du.sePublications
Change search
Refine search result
234567 201 - 250 of 303
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 201.
    Skarin, Anna
    et al.
    SLU.
    Sandström, Per
    SLU.
    Alam, Moudud
    Dalarna University, School of Technology and Business Studies, Statistics.
    Out of sight of wind turbines — Reindeer response to wind farms in operation2018In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 8, p. 9906-9919Article in journal (Refereed)
    Abstract [en]

    To meet the expanding land use required for wind energy development, a better understanding of the effects on terrestrial animals’ responses to such development is required. Using GPS-data from 50 freely ranging female reindeer (Rangifer tarandus) in the Malå reindeer herding community, Sweden, we determined reindeer calving sites and estimated reindeer habitat selection using resource selection functions (RSF). RSFs were estimated at both second- (selection of home range) and third-order (selection within home range) scale in relation to environmental variables, wind farm (WF) development phase (before construction, construction, and operation), distance to the WFs and at the second-order scale whether the wind turbines were in or out of sight of the reindeer. We found that the distance between reindeer calving site and WFs increased during the operation phase, compared to before construction. At both scales of selection, we found a significant decrease in habitat selection of areas in proximity of the WFs, in the same comparison. The results also revealed a shift in home range selection away from habitats where wind turbines became visible toward habitats where the wind turbines were obscured by topography (increase in use by 79% at 5 km). We interpret the reindeer shift in home range selection as an effect of the wind turbines per se. Using topography and land cover information together with the positions of wind turbines could therefore help identify sensitive habitats for reindeer and improve the planning and placement of WFs. In addition, we found that operation phase of these WFs had a stronger adverse impact on reindeer habitat selection than the construction phase. Thus, the continuous running of the wind turbines making a sound both day and night seemed to have disturbed the reindeer more than the sudden sounds and increased human activity during construction work.

  • 202.
    Srinivasan, Suriya
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Design and Mathematical Modelling of a Solar Carport with Flat Reflector2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the world is moving towards the renewable energy, there is increase in usage of the electric vehicles in transport sector. This has led to more consumption of electricity from the grid and thus affecting its stability. To overcome this issue many decentralized charging stations have come of which generating electricity from the solar energy is more popular. These solar carports act as a shelter for the vehicles from various climatic factors such as rain, snow, dust in addition to producing renewable electricity.

    The main aim of this thesis study is to design a solar carport with the reflector compared to the existing Solar carports. The roof selected for this thesis study is a “V” shaped roof with the PV modules installed on one side of the roof and a reflector installed on the other side of the roof. The objectives of this thesis study are creating a mathematical irradiation and yield model of the PV system with and without a reflector. In addition, find the optimum roof tilt angle for a PV system with the reflector. Finally, determine the optimum increase in the annual energy yield for a PV system with the reflector compared to the PV system without a reflector.

    Microsoft Excel is used to create the mathematical irradiation and yield model of the PV system. The simulation was done for three different locations by obtaining hourly irradiation and temperature data from the PVsyst software. As a case study four different reflective materials of different specular and diffuse reflectance were chosen for better understanding and comparison. The simulation results showed that there is significant increase in the annual energy yield for a PV system with the reflector for all the locations. The study also shows that the increase in energy yield, optimum roof tilt angle is dependent on the specular and diffuse nature of the reflector.

    The study has concluded that the increase in the annual energy yield for a PV system with the specular reflector is more compared to a PV system with the diffuse reflector for the lower roof tilt angles and vice versa. It is also clear that the increase in the energy yield is similar for all the three locations. Hence, based on the roof tilt angle the selection of the reflector material needs to be done for an optimum design of the solar carport.

  • 203.
    Swing Gustafsson, Moa
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    The impact on the energy system of heating demands in buildings: A case study on district heating and electricity for heating in Falun, Sweden2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

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

  • 204.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalen University.
    Primary energy use in buildings in a Swedish perspective2016In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 130, p. 202-209Article in journal (Refereed)
    Abstract [en]

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

  • 205.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalen University.
    Assessment of the potential for district heating to lower the peak electricity consumption in a medium size municipality in SwedenManuscript (preprint) (Other academic)
    Abstract [en]

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

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

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

  • 206.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Life cycle cost of heat supply to areas with detached houses: a comparison of district heating and heat pumps from an energy system perspective2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 12, article id 3266Article in journal (Refereed)
    Abstract [en]

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

  • 207.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalen University.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalen University.
    Mapping of heat and electricity consumption in a medium size municipality in Sweden2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, p. 1434-1439Article in journal (Refereed)
    Abstract [en]

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

  • 208.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Potential for district heating to lower peak electricity demand in a medium-size municipality in Sweden2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 186, p. 1-9Article in journal (Refereed)
    Abstract [en]

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

  • 209.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Primary energy reduction in buildings: Case study on a residential building in Falun, Sweden2014In: Proceedings from the 14th International Symposium on District Heating and Cooling / [ed] Anna LAND, Swedish District Heating Association, 2014, p. 543-545Conference paper (Refereed)
    Abstract [en]

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

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

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

  • 210.
    Tesfay Abraham, Bisrat
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Degradation Evaluation of Grid- Connected PV Modules at Högskolan Dalarna Borlänge, Sweden2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

  • 211.
    Thyr, Max
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Simulation Study of Bifacial PV Modules in Sweden2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

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

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

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

    later be compared with measured results.

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

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

    reference system has also been simulated using monofacial PV modules.

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

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

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

    south.

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

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

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

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

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

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

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

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

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

    bright canvas.

  • 212.
    Troitiño Malavasi, Bruno Matias
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Replacing Finned Copper withCorrugated Stainless Steel, forthe Heat Exchangers of a SolarCombisystem Store: Performance and EconomicEvaluation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

  • 214.
    Trygg, Louise
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ersson, Hans
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gradén, Mattias
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ragnarsson, Marit
    Rehme, Jakob
    Hinder och Drivkrafter: Projekt Branschvis Energieffektivisering2015Report (Other academic)
    Abstract [sv]

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

    Projektet BEE – Branschvis Energieffektivisering

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

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

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

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

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

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

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

  • 215.
    Tuccella, Simone
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Grid Connection of the Existing Off-grid PV system at Mavuno Secondary School in Tanzania2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

  • 216.
    Turk, Suheyla
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Sustainable Neighbourhood Design in Jakobsgårdarna, Borlänge2019Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Energy efficient houses benefit communities not only to provide renewable energy shares and generating surplus electricity supporting local economic development. Also, residents in energy efficient houses have less energy usage that reduces household budget expenses. However, one of the obstacles of energy efficient technology installment of residential buildings is high investment cost, which can be solved with the usage of modular housing. In Europe, housing costs have a large share, especially for Sweden, housing expenses is a burden mostly for people who are at the risk of poverty. Also, high investment costs of energy efficient housing are combined with high construction prices leading a large share of budgets and effort to make houses affordable for low income groups. This study develops a scenario to find solutions for affordable housing problem in Sweden with a design proposal. The aim of this study is to investigate if there are ways of achieving socio-economic mix by the production of energy efficient affordable housing and urban gardening to develop a strategy for resource efficiency in Jakobsgårdarna. To achieve the aim, energy efficient affordable housing designed as modular units to achieve a local economic development. This study uses a design-based research method consisting of learning from background cases to transfer lesson learned in design phase of the sustainable neighborhood consisting of energy efficient technologies. Background cases were analyzed with literature review to define sustainable neighborhood, which was then used to develop a hypothesis. Findings of this thesis generates definition of sustainability tools consisting of a collaborative ownership; designing common kitchens; producing electricity and biogas from renewable energy sources; practicing urban agriculture; managing waste and storm and methods to cross subsidize energy efficient affordable housing production. The outcome of this research provides a sustainable neighborhood design proposal for Jacobsgårdarna, Borlänge.

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

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

  • 218. Udomsri, Seksan
    et al.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Martin, Andrew R.
    Martin, Viktoria
    Decentralized cooling in district heating network: system simulation and parametric study2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 92, p. 175-184Article in journal (Refereed)
    Abstract [en]

    This paper presents system simulation and parametric study of the demonstration system of decentralized cooling in district heating network. The monitoring results obtained from the demonstration were calibrated and used for parametric studies in order to find improved system design and control. This study concentrates on system simulation studies that aim to: reduce the electricity consumption, to improve the thermal COP's and capacity if possible; and to study how the system would perform with different boundary conditions such as climate and load. The internal pumps inside the thermally driven chiller (TDC) have been removed in the new version TDC and implemented in this study to increase the electrical COP. Results show that replacement of the fourth with the fifth generation TDC increases the system electrical COP from 2.64 to 5.27. The results obtained from parametric studies show that the electrical and thermal COP's, with new realistic boundary conditions, increased from 2.74 to 5.53 and 0.48 to 0.52, respectively for the 4th generation TDC and from 5.01 to 7.46 and 0.33 to 0.43, respectively for the 5th generation TDC. Additionally the delivered cold increased from 2320 to 8670 and 2080 to 7740 kWh for the 4th and 5th generation TDC's, respectively. (C) 2011 Elsevier Ltd. All rights reserved.

  • 219.
    Vangari, Divyanagalakshmi Haribabu
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fathima, Sumayya
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Design of Distributed Rooftop PV System to Minimize Power Cuts for an Indian Village2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

  • 220.
    Verma, Pankaj
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Water saving comparison study between innovative and conventional cleaning systems for CSP technologies2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 221.
    Vestlund, Johan
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Dalenbäck, Jan-Olof
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Movement and mechanical stresses in sealed, flat plate solar collectors2012In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 86, no 1, p. 339-350Article in journal (Refereed)
    Abstract [en]

    This article describes movements and mechanical stresses in sealed, gas-filled, flat plate solar collectors. The advantage of a sealed space between a collector absorber and glass cover is that it (i) eliminates the influence of humidity condensation and dust and (ii) it lowers the heat losses when the enclosed space is filled with a suitable gas at normal pressure. However as the solar collector temperature varies, volume and pressure changes cause movement and mechanical stresses. In this study, the finite element method was used to determine movements and mechanical stresses. Several geometries were analyzed and it was found that the stresses in the investigated collectors are a factor 2–4 below the critical stress levels. Furthermore, it was found to be possible to reduce the stresses and improve the factor of safety by (i) using a larger area and/or reducing the distance between the glass and the absorber and/or (ii) changing the length and width so the tubes are longer.

  • 222.
    Vestlund, Johan
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Dalenbäck, Jan-Olof
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Thermal and mechanical performance of sealed, gas-filled, flat plate solar collectors2012In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 86, no 1, p. 13-25Article in journal (Refereed)
    Abstract [en]

    The study includes calculations for both the thermal performance and the mechanical behaviour of a gas-filled, flat plate solar collector without external gas expansion, i.e., a collector with varying gas volume and gas pressure and movement in both cover glass and absorber. Classical theories for the thermal performance are combined with a finite-element method to investigate which factors have an impact from the mechanical stress point of view. This article describes major results for collectors with copper and aluminium absorbers combined with different inert gases. It is shown that a collector may be designed which uses less material than a standard collector but achieves at least the same thermal performance, by using a thinner collector and a thinner absorber and a suitable gas filling other than air. If copper is used in absorber and tubes, a 0.15 mm thick absorber together with a tube-to-tube distance of 103 mm results in the same performance as a 0.3 mm absorber with a 144 mm tube-to-tube distance, but the former will use 25% less material. The use of copper can be further reduced if the absorber is made of aluminium and the tubes are made of copper. The factor of safety for thick (>0.5 mm) aluminium absorbers is, however, not as large as it is for copper absorbers.

  • 223.
    Vestlund, Johan
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Dalenbäck, Jan-Olof
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Thermal losses in sealed, gas-filled flat plate solar collectors2007In: Solar World Congress, Peking, 2007, Vol. 1, p. 651-655Conference paper (Other academic)
    Abstract [en]

    A sealed space between absorber and cover glass makes it possible reducing the influence of humidity condensate and dust at the same time as the enclosed space can be filled with a suitable gas for lowering the losses. This paper is about the size of the losses in these collectors. A calculating model of a gas-filled flat plate solar collector was built in Matlab with standard heat transfer formulas. It showed that the total loss can be reduced up to 20% when changing to an inert gas. It is also possible using a much shorter distance and still achieve low losses at the same time as the mechanical stresses in the material is reduce.

  • 224.
    Vestlund, Johan
    et al.
    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.
    Dalenbäck, Jan-Olof
    Thermal performance of gas-filled flat plate solar collectors2009In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 83, no 6, p. 896-904Article in journal (Refereed)
    Abstract [en]

    A sealed space between absorber and cover glass in a flat plate solar collector makes it possible to reduce the influence of humidity condensate and dust at the same time as the enclosed space can be filled with a suitable gas for lowering the heat losses. This article describes the influence of different gases on the heat losses in a typical flat plate solar collector. A model of a gas-filled flat plate solar collector was built in Matlab with standard heat transfer formulas. The results show that the overall heat loss can be reduced by up to 20% when changing from air to an inert gas. It is further possible to reduce the distance between absorber and cover in order to reduce the mechanical stresses in the material with similar heat losses.

  • 225.
    Vidal Lorbada, Ricardo
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Design and implementation of a charge controller with buck converter topology for a Li-ion battery using the component LTC4015.2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

  • 226.
    Vijay Vichare, Rohan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Evaluation of Two Solar Heating and Cooling Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

  • 227.
    Vijayan, Veenaaishwarya
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Simulation Study for Optimal Inverter Sizing of Grid-Connected PV Systems in Swedish Locations2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

  • 228.
    Vijayaragavan, Krishna Prasad
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Feasibility of DC microgrids for rural electrification2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

     

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

     

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

     

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

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

  • 229.
    Walusimbi Kizanyiro, Samuel
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Soiling Effects on Photovoltaic Modules, Modelling of Specific Cleaning Frequency Optimization for a 10 MW PV Power Plant inTororo, Uganda2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The accumulation of dust on the photovoltaic (PV) modules for the PV plant result in energy loss and therefore, there was a need to assess the impact of soiling on the PV modules since soiling losses are location specific. In this work, the approach of quantifying soiling loss experimentally which involved comparing the temperature corrected short circuit current values for the naturally soiled string to the frequently cleaned string had higher accuracy than the method of extracting soiling loss from the PV plant production data. This was due to the uncertainties associated with the plant production data.

    The average soiling loss values were determined experimentally and from the plant production data. The month of January 2018 was found to have the highest soling loss of 6 % and March 2018 had the lowest soiling loss was less than 1 %. The soiling for the month of January 2018 was used to determine an optimum cleaning interval which balances out with the revenue lost due to soiling and the cost of the cleaning event using the cleaning schedule model and the optimum interval was 21 days from the last date when the plant last cleaned. This optimum cleaning interval reduces the total cost per unit energy generated by the PV plant and therefore, the levelized cost of electricity. However, the optimum cleaning interval may vary depending on the cost of the cleaning event as well as the seasonal variations in the soiling loss and energy generated. The cleaning schedule model developed can be used to determine when the PV plant should be cleaned. However, this model should be used as a guideline since soiling loss highly depends on the climate of the area and it is always changing.

  • 230. Wang, Xinru
    et al.
    Xia, Liang
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Copertaro, Benedetta
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Pan, Song
    Wu, Jinshun
    A systematic review of recent air source heat pump (ASHP) systems assisted by solar thermal, photovoltaic and photovoltaic/thermal sources2020In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 146, p. 2472-2487Article in journal (Refereed)
  • 231. Wei, Yixuan
    et al.
    Xia, Liang
    Pan, Song
    Wu, Jinshun
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Han, Mengjie
    Dalarna University, School of Technology and Business Studies, Statistics.
    Zhang, Weiya
    Xie, Jingchao
    Li, Qingping
    Prediction of occupancy level and energy consumption in office building using blind system identification and neural networks2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 240, p. 276-294Article in journal (Refereed)
    Abstract [en]

    Occupancy behaviour plays an important role in energy consumption in buildings. Currently, the shallow understanding of occupancy has led to a considerable performance gap between predicted and measured energy use. This paper presents an approach to estimate the occupancy based on blind system identification (BSI), and a prediction model of electricity consumption by an air-conditioning system is developed and reported based on an artificial neural network with the BSI estimation of the number of occupants as an input. This starts from the identification of indoor CO2 dynamics derived from the mass-conservation law and venting levels. The unknown parameters, including the occupancy and model parameters, are estimated by using a frequentist maximum-likelihood algorithm and Bayesian estimation. The second phase is to establish the prediction model of the electricity consumption of the air-conditioning system by using a feed-forward neural network (FFNN) and extreme learning machine (ELM), as well as ensemble models. To analyse some aspects of the benchmark test for identifying the effect of structure parameters and input-selection alternatives, three studies are conducted on (1) the effect of predictor selection based on principal component analysis, (2) the effect of the estimated occupancy as the supplementary input, and (3) the effect of the neural network ensemble. The result shows that the occupancy number, as the input, is able to improve the accuracy in predicting energy consumption using a neural network model.

  • 232. Wei, Yixuan
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Shi, Yong
    Xia, Liang
    Pan, Song
    Wu, Jinshun
    Han, Mengjie
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Zhao, Xiaoyun
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    A review of data-driven approaches for prediction and classification of building energy consumption2018In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 82, no 1, p. 1027-1047Article in journal (Refereed)
    Abstract [en]

    A recent surge of interest in building energy consumption has generated a tremendous amount of energy data, which boosts the data-driven algorithms for broad application throughout the building industry. This article reviews the prevailing data-driven approaches used in building energy analysis under different archetypes and granularities, including those methods for prediction (artificial neural networks, support vector machines, statistical regression, decision tree and genetic algorithm) and those methods for classification (K-mean clustering, self-organizing map and hierarchy clustering). The review results demonstrate that the data-driven approaches have well addressed a large variety of building energy related applications, such as load forecasting and prediction, energy pattern profiling, regional energy-consumption mapping, benchmarking for building stocks, global retrofit strategies and guideline making etc. Significantly, this review refines a few key tasks for modification of the data-driven approaches in the context of application to building energy analysis. The conclusions drawn in this review could facilitate future micro-scale changes of energy use for a particular building through the appropriate retrofit and the inclusion of renewable energy technologies. It also paves an avenue to explore potential in macro-scale energy-reduction with consideration of customer demands. All these will be useful to establish a better long-term strategy for urban sustainability.

  • 233.
    Weldemariam, Ashenafi
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Analyzing the Effect of Soiling on the Performance of a Photovoltaic System of Different Module Technologies in Kalkbult, South Africa2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The fact that most of the large scale solar PV plants are built in arid and semi-arid areas

    where land availability and solar radiation is high, it is expected the performance of the PV

    plants in such locations will be affected significantly due to high cell temperature as well as

    due to soiling. Therefore, it is essential to study how the different PV module technologies

    will perform in such geographical locations to ensure a consistent and reliable power

    delivery over the lifetime of the PV power plants.

    As soiling is strongly dependent on the climatic conditions of a particular location a test

    station, consisted of about 24 PV modules and a well-equipped weather station, was built

    within the fences of Scatec’s 75 MW Kalkbult solar PV plant in South Africa.

    This study was performed to a better understand the effect of soiling by comparing the

    relative power generation by the cleaned modules to the un-cleaned modules. Such

    knowledge can enable more quantitative evaluations of the cleaning strategies that are

    going to be implemented in bigger solar PV power plants.

    The data collected and recorded from the test station has been analyzed at IFE, Norway

    using a MatLab script written for this thesis project. This thesis work has been done at

    IFE, Norway in collaboration with Stellenbosch University in South Africa and Scatec

    Solar a Norwegian independent power producer company.

    Generally for the polycrystalline modules it is found that the average temperature

    corrected efficiency during the period of the experiment has been 15.00±0.08 % and for

    the thin film-CdTe with ARC is 11.52% and for the thin film without ARC is about

    11.13% with standard uncertainty of ±0.01 %.

    Besides, by comparing the initial relative average efficiency of the polycrystalline-Si

    modules when all the modules have been cleaned for the first time and the final relative

    efficiency; after the last cleaning schedule which is when all the reference modules E, F, G,

    and H have been cleaned for the last time it is found that poly3 performs 2 % and 3 %

    better than poly1 and poly16 respectively, poly13 performs 1 % better than poly15 as well

    as poly5 and poly12 performs 1 % and 2 % better than poly10 respectively. Besides, poly5

    and poly12 performs a 9 % and 11 % better than poly7. Furthermore, there is no change

    in performance between poly6 and poly9 as well as poly4 and poly15. However, the

    increase in performance of poly3 to poly1, poly13 to poly15 as well as poly5 and poly12 to

    poly10 is insignificant.

    In addition, it is found that TF22 perform 7% better than the reference un-cleaned module

    TF24 and similarly; TF21 performs 7% higher than TF23. Furthermore, modules with

    ARC glass (TF17, TF18, TF19, and TF20) shows that cleaning the modules with only

    distilled water (TF19) or dry-cleaned after cleaned with distilled water(TF20) decreases the

    performance of the modules by 5 % and 4 % comparing to its respective reference uncleanedmodules TF17 and TF18 respectively.

  • 234.
    Win, Kaung Myat
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Emissions from residential wood pellet boilers and stove characterized into start-up, steady operation and stop emissions2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 4, p. 2496-2505Article in journal (Refereed)
    Abstract [en]

    Gaseous and particulate emissions from three residential wood pellet boilers and a stove were characterized and quantified at start-up, steady (full, medium and low combustion power), and stop phases. The aim was to characterize the emissions during the different phases of boiler operation and to identify when the major part of the emissions occur to enable actions for emission reduction where the savings can be highest. The investigated emissions comprised carbon monoxide (CO), nitrogen oxide (NO), total organic carbon (TOC), and particulate matter (PM 2.5). In this study, particle emissions were characterized by both number and mass concentration. The emission characteristics at high combustion power were relatively similar for all tested devices while significant differences in CO and TOC were observed at lower combustion power. Highest CO and TOC emissions are produced by the bottom fed boiler at low combustion power. The accumulated start-up emissions of the tested devices varied in the ranges of 0.5−12 g CO, 0.1−0.7 g NO, 0.1−2 g TOC, 0.12−2.9 g PM2.5, and 2.4 × 1013 to 3.1 × 1014 particles PM2.5. The accumulated stop emissions varied in the ranges 4−15.5 g CO, 0.01−0.11 g NO, 0.02−1.6 g TOC, 0.1−1.3 g PM2.5, and 3.3 × 1013 to 1.4 × 1014 particles PM2.5. The bottom fed boiler B1 had higher start-up and stop emissions than the tested top fed boilers and more particle emissions were accumulated in start-up phase than in stop phases of boiler B1, B3, and stove S1. Number of particles emitted from residential wood pellet combustion is dominated by fine particles smaller than 1 μm and similar particle distribution both in number and mass were observed for the tested devices. The start-up phase generated higher accumulated particle mass than the stop phase.

  • 235.
    Win, Kaung Myat
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Persson, Tomas
    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.
    Particles and gaseous emissions from realistic operation of residential wood pellet heating systems2012In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 59, p. 320-327Article in journal (Refereed)
    Abstract [en]

    Gaseous and particulate emissions from six residential wood pellet heating systems are determined at a realistic six day operation sequence. The study aims to investigate the total emissions from a realistic operation of the heating systems including start-up and stop phases. Five combined solar and pellet heating systems and one reference boiler without solar system with an integrated DHW preparation was tested in a laboratory at realistic operation conditions. The investigated emissions comprised carbon monoxide (CO), nitrogen oxide (NO), total organic carbon (TOC) and particulate matter (PM2.5). In this study, the emissions are presented as accumulated total emissions from the whole six days period and the emissions from start-up and stop phases are also presented separately to evaluate the influence of the emissions from these phases on the total emissions. Emission factors of the measured systems from the six day period are between 192 and 547 mg MJ1 for the CO emissions, between 61 and 95 mg MJ1 for the NO, between 6 and 45 mg MJ1 for the TOC, between 31 and 116 mg MJ1 for the particulate matter and between 2.1 × 1013 and 4 × 1013 for the number of particles. The emissions from the start-up and stop phases are significantly high for the CO (63–95 %) and the TOC (48–93 %). NO and particles emissions are shown to dominate during stationary operation. However, 30–40 % of the particle emissions arise from the start and stop periods. It is also shown that the average emissions of CO, TOC and particles under the realistic annual conditions were higher than the limit values of two eco labels.

  • 236. Wu, J.
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Shen, Jingchun
    University of Nottingham, Ningbo.
    Wu, Y.
    Connelly, K.
    Yang, T.
    Tang, L.
    Xiao, M.
    Xu, P.
    Wang, H.
    A review of thermal absorbers and their integration methods for the combined solar photovoltaic/thermal (PV/T) modules2017In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 75, p. 839-854Article in journal (Refereed)
    Abstract [en]

    Thermal absorbers and their integration methods are critical to solar photovoltaic/thermal (PV/T) modules. These two elements directly influence the cooling effort of PV layers and as a result, the related electrical/thermal/overall efficiency. This paper conducts a critical review on the essential thermal absorbers and their integration methods for the currently-available PV modules for the purpose of producing the combined PV/T modules. A brief overview of different PV/T technologies is initially summarized, including aspects of their structure, efficiencies, thermal governing expressions and their applications. Seven different types of thermal absorbers and four corresponding integration methods are subsequently discussed and summarized in terms of their advantages/disadvantages and the associated application for various PV/T modules. Compared to traditional thermal absorbers, such as sheet-and-tube structure, rectangular tunnel with or without fins/grooves and flat-plate tube, these four types, i.e. micro-channel heat pipe array/heat mat, extruded heat exchanger, roll-bond heat exchanger and cotton wick structure, are promising due to the significant enhancement in terms of efficiency, structure, weight, and cost etc. The appropriate or suitable integration method varies in different cases, i.e. the ethylene-vinyl acetate (EVA) based lamination method seems the best option for integration of PV layer with thermal absorber when compared with other conventional methods, such as direct contact, thermal adhesive and mechanical fixing. Finally, suggestions for further research topics are proposed from five aspects. The overall research results would provide useful information for the assistance of further development of solar PV/T modules with high feasibility for widespread application in energy supply even at district or city-level in the near future. © 2016 Elsevier Ltd.

  • 237. Wu, Yupeng
    et al.
    Parham, Mirzaei
    Zhang, Xingxing
    Fang, Wenbo
    Thermal and optical analysis of a passive heat recovery and storage system for building skin2016Conference paper (Refereed)
  • 238.
    Wäckelgård, Ewa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Svedung, Harald
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Optical characterization and modelling of paint top-coatings for low-emittance applications2016In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 78, p. 275-281Article in journal (Refereed)
    Abstract [en]

    The study reports on characterization of low-infrared-emittance paint top-coatings for interior building applications in which the thermal radiation becomes important in comparison with thermal conductance. The top-coating that consist of a binder with aluminium flakes has been optically characterized in the infrared wavelength range in order to determine single flake and binder emittance from reflectance measurements. The single flake emittance was found to be 0.12 for non-leafing cornflake. The absorption coefficient that determines the binder emittance as a function of binder thickness was 0.060 [μm]−2 and 0.085 [μm]−2 for Lumiflon and polyester respectively. These results were used as parameters in a simple model of the flake-binder top-coating to investigate how the emittance of the top-coating was influence by the two components and compared with a state-of-art low-emittance commercial paint. It was found from the modelling that replacing the polyester binder with Lumiflon reduces the infrared emittance (at room temperature) from 0.36 to 0.30. Increasing flake reflectance from 0.88 to 0.96 and at the same time reduce flake thickness from 2 to 1 μm gives an emittance of 0.20. However, the real samples prepared with Lumiflon showed a severe degradation caused by the flakes floating up closer to the surface which indicates a viscosity problem that needs to be solved for practical use. Thinner flakes with higher reflectance can be found if vacuum metallised pigments are used instead of ball-milled.

  • 239. Xiao, M
    et al.
    Tang, L
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Yu-Fat-Lun, I
    Li, G
    Analysis on cooling technologies of concentrated solar power system: a review2017Conference paper (Refereed)
    Abstract [en]

    The application of the Concentrated Solar Power (CSP) system has attracted an ever-increasing attention with the deepening worldwide energy crisis. Operating temperature is one of the most important factors for CSP system that affects the solar photoelectric conversion efficiency. Reasonable cooling method cannot only decrease the operative temperature, balance flare inhomogeneity, also should display the characteristics of convenient installation, low power consumption and high reliability. Based on a comprehensive literature review, this work conducted a thorough compilation on different cooling techniques of CSP system. It includes the commonly used air cooling and water cooling, also illustrates the promising ground coupled cooling, impinging jet cooling, liquid immersion cooling, microchannel cooling, heat pipe cooling and Phase Change Material systems etc. Besides, the advantages and disadvantages of different cooling technologies are briefly analysed. It is expected that this paper could provide guidance for development and optimization of cooling technologies in CSP system.

  • 240. Xiao, Manxuan
    et al.
    Tang, Llewelly
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Lun, Isaac Yu Fat
    Yuan, Yanping
    A Review on Recent Development of Cooling Technologies for Concentrated Photovoltaics (CPV) Systems2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 12, article id 3416Article in journal (Refereed)
    Abstract [en]

    Concentrated Photovoltaics (CPV) technology, as an energy saving method which can directly generate electricity from the Sun, has attracted an ever-increasing attention with the deepening worldwide energy crisis. However, operating temperature is one of the main concerns that affect the CPV system. Excess cell temperature causes electrical conversion efficiency loss and cell lifespan decrease. Thus, reasonable cooling methods should decrease the operating temperature and balance the flare inhomogeneity. They also need to display high reliability, low power consumption, and convenient installation. This paper presented the architectural, commercial, and industrial usage of CPV system, reviewed the recent research developments of different cooling techniques of CPV systems during last few years, including the spectral beam splitting technology, cogeneration power technology, commonly used and promising cooling techniques, active and passive cooling methods. It also analysed the design considerations of the cooling methods in CPV systems, introduced the classification and basic working principles and provided a thorough compilation of different cooling techniques with their advantages, current research limitations, challenges, and possible further research directions. The aim of this work is to find the research gap and recommend feasible research direction of cooling technologies for CPV systems. 

  • 241. Xiong, Y
    et al.
    Bo, L
    Qiang, M
    Wu, Y
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology. University of Nottingham.
    Xu, P
    Ma, C
    A characteristic study on the start-up performance of molten-salt heat pipes: Experimental investigation2017In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 82, p. 433-438Article in journal (Refereed)
    Abstract [en]

    This paper reports a fundamental experimental investigation of the start-up characteristics of heat pipes using a dedicated molten-salt mixture as the working fluid. Based on four single salt, i.e. NaNO3(AR), KNO3(AR), LiNO3(AR) and Ca(NO3)2(AR), a quaternary molten-salt working fluid was developed and charged at different masses into four heat pipes with the same dimensions of 980 mm in length and 22 mm in diameter. A parallel comparison on the start-up performance of these heat pipes was then conducted to observe the influence of the charging mass and the inclination angle under the consistent lab-controlled conditions. The experimental results showed the heat pipe with molten-salt charge of 40 g responded much quicker than those with molten salt charge of 60 g, 70 g and 80 g respectively; meanwhile, the molten-salt heat pipe achieved the maximum condensation temperature at inclination angle of 50°. Comparing to the conventional naphthalene heat pipe, the dedicated molten-salt heat pipe had a much shorter start-up time when they were charged with the same amount of 40 g. The overall research result is expected to provide certain guidance for further design and operation of molten-salt heat pipe in high-and-medium-temperature heat transfer and storage scenarios. 

  • 242. Xu, Jihuan
    et al.
    Zhang, Xingxing
    A novel water heating system by low-temperature solar capillary heat pipe assisted with heat pump2012Patent (Other (popular science, discussion, etc.))
  • 243. Xu, Peng
    et al.
    Liu, Chenchen
    Zhang, Xingxing
    Tang, Llewellyn
    Numerical study on the thermal performance of earth-tube system for green building in Ningbo, China2016Conference paper (Refereed)
  • 244. Xu, Peng
    et al.
    Shen, Jingchun
    University of Nottingham, Ningbo.
    Zhang, Xingxing
    University of Hull; University of Nottingham .
    He, Wei
    Zhao, Xudong
    Design, fabrication and experimental study of a novel loop-heat-pipe based solar thermal facade water heating system2015In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, p. 566-571Article in journal (Refereed)
    Abstract [en]

    This paper investigated a novel loop-heat-pipe based solar thermal facade heat-pump system for hot water from concept design, prototype fabrication and experimental test. Given the specific testing conditions, the solar thermal efficiency of the facade module achieved nearly 0.71 in average and the mean system's COP was about 5.0. It is expected that such novel LHP based solar thermal facade technology would further contributed to the development of the renewable (solar) driven heating/hot water service and therefore lead to significant environmental benefits.

  • 245. Xu, Peng
    et al.
    Shen, Jingchun
    Zhang, Xingxing
    University of Hull; University of Nottingham.
    Zhao, Xudong
    Qian, Yingchu
    Case study of smart meter and in-home display for residential behavior change in Shanghai, China2015In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, p. 2694-2699Article in journal (Refereed)
    Abstract [en]

    Smart meters and in-home displays (IHD) have been recently adopted to help give residential consumers more control over energy consumption, and to help meet environmental and security of supply objectives. The paper aims to identify the effectiveness of smart meters and real-time IHDs in reducing Shanghai household energy consumption through a pilot investigation. The research results demonstrate the improved awareness, understanding, and attitudes towards the energy saving by smart meters and IHDs.

  • 246. Xu, Peng
    et al.
    Zhang, Xingxing
    Shen, Jingchun
    Yang, Tong
    Deng, Wu
    Tang, Llewellyn
    Empirical study of the energy saving potentials in Shanghai residential buildings through human behaviour change2015Conference paper (Refereed)
  • 247. Xu, Peng
    et al.
    Zhang, Xingxing
    University of Nottingham, Ningbo.
    Shen, Jingchun
    University of Nottingham, Ningbo.
    Yang, Tong
    Deng, Wu
    Tang, Llewellyn
    Empirical study of the energy saving potentials in Shanghai residential buildings through human behaviour change2015Conference paper (Refereed)
  • 248. Xu, Peng
    et al.
    Zhang, Xingxing
    Shen, Jingchun
    University of Nottingham, Ningbo.
    Yang, Tong
    Tang, Llewellyn
    Comparative study of a novel thermal absorber based solar photovoltaic/thermal against photovoltaic system2015Conference paper (Refereed)
  • 249. Xu, Peng
    et al.
    Zhang, Xingxing
    Shen, Jingchun
    Yang, Tong
    Tang, Llewellyn
    Field-experimental study of a novel solar photovoltaic/thermal (PV/T) system2015Conference paper (Refereed)
  • 250. Xu, Peng
    et al.
    Zhang, Xingxing
    University of Hull.
    Shen, Jingchun
    University of Hull.
    Zhao, Xudong
    He, Wei
    Li, Deying
    Parallel experimental study of a novel super-thin thermal absorber based photovoltaic/thermal (PV/T) system against conventional photovoltaic (PV) system2015In: Energy Reports, ISSN 2050-0505, E-ISSN 2352-4847, Vol. 1, p. 30-35Article in journal (Refereed)
    Abstract [en]

    Photovoltaic (PV) semiconductor degrades in performance due to temperature rise. A super thin-conductive thermal absorber is therefore developed to regulate the PV working temperature by retrofitting the existing PV panel into the photovoltaic/thermal (PV/T) panel. This article presented the parallel comparative investigation of the two different systems through both laboratory and field experiments. The laboratory evaluation consisted of one PV panel and one PV/T panel respectively while the overall field system involved 15 stand-alone PV panels and 15 retrofitted PV/T panels. The laboratory testing results demonstrated the PV/T panel could achieve the electrical efficiency of about 16.8% (relatively 5% improvement comparing with the stand-alone PV panel), and yield an extra amount of heat with thermal efficiency of nearly 65%. The field testing results indicated that the hybrid PV/T panel could enhance the electrical return of PV panels by nearly 3.5%, and increase the overall energy output by nearly 324.3%. Further opportunities and challenges were then discussed from aspects of different PV/T stakeholders to accelerate the development. It is expected that such technology could become a significant solution to yield more electricity, offset heating load freely and reduce carbon footprint in contemporary energy environment.

234567 201 - 250 of 303
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf