliver is 3.75 MW. The results of the thesis show that these high-power chargers place high demands on thepower grid. When connecting a charging station with MCS charging points to the grid, it may require local upgrading of lines and transformers, but also upgrading in otherparts of the network. Examples of such upgrades are reactive power compensation to be able to support the network locally at peak loads to obtain voltage levels within stable voltage ranges, but also upgrades of lines and transformers to be able to deliver the desired power. Integration of a battery storage in connection with a charging station relieves the powergrid and its components. However, it is important to highlight that since the battery needs to be recharged, this means that a more even power requirement is needed. However, the  maximum load on both transformers and lines is reduced, which can be a desirable effect when a charging station of the same nature is put into operation.

The Swedish authority for social protection and preparedness, MSB, believes that the self-sufficiency of the country must be strengthened in order to be prepared for a crisis. Presently, Sweden is only 50% self-sufficientwhich is very low compared to its neighboring countries; and it is worse the further north you go. One solution could be to increase the production of food, for example vegetables, but the number of greenhouse operations in Sweden are already dwindling due to the inhospitable climate, which makes it expensive to keep up all-year cultivations. Norrbotten, the northernmost part of Sweden, has the highest heat demand for greenhouses in the country. One option could be to set up operation in heavily insulated buildings and rely on artificial lighting, in so called plant factories. Though, these are expensive, electricity intensive and have generally lower yields. This report will cover the development, validation, and performance of a dynamic model of a new greenhouse concept, developed for subarctic climates. The greenhouse is meant to utilize the strengths of both glass houses and plant factories to optimize the profits for a year-round operation. This, to find an alternative solution to the self-sufficiency problem in the winter. In addition to this, the optimal glaze for the climate shell had to be determined and what type of lighting technology would be the most viable. The hybrid greenhouse is a gableroof greenhouse with insulated north, west and east walls designed for microgreen cultivation, Lactuca Sativa. The interesting part of the greenhouse is that it has a retractable insulation cover, of mineral wool, inside of the climate shell. This was meant to heavily insulate the greenhouse during the winter seasons, though it would not let any sunlight in. This meant that the hybrid greenhouse must rely on artificial lighting in the winter but will get a reduced heating demand. When the outdoor temperature rises and the sun becomes more visible,the cover can be retracted to utilize sunlight for heating and photosynthesis. The cost between heating and electricity usage and the profits from the amount of yield will therefore vary depending on how long the coveris opened or closed and an optimal cost solution should be found somewhere within that variation. The model was created using Simulink version 10.6, which could simulate the heat demand, the humidity level, CO2-concentration, and the yield of the greenhouse. The models heat demand and yield was validated againsta greenhouse in Nikkala, Sweden, owned by Norrskenstomater. The model produced a standard deviation of 24.6 MWh over three months but it overestimated the yearly yield of Norrskenstomater with about 40%. To make the sure the hybrid greenhouse performed effectively, the amount of leakage must be minimized, as this has a significant impact on the heat demand. The hybrid greenhouse needs lighting alternatives with substantial active cooling (90% of the lamps input power), such as light emitting diodes. High pressure sodium lamps produce too much heat and can not be used at all. For yearly simulations, the cover was set to close for certain amounts of months during the year. The highest yearly profit, highest net present value (4.8 MSEK) and lowest payback time (3.5 years) could be achieved if the cover were closed between October and March. The best glazing material in terms of economic performance was 4 mm glass followed by 16 mm plastic panels in acrylic. The hybrid greenhouse could even outperform a greenhouse that did not cultivate during the winter. The hybrid greenhouse seems to get rid of the negative impacts of winter cultivation and is therefore considereda viable alternative as a cultivation system for subarctic climates.

Computational Fluid Dynamics (CFD) has emerged as an indispensable tool in various engineering fields, particularly in the design and optimization of HVAC systems in complex environments, such as engine rooms. This paper presents a comprehensive overview of CFD applications and focuses on the engine rooms of the Grange Castle Power Plant in Dublin, Ireland. Sustainable Development Capital LLP (SDCL) is constructing a state-of-the-art power plant at Grange Castle Business Park in Dublin, featuring six MAN 18V51/60DF engine generators and a total net export capacity of 111 MW. The plant uses pioneering dualfuel technology and serves as a contingency facility to stabilize the power grid amidst increasing integration of renewable energy. It functions as a responsive backup power generator and a peak load reducer, aiding the Irish government's goal of sourcing 80% of power from renewables by 2030. The initiative is part of a wider strategy including MAN Energy Solutions and Greener Ideas Limited, contributing to three new power plants in Ireland with a combined capacity of 311 MW.This study utilizes steady-state CFD simulations, employing the widely adopted k-epsilon turbulence model. Known for its robustness and computational efficiency, the k-epsilon turbulence model is utilized to analyse one engine cell at the Grange Castle Power Plant. As a two-equation model, it involves solving two additional transport equations alongside the Navier-Stokes equations to simulate fluid flow.Commonly applied in engineering applications, this model will be utilized to provide predictions of airflow and temperatures within the cell during standby and running states over the course of the year. By leveraging the strengths of the k-epsilon turbulence model, the study seeks to gain valuable insights into the complex fluid dynamics within the engine cell, ultimately helping to optimize its performance and efficiency. The analysis focused on one engine cell, with the setup and geometry for each cell being identical.Specifically, the research investigates maintaining the temperature within the cell, temperature distributions, airflow comparisons to design specifications and requirements, heating load and adequate airflow calculations, and potential benefits of optimizing the design and operation of the engine cell.The dimensions and characteristics of the engine room, along with the engines themselves and the heat they generate, play a significant role in the design process. In this study, there are several essential factors to consider, including a negative pressure ventilation system, as well as combustion and cooling air provided through air intake units that draw air from outside the engine hall and exhaust it using fans mounted on the roof. The ventilation system must be designed to maintain the room temperature within the range of 9 °C to 45°C at different points in the room. Since the engine combustion air will be drawn from inside the engine hall, the ventilation system must provide the required volumes of combustion air at all times, along with the necessary ventilation. The CFD analysis conducted in this study provides the groundwork for designing an effective ventilation system that can maintain optimal temperature conditions in the engine room. Using the simulation results, the ventilation system will be optimized to ensure the required temperature is maintained while also preventing the formation of explosive atmospheres.iiAlso, the simulation study presented in this report showcases the ability of CFD simulations to predict airflow and temperature fields in the engine room of a power plant. It is essential to understand the different scenarios' conditions to design a reliable and efficient engine room system. Furthermore, CFD simulations have proven to be an effective tool for optimizing HVAC installations to meet specific building requirements even before installing any equipment. CFD takes into account all factors influencing airflow and temperature, ensuring finely tuned designs even in confined spaces.To accurately analyse and simulate the environment, a 3D model of the engine and room is created using Inventor and AutoCAD software. However, for complex systems like the engine room, simplifying the geometry is necessary when preparing a CFD model. This is because including every detail can result in an excessive number of mesh elements, leading to longer simulation times and higher computational costs. Therefore, striking a balance between geometric complexity and computational efficiency is important for an optimal CFD model. By creating a simplified model, the CFD simulation can be more computationally efficient while still accurately capturing important flow features. The 3D model allows for seamless integration with the CFD software, enabling accurate representation of the environment for analysis.The study conducted simulations for a high-power diesel & gas engine room under four different scenarios, covering various seasonal and load conditions. The results indicated that a heating coil with a 250 kW capacity is required to preheat the airflow of 25.5 m³/s by 8 °C to maintain the required temperature above 9 °C during winter. Similarly, during summer, fans with an airflow rate of 60 m³/s are necessary to keep the engine room temperature below 45 °C. This analysis is critical for designing an optimal ventilation system in engine rooms, ensuring sufficient airflow and maintaining appropriate engine temperature to prevent engine start failure. The simulation results provide invaluable information for HVAC engineers to design an efficient and reliable engine room system.Through the utilization of CFD simulations, engineers can simulate and analyse the performance of the HVAC system under various conditions, providing them with the necessary information to make well-informed decisions to ensure that the system meets the required performance criteria. Implementing CFD in the early stages of HVAC design provides valuable insights, saving engineers time and money associated with real-life testing and validation. By leveraging CFD simulations, engineers can virtually test and evaluate multiple design alternatives, ventilation strategies, and system configurations prior to actual implementation. This proactive approach helps engineers pinpoint potential issues, optimize system design for enhanced efficiency and effectiveness, and minimize the need for expensive post-installation modifications and adjustments.

The deployment of distributed photovoltaic (PV) is accelerating worldwide. Understanding when and where PV systems will generate electricity is valuable as it affects the power balance in the grids. One way of obtaining this information is simulating the PV power production of systems detected in Remotely Sensed Data (RSD). The use of aerial imagery and machine learning models has proven effective for identifying solar energy facilities. In a Swedish research project, a Convolutional Neural Network (CNN) could identify 95% of all PV systems within a municipality. Furthermore, using Light Detection and Ranging (LiDAR) data, the orientation and area of detected PV systems can be estimated. Combining this information, with local weather and irradiance data, the historic PV power generation can be simulated. The purpose of this study is to adapt and validate a model for simulating historic decentralized PV electricity generation, based on an optimization tool developed by Becquerel Sweden, and further develop the model to simulate aggregated electricity generation on a municipality level where the individual orientation of each PV system is taken into account. The model has a temporal resolution of 1 hour and a spatial resolution of 2.5×2.5 km.  A regression analysis demonstrated that the simulated generation corresponds well to the measured generation of 7 reference systems, with coefficients of determination ranging from 0.69–0.84. However, the model tends to overestimate the production compared to the measured values, with a higher total simulated production and positive mean bias errors. The correlation of the measured and generated PV power was similar, when simulating using orientations provided by the reference facility owners and LiDAR approximated orientations. Generic module parameters and an average DC/AC ratio were derived in this study, enabling simulation on a municipal level. Due to available RSD, Knivsta Municipality was the object for this study. The aggregated PV electricity generation was simulated for 2022, using both an estimation of optimal conditions and an estimation of real conditions. This was compared to the assumption that all installed AC capacity in the municipality is fed to the grid. The results show that during the highest production hour, the electricity generation resulting from estimated optimal conditions, exceeds the total installed AC capacity, while the simulation using approximated real conditions never reach the total installed AC capacity. However, the average hourly production for both scenarios, never exceeds 45% of the total installed AC capacity.

Transportation is embedded in the fabric of society and a key enabler of socio-economic development, but it is also a major source of carbon dioxide (CO2) and local air pollution (AP). Cities collectively account for around three quarters of total energy-related CO2 emissions, and the negative health impacts from local APs are most felt in dense urban environments. Thus, transitioning away from current fossil fuel regime in urban transportation is necessary to address both global and local challenges. Mathematical models as energy system optimisation models (ESOMs) are commonly applied to explore contrasting energy futures and to provide insights on how the energy system (or specific sub-sectors) may evolve under different conditions. However, ‘typical’ national level models are not fully adapted to capture the characteristics of local (city) transportation, and previous city-level ESOM based analyses have focused on decarbonisation of local energy systems, thus omitting other local policy considerations as e.g. air quality, and several studies excluded transportation altogether.  In this thesis, a generic city-level ESOM framework (TIMES-City) was further adapted and used to provide policy-relevant insights on the anticipated energy transition of the local transport sector. The underlying work rests on a systems analysis approach, building on careful consideration of the overall system performance and boundaries, understanding of specific system characteristics, and challenges and opportunities facing local ‘system managers’; this has implications for model representation and for quantitative and qualitative modelling assumptions. Further, availability and quality of local transport, energy and emission data needed to calibrate models poses significant challenges, and considerable effort was also put on producing projections for future transport demand (a key model input), using lessons and input data from traditional transport demand models. These considerations were addressed in Paper I.  The model was then applied to two different cases (in Sweden) to explore potential conflicts and co-benefits between ambitious climate targets and deep cuts in APs (Paper II), and to assess the roles of local and regional governments in CO2 mitigation when also considering ambitious national-scale policies (Paper III). The results of Paper II indicate that substituting fossil fuels for biofuels in conventional vehicles is the least-cost decarbonisation pathway, however this produces only minor or even negative benefits to air quality. While, zero-emission vehicles cut all local tail-pipe emissions, but their total impact on climate change mitigation is determined by upstream impacts from the conversion and distribution of energy carriers. Thus, ensuring low levels of total CO2 and APs from transportation calls for re-coupling of the local and global responsibilities and motivations into comprehensive mitigation strategies. The results of Paper III indicate that current Swedish national mitigation measures will drive down CO2 emissions in transportation considerably, but biofuel availability and BEV (battery electric vehicles) costs are critical for the rate and extent of the transition, while locally and regionally determined measures to enable shifts (from car) to active travelling, public transportation and home-based work have a much more limited direct impact. Nonetheless, these measures, along with city investments in BEVs and charging infrastructure which pave the way also for residents and local businesses, can help to reduce overall energy intensity of the transport sector, thus slowing down growth in fuel demand and contribute to reaching ambitious climate targets with limited renewable resources (as e.g. biofuels). The two studies (Papers II and III) illustrate the usefulness of applying comprehensive ESOMs also at sub-national levels, providing insights on both global and local sustainability implications as well as deeper understanding of the roles of local and regional decision-makers in enabling and supporting low-carbon transitions in transportation.

Sewage sludge is a by-product of wastewater treatment that simultaneously gathers contaminants, valuable organic matter, and nutrients. The treatment of the increasing amount of sewage sludge is important from both pollution prevention and resource recovery perspectives as i) large shares of mineral phosphorus, listed as a critical raw material, terminate in the sewage sludge, and ii) energy recovery from sewage sludge can cover the energy-intensive demand of the treatment process. Previous research has identified sewage sludge combustion as a suitable treatment approach as it both addresses contaminant destruction and paves the way for efficient phosphorus recovery from the sewage sludge ash. The commercial development of this practice has, however, been slow. Therefore, this thesis aims to investigate the challenges in sustainable sewage sludge management, and to, in more detail, identify the economic viability of energy and phosphorus recovery from sewage sludge through combustion. The thesis’ aim is divided into two objectives addressed in three papers. First, to investigate how different aspects of sewage sludge management, such as contaminants, economic efficiency, technical aspects, and legislation, evolve and interact. This has been done by a review of sewage sludge management research over fifty years (Paper I). Second, to investigate the economic viability of simultaneous energy and phosphorus recovery from sewage sludge by comparing different technology and market scenarios. This has been done for i) new sewage sludge mono-/co-combustion plants (Paper II), and ii) the integration of treatment technologies, mainly anaerobic digestion, hydrothermal carbonization, and combustion, in an existing wastewater treatment plant (Paper III).  Results from the analysis of sewage sludge management research (Paper I) show a narrow-focused perspective that often excludes inseparable aspects such as combination of economic consideration and advanced extraction technology. The investment viability of a new mono-/co-combustion of sewage sludge (Paper II) is highly conditional on heat, electricity, and fertilizer price, and external financial support is often a crucial requirement. Sewage sludge co-combustion with potassium-rich biomasses improves sewage sludge quality and forms usable ash as fertilizer without further need for phosphorus recovery technology. In this case, the economic feasibility of the process is independent of usable ash revenue, which stimulates a competitive selling price for the ash, thereby improving the marketing of sludge-based fertilizer. Avoided disposal costs of sewage sludge for a retrofitted wastewater treatment plant by introducing hydrothermal carbonization (Paper III) shows good economic feasibility while recovering phosphorus. Integrating anaerobic digestion, hydrothermal carbonization, and combustion may also improve investment incentives by improving energy outputs and phosphorus recovery. The economic feasibility is contingent on product (hydrochar, heat, electricity) prices and sensitive to added equipment costs, and costs for sludge transportation and disposal.

En studie har genomförts för att undersöka möjligheterna att torka gjutsand i en fluidiserad bädd. Sand är ett ändligt material och i gjutprocessen används tonvis gjutsand årligen. Volvo Powertrain Production har ett gjuteri i Skövde där de undersöker om de kan återanvända sin gjutsand. För att återanvända gjutsanden måste den först tvättas ren från föroreningar för att sedan torkas innan den kan användas i processen igen. Gjuteriet har stora mängder restvärme som skulle kunna utnyttjas till torkningen av gjuterisand. Studien genomförs för att öka kunskapen om torkning av gjutsand i en fluidiserad bädd vid olika gastemperaturer och flöden.  Målet är att analysera gjutsandens fluidiseringsegenskaper och att beräkna vilken temperatur och vilket luftflöde som genererar lägst energibehov vid torkning. Gjutsanden ska torkas från en fukthalt på 12 % till en fukthalt på 0,1 %. Gjutsandens slitage mäts för att säkerställa att medelkornstorleken inte underskrider 150 µm och att finandelar under 63 µm inte överskrider 1 % av den totala massan. Målet är även att projektera en tork som kan torka 10 000 ton gjutsand/år samt att beräkna den miljömässiga förbättringen som genereras av att återvinna gjutsanden i CO2-ekv.  Resultatet för studien visar att torr gjutsand fluidiserar vid en hastighet på 0,09 m/s. Studien visar också att fluidiseringen av gjutsand inte har ett betydande slitage på sangkornens storlek. Sandens slitagegrad är viktig eftersom sanden vill kunna återanvändas många gånger och resultatet tyder på att fluidisering är en skonsam process. Torkning av 10 000 ton gjutsand/år kräver en tork på 22,2 m3. Torkens storlek ses som rimlig och för att få en kontinuerlig torkning kan en fluidiserad bandtork användas.  Resultatet visar att för att torka så energieffektivt som möjligt bör det ingående volymflödet på luften vara 0,028 m3/s. Ingående lufttemperatur bör vara 100 °C när sandbädden är fast och 45°C när gjutsanden är fluidiserad. Gjuteriet genererar stora mängder restvärme och procesströmmar upp till 100 °C kan ses som obegränsad. Det betyder att restvärme kan användas för att torka gjutsanden. Resultatet för de miljömässiga beräkningarna visar att 226 till 244 ton CO2-ekv kan reduceras genom att återvinna 10 000 ton gjutsand per år. Torkningseffekten är mycket låg och det kan vara ett problem om restvärmetillgången minskar. För att nyttja en större del av den tillförda energin kanett recirkulerande flöde användas. I dagens process ses dock inte det som nödvändigt eftersom energin är obegränsad och inte nyttjas till andra ändamål. / 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.

Ett hållbart samhälle behöver ha en klimatvänlig snöröjning. Den traditionella snöröjningen är associerad med en del problem, exempelvis bidrar saltspridning till ökad korrosion av vägar och fordon, förorening av både ytvatten och grundvatten samt ökad mobilitet av tungmetaller. Ett hållbart alternativ är hydronisk markvärme, även kallat Hydronic Asphalt Pavement, HAP. Snösmältning med ett HAP-system sker genom att en varm fluid cirkulerar i rör under ytan som ska hållas snöfri. HAP- systemets energianvändning och snösmältningskapacitet är beroende av hur de värmande rören är placerade samt vilket styrsystem som används. Rapporten syftar till att öka förståelsen för hur styrsystemet och geometrin påverkar HAP-systemets energianvändning och snösmältningstid. En numerisk 2D-modell konstrueras i COMSOL Multiphysics vilken användes för att simulera styrsystemets och geometrins påverkan på HAP-systemet. Snön förenklades som en värmesänka till vilken modellen överförde värme via ett värmeflöde. En avgränsning i rapporten var att det bortsågs från vatten på ytan för att förenkla modellen. Resultatet bekräftar att HAP-systemets styrsystem och geometri har stor påverkan på dess energianvändning och snösmältningstid. Generellt ger en hög energianvändning kortare tid med snö på ytan. Det gör att om det är önskvärt att ha ett energisnålt system behöver en avvägning mellan energianvändning och tid med snö på ytan göras. Ett intermittent styrsystem bedöms vara ett bra alternativ då det ger relativt låg energianvändning och kort tid med snö på ytan. Om det inte finns en begränsning i energianvändning finns det flera styrsystem som kan ge en snöfri yta hela året. Ytans temperatur är den bästa styrparametern att använda för att minska både energianvändning och snösmältningstid. Då värmerören placeras grundare ökar energibehovet och tiden med snö på ytan minskar. Det är möjligt att placera värmerören djupare med bibehållen snöfri tid på ytan om styrsystemet anpassas efter djupet. En viktig anpassning är att styrsystemet ger en förvärmningseffekt, exempelvis att vägen börjar värmas då vägytans temperatur understiger 1°C. En ökning av avståndet mellan värmerören, CCrör, minskar energibehovet och tiden med snö på ytan ökar. Det bedöms vara möjligt att öka CCrör till 350 mm utan att generera för stora skillnader i temperaturprofilen över ytan då rördjupet är 100 mm eller 160 mm. Det styrsystem som gynnas mest av att öka CCrör till 350 mm är ”Grundfall”, vilken värmer vägen under hela vinterhalvåret. Energianvändningen minskar då med 132 kWh/m2 (22,9%) och den längsta ihållande tiden med snö på ytan ökar från 0 h till 4 h. Beroende på vad kraven på ytan är kan det vara möjligt att ha 350 mm som CCrör för de andra styrsystemen. HAP-systemet blir resurseffektivare och billigare vid konstruktion ju större CCrör som används, vilket är önskvärt. Resultatet visar att det är en liten minskning i energianvändning och snösmältningstid då isolering är under värmerören jämfört med ingen isolering. Detbedöms därför vara omotiverat ur både energisynpunkt och snösmältningsmässigt att använda isolering under värmerören på det sätt som undersökts i detta arbete. Det är en markant skillnad i energianvändning mellan ett styrsystem som är enklare och ett som är mer komplext. Om styrsystemet ”Intermittent” används i stället för ”Grundfall” vid Hamngatan i Karlstad skulle det generera en minskad energianvändning av 4,37 GWh fjärrvärme (58,5%), vilket motsvarar 199 ton CO2 per år. Resultatet understryker vikten att ett optimalt styrsystem används. Även en liten skillnad i energianvändning kan ge stora energimässiga besparingar eftersom det ofta är stora ytor som värms med ett HAP-system. För att kunna avgöra vilket styrsystem som är bäst lämpat behöver kraven på ytan bestämmas, vilket inte görs i arbetet, utan resultaten hålls generella. / A sustainable society need to have a climate friendly snow removal system. The traditional snow removal systems generate some problems, for example increased corrosion of roads and vehicles, contamination of both surface- and ground water and increased mobility of heavy metals. A sustainable alternative is Hydronic Asphalt Pavement, HAP. Snow melting with a HAP-system is generated by circulating a warm fluid in pipes underneath the surface that is to be snow free. Both the energy usage and snow melting time is affected by how the heat pipes are placed and which control system that is used. The report aims to increase the knowledge of how both the control system and geometry of the heating pipes affect the energy use and snow melting time of a HAP-system. A numerical 2D-model was constructed in COMSOL Multiphysics which was used to simulate how the control system and geometry of the heating pipes effects the HAP-system. The snow was simplified to a heat sink, to which the model could transfer heat through a convective heat flux. A demarcation of the study is that water on the surface is ignored to simplify the model. The results confirms that both the control system and geometry of the heat pipes greatly affects the energy usage and snow melting time. In general, a large energy usage generates a shorter total time with snow on the surface. It is therefore needed to do a balancing between energy usage and the total time with snow on the surface if the energy usage is to be restricted. An intermittent control system is considered to be a good alternative as it gives a relative low energy usage and short time with snow on the surface. If there is no limitation on the energy use, there is several control systems that gives a snow free surface throughout the year. The surface temperature is the best parameter for the control system as it minimizes both the energy usage and snow melting time. When the heating pipes is placed shallower the energy usage is increased and the time with snow on the surface decreases. It is possible to place the heating pipes at a greater depth and still have the same functionality of the HAP-system if the control system is adjusted accordingly. One important adjustment for the control system is preheating, for example that the heating is turned on when the air temperature is less than 1°C. An increase of CCrör decrease the energy usage and increase the time with snow on the surface. It is possible to increase CCrör to 350 mm and still have a smooth temperature profile if the heating pipes is placed 100 mm or 160 mm beneath the road surface. The control system that gains the most out of an increase in !!!ö! to 350 mm is “Grundfall”, which reduce its energy usage with 132 kWh/m2 (22,9%) and the longest time with snow on the surface is increased from 0 h to 4 h. Depending on which demands the surface is to meet, it is possible to have 350 mm as CCrör for the other control systems. An increase in CCrör makes the HAP-system more resource efficient and cheaper to build, which is desirable. The results show a small decrease in energy usage and snow melting time when isolation is underneath the heating pipes compared to without isolation. It is therefore deemed to be unmotivated to use isolation as it is used in this paper, in both energy use- and snow melting time-perspective. There is a significant difference in energy use between a simple and more complex control system. If the control system “Intermittent” is used instead of “Grundfall” at Hamngatan in Karlstad the energy usage would decrease with 4,37 GWh heat (58,5%) and 199 ton of CO2. The result underlines the importance of an optimal control system for a HAP-system. Even a small change in energy consumption can generate large energy savings due to the scale of the surfaces that is heated with HAP-systems. To be able to decide which control system that is the best suited, the demand on the surface needs to be set. The demands are not set in this paper in order to keep the results general.

Wireless technology is used daily across the globe. A very common wireless technology is Bluetooth. The Bluetooth technology exists everywhere, from cars to mobile phones and even kitchen appliances. Recently, Bluetooth Low Energy has added support for another physical layer, LE 2M PHY. This physical layer is supposed to be faster and more energy efficient than its predecessor, LE 1M PHY, with a decrease in range. Because of this new physical layer, Bluetooth Low Energy can now compete with Bluetooth Classic during data transmission, in both speed and energy efficiency. This thesis aims to find the breaking point where Bluetooth Low Energy becomes less energy efficient than Bluetooth Classic, in relation to bit rate speed and total amount of bytes sent. Before experiments were conducted, multiple iterations of an artifact had to be done to end up with an artifact that provides valid and reliable data. The experiments were then conducted by changing the bit rate speed and sending different amounts of bytes. The results from the experiments show that Bluetooth Classic is practically both faster and more energy efficient with its fastest modulation than Bluetooth Low Energy is with LE 2M PHY enabled, even though this should not be the case theoretically. Bluetooth Classic is overall more energy efficient than Bluetooth Low Energy and thus the conclusion of this study is that no breaking points between the two technologies exist.