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  • 201.
    Poppi, Stefano
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Heinz, Andreas
    Hengel, Franz
    Cheze, David
    Mojic, Igor
    Cialani, Catia
    Dalarna University, School of Technology and Business Studies, Economics.
    Analysis of system improvements in solar thermal and air source heat pump combisystems2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 173, p. 606-623Article in journal (Refereed)
    Abstract [en]

    A solar thermal and heat pump combisystem is one of many system alternatives on the market for supplying domestic hot water (DHW) and space heating (SH) in dwellings. In this study a reference solar thermal and air source heat pump combisystem was defined and modelled based on products available on the market. Based on the results of an extensive literature survey, several system variations were investigated to show the influence of heat pump cycle, thermal storage and system integration on the use of electricity for two houses in the climates of Zurich and Carcassonne. A singular economic cash flow analysis was carried out and the “additional investment limit” of each system variation was determined for a range of economic boundary conditions. This is the maximum extra investment cost for the system variant compared to the reference system that will give a break even result for a 10 year period. The results show that variations in electricity price affects the additional investment limit far more than the other economic parameters. Several of the variants show potential for achieving a cost benefit, but the potential varies a lot depending on load and climate boundary conditions. For all variants, the biggest difference in electricity savings was found for Zurich rather than in Carcassonne, which is explained by the larger heating load. However, in three cases the largest savings were for the SFH45 house despite the fact that the annual electricity use of the system is much lower than that for the SFH100 house, 3581 kW h/year compared to 8340 kW h/year. This was attributed to the fact that, in these cases, the operating level of the space heating circuit played a significant role, the SFH45 house being supplied with a 35/30 °C heating system while the SFH100 was supplied with a 55/45 °C heating system.

  • 202.
    Poppi, Stefano
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Sommerfeldt, N.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Madani, H.
    Lundqvist, P.
    Techno-economic review of solar heat pump systems for residential heating applications2018In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 81, p. 22-32Article in journal (Refereed)
    Abstract [en]

    Solar heat pump systems (SHPs) have been investigated for several decades and have been proven to increase the share of renewable energy and reduce electric energy demand in residential heating applications. Many review articles have been published on the subject, however literature discussing the techno-economics of different solar technologies (thermal, photovoltaic and hybrid thermal/photovoltaic) in combination with heat pumps is lacking, and thus to directly compare the merits of different SHPs is not an easy task. The objectives of this study are: a) review the different system boundaries and the main performance indicators used for assessing energetic and economic performances; b) review techno-economic studies in the literature and identify which studies give enough information and are compatible enough for making an economic inter-comparison; c) present an economic inter-comparison based on the identified systems. The results show that there is a lack of studies including an economic assessment of solar photovoltaic and heat pump systems. Additionally, there are no consistent boundaries or approaches to the study structures, making comparisons between systems difficult. In conclusion, a standardized or broadly accepted definition of technical and economic performance for SHPs is needed. Despite this, the study has shown that there are clear trends for decreasing payback times for SHPs, both solar thermal (ST) and photovoltaic (PV), with decreasing heating degree-days and with increasing solar resource.

  • 203.
    Psimopoulos, Emmanouil
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bee, E.
    Luthander, R.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Smart control strategy for PV and heat pump system utilizing thermal and electrical storage and forecast services2017Conference paper (Refereed)
  • 204.
    Psimopoulos, Emmanouil
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Uppsala University.
    Bee, Elena
    University of Trento, Trento, Italy.
    Luthander, Rasmus
    Uppsala University.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Smart control strategy for PV and heat pump system utilizing thermal and electrical storage and forecast services2017Conference paper (Refereed)
    Abstract [en]

    In this study, a detailed model of a single-family house with exhaust air heat pump, PV system and energy hub developed in the simulation software TRNSYS 17 is used to evaluate energy management algorithms that utilize weather and electricity price forecasts. A system with independent PV and heat pump is used as a base case. The proposed control strategy is applied to the base case to optimize the available PV electricity production using short-term weather and electricity price forecasts. The three smart and predictive control algorithms were developed with the scope to minimize final energy by the use of the thermal storage of the building, the hot water tank and electrical storage. The results show reduction of the final energy of 26.4%, increase of the self-consumption to 60% and decrease of the annual cost of 15% when using the forecast services in combination with thermal and electrical storage compared to the base case.

  • 205.
    Psimopoulos, Emmanouil
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Uppsala University.
    Bee, Elena
    Widén, Joakim
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Techno-economic analysis of control algorithms for an exhaust air heat pump system for detached houses coupled to a photovoltaic system2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 249, p. 355-367Article in journal (Refereed)
    Abstract [en]

    Operational control strategies for the heating system and “smart” utilization of energy storage were developed and analyzed in a simulation based case study of a single-family house with exhaust air heat pump and photovoltaic system. Rule based control algorithms that can easily be implemented into modern heat pump controllers were developed with the aim to minimize final energy and maximize self-consumption by the use of the thermal storage of the building, the hot water tank and electrical storage. Short-term weather and electricity price forecasts are used in some of the algorithms. Heat supply from an exhaust air heat pump is limited by the ventilation flow rate fixed by building codes, and compact systems employ an electric heater as backup for both space heating and hot water. This heater plays an important role in the energy balance of the system. A typical system designed for new detached houses in Sweden was chosen for the study. This system, together with an independent photovoltaic system, was used as a base case and all results are compared to those for this base case system. TRNSYS 17 was used to model the building and system as well as the control algorithms, and special care was taken to model the use of the backup electric heater as this impacts significantly on final energy use. Results show that the developed algorithms can reduce final energy by 5–31% and the annual net cost for the end user by 3–26%, with the larger values being for systems with a battery storage. Moreover, the annual use of the backup electric heater can be decreased by 13–30% using the carefully designed algorithms.

  • 206.
    Psimopoulos, Emmanouil
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Uppsala universitet.
    Leppin, Lorenz
    Luthander, Rasmus
    Uppsala universitet, Fasta tillståndets fysik.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Control algorithms for PV and Heat Pump system using thermal and electrical storage2016In: Proceedings of the 11th ISES EuroSun 2016 International Conference on Solar Energy for Buildings and Industry, Palma de Mallorca, Spain, 11-14 October 2016, International Solar Energy Society , 2016Conference paper (Other academic)
    Abstract [en]

    In this study a detailed model of a single-family house with an exhaust air heat pump and photovoltaic system is developed in the simulation software TRNSYS. The model is used to evaluate three control algorithms using thermal and electrical storage in terms of final energy, solar fraction, self-consumption and seasonal performance factor. The algorithms are tested and compared with respect to energetic improvement for 1) use of the heat pump plus storage tank for domestic hot water and space heating, 2) use of the electrical storage in batteries and 3) use of both electrical and thermal storage. Results show the highest increase of self-consumption to 50.5%, solar fraction to 40.6% and final energy decrease to 6923 kWh by implementing the third algorithm in a system with 9.36 kW PV capacity and battery storage of 10.8 kWh. The use of electrical energy storage has higher positive impact compared to the thermal storage with the settings and component sizes used. The combined use of thermal storage and batteries leads to final energy savings that are nearly the same as the combined savings of thermal storage and batteries separately, showing that they are mostly independent of one another for the settings of this study.

  • 207.
    Puhakka, Fredrik
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Lund, Simon
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energy focus in the building process2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Residential buildings have served as homes for the humankind throughout the years and the energy focus is relatively new in comparison. The interest of the energy perspective has increased alongside with the stricter laws and goals in the European Union and the Swedish Building Board. In multiple cases, the calculated energy usage of the buildings are usually lower than the real time measured energy consumption, showing the importance of performing energy follow-ups of the buildings. The goal of this thesis is revolving around the understanding of the the problems, performance and importance of energy follow-ups in the building process. This study will only focus on the energy focus of residential buildings in the building process, while only taking the Swedish laws into consideration. A literature study was performed as an intention to understand the subject and its problems more thoroughly. The literature study contains the Swedish laws regarding the subject, the structure of the building process and possible failure points, while also looking at multiple studies regarding the difference between the calculated and the measured values. Furthermore, inquiries were sent out to multiple municipalities and companies with questions related to the subject.

    In the answers from the different respondents, the result showed that both municipalities and companies stores energy statistics in web-based programs and requires real measurements to perform energy follow-ups. One municipality describes that there was a vague understanding of the consequences or penalties of not performing an energy follow-up according to the time-plan. Furthermore, the company A described that there was a lack of knowledge of how or where measurements should be performed in detail and where responsibility should be placed if not everything is fulfilled according to the contract. The companies set up their own local goals that surpasses the rules of the BBR and the companies very rarely breaks the energy limits. Company B has only failed to meet the energy limits once and that project was sold off to another actor. Company B also describes that they have never failed to perform an energy follow-up according to the time-plan and doesn’t know what to do if it would happen. Another municipality refers multiple times to their goals regarding the climate and energy limits, however, the methodology on how to achieve these goals aren’t described. Lastly, the there’s no form of cooperation between the municipalities or the companies.

    Differences in energy performance, between the calculated and the real, is often a result of many different factors, which is not always easy to define. Throughout the building process, it is of high importance to keep focus on the energy question in every step. Good and correct knowledge has to be present the whole process to give the best prerequisites for a good performing building. Bad energy performance leads to higher cost for the habitants. Loose terms in laws and regulations can lead to bad energy calculations and leave room for influencing the calculation to show wanted results. Good energy declarations require proper measurements and as the standard equipment today provides somewhat lacking data with monthly values, which makes it difficult to study the reasons to higher energy consumption. For better understanding abnormal energy consumption, more detailed values are often necessary. In terms of applicability, this study can contribute to the awareness to the different issues that has occurred from the study, for example the required education and the responsibility in more detail. A few conclusions can be made from this study, the lack of knowledge in terms of responsibility, consequences or penalties and how measurements should be made in detail. Another conclusion are that web-based programs are used for energy follow-ups and require real values and there’s no cooperation between different actors related to this subject.

  • 208.
    Quintana, Samer
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Building integrated photovoltaic (BIPV) modelling for a demo site in Ludvika based on building information modelling (BIM) platform2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis aims to design and simulate a building integrated photovoltaic (BIPV)

    system for three demo buildings in Ludvika, Sweden, which is part of the Energy-

    Matching’s project under the European H2020 research scheme. A literature

    review was firstly conducted in the area of energy scenarios, engineering tools,

    methodologies and the workflows in design and building energy modelling. Then,

    this thesis developed the three-dimensional (3D) building models of the demo

    site, based on the Revit – a building information modelling (BIM) tool. Next, the

    PVSITES tool was considered as the main approach to simulate and optimize the

    BIPV system. Results on the energy output of the dedicated BIPV system, as well

    as financial costs, were finally obtained. It was found that the optimal location for

    the BIPV system was on the three buildings south and east faced roofs, with a total

    area of approximately 800 meters squared (m2) and a yearly irradiance potential

    between 1020 kilowatts hours per meter squared (kWh/m2) and 925 kWh/m2

    respectively. The simulation showed that this BIPV system of 615 m2 with a power

    of 36 kilowatts-peak (kWp) could yield a maximum of 29,000 kilowatts hours per

    year (kWh), a 5% of the total yearly energy demand of the building and over the

    summer, this percentage increases considerably. With the estimated standards

    costs, the BIPV system have a 12 years payback period and 61% investment ratio

    over a 20 years period, concluding that a BIPV system on the Ludvika demo

    building is a feasible project, in terms of energy potential and as well as

    economically. This thesis also concludes that performing the BIPV simulation on

    the BIM platform is both reliable and flexible, and also has the potential to be

    reused, refined and scaled up.

  • 209.
    Radoglou, Kalliopi
    et al.
    Democritus University of Thrace.
    Sismanis, Nikos
    Democritus University of Thrace.
    Smirnakou, Sonia
    Democritus University of Thrace.
    Mattsson, Anders
    Dalarna University, School of Technology and Business Studies, Forest and Wood Technology.
    Hernandez Velasco, Marco
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Schirone, Bartolomeo
    Universita degli Studi della Tuscia.
    Marras, Tatiana
    Universita degli Studi della Tuscia.
    Vessella, Federico
    Universita degli Studi della Tuscia.
    Chiatante, Donato
    Università degli Studi dell'Insubria.
    Terzaghi, Mattia
    Università degli Studi dell'Insubria.
    Fulgaro, Nicoletta
    Università degli Studi dell'Insubria.
    Montagnoli, Antonio
    Università degli Studi dell'Insubria.
    ZEPHYR Project – Deliverable D3.2: Intermediate report on growth tests2014Report (Other (popular science, discussion, etc.))
  • 210.
    Ramaswamy Iyyaswamy, Prashanth
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Performance Analysis of a Building Integrated Photovoltaic System in Norway2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, performance of the PV system on the facade of the Oseana building is

    evaluated. The thesis was done at the Institute for Energy Technology (IFE), which is

    situated in Kjeller, Norway. The building of the PV system that is being analyzed in this

    thesis is situated in Osøyro, Os Kommune, which is located south of Bergen. The analysis

    was carried out by modelling the building and the PV system in PVsyst, a software package

    specifically used for sizing, simulation and analysis of complete PV systems. Simulations

    were performed on user-defined models based on the original system, whilst considering

    different cases, the results from these simulations were compared to the inverter output

    data, and conclusions were derived.

    The building with the PV system under study has a unique architecture, having a curved

    facade with the panels mounted on this curved facade. The facade also has a walkway

    coming out of the third floor window, which causes shading. The effects of the shading

    caused by the walkway were analyzed. Simulations were carried out for different cases and

    the results were compared to derive conclusions.

    Different weather data sources were considered and used in the base simulations to

    identify the most relevant data source. Once the best data source was identified, further

    simulations were carried out to generate outputs such as the system’s annual yield, losses

    and performance ratio. These simulation outputs were then compared with the actual

    annual outputs of the system. The performance ratios of the simulated systems, with and

    without the walkway are obtained and a comparison between them is made. The probable

    values of global horizontal irradiance are calculated and these values were compared with

    the annual yield of the system to check if the data would match. Probability simulations

    were also carried out to determine the percentage chance that the system would yield a

    certain output value in any given year. Furthermore, the orientation of the PV plane of the

    PV system was changed by altering the tilt angles

  • 211.
    Ramírez Villegas, Ricardo
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A methodology to assess impacts of energy efficient renovation - A Swedish case study2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The European Union aims to reduce energy use and CO2-emissions by 40 % by the year 2030. The building sector has been identified as having a great potential to reduce emission of CO2 by increasing its energy efficiency. Also, there is a growing concern of the buildings environmental performance, that lead to the development of building environmental assessment tools. However, different types of energy sources and confusing environmental impacts affect the decision making when renovating for improved energy efficiency. This study develops and tests a methodology to help decision-makers when considering major renovation of their building stock when connected to adistrict heating system. The proposed methodology is applied and used to investigate how different renovation scenarios affects the building environmental impacts in terms of CO2 emissions and identify and discuss future improvements of the methodology.

    The novelty of the method is the expanded system boundaries that include both the distribution and production of district heating and the energy use at a building level. In this way it is possible to compare and weight measures made both at the energy system level and the building level. This work has limited its approach to energy use in buildings, but it is important to bring the life cycle thinking to the methodology. During the choice of the renovation methods it was noticed that the environmental impact of the production of some components in order to reduce the energy use of a building are not insignificant. Even if all the renovation measures considered in this case study are feasible, it is important to determine in which order they are desirable or achievable from an economic point of view. Uncertainty in the future development of energy, and limited economic resources can play an important role in the possibility of energy efficient renovation.

  • 212.
    Ramírez Villegas, Ricardo
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. University of Gävle.
    Eriksson, O.
    Olofsson, T.
    Life cycle assessment of building renovation measures–trade-off between building materials and energy2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 3, article id 344Article in journal (Refereed)
  • 213.
    Ramírez Villegas, Ricardo
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Eriksson, Ola
    Högskolan i Gävle.
    Olofsson, Thomas
    Dalarna University, School of Technology and Business Studies, Construction. Umeå universitet.
    Assessment of renovation measures for a dwelling area: impacts on energy efficiency and building certification2016In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 97, p. 26-33Article in journal (Refereed)
    Abstract [en]

    The European Union has an ambitious plan to reduce energy use and emissions by the year 2030. The building and real estate sectors have a great potential to help reduce emissions by energy efficiency. However, different energy sources and environmental standards affect the decision making of these major renovations in the existing stock. This study investigates how different renovation strategies affect the energy rating of a selected Building Environmental Assessment Tool and analyses the consequences in terms of greenhouse gas emissions for the local district heating system. Both building energy simulations and energy systems cost optimization were used to determine the energy use and local emissions. The results of different renovation scenarios were used to evaluate the rating in the selected tool and the impact in the district heating local emissions. The used methodology illustrates how energy efficient renovation impacts on the district heating system’s local emissions. However, a bias towards resource classification within the Swedish Building Environmental Tool, Miljöbyggnad, needs to be addressed in order to assess the impact of local emissions. © 2015 Elsevier Ltd.

  • 214.
    Ramírez Villegas, Ricardo
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Högskolan i Gävle.
    Eriksson, Ola
    Olofsson, Thomas
    Combined environmental and economic assessment of energy efficiency measures in a multi-dwelling building2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 13, article id 2484Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to assess how different renovation scenarios affect the environmental and economic impacts of a multi-dwelling building in a Nordic climate, how these aspects are correlated and how different energy carriers affect different environmental impact categories. In order to reduce greenhouse gas emissions, the European Union has set an agenda in order to reduce energy use in buildings. New buildings on the European market have a low replacement rate, which makes building renovation an important factor for achieving the European Union goals. In this study, eight renovation strategies were analyzed following the European Committee for Standardization standards for life cycle assessment and life cycle costs of buildings. This study covers all life cycle steps from cradle to grave. The renovation scenarios include combinations of photovoltaics, geothermal heat pumps, heat recovery ventilation and improved building envelopes. Results show that, depending on the energy carrier, reductions in global warming potential can be achieved at the expense of an increased nuclear waste disposal. It also shows that for the investigated renovation strategies in Sweden there is no correlation between the economic and the environmental performance of the building. Changing energy carriers in Sweden in order to reduce greenhouse gas emissions can be a good alternative, but it makes the system more dependent on nuclear power.

  • 215.
    Rasch, André
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Utvärdering av Ngenic Tune: Smart styrning av värmesystem i småhus2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In 2016, the global energy consumption was represented to 20 % by buildings, where energy use supplied heating, cooling, lightning and water heating. For the following years until 2040, global energy consumption is expected to grow 48 %, which in turn make demand for energy efficient measures. For the years of 2030 as well 2050, the EU-commission have set up climate goals to reduce global greenhouse gas emissions. Along with this were presented strategies for meeting future climate goals, where one strategy is about increasing overall energy efficiency, which includes buildings. One way of increasing building energy efficiency is through implementation of smart heating control, a cost-effective solution which through a retrofitting measure may reduce building energy consumption. For this paper, a smart thermostat named Ngenic Tune was implemented into a selection of single family houses in Borlänge district heating network. The purpose was to study improvements in thermal comfort and reduction of return temperature from domestic substations. Through a combined survey-interview study of Ngenic Tune users, the study revealed promising potentials for large scale implementation of the technology. The smart thermostat also showed tendency of lowering the return temperature.

  • 216.
    Reitz, Linda
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Planning and visualization of energy-efficient container buildings for residential purposes under three climatic conditions2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Shipping containers that can no longer be used in cargo transportation are accumulating in large numbers in ports all over the world. At the same time, the usage of fully modular and prefabricated components in the construction sector is on a constant rise in recent years. Reusing these containers in their current form without melting them down, significantly elevates their lifetime usage as well as opens new and interesting options for modular buildings.

    While there are already many container buildings worldwide, the area of energy-efficient container houses has hardly been touched. Therefore, the goal of this thesis is to show the usage of shipping containers to plan energy efficient buildings in three different climate zones, while each building itself is fully climate adaptable for its location using passive architecture.

    To accomplish this primary focus, a detailed analysis of the climate conditions of the locations is necessary. The tree locations are Stockholm, Berlin, and Cape Town. Afterwards a uniform base model will be developed, depending on the specifications of these shipping containers. This Base Case can be adapted to three different climate conditions, by modification and adaptation to create buildings with an effective passive architecture for each location’s climate conditions. These modifications will be used to develop a suitable design for each climate zone with all specifications described and visualized for each case of usage.

  • 217. Ren, Guangying
    et al.
    Sunikka-Blank, Minna
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The Influence of Variation in Occupancy Pattern on Domestic Energy Simulation Prediction: A Case Study in Shanghai2017Conference paper (Refereed)
  • 218.
    Rizos, Konstantinos
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Design Synthesis and Characterization of New Hybrid Derivatives for Dye Sensitized Solar Cells (DSSCs) Based on Porphyrin Rings2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sunlight is the most abundant and one of the cleanest sources of energy. Nature harnesses solar energy very efficiently via the photosynthetic process. A tremendous effort has been expended at learning from natural photosynthesis and creating artificial systems for solar energy applications based on porphyrins that are key light – absorber components of successful solar cells. Dye-sensitized solar cells (DSSCs) establish an innovative class of hybrid organic-inorganic solar cells. The device consists of a mesoporous film of titanium dioxide (TiO2) nanoparticles, coated with a dye monolayer. The role of the dye in DSSCs is similar to the role of chlorophyll in plants and its presence guarantees the sensitivity of the DSSC in the visible part of the solar spectrum, by gathering solar light and transferring the energy via electron transfer to an appropriate material to produce electricity. To date the highest solar energy to electricity conversion efficiencies have reached ~13%. The principal aim of this thesis is the synthesis and characterization of new porphyrin bioinorganic sensitizers for DSSCs. The synthesis part has used a modified synthetic approach by the Coutsolelos group that has successfully produced a new porphyrin product. The base porphyrin was prepared by the trifluoroacetic acid (TFA) catalyzed condensation following a modified procedure. The porphyrin was purified by silica gel column chromatography using dichloromethane. Metallation of porphyrin by Zn was done in the chloroform–methanol mixture followed by the chromatographic purification. The new porphyrin product was subsequently characterized with Ultraviolet – Visible (UV-VIS), Nuclear Magnetic Resonance (NMR), and Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) spectroscopies that have verified the formation of the end product. The characterization shows that the new synthesized porphyrin has characteristics very similar to that of the porphyrin complex with the record efficiency of 13%.

  • 219.
    Rozas Barrio de Mendoza, Andrés Arturo
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Design, Implementation and Performance Evaluation of an Off-grid Photovoltaic Powered Grain Mill without Battery Storage Master2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Many rural communities in developing countries still do not have access to electricity, however, inhabitants of those communities must still perform energy demanding activities. Such is the case of milling grains to fulfill their food intake. This activity, in many cases, is still performed manually.

    This research project aims in providing a solution to the aforementioned problem by designing, implementing and testing a grain mill powered solely by means of photovoltaic energy. It is intended to avoid the use of an intermediate battery in order to reduce the initial and possible running costs of the solution.

    The project development included testing the operation of the mill under different speeds and loads to acknowledge the torque profile and accurately size the corresponding motor. A brushless direct current motor together to its speed controller was selected to drive the mill. The operation of the mill was tested under constant and variable power source to characterize the electrical performance and size a suitable photovoltaic module. Also, the quality of the flour and output rate were analyzed.

    A modified maximum power point tracker controller was designed and implemented based on a microcontroller (Arduino Uno board). The perturb and observe as well as the incremental conductance maximum power point tracking methods were implemented and analyzed to be used as the basis of the modified tracking algorithm.

    The overall performance of the designed controller was evaluated using a modified test procedure based on the EN 50530 standard, which indicates how to evaluate the static and the dynamic efficiency of the maximum power point trackers in grid connected inverters.

    The proposed controller achieved an average static efficiency of 47 % while milling corn and 55 % while milling wheat, based on the weighting factors defined in the European efficiency. Moreover, the controller reached an average dynamic efficiency of 50 % while milling corn and 62 % while milling wheat during the test with irradiance change from medium to high levels (300 W/m2 to 1000 W/m2). Finally, the average flour output rate while milling corn was measured as 3.25 kg/h while milling corn and 5.38 kg/h while milling wheat.

  • 220.
    Saini, Puneet Kumar
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A Preliminary Optimisation and Techno-economic Analysis of Solar Assisted Building Heating System Using Transpired Air Solar Collector and Heat Pump in Sweden2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis presents an optimisation approach and techno-economic evaluation tool for a system consisting of a transpired solar air collector and air source heat pump in a series arrangement. The thesis also investigates the application of the developed tool for feasibility study of a solar heat pump system for a group of three multi-family houses located in Ludvika, Sweden.

     

    Transpired solar air collector is used in combination with an air source heat pump to meet space heating and hot water demand for the defined location. Moreover, the solar pre-heated fresh air is used as a heat source for the heat pump evaporator to improve its coefficient of performance. Solar heat pump systems are extensively studied by numerous researchers, However the analyses about techno-economic feasibility of air source heat pump with transpired air solar collector are still lacking. Therefore, an optimisation tool is developed based on the non-linear programming for coherent operation strategy and variation in collector flow rate. The effect of optimisation along with the techno-economic feasibility for a demo case residential building in Sweden is then preliminary studied based on the defined boundary conditions.

     

    The analysis is gradually progressed through several phases of thesis starting from system description and followed by tool methodology and case study. A pre-developed dynamic simulation model is used to obtain the space heating and domestic hot water demand of the building. The electricity expenses of the existing system are evaluated and the results are used as a reference to compare the savings resulting from the installation of transpired solar collectors with gross area of 50 m2.

     

    The results are presented as a defined economic indicator such as payback period. The results of the simulation reflect that the installation of 50 m2solar collector area leads to 3 % savings compared to the defined reference case, with a simple payback of 22 years. Moreover, results also indicate that variation of collector flow rate and operation timings are effective strategies to maximise the system savings. The analysis reveals that the optimisation can result in up to 60 % additional savings in comparison to a fixed flow rate case.

     

    The developed tool has a potential use for feasibility check at an earlier stage of the installation project, without the need for extensive system simulations. Moreover, the tool overcomes the shortcoming of various available tools such as RETscreen solar air heating project model, which are not designed to evaluate the performance of solar collectors with heat pump systems.

  • 221.
    Sandström, August
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energitekniska lösningar på ett flerbostadshus i Falun2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The thesis work has been done at the consulting company called ÅF Infrastructure (Ångpanneföreningen in Swedish) in Sweden, Borlänge. They wanted information about different energy efficient solutions and what the results would be if they are implemented in a newbuilding-project. In this thesis work energy efficient solutions have been evaluated in an upcoming multifamily house located in Falun, Sweden. The solutions that have been evaluated are better isolated doors and windows, more isolated outer wall, different heat recovery ventilation (HRV) systems and geothermal heating pump. The study has gathered information about which solution that have the highest energy saving and also the economy of these solutions during the lifetime of the multifamily house.

    To simulate how much energy saving the different solutions generates a program called IDA ICE (Indoor Climate and Energy) has been used. A model of the upcoming project has been built in the program, after that the different solutions are tested. The results are put in a spreadsheet designed by ÅF, the results from IDA ICE transforms into different energy posts in the sheet.

    The reference case has been used as a reference to compare the different solutions. The reference case has district heating and ventilation with HRV. The surrounding building parts has an average U-value of 0,26 W/m2K. Total heated area (Atemp) is measured to 1330 m2. Simulation of the basic case gives a total energy use of 115 MWh/year. Depending on solution energy savings between 1500 and 62 000 kWh/year are made. Cost savings during the solutions lifetime are at lowest around 40 000 SEK and highest around 545 000 SEK. As expected, a geothermal heat pump generates most energy savings, with almost 62 000 kWh/ year. But using a heat pump increases the electricity demand with almost 3,5 times.

  • 222.
    Selva Marti, Salvador
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Aerial Thermography Inspections in Large-Scale PV Plants2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to successfully compete against the use of fossil fuels to generate electricity, one of the challenges in the photovoltaic (PV) business currently in focus is on the asset management of large PV plants, in which developing control techniques to prognosticate and evaluate the future energy performance will be essential. Infrared thermography inspections can give meaningful support to assess the quality and performance of PV modules. However, the implementation of a cost-effective method to scan and check huge PV plants represents different challenges, such as the cost and time of detecting PV module defects with their classification and exact localization within the solar plant. In this context, it has recently been investigated the potential of a new innovative technology in the PV plants monitoring operations by using drones.

    The main purpose of this work is to establish a scientific basis for the interpretation of thermographic images taken by drones, in particular, regarding the influence of thermographic irregularities which will negatively influence the performance of PV plants.

    The drone is employed to monitor PV modules conditions by using special thermography sensors mounted on it in order to scan images. The captured images are then automatically sent to a technical office database for the image processing software. This special software receives, stores and analyses the captured images to detect the specific defect on the PV modules. Then, all information is processed and reported to the final decision-making team to decide about the best solution for the particular degraded PV module, in relation with the requirements from the operation and maintenance (O&M) services.

    In this particularly study project of the inspected PV plant situated in the UK, which has been carried out by trained personnel at Quintas Energy (QE), the majority of identified faults, which influence the PV module performance (especially the power output significantly), are on a sub-panel level, either individual cells or uneven hot spots. There are also some modules with bypass diode faults as well as a string fault was detected. Such faults must be repaired by the PV module manufacturer, in relation to the manufacturer’s warranties, without any cost at all since the PV modules are indeed still in warranty.

    It has been concluded that, in comparison with traditional manned systems by using hand-held cameras, the main functionality of using drones is the early fault diagnosis which could reduce corrective maintenance activities, since defects are easily and quickly identified and, then, repaired. This fact could reduce defects to become more serious and, thus, more difficult to be repaired, along with their correspondent production losses and costs.

    QE has learned by making mistakes during this project study and gained experience of this unmanned aerial vehicles (UAV) technology. Currently, they are in the process of improving this technique and will continue to implement it to all their PV plants since the efficiency of PV systems can be significantly improved by appropriate use of O&M instruments and benefit from innovative monitoring tools, such as the unmanned aerial technology.

  • 223.
    Sharma, Raushan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    PVT Roof Integrated System – Technical and Economic Feasibility for an Agricultural Building2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Modern agriculture is profoundly reliant on use of fossil fuels and with the vision of transferring those uses to renewable energy sources, a hybrid photovoltaic thermal system (PVT) has been designed in this study to use the cogenerated heat for crop drying while generating green electricity.

    The designed PVT system will use a fan to extract the heat and provide the optimal thermal energy during crop drying period and will be used in passive mode to improve the electrical efficiency of the system during rest of the period. The main aim of this study is to quantify the output from the designed PVT system with its economic evaluations.

    A novel methodology is developed by using the simulated output from grid connected PV system as an input for modelling the PVT system using steady state equations in Microsoft Excel. Parameters such as duct depth, air mass flow rate and corresponding fan electrical power requirements were optimized using batch simulations for providing optimal thermal and electrical output from the system.

    The thermal energy efficiency of the designed PVT system using copper indium gallium selenide (CIGS) cells was predicted to be 28 % with the electrical efficiency improvement by 2 % for forced cooling and around 1 % during passive air flow. The designed PVT system will have a payback period of 13 years with the current financial regulations and framework in Sweden.

  • 224.
    Shen, Jingchun
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Copertaro, Benedetta
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    An early-stage analysis of climate-adaptive designs for multi-family buildings under future climate scenario: case studies in Rome, Italy and Stockholm, Sweden2019In: Article in journal (Refereed)
    Abstract [en]

    This paper presents a preliminary case study for climate-adaptive residential multifamily building designs located in urban centre at early stage, to allow thermal comfort and minimum energy use from today to the last part of 21st century. The generated future climate data combined with comfort model assessment has been proposed as a new way including future climate scenarios in preliminary building design for two representative sites, in Rome, Italy and Stockholm, Sweden. The existing vulnerability to the expected climate conditions from psychometric analysis indicates that: (1) the climate trend in Rome would gradually lead to more failures in the majority of conventional adaptive design measures, as the cooling and dehumidification demands would rise from 5.3% to 23.6%, while the heating and humidification demands would decrease from 27% to 16%; (2) the climate trend in Stockholm would result in an increased comfort period by exploiting more adaptive design measures, since the heating and humidification demands would be reduced from 67% to 53%. However, the cooling and dehumidification demands would increase slightly from 0% to 1.5%. Accordingly, four main key risks are identified: 1) overheating would become a rising increasing public health threat for buildings in Rome that rely exclusively on natural ventilation; 2) open questions remain for the design team in the area of correct cooling load selection, additional space for the future installation and the effectiveness of current cooling device etc.; 3) occasional heat waves and gradual rising humidity levels are expected to be a vulnerable topic for conventional lightweight building in Stockholm; 4) buildings with a heavy heating load would tend to have greater cooling demand, especially those with poor ventilation resources or greater internal gains. In conclusion, it is suggested that envelope optimization, whichever climate type, is one of the most efficient and effective adaptation measures towards future climate conditions.

  • 225. Sotnikov, A.
    et al.
    Nielsen, C. K.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dalenbäck, J. -O
    Andersen, Martin
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Psimopoulos, Emmanouil
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Simulations of a Solar-Assisted Block Heating System2017Conference paper (Refereed)
  • 226.
    Swing Gustafsson, Moa
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    The impact on the energy system of heating demands in buildings: A case study on district heating and electricity for heating in Falun, Sweden2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Energy efficiency measures in buildings are considered to have great potential in order to reduce total energy consumption, and thus contribute to a reduced environmental impact and a better climate. In Sweden, however, the energy performance requirements for buildings are formulated in terms of bought energy, i.e. as bought electricity and district heating (DH), which does not always reflect the environmental and climate impact from a broader perspective. Focusing on bought energy means that many choose an electricity-based heat pump solution in their building instead of DH, since heat pumps result in a smaller amount of bought energy compared to DH.

    The surrounding energy system of the buildings is affected by the choice of energy carriers used for heating. How the energy system is affected is studied in this thesis using two different methods. In the first part, primary energy consumption has been calculated for a simulated building with different heating solutions, representing different electricity and DH demands. In the second part, the impact on total consumption in the surrounding power and DH networks due to different market shares of electricity-based heating and DH has been studied. The second part also includes an analysis of the potential to produce electricity using combined heat and power (CHP) in different scenarios depending on the market share of DH. This part has been carried out as a case study for the Swedish municipality of Falun.

    The results show that the choice of energy carrier has a great influence on primary energy consumption. The resulting primary energy consumption does, however, to an even greater extent depend on the calculation method used. Which heating solution, and thus also which energy carrier, gets the lowest primary energy consumption varies in the different methods.

    The surrounding power and DH networks are also affected to a great extent by the choice of energy carrier. There is a huge potential to lower peak demand in the power grid by avoiding electricity-based heating. The potential to produce electricity using CHP is also increased with a larger market share for DH. In Falun, reduced electricity demand and increased electricity production using CHP make it possible to cover the peak power demand using only electricity production from CHP. In comparison, 10 % of the peak power demand was covered by electricity from CHP in 2015.

    The choice of energy carrier for heating in buildings affects the surrounding energy system to a high degree, and is therefore an important aspect to take into account in both local, national and global energy efficiency projects. 

  • 227.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalen University.
    Primary energy use in buildings in a Swedish perspective2016In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 130, p. 202-209Article in journal (Refereed)
    Abstract [en]

    The building sector accounts for a large part of the energy use in Europe and is a sector where the energy efficiency needs to improve in order to reach the EU energy and climate goals. The energy efficiency goal is set in terms of primary energy even though there are different opinions on how to calculate primary energy. When determining the primary energy use in a building several assumptions are made regarding allocation and the value of different energy sources. In order to analyze the difference in primary energy when different methods are used, this study use 16 combinations of different assumptions to calculate the primary energy use for three simulated heating and ventilations systems in a building. The system with the lowest primary energy use differs depending on the method used. Comparing a system with district heating and mechanical exhaust ventilation with a system with district heating, mechanical exhaust ventilation and exhaust air heat pump, the former has a 40% higher primary energy use in one scenario while the other has a 320% higher in another scenario. This illustrates the difficulty in determining which system makes the largest contribution to fulfilling the EU energy and climate goals.

  • 228.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalen University.
    Assessment of the potential for district heating to lower the peak electricity consumption in a medium size municipality in SwedenManuscript (preprint) (Other academic)
    Abstract [en]

    Sweden faces several challenges when more intermittent renewable power is integrated into the energy system. One of the challenges is to have enough electrical power available in periods with low production from intermittent sources. A solution to the problem could be to reduce the electricity peak demand and at the same time produce more electricity during peak hours. One way of doing this is to convert electricity based heating in buildings to district heating (DH) based on combined heat and power (CHP).

    The study analyzes how much a medium sized Swedish municipality can contribute to lower the electricity peak demand. This is done by quantifying the potential to reduce the peak demand for six different scenarios of the future heat market volume and heat market shares regarding electricity based heating and DH in 2050.

    The main finding is that electricity consumption will be reduced by 35-70 % during the peak hour (and 20-40 % on a yearly basis) for all the six scenarios studied compared with the current situation. If the aim is to lower the electricity peak demand in the future, the choice of heating system is more important than reducing the heat demand itself. For the scenario with a large share of DH, it is possible to cover the electricity peak demand in the municipality by using CHP.

  • 229.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Life cycle cost of heat supply to areas with detached houses: a comparison of district heating and heat pumps from an energy system perspective2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 12, article id 3266Article in journal (Refereed)
    Abstract [en]

    There are different views on whether district heating (DH) or heat pumps (HPs) is or are the best heating solution in order to reach a 100% renewable energy system. This article investigates the economic perspective, by calculating and comparing the energy system life cycle cost (LCC) for the two solutions in areas with detached houses. The LCC is calculated using Monte Carlo simulation, where all input data is varied according to predefined probability distributions. In addition to the parameter variations, 16 different scenarios are evaluated regarding the main fuel for the DH, the percentage of combined heat and power (CHP), the DH temperature level, and the type of electrical backup power. Although HP is the case with the lowest LCC for most of the scenarios, there are alternatives for each scenario in which either HP or DH has the lowest LCC. In alternative scenarios with additional electricity transmission costs, and a marginal cost perspective regarding the CHP investment, DH has the lowest LCC overall, taking into account all scenarios. The study concludes that the decision based on energy system economy on whether DH should expand into areas with detached houses must take local conditions into consideration.

  • 230.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalen University.
    Mapping of heat and electricity consumption in a medium size municipality in Sweden2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, p. 1434-1439Article in journal (Refereed)
    Abstract [en]

    The Nordic electricity system faces many challenges with an increased share of intermittent power from renewable sources. One such challenge is to have enough capacity installed to cover the peak demands. In Sweden these peaks appear during the winter since a lot of electricity is used for heating. In this paper a mapping of the heat and electricity consumption in a medium size municipality in Sweden is presented. The paper analyze the potential for a larger market share of district heating (DH) and how it can affect the electrical power balance in the case study. The current heat market (HM) and electricity consumption is presented and divided into different user categories. Heating in detached houses not connected to DH covers 25 % of the HM, and 30 % of the electricity consumption during the peak hours. Converting the detached houses not connected to DH in densely populated areas to DH could reduce the annual electricity consumption by 10 %, and the electricity consumption during the peak hours by 20 %.

  • 231.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Potential for district heating to lower peak electricity demand in a medium-size municipality in Sweden2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 186, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Sweden faces several challenges with more intermittent power in the energy system. One challenge is to have enough power available in periods with low intermittent production. A solution could be to reduce peak demand and at the same time produce more electricity during these hours. One way of doing this is to convert electricity-based heating in buildings to district heating based on combined heat and power. The study analyzes how much a Swedish municipality can contribute to lowering peak electricity demand. This is done by quantifying the potential to reduce the peak demand for six different scenarios of the future heat demand and heat market shares regarding two different energy carriers: electricity-based heating and district heating. The main finding is that there is a huge potential to decrease peak power demand by the choice of energy carrier for the buildings’ heating system. In order to lower electricity peak demand in the future, the choice of heating system is more important than reducing the heat demand itself. For the scenario with a large share of district heating, it is possible to cover the electricity peak demand in the municipality by using combined heat and power.

  • 232.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Primary energy reduction in buildings: Case study on a residential building in Falun, Sweden2014In: Proceedings from the 14th International Symposium on District Heating and Cooling / [ed] Anna LAND, Swedish District Heating Association, 2014, p. 543-545Conference paper (Refereed)
    Abstract [en]

    Since a large share of the total European primary energy is consumed in the building sector, buildings have to become more energy efficient in order to reach the goals of the European energy efficiency directive. In Sweden, focus has been on lowering final energy consumption, not primary energy consumption. A relevant question today is whether a general understanding of the primary energy concept is needed to encourage selection of better energy efficiency measures from an environmental perspective. There are however uncertainties of how to calculate primary energy consumption since different primary energy factors (PEF) are used by different actors, especially for district heating (DH) and electricity (EL.).

    In this study total primary energy consumption was calculated for a residential building before and after several renovation measures were made. The major change after the renovation was that a large share of the DH was substituted by heat from an exhaust air heat pump and solar collectors. A range of commonly used PEFs were assessed.

    The evaluation showed that the energy efficiency measures reduced the total primary energy consumption for most combinations of PEFs. The most essential was how the DH was valued. A low PEF for DH in combination with most of the PEFs for electricity could even result in higher total primary energy consumption after the renovation.  

  • 233.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalens högskola.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Gustafsson, Marcus
    Life cycle cost of building energy renovation measures, considering future energy production scenarios2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 14, article id 2719Article in journal (Refereed)
    Abstract [en]

    A common way of calculating the life cycle cost (LCC) of building renovation measures is to approach it from the building side, where the energy system is considered by calculating the savings in the form of less bought energy. In this study a wider perspective is introduced. The LCC for three different energy renovation measures, mechanical ventilation with heat recovery and two different heat pump systems, are compared to a reference case, a building connected to the district heating system. The energy system supplying the building is assumed to be 100% renewable, where eight different future scenarios are considered. The LCC is calculated as the total cost for the renovation measures and the energy systems. All renovation measures result in a lower district heating demand, at the expense of an increased electricity demand. All renovation measures also result in an increased LCC, compared to the reference building. When aiming for a transformation towards a 100% renewable system in the future, this study shows the importance of having a system perspective, and also taking possible future production scenarios into consideration when evaluating building renovation measures that are carried out today, but will last for several years, in which the energy production system, hopefully, will change.

  • 234. Takács, Ágnes
    et al.
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gulyás, Ágnes
    Kiss, Márton
    Kántor, Noémi
    Radiation conditions at a Central European square in a hot summer day, a case study from Szeged, Hungary2017In: 97th Annual Meeting of the American Meteorological Society (AMS) jointly with the 13th Symposium on the Urban Environment, Seattle, WA, 2017Conference paper (Other academic)
    Abstract [en]

    In the light of sustained urbanization and rising temperature trends, mitigating the impact of extreme heat events is a pressing urban planning issue. Radiation heat load, quantified as mean radiant temperature (Tmrt), has been identified as the main source of summer heat stress. Several studies ascertained that Tmrt is the key factor driving human thermal comfort in outdoor urban places. Shading that reduces radiation heat load (Tmrt) is the most effective means to mitigate heat stress in outdoor public places, which offer a venue for leisure, recreation and for the social life of residents. Nonetheless, the small-scale thermal conditions of urban places are not only governed by shade trees and greenery, but also by buildings and paved surfaces. The aim of this study is twofold. First, it assesses the impact of differently oriented street facades with varying solar exposure on the human radiation balance at a medium-sized square in a mid-latitude city. Second, it evaluates the performance of popular, freely available microclimate and radiation models in deriving Tmrt values. The well-vegetated, rectangular Bartók square was selected in Szeged, Hungary to calculate various radiation parameters using three numerical simulation models (ENVI-met, SOLWEIG and RayMan). The derived parameters (radiation flux densities from different directions, as well as Tmrt) are compared with corresponding values obtained from detailed on-site measurements. The field data are collected as part of a 24-hour long radiation measurement utilizing the six-directional method, where a set of pyranometers and pyrgeometers are used to record short- and long-wave flux densities from six perpendicular directions (from above, from below as well as from the four cardinal points). The model-measurement comparison is based on hourly data from five locations within the square: from the center and from near the four bordering street facades of the rectangular square. Our initial results indicate that besides direct solar radiation, the temperatures of artificial surfaces (e.i. of building walls and pavements) strongly influences the human radiation balance: the increased temperature of surrounding surfaces increases the amount of emitted long-wave radiation and thus, reduces the amount a person is able to dissipate. Investigations like ours are necessary both for the advancement of our filed in general, and for the development of numerical models in particular. Models are simplifications of reality and thus they introduce a certain degree of idealization: trees are never as perfectly shaped or have a homogeneous crown transmissivity and leaf area index (LAI) in the reality, neither do surface parameters are as uniform as frequently assumed by models. All these differences influence model results to a certain degree. Therefore, the ideal outdoor thermal conditions that practitioners often plan for from behind their desks are likely to be worse in reality. Identifying the strengths and weaknesses of different models and revealing how they compare to reality is essential for both scientists and urban planners, since they all need to understand and acknowledge the limitations of the numerical approach.

  • 235.
    Tesfay Abraham, Bisrat
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Degradation Evaluation of Grid- Connected PV Modules at Högskolan Dalarna Borlänge, Sweden2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study has been carried out to evaluate the degradation of grid connected PV system modules installed at Högskolan Dalarna in Borlänge, Sweden. The system which has two arrays each containing 36 monocrystalline PV modules has been in operation since 1994. The modules from GPV of an average peak power 43.9W were tested for I-V curve characteristics under outdoor conditions using AMPROBE Solar 4000 I-V curve tracer with ±1% accuracy and AMBROBE Solar 4000 Sensor with accuracy of ±5%. Measured electrical parameters (short circuit current, open circuit voltage, and maximum power) were extrapolated to STC following Standards IEC 60904-1 for I-V curve measurement and IEC 60891 for temperature and solar irradiation corrections. Thus, values extrapolated to STC were compared with nominal values to calculate global power degradation.

    An average global power degradation showing a standard deviation of 1.6% is found as 11.9% while open circuit voltage and shot circuit current average degradations are 2.5% and 6.4% respectively. Calculated median degradation rate of 0.6% is also compared with a related study median degradation rate of 0.46% per year in similar weather conditions and estimated warranties of 80% of the nominal power after 20 years of operation provided in the 90s. Thus, all the tested modules have a median degradation of 2.5% higher than that of related study and they have shown higher performance as compared to estimated manufacturer’s warranty.

    Regarding degradation modes, visual inspection was carried out on each module, except light yellowing or browning in some modules, no visually visible defects or faults like cell crack, delamination, bubbles, hot spot, and rust in connection boxes were displayed. However, the calculated power degradation, depending on the I-V curves deviations found, is induced because of the possible causes by parasitic resistances, mismatch, ageing, and loss of transparency of encapsulant due to light browning.

  • 236.
    Thyr, Max
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Simulation Study of Bifacial PV Modules in Sweden2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    One argument against the usage of PV system is the low energy density. Another common

    argue is the bad possibility to match energy generation and the energy demand in time. A

    solution for these problems could be to use bifacial PV modules. A bifacial PV module can

    generate energy even from the rear side. With this technic more energy can be generated

    per area. In this thesis simulations with bifacial PV modules has been performed for three

    different locations in Sweden. Different tilts, mounting heights and azimuth angles have

    been simulated, all in combination of varying albedo. These cases simulated are Borlänge,

    Jukkasjärvi and Linköping. In Linköping there is a PhD project about bifacial PV modules

    going on. The test field used in that project has been simulated in this simulation study to

    later be compared with measured results.

    In this thesis the simulation tool Polysun was used. Polysun is a user friendly tool and with

    the latest update it’s possible to simulate bifacial PV modules. For all three cases a

    reference system has also been simulated using monofacial PV modules.

    The simulated result suggests that bifacial PV modules should be mounted with the same

    tilt as monofacial PV modules. The orientation should be towards south, the output

    becomes evident decreased if the bifacial PV modules are facing east-west compared to

    south.

    Polysun seems to only take ground reflected radiation into account when calculating the

    rear side energy output when simulations is performed with bifacial PV modules. When

    the albedo is 0 there won’t be an extra output from rear side for all mounting

    combinations. If the bifacial PV module is mounted 0m above ground, there won’t be any

    energy output from the rear side either. This are big limitations in the program.

    In Polysun the simplification is made that it’s the same albedo all year around. It’s not

    possible to do simulations with different albedos. In reality the natural albedo will change

    with the season, especially in Sweden. But those conditions are not possible to simulate. A

    good idea for bifacial modules would be to secure as high albedo as possible by paint or a

    bright canvas.

  • 237.
    Tjäder, Jonas
    et al.
    STRI.
    Ackeby, Susanne
    STRI.
    Bastholm, Caroline
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The role and interaction of microgrids and centralized grids in developing modern power systems2016Conference paper (Refereed)
  • 238.
    Troitiño Malavasi, Bruno Matias
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Replacing Finned Copper withCorrugated Stainless Steel, forthe Heat Exchangers of a SolarCombisystem Store: Performance and EconomicEvaluation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The importance of investigating cost reduction in materials and components for solar thermal systems is crucial at the present time. This work focuses on the influence of two different heat exchangers on the performance of a solar thermal system. Both heat exchangers studied are immersed helically coiled, one made with corrugated stainless steel tube, and the other made with finned copper tube with smooth inner surface.A test apparatus has been designed and a simple test procedure applied in order to study heat transfer characteristics and pressure drop of both coils. Thereafter, the resulting experimental data was used to perform a parameter identification of the heat exchangers, in order to obtain a TRNSYS model with its corresponding numerical expression. Also a representative small-scale combisystem model was designed in TRNSYS, in order to study the influence of both heat exchangers on the solar fraction of the system, when working at different flow rates.It has been found that the highest solar fraction is given by the corrugated stainless steel coil, when it works at the lowest flow rate (100 l/hr). For any higher flow rate, the studied copper coil presents a higher solar fraction. The advantageous low flow performance of stainless steel heat exchanger turns out to be beneficial for the particular case of solar thermal systems, where it is well known that low flow collector loops lead to enhanced store stratification, and consequently higher solar fractions.Finally, an optimization of the stainless steel heat exchanger length is carried out, according to economic figures. For the given combisystem model and boundary conditions, the optimum length value is found between 10 and 12 m.

  • 239. Trygg, Louise
    et al.
    Björk, Curt
    Karlsson, Peter
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Djuric Ilic, Danica
    Heat collaboration for increased resource efficiency: A case study of a regional district heating system and a mine2016Conference paper (Other academic)
    Abstract [en]

    To rapidly develop sustainable energy systems is crucial for the whole society's transition towards sustainability. System efficiency and reduced climate impact are important parts of this. Swedish district heating systems are fairly well developed, mainly based on non-fossil fuels, and includes energy-efficient technologies (such as combined heat and power production and fuel gas condensation). Increased use of district heating is therefore considered as a way to increase energy-efficiency, to phase out fossil energy for heating purposes, and subsequently to a reduction of global CO2 emissions. 

    The aim of this paper is to study system impact of increased demand of district heating by analysing a collaboration on heat supply between the local energy supplier of Ludvika in Sweden and a nearby mine. The paper analyses economic potential, as well as the potential for more efficient operation of district heating production plants in the local district heating system. The heat demand in the mine is presently supplied from a small-scale biomass-fuelled heat-only boiler located near to the mine. The system consists of two biomass-fuelled heat-only boilers with fuel gas condensers. The consequences of connecting the heat demand of the mine with the municipal district heating system is analyzed using the cost optimization model MODEST. 

  • 240.
    Trygg, Louise
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ersson, Hans
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gradén, Mattias
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ragnarsson, Marit
    Rehme, Jakob
    Hinder och Drivkrafter: Projekt Branschvis Energieffektivisering2015Report (Other academic)
    Abstract [sv]

    Föreliggande rapport är en del av utvärdering av projektet BEE – Branschvis energieffektivisering.

    Projektet BEE – Branschvis Energieffektivisering

    Projektet genomfördes under 2013-2014 i Dalarna och Gävleborgs län. Projektägare var Länsstyrelsen Dalarna i samarbete med Gävle-Dala Energikontor. Projektet finansierades med medel från Energimyndigheten, Region Gävleborg och Länsstyrelsen Dalarna.

    Samarbete inleddes med små och medelstora industrier (SME) inom följande branscher: sågverk, teknikföretag, träindustrier, kött- och livsmedelsindustrier, alpina skidanläggningar, turisthotell, drivmedelsstationer och livsmedelsbutiker. För varje bransch har projektet anlitat en specialiserad energikonsult som hjälpt företagen med energikartläggningar och gett stöd för planering av åtgärder. 125 företag medverkade i projektet, varav 116 stycken gjorde en heltäckande energikartläggning. Sammanlagt togs mer än 1 750 förslag på åtgärder fram.

    I projektidén för BEE ingick även att engagera energi- och klimatrådgivarna i genomförandet, för att på så sätt bidra till kompetensutveckling. Syftet med projektet var att fokusera på energikartläggningar och genomförande av åtgärder. Själva energikartläggningarna har inte genomförts med finansiering av projektet, utan som en affärsmässig uppgörelse mellan företagen och vald energikonsult.

    Syftet med föreliggande rapport är att studera förutsättningar för en implementering av åtgärder för energieffektivisering som framkommit vid de genomförda energikartläggningarna från projekt BEE. Genom intervjuundersökningar och enkätstudier har drivkrafter och hinder studerats för energieffektivisering samt hur företagen arbetar med internt energieffektivisering. Som komplement till detta är även en analys gjord avseende ekonomiska förutsättning för energieffektivisering i de studerande branscherna (se appendix 1).

    De resultat som presenteras i denna rapport har gjorts med representanter från olika befattningar inom de analyserade industrierna. Alla har gett sin syn på hinder och drivkrafter för energieffektivisering samt hur det interna energieffektiviseringsarbetet fortgår inom deras organisation och hur det kan förbättras.

    Resultat från intervjuundersökningar och enkätstudier visar bl.a. att inom branscherna teknikföretag, kött- och livsmedelsindustrier, alpina skidanläggningar, drivmedelsstationer, turisthotell och livsmedelsbutiker är kostnadsbesparingar är en av de tre främsta gemensamma drivkraften, samt att brist på investeringskapital eller osäkerhet kring investeringsberäkning anges som ett av de främsta hindren för energieffektivisering. Inom branscherna sågverk och träföretag är beteende och attityder rankat som främsta hindret för energieffektivisering samt stöd från högsta ledningen den största drivkraften för att genomföra energieffektiviseringar.

    Resultat från studien visar också att projekt BEE bidragit med ytterligare kunskap om möjligheten att energieffektivisera, samt även att projektet har medfört ett mer aktivt energieffektiviseringsarbete inom den egna organisationen.

  • 241.
    Tuccella, Simone
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Grid Connection of the Existing Off-grid PV system at Mavuno Secondary School in Tanzania2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The research investigated the grid connection of the existing off-grid PV system at Mavuno Secondary School in Tanzania. The national power grid reached the area during 2015; therefore the grid connection has been studied together with eventual increases of the PV array size. Such research provided a feasibility study in the unexplored topic of connecting stand-alone systems to the national grid once it becomes available.

    The first part of the study aimed to define the load consumptions of the school. On this regard, a measurement system has been set up. It also measured the values of battery state of charge and PV production. The second part involved the modelling and simulations of the system by means of the software HOMER. The existing system has been simulated showing a cost of energy of 0.42 $/kWh. The modelled results showed an overall similarity with the measured values, although some limitations of both measurement system and simulation tools were present. After that, the optimisations of the system regarding future scenarios have been performed. The investigation involved both PV stand-alone and grid connection configurations. Increased load cases and different grid scenarios have been considered. Depending on the load scenarios, the stand-alone system presented a cost of energy between 0.34 $/kWh and 0.55 $/kWh. Instead, depending on load and grid configurations, the grid connected system showed a cost of energy ranging from negative values to 170 $/kWh. The negative values were due to the higher incomes of the sellback compared to the system expenses.

  • 242.
    Turk, Suheyla
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Sustainable Neighbourhood Design in Jakobsgårdarna,Borlänge2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Energy efficient houses benefit communities not only to provide renewable energy shares and surplus electricity to support local economic development. Also, resident in energy efficient houses have less energy usage. However, one of the obstacles of energy efficient technology installment is high investment cost, which are coped with the usage of modular housing by some practices. In Sweden, when it is combined with high housing construction expenses, energy efficient houses cannot be afforded by people having low income. This study develops a scenario to find solutions for affordable housing problem. The aim of this study is to investigate if there are ways of achieving socio-economic mix by the production of energy efficient affordable housing using urban gardening as a strategy for resource efficiency in Jakobsgårdarna. To do this, energy efficient affordable housing with modular units are designed, while analyzing socio-economic structure of neighborhood is analyzed, strategies for local economic are developed and energy efficient affordable housing is designed. This study uses a design-based research method consisting of learning from background cases and implementation of a single case study. Background cases were linked to each other by aspects and features by the literature review and then were used to develop a hypothesis. The lessons learned from literature review examples are used to define sustainable neighborhood. A collaborative ownership; designing common kitchens; producing electricity by solar panels and producing biogas; practicing urban agriculture; waste and storm management and development of land allocation strategies to cross subsidize energy efficient affordable housing production; were defined as sustainability tools for efficient usage of sources. The outcome of this research brings an urban design proposal for Jacobsgårdarna neighborhood development.

  • 243. Turk, Suheyla
    et al.
    Quintana, Samer
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Life-cycle analysis as an indicator for impact assessment in sustainable building certification system: the case of Swedish building market2018In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 153, p. 414-419Article in journal (Refereed)
    Abstract [en]

    This paper assesses the prevailing sustainable building certification systems in Sweden, based on a critical analysis of their characterization for human and environmental impacts through the integration of life-cycle analysis. The aim of this study is to compare sustainable building certifications systems in terms of their assessment categories. In the Swedish market, BREEAM SE, LEED, Green Buildings and Miljobyggnad are the most used building certifications. Therefore, their guidelines are reviewed to evaluate which of them has comprehensively included human health indicators. This research presents useful information for transforming existing and developing future sustainable building certification systems.

  • 244.
    Vangari, Divyanagalakshmi Haribabu
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fathima, Sumayya
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Design of Distributed Rooftop PV System to Minimize Power Cuts for an Indian Village2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    India is a developing country. The national energy production is not enough to fulfill the energy demands of the country. Moreover, there are many villages still needs to be electrified. Among the electrified villages, most of them receive only a few hours of electricity each day making it difficult for people residing there. India has excellent potential for the solar power receiving (4 to 7) kWh/m

    2. Therefore, Government of India sets an ambitious target to install 100 GW of solar capacity by 2022, 40 GW is from rooftop solar. The government is encouraging installation of rooftop PV systems by providing several financial incentives to set up rooftop PV system and policies to purchase the energy. However, the people living in rural areas are not capable of utilizing such financial incentives and understand the procedures due to lack of knowledge and financial ability. Thus, a suitable techno-economical model for grid-connected solar rooftop installations for an Indian village by a third-party investor and project developer is investigated in this thesis.

    The design of a grid-connected rooftop PV system with a battery is considered in this thesis. The sizing of PV system and battery are done based on the village annual day and night load demands. A 72 kW PV system consisting of 3 kW each on 24 roofs is considered to meet the village load demand. Two design methods are discussed for power evacuation from the 72 kW PV system, (1) Centralized design and (2) Decentralized design. In centralized design, all the 3 kW PV strings are connected in parallel to a central inverter, which is integrated with the three-phase grid. A central battery bank is installed and charged by an inverter fed by the utility supply. In decentralized design, the 3 kW PV sting on each roof is integrated to the nearby single phase line through a single phase inverter. The battery bank is equally distributed among the 24 houses, and each battery is charged by a single phase inverter fed by the utility supply.

    The techno-economic study of the two methods are performed, and the key technical and economic performance indices are compared. The assumptions are made wherever needed, and the uncertainties in the inputs data and methods and their impact on the results are discussed. A 10 % of uncertainties in the inputs data for simulations and other parameters are considered for evaluating the impact of PV system performance. The annual produced energy, specific production, and performance ratio for centralized design are 102 MWh, 1411 kWh/kW, and 0.73 respectively. The corresponding performance indices for decentralized design are 108 MWh, 1498 kWh/kW, and 0.77 respectively. The levelized cost of energy and payback period for the centralized design is 3.23 INR and 8 years whereas for decentralized design are 3.13 INR and 7 years for decentralized design by considering 50 % subsidy on the capital cost of the PV system. The payback period increases to 15 years for centralized design and 13 years for decentralized design without any capital subsidy. Therefore, capital subsidy makes the project more attractive to the project investor. The technical and economic performance of the 72 kW PV system with the decentralized design is better than the centralized design, without considering the impact of uncertainty. However, after considering both the positive and negative variation of uncertainty (± 10 %), it is difficult to comment on which design has the better results because both designs have nearly equal range of results.

    The underlying limitations of the study are highlighted, and their impact on the results are discussed. The main limitations are the accurate estimation of load profile and boundary conditions of the village (such as actual dimensions of the house, orientation, and tilt angle of the roofs) to perform the simulations.

    The relevant previous work is cited at appropriate places in the report.

  • 245.
    Verma, Pankaj
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Water saving comparison study between innovative and conventional cleaning systems for CSP technologies2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 246.
    Vidal Lorbada, Ricardo
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Design and implementation of a charge controller with buck converter topology for a Li-ion battery using the component LTC4015.2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report presents the process of design and implementation of a battery charger for a Li-ion battery. The development of this battery charger includes the component from Linear Technology LTC4015. This component integrates the functions of a battery charger configured as a buck (step-down) converter. This device must be integrated in a Printed Circuit Board with a specific design. Also, it must be configured using a microcontroller named Raspberry Pi, which also performs the measurements.

    The method of design is divided in two parts. One is focused on developing the printed circuit board, which includes the simulation of the device and the development of the PCB, and the second one is focused on developing the program used in the microcontroller to manage the operation of the LTC4015.

    The result is a charge controller device that can be used with different configurations with a buck converter topology. The different parts of the design process are the simulation, the design and the implementation. Each of these parts have a section of results in this report. The simulation section includes results obtained with LTSpice and the device LTC4020, which is a similar device to the LTC4015 but without the Maximum Power Point Tracking mode, which is not modelled in LTSpice.

    PV is the main power source considered to charge the battery, and is carefully studied in this project. The PV input is studied with LTSpice, first simulating the I-V curve of the schematic of the solar cell. Second, integrating a solar cell in the simulation of the LTC4015. Third, operating the device LTC4015 with a solar panel that is also characterized.

    The design section includes the electronic components used for the development of the board that integrates the charge controller, the LTC4015 in this case, based on the calculations performed for the requirements of the LTC4015. Finally, the implementation section includes the description of the board implemented but also the description of the configuration and measurement code.

    The conclusions presented in this report show that the LTC4015 is a battery buck charger with different functions that make it suitable to be used in different solar applications. Also, this report opens new future work lines, such as the full characterization of the board, the implementation of a test bench and the integration of the board in different applications for solar energy systems.

  • 247.
    Vijay Vichare, Rohan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Evaluation of Two Solar Heating and Cooling Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main purpose of this study is to compare a heat pump system with a SunCool collector system based on the key performance factors. SunCool collectors are sorption integrated solar thermal collectors which produce both heating and cooling. This analysis is carried out in TRNSYS software. The heat pump system is designed with the PV system and then it’s been simulated in TRNSYS for certain climate conditions. The SunCool collector system has been simulated in the existing TRNSED application by using the TRNSYS input file of the system. The parametric study has also been done to get the ideal size of the system and to check how the system works under different parametric conditions. The results of the simulations have been evaluated in terms of total electric consumption, solar fraction, self-consumption and total energy production. Both systems have been simulated for the location of Madrid, Spain. The same load data has been used in the simulation of these systems.

    A simulation study shows that the heat pump system provides 405 MWh of energy to DHW system per year and 351 MWh of energy to space heating and cooling system per year. The SunCool collector system provides 391 MWH and 101 MWh of energy to DHW and space cooling system respectively. The control system of SunCool collector system doesn’t provide energy to space heating. The heat pump system has a maximum load at night hence during the night it takes electricity from the grid and during the day it gives it back to the grid. Almost 80% of the total electricity load is provided by the grid.

    The comparison study of the simulation results shows that the PV+heat pump system provides the full amount of load while the SunCool collector system provides 97% of DHW load and 51% of cooling load with the same number of collectors. Even though the heat pump provides the full amount of load, the electricity consumption of the system is quite higher at 246 MWh per year although for SunCool collector system it’s just 20 MWh per year. Solar fraction of the SunCool collector system is 64% whereas for heat pump system it’s 17%. Hence to select the feasible option between heat pump system and SunCool collector system, an economic analysis must be done by considering the price of the collectors, feed-in tariff and price of the grid electricity.

  • 248.
    Vijayan, Veenaaishwarya
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Simulation Study for Optimal Inverter Sizing of Grid-Connected PV Systems in Swedish Locations2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In present scenario grid connected photovoltaic systems are widely deployed in towns and cities as they can contribute to better environment. They also have advantage of generating significant quality of energy near the consumption point by avoiding transmission and distribution losses. In any grid connected system one of the main components needed would be the inverter for delivering AC output to the grid. The key issue to have best output merely depends on the sizing of the component. Factors influencing the sizing of the components in the PV system are components technology, climatic aspects of placements of inverter installed and solar radiation distribution characteristics that, of which location and climatologically plays a major role. In places like Sweden and most parts of northern European countries, under sizing of the inverter in PV grid-connected systems is recommended. This is because solar radiation reaches seldom values around 1000 W/m2 which PV modules are rated for. There are also many cloudy days when the inverter would operate in 5-20% of the nominal range where inverter efficiencies are significantly lower than for higher radiation. Thus leading to cost efficient photovoltaic grid connected systems though there might be certain amount of energy losses in the system.

    Operating at higher or lower ranges reduces the efficiencies of inverters to some extend due to technical implications of the device. In this thesis, the optimal sizing factor of inverter will be studied, besides the energy yield, the cost and expected life time of the inverter shall also be taken into account. For more appropriate results three different locations that covers south, middle and north part of Sweden is taken into account. A life cycle analysis is also done based on system yield simulations, data from the literature and cost data provided by the government norms of Sweden.

    The thesis will also investigate on the effect on life time of the inverters data influences the results due to undersize compared to the PV array and how much the maxima smoothes out due the time resolution of the radiation. One hour average data might mislead as it averages out some of the peak radiation. Comparisons between hourly averages and minute wise global solar radiation is done and analyzed.

  • 249.
    Vijayaragavan, Krishna Prasad
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Feasibility of DC microgrids for rural electrification2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    DC system and DC microgrids are gaining popularity in recent times. This thesis suggests a method to state the workability of a DC based PV system using the softwares Simulink, PVsyst and HOMER. The aims of this project include suggesting a DC based architecture, finding out the performance ratio and a cost analysis. The advantages of the DC based system, the cost benefits associated with it and its performance will determine its feasibility.

     

    Not many softwares have the functionality to simulate DC based PV systems. PVsyst is considered as one of the most sought-out softwares for the simulation of PV systems. It can simulate a DC based PV system but has a lot of limitations when it comes to the architecture and voltage levels. Due to these factors, the results from softwares Simulink, Homer and PVsyst are used to calculate the performance ratio of the suggested DC system. 

     

    The simulation of the DC system involves modelling of a DC-DC converter. DC-DC converters are used in HVDC transmission and are being considered for small scale and medium scale microgrids. The DC-DC boost converter is coupled with a MPPT model in Simulink. P and O algorithm is chosen as the MPPT algorithm as it is simple and widely used. The Simulink model of PV array and MPPT based boost converter provides the power output at the needed voltage level of 350V. The input for the Simulink model is obtained from the results of HOMER. The inputs include solar irradiation data and cell temperature. The same input data is used for the simulations in HOMER and PVsyst. The performance ratio is obtained by combining the power output from Simulink with the other aspects of the system from PVsyst. The performance ratio is done only for the month of January due to the limitations in Simulink. The performance ratio is found out to be 65.5 %.

     

    The cost estimation is done for the distribution and power electronics aspects of the system. It is found out that the cost associated with the conductors will have an impact on the total cost

    only if the conductors used for distribution is more in length. The cost associated with the power converters will make a difference in total cost only if the system is within the range of 100kW. The study shows the workability of the PV based DC system based on the above mentioned aspects

  • 250.
    Wallin, Elisabeth
    Dalarna University, School of Technology and Business Studies, Energy Technology. SLU.
    From growth cessation to bud burst: conifer seedling development in response to nursery culture and environmental stimuli2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Sweden, 350-400 million seedlings are produced annually for forest regeneration. About one third of these are overwintered in frozen storage, necessitating accurate methods to assess storability. Young transplants of Norway spruce (Picea abies (L.) Karst.) intended for short-term frozen storage were considered storable before reaching target levels for safe storage using shoot dry matter content, freezing tolerance and the molecular test ColdNSure™. Results also indicated that using shoot dry matter content for storability assessment can be misleading, not only for Norway spruce but also for Scots pine (Pinus sylvestris (L.)). Post-storage vitality can easily and rapidly be determined by measuring the electrolyte leakage from shoots (SEL) of pine and spruce seedlings. SEL and regrowth tests showed that the vitality of young transplants decreased when the time in storage was prolonged from 3-4 to 5-7 months. Short-day (SD) treatment of seedlings shortens the time for dormancy induction and makes seedlings storable at an earlier date. The activity level of dormancy related genes, and genes associated with freezing tolerance reflects the effect of different treatments e.g., the importance of combining longer periods of SD treatment (21-28 days) with low temperature exposure to rapidly obtain storable seedlings. Gene expression profiles have the potential to be used for assessment of seedling dormancy status, predict the development of freezing tolerance, bud set, the risk for a second bud flush in autumn and the timing of bud burst in spring. The interest in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) has increased in Sweden. Frost risks in spring make bud burst timing important when selecting suitable provenances of Douglas-fir for planting. A field trial and a greenhouse study showed the same pattern concerning time of bud burst for a number of Douglas-fir provenances, indicating that greenhouse screening tests can be used for provenance selection. Considering bud burst patterns together with previously reported winter hardening characteristics the interior provenance Three Valley would have a good chance of successful field establishment in southern Sweden.

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