du.sePublications
Change search
Refine search result
12 1 - 50 of 64
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Ackeby, Susanne
    et al.
    STRI AB.
    Tjäder, Jonas
    Bastholm, Caroline
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The role and interaction of microgrids and centralized grids in developing modern power systems2017Conference paper (Refereed)
    Abstract [en]

    An extension of microgrids is now underway, primarily to allow increased electrification in growing economies but also to meet the need to reduce global CO2 emissions and to provide ancillary services to centralized grids. Energy access constitutes one of the fundamental building blocks for economic growth as well as social equity in the modern world. Access to sustainable energy is needed to achieve sustainable development. A microgrid should not be seen as a competitor to the centralized grid but as a complement.Through examination of several implemented cases from different parts of the world the following topics are considered: Analysis of the interaction between centralized grids and microgrids Analysis of stakeholder decision parameters for electrification Analysis of design differences and requirements for microgrids, depending on the intended purpose and the need of the end customer.It is determined that good planning, suitable requirements and clear regulations for microgrids (in relation to centralized grids) limits the risk of stranded assets and enables better business cases for the involved stakeholders.The paper is based on the discussion paper The role and interaction of microgrids and centralized grids in developing modern power systems – A case review publiced by ISGAN (International Smart Grid Action Network) Annex 6: Power T&D Systems.The discussion paper and further information about ISGAN is available at http://www.iea-isgan.org/.

  • 2.
    Andersen, Martin
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Chalmers University of Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dalenbäck, Jan-Olof
    Chalmers University of Technology.
    Techno-Economic Analysis of Solar Options for a Block Heating System2016In: Conference Proceedings: Eurosun 2016, Palma De Mallorca: International Solar Energy Society, 2016, , p. 16Conference paper (Refereed)
    Abstract [en]

    An innovative small solar district heating system with one central heating plant and four solar substations has been built in Vallda Heberg, Sweden, to supply a new housing area with passive houses. The target solar fraction was 40% and the total system design, including heat distribution in the buildings, was based on previous experience and aimed to be simple and cost-effective. The main aim of this study was to determine whether the system can be designed in a more effective manner by change of distribution system and load density. TRNSYS models were calibrated against measured data and then used to predict the energy performance. Results indicate that lower distribution heat losses can be obtained by change to a distribution concept with lower operating temperatures, while potentially reducing cost. Changes in heat density cause reduced distribution losses and boiler supplied heat demand, with only minor effects on solar system yield.

  • 3. Andrén, Lars
    et al.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Lennermo, Gunnar
    Handbok för kombinerade sol- och biovärmesystem: Teknik - System - Ekonomi2012Report (Other academic)
    Abstract [sv]

    Handboken beskriver olika solfångarkonstruktioner och solvärmekretsens ingående komponenter och ger en grundlig inblick i ackumulatortankens konstruktion och funktion. I boken finns förslag på systemutformning, olika tekniska lösningar och hur systemen bör styras och regleras. Handboken beskriver i första hand utformning-lösning-styrning av kombinationen sol- och pelletsvärme, men tar även upp solvärme i kombination med vedpannor, värmedrivna vitvaror och värmepumpar. Värmesystem med vattenburen värme är utmärkta att kombinera med solvärme, men det är i de flesta fall enklare att få till bra lösningar vid nyinstallation, än vid komplettering av befintlig anläggning. När solvärme och pelletsvärme ska kombineras finns det många alternativ till systemutformning. Det är viktigt att vattenburna pelletssystem utformas korrekt och kombineras på rätt sätt med solvärme för att komforten ska bli hög och elanvändningen låg. Vattenmantlade pelletskaminer med ett vattenburet värmesystem är extra intressant i kombination med solvärme. När eldningen upphör i samband med att värmebehovet avtar kan solvärmen ta över. En generell slutsats är att konventionella svenska pelletspannor med inbyggd varmvattenberedning inte är lämpliga i kombination med solvärmesystem. Den typen av bränslepannor ger komplicerade systemlösningar, höga värmeförluster och det är svårt att åstadkomma en tillräckligt bra temperaturskiktning i ackumulatortanken om varmvattenberedning sker i pannan. Solvärme för varmvattenberedning kan vara ett enkelt och bra komplement till pelletskaminer som genererar varmluft. För solvärmesystem är det viktigt att kraftig temperaturskiktning erhålls när värmelagret laddas ur. Det betyder att ackumulatortankens (eller varmvattenberedarens) nedre vattenvolym ska kylas ner till temperaturer som ligger nära ingående kallvattentemperatur. Ackumulatortankens mellersta del bör kylas till samma temperatur som radiatorreturen. Vid design av solfångarkretsen måste överhettning och stagnation kunna klaras utan risk för glykolnedbrytning eller andra skador på värmebärare eller rörkrets (och andra komponenter i kretsen). Partiell förångning minskar risken för att glykolen skadas då solfångaren når höga stagnationstemperaturer. Solfångarens glykolblandning tillåts koka (förångas) på ett kontrollerat sätt så att endast ånga blir kvar i solfångaren. Vätskevolymen i solfångaren samlas upp i ett större expansionskärl och systemet återfylls när vätskan kondenserar. Dränerande solfångarsystem med enbart vatten är ett möjligt alternativ till konventionella solfångare. De kräver en större noggrannhet vid installationen, så att sönderfrysning undviks. Dränerande systemlösningar är relativt ovanliga i Sverige. Om solfångaren under senhöst-vinter-tidig vår kan arbeta med att förvärma kallvatten från 10 till 20 ºC erhålls en betydligt bättre verkningsgrad på solfångaren (och framför allt ökar värmeutbytet då drifttimmarna ökar väsentligt) än om radiatorreturen (som i bästa fall ligger på temperaturnivån 30 - 40 ºC) ska förvärmas. Därför bör radiatorreturen placeras en bra bit upp från botten i ackumulatortanken och tappvarmvattnet ska förvärmas i en slinga som börjar i tankens botten. Om det finns ett VVC-system måste systemet anslutas på ett speciellt sätt så att ackumulatortankens temperaturskiktning inte störs. En viktig parameter vid ackumulatortankens utformning är att värmeförlusterna hålls låga. Det är viktigt för att klara tappvarmvattenlasten med solvärme under mulna perioder sommartid (men också för att hålla energianvändningen låg). I moderna hus, där ackumulatortanken i regel placeras i bostaden, blir det en komfortfråga att undvika övertemperaturer i det rum där värmelagret placeras. En bra standard på isoleringen (med minimerade värmeförluster) kräver att det finns ett lufttätt skikt över hela isoleringen som dessutom sluter tätt mot röranslutningar. Ofrivillig självcirkulation i anslutande kretsar som kan kyla av och blanda om ackumulatortankens vattenvolym, bör förhindras med backventiler och nedböjning av rören i isolerskiktet eller direkt utanför tanken.

  • 4.
    Azad, Mohammad
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Evaluation of an Energy System for multi-family houses with Combination of Exhaust Air Heat Pump and PV: Case Study: Demonstration Building of The EU Energy Matching Project, Sweden-Ludvika2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigated application of the heat recovery ventilation using an exhaust air heat pump and a roof top photovoltaic (PV) system for a group of three multi-family houses located in Ludvika, Sunnansjö. The buildings in the existing condition have mechanical ventilation and a centralized heating system consists of a pellet boiler as the main source and an oil boiler as back up.

    Exhaust air heat pump (EAHP) has been known by the previous relevant researches as an effective solution to promote the energy efficiency in the buildings. Furthermore, reduction in PV cost has made the PV as a financially viable option to be contributed in supplying electricity demand.

    In this respect, this thesis aimed to calculate the potential of energy saving in the case study using the combination of EAHP and PV. For this purpose, the buildings and the proposed energy system were simulated to enable the comparison of energy demand before and after the renovation. The simulation was gradually progressed through several phases and each stage created the prerequisites of the next.

    Since the buildings were relatively similar in terms of boundary conditions, one of the buildings were initially modeled and the concluded space heating (SH) demand was extrapolated to the three buildings scope. The simulation of the building was done using 3dimensional thermal model offered by Trnsys3d. The primary results were also calibrated against the available annual fuel consumption data. In the second phase, a pre-developed TRNSYS model of the energy system was completed using the result of previous step as the total SH demand as well as the estimated domestic hot water (DHW) consumption from a stochastic model. This simulation produced the electricity demand profile of the heat pump when the heat pump provided the total heat demand. Subsequently, the electricity consumption of the flats and operational equipment were estimated using stochastic model and available monthly measurement, respectively.

    Since the feasibility and optimal placement of 74 𝑘𝑊 PV modules offered for these buildings had been already examined by the author in another study, the final simulation were performed in an hourly basis considering PV production and total electricity demand; i.e. EAHP, flats consumption and operational equipment.

    The results of the simulation showed that 21 % of total electricity demand during a year could be supplied by the proposed PV system even without any electrical storage, whereas 74 % of total yearly PV production is consumed by the local loads. The results also proved that removing old inefficient oil boiler and supplementing the pellet boiler with the combination of EAHP and PV could mitigate the annual purchased energy (including electricity and pellet) by approximately 40 % compared to the current condition.

  • 5.
    Bales, Chris
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Betak, Jan
    Broum, Michal
    Chèze, David
    Cuvillier, Guillaume
    Haberl, Robert
    Hafner, Bernd
    Haller, Michel
    Poppi, Stefano
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Weidinger, Alexander
    Optimized solar and heat pump systems, components and dimensioning: Deliverable 7.3 - MacSheep - New Materials and Control for a next generation of compact combined Solar and heat pump systems with boosted energetic and exergetic performance2015Report (Other (popular science, discussion, etc.))
    Abstract [en]

    This report describes the optimised solar and heat pump systems developed in the MacSheepproject as well as the simulation results for these systems. Four systems have been developed by four different development groups, each with one private company participating. The development groups have chosen different types of systems as well as different target loads for their systems, which give a wide coverage of the potential markets. The aim of the project was to achieve a 25% performance increase compared to state of the art systems, while being cost-competitive compared to the state of the art.Two reference state of the art solar and heat pump systems have been defined, modelled,and simulated to derive benchmark electricity demands and SPF values for the boundary conditions that were defined for the MacSheep project. The reference systems usedtheground (boreholes) orair as a heat source for the heat pump. The chosen boundary conditions were the climates of Zurich and Carcassone, arealistic DHW load,and two buildings, one representing a modern low energy building (SFH45) and one representing an existing building (SFH100). These reference systems and boundary conditions were defined within the first year of the project, and are used throughout the project.New components were developed for the MacSheepsolar and heat pump systems and these developments are reported in the reportsof work packages 3 –6. Component models have been programmed and validated with laboratory measurements.In this report, simulation results for the four MacSheep systems arecompared to the relevant reference system in order to quantify the expected performance increase. These simulations include the component models with their validated parameters and performance obtained from phase 3 of the project.In addition, the costs of the systemswere estimated. The key performance indicator for the final system developments was defined as a figure for electric savings (25%) compared to the state of the art at competitive (i.e. comparable) cost. Therefore, cost-savings that were achieved for some of the components that were developed were allowed to be compensated by increased cost for other components or increased collector areasin order to show the project's achievements in the light of the defined key performance indicator.At present, the updated simulations show electric savings of 17%, 24%, 26%, and 30%, respectively, for the different developments and the different target heat loads.Threeof these systems will be built and tested during 2015,using the whole system test method that was further developed within the MacSheep project (see report D2.3 for more details). The results from these tests will give benchmark energy used of these systems both for the test sequence itself but also on an annual base. In addition, the simulation models described in this report will be verified against the measurements and then used for annual simulations for otherboundary conditionsthan the once that are represented in the test sequence.

  • 6.
    Bales, Chris
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Betak, Jan
    Broum, Michal
    Chèze, David
    CEA INES.
    Cuvillier, Guillaume
    Haberl, Robert
    Institut für Solartechnik SPF Hochschule für Technik HSR.
    Haller, Michel Y.
    Institut für Solartechnik SPF Hochschule für Technik HSR.
    Hamp, Quirin
    Poppi, Stefano
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Weidinger, Alexander
    Final report on storage developments in WP - Deliverable 5.4: MacSheep - New Materials and Control for a next generation of compact combined Solar and heat pump systems with boosted energetic and exergetic performance2015Report (Other (popular science, discussion, etc.))
  • 7.
    Baranger, Renaud
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Performance Analysis of a Grid-Connected PV System in Borlänge, Sweden2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis aimed to evaluate the performance of the new configuration of the array one of Högskolan Dalarna grid-connected PV system. This PV grid-connected system has been in operation since 1994. The system is composed of two arrays with a rated power of 1.62kW and two inverters of 1.2 kWp. In 2014 the new configuration of array one was composed of 4 strings of 9 modules each. This configuration had twice as much current than array two, and its voltage was halved (180V). The objective was to improve the global performance of the system, mostly under low irradiance conditions. The performance evaluation of the system was conducted according to IEC 61724 standard, and was performed in March and April 2014.

    It appeared that the higher current in array one improved the turn-on power of its inverter. While the inverter of array two started operating at 126W/m² the inverter of array one started at 37W/m². It was also shown that the array yield of array one increased by 1% at low irradiance (0-200W/m²) during the two months of this thesis work. Moreover, the input voltage dependency of the inverter was clearly shown. Halved the voltage in array one increased the inverter efficiency between 1% and 2%. It was shown that the higher current of the array one did not impact the losses of the system. The system losses also decreased between 9.4% and 10.5%. Besides, this work highlighted that arrays’ DC power was probably different. It led to a better performance of array two at high irradiance compare to array one. Eventually the performance ratio of array one was greater than array two during these two months. It reached 63.2% in March and 69.4% in April.

  • 8.
    Bastholm, Caroline
    Dalarna University, School of Technology and Business Studies, Energy Technology. IEA Photovoltaic Power Systems Programme.
    A user guide to simple monitoring and sustainable operation of PV-diesel hybrid systems: Handbook for system users and operators2015Report (Other (popular science, discussion, etc.))
    Abstract [en]

    This report contains a suggestion for a simple monitoring and evaluation guideline for PV-diesel hybrid systems. It offers system users a way to better understand if their system is operated in a way that will make it last for a long time. It also gives suggestions on how to act if there are signs of unfavourable use or failure. The application of the guide requires little technical equipment, but daily manual measurements. For the most part, it can be managed by pen and paper, by people with no earlier experience of power systems.The guide is structured and expressed in a way that targets PV-diesel hybrid system users with no, or limited, earlier experience of power engineering. It is less detailed in terms of motivations for certain choices and limitations, but rich in details concerning calculations, evaluation procedures and maintenance routines. A more scientific description of the guide can be found in a related journal article.

  • 9.
    Bastholm, Caroline
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Using locally available components and local knowledge to build sustainable stand-alone power systems2013In: Symposium Small PV-Applications : rural electrification and commercial use ; Ulm, Germany, June 17th/18th, 2013, Regensburg: Ostbayerisches Technologie-Transfer-Institut eV (OTTI) , 2013Conference paper (Other academic)
    Abstract [en]

    The aim of this paper is to point out benefits as well as disadvantages associated with the use of locally available, not necessarily standardized, components in stand-alone electrical power systems at rural locations. Advantages and challenges arising when the direct involvement in design, construction and maintenance of the power system is reserved to people based in the area of implementation are discussed. The presented research is centered around one particular PV-diesel hybrid system in Tanzania; a case study in which technical and social aspects related to the particular power system are studied.

  • 10. Bee, Elena
    et al.
    Prada, Alessandro
    Baggio, Paolo
    Psimopoulos, Emmanouil
    Dalarna University, School of Technology and Business Studies, Energy Technology. Uppsala University.
    Air-source heat pump and photovoltaic systems for residential heating and cooling: Potential of self-consumption in different European climates2019In: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, Vol. 12, no 3, p. 453-463Article in journal (Refereed)
    Abstract [en]

    Renewable sources will play a key role in meeting the EU targets for 2030. The combined use of an aerothermal source through a heat pump and a solar source with a photovoltaic (PV) system is one feasible and promising technology for the heating and cooling of residential spaces. In this study, a detailed model of a single-family house with an air-source heat pump and a PV system is developed with the TRNSYS simulation software. Yearly simulations are run for two types of buildings and nine European climates, for both heating and cooling (where needed), in order to have an overview of the system behaviour, which is deeply influenced by the climate. The storage system (electrical and thermal) is also investigated, by means of multiple simulation scenarios, with and without the battery and with different water storage sizes. The numerical results provide an overview of the performance of the considered heating and cooling system, as well as the balance of the electrical energy exchange between the grid, the building, and the PV array.

  • 11. Birchall, Sarah
    et al.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Wallis, Ian
    Dipasquale, Chiara
    Bellini, Alessandro
    Fedrizzi, Roberto
    Survery and simulation of energy use in the European building stock2016Conference paper (Refereed)
    Abstract [en]

    the work towards increased energy efficiency. In order to plan and perform effective energy renovation of the buildings, it is necessary to have adequate information on the current status of the buildings in terms of architectural features and energy needs. Unfortunately, the official statistics do not include all of the needed information for the whole building stock.

     

    This paper aims to fill the gaps in the statistics by gathering data from studies, projects and national energy agencies, and by calibrating TRNSYS models against the existing data to complete missing energy demand data, for countries with similar climate, through simulation. The survey was limited to residential and office buildings in the EU member states (before July 2013). This work was carried out as part of the EU FP7 project iNSPiRe.

     

    The building stock survey revealed over 70% of the residential and office floor area is concentrated in the six most populated countries. The total energy consumption in the residential sector is 14 times that of the office sector. In the residential sector, single family houses represent 60% of the heated floor area, albeit with different share in the different countries, indicating that retrofit solutions cannot be focused only on multi-family houses.

     

    The simulation results indicate that residential buildings in central and southern European countries are not always heated to 20 °C, but are kept at a lower temperature during at least part of the day. Improving the energy performance of these houses through renovation could allow the occupants to increase the room temperature and improve their thermal comfort, even though the potential for energy savings would then be reduced.

  • 12.
    Brandsma, Age
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Performance Evaluation for a Solar Assisted Air Conditioning System in Taipei2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report shows the study performed at Taipei National University of Technology in Taipei to evaluate the performance of a solar air conditioning system. The performance is evaluated under Taiwan climate conditions. The research is performed under summer weather conditions. No influence is done on these conditions. A solar air conditioning system currently available on the market is used. No changes are made to the system.

    The work to be done is divided into different phases in order to guide the process. First, a literature research is done to find similar research done on this topic and to gain a basic understanding of the topic. Then several measurement plans are made to investigate different parts of the system.. Measurements are done. It is tried to developing a computer model in order to be able to simulate the system performance.

    The overall objective was to gain knowledge about a solar assisted air-conditioning system and develop a model to simulate the system. Initially a list of research questions was made in order to quantify ‘gaining knowledge’ about the system. The plan was to answer them by using measurement data and creating a model to perform simulations. There are measurements done in this report, however due to too many ‘unknowns’* it is difficult to draw conclusions from them. A lot of research questions are still open and they are also not included in this report. It is also not succeeded to make a working model of a solar assisted air conditioner.

    It is succeeded in making a model to predict the performance of the evaporator. This model is currently within 11% accurate.

  • 13. Chèze, David
    et al.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Betak, Jan
    Broum, Michal
    Heier, Johan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Heinz, Andreas
    Franz, Hengel
    Hamp, Quirin
    Poppi, Stefano
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Final report on Control strategies, fault detection and on-line diagnosis in WP6 - Deliverable 6.4: MacSheep -New Materials and Control for a next generation of compact combined Solar and heat pump systems with boosted energetic and exergetic performance2015Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The main objective of this work package was to investigate generic control strategies, generic fault-detection and on-line diagnosis algorithms that may apply to the developed prototypes of solar and heatpump systems within MacSheep. The results should lead toimproved reliability and/orincreased energy savings for the end-userthrough new controller features. The use of DHW consumption forecast was identified as a promising control strategy and a simple yet reasonably effective algorithm to get the water tapping behaviourof the userwas developed. Viessmannimplemented the ideas of this approach in an ICT solution for their controller to provide statistical tapping informationto the user who can then set the period when hot waterthatis expected to be used. The operationalstrategy based on DHW consumptionforecast for one hour was not implemented since the potential gains are small (~2%) and there is ahigh user discomfort risk in the case of an inaccurate forecastPrevious studies have shown that solar overheating of the building led to gas savings with solar gas combisystems. Using a similar strategy on the MacSheep reference system did not lead to significant savings, due to strong interactions between space and DHW heating and a higher share of HP operation time for DHW charging of the store, which has a lower efficiency.Another smart control strategy was investigated forvariable electricity pricesusing overheating of the building and/or the DHW volume of the store.The main conclusion of the study is that the combination of the two algorithms led to cost savings for the Austria (Graz) and France (Chambery) with both theSFH45 and SFH100 buildings.Since only the share related to user consumption varies during the day while the grid and transmission costs are usually constant, thecost savings were small, far below 1%.Among the proposed fault detection algorithms for solar and heat pump systems, detection of wrongly connected tubes in the solar collector loop was found interesting by Viesmmann and Regulus. It was implemented and tested in their respective prototype controller. Regulus also implemented the detection of wrong order phase connections in its heat pump prototype as well as threshold tests on abnormal temperature and pressure evolution.

  • 14.
    Dermentzis, Georgios
    et al.
    Univeristy of Innsbruck.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Ochs, Fabian
    Univeristy of Innsbruck.
    Holmberg, Sture
    KTH.
    Feist, Wolfgang
    Passivhaus Institut.
    Calabrese, Toni
    University of Innsbruck.
    Oberrauch, Philipp
    University of Innsbruck.
    Evaluation of a versatile energy auditing tool2016Conference paper (Refereed)
    Abstract [en]

    Energy auditing can be an important contribution for identification and assessment of energy conservation measures (ECMs) in buildings. Numerous tools and software have been developed, with varying degree of precision and complexity and different areas of use.

     

    This paper evaluates PHPP as a versatile, easy-to-use energy auditing tool and gives examples of how it has been compared to a dynamic simulation tool, within the EU-project iNSPiRe. PHPP is a monthly balance energy calculation tool based on EN13790. It is intended for assisting the design of Passive Houses and energy renovation projects and as guidance in the choice of appropriate ECMs.

     

    PHPP was compared against the transient simulation software TRNSYS for a single family house and a multi-family house. It should be mentioned that dynamic building simulations might strongly depend on the model assumptions and simplifications compared to reality, such as ideal heating or real heat emission system. Setting common boundary conditions for both PHPP and TRNSYS, the ideal heating and cooling loads and demands were compared on monthly and annual basis for seven European locations and buildings with different floor area, S/V ratio, U-values and glazed area of the external walls.

     

    The results show that PHPP can be used to assess the heating demand of single-zone buildings and the reduction of heating demand with ECMs with good precision. The estimation of cooling demand is also acceptable if an appropriate shading factor is applied in PHPP. In general, PHPP intentionally overestimates heating and cooling loads, to be on the safe side for system sizing. Overall, the agreement with TRNSYS is better in cases with higher quality of the envelope as in cold climates and for good energy standards. As an energy auditing tool intended for pre-design it is a good, versatile and easy-to-use alternative to more complex simulation tools.

  • 15.
    El Kontar, Nabil
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Optimization of Grid-Connection Capacity for Wind Power Plants by Adding Photovoltaic Power2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A wind farm does not operate at nominal power output all the time around the year due to the intermittent nature of the wind and thus leaving a chance to further utilize the transformer rating by adding another power generation. Since the necessary infrastructure for grid connection has been already laid out for the wind farm, adding a certain capacity of photovoltaic power to the low voltage side of the transformer offers a potential to optimize the power production of the hybrid plant at a reduced initial investment. In this thesis, the study aims to optimize the power production of a grid connected wind farm by adding photovoltaic panels. The studied wind farm, located in Gotland Island in southern Sweden, contains three wind turbines with a nominal capacity of 150 kW each; totaling to 450 kW of wind power and coupled to the grid by a utility owned transformer of 500 kVA capacity. Total power production resulting from the addition of a certain photovoltaic power is analyzed on hourly basis in order to keep it below transformer’s rating. A total power production exceeding 500 kW will result in an overload and is reduced to 500 kW thus resulting in losses. Hourly wind power production data was provided by the operator for a period of one year, and solar irradiance data for the same year was obtained from SMHI “Swedish Meteorological and Hydrological Institute” for Gotland isle. The power production from a specified photovoltaic module was simulated for different photovoltaic capacities at different tilt angles and the estimated total generated power was analyzed with an aim to add as much photovoltaic power while keeping overloads to a minimum. In this studied case, the utility company owning the transformer requested that the maximum allowed power should be 450 kW (50 kW below the nominal rating) although previously the wind farm was allowed to deliver up to 550 kW active power. It is shown that the amount of photovoltaic power that can be added, while keeping lost power due to overloads at a minimum of 1% of total generated power, is highly dependent on transformer rating. The transformer rating of 450 kW 500 kW and 550 kW resulted in potential photovoltaic peak power of 125 kWp 325 kWp and 425 kWp respectively to be added. Optimizing the added photovoltaic power in a way to minimize total power standard deviation on yearly basis (series of twelve months) results in a recommended peak capacity of 500 kWp or 110% of the rated wind power, while a suitable transformer will be rated at 700 kVA.

  • 16.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    A testing and demonstration facility for PV systems and components2013In: Proceedings of 3rd Symposium Small PV Applications: Rural Electrification and commercial use / [ed] OTTI e.V., Regensburg, Germany, 2013, p. 111-116Conference paper (Other academic)
    Abstract [en]

    A test and demonstration facility for PV and PV hybrid systems and system components has been designed and installed at Dalarna University in Sweden. The facility allows studies of complete PV systems or single components in a range of 0.1-10 kW. The facility includes two grid-connected PV systems, a PV Hybrid off-grid system, three emulators and the necessary measurement and control equipment. Tests can be done manually or automatically through programmed test procedures controlled that will be implemented in Labview. The facility shall be used by researchers, professionals of the industry and engineering students.

  • 17.
    Fiedler, Frank
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Carbon monoxide emissions of combined pellet and solar heating systems2009In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 2, p. 135-143Article in journal (Refereed)
    Abstract [en]

    Emissions are an important aspect of a pellet heating system. Low harmful 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 and when the average load is below the lowest possible combustion power of the burner. Combining pellet heaters with a solar heating system can significantly reduce cycling of the pellet heater and avoid the inefficient summer operation of the pellet heater. Five combined systems representing the range of typical solutions of this system type and one recently developed system have been studied, modelled and simulated. These systems are compared to a reference system, which is based on a pellet boiler and is not combined with a solar heating system. The aim was to study CO-emissions of the different types of systems and to analyse the potential of CO-emission reduction when the pellet heater is combined with a solar heating systems. Another aim was to compare the yearly CO-emissions obtained from simulations under realistic dynamic conditions with the yearly CO-emissions calculated based on the values that are obtained by the standard test methods. The study was performed with the simulation tool TRNSYS. The parameter used in the study have been identified from lab measurements on existing pellet boilers/stoves and solar heating systems. The results from the simulations show that it is possible to almost halve the CO-emission if the pellet heater is combined with a solar heating system. The results also show that the CO-emission of existing combined solar and pellet heating systems can be drastically reduced if the pellet heater is properly controlled and some basic design rules are observed. This can also be seen when analyzing the results for the new system concept where these rules have been taken into account. Comparing the yearly CO-emissions obtained from the simulations with the yearly CO-emissions calculated based on the standard test methods shows that using the latter give too low CO-values for the whole year. It is also shown that for the existing systems the average emissions under these realistic annual conditions were greater than the limit values of two Eco-labels.

  • 18.
    Filatov, Artem
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Concentrating Collector for Torsång District Heating System2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis report for Dalarna University in Borlange and Absolicon company the study of a possibility to add an array of concentrating solar collectors to a Torsång district heating system was done. The whole idea of this work was to make a simulation of this kind of system, trying to get 15-20% of solar fraction, and make an economical evaluation.

    At the same time, another goal was to make two comparisons: between concentrating and flat-plate collector in the same system, and between two tools for collector analysis – Polysun and Absolicon tool, based on TRNSYS, which was designed to estimate the output of the collector for a certain temperature, without any load.

    During the study, the analysis of the simulating tools was made and the combination of those two tools was used. Using long iteration cycles, involving changing the field layout, number of collectors and distance between collector rows in flat-plate collector case, both types of collectors were analyzed. The method of the analysis was to get an equal output of the field and see the differences, which appear while using different collector types.

  • 19. Gu, Yaxiu
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Han, Mengjie
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Chen, Xiangjie
    Yuan, Yanping
    Techno-economic analysis of a solar photovoltaic/thermal (PV/T) concentrator for building application in Sweden using Monte Carlo method2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 165, p. 8-24Article in journal (Refereed)
    Abstract [en]

    The solar energy share in Sweden will grow up significantly in next a few decades. Such transition offers not only great opportunity but also uncertainties for the emerging solar photovoltaic/thermal (PV/T) technologies. This paper therefore aims to conduct a techno-economic evaluation of a reference solar PV/T concentrator in Sweden for building application. An analytical model is developed based on the combinations of Monte Carlo simulation techniques and multi energy-balance/financial equations, which takes into account of the integrated uncertainties and risks of various variables. In the model, 11 essential input variables, i.e. average daily solar irradiance, electrical/thermal efficiency, prices of electricity/heating, operation & management (OM) cost, PV/T capital cost, debt to equity ratio, interest rate, discount rate, and inflation rate, are considered, while the economic evaluation metrics, such as levelized cost of energy (LCOE), net present value (NPV), and payback period (PP), are primarily assessed. According to the analytical results, the mean values of LCOE, NPV and PP of the reference PV/T connector are observed at 1.27 SEK/kW h (0.127 €/kW h), 18,812.55 SEK (1881.255 €) and 10 years during its 25 years lifespan, given the project size at 10.37 m2 and capital cost at 4482–5378 SEK/m2 (448.2–537.8 €/m2). The positive NPV indicates that the investment on the selected PV/T concentrator will be profitable as the projected earnings exceeds the anticipated costs, depending on the NPV decision rule. The sensitivity analysis and the parametric study illustrate that the economic performance of the reference PV/T concentrator in Sweden is mostly proportional to solar irradiance, debt to equity ratio and heating price, but disproportionate to capital cost and discount rate. Together with additional market analysis of PV/T technologies in Sweden, it is expected that this paper could clarify the economic situation of PV/T technologies in Sweden and provide a useful model for their further investment decisions, in order to achieve sustainable and low-carbon economics, with an expanded quantitative discussion of the real economic or policy scenarios that may lead to those outcomes.

  • 20.
    Haddi, Jihad
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Thermal Evaluation of a Solarus PV-T collector2013Independent thesis Advanced level (degree of Master (One Year)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    Low concentrator PV-T hybrid systems produce both electricity and thermal energy; this fact increases the overall efficiency of the system and reduces the cost of solar electricity. These systems use concentrators which are optical devices that concentrate sunlight on to solar cells and reduce expensive solar cell area. This thesis work deals with the thermal evaluation of a PV-T collector from Solarus.Firstly the thermal efficiency of the low concentrator collector was characterized for the thermal-collector without PV cells on the absorber. Only two types of paint were on the absorber, one for each trough of the collector. Both paints are black one is glossy and the other is dull,. The thermal efficiency at no temperature difference between collector and ambient for these two types of paint was 0.65 and 0.64 respectively; the U-value was 8.4 W/m2°C for the trough with the glossy type of paint and 8.6 W/m2°C for the trough with dull type of paint. The annual thermal output of these two paints was calculated for two different geographic locations, Casablanca, Morocco and Älvkarleby, Sweden.Secondly the thermal efficiency was defined for the PV-T collector with PV cells on the absorber. The PV cells cover 85% of the absorber, without any paint on the rest of the absorber area. We also tested how the electrical power output influences the thermal power output of the PV-T collector. The thermal and total performances for the PV-T collector were only characterized with reflector sides, because of the lack of time we could not characterize them with transparent sides also.

  • 21.
    Heier, Johan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energirenovering av småhus - en förstudie2018Report (Other academic)
    Abstract [en]

    The building stock in Sweden is in great need of renovation, not least our single family houses. The need for renovation does not only consist of maintenance of the buildings, but also increased energy efficiency in order to reach set targets. It is not enough to only make changes to the heating systems, something that is especially common among single family houses in the form of switching to a heat pump, but improvements to the building envelope are also required. Extensive and a broad range of activities have been made for multifamily buildings but for single family houses only smaller, more directed activities have been made. This can partly be due to the difficulty of reaching out to the approximately two million single family house owners in the country who form a much diversified group, with different motivations and wishes (even within the same household), economic conditions and interest for energy renovation.

     Dalarna University has previously performed a number of studies on energy renovation of single family houses from various perspectives, but no holistic study. This study aims to do a review of the knowledge in the field and also engage in a dialogue with chosen actors during seminars and workshops, in order to investigate how the development of energy renovation for single family houses can be moved forward on a national level.

     The study shows that there is a large potential for energy renovation in the single family house stock, but also many barriers that must be overcome. These barriers are to a smaller degree technical, but instead other problem areas dominate such as financing, lack of suitable policy instruments, lack of knowledge among involved actors, regulations etc.. The study has not been able to identify good examples of frameworks covering all the necessary aspects in order to encourage single family house owners to perform energy renovations of sufficient scale. Additionally, the large number of actors required to undertake an extensive energy renovation means that a high level of knowledge, a wide network of contacts and a large commitment are required; something found in few single family house owners. There is also no clear stakeholder willing to engage in this type of turnkey design and building contracting for single family houses.

     The overall assessment of the key actors involved in this pre study is that a broad commitment is required in order for the single family house sector significantly contributing to set targets for improved energy efficiency in buildings. The commitment must be long term as well as including multi- and interdisciplinary research and business development in order to lay the foundations for relevant and effective policy instruments and awareness increasing knowledge interventions.

  • 22.
    Heier, Johan
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology. KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Martin, Viktoria
    Department of Energy Technology, KTH.
    Combining Thermal Energy Storage with Buildings: A Review2015In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 42, p. 1305-1325Article in journal (Refereed)
    Abstract [en]

    Thermal Energy Storage (TES) has been a topic of research for quite some time and has proven to be a technology that can have positive effects on the energy efficiency of a building by contributing to an increased share of renewable energy and/or reduction in energy demand or peak loads for both heating and cooling. There are many TES technologies available, both commercial and emerging, and the amount of published literature on the subject is considerable. Literature discussing the combination of thermal energy storage with buildings is however lacking and it is therefore not an easy task to decide which type of TES to use in a certain building. The goal of this paper is to give a comprehensive review of a wide variety of TES technologies, with a clear focus on the combination of storage technology and building type. The results show many promising TES technologies, both for residential and commercial buildings, but also that much research still is required, especially in the fields of phase change materials and thermochemical storage.

  • 23.
    Heinz, Andreas
    et al.
    Institute of Thermal Engineering Graz University of Technology.
    Hengel, Franz
    Institute of Thermal Engineering Graz University of Technology.
    Mojic, Igor
    Institut für Solartechnik SPF Hochschule für Technik HSR.
    Haller, Michel Y.
    Institut für Solartechnik SPF Hochschule für Technik HSR.
    Poppi, Stefano
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Matuska, Tomas
    Czech Technical University in Prague, Faculty of Mechanical Engineering.
    Sedlar, Jan
    Czech Technical University in Prague, Faculty of Mechanical Engineering.
    Petrak, Jiri
    Czech Technical University in Prague, Faculty of Mechanical Engineering.
    Final report on heat pump developments in WP 4 - MacSheep Deliverable 4.4: MacSheep -New Materials and Control for a next generation of compact combined Solar and heat pump systems with boosted energetic and exergetic performance2015Report (Other (popular science, discussion, etc.))
  • 24.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Popularisering och spridning av forskningsresultat2000Report (Other academic)
  • 25.
    Hernandez Velasco, Marco
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Performance Evaluation of Different PV-Array Configurations under Weak Light Conditions and Partial Shadings2012Independent thesis Advanced level (degree of Master (One Year)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    The paper analyses empirical performance data of five commercial PV-plants in Germany. The purpose was on one side to investigate the weak light performance of the different PV-modules used. On the other hand it was to quantify and compare the shading losses of different PV-array configurations. The importance of this study relies on the fact that even if the behavior under weak light conditions or the shading losses might seem to be a relatively small percentage of the total yearly output; in projects where a performance guarantee is given, these variation can make the difference between meeting or not the conditions.When analyzing the data, a high dispersion was found. To reduce the optical losses and spectral effects, a series of data filters were applied based on the angle of incidence and absolute Air Mass. To compensate for the temperature effects and translate the values to STC (25°C), five different methods were assessed. At the end, the Procedure 2 of IEC 60891 was selected due to its relative simplicity, usage of mostly standard parameters found in datasheets, good accuracy even with missing values, and its potential to improve the results when the complete set of inputs is available.After analyzing the data, the weak light performance of the modules did not show a clear superiority of a certain technology or technology group over the others. Moreover, the uncertainties in the measurements restrictive the conclusiveness of the results.In the partial shading analysis, the landscape mounting of mc-Si PV-modules in free-field showed a significantly better performance than the portrait one. The cross-table string using CIGS modules did not proved the benefits expected and performed actually poorer than a regular one-string-per-table layout. Parallel substrings with CdTe showed a proper functioning and relatively low losses. Among the two product generations of CdTe analyzed, none showed a significantly better performance under partial shadings.

  • 26.
    Hernandez Velasco, Marco
    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.
    Timm, Dirk
    juwi Solar GmbH.
    COMPARISON OF PARTIAL SHADING LOSSES IN FREE FIELD PV-PLANTS WITH DIFFERENT ARRAY CONFIGURATIONS2013In: EU PVSEC Proceedings, 2013, p. 4171-4175Conference paper (Other academic)
    Abstract [en]

    A common problem when planning large free field PV-plants is optimizing the ground occupation ratio while maintaining low shading losses. Due to the complexity of this task, several PV-plants have been built using various configurations. In order to compare the shading losses of different PV technologies and array designs, empirical performance data of five free field PV-plants operating in Germany was analyzed. The data collected comprised 140 winter days from October 2011 until March 2012. The relative shading losses were estimated by comparing the energy output of selected arrays in the front rows (shading-free) against that of shaded arrays in the back rows of the same plant. The results showed that landscape mounting with mc-Si PV-modules yielded significantly better results than portrait one. With CIGS modules, making cross-table strings using the lower modules was not beneficial as expected and had more losses than a one-string-per-table layout. Parallel substrings with CdTe showed relatively low losses. Among the two CdTe products analyzed, none showed a significantly better performance.

  • 27.
    Hernandez Velasco, Marco
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Timm, Dirk
    juwi Solar GmbH.
    Weak light performance efficiency in installed pv-arrays of different module technologies2014In: 29th European Photovoltaic Solar Energy Conference and Exhibition Proceedings, 2014, p. 2515-2522Conference paper (Other academic)
    Abstract [en]

    This work analyses the weak light performance efficiency of six different free field and grid-connected PVarrays of various module technologies (mc-Si, CIGS, CdTe). The installed capacities per array range from 1,8kWp to 2,2kWp. The studied systems are located at the same site in Germany and are mounted on a ventilated and shaded-free structure. The irradiance was measured with both a pyranometer and a c-Si reference cell oriented at the plane of the array. Besides the weather conditions, the arrays share a similar system configuration (same inverter model, rack type and orientation, temperature sensors, etc.) making their results highly comparable. The data collected comprised 312 days from September 2011 until July 2012. When analyzing the data points at moments of low irradiance (< 800W/m2), a high dispersion was found which is most likely due to optical effects, different spectral distributions and changing module temperatures. To reduce the optical and spectral effects, a series of data filters were applied to limit the points used (Air Mass ≤4 and Angle of Incidence ≤50°). To compensate for the temperature effects and translate the values to STC (25°C), five different methods were assessed. The Procedure 2 of the IEC 60891 was considered the most suitable due to its relative simplicity, availability of parameters in the datasheets, good accuracy even with missing values, and the potential to improve the results when the complete set of inputs is available. The final analysis of the weak light performance showed no clear superiority of any particular PV-technology. From the results of this study, an overall advantage of thin-film over crystalline modules cannot be anymore concluded.

  • 28.
    Hernandez Velasco, Marco
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Mattsson, Anders
    Dalarna University, School of Technology and Business Studies, Forest and Wood Technology.
    Cultivation of forest regeneration materials under artificial radiant sources—effects of light intensity on energy consumptionand seedling development2014In: The International Forestry Review Vol.16 (5), 2014 / [ed] John A. Parrotta, Cynthia F. Moser, Amy J. Scherzer, Nancy E. Koerth and Daryl R. Lederle, 2014, Vol. 16, no 5, p. 300-300Conference paper (Other academic)
    Abstract [en]

    In times of major environmental challenges and increasing demand for forest products, planted forests have acknowledgedadvantages compared to other land uses. Despite not being able to completely take the place of natural forests, planted ones have,if properly managed, great potential to contribute in addressing these problems. Besides the ecological benefi ts such as carbonsequestration, planted forests can help meet the demand for wood products without further depletion of the natural forest. Forestrestoration, rehabilitation, and reforestation are limited by the capacity for producing forest regeneration materials. Often, asproduction is intensifi ed at forest nurseries, the practices begin to have an adverse impact on the environment and stop being trulysustainable. One of the main issues in nurseries is the energy consumption for grow lights during periods of short daylight.By using high-effi ciency LED grow lamps and adjusting the light intensity, this study aimed to reduce the energy consumptionfrom lighting per seedling without compromising seedling development. The precultivation of Picea abies and Pinus sylvestrisseedlings was done during 5 weeks under controlled conditions at 20 °C and a relative humidity of 60%. The photoperiod was16 hours at an intensity ranging from 50 to 350 μmol/m2/s in intervals of 50 μmol/m2/s intervals.

  • 29.
    Hernandez Velasco, Marco
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Mattsson, Anders
    Dalarna University, School of Technology and Business Studies, Forest and Wood Technology.
    Energy efficiency in intensified production of forest regeneration materials – design of a photovoltaic system for sustainably powering an innovative forestry incubator2014In: The International Forestry Review Vol.16 (5), 2014 / [ed] John A. Parrotta, Cynthia F. Moser, Amy J. Scherzer, Nancy E. Koerth and Daryl R. Lederle, 2014, Vol. 16, no 5, p. 393-393Conference paper (Other academic)
    Abstract [en]

    Planted forests can contribute addressing problems of global concern such as climate change mitigation, biodiversity lost and pressure on ecosystems due to high demand of forestry products. However, in order to be able to profit from these benefits sustainably, production rates of forest regeneration materials should be higher than the harvesting rates. Nevertheless, intensive production methods often bring along adverse consequences for the environment. In the frame of the ZEPHYR project, funded by the European Commission under the Seventh Framework Programme (FP7), innovative and cost-friendly technologies for the pre-cultivation are being developed. They will be integrated into a functional and transportable system for a large scale production of seedlings, with zero-impact on the environment and not affected by outdoor conditions. To achieve this, high efficiency devices with low energy consumption will be used and the incubator will be powered by solar energy. This work aims to present the efforts made to reduce the energy loads and optimize the photovoltaic (PV) system. The power system will also be capable of connecting to the electricity grid, using a diesel generator as a back-up, and a battery bank with at least one day of autonomy (up to 7 kWh/day) in central European latitudes.   

  • 30.
    Hernandez Velasco, Marco
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Pérez-Mora, Nicolás
    University of Balearic Islands and Sampol Ingenieria y Obras.
    Marras, Tatiana
    Universita degli Studi della Tuscia.
    Using Hybrid Solar Photovoltaic + Combined Heat and Power Systems (PV+CHP) to Enable Industrial Scale Indoor Plant Cultivation: a Feasibility Study2016Conference paper (Other academic)
    Abstract [en]

    A rapid population growth linked to intensive agriculture has originated several problems such as soil degradation, groundwater depletion, forestland transformation, and eutrophication of aquatic systems. Vertical farming offers an alternative for producing plants indoors in a resources and space efficient manner, reducing leakage of chemicals, optimizing water and land use, and allowing year-round cultivation. Controlled environment agriculture (CEA) also enables urban residents to access locally grown plants that would have otherwise been imported from far away, reducing transport and storage emissions. This comes with a caveat: the energy loads increase to provide artificial illumination and keep an optimal climate. To address this issue, the present work studies the feasibility of using a hybrid photovoltaics and combined heat and power system (PV+CHP) to satisfy the energy demands of an industrial-sized growth room. For this, different European locations and climates have been considered as well as various growth protocols.

  • 31.
    Hernandez Velasco, Marco
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    R Pamidi, Sreenivaasa
    Exergy Ltd..
    The Zephyr concept and the energetic autonomy2014In: CAFFEINA 2014: Il Futuro e le Radici - The Future and the Roots, 2014Conference paper (Other academic)
    Abstract [en]

    Currently, forest ecosystems are facing many sustainability problems due to drastic climate changes and extreme exploitation of their resources. Planted forests can contribute to more sustainable practices and help addressing some of these issues. In order to be able to profit from these benefits sustainably, production rates of forest regeneration materials should be higher than the harvesting rates. Nevertheless, intensive production methods often bring along adverse consequences for the environment.

    At the moment, there exist several options such as greenhouses or plant growth chambers that allow producing forest materials more rapidly. Unfortunately these systems consume considerable high amounts of energy for lighting, acclimatization and irrigation having a negative impact on the environment.

    The Zephyr project aims to introduce an innovative technology built on pre-cultivation of forest regeneration materials in a zero-impact and cost-friendly production unit. The project will integrate several technologies into a functional and transportable system for large scale production of pre-cultivated forest regeneration materials adapted to transplanting and further growth at forest nurseries.

    A transportable and closed incubator independent from the outdoor climate provides a better control on the seedlings production. The plants can be produced directly at the place where they are needed avoiding further transportation to the reforestation/afforestation zone. The closed-climate allows seedlings pre-cultivation in places where it would not be possible otherwise (e.g. near deserts). Additionally, it extends the production time throughout the whole year even during the winter. Moreover, it will allow a certified and standardized production of reforestation materials, with a noticeable increasing of the efficiency of the reforestation operations.

    Specially developed LED growth lamps and wireless sensors will be used to reduce energy consumption and monitor the cultivation process. The main part of the energy will be provided by solar PV-panels, depending from the geographic and climatic area the power system should be able to provide at least one day of autonomy (in central Europe). The energy savings will result in a reduction of greenhouse gas emissions; moreover, since the LED lamps do not produce additional warming, there will be further energy saving through the reduction of air conditioning costs.

    The PV system is designed based on the load specifications of the different subsystems involved for advanced state-of-art pre-cultivation of forest seedlings. It will be further evaluated based on the changes in the load profiles as the growth protocols for different species are defined.  The main objectives are to maximize the power/energy flow delivered to the load and to investigate feasible options for an external backup power source whilst considering options to reduce the overall load of the system.

  • 32.
    Hernandez Velasco, Marco
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Sreenivaasa R, Pamidi
    Exergy Ltd.
    Climate control in the production of forest plants: using photovoltaics to power an innovative forestry incubator2015In: Solar Air-Conditioning: 6th International conference, Regensburg, Germany: Ostbayerisches Technologie-Transfer-Institut (Verlag) , 2015, p. 106-111Conference paper (Other academic)
    Abstract [en]

    Forest ecosystems are currently challenged by fluctuations in the climate and an extreme exploitation of their resources.  Forest restoration requires among other things, high amounts of healthy forest seedlings to replace the lost trees.  However, the cultivation of these seedlings often involves intensive methods in forest nurseries which consume considerable amounts of energy for lighting, acclimatization and irrigation.

    The ZEPHYR project, funded by the European Commission under the Seventh Framework Programme (FP7), is developing innovative and cost-friendly technologies for the pre-cultivation of forest plants. Devices such as LED growth lights and a new generation of wireless sensors will be integrated into a functional and transportable system for large scale production of forest seedlings. The unit will have a very low impact on the environment, will be independent of the outdoor conditions and will be powered by solar energy. The whole concept represents a breakthrough in forest nursery production for reforestation purposes. It addresses issues such as energy use, water recycling, reduction of fertilizers and avoidance of pesticides.

    One of the main features of the Zephyr incubator is the fact that the seedlings will be pre-cultivated during the first stage in an isolated environment. A transportable and closed incubator possess several advantages: it provides a better climate control for the production of seedlings and reduces the need for pesticides and fertilizers. The closed-climate allows growing seedlings in places where it would not be possible otherwise (e.g. near deserts). The plants can be produced directly at the place where they are needed avoiding further transport to the reforestation/afforestation site. Additionally, it extends the production time throughout the whole year even during the winter. Moreover, it will allow a certified and standardized production of reforestation materials, with a noticeable increase in the success of the restoration actions.

    In order to benefit from the advantages of a closed growing environment without having a negative impact on the environment, the incubator will be powered mainly by a solar photovoltaic (PV) system which will be mounted on the roof of the unit. In order to reduce the amount of air conditioning needed, the chamber has been isolated from the rest of the system. The growth protocols have been set to a certain temperature range that allows a more flexible operation of the air conditioning system without compromising the development of the seedlings. Finally, since the LED growth lamps do not produce as much additional heat compared to other lightning sources so there will be further savings.

  • 33.
    Howley, Brian
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fleischer, Marc
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Solar PV Powered Air Conditioner Analysis for an Office/Classroom in a Tropical Climate2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on using photovoltaic produced electricity to power air conditioners in a tropical climate. The study takes place in Surabaya, Indonesia at two different locations the classroom, located at the UBAYA campus and the home office, 10 km away. Indonesia has an average solar irradiation of about 4.8 kWh/m²/day (PWC Indonesia, 2013) which is for ideal conditions for these tests.

    At the home office, tests were conducted on different photovoltaic systems. A series of measuring devices recorded the performance of the 800 W PV system and the consumption of the 1.35 kW air conditioner (cooling capacity). To have an off grid system many of the components need to be oversized. The inverter has to be oversized to meet the startup load of the air conditioner, which can be 3 to 8 times the operating power (Rozenblat, 2013). High energy consumption of the air conditioner would require a large battery storage to provide one day of autonomy. The PV systems output must at least match the consumption of the air conditioner.

    A grid connect system provides a much better solution with the 800 W PV system providing 80 % of the 3.5 kWh load of the air conditioner, the other 20 % coming from the grid during periods of low irradiation. In this system the startup load is provided by the grid so the inverter does not need to be oversized. With the grid-connected system, the PV panel’s production does not need to match the consumption of the air conditioner, although a smaller PV array will mean a smaller percentage of the load will be covered by PV.

    Using the results from the home office tests and results from measurements made in the classroom. Two different PV systems (8 kW and 12 kW) were simulated to power both the current air conditioners (COP 2.78) and new air conditioners (COP 4.0). The payback period of the systems can vary greatly depending on if a feed in tariff is awarded or not. If the feed in tariff is awarded the best system is the 12 kW system, with a payback period of 4.3 years and a levelized cost of energy at -3,334 IDR/kWh. If the feed in tariff is not granted then the 8 kW system is the best choice with a lower payback period and lower levelized cost of energy than the 12 kW system under the same conditions.

  • 34. Joly, M.
    et al.
    Ruiz, G.
    Mauthner, F.
    Bourdoukan, P.
    Emery, M.
    Andersen, Martin
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A methodology to integrate solar thermal energy in district heating networks confronted with a Swedish real case study2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 122, p. 865-870Article in journal (Refereed)
    Abstract [en]

    Among other solutions, the integration of solar energy in district heating networks can contribute significantly to the increase of the renewable energy fraction in an urban area. This article describes the methodology developed in the framework of IEA Task 52 to help stakeholders during early phases of new or refurbishments projects. This methodology integrates a tool which is capable to assess the main solar indicators of the project with only two inputs: the solar installation area and the building heated area. The tool outputs are compared to the measured values of a Swedish case study.

  • 35.
    Joudi, Ali
    Dalarna University, School of Technology and Business Studies, Energy Technology. Linköpings universitet.
    Radiation properties of coil-coated steel in building envelope surfaces and the influence on building thermal performance2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Recent studies have shown that the optical properties of building exterior surfaces are important in terms of energy use and thermal comfort. While the majority of the studies are related to exterior surfaces, the radiation properties of interior surfaces are less thoroughly investigated. Development in the coil-coating industries has now made it possible to allocate different optical properties for both exterior and interior surfaces of steel-clad buildings. The aim of this thesis is to investigate the influence of surface radiation properties with the focus on the thermal emittance of the interior surfaces, the modeling approaches and their consequences in the context of the building energy performance and indoor thermal environment.

    The study consists of both numerical and experimental investigations. The experimental investigations include parallel field measurements on three similar test cabins with different interior and exterior surface radiation properties in Borlänge, Sweden, and two ice rink arenas with normal and low emissive ceiling in Luleå, Sweden. The numerical methods include comparative simulations by the use of dynamic heat flux models, Building Energy Simulation (BES), Computational Fluid Dynamics (CFD) and a coupled model for BES and CFD. Several parametric studies and thermal performance analyses were carried out in combination with the different numerical methods.

    The parallel field measurements on the test cabins include the air, surface and radiation temperatures and energy use during passive and active (heating and cooling) measurements. Both measurement and comparative simulation results indicate an improvement in the indoor thermal environment when the interior surfaces have low emittance. In the ice rink arenas, surface and radiation temperature measurements indicate a considerable reduction in the ceiling-to-ice radiation by the use of low emittance surfaces, in agreement with a ceiling-toice radiation model using schematic dynamic heat flux calculations.

    The measurements in the test cabins indicate that the use of low emittance surfaces can increase the vertical indoor air temperature gradients depending on the time of day and outdoor conditions. This is in agreement with the transient CFD simulations having the boundary condition assigned on the exterior surfaces. The sensitivity analyses have been performed under different outdoor conditions and surface thermal radiation properties. The spatially resolved simulations indicate an increase in the air and surface temperature gradients by the use of low emittance coatings. This can allow for lower air temperature at the occupied zone during the summer.

    The combined effect of interior and exterior reflective coatings in terms of energy use has been investigated by the use of building energy simulation for different climates and internal heat loads. The results indicate possible energy savings by the smart choice of optical properties on interior and exterior surfaces of the building.

    Overall, it is concluded that the interior reflective coatings can contribute to building energy savings and improvement of the indoor thermal environment. This can be numerically investigated by the choice of appropriate models with respect to the level of detail and computational load. This thesis includes comparative simulations at different levels of detail.

  • 36.
    Joudi, Ali
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Svedung, Harald
    Building Surface Radiation Properties and Heat Flux: poster2010In: ENERGY FORUM on Solar Building Skins, Bressanone, Italien, 2010Conference paper (Other academic)
  • 37.
    Joudi, Ali
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Svedung, Harald
    Energy savings in buildings through optimized surface heat radiation properties2009In: Ökosan'09 - The International Symposium on High-Quality Thermal Retrofit of Large-Volume Buildings, Weiz, Austria, 2009Conference paper (Other academic)
  • 38.
    Lang, Markus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Performance Study of a PVT Air Collector2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

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

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

  • 39.
    Leijonhufvud, Gustaf
    et al.
    Högskolan på Gotland, Uppsala universitet.
    Henning, Annette
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Rethinking indoor climate control in historic buildings: The importance of negotiated priorities and discursive hegemony at a Swedish museum2014In: Energy Research & Social Science, ISSN 2214-6296, Vol. 4, p. 117-123Article in journal (Refereed)
    Abstract [en]

    Much effort has in recent years been directed to support sustainable indoor climate control strategies in historic buildings. In this paper we show the necessity to complement the dominant technical approaches with research that take a wider interest in specific contexts, social practicies, and negotiated decisions. The objective of the paper is to illustrate how the interactions between perceptions and experiences of different professional groups are pivotal for the management of the indoor climate. An ethnographic study of decision making in an historic house museum was carried out in 2009 and 2012. Interviews were made with individuals who either took part in management or were affected by the indoor climate. The findings show how discussions among social actors and the way their respective priorities are negotiated are essential features of the management of the indoor climate and have a strong impact on the ability to modify it. It turns out that a hegemonic discourse about preservation as the dominant rationale for indoor climate control in tandem with "acceptable" conditions with respect to preservation have reinforced a state of stability. This explorative study opens up for a re-framing of how a more sustainable management of historic buildings can be achieved.  

  • 40.
    Lidberg, Tina
    Dalarna University, School of Technology and Business Studies, Energy Technology. Högskolan i Gävle, Energisystem.
    Influences from Building Energy Efficiency Refurbishment on a Regional District Heating System2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Improving energy performance of existing buildings is an important part in decreasing energy use and in turn reduce the greenhouse gas emissions caused by human activity and the primary energy use.

    To be able to evaluate how energy refurbishment influences the greenhouse gas emissions and the primary energy use a wider system perspective is needed that puts the building in its context. This thesis deals with energy refurbishment packages performed on multi-family buildings within district heated areas and how they influence greenhouse gas emissions and primary energy use when the district heating use is altered.

    A simulated building is used to evaluate several energy refurbishment packages. The results are used as input data for models of district heating systems to cost optimize the district heating production. The results from the cost optimization are used to evaluate the impact on greenhouse gas emissions and primary energy use.

    The results show a difference between measures that saves district heating without increasing the use of electricity and measures that increases the use of electricity while district heating is saved. For example, a building refurbishment package including only building envelope improvements saves the same amount of district heating as a package including only mechanical ventilation with heat recovery. Despite this, the emissions of greenhouse gases and the use of primary energy is to a greater extent reduced in the first package because the use of electricity remains unchanged.

    Comparing energy refurbishment packages performed on the same building, but within different district heating systems, show the importance of the design of the district heating system. Depending on the fuel types used and to which extent electricity is co-produced in the district heating system, the results of implementing the energy refurbishment packages vary. The largest reduction of greenhouse gases and primary energy use occurs when a refurbishment package is performed on a building in a district heating system with high share of biofuel and no electricity production.

  • 41.
    Lidberg, Tina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Olofsson, Thomas
    Dalarna University, School of Technology and Business Studies, Construction. Umeå universitet.
    Trygg, Louise
    Linköpings Universitet.
    System impact of energy efficient building refurbishment within a district heated region2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 106, p. 45-53Article in journal (Refereed)
    Abstract [en]

    The energy efficiency of the European building stock needs to be increased in order to fulfill the climate goals of the European Union. To be able to evaluate the impact of energy efficient refurbishment in matters of greenhouse gas emissions, it is necessary to apply a system perspective where not only the building but also the surrounding energy system is taken into consideration.

    This study examines the impact that energy efficient refurbishment of multi-family buildings has on the district heating and the electricity production. It also investigates the impact on electricity utilization and emissions of greenhouse gases.

    The results from the simulation of four energy efficiency building refurbishment packages were used to evaluate the impact on the district heating system. The packages were chosen to show the difference between refurbishment actions that increase the use of electricity when lowering the heat demand, and actions that lower the heat demand without increasing the electricity use. The energy system cost optimization modeling tool MODEST (Model for Optimization of Dynamic Energy Systems with Time-Dependent Components and Boundary Conditions) was used.

    When comparing two refurbishment packages with the same annual district heating use, this study shows that a package including changes in the building envelope decreases the greenhouse gas emissions more than a package including ventilation measures.

  • 42.
    Linde, Daniel
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Evaluation of a Flat-Plate Photovoltaic Thermal (PVT) Collector prototype2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This Master thesis, in collaboration with Morgonsol Väst AB, was completed as a part of the Solar Energy engineering program at Dalarna University. It analyses the electrical and thermal performance of a prototype PVT collector developed by Morgonsol Väst AB. By following the standards EN 12975 and EN ISO 9806 as guides, the thermal tests of the collector were completed at the facility in Borlänge. The electrical performance of the PVT collector was evaluated by comparing it to a reference PV panel fitted next to it. The result from the tests shows an improved electrical performance of the PVT collector caused by the cooling and a thermal performance described by the linear efficiency curve ηth=0.53-21.6(Tm-Ta/G). The experimental work in this thesis is an initial study of the prototype PVT collector that will supply Morgonsol Väst with important data for future development and research of the product.

  • 43. Luo, H.
    et al.
    Liang, X.
    Lu, J.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Applicability analysis of insulation in different climate zones of China2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 1835-1841Article in journal (Refereed)
    Abstract [en]

    In this paper we evaluated the applicability of the widely-used passive design strategy i.e., insulation, in three typical climate zones of China. Software IES VE was used for modelling and simulation of performance of insulation in a residential house. The practical behavior patterns of Chinese family from survey were utilized for analyzing the thermal characteristics of the house. Four parameters of the results were selected for analyzing the performance of insulation in three cities of China. The conditions varying in time periods and locations were compared on the basis of the simulation.

  • 44.
    Mattsson, Anders
    et al.
    Dalarna University, School of Technology and Business Studies, Forest and Wood Technology.
    Hernandez Velasco, Marco
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Rusu, Cristina
    Acreo Swedish ICT AB.
    Pietrzak, Malgorzata
    Azorina S.A.
    Ferreira, Raquel
    Azorina S.A.
    Radoglou, Kalliopi
    Democritus University of Thrace.
    Smirnakou, Sonia
    Democritus University of Thrace.
    Bantis, Filippos
    Democritus University of Thrace.
    Fulgaro, Nicoletta
    Università degli Studi dell'Insubria.
    Kotilainen, Titta
    Valoya OY.
    ZEPHYR Project – Deliverable D7.6: Articles and peer-reviewed papers2015Report (Other (popular science, discussion, etc.))
  • 45.
    Melo, Manuel
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Economic Evaluation of a Solar Charged Thermal Energy Store for Space Heating2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A thermal energy store corrects the misalignment of heating demand in the winter relative to solar thermal energy gathered in the summer. This thesis reviews the viability of a solar charged hot water tank thermal energy store for a school at latitude 56.25N, longitude -120.85W

  • 46. Menegon, D.
    et al.
    Persson, Tomas
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Haberl, R.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Haller, M.
    Direct characterisation of the annual performance of solar thermal and heat pump systems using a six-day whole system test2020In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 146, p. 1337-1353Article in journal (Refereed)
  • 47.
    Nielsen, Caroline
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Travel Report from the first field trip within the SIDA supported project "Mini-grids supplied by renewable energy - improving technical and social feasibility: Including visits to Ihushi Development Center, Tweyambe Secondary School and Mavuno Project in Tanzania. Conducted in April 20112011Report (Other academic)
    Abstract [en]

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

  • 48.
    Pamidi R., Sreenivaasa
    et al.
    Exergy Ltd..
    Polidori, Carlo
    Veltha IVZW.
    Mattsson, Anders
    Dalarna University, School of Technology and Business Studies, Forest and Wood Technology.
    Hernandez Velasco, Marco
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ghrissi, Meftah
    Robosoft SA.
    Carrel, Aubert
    Robosoft SA.
    Menta, Andrea
    CO.MET.ART. SAS.
    Ramiro, Manuel
    ADVANTIC Sistemas y Servicios.
    Kotilainen, Titta
    Valoya OY.
    Aikala, Lars
    Valoya OY.
    ZEPHYR Project – Deliverable D2.4: Technical specification for the Power system with solar panels2013Report (Other (popular science, discussion, etc.))
  • 49.
    Pamidi, Sreenivaasa R
    et al.
    Exergy Ltd..
    Hernandez Velasco, Marco
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Reducing the impact of forest plant production - Design of a stand-alone PV-hybrid system for powering an innovative forestry incubator2014In: 29th European Photovoltaic Solar Energy Conference and Exhibition Proceedings, 2014, p. 3811-3814Conference paper (Other academic)
    Abstract [en]

    Nowadays, the high demand of forestry products imposes a high pressure on the ecosystems and can derive in biodiversity lost and other ecological problems. Planted forests can contribute to more sustainable practices and help addressing other problems of global concern such as climate change, erosion and desertification. Large scale production of seedling is required to offset the high harvesting rates; however these intensive methods often have a negative impact on the environment. Funded by the European Commission under the Seventh Framework Programme (FP7), the ZEPHYR project consortium is developing innovative and cost-friendly technologies for the pre-cultivation of forestry species. These will be integrated into a functional and transportable system for pre-cultivation of seedlings, with zeroimpact on the environment and not affected by outdoor conditions. To achieve this, the incubator will be powered mainly by solar energy. This work aims to present the efforts made to design and optimize the solar photovoltaic (PV) system which will be mounted on the roof of the unit. Especially developed devices such as LED growth lamps and wireless sensors will be used to reduce energy consumption and monitor the cultivation process. A load profile study was conducted and the growth protocols were adapted to perform most of the tasks during daytime to use the energy from the PV panels directly. A battery bank will be designed to provide at least one day of autonomy in central European latitudes. Moreover, the power system will also be capable of connecting to the electricity grid or use a diesel generator as a backup.

  • 50. Pan, S.
    et al.
    Wang, H.
    Pei, F.
    Yang, L.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    An investigation on energy consumption of air conditioning system in Beijing subway stations2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 2568-2573Article in journal (Refereed)
    Abstract [en]

    This paper initially depicted on the energy consumption of air conditioning systems in Beijing subway stations. An investigation was conducted among ten underground subway stations to the examination of practical operation conditions of their cooling units. The overall field testing included information such as air conditioning system formation, equipment types, system operation parameters, energy consumption and system operation efficiency. The results showed that the COP value of refrigerators in the tested subway stations were generally high at about 4.4 in average. Nevertheless, the mean EER and SCOP values were nearly 27% and 48% lower than the average COP value due to the large amount of energy consumption in water pumps, cooling towers and fans. There was a big difference among each station in terms of the instantaneous power consumption of air conditioning systems. The most energy consuming station was nearly seven times higher than the least one. It was observed that there was a lack of maintenance and system operation strategy for these underground air condition systems. A promising potential for energy saving was found out within the air conditioning systems in Beijing subway stations.

12 1 - 50 of 64
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf