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  • 51. Chen, X.
    et al.
    Su, Y.
    Aydin, D.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ding, Y.
    Reay, D.
    Law, R.
    Riffat, S.
    Experimental investigations of polymer hollow fibre integrated evaporative cooling system with the fibre bundles in a spindle shape2017In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 154, p. 166-174Article in journal (Refereed)
    Abstract [en]

    Due to the advantages of light weight, corrosion resistant and low cost, hollow fibres have been studied as the substitute for metallic materials. A novel hollow fibre integrated evaporative cooling system, in which the hollow fibre module constitutes as the humidifier and the evaporative cooler, is proposed. This novel hollow fibre integrated evaporative cooling system will provide a comfortable indoor environment for hot and dry area. Moreover, the water vapour can permeate through the hollow fibre effectively, and the liquid water droplets will be prevented from mixing with the processed air. In order to avoid the flow channelling or shielding of adjacent fibres, the fibres inside each bundle were made into a spindle shape to allow maximum contact between the air stream and the fibre. The cooling performances of the proposed novel polymer hollow fibre integrated evaporative cooling system were experimentally investigated under the incoming air temperature in the range of 26 °C to 32 °C and relative humidity of 25%–35%. The effects of air velocities on the cooling effectiveness, heat and mass transfer coefficients, specific water consumption and pressure drop across the polymer hollow fibre module were analysed. Two sets of experimentally derived non-dimensional heat and mass transfer correlations were summarized, which could be favourable for the future design of polymer hollow fibre integrated evaporative cooling system.

  • 52.
    Cubillas Camou, Elsa
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Performance Analysis on Photovoltaic Plant in Norway2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to analyze the performance of the biggest PV system located in Oslo, Norway. The PV system has a capacity of 130 kW, it started operations in 2014 and it is located on the rooftop of a nursing house managed by the municipality. The analysis was done by making four different comparisons that lead to have a more detailed overview. The comparisons were from the energy production from different years, months and days; the performance ratio from different subsystems; the modeled energy output vs the actual energy output and lastly a relative degradation from different subsystems.

    The thesis was conducted in Kjeller, Norway at the Institute for Energy Technology facilities. Data was collected from two different monitoring systems, the first was from an onsite weather station and the second was from the energy production monitoring system. After collecting all the data, the production comparison from different years, days and months was performed. A performance ratio analysis was done in order to know how well the PV system was performing. The software HelioScope was used to simulate a model of the PV system and the results of the simulation were compared to the real energy output. A degradation analysis without irradiance data proposed by the National Renewable Energy Laboratory was implemented to compare the degradation rate between different subsystems.

    The production analysis comparison within subsystems demonstrates that some identical subsystems produce more energy than others. For the performance ratio analysis, the results showed that the PV system has a good performance ratio despite of the shading some PV modules receive. The simulation of the model in HelioScope showed some discrepancies for the winter months while for summer months it was more accurate. Finally, the degradation analysis was not possible to demonstrate actual results, but the methodology was implemented.

  • 53.
    Córdoba Candela, Jose
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Prefeasibility Study of a Central Solar Heating Plant with Seasonal Storage in Astana2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The feasibility of a Central solar heating plant with seasonal storage (CSHPSS) in a new district in Astana was evaluated. A total usable footprint of 481271 m2 of low energy (passivhaus standards) multi storey apartment blocks and single family houses (15000 expected inhabitants) was studied.

    Astana is a very cold climate, with heating degree days (below 18 °C) of 5724 °C.day/year. However the solar radiation is higher than in northern Europe (where most CSHPSS are located). Space heating demand, using passivhaus standards, would be 7.2 GWh/y, DHW demand calculated was 11 GWh/y and transmission losses 2.41 GWh/y.

    Astana’s DH network was studied in order to analyze the integration of this solar thermal system within the city network. Nevertheless due to its typology (open system) and its temperature regime a newly built DH within the existing network is chosen, a secondary 60/30 °C network is considered to be appropriate. Previous plants and technologies used in central plants were reviewed in order to select the most appropriate ones.

    In the simulation, collector areas between 1.4 and 2.5 m2 per MWh heat demand and water storage volumes between 1.2 and 4.0 m3 per m2 collector area satisfy between 41 and 81 per cent of the total heat demand by solar thermal heat. Levelized cost of energy (LCOE) increases from 0.099 €/kWh to 0.107 €/KWh when increasing the solar fraction. Two systems were selected as optimum (from LCOE point of view) that gave solar fractions of at least 50 % and 80 %.

    In order to calculate feed-in tariff, Net Present Value (NPV) and Payback Time (PBT), local economic figures were chosen considering different financial considerations resulting in a discount rate of 12% and inflation of 7%. Since the heat tariff for solar thermal is not defined by law, this tariff was calculated for an expected internal rate of return of 28%. For SF=50% the investment would have a feed-in tariff of 0.184 €/kWh, a PBT=8.2 years and NPV=9.92 M€. For SF=80% the investment would have a feed-in tariff of 0.191 €/kWh, a PBT=7.75 years and NPV=16.7 M€.

  • 54.
    d’ Souza, David
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Experimental Characterisation and Modelling of a Membrane Distillation Module Coupled to aFlat Plate Solar Collector Field2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An experimental characterisation of a pre-commercial spiral wound permeate gap membrane distillation module was carried out to test its performance at different operating conditions for the purpose of seawater desalination. The experimental setup consisted of a flat plate solar collector field indirectly coupled to the permeate gap membrane distillation module via an inertia tank. The operating parameters varied were the condenser inlet temperature (from 20 °C to 30 °C), evaporator inlet temperature (from 60 °C to 80 °C) and seawater feed flow rate (from 200 l/h to 400 l/h). Within this operational boundary, it was found that the maximum permeate/distillate flux was 4.135 l/(h∙m2) which equates to a distillate production/flow rate of close to 21.3 l/h. The maximum potential distillate production rate is expected to be significantly higher than this value though as the maximum manufacturer specified feed flow rate is 700 l/h and the maximum evaporator inlet temperature is rated at 90 °C. Both these parameters are positively related to the distillate production rate. The minimum specific thermal energy consumption was found to be 180 kWh/m3.

    A mathematical model of the overall system was developed, and experimentally validated, to mathematically describe the coupling of the membrane distillation module with a solar collector field. The effectiveness of internal heat recovery of the membrane distillation module was found to be an accurate and simple tool to evaluate the thermal energy demand of the distillation process at a given set of operation parameters. The mathematical model was used to further investigate the experimental findings and provide insights into the operational dynamics of the membrane distillation module. It was also used to determine some external conditions required for steady state operation, at a given distillation operating point, such as the minimum solar irradiation required for operation and the auxiliary cooling required in the solar collector loop for maintaining steady state conditions.

    Finally, general guidelines are provided toward better operational practices to improve the coupling of a solar thermal collector unit/field with a membrane distillation system using a storage tank or inertia tank.

     

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  • 55.
    Dahlblom, Linus
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Utveckling av infästningsplattor för montering av solpaneler på tätskiktstak2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Solar panels are becoming more and more common. Unfortunately, there are currently no solutions adapted to secure the panels on membrane roofs. Instead, they are attached with methods that are meant for personal safety, which are oversized for the purpose. In this work a mounting plate that is adequately sized for mounting solar panels is developed. This is done using a product development process that is designed to define the loads on the panels and from there develop a solution which is shaped and sized for the purpose. The result is a product that withstands the loads with a good margin to a considerably lower price than the original solutions.

  • 56.
    Dalenbäck, Jan-Olov
    et al.
    Svensk Solenergi.
    Ollas, Patrik
    SP Energiteknik.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Biobränsle och solvärme för 100% förnybar värmeförsörjning: Projekt nr 30688-2 - Biobränsle och solvärme2015Report (Other academic)
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  • 57.
    Daniels, Maria
    Dalarna University, School of Technology and Business Studies, Occupational science. Dalarna University, School of Health and Social Studies.
    Inspirationsbenchmarking för förbättrad verksamhet för ABB Components i Ludvika2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
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  • 58.
    Daroudi, Parham
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Simulation of an energy efficient single-family house in the area of Smedjebacken to meet Miljöbyggnad’s Gold House energy category requirements2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since the building construction area is accounted for high share of energy usage (36 %) in

    Europe, there is high demand to pay attention to this area accurately. Sweden which is one

    of the pioneer countries in terms of building energy efficiency plans to reduce this value to

    50 % by 2050. To reduce this value there is a need to define a mandatory guideline for

    builders by the government. So national board of housing, building and planning (Boverket)

    were given responsibility to define these regulations for builders and house owners. Parallel

    with that Swedish green building council developed a certification considering the buildin

    g’s

    energy demand, indoor air climate and environmental impact of building called

    Miljöbyggnad. While all the existing and new buildings following Boverket’s regulations

    meet this certification’s lowest limitations, some ambitious

    builders tend to fulfil its highest

    level of limitations called Gold level.

    This study aimed to design a house in the area of Smedjebacken to meet Miljö

    byggnad’s

    gold house’s energy category requirements. To meet the mentioned requirements several

    parametric studies regarding insulation thickness, windows assembly, heating and ventilation

    system are done via simulation software called TRNSYS. The result of testing several

    models show that although windows assembly does not affect this building

    ’s energy demand

    very much, other parameters such as insulation

    ’s thickness and type of heating system have

    a key role.

    In addition, a parametric study regarding the impact of thermal mass on the building energy

    demand is performed. The result shows that the effect of removed massive wood is

    compensated by replaced additional mineral wool insulation.

    In conclusion it is concluded that a single family house located in a cold climate like

    Smedjebacken using

    district heating cannot meet Miljöbyggnad’s gold level criteria without

    help of heat recovery ventilation. Furthermore, building with ground source heat pump as

    its

    heating system can meet Miljöbyggnad’s principals easier than those having district

    heating. In this case building with 200 mm insulation thickness even with exhaust air

    ventilation meets certification principals easily.

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  • 59.
    Darth, David
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Värmehantering - Datorstödd dimensionering av kapsling för batteriladdare2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis-work, the possibility of integrating a heat sink in the encapsulation of a batterycharger has been investigated. To manage the thermal load, a plate-finned heat sink has been dimensioned. Two design concepts have been developed, with two different heat sinks integrated in the design. The concepts thermal performance has been simulated in Solidworks Flow Simulation to identify surface-temperatures, component-cooling, flow conditions and radiation. The results from the calculations and the simulations shows that both of the concepts, at an ambient temperature of 30ᵒC, performs a sufficient heat flux to keep the internal components under 93ᵒC. The battery-charger’s encapsulation temperature would not exceed 54ᵒC under these conditions. For further development, a concept with the heat sink covered by a “lid” has been recommended.

  • 60.
    de Fatima Dias, Jane
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Reuse of Construction Materials2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The building and construction sectors are one of the main contributors to the socio-economic development of a country. Globally, these sectors generate around 5% to 10% of national employment and around 5% to 15% of a country's gross domestic product during construction, use and demolition. On the other hand, the sectors consume around 40% of world primary energy, use 30% of raw materials, generate 25% of solid waste, consume 25% of water, and use 12% of land. Furthermore, the sectors account for up to 40% of greenhouse gas (GHG) emissions, mainly from energy use during the life cycle of buildings.

    This study aims to assess the potential environmental benefits of reusing concrete and ceramic roof tile within the Swedish context in terms of their CO2 emission. Methodology used was a comparative LCA was to quantify the emissions. In order to calculate LCA, OpenLCA 1.7.0 software was used and to evaluate the emissions, LCIA method selected was ReCiPe, midpoint, Hierarchist model, climate change category expressed in GWP 100 years (in kg CO2eq). The FU of the study was a square meter of roof covering for a period of 40 years with potential to extent up to 80 years. A square meter of concrete roof tile weight 40 kg while ceramic 30 kg.

    The environment impact evaluation considered three product system, single use (cradle to grave), single use covering (cradle to user) and single reuse (user to cradle) within 40 years lifespan. In order to compare LCA of the roof tiles, two scenarios were created, Scenario 1 concrete RT in single use and single reuse whilst Scenario 2 evaluates ceramic RT. The outcomes of both scenarios were communicated through a model single family house. Dalarna’s Villa is located in Dalarna region in Sweden and a storage facility Ta Till Våra was to validate the benefits of reused materials.

    Comparative LCA revealed that concrete RT in single use released almost 80% more CO2 emissions than ceramic RT and generated 25% more disposable material by weight. The CO2 released by the single use vs. single reuse concrete RT showed higher emissions in the production of the concrete RT than the single reuse, the same occur with ceramic RT. The reuse of the tiles on the same site had an insignificant impact on the environment in both materials. The comparison shows that reuse reduces associated emissions by about 80% in both cases, reusing concrete is more beneficial, as emissions are reduced by 9.95 kg/m2 as opposed to 2.32 kg/m2 at the ceramics. This study reveals the benefit of reusing concrete and ceramic roof tile. In addition, the advantage of building a storage facility to reuse the disposable building materials, reducing the roofing materials ending at the landfill after 40 years. Furthermore, it demonstrated the reduction of CO2 emissions associated with the embodied energy.

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  • 61. Dermentzis, G.
    et al.
    Ochs, F.
    Gustafsson, M.
    Calabrese, T.
    Siegele, D.
    Feist, W.
    Dipasquale, C.
    Fedrizzi, R.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A comprehensive evaluation of a monthly-based energy auditing tool through dynamic simulations, and monitoring in a renovation case study2019In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 183, p. 713-726Article in journal (Refereed)
    Abstract [en]

    An energy auditing tool (PHPP) was evaluated against a dynamic simulation tool (TRNSYS) and used for the assessment of energy conservation measures in a demo case study. The comprehensive comparison of useful heating and cooling demands and loads included three building types (single-, multi-family house, and office), three building energy levels (before renovation and after renovation with a heating demand of 45 and 25 kWh/(m²·a)) and seven European climates. Dynamic simulation results proved PHPP (monthly energy balance) to be able to calculate heating demand and energy savings with good precision and cooling demand with acceptable precision compared to detailed numerical models (TRNSYS). The average deviation between the tools was 8% for heating and 15% for cooling (considering climates with a relevant cooling load only). The higher the thermal envelope quality was, i.e. in case of good energy standards and in cold climates, the better was the agreement. Furthermore, it was confirmed that PHPP slightly overestimates the heating and cooling loads by intention for system design. The renovation design of a real multi-family house was executed using PHPP as energy auditing tool. Several calculation stages were performed for (a) baseline, (b) design phase, and (c) verification with monitoring in order to calculate the corresponding heating demand. The PHPP model was calibrated twice, before and after the renovation. The necessity for tool calibration, especially for the baseline, was highlighted increasing the confidence with respect to a number of boundary conditions. In this study, PHPP was tested as an energy auditing tool aiming to be a versatile and less error-prone alternative to more complex simulation tools, which require much more expert knowledge and training. 

  • 62.
    Dimtsu Tamene, Hailu
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Solar Mini-grid Model Validation for Rural Electrification2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis was aimed at validating an Excel tool developed by Energicity Company. In addition, to study a commercial software that can be used to design a solar mini-grid system for the company.

    A 9.9 kW solar mini-grid in Bekwai, Ghana was used as a case study. Weather data from Meteonorm and component specification was used as input parameter for the simulation works.

    HOMER pro and PVsyst commercial software were selected to validate the Excel tool. Each software was also explained in detail.

    The validation was done by comparing input parameters and simulation results of the Excel tool with the selected commercial software. The process was divided into two main parts. The first part was, comparing the mathematical model, and the PV array electricity production of the software used as an input to the Excel tool, which was SAM, with HOMER pro and PVsyst. The second part was comparing the final simulation result of both tools, including the Excel tool.

    The comparison result shows that the difference in the mathematical model for the diffuse irradiation in each software leads to a difference in the electricity production at the PV array output. Even though the difference is not significant for a small scale mini-grid system, the difference can cause a wrong estimation for critical loads, where a higher percentage of availability is required.

    The DC losses at the PV array has a notable impact on estimating the electricity production. PVsyst considers more loss parameters than SAM and HOMER pro. As a result, the simulation result of the PVsyst shows lower electricity production at the output of the PV array compared to the others. This indicates as PVsyst is a more conservative software model.

    The loss in the battery has another significant impact on estimating the energy delivered to the load. The battery model for each tool was different. The Excel tool uses higher battery loss percentage. Due to this, the energy served to the load by the Excel tool was lower than HOMER pro and SAM. HOMER pro’s estimation of the battery loss was almost equal to the Excel tool. The battery loss estimated by PVsyst was lower than all models. However, there were uncertainties in the input parameters of the battery, because of most of the parameters provided by the battery manufacturer was not compatible with the input parameters required by PVsyst.

  • 63. Dipasquale, Chiara
    et al.
    Fedrizzi, Roberto
    Bellini, Alessandro
    Gustafsson, Marcus
    Ochs, Fabian
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Database of energy, environmental and economic indicators of renovation packages for European residential buildings2019In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 203, article id 109427Article in journal (Refereed)
    Abstract [en]

    Increasing the energy efficiency with a vast impact in the residential building stock requires retrofit solutions that can be exploited with respect to a wide range of different building typologies and climates. Several tools and methodologies are nowadays available both for the assessment of building demands and for the individuation of optimum retrofit solutions. However, they are usually either too complex to be adopted by professionals or, on the contrary, oversimplified to account for the full complexity of a deep envelope and HVAC system retrofit. In this context, this paper describes a methodology developed to generate reliable information on retrofit solutions for typical buildings in different climatic conditions. Detailed numerical models are used to simulate a number of combinations of envelope and HVAC systems retrofit measures and renewable energy integration. Energy performance results are gathered in a database that allows comparing solutions, spanning over a range of more than 250,000 combinations of building types, age of construction, climates, envelope performance levels and HVAC systems configurations. Economic feasibility is also derived for each of the combinations. In this way, the accurateness of a detailed and validated calculation is made available to assist during the decision making process, with minimum computational effort being required by professionals: the variety and density of evaluated combinations allows to easily assess the performance of a specific case by interpolating among instances previously assessed. The applicability of the results to different climates and similar building typologies is verified by a comparison of the database results with a specific case dynamic simulation.

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  • 64.
    Diyad Elmi, Mohamed
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Manoharan, Lavaraj
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Optimal Grid Connected Inverter Sizing for Different Climatic Zones2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Grid connected inverter requires accurate and appropriate sizing which depends on the temperature, inverter operating efficiency, performance ratio, annual system yield and solar radiation characteristics. The aim of this study was to design and size for optimum sizing factor for grid connected inverter. The main component to be considered in any photovoltaic grid connected system is the inverter since the output depends on the inverter sizing ratio, therefore optimal sizing factor was designed by considering factors that affects inverter sizing such as temperature, irradiance and the location. Large and small systems of 50 kW and 5 kW respectively were considered to determine grid connected inverter sizing factors for different climates in Kenya, Sweden, and India using PVsyst simulation. Two different inverter brands of SMA and ABB with 20 kW and 25 kW rating for large system and 4.6 kW, 4 kW inverters for small system.

    PVsyst simulation result showed that different locations with different orientation angles, the optimum sizing varies hence affects the annual performance of the system. Photovoltaic system inverters are sized based on the rated power of the installed system and this can be achieved when the inverter size is either almost matching or not.

    In this case the study presents the optimal sizing factor for grid connected inverter for Mandera in Kenya, Norrköping in Sweden and Kerala in India. The determination was done through the use of designing, assessing and analyzing of the relationship between the sizing factor with performance ratio, operational efficiency and annual hourly energy yield. The unique weather profile in Kerala and in Mandera favors the adoption of solar energy technology in the location. Solar radiation for one year was used as a baseline input and the result reveals that Mandera receives yearly radiation of 2.1 MWh/m² while Kerala and Norrköping receives 2 MWh/m² and 1.1 MWh/m² respectively.

    Design simulation using PVsyst tool made it possible for the determination of the optimal sizing factor for the grid connected system. Considerations such as the losses and the variations within the specific location was done and a graph showing the relationship between the sizing factor in relation to the operational inverter efficiency as well as energy yield and performance ratio was later on compared to see the behavior of the sizing factor.

    The study concludes that operational efficiency, performance ratio and energy yield affects the array optimum sizing ratio. For the three locations, inverters (SMA and ABB) shows different variations because optimal sizing ratio depends on the location and irradiation. The results reveal that Mandera has an optimal grid connected inverter sizing of the range from 1.1 to 1.4 while in Kerala it has from 1.2 to 1.4 and Norrköping has the range from 1.1 to 1.3. Optimal sizing of grid connected inverters depends on the energy yield and the location therefore the inverter mismatch voltage and its rating values have to be considered while determining the optimal sizing factor. The 25 kW inverters in all the locations had better efficiency and sizing factor and this proves that sizing the photovoltaic inverter will give better performance and efficiency.

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  • 65. Duan, Zhiyin
    et al.
    Zhan, Changhong
    Zhang, Xingxing
    De Montfort University.
    Mustafa, Mahmud
    Zhao, Xudong
    Alimohammadisagvand, Behrang
    Hasan, Ala
    Indirect evaporative cooling: Past, present and future potentials2012In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 16, no 9, p. 6823-6850Article in journal (Refereed)
    Abstract [en]

    This paper reported a review based study into the Indirect Evaporative Cooling (IEC) technology, which was undertaken from a variety of aspects including background, history, current status, concept, standardisation, system configuration, operational mode, research and industrialisation, market prospect and barriers, as well as the future focuses on R&D and commercialisation. This review work indicated that the IEC technology has potential to be an alternative to conventional mechanical vapour compression refrigeration systems to take up the air conditioning duty for buildings. Owing to the continuous progress in technology innovation, particularly the M-cycle development and associated heat and mass transfer and material optimisation, the IEC systems have obtained significantly enhanced cooling performance over those the decade ago, with the wet-bulb effectiveness of greater than 90% and energy efficiency ratio (EER) up to 80. Structure of the IEC heat and mass exchanger varied from flat-plate-stack, tube, heat pipe and potentially wave-form. Materials used for making the exchanger elements (plate/tube) included fibre sheet with the single side water proofing, aluminium plate/tube with single side wicked setting (grooved, meshed, toughed etc), and ceramic plate/tube with single side water proofing. Counter-current water flow relevant to the primary air is considered the favourite choice; good distribution of the water stream across the wet surface of the exchanger plate (tube) and adequate (matching up the evaporation) control of the water flow rate are critical to achieving the expected system performance. It was noticed that the IEC devices were always in combined operation with other cooling measures and the commonly available IEC related operational modes are (1) IEC/DEC system; (2) IEC/DEC/mechanical vapour compression system; (3) IEC/desiccant system; (4) IEC/chilled water system; and (5) IEC/heat pipe system. The future potential operational modes may also cover the IEC-inclusive fan coil units, air handle units, cooling towers, solar driven desiccant cycle, and Rankine cycle based power generation system etc. Future works on the IEC technology may focus on (1) heat exchanger structure and material; (2) water flowing, distribution and treatment; (3) incorporation of the IEC components into conventional air conditioning products to enable combined operation between the IEC and other cooling devices; (4) economic, environment and social impacts; (5) standardisation and legislation; (6) public awareness and other dissemination measures; and (7) manufacturing and commercialisation. All above addressed efforts may help increase the market ratio of the IEC to around 20% in the next 20 years, which will lead to significant saving of fossil fuel consumption and cut of carbon emission related to buildings.

  • 66.
    Edlund, Johan
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Utveckling av en variabel oljepump för tävlingsmotorer2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Racing engines often use dry sump lubrication systems in which pumps supply oil to and fromthe engine via an external tank. Dry sump pumps consist of several separate displacement pumpstages that are driven by the crankshaft of the engine, usually via a reduction gearing. Asignificant portion of the power taken from the crankshaft by a dry sump pump is due to thepump stage force feeding the engine with oil from the external tank due to the supply pressurerequired by the engine. So if the power required to drive the pressure stage could be reduced itwould have a large impact on the total power used by the dry sump pump. One way to reduce thepower used by an oil pump is to replace the regular displacement pump with a pump having avariable displacement. Since the oil pump is driven at a speed that is proportional to the speed ofthe crankshaft the pump has to be dimensioned with a high displacement to provide adequate oilflow and pressure at low engine speeds leading to a pump that is oversized at high engine speeds.Normally the excess capacity of the pump at high speed is dealt with by a pressure relief valve,but this does little to reduce the power used by the pump. While variable displacement pumpsare becoming more and more common among production engines having a wet sump none haveso far been used in a dry sump lubrication system for a racing engine. With a racing engine acompact size and low weight are important, particularly when regulations mandate the maximumsize of the pump such as in NASCAR. To fit with NASCAR regulations and it’s 3.5 x 3.5 x 10inch maximum dimensions a variable vane pump using a tilting cam ring to control displacementwas selected as a replacement for the gear pump with pressure relief. While the standaloneprototype met the 3.5 x 3.5 inch requirement, the pump stage was longer and heavier than thegear pump it was supposed to replace.

  • 67.
    Efraimsson, Kim
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Development of foldable center section for train coupler2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To safely convey trains in an urban area, a number of factors must be considered. One of these is that parts pointing out from the cart may cause harm to people or the train’s surroundings. An example of such a part is the train coupler located in the front or back of the cart. To avoid this problem, train couplers with the ability to be folded and hidden behind a hatch on the cart are used. To fold the coupler, a center section with a folding joint and locking mechanism is used.

    The main problem with existing foldable center sections is that over time, a play develops in the joint and locking mechanism as a result of wear damages. The play enables the coupler to move in an undesirable fashion which causes, among other things, the train ride to be unpleasant for passengers.

    The purpose of this project was to develop a new concept for a foldable center section which aims to reduce or eliminate the wear damages and play mentioned above. This report describes the development process, which theories were used, which methods were used and the final result of the project.

    The result of the development project is a concept for a new variant of foldable center section with associated 3D models, overview drawings and a validation plan for a finished prototype. The developed concept differs from existing solutions in many ways. The goal to reduce wear damages and its consequences was achieved with the new concept. However, the result is not optimal. This is discussed in the conclusion of the report.

  • 68.
    Elbana, Karim
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Socio-Technical Analysis for the Off-Grid PV System at Mavuno Girls’ Secondary School in Tanzania2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this study is to investigate, analyse and evaluate the installed off-grid PV system in Mavuno

    girls’ secondary school that is located in a rural area in northwest Tanzania. The original motivation behind this study was the rapid degradation of the installed battery bank within less than 3 years. The PV system was installed before the actual operation of the school, so the study aimed to answer a very pressing question which is "What is the actual load profiles in the school?". There was a high need to identify the actual school load profiles to enable several concerned social actors to evaluate the system and to decide for future extensions. Therefore, the study aimed to analyse the implementation of electricity in the school by creating actual load profiles, analysing the system performance versus the users’ needs and evaluating the sustainability and utilization of implementation.

    The study followed a multi-disciplinary approach combining the social and technical aspects of PV systems implementation

    to seek further understanding of the users’ consumption behaviours. It thus included a 1-month of field work in June 2018 during which participant observations and semi-structured interviews together with load measurements were carried out so as to create load profiles that are considering the patterns and deviations in users’ behaviours. During the field work, 2/3 of the students were in holidays so the taken measurements corresponded to the school at 30 % capacity. That is why the study also included 4 days of inverter data logging after the 1-month field work by the technical head of the school to overcome the limitations in held measurements.

    The observations showed that the actual installed system was slightly different from the documentation. In addition, the local installation practices are not fully appropriate from the technical point of view, and are affected by local social norms, as will be discussed. Besides, the participant observations and held interviews with relevant social actors showed that the daily behaviours of energy users do not exactly follow the school daily routine. Consequently, the social study was important to create actual effective load profiles. The observations and responses from interviews together with measurements were used to categorize the school loads into 29 different units. Those units can be used for current load prioritizations and for future load extrapolations. The created load profiles also represent a useful addition to load databases used by energy researchers who work on similar rural electrification projects.

    After the field work, several characteristics were calculated by Microsoft Excel such as apparent power consumptions, active power consumptions, battery bank state of charge, load power factor and PV generated energy. The characteristics were used in calculations evaluating the energy balance in the system. The results of held calculations showed that lighting during dark hours accounted for on around 78 % of the logged daily apparent energy use, as it has a low a low average power factor of 0.28. It also showed that some loads if time-bounded, they will significantly decrease the daily energy consumption. The calculations were also used to run PVSyst simulations to evaluate the system sizing which resulted in the recommendation that either the array size should be doubled, or the apparent energy consumption should be decreased to half.

    The study included suggestions for possible improvements such as decreasing the reactive consumed energy by either replacing the currently used light bulbs with ones that have higher power factor (

    ≥0.8 for example) or by installing a capacitive compensation for power factor correction. In addition, it was recommended to quantify the school loads according to their priority or importance and to regulate observed time-unbounded loads such as "pumping water" and "ironing". Lastly, the study discussed how generated electricity is utilized in the school and what opportunities for women empowerment have become potentially possible with the provision of electricity.

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  • 69.
    Elemam, Aboubker
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Development of a ESES Solar Thermal Lab on Full Scale System2011Independent thesis Advanced level (degree of Master (One Year)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    The main aim of this project is to develop an ESES lab on a full scale system. The solar combisystem used is available most of the time and is only used twice a year to carry out some technical courses. At the moment, there are no other laboratories about combisystems. The experiments were designed in a way to use the system to the most in order to help the students apply the theoretical knowledge in the solar thermal course as well as make them more familiar with solar systems components. The method adopted to reach this aim is to carry out several test sequences on the system, in order to help formulating at the end some educating experiments. A few tests were carried out at the beginning of the project just for the sake of understanding the system and figuring out if any additional measuring equipment is required. The level of these tests sequences was varying from a simple energy draw off or collector loop controller respond tests to more complicated tests, such as the use of the ‘collector’ heater to simulate the solar collector effect on the system. The tests results were compared and verified with the theoretical data wherever relevant. The results of the experiment about the use of the ‘collector’ heater instead of the collector were positively acceptable. Finally, the Lab guide was developed based on the results of these experiments and also the experience gotten while conducting them. The lab work covers the theories related to solar systems in general and combisystems in particular. 

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  • 70.
    ElSherif, Khaled
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Solar Powered Smart Street Post2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work aimed to develop solar Photovoltaic (PV) powered smart street post. The post was set to serve on highways for wild animals’ detection and warn vehicles of possible crossings. The main aim was to design reliable standalone PV system via PVSyst software and experimenting four different PV technologies including a bifacial module under. Another aim was to select and develop the hardware and software terms of the smart street pot. Radar sensor and analog to digital (A/D) data acquisition (DAQ) card were set to be used for the motion detection. RF wireless communication module was used for communicating with nearby posts to send data and trigger warning light emitting diodes (LED) sign. A Raspberry Pi microcontroller was programmed to control the operation of the street post through processing the signal from radar sensor and communicating with nearby posts.

    The PV system design included generation of street post’s daily profile, sizing and selection of the components of the system including the module, battery, charge controller and power stage circuit. The later was designed to provide suitable voltage level and interface for the loads connected. PVSyst model was built and set to be located in Ulm, Germany. The design parameters were set, and different set of orientations were tested for each module.

    The simulation results showed bifacial module delivered a reliable PV system in case of south and south-east orientation and achieved better performance in other orientations in comparison to the other PV modules implemented. Due to limitations in PVSyst software the results provided had an overall uncertainty of 5%.

    The microcontroller was able to process the data from the radar sensor and DAQ card and perform fast Fourier transform (FFT). However, further processing of motion detection was complex to be included in the thesis work. The radar sensor and DAQ card provided signals with uncertainty of ± 3.4 mV. The RF wireless communication module transmitted signal over various ranges up to 150 m with time delay of 500 ms.

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  • 71.
    Emanuelsson, Simon
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Kartläggning av breddkontraktion och förbättring av breddkontraktionsberäkning2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    At the continuous annealing line at SSAB in Borläge there are problems with sheet width not meeting customer requirements caused by width contraction during the annealing process. Difficulties lies at handling contraction variation and the extent to how the processes is contributing is unclear. Mathematical formula estimates the value of the contraction and preventive witdh is added at earlier process step. Newly installed equipment enable mapping of how diffrent plate dimensions and steels are affected. Investigations show correlation between plate thickness and witdh contraction but clearly influence from high annealing temperatures. Comparison of calculated and actual value for width contraction indicates the necessity of complement to how formula handle sheet thickness. Applying mathematical functions forms a new replacement plate thickness dependent term that raises the calculations within the plate thickness range. Along with factor experiments, the new term reduces differences between calculated and actual width contration for examined sheet, indicating that improvement to the mathematical formula has been achieved.

  • 72.
    Engberg, Göran
    Dalarna University, School of Technology and Business Studies, Materials Technology. Dalarna University, School of Technology and Business Studies, Material Science.
    Constitutive models, physically based models for plasticity2014In: Encyclopedia of Thermal Stresses / [ed] Hetnarski RB, Dordrecht, Heidelberg, New York, London: Springer, 2014, p. 649-662Chapter in book (Refereed)
    Abstract [en]

    Physically based models for the plastic behavior of crystalline, metallic materials are discussed. However, deformation by twinning and phase transformations as well as the evolution of texture are omitted. 

  • 73.
    Engström, Fredrik
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Ökad tillgänglighet i maskiner för skärande bearbetning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this work is to develop principles for an approach that can continuously increase the availability of the company's machines. By studying the theory of this subject, measurements has designed to produce what the companies availability is in their four main machines. The approach shown in this work is based on three different parameters that affect the value. It is production dependent stop, maintenance dependent stop and resource shortages. By doing this way, the company can be able to have a clearly arranged data to work with, which they easily can see how to enhance availability. It has also been raised a little bit about the reliability and the mean down time where it is also possible to obtain facts to increase availability. What this work have come to is that it can be very different things that affect availability negative but by doing it this way they can see these things and put into action after that.

  • 74.
    Eriksson, Per Erik
    Dalarna University, School of Humanities and Media Studies, Moving Image Production. Mälardalens högskola, Inbyggda system.
    Videography as Design Nexus: Critical Inquires into the Affordances and Efficacies of Live-action Video Instructions2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is about live-action instructional videos (LAVs). By addressing design problems with respect to the how-to video genre, the thesis asks fundamental questions about mediated instructional communication efficacies and the factors that either obstruct or augment them. 

    The analysis presented in this thesis is based on the notion that videography is a design nexus and key focal point of the connections that make live-action video instructional efforts possible. This Design Nexus is explored by defining and illuminating key ontological dimensions, medium specificities and the video users’ cognitive capacities. This is to acknowledge that the users of instructions in this thesis are center stage, both as biological and cultural beings.

    The methods used in this thesis and its associated papers are eye-tracking, video observations, questionnaires, self-reports, focus group interviews and YouTube analytics. Hence, both numerical data and non-numerical data are analyzed in this study.

    The results of the analyses indicate that pre-production planning is key in live-action video instructional endeavors, but not at the expense of the videographer’s status as designer. Moreover, the analyses show that users’ cognitive processing and visual decoding depend on the power of the live-action format to show actual human behavior and action. Other presented evidence seems to infer that LAV-instructions are a little less demanding if users apply a focused decoding style when interacting with them. Nevertheless, physiological engagement of this kind is likely not to fully compensate for users’ psychological engagement.

    This thesis contributes to a more comprehensive understanding of humans’ abilities to interpret the actions of others via medial means. By relating this to video medium-specific affordances, this thesis also furthers important efficacy distinctions and boundary conditions. This understanding is considered important for live-action video makers and designers of visual instructions as well as scholars who need to develop better methods to assess users’ behavioral engagement when they interact with digital instructional media.

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  • 75.
    Fahlvik, Adam
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    3D-skrivare för prototyptillverkning i plast 20162016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis project has been to investigate which new 3D printing equipment

    would be of greatest use for the company Dalelven Produkutveckling AB.

    Through interviews with the company's project leaders the company's needs for new equipment has been identified.

    Information about 3D printers, processingmethods and perihpal equipment has been gathered and sorted. With the support of theories from Quality Function Deployment 3D printers have been evaluated and sorted in categories in accordance with the company's needs.

    Dalelven need to be able to create prototypes in several kinds of plastic. In comparison between the most interesting 3D printers Stratasys polyjet printers from their Objet Connex series got the highest score (exluding HP's “Multi Jet Fusion” printers that not yet are for sale).

    In a comparison between 3D printers that print with thermoplastics it was observed that a couple of relatively unknown companies is producing 3D printers with in some categories better specifications than the established companies alternatives.

  • 76.
    Fakih, Abdullah
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Undersökning av rullfriktionsplanetväxel: Undersökning i FEM och framtagning av dimensioneringsverktyg2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The work is about improvement analysis of a planetary gear. The gear is affected by the friction between the planetary roller and the sleeve. This means that there are no cogs on the wheels, but the rotating parts of the planetary gear are completely round. The friction occurs after the shrinkage of a sleeve on three planetary rollers that is seated in a planetary holder. A company in Smedjebacken uses the planetary gear in their electric hybrid system and during the test run, the planetary gear has failed. The company has carried out an investigation into the cause of the accident and concluded that the sleeve becomes oval after the shrinkage which causes imbalance of the future gear at high speeds. I was commissioned to investigate how the sleeve is affected after the shrinkage and the production of a dimensioning tool that is based on Excel for an improvement proposal for the sleeve.

    The approaches that have been used to fulfill purpose are the gathering of information consisting of interviews and information on the parts of the planetary gear. Furthermore, literature research was carried out to obtain a comprehensive picture of the problem and own studies of the existing sleeve.

    The method has been divided into two parts. Firstly, the examination of the sleeve in the finite element method (FEM) and secondly determine how the structure of the dimensioning tool should be designed. The design tool structure consists of three sheets in Excel program. The first sheet introduces and explains how it works. The second sheet is static calculations that show how the forces act in the sleeve depending on the angle. The last sheet contains Calculations that are based on Hertz's surface pressure. Future work can be the improvement of dimensioning tools and a wider investigation into the cause of the failure of the planetary gear in the hybrid system.

  • 77.
    Farag, Ahmed
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gabriele, Giovanni
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A Feasibility Study of Solar-Assisted District Heating in Torsång2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays, using renewable energy, especially solar, is an expanding trend in the Nordic

    countries. In the past few years, the Europian Union has issued energy efficiency directives

    [1] that obligated its member countries to involve 50 % of renewable energies in the

    district heating (DH) networks. This opens the door for the integration of solar energy in

    the existent heat generation plants.

    Borlänge Energi AB, a municipal energy company, owns and operates a DH plant and

    network in Torsång; a small-community village outside Borlänge, in Dalarna County,

    Sweden. The plant generates the required heat using conventional energy boilers fueled by

    wood pellets, grid electricity, and oil. The company suggested using the nearby empty land,

    owned by the municipality, for installing a solar thermal collector field.

    The thesis aims at doing a feasibility study of the possible integration of a solar thermal

    collector field to the existent DH plant in Torsång. The goal is to replace the oil boilers

    with solar energy and to estimate the amount of fuel and emissions that can be saved and

    their effects on economics.

    To achieve the appointed tasks, a planned strategy was developed. After visiting the site

    and collecting all relevant data, the missing hourly load was calculated. Thumb rules were

    used for system sizing. The Polysun simulation software is used to model and simulate the

    proposed system. Two collector models from the same manufacturer were tested. The

    effects of lowering the DH temperature and changing the pellet boiler shut-down period

    were investigated. A sensitivity analysis of the solar fraction was conducted to provide

    different sizing options. In the end, an economic evaluation of the proposed solutions was

    made.

    The results revealed that, for all cases, the oil boilers could be successfully replaced saving

    0.6 m3 of diesel oil and 1.1 ton of CO2 emissions annually. A solar fraction of around 35 %

    was achieved. Shutting down the pellet boiler in the three summer months was proposed

    which reduced its operating time. Consequently, the pellet boiler energy production and

    the fuel consumption reduced by around 36 %. While its CO2 emissions are mitigated by

    26 %.

    The project, from the economic perspective, is showing a competitive value of LCOH

    (between 386 and 423 SEK/MWh) which is lower than the actual cost of the produced

    heat by the plant (500 SEK/MWh). The payback period is quite reasonable with values

    between 24 and 37 years, depending on the chosen solution. Governmental subsidies are

    not taken into consideration in the economic analysis, so the proposed values represent an

    upper boundary, which can be lowered whenever any incentive will be granted to the

    project.

    The proposed system makes room for two possible solutions: the first allows to shut-down

    the pellet boiler for the whole summer, thus giving more flexibility for the maintenance of

    it, benefits in terms of fuel and related emissions saved, but increasing the electricity

    consumption. The second solution, instead, is offering a shorter shut-down time, but with

    more monetary benefits.

  • 78.
    Fedorov, Anton
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Photovoltaic System Design for a Contaminated Area in Falun – Comparison of South and East- West Layout2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis the solar part of a large grid-connected photovoltaic system design has been done. The main purpose was to size and optimize the system and to present figures helping to evaluate the prospective project rationality, which can potentially be constructed on a contaminated area in Falun. The methodology consisted in PV market study and component selection, site analysis and defining suitable area for solar installation; and system configuration optimization based on PVsyst simulations and Levelized Cost of Energy calculations.

    The procedure was mainly divided on two parts, preliminary and detailed sizing. In the first part the objective was complex, which included the investigation of the most profitable component combination and system optimization due to tilt and row distance. It was done by simulating systems with different components and orientations, which were sized for the same 100kW inverter in order to make a fair comparison. For each simulated result a simplified LCOE calculation procedure was applied. The main results of this part show that with the price of 0.43 €/Wp thin-film modules were the most cost effective solution for the case with a great advantage over crystalline type in terms of financial attractiveness.

    From the results of the preliminary study it was possible to select the optimal system configuration, which was used in the detailed sizing as a starting point. In this part the PVsyst simulations were run, which included full scale system design considering near shadings created by factory buildings. Additionally, more complex procedure of LCOE calculation has been used here considered insurances, maintenance, time value of money and possible cost reduction due to the system size.

    Two system options were proposed in final results; both cover the same area of 66000 m2. The first one represents an ordinary South faced design with 1.1 MW nominal power, which was optimized for the highest performance. According to PVsyst simulations, this system should produce 1108 MWh/year with the initial investment of 835,000 € and 0.056 €/kWh LCOE. The second option has an alternative East-West orientation, which allows to cover 80% of occupied ground and consequently have 6.6 MW PV nominal power. The system produces 5388 MWh/year costs about 4500,000 € and delivers electricity with the same price of 0.056 €/kWh. Even though the EW solution has 20% lower specific energy production, it benefits mainly from lower relative costs for inverters, mounting and annual maintenance expenses.

    After analyzing the performance results, among the two alternatives none of the systems showed a clear superiority so there was no optimal system proposed. Both, South and East-West solutions have own advantages and disadvantages in terms of energy production profile, configuration, installation and maintenance. Furthermore, the uncertainty due to cost figures assumptions restricted the results veracity.

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  • 79. Fedrizzi, Roberto
    et al.
    Dipasquale, Chiara
    Bellini, Alessandro
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ochs, Fabian
    Dermentzis, Georgios
    Nouvel, Romain
    Cotrado, Mariela
    D6.3a Performance of the Studied Systemic Renovation Packages - Method2015Report (Other academic)
    Abstract [en]

    One of the primary objectives of the iNSPiRe project was to develop a tool that predicts the energy and cost saving impacts of various systemic retrofit interventions. This tool is now available for all those involved in the renovation of older buildings (from consulting offices, moving through construction companies and to decision makers) to use as a means of selecting which retrofit package will deliver the greatest costs savings and most improved energy efficiencies.To this purpose, we have produced three databases that provide valuable information about the energy performance of a variety of buildings in different climates, based on different energy requirements. These are the results of a three stage process:1. Collection of energy use data (statistics) for the whole of EU 27, the structuring of a building stock database and the definition of reference buildings that represent the most typical buildings of the building stock. Data for six different age categories were derived, including typical construction information and insulation standards for these periods. Seven climatic regions were also defined to cover the EU 27. The structured data are available in the Building Stock Statistics database.2. Derivation of a complete and consistent database of heating and cooling demands in residential and office buildings covering the whole of the EU 27 based on the simulation of the defined reference buildings in seven climatic regions. The simulations were calibrated against the energy use statistics, and are thus consistent with these, but offer the full range of heating and cooling demands for all climates and building types for six different age categories. The results are available in the Reference Building Simulation database.3. Definition of a range of retrofit measures for the reference buildings including climatic shell, HVAC system and heating/cooling distribution. The matrix of these measures was then simulated for all building types for the seven different climatic regions to provide data for the third database, the Systemic Renovation Packages database.

  • 80. Fedrizzi, Roberto
    et al.
    Dipasquale, Chiara
    Bellini, Alessandro
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ochs, Fabian
    Dermentzis, Georgios
    Nouvel, Romain
    Cotrado, Mariela
    D6.3b Performance of the Studied Systemic Renovation Packages - Single Family Houses2015Report (Other academic)
    Abstract [en]

    One of the primary objectives of the iNSPiRe project was to develop a tool that predicts the energy and cost saving impacts of various systemic retrofit interventions. This tool is now available for all those involved in the renovation of older buildings (from consulting offices, moving through construction companies and to decision makers) to use as a means of selecting which retrofit package will deliver the greatest costs savings and most improved energy performance.The whole set of Renovation Packages in the published database includes results for a range of SFH typologies, from detached to row houses, with different external surface over building volume ratio.In order to compare the same Envelope Renovation when applied to different SFH typologies and climates, we adopted the detached constructions as the basis to define insulation, windows and mechanical ventilation measures that match the heating demand standards sought (15, 25, 40, 70 kWh/m2y). Since the solutions found are the most conservative, lower heating demands are obtained for semi-detached and row houses.The solutions elaborated in terms of window features, and walls/roof cross sections and materials, are reported in Deliverable 6.3a for the whole range of buildings and the 7 climates analysed.In this document we comment the results relative to the reference buildings built 1945-1970, renovated with four generation systems (AWHP, GWHP, gas boiler and biomass boiler) and three distribution systems (radiant ceilings, radiators and fan coils). In order to limit the number of solutions discussed, here we report results only for the detached SFHs. The full range of solutions is published on the iNSPiRe website.The generation plants are hybrid solutions designed to combine heat pumps or boilers with solar thermal and/or PV technologies. These combinations integrate multiple renewable energy sources, thus allowing to reach in the best cases the 50 kWh/m2y primary energy consumption limit that is the objective of the retrofit packages devised.

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  • 81. Fedrizzi, Roberto
    et al.
    Dipasquale, Chiara
    Bellini, Alessandro
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ochs, Fabian
    Dermentzis, Georgios
    Nouvel, Romain
    Cotrado, Mariela
    D6.3c Performance of the Studied Systemic Renovation Packages - Multi-Family Houses2015Report (Other academic)
    Abstract [en]

    In this report, we comment the results relative to the reference buildings built within the first age (1945-1970), and renovated with 4 generation systems (air to water heat pump, ground water heat pump, gas boiler and biomass boiler) and 3 distribution systems (radiant ceilings, radiators and fan coils).According to the buildings classification (see D2.1a and D2.1c), two different Multi Family Houses typologies are identified, small Multi Family House (s-MFH) and large Multi Family House (l-MFH). In the published database, only s-MFHs are included, varying the number of floors (3, 5 and 7 floors) and, consequently, the surface over volume (S/V) ratio.As well as for the SFHs, we adopted a reference S/V ratio as the basis to define insulation, windows and mechanical ventilation measures to match the sought heating demand targets (15, 25, 45, 70 kWh/m²y), that is 5 floors and 10 apartments.

  • 82.
    Folmerz, Mattias
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Oljeläckage torkparti PM12: Utvärdering av oljeläckage i torkparti PM122017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Stora Enso Kvarnsveden is a paper mill located at Dalälven in Kvarnsveden. The utility currently has two producing machines, and this study deals with one of them, which is PM12. At PM12 there is a problem with oil leaks in the machine's drying section. Leakage occurs through the bearing houses who are there to support the dryer's rollers. In this study, it has been investigated what the leakage is due to focusing on its bearing seals.

    The purpose of this study has been to investigate why leakage occurs and to generate concepts to reduce or eliminate leaks. The study has included various measurements and investigations to address the problem. A literature study has been conducted to identify causes and solutions. Concepts have been generated from the literature study as well as the measurements that have been taken.

    After this study it´s not fully realized why the leakage occurs, but it had come a long bit on the way. Proposals for continued work have been given, where it is recommended more specifically what kind of measurements that should be done and the concepts that should be further developed.

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  • 83.
    Forsberg, Elin
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Undersökning: kostnadsreducering av Komponent2020Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This investigation is made in cooperation with a manufacturing company making machines for the foresting industry. The Company is of the opinion that a Component of these machines has a manufacturing cost that is too high, which in turn brings a risk of customer buying similar components manufactured by competing companies to The Company. The Company’s Components is today manufactured by a subcontractor, The Subcontractor. This work began with an investigation of the individual parts of The Component and case studies of the manufacturing process. Further on where suggestions of how to affect the manufacturing costs defined; integration of parts, standardize components, analyse of different ordering volume, and elimination of process steps in the manufacturing process. These actions effect of the manufacturing costs were then examined and compared. The result of this work has not generated cost reductions of The Component that would make The Company competitive on the market of The Component. However the work have generated suggestions on other alternatives that The Company can continue working with to reduce the manufacturing costs of The Component.

  • 84. Freitas, Iuri
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Green building rating systems in Swedish market: A comparative analysis between LEED, BREEAM SE, GreenBuilding and Miljöbyggnad2018In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 153, p. 402-407Article in journal (Refereed)
    Abstract [en]

    In Sweden, there are four most commonly used green building rating systems, which are LEED, BREEAM SE, GreenBuilding and Miljöbyggnad. In this study, each of them is analyzed under the aspects of certification process, implementation cost, educational needs and the variety of categories. SWOT method is further applied to extract the strengths, weaknesses, opportunities and threats of each of the rating system in a direct and indirect manner, making it clearer to choose among various options when considering the individual needs of each project in practice. 

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  • 85.
    Frota de Albuquerque Landi, Fabiana
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energy Performance Contracting in Swedish scenario: a case study with Morastrand AB2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Renovation of the existing buildings in Sweden represents a great potential to achieve the

    energy efficiency and carbon emission targets set by the European Union and the Swedish

    government. The Energy Performance Contracting (EPC) is regarded as an efficient way

    to manage and to outsource the risks of energy efficiency (EE) measures.

    The thesis aims to identify the theoretical framework of EPC in the Swedish scenario and,

    through a real case, develop a model that relates EE measures and its results considering

    the capital investment versus running costs of renovation projects.

    The work is based on the incorporation with the Morastrand AB. The research expects to

    assess EPC processes and measures as in Energy Service Companies (ESCO) and

    consequently help in the decision making and the management of the projects.

    The thesis is composed of two parts. The first part identifies the theoretical framework of

    energy contract models focusing on the EPC, while a case study with Morastrand AB is

    subsequently presented. It is suggested one approach for the preliminary comparison of

    different renovation measures in EE projects, corresponding to the first step of the

    planning phase of an EPC.

    General recommendations and sensitive factors were identified and can assist Morastrand

    AB to effectively implement EE projects in the future. For orienting investments, the

    Lifecycle Cost Analysis (LCCA) is a method to study solutions under economic aspects

    and further it can be extended to the complete Lifecycle Assessment of the upcoming

    projects.

    The theoretical framework of the EPC is composed by identifying the projects, performing

    the technical analysis, determinizing the potential in energy savings, deepening the

    analysis with auditions, tendering the project, designing and executing the project,

    commissioning, operating and supporting the systems with constant monitoring and

    maintenance.

    The biggest challenge for the EPC in Sweden is the relation between the ESCOs and their

    clients. The figure of the facilitator could improve the results and balance the knowledge

    gap between the parts.

    The actors of these projects are the ESCO, the client, the facilitator and the financing part.

    In Sweden, very frequently the client finances the operation. There are a few models of

    contracting, and the most popular are guaranteed savings and shared savings.

    The thesis performed the LCCA of three options for window replacement in a building at

    the end of its lifespan. The results show that the trends in prices and interest rates are

    sensitive factors. In this case, the projects with higher initial investments were more

    profitable. Those solutions can shield the company against energy prices escalates and

    contribute to the green policies.

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  • 86.
    Gerardi, Marcelin
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Namsrai, Miki
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A software system for variables comparison of a paper machine for improved performance2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today paper is to find everywhere, and the production factories always need to increase the

    productivity if they want to stay competitive. Stora Enso Kvarnsveden has one of the biggest

    magazine paper machines in the world, which produces around 1900 meters of paper per

    minute. The production process is highly automatized, which reduces the number of operators

    that work on the machine. Still, process variations can cause brakes in the paper web and lead

    to loss of income, energy and paper production. It may also have a direct impact on the paper

    quality. This report is focusing the following question:

    How to keep the Paper Machine production process under controlled conditions?

    To make a data analysis fully relevant, we need to use the most important variables of the

    machine. By analyzing these data some unexpected behavior and variation of process values

    can be pointed out. The analyzing tool needs to be fast and portable, and therefore a software

    system has been developed. By comparing process data with reference data this software can

    make a powerful analysis.

    The created software is intended to be used either by operators or engineers. The most

    important results are collected in a file. In this text file, the comparison function gives the

    results which are stored in a CSV-format. Furthermore, an auto-update function allows the

    users to run it automatically. Graphical presentations are supporting the interpretation of the

    results.

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  • 87.
    Ghaghazanian, Arash
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    System Integration of PV/T Collectors in Solar Cooling Systems2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The demand for cooling and air-conditioning of building is increasingly ever growing. This increase is mostly due to population and economic growth in developing countries, and also desire for a higher quality of thermal comfort. Increase in the use of conventional cooling systems results in larger carbon footprint and more greenhouse gases considering their higher electricity consumption, and it occasionally creates peaks in electricity demand from power supply grid. Solar energy as a renewable energy source is an alternative to drive the cooling machines since the cooling load is generally high when solar radiation is high.

    This thesis examines the performance of PV/T solar collector manufactured by Solarus company in a solar cooling system for an office building in Dubai, New Delhi, Los Angeles and Cape Town. The study is carried out by analyzing climate data and the requirements for thermal comfort in office buildings. Cooling systems strongly depend on weather conditions and local climate. Cooling load of buildings depend on many parameters such as ambient temperature, indoor comfort temperature, solar gain to the building and internal gains including; number of occupant and electrical devices.

    The simulations were carried out by selecting a suitable thermally driven chiller and modeling it with PV/T solar collector in Polysun software. Fractional primary energy saving and solar fraction were introduced as key figures of the project to evaluate the performance of cooling system. Several parametric studies and simulations were determined according to PV/T aperture area and hot water storage tank volume.

    The fractional primary energy saving analysis revealed that thermally driven chillers, particularly adsorption chillers are not suitable to be utilizing in small size of solar cooling systems in hot and tropic climates such as Dubai and New Delhi. Adsorption chillers require more thermal energy to meet the cooling load in hot and dry climates. The adsorption chillers operate in their full capacity and in higher coefficient of performance when they run in a moderate climate since they can properly reject the exhaust heat. The simulation results also indicated that PV/T solar collector have higher efficiency in warmer climates, however it requires a larger size of PV/T collectors to supply the thermally driven chillers for providing cooling in hot climates. Therefore using an electrical chiller as backup gives much better results in terms of primary energy savings, since PV/T electrical production also can be used for backup electrical chiller in a net metering mechanism.

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  • 88.
    Gilén, Karolina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Haglund, Arvid
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Sammankoppling av fjärrvärmenät: Transiteringsledning mellan Borlänge, Ornäs och Torsång2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Borlänge Energi, BE, owns small district heating, DH, networks in Ornäs and Torsång outside Borlänge, these have high operating costs that are not weighed up by the revenue they make, due to this BE makes a yearly loss on them. Because of this BE wants to connect the small DH networks with the main DH network in Borlänge where the production costs are lower. The technical and economical prerequisites for a connection have therefore been studied.

    Previous literature has been studied regarding economic parameters for connection of DH networks. Unfortunately, the type of connection that is studied in this report has not been found. The studied literature covers expansion of DH network and connection of larger DH networks, and in most cases, the connecting networks have different owners.

    Three possible routes were chosen for the connection with Borlänges DH. The current load for Ornäs and Torsång as well as possible new customers was calculated and used to dimension the pipes and calculate the costs for three different scenarios with different loads. Thereafter the costs and incomes from a connection has been calculated, and then used in BEs capital budget where the pay-off time was calculated based on the discounting method. The capital budgets showed that all the routes except one in the base case were profitable within the time frame of 30 years that was set by BE for investments in DH. Sensitivity analyses were made for pay-off time, construction costs and pipe dimension, which showed that the pay-off time is affected by several factors. But was mostly affected if production costs increase or if pipes are dimensioned for a much larger load than what actually is connected in the end. The number of new customers is therefor important to ensure before building the interconnecting pipe. Pipe dimension was affected most by the load as the transition losses are relatively small, and the building costs were affected most by the cost of the DH pipes since they constitute a large part of those costs.

    Besides from the technical and economical results it has been shown that each and all of the routes have its own prerequisites, where each route has its own pros and cons. All-in-all one route has been chosen as more suitable than the other two, as it besides one of the shortest pay off times also include possibilities to connect new customers along the route.

    As district heating is dependent on local conditions, in regard to both the technical aspects and the soil composition, the report includes several simplifications and assumptions, which have been made based on local conditions and experience. It is necessary to take this into consideration before attempting to apply the findings of this report in other places than Borlänge.

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  • 89. Gluesenkamp, Kyle R.
    et al.
    Frazzica, Andrea
    Velte, Andreas
    Metcalf, Steven
    Yang, Zhiyao
    Rouhani, Mina
    Blackman, Corey
    Dalarna University, School of Technology and Business Studies, Energy Technology. SaltX Technol AB / Malardalens Univ.
    Qu, Ming
    Laurenz, Eric
    Hallin, Ingemar
    Experimentally Measured Thermal Masses of Adsorption Heat Exchangers2020In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 13, no 5, article id 1150Article in journal (Refereed)
    Abstract [en]

    The thermal masses of components influence the performance of many adsorption heat pump systems. However, typically when experimental adsorption systems are reported, data on thermal mass are missing or incomplete. This work provides original measurements of the thermal masses for experimental sorption heat exchanger hardware. Much of this hardware was previously reported in the literature, but without detailed thermal mass data. The data reported in this work are the first values reported in the literature to thoroughly account for all thermal masses, including heat transfer fluid. The impact of thermal mass on system performance is also discussed, with detailed calculation left for future work. The degree to which heat transfer fluid contributes to overall effective thermal mass is also discussed, with detailed calculation left for future work. This work provides a framework for future reporting of experimental thermal masses. The utilization of this framework will enrich the data available for model validation and provide a more thorough accounting of adsorption heat pumps.

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  • 90.
    Graefenhain, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energy Yield Simulation Analysis of Bifacial PV Installations in the Nordic Climate2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Recently, commercial softwares for PV system simulation released bifacial extensions. While research laboratories have developed their own simulation tools, in both cases it is imperative to display their applicability, as well as continuously assess their accuracy and/or limitations in practice, i.e. for different bifacial PV systems and field conditions. This paper presents a design and energy yield simulation study of two bifacial PV systems installed and operating in Nordic climate conditions, i.e. in Vestby, Norway (

    System 1) and in Halmstad, Sweden (System 2). The aim of this study is:

    • • To validate and compare the accuracy of two bifacial PV simulation tools newly featured in the software platforms of PVsyst and Polysun respectively, against real-field energy yield data.

    Each investigated system is modeled and analyzed with both simulation tools, resulting in four individual case stu

    dies. Further details on the systems’ monitoring set-up, the data input, modeling steps, and the involved uncertainties are presented in this paper.

    The results of the four case studies show higher percent deviations (both monthly and hourly data) between simulated energy results and real energy results during winter periods compared to summer periods. System 1 had a lower bifacial gain (around 2%) than System 2 which ranges from 2% in summer periods to 25% during winter.

    The collected field data had too high of an uncertainty to determine whether the bifacial PV simulation extensions are accurate within a certain tolerance. The reason for higher simulation inaccuracy in the winter is due to: lower production, higher uncertainty in albedo, and more diffuse irradiation.

    It is recommended for the bifacial PV simulation extensions include options for considering a variable albedo. The bifacial gain in System 2 was higher in the winter because of the higher albedo value given whereas in System 1, the albedo value was kept constant. Further parametric studies should be conducted on the bifacial gain using vertical mounted bifacial PV modules oriented east and west for Nordic climate conditions.

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  • 91.
    Grälls, Gustav
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Kemell, Tim
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energieffektivisering av glödskalsspolning: Utredning av högtryckssystem för glödskalsspolning, med avseende på energieffektiviserande förbättringar och förslag till åtgärder.2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The hot rolling mill at SSAB in Borlänge uses large amounts of electricity every year. The work of systematically reducing energy usage is an ongoing process, both for the sake of the environment but also for increasing profit in the production. The high pressure system for descaling uses 20 GWh of electricity every year. This is about 10 % of the hot rolling mills total electricity usage. The steel slabs are heated before being rolled. This causes iron and oxygen to react with each other and form a scale. This scale is not desired in steel production which is why several methods to remove it have been developed. The method being used at SSAB is high pressure water descaling.

    Large volumes of water are being pressurized and sprayed through nozzles in thin triangle-like jets against the steel. To remove the scale a certain amount of energy is required. It can be calculated by using impingement pressure as a function of specific water rate (amount of water per square meter). This thesis is based on the assumption that the energy usage in the total system can be reduced without reducing the amount of energy that strikes the steel surface. The total efficiency of the system is today 39 %.

    A big contribution to the low efficiency is that all pumps are running on constant rotational speed. They need a minimal flow of water through them for cooling. This minimal flow is according to the manufacturer supposed to be 12 m3/h, but in reality they run at 30 m3/h. This is because of wear in the relief valves that are supposed to reduce the drainage flow. The relief valves are also designed to close the minimal flow to drain during descaling. This is not working as it should and water is flowing to drain during descaling. This result in the yearly energy usage increasing with 3 GWh. Additionally, because of the increased flow to the drain, energy usage is increased by around 6 %. The accumulators being used, four in total at 7 m3 each, are not used in an optimal way. Some observations have been done and at those times the tanks have been filled with about 50 % water. An accumulator should, according to theory, be empty when reaching lowest allowed system pressure. As being used today only a few percent of the tanks water volume can be used.

    A suggestion of bigger change that has been developed is to change pumps and to install bigger accumulators at the furnace and roughing descaler. This would then be made into a separate system, separated from the finishing descaler. An advantage with separate systems is that the parts can be dimensioned for different pressures. This could be especially interesting if piston pumps are installed in the accumulator system.

  • 92.
    Gustafsson, Emil
    Dalarna University, School of Technology and Business Studies, Materials Technology. Luleå tekniska universitet.
    Design and application of experimental methods for steel sheet shearing2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Shearing is the process where sheet metal is mechanically cut between two tools. Various shearing technologies are commonly used in the sheet metal industry, for example, in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material. The constant development of sheet metals toward higher strength and formability leads to increased forces on the shearing equipment and tools.

    Shearing of new sheet materials imply new suitable shearing parameters. Investigations of the shearing parameters through live tests in the production are expensive and separate experiments are time consuming and requires specialized equipment. Studies involving a large number of parameters and coupled effects are therefore preferably performed by finite element based simulations. Accurate experimental data is still a prerequisite to validate such simulations. There is, however, a shortage of accurate experimental data to validate such simulations.

    In industrial shearing processes, measured forces are always larger than the actual forces acting on the sheet, due to friction losses. Shearing also generates a force that attempts to separate the two tools with changed shearing conditions through increased clearance between the tools as result. Tool clearance is also the most common shearing parameter to adjust, depending on material grade and sheet thickness, to moderate the required force and to control the final sheared edge geometry.

    In this work, an experimental procedure that provides a stable tool clearance together with accurate measurements of tool forces and tool displacements, was designed, built and evaluated. Important shearing parameters and demands on the experimental set-up were identified in a sensitivity analysis performed with finite element simulations under the assumption of plane strain. With respect to large tool clearance stability and accurate force measurements, a symmetric experiment with two simultaneous shears and internal balancing of forces attempting to separate the tools was constructed.

    Steel sheets of different strength levels were sheared using the above mentioned experimental set-up, with various tool clearances, sheet clamping and rake angles. Results showed that tool penetration before fracture decreased with increased material strength. When one side of the sheet was left unclamped and free to move, the required shearing force decreased but instead the force attempting to separate the two tools increased. Further, the maximum shearing force decreased and the rollover increased with increased tool clearance.

    Digital image correlation was applied to measure strains on the sheet surface. The obtained strain fields, together with a material model, were used to compute the stress state in the sheet. A comparison, up to crack initiation, of these experimental results with corresponding results from finite element simulations in three dimensions and at a plane strain approximation showed that effective strains on the surface are representative also for the bulk material.

    A simple model was successfully applied to calculate the tool forces in shearing with angled tools from forces measured with parallel tools. These results suggest that, with respect to tool forces, a plane strain approximation is valid also at angled tools, at least for small rake angles.

    In general terms, this study provide a stable symmetric experimental set-up with internal balancing of lateral forces, for accurate measurements of tool forces, tool displacements, and sheet deformations, to study the effects of important shearing parameters. The results give further insight to the strain and stress conditions at crack initiation during shearing, and can also be used to validate models of the shearing process.

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  • 93.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Karlsson, Lars
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Experimental study of forces and energies during shearing of steel sheet with angled tools2016In: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 11, article id 10Article in journal (Refereed)
    Abstract [en]

    Shearing is a fast and inexpensive method to cut sheet metal that has been used since the beginning of the industrialism. Consequently, published experimental studies of shearing can be found from over a century back in time. Recent studies, however, are due to the availability of low cost digital computation power, mostly based on finite element simulations that guarantees quick results. Still, for validation of models and simulations, accurate experimental data is a requisite. When applicable, 2D models are in general desirable over 3D models because of advantages like low computation time and easy model formulation. Shearing of sheet metal with parallel tools is successfully modelled in 2D with a plane strain approximation, but with angled tools the approximation is less obvious. Therefore, plane strain approximations for shearing with angled tools were evaluated by shear experiments of high accuracy. Tool angle, tool clearance, and clamping of the sheet were varied in the experiments. The results showed that the measured forces in shearing with angled tools can be approximately calculated using force measurements from shearing with parallel tools. Shearing energy was introduced as a quantifiable measure of suitable tool clearance range. The effects of the shearing parameters on forces were in agreement with previous studies. Based on the agreement between calculations and experiments, analysis based on a plane strain assumption is considered applicable for angled tools with a small (up to 2 degrees) rake angle.

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  • 94.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Karlsson, Lars
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Luleå University of Technology.
    Experimental study of strain fields during shearing of medium and high-strength steel sheet2016In: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 11, no 1, article id 14Article in journal (Refereed)
    Abstract [en]

    There is a shortage of experimentally determined strains during sheet metal shearing. These kinds of data are a requisite to validate shearing models and to simulate the shearing process. In this work, strain fields were continuously measured during shearing of a medium and a high strength steel sheet, using digital image correlation. Preliminary studies based on finite element simulations, suggested that the effective surface strains are a good approximation of the bulk strains below the surface. The experiments were performed in a symmetric set-up with large stiffness and stable tool clearances, using various combinations of tool clearance and clamping configuration. Due to large deformations, strains were measured from images captured in a series of steps from shearing start to final fracture. Both the Cauchy and Hencky strain measures were considered, but the difference between these were found negligible with the number of increments used (about 20 to 50). Force-displacement curves were also determined for the various experimental conditions. The measured strain fields displayed a thin band of large strain between the tool edges. Shearing with two clamps resulted in a symmetric strain band whereas there was an extended area with large strains around the tool at the unclamped side when shearing with one clamp. Furthermore, one or two cracks were visible on most of the samples close to the tool edges well before final fracture. The fracture strain was larger for the medium strength material compared with the high-strength material and increased with increasing clearance.

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  • 95.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Marth, Stefan
    Luleå University of Technology.
    Karlsson, Lars
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Luleå University of Technology.
    Strain and stress conditions at crack initiation during shearing of medium- and high-strength steel sheet2017In: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 12, no 1, p. 10-Article in journal (Refereed)
    Abstract [en]

    Strain and stress conditions in sheet metal shearing are of interest for calibration of various fracture criteria. Most fracture criterion are governed by effective strain and stress triaxiality. This work is an attempt to extend previous measurements of strain fields in shearing of steel sheets with the stress state calculated from the measured displacement fields. Results are presented in terms of von Mises stress and stress triaxiality fields, and a comparison was made with finite element simulations. Also an evaluation of the similarities of the stress conditions on the sheet surface and inside the bulk material were presented. Strains and von Mises stresses were similar on the surface and the bulk material, but the stress triaxiality was not comparable. There were large gradients in strain and stress around the curved tool profiles that made the results resolution dependent and comparisons of maximum strain and stress values difficult. The stress state on the sheet surface calculated from displacement field measurements is still useful for validation of a three dimensional finite element model.

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  • 96.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Jansson, Anders
    Design and validation of a sheet metal shearing experimental procedure2014In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 214, no 11, p. 2468-2477Article in journal (Refereed)
    Abstract [en]

    Throughout the industrial processes of sheet metal manufacturing and refining, shear cutting is widely used for its speed and cost advantages over competing cutting methods. Industrial shears may include some force measurement possibilities, but the force is most likely influenced by friction losses between shear tool and the point of measurement, and are in general not showing the actual force applied to the sheet. Well defined shears and accurate measurements of force and shear tool position are important for understanding the influence of shear parameters. Accurate experimental data are also necessary for calibration of numerical shear models. Here, a dedicated laboratory set-up with well defined geometry and movement in the shear, and high measurability in terms of force and geometry is designed, built and verified. Parameters important to the shear process are studied with perturbation analysis techniques and requirements on input parameter accuracy are formulated to meet experimental output demands. Input parameters in shearing are mostly geometric parameters, but also material properties and contact conditions. Based on the accuracy requirements, a symmetric experiment with internal balancing of forces is constructed to avoid guides and corresponding friction losses. Finally, the experimental procedure is validated through shearing of a medium grade steel. With the obtained experimental set-up performance, force changes as result of changes in studied input parameters are distinguishable down to a level of 1%.

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  • 97.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Jansson, Anders
    Experimental study on the effects of clearance and clamping in steel sheet metal shearing2016In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 229, p. 172-180Article in journal (Refereed)
    Abstract [en]

    Shear cutting is common within several sheet metal industry processing steps, e.g. in cut to length lines, slitting lines, end cropping. Shearing is fast and cheap relative to competing cutting methods like laser and plasma cutting, but involves large forces on the equipment that increase with increased sheet material strength. Accurate shear experiments are a prerequisite to increase the knowledge of shearing parameters, improve industrial shearing, and provide data for validation of numerical shear models. Here, the two shear parameters clearance and clamp configuration, identified as important to the shear results, were studied in an experimental set-up with well defined tool movement and high measurability of tool position and force. In addition to force measurements, the sheared edge geometry was characterized. Steels of low, medium, and high strength were selected for the study. Throughout the experimental study, the shear tool penetration before fracture decreased with increased material strength. The required shear force decreased and the force attempting to separate the two shear tools increased when one side of the sheet was left unclamped and free to move. Further, the maximum shear force increased with decreased clearance. Clearance changes were small and moreover continuously measured during all shear experiments.

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  • 98. Gustafsson, M.
    et al.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Trygg, L.
    Karlsson, B.
    CO2 emission evaluation of energy conserving measures in buildings connected to a district heating system: Case study of a multi-dwelling building in Sweden2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 111, p. 341-350Article in journal (Refereed)
    Abstract [en]

    When taking action to fulfill the directives from the European Union, energy conserving measures will be implemented in the building sector. If buildings are connected to district heating systems, a reduced heat demand will influence the electricity production if the reduced heat demand is covered by combined heat and power plants.This study analyze five different energy conserving measures in a multi-dwelling building regarding how they affect the marginal production units in the district heating system in Gävle, Sweden. For CO2 emission evaluations, two different combinations of heat and electricity conserving measures are compared to an installation of an exhaust air heat pump.The different energy conserving measures affect the district heating system in different ways. The results show that installing an exhaust air heat pump affects the use/production of electricity in the district heating system most and electricity conserving measures result in reduced use of electricity in the building, reduced use of electricity for production of heat in the district heating system and an increase of electricity production.The conclusion is that electricity use in the building is the most important factor to consider when energy conserving measures are introduced in buildings within the district heating system in Gävle.

  • 99.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology. KTH.
    Energy efficient and economic renovation of residential buildings with low-temperature heating and air heat recovery2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    With the building sector accounting for around 40% of the total energy consumption in the EU, energy efficiency in buildings is and continues to be an important issue. Great progress has been made in reducing the energy consumption in new buildings, but the large stock of existing buildings with poor energy performance is probably an even more crucial area of focus. This thesis deals with energy efficiency measures that can be suitable for renovation of existing houses, particularly low-temperature heating systems and ventilation systems with heat recovery. The energy performance, environmental impact and costs are evaluated for a range of system combinations, for small and large houses with various heating demands and for different climates in Europe. The results were derived through simulation with energy calculation tools.

    Low-temperature heating and air heat recovery were both found to be promising with regard to increasing energy efficiency in European houses. These solutions proved particularly effective in Northern Europe as low-temperature heating and air heat recovery have a greater impact in cold climates and on houses with high heating demands. The performance of heat pumps, both with outdoor air and exhaust air, was seen to improve with low-temperature heating. The choice between an exhaust air heat pump and a ventilation system with heat recovery is likely to depend on case specific conditions, but both choices are more cost-effective and have a lower environmental impact than systems without heat recovery. The advantage of the heat pump is that it can be used all year round, given that it produces DHW.

    Economic and environmental aspects of energy efficiency measures do not always harmonize. On the one hand, lower costs can sometimes mean larger environmental impact; on the other hand there can be divergence between different environmental aspects. This makes it difficult to define financial subsidies to promote energy efficiency measures.

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  • 100.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH, Strömnings- och klimatteknik.
    Energy Efficient Renovation Strategies for Swedish and Other European Residential and Office Buildings2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The high energy use in the European building stock is attributable to the large share of old buildings with poor energy performance. Energy renovation of buildings is therefore vital in the work towards energy efficiency and reduced environmental impact in the EU. Yet, the strategies and energy system implications of this work have not been made clear, and the rate of building renovation is currently very low.

    The aim of this thesis is to investigate the economic and environmental aspects of energy renovation strategies, with two main objectives:

    • Renovation of Swedish district heated multi-family houses, including life-cycle cost and environmental analysis and impact on the local energy system;

    • Renovation of European residential and office buildings, including life-cycle cost and environmental analysis and influence of climatic conditions.

    Buildings typical for the respective regions and the period of construction 1945-1970 were simulated, in order to determine the feasibility and energy saving potential of energy renovation measures in European climates. A variety of systems for heating, cooling and ventilation were studied, as well as solar energy systems, with focus on heat pumps, district heating, low-temperature heating systems and air heat recovery.

    Compared to normal building renovation, energy renovation can often reduce the life-cycle costs and environmental impact. In renovation of typical European office buildings, as well as Southern European multi-family houses, more ambitious renovation levels can also be more profitable.

    Exhaust air heat pumps can be cost-effective complements in district heated multi-family houses, while ventilation with heat recovery is more expensive but also more likely to reduce the primary energy use. From a system perspective, simple exhaust ventilation can reduce the primary energy use in the district-heating plant as much as an exhaust air heat pump, due to the lower electricity use.

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