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  • 101.
    Huang, Pei
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. City University of Hong Kong.
    Xu, T.
    Guangzhou University, Guangzhou, PR China.
    Sun, Y.
    City University of Hong Kong, Kowloon, Hong Kong; City University of Hong Kong Shenzhen Research Institute, Shenzhen, PR China.
    A genetic algorithm based dynamic pricing for improving bi-directional interactions with reduced power imbalance2019In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 199, p. 275-286Article in journal (Refereed)
  • 102.
    Johansson Macedo, Liv May
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Modification of a Moving Bed Biofilm Reactor(MBBR) due to radically changed process conditions: A case study of Kvarnsveden paper mill2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Papermaking process require large amounts of energy and water; therefore, pulp and paper

    mills can be potentially very polluting. The wastewater resulting from the papermaking

    process must be carefully managed as it is very rich in dissolved organic matter and contain

    compounds that make it difficult to treat. MBBR technology emerged as a possibility to

    increase the treatment capacity and to make more compact treatment systems designed to

    remove high organic loads, since in addition to having biomass in suspension as the

    activated sludge process, also has biomass adhered to plastic supports. This research was

    commissioned by Stora Enso Kvarnsveden and emerged in need of a bioreactor

    modification due to reduction of the wastewater load after the closure of PM11 in 2013 and

    PM8 in 2017. An evaluation of the performance of bioreactors is necessary with possible

    results to only run one bioreactor in the future and save energy. For performance analysis,

    two weeks of measurements were performed, one with the two bioreactors running at the

    same time and one with only K150 reactor running, trying to simulate what happens if one

    of them is stopped. Analysis of the main operating parameters of the MBBR system were

    evaluated during this research. As result, it was recommended an action to remove the

    excess of adhered biomass and an increase of the filling rating to 50%, in order to optimize

    TOC reduction.

  • 103.
    Johari, Fatemeh
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Predictive Control Strategies for aHeat Pump System with PV and Electrical Storage with Various Boundary Conditions2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The idea of nearly zero energy building (nZEB) has been emerged from the global trend toward reduction in fossil fuel consumption and green-house gas emission. In spite of different definitions for nZEB, it is vastly known as a grid connected building with highly reduced energy consumption by means of on-site renewable energy production. Accordingly, heat pumps are one of the remarkably efficient heating and cooling technologies considered as the promising components of the nZEBs, specially, when they are associated with the renewable energy systems. However, due to the interaction between heat pump, PV and the grid, the efficiency and the electrical self-consumption of the system strongly depend on the advanced controller strategies such as predictive controllers using price and weather forecast services. Although design of the control algorithms is a very challenging procedure, evaluation of the functionality of these defined algorithms is of paramount importance as well.In this thesis, the robustness of the pre-defined price and weather predictive controllers is studied by testing the performance of a heat pump system for different boundary conditions and compare the results with a reference case study. The base case is a heat pump system for a single-family house with the total heating floor area of 143 m2 and the annual heating demand of 100 kWh/m2.year. The building is located in Norrköping, Sweden and it is assumed that a family of 4 (parents and 2 children) are living in the house. The associated 5.7 kW PV system is mounted on the south oriented roof with the slope of 27˚. Moreover, the system has a storage tank with the total capacity of 180 liter for DHW and a 7.2 kWh battery bank increases the amount of harvested solar energy.The identified methodology of this thesis suggests evaluating the system for the range of variables and boundary conditions, included the climate, thermal properties of the building, orientation and slope of the roof of the building, room set temperature and the occupancy of the building which leads to the various DHW and electricity load profile. Moreover, to study the influences of the controllers on the system, a group of performance indicators are defined. PV self-consumption, solar fraction, final energy use, annual net cost of electricity and seasonal performance factor of the system are considered as the key figures of this study. Next, it aims to do the sensitivity analysis of the system with and without controllers under various boundary conditions. For this purpose, the TRNEdit, as one of the TRNSYS tools which is extended purposely to edit TRNSYS files and manage the parametric simulation studies, is used. Finally, the results from the parametric studies of the system is evaluated to examine the robustness of the controllers.Consequently, the acquired results from the sensitivity analysis of the system with the introduced predictive controllers proves that the performance of the system successfully promotes when it utilizes predictive strategies of PV generation and electricity price. However, the suggested control algorithms need to be slightly modified in order to achieve better results when they operate simultaneously.

  • 104.
    Jordan, Ulrike
    et al.
    Kassel University.
    Vajen, Klaus
    Kassel University.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Cortés Forteza, Pau Joan
    SAMPOL Ingeniería y Obr.
    Frank, Elimar
    University for Applied Sciences Rapperswil.
    Furbo, Simon
    Technical University of Denmark.
    Kerskes, Henner
    Stuttgart University.
    Heinzen, Roland
    FSave Solartechnik GmbH.
    Luke, Andrea
    Kassel University.
    Martinez-Moll, Victor
    University of the Balearic Islands.
    Pietschnig, Rudolf
    Kassel University.
    Streicher, Wolfgang
    University of Innsbruck.
    Wagner, Waldemar
    AEE Intec.
    Witzig, Andreas
    Vela Solaris AG.
    SOLNET - PhD-Scholarships and courses on solar heating2014Conference paper (Other academic)
    Abstract [en]

    SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference-accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, “SHINE”, was launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat for industrial processes, as well as sorption stores and materials started in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects will be hosted by six different universities and five companies from all over Europe.

  • 105.
    Jordan, Ulrike
    et al.
    Kassel University.
    Vajen, Klaus
    Kassel University.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Forteza, Pau Joan Cortés
    SAMPOL.
    Drück, Harald
    Stuttgart University.
    Frank, Elimar
    University for Applied Sciences Rapperswil.
    Furbo, Simon
    Technical University of Denmark.
    Heinzen, Roland
    FSave Solartechnik GmbH.
    Luke, Andrea
    Kassel University.
    Martinez Moll, Victor
    Balearic Islands University.
    Pietschnig, Rudolph
    Kassel University.
    Streicher, Wolfgang
    University of Innsbruck.
    Wagner, Waldemar
    AEE Intec.
    SolNet - PhD-scholarships and courses on Solar Heating2013In: ISES SWC2013, Freiburg, 2013Conference paper (Other academic)
    Abstract [en]

    SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference-accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, "SHINE", will be launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat for industrial processes, as well as sorption stores and materials will be offered, starting in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects will be hosted by six different universities and five companies from all over Europe

  • 106.
    Joudi, Ali
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Svedung, Harald
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Highly reflective coatings for interior and exterior steel cladding and the energy efficiency of buildings2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 12, p. 4655-4666Article in journal (Refereed)
    Abstract [en]

    The effect of surface heat-radiation properties of coil-coated steel cladding material on the energy efficiency of buildings in Nordic climate is addressed by parallel temperature and energy usage measurements in a series of test cabins with different exterior solar reflectivity and interior thermal reflectivity. During one year, a number of one- or two-week experiments with air conditioner cooling and electrical floor heating were made while logging air-, radiation- and surface temperatures, energy consumption and weather conditions. Measurements show significant energy savings in the test cabins by the use of high thermal reflectivity interior surfaces both during heating and cooling and a strongly reduced cooling demand by the use of high solar reflectivity exterior surfaces. Results are interpreted within the context of a steady-state energy flux model, to illuminate the importance of surface resistance properties (radiation and convective heat dissipation).

  • 107.
    Joudi, Ali
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Svedung, Harald
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Energy efficient surfaces on building sandwich panels: a dynamic simulation model2011In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 43, no 12, p. 3736-3736Article in journal (Refereed)
    Abstract [en]

    The choice of building envelope is critical for the energy performance of buildings. The major part of the energy used by a building during its lifetime is used for maintaining a suitable interior thermal climate under varying exterior conditions. Although exterior heat radiation properties (i.e. total solar reflectivity and long wave thermal emissivity) have been well accepted to have a large impact on the need for active cooling in warmer climate, the effect of a reduced thermal emissivity on interior surfaces on the building thermal energy flux is rarely studied. This paper addresses the sensitivity of the thermal energy flux through a sandwich panel, by systematically varying the surface thermal emissivity (both interior and exterior) and total solar reflectance of exterior surface, for three geographical locations: southern, middle and northern Europe. A model is introduced for calculating the effect of both interior and exterior optical properties of a horizontal roof panel in terms of net energy flux per unit area. The results indicate potential energy saving by the smart choice of optical properties of interior and exterior surfaces.

  • 108.
    Kabanshi, Alan
    et al.
    HiG.
    Sattari, Amir
    Dalarna University, School of Technology and Business Studies, Construction.
    Linden, Elisabet
    HiG.
    Wigö, Hans
    HiG.
    Sandberg, Mats
    HiG.
    Experimental study on contaminant entrainment in air distribution systems with free jets2017Conference paper (Refereed)
  • 109.
    Khadra, Alaa
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Economic Performance Assessment of Three Renovated Multi-Family Houses with Different HVAC Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since the building sector is responsible for 40% of the energy consumption and 36% of

    CO2 emissions in the EU, the reduction of energy use has become a priority in this sector.

    The EU has adopted several policies to improve energy efficiency. One of these policies

    aims to achieve energy efficient renovations in at least 3% of buildings owned and

    occupied by governments annually. In Sweden, a large part of existing buildings was built

    between 1965 and 1974, a period commonly referred to as ‘miljonprogrammet’. Stora

    Tunabyggen AB, the public housing company in Borlänge municipality, begun a

    renovation project in the Tjärna Ängar neighborhood within the municipality with the

    greatest share of its buildings stock from this period. The pilot project started in 2015. The

    aim of this project was to renovate three buildings with similar measures, that is, by

    adding 150 mm attic insulation, replacing windows with higher performing ones (U-value

    1 W/m

    ²K), by adding 50 mm of insulation to the infill walls and by the installation of flowreducing

    taps. The essential difference between the three renovation packages is the

    HVAC systems. The selected HVAC systems are (1) exhaust air heat pump, (2) mechanical

    ventilation with heat recovery and (3) exhaust ventilation. Life cycle cost analysis was

    conducted for the three building and sensitivity analysis for different values of discount

    rate and energy price escalation was performed. The study found that the house with

    exhaust ventilation has the lowest life cycle cost and the highest energy cost. The house

    with exhaust air heat pump has 3% higher life cycle cost and 18% lower energy use at 3%

    discount rate and 3% energy price escalation. The study found that mechanical ventilation

    with heat recovery is not profitable, although it saves energy. The sensitivity analysis has

    shown that the possible increment of price energy and lower discount rate give higher

    value for the future costs in life cycle cost analysis. This lead to the main finding of this

    thesis, which is that exhaust air heat pump is the best choice for the owner according to

    the available data and the assessed parameters.

  • 110.
    Kießling, Ralf
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Adiabatic Precooling for CoolingTowers – Measurements andAnalysis of Impact on SolarDriven Chiller2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today most of cooling demand is satisfied with electrically driven compressor chillers. Due to global warming, cooling demand will increase worldwide. Therefore alternative refrigeration methods need to be improved to preserve limited energy resources. One opportunity is thermally driven chillers, which perform absorption cycle process. In this principle main energy input is done by heat and only a little electricity. This heat can be either produced conventionally by combustion or sustainably with solar thermal collectors. Like any other electrical driven chiller, all heat brought into the process need to get rejected by a recooler. In case of thermally driven chiller, heat rejection amount is much higher. This causes higher system cost compared to electrical driven chiller and blocks larger market diffusion of thermally driven chiller. Therefore improved heat rejection concepts are necessary also to maximise solar utilisation.In this thesis measurements were performed on a dry cooling tower extended with an adiabatic precooling system to increase recooling capabilities. This system has a simple and cheap design and needs less maintenance to remain hygienic quality. During measurements a correlation between evaporation water flow and fan speed to heat rejection was found and with normalisation it was possible to predict heat rejection dependent on these two operation factors for given ambient air conditions. At the start, measurements were performed and the test rig was evaluated to ensure high accuracy. The sensor alignment in the test rig was insufficient; therefore evaporation, which causes precooling effect, was calculated instead measured by relative humidity sensors.The measurements attest that the system has high precooling effectiveness up to 10 K below ambient temperature for appropriate conditions. Under such conditions almost doubled heat rejection was measured.To quantify the impact to a thermally driven chiller supplied by solar heat on a theoretical basis, a model including solar thermal collector and cooling tower was developed. Extended with meteorological data for a chosen location, supplied cold of the chiller and consumed electricity for the cooling tower fan was calculated for a single day and for period of one year. Using adiabatic precooling enables two optimisation methods; first increased chillers cold output and second reduced electrical fan consumption. Here simulation has shown huge electrical energy saving potential of sixty-nine percent on the one hand, or nine percent more supplied cold on the other hand compared to ordinary dry recooling. However while analysing results for increasing supplied cold, it was found a high dependency to available heat produced by solar thermal collectors.In future work, the adiabatic precooling system should prove its advantages in a field study to achieve knowledge about its long term behaviour

  • 111.
    Korde, Anukool
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Assessment of a Solar PV Re-Powering Project in Sweden Using Measured and Simulated Data2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Re-powering solar PV plants is an upcoming discussion on the global stage. Although the respective component warranties indicate the time to change the system machinery, the methodology and justification for carrying this out are two aspects that need further study.

    The rooftop solar PV system on top of Dalarna University was re-positioned in 2014. Prior to installing the system in its new position, the system arrays were reconfigured and new inverters were installed.

    This thesis aimed to compare and analyze two sections of the solar power plant to understand which amongst them performs better. Graphs depicting energy, current, voltage and other parameters were formulated to ascertain the efficacy of the array configurations for this Nordic latitude.

    Thereafter, PVsyst and SAM were used to compare the simulated results with the actual output from the system.

    It was found that the measured energy output from one section of the solar power plant was higher than that of the other during 2014. On an annual basis, this difference was 21.5 kWh or 2%. On closer inspection, this contrast was attributed to a difference in yield early in the morning.

    Further, PVsyst simulated the annual energy with a deviation of less than 1% than what was measured, whereas SAM measured a deviation in energy measurement of 2.5% higher than the actual measured energy. These values were obtained using the detailed design options for both softwares. A point to keep in mind is that prior experience of working with both these softwares is recommended prior to carrying out the simulations on these softwares.

    An underlying point to note in this study is its limitations. This study is valid in the northern latitudes, such as the Nordic climates, since other regions would not have such low (sub-zero) temperatures to account for while sizing the inverter. In regions of high irradiance, a system re-powered in a way such as the system in this case would have higher clipping losses.

    Relevant previous studies and related topics have been visited, summarized and cited.

  • 112.
    Kuhn, Tillmann
    et al.
    Fraunhofer ISE.
    Fath, Karoline
    Fraunhofer ISE.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Nouvel, Romain
    ZAFH.
    Fedrizzi, Roberto
    EURAC.
    D2.3 RES availability survey and boundary conditions for simulations2014Report (Other academic)
  • 113.
    Kumar, Pankaj
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Performance Evaluation of High Temperature Steam Generating Solar Collectors2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Absolicon Company in Härnösand have developed a solar collector field with high performance parabolic solar collectors to generate high temperature steam of around 160°C which could be directly used for industrial application. This project work involves thermal and optical performance evaluation of the collector field to check the collector performance.

    The solar collector field is set up in Härnösand, Energy Park; the collector field consists of 8 parabolic solar collectors with a sun tracking mechanism. The sun tracking is provided by 4 different actuators. The parabolic collectors are imaging type and line focus. The heat transfer fluid is circulated through the collector circuit with the help of a variable flow pump, which varies its flow rate based on the solar irradiation values.

    This project work includes, conducting the literature review and developing a test rig for testing of the collector field as per the EN12975 standards, 2006 (steady state testing) for solar collector testing. The thermal and optical performance evaluation of the collector field has to be evaluated along with the determination of the radiative, conductive and convective heat loss coefficients.

    In the test work, the thermal performance is determined by measuring the heat energy gained by the heat transfer fluid (HTF) in the system on a clear sunny day at solar noon period. The heat loss coefficients are calculated by circulating a constant temperature HTF into the collector circuit as per the EN12975, (2006) standards and then curve tracing was done to obtain the value of heat loss coefficients. The peak optical efficiency was determined by testing the collector at solar noon period under steady state conditions as per the standards.

    Matlab simulation analysis was also performed as a part of this project work to check the effect of changing incidence angle of solar radiation on the solar collector surface to determine the IAM for the collector field. Effects on the results were also determined due to the sensor errors and sensitivity analysis of the system was also performed.

  • 114.
    Kurdia, Ali
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Consequences of Nordic Conditions on the Performance of Large-Scale Building Applied PV Installations2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis aimed for a better understanding of the Nordic weather conditions in terms of snow induced soiling on the performance and production of an established photovoltaic plant located on the roof of Økern nursing home, Oslo.

    In order to realize the main aim, several steps had to be done in preparation of the main analysis, these steps in fact are as important to this thesis as the main deliverable.

    The search for appropriate meteorological data proved to be not an easy task because of the scarcity of ground measurement stations, and the high inaccuracies in satellite observations.

    After analyzing all the sources with available data for the region of Oslo, three sources of data were chosen based on comparisons to an onsite set of reference measurements, these are the Blindern meteo station, the NASA SSE satellite derived observations, and the STRANG data base.

    A model of the actual system was created in PVsyst, exceptional attention to the level of detail was exercised in order to approach the case of eliminating any source of variation in the simulated models other than the required study parameter, the soiling.

    Simulations of many system variants ultimately resulted in the aggregation of a soiling loss profile to be used in conjunction with each of the meteo sources to predict the snow induced soiling consequences on the system.

    The soiling loss profiles were tested and the results compared to actual system production measurements, and it was successful in introducing the correction the model needed to simulate the system closely to reality.

    However, absolute change in production figures is relatively small, therefore, this study and any future continuation of it is oriented into research and improvement as it possess minimal impact on a commercial application.

  • 115.
    Lang, Markus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Performance Study of a PVT Air Collector2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    PVT collectors are more and more in focus as they combine electricity generation and generation of heat in one single collector. In this thesis a thin film CIGS PV module is used to replace a conventional solar absorber and create an air ventilated PVT collector. The thesis includes the design and construction of the collector, measurement of important performance parameters as well as analysis of the collected data in terms of thermal and electrical performance.

    A Solibro CIGS PV module is used as solar absorber and a wooden box is constructed around the module. An electric fan is used to control air flow behind the PV module. Inlet and outlet air temperatures of the collector are measured as well as the temperatures of the backside of the PV module and the opposite wall in the air channel and logged together with irradiance level every ten seconds during a period of one week.

    During the measurement period with clear sky conditions quite constant irradiance levels can be measured resulting in a temperature increase between inlet and outlet air temperature of 22 °C. PV module temperatures reached values up to 60 °C while the outlet temperature reached 45 °C. Thermal power reached values above 300 W/m² and efficiency was calculated to 0.33 for high periods with high irradiance (900 W/m).

    Infrared images of the collector show that the heat distribution on the PV module was quite uniform which means that also air flow behind the module can be considered uniformly distributed. Only a small area around the air inlet showed slightly lower temperature levels compared to the opposite side at the same level.

    Electrical performance was analyzed theoretically by comparing output levels under conditions of forced ventilation and with natural ventilation. The temperature difference achieved by the cooling effect on the module by the forced airflow accounted for an increase of about 6 % of power output. In absolute numbers however the needed power for the fan is higher compared to the gain in electricity output from the 100 Wp PV module.

    It can be seen that measured outlet temperatures were slightly delayed compared to corresponding irradiance levels and the temperature changes are less fluctuating thus smoothened compared to the fast changing irradiance values. Pressure drop in the collector is a limiting factor that requires a minimum air gap diameter for a certain airflow.

    Using a CIGS PV module is a suitable option to replace a conventional absorber in a solar collector if the benefit from the produced electricity is of use and maximum thermal output is not the major concern. To achieve higher temperatures air flow needs to be decreased which will have a negative impact on the total electricity output.

    In terms of using such a collector for solar drying it depends on the prevailing climate conditions if desired temperature levels can be reached. The electricity produced by the PV module could directly be used to power an electric fan and in a further step could open for the option to control air flow and air temperature into the drying chamber.

  • 116.
    Lehnberg, Isak
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Uppföljning av fastighet med värmelager2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Gamla byn AB is a municipal housing-company in Avesta. In 2015 they built a nursery school named Rödluvan in Horndal outside of Avesta, as a new building in their property stock. Rödluvan was provided with a relatively new heating system named ASES (Active Solar Energy Storage) which is a solution by Norconsult. The heating system is mainly made up by a heat storage under the building, solar collectors and a heat pump. The solar collectors provides the storage with heat which is then collected by the heat pump when needed. Gamla byn wants an evaluation of how the system has performed so they can decide if ASES is to be used on additional buildings. During 2018 a thesis and an energy declaration was done, and they showed that the heating system used twice as much energy than was planned. They also presented action proposals in terms of optimization of the ventilation, which was later carried out by Gamla byn. A storage tank was also installed during 2018 to help balance the heating system. This was done after the thesis and energy declaration.

    This thesis is executed as a quantitative case study on the nursery school Rödluvan, on order of Gamla byn, since a new evaluation was of interest. A lot of information has been collected on the energy use in the building and during the progress of the thesis it has emerged that the energy use has reduced considerably since spring 2018. This thesis has had access to a lot more information on the readings of the system compared to the previous evaluations and it has proved that some corrections has been needed on the readings to obtain the true energy use of the heating system. The energy declaration and the previous thesis showed that the value to heating and warmwater was 33 kWh/m2 , year, compared to the planned value of 15 kWh/m2 , year. Since the energy use has reduced considerably since they were written and some corrections has been done on the readings, the value in this work is closer to the planned value. Including energy use of an electric boiler, which has only been running a few times when the heat pump has not functioned properly, the energy use to heating and warmwater amounts to 26 kWh/m2 , year since 2015. If the electric boiler is excluded, considering that it has not been running since the energy use was reduced during 2018, the energy use to heating and warmwater has been 24 kWh/m2 , year since 2015. Complete readings are missing in order to measure the true energy use to heating and warmwater during one year since April 2018. Readings from the recent winter combined with estimations of the energy use during the remaining months based on values of previous years, it shows that the energy use the most recent year to heating and warmwater has been about 19 kWh/m2 , year. With complete readings for a whole year, combined with further optimization of the ventilation, the value probably reduces further. The conclusion is that the heating system doesn’t seem to have worked optimally, but since the previous evaluations in 2018 the energy use has reduced considerably, and the new value is much closer to the planned. This presumes that the heating system continues to function at least as well it has the recent year.

  • 117.
    Leidi, Johan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The exchange-value of solar thermal energy2007In: ISES Solar World Congress 2007, ISES 2007, 2007, Vol. 4, p. 2961-2965Conference paper (Refereed)
    Abstract [en]

    In Sweden there is a tendency that alternative energy will develop on market premises. In this paper I suggest that the low exergy value of solar thermal heat limits the technique's commodification, i.e. the possibility of having a commercial exchange-value on the market. Anthropologists argue that value of a commodity has to be related to social and cultural aspect of the society where it is situated. By applying anthropological theories of value on solar thermal energy I propose that we also need to include the solar thermal energy's physical conditions to understand its potential of becoming a commodity in the society where it is supposed to produce action.

  • 118.
    Leppin, Lorenz
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Development of Operational Strategies for a Heating Pump System with Photovoltaic, Electrical and Thermal Storage2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study describes the development of operational strategies for an exhaust air heat pump system that supplies space heating and domestic hot water. The system combines photovoltaic power production with two different storage types. These are electrical storage using batteries and thermal storage in using a domestic hot water tank and in form of the thermal capacity of the building. The investigation of the control strategies is carried out for a detailed single family house model in Sweden in the simulation software TRNSYS. The overall aim of the control strategies is to improve the performance of the energy system in terms of self-consumption, self-sufficiency, final energy and seasonal performance factor. Three algorithms are developed and compared to a base case without additional control. The first algorithm only uses the thermal storage in the hot water tank and the building. The second uses only the battery to store the photovoltaic electricity. The third control algorithm combines both storage types, electrical and thermal.

    The simulation results show that for the studied system the energetic improvement is higher with the use of electrical storage compared to using thermal storage. The biggest improvement however is reached with the third algorithm, using both storage types in combination. For the case of a photovoltaic-system with 9 kW and battery store with 10.8 kWh and a 180 l hot water store the self-consumption reaches up to 51% with a solar fraction of 41 %. The reduction in final energy consumption for this case is 3057 kWh (31 %) with the heat pump having a seasonal performance factor of 2.6. The highest self-consumption is reached with a photovoltaic-system of 3 kW and battery store with 3.6 kWh, which comes to 71 %.

  • 119. Letz, Thomas
    et al.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Perers, Bengt
    A new concept for combisystems characterization: the FSC method2009In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 83, no 9, p. 1540-1549Article in journal (Refereed)
    Abstract [en]

    Solar combisystems are relatively complex systems with many different components and operational parameters. Before the beginning of IEA-SHC Task 26 ("solar combisystems"), no method was available with which they could be compared. The well known "f-chart" method was introduced by Duffie and Beckman already in the seventies, but was only useful for dimensioning generic combisystems, with a defined hydraulic scheme. It didn't give a method to compare different designs. The objective of this work was to develop a simple tool for characterizing the performance of these systems. The method used was to analyse the comprehensive simulation results of Task 26 and to look for relationships between the key external factors of climate and load, and the system performance. The result is a new and simple methodology for characterization of solar combisystems, called the fractional solar consumption (FSC) method. FSC is a dimensionless quantity, which takes simultaneously into account the climate, the space heating and domestic hot water loads, the collector size, its orientation and tilt angle, but which does not depend on the studied system design. The study shows that fractional energy savings, with and without parasitic energy included, can be expressed as a quadratic function of FSC. The relationship was shown to be valid for a wide range of conditions, but to be limited for certain parameters such as collector orientation and hot water load. The method has been used to create a nomogram and the computer design tool CombiSun.

  • 120. Li, G.
    et al.
    Tang, L.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dong, J.
    Xiao, M.
    Factors affecting greenhouse microclimate and its regulating techniques: a review2018In: IOP Conference Series: Earth and Environmental Science, 2018, Vol. 167, no 1, article id 012019Conference paper (Refereed)
    Abstract [en]

    This paper reviews factors affecting greenhouse microclimate and its regulating techniques towards upgrading the greenhouse applications in the area of southeast China which have little or very basic technology integration. The microclimate of greenhouse is apparently influenced by the shape and its orientation, the wind direction, the property of covering material, and the use of insect-proof screen as they eventually affect the total solar radiation, the thermal characterises, and the flow pattern inside. The natural ventilation and sun block are the most common method to cool the greenhouse, but more efficient evaporative cooling such as pad-fan system, misting/fogging system and roof sprinkler are required with extreme temperatures. The earth to air heat exchanger and the heat storage using phase change material may be used for heating or cooling throughout the year which are more economic and energy-saving than other traditional thermal technologies. The reviewed knowledge provides insights into upgrading greenhouse applications in Ningbo area towards more sustainable and efficient greenhouse farming.

  • 121. Li, Guozhen
    et al.
    Tang, Llewellyn
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Xiao, Manxuan
    Dong, Jie
    Effect of solar radiation and natural ventilation on temperature distribution in a greenhouse: a numerical study2017Conference paper (Refereed)
  • 122.
    Lidberg, Tina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ramírez Villegas, Ricardo
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Olofsson, Thomas
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Eriksson, Ola
    University of Gävle.
    AN APPROACH TO ILLUSTRATE STRATEGIES FOR IMPROVED ENERGY EFFICIENCY AT THE MUNICIPAL LEVEL2014In: Proceedings from the 14th International Symposium on District Heating and Cooling: Proceedings from the14th InternationalSymposium on District Heating and Cooling September, 6-10, 2014 Stockholm, SWEDEN / [ed] Anna Land, Swedish District Heating Association, 2014, p. 50-55Conference paper (Refereed)
  • 123.
    Lindberg, Eva
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Past and future of European Solar Energy School2007In: Proceedings of ISES Solar World Congress 2007: Solar energy and human settlement, vols I-V, 2007, Vol. 4, p. 3014-3018Conference paper (Refereed)
    Abstract [en]

    The European Solar Engineering School ESES is a one-year master program that started in 1999 at the Solar Energy Research Center SERC, Dalarna University College. It has been growing in popularity over the years, with over 20 students in the current year. Approximately half the students come from Europe, the rest coming from all over the globe. This paper describes the contents and experiences from eight years of running the programme an the adapting the programme to the Bologna process. The majority of the students from ESES have found work in the solar industry, energy industry or taken up PhD positions. An alumni group has been started that actively gives support to past, present and potential future students.

  • 124. Liu, Haoyang
    et al.
    Zhang, Xingxing
    Saffa, Riffat
    A Novel Vacuum Window System2011In: Proceeding 10th International Conference on Sustainable Energy Technologies, Istanbul, Turkey, 04th -07th September 2011, 2011Conference paper (Refereed)
  • 125. Liu, Shengchun
    et al.
    Hao, Ling
    Rao, Zhiming
    Zhang, Xingxing
    University of Nottingham.
    Experimental study on crystallization process and prediction for the latent heat of ice slurry generation based sodium chloride solution2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 185, p. 1948-1953Article in journal (Refereed)
    Abstract [en]

    The research on the crystallization process is a fundamental task for the investigation of freezing properties of ice slurry. This paper presents an experimental study on the influence of concentration on essential parameters of the crystallization process for the ice slurry produced from sodium chloride solution using a scraped surface heat exchanger. It was found that the liquid temperature experiences four different segments during the whole crystallization process. This trend keeps accordance with the result from literature and it was used to verify the accuracy of the experiment test. It was also observed that the concentrations of sodium chloride solution have significant effects on several freezing properties of the ice slurry generation. The curves obtained in this paper are useful to predict the freezing point and the solidification time in practice. Additionally, a mathematical correlation between the latent heat and concentration was developed eventually by polynomial fitting the curve gained from experiments. The error between the fitting curves and original experimental data was no more than 5%. Totally, during the ice generation process, it is of great significance that the concentration of brine solution can be adjusted to meet the cooling capacity requirement according to the fitting curves and mathematical correlations obtained in this paper.

  • 126. Liu, Xuezhi
    et al.
    Liu, Huolong
    Zhang, Xingxing
    University of Hull.
    Zhao, Xudong
    Transmission network expansion planning by improved simulated annealing approach2014In: SOP Transactions on Power Transmission and Smart Grid, ISSN 2380-0003, Vol. 1, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    The transmission network expansion planning problem is effectively solved by the improved simulated annealing approach. A mixed integer nonlinear programming model of this problem is formulated using the DC power flow model. The detailed process of simulated annealing algorithm has been improved, and applied to 6-bus and 24-bus systems. The solutions obtained by the improved SA approach are compared with solutions found using LINGO software. Numerical results have shown that the proposed approach requires less time to obtain local optimal solutions.

  • 127. Liu, Xuezhi
    et al.
    Zhang, Xingxing
    University of Hull.
    Zhao, Xudong
    Liu, Huolong
    Damping control for power system based on state observer2014In: SOP Transactions on Power Transmission and Smart Grid, ISSN 2380-0003, Vol. 1, no 1, p. 9-19Article in journal (Refereed)
    Abstract [en]

    In this work, design of damping controller for Power System based on state observer is studied. The linearized state equation model of multi-machine power system is built, which includes four-order generator model and three-order excitation model. The power system damping characteristic is improved using feedback control based on the states that are estimated by full-order and reduced-order observer. The simulation results using a four-machine two-area system is utilized to validate the effectiveness of the proposed method.

  • 128.
    Lorenz, Erik
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dahlin, Frida
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fossilfri Fjärrvärme: Möjligheter till konvertering av fossila spetslastpannor hos Falu Energi och Vatten2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    After the Paris climate agreement, the requirements were raised on the district heating sector in Sweden to eliminate the fossil fuels from the production. This concerns mainly the peak load production during cold season when the fossil boilers are needed the most. To get rid of the peak load production of fossil fuels, it is necessary to find an alternative way of producing the heat that still fulfill the requirements on the boilers. You often need to have a flexible load control and a quick startup of the boiler. It is possible to convert a fossil boiler to be able to use bio oil or bio diesel, more or less keeping the same properties of the boiler. The requirements on the system in such a conversion is dependent on the fuel and its properties. In this study the definition of fossil free district heating refers to only the fuel used for production.

    "Falu Energi och Vatten" (FEV) is a district heating company in a town called Falun in Sweden. They use approximately 3 % fossil fuel (liquefied petroleum gas and heating oil 1) of the energy used for district heat production and have the ambition to be fossil free. The district heating grid in Falun has been studied to examine the economic consequences of a conversion of fossil boiler for peak load production. The technical requirements that leads to economic consequences have also been studied.

    By studying literature and contacting some technology providers, fuel providers and other heat producers the costs that will be affected by the conversion has been obtained. Three different fuel choices in a boiler conversion have been studied; MFA, RME and HVO. To evaluate the economic consequences, a Life cycle cost analysis (LCC) has been used. Apart from the three different choices of fuel, an LCC has also been calculated for a scenario where you keep using fossil fuels. A sensitive analysis has also been made where different energy demands, prices for energy and the cost of capital have been studied.

    The results show that all the different choices of bio fuels studied for a conversion is more expensive than keep on using the fossil fuels for FEV. MFA has the lowest LCC, but the largest investment. The price for HVO and the taxes when used for heating makes it substantially more expensive than the other fuels. The sensitive analysis shows that the price of energy and energy demand in the future is crucial for the economic consequences. These must change substantially if the investments are to be considered profitable during the calculation period of 10 years. MFA has a lower LCC the greater the energy demand is for FEV in the future. RME has a lower LCC the lesser the energy demand is.

    It has emerged that the necessary measures and costs for a conversion of boilers differs a lot depending on local pre-conditions of the boilers and the storage of fuels. The calculations are based on several assumptions making the results uncertain and should be handled with caution.

    The results are also specific to the conditions of FEV which should be considered before the results can be applied under other circumstances.

  • 129.
    Lorenz, Klaus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Solvärme i flerbostadshus2014Report (Other academic)
    Abstract [sv]

    I detta arbete har utbyte och kostnader för solvärme kopplat till fjärrvärmeanslutna fastigheter analyserats. Inledande refereras olika kopplingsförslag som Svensk Fjärrvärme rekommenderar. Mätningarna på primärinkopplade solvärmesystem (där systemet levererar till fjärrvärmenätet), som nyligen har sammanställts i ett Fjärrsyn projekt aktualiserar frågeställningen i vilka fall solvärmen bör kopplas in med primär- respektive med sekundärinkoppling. Skillnaden är system med ackumulatortank som minskar inköpt fjärrvärme å ena sidan (sekundärinkoppling) och system som matar solvärmen in i fjärrvärmens primärledning å andra sidan. I både fallen förbättras fastighetens energiprestanda enligt den svenska definitionen, som baseras på inköpt energi.

  • 130.
    Lorenz, Klaus
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Välja värmesystem för villan: Enkla tips som sparar miljön och ger valfrihet inför framtida förändringar2005Book (Other academic)
    Abstract [sv]

    "Välja värmesystem för villan" är en populärt skriven tvärvetenskaplig skrift. Villahushåll som planerar att förändra sitt värmesystem får konkreta tips och råd som utgår från deras egen situation. De får rådet att tänka långsiktigt och undvika fallgropar som gör värmesystemet svårt att förändra. Skriften är den första delen i en serie om flexibla värmesystem. Den andra delen vänder sig till installatörer.

  • 131. Lu, Lu
    et al.
    Yan, Yuting
    Zhang, Xingxing
    Li, Junming
    Zhao, Xudong
    Theoretical Study on City Gas Pipeline Leakage and Diffusion2013In: Proceeding 13th International Conference on Sustainable Energy Technologies, Hong Kong, 28th -30th August 2013, 2013Conference paper (Refereed)
  • 132. Lu, Lu
    et al.
    Zhang, Xingxing
    University of Hull.
    Yan, Yuting
    Li, Jun-Ming
    Zhao, Xudong
    Theoretical analysis of natural-gas leakage in urban medium-pressure pipelines2014In: Journal of Environment and Human, ISSN 2373-8324, Vol. 1, no 2, p. 71-86Article in journal (Refereed)
    Abstract [en]

    With widespread deployment of the urban natural gas industry, the energy security is now becoming one of the priorities in practice. Gas leakage may occur from the pipeline during the collection and transportation process. This article therefore presented a theoretical study on the urban natural gas pipeline leakage in order to provide the basic theory of the rescue policy making in emergent occasions. The investigation was undertaken through the fundamental analysis based on derivation of gas leakage models. The gas leakage model was applied to analyze the pressure, temperature and flow rate of gas leakage over time under both the steady-state and dynamic conditions. Two main impacting factors, pressure and hole size, were subsequently discussed. It is concluded that for the steady leakage the flow rate increases with the increase of pipeline pressure and hole size. And the distribution of pressure, temperature, density and velocity were calculated along the pipeline. For the unsteady leakage, the time of leakage is very short under different initial pressure and hole size, and the total leakage and average leakage rates were analyzed.

  • 133. Lu, Lu
    et al.
    Zhang, Xingxing
    Zhao, Xudong
    Numerical simulation of gas pipeline leakage and diffusion2014Conference paper (Refereed)
  • 134.
    Luthander, Rasmus
    et al.
    Uppsala universitet, Fasta tillståndets fysik.
    Psimopoulos, Emmanouil
    Dalarna University, School of Technology and Business Studies, Energy Technology. Uppsala universitet, Fasta tillståndets fysik.
    Widén, Joakim
    Uppsala universitet, Fasta tillståndets fysik.
    Demand Side Management Using PV, Heat Pumps and Batteries: Effects on Community and Building Level2017In: Proceedings of the 33rd European Photovoltaic Solar Energy Conference, 2017Conference paper (Refereed)
    Abstract [en]

    This study examines how the energy management optimization on household level affects the maximum power flow in a community of houses and the contribution to load smoothening in the community. A detailed model of a single-family house with exhaust air heat pump and photovoltaic system is used in combination with high-resolution weather, electricity use and hot water use data. All five houses in the community are identical but the occupancy of the residents and their use of electric appliances and hot water differ. Results show no reduction of the maximum power delivered to the grid if the houses are operated to optimize the individual self-consumption and self-sufficiency. The highest aggregated power from the grid for the whole community occurred when the heat pumps were controlled by the PV electricity production but without any battery storage. This case also resulted in least smoothing of the aggregated household loads in the community. The conclusion of the study is that energy optimization for individual households in a community do not have to result in a reduction of the aggregated load and power production.

  • 135. Ma, Tianqi
    et al.
    Jia, Zhenyuan
    Li, Hongqi
    Zhang, Xingxing
    Zhao, Xudong
    Optimization of Integrated Energy Process in China Industrial Compressed Air System2013Conference paper (Refereed)
  • 136.
    Magnusson, Benny
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ekerind, Mattias
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    FTX-system i flerbostadshus2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of the report is to investigate potential energy savings when installing FTX systems in multi-family houses. Three common types of heat exchangers are compared to each other: rotary, counter current and cross heat exchangers. The purpose is to see how much the different systems reduce the specific energy use of the building. The house in the study is a typical multi-family house from the 70's located in Borlänge. Exhaust air ventilation is installed, and the building shell is of expected standard of an older apartment block. The specific energy use was calculated at 156 kWh/m

    2 year, far from BBR’s requirements for new construction or major renovations.

    No new measurements have been made on site in the study and the focus lies in processing and evaluating secondary data. Information about the FTX systems was extracted from quotations from selected suppliers. Data regarding the building was derived from blueprints while usage data was collected from the SVEBY project, which compiles surveys and measurements of residents’ habits.

    It was found that the installation of FTX systems, regardless of type, reduced the specific energy consumption by about 30%, down to around 110 kWh / m

    2 year. Only installation of an FTX system would not suffice to meet current BBR requirements. Furthermore, it was found that a theoretical renovation of the building shell according to BBR´s new building regulations had an equivalent result and reduced the building's specific energy consumption by 25%. As a combined measure, the installation of an FTX system and building shell renovation according to BBR´s new building regulations would make it possible to meet BBR’s requirements for specific energy use.

    The negligible difference in performance of the various FTX systems can, to some extent, be explained by the lack of data available for the study. Nevertheless, the choice of FTX system should largely be based on other criteria such as cost of assembly, installation and maintenance as well as comfort in terms of noise level and filtered air pollution.

  • 137.
    Majli, Nadia
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Reverse Osmosis Desalination in Morocco; Preliminary Techno-economic Assessment of Autonomous Grid Connected and Off-grid Photovoltaic Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    Reverse osmosis desalination powered by a photovoltaic system can potentially break the dependence of conventional desalination. This can reduce operation costs of the system as well as improve environmental sustainability. This thesis project presents a study on grid connected and stand-alone photovoltaic systems to provide the required electricity for

    providing fresh water to a golf course located near a luxury hotel resort in Agadir, Morocco. This site requires a high quantity of fresh water for grass spraying systems. The design steps of the suggested system are carried out such that the site radiation data and two different scenarios for the electrical load distribution have been analyzed in the considered site are taken into account during the design simulation. Also, a techno-economic analysis is conducted to assess the economic viability of the system.

    The main simulation tool to be used in this thesis is HOMER (Hybrid Optimization Modeling Electric Renewables) developed by the National Renewable Energy Laboratory (NREL) in the United States of America. HOMER is a simulation tool designed to optimize the size of energy systems for defined boundary conditions. The optimization is based on economic figures such as the Net Present Cost (NPC). This tool helps to find the least cost combination of components. HOMER can be applied to a number of system designs such as on grid, off-grid. A sensitivity analysis of different parameters have also been studied such as PV capital cost per kW, and finally the escalation rate of diesel price.

    The main conclusion, that the capital cost of the photovoltaic system with the reverse osmosis desalination unit is at the moment high. This case study becomes competitive with the other hybrid alternativ.

  • 138.
    Manhal, Ali
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    M. Ali, Tammam
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Solar Tent: A Photovoltaic Generator Model for a Flexible Fabric with Inbuilt Cells2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Natural disasters and conflicts in many different parts of the world force thousands of people to get displaced from their homes and live in refugee camps temporarily or permanently. For refugee families, lack of energy access has great impact on their lives.

    Tarpon Solar Company has developed a solar tent which is a combination of laminated cloth and flexible solar cells. In addition to producing renewable electricity, it can create a comfortable outdoor shelter from sun, rain and wind.

     

    The aims of this study were to define and size the solar system of the tent in both AC and DC systems and optimize the tent to work in different locations around the world. Besides designing a monitoring system for the solar tent to evaluate the performance. In addition, defining the social aspect and the consumer behavior for a better solar tent future design. As a case study, Tarpon AC solar tent in Glava, Sweden has been installed to cover the basic needs of the tent users. To understand the solar tent performance in different weather zones, 4 different locations were suggested. A monitor system was designed to monitor the tent solar system performance. The simulation software PVsyst was used to size the PV system in the different locations with different solar data.

     

    The PVsyst simulation results showed that the current Tarpon solar tent with 32 photovoltaic modules is extremely oversized to cover the basic needs loads (Lighting, mobile charging and ventilation) in the emergency cases.

     

    The current Tarpon solar tent has a standard number of photovoltaic modules integrated in the tent fabric while the photovoltaic modules number should vary from one location to another according to the weather data and solar irradiation. In this case the current Tarpon solar system used in Glava, Sweden can be optimized by decreasing the number of photovoltaic modules to only 6 photovoltaic modules instead of 32 modules.

     

    The study also shows that the features of the off-grid system components (battery and charge controller) are different from one location to another according to the criteria of selection.

     

    This study concludes that for the temporary short-term emergency use of the tent where only basic needs loads are needed, DC system is better than AC system in terms of energy efficiency, system size and cost in the different proposed locations. While AC system is better when using the tent for prolonged time in terms of user flexibility and ability to extend the system. Understanding the consumer behavior and the goal of the tent whether to be used for an emergency short term shelter or a permanent shelter for a prolonged time are important factors for a better solar tent design.

  • 139.
    Mazraeh, Hifa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Abdullahi, Abdiaziz
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Värmeåtervinning ur spillvatten för flerbostadshus: Kornstigen 25 i Borlänge2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this work is to compile knowledge of waste water recovery systems in multi-family houses from literature, previous studies and relevant actors on the subject area. The purpose is also to make temperature measurements in a multi-family house in Borlänge to calculate and analyze the energy saving potential of the Ekoflow heat exchanger from Isaksson Rostfria AB.

    Ekoflow is a waste water heat exchanger that recycles heat energy from wastewater. Through wastewater heat exchanger, the waste water flows from the drain and the cold water in the countercurrent direction. Ekoflow has been installed in some bath houses and hotels and showed good recovery rates in these areas.

    It is a little difficult to find a temperature meter on the market that can measure and store the measured values of a vertical drainage stream. Therefore, produced own temperature meter, which was used to collect measurement data for analysis and calculation of the results.

    Application of the technology in the reference building adds some problems. One problem is that both gray and black water pass through the same pipe which reduces the temperature of the waste water. The second problem is that the building does not have a common connection point to the municipal sewers, which means that a heat exchanger will be needed for each main line.

    Energy consumption in multi-family houses varies depending on the living space and number of residents in the house. The number of residents in the reference building is not known but the temperature and water flow and spill water temperature measurements showed that the building has high hot water consumption. Energy saving depends on several parameters such as incoming cold and waste water temperature to waste water heat exchanger and the length of heat exchanger. The energy savings for three different lengths of the Ekoflow heat exchanger were calculated and a 48-meter heat exchanger showed energy savings of approximately 40 MWh / year, which is profitable from the energy saving perspective.

  • 140.
    Menthon, Maxence
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Van Migom, Léa
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Reducing energy consumption of refrigerators byusing the outside temperature2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays, many electrical appliances are used daily. The refrigerator is one of them.

    Consequently, by affecting the energy used by the refrigerator, a huge amount of energy,

    greenhouse gases (GHG) emissions and money can be saved. It is what this thesis tries to do

    by applying a concept: using the cold from outside. Indeed, this report exposes the process to

    answer the following question:

    How much energy, GHG emissions and money can be saved by using the cold from

    outside on the refrigerating appliances?

    To do so, measurements have been done on a refrigerator placed in a climate chamber. The

    experiment procedure is inspired by the Swedish standard of energy consumption testing in

    order to have the most relevant results as possible. The results of the measures were then used

    to create a mathematical modelling. And finally, by applying the modelling at different

    climate of the world represented by chosen cities, calculations were made to estimate the

    energy, GHG emissions and money savings which can be done thanks to this concept.

  • 141.
    Molin, Elin
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Stridh, B.
    Molin, A.
    Wäckelgård, Ewa
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Experimental yield study of bifacial PV modules in Nordic conditions2018In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, no 6, p. 1457-1463Article in journal (Refereed)
    Abstract [en]

    This study reports on the first full-year field study in Sweden using bifacial photovoltaic modules. The two test sites are located on flat roofs with a low albedo of 0.05 in Linköping (58 °N) and were studied from December 2016 to November 2017. Site 1 has monofacial and bifacial modules with a 40° tilt facing south, which is optimal for annual energy yield for monofacial modules at this location. Site 2 has monofacial 40° tilt south-facing modules and bifacial vertical east–west orientated modules. The annual bifacial energy gain (BG E ) was 5% at site 1 and 1% at site 2 for albedo 0.05. The difference in power temperature coefficients between bifacial and monofacial modules was estimated to influence BG E by +0.4 and +0.1 percentage points on site 1 and 2, respectively. A higher albedo could be investigated on a sunny day with fresh snow for the bifacial east–west modules. The specific yield was 7.57 kWh/kW p , which was a yield increase of 48% compared with tar paper at similar solar conditions.

  • 142.
    Morales-Pallares, Marcos
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Long Term Sustainability of Standalone PV Systems for Community Services: Case Studies from Rwanda2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis was developed with a twofold aim in mind. In first place, to study some of the components that are required to achieve long term sustainability of standalone PV systems for community services. This means, to put in place the necessary ingredients to ensure that standalone PV systems that power schools, health centers or administration offices, among other public institutions, are able to last for their typical life time (20-25 years).

    In particular, the focus of this theoretical part of the thesis is mainly set on both the technical and socio-technical dimensions of long term sustainability. As part of the first one, the study delves into aspects related to PV system design and quality in installations, sustainable system use and operation, as well as maintenance theory. As part of the socio-technical dimension, research in the literature has been done mainly about those social concepts related to the community surrounding a PV system, aspects related to system operation from a user’s perspective, as well as maintenance seen from a socio-technical point of view. Complementarily to the previous two, other dimensions such as the financial, governmental, environmental and related to project management are also introduced.

    The second part of this thesis is based on work done during a one month trip to Rwanda. During this time three main case studies were developed around two schools and one health center, in order to assess the degree of fulfilment of the different dimensions of long-term sustainability in these sites, setting most of the efforts on both the technical and the socio-technical dimensions. Additionally, three complementary (and shorter) visits to two administration offices and an additional school also took place. These visits plus some interviews to several Rwandan companies completed the picture of long-term sustainability of standalone PV systems in the Rwandan context.

    Although the components and the installation of standalone PV systems in recent national Rwandan programs were of high quality, there was generally a lack of adequate direct and indirect lightning protections, in spite of the fact that Rwanda is one of the places with highest keraunic levels in the world. In some cases, previous systems had poor designs, used low quality wiring or installed low quality batteries, not in compliance with international standards. In terms of maintenance and component replacements, these elements were almost never taken into account as part of any original project plan, including financial and human resources. However, although maintenance structures only started to be defined in national programs after system installation, they all lacked the actors and instruments to properly trace quality in maintenance.

    In socio-technical terms, efforts to engage or transfer system operation and energy efficiency knowledge, in the form of trainings for end-users, did not seem to be sufficient. Therefore, some sites experimented a notable load increase or a load shift. In most situations, energy consumption could be optimized, either by using energy efficient appliances (e.g. namely thin clients, energy efficient fridges) or by optimizing the frequency and total time of their use (i.e. autoclaves in health centers). Simple but yet effective operation strategies could also be easily adopted in order to adequate energy use to energy generation, as per the examples included in this thesis. Last but not least, remote monitoring solutions should be considered in the future as means to improve operation and maintenance, especially in wide national projects.

  • 143.
    Moretti, Sebastián
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Simwinga, Abiya
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Economic and Technical Analysis of Integration of PV into the Existing Diesel Power Station in Shang’ombo, Zambia2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The main objective of this study was to carry out an economical and technical analysis of integrating PV into an existing 320 kW diesel power plant in Shang’ombo township in the western province of Zambia. Additionally, the study evaluates the best feasible solution by analyzing different hybrid combinations and configurations whilst taking into account the least Levelized Cost of Electricity (LCOE) and the Net Present Cost (NPC) with regard to the Life Cycle Cost of the project. Hybrid Optimization of Multiple Electric Renewables- (HOMER) software was used for modelling and simulation of five different off-grid solutions. CASE A was for the current system (100 % diesel generated power plant), CASE B: current system and PV, CASE C: Current system, PV and battery, CASE D: Current system, PV, battery and an additional small generator and CASE E: 100% PV and battery.

    The results show that the current system (100 % diesel generator system) is not economically sustainable as it has a very high LCOE of $0.50/kWh due to high cost of diesel and high costs of operation and maintenance of diesel generator sets. On the other hand, a system with 100 % PV with batteries gave the lowest LCOE of $ 0.31/kWh, as it had the lowest operation and maintenance costs and, additionally, zero carbon emissions. Overall, the NPC of the system with 100 % PV with batteries was 1.7 times lower than the current diesel system. However, if the utility company, Zambia Electricity Supply Corporation (ZESCO), would prefer to use the existing diesel generators for the PV/Diesel hybrid system, then CASE C would be the best solution. This hybrid configuration achieves 87 % solar fraction with LCOE of $ 0.39/kWh.

    Lastly, the results generally showed that the initial capital cost of solar energy projects was relatively higher as compared to the equivalent diesel based plants. However, with the continued down ward trend in the price of PV per kWp, solar is the best solution to bridge the current energy deficit that Zambia is currently facing. Additionally, solar solutions answers the worlds cry for clean energy which is environmentally friendly and reduces on the impacts of global warming.

  • 144.
    Mugisha, Jean Claude
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A study on Auxiliary Battery Energy Storage to Mitigate PV Output Power Fluctuations: Case Study: 8.5 MW Agahozo Shalom Youth Village (ASYV) PV Power Plant in Rwanda2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Solar energy is experiencing a rapid growth worldwide and it is a promising technology to play a vital role in future power systems. However, the natural intermittent of solar energy resources affect the quality of the output power from a solar system putting its dispatchability in question. Battery Energy Storage System (BESS) is among the solutions to suppress PV power fluctuations and allow smooth PV power production as result. In this work, BESS was modelled, integrated and simulated for Agahozo Shalom Youth Village (ASYV) PV Power Plant located in Rwanda. MATLAB/Simulink was used as modelling and simulation tool and Excel was used in data analysis. For ease of work, one of eight PV arrays at the power plant was considered and the results were scaled up to the entire power plant afterwards.

    Annual data for year 2017 was analysed and the worst-case scenario which is the day with highest irradiance variation was found. Both PV power and ambient temperature data for this day were used as input to the model. Four smoothing approaches namely Low Pass Filter (LPF), Simple Moving Average (SMA), Exponential Moving Average (EMA) and Ramp Rate Control (RRC) were investigated in detail, applied to the model and compared in terms of performance and battery size that each approach would require. The degree to which power output needs to be smoothed can vary based on regulatory requirements and the technical conditions of the power grid. For this reason, three Ramp Rate Limits (RRLs) namely ±10 %, ±20 % and ±30 % of the rated PV array power per minute were applied in smoothing algorithms to see how large the battery storage would be if Rwandan grid operator was to impose one of the aforesaid RRLs.

    The results showed that all smoothing methods managed to smoothen out PV array power at all RRLs as intended. The difference occurred in performance of smoothing methods and battery size in terms of power and energy that each method required. In all cases, it was noticed that both LPF and EMA displayed almost similar results which made it difficult to make a clear distinction between the two. However, in their slight difference, EMA required a slightly smaller battery size. The memory effect of SMA was noticed and this method was requiring bigger battery size at all RRLs. The RRC performance was better especially at ±10 % RRL compared to other three methods. The particularity of RRC was that it only allows the battery to respond when needed and the battery charges or discharges the exact amount of power needed. This was different from the other three smoothing methods. They were always allowing the battery to respond even when the present power ramp is within the set RRL resulting in high charging/discharging cycles which causes cyclic degradation of the battery. In addition, these methods over-smoothed the PV array power where more than needed power could be absorbed or delivered by the battery resulting in unnecessary bigger battery size.

    Some of downsides of RRC method were that it requires bigger battery size in terms of energy and it could be more sensitive to the uncertainty associated with PV array power measurement compared to other methods. Nonetheless, its battery size in terms of power requirement was less than other methods since it does not over-smooth the PV array power. Since RRC and EMA methods were requiring less battery power and less battery energy at all RRLs respectively, both methods were chosen while scaling up the results to the entire power plant. Using EMA smoothing methods over RRC at ±10 % RRL could results in saving $113 thousand of battery capital cost. However, at ±20 % and ±30 % RRL, the RRC method was found to be the best option since it needs less capital cost than EMA smoothing approach.

  • 145.
    Muthalagappan, Narayanan
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Correlation of PID with other Reliability Tests for CIGS Solar Cells2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With solar photovoltaic plants getting larger and larger, the balance in the system is getting important. Balance of the system is necessary to get the maximum power from the system by arranging its components in an optimal way. With PV systems having high DC voltages of up to 600V in USA and 1000V in Europe, the high voltage stress induced in the system is a lot. One of the effects created due to an imbalance in the system is the Potential Induced Degradation. Previous researchers have found out that the Potential Induced Degradation (PID) is due to the voltage imbalance in the string (a schematic arrangement of solar modules in a system) which is influenced by the environmental factors. The objective of the project is to characterize the electrical properties of different available CIGS solar cell types and to correlate other reliabilty tests with PID test to find out if PID has any correlation with the other degradation mechanisms. Thus 8 samples were requested from two different manufacturers of different CIGS solar cells which were tested and results were compared and analysed. Therefore it was found out some compostional structure prove stable against the PID. But changing the combinaton of the compounds have a difference. Some relational pattern of degradation with the Stability test was evident. Few of the previous finding were again confirmed with a new path of approach for the further researches.

  • 146.
    Myhren, Jonn Are
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Heier, Johan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Hugosson, Mårten
    Dalarna University, School of Technology and Business Studies, Business Administration and Management.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The perception of Swedish housing owner’s on the strategies to increase the rate of energy efficient refurbishment of multi-family buildings2018In: Intelligent Buildings International, ISSN 1750-8975, E-ISSN 1756-6932Article in journal (Refereed)
    Abstract [en]

    Improving the energy performance of existing buildings is crucial for reaching both EU and national climate and energy targets. The main objective of this study was to map challenges that Swedish housing owners perceive when making energy-efficiency refurbishments. A secondary objective was to compare how well these challenges relate to national strategies. The study applied a combined methods approach with audience response meters and in-depth qualitative semi-structured interviews. The housing owners express the view that they have sufficient knowledge of national ambitions to improve the energy performance of buildings and welcome the new building regulations. Despite this supposed knowledge and the current economic situation with beneficial loans, the refurbishment rate still remains low. The housing owners explain that they are concerned about the ‘performance gap’ and request more accurate energy performance predictions. They are also waiting for proof that all sustainability goals can be reached in reality. Probably, too few projects fulfilling ambitions in all categories: economically, socially and energy-wise have been followed up and demonstrated nationally. The new national information centre on refurbishment of buildings may help to spread information about such projects, raise awareness and thus increase the refurbishment rate.

  • 147.
    Myhren, Jonn Are
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Olofsson, Thomas
    Dalarna University, School of Technology and Business Studies, Construction.
    Bergdahl, Martin
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Lågtemperaturuppvärmning med tilluftsradiatorer och värmeåtervinning i frånluft: en varsam renovering av flerbostadshus för energieffektivisering2014Report (Other academic)
    Abstract [sv]

    För att nå reella sänkningar av energianvändningen i hela byggnadsbeståndet krävs tillgång till kostnadseffektiva renoveringspaket med energieffektiva systemlösningar där samspel mellan installationssystem och byggnad beaktas.

    Denna förstudie belyser möjligheter med alternativa renoveringspaket med lågtemperatur-tilluftsradiatorer och värmeåtervinning i frånluften (FX). Systemkombinationer och jämförelser har gjorts med mera etablerade lösningar med traditionella radiatorer, balanserad mekanisk ventilation (FTX) och solvärme. Mindre prövade lösningar såsom frånluftsmoduler (VBX) kopplat till befintliga värmepumpar och behovsstyrd ventilation undersöktes också.

    Energianvändning och kostnadseffektivitet med de undersökta åtgärdspaketen prövades för två äldre bostadshus med vardera specifika restriktioner: den ena inom fjärrvärmenätet och det andra ett K-märkt hus utanför fjärrvärmenätet. Samtidigt reflekterades det över vilka tekniska lösningar som samtidigt är gynnsammast ur hållbarhetssynpunkt. För flertalet befintliga byggnader behöver såväl metoder som komponenter utvecklas på ett varsamt sätt som uppfyller båda ägarens krav som övergripande mål baserat på systemförutsättning och kostnadseffektivitet.

    Förstudien visar att:

     lågtemperatur-tilluftsradiatorer är en systemkomponent som möjliggör ökad komfort via förvärmning och filtrering av inkommande ventilationsluft, effektivare värmeproduktion och minskning av värmeförluster i distribution av varmvatten. Renovering med installation av FX-system i kombination med lågtemperatur-tilluftradiatorer är ett alternativ till FTX system som begränsar byggåtgärderna i byggnaden och ger lägre livscykelkostnad

     Byggnadsskalets täthet blir avgörande för energinyttan båda med FX- och FTX-system. Förstudien visar att FX-system är fördelaktig i byggnader med dålig lufttäthet

     I byggnader med befintligt frånluftssystem kan behovsstyrning av ventilationen vara ett enkelt och kostnadseffektivt sätt att sänka ventilationsförlusterna och spara energi som alternativ till att installera återvinningssystem

    Förstudien visar klart att energieffektiv renovering kan åstadkommas med val av varsamma metoder som också åstadkommer ökad komfort och systemnytta, utanför såväl som inom fjärrvärmenätet. Samtidigt kan ägarens krav på kostandsnytta nås och byggnaders bevarandekrav uppfyllas.

    Nu krävs det demonstrationsprojekt för att inte minst sprida kunskap i branschen men också applicering på större bostadsområden.

  • 148.
    Nielsen, Caroline
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Travel Report from the first field trip within the SIDA supported project "Mini-grids supplied by renewable energy - improving technical and social feasibility: Including visits to Ihushi Development Center, Tweyambe Secondary School and Mavuno Project in Tanzania. Conducted in April 20112011Report (Other academic)
    Abstract [en]

    This report describes the outcome of the first visit to Tanzania, within the project "Mini-grids supplied by renewable energy - improving technical and social feasibility". The trip included visits to three different organizations; Ihushi Development Center (IDC) near Mwanza, TIDESO near Bukoba, and Mavuno Project in Karagwe. At IDC, a brief evaluation of the current power system was done and measuring equipment for long term measurements were installed. At all three locations investigations regarding the current and future electricity demand were conducted and connections to people relevant to the study were established. The report is including as well some technical specifications as some observations regarding organization and management of the technical systems. The trip was including only short visits and therefore only brief introductions to the different organizations, based on observations done by the author. The report is hence describing the author’s understanding of the technical system and social structures after only short visits to each of the organizations, and may differ from observations done at another point in time, over a different time period, or by some other person.This report describes the outcome of the first visit to Tanzania, within the project "Mini-grids supplied by renewable energy - improving technical and social feasibility". The trip included visits to three different organizations; Ihushi Development Center (IDC) near Mwanza, TIDESO near Bukoba, and Mavuno Project in Karagwe. At IDC, a brief evaluation of the current power system was done and measuring equipment for long term measurements were installed. At all three locations investigations regarding the current and future electricity demand were conducted and connections to people relevant to the study were established. The report is including as well some technical specifications as some observations regarding organization and management of the technical systems. The trip was including only short visits and therefore only brief introductions to the different organizations, based on observations done by the author. The report is hence describing the author’s understanding of the technical system and social structures after only short visits to each of the organizations, and may differ from observations done at another point in time, over a different time period, or by some other person.

  • 149.
    Nielsen, Caroline
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Evaluation of a Micro PV-Diesel Hybrid System in Tanzania2012Conference paper (Refereed)
    Abstract [en]

    In April 2011 a monitoring system was installed to enable studies of the performance and the usage of a micro PV-Diesel Hybrid system at the Ihushi Development Center (IDC) near Mwanza in Tanzania. Estimations of the load have been obtained by a survey of installed appliances and interviews with users of installed equipment. The load profile obtained by measurements has been analyzed and compared to estimations of the energy use. Further, the system size and performance were studied.

  • 150.
    Nielsen, Christian
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology. Chalmers University.
    Haegermark, Maria
    Dalenbäck, Jan-Olof
    Analysis of a Novel Solar District Heating System2014In: ISES Conference Proceedings EuroSun 2014, International Solar Energy Society (ISES) , 2014Conference paper (Other academic)
    Abstract [en]

    This paper describes a new residential building area with a solar assisted block heating plant. The building area currently comprises 26 single family buildings, four small multifamily buildings, 6 terrace houses and a nursing home for elderly people with 64 apartments. All buildings are designed for a low heat demand    (<45 kWh a-1 m-2) and the total heated floor area is 14 000 m2.  The block heating system comprises a central 250 kW wood pellet boiler, about 700 m2 of distributed roof-integrated solar collectors and a novel heat distribution system. An initial evaluation indicates that designed heat demands, as well as the overall system performance including expected solar contribution, is likely to be met.  Reported measurements include annual (April 2013 – March 2014) heat balances for two substations with single family buildings, yearly solar energy gains (August 2013 – July 2014), and a monthly (March 2014) heat balance for the whole system.

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