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  • 1.
    Andersen, Martin
    et al.
    Dalarna University, School of Information and Engineering, Energy Technology. Dept. of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg.
    Bales, Chris
    Dalarna University, School of Information and Engineering, Energy Technology.
    Dalenbäck, J. -O
    Economic Analysis of Heat Distribution Concepts for a Small Solar District Heating System2022In: Energies, E-ISSN 1996-1073, Vol. 15, no 13, article id 4737Article in journal (Refereed)
    Abstract [en]

    One challenge in today’s district heating systems is the relatively high distribution heat loss. Lowering distribution temperatures is one way to reduce operational costs resulting from high heat losses, while changing the distribution system from steel pipes to plastic pipes and changing the heat distribution concept can reduce investment costs. The result is that the overall life cycle cost of the district heating system is reduced, leading to the improved cost competitiveness of district heating versus individual heating options. The main aim of this study was to determine the most cost-efficient distribution system for a theoretical solar district heating system, by comparing the marginal life cycle cost of two different distribution systems. A secondary aim was to determine the influence of the employed pipe type and insulation level on the marginal life cycle cost by comparing detailed economic calculations, including differences in pipe installation costs and construction costs, among others. A small solar-assisted district heating system has been modeled in TRNSYS based on a real system, and this “hybrid” model is used as a basis for a second model where a novel distribution system is employed and the heating network operating temperature is changed. Results indicate that a novel distribution concept with lower network temperatures and central domestic hot water preparation is most efficient both from an energy and cost perspective. The total life cycle costs vary less than 2% for a given distribution concept when using different pipe types and insulation classes, indicating that the investment costs are more significant than operational costs in reducing life cycle costs. The largest difference in life cycle cost is observed by changing the distribution concept, the novel concept having approximately 24% lower marginal life cycle cost than the “hybrid” system. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

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  • 2.
    Fiedler, Frank
    et al.
    Dalarna University, School of Information and Engineering, Energy Technology.
    Matas, Joaquin C.
    Techno-Economic Analysis of Grid-Connected PV Battery Solutions for Holiday Homes in Sweden2022In: Energies, E-ISSN 1996-1073, Vol. 15, no 8Article in journal (Refereed)
    Abstract [en]

    Grid-connected PV battery systems for private homes are becoming increasingly popular in many countries, including Sweden. This study aimed to evaluate the techno-economic feasibility of such distributed, grid-connected PV battery systems for single homes at a Swedish holiday location. It was especially of interest to investigate the impact of demand charges, as they are frequently introduced by utilities in Sweden and are also common in popular winter sport regions. Grid-connected PV battery systems were sized and optimized based on their net present cost. Load patterns, incentives, demand tariff structures and electricity price variation were used to study the sensitivity of the obtained results. Grid-connected residential PV battery systems were found to be equally profitable compared to grid-connected PV systems without batteries when demand charges were applied. When the load profiles had peak loads throughout the whole year and the batteries were large enough sized to shave many peaks, grid-connected PV battery systems had slightly higher profitability than grid-connected PV systems without batteries. The total savings also depended on the actual rate of demand charge. The good profitability we found greatly depends on the current state incentives for these systems in the form of tax credits for surplus electricity and investment costs. Removing the tax credit for surplus electricity would reduce the savings generated by a grid-connected PV system without batteries significantly more than for grid-connected PV systems with batteries.

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  • 3. Gluesenkamp, Kyle R.
    et al.
    Frazzica, Andrea
    Velte, Andreas
    Metcalf, Steven
    Yang, Zhiyao
    Rouhani, Mina
    Blackman, Corey
    Dalarna University, School of Technology and Business Studies, Energy Technology. SaltX Technol AB / Malardalens Univ.
    Qu, Ming
    Laurenz, Eric
    Hallin, Ingemar
    Experimentally Measured Thermal Masses of Adsorption Heat Exchangers2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 5, article id 1150Article in journal (Refereed)
    Abstract [en]

    The thermal masses of components influence the performance of many adsorption heat pump systems. However, typically when experimental adsorption systems are reported, data on thermal mass are missing or incomplete. This work provides original measurements of the thermal masses for experimental sorption heat exchanger hardware. Much of this hardware was previously reported in the literature, but without detailed thermal mass data. The data reported in this work are the first values reported in the literature to thoroughly account for all thermal masses, including heat transfer fluid. The impact of thermal mass on system performance is also discussed, with detailed calculation left for future work. The degree to which heat transfer fluid contributes to overall effective thermal mass is also discussed, with detailed calculation left for future work. This work provides a framework for future reporting of experimental thermal masses. The utilization of this framework will enrich the data available for model validation and provide a more thorough accounting of adsorption heat pumps.

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  • 4.
    Kroner, Marie-Désirée
    et al.
    Dalarna University, School of Information and Engineering, Energy Technology. Electrical Power Engineering, Luleå University of Technology, Sweden.
    Lundgren, Urban
    Wireless Communication, RISE Research Institute of Sweden, Box 857, 50115 Borås, Sweden.
    Augusto, André
    Dalarna University, School of Information and Engineering, Energy Technology.
    Bollen, Math
    Electrical Power Engineering, Luleå University of Technology, 97187 Skellefteå, Sweden.
    Radiated Electromagnetic Emission from Photovoltaic Systems—Measurement Results: Inverters and Modules2024In: Energies, E-ISSN 1996-1073, Vol. 17, no 8, article id 1893Article in journal (Refereed)
    Abstract [en]

    Radiated electromagnetic emission of photovoltaic systems, for example, adversely impacting radiocommunication, can pose a major barrier against further increase in photovoltaic penetration. This is particularly the case near sensitive infrastructure and activities such as hospitals, airports, search and rescue, and military. To understand the impact of each component and installation detail, we performed systematic radiated electromagnetic emission measurements on comparable commercial photovoltaic systems in the frequency range 150 kHz to 30 MHz. Our measurements indicate that string inverters are unlikely to interfere with radiocommunication when installed according to recommended standards, rules, guidelines, and regulations. It was shown that module-level power optimizers are the main cause of high levels of radiated emissions. The frameless bifacial module showed higher levels of radiated emissions than the monofacial module with frame. Changes in cable management and earthing have less impact on radiated emissions than the choice of solar inverter concept and module type.

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  • 5.
    Lidberg, Tina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Olofsson, Thomas
    Umeå Universitet, Institutionen för tillämpad fysik och elektronik.
    Ödlund, Louise
    Linköpings Universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Impact of Domestic Hot Water Systems on District Heating Temperatures2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 24, article id 4694Article in journal (Refereed)
    Abstract [en]

    When buildings become more energy effective, the temperature levels of district heating systems need to be lower to decrease the losses from the distribution system and to keep district heating a competitive alternative on the heating market. For this reason, buildings that are refurbished need to be adapted to suit low-temperature district heating. The aim of this paper is to examine whether four different energy refurbishment packages (ERPs) can be used for lowering the temperature need of a multi-family buildings space heating and domestic hot water (DHW) system as well as to analyse the impact of the DHW circulation system on the return temperature. The results show that for all ERPs examined in this study, the space heating supply temperature agreed well with the temperature levels of a low-temperature district heating system. The results show that the temperature need of the DHW system will determine the supply temperature of the district heating system. In addition, the amount of days with heating demand decreases for all ERPs, which further increases the influence of the DHW system on the district heating system. In conclusion, the DHW system needs to be improved to enable the temperature levels of a low-temperature district heating system.

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    Lidberg et al
  • 6.
    Psimopoulos, Emmanouil
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Uppsala University.
    Johari, Fatemeh
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Widén, Joakim
    Impact of Boundary Conditions on the Performance Enhancement of Advanced Control Strategies for a Residential Building with a Heat Pump and PV System with Energy Storage2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 6Article in journal (Refereed)
    Abstract [en]

    Operational control strategies for the heating system of a single-family house with exhaust air heat pump and photovoltaic system and “smart” utilization of energy storage have been developed and evaluated in a simulation study. The main aim and novelty of this study is to evaluate the impact on the benefit of these advanced control strategies in terms of performance (energy use and economic) for a wide range of boundary conditions (country/climate, occupancy and appliance loads). Short-term weather data and historic price data for the same year as well as stochastic occupancy profiles that include the domestic hot water load are used as boundary for a parametric simulation study for the system modeled in detail in TRNSYS 17. Results show that the control using a forecast of dynamic electricity price leads to greater final energy savings than those due to the control using thermal storage for excess PV production in all of the examined locations except Sweden. The impact on self-consumption using thermal storage of heat produced by the heat pump using excess PV production is found to decrease linearly with increasing household electricity for all locations. A reduction in final energy of up to 842 kWh year−1 can be achieved just by the use of these algorithms. The net energy cost for the end-user follows the same trend as for final energy and can result in cost savings up to 175 € year−1 in Germany and Spain due to the use of the advanced control.

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  • 7.
    Ramírez Villegas, Ricardo
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. University of Gävle.
    Eriksson, O.
    Olofsson, T.
    Environmental payback of renovation strategies in a northern climate-the impact of nuclear power and fossil fuels in the electricity supply2019In: Energies, E-ISSN 1996-1073, Vol. 13, no 1, article id 80Article in journal (Refereed)
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  • 8.
    Ramírez Villegas, Ricardo
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. University of Gävle.
    Eriksson, O.
    Olofsson, T.
    Life cycle assessment of building renovation measures–trade-off between building materials and energy2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 3, article id 344Article in journal (Refereed)
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  • 9.
    Ramírez Villegas, Ricardo
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Högskolan i Gävle.
    Eriksson, Ola
    Olofsson, Thomas
    Combined environmental and economic assessment of energy efficiency measures in a multi-dwelling building2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 13, article id 2484Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to assess how different renovation scenarios affect the environmental and economic impacts of a multi-dwelling building in a Nordic climate, how these aspects are correlated and how different energy carriers affect different environmental impact categories. In order to reduce greenhouse gas emissions, the European Union has set an agenda in order to reduce energy use in buildings. New buildings on the European market have a low replacement rate, which makes building renovation an important factor for achieving the European Union goals. In this study, eight renovation strategies were analyzed following the European Committee for Standardization standards for life cycle assessment and life cycle costs of buildings. This study covers all life cycle steps from cradle to grave. The renovation scenarios include combinations of photovoltaics, geothermal heat pumps, heat recovery ventilation and improved building envelopes. Results show that, depending on the energy carrier, reductions in global warming potential can be achieved at the expense of an increased nuclear waste disposal. It also shows that for the investigated renovation strategies in Sweden there is no correlation between the economic and the environmental performance of the building. Changing energy carriers in Sweden in order to reduce greenhouse gas emissions can be a good alternative, but it makes the system more dependent on nuclear power.

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  • 10. Singh, Anirudh
    et al.
    Dhar, Atul
    Kumar, Parmod
    Powar, Satvasheel
    Dalarna University, School of Information and Engineering, Energy Technology. Indian Inst Technol Mandi, Sch Engn, India.
    Computational Study on Parametric Variation with Solar Heat Induction of an Entrained Flow Gasifier2022In: Energies, E-ISSN 1996-1073, Vol. 15, no 11, article id 3873Article in journal (Refereed)
    Abstract [en]

    Gasification has played an important role in the sustainable use of waste biomass, providing useful combustible gases in the process. Gasification has an important role in waste management and promotes energy independence for many oil-deficit countries. The gasification process has been studied by various researchers, and improvements have been achieved in its sub-processes such as devolatilization, feed input methods, and so on. We examined the influence of gasifier operation parameters, such as oxidizer content, moisture content in the feedstock, and solar flux input inside the gasifier, on the temperature distribution, velocity distribution, and product gas yields of the gasifier. The results indicate that inducing solar energy at different stages of the gasifier leads to different yields of product gas composition (CO and H-2).

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

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

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  • 12.
    Swing Gustafsson, Moa
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. Mälardalens högskola.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Dotzauer, Erik
    Gustafsson, Marcus
    Life cycle cost of building energy renovation measures, considering future energy production scenarios2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 14, article id 2719Article in journal (Refereed)
    Abstract [en]

    A common way of calculating the life cycle cost (LCC) of building renovation measures is to approach it from the building side, where the energy system is considered by calculating the savings in the form of less bought energy. In this study a wider perspective is introduced. The LCC for three different energy renovation measures, mechanical ventilation with heat recovery and two different heat pump systems, are compared to a reference case, a building connected to the district heating system. The energy system supplying the building is assumed to be 100% renewable, where eight different future scenarios are considered. The LCC is calculated as the total cost for the renovation measures and the energy systems. All renovation measures result in a lower district heating demand, at the expense of an increased electricity demand. All renovation measures also result in an increased LCC, compared to the reference building. When aiming for a transformation towards a 100% renewable system in the future, this study shows the importance of having a system perspective, and also taking possible future production scenarios into consideration when evaluating building renovation measures that are carried out today, but will last for several years, in which the energy production system, hopefully, will change.

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

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

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