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  • 101.
    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.

  • 102.
    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.   

  • 103.
    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.
    Light quality and intensity of light-emitting diodes during pre-cultivation of Picea abies (L.) Karst. and Pinus sylvestris L. seedlings - impact on growth performance, seedling quality and energy consumption2019In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 34, no 3, p. 159-177Article in journal (Refereed)
    Abstract [en]

    Three different LED lamps with continuous spectra were compared against commonly used fluorescent lights. The lamps were characterized by light output, energy consumption and spectral quality for plant growth. The biological effects of light quality were compared by pre-cultivating seedlings of Picea abies (L.) Karst. and Pinus sylvestris L. under each spectrum for 35 days in a growth chamber with controlled temperature, humidity and photoperiod. The seedlings were then transplanted and cultivated for one vegetation period at the nursery, then planted outdoors on a forest field trial and followed for three years. The seedlings showed similar growth performance for all spectra tested. LED lamps have several advantages to fluorescent light such as energy consumption, longer life span and adjustable light intensity. Regarding light intensity the effects on growth performance were studied for both species using the most promising LED spectra. The photosynthetically active radiation (PAR) was maintained at 50, 100, 200 and 400 mu mol m(-2) s(-1). Unlike energy consumption, seedling development did not display a linear relationship to light intensity. Instead, the results show an optimum light level between 100 and 200 mu mol m(-2) s(-1) for the shade tolerant Picea abies seedlings and a level of around 200 mu mol m(-2) s(-1) for the more shade intolerant Pinus sylvestris seedlings.

  • 104.
    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.
    Long night treatment for induction of cold hardiness using artificial lights: effects of photoperiod on seedling storabilityand energy consumption2014In: 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. 379-379Conference paper (Other academic)
    Abstract [en]

    Human-assisted forest regeneration in Nordic climates is considerably limited by the harsh outdoor conditions. There is onlya small open window of time during the summer when the weather is favorable for transplantation and establishment ofpre-cultivated seedlings in open land. Greenhouses and modern growth chambers help to cope with this limitation by allowingyear-round seedling cultivation. Nonetheless, production levels are constrained to the cold storage capacity during the nontransplantingseason. This storage is in turn dependent on the ability of the conifer to adapt to freezing temperatures and withstand theoverall stress associated with cold hardening. Long night treatments can induce dormancy with cessation of growth and terminalbuds initiation, leading to a better cold resistance. When growing forest regeneration materials under artifi cial lights, the lengthsof the long night treatment and the photoperiod will have a signifi cant impact not only on the biological response of the seedlingsbut also on the energy consumption, and thus on the CO2 emissions. The aim of this work was to explore different long nighttreatment regimes for induction of cold hardiness in Picea abies and Pinus sylvestris seedlings using artifi cial lights. This wasdone with the purpose of studying the relationship between the energy consumption and the biological responses.

  • 105.
    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.
    Nuevas tecnologías para el pre-cultivo de plantas forestales - diseño de una incubadora sustentable para minimizar el impacto ambiental2014In: VI Congreso Forestal Latinoamericano: Latinoamérica unida en armonia por la sustentabilidad de los recursos forestales, 2014Conference paper (Other academic)
    Abstract [es]

    Los bosques plantados pueden contribuir a combatir problemas globales como el cambio climático, la erosión del suelo y la presión en los ecosistemas debido a la alta demanda de productos forestales. Para que este beneficio sea sustentable, la producción del material para la regeneración forestal tiene que ser mayor a la velocidad en que se tala. Las técnicas intensivas en los viveros forestales puede traer efectos adversos al ambiente como el uso de fertilizantes, pesticidas y alto consumo energético de los invernaderos. 

    Financiado por Séptimo Programa de Investigación y Desarrollo de la Unión Europea, el proyecto ZEPHYR está enfocado a desarrollar nuevas tecnologías para el pre-cultivo de plantas forestales de una manera sustentable y económicamente viable. Estas innovaciones estarán integradas en una incubadora transportable y totalmente funcional para la producción a gran escala. El cuarto de crecimiento será independiente de las condiciones exteriores y tendrá un mínimo impacto ambiental. Para lograr esto se usaran aparatos de alta eficiencia y bajo consumo energético como lámparas LED y todo funcionará con un sistema solar fotovoltaico.

  • 106.
    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.
    Outdoor performance of forest seedlings pre-cultivated under artificial lights: effects of the light spectra used for pre-cultivation on the future establishment and development2015In: Rainforest challenges: Book of abstracts / [ed] Vladan Ivetić and Tatjana Ćirković‐Mitrović , 2015, p. 20-20Conference paper (Other academic)
    Abstract [en]

    Forest nurseries are essential for producing good quality seedlings, thus being a key element in the reforestation process. With increasing climate change awareness, nursery managers are looking for new tools that can help reduce the effects of their operations on the environment. The ZEPHYR project, funded by the European Commission under the Seventh Framework Programme (FP7), has the objective of finding new alternatives for nurseries by developing innovative zero-impact technologies for forest plant production. Due to their direct relationship to the energy consumption of the nurseries, one of the main elements addressed are the grow lights used for the pre-cultivation. New LED luminaires with a light spectrum tailored to the seedlings’ needs are being studied and compared against the traditional fluorescent lamps. Seedlings of Picea abies and Pinus sylvestris were grown under five different light spectra (one fluorescent and 4 LED) during 5 weeks with a photoperiod of 16 hours at 100 μmol∙m-2∙s-1 and 60% humidity. In order to evaluate if these seedlings were able cope with real field stress conditions, a forest field trial was also designed. The terrain chosen was a typical planting site in mid-Sweden after clear-cutting. Two vegetation periods after the outplanting, the seedlings that were pre-cultivated under the LED lamps have performed at least as well as those that were grown under fluorescent lights. These results show that there is a good  potential for lightning substitution in forestry nurseries.

  • 107.
    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.
    Swedish experiences and visions on the production of containerized seedlings2016In: / [ed] Palle Madsen, 2016Conference paper (Other academic)
  • 108.
    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.

  • 109.
    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.

  • 110.
    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.

  • 111.
    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.

  • 112. Hu, J
    et al.
    Chen, W
    Yin, Y
    Li, Y
    Yang, D
    Wang, H
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Electrical-thermal-mechanical properties of multifunctional OPV-ETFE foils for transparent membrane buildings2018In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 66, p. 394-402Article in journal (Refereed)
    Abstract [en]

    ETFE (ethylene tetrafluoroethylene) foils integrated organic photovoltaic cells (OPV) have attracted considerable attention in recent years due to the achievement of sustainability. As building materials, multifunctional OPV-ETFE foils could produce electricity, store thermal energy and possess structural capability. In this case, electrical, thermal and mechanical properties coexist and influence each other due to photovoltaic/thermal effects. Understanding the fundamental mechanism is significant to analyze and design corresponding structures. This paper concerns coupled properties of OPV-ETFE specimens with controlled experiments. One-parameter and two-parameter analysis of two typical specimens are performed to investigate essential properties. Experimental observations show that within normal working conditions, electrical properties are relatively independent but that thermal-mechanical properties are related to each other. Yield stress, yield strain and elastic modulus are calculated from stress-strain curves; these mechanical properties are comparable with those of original ETFE foils at the same temperature. It is concluded from temperature-stress curves that yield point has a critical effect on temperature-stress correlation and that mechanical properties of double OPV specimens are better than those of single OPV specimens. Generally, these mechanical properties could provide basic insights into evaluation of energetic performance and structural behavior of transparent membrane buildings.

  • 113. Huang, P
    et al.
    Fan, C
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Wang, J
    A hierarchical coordinated demand response control for buildings with improved performances at building group2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 242, p. 684-694Article in journal (Refereed)
    Abstract [en]

    Demand response control is one of the common means used for building peak demand limiting. Most of the existing demand response controls focused on single building’s performance optimization, and thus may cause new undesirable peak demands at building group, imposing stress on the grid power balance and limiting the economic savings. A few latest studies have demonstrated the potential benefits of demand response coordination, but the proposed methods cannot be applied in large scales. The main reason is that, for demand response coordination of multiple buildings, associated computational load and coordination complexity, increasing exponentially with building number, are challenges to be solved. This study, therefore, proposes a hierarchical demand response control to optimize operations of a large scale of buildings for group-level peak demand reduction. The hierarchical control first considers the building group as a ‘virtual’ building and searches the optimal performance that can be achieved at building group using genetic algorithm. To realize such optimal performance, it then coordinates each single building’s operation using non-linear programming. For validations, the proposed method has been applied on a case building group, and the study results show that the hierarchical control can overcome the challenges of excessive computational load and complexity. Moreover, in comparison with conventional independent control, it can achieve better performances in aspects of peak demand reduction and economic savings. This study provides a coordinated control for application in large scales, which can improve the effectiveness and efficiency in relieving the grid stress, and reduce the end-users’ electricity bills.

  • 114.
    Huang, Pei
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. City University of Hong Kong.
    Xu, T.
    Sun, Y.
    A genetic algorithm based dynamic pricing for improving bi-directional interactions with reduced power imbalance2019In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 199, p. 275-286Article in journal (Refereed)
  • 115.
    Johansson Macedo, Liv May
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Modification of a Moving Bed Biofilm Reactor(MBBR) due to radically changed process conditions: A case study of Kvarnsveden paper mill2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    TOC reduction.

  • 116.
    Johari, Fatemeh
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Predictive Control Strategies for aHeat Pump System with PV and Electrical Storage with Various Boundary Conditions2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

  • 117. 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.

  • 118.
    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.

  • 119.
    Joudi, Ali
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. SSAB Europe, Borlänge.
    Cehlin, Mathias
    Högskolan i Gävle.
    Svedung, Harald
    Dalarna University, School of Technology and Business Studies, Energy Technology. SSAB Europe, Borlänge.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Moshfegh, Bahram
    Högskolan i Gävle.
    Numerical and experimental investigation of the influence of infrared reflective interior surfaces on building temperature distributions2017In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 26, no 3, p. 355-367Article in journal (Refereed)
    Abstract [en]

    Radiative properties of interior surfaces can affect not only the building heat flux but also the indoor environment, the latter of which has not been thoroughly investigated. The aim of this study is to analyse the effect of surface emissivity on indoor air and surface temperature distributions in a test cabin with reflective interior surfaces. This was done by comparing experimental and simulation data of the test cabin with that of a normal cabin. This study employs transient computational fluid dynamics (CFD) using re-normalisation group (RNG) k–" model, surface-to-surface radiation model and an enhanced wall function. Boundary conditions were assigned to exterior surfaces under variable outdoor conditions. The numerical and the measurement results indicate that using interior reflective surfaces will affect the indoor air temperature distribution by increasing the vertical temperature gradient depending on the time of the day. CFD simulations with high spatial resolution results show increased interior surface temperature gradients consistent with the increased vertical air temperature gradient. The influence of reflective surfaces is potentially greater with higher indoor surface temperature asymmetry. The vertical indoor air temperature gradient and surface temperatures are important parameters for indoor thermal comfort.

  • 120.
    Khadra, Alaa
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Economic Performance Assessment of Three Renovated Multi-Family Houses with Different HVAC Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

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

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

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

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

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

    1 W/m

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

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

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

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

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

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

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

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

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

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

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

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

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

    the available data and the assessed parameters.

  • 121.
    Korde, Anukool
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Assessment of a Solar PV Re-Powering Project in Sweden Using Measured and Simulated Data2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

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

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

  • 122.
    Kovacs, Peter
    et al.
    RISE Research Institutes of Sweden.
    Dahlenbäck, Jan-Olof
    Chalmers University of Technology .
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Tvärfackligt projekt ger branschen ökad kunskap om solcellstak vid takrenovering2019In: Husbyggaren, ISSN 0018-7968, Vol. 3, p. 8-11Article in journal (Other (popular science, discussion, etc.))
    The full text will be freely available from 2020-06-24 14:57
  • 123.
    Kuhn, Tillmann
    et al.
    Fraunhofer ISE.
    Fath, Karoline
    Fraunhofer ISE.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Nouvel, Romain
    ZAFH.
    Fedrizzi, Roberto
    EURAC.
    D2.3 RES availability survey and boundary conditions for simulations2014Report (Other academic)
  • 124.
    Kumar, Pankaj
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Performance Evaluation of High Temperature Steam Generating Solar Collectors2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

  • 125.
    Kurdia, Ali
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Consequences of Nordic Conditions on the Performance of Large-Scale Building Applied PV Installations2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

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

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

  • 126. Kántor, Noémi
    et al.
    Chen, Liang
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Human-biometeorological significance of shading in urban public spaces: Summertime measurements in Pécs, Hungary2018In: Landscape and Urban Planning, ISSN 0169-2046, E-ISSN 1872-6062, Vol. 170, p. 241-255Article in journal (Refereed)
    Abstract [en]

    Shading is shown to be one of the most effective strategies to mitigate urban heat stress, especially on a small scale. This paper presents an empirical study investigating the effectiveness of different means of shading—by sun sails and trees—to improve the local thermal environment during the summer. Three different urban settings were investigated through detailed human-biometeorological measurements in the Hungarian city of Pécs. Our study employed the accurate six-directional radiation measurement technique, and calculated Physiological Equivalent Temperature (PET) from the obtained data to assess outdoor thermal conditions. Our results indicate that in open urban squares trees can mitigate heat stress more effectively than low-hanging sun sails, installed right above the head of pedestrians. In the period of 9:00–16:00, the average PET reduction by trees and low sun sails was 9.0 °C and 5.8 °C, respectively. Sun sails, installed at higher elevation to shade an entire street canyon, and mature trees with dense canopy had more pronounced heat stress reduction ability, and were able to reduce the local PET by over 10 °C. Our study demonstrates the importance of detailed small-scale field measurements, the outcomes of which can be incorporated into climate-responsive urban design strategies with ease.

  • 127.
    Kántor, Noémi
    et al.
    University of Szeged, Szeged, Hungary.
    Gulyás, Ágnes
    University of Szeged, Szeged, Hungary.
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Mikroklíma modellezés a városi közterülettervezés szolgálatában [Microclimate modeling at the service of urban public space design]2017In: Meteorológiai Tudományos Napok. 2017. November 23-24. Mikro- és mezoskálájú légköri folyamatok modellezése. Az előadások összefoglalói. / [ed] István Geresdi, Ferenc Ács, Balázs Szintai and Tamás Weidinger, Budapest, Hungary, 2017Conference paper (Refereed)
    Abstract [hu]

    Európa lakosságának mintegy kétharmada már most is városi környezetben él, s a városi populáció aránya 2050-re várhatóan 80% fölé fog emelkedni. Mivel a városokra jellemző többlet hőmennyiség, valamint a városok csökkent átszellőzési képessége tovább súlyosbítják a klímaváltozással járó hőmérsékletemelkedést, a – várhatóan egyre gyakoribbá, hosszabbá és intenzívebbé váló – hőhullámok hatásai különösen a városlakók egészségét veszélyeztetik. Ennél fogva a nyári hőség káros következményeinek megelőzése a várostervezés egyik kiemelt feladata. A természet- alapú megoldások (Nature-Based Solutions, NBS) egy újonnan bevezetett fogalom a környezetkutatás és környezet- gazdálkodás területén, mely a klímaváltozással járó kihívások kezelésére természetes tényezőket, illetve folyamatokat ajánl. Ebben a tanulmányban – a négyéves Nature4Cities projekt keretein belül – a fás vegetáció hőstressz-mérséklő kapacitását vettük górcső alá egyrészt terepi mérések, másrészt numerikus szimulációk segítségével.A léghőmérséklet korántsem az egyedüli paraméter az emberi szervezet hőháztartása szempontjából. Sőt, számos humán-biometeorológiai tanulmány rámutatott már a sugárzási viszonyok vezető szerepére a nyári hőterhelés kialakulásában. Éppen ezért tanulmányunkban a biometeorológiai vizsgálatok kulcsparaméterére, az átlagos sugárzási hőmérsékletre (Mean Radiant Temperature, Tmrt), illetve ennek a fás vegetáció általi mérséklésére helyeztük a hangsúlyt.Tanulmányunk első részében három, a város-biometeorológia területén gyakran alkalmazott mikroklíma modellt (RayMan, ENVI-met, SOLWEIG) hasonlítottunk össze a tekintetben, hogy mennyire képesek a Tmrt valós értékeinek szimulálására. A modellellenőrzéshez egy derült égboltviszonyokkal jellemezhető késő nyári nap humán- biometeorológiai méréssorozatának adatait használtuk fel. A 26-órás mérés során a szegedi Bartók Béla tér öt különböző pontján rögzítettük a rövid-, és hosszúhullámú sugárzási mérleg komponenseket, hogy azokból a leghitelesebb biometeorológiai eljárás szerint Tmrt-t számoljunk. A három mikroklíma-modell közül a SOLWEIG szolgáltatta a leghitelesebb eredményeket, így később ezt a modellt használtuk arra, hogy összehasonlítsuk különféle fásítási szcenáriók hőstressz-mérséklő hatását – ugyancsak a szegedi Bartók Béla téri mintaterületen. A szimulációk alapján a lombkorona transzmisszivitásának (sugárzásáteresztő képességének) változtatása kisebb, míg azonos korona-térfogat mellett a lombkorona méretének (több kis fa vs. kevesebb nagyobb fa), valamint a fák területen belüli elrendezésének változtatása (egyenletesen vs. csak az épülethomlokzatok mentén ültetett fák) jelentősebb Tmrt módosítást eredményezett.

  • 128. Kántor, Noémi
    et al.
    Gulyás, Ágnes
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Relevance of urban trees and sun shades regarding summertime heat stress reduction – a field surveys from Pécs, Hungary2017Conference paper (Refereed)
    Abstract [en]

    Mitigating the impact of summertime heat stress became the central issue of climate-conscious urban planning as a result of rising temperatures and continued urbanization trends. Furthermore, recent EU planning directives gave priority to nature-based solutions (NBS) and hence to re-naturing cities. Within the scope of the international Nature4Cities project fostering the use such solution, an inter- and cross-disciplinary research will be done assessing the performance of archetypal NBSs addressing different urban challenges – in this case, heat mitigation in urban environments.The objective of this particular study is to compare the effectiveness of natural and artificial shading solutions (urban trees and sun sails) in reducing summertime heat stress and enhancing outdoor thermal comfort of pedestrians. The Physiological Equivalent Temperature (PET), used as performance indicator in this study, was calculated from field data. The measurement campaign utilizing two human-biometeorological stations recorded pedestrian-level radiant flux densities from six perpendicular directions, air temperature, relative humidity and wind speed on three late-summer days. The daytime measurements were conducted at three different urban settings in Pécs, a medium-size Central-European city.Our research found that mature trees with dense canopy have the highest heat stress reduction potential and could reduce the local PET by up to 10°C. Even though artificial sun sails blocked effectively direct solar exposure, the low-hanging sun sails became the sources of long-wave radiation which made the thermal comfort conditions below them somewhat worse compared to trees. Our study demonstrates the importance of small-scale field measurements, the outcomes of which are directly applicable in the climate-adaptive design of urban spaces.

  • 129. Kántor, Noémi
    et al.
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gulyás, Ágnes
    The impact of façade orientation and vegetation on summer heat stress – measurements and simulations from a rectangular Central-European square2017Conference paper (Refereed)
    Abstract [en]

    Around three quarter of the European population already lives in urban areas and by 2050 this proportion isexpected to rise over 80%. Since climate change is expected to bring rising temperatures and more frequent heatwaves, mitigating the impact of extreme heat events is one of the most important issues in urban planning. Nature-Based Solutions (NBS) is a recently introduced concept in environmental research and management that promotesnature as a means to address the challenges brought about climate change. Researches of human-biometeorologydemonstrated that radiation heat load, quantified as mean radiant temperature (Tmrt), is the main source ofdaytime heat stress in summer. In European cities—especially in those with dense historic urban cores—carefullyplanned and properly maintained shade trees constitute the most effective NBS for mitigating extreme thermalconditions, while also offering several co-benefits.This study was conducted with the following two aims: (a) to assess the impact of woody vegetation anddifferent façade orientation on the radiation heat load in a complex urban setting; and (b) to evaluate the performanceof SOLWEIG, a radiation model, in reproducing the measured short- and long-wave radiation flux densities.The observation was conducted over a 26-hour long period at the rectangular Bartók Square in Szeged (Hungary)on a clear and warm late-summer day. The investigation utilized two tailor-made human-biometeorologicalstations equipped with rotatable net radiometers. The model–measurement comparison is based on data collectedfrom five locations within the square: from the center and from four sites next to the bordering façades.The measurements confirmed that on clear summer days Tmrt can reach extreme level at exposed locations(65–75C). However, shade trees are able to reduce daytime Tmrt to 30–35C. Shading SE-, S- and SW-facingfaçades and adjacent sidewalks is extremely important for the reduction of pedestrian heat stress and thus, therisk of heat stroke. When a measurement point adjacent to a facade became exposed to direct solar radiation,the radiation load increased significantly due to the additional lateral components—the reflected short-wave andthe emitted long-wave fluxes—emanating from the wall. In this respect, SOLWEIG was unable to reproducethe prolonged heat emitting effect of walls following solar exposure. Additionally, the measurement–modelcomparison revealed minor inconsistencies that originated from the model’s treatment of tree crowns: representingthem as perfectly shaped and homogeneous bodies. Due to this simplification, the observed brief penetrations ofdirect sunbeams through the canopy at most locations were not reproduced.

  • 130. Kántor, Noémi
    et al.
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gulyás, Ágnes
    Unger, János
    The impact of façade orientation and woody vegetation on summertime heat stress patterns in a Central-European square: comparison of radiation measurements and simulations2018In: Advances in Meteorology, ISSN 1687-9309, E-ISSN 1687-9317, article id 2650642Article in journal (Refereed)
    Abstract [en]

    Increasing summertime air temperature deteriorates human health especially in cities where the warming tendency is exacerbated by urban heat island. Human-biometeorological studies shed light on the primary role of radiation conditions in the development of summertime heat stress. However, only a limited number of field investigations have been conducted up to now. Based on a 26-hour long complex radiation measurement this study presents the evolved differences within a medium-sized rectangular square in Szeged, Hungary. Besides assessing the impact of woody vegetation and façade orientation on the radiation heat load, different modeling software (ENVI-met, SOLWEIG, RayMan) are evaluated in reproducing mean radiant temperature (Tmrt).Although daytime Tmrt can reach extreme level at exposed locations (65–75°C) mature shade trees can reduce it to 30–35°C. Nevertheless, shading from buildings adjacent to sidewalks plays also an important role in mitigating pedestrian heat stress. Sidewalks facing to SE, S and SW do not benefit from the shading effect of buildings therefore shading them by trees or artificial shading devices is of high importance. The measurement–model comparison revealed smaller or larger discrepancies that raise awareness on the careful adaptation of any modeling software and on the relevance of fine-resolution field measurements.

  • 131.
    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.

  • 132.
    Lehnberg, Isak
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Uppföljning av fastighet med värmelager2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

  • 133. Lei, S.
    et al.
    Shi, Y.
    Yan, Y.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Numerical study on inertial effects on liquid-vapor flow using lattice Boltzmann method2019In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 160, p. 428-435Article in journal (Refereed)
    Abstract [en]

    Liquid-vapor flow in porous media is studied in this article. To fulfill this goal, a double-distribution-function lattice Boltzmann (LB) model is proposed based on the separate-phase governing equations at the representative elementary volume (REV) scale. Importantly, besides the Darcy force and capillary force, which were commonly included in previous studies, the LB model in this article also considers the inertial force characterized by the Forchheimer term. This feature enables the model to offer an effective description of liquid-vapor flow in porous media at low, intermediate and even high flow rates. We validated the LB model by simulating a single-phase flow in porous media driven by a pressure difference and found its results are in good agreement with the available analytical solutions. We then applied the model to study water-vapor flow in a semi-infinite porous region bounded by an impermeable and heated wall. The numerical simulation reveals the flow and mass transfer characteristics under the compounding effects of inertial, Darcy and capillary forces. Through a comparison with the results given by the generalized Darcy's law, our numerical results directly evidence that the inertial force is a dominating factor when a fluid passes through porous media at an intermediate or high flow rate.

  • 134.
    Leidi, Johan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The exchange-value of solar thermal energy2007In: ISES Solar World Congress 2007, ISES 2007, 2007, Vol. 4, p. 2961-2965Conference paper (Refereed)
    Abstract [en]

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

  • 135.
    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.  

  • 136.
    Leppin, Lorenz
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Development of Operational Strategies for a Heating Pump System with Photovoltaic, Electrical and Thermal Storage2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

  • 138. Li, G
    et al.
    Tang, L
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Hao, J
    Xiao, M
    Dong, J
    Numerical and experimental investigations on improving the efficiency of Clean-In-Place procedures in closed processing systems: A review2017Conference paper (Refereed)
    Abstract [en]

    This paper reviews the recent numerical and experimental investigations on improving the efficiency of Clean-In-Place procedures thus saving operation energy. The paper covers the fouling of equipment surfaces, the concept of CIP and its operation practices, the physical factors controlling the efficiency of CIP procedures with a special attention being paid to the hydrodynamic force of the cleaning fluids. The studies show that CIP efficiency dependents on many factors, such as the type of soil to be removed, the cleaning time, the temperature of cleaning agent, and the favourable hydrodynamic force of the moving liquid. Among the hydrodynamic factors, the wall shear stress and its fluctuation rate reported to be the dominating factor for cleaning straight circular pipes. Whilst for cleaning of more complex geometries and areas difficult to clean, the controlling factor may also include the flow pattern, flow exchange, flow turbulence, and the property of the recirculation zone.

  • 139. Li, Guozhen
    et al.
    Tang, Llewellyn
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dong, Jie
    A review of factors affecting the efficiency of clean-in-place procedures in closed processing systems2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 178, p. 57-71Article in journal (Refereed)
    Abstract [en]

    This paper reviews the current state of researches on improvement of Clean-In-Place (CIP) procedures in closed processing system thus saving energy, with a special attention paid to the hydrodynamic effects of cleaning fluid and the numerical and experimental approaches to investigate the identified controlling factors. The paper discussed the fouling problems of processing plants and the importance of sufficient CIP procedures, the forces contributing to cleaning with a special focus on the hydrodynamic effects. In general, it is possible to enhance hydrodynamic removal forces by local introduction of, among others, high wall shear stress and fluctuation rate of wall shear stress without consuming more energy. A theoretical model of particle removal in flow was also reviewed which supports the factors identified. The paper therefore further reviewed and compared the current state of modelling and experimental techniques on CIP improvement. To simulation the CIP process, it is necessary to consider 3D time-resolved Large Eddy Simulation with a Hybrid RANS-LES WMLES as Sub-Grid-Scale model because it captures both the mean and fluctuation rate of flow variables, while affordable for industrial flows. The wall shear stress measurement techniques and cleanablity test methods were also discussed and suggested.

  • 140. Li, Guozhen
    et al.
    Tang, Llewellyn
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Xiao, Manxuan
    Dong, Jie
    Effect of solar radiation and natural ventilation on temperature distribution in a greenhouse: a numerical study2017Conference paper (Refereed)
  • 141.
    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.

  • 142.
    Lidberg, Tina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Olofsson, Thomas
    Dalarna University, School of Technology and Business Studies, Energy Technology. Umeå universitet.
    Trygg, L.
    Comparing different building energy efficiency refurbishment packages performed within different district heating systems2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, p. 1719-1724Article in journal (Refereed)
    Abstract [en]

    This study analyses the differences in primary energy (PE) use of a multi-family building refurbished with different refurbishment packages situated in different district heating systems (DHS). Four models of typical DHS are defined to represent the Swedish DH sector. The refurbishment packages are chosen to represent typical, yet innovative ways to improve the energy efficiency of a representative multi-family building in Sweden. The study was made from a broad system perspective, including valuation of changes in electricity use on the margin. The results show a significant difference in PE savings for the different refurbishment packages, depending on both the package itself as well as the type of DHS. Also, the package giving the lowest specific energy use per m2 was not the one which saved the most PE. © 2017 The Authors.

  • 143.
    Lidberg, Tina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Olofsson, Thomas
    Dalarna University, School of Technology and Business Studies, Construction. Umeå universitet.
    Ödlund, L
    Environmental impact of energy refurbishment of buildings within different district heating systems2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, no SI, p. 231-238Article in journal (Refereed)
    Abstract [en]

    The refurbishment of existing buildings is often considered a way to reduce energy use and CO2 emissions in the building stock. This study analyses the primary energy and CO2 impact of refurbishing a multi-family house with different refurbishment packages, given various district heating systems. Four models of typical district heating systems were defined to represent the Swedish district heating sector. The refurbishment packages were chosen to represent typical, yet innovative ways to improve the energy efficiency and indoor climate of a multi-family house. The study was made from a system perspective, including the valuation of changes in electricity use on the margin. The results show a significant difference in primary energy use for the different refurbishment packages, depending on both the package itself as well as the type of district heating system. While the packages with heat pumps had the lowest final energy use per m2 of floor area, air heat recovery proved to reduce primary energy use and emissions of CO2-equivalents more, independent of the type of district heating system, as it leads to a smaller increase in electricity use.

  • 144.
    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.

  • 145.
    Lidberg, Tina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ramírez Villegas, Ricardo
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Olofsson, Thomas
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Eriksson, Ola
    University of Gävle.
    AN APPROACH TO ILLUSTRATE STRATEGIES FOR IMPROVED ENERGY EFFICIENCY AT THE MUNICIPAL LEVEL2014In: Proceedings from the 14th International Symposium on District Heating and Cooling: Proceedings from the14th InternationalSymposium on District Heating and Cooling September, 6-10, 2014 Stockholm, SWEDEN / [ed] Anna Land, Swedish District Heating Association, 2014, p. 50-55Conference paper (Refereed)
  • 146.
    Lindberg, Eva
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fiedler, Frank
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Past and future of European Solar Energy School2007In: Proceedings of ISES Solar World Congress 2007: Solar energy and human settlement, vols I-V, 2007, Vol. 4, p. 3014-3018Conference paper (Refereed)
    Abstract [en]

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

  • 147.
    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.

  • 148. Liu, G
    et al.
    Xiao, M
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Chen, X
    Liu, L
    Pan, S
    Wu, J
    Tang, L
    Clements-Croome, D
    A review of air filtration technologies for sustainable and healthy building ventilation2017In: Sustainable cities and society, ISSN 2210-6707, Vol. 32, p. 375-396Article in journal (Refereed)
    Abstract [en]

    Urbanization increased population density in cities and consequently leads to severe indoor air pollution. As a result of these trends, the issue of sustainable and healthy indoor environment has received increasing attention. Various air filtration techniques have been adopted to optimize indoor air quality. Air filtration technique can remove air pollutants and effectively alleviate the deterioration of indoor air quality. This paper presents a comprehensive review on the synergistic effect of different air purification technologies, air filtration theory, materials and standards. It evaluated different air filtration technologies by considering factors such as air quality improvement, filtering performance, energy and economic behaviour, thermal comfort and acoustic impact. Current research development of air filtration technologies along with their advantages, limitations and challenges are discussed. This paper aims to drive the future of air filtration technology research and development in achieving sustainable and healthy building ventilation.

  • 149.
    Lorenz, Erik
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dahlin, Frida
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Fossilfri Fjärrvärme: Möjligheter till konvertering av fossila spetslastpannor hos Falu Energi och Vatten2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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

  • 150.
    Lorenz, Klaus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Solvärme i flerbostadshus2014Report (Other academic)
    Abstract [sv]

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

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