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  • 1.
    Ahlberg Tidblad, Annika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Volvo Car Corp, SE-40531 Gothenburg, Sweden.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    de Meatza, Iratxe
    CIDETEC, Basque Res & Technol Alliance BRTA, P Miramon 196, Donostia San Sebastian 20014, Spain.
    Landa-Medrano, Imanol
    CIDETEC, Basque Res & Technol Alliance BRTA, P Miramon 196, Donostia San Sebastian 20014, Spain.
    Biendicho, Jordi Jacas
    Inst Recerca Energia Catalunya IREC, Barcelona 08930, Spain.
    Trilla, Lluís
    Inst Recerca Energia Catalunya IREC, Barcelona 08930, Spain.
    Buysse, Maarten
    Bax & Co, Barcelona 08013, Spain.
    Ierides, Marcos
    Bax & Co, Barcelona 08013, Spain.
    Perez Horno, Beatriz
    Bax & Co, Barcelona 08013, Spain.
    Kotak, Yash
    TH Ingolstadt, CARISSMA Inst Elect Connected & Secure Mobil C EC, Esplanade 10, D-85049 Ingolstadt, Germany.
    Schweiger, Hans-Georg
    TH Ingolstadt, CARISSMA Inst Elect Connected & Secure Mobil C EC, Esplanade 10, D-85049 Ingolstadt, Germany.
    Koch, Daniel
    TH Ingolstadt, CARISSMA Inst Elect Connected & Secure Mobil C EC, Esplanade 10, D-85049 Ingolstadt, Germany.
    Kotak, Bhavya Satishbhai
    TH Ingolstadt, CARISSMA Inst Elect Connected & Secure Mobil C EC, Esplanade 10, D-85049 Ingolstadt, Germany.
    Future Material Developments for Electric Vehicle Battery Cells Answering Growing Demands from an End-User Perspective2021In: Energies, E-ISSN 1996-1073, Vol. 14, no 14, article id 4223Article, review/survey (Refereed)
    Abstract [en]

    Nowadays, batteries for electric vehicles are expected to have a high energy density, allow fast charging and maintain long cycle life, while providing affordable traction, and complying with stringent safety and environmental standards. Extensive research on novel materials at cell level is hence needed for the continuous improvement of the batteries coupled towards achieving these requirements. This article firstly delves into future developments in electric vehicles from a technology perspective, and the perspective of changing end-user demands. After these end-user needs are defined, their translation into future battery requirements is described. A detailed review of expected material developments follows, to address these dynamic and changing needs. Developments on anodes, cathodes, electrolyte and cell level will be discussed. Finally, a special section will discuss the safety aspects with these increasing end-user demands and how to overcome these issues.

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  • 2.
    Ahmad, Haseeb
    Gotland University, School of Culture, Energy and Environment.
    Offshore Wind Park Connection to an HVDC Platform, without using an AC Collector Platform2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the comparison between two different alternating current topologies of an offshore wind farms connection to an offshore high voltage direct current (HVDC) converter platform. The offshore high voltage direct current converter platform converts alternating current into direct current. Two different topologies will be investigated.

    In the first topology, the offshore wind farms are connected to an HVDC converter platform through offshore AC collector platform. An offshore AC collector platform is used to collect energy from the wind farm and step up the voltages for transmission to HVDC convertor platform. The offshore AC collector platforms contribute significantly in the total cost and technical complexity of the HVDC connection.

    In the second topology, the offshore AC collector platform is removed from the circuit and the offshore wind farms are connected directly to offshore HVDC converter platform.

    In this thesis, short circuit analysis and loss analysis of an offshore wind farm cluster connected to an offshore HVDC converter platform is conducted for the two topologies described above.

    Two wind turbine generator types i.e. doubly fed induction generator and full conversion generator is compared for two different topologies. The effect of changing the distance between wind farms and offshore HVDC converter platform on short circuit currents in the absence of AC collector platform is presented for the second configuration. Two internal voltage levels i.e. 33 kV and 66kV of wind farms are compared for short circuit currents in the absence of AC collector platform. DIgSILENT software is used to perform short circuit calculations.

    The thesis is done in collaboration with “Offshore Wind Connections” department ABB, Sweden. The idea is still under development however this study will serve as good starting point to figure out the cost efficient AC topology of an offshore wind park HVDC connection.

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    Offshore Wind Park Connection to an HVDC Platform, without using an AC Collector Platform
  • 3.
    Ahmed, Ubaid
    et al.
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Muhammad, Rasheed
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Abbas, Syed Sami
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Aziz, Imran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Mahmood, Anzar
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Short-term wind power forecasting using integrated boosting approach2024In: Frontiers in Energy Research, E-ISSN 2296-598X, Vol. 12, article id 1401978Article in journal (Refereed)
    Abstract [en]

    Rapidly increasing global energy demand and environmental concerns have shifted the attention of policymakers toward the large-scale integration of renewable energy resources (RERs). Wind energy is a type of RERs with vast energy potential and no environmental pollution is associated with it. The sustainable development goals: affordable and clean energy, climate action, and industry, innovation and infrastructure, can be achieved by integrating wind energy into the existing power systems. However, the integration of wind energy will bring instability challenges due to its intermittent nature. Mitigating these challenges necessitates the implementation of effective wind power forecasting models. Therefore, we have proposed a novel integrated approach, Boost-LR, for hour-ahead wind power forecasting. The Boost-LR is a multilevel technique consisting of non-parametric models, extreme gradient boosting (XgBoost), categorical boosting (CatBoost), and random forest (RF), and parametric approach, linear regression (LR). The first layer of the Boost-LR uses the boosting algorithms that process the data according to their tree development architectures and pass their intermediary forecast to LR which is deployed in layer two and processes the intermediary forecasts of layer one models to provide the final predicted wind power. To demonstrate the generalizability and robustness of the proposed study, the performance of Boost-LR is compared with the individual models of CatBoost, XgBoost, RF, deep learning networks: long short-term memory (LSTM) and gated recurrent unit (GRU), Transformer and Informer models using root mean square error (RMSE), mean square error (MSE), mean absolute error (MAE) and normalized root mean square error (NRMSE). Findings demonstrate the effectiveness of the Boost-LR as its forecasting performance is superior to the compared models. The improvement in MAE of Boost-LR is recorded as to be 31.42%, 32.14%, and 27.55% for the datasets of Bruska, Jelinak, and Inland wind farm, respectively as compared to the MAE of CatBoost which is revealed as the second-best performing model. Moreover, the proposed study also reports a literature comparison that further validates the effectiveness of Boost-LR performance for short-term wind power forecasting.

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  • 4.
    Ahnesjö, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Le Corre, Jean-Marie
    Westinghouse Electric Sweden AB.
    Andersson, Stig
    Westinghouse Electric Sweden AB.
    Tomographic reconstructions and predictions of radial void distribution in BWR fuel bundle with part-length rods2015Conference paper (Refereed)
    Abstract [en]

    The Westinghouse FRIGG facility, in Västerås/Sweden, is dedicated to the measurement of critical power,stability and pressure drop in fuel rod bundles under BWR operating conditions (steady-state andtransient). Capability to measure cross-sectional void and radial void distributions during steady-stateoperation was already considered when the facility was built in the late 1960s, using gamma transmissionmeasurements. In the 1990s, redesigned equipment was installed to allow for full 2D tomography andsome test campaigns were successfully run where the void was measured in the Westinghouse SVEA-96fuel bundle geometry with and without part-length rods.

    In this paper, the tomographic raw data from the SVEA-96 void measurement campaigns are revisitedusing various tomographic reconstruction techniques. This includes an algebraic method and a filteredback-projection method. Challenges, for example due to artifacts created by high difference in gammaabsorption, or to accurately identify the location of the bundle structure, are resolved. The resultingdetailed void distributions are then averaged over entire sub-channels or within the steam core only, forcomparison against sub-channel simulations.

    The resulting void distributions are compared against sub-channel void predictions using the VIPREW/MEFISTO code. The region downstream the part-length rods are of particular interest to investigatehow the void in the steam core is redistributed within the open region of the bundle. The comparisonshows a reasonable agreement between the measurements and the predictions.

  • 5.
    Aihara, Aya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity. Uppsala Univ, Dept Elect Engn, Div Elect, Uppsala, Sweden..
    Mendoza, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity. Hexicon, Slupskjulsvagen 30, S-11149 Stockholm, Sweden..
    Goude, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Bernhoff, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    A numerical study of strut and tower influence on the performance of vertical axis wind turbines using computational fluid dynamics simulation2022In: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 25, no 5, p. 897-913Article in journal (Refereed)
    Abstract [en]

    This paper presents the influence of the strut and the tower on the aerodynamic force of the blade for the vertical axis wind turbine (VAWT). It has been known that struts degrade the performance of VAWTs due to the inherent drag losses. In this study, three-dimensional Reynolds-averaged Navier-Stokes simulations have been conducted to investigate the effect of the strut and the tower on the flow pattern around the rotor region, the blade force distribution, and the rotor performance. A comparison has been made for three different cases where only the blade; both the blade and the strut; and all of the blade, the strut, and the tower are considered. A 12-kW three-bladed H-rotor VAWT has been studied for tip speed ratio of 4.16. This ratio is relatively high for this turbine, so the influence of the strut is expected to be crucial. The numerical model has been validated first for a single pitching blade and full VAWTs. The simulations show distinguished differences in the force distribution along the blade between two cases with and without struts. Since the wake from the struts interacts with the blades, the tangential force is reduced especially in the downwind side when the struts are considered. The calculated power coefficient is decreased by 43 %, which shows the importance of modeling the strut effect properly for accurate prediction of the turbine performance. The simulations also indicate that including the tower does not yield significant difference in the force distribution and the rotor power.

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  • 6.
    Aihara, Aya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Mendoza, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity. Hexicon AB, Ostra Jarnvagsgatan 27, S-11120 Stockholm, Sweden..
    Goude, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Bernhoff, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Comparison of Three-Dimensional Numerical Methods for Modeling of Strut Effect on the Performance of a Vertical Axis Wind Turbine2022In: Energies, E-ISSN 1996-1073, Vol. 15, no 7, article id 2361Article in journal (Refereed)
    Abstract [en]

    This paper compares three different numerical models to evaluate their accuracy for predicting the performance of an H-rotor vertical-axis wind turbine (VAWT) considering the influence of struts. The strut of VAWTs is one factor that makes the flow feature around the turbine more complex and thus influences the rotor performance. The focus of this study is placed on analyzing how accurately three different numerical approaches are able to reproduce the force distribution and the resulting power, taking the strut effect into account. For the 12 kW straight-bladed VAWT, the blade force is simulated at three tip speed ratios by the full computational fluid dynamics (CFD) model based on the Reynolds-averaged Navier-Stokes (RANS) equations, the actuator line model (ALM), and the vortex model. The results show that all the models do not indicate a significant influence of the struts in the total force over one revolution at low tip speed ratio. However, at middle and high tip speed ratio, the RANS model reproduces the significant decrease of the total tangential force that is caused due to the strut. Additionally, the RANS and vortex models present a clear influence of the struts in the force distribution along the blade at all three tip speed ratios investigated. The prediction by the ALM does not show such distinctive features of the strut impact. The RANS model is superior to the other two models for predicting the power coefficient considering the strut effect, especially at high tip speed ratio.

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  • 7.
    Al Obeid, Karar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Barr, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Energieffektivisering av Scanias automationsindustri: En studie som syftar till att förbättra Scanias verktyg, MDC-EE och utförs för att eliminera icke värdegivande tillförd energi för en bearbetningsmaskin och industriell tvättmaskin.2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Scania have set a goal to reduce 25% of its energy usages in the production to provide sustainable transport solution by 2025. Scania have studied their current production processes over the years for energy efficiency and have developed a tool named Machine Data Card - Energy Efficiency (MDC-EE) for a group of equipment (e.g., washing machine, machine tool). The developed MDC-EE for an equipment, consist of six levels and allows suppliers to grade their product according to Scania’s standard. This means that Scania can choose an energy efficient solution in the early procurement phase of a new equipment or facilities.

    We have studied two existing machines (i.e., a washing machine and a machine tool) at Scania with the energy efficiency method (i.e., MDC-EE) and propose improvements for energy efficiency. Later we evaluated the MDC-EE method and proposes improvement opportunities so the method can be generalised.

    A yearly saving of about 83 MWh can be achieved on the two machines by optimizing their operation time in relation to the real need in the process. Therefore, Scania has the possibility to save a large amount of energy, with little or no investment cost, if those improvements are implemented in machines like the examined units. 

    We continued to focus on the improvement opportunities on Scania’s energy efficiency method and suggests new definitions for different MDC-EE by clarifying the existing MDC-EE levels. In addition, we introduced an energy classing so that an equipment can be assessed by considering both operation time and installed power for all MDC-EE levels. 

    For the time being there is no information about which components should prioritized to increase the energy efficiency in a machine. If MDC-EE is used together with a weight factor, the correct components can be prioritized. As a recommendation, we suggested that Scania should continue working on a new method, based on the weighting factor, so that components can be prioritized in the initial stage of procurement.  

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  • 8.
    Alipour, Mohammad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yin, Litao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tavallaey, Shiva Sander
    ABB AB Corp Res, Forskargrand 7, SE-72178 Västerås, Sweden.;KTH, Dept Mech, Sch Sci, SE-10044 Stockholm, Sweden..
    Andersson, Anna Mikaela
    ABB AB Corp Res, Forskargrand 7, SE-72178 Västerås, Sweden..
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A surrogate-assisted uncertainty quantification and sensitivity analysis on a coupled electrochemical-thermal battery aging model2023In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 579, article id 233273Article in journal (Refereed)
    Abstract [en]

    High-fidelity physics-based models are required to comprehend battery behavior at various operating condi-tions. This paper proposes an uncertainty quantification analysis on a coupled electrochemical-thermal aging model to improve the reliability of a battery model, while also investigating the impact of parametric model uncertainties on battery voltage, temperature, and aging. The coupled model's high computing cost, however, is a significant barrier to perform uncertainty quantification (UQ) and sensitivity analysis (SA). To address this problem, a surrogate model - i.e, by simulating the outcome of a quantity of interest that cannot be easily computed or measured - based on the Gaussian process regression (GPR) theory and principle component analysis (PCA) is built, using a small collection of finite element simulation results as synthetic training data. In total, 43 variable electrochemical-thermal parameters as well as 13 variable aging parameters are studied and estimated. Moreover, the trained surrogate model is also used in the parameterization of the electrochemical and thermal models. The results show that the uncertainties in the input parameters significantly affect the estimations of battery voltage, temperature, and aging. Based on this sensitivity analysis, the most influential parameters affecting the above mentioned battery outputs are reported. This approach is thereby helpful for developing robust and reliable high-fidelity battery aging models with potential applications in digital twins as well as for synthetic data generation.

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  • 9.
    Alm, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Energieffektivisering av Saltsjöbaden Grand Hotell2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a hotel building there are many processes which consume energy, such as lightning and drive fan motor in the ventilation system. These processes needs supplied with electricity. The building is a big consumer of heat. The heating system is supplied with heat pumps and oil. The consumption of electricity is about 1700 MWh and 350 MWh of oil. This thesis affects an energy saving investigation for a hotel and the purpose is to find measures to reduce the energy consumption for this building. The method for the investigation consisted of three steps. First step was to establish how much energy the building consumes today. Second step was to find measures which could be implemented and the third was to calculate the energy saving potential for each measure. If all investigated measures will be implemented the Hotel could save up to 40 % energy. If only the economical and easy measures would be implemented the hotel could save 30 % energy. The easiest measure was to change some parameters in the control system so the oil burners did not go at all times. With that change and a change in the control system for ventilation to reduce the hours the ventilation are on gave reduced energy consumption with 20 %. The economical investments were converting one of the oil burners to an extra heat pump and to change all old lighting to a new LED-Lighting.

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  • 10.
    Almlöv, Melker
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Hammar, David
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    CFD Simulation and analysis of windings cooling using ANSYS FLUENT2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    High voltage transformers generate significant heat during operation, which must be effectively managed to prevent overheating and damage. To study and optimize the cooling of transformer windings, we use Computational Fluid Dynamics (CFD) simulations. These simulations focus on finite volume meshing, heat reduction, and identifying hot spots.

    CFD simulations work by dividing the transformer windings into many small cells using a technique called finite volume meshing. This detailed breakdown allows precise calculations of fluid flow and heat transfer. Finer mesh resolutions provide more accurate results but require more computing power, while mesh optimization focuses computa-tional resources on critical areas where overheating is most likely.

    The primary goal is to efficiently reduce the heat generated within the transformer windings. Identifying and managing hot spots, areas with the highest temperatures, is crucial for transformer reliability. CFD simulations map out these hot spots, which need special attention to prevent damage. Understanding how temperature is distributed throughout the transformer helps in designing systems that keep all areas within safe limits.

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    fulltext
  • 11.
    Amici, Julia
    et al.
    Politecn Torino, DISAT Dept Appl Sci & Technol, Corso Duca Abruzzi, 24, I-10129 Turin, Italy..
    Asinari, Pietro
    Politecn Torino, Dept Energy, Corso Duca Abruzzi, 24, I-10129 Turin, Italy.;Ist Nazl Ric Metrol INRiM, Str Cacce 91, I-10135 Turin, Italy..
    Ayerbe, Elixabete
    Basque Res & Technol Alliance BRTA, CIDETEC, Paseo Miramon 196, Donostia San Sebastian 20014, Spain..
    Barboux, Philippe
    PSL Res Univ, Chim ParisTech, CNRS, Inst Rech Chim Paris IRCP, F-75005 Paris, France..
    Bayle-Guillemaud, Pascale
    Univ Grenoble Alpes, CEA, CNRS, IRIG SyMMES, F-38000 Grenoble, France..
    Behm, R. Juergen
    Ulm Univ, Inst Theoret Chem, Albert Einstein Allee 11, D-89081 Ulm, Germany..
    Berecibar, Maitane
    Vrije Universiteit Brussel, MOBI Mobil Logist & Automot Technol Res Ctr, Pleinlaan 2, B-1050 Brussels, Belgium..
    Berg, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bhowmik, Arghya
    Tech Univ Denmark, Dept Energy Convers & Storage, Anker Engelundvej Bldg 301, DK-2800 Lyngby, Denmark..
    Bodoardo, Silvia
    Politecn Torino, DISAT Dept Appl Sci & Technol, Corso Duca Abruzzi, 24, I-10129 Turin, Italy..
    Castelli, Ivano E.
    Tech Univ Denmark, Dept Energy Convers & Storage, Anker Engelundvej Bldg 301, DK-2800 Lyngby, Denmark..
    Cekic-Laskovic, Isidora
    Forschungszentrum Julich, Helmholtz Inst Munster HI MS IEK12, Correns Str 46, North Rhine Westphalia, D-48149 Munster, Germany..
    Christensen, Rune
    Tech Univ Denmark, Dept Energy Convers & Storage, Anker Engelundvej Bldg 301, DK-2800 Lyngby, Denmark..
    Clark, Simon
    SINTEF Ind, New Energy Solut, Sem Saelands Vei 12, N-7034 Trondheim, Norway..
    Diehm, Ralf
    Karlsruhe Inst Technol KIT, Inst Thermal Proc Engn, Thin Film Technol, Kaiser Str 12, D-76131 Karlsruhe, Germany..
    Dominko, Robert
    Federat Rech CNRS 3104, ALISTORE European Res Inst, Hub Energie,15 Rue Baudelocque, F-80039 Amiens, France.;Helmholtz Inst Ulm HIU, Elctrochm Energy Storage, Helmholtz Str 11, D-89081 Ulm, Germany..
    Fichtner, Maximilian
    Helmholtz Inst Ulm HIU, Elctrochm Energy Storage, Helmholtz Str 11, D-89081 Ulm, Germany..
    Franco, Alejandro A.
    Federat Rech CNRS 3104, ALISTORE European Res Inst, Hub Energie,15 Rue Baudelocque, F-80039 Amiens, France.;Univ Picardie Jules Verne, Lab React Chim Solides LRCS, CNRS UMR 7314, Hub Energie,15 Rue Baudelocque, F-80039 Amiens, France.;Fed Rech CNRS 3459, Reseau Stockage Electrochim Energie RS2E, Hub Energie,15 Rue Baudelocque, F-80039 Amiens, France..
    Grimaud, Alexis
    Fed Rech CNRS 3459, Reseau Stockage Electrochim Energie RS2E, Hub Energie,15 Rue Baudelocque, F-80039 Amiens, France.;Coll France, Chim Solide Energie, UMR 8260, F-75231 Paris 5, France..
    Guillet, Nicolas
    Univ Grenoble Alpes, Liten, CEA, Ines Campus, F-73375 Le Bourget Du Lac, France..
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hartmann, Sarah
    Univ Grenoble Alpes, Leti, CEA, F-38000 Grenoble, France..
    Heiries, Vincent
    Fraunhofer Inst Silicate Res ISC, Neunerplatz 2, D-97082 Wurzburg, Germany..
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Heuer, Andreas
    Forschungszentrum Julich, Helmholtz Inst Munster HI MS IEK12, Correns Str 46, North Rhine Westphalia, D-48149 Munster, Germany.;Univ Munster, Inst Phys Chem, D-48149 Munster, Germany..
    Jana, Saibal
    Karlsruhe Inst Technol, Inst Nanotechnol, Hermann Helmholtz Platz 1, D-76344 Eggenstein Leopoldshafen, Germany..
    Jabbour, Lara
    Univ Grenoble Alpes, Liten, CEA, F-38000 Grenoble, France..
    Kallo, Josef
    Ulm Univ, Inst Energy Convers & Storage, Albert Einstein Allee 47, D-89081 Ulm, Germany..
    Latz, Arnulf
    Helmholtz Inst Ulm HIU, Elctrochm Energy Storage, Helmholtz Str 11, D-89081 Ulm, Germany.;German Aerosp Ctr, Pfaffenwaldring 38-40, D-70569 Stuttgart, Germany.;Ulm Univ, Albert Einstein Allee 47, D-89081 Ulm, Germany..
    Lorrmann, Henning
    Fraunhofer Inst Silicate Res ISC, Neunerplatz 2, D-97082 Wurzburg, Germany..
    Lovvik, Ole Martin
    SINTEF Ind, Sustainable Energy Technol, Forskningsveien 1, N-0314 Oslo, Norway..
    Lyonnard, Sandrine
    Univ Grenoble Alpes, CEA, CNRS, IRIG SyMMES, F-38000 Grenoble, France..
    Meeus, Marcel
    EMIRI, Rue Ransbeek, 310, B-1120 Brussels, Belgium..
    Paillard, Elie
    Politecn Milan, Dept Energy, Via Lambruschini 4, I-20156 Milan, Italy..
    Perraud, Simon
    Univ Grenoble Alpes, Liten, CEA, F-38000 Grenoble, France..
    Placke, Tobias
    Univ Munster, Inst Phys Chem, MEET Battery Res Ctr, Correns Str 46, D-48149 Munster, Germany..
    Punckt, Christian
    Helmholtz Inst Ulm HIU, Elctrochm Energy Storage, Helmholtz Str 11, D-89081 Ulm, Germany..
    Raccurt, Olivier
    Univ Grenoble Alpes, Liten, CEA, F-38000 Grenoble, France..
    Ruhland, Janna
    Karlsruher Inst Technol, Inst Prod Sci, Kaiser Str 12, D-76131 Karlsruhe, Germany..
    Sheridan, Edel
    SINTEF Energy, Elect Power Technol, Sem Saelands Vei 11, N-7034 Trondheim, Norway..
    Stein, Helge
    Helmholtz Inst Ulm HIU, Elctrochm Energy Storage, Helmholtz Str 11, D-89081 Ulm, Germany..
    Tarascon, Jean-Marie
    Fed Rech CNRS 3459, Reseau Stockage Electrochim Energie RS2E, Hub Energie,15 Rue Baudelocque, F-80039 Amiens, France.;Coll France, Chim Solide Energie, UMR 8260, F-75231 Paris 5, France..
    Trapp, Victor
    Fraunhofer Inst Silicate Res ISC, Neunerplatz 2, D-97082 Wurzburg, Germany..
    Vegge, Tejs
    Tech Univ Denmark, Dept Energy Convers & Storage, Anker Engelundvej Bldg 301, DK-2800 Lyngby, Denmark.;Federat Rech CNRS 3104, ALISTORE European Res Inst, Hub Energie,15 Rue Baudelocque, F-80039 Amiens, France..
    Weil, Marcel
    Helmholtz Inst Ulm HIU, Elctrochm Energy Storage, Helmholtz Str 11, D-89081 Ulm, Germany.;Karlsruher Inst Technol, Inst Technol Assessment & Syst Anal, Hermann Helmholtz Platz 1, D-76344 Eggenstein Leopoldshafen, Germany..
    Wenzel, Wolfgang
    Karlsruhe Inst Technol, Inst Nanotechnol, Hermann Helmholtz Platz 1, D-76344 Eggenstein Leopoldshafen, Germany..
    Winter, Martin
    Forschungszentrum Julich, Helmholtz Inst Munster HI MS IEK12, Correns Str 46, North Rhine Westphalia, D-48149 Munster, Germany.;Univ Munster, Inst Phys Chem, MEET Battery Res Ctr, Correns Str 46, D-48149 Munster, Germany..
    Wolf, Andreas
    Fraunhofer Inst Silicate Res ISC, Neunerplatz 2, D-97082 Wurzburg, Germany.;Friedrich Alexander Univ Nurnberg Erlangen FAU, Egerland Str 1, D-91058 Erlangen, Germany..
    Edström, Kristina
    Vrije Universiteit Brussel, MOBI Mobil Logist & Automot Technol Res Ctr, Pleinlaan 2, B-1050 Brussels, Belgium.;Univ Ljubljana, Natl Inst Chem, Fac Chem & Chem Technol, Ljubljana 1000, Slovenia..
    A Roadmap for Transforming Research to Invent the Batteries of the Future Designed within the European Large Scale Research Initiative BATTERY 2030+2022In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 12, no 17, article id 2102785Article, review/survey (Refereed)
    Abstract [en]

    This roadmap presents the transformational research ideas proposed by "BATTERY 2030+," the European large-scale research initiative for future battery chemistries. A "chemistry-neutral" roadmap to advance battery research, particularly at low technology readiness levels, is outlined, with a time horizon of more than ten years. The roadmap is centered around six themes: 1) accelerated materials discovery platform, 2) battery interface genome, with the integration of smart functionalities such as 3) sensing and 4) self-healing processes. Beyond chemistry related aspects also include crosscutting research regarding 5) manufacturability and 6) recyclability. This roadmap should be seen as an enabling complement to the global battery roadmaps which focus on expected ultrahigh battery performance, especially for the future of transport. Batteries are used in many applications and are considered to be one technology necessary to reach the climate goals. Currently the market is dominated by lithium-ion batteries, which perform well, but despite new generations coming in the near future, they will soon approach their performance limits. Without major breakthroughs, battery performance and production requirements will not be sufficient to enable the building of a climate-neutral society. Through this "chemistry neutral" approach a generic toolbox transforming the way batteries are developed, designed and manufactured, will be created.

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  • 12.
    Andersen, Soren Juhl
    et al.
    Tech Univ Denmark, DTU Wind Energy, DK-2800 Lyngby, Denmark.
    Sorensen, Jens Norkaer
    Tech Univ Denmark, DTU Wind Energy, DK-2800 Lyngby, Denmark.
    Mikkelsen, Robert
    Tech Univ Denmark, DTU Wind Energy, DK-2800 Lyngby, Denmark.
    Ivanell, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Statistics of LES Simulations of Large Wind Farms2016In: SCIENCE OF MAKING TORQUE FROM WIND (TORQUE 2016), IOP PUBLISHING LTD , 2016, article id 032002Conference paper (Refereed)
    Abstract [en]

    Numerous large eddy simulations are performed of large wind farms using the actuator line method, which has been fully coupled to the aero-elastic code, Flex5. The higher order moments of the flow field inside large wind farms is examined in order to determine a representative reference velocity. The statistical moments appear to collapse and hence the turbulence inside large wind farms can potentially be scaled accordingly. The thrust coefficient is estimated by two different reference velocities and the generic C-T expression by Frandsen. A reference velocity derived from the power production is shown to give very good agreement and furthermore enables the very good estimation of the thrust force using only the steady C-T-curve, even for very short time samples. Finally, the effective turbulence inside large wind farms and the equivalent loads are examined.

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  • 13.
    Andersson, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Bernhoff, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity. World Wide Wind Tech AS, Alesund, Norway.
    Goude, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Vortex filament method 3D analysis of design parameters for counter-rotating axis floating tilted turbine2023In: EERA DeepWind conference 2023 / [ed] Tande, J. O. G.; Kvamsdal, T.; Muskulus, M., Institute of Physics Publishing (IOPP), 2023, article id 012001Conference paper (Refereed)
    Abstract [en]

    The Counter-Rotating Axis Floating Tilted turbine (CRAFT) is a new design for floating off-shore wind power, which utilizes a low center of gravity and allows the tower to tilt to mitigate costs for platforming.

    In this study, 3D simulations of the CRAFT have been performed to investigate the effect from the tower's tilt angle on the aerodynamics of the turbine using a vortex filament method. Due to lack of empirical data of the CRAFT, the method has been benchmark tested against a previous project on a vertical axis wind turbine.

    Using this method, the blades' twist angle has been set to achieve good lift-to-drag ratio along the entire blade. Furthermore, the blades' chord length has been determined for optimal Tip Speed Ratio (TSR) 6 when the tower is tilted 30 degrees from vertical position.

    The CRAFT has been simulated vertically and tilted 15°, 30° and 45°, for TSRs ranging between 4 and 9. The power coefficients (CP) and normal forces have been determined, and velocity plots are presented to show how the near-wake develops.

    The results from this study serves as a basis for further development and design of the CRAFT.

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  • 14. Andersson, Frida
    Utvärdering av ventilationsflöde och luftkvalitet i bostadsgarage: En mätstudie och utformning av ett verktyg för framtida projekt2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Parking garages are often ventilated in accordance with SBN minimum requirements, which specify an extract air flow rate of 0.9 l/s, m2 for residential parking garages and 1.8 l/s, m2 for public parking garages. It has recently been observed that fan units in many cases are overdimensioned and as a result often operate at low flow rates and rarely need to operate at full capacity. Oversized air handling systems create an excessively high demand for energy which raises overall operation costs.

    The aim of this master’s thesis is to investigate if the air flow in residential parking garages can be reduced while avoiding excess levels of pollution and maintaining an acceptable building moisture level. Furthermore, an excel macro was created in order to facilitate a more streamlined approach for future projects. The function of the macro was to simplify the process of determining the dimensions of ventilationsystems.

    Two residential parking garages with different types of air handling units were compared by measuring pollution contents in the air as well as extract air flow rate. Additionally, simulations were carried out for three different scenarios where the air flow was varied. The purpose of the simulations was to examine the energy-saving benefits of lower airflows compared to the current ventilation flow rate.

    Based on measurement data and simulations it can be concluded that the exhaust air flow for the investigated parking garages can be reduced to 0.2 l / s, m2 without reaching excess levels of pollution or allowing unacceptable moisture levels to develop. However, it is important that the air handling unit can operate at higher air flows in order to vent temporarily high peak concentrations. Furthermore, it should be noted that the pollution levels were consistently kept low and only a few peak concentrations were registered. This was to some extent not an unexpected result. High peak concentrations can be registered in a misrepresentative fashion. For example, if a car starts near the gas sensor it can cause a high peak concentration to be registered. Upon validation of the excel macro used, it is clear that the results correspond well with the above-mentioned measurements. Further studies can be done however, in order to obtain even more conclusive results.

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  • 15. Andersson, Hjalmar
    et al.
    Zdansky Cottle, Leo
    Claesson, Melker
    Karlsson, Nils
    Stenhammar, Oscar
    Insamling av drift- och produktionsdata från energiteknik vid Ihus anläggning på Vaksala-Eke2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att minska den globala uppvärmningen bär utbyggnaden av förnybar energiproduktion en stor vikt i dagens samhälle. Av den anledningen är det av stor betydelse som nya tekniker för energiproduktion testas. För att undersöka huruvida dessa tekniker är effektiva och lönsamma är det viktigt att deras produktionsdata publiceras och görs tillgänglig för allmänheten. Det är anledningen till att det här projektet beställts från Ihus via STUNS energi.

    Projektidén var att samla in högfrekvent uppmätt produktionsdata från en soltracker, ett vindkraftverk och ett batterilager. Dessutom skulle väderdata samlas från en väderstation och solinstrålningsmätare för att sedan offentliggöra datan via STUNS Energiportal.

    För genomförandet av projektet användes en enklare dator för att ta emot information från olika sensorer. För att kommunicera med enheterna användes olika standardiserade kommunikationsprotokoll. Enheterna konfigurerades och kopplades in i datorn. Den insamlade datan bearbetades med en programmerad kod. Programmet sände iväg datan till en molnlagringsplattform för att sedan publicera den.

    Uppkoppling mot soltrackerns växelriktare samt pyranometern lyckades. Den insamlade informationen från de två enheterna publicerades sedan på Energiportalen. Väderstationen producerade data men kommunikation med det ursprungligt tänkta protokollet lyckades inte att upprättas. Genom ett annat protokoll erhölls värden, men inte genom den implementerade koden. Dessutom uppstod problem med batterilagret och vindkraftverket. Ingen information lyckades hämtas från någon av dem.

    I projektets gång har det samlats in mätpunkter var femte sekund för respektive enhet. Utifrån det erhållna resultatet kan de konstateras att vid högfrekvent insamling av väder- och produktionsdata, blir viktig information tydligare för vardera energiproduktionsenhet. Denna information kan gå förlorad vid lågfrekvent datainsamling. Det beror på vädrets hastiga fluktuation. En lågfrekventare datainsamling ger således en sämre uppfattning av hur värdena egentligen ändras med tiden.

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  • 16.
    Andersson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Helander-Claesson, Jonas
    Uppsala Water & Waste Ltd, Box 1444, SE-75144 Uppsala, Sweden.
    Olsson, Jesper
    Käppalaförbundet, Box 3095, SE-18103 Lidingö, Sweden.
    Study on reduced process temperature for energy optimisation in mesophilic digestion: A lab to full-scale study2020In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 271, article id 115108Article in journal (Refereed)
    Abstract [en]

    This unique study combined the lab and full scales to investigate how the anaerobic digestion process of sewage sludge was affected by a temperature change within the lower mesophilic temperature range (32–37.5 °C). Both scientific methane potential experiments and dewaterability studies were made to be used in changes of the operational conditions for a full-scale wastewater treatment plant. The aim of this study was to reduce anaerobic digestions heat consumption by altering the operational mesophilic temperature in first lab-scale experiments and then in continuation to full-scale conditions. The results of the study suggest that it is possible to save approximately 13% in heat energy demand each year by reducing the temperature for anaerobic digestion by 2.5 °C. At the lab scale, the effect of temperature on biogas production was tested in a batch experiment by measuring the biochemical methane production. At 32 °C, the production of biogas decreased by 11% compared to that at 37.5 °C. No significant difference was observed between 37.5 °C and 34.5 °C. The effect of temperature on sludge dewaterability was tested by measuring the capillary suction time, and no difference was detected between various temperatures. To confirm these results, the temperature in two full-scale digesters was gradually adjusted from 37.5 °C to 35 °C. No change was observed in biogas production, process stability, or dewaterability. The amount of heat energy that can be saved for the full-scale digesters was calculated using a heat balance. This study shows that it is possible to reduce the heat demand for AD in real applications without compromising the biogas production and process stability.

  • 17.
    Andersson, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Energy storage solutions for electric bus fast charging stations: Cost optimization of grid connection and grid reinforcements2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study investigates the economic benefits of installing a lithium-ion battery storage (lithium iron phosphate, LFP and lithium titanate, LTO) at an electric bus fast charging station.  It is conducted on a potential electric bus system in the Swedish city Västerås, and based on the existing bus schedules and routes as well as the local distribution system. The size of the energy storage as well as the maximum power outtake from the grid is optimized in order to minimize the total annual cost of the connection. The assessment of the distribution system shows that implementing an electric bus system based on opportunity charging in Västerås does not cause over-capacity in the 10 kV grid during normal feeding mode. However, grid reinforcements might become necessary to guarantee potential backup feeding modes. Batteries are not a cost effective option to decrease grid owner investments in new transformers. However, battery energy storage have the possibility to decrease the annual cost of connecting a fast charging station to the low-voltage grid. The main advantage of the storage system is to decrease the fees to the grid owner. Of the studied batteries, LTO is the most cost effective solution because of its larger possible depth-of-discharge for a given cycle life. The most important characteristics, that determine if a fast charging station could benefit economically from an energy storage, is the bus frequency. The longer the time in between buses and the higher the power demand, the more advantageous is the energy storage.

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  • 18.
    Andersson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Mårtensson, Gustav
    Mycronic AB, Täby.; Chalmers Univ Technol, MC2, EMSL, Gothenburg.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Flowing and pressurizing a solid-liquid two phase monodispersed fluid with high solid content in a transparent microfluidic high-pressure chip2017In: 28TH MICROMECHANICS AND MICROSYSTEMS EUROPE WORKSHOP, IOP PUBLISHING LTD , 2017, article id UNSP 012010Conference paper (Refereed)
    Abstract [en]

    Handling highly concentrated solid-liquid two-phase fluids in microfluidics is challenging. In this paper, we present the first studies of flowing solder paste with a high solid content in a transparent high-pressure tolerant glass chip, thereby increasing the understanding of how multiphase liquids with high density difference between the phases behave in small channels (840 mu m in diameter). The system, including a custom made high-pressure, low resistance, interface, was continuously operated at pressures up to of 6 MPa and devices where shown to have pressure tolerance up to 17 MPa. During flow through the chip, the packing density of the solder balls displayed inhomogeneity over the channel where chains of solder balls in contact with each other were formed together with voids. These in-homogeneities persisted along the channel during flow. The flow rate of the paste through the chip oscillated between 63 to 350 mu m/s when pumping at constant volume rate of 30 mu l/min. When a pressure of 2 MPa was applied, the volume of the solder paste particle segment decreased 1.6%, and 0.1% was elastically recovered when the pressure was released. It is concluded that this transparent microfluidic high-pressure glass chip with the special developed interface is suitable for flow studies of solder paste with a high solid content.

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  • 19.
    Andersson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Holcombe, Scott
    OECD Halden Reactor Project.
    Tverberg, Terje
    Halden Reactor Project.
    Quantitative Gamma Emission Tomography Inspection of LOCA rod IFA-650.152017In: EHPG, 2017Conference paper (Refereed)
  • 20.
    Andersson, Rassmus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Micro versus Nano: Impact of Particle Size on the Flow Characteristics of Silicon Anode Slurries2020In: ENERGY TECHNOLOGY, ISSN 2194-4288, Vol. 8, no 7, article id 2000056Article in journal (Refereed)
    Abstract [en]

    Silicon is interesting for use as a negative electrode material in Li-ion batteries due to its extremely high gravimetric capacity compared with today's state-of-the-art material, graphite. However, during cycling the Si particles suffer from large volume changes, leading to particle cracking, electrolyte decompositions, and electrode disintegration. Although utilizing nm-sized particles can mitigate some of these issues, it would instead be more cost-effective to incorporate mu m-sized silicon particles in the anode. Herein, it is shown that the size of the Si particles not only influences the electrode cycling properties but also has a decisive impact on the processing characteristics during electrode preparation. In water-based slurries and suspensions containing mu m-Si and nm-Si particles, the smaller particles consistently give higher viscosities and more pronounced viscoelastic properties, particularly at low shear rates. This difference is observed even when the Si particles are present as a minor component in blends with graphite. It is found that the viscosity follows the particle volume fraction divided by the particle radius, suggesting that it is dependent on the surface area concentration of the Si particles.

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  • 21.
    Antonelli, Jacopo
    Gotland University, School of Culture, Energy and Environment.
    Reduced order modeling of wind turbines in MatLab for grid integration and control studies2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The current trend in the wind power industry is to develop wind turbines of constantly increasing size and rated power, as well as wind farms of growing size and installed wind power. A careful study of the behaviour of the wind turbines during their operation is of crucial importance in the planning phase and in the design stage of a wind farm, in order to minimize the risks deriving from a non accurate prediction of their impact in the electric grid causing sensible faults of the system.

    To analyze the impact of the wind turbines in the system, motivates the development of accurate yet simple models.

    To be able to practically deal with this topics, a simple model of a wind turbine system is investigated and developed; it has the aim to describe the behaviour of a wind turbine in operation on a mechanical standpoint.

    The same reduced order simple model can also be employed for control system studies; the control system model that can’t be used in generation, can use the reduced model. Together with the analytical description of such model, is realized a MatLab code to numerically analyse the response of the system, and the results of the simulation through such code are presented.

    The objective of this thesis has been to provide a simple benchmark tool in MatLab for grid integration and control studies for interested researchers.

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    Reduced order modeling of wind turbines in MatLab for grid integration and control studies
  • 22.
    Ardo, Shane
    et al.
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA;Univ Calif Irvine, Dept Chem Engn & Mat Sci, Irvine, CA 92697 USA;US DOE, Off Energy Efficiency & Renewable Energy EERE, Fuel Cell Technol Off, EE-3F,1000 Independence Ave SW, Washington, DC 20585 USA.
    Rivas, David Fernandez
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Modestino, Miguel A.
    NYU, Dept Chem & Biomol Engn, Brooklyn, NY 11201 USA.
    Greiving, Verena Schulze
    Univ Twente, Dept Sci Technol & Policy Studies, Enschede, Netherlands.
    Abdi, Fatwa F.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Solar Fuels, Berlin, Germany.
    Llado, Esther Alarcon
    Amolf Inst, Ctr Nanophoton, Amsterdam, Netherlands.
    Artero, Vincent
    Univ Grenoble Alpes, CNRS, CEA, Lab Chim & Biol Metaux, Grenoble, France.
    Ayers, Katherine
    Proton OnSite, Wallingford, CT 06492 USA.
    Battaglia, Corsin
    Empa, Swiss Fed Labs Mat Sci & Technol, Dubendorf, Switzerland.
    Becker, Jan-Philipp
    Forschungszentrum Julich, IEK Photovolta 5, Julich, Germany.
    Bederak, Dmytro
    Univ Groningen, Zernike Inst Adv Mat, Nijenborgh 4, NL-9747 AG Groningen, Netherlands.
    Berger, Alan
    Air Prod & Chem Inc, Allentown, PA 18195 USA.
    Buda, Francesco
    Leiden Univ, Leiden Inst Chem, Leiden, Netherlands.
    Chinello, Enrico
    Ecole Polytech Fed Lausanne, LAPD, Lausanne, Switzerland.
    Dam, Bernard
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Di Palma, Valerio
    Eindhoven Univ Technol, Dept Appl Phys, Eindhoven, Netherlands.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Fujii, Katsushi
    Univ Kitakyushu, Inst Environm Sci & Technol, Wakamatsu Ku, Kitakyushu, Fukuoka, Japan.
    Gardeniers, Han
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Geerlings, Hans
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Hashemi, S. Mohammad H.
    Ecole Polytech Fed Lausanne, Opt Lab LO, Lausanne, Switzerland.
    Haussener, Sophia
    Ecole Polytech Fed Lausanne, LRESE, Lausanne, Switzerland.
    Houle, Frances
    Lawrence Berkeley Natl Lab, Joint Ctr Artificial Photosynthesis & Chem Sci Di, Berkeley, CA 94720 USA.
    Huskens, Jurriaan
    Univ Twente, MESA Inst Nanotechnol, Mol Nanofabricat Grp, Enschede, Netherlands.
    James, Brian D.
    Strateg Anal Inc, Arlington, VA 22203 USA.
    Konrad, Kornelia
    Univ Twente, Dept Sci Technol & Policy Studies, Enschede, Netherlands.
    Kudo, Akihiko
    Tokyo Univ Sci, Fac Sci, Dept Appl Chem, Tokyo 1628601, Japan.
    Kunturu, Pramod Patil
    Univ Twente, MESA Inst Nanotechnol, Mol Nanofabricat Grp, Enschede, Netherlands.
    Lohse, Detlef
    Univ Twente, MESA Inst Nanotechnol, Phys Fluids Grp, Enschede, Netherlands.
    Mei, Bastian
    Univ Twente, MESA Inst Nanotechnol, Photocatalyt Synth Grp, Enschede, Netherlands.
    Miller, Eric L.
    Moore, Gary F.
    Arizona State Univ, Sch Mol Sci, Biodesign Ctr Appl Struct Discovery CASD, Tempe, AZ 85287 USA.
    Muller, Jiri
    Inst Energiteknikk, Kjeller, Norway.
    Orchard, Katherine L.
    Univ Cambridge, Dept Chem, Cambridge, England.
    Rosser, Timothy E.
    Univ Cambridge, Dept Chem, Cambridge, England.
    Saadi, Fadl H.
    CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA.
    Schuttauf, Jan-Willem
    Swiss Ctr Elect & Microtechnol CSEM, PV Ctr, Neuchatel, Switzerland.
    Seger, Brian
    Tech Univ Denmark DTU, Dept Phys, Lyngby, Denmark.
    Sheehan, Stafford W.
    Catalyt Innovat, Fall River, MA 02723 USA.
    Smith, Wilson A.
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Spurgeon, Joshua
    Univ Louisville, Conn Ctr Renewable Energy Res, Louisville, KY 40292 USA.
    Tang, Maureen H.
    Drexel Univ, Chem & Biol Engn, Philadelphia, PA 19104 USA.
    van de Krol, Roel
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Solar Fuels, Berlin, Germany.
    Vesborg, Peter C. K.
    Tech Univ Denmark DTU, Dept Phys, Lyngby, Denmark.
    Westerik, Pieter
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Pathways to electrochemical solar-hydrogen technologies2018In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 11, no 10, p. 2768-2783Article, review/survey (Refereed)
    Abstract [en]

    Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/ or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.

  • 23.
    Armand, Michel
    et al.
    Basque Res & Technol Alliance BRTA, Ctr Cooperat Res Alternat Energies CIC EnergiGUNE, Alava Technol Pk,Albert Einstein 48, Vitoria 01510, Spain.
    Axmann, Peter
    Zentrum Sonnenenergie & Wasserstoff Forsch Baden, Helmholtzstr 8, D-89081 Ulm, Germany.
    Bresser, Dominic
    Helmholtz Inst Ulm HIU, Helmholtzstr 11, D-89081 Ulm, Germany; Karlsruhe Inst Technol KIT, POB 3640, D-76021 Karlsruhe, Germany.
    Copley, Mark
    Univ Warwick, WMG, Coventry CV4 7AL, W Midlands, England.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. ALISTORE European Res Inst, CNRS, FR 3104, Hub Energie, 15 Rue Baudelocque, F-80039 Amiens, France.
    Ekberg, Christian
    Chalmers Univ Technol, Dept Chem & Chem Engn, Nucl Chem & Ind Mat Recycling, S-41296 Gothenburg, Sweden.
    Guyomard, Dominique
    Univ Nantes, CNRS, Inst Mat Jean Rouxel, IMN, F-44000 Nantes, France.
    Lestriez, Bernard
    Univ Nantes, CNRS, Inst Mat Jean Rouxel, IMN, F-44000 Nantes, France.
    Novák, Petr
    Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Petranikova, Martina
    Chalmers Univ Technol, Dept Chem & Chem Engn, Nucl Chem & Ind Mat Recycling, S-41296 Gothenburg, Sweden.
    Porcher, Willy
    Univ Grenoble Alpes, CEA Liten, 17 Ave Martyrs, F-38054 Grenoble, France.
    Trabesinger, Sigita
    Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Wohlfahrt-Mehrens, Margret
    Zentrum Sonnenenergie & Wasserstoff Forsch Baden, Helmholtzstr 8, D-89081 Ulm, Germany; Helmholtz Inst Ulm HIU, Helmholtzstr 11, D-89081 Ulm, Germany.
    Zhang, Heng
    Basque Res & Technol Alliance BRTA, Ctr Cooperat Res Alternat Energies CIC EnergiGUNE, Alava Technol Pk,Albert Einstein 48, Vitoria 01510, Spain.
    Lithium-ion batteries: Current state of the art and anticipated developments2020In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 479, article id 228708Article in journal (Refereed)
    Abstract [en]

    Lithium-ion batteries are the state-of-the-art electrochemical energy storage technology for mobile electronic devices and electric vehicles. Accordingly, they have attracted a continuously increasing interest in academia and industry, which has led to a steady improvement in energy and power density, while the costs have decreased at even faster pace. Important questions, though, are, to which extent and how (fast) the performance can be further improved, and how the envisioned goal of truly sustainable energy storage can be realized.

    Herein, we combine a comprehensive review of important findings and developments in this field that have enabled their tremendous success with an overview of very recent trends concerning the active materials for the negative and positive electrode as well as the electrolyte. Moreover, we critically discuss current and anticipated electrode fabrication processes, as well as an essential prerequisite for "greener" batteries - the recycling. In each of these chapters, we eventually summarize important remaining challenges and propose potential directions for further improvement. Finally, we conclude this article with a brief summary of the performance metrics of commercial lithium-ion cells and a few thoughts towards the future development of this technology including several key performance indicators for the mid-term to long-term future.

  • 24.
    Aslani, Mohammad
    et al.
    Univ Gävle, Dept Comp & Geospatial Sci, Gävle, Sweden..
    Seipel, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Univ Gävle, Dept Comp & Geospatial Sci, Gävle, Sweden.
    Automatic identification of utilizable rooftop areas in digital surface models for photovoltaics potential assessment2022In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 306, article id 118033Article in journal (Refereed)
    Abstract [en]

    The considerable potential of rooftop photovoltaics (RPVs) for alleviating the high energy demand of cities has made them a proven technology in local energy networks. Identification of rooftop areas suitable for installing RPVs is of importance for energy planning. Having these suitable areas referred to as utilizable areas greatly assists in a reliable estimate of RPVs energy production. Within such a context, this research aims to propose a spatially detailed methodology that involves (a) automatic extraction of buildings footprint, (b) automatic segmentation of roof faces, and (c) automatic identification of utilizable areas of roof faces for solar infrastructure installation. Specifically, the innovations of this work are a new method for roof face segmentation and a new method for the identification of utilizable rooftop areas. The proposed methodology only requires digital surface models (DSMs) as input, and it is independent of other auxiliary spatial data to become more functional. A part of downtown Gothenburg composed of vegetation and high-rise buildings with complex shapes was selected to demonstrate the methodology performance. According to the experimental results, the proposed methodology has a high success rate in building extraction (about 95% correctness and completeness) and roof face segmentation (about 85% completeness and correctness). Additionally, the results suggest that the effects of roof occlusions and roof superstructures are satisfactorily considered in the identification of utilizable rooftop areas. Thus, the methodology is practically effective and relevant for the detailed RPVs assessments in arbitrary urban regions where only DSMs are accessible.

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  • 25.
    Aslani, Mohammad
    et al.
    Univ Gävle, Dept Comp & Geospatial Sci, Gävle, Sweden..
    Seipel, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division Vi3. Univ Gävle, Dept Comp & Geospatial Sci, Gävle, Sweden..
    Rooftop segmentation and optimization of photovoltaic panel layouts in digital surface models2023In: Computers, Environment and Urban Systems, ISSN 0198-9715, E-ISSN 1873-7587, Vol. 105, article id 102026Article in journal (Refereed)
    Abstract [en]

    Rooftop photovoltaic panels (RPVs) are being increasingly used in urban areas as a promising means of achieving energy sustainability. Determining proper layouts of RPVs that make the best use of rooftop areas is of importance as they have a considerable impact on the RPVs performance in efficiently producing energy. In this study, a new spatial methodology for automatically determining the proper layouts of RPVs is proposed. It aims to both extract planar rooftop segments and identify feasible layouts with the highest number of RPVs in highly irradiated areas. It leverages digital surface models (DSMs) to consider roof shapes and occlusions in placing RPVs. The innovations of the work are twofold: (a) a new method for plane segmentation, and (b) a new method for optimally placing RPVs based on metaheuristic optimization, which best utilizes the limited rooftop areas. The proposed methodology is evaluated on two test sites that differ in urban morphology, building size, and spatial resolution. The results show that the plane segmentation method can accurately extract planar segments, achieving 88.7% and 99.5% precision in the test sites. In addition, the results indicate that complex rooftops are adequately handled for placing RPVs, and overestimation of solar energy potential is avoided if detailed analysis based on panel placement is employed.

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  • 26.
    Atak, Haluk
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Department of Nuclear Engineering, Hacetteppe University.
    Anastasiadis, Anastasios
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Elter, Zsolt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Holcombe, Scott
    Institute for Energy Technology – OECD Halden Reactor Project.
    Andersson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    The degradation of gamma-ray mass attenuation of UOX and MOX fuel with nuclear burnup2020In: Progress in nuclear energy (New series), ISSN 0149-1970, E-ISSN 1878-4224, Vol. 125, article id 103359Article in journal (Refereed)
    Abstract [en]

    Nondestructive gamma-ray spectrometry of nuclear fuel is routinely performed in axial gamma scanning devices and more recently with gamma emission tomography. Following the irradiation of a fresh nuclear fuel with high intensity neutron flux in a nuclear reactor core, a great number of gamma-emitting radionuclides are created. These can be utilized for gamma spectrometric techniques. However, due to the high density and atomic number of the nuclear fuel, self-attenuation of gamma-rays is a challenge, which requires attenuation correction in order to perform accurate analysis of the source activity in the fuel.

    In this study, the degradation of the gamma-ray mass attenuation with burnup was investigated and, in addition, a predictive model was created by investigating the attenuation change at various gamma energies caused by the burnup of the nuclear fuel. This model is intended for use by spectrometry practitioners inspecting nuclear fuel. To this aim, the energy-dependent gamma-ray mass-attenuation coefficients were investigated as a function of burnup for UOX, and three MOX fuels having different initial Pu contents. The Serpent 2 reactor physics code was used to simulate the burnup history of the fuel pins. The nuclide inventory of the Serpent 2 output is combined with the NIST XCOM database to calculate the mass attenuation coefficients.

    The mass attenuation coefficient of the fuel was found to decrease with the fuel burnup, in the range of a few percent, depending on the burnup and gamma energy. Also, a theoretical burnup dependent swelling model was imposed on fuel density to see how linear attenuation coefficient of fuel material is changed. Furthermore, greater effect may be expected on the transmitted intensity, where a simulation study of a PWR assembly revealed that the contribution from the inner rods in a scanned fuel assembly increased by tens of percent compared to the one with non-irradiated fresh fuels, when shielded by the outer rods of the assembly. A sensitivity analysis was performed in order to test the effect of a number of geometrical and operational reactor parameters that were considered to potentially effect the mass attenuation coefficient. Finally, a simple-to-use predictive model was constructed providing the mass-attenuation coefficient [cm2/g] of fuel as a function of burnup [MWd/kgHM] and initial Pu content [wt%]. The resulting predictive model was optimized by using the nonlinear regression method.

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  • 27.
    Avila, M.
    et al.
    Barcelona Supercomp Ctr, CASE Dept, Barcelona, Spain..
    Chavez-Arroyo, R. A.
    Natl Renewable Energy Ctr CENER, Sarriguren, Spain..
    Arnqvist, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Olivares-Espinosa, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Dellwik, E.
    Tech Univ Denmark, Dept Wind Energy, Roskilde, Denmark..
    Daily cycle simulations of thermally stratified flows over forests2019In: Wake Conference 2019 22–24 May 2019, Visby, Sweden, IOP PUBLISHING LTD , 2019, article id 012003Conference paper (Refereed)
    Abstract [en]

    The aim of the present work is to obtain a better understanding of how to model the thermally stratified wind field over a forest during full diurnal cycles. The setup of the study assumes a horizontally homogeneous forest, with the objective of finding a simple and efficient way to model the canopy flow using time-dependent input data, obtained from measurements and mesoscale simulations. With this, new insights can be gained for future microscale modelling of complex forested terrains using mesoscale input data. In terrain without forest a diurnal cycle is commonly simulated by imposing time-dependent ground temperature. However, the presence of forests partially isolates the temperature at ground level from the flow above the canopy, making this common approach ineffective. This work proposes imposing the time-dependent net radiation at the forest canopy top to drive the thermal stratification changes along the diurnal cycle. To this end, several full days of simulation are driven by prescribing the net radiative heat flux balance measured on top of the canopy, together with a geostrophic pressure gradient. The advantage of the method is its simplicity and that the input data can be easily obtained from mesoscale modelling. When compared to the observations at the Swedish site Ryningsnas, the new method dramatically improves estimations of wind speed, wind direction and turbulent kinetic energy compared to simulations that only assume neutral stratification. Out of the variables studied, temperature and turbulent heat flux profiles were the ones that qualitatively followed the measurements the best, while wind speed and turbulent kinetic energy showed a larger disagreement.

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  • 28.
    Aydin, Murat
    et al.
    Bochum Univ Appl Sci, Int Geothermal Ctr, D-44801 Bochum, Germany;Istanbul Tech Univ, Energy Inst, TR-34469 Istanbul, Turkey.
    Onur, Mustafa
    Univ Tulsa, McDougall Sch Petr Engn, Tulsa, OK 74104 USA.
    Sisman, Altug
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Istanbul Tech Univ, Energy Inst, TR-34469 Istanbul, Turkey.
    A new method for analysis of constant-temperature thermal response tests2019In: Geothermics, ISSN 0375-6505, E-ISSN 1879-3576, Vol. 78, p. 1-8Article in journal (Refereed)
    Abstract [en]

    In this study, a new analysis method is proposed for estimating thermal conductivity of a ground by using the constant-temperature thermal response test data. The new method is based on an analytical solution of heat transfer rate per unit borehole length by using the Laplace transformation for constant-temperature thermal response tests. Its advantage is that it allows one to estimate thermal conductivity directly from the slope of the logarithmic time dependency of inverse unit-heat-transfer rate value without making an estimation of volumetric heat capacity. The method has been verified by using a numerical model and applied to different experimental data based on different test temperatures and compared with the classical thermal response test method. The results show that the proposed method reliably and effectively estimates thermal conductivity of ground.

  • 29.
    Aydin, Murat
    et al.
    Ruhr Univ Bochum, Engn Geol & Rock Mass Mech, Bochum, Germany..
    Ozdogan Dolcek, Ayse
    Univ Balikesir, Dapartment Geol Engn, Balikesir, Turkiye..
    Onur, Mustafa
    Univ Tulsa, McDougall Sch Petr Engn, Tulsa, OK 74104 USA..
    Sisman, Altug
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Flow-controlled thermal response test and its comparison with the conventional test methods2024In: Geothermics, ISSN 0375-6505, E-ISSN 1879-3576, Vol. 120, article id 103011Article in journal (Refereed)
    Abstract [en]

    A novel flow-controlled (FC) thermal response test (TRT) system is introduced to resolve the recently addressed inconsistency between the constant heat flux (CHF) and constant temperature (CT) TRTs. FC-TRT allows us to keep both inlet and outlet temperatures constant and improve the accuracy of CT-TRT. Using the FC-TRT system, four types of TRT experiments are performed, providing CT, CHF, and constant inlet temperature conditions, besides the novel one keeping both temperature and heat flux constant. Thermal conductivities from these TRT measurements are compared, and a good agreement is observed. FC-TRT offers higher accuracy and various TRT applications in one platform.

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  • 30.
    Aydin, Murat
    et al.
    Istanbul Technical University, Energy Institute.
    Sisman, Altug
    Istanbul Technical University, Energy Institute.
    Experimental and computational investigation of multi U-tube boreholes2015In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 145, p. 163-171Article in journal (Refereed)
    Abstract [en]

    In ground source heat pump (GSHP) applications, borehole drilling cost constitutes an important part ofthe investment cost and it can be reduced by improving borehole performance. In vertical GSHP applications,usually double-U tube configurations are used to improve the heat transfer rate per unit length of aborehole, (unit HTR value). To determine the optimal number of U-tubes which maximizes the commercialand engineering benefits of multi U-tube applications, cost and performance analyses of multi U-tubeboreholes are crucial. In this study, a triple U-tube is used in a borehole of 50 m depth. Time variation ofunit HTR value of the borehole is experimentally measured when single, double and triple U-tubes are inoperation separately. Furthermore a computational model is calibrated by fitting the computationalresults to the experimental ones, and effects of using four and five U-tubes in a borehole are computationallyinvestigated. The relations between number of U tubes and time variation of unit HTR value ofa borehole as well as investment cost are analyzed. Long term borehole performance predictions aremade and compared for multi U-tube applications. Both experimental and computational results showedthat performance improvements are remarkable for 2U-tube and 3U-tube configurations while it isnearly insignificant for 4U and 5U ones. If the investment cost per thermal power is considered, 2U-tubeconfiguration is the optimal one if the prices of polyethylene pipes are relatively high, like in Turkey.When the cost of pipes decreases, then 3U-tube or even 4U–tube configuration can be the cheapestsolution.

  • 31.
    Ayob, Mohd Nasir
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Univ Malaysia Perlis, Sch Mechatron Engn, Arau 02600, Perlis, Malaysia.
    Castellucci, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Göteman, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Widén, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Abrahamsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Engström, Jens
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Waters, Rafael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Small-Scale Renewable Energy Converters for Battery Charging2018In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 6, no 1, article id 26Article in journal (Refereed)
    Abstract [en]

    This paper presents two wave energy concepts for small-scale electricity generation. In the presented case, these concepts are installed on the buoy of a heaving, point-absorbing wave energy converter (WEC) for large scale electricity production. In the studied WEC, developed by Uppsala University, small-scale electricity generation in the buoy is needed to power a tidal compensating system designed to increase the performance of the WEC in areas with high tides. The two considered and modeled concepts are an oscillating water column (OWC) and a heaving point absorber. The results indicate that the OWC is too small for the task and does not produce enough energy. On the other hand, the results show that a hybrid system composed of a small heaving point absorber combined with a solar energy system would be able to provide a requested minimum power of around 37.7W on average year around. The WEC and solar panel complement each other, as the WEC produces enough energy by itself during wintertime (but not in the summer), while the solar panel produces enough energy in the summer (but not in the winter).

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  • 32.
    Baak, Werner
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    TECHNO-ECONOMIC ANALYSIS OF REPOWERING POTENTIAL IN NORTH RHINE-WESTPHALIA, GERMANY2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Germany is one of the pioneer countries in wind turbine technology. They installed many wind turbines during the last decades and are now confronted with a shortage of land suitable for new wind parks. Now, with an estimated wind turbine service life of 20 – 25 years whole wind parks are becoming obsolete and owners have to decide whether do decommission, repower or to continue the operation of their parks. The advantages of repowering as well as the bureaucratic hurdles are outlined and evaluated.

    This thesis deals with the repowering potential in North Rhine-Westphalia and is analysing the technical and economical possibilities of repowering. The main objectives are to identify wind turbines eligible for repowering and also to develop repowering scenarios in order to determine their techno-economic feasibility.  The designed steps of the methodology allow the census and the subsequent implementation of the results in WindPro and RETScreen. 

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    Thesis_WernerBaak
  • 33.
    Babac, Gulru
    et al.
    Istanbul Technical University, Energy Institute.
    Sisman, Altug
    Istanbul Technical University, Energy Institute.
    Cimen, Tolga
    Istanbul Technical University, Energy Institute.
    Two-dimensional thermal analysis of liquid hydrogen tank insulation2009In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 34, p. 6357-6363Article in journal (Refereed)
    Abstract [en]

    Liquid hydrogen (LH2) storage has the advantage of high volumetric energy density, whileboil-off losses constitute a major disadvantage. To minimize the losses, complicatedinsulation techniques are necessary. In general, Multi Layer Insulation (MLI) and a Vapor-Cooled Shield (VCS) are used together in LH2 tanks. In the design of an LH2 tank with VCS,the main goal is to find the optimum location for the VCS in order to minimize heatleakage. In this study, a 2D thermal model is developed by considering the temperaturedependencies of the thermal conductivity and heat capacity of hydrogen gas. The developedmodel is used to analyze the effects of model considerations on heat leakagepredictions. Furthermore, heat leakage in insulation of LH2 tanks with single and doubleVCS is analyzed for an automobile application, and the optimum locations of the VCS forminimization of heat leakage are determined for both cases.

  • 34.
    Backlund, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Modellering, simulering och analys av kärnreaktorn BWRX-3002023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The demand for fossil-free energy production is rising due to electrification and increased consumption in the energy system. There are also multiple climate goals to reach, to preserve the possibilities of a sustainable future.

    A response to this is the BWRX-300, a natural circulation boiling water small modular reactor (SMR) concept developed by GE Hitachi Nuclear Energy. It is currently at the forefront of study for many power utility companies around the world. For decision making it is of interest to investigate the capabilities of new facilities. This Master Thesis work's aim is to study the BWRX-300 reactor's feasibility together with evaluating and optimizing its performance using the core simulation softwares Casmo5 and Simulate5.

    This is carried out by first verifying Simulate5's natural circulation capabilities by modifying an existing forced-circulation reactor to natural circulation, then comparing simulation results to real world data. 

    Next a comprehensive model of the BWRX-300 reactor pressure vessel is modelled and validated. Equilibrium cores for 12- and 24-month cycle lengths are then simulated where key reactor performance metrics such as fuel economy, safety margins, axial profiles (of voids and pressure drop) and reactor characteristics are extracted. The effect of different fuel assembly designs in the BWRX-300 reactor core is investigated to find first core design optimums. Furthermore the decay heat removal system in the BWRX-300 is investigated. Lastly the results are used to evaluate the optimal operating mode given the current and future more dynamic projected state of the energy system. 

    The results show that there are no real technical difficulties while operating the BWRX-300 reactor for 12 or 24 months. The decay heat removal system and core flow characteristics provide abundant coolant flow to maintain long term fuel integrity during both normal and abnormal operation modes. More or less routine core design optimization work is required to obtain sufficient safety margins and improve fuel economy. It is observed that the smaller reactor core requires an increase in average fuel enrichment to maintain criticality throughout the cycle, potentially creating an incentive to raise the current licensing limit. However it is deemed possible to avoid this by conducting further fuel design optimization work.

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  • 35.
    Baloukidis, D.
    et al.
    Democritus Univ Thrace, Dept Elect & Comp Engn, Xanthi, Greece..
    Sarris, T.
    Democritus Univ Thrace, Dept Elect & Comp Engn, Xanthi, Greece..
    Tourgaidis, S.
    Democritus Univ Thrace, Dept Elect & Comp Engn, Xanthi, Greece..
    Pirnaris, P.
    Democritus Univ Thrace, Dept Elect & Comp Engn, Xanthi, Greece..
    Aikio, A.
    Univ Oulu, Space Phys & Astron Res Unit, Oulu, Finland..
    Virtanen, I.
    Univ Oulu, Space Phys & Astron Res Unit, Oulu, Finland..
    Buchert, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Papadakis, K.
    Democritus Univ Thrace, Xanthi, Greece.;Univ Helsinki, Helsinki, Finland..
    A Comparative Assessment of the Distribution of Joule Heating in Altitude as Estimated in TIE-GCM and EISCAT Over One Solar Cycle2023In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 128, no 12, article id e2023JA031526Article in journal (Refereed)
    Abstract [en]

    During geomagnetically active times, Joule (or frictional) heating in the Lower Thermosphere-Ionosphere is a significant source of thermal energy, greatly affecting density, temperature, composition and circulation. At the same time, Joule heating and the associated Pedersen conductivity are amongst the least known parameters in the upper atmosphere in terms of their quantification and spatial distribution, and their parameterization by geomagnetic parameters shows large discrepancies between estimation methodologies, primarily due to a lack of comprehensive measurements in the region where they maximize. In this work we perform a long-term statistical comparison of Joule heating as calculated by the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) and as obtained through radar measurements by the European Incoherent Scatter Scientific Association (EISCAT). Statistical estimates of Joule heating and Pedersen conductivity are obtained from a simulation run over the 11 year period spanning from 2009 until 2019 and from radar measurements over the same period, during times of radar measurements. The results are statistically compared in different Magnetic Local Time sectors and Kp level ranges in terms of median values and percentiles of altitude profiles. It is found that Joule heating and Pedersen conductivity are higher on average in TIE-GCM than in EISCAT for low Kp and are lower than EISCAT for high Kp. It is also found that neutral winds cannot account for the discrepancies between TIE-GCM and EISCAT. Comparisons point toward the need for a Kp-dependent parameterization of Joule heating in TIE-GCM to account for the contribution of small scale effects. During times of high solar activity, Joule (or frictional) heating in the Lower Thermosphere-Ionosphere is a significant source of thermal energy, greatly affecting density, temperature, composition and circulation. Joule heating is largely unknown, due to a lack of measurements in the altitude ranges where it maximizes. In this work we compare Joule heating estimates from the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) and as obtained through radar measurements by the European Incoherent Scatter Scientific Association (EISCAT), from a simulation run over the 11 year period spanning from 2009 until 2019 and from radar measurements over the same period. The results are compared in different Magnetic Local Time sectors and Kp level ranges in terms of median values and percentiles of altitude profiles. It is found that Joule heating and Pedersen conductivity are higher on average in TIE-GCM than in EISCAT for low activity levels and are lower than EISCAT for high activity levels. It is also found that neutral winds cannot account for the discrepancies between TIE-GCM and EISCAT. Comparisons point toward the need for a new parameterization of Joule heating in TIE-GCM to account for the contribution of small scale effects. Joule heating and Pedersen conductivity are calculated in Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) and European Incoherent Scatter Scientific Association (EISCAT) during solar cycle 24, as a function of Kp, Magnetic Local Time and altitudeJoule heating and Pedersen conductivity in TIE-GCM are under-estimated for high Kp compared to EISCAT measurementsComparisons point toward the need for parameterization of small scale effects in TIE-GCM

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  • 36.
    Bao, Haiyan
    et al.
    Changsha Univ Sci & Technol, Sch Hydraul Engn, Changsha.; Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan.
    Yang, Jiandong
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan.
    Zhao, Guilian
    PowerChina Chengdu Engn Corp Ltd, Chengdu.
    Zeng, Wei
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Hubei, Peoples R China..
    Liu, Yanna
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan.
    Yang, Weijia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan.
    Condition of setting surge tanks in hydropower plants - A review2018In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 81, p. 2059-2070Article, review/survey (Refereed)
    Abstract [en]

    Hydropower plays an important role in the safe, stable and efficient operation of power systems, especially with current trends toward renewable energy systems. The total global potential of gross, technical, economic, and exploitable hydropower are still enormous in the future, and the developments of new hydropower stations (HPSs) are of great importance. For constructions of new HPSs, the condition of setting surge tanks (CSST) is crucial for various perspectives, e.g. safety, stability and economy of HPSs. In this review, the CSST are summarized and analyzed from the three aspects: regulation assurance, operation stability, and the regulation quality, with an aim of providing a reference and guidance for research and engineering applications regarding surge tanks. Upstream and downstream surge tanks in conventional HPSs and pumped storage power stations are all included. Moreover, a comprehensive comparison of CSST under different conditions is conducted. One of the main focuses of this review is on Chinese studies, for introducing many meaningful results written in Chinese to more readers all over the world.

  • 37.
    Basirat, Farzad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Sharma, Prabhakar
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Fagerlund, Fritjof
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Niemi, Auli
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Experimental and modeling investigation of CO2 flow and transport in a coupled domain of porous media and free flow2015In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 42, p. 461-470Article in journal (Refereed)
    Abstract [en]

    A solid understanding of the transport mechanisms of gaseous CO2 near the land surface is necessary for developing reliable monitoring techniques and predictive models for possible CO2 leakage from deep underground storage. The objective of this work has been to develop an experimental method along with a simulation model for gaseous CO2 flow and transport in a system including both the porous media and the free air space above it. The experimental system consisted of a two-dimensional bench scale rectangular sandbox containing homogenous sand with an open space of still air above it. Gaseous CO2 was injected in different modes and the CO2 breakthrough was measured on specified ports in the system by using CO2 concentration sensors. A numerical model combining the gas flow in the porous medium and the free flow region was developed and used to model the experimental data. In this quest, the Discontinuous One-Domain approach was selected for modeling transport between the free flow and porous regions. The observed and simulated CO2 breakthrough curves both in the dried sand and in the free flow matched very well in the case of uniform injection and satisfactorily even in the case of point injection. Consequently, it seems that the model reasonably matches the observed data in the cases where the boundary condition is well defined. In summary, our results show that the developed experimental setup provides capability to study gaseous CO2 flow and transport in a coupled porous medium - free flow system and that our modeling approach is able to predict the flow and transport in this system with good accuracy.

  • 38.
    Basirat, Farzad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Yang, Zhibing
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China..
    Bensabat, Jacob
    Environm & Water Resources Engn EWRE Ltd, Haifa, Israel..
    Levchenko, Stanislav
    Environm & Water Resources Engn EWRE Ltd, Haifa, Israel..
    Pan, Lehua
    Lawrence Berkeley Natl Lab LBNL, Energy Geosci Div, Berkeley, CA USA..
    Niemi, Auli
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Characterization of CO2 self-release during Heletz Residual Trapping Experiment I (RTE I) using a coupled wellbore-reservoir simulator2020In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 102, article id 103162Article in journal (Refereed)
    Abstract [en]

    In order to quantify CO2 residual trapping in situ, two dedicated single-well push-pull experiments have been carried out at the Heletz, Israel pilot CO2 injection site. Field data from some parts of these experiments suggests the important effect of the hydrodynamic behavior in the injection-withdrawal well. In the present work a model capturing the CO2 transport and trapping behavior during Heletz Residual Trapping Experiment I is developed, with a special focus on coupled wellbore-reservoir flow. The simulation is carried out with the numerical simulator T2Well/ECO2N (Pan et al. 2011) which considers the wellbore-reservoir coupling. Of particular interest is to accurately model the period when the well is open to the atmosphere and self-producing CO2 and water in a geyser-like manner. It is also of interest to identify what conditions are causing the oscillating pressure-temperature behavior and the associated periodic gas-liquid releases, as well as to determine the amount of gas lost from the reservoir during this period. The results suggest that the behavior is due to cyclical CO2 exsolution from the aqueous phase along with a reduction of mobility of both CO2 and brine in the near wellbore-reservoir area, the latter being due to a zone of dispersed CO2 bubbles near the wellbore. This behavior could be successfully captured with a new set of relative permeability functions developed earlier for CO2 exsolution in laboratory experiments (Zuo et al., 2013).

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  • 39.
    Bastholm, Caroline
    et al.
    Högskolan Dalarna, Energiteknik.
    Fiedler, Frank
    Högskolan Dalarna, Energiteknik.
    Techno-economic study of the impact of blackouts on the viability of connecting an off-grid PV-diesel hybrid system in Tanzania to the national power grid2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 171, no 1, p. 647-658Article in journal (Refereed)
    Abstract [en]

    National electrification plans for many countries with a low level of electrification promote the implementation of centralized and decentralized electrification in parallel. This paper explores different ways of utilizing an established off-grid PV-diesel hybrid system when the national grid becomes available. This is a rather unique starting point within the otherwise well-explored area of rural electrification. With particular focus on the impact of blackouts in the national grid, we evaluate the economic viability of some alternatives: to continue to use the off-grid micro-grid, to connect the existing micro-grid with or without battery backup to the national grid, or to use the national grid only. Our simulation results in HOMER demonstrate that with a grid without blackouts, there are few benefits to maintain the existing system. Low grid-connection fees, low tariffs and low revenues from selling excess electricity to the grid contribute to this result despite the fact that the system does not carry any investment costs. With a grid with blackouts, it is beneficial to maintain the system. The extent of blackouts and the load on the system determine which system configuration is most feasible. The results make clear the importance of taking blackouts in the national grid into consideration when possible system configurations are being evaluated. This is rarely quantified in studies comparing different electrification alternatives, but deserves more attention.

  • 40.
    Baudoin, Antoine
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Cooling Strategies for Wave Power Conversion Systems2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Division for Electricity of Uppsala University is developing a wave power concept. The energy of the ocean waves is harvested with wave energy converters, consisting of one buoy and one linear generator. The units are connected in a submerged substation. The mechanical design is kept as simple as possible to ensure reliability.

    The submerged substation includes power electronics and different types of electrical power components. Due to the high cost of maintenance operations at sea, the reliability of electrical systems for offshore renewable energy is a major issue in the pursuit of making the electricity production economically viable. Therefore, proper thermal management is essential to avoid the components being damaged by excessive temperature increases.

    The chosen cooling strategy is fully passive, and includes no fans. It has been applied in the second substation prototype with curved heatsinks mounted on the inner wall of the pressurized vessel. This strategy has been evaluated with a thermal model for the completed substation. First of all, 3D-CFD models were implemented for selected components of the electrical conversion system. The results from these submodels were used to build a lumped parameter model at the system level.

    The comprehensive thermal study of the substation indicates that the rated power in the present configuration is around 170 kW. The critical components were identified. The transformers and the inverters are the limiting components for high DC-voltage and low DC-voltage respectively. The DC-voltage—an important parameter in the control strategy for the WEC—was shown to have the most significant effect on the temperature limitation.

    As power diodes are the first step of conversion, they are subject to large power fluctuations. Therefore, we studied thermal cycling for these components. The results indicated that the junction undergoes repeated temperature cycles, where the amplitude increased with the square root of the absorbed power.

    Finally, an array of generic heat sources was optimized. We designed an experimental setup to investigate conjugate natural convection on a vertical plate with flush-mounted heat sources. The influence of the heaters distribution was evaluated for different dissipated powers. Measurements were used for validation of a CFD model. We proposed optimal distributions for up to 36 heat sources. The cooling capacity was maximized while the used area was minimized.

    List of papers
    1. Optimized distribution of a large number of heat sources cooled by conjugate turbulent natural convection
    Open this publication in new window or tab >>Optimized distribution of a large number of heat sources cooled by conjugate turbulent natural convection
    (English)In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606Article in journal (Refereed) Submitted
    National Category
    Energy Engineering
    Identifiers
    urn:nbn:se:uu:diva-307944 (URN)
    Available from: 2016-11-24 Created: 2016-11-23 Last updated: 2017-11-29
    2. Temperature and velocity measurements in a buoyant flow induced by a heat source array on a vertical plate
    Open this publication in new window or tab >>Temperature and velocity measurements in a buoyant flow induced by a heat source array on a vertical plate
    2017 (English)In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 88, p. 234-245Article in journal (Refereed) Published
    Abstract [en]

    Heat source arrays are common in engineering applications. Natural convection is a reliable and silent cooling strategy. Therefore, an array of flush-mounted heat sources has been studied under conjugate conduction and natural convection condition. This studies was performed for a system with relatively large dimensions, typical for power electronics, and a modified Rayleigh number up to 2 . 10(10) A modular set of heaters was designed to vary the distribution of heat sources on the plate and investigate the influence of the spacing. Velocity and temperature were measured in the convective flow with particle image velocimetry and micro-thermocouple. The velocity field was analyzed with proper orthogonal decomposition. The first instabilities of the convective flows were described. The results gave abetter understanding of the heat transfers in these configurations and are valuable for model validation.

    National Category
    Energy Engineering Fluid Mechanics and Acoustics
    Identifiers
    urn:nbn:se:uu:diva-307943 (URN)10.1016/j.expthermflusci.2017.06.002 (DOI)000409285600023 ()
    Funder
    SweGRIDS - Swedish Centre for Smart Grids and Energy StorageStandUp
    Available from: 2016-11-24 Created: 2016-11-23 Last updated: 2017-12-01Bibliographically approved
    3. Experimental Optimization of Passive Cooling of a Heat Source Array Flush-Mounted on a Vertical Plate
    Open this publication in new window or tab >>Experimental Optimization of Passive Cooling of a Heat Source Array Flush-Mounted on a Vertical Plate
    2016 (English)In: Energies, E-ISSN 1996-1073, Vol. 9, no 11, article id 912Article in journal (Refereed) Published
    Abstract [en]

    Heat sources, such as power electronics for offshore power, could be cooled passively—mainly by conduction and natural convection. The obvious advantage of this strategy is its high reliability. However, it must be implemented in an efficient manner (i.e., the area needs to be kept low to limit the construction costs). In this study, the placement of multiple heat sources mounted on a vertical plate was studied experimentally for optimization purposes. We chose a regular distribution, as this is likely to be the preferred choice in the construction process. We found that optimal spacing can be determined for a targeted source density by tuning the vertical and horizontal spacing between the heat sources. The optimal aspect ratio was estimated to be around two.

    Keywords
    discrete heat sources, source array, natural convection, optimization
    National Category
    Energy Engineering
    Identifiers
    urn:nbn:se:uu:diva-307831 (URN)10.3390/en9110912 (DOI)000388580000054 ()
    Funder
    SweGRIDS - Swedish Centre for Smart Grids and Energy StorageStandUp
    Available from: 2016-11-22 Created: 2016-11-22 Last updated: 2023-08-28Bibliographically approved
    4. Assessment of Thermal Cycling in a Rectifier For WavePower Generation
    Open this publication in new window or tab >>Assessment of Thermal Cycling in a Rectifier For WavePower Generation
    2016 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    Natural convection allows for passive cooling which isused in many engineering applications. Placing dissipatingcomponents on a common vertical heatsink can be opti-mized to give the best possible cooling capacity. In thisstudy, a numerical model for three-dimensional conjugatedconvective and conductive heat transfer was used to evalu-ate the distribution of up to 36 ush-mounted rectangularheaters. The temperature proles and the heat uxes werecompared with experimental data for validation. The dis-sipated power was set as an input parameter and the op-timal distribution was selected as the one with the lowesttemperature elevation. Two dierent heuristicsa geo-metric parameter and an articial neural networkwereproposed and evaluated as alternatives to heavy CFD cal-culations.

    National Category
    Energy Engineering
    Identifiers
    urn:nbn:se:uu:diva-307945 (URN)
    Conference
    IET Renewable Power Generation
    Available from: 2016-11-23 Created: 2016-11-23 Last updated: 2016-11-25
    5. Thermal Rating of a Submerged Substation for Wave Power
    Open this publication in new window or tab >>Thermal Rating of a Submerged Substation for Wave Power
    2016 (English)In: IEEE Transactions on Sustainable Energy, ISSN 1949-3029, E-ISSN 1949-3037, Vol. 7, no 1, p. 436-445Article in journal (Refereed) Published
    Abstract [en]

    The costs of offshore maintenance operations put high reliability-requirements on offshore equipment for ocean energy, especially on submerged ones. Thermal management is thus essential in the design of the prototypes of a marine substation, developed at Uppsala University, for grid interface of wave power parks. The cooling system itself should be efficient as well as reliable. Therefore, the feasibility of a completely passive cooling strategy was evaluated. The studied substation includes various power components, which dissipate heat and are installed in one pressurized vessel. Thermal cross-coupling was investigated with 3-D submodels and a thermal network model. An electric circuit was coupled to determine the rated power of the substation. The results depend mainly on the dc-voltage, the seawater temperature, and the thermal contact between the components and the hull.

    Keywords
    Computational fluid dynamics;Computational modeling;Heat transfer;Heating;Integrated circuit modeling;Substations;Wave power;Computational fluid dynamic (CFD);natural convection;ocean energy;passive cooling;power electronics;thermal management;wave power
    National Category
    Engineering and Technology Ocean and River Engineering
    Identifiers
    urn:nbn:se:uu:diva-267226 (URN)10.1109/TSTE.2015.2425045 (DOI)000367340700044 ()
    Funder
    SweGRIDS - Swedish Centre for Smart Grids and Energy StorageStandUpSwedish Energy Agency
    Available from: 2015-11-19 Created: 2015-11-19 Last updated: 2017-12-01Bibliographically approved
    6. Thermal modelling of a passively cooled inverter for wave power
    Open this publication in new window or tab >>Thermal modelling of a passively cooled inverter for wave power
    2015 (English)In: IET Renewable Power Generation, ISSN 1752-1416, E-ISSN 1752-1424, Vol. 9, no 4, p. 389-395Article in journal (Refereed) Published
    Abstract [en]

    Owing to very costly maintenance operations, the reliability of electrical systems for offshore renewable energy is a major issue to make electricity production economical. Therefore proper thermal management is essential in order to avoid the components from being damaged by excessive temperature increase. Both analytic and computational fluid dynamics (CFD) models were implemented to assess the temperature increase in the inverter installed in a submerged substation and during working conditions. It was shown that this inverter could transmit a total power of up to about 35 kW. This limit is dependent on a certain distance between the modules and a perfect thermal contact with the hull. The influence of several of such parameters as well as the efficiency of passive cooling were studied.

    Keywords
    wave power plants, invertors, substations, cooling, thermal modelling, passively cooled inverter, wave power, CFD models, submerged substation, thermal contact, passive cooling
    National Category
    Environmental Engineering
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-252981 (URN)10.1049/iet-rpg.2014.0112 (DOI)000352809300011 ()
    Available from: 2015-05-19 Created: 2015-05-18 Last updated: 2017-12-04Bibliographically approved
    7. Wave Energy Research at Uppsala University and The Lysekil Research Site, Sweden: A Status Update
    Open this publication in new window or tab >>Wave Energy Research at Uppsala University and The Lysekil Research Site, Sweden: A Status Update
    Show others...
    2015 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper provides a summarized status update ofthe Lysekil wave power project. The Lysekil project is coordinatedby the Div. of Electricity, Uppsala University since 2002, with theobjective to develop full-scale wave power converters (WEC). Theconcept is based on a linear synchronous generator (anchored tothe seabed) driven by a heaving point absorber. This WEC has nogearbox or other mechanical or hydraulic conversion systems,resulting in a simpler and robust power plant. Since 2006, 12 suchWECs have been build and tested at the research site located atthe west coast of Sweden. The last update includes a new andextended project permit, deployment of a new marine substation,tests of several concepts of heaving buoys, grid connection,improved measuring station, improved modelling of wave powerfarms, implementation of remote operated vehicles forunderwater cable connection, and comprehensive environmentalmonitoring studies.

    Keywords
    Wave energy, point absorber, experiments, arrays, generators, ROVs
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Ocean and River Engineering
    Identifiers
    urn:nbn:se:uu:diva-265218 (URN)
    Conference
    Proceedings of the 11th European Wave and Tidal Energy Conference. Nantes, France, September 2015
    Available from: 2015-10-26 Created: 2015-10-26 Last updated: 2019-08-19Bibliographically approved
    8. Measurement System For Wave Energy Converter - Design And Implementation
    Open this publication in new window or tab >>Measurement System For Wave Energy Converter - Design And Implementation
    2014 (English)In: 33Rd International Conference On Ocean, Offshore And Arctic Engineering, 2014, Vol 9A: Ocean Renewable Energy, AMER SOC MECHANICAL ENGINEERS , 2014Conference paper, Published paper (Refereed)
    Abstract [en]

    A Wave Energy Converter (WEC) measurement system has been constructed and installed with the purpose to measure, log and evaluate the WEC's performance during operation at sea. The WEC is to be deployed at Uppsala University's wave power research site in Lysekil on the west coast of Sweden. In designing such a system the key research objectives has been (1) to study the risk of overheating due to high currents in the stator windings, (2) to evaluate how the WEC's outer structure withstands drag and bending forces from the buoy line and (3) to construct a detection system which indicates if water leaks into the generator. The measurement system was designed to collect data essential to study these key objectives. Transducers were used to measure: buoy line force, translator position, phase currents, bending and tensile strain on the generator hull, water level inside generator and the temperature at multiple places inside the generator. The measurement system has been installed and calibrated in the WEC. Furthermore, the design has been evaluated in lab experiments in order to verify the function and accuracy of the different measurements. This paper presents the underlying research objectives for developing the WEC generator measurement system, together with a description of the technical implementation.

    Place, publisher, year, edition, pages
    AMER SOC MECHANICAL ENGINEERS, 2014
    National Category
    Energy Systems Ocean and River Engineering
    Identifiers
    urn:nbn:se:uu:diva-272118 (URN)000363499000005 ()978-0-7918-4553-0 (ISBN)
    Conference
    33Rd International Conference On Ocean, Offshore And Arctic Engineering
    Note

    Första författaren har bytt efternamn till Ulvgård

    Available from: 2016-01-12 Created: 2016-01-12 Last updated: 2017-09-28
    9. Status Update of the Wave Energy Research at Uppsala University
    Open this publication in new window or tab >>Status Update of the Wave Energy Research at Uppsala University
    Show others...
    2013 (English)Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Aalborg, Denmark: , 2013
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-212701 (URN)
    Conference
    10th European Wave and Tidal Conference (EWTEC)
    Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2017-12-07
    10. Temperature Study in a Marine Substation for Wave Power
    Open this publication in new window or tab >>Temperature Study in a Marine Substation for Wave Power
    Show others...
    2012 (English)In: International Journal of Mechanic Systems Engineering, ISSN 2225-7403, Vol. 2, no 4, p. 126-131Article in journal (Refereed) Published
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-190091 (URN)
    Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2017-01-18Bibliographically approved
    11. Marine substation design for grid-connection of a research wave power plant on the Swedish West coast
    Open this publication in new window or tab >>Marine substation design for grid-connection of a research wave power plant on the Swedish West coast
    2013 (English)Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Aalborg, Denmark: , 2013
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-212687 (URN)
    Conference
    10th European Wave and Tidal Conference (EWTEC)
    Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2016-11-24
    12. Lysekil Research Site, Sweden: A status update
    Open this publication in new window or tab >>Lysekil Research Site, Sweden: A status update
    Show others...
    2011 (English)In: 9th European Wave and Tidal Energy Conference, Southampton, UK, 2011, 2011Conference paper, Published paper (Refereed)
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-160039 (URN)
    Conference
    9th European Wave and Tidal Energy Conference, Southampton, UK, 5-9 September 2011
    Available from: 2011-10-13 Created: 2011-10-13 Last updated: 2017-01-25
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  • 41.
    Baudoin, Antoine
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Boström, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Saury, Didier
    Assessment of Thermal Cycling in a Rectifier For WavePower Generation2016Conference paper (Refereed)
    Abstract [en]

    Natural convection allows for passive cooling which isused in many engineering applications. Placing dissipatingcomponents on a common vertical heatsink can be opti-mized to give the best possible cooling capacity. In thisstudy, a numerical model for three-dimensional conjugatedconvective and conductive heat transfer was used to evalu-ate the distribution of up to 36 ush-mounted rectangularheaters. The temperature proles and the heat uxes werecompared with experimental data for validation. The dis-sipated power was set as an input parameter and the op-timal distribution was selected as the one with the lowesttemperature elevation. Two dierent heuristicsa geo-metric parameter and an articial neural networkwereproposed and evaluated as alternatives to heavy CFD cal-culations.

  • 42.
    Baudoin, Antoine
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Saury, Didier
    Univ Poitiers, ENSMA, CNRS, Inst PPRIME, BP 40109, F-86961 Futuroscope, France.
    Temperature and velocity measurements in a buoyant flow induced by a heat source array on a vertical plate2017In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 88, p. 234-245Article in journal (Refereed)
    Abstract [en]

    Heat source arrays are common in engineering applications. Natural convection is a reliable and silent cooling strategy. Therefore, an array of flush-mounted heat sources has been studied under conjugate conduction and natural convection condition. This studies was performed for a system with relatively large dimensions, typical for power electronics, and a modified Rayleigh number up to 2 . 10(10) A modular set of heaters was designed to vary the distribution of heat sources on the plate and investigate the influence of the spacing. Velocity and temperature were measured in the convective flow with particle image velocimetry and micro-thermocouple. The velocity field was analyzed with proper orthogonal decomposition. The first instabilities of the convective flows were described. The results gave abetter understanding of the heat transfers in these configurations and are valuable for model validation.

  • 43.
    Baudoin, Antoine
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Saury, Didier
    Boström, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Optimized distribution of a large number of heat sources cooled by conjugate turbulent natural convectionIn: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606Article in journal (Refereed)
  • 44.
    Baudoin, Antoine
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Saury, Didier
    Univ Poitiers, ENSMA, CNRS, Inst PPRIME, BP 40109, F-86961 Futuroscope, Chassencuil, France.
    Zhu, Bo
    Univ Poitiers, ENSMA, CNRS, Inst PPRIME, BP 40109, F-86961 Futuroscope, Chassencuil, France.
    Boström, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Experimental Optimization of Passive Cooling of a Heat Source Array Flush-Mounted on a Vertical Plate2016In: Energies, E-ISSN 1996-1073, Vol. 9, no 11, article id 912Article in journal (Refereed)
    Abstract [en]

    Heat sources, such as power electronics for offshore power, could be cooled passively—mainly by conduction and natural convection. The obvious advantage of this strategy is its high reliability. However, it must be implemented in an efficient manner (i.e., the area needs to be kept low to limit the construction costs). In this study, the placement of multiple heat sources mounted on a vertical plate was studied experimentally for optimization purposes. We chose a regular distribution, as this is likely to be the preferred choice in the construction process. We found that optimal spacing can be determined for a targeted source density by tuning the vertical and horizontal spacing between the heat sources. The optimal aspect ratio was estimated to be around two.

    Download full text (pdf)
    fulltext
  • 45.
    Bee, Elena
    et al.
    Univ Trento, Dept Civil Environm & Mech Engn, Trento, Italy.
    Prada, Alessandro
    Univ Trento, Dept Civil Environm & Mech Engn, Trento, Italy.
    Baggio, Paolo
    Univ Trento, Dept Civil Environm & Mech Engn, Trento, Italy.
    Psimopoulos, Emmanouil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Dalarna Univ, Energy Technol, Borlange, Sweden.
    Air-source heat pump and photovoltaic systems for residential heating and cooling: Potential of self-consumption in different European climates2019In: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, Vol. 12, no 3, p. 453-463Article in journal (Refereed)
    Abstract [en]

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

  • 46.
    Benesperi, Iacopo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, S-75120 Uppsala, Sweden.
    Michaels, Hannes
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Freitag, Marina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    The researcher's guide to solid-state dye-sensitized solar cells2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 44, p. 11903-11942Article, review/survey (Refereed)
    Abstract [en]

    In order to sustainably support its ever-increasing energy demand, the human society will have to harvest renewable energy wherever and whenever possible. When converting light to electricity, silicon solar cells are the technology of choice to harvest direct sunlight due to their high performance and continuously dropping price. For diffused light and indoor applications, however, silicon is not the material of choice. To power the next gizmo in your smart home, dye-sensitized solar cells (DSCs) are a viable alternative. Made from inexpensive, earth-abundant, and non-toxic materials, DSCs perform best at low light intensity. So far, issues such as leakage of the liquid electrolyte and its corrosive nature have limited the commercialization of this technology. To overcome these limitations, solid-state DSCs (ssDSCs) - in which the liquid electrolyte is replaced by a solid material - have been developed. For many years their efficiencies have been poor, preventing them from being widely employed. In the past six years, however, research efforts have led them to rival with their liquid counterparts. Here, we will review recent advancements in the field of ssDSCs. Every device component will be acknowledged, from metal oxides and new dyes to novel hole transporters, dopants, counter-electrodes and device architectures. After reviewing materials, long-term stability of devices will be addressed, finally giving an insight into the future that awaits this exciting technology.

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  • 47.
    Berggren, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Study of auxiliary power systemsfor offshore wind turbines: an extended analysis of a diesel gen-setsolution2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Until today the offshore wind power has grown in a steady pace and many new wind farms are being constructed around the globe. An important factor that is investigated today in the industry are the security of power supply to the equipment needed for controlling the offshore system during emergency situations. When a offshore wind farm is disconnected from the external grid and an emergency case occur the wind turbine generators lose their ability to transfer power and they are forced to be taken out of operation. As there are a number of loads in the wind turbines (navigation lights, sensor- and communication-apparatus, ventilation- and heating equipment etc.) they have a load demand which must be supplied in emergency mode. The German Transmission System operator (TSO) TenneT GmbH has set a requirement that the wind turbines is to be supplied by an auxiliary power supply (APS) in 12 hours and therefore there is need for a long-term auxiliary power supply system. This master thesis was assigned to investigate the most feasible APS-system. From the study of a number of different APS's one concept was chosen. This was the diesel gen-set solution placed on an offshore substation at sea. The system was modeled in the software DIgSILENT PowerFactory where a load flow analysis validated the calculated data and a study of the impact of  transients in the system was performed.

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    MasterThesis_JoakimBerggren_8803220451
  • 48.
    Bergvall, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Cost Comparison of Repowering Alternatives for Offshore Wind Farms2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis is to evaluate different repowering alternatives from the viewpoint of increasing power production from existing offshore wind farms (OWF), as some of the first commissioned OWFs are approaching the end of their expected lifetime. The thesis presents a literature review of components and financial aspects that are of importance for repowering of OWFs. In the literature review, risks and uncertainties regarding repowering are also lifted and analysed. The thesis contains a case study on Horns Rev 1 OWF, where three different repowering scenarios are evaluated by technical and financial performance, aiming to compare the cost of repowering alternatives. The design of the case study is based around previous studies of offshore repowering having focused mainly on achieving the lowest possible levelized cost of energy (LCoE) and highest possible capacity factor, often resulting in suggested repowering utilizing smaller wind turbines than the existing ones.

    In order to evaluate the financial viability of repowering alternatives, the software RETScreen Expert was used to estimate the annual energy production (AEP) after losses and calculate the net present value (NPV) and LCoE for lifetime extension and full repowering utilizing different capacity wind turbines. Input values from the literature as well as real wind resource measurements from the site was utilized to achieve as accurate results as possible.

    The result of the case study shows that repowering of OWFs have the possibility of providing a very strong business case with all scenarios resulting in a positive NPV as well as lower LCoE than the benchmarked electricity production price. Although the initial investment cost of the different repowering alternatives presented in this thesis still are uncertain to some extent, due to the lack of reliable costs for repowering alternatives, this thesis provides a base for further research regarding the repowering of OWFs.

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    Cost Comparison of Repowering Alternatives for Offshore Wind Farms
  • 49.
    Bhowmik, Arghya
    et al.
    Dept Energy Convers & Storage, Bldg 301, DK-2800 Lyngby, Denmark..
    Berecibar, Maitane
    Vrije Univ Brussel, Battery Innovat Ctr, MOBI Res Grp, Pl Laan 2, B-1050 Brussels, Belgium..
    Casas-Cabanas, Montse
    Basque Res & Technol Alliance BRTA, Ctr Cooperat Res Alternat Energies CIC EnergiGUNE, Parque Tecnol Alava,Albert Einstein 48, Vitoria 01510, Spain.;Ikerbasque, Basque Fdn Sci, Maria Diaz de Haro 3, Bilbao 48013, Spain.;Alistore ERI, Amiens, France..
    Csanyi, Gabor
    Univ Cambridge, Engn Lab, Trumpington St, Cambridge CB2 1PZ, England..
    Dominko, Robert
    Alistore ERI, Amiens, France.;Natl Inst Chem, Hajdrihova 19, Ljubljana 1000, Slovenia.;Univ Ljubljana, FKKT, Vecna Pot 113, Ljubljana 1000, Slovenia..
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Palacin, M. Rosa
    Alistore ERI, Amiens, France.;CSIC, Inst Ciencia Mat Barcelona, ICMAB, Campus UAB, Bellaterra 08193, Catalonia, Spain..
    Stein, Helge S.
    Helmholtz Inst UIm, Helmholtzstr 11, D-89081 Ulm, Germany.;Karlsruhe Inst Technol, Inst Phys Chem, Fritz Haber Weg 2, D-76131 Karlsruhe, Germany..
    Vegge, Tejs
    Dept Energy Convers & Storage, Bldg 301, DK-2800 Lyngby, Denmark.;Alistore ERI, Amiens, France..
    Implications of the BATTERY 2030+ AI-Assisted Toolkit on Future Low-TRL Battery Discoveries and Chemistries2022In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 12, no 17, article id 2102698Article, review/survey (Refereed)
    Abstract [en]

    BATTERY 2030+ targets the development of a chemistry neutral platform for accelerating the development of new sustainable high-performance batteries. Here, a description is given of how the AI-assisted toolkits and methodologies developed in BATTERY 2030+ can be transferred and applied to representative examples of future battery chemistries, materials, and concepts. This perspective highlights some of the main scientific and technological challenges facing emerging low-technology readiness level (TRL) battery chemistries and concepts, and specifically how the AI-assisted toolkit developed within BIG-MAP and other BATTERY 2030+ projects can be applied to resolve these. The methodological perspectives and challenges in areas like predictive long time- and length-scale simulations of multi-species systems, dynamic processes at battery interfaces, deep learned multi-scaling and explainable AI, as well as AI-assisted materials characterization, self-driving labs, closed-loop optimization, and AI for advanced sensing and self-healing are introduced. A description is given of tools and modules can be transferred to be applied to a select set of emerging low-TRL battery chemistries and concepts covering multivalent anodes, metal-sulfur/oxygen systems, non-crystalline, nano-structured and disordered systems, organic battery materials, and bulk vs. interface-limited batteries.

    Download full text (pdf)
    fulltext
  • 50.
    Bin Asad, S M Sayeed
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University.
    ANALYZING WIND MEASUREMENTS FROM THE MET MAST, SODAR & LIDAR2022Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wind energy is rapidly expanding worldwide, and it is common practice to maximize production by selecting sites with higher wind potential. To perform critical operations such as wind flow modeling, wind turbine micro placement, annual energy yield calculation, and cost of energy estimation, a thorough understanding of a site's wind resource is required. The present study examines data from three independent wind measurement systems to see how measured data depends on the choice of the measurement system and how this might forecast the wind resource and, consequently, the energy output of a potential wind farm. 

    The present analysis uses three measurement units, one meteorological mast (met mast), and ground-based AQ510 Sound Detection And Ranging (SoDAR) & SoDAR and ZX 300 Light Detection And Ranging (LiDAR) devices to capture wind data for nearly a year. This study describes the operating concept of remote sensing devices such as AQ510 SoDAR and ZX 300 LiDAR, the linear regression relationship between wind speed measured on the Met Mast versus SoDAR, Met Mast versus LiDAR, and SoDAR versus LiDAR. Additionally, an understanding of stratification for this potential wind farm’s site is explored for specific days during spring, summer, and winter. 

    The results of the intercomparison study among Met Mast, SoDAR & LiDAR show quite a good relationship between the different measurement systems, being the correlation coefficient between the mast and the LiDAR measurements being slightly larger than between the mast and the SoDAR measurements. Comparison during the stability and instability regimes show a larger difference in some cases. Python and MS Excel are used to build data filtering procedures, the Richardson number, and comparison computations. 

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