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  • 51.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Lindberg, Eva
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Börjesson, Kent
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Optical properties of the Czechoslovakian Fresnel lens measured using a laser beam1989In: ISES Solar World Congress, Kobe, Japan, 1989Conference paper (Refereed)
    Abstract [en]

    Linear glass Fresnel lenses have been experimentally investigated by means of a narrow He-Ne laser beam, both at normal incidence and at various combinations of meridional and sagittal angles of incidence. Both rays incident on the flat and on the grooved side were studied. Results were compared with previous ray tracing results by Franc et al. The experiments suggest, contrary to ray tracing, that the grooves should face the sun in other than sun-tracking applications.

  • 52.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Marks, Jörgen
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Co-generation of electricity and heat from combustion of wood powder utilizing thermophotovoltaic conversion1994In: First NREL Conference on Thermophotovoltaic Generation of Electricity, Copper Mountain, CO, USA, 1994Conference paper (Other academic)
    Abstract [en]

    The development of a thermophotovoltaic converter that uses combustion of wood powder as energy source has started with development of the combustion source. During the last few months, we have constructed and tested a feeding mechanism and a combustion chamber that seem very promising. We manage to keep a 10 kW flame steadily burning for several minutes at the time, generating a temperature exceeding 1400 K. The plans for continued development of this and other components of the converter are discussed in the paper.

  • 53.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Marks, Jörgen
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Development of a TPV converter for co-generation of electricity and heat from combustion of wood powder1994In: First World Conference on Photovoltaic Energy Conversion, Hawaii, USA, 1994Conference paper (Refereed)
    Abstract [en]

    Wood fuel has a high energy density, 18.3 MJ/kg dry matter, and it is combustible also in existing oil furnaces (in the range 1-15 MW) with little alteration. In principle, wood powder would be a possible fuel for small scale combustion, and we are in the process of developing such a furnace. During the last few months, we have constructed and tested a feeding mechanism and a combustion chamber that seem very promising. As of November 1994, we have reached 1481 K and been able to keep the temperature around 1400 K for any length of time at the time in one of our two prototype burners. A joint TPV R&D program, in which we cooperate with researchers at National Renewable Energy Laboratory, Golden, CO, USA, is in the planning, aiming at co-generation of electricity and heat from refined wood fuel.

  • 54.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Marks, Jörgen
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    TPV at RNEL - Report from a visit to National Renewable energy lab. Golden, Colorado, USA 28-29 Oct. 19931993Report (Other academic)
  • 55.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rönnelid, MatsDalarna University, School of Technology and Business Studies, Environmental Engineering.
    Proceedings of International Conference North Sun '881999Book (Other academic)
  • 56.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Binder, Betty
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Lindberg, Eva
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Use of nonimaging concentrators for moderate concentration of sunlight onto PV cells1989In: 9thy European Photovoltaics Solar Energy Conference, Freiburg, Tyskland, 1989Conference paper (Refereed)
    Abstract [en]

    The square cornet type nonimaging concentrator has been shown useful for moderate concentration of sunlight onto photovoltaic solar cells, since it creates no hot spots at the exit aperture. In this paper are presented the mathematical formulas on which the cornet designs are based, results from computer simulations on overall cornet performance compared with measurements as well as exit aperture intensity variations, measured optical concentration ratios under controlled circumstances, and cell temperature measurements under realistic circumstances. In an Appendix are given performance curves for a large number of cornets as determined from computer simulations, covering the useful range of concentration factors and acceptance angles.

  • 57.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, Björn
    Bergkvist, Mikael
    Wäckelgård, Eva
    Use of an integrating sphere for transmittance measurements on nonimaging concentrators1989In: North Sun´88, Borlänge, 1989Conference paper (Other academic)
  • 58.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Nordlander, Svante
    Analysis of a possible perfect nonimaging concentrator1986In: North Sun´86, Copenhagen, Denmark, 1986Conference paper (Other academic)
  • 59.
    Broman, Lars
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Sallah, S.O.A.
    On the role of solar electricity in rural development1987In: ISES Solar World Congress, Hamburg, 1987Conference paper (Other academic)
  • 60.
    Bååth, Andreas
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Investigation of Högskolans 1.44/1.8 kW PV system2003Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In this work an investigation of a low performing grid-connected PV system was conducted. The system totally consists of 72 PV modules of 45Wp each and two inverters. The investigation showed that the inverters were the main cause of the bad performance. One of the inverters performs more than 10% below the manufacturer’s specifications while the other one has completely stopped working. The PV modules in the system perform well and all installations have been properly conducted. To improve the system the best solution would be to buy a new inverter and connect all the modules to that one. Today the array is oriented to 30? south-east and the tilt is set to 60?. The output from the system could be increased with approxemately3.3% by changing the orientation of the modules directly to south and the tilt to 42?.

  • 61.
    Caicai, Xiong
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Long Term Heat Storage Using the Thermochemical Accumulator (TCA)2006Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Thermo-chemical accumulator (TCA) is chemical heat pump integrated high energy density heat storage. It could be used for heating or cooling. The purpose of this thesis work is to find out the suitable low temperature source which is between 5ºC to 30ºC. And size the system to find out the required collector and proper amount of lithium chloride for 3 climates (Stockholm, Zurich and Carpentras) The studies of low temperature source were base on the literature survey. 3 kinds of low temperature source were studied, which are domestic waste water, domestic exhaust air and group heating. System sizing was carried on by using simulation program called TRNSYS version 16. The charging process and discharging process was simulated separated. The reference house used in simulation was SFH30 from IEA-SHC task 26 and the weather data for Stockholm, Zurich and Carpentras were used in simulation. The results show that seasonal storage requires both large stores and relatively high source temperatures of free heat. For Carpentras the space heating load can be supplied with a machine with 1400 kg of LiCl salt together with 20 m2 flat plate collector and low temperature heating whereas 9650 kg and 30 m2 were required in Stockholm. In Stockholm, the source temperature needed to be above 15°C in order to get more than 95% of the space heating load delivered, whereas in Carpentras 8°C was sufficient. The conclusion is that ground heat is the most suitable heat source compare with other 2 sources. And the TCA have better performance and smaller size in Carpentras due to the relative higher solar radiation and smaller heat demand.

  • 62.
    Carera, Remy
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Resistance Between PV Cells and Thermal Absorber in a Photovoltaic/Thermal Solar System2003Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    A polyurethane PU solar heat collector was combined with polycrystalline silicon PV cells in a hybrid energy-generating unit that simultaneously produced low temperature heat and electricity. The solar radiation increases the temperature of PV modules, resulting in a drop of their electrical efficiency. By proper circulation of a fluid with low inlet temperature, heat is extracted from the PV modules keeping the electrical efficiency at satisfactory values. The extracted thermal energy can be used in several ways, increasing the total energy output of the system. Hybrid PV/T systems can be applied mainly in buildings for the production of electricity and heat and are suitable for PV applications under high values of solar radiation and ambient temperature. Because PV/T panels have higher energy output per unit surface area than a combination of separate PV panels and solar thermal collectors, they are especially useful where roof space is limited, like most of residential areas. In addition, the installation cost of a PV/T system is potentially much lower than the installation cost of separate PV and thermal systems.

  • 63.
    Carlqvist, Anneli
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Impact of heating system design on the performance of a solar combisystem2006Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    A solar combisystem is to replace a non-solar heating system in a single family house during 2006. It consist of two 60*60 units; a water storage tank and a technical unit. This solar combisystem was developed during the REBUS-project that aims to develop solar combisystem for Nordic conditions. The water storage tank has a solar storage volume and a hot water stand-by volume. The technical unit contains a condensing gas boiler, heat exchangers, pumps, switching valves, expansion vessel and control components. To work optimally, the REBUS solar combisystem needs low temperature strategy (<60°C). Both the solar collector and the natural condensing gas boiler benefit from low temperatures. This is mainly provided by having a low temperature Space Heating system. The Domestic Hot Water draw offs are at high temperature but during short periods. Space Heating is demanded continuously during a larger part of the year and was 85 % of the total annual heating energy consumption year 2005. To get a better understanding of the heating system’s impact on the REBUS solar combisystem, evaluation of measurement data from the single family house heating system was carried out during spring 2006. The interaction between the different components of the heating system was characterized. To get a view of the energy demand, losses and savings, a pre-study of different temperature and flow control strategies that could meet the space heating energy load was done with Trnsys simulations. The evaluation showed the importance of having a good control strategy for interaction between the Domestic Hot Water heating, the gas boiler, correct adjustment of the Space Heating, and the inhabitants living conditions. A bad adjusted heating system might give higher energy consumption and irregular heating. The simulations showed that it is possible to use lower temperature and flow rates and still fulfil the Space Heating load. In addition, the natural gas energy consumption could be reduced by 15%. The solar saving fractions calculated gave a range of 12-16% depending on control strategy.

  • 64.
    Castillo, Ezequiel
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Evaluation and characterization of a parabolic trough solar collector system2006Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In Cuernavaca, Morelos in the country of Mexico, the IIE (Electrical Research Institute) built a Parabolic Trough Solar Collector in order to have an experimental station and to satisfy the water heating demand used for sanitary services in a Automobile Company. The IIE built the system and put it on function but they did little theoretical research on it, and they are missing a very important factor which is the characteristic equation for this special collector. The best effort was done in order to complete this thesis, even thought lots of measurements where missing, and with other ones the values where not reliable as wanted. But with justifications and suppositions, the calculations where done and the objective was reached in the best way possible. Some recommendations are done too in order to get better values if the chance of make some tests to the collector appears, or if these equations are applied to other collectors. In the study first the equations in order to reach the theoretical values was made, then after some justifications for some values, the measured ones where introduced into the equations and the results where putted into tables and then into graphs, in order to watch better and identify better the resu

  • 65.
    Clauzonnier, Adrien
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Hybrid Charging Station Design for Electrical Transportation2004Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Depleting oil and gas reserves, combined with growing concerns of atmospheric pollution/degradation, have made search for energy from renewable sources of energy, such as solar and wind, inevitable. The main task of this project is to design a system running on renewable energy, particularly wind/PV, in order to promote “clean energies” to the tourist of Borlänge. The second task is to confront several designs in order to decide which one is the most cost effective using Life Cycle Cost analysis. In the present study, hourly mean wind-speed and solar radiation data for the period 1087-2003 recorded at the solar radiation and meteorological monitoring station, Borlänge (60.48?N, 15.43?E), Sweden, have been analyzed to investigate the potential of utilizing hybrid (wind/solar) energy conversion systems to meet the load requirements of a typical electrical chatging station for electric scooters and bikes (with summer electrical energy demand of 1106 kWh). The monthly average daily values for the summer period of solar radiation for Borlänge range from 2.9 kWh/m2 to 5.6 kWh/m2. The hybrid systems considered in the present analysis consist of different combinations of commercial I kW wind turbine, 85 Wp photovoltaic (PV) panels supplemented with battery storage unit and bio-ethanol back-up. The study shows that with one 1 kW wind turbine fitted with a 20 meters high tower together with 1.3 m2 PV, and 5 days of battery storage, the bio-ethanol back-up system has to provide 72% of the load demand. However, this system is not the most cost effective but it is the one matching the most the main tasks of this project which is to promote sustainable development and renewable energy by designing a hybrid charging station for electrical transportation.

  • 66.
    Csanyi, Laszlo
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Lacoste, Baptiste
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    The next generation of flat-plate solar collectors -design study & experiments2006Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    We investigated the possibilities of a new design of flat-plate solar collectors where the main idea is to replace the air inside the conventional design by a low conducting gas, even applying vacuum insulating techniques. During the report we outlined the basic principle of solar thermal collectors, the conventional design of flat-plate collectors and investigated the loss mechanism of these appliances in order to create the proper background for the steps we made and to reveal the importance of reducing heat losses by the mean of using insulating gases and/or vacuum in general. Similar solutions, such as insulating glass units, have been introduced to get another aspects on the problems we have with during the project. Design alternatives and different solution related to gas filling, sealing and various measurements have been placed inside the report, to reveal the possibilities; however many of these solutions was not proper for our purposes, mainly due to the financials. Hence, in most cases we fall back upon the simplest solution, however even with this, good results can be shown. Three experimental setup have been built form the materials what was collected in order to carry out heat loss measurements by using Carbon Dioxide, Argon and Argon+Vacuum insulation inside the setups. By proper tests we showed significant change in the overall heat losses. The main result is there is a 17% reduction in the overall heat losses while applying alloying Argon and vacuum, which is about 15% while having only Argon inside, compared to case when the same experimental setup was filled with air.

  • 67. Dahm, J
    et al.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Lorenz, Klaus
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Dalenbäck, J-O
    Six-Day System Test and Component test and System Simulation for Combitanks with Internal heat Exchangers1997Report (Other academic)
    Abstract [en]

    An international standard, ISO/DP 9459-4 has been proposed to establish a uniform standard of quality for small, factory-made solar heating systerns. In this proposal, system components are tested separatelyand total system performance is calculated using system simulations based on component model parameter values validated using the results from the component tests. Another approach is to test the whole system in operation under representative conditions, where the results can be used as a measure of the general system performance. The advantage of system testing of this form is that it is not dependent on simulations and the possible inaccuracies of the models. Its disadvantage is that it is restricted to the boundary conditions for the test. Component testing and system simulation is flexible, but requires an accurate and reliable simulation model. The heat store is a key component conceming system performance. Thus, this work focuses on the storage system consisting store, electrical auxiliary heater, heat exchangers and tempering valve. Four different storage system configurations with a volume of 750 litre were tested in an indoor system test using a six -day test sequence. A store component test and system simulation was carried out on one of the four configurations, applying the proposed standard for stores, ISO/DP 9459-4A. Three newly developed test sequences for intemalload side heat exchangers, not in the proposed ISO standard, were also carried out. The MULTIPORT store model was used for this work. This paper discusses the results of the indoor system test, the store component test, the validation of the store model parameter values and the system simulations.

  • 68. Dahm, Jochen
    et al.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Lorenz, Klaus
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Dalenbäck, Jan-Olof
    Evaluation of storage configurations with internal heat exchangers1998In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 62, no 6, p. 407-417Article in journal (Refereed)
    Abstract [en]

    An international standard, ISO/DP 9459-4A, 1996 has been proposed to establish a uniform standard of quality for small solar heating systems. In this proposal, system components are tested separately and total system performance is calculated using system simulations based on validated component model parameter values. Another approach is to test the whole system in operation under representative conditions, where the results can be used as a measure of the general system performance. Component testing and system simulation is flexible, but requires an accurate and reliable simulation model. The advantage of system testing is that it is not dependent on simulations and that it shows the actual system performance. Its disadvantage is that it is restricted to the boundary conditions for the test. The heat store is a key component concerning system performance. Thus, this work focuses on the storage system consisting of store, electrical auxiliary heater, internal heat exchangers (solar and load loops) and tempering valve. Four different storage system configurations with a volume of 7501 were tested in an indoor system test using a statistically generated six-day test sequence and a solar collector simulator. A store component test and system simulation was carried out on one of the four configurations, applying the proposed standard for stores, ISO/DP 9459-4A, 1996 and the MULTIPORT store model. Three test sequences for internal load side heat exchangers, not in the proposed ISO standard, were also carried out. This paper discusses the results of the indoor system test, the store component test, the validation of the store model parameter values and the system simulations. (C) 1998 Elsevier Science Ltd. All rights reserved.

  • 69.
    Deniz, Hikmet
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Improvement of Plastic Solar Collector for Falu Tank AB2004Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    A number of constraints have limited solar applications to a very small percentage of global energy utilization. One of these constraints which is the most important one is high cost of solar systems. Especially nowadays the future of solar energy market depends on solar energy system’s cost viability over the traditional energy system. Therefore the manufacturer and researcher are looking for the cheaper solar system options. Solar collector is the main component in a solar water heating system since efficiency of solar collector affects overall efficiency of whole system. This paper presents an analysis of a new solar collector which is made with fibre glass fabric reinforced polyester resin. Fibre glass fabric is relatively cheap material and which is already used as insulation material for underground tanks. A theoretical thermal analysis of 5 different design options was done in this work. Additionally theoretical optic and economic analysis of these designs were done. According to this theoretical calculations design numbered 4 which is top absorber plate design with glazing is the best design option both economical and energy efficiency way. Efficiency test of a prototype collector which is built based on theoretical calculations also have been done in order to get practical results and to evaluate the theoretical and practical cases. And result shows this collector especially in low temperatures is promising for the future using. However still further development of this collector is necessary in order to find optimum design. Also some other characterization tests should be done for various design options.

  • 70.
    Divine, Atsu
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    PV lighting at an office usings LEDs2006Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Although lighting systems powered by photovaltaics (PV) cells have existed for many years, they are not widely used, due to their high initial cost and low conversion efficiency. One of the challenges facing PV powered lighting systems has been how to use DC power generated by PV modules to energize light sources that are designed to function with AC power. Usually the efficacy of DC light sources is very poor compared to AC light sources. LED lighting bulb is a new technology which is fast growing with several diverging views about its efficiency and whether they can replace the conversional lamps. Following the introduction of white and high-power LEDs, many companies are developing products that aim to replace the traditional illumination sources. With the initial high cost of PV power the goal of all solar energy engineers is to improve efficiency and decrease the cost so it can be affordable. The first part of this research deals with replacing the conventional fluorescent lighting system in an office room with 12V DC powered LED lamps. The essence is to have the same illumination and comfort as what exist with the conventional lamps and compare the two systems. The second part deals with determining which portion of the electric load of SERC could be run on DC current. The conventional fluorescent lamps expend 168W power to provde the illumination in the office room with the six (6) bulbs that are used. However, it will take (43) 12-LED lamps, (17) 45-LED lamps, (40) 99-LED lamps and (15) 48-LED lamps; which sum up to 115 different LED lamps with different power consumptions to provide the same illumination. All put together, will expend 339W power whiles the lamps will cost 12187 SEK. In the second part, the electrical load of the office building (SERC) was determined and hence the possible equipment and and electrical load that could be run on DC. A total of 17.16MWh out of the 72.142MWh determined electrical load of SERC could be used on DC.

  • 71.
    Emde, Christoph
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Lowering Barriers for Implementation of PV water Pumping in Developing Countries2004Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This Master Thesis work evaluates water supply technologies based on photovoltaic energy conversion, in developing countries, analysing strengths and weaknesses of the technology at present time, highlighting the development is past decades as well as future opportunities. Alternative options for serving the purpose of rural water pumping are weighted vis-à-vis and their requirements and concepts are discussed from technical as well as non technical points of view. Technical solutions, applied during the last decades, and market available ones in recent days are being analysed and a proposal for a promising approach is being derived successively. A compiled checklist contains key-issues, being essential for overcoming barriers towards large-scale implementation of the technology. Attention has to be paid to reliability and price of course, but furthermore to the availability of spare part logistics, maintenance and repair services, being capable to achieve operation, free of significant time of idleness under no requirement of skills except those, being available on-site. Therefore the choice of components shall be oriented on the local offer of standardised products, such as industrial frequency converters, instead of specialized products. The technology should preferable be manufactured locally; installation, maintenance and repair as well as operation should. The infrastructural preparedness, providing spare parts logistics and services has to be given. Applications of photovoltaic water pumping in developing countries can be categorised in income generation and domestic use of pumped water. There is a large potential for PVP in livestock watering as irrigation already being used, due to the matter of fact, that obtained benefit can be expressed in monetary value and initial cost for the technology can be recouped. The situation concerning drinking water supply in rural villages is to be considered as more problematic from economic point of view. The supply of clan water, accompanied by the appearance of improved health, hygiene and secondary effects as increase in productivity and literacy are more challenging to be judged economically. Therefore funds are required to overcome the deficiency of financial means.

  • 72.
    Esechie, Felix
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Models of the PV/T (Photovoltaic/Thermal system) + TCA (Thermo chemical ackumulator) Tri-generation system2006Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The purpose of this thesis work is to develop models of a particular tri generation system (TCA + PV/T), with solar irradiation as the main source of waste heat. A tri generation system is one which delivers combined heating and power. In so doing the aim of the work will be to show the functionality of these developed models and how it works in three different climates (Madrid, Spain; Benin, Nigeria; Phoenix, USA) The method used in the development of these models is in the EES program (engineering equation solver) which is useful in the calculation of heat and energy equations. Composite models were combined and a final simulation was performed to give outputs of heat and cooling produced for the different climates. The results obtained are mixed, with the Phoenix climate given the best results by delivering the required load capacity to this system and with the Madrid climate being the most unlikely. The main conclusion is that for this tri generation system to be feasible a back up system is required for the constant running of the tri generation system

  • 73.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Combined solar and pellet heating systems: Studies of energy use and CO-emissions2006Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this study 4 solar and pellet heating systems have been studied with the help of annual dynamic simulations. Two of the systems comprised a pellet stove and two systems were solar combisystems; one with a store integrated pellet burner, the other with a separate pellet boiler. The aim was to evaluate their thermal performance and their CO-emissions. The systems have been modelled based on lab measurements of the single system components. The used models allow a detailed study of the dynamic behaviour of the systems. The stove systems have the least primary energy consumption provided the auxiliary electricity is taken into account with a conversion factor of 100%. If the auxiliary electricity is taken into account with a conversion of 40% and/or the systems are placed in the heated area the combisystems need less or a similar amount of primary energy. Modulating combustion power reduces the number of starts and stops and for most pellet units this reduces the total CO emissions. The obtained annual CO emissions are higher than the values obtained from the standard test methods. It was shown that the average emissions under realistic annual conditions were greater than the limit values of two Eco-labels. The system performance can be significantly improved by a proper control of the pellet heater and by sizing the pellet heater according to the size of the peak space heating demand. Based on these findings from the simulations two prototypes of a combined solar and pellet heating system has been designed, built and tested; one for the lab and one that has been installed in a demonstration house. The system is very compact and is suitable for detached houses with no heating room or little space for a heating system.

  • 74.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Optical and Thermal Performance of Load Adapted Solar Collectors2002Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This thesis is part of a research project about Load Adapted Collectors (LAC) for high latitudes at the Solar Energy Research Center (SERC) in Borlänge. Load adapted collectors have been studied regarding their optical and thermal performance. The aim of this kind of collector is to reduce the mismatch between solar radiation and heating load for locations with high latitudes like Sweden. Using the LAC in solar combisystems for domestic hot water and heating may also eliminate overheating problems in the summer months. Internal reflectors are used for the collectors to obtain a lower output in the summer and a higher gain in spring, autumn and winter. In order to keep the construction as simple as possible only flat cylindrical surfaces have been applied for the reflectors. Within the research project another thesis work has been accomplished by Fars Mustafa, which deals with theoretical models to optimise the geometry of the LAC. Based on his results two collector prototypes have been built and tested outdoors. The evaluation showed that the determined angular dependent optical efficiency suits with the values obtained from the theoretical analysis. Deviations for the first collector prototype can be explained mainly by optical imperfections of the reflector. The first prototype has a sharper pronounced angular dependency than the second model. The two prototypes show a similar thermal performance. Both have a U-value of about 2.6 W/m2K for a ?T=50K, which is an improvement of about 1.2 W/m2K in comparison with former prototypes. The second tested prototype uses a half sized bi-facial absorber, which has not result in lower heat losses. However, the application of the 70 mm wide absorber has the advantage of a slimmer collector and simplifies the integration into roofs. One year simulations for a test system using the parameter obtained from the measurements have been carried out. From the results can be seen that both collectors have a well load adapted behaviour. Nevertheless slight changes in the geometry still could improve the useful output from the first prototype and minimize the remaining overheating from the second prototype.

  • 75.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    The Application Of Renewable Energy For Prefab Houses In Germany2003Report (Other academic)
    Abstract [en]

    Within the framework of the REBUS project the German building industry has been investigated regarding their energy concepts. The intention was to evaluate the establishment of renewable energy sources on the German market for new built houses and prefab houses in particular. For this purpose the products of 85 manufacturers of prefab houses have been analyzed. Of special interest was the application of heating and hot water systems driven by solar energy and biomass. The results show that both techniques are well accepted and established. Almost 90% of the manufacturers offer solar systems on request and almost 70% heating systems based on Pellets. 24% offered solar and 7% as standard options in their range. From the achieved figures the potential of the Swedish market can be worked out. Strategies to introduce renewable energy to a greater extent to Swedish house manufacturers and builders might also be found.

  • 76.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    The state of the art of small-scale pellet-based heating systems and relevant regulations in Sweden, Austria and Germany2004In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 8, no 3, p. 201-221 Article in journal (Refereed)
    Abstract [en]

    The emphasis of this report is on the actual technology of small-scale pellet combustion units and important regulations concerning emissions and pellets. Wood as a heating source has a long tradition in Sweden, but the use of compressed wood pellets in domestic stoves and boilers is rather new. Based on a literature survey, information from manufacturers and test institutes, this report gives an overview about existing technology and investigates how mature it is already. Some comparisons were made to similar heating units in Austria, where this technique is also widely used. It could be seen that the Austrian boilers are more sophisticated including a high level of comfort for the user. On the other hand the simpler Swedish boilers are significantly less expensive, and it is questionable if Swedish costumers are willing to pay for the higher comfort. Relevant regulations concerning emissions and fuel quality are also reported and compared between Sweden, Germany and Austria. In addition some interesting non-official certificates and environmental labels are presented. These give an outlook to future, probably more stringent, regulations.

  • 77.
    Fiedler, Frank
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Nordlander, Svante
    Comparison of carbon monoxide emissions and electricity consumption of modulating and non-modulating pellet and solar heating systems2007In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 31, no 10, p. 915-930Article in journal (Refereed)
    Abstract [en]

    Emission and electricity consumption are important aspects of a pellet heating system. Low noxious emissions, particularly carbon monoxide, are a measure of a well-performing system. High carbon monoxide emissions are often caused by unnecessary cycling of the burner, poor adjustment of the combustion air and insufficient maintenance. The carbon monoxide output, the thermal performance and the electricity consumption for modulating and non-modulating operation mode have been investigated by simulations of four stoves/boilers as part of combined solar and pellet heating systems. The systems have been modelled with the simulation programme TRNSYS and simulated with the boundary conditions for space heating demand, hot water load and climate data as used in earlier research projects. The results from the simulations show that operating the pellet units with modulating combustion power reduces the number of starts and stops but does not necessarily reduce the carbon monoxide output. Whether the carbon monoxide output can be reduced or not depends very strongly on the reduction of starts and stops and how much the carbon monoxide emissions increase with decreased combustion power, which are in turn dependent on the particular settings of each pellet burner and how the heat is transferred to the building. However, for most systems the modulating operation mode has a positive impact on carbon monoxide emissions. Considering the total auxiliary energy demand, including the electricity demand of the pellet units, the modulating combustion control is advantageous for systems 1 and 4 for the used boundary conditions. The study also shows that an appropriate sizing of the stove or boiler has a huge potential for energy saving and carbon monoxide emission reduction.

  • 78.
    Fiedler, Frank
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Thür, Alexander
    Design method for solar heating systems in combination with pellet boilers/stoves2006In: EuroSun 2006, Glasgow, UK, 2006Conference paper (Other academic)
    Abstract [en]

    In this study an optimization method for the design of combined solar and pellet heating systems is presented and evaluated. The paper describes the steps of the method by applying it for an example of system. The objective of the optimization was to find the design parameters that give the lowest auxiliary energy (pellet fuel + auxiliary electricity) and carbon monoxide (CO) emissions for a system with a typical load, a single family house in Sweden. Weighting factors have been used for the auxiliary energy use and CO emissions to give a combined target function. Different weighting factors were tested. The results show that extreme weighting factors lead to their own minima. However, it was possible to find factors that ensure low values for both auxiliary energy and CO emissions.

  • 79.
    Fiedler, Frank
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Nordlander, Svante
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Thermal performance of combined solar and pellet heating systems2006In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 31, no 1, p. 73-88Article in journal (Refereed)
    Abstract [en]

    Various pellet heating systems are marketed in Sweden, some of them in combination with a solar heating system. Several types of pellet heating units are available and can be used for a combined system. This article compares four typical combined solar and pellet heating systems: System 1 and 2 with a pellet stove, system 3 with a store integrated pellet burner and system 4 with a pellet boiler. The often lower efficiency of pellet heaters compared to oil or gas heaters increases the final energy demand. Consequently heat losses of the various systems have been studied. The systems have been modeled in TRNSYS and simulated with parameters identified from measurements. For almost all systems the flue gas losses are the main heat losses except for system 3 where store heat losses prevail. Relevant are also the heat losses of the burner and the boiler to the ambient. Significant leakage losses are noticed for system 3 and 4. For buildings with an open internal design system 1 is the most efficient solution. Other buildings should preferably apply system 2 or 3. The right choice of the system depends also on whether the heater is placed inside or outside of the heated area. Unlike the expectations and results from other studies, the operation of the pellet heaters with modulating combustion power is not necessarily improving the performance. A large potential for system optimization exists for all studied systems, which when applied could alter the relative merits of the different system types.

  • 80.
    Fiedler, Frank
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Thür, Alexander
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Furbo, Simon
    The actual status of the development of a Danish/Swedish system concept of a solar combisystem2005In: Northsun, Vilnius, 2005Conference paper (Other academic)
    Abstract [en]

    At the beginning of 2003 the four year long research project REBUS on education, research, development and demonstration of competitive solar combisystems was launched. Research groups in Norway, Denmark, Sweden and Latvia are working together with partners from industry on innovative solutions for solar heating in the Nordic countries. Existing system concepts have been analyzed and based on the results new system designs have been developed. The proposed solutions have to fulfill country specific technical, sociological and cost requirements. Due to the similar demands on the systems in Denmark and Sweden it has been decided to develop a common system concept for both countries, which increases the market potential for the manufacturer. The focus of the development is on systems for the large number of rather well insulated existing single family houses. In close collaboration with the industrial partners a system concept has been developed that is characterized by its high compactness and flexibility. It allows the use of different types of boilers, heating distribution systems and a variable store and collector size. Two prototypes have been built, one for the Danish market with a gas boiler, and one for the Swedish market with a pellet boiler as auxiliary heater. After intensive testing and eventual further improvements at least two systems will be installed and monitored in demonstration houses. The systems have been modeled in TRNSYS and the simulation results will be used to further improve the system and evaluate the system performance.

  • 81. Furbo, Simon
    et al.
    Thür, Alexander
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Competitive solar heating systems for residential buildings2005In: Northsun, Vilnius, 2005Conference paper (Other academic)
  • 82. Furbo, Simon
    et al.
    Thür, Alexander
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rekstad, John
    Meir, Michaela
    Blumberga, Dagnija
    Rochas, Claudio
    Karlsson, Björn
    Nordic Energy Research Cooperation on Solar Combisystems2006In: Eurosun 2006, Glasgow, UK, 2006Conference paper (Other academic)
    Abstract [en]

    This paper describes ongoing research on solar combisystems for the Nordic and Baltic countries carried out within the projects "Competitive solar heating systems for residential buildings" and "Solar thermal components adapted to common building standards". The aim of the projects is to develop competitive solar combisystems which are attractive to buyers and to educate experts in the solar heating field.

  • 83.
    Gal, Csilla
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Szalay, Zsuzsa
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Energy Conscious Retrofit of Single Family Houses: Comparison of Sweden and Hungary2001Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The aim of this work is to study the possibilities for energy-conscious and environmental-friendly retrofitting of single-family houses in Sweden and Hungary. According to the climate, energetic, architectural characteristics of the countries, the following options were studied in more detail: additional insulation of buildings, passive solar gain systems and active utilization of biomass and solar energy. We choose two type houses in Hungary and Sweden to apply our knowledge in real retrofit situations. The engineering and architectural problems were examined based on energy, environment and economics and suggestions for retrofitting were made. The chosen type houses were named as “Kecel” and Pecel” for the Hungarian houses and Building A and B for the Swedish ones. In the original case, the Hungarian houses “Kecel” and “Pecel” had a heating demand of 36310 and 40195 kWh, respectively. The second house had a useful floor area of almost twice as big as that of the first one, however, due to the stricter norms and more careful choice of materials the heating demand was only slightly higher. The Swedish Building A and Building B had a yearly heating demand of 26670 and 17903 kWh, respectively. Building B similarly to “Pecel” was built later according to the standards and had bigger floor area. It is worth noticing that the Hungarian houses had a demand of almost twice as big as the Swedish houses, even though they were also not so well insulated. The first step that we considered was to add insulation to the boundary structures in every house. As it had been expected, the additional insulation was the most cost-efficient in case of the worst insulated structures and buildings. The heating demand of every house reduced significantly, however the most spectacular was the reduction in case of type house “Kecel”: from 36,310 to 36,638 kWh. In general, we can say that additional insulation of the houses should be the first step to consider. Our economical calculations also proved this. Especially if we consider the escalation of the fuel prices, avoiding the waste of energy becomes very important. As a next step, we considered the solar retrofit of the houses with solar domestic hot water and combi-systems. Both in Sweden and Hungary there is a great potential for solar applications. However, investing in solar is not always worth from the economical point of view. We optimised the system sizes according to the specific investment costs and made economical analysis. However, we did not get any rational payback periods for the systems applying average Swedish prices and current energy prices. Hopefully, in the future, the system prices are going to decrease due to improved designs and mass production. On the other hand, due to different reasons, the energy prices are probably going to increase in the near future in both countries. These factors might influence the implementation of solar energy positively.

  • 84.
    Garcia, Daniel Barandalla
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Monitoring of a Solar Combisystem Prototype2005Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This project work has been achieved in the Technical University of Denmark in the department of civil engineering. The project is carried out within the REBUS project (see ref. 15) that is researching on solar heating systems for combined space heating demand and hot water supply. In this case the prototype system is a solar combisystem with natural gas boiler. To ensure that the solar heating system object to study is working properly and it is able to guarantee the consumption of domestic hot water is a dwelling house and the required space heating, it is fundamental to have under control some basic parameters in the system. For this reason the monitoring of the system is essential and it is realized by placing in the correct place some sensors that give information about the temperatures of water flowing in the hydraulic circuit as well as the volume of water that is going through the pipes. To check all those parameters in the prototype system, several temperature sensors are installed in the hydraulic circuit, and also four flow meters that are going to measure the volume flow of water in the collector loop, DHW loop, space heating loop and boiler loop. To achieve the highest accuracy these devices have to be calibrated before being installed in the system. When the calibration of the flow meters and the temperature sensors is done and all the elements installed in the system, the measurement equipment is connected to a data logger that is programmed to receive and save all the data. The program designed for the data logger also calculates the amount of energy that is transferred in each one of the different loops in the system. At the end, the monitoring equipment is checked to prove that is is working properly and several tests charging and discharging the storage tank through different loops are performed to get an energy balance of each one of the processes. Not less important is to have under control other parameters as the temperature in the technical unit, where the natural gas boiler is placed and the humidity in the chimney of the natural gas boiler are going to be measured as well as the position of the different valves in the system to know in which direction the water is flowing through the different pipes.

  • 85.
    Giselbrecht, Andreas
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Feasibility Study - 50% Solar Fraction for an Office Building in Sweden2006Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Why 50% solar fraction? Because, reaching 50% solar fraction would mean that the auxiliary heating system that covers the heat load, in periods when solar energy is not available, becomes really an auxiliary. The thesis should therefore outline if a 50% solar fraction is feasible for the buildning where the Solar Energy Research Center (SERC) in Sweden is situated. By defining the heat load of the building it turned out that the realisation of optimization potentials at the ventilation system could reduce the heat load by 33% ( to 64.8 MWh). THe sizing procedure itself was divided in a rough and detailed sizing. For finding the optimum system size a compromise between given building realities and a system cost optimum has to be found. In addition, different temperature levels for space heating and domestic hot water were considered. The final decision was done in favour of a reduced temperature level since significant influences on system size and costs were outlined within the simulation.

  • 86.
    Guaxiao, Yao
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Analysis of Three-pipe Systems for Combined Heating and Cooling Distribution2001Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This study analyses the possibility of constructing combined district heating and cooling systems with a common return pipe, i.e. three-pipe systems (3P) instead of conventional four-pipe (4P) systems. In a 3P system the return temperatures vary widely during the season, from being close to the heating system return temperature at winter time to being close to the cooling system return temperature at summer time, depending on the combination between heating demand and cooling demand. In the chosen example in this paper (50% cooling load case) the temperatures are about 48?C (winter) and 25?C (summer), respectively. This lower return temperatures can be used for more effective operation of the biomass cooling plant by using stack gas condensers more effectively. On the other hand, this means also that more energy has to be supplied to the heating circuit and at the same time, a higher cooling capacity is necessary to cool down the return flow to the cooling supply temperature. In practice it means that in the 3P system energy is transferred from the heating circuit to the cooling circuit and either must be rejected by the cooling tower of the cooling circuit, or partially recovered by means of of a heat pump. The condenser of the heat pump is connected for preheating the water of the heating circuit. The general presumptions for the 3P systems investigated in the study are that the 3P system uses the same pipe trench as the 4P system and that both the heating and cooling systems, 4P as well as 3P, are layed at the same occasion over the same consumer area. However, it was assumed that in average only each 10th customer was connected to the district-cooling network. Furthermore, it was assumed that the network out of the heating/cooling plant is divided into two main stems. In the basic analysis, only the cost of the cooling equipment and pipes were included in the economic analysis, whereas the biomass heating plant was taken to be the same in all models. As to the operating cost, the price of electricity was chosen to 350 SEK/MWh and that of biomass fuel to 80 SEK/MWh. This cost difference reflects a typical situation in Swedish energy market. The investment costs were converted to annual costs by means of annuity rate of 8% (20 years, 5% interest). In the study, three different models are compared for 4P and 3P systems, respectively. Model 1 is the base case for completely separated heating and cooling systems in the 4P case; in 3P heat exchangers are used for recovering part of the energies, keeping the heating return temperature at 30?C whenever the common return temperature TR is below this value, and keeping the cooling temperature at 30?C, whenever TR is above that temperature. In Model 2, a heat pump is interconnecting the supply pipes of the cooling and heating circuits, recovering energy by means of its evaporator cooling, the cooling supply pipe and preheating the heating medium at the entrance of the biomass plant. The maximum preheating temperature (summer time) is 80?C (two-stage heat pump). By that way a large amount of the heat rejected in Model 1 can be recovered and the total energy of such a system is quite close to that of the totally separated 4P Model 1 system. However, an important part of the heating energy is electrical (compressor) work, and hence normally this is an expensive way of producing heat. For avoiding this disadvantage of Model 2, in Model 3 part of the cooling was achieved by a pre-cooling tower (3P system only), bringing down a large amount of the common return temperature at summer time to the cooling supply temperature and leaving only as much energy as necessary for the delivering the summer load to the heat pump. This system uses totally more energy than Model 2, but much less electricity and can therefore under some circumstances be more economic than Model 2. In all 3P cases, extra or larger equipment (heat exchangers, cooling towers, heat pumps) are used compared to the 4P systems. But the investment costs for this equipment can be compensated by lower costs for omitting one return pipe. So generally speaking, if cooling investment and pipe investment costs (heating plant costs not included) are compared, it can be seen that 3P systems generally have lower investment costs compared to 4P systems. The opposite holds for the operating costs (fuel and electricity). Those of the 3P systems are far above (Model1 and 2) or slightly above (Model 3) that of 4P systems. That also means that 3P systems are more energy intensive than 4P and therefore should in general not be applied for the reason of energy economy. In some occasions, where electricity prices are low, the comparison gives results indicating that the total annual costs of the 4P systems and 3P systems are quite similar at low cooling loads (25%), i.e. cases where the energy consumption of 3P and 4P systems does not differ too much. For these cases with low electricity prices, some favourable conditions for 3P systems could emerge. However, the differences are quite small and such systems need more detailed analysis of every application.

  • 87. Gustafsson, Kjell
    et al.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Niwong, Sigge
    Small scale utilization of renewable sources of energy: Reports from three conferences1991Report (Other academic)
  • 88.
    Haapaniemi, Hannu
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Evaluation of Properties and Performance of Low-cost Prototype Solar Collector2004Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Solar collector technology is looking for expansion towards low cost collectors. When low cost collector markets are increasing also the competition between manufacturers is reaching higher levels. Low cost collectors can offer new business opportunities for countries which have strong knowledge of plastic materials and automated production technologies . At the moment collectors from polypropylene materials are having leading market share of low cost collectors with rather good manufacturing technology and efficiency. Problems are still remaining with polymer materials and search for new materials and development of old ones is going on forward. Fibre glass fabric is old material and used as part of collectors also before. Prototype build by Falutank is made totally from fibre glass fabrics and laminated with polyester resin. Material properties are similar to other plastics. Major problem with low thermal conductivity is also similar. Prototype’s performance and characteristics have been measured in Borlänge , Sweden, at latitude 60?N. Standard ISO9806-1 was used as a reference for efficiency measures. Test results are showing that prototype can produce energy with efficiency curve similar to unglazed plastic collectors. Costs however are higher due to the manual manufacturing and high hourly labour costs. Costs are major preventing factor for prototype’s launching on market. To be able to compete with on-market products prototype collector must be designed differently to achieve not only higher performance but also radical savings in manufacturing costs. Results show also that glass fibre fabrics have potential to offer for low cost solar collector markets. To clarify how much potential there is requires still comprehensive development and these ideas are presented in this report. Hopefully the work for next prototype will go positively forward.

  • 89.
    Helgesson, Anna
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Evaluation of an EPS-MaReCo2001Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The MaReCo (Maximum Reflector Collector) is a specially designed collector that has been developed within the frames of a Swedish R&D-program concerning solar heat. The MaReCo is a stationary reflector collector adapted for Swedish conditions. With the purpose of reducing the collector costs a MaReCo-module was built in EPS (Expanded PolyStyrene). One advantage with this material is that it is easy to handle. One disadvantage is that it is sensitive for exposure of temperatures over 90oC duringlong periods. This is a temperature that is easily reached in a collector under stagnation. The purpose of this project has been to evaluate a prototype of the EPS-MaReCo. The prototype was placed at Vattenfall’s laboratory in Älvkarleby. Stagnation temperatures and energy output has been studied for both a reflector made of anodized aluminium foil and for a relector made of laminated aluminium foil: The highest absorber temperature that was reached during stagnation a sunny day was recorded to 238oC and the highest reflector temperature was 83oC. The measurements indicates that the collector prototype can handle stagnation. This conclusion is also confirmed with a visual analysis of collector module after the temperature measurements. The measurements also showed that there is no risk of too high temperatures being during normal operation. The performance evaluation was done according to the principle of dynamic testing. For the anodized reflector optical efficiencies of 0.59 and0.38 were determined for direct and diffuse radiation respectively. The heat loss factor was 1.60 W/m2,K. The same values for the laminated AL-reflector was 0.51, 0.38 and 1.22. With the simulating program Minsun, the yearly energy output was estimated to be 371 /323 / 246 kWh/m2 for the anodized reflector and 351 / 288 / 242 for the laminated at the operating temperatures 20 / 50 / 75oC

  • 90. Helgesson, Anna
    et al.
    Karlsson, Björn
    Krohn, Peter
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    PV-Panel with an Overedge Reflector for Northern Sun Conditions2001In: North Sun, Leiden, The Netherlands, 2001Conference paper (Other academic)
  • 91.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Ambiguous Artefacts: Solar Collectors in Swedish Contexts. On Processes of Cultural Modification2000Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This is a book about solar collectors and the place of these artefacts in a political energy debate that has aroused strong feelings in Sweden during the last twenty-five years. It is a book about the hopes for a less polluted earth, which solar collectors have come to symbolise, and a book about the ways in which problems in utilising solar energy are culturally perceived. One main aims of this study has been to find out more about the conflicting perceptions of solar collectors as 'saviours of the world' and simultaneously as uninteresting or less credible artefacts that 'may come in the future'. Another main purpose of the study has been to describe and explain those cultural processes of modification that are taking place around solar collectors in active attempts to integrate these into established cultural structures.

  • 92.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Can qualitative methods support the development of more flexible and energy saving thermal comfort?2006In: Comfort and energy use in buildings - getting them right, Windsor, UK, 2006Conference paper (Refereed)
    Abstract [en]

    This paper uses examples from a Swedish study to suggest some ways in which cultural variation could be included in studies of thermal comfort. It is shown how only a slight shift of focus and methodological approach could help us discover aspects of human life that add to previous knowledge within comfort research of how human beings perceive and handle warmth and cold. It is concluded that it is not enough for buildings, heating systems and thermal control devices to be energy-efficient in a mere technical sense. If these are to help to decrease, rather than to increase, energy consumption, they have to support those parts of already existing habits and modes of thought that have the potential for low energy use. This is one reason why culture-specific features and emotional cores need to be investigated and deployed into the study and development of thermal comfort.

  • 93.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Climate change and energy use: The role for anthropological research2005In: Anthropology Today, ISSN 0268-540X, E-ISSN 1467-8322, Vol. Vol. 21, no 3, no JuneArticle in journal (Refereed)
    Abstract [en]

    The expression 'global climate change' no longer designates merely a discourse on possible future risks; today it us used as a shorthand for specific ongoing events that are having a serious impact on the lives of people around the world. In the light of this change and consequent efforts to limit carbon dioxide emissions, contributions from social scientists are increasingly in demand within the study of energy use. My concern here is not whether intervention is a proper role for anthropologists, but rather how we may position ourselves within energy- and climate-related research.

  • 94.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Creating Diachronic Ethnographies: Reflections between fieldwork and analysis1996In: Antropologiska studier, ISSN 0345-0902, no Nr 54-55Article in journal (Other academic)
  • 95.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Equal Couples in Equal Houses: Cultural perspectives on Swedish solar and bio-pellet heating design2005In: Sustainable Architectures: Cultures and Natures in Europe and North America / [ed] Guy, S; Moore, S, Spon Press , 2005Chapter in book (Other academic)
    Abstract [en]

    Knowing how to design a heating system that will work mechanically is quite different from knowling how to design a system that users perceive as responsive to their domestic practices and values. In this chapter, social anthropologist Henning argues that the challenge for designers involved in the development or marketing of green buildings with heating systems that are based on renewable sources of energy is to see things from the perspective of those who are supposed to live in these buildings. The chapter focuses on three culture-specific aspects of Swedish households and single-family houses: perceptions of house and home, of private and public space, and of male and female space. Through these three angles, some clues are given as to how design, performance and location of solar and bio-pellet heating systems could be made to resonate with predominant experiences, habits and ways of thinking among both men and women.

  • 96.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    From electricity to pellet/solar - what goes on in the homes?2002In: Proceedings, Stockholm, 2002Conference paper (Other academic)
  • 97.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    In Bio-Fuel We Trust2006In: Biomass and Bioenergy: New Research / [ed] Brenes, M.D., New York: Nova Science Publishers , 2006, p. 125-140Chapter in book (Other academic)
    Abstract [en]

    In bio-fuel we trust. Or do we? In this chapter, ethnographic material from Sweden is used to discuss ways sin which trust may influence the choice of bio-fuel for heating purposes. The meaning and substance of trust or distrust, as well as the very conditions for trust, are elaborated on in relation to solar and bio-pellet systems, district heating with bio-fuel, and traditional fireplaces. An important conclusion of this chapter is that the degree to which people perceive others as being like themselves or not tends to be decisive for whether these others are to be trusted, and therefore worth listening to. The context and situation in which a certain heating system is being chosen does not only involve trust in individuals, however, but in companies and the authorities, as well as in the arterfacts themselves. An example is given on how distrust of district heating companies led house owners to reject an offer of district heating despite the comfort and environmental benefit this could have provided. it is shown how this distrust might be resolved by making the rhythm of households and sitrict heating companies more in step with one another. The strong emotional attachment to and deep-felt trust in the traditional fireplace is also analysed, and a question is put forward as to whether these feelings could be transferred to modern bio-pellet stoves. Finally, our great and assured trust in bio-fuel as a main solution to global climate change is shortly commented upon and partly questioned.

  • 98.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Kommunikation om kärnkraft: Ett jämförande perspektiv1991Book (Other academic)
  • 99.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Kvinnor och teknik 4: Utvärdering av ett SIDA-finansierat samarbetsprojekt mellan Karagweföreningen, Sverige, och KARADEA, Tanzania2003Report (Other academic)
  • 100.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Social Anthropological and Interdisciplinary Research on the Conversion of Electrically Heated Single Family Houses to Heating by Combined Pellet-Solar Systems2004In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, no 27, p. 547-555Article in journal (Refereed)
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