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  • 51.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Genomförande av en serie examensarbeten (magisteruppsatser) inom solelområdet under 20052005Report (Other academic)
  • 52.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Grundläggande förutsättningar för solfångare med interna reflektorer: en kunskapsöversikt1991Report (Other academic)
    Abstract [sv]

    Syftet med föreliggande rapport har varit att visa på de grundläggande egenskaperna för solfångare med interna reflektorer. Vidare tjänar rapporten syftet att ge en bild av dagsläget inom detta område och därigenom fungera som en utgångspunkt för forskning och utveckling kring solfångare med interna reflektorer för svenskt bruk. Arbetet har därför till stor del gått ut på att leta referenser genom tidskrifter och databaser. Den stora fördelen med CPC-solfångare, som är den klart dominerande typen av solfångare med interna reflektorer, består i dess låga värmeförluster, vilket gör dem attraktiva speciellt vid högre driftstemperaturer. De optiska egenskaperna hos olika typer av CPC-solfångare har grundligt studerats sedan mitten av 70-talet, medan studier av värmeförluster varit mer begränsad. Idag har forskningen och intresset för CPC-solfångare mattats av något, men fortsatt forskning pågår t ex i ett flertal länder, t ex USA, Israel, NordIrland och Japan. Endast en kommersiell tillverkare av CPC-solfångare har hittats (Portugal), vilken dock upphört p g a yttre ekonomiska faktorer. Japans CPC-teknologi anses stå närmast kommersiellt genombrott. Idag har utvecklingen av CPC-solfångare inriktats mot i huvudsak två koncept: 1. Stationära lågkoncentrerande CPC-solfångare för produktion av värme i området 60-100 grader C. Dessa konstruktioner är ofta enkla och man försöker minimera kostnaderna för dessa konstruktioner genom att minimera behovet av t ex reflektorer och isolering. Syftet med dessa är att konkurera med plana solfångare vilka producerar värme i samma temperaturintervall. Typiska solfångarparametrar 5 som rapporteras för denna typ är UL < 3.0 W/m2 ,°C och n0 = 0.65-0.75. 2. Stationära lågkoncentrerande CPC-solfångare för produktion av värme i området 100-300 grader C. Ofta bygger dessa på olika teknik för evakuering av absorbatorn, antingen genom att omsluta cirkulära absorbatorer med glasrör eller genom att införa CPC-reflektorer i heatpipes. Syftet med dessa är ofta att på ett billigt sätt producera högtemperaturvärme för olika industriprocesser, och därmed konkurera med koncentrerande solfångare typ paraboliska tråg eller traditionella heat-pipes. Beräkningar av vad en Svensk CPC-solfångare, baserad på de plana absorbatorer som finns på marknaden idag, kan prestera visar att årsutbytet av energi är jämförbart med de bästa svenska plana solfångaren som finns på marknaden idag då driftstemperaturen är ca 60-65 °C. För högre driftstemperaturer ökar skillnaden till CPC-solfångarens fördel. Vidare visas att årsutbytet har en jämnare fördelning över året jämfört, med vad en plan solfångare med samma prestanda har. Den högre prestandan vid höga driftstemperaturer och den jämnare fördelningen av energiproduktion över året gör solfångare med CPC-reflektorer intressanta för större solfångarfält, kopplade till nät med höga returtemperaturer och/eller solvärmesystem med säsongslager. Det är dock brist på undersökningar av värmeförluster i CPC-solfångare med låga koncentrationer och med plana absorbatorer, vilket är av intresse ifall de svenska erfarenheterna av plana solfångare skall tas tillvara. Potentialen med ytterligare reduktion av värmeförlusterna genom att införa extra konvektionshinder i kombination med plan absorbator har inte heller undersökts tillräckligt.

  • 53.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Optical and thermal properties of low-concentrating CPC-collectors for Swedish conditions1995Licentiate thesis, monograph (Other academic)
  • 54.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Optical design of stationary solar concentrators for high latitudes: Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and technology 3531998Doctoral thesis, monograph (Other academic)
  • 55.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rapport från en studieresa till Portugal 26/11-1/12 19911991Report (Other academic)
    Abstract [sv]

    Föreliggande rapport innehåller minnesanteckningar från en studieresa till Portugal 25/11- 2/121991. Syftet var framförallt att diskutera CPC-teknologi för solvärmeändamål med Manuel Collares-Pereira, CCE, Lissabon, inför ett fortsatt arbete med att utveckla CPC-teknologi i Sverige. Även andra institut och anläggningar besöktes och beskrivs i rapporten.

  • 56.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Solar energy in Karagwe, report from a study tour in Tanzania in July 19871987Report (Other academic)
  • 57.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Solcellspaneler med underliggande tillsatsreflektorer för svenskt klimat1996Report (Other academic)
    Abstract [sv]

    En numerisk studie av möjligheten att öka årsutbytet från solcellspaneler genom att använda underliggande tillsatsreflektorer har genomförts. Studien baseras på solstrålningsdata för Stockholm 1983-1991. Beräkningar har gjorts dels genom att beräkna den totala årliga energimängden som träffar panelen, dels den energimängd som träffar panelen om endast jämn belysning tillåts. Dessa två modeller antas motsvara de energimängder som kan tillvaratas av paneler av tunnfilmstyp respektive traditionella paneler uppbyggda av kristallina kiselceller. Om tillsatsreflektorn antas ha hög spekulär reflektans (rspec = 0.8) kan den årliga energimängden ökas med upp till 25 % med tillsatsreflektor. Denna ökning kan dock bli avsevärt större ifall reflektorn tillåts ändra lutning två gånger per år; 30-37% ökning ifall reflektorlängden är 2-5 ggr panelbredden. Fler lutningsändringar än 2 per år ger endast marginella ytterligare ökningar av den instrålade energimängden. Resultatet blir betydligt sämre då endast jämn belysning kan tillgodogöras av panelen jämfört med då ojämn belysning kan tillgodogöras. Detta indikerar att tillsatsreflektorer för att optimera utbytet från solcellspaneler på årsbasis framförallt är en teknik för paneler av tunnfilmstyp.

  • 58.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Solel i det svenska elnätet.: Hur man handskas med överproduktion från PV-anläggningar i framtiden2007Report (Other academic)
    Abstract [sv]

    Fortsätter dagens tillväxt av nätansluten solel kommer vi en gång i framtiden att nå dithän att produktionen av el tidvis överstiger efterfrågan, dvs att vi får en överproduktion av el. Med dagens Svenska elförbrukningsprofil över året, och antagandet att vi inte har någon annan typ av elproduktion då solen lyser, kan solcellsgenererad el stå för ca 9% av landets elförbrukning utan att överproduktion sker. Även om detta är ett hypotetisk scenario som ligger mycket långt fram i tiden är det viktigt att få dessa storleksordningar klara för sig då framtidens elförsörjning planeras. I denna studie har timväderdata från fem svenska mätstationer använts tillsamman med verkliga lastprofiler för hur elen används under året I Sverige. En programkod har skrivits för att beräkna utbyte från solceller med olika lutning och riktning på olika plaster i Sverige. Programmet har beräknat hur stor solcellsyta som kan installeras i Sverige utan att överproduktion av el sker och hur solcellsmoduler optimalt ska kunna vinklas då solcellsytan ökas ytterligare. Den solcellsyta som beräknats fram då elproduktionen under soliga dagar når elbehovet beskrivs som A0 och har för Sverige beräknats till 128 miljoner m2. Vidare har det studerats vad som händer om solcellsytan ökar utöver A0 och olika lutning och orientering av solcellsytan tillåts. Om Solcellsytan ökar till 2* A0 erhålls maximalt utbyte om solcellsmodulerna har samma lutning och orientering som i fallet med ytan A0. Överproduktionen I detta fall begränsas till 6% av den totalt genererade elen och solcellerna kan I detta fall täcka 17% av det årliga elbehovet i Sverige. Ökas solcellsytan ytterligare är lutningen och riktningen av solcellerna mindre viktiga då överproduktionen framförallt kommer från de solceller som riktas optimalt (dvs mot söder och en lutning kring 45grader). I Sverige kan den installerade solcellsytan fortsätta att växa till den täcker ca 15-17% av landets årliga elbehov innan överproduktion blir ett allvarligt problem. Ska solel täcka en store del av elbehovet än detta måste överproduktion accepteras, lagring av el implementeras eller elförbrukningsprofilen förändras.

  • 59.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Solen är afrikas GULD1987In: Medsols, ISSN 0281-918X, no 5, p. 16-17Article in journal (Other academic)
  • 60.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    The origin of the asymmetric annual irradiation distribution at high latitudes1999In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 19, p. 345-358Article in journal (Refereed)
  • 61.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    The origin of the asymmetry in the irradiation distribution at high latitudes1999In: North Sun, 1999Conference paper (Other academic)
    Abstract [en]

    The possibility of using solar energy during winter depends on the available solar radiation and on the geometry of the receiving surface. For high latitudes, the annual distribution of the available radiation is characterized by high asymmetry with a large amount of solar radiation from high altitude angles during the summer and a small amount of direct radiation from small altitude angles during the winter. This article deals with the origin of the difference between available solar radiation during summer and winter at high latitudes. Factors like the tilt of the earth’s axis, the eccentricity of the earth’s orbit, absorption and scattering of radiation in the atmosphere and seasonal changes in the weather conditions are discussed. Numerical examples of how these factors contribute to the reduction of the winter radiation compared to the summer radiation on surfaces with different orientation in Stockholm, latitude 59.4°N, are given. It is shown that the influence of the atmosphere and seasonal changes in the climate, and not pure earth-sun geometry, are the main reasons why it is hard to utilize solar energy at high latitudes during the winter.

  • 62.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Adsten, Monika
    T, Lindström
    P, Nostell
    E, Wäckelgård
    Optical Scattering from rough rolled aluminium surfaces2001In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 40, p. 2148-2158Article in journal (Refereed)
  • 63.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Lorenz, Klaus
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Nordlander, Svante
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Sol till både vatten och värme, Enkla åtgärder kan öka solvärmeutbytet2004Book (Other academic)
  • 64.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Estévez, Nicolás
    Potential of solar electricity in the Swedish electricity grid2008In: Eurosun 2008, Lissabon, Portugal, 2008Conference paper (Other academic)
    Abstract [sv]

    The purpose of the present work is to examine how much PV that can be installed in the Swedish electricity grid before occurrences of electricity production from PV exceeding the electricity consumption start to happen. This is important to know since the use of PV in the electricity grid can be assumed to increase rapidly in the next decades. If PV should have an important role in the future electricity mix, it is important to know how electricity production and electricity demand matches to be able to prepare that PV can have a significant share of the electricity production. With the electricity demand profile of today, Sweden will face a problem with electricity overproduction when PV panel production accounts for about 9% of total yearly electricity demand. If other non-interruptible electricity sources like some hydro power, nuclear power and wind energy are taken into account, even less solar electricity can be produced within the Swedish electricity grid. Although this scenario might be over a decade away from happening it is important to look ahead now and make sure that our current practices and standards do not lead us into trouble in the future.

  • 65.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Reserapport Plataforma SolarAlmeria, 5-8/6 20112012Report (Other academic)
    Abstract [sv]

    Reserapporten beskriver verksamheten vid Plataforma Solar Almeria (PSA) i Spanien och diskuterar tänkta samarbetsmöjligheter mellan PSA och Högskolan Dalarna

  • 66.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, B
    Experimental investigation of heat losses from low-concentrating non-imaging concentrators1996In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 57, p. 93-109Article in journal (Refereed)
  • 67.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, B
    Irradiation distribution diagrams and its use for estimating collectable energy1997In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 61, p. 191-201Article in journal (Refereed)
  • 68.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, B
    Optical properties of modified compound parabolic concentrators with linear corrugated reflectors1998In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 37, p. 5222-5226Article in journal (Refereed)
  • 69.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, B
    The use of corrugated booster reflectors for large solar collector fields1999In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 65, p. 343-351Article in journal (Refereed)
  • 70.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, B
    Krohn, P
    Wennerberg, J
    Booster reflectors for PV modules in Sweden2000In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 8, p. 279-291Article in journal (Refereed)
  • 71.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, Björn
    Construction and testing of a low-concentrating CPC-collector1994In: North Sun, Glasgow, Scotland, 1994Conference paper (Other academic)
  • 72.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, Björn
    Heat losses in solar collectors with internal reflectors1993In: ISES Solar World Congress, Budapest, Hungary, 1993Conference paper (Other academic)
  • 73.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, Björn
    Optimized truncation of a wide acceptance angle CPC2003In: ISES World Congress, Gothenburg, 2003Conference paper (Other academic)
  • 74.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, Björn
    The latitude dependent irradiation distribution in Europe and its implication for the design of stationary concentrators1998In: Eurosun 1998, Portoroz, Slovenia, 1998Conference paper (Other academic)
    Abstract [en]

    When a stationary solar concentrator is designed, the spatial distribution of the available irradiation is of vital interest. An irradiation distribution based only on solar geometry will look similar at different sites. The only difference is that the distribution of the incident irradiation is shifted to lower solar altitudes when latitude is increased. However, real irradiation distribution will show strong asymmetry at high latitude sites, since the winter irradiation is reduced by absorption and scattering in the atmosphere, and by seasonal changes in the climate. The reduced winter irradiation at high latitudes implies that the available annual radiation is concentrated to a narrower angular interval. This means that the degree of concentration that is possible increases with latitude. In the paper examples of irradiation distribution from different sites in Europe from latitude 38°N to 65°N are shown. The origin of the reduced winter irradiation with increased latitude is discussed, and numerical examples on the performance of different types of stationary concentrators for different latitudes are given.

  • 75.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, Björn
    The use of corrugated booster reflectors for large solar collector fields1995In: ISES Solar World Congress, Harare, Zimbabwe, 1995Conference paper (Other academic)
  • 76.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, Björn
    Gordon, J.M.
    The impact of high latitudes on the optical design of solar systems1996In: EuroSun 1996, Freiburg, Germany, 1996Conference paper (Other academic)
    Abstract [en]

    Irradiation distribution functions based on the yearly collectible energy have been derived for two locations; Sydney, Australia which represents a mid-latitude site and Stockholm, Sweden, which represents a high latitude site. The strong skewing of collectible energy toward summer solstice at high latitudes dictates optimal collector tilt angles considerably below the polar mount. The lack of winter radiation at high latitudes indicates that the optimal acceptance angle for a stationary EW-aligned concentrator decreases as latitude increases. Furthermore concentrator design should be highly asymmetric at high latitudes.

  • 77.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Krohn, Peter
    Perers, Bengt
    Karlsson, Björn
    Static Concentrators for Photovoltaic Modules at High Latitudes1996In: EuroSun 1996, Freiburg, Germany, 1996Conference paper (Other academic)
    Abstract [en]

    The paper gives an analysis of the performance of the photovoltaic modules with planar booster reflectors with variable length and tilts for Swedish conditions. The booster reflector for photovoltaic modules of crystalline silicon cells should be designed so that an even illumination over the module is obtained since the cells in the module are connected in series. However, if amorphous silicon or thin film modules are used, the module can be placed with the length of the cells extended north-south. In this geometry the cells which are connected in series in the module always obtain the same average irradiance, and reflectors of a shorter length can be used compared to a design where the whole module has to be evenly illuminated. A specular booster mirror with reflectance = 0.8 in front of an east-west aligned PV module with one third of the reflector area increases the annual irradiation by about 25% with allowance of uneven illumination on the module plane and no requirement for tracking. The additional cost for the reflectors is of the order of 10 % of the cost of the modules, which means that installation of a booster mirror is cost effective compared to increasing the module size.

  • 78.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, B
    Karlsson, B
    Construction and testing of a large area CPC-collector and comparison with a flat plate collector1996In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 57, p. 177-184Article in journal (Refereed)
  • 79.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, B
    Karlsson, B
    On the factorization of incidence angle modifiers for CPC-collectors1997In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 59, p. 281-286Article in journal (Refereed)
  • 80.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Karlsson, Björn
    Corrugated booster reflectors for large solar collector fields1994In: North Sun, Glasgow, Scotland, 1994Conference paper (Other academic)
  • 81.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Karlsson, Björn
    On the factorization of incidence angle modifiers for CPC-collectors1995In: ISES Solar World Congress, Harare, Zimbabwe, 1995Conference paper (Other academic)
  • 82.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Karlsson, Björn
    Optical properties of nonimaging concentrators with corrugated reflectors1994In: SPIE Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII, Freiburg, Germany, 1994Conference paper (Other academic)
  • 83.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Karlsson, Björn
    Krohn, Peter
    Cooling of PV modules equipped with low-concentrating CPC reflectors1999In: ISES Solar World Congress, Jerusalem, Israel, 1999Conference paper (Other academic)
  • 84.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Krohn, Peter
    Spante, Lennart
    Karlsson, Björn
    Active cooling of low-concentrating hybrid PV/Thermal collectors1999In: North Sun, Edmonton, Canada, 1999Conference paper (Other academic)
    Abstract [en]

    A series of measurements on the performance of solar cell string modules with low-concentrating CPC reflectors with a concentration factor C ˜ 4X have been carried out. To minimise the reduction in efficiency due to high cell temperatures, the modules were cooled. Four different way of cooling were tested: 1) The thermal mass of the module was increased, 2) passive air cooling was used by introducing a small air gap between the module and the reflector, 3) the PV cells were cooled by a large cooling fin, 4) the module was actively cooled by circulating cold water on the back. The best performance was given with the actively cooled PV module which gave 2,2 times the output from a reference module while for the output from the module with a cooling fin the value was 1,8. Active cooling is also interesting due to the possibility of co-generation of thermal and electrical energy which is discussed in the paper. Simulations, based on climate data from Stockholm, latitude 59.4°N, show that there are good prospects for producing useful temperatures of the cooling fluid with only a slightly reduced performance of the electrical fraction of the PV thermal hybrid system.

  • 85.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Krohn, Peter
    Spante, Lennart
    Karlsson, Björn
    Experimental performance of a string module in a CPC reflector cavity1998In: 2nd World Conf. on Photovoltaic Energy Conversion, Vienna, Austria, 1998Conference paper (Other academic)
    Abstract [en]

    The purpose of the work is to develop a cost effective semistationary CPC concentrator for a string PV-module. A novel method of using annual irradiation distribution diagram projected in a north-south vertical plane is developed. This method allows us easily to determine the optimum acceptance angle of the concentrator and the required number of annual tilts. Concentration ranges of 2-5x are investigated with corresponding acceptance angles between 5 and 15°. The concentrator should be tilted 2-6 times per year. Experiments has been performed on a string module of 10 cells connected in a series and equipped with a compound parabolic concentrator with C = 3.3X. Measurement show that the output will increase with a factor of 2-2.5 for the concentrator module, compared to a reference module without concentrator. If very cheap aluminium reflectors are used the costs for the PV-module can be decreased nearly by a factor of two.

  • 86.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Sonderen, Christiaan
    Asymmetrical awnings: a way to increase daylight in buildings without increasing the overheating2006In: Eurosun 2006, Glasgow, Scotland, 2006Conference paper (Other academic)
    Abstract [en]

    Different shapes of asymmetric awnings for east and west windows are investigated mathematically as well as by measurement in a model. A box with 90 cm side and a 30x30 cm window was placed outdoor in overcast weather and the daylight factor was measured at the bottom of the box when the window was unshaded or equipped with different awnings. The average daylight factor in the box decreased from 4.6% for the unshaded window to 1.0% when a full awning was used. With “the best” asymmetrical awning, the average daylight factor was 80% larger than with the full awing. Using Dutch climate, calculation of the energy from direct radiation transmitted through the window during the cooling season showed that this was decreased from 100% as an annual mean for the unshaded window down 22% with a full awing. With “the best” asymmetrical awning, 26% of the energy was transmitted. Calculation of the indoor temperature in a hypothetical row house in Netherlands show that the use of either normal or asymmetrical awnings considerable decrease the indoor temperature during the hot season. Therefore the use of asymmetrical awnings for east or west faced windows considerable can increase the daylight in buildings, with almost no change in overheating, compared to if traditional awnings are used.

  • 87.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Tepe, Rainer
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Solvärme och värmepump: utvärdering av ett värmesystem i Uppsala2004Report (Other academic)
  • 88.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Wik, Tina
    Träbyggande och energieffektivt byggande i Tyskland, Österrike och Lichtenstein: Rapport från Forum Holzbau09 och en studieresa i december 20092010Report (Other academic)
  • 89.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Wik, Tina
    Dalarna University, School of Technology and Business Studies, Construction.
    Janols, Henrik
    Dalarna University, School of Technology and Business Studies, Construction.
    Brännström, Mattias
    Helling, Håkan
    Lövenvik, Tommy
    Passive crosslaminated timber buildings: Final report Cerbof-project no. 762013Report (Other academic)
    Abstract [en]

    In this project, Stora Enso’s newly developed building system has been further developed to allow building to the Swedish passive house standard for the Swedish climate. The building system is based on a building framework of CLT (Cross laminated timber) boards. The concept has been tested on a small test building. The experience gained from this test building has also been used for planning a larger building (two storeys with the option of a third storey) with passive house standard with this building system.

    The main conclusions from the project are:

     It is possible to build airtight buildings with this technique without using traditional vapour barriers. Initial measurements show that this can be done without reaching critical humidity levels in the walls and roof, at least where wood fibre insulation is used, as this has a greater capacity for storing and evening out the moisture than mineral wool. However, the test building has so far not been exposed to internal generation of moisture (added moisture from showers, food preparation etc.). This needs to be investigated and this will be done during the winter 2013-14.

     A new fixing method for doors and windows has been tested without traditional fibre filling between them and the CLT panel. The door or window is pressed directly on to the CLT panel instead, with an expandable sealing strip between them. This has been proved to be successful.

     The air tightness between the CLT panels is achieved with expandable sealing strips between the panels. The position of the sealing strips is important, both for the air tightness itself and to allow rational assembly.

     Recurrent air tightness measurements show that the air tightness decreased somewhat during the first six months, but not to such an extent that the passive house criteria were not fulfilled. The reason for the decreased air tightness is not clear, but can be due to small movements in the CLT construction and also to the sealing strips being affected by changing outdoor temperatures.

     Long term measurements (at least two years) have to be carried out before more reliable conclusions can be drawn regarding the long term effect of the construction on air tightness and humidity in the walls.

     An economic analysis comparing using a concrete frame or the studied CLT frame for a three storey building shows that it is probably more expensive to build with CLT. For buildings higher than three floors, the CLT frame has economic advantages, mainly because of the shorter building time compared to using concrete for the frame. In this analysis, no considerations have been taken to differences in the influence on the environment or the global climate between the two construction methods.

  • 90. Spante, L
    et al.
    Andersson, M
    Perers, B
    Krohn, P
    Helgesson, A
    Karlsson, B
    Setterwall, C.M.
    Gröndalen, O
    Sunér, M
    Holmström, S
    Stolt, L
    Wennerberg, J
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Kjellsson, E
    Selhagen, L
    Sandell, P
    Forssander, M
    Andersson, B
    Ulvönäs, S
    Romero, M.A.
    Solel 97-99. Ett branchgemensamt FoU-program: Årsrapport 19971998Report (Other academic)
  • 91. Spante, L
    et al.
    Andersson, M
    Perers, B
    Krohn, P
    Karlsson, B
    Sunér, M
    Joensen, A
    Dahlöf, P
    Sporrborn, D
    Selhagen, L
    Sandell, P
    Forssander, M
    Stolt, L
    Wennerberg, J
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Kjellsson, E
    Johannesson, C.M.
    Andersson, G
    Romero, M.A.
    Solel 97-99. Ett branchgemensamt FoU-program: Årsrapport 19981999Report (Other academic)
  • 92.
    Tepe, Rainer
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Solfångare och värmepump: Marknadsöversikt och preliminära simuleringsresultat2002Report (Other academic)
  • 93. Tepe, Rainer
    et al.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Perers, Bengt
    Swedish solar systems in combinations with heat pumps2003In: ISES World Congress, Gothenburg, 2003Conference paper (Other academic)
  • 94. 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. 

  • 95.
    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.
    Design of gas filled solar collectors2010In: Eurosun 2010 / [ed] Vestlund, Johan, Graz, 2010Conference paper (Other academic)
    Abstract [en]

    With a suitable gas filling used between cover glass and absorber in a flat plate solar collector, it is possible achieving better thermal performance at the same time as the distance between absorber and glass can be reduced. Though, even if there is no vacuum inside the box, there will be potential risks for exhaustion due to stresses depending on the gas volume varies as the temperature varies. This study found out that it is possible build such a collector with less material in the absorber and the tubes and still getting better performance, without risks for exhaustion.

  • 96.
    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.

  • 97.
    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.
    Movements and mechanical stresses in gas-filled flat plate solar collectors2008In: Eurosun 2008, Lissabon, 2008Conference paper (Other academic)
    Abstract [en]

    Sealed gas filled flat plate solar collectors will have stresses in the material since volume and pressure varies in the gas when the temperature changes. Several geometries were analyzed and it could be seen that it is possible reducing the stresses and improve the safety factor of the weakest point in the construction by using larger area and/or reducing the distance between glass and absorber and/or change width and height relationship so the tubes are getting longer. Further it could be shown that the safety factor won't always get improved with reinforcements. It is so because when an already strong part of the collector gets reinforced it will expose weaker parts for higher stresses. The finite element method was used for finding out the stresses.

  • 98.
    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.

  • 99.
    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.

  • 100.
    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.

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