| 1. |
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| 2. |
- Gustafsson, Marcus, 1987-, et al.
(författare)
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Techno-economic analysis of energy renovation measures for a district heated multi-family house
- 2016
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 177, s. 108-116
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Tidskriftsartikel (refereegranskat)abstract
- Renovation of existing buildings is important in the work toward increased energy efficiency and reduced environmental impact. The present paper treats energy renovation measures for a Swedish district heated multi-family house, evaluated through dynamic simulation. Insulation of roof and façade, better insulating windows and flow-reducing water taps, in combination with different HVAC systems for recovery of heat from exhaust air, were assessed in terms of life cycle cost, discounted payback period, primary energy consumption, CO2 emissions and non-renewable energy consumption. The HVAC systems were based on the existing district heating substation and included mechanical ventilation with heat recovery and different configurations of exhaust air heat pump.Compared to a renovation without energy saving measures, the combination of new windows, insulation, flow-reducing taps and an exhaust air a heat pump gave up to 24% lower life cycle cost. Adding insulation on roof and façade, the primary energy consumption was reduced by up to 58%, CO2 emissions up to 65% and non-renewable energy consumption up to 56%. Ventilation with heat recovery also reduced the environmental impact but was not economically profitable in the studied cases. With a margin perspective on electricity consumption, the environmental impact of installing heat pumps or air heat recovery in district heated houses is increased. Low-temperature heating improved the seasonal performance factor of the heat pump by up to 11% and reduced the environmental impact.
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| 3. |
- Salehin, Sayedus, et al.
(författare)
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Designing of an emergency energy module for relief and refugee camp situations : Case study for a refugee camp in Chad-Sudan border
- 2011
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Ingår i: 2011 World Congress on Sustainable Technologies. - 9780956426345 ; , s. 9-14
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Konferensbidrag (refereegranskat)abstract
- Each year thousands of people get displaced and are forced to live in refugee camps or relief camps because of man-made or natural disasters. These people often lack basic needs such as clean water, lighting, cooling, etc. and many times these camps exist for more than 7-8 years. This paper aims at conceptualizing an Emergency Energy Module (EEM) which provides electrical energy to satisfy the basic needs and that can be deployed as an emergency response in a self-sufficient, self-contained, and highly mobile fashion, to support the energy demand of a refugee or a relief camp and the aid workers for long term. As a case study, a refugee camp near Chad-Sudan border has been investigated. As a preliminary study, electrical demand was determined for the camp. Further, locally available energy resources were studied and assessed based on key design criteria and the technologies were selected to meet the demand. Polycrystalline Solar PV panels, micro wind turbine and biogas polyethylene digester and diesel generator were chosen as the technology to harness selected energy resources. HOMER Software has been used for optimization and techno-economic analysis of the energy system. The selected solution has been, then, analyzed from an operational point of view.
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| 4. |
- Okda, Sherif, et al.
(författare)
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Testing of the Aerodynamic Characteristics of an Inflatable Airfoil Section
- 2020
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Ingår i: Journal of Aerospace Engineering. - 1943-5525 .- 0893-1321. ; 33:5
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Tidskriftsartikel (refereegranskat)abstract
- Inflatable structures are characterized by being light and easy to manufacture and deploy. Hence, they find many applications in aerospace and aeronautical engineering. In this paper, an inflatable segment with a The National Advisory Committee for Aeronautics (NACA) 0021 airfoil cross-section is designed, fabricated, and tested. The geometrical accuracy of the manufactured inflatable segment is measured using laser scanning. Measurements show that the average normalized error of the chord length and thickness are 2.97% and 0.554%, respectively. The aerodynamic behavior of the inflatable segment is then tested in a wind tunnel at different wind speeds and angles of attack. Lift forces are measured using a six-component balance, while the drag forces are calculated from the wake measurements. The lift and drag coefficients of the inflatable section are compared to those of a standard NACA 0021 airfoil. Finally, flow visualization is examined at different angles of attack using two methods: smoke and tufts. Both methods show that flow separation starts at 15° and full stall occurs at 25°. Results indicate that inflatables can find more applications in the design and construction of aerodynamic structures, such as wings.
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| 5. |
- Chen, B., et al.
(författare)
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Pathways for sustainable energy transition
- 2019
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 228, s. 1564-1571
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Tidskriftsartikel (refereegranskat)abstract
- Energy transitions are ongoing processes all over the world. While sustainable solutions are envisioned for the future, many societies are still under high-carbon and high-pollution energy regime borne by fossil fuels. How to design pathways towards sustainable energy transition has attracted worldwide concerns. Understanding the possible transition pathways of the energy system requires the integration of new energy technologies, environmental sciences, economics and management. This Special Issue of Journal of Cleaner Production targets to collect the latest research results on sustainable energy systems, discover innovative avenues and inspiring models and share knowledge on energy system modelling and management. In this paper, we identify 4 themes on sustainable energy transition pathways including: (1)Sustainable energy economics and management; (2)Renewable energy generation and consumption; (3)Environmental impacts of energy systems; and (4)Electric vehicle and energy storage. Theories, technologies, innovative models, and successful experiences are discussed accordingly. It is suggested that creative, robust and audacious strategies in governance, management and education are needed to boost sustainable energy transition across various scales and sectors.
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| 6. |
- von Platten, Jenny, et al.
(författare)
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Renovating on unequal premises : A normative framework for a just renovation wave in swedish multifamily housing
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:19
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Tidskriftsartikel (refereegranskat)abstract
- While the energy transition of the EU housing stock is now being intensified with the launch of the Renovation Wave, economic inequalities are increasing in many OECD countries, which has effects on housing-related inequalities and the demand of affordable housing. The Renovation Wave is thus an opportunity to improve housing quality for low-income households, but also entails risks for increased rents. In Sweden, the standard of housing is relatively high and energy poverty in multifamily housing is rare, meaning that there are limited social benefits to be achieved from extensive energy retrofitting; moreover, Sweden lacks a social housing sector, which limits protection of the worst-off residents. This paper thus explores whether the limited social benefits of the Renovation Wave weigh up against the risks that it entails for the worst-off in the Swedish context. This is done within a normative framework for just energy transitioning that is developed within the context of the Renovation Wave and increasing economic inequalities, consisting of four ordered principles: (1) The equal treatment principle; (2) The priority principle; (3) The efficiency principle; and (4) The principle of procedural fairness. Analysis showed that to be considered just according to our framework, the Swedish energy transition of housing should, in contradistinction to what is suggested in the Renovation Wave, limit the imposition of extensive energy retrofitting in low-income areas. Finally, having identified a mismatch between the most effective approaches in terms of energy savings and the most acceptable approaches in terms of social justice, we offer policy recommendations on how to bridge this mismatch in a Swedish context. © 2021 by the authors.
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| 7. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Forskningsöversikt (refereegranskat)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 8. |
- Herre, Lars, 1990-, et al.
(författare)
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Simplified model of integrated paper mill for optimal bidding in energy and reserve markets
- 2020
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- Due to the increased use of variable renewable energy sources, more capacity for reserves is required. Non-generating resources such as large industrial consumers can arbitrage energy prices and provide reserve capacity by exploiting the inherent flexibility in selected industrial processes. A large enough industrial consumer can capitalize on this flexibility through optimized bidding in electricity markets. In this work, the day-ahead cost minimization of a risk-averse pulp and paper mill is formulated as a two-stage stochastic problem, considering thermodynamic and electrical constraints. The bids in the energy and reserve markets are jointly optimized subject to price uncertainty as well as uncertainty of frequency realization. The results of a case study in Sweden display a significant economic benefit in exploiting the flexibility of integrated pulp and paper mills with electric boilers. The expected cost of the pulp and paper mill resulting from different strategies are compared and the risk-aversion of the pulp and paper mill is investigated. Reserve offers are mainly facilitated by fast-acting electric boilers and supported by flexibility in the steam network. We show that reserve offers can significantly improve the profitability of the pulp and paper mill.
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| 9. |
- Lv, Zhihan, Dr. 1984-, et al.
(författare)
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Towards carbon Neutrality : Prediction of wave energy based on improved GRU in Maritime transportation
- 2023
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 331
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Tidskriftsartikel (refereegranskat)abstract
- Efficient use of renewable energy is one of the critical measures to achieve carbon neutrality. Countries have introduced policies to put carbon neutrality on the agenda to achieve relatively zero emissions of greenhouse gases and to cope with the crisis brought about by global warming. This work analyzes the wave energy with high energy density and wide distribution based on understanding of various renewable energy sources. This study provides a wave energy prediction model for energy harvesting. At the same time, the Gated Recurrent Unit network (GRU), Bayesian optimization algorithm, and attention mechanism are introduced to improve the model's performance. Bayesian optimization methods are used to optimize hyperparameters throughout the model training, and attention mechanisms are used to assign different weights to features to increase the prediction accuracy. Finally, the 1-hour and 6-hour forecasts are made using the data from China's NJI and BSG observatories, and the system performance is analyzed. The results show that, compared with mainstream prediction algorithms, GRU based on Bayesian optimization and attention mechanism has the highest prediction accuracy, with the lowest MAE of 0.3686 and 0.8204, and the highest R2 of 0.9127 and 0.6436, respectively. Therefore, the prediction model proposed here can provide support and reference for the navigation of ships powered by wave energy.
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| 10. |
- Lindroth [formerly Tyrberg], Simon, 1979-
(författare)
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Buoy and Generator Interaction with Ocean Waves : Studies of a Wave Energy Conversion System
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- On March 13th, 2006, the Division of Electricity at Uppsala University deployed its first wave energy converter, L1, in the ocean southwest of Lysekil. L1 consisted of a buoy at the surface, connected through a line to a linear generator on the seabed. Since the deployment, continuous investigations of how L1 works in the waves have been conducted, and several additional wave energy converters have been deployed. This thesis is based on ten publications, which focus on different aspects of the interaction between wave, buoy, and generator. In order to evaluate different measurement systems, the motion of the buoy was measured optically and using accelerometers, and compared to measurements of the motion of the movable part of the generator - the translator. These measurements were found to correlate well. Simulations of buoy and translator motion were found to match the measured values. The variation of performance of L1 with changing water levels, wave heights, and spectral shapes was also investigated. Performance is here defined as the ratio of absorbed power to incoming power. It was found that the performance decreases for large wave heights. This is in accordance with the theoretical predictions, since the area for which the stator and the translator overlap decreases for large translator motions. Shifting water levels were predicted to have the same effect, but this could not be seen as clearly. The width of the wave energy spectrum has been proposed by some as a factor that also affects the performance of a wave energy converter, for a set wave height and period. Therefore the relation between performance and several different parameters for spectral width was investigated. It was found that some of the parameters were in fact correlated to performance, but that the correlation was not very strong. As a background on ocean measurements in wave energy, a thorough literature review was conducted. It turns out that the Lysekil project is one of quite few projects that have published descriptions of on-site wave energy measurements.
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| 11. |
- Behzadi, Amirmohammad, et al.
(författare)
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A Green and Energy-Efficient Smart Building Driven by Photovoltaic Thermal Panels Connected to the Grid
- 2023
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Ingår i: International Conference on Smart Cities and Green ICT Systems, SMARTGREENS - Proceedings. - : Science and Technology Publications, Lda. - 9789897586514 ; , s. 106-112
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Konferensbidrag (refereegranskat)abstract
- The present paper introduces a new smart building system driven by photovoltaic thermal panels. The concept is to improve the contribution of renewable energy in the local matrix for peak load shaving by having a two-way connection with the local electricity network via a rule-based energy monitoring control design. Besides, the feasibility of removing the electrical storage unit with high investment cost is studied by establishing a dynamic interaction between the energy production and usage components to reduce the energy costs over the year. The system has intelligent thermal energy storage integrated with an electrically-driven coil, heat exchanger, pumps, and several smart valves and control units. The transient system simulation (TRNSYS) package is implemented to assess the practicality of the suggested intelligent model for a building complex in Malmo, Sweden. According to the parametric outcomes, by raising the panel area, while the generated electricity increases, the solar utilization factor falls, indicating conflictive changes among performance metrics. The results also show that the renewable resource covers the building's heating and electricity demands for the majority of the year and that a significant amount of energy is sold to the neighbourhood electricity grid, demonstrating the viability of the introduced intelligent model.
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| 12. |
- Binder, Christian, 1988-, et al.
(författare)
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Phosphor Thermometry for In-Cylinder Surface Temperature Measurements in Diesel Engines
- 2019
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Ingår i: Measurement science and technology. - 0957-0233 .- 1361-6501.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Surface temperature measurements in technically relevant applications can be very hallenging and yet of great importance. Phosphor thermometry is a temperature measurement technique that has previously been employed in technically relevant applications to obtain surface temperature. The technique is based on temperature-dependent changes in a phosphor’s luminescence. To improve the accuracy and precision of temperature measurements with this technique, the present study considers, by way of example, the impact of conditions inside the cylinder of a diesel engine on decay time based phosphor thermometry. After an initial, general assessment of the effect of prevailing measurement conditions, this research investigates errors caused by soot luminosity, extinction, signal trapping and changes of phosphors’ luminescence properties due to exposure to the harsh environment. Furthermore, preferable properties of phosphors which are suitable for in-cylinder temperature measurements are discussed. 16 phosphors are evaluated, including four which – to the authors’ knowledge –have previously not been used in thermometry. Results indicate that errors due to photocathode bleaching, extinction, signal trapping and changes of luminescence properties may cause an erroneous temperature evaluation with temperature errors in the order of serval tens of Kelvin.
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| 13. |
- Skagestad, Ragnhild, 1978, et al.
(författare)
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GCCSI Webinar: Cutting Cost of CO2 Capture in Process Industry (CO2stCap) Project overview & first results for partial CO2 capture at integrated steelworks
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- GCCSI Webinar: Cutting Cost of CO2 Capture in Process Industry (CO2stCap) Project overview & first results for partial CO2 capture at integrated steelworks This publication has the format of a webinar: The CO2StCap project is a four year initiative carried out by industry and academic partners with the aim of reducing capture costs from CO2 intensive industries (more information here). The project, led by Tel-Tek, is based on the idea that cost reduction is possible by capturing only a share of the CO2 emissions from a given facility, instead of striving for maximized capture rates. This can be done in multiple ways, for instance by capturing only from the largest CO2 sources at individual multi-stack sites utilising cheap waste heat or adapting the capture volumes to seasonal changes in operations. The main focus of this research is to perform techno-economic analyses for multiple partial CO2 capture concepts in order to identify economic optimums between cost and volumes captured. In total for four different case studies are developed for cement, iron & steel, pulp & paper and ferroalloys industries. The first part of the webinar gave an overview of the project with insights into the cost estimation method used. The second part presented the iron & steel industry case study based on the Lulea site in Sweden, for which waste-heat mapping methodology has been used to assess the potential for partial capture via MEA-absorption. Capture costs for different CO2 sources were discussed, demonstrating the viability of partial capture in an integrated steelworks.
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| 14. |
- Johansson, Björn, 1975, et al.
(författare)
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Power Level Sampling of Metal Cutting Machines for Data Representation in Discrete Event Simulation
- 2015
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 53:23, s. 7060-7070
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Tidskriftsartikel (refereegranskat)abstract
- An extension to the application area for discrete event simulation (DES) has been ongoing since the last decade and focused only on economic aspects to include ecologic sustainability. With this new focus, additional input parameters, such as electrical power consumption of machines, are needed. This paper aim at investigating how NC machine power consumption should be represented in simulation models of factories. The study includes data-sets from three different factories. One factory producing truck engine blocks, one producing brake disc parts for cars and one producing forklift components. The total number of data points analysed are more than 2,45,000, where of over 1,11,000 on busy state for 11 NC machines. The low variability between busy cycles indicates that statistical representations are not adding significant variability. Furthermore, results show that non-value-added activities cause a substantial amount of the total energy consumption, which can be reduced by optimising the production flow using dynamic simulations such as DES.
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| 15. |
- Shahroozi, Zahra, 1992-
(författare)
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Survivability control using data-driven approaches and reliability analysis for wave energy converters
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wave energy, with five times the energy density of wind and ten times the power density of solar, offers a compelling carbon-free electricity solution. Despite its advantages, ongoing debates surround the reliability and economic feasibility of wave energy converters (WECs). To address these challenges, this doctoral thesis is divided into four integral parts, focusing on optimizing the prediction horizon for power maximization, analyzing extreme waves' impact on system dynamics, ensuring reliability, and enhancing survivability in WECs.Part I emphasizes the critical importance of the prediction horizon for maximal power absorption in wave energy conversion. Using generic body shapes and modes, it explores the effect of dissipative losses, noise, filtering, amplitude constraints, and real-world wave parameters on the prediction horizon. Findings suggest achieving optimal power output may be possible with a relatively short prediction horizon, challenging traditional assumptions.Part II shifts focus to WEC system dynamics, analyzing extreme load scenarios. Based on a 1:30 scaled wave tank experiment, it establishes a robust experimental foundation, extending into numerical assessment of the WEC. Results underscore the importance of damping to alleviate peak forces. Investigating various wave representations highlights conservative characteristics of irregular waves, crucial for WEC design in extreme sea conditions.Part III explores the computational intricacies of environmental design load cases and fatigue analyses for critical mechanical components of the WEC. The analysis is conducted for hourly sea state damage and equivalent two-million-cycle loads. Finally, a comparison of safety factors between the ultimate limit state and fatigue limit state unfolds, illustrating the predominant influence of the ultimate limit state on point-absorber WEC design.Part IV, centers on elevating survivability strategies for WECs in extreme wave conditions. Three distinct controller system approaches leverage neural networks to predict and minimize the line force. Distinct variations emerge in each approach, spanning from rapid detection of optimal damping to integrating advanced neural network architectures into the control system with feedback. The incorporation of a controller system, refined through experimental data, showcases decreases in the line force, providing a practical mechanism for real-time force alleviation.This thesis aims to contribute uniquely to the goal of advancing wave energy conversion technology through extensive exploration.
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| 16. |
- Kyprianidis, Konstantinos, 1984, et al.
(författare)
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Multidisciplinary Analysis of a Geared Fan Intercooled Core Aero-Engine
- 2014
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 136:1
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Tidskriftsartikel (refereegranskat)abstract
- The reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, along with the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. The thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is very little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to analyze the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. With minimum mission fuel in mind, the results indicate as optimal values a pressure ratio split exponent of 0.38 and an intercooler mass flow ratio of 1.18 at hot-day top of climb conditions. At ISA midcruise conditions a specific thrust of 86 m/s, a jet velocity ratio of 0.83, an intercooler effectiveness of 56%, and an overall pressure ratio value of 76 are likely to be a good choice. A 70,000 lbf intercooled turbofan engine is large enough to make efficient use of an all-axial compression system, particularly within a geared fan configuration, but intercooling is perhaps more likely to be applied to even larger engines. The proposed optimal jet velocity ratio is actually higher than the value one would expect by using standard analytical expressions, primarily because this design variable affects core efficiency at midcruise due to a combination of several different subtle changes to the core cycle and core component efficiencies at this condition. The analytical expressions do not consider changes in core efficiency and the beneficial effect of intercooling on transfer efficiency, nor do they account for losses in the bypass duct and jet pipe, while a relatively detailed engine performance model, such as the one utilized in this study, does. Mission fuel results from a surrogate model are in good agreement with the results obtained from a rubberized-wing aircraft model for some of the design parameters. This indicates that it is possible to replace an aircraft model with specific fuel consumption and weight penalty exchange rates. Nevertheless, drag count exchange rates have to be utilized to properly assess changes in mission fuel for those design parameters that affect nacelle diameter.
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| 17. |
- Wadekar, Sandip, 1989
(författare)
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Large-Eddy Simulation of Gasoline Fuel Spray Injection at Ultra-High Injection Pressures
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gasoline direct injection is a state-of-the-art technique that reduces hydrocarbon and particulate emissions. However, further improvement is needed to meet current as well as future emission regulations. A prominent solution is to increase the fuel injection pressure which allows faster fuel droplet atomization, quick evaporation and improves fuel-air mixture formation under realistic engine conditions. In this work, the gasoline fuel injection process at ultra-high injection pressures ranging from 200 to 1500 bar was analyzed using numerical models. In particular, the Large-Eddy Simulation (LES) method, with the standard Smagorinsky turbulence model, was utilized using the Eulerian formulation for the continuous phase. The discrete droplet phase was treated using a Lagrangian formulation together with spray sub-models. In the first part of study, spray was injected into an initially quiescent constant volume chamber using two different nozzle hole shape geometries: divergent and convergent. The numerical results were calibrated by reproducing experimentally observed liquid penetration length and efforts were made to understand the influence of ultra-high injection pressures on spray development. The calibrated models were then used to investigate the impact of ultra-high injection pressures on mean droplet sizes, droplet size distribution, spray-induced large-scale eddies and entrainment rate. The results showed that, at ultra-high injection pressures, the mean droplet sizes were significantly reduced and the droplets achieving very high velocities. Integral length scales of spray-induced turbulence and air entrainment rate were better for the divergent-shaped injector, and considerably larger at higher injection pressures compared to lower ones. In the second part of the study, four consecutive full-cycle cold flow LES simulations were carried out to generate realistic turbulence inside the engine cylinder. The first three cycles were ignored, with the fourth cycle being used to model the injection of the fuel using the divergent-shaped injector only (which was found to be better in the previous part of this study) at different injection pressures. In addition to the continuous gas phase (Eulerian) and the dispersed liquid (Lagrangian), the liquid film feature (Finite-Area) was used to model the impingement of fuel spray on the engine walls and subsequent liquid film formation. The simulation results were used to evaluate spray-induced turbulence, fuel-air mixing efficiency and the amount of liquid mass deposited on the walls. The limitation of the high-pressure injection technique with respect to liquid film formation was optimized using a start of injection (SOI) sweep. Overall results showed that the mixing efficiency increased at high injection pressure and that SOI should occur between early injection and late injection to optimize the amount of mass being deposited on the engine walls.
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| 18. |
- Honeth, Nicholas, et al.
(författare)
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Application of the IEC 61850-7-420 data model on a hybrid renewable energy system
- 2011
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Ingår i: 2011 IEEE PES Trondheim PowerTech. - Trondheim : IEEE Communications Society. - 9781424484195 - 9781424484171
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Konferensbidrag (refereegranskat)abstract
- IEC 61850 is the most promising standard for design of substation communication and automation systems. Recent revisions of the standard include support for modeling, and control of Distributed Energy Resources (DER). This paper presents an application of the IEC 61850-7-420 data model for DER in the implementation of a control and energy management system for a Hybrid Renewable Energy System (HRES). These systems are beginning to prove their usefulness in providing deployable electrical supply in locations where no such supply exists as well as for backup power or power quality related support functions. The motivation for applying the standard to the design process is twofold; to modularize the design according to an accepted international standard and to design for interoperability with other IEC 61850 enabled devices and SCADA systems.
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| 19. |
- Yang, Shun-Han, 1987, et al.
(författare)
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Parametric study of the dynamic motions and mechanical characteristics of power cables for wave energy converters
- 2018
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Ingår i: Journal of Marine Science and Technology. - : Springer Science and Business Media LLC. - 0948-4280 .- 1437-8213. ; 23:1, s. 10-29
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Tidskriftsartikel (refereegranskat)abstract
- A case study of a point-absorber wave energy converter (WEC) system is presented. The WEC system forms an array, with several WECs located around a central hub to which they are each connected by a short, free-hanging power cable. The objective of the study is to analyse the dynamic characteristics and estimate the fatigue life of the power cable which is not yet in use or available on the commercial market. Hence, a novel approach is adopted in the study considering that the power cable’s length is restricted by several factors (e.g., the clearances between the service vessel and seabed and the cable), and the cable is subject to motion and loading from the WEC and to environmental loads from waves and currents (i.e., dynamic cable). The power cable’s characteristics are assessed using a numerical model subjected to a parametric analysis, in which the environmental parameters and the cable’s design parameters are varied. The results of the numerical simulations are compared and discussed regarding the responses of the power cables, including dynamic motion, curvature, cross-sectional forces, and accumulated fatigue damage. The effects of environmental conditions on the long-term mechanical life spans of the power cables are also investigated. Important cable design parameters that result in a long power cable (fatigue) service life are identified, and the cable service life is predicted. This study contributes a methodology for the first-principle design of WEC cables that enables the prediction of cable fatigue life by considering environmental conditions and variations in cable design parameters.
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| 20. |
- Kersten, Anton, 1991
(författare)
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Modular Battery Systems for Electric Vehicles based on Multilevel Inverter Topologies - Opportunities and Challenges
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modular battery systems based on multilevel inverter (MLI) topologies can possibly overcome some shortcomings of two-level inverters when used for vehicle propulsion. The results presented in this thesis aim to point out the advantages and disadvantages, as well as the technical challenges, of modular vehicle battery systems based on MLIs in comparison to a conventional, two-level IGBT inverter drivetrain. The considered key aspects for this comparative investigation are the drive cycle efficiency, the inverter cost, the fault tolerance capability of the drivetrain and the conducted electromagnetic emissions. Extensive experiments have been performed to support the results and conclusions. In this work, it is shown that the simulated drive cycle efficiency of different low-voltage-MOSFET-based, cascaded seven-level inverter types is improved in comparison to a similarly rated, two-level IGBT inverter drivetrain. For example, the simulated WLTP drive cycle efficiency of a cascaded double-H-bridge (CDHB) inverter drivetrain in comparison to a two-level IGBT inverter, when used in a small passenger car, is increased from 94.24% to 95.04%, considering the inverter and the ohmic battery losses. In contrast, the obtained efficiency of a similar rated seven-level cascaded H-bridge (CHB) drivetrain is almost equal to that of the two-level inverter drivetrain, but with the help of a hybrid modulation technique, utilizing fundamental selective harmonic elimination at lower speeds, it could be improved to 94.85%. In addition, the CDHB and CHB inverters’ cost, in comparison to the two-level inverter, is reduced from 342€ to 202€ and 121€, respectively. Furthermore, based on a simple three-level inverter with a dual battery pack, it is shown that MLIs inherently allow for a fault tolerant operation. It is explained how the drivetrain of a neutral point clamped (NPC) inverter can be operated under a fault condition, so that the vehicle can drive with a limited maximum power to the next service station, referred to as limp home mode. Especially, the detection and localization of open circuit faults has been investigated and verified through simulations and experiments. Moreover, it is explained how to measure the conducted emissions of an NPC inverter with a dual battery pack according to the governing standard, CISPR 25, because the additional neutral point connection forms a peculiar three-wire DC source. To separate the measured noise spectra into CM, line-DM and phase-DMquantities, two hardware separators based on HF transformers are developed and utilized. It is shown that the CM noise is dominant. Furthermore, the CM noise is reduced by 3dB to 6dB when operating the inverter with three-level instead of two-level modulation.
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| 21. |
- Wang, S., et al.
(författare)
-
Operational reliability of multi-energy customers considering service-based self-scheduling
- 2019
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 254
-
Tidskriftsartikel (refereegranskat)abstract
- The developments of energy storage and substitution techniques have made it possible for customers to self-schedule their energy consumption behaviors, to better satisfy their demands in response to uncertain supply conditions. The interdependency of multiple energies, the chronological characteristics, and uncertainties in the self-scheduling context bring about additional complexities to secure the reliable energy requirements of multi-energy customers. As a necessary and challenging task, the operational reliability of multi-energy customers is tackled in this paper. Considering that the consumed energies eventually come down to the energy-related services, the self-scheduling of multi-energy customers is implemented from the perspective of specific energy-related services rather than energy carriers. Firstly, an optimal self-scheduling model for multi-energy customers is developed with the consideration of chronological service curtailment, service shifting and possible failures during service shifting. In the optimal self-scheduling model, the costs of service curtailment and shifting are formulated based on the proposed evaluation method. The time-sequential Monte Carlo simulation approach is applied to model the chronological volatilities of multi-energy demands over the entire study period, embedded with a scenario reduction technique to reduce the computational efforts. Taking full account of the possible scenarios, the quantitative reliability indices of the multi-energy customers can be obtained. The results in test cases demonstrate that the expected energy not supplied of the multi-energy customer drops significantly by 56.32% with the self-scheduling strategy. It can be also concluded that, the self-scheduling and its inherent uncertainties do have significant impacts on the operational reliability of the multi-energy customer.
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| 22. |
- Li, Xiaojian, 1991, et al.
(författare)
-
Installation effects on engine design
- 2020
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Increasing the engine bypass ratio is one way to improve propulsive efficiency. However, an increase in the bypass ratio (BPR) has usually been associated with an increase in the fan diameter. Consequently, there can be a notable increase in the impact of the engine installation on the overall aircraft performance. In order to achieve a better balance between those factors, it requires novel nacelle and engine design concepts. This report mainly reviews installation effects on engine design. Firstly, the installation effects assessment methods are introduced. Then, the installation effects on engine cycle design, intake design and exhaust design are sequentially reviewed.
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| 23. |
- Chiu, Justin N. W., et al.
(författare)
-
Industrial surplus heat storage in smart cities
- 2015
-
Ingår i: ASME 2015 9th International Conference on Energy Sustainability, ES 2015, collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. - : American Society of Mechanical Engineers. - 9780791856857
-
Konferensbidrag (refereegranskat)abstract
- Surplus heat generated from industrial sectors amounts to between 20% and 50% of the total industrial energy input. Smart reuse of surplus heat resulted from industrial sectors and power generation companies is an opportunity to improve the overall energy efficiency through more efficient use the primary energy sources. A potential solution to tackle this issue is through use of thermal energy storage (TES) to match user demand to that of the generated surplus heat. A mobile TES (MTES) concept of transportation of industrial surplus heat from production sites to end customers has shown promising results. One commissioned demonstration project using industrial heat for swimming pool water temperature regulation in Dortmund, Germany proved the interest and attention given to this concept. In this paper, a techno-economic case study in Sweden of transportation of surplus thermal energy to district heating in smart cities is presented. The application consists of heat storage at 110°C- 130°C through the use of phase change materials (PCM) based TES, notably with use of Erythritol (90 kWh/ton) for the considered temperature range, to remote district heating network located at 48 km from the thermal energy generation site. The advantages of using latent heat based PCM are the high enthalpy density per unit volume and per unit mass, as well as the quasi-constant temperature during charging and releasing of heat. The M-TES in this study has a total storage capacity of 2.1 MWh, the optimization of charge/discharge time to the amount of stored/released energy and to that of energy transportation rate is presented in this paper. Contrary to logical thinking, it is shown through this work that under certain conditions, it is more cost-effective to operate at partial load of storage units albeit the increased number of transport trips and charge/discharge cycles.
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| 24. |
- Lv, Zhihan, Dr. 1984-, et al.
(författare)
-
Digital twins for secure thermal energy storage in building
- 2023
-
Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 338
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work is to explore the role of the safe and optimal scheduling of thermal energy storage systems in intelligent buildings in promoting sustainable economic development under Digital Twins (DTs) technology. Phase Change Material (PCM) has high energy density, constant temperature storage, small footprint, and long service life. Here, PCM is first placed in the indoor building structure, and the DTs technology is introduced. In the development of intelligent buildings, the data generated by the energy storage system of intelligent buildings in the real space can be mapped to the virtual space in real time for simultaneous analysis. In addition, the PCM wall structure and thermal network DTs model are designed for the intelligent building. In addition, the PCW structure is used to build a thermal energy storage and dispatch model of the smart thermoelectric building based on DTs. Finally, the model is evaluated and analyzed experimentally. The analysis of system optimization power under different schemes indicates that the scheduling operation strategy of thermal energy storage of building walls can avoid overcharging or over-discharging batteries in the microgrid and reduce battery power consumption. Besides, the building wall energy storage capacity is always in the range of 0.2 ∼ 0.8 on the all-weather scale. Moreover, the model constructed here achieves significantly lower economic costs, environmental costs, and energy costs and a better energy-saving effect than the existing model. The model built here can serve as experimental reference for further digital energy storage in intelligent buildings and comprehensive energy utilization because of its superior safety performance and lower consumption.
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| 25. |
- Mohammed, Abdullah, et al.
(författare)
-
Minimizing energy consumption for robot arm movement
- 2014
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271 .- 2212-8271. ; 25, s. 400-405
-
Konferensbidrag (refereegranskat)abstract
- Robots are widely used in industry due to their efficiency and high performance. Many of them are operating in the manufacturing stage of the production line where the highest percentage of energy is consumed. Therefore, their energy consumption became a major focus for many robots manufacturers and academic research groups. Nevertheless, the optimization of that consumption is still a challenging task which requires a deep understanding of the robot's kinematic and dynamic behaviors. This paper proposes an approach to develop an optimization module using Matlab® to minimize the energy consumptions of the robot's movement. With the help of Denavit-Hartenberg notation, the approach starts first by solving the inverse kinematics of the robot to find a set of feasible joint configurations required to perform the task, solving the inverse kinematics is usually a challenging step which requires in-depth analyses of the robot. The module then solves the inverse dynamics of the robot to analyze the forces and torques applied on each joint and link in the robot. Furthermore, a calculation for the energy consumption is performed for each configuration. The final step of the process represents the optimization of the calculated configurations by choosing the one with the lowest power consumption and sends the results to the robot controller. Three case studies are used to evaluate the performance of the module. The experimental results demonstrate the developed module as a successful tool for energy efficient robot path planning. Further analyses for the results have been done by comparing them with the ones from commercial simulation software. The case studies show that the optimization of the location for the target path could reduce the energy consumption effectively.
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| 26. |
- Mölleryd, Bengt A, 1947-
(författare)
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Governance of innovation - deploying an architectural framework for innovation of technological systems for energy, security and defence
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Governance of innovation – deploying an architectural framework for innovation of technological systems for energy, security and defence Innovation has a great deal of attraction but is associated with serious uncertainties and downsides. It is potentially beneficial for growth, sector and industrial development and competitiveness. Innovation brings hope of solving societal challenges, such as climate change and environment protection, and could help secure a supply of energy. Furthermore, it improves resilience and strengthens security and defence.The downside of innovations of some magnitude concern severe transitions and disruptions. Digitisation, with associated net technologies, is an illustrative example of an innovation that creates new services, competitiveness and other benefits which is enormously positive and attractive, while simultaneously dismantles and destroys existing systems, firms and branches, and whole sectors and practices.The thesis deals with promoting innovations at large but specifically systemic, defined as a value-adding (to customers and users) set or convergence of new products/services from technological systems in processes which emerge by evolutionary association and integration of systems transforming businesses, industries and sectors (with disruptions as consequence). Innovations are distinguished by certain structural properties namely systemicitiness. The systemicitiness of innovations suggests a distinct architectural framework that determines the structure of innovations. The purpose of the proposal for an architectural framework for innovation is guidance to governance of innovation. Platform based ecosystems exemplifies an emulation of systemic innovation that aligns with the proposed framework. The framework is distilled from cases, events, patterns, landscapes and models of innovation in the literature, connected with examination of systemicitiness and governance approaches to innovation and innovation processes. The architectural framework is conjected as compatible and complementary to common policies and instruments for innovation and innovation processes as holistic systems engineering, standards and protocols (e.g. ISO/IEC 15288:2015, ISO/IEC 42010:2011, NISP).
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| 27. |
- Tillig, Fabian, 1984, et al.
(författare)
-
A generic energy systems model for efficient ship design and operation
- 2017
-
Ingår i: Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment. - : SAGE Publications. - 2041-3084 .- 1475-0902. ; 231:2, s. 649-666
-
Tidskriftsartikel (refereegranskat)abstract
- There is an evironmental and econimical motivated need to reduce the fuel consumption and air emmissions of ships. To achieve a reduction of the energy consumption, the energy flow in the entire energy system of a ship must be analyzed in both, the component, or subsystem level as well as in a holistic way to capture the interactions between the components. Of the currently available energy consumption monitoring and prediction methods or models, no single model or method can be used to asses the energy efficiency of an arbritary vessel in both the early design phase and operation of ships. This study presents a new generic ship energy systems model that can be used for this purpose. This new model has two parts: one for assessment of a ship’s energy consumption based on an ordinary static power prediction and one for advanced operational analysis, considering hydrodynamic and machinery systems effects. A Panamax tanker vessel was used as the case study vessel to prove the versatility of the model for five example simulations for the design and operation of ships. The examples include variations of the main dimensions, propeller design, engine layout and the operational profile on a North Atlantic route. From the results, different areas with a potential for energy savings were identified.
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| 28. |
- Acuña, José, 1982-
(författare)
-
Distributed thermal response tests : New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes
- 2013
-
Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs.Field tests are performed using distributed temperature measurements along U-pipe and coaxial heat exchangers installed in groundwater filled boreholes. The measurements are carried out during heat injection thermal response tests and during short heat extraction periods using heat pumps. Temperatures are measured inside the secondary fluid path, in the groundwater, and at the borehole wall. These type of temperature measurements were until now missing.A new method for testing borehole heat exchangers, Distributed Thermal Response Test (DTRT), has been proposed and demonstrated in U-pipe, pipe-in-pipe, and multi-pipe BHE designs. The method allows the quantification of the BHE performance at a local level.The operation of a U-pipe thermosyphon BHE consisting of an insulated down-comer and a larger riser pipe using CO2 as a secondary fluid has been demonstrated in a groundwater filled borehole, 70 m deep. It was found that the CO2 may be sub-cooled at the bottom and that it flows upwards through the riser in liquid state until about 30 m depth, where it starts to evaporate.Various power levels and different volumetric flow rates have been imposed to the tested BHEs and used to calculate local ground thermal conductivities and thermal resistances. The local ground thermal conductivities, preferably evaluated at thermal recovery conditions during DTRTs, were found to vary with depth. Local and effective borehole thermal resistances in most heat exchangers have been calculated, and their differences have been discussed in an effort to suggest better methods for interpretation of data from field tests.Large thermal shunt flow between down- and up-going flow channels was identified in all heat exchanger types, particularly at low volumetric flow rates, except in a multi-pipe BHE having an insulated central pipe where the thermal contact between down- and up-coming fluid was almost eliminated.At relatively high volumetric flow rates, U-pipe BHEs show a nearly even distribution of the heat transfer between the ground and the secondary fluid along the depth. The same applies to all coaxial BHEs as long as the flow travels downwards through the central pipe. In the opposite flow direction, an uneven power distribution was measured in multi-chamber and multi-pipe BHEs.Pipe-in-pipe and multi-pipe coaxial heat exchangers show significantly lower local borehole resistances than U-pipes, ranging in average between 0.015 and 0.040 Km/W. These heat exchangers can significantly decrease the temperature difference between the secondary fluid and the ground and may allow the use of plain water as secondary fluid, an alternative to typical antifreeze aqueous solutions. The latter was demonstrated in a pipe-in-pipe BHE having an effective resistance of about 0.030 Km/W.Forced convection in the groundwater achieved by injecting nitrogen bubbles was found to reduce the local thermal resistance in U-pipe BHEs by about 30% during heat injection conditions. The temperatures inside the groundwater are homogenized while injecting the N2, and no radial temperature gradients are then identified. The fluid to groundwater thermal resistance during forced convection was measured to be 0.036 Km/W. This resistance varied between this value and 0.072 Km/W during natural convection conditions in the groundwater, being highest during heat pump operation at temperatures close to the water density maximum.
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| 29. |
- Sun, Peikun, et al.
(författare)
-
Analysis of camber control and torque vectoring to improve vehicle energy efficiency
- 2018
-
Ingår i: The Dynamics of Vehicles on Roads and Tracks. - : CRC Press/Balkema. - 9781138035713 ; 1, s. 121-128
-
Konferensbidrag (refereegranskat)abstract
- This paper focuses on the use of camber control and torque vectoring in order to make future vehicles more energy efficient and thereby more environmentally friendly. The energy loss during steady state cornering including rolling resistance loss, aerodynamic loss, longitudinal slip loss and lateral slip loss, is formulated and studied. Camber control, torque vectoring control and a combination of both are compared. From the simulation results, it can be concluded that during steady state cornering, torque vectoring has a very small contribution to energy reduction while camber control can make a significant contribution to energy saving. By combining torque vectoring and camber control during steady state cornering, in theory up to 14% energy saving are found for certain cases.
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| 30. |
- Sandberg, Marcus, et al.
(författare)
-
A modelling methodology for assessing use of datacenter waste heat in greenhouses
- 2017
-
Konferensbidrag (refereegranskat)abstract
- In Sweden, the number of datacenters establishments are steadily increasing thanks to green, stable and affordable electricity, free air cooling, advantageous energy taxes and well-developed Internet fiber infrastructures. Even though datacenters use a lot of energy, the waste heat that they create is seldom reused. A possible cause is that this waste heat is often low grade and airborne: it is therefore hard to directly inject it into a district heating system without upgrades, which require additional energy and equipment that generate extra costs. One option for reusing this heat without needs for upgrades is to employ it for heating up greenhouses. But assessing the feasibility of this approach by building physical prototypes can be costly, therefore using computer models to simulate real world conditions is an opportunity. However, there is a lack of computer modelling methodologies that can assess the possibility of using waste heat from datacenters in greenhouses in cold climates.The objective of this paper is therefore to propose such a methodology and discuss its benefits and drawbacks in comparison with other research studies. This methodology combines computational fluid dynamics, process modelling and control engineering principles into a computer model that constitutes a decision support system to study different waste heat and greenhouse or mushroom house scenarios.The paper validates the strategy through a case study in northern Sweden, where we assess the amount of produced waste heat by collecting temperature, relative humidity, and fan speed data for the air discharged from the datacenter.The resulting methodology, composed by conducting measurements and computer models, calculations can then be used for other datacenter operators or greenhouse developers to judge whether it is possible or not to build greenhouses using datacenter waste heat.
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| 31. |
- Tillig, Fabian, 1984, et al.
(författare)
-
Design, operation and analysis of wind-assisted cargo ships
- 2020
-
Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018. ; 211:1, s. 1-23
-
Tidskriftsartikel (refereegranskat)abstract
- This study presents a novel approach to analytically capture aero- and hydrodynamic interaction effects on wind-assisted ships. Low aspect ratio wing theory is applied and modified to be used for the prediction of lift and drag forces of hulls sailing at drift angles. Aerodynamic interaction effects are captured by analytically solving the Navier-Stokes equation for incompressible, potential flow. The developed methods are implemented to a 4 degrees-of-freedom performance prediction model called “ShipCLEAN”, including a newly developed method for rpm control of Flettner rotors on a ship to maximize fuel savings. The accuracy of the model is proven by model- and full-scale verification. To present the variability of the model, two case study ships, a tanker and a RoRo, are equipped with a total of 11 different arrangements of Flettner rotors. The fuel savings and payback times are assessed using realistic weather from ships traveling on a Pacific Ocean route (tanker) and Baltic Sea route (RoRo). The results verify the importance of using a 4 degrees-of-freedom ship performance model, aero- and hydrodynamic interaction and the importance of controlling the rpm of each rotor individually. Fuel savings of 30% are achieved for the tanker, and 14% are achieved for the RoRo.
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| 32. |
- Ringsberg, Jonas, 1971
(författare)
-
Models and strategies
- 2017
-
Ingår i: Wave & Tidal Energy Network Magazine. ; :11, s. 27-27
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Wave Energy Group on the Division of Marine Technology on the Department of Mechanics and Maritime Sciences, Chalmers University of Technology, develops simulation models for structural integrity analysis of mooring lines and umbilical cables used in wave energy converter (WEC) systems. The article gives an overview of ongoing research projects and an outlook.
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| 33. |
- Fachrizal, Reza, 1993-, et al.
(författare)
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Urban-scale energy matching optimization with smart EV charging and V2G in a net-zero energy city powered by wind and solar energy
- 2024
-
Ingår i: eTransporation. - : Elsevier. - 2590-1168. ; 20
-
Tidskriftsartikel (refereegranskat)abstract
- Renewable energy sources (RES) and electric vehicles (EVs) are two promising technologies that are widely recognized as key components for achieving sustainable cities. However, intermittent RES generation and increased peak load due to EV charging can pose technical challenges for the power systems. Many studies have shown that improved load matching through energy system optimization can minimize these challenges. This paper assesses the optimal urban-scale energy matching potentials in a net-zero energy city powered by wind and solar energy, considering three EV charging scenarios: opportunistic charging, smart charging, and vehicle-to-grid (V2G). This paper takes a city on the west coast of Sweden as a case study. The smart charging and V2G schemes in this study aim to minimize the mismatch between generation and load and are formulated as quadratic programming problems. Results show that the optimal load matching performance is achieved in a net-zero energy city with the V2G scheme and a wind-PV electricity production share of 70:30. The load matching performance is increased from 68% in the opportunistic charging scenario to 73% in the smart charging scenario and to 84% in the V2G scenario. It is also shown that a 2.4 GWh EV battery participating in the V2G scheme equals 1.4 GWh stationary energy storage in improving urban-scale load matching performance. The findings in this paper indicate a high potential from EV flexibility in improving urban energy system performance.
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| 34. |
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| 35. |
-
Chalmers Environmental Initiative Progress Report 2001
- 2001
-
Samlingsverk (redaktörskap) (refereegranskat)abstract
- The Board of the Chalmers University of TechnologyFoundation decided in 1999 to invest SEK 100million in a strategic investment in the environmentwith a special focus on environmental systems analysis.This investment was entitled The ChalmersEnvironmental Initiative (CEI). Through thisenvironmental initiative Chalmers has acquired aprominent international position within environmentalsystems analysis.CEI is the result of the active research and educationthat has taken place at Chalmers over the past 10years. A broad base in combination with leadingedge technology presented the opportunity to createa very strong research programme based oninteraction between the various schools at Chalmers.As CEI is integrated into undergraduate anddoctoral programmes at Chalmers, engineers,architects and doctoral students have access, withinthe framework of their studies, to research-basedenvironmental education with a focus on asustainable society. CEI also co-operates with otherparties, such as industry, politicians, various organisationsand the general public, as a further means ofcontributing to sustainable development in society.Within CEI, seven new professors have beenappointed within the following areas:Management for SustainabilityRolf Wolff, 1 June 2000Environmental Systems TechnologyAnne-Marie Tillman, 1 September 2000Sustainable Industrial MetabolismChristian Azar, 1 September 2000Global Environmental MeasurementsDonal Murtagh, 1 November 2000Green ChemistryWilliam J. Frederick Jr, 1 August 2001Sustainable Energy SystemsFilip Johnsson, preliminary 1 October 2001Design for Sustainable Urban DevelopmentVacant: interviews during April 2001The four professors appointed in 2000 are presentedin this report as well as their declaration of intentfor the next few years. At present, the CEI professorsare involved with approximately 40 universities,institutes and industrial partners in the form ofproject co-operation and joint publications. The fourprofessors have the greater proportion of theirenvironmental research funded through externalgrants, compared to CEI. The proportion of facultyfunds and other internal Chalmers funds is at presentvery low. A summary of the financing structureis also included in this report.During 2001, various forms of co-operation wereinitiated between the professors, such as joint projectplans, doctoral students, courses and graduateschools. During autumn 2001, a residential seminaris planned for discussions within CEI as well as anopen presentation of the project and the professors.This major in-house focus on environmental researchhas attracted attention externally and contributedto the opening up of new potential in combinationwith increased expectations. Since May 1, 2000,Chalmers has been a member of the Alliance forGlobal Sustainability (AGS), an association of someof the world’s foremost universities in theenvironmental field. AGS and other platforms formthe basis for international research collaboration.CEI and other environmental activities have led tospin-off effects and contributed to increased interestin Chalmers as an environmental university.Chalmers and Göteborg University were, forexample, jointly awarded the King Carl XVI Gustafvisiting professorship in environmental science for2001-2002 and Margot Wallström received anhonorary doctorate from Chalmers in 2001. A largenumber of well-known environmental researchershave also visited Chalmers to take part inconferences and seminars, including the winners ofthe Volvo Environmental Award for 2000 and thewinner of the City of Göteborg InternationalEnvironmental Award for 2000.
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| 36. |
- Jiao, Yang, et al.
(författare)
-
Analysis of two hybrid energy storage systems in an off-grid photovoltaic microgrid : A case study
- 2020
-
Ingår i: Proceedings IEEE PES Innovative Smart Grid Technologies Conference Europe. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 554-558
-
Konferensbidrag (refereegranskat)abstract
- In recent years, driven by global environmental issues, a growing number of renewable energy sources (RESs) have been developed. Microgrids have been confirmed as an important part in the increasing penetrations of renewable energy and the shift from a centralized paradigm to decentralized electricity production. The energy storage system (ESS) is a critical component that affects the development of microgrids. Combining advantages from different energy storage technologies, a hybrid energy storage system (HESS) can satisfy multiple requirements in microgrids. This paper compares the single battery system with the battery-supercapacitor (SC) HESS and the battery-flywheel HESS in an isolated photovoltaic (PV) power microgrid. Results show that both the SC and the flywheel distinctly reduce the battery charging and discharging powers and the required capacity of the battery. Therefore, the stresses and the needed size of the battery are reduced and the battery lifetime is extended.
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| 37. |
- Han, Weiji, 1987, et al.
(författare)
-
Next-Generation Battery Management Systems: Dynamic Reconfiguration
- 2020
-
Ingår i: IEEE Industrial Electronics Magazine. - 1941-0115 .- 1932-4529. ; 14:4, s. 20-31
-
Tidskriftsartikel (refereegranskat)abstract
- Batteries are widely applied to the energy storage and power supply in portable electronics, transportation, power systems, communication networks, etc. They are particularly demanded in the emerging technologies of vehicle electrification and renewable energy integration for a green and sustainable society. To meet various voltage, power, and energy requirements in large-scale applications, multiple battery cells have to be connected in series and/or parallel. While battery technology has advanced significantly in the past decade, existing battery management systems (BMSs) mainly focus on state monitoring and control of battery systems packed in fixed configurations. In fixed configurations, though, the battery system performance is in principle limited by the weakest cells, which can leave large parts severely underutilized. Allowing dynamic reconfiguration of battery cells, on the other hand, allows individual and flexible manipulation of the battery system at cell, module, and pack levels, which may open up a new paradigm for battery management. Following this trend, this paper provides an overview of next-generation BMSs featuring dynamic reconfiguration. Motivated by numerous potential benefits of reconfigurable battery systems (RBSs), the hardware designs, management principles, and optimization algorithms for RBSs are sequentially and systematically discussed. Theoretical and practical challenges during the design and implementation of RBSs are highlighted in the end to stimulate future research and development.
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| 38. |
- Jeong, Seung Hee, 1978-
(författare)
-
Soft Intelligence : Liquids Matter in Compliant Microsystems
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soft matter, here, liquids and polymers, have adaptability to a surrounding geometry. They intrinsically have advantageous characteristics from a mechanical perspective, such as flowing and wetting on surrounding surfaces, giving compliant, conformal and deformable behavior. From the behavior of soft matter for heterogeneous surfaces, compliant structures can be engineered as embedded liquid microstructures or patterned liquid microsystems for emerging compliant microsystems.Recently, skin electronics and soft robotics have been initiated as potential applications that can provide soft interfaces and interactions for a human-machine interface. To meet the design parameters, developing soft material engineering aimed at tuning material properties and smart processing techniques proper to them are to be highly encouraged. As promising candidates, Ga-based liquid alloys and silicone-based elastomers have been widely applied to proof-of-concept compliant structures.In this thesis, the liquid alloy was employed as a soft and stretchable electrical and thermal conductor (resistor), interconnect and filler in an elastomer structure. Printing-based liquid alloy patterning techniques have been developed with a batch-type, parallel processing scheme. As a simple solution, tape transfer masking was combined with a liquid alloy spraying technique, which provides robust processability. Silicone elastomers could be tunable for multi-functional building blocks by liquid or liquid-like soft solid inclusions. The liquid alloy and a polymer additive were introduced to the silicone elastomer by a simple mixing process. Heterogeneous material microstructures in elastomer networks successfully changed mechanical, thermal and surface properties.To realize a compliant microsystem, these ideas have in practice been useful in designing and fabricating soft and stretchable systems. Many different designs of the microsystems have been fabricated with the developed techniques and materials, and successfully evaluated under dynamic conditions. The compliant microsystems work as basic components to build up a whole system with soft materials and a processing technology for our emerging society.
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| 39. |
- Grip, Carl-Erik, et al.
(författare)
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Possibilities and problems in using exergy expressions in process integration
- 2011
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Ingår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011), 9-13 May, Linköping.. - Linköping : Linköping University Electronic Press. ; , s. 1605-1612
-
Konferensbidrag (refereegranskat)abstract
- Industrial energy systems are complicated networks, where changes in one process influence its neighboring processes. Saving energy in one unit does not necessarily lead to energy savings for the total system. A study has been carried out on the possibility to use the exergy concept in the analysis of industrial energy systems. The exergy concept defines the quality of an amount of energy in relation to its surrounding, expressing the part that could be converted into work. The study consists of literature studies and general evaluations, an extensive case study and an interview study. In the latter it was found that non technical factors are major obstacles to the introduction of exergy.
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| 40. |
- PAPPIS, IOANNIS, 1989-
(författare)
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Trade-offs and conflicting objectives of decision-making investments in low-carbon technology portfolios for sustainable development : National and continental insights offered by applying energy system models
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Energy infrastructure and appropriate energy policies are crucial for sustainable development and to meet Sustainable Development Goals (SDGs). Limiting global warming potential below 1.5oC would require “rapid and far-reaching” transitions and unprecedented changes in all aspects of society. Several factors influence investment decisions on energy conversion technologies and their specific locations. The choice, timing, and location of energy investments affect the total system cost, socio-economic development, the environment (e.g., emissions, water use), and a nation's energy security. However, existing national energy modelling initiatives only investigate a subset of these pillars for achieving sustainability.This thesis examines the challenges associated with the energy transition of low-and middle-income countries (Paraguay, Ethiopia, Africa). This work considers national and global policies, focusing on achieving SDG7 and SDG13. The dissertation includes a cover essay and four appended papers. The research conducted in this Thesis examines how energy-systems models can assist in understanding an energy system's complex interactions for sustainable development.Specifically, the results highlight hydropower and solar PV as key technologies to achieve climate change targets, energy security and energy access goals. Hydropower and other renewable electricity can be exported to bolster energy security for the exporting country, although export revenues are eroded by local demand growth and low export prices. The benefits of low-cost electricity provided by cross-border hydropower should be balanced against energy security concerns for the importing country. The research demonstrates the benefits of regional coordination, with trade enabling renewable resources to be harnessed and the electricity transmitted to demand centres. Although RET decreases carbon dioxide emissions and water use compared to fossil-fuel plants and creates more jobs, they require high up-front capital costs offset by the lower operating fuel costs in the long term. Thus, increasing the ambition of climate targets while achieving electricity access results in lower cumulative costs. Also, although hydropower and renewable technologies build climate resilience, hydropower operation depends on climate variability affecting energy security. Thus, mitigation strategies should consider the associated challenges of climate change in hydropower investments.Hydropower and renewables are primarily grid-connected technologies, so off-grid and mini-grid systems are key complements to national-grid expansion when pushing for universal energy access. They also impact energy security, total system costs and socio-economic development. This Thesis's outcomes can support governments in strategic energy planning to identify future renewable energy projects and ensure their financial viability. Energy systems in their transition need to be affordable, reliable and sustainable (e.g., energy secured, combat climate change) by being climate-resilient. The thesis findings demonstrate that nations need integrated energy planning, accounting for the geospatial characteristics of energy technologies, and water resources management to achieve SDG7 and build climate-resilient (SDG13). A broad portfolio of renewable technologies, interconnectors and a decentralized power generation system providing electricity closer to the end-user demand is needed to enhance energy security, decrease environmental pressures and provide affordable electricity for a nation.
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| 41. |
- Yang, Shun-Han, 1987, et al.
(författare)
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The influence of biofouling on power capture and the fatigue life of mooring lines and power cables used in wave energy converters
- 2016
-
Ingår i: Progress in Renewable Energies Offshore - Proceedings of RENEW 2016, the Second International Conference on Renewable Energies Offshore. - Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742 : CRC Press. ; , s. 711-722
-
Konferensbidrag (refereegranskat)abstract
- This study presents an analysis of a wave energy converter (WEC) system consisting of a buoy, a mooring system and a power cable connected to a hub. The investigated WEC system is currently under full-scale testing near Runde in Norway. The purpose of the study was to investigate the characteristics of the entire system, primarily with regard to energy performance and the fatigue life of the mooring lines and power cable, considering the effects of marine biofouling and its growth on the system’s components. The energy performance of the system and the fatigue life of the mooring lines and the power cable were systematically studied via parameter variation analysis, considering different mooring configurations, biofouling conditions, and environmental loads (current and sea state conditions), among other factors. Hydrodynamic and structural response simulations were conducted in a coupled response analysis using the DNV-GL software SESAM. Energy performance analyses and stress-based rainflow counting fatigue calculations were performed separately using an in-house code. The results show that, for a WEC system which has been deployed for 25 years, biofouling can reduce the total power absorption by up to 10% and decrease the fatigue life of the mooring lines by approximately 20%.
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| 42. |
- Sarkar, Saptarshi, 1992, et al.
(författare)
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Transient torque reversals in indirect drive wind turblnes
- 2023
-
Ingår i: Wind Energy. - 1099-1824 .- 1095-4244. ; 26, s. 691-716
-
Tidskriftsartikel (refereegranskat)abstract
- The adverse effect of transient torque reversals (TTRs) оп wind turЬine gearboxes сап Ье severe due to their magnitude and rapid occurrence compared with other equipment. The primary damage is caused to the bearings as the bearing loaded zone rapidly changes its direction. Other components are also affected Ьу TTRs (such as gear tooth); however, its impact оп bearings is the largest. While the occurrence and severity of TTRs are acknowledged in the industry, there is а lack of academic literature оп their initiation, propagation and the associated risk of damage. Furthermore, in the wide range of operation modes of а wind turЬine, it is not known which modes сап lead to TTRs. Further, the interdependence of TTRs оп environmental loading like the wind is also not reported. This paper aims to address these unknowns Ьу expanding оп the understanding of TTRs using а high-fidelity numerical model of an indirect drive wind turЬine with а douЬly fed induction generator (DFIG). То this end, а multibody model of the drivetrain is developed in SIMPACK. The model of the drivetrain is explicitly coupled to state-of-the-art wind turЬine simulator OpenFAST and а grid-connected DFIG developed in MATLAB®'s Simulink® allowing а coupled analysis of the electromechanical system. А metric termed slip risk duration is proposed in this paper to quantify the risk associated with the TTRs. The paper first investigates а wide range of IEC design load cases to uncover which load cases сап lead to TTRs. lt was found that emergency stops and symmetric grid voltage drops сап lead to TTRs. Next, the dependence of the TTRs оп inflow wind parameters is investigated using а sensitivity analysis. lt was found that the instantaneous wind speed at the onset of the grid fault or emergency shutdown was the most influential factor in the slip risk duration. The investigation enaЫes the designer to predict the occurrence of TTRs and quantify the associated risk of damage. The paper concludes with recommendations for utility-scale wind turЬines and directions for future research.
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| 43. |
- Lejon, Marcus, 1986, et al.
(författare)
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Multidisciplinary Design of a Three Stage High Speed Booster
- 2017
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Ingår i: ASME Turbo Expo 2017: Turbine Technical Conference and Exposition. - : ASME Press. ; 2B-2017
-
Konferensbidrag (refereegranskat)abstract
- The paper describes a multidisciplinary conceptual design of an axial compressor, targeting a three stage, high speed, high efficiency booster with a design pressure ratio of 2.8. The paper is outlined in a step wise manner starting from basic aircraft and engine thrust requirements, establishing the definition of the high speed booster interface points and its location in the engine. Thereafter, the aerodynamic 1D/2D design is carried out using the commercial throughflow tool SC90C. A number of design aspects are described, and the steps necessary to arrive at the final design are outlined. The SC90C based design is then carried over to a CFD based conceptual design tool AxCent, in which a first profiling is carried out based on a multiple circular arc blade definition. The design obtained at this point is referred to as the VINK compressor. The first stage of the compressor is then optimized using an in-house optimization tool, where the objective functions are evaluated from detailed CFD calculations. The design is improved in terms of efficiency and in terms of meeting the design criteria put on the stage in the earlier design phases. Finally, some aeromechanical design aspects of the first stage are considered. The geometry and inlet boundary conditions of the compressor are shared with the turbomachinery community on a public server. This is intended to be used as a test case for further optimization and analysis.
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| 44. |
- Julià Lluis, Enric, 1994, et al.
(författare)
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Concept design and performance evaluation of a fossil-free operated cargo ship with unlimited range
- 2020
-
Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:16, s. 1-23, s. 283-292
-
Tidskriftsartikel (refereegranskat)abstract
- To meet the IMO goals of emissions reduction in shipping, drastic actions must be taken. Wind-assisted propulsion and renewable energy sources are today discussed frequently as realistic alternatives for future ship propulsion and energy production. This study presents a new and innovative concept of a fossil-free operated cargo ship aiming to achieve an unlimited range. The purpose of the study is to present the feasibility but also the limitations of a ship propelled and operated purely on renewable energy harnessed at sea, independent from shore-based energy sources. Aside from Flettner rotors for propulsion, the ship concept incorporates photovoltaic generators, wind turbines, and a dual-mode propeller to produce energy for the auxiliary systems and for the Flettner rotors, as well as batteries to balance the energy production and consumption. The dual-mode propeller can be used for energy generation and propulsion, thus levelling out any speed drops or peaks and thereby ensuring more reliable operation. The whole system is modelled numerically, and full ship voyages are simulated using the ship performance model ShipCLEAN. Results show feasible achieved speeds on a route with realistic weather conditions. However, negative energy balances limit the pure renewable sailing conditions. Further logistic and technical challenges are discussed.
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| 45. |
- Manjate, Juvencio Arnaldo, et al.
(författare)
-
Can Energy-Aware Routing Improve the Energy Savings of Energy-Efficient Ethernet?
- 2018
-
Ingår i: IEEE Transactions on Green Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 2473-2400. ; 2:3, s. 787-794
-
Tidskriftsartikel (refereegranskat)abstract
- Telecommunication networks are over-provisioned with redundant resources in order to cope with traffic load during peak hours and to quickly recover from failures. However, much of the resources are underutilized during long periods of time, but still consuming full energy. With the growing concerns of energy waste and greenhouse gas emissions, the network design principles tend to shift towards allocation of resources on-demand for energy-efficiency. In this paper, we analyze and evaluate the performance of two different energy-saving techniques, namely energy saving topology control (ESTOP) and energy-efficient Ethernet (EEE). We investigate the energy-saving characteristics of ESTOP+EEE; the combination of ESTOP and EEE. The evaluation is conducted in OMNet++ with realistic and synthetic network topologies under varying traffic conditions. The results indicate that the combination has a significant potential for saving energy, compared to running ESTOP or EEE alone, but that the amount of energy savings depends on topology, traffic load, and the chosen target connectivity level for ESTOP. In particular, the results show that the target connectivity level needs to be carefully matched to the topology and the current traffic situation, suggesting that ESTOP+EEE would be suitable where the target connectivity level is dynamically adjusted according to traffic variations.
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| 46. |
- Engström, Rebecka Ericsdotter, et al.
(författare)
-
Connecting the resource nexus to basic urban service provision – with a focus on water-energy interactions in New York City
- 2017
-
Ingår i: Sustainable cities and society. - : Elsevier. - 2210-6707. ; 31, s. 83-94
-
Tidskriftsartikel (refereegranskat)abstract
- Urban water and energy systems are crucial for sustainably meeting basic service demands in cities. This paper proposes and applies a technology-independent “reference resource-to-service system” framework for concurrent evaluation of urban water and energy system interventions and their ‘nexus’ or ‘interlinkages’. In a concrete application, data that approximate New York City conditions are used to evaluate a limited set of interventions in the residential sector, spanning from low-flow toilet shifts to extensive green roof installations. Results indicate that interventions motivated primarily by water management goals can considerably reduce energy use and contribute to mitigation of greenhouse gas emissions. Similarly, energy efficiency interventions can considerably reduce water use in addition to lowering emissions. However, interventions yielding the greatest reductions in energy use and emissions are not necessarily the most water conserving ones, and vice versa. Useful further research, expanding the present analysis should consider a broader set of resource interactions, towards a full climate, land, energy and water (CLEW) nexus approach. Overall, assessing the impacts, trade-offs and co-benefits from interventions in one urban resource system on others also holds promise as support for increased resource efficiency through integrated decision making.
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| 47. |
- Bouchouireb, Hamza, 1991-, et al.
(författare)
-
Exploring the aero-structural-battery energy storage coupling within the early-stage development of life cycle energy optimal electric vehicles
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Life Cycle Energy Optimisation (LCEO) methodology is used to explore the coupling existing between an electric vehicle's aerodynamic shape, structural material composition and design, and the properties of its onboard battery's chemistry in order to enable the development of more sustainable vehicle configurations. To this end, a mixed integer nonlinear programming formulation of the LCEO methodology was developed to include the effects of battery energy storage systems on the Life Cycle Energy (LCE) optimal vehicle designs. In particular, the vehicle's battery size and number of such batteries needed over its life cycle were introduced as variables subject to a range and a battery cycle life constraint. The former is derived from the battery-capacity-to-structural-mass ratio of recent production vehicles, while the latter ensures that the batteries' cycle lives are sufficient for the entirety of the vehicle's use phase. Additionally, three lithium-based battery chemistries with varying properties were included: lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP) and lithium cobalt oxide (LCO); along with a closed-loop end-of-life recycling scenario for the battery materials. The results of the coupled aero-structural-battery energy storage LCE-driven design optimisations demonstrate that battery chemistry and recycling potential have a significant impact on the system's design in terms of overall LCE footprint, battery size and number, as well as aerodynamic shape. More specifically, a change in battery composition was found to lead to up to 12.5% variation in drag coefficient, while battery recycling can on average reduce a vehicle's associated LCE by 32%. Furthermore, battery material recycling was found to decrease the role played by the specific energy and cycle lives of the batteries, and increase that played by their embodied energy. Consequently, the LFP battery chemistry was found to be the best performer from an LCE perspective in the presence of battery material recycling; while the NMC chemistry was found to perform marginally better in the absence of the latter.
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| 48. |
- Killer, Marvin, et al.
(författare)
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Implementation of large-scale Li-ion battery energy storage systems within the EMEA region
- 2020
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 260
-
Tidskriftsartikel (refereegranskat)abstract
- Large-scale Lithium-ion Battery Energy Storage Systems (BESS) are gradually playing a very relevant role within electric networks in Europe, the Middle East and Africa (EMEA). The high energy density of Li-ion based batteries in combination with a remarkable round-trip efficiency and constant decrease in the levelized cost of storage have led to the recent boom of the technology. However, many of the potential applications of large-scale battery systems are not economically viable at this point in time. As a result, several BESS projects are being pushed by the industry towards specific niches which are based on revenue streams that can be rather complex than straightforward. The aim of this paper is to provide an overview of how large-scale Li-ion BESS are currently being implemented in the EMEA region, giving an answer to the following questions: what are the main use-cases of large-scale Li-ion batteries that are being implemented? What are the key factors that are enabling the deployment of BESS projects in the present markets? How can current tendencies be extrapolated to the future outlook of Li-ion BESS implementations? The large-scale energy storage market is evolving at a very fast pace, hence this review paper intends to contribute to a better understanding of the current status of Li-ion battery systems focusing on the economic feasibility that is driving the realization of Li-ion BESS projects in the EMEA region.
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| 49. |
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| 50. |
- Thulin, Oskar, 1987, et al.
(författare)
-
First and Second Law Analysis of Radical Intercooling Concepts
- 2018
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 140:8, s. 081201-081201-10
-
Tidskriftsartikel (refereegranskat)abstract
- An exergy framework was developed taking into consideration a detailed analysis of the heat exchanger (HEX) (intercooler (IC)) component irreversibilities. Moreover, it was further extended to include an adequate formulation for closed systems, e.g., a secondary cycle (SC), moving with the aircraft. Afterward, the proposed framework was employed to study two radical intercooling concepts. The first proposed concept uses already available wetted surfaces, i.e., nacelle surfaces, to reject the core heat and contributes to an overall drag reduction. The second concept uses the rejected core heat to power a secondary organic Rankine cycle and produces useful power to the aircraft-engine system. Both radical concepts are integrated into a high bypass ratio (BPR) turbofan engine, with technology levels assumed to be available by year 2025. A reference intercooled cycle incorporating a HEX in the bypass (BP) duct is established for comparison. Results indicate that the radical intercooling concepts studied in this paper show similar performance levels to the reference cycle. This is mainly due to higher irreversibility rates created during the heat exchange process. A detailed assessment of the irreversibility contributors, including the considered HEXs and SC, is made. A striking strength of the present analysis is the assessment of the component-level irreversibility rate and its contribution to the overall aero-engine losses.
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