| 1. |
- Bermperis, Dimitios, et al.
(författare)
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Synergies and Trade-Offs in Hybrid Propulsion Systems Through Physics-Based Electrical Component Modeling
- 2024
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Ingår i: Journal of engineering for gas turbines and power. - : American Society of Mechanical Engineers (ASME). - 0742-4795 .- 1528-8919. ; 146:1
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid-electric propulsion is recognized as an enabling technology for reducing aviation’s environmental impact. In this work, a serial/parallel hybrid configuration of a 19-passenger commuter aircraft is investigated. Two underwing-mounted turboprop engines are connected to electrical branches via generators. One rear fuselage-mounted electrically driven ducted fan is coupled with an electric motor and respective electrical branch. A battery system completes the selected architecture. Consistency in modeling accuracy of propulsion systems is aimed for by development of an integrated framework. A multipoint synthesis scheme for the gas turbine and electric fan is combined with physics-based analytical modeling for electrical components. Influence of turbomachinery and electrical power system design points on the integrated power system is examined. An opposing trend between electrical and conventional powertrain mass is driven by electric fan design power. Power system efficiency improvements in the order of 2% favor high-power electric fan designs. A trade-off in electrical power system mass and performance arises from oversizing of electrical components for load manipulation. Branch efficiency improvements of up to 3% imply potential to achieve battery mass reduction due to fewer transmission losses. A threshold system voltage of 1 kV, yielding 32% mass reduction of electrical branches and performance improvements of 1–2%, is identified. This work sets the foundation for interpreting mission-level electrification outcomes that are driven by interactions on the integrated power system. Areas of conflicting interests and synergistic opportunities are highlighted for optimal conceptual design of hybrid powertrains.
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| 2. |
- Bermperis, Dimitios, et al.
(författare)
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SYNERGIES AND TRADE-OFFS IN HYBRID PROPULSION SYSTEMS THROUGH PHYSICS-BASED ELECTRICAL COMPONENT MODELLING
- 2023
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Ingår i: Proc. ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791886939
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Konferensbidrag (refereegranskat)abstract
- Hybrid-electric propulsion is recognized as one of the enabling technologies for reducing aviation’s environmental impact. In this work a serial/parallel hybrid configuration of a 19-passenger commuter aircraft is investigated. Two underwing-mounted turboprop engines are connected to electrical branches via generators. One rear fuselage-mounted electrically driven ducted fan is coupled with an electric motor and respective electrical branch. A battery system completes the selected architecture. Consistency in modelling accuracy of propulsion systems is aimed for by development of an integrated framework. A multi-point synthesis scheme for the gas turbine and electric fan is combined with physics-based analytical modelling for electrical components. Influence of turbomachinery and electrical power system design points on the integrated power system is examined. An opposing trend between electrical and conventional powertrain mass is driven by electric fan design power. Power system efficiency improvements in the order of 2% favor high-power electric fan designs. A trade-off in electrical power system mass and performance arises from oversizing of electrical components for load manipulation. Branch efficiency improvements of up to 3% imply potential to achieve battery mass reduction due to fewer transmission losses in mission-significant segments. A threshold system voltage of 1kV, yielding 32% mass reduction of electrical branches and performance improvements of 1-2%, is defined. Above the indicated threshold, benefits are limited, and system design complexity increases unfavorably. This work sets the foundation for interpreting mission-level electrification outcomes that are driven by interactions on the integrated power system. Areas of conflicting interests and synergistic opportunities are highlighted for optimal conceptual design of hybrid powertrains.
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| 3. |
- Marzi, E., et al.
(författare)
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Power-to-Gas for energy system flexibility under uncertainty in demand, production and price
- 2023
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Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 284
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Tidskriftsartikel (refereegranskat)abstract
- The growing penetration of non-programmable renewable energy sources and the consequent fluctuations in energy prices and availability lead to the need to enhance energy system flexibility and synergies between different energy vectors. This can be reached through sector integration. Among the most relevant technologies used for this purpose, Power-to-Gas systems allow excess renewable electricity to be converted directly into fuels that can be then stored or used. A smart energy system, however, which includes these innovative solutions, requires intelligent management methods to optimize its operation. This work investigates the operational strategy of energy systems integrated with Power-to-Gas solutions for seasonal storage, by developing an optimization model for the system, formulated as Mixed-Integer Linear Programming problem. The algorithm tackles the uncertain nature of future disturbances, such as energy needs, generation and price using two-stage stochastic programming. The algorithm is tested on grid-connected and 100% renewable energy supply case studies. The novel stochastic algorithm allows a more robust optimization compared to a deterministic optimization, and system management is ensured under several future disturbances realization. Furthermore, the integration of Power-to-Gas solutions warrants the energy security of the energy systems and acts as a buffer to forestall unpredictable behavior of the disturbances.
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| 4. |
- Taha, Mohammed, et al.
(författare)
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Techno-economic evaluation of hydrogen production for airport hubs
- 2024
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Ingår i: Energy Proceedings. - : Scanditale AB.
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Konferensbidrag (refereegranskat)abstract
- Hydrogen is considered one of the most promising alternative fuels for aviation, which can be used to power aircraft and airport ground services. Onsite hydrogen production from renewables can be suitable for small- size airports, while the larger size airports can be supplied through transportation either from dedicated green hydrogen production plants or other sources of hydrogen. This paper presents a study of two hydrogen supply scenarios, one taking the small airport of Stockholm Skavsta as a case study for in-house hydrogen production. The second is evaluating offshore green hydrogen supply to the large size airport of Arlanda. The in-house hydrogen production evaluates 18 scenarios covering all possible scenarios for alkaline, PEM, and solid oxide electrolysis as production means and compressed, cryo- compressed, and liquid gas as storage, with power supply from grid and grid plus in-house solar system. The optimum production and storage facility size is determined in association with the levelized cost and carbon emissions for each scenario. For the large-size airport, the study evaluates the hydrogen supply from offshore production facilities transported as compressed, cryo-compressed, or liquid gas via offshore pipeline and onshore pipeline, Offshore pipeline and truck, Ship and onshore pipeline, or Ship and truck. The results showed the levelized cost to be between 2.93-2.44 Euro/kg H2 in the case of in-house production. Compressed hydrogen offshore and onshore pipeline is the least cost for Arlanda airport hydrogen supply. This paper demonstrates a direction for aviation sector decarbonization and establishes a pathway for airports' in-house hydrogen production and outsourced hydrogen supply.
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| 5. |
- Vouros, Stavros, et al.
(författare)
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Enabling the potential of hybrid electric propulsion through lean-burn-combustion turbofans
- 2021
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Ingår i: Journal of the Global Power and Propulsion Society. - : Global Power and Propulsion Society. - 2515-3080. ; 5, s. 164-176
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid-electric propulsion has emerged as a promising technology to mitigate the adverse environmental impact of civil aviation. Boosting conventional gas turbines with electric power improves mission performance and operability. In this work the impact of electrification on pollutant emissions and direct operating cost of geared turbofan configurations is evaluated for an 150-passenger aircraft. A baseline two-and-a-half-shaft geared turbofan, representative of year 2035 entry-into-service technology, is employed. Parallel hybridization is implemented through coupling a battery-powered electric motor to the engine low-speed shaft. A multidisciplinary design space exploration framework is employed comprising modelling methods for multi-point engine design, aircraft sizing, performance and pollutant emissions, mission and economic analysis. A probabilistic approach is developed considering uncertainties in the evaluation of direct operating cost. Sensitivities to electrical power system technology levels, as well as fuel price and emissions taxation are quantified at different time-frames. The benefits of lean direct injection are explored along short-, medium-, and long-range missions, demonstrating 32% NOx savings compared to traditional rich-burn, quick-mix, lean-burn technologies in short-range operations. The impact of electrification on the enhancement of lean direct injection benefits is investigated. For hybrid-electric powerplants, the take-off-to-cruise turbine entry temperature ratio is 2.5% lower than the baseline, extending the corresponding NOx reductions to the level of 46% in short-range missions. This work sheds light on the environmental and economic potential and limitations of a hybrid-electric propulsion concept towards a greener and sustainable civil aviation.
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| 6. |
- Vouros, Stavros, et al.
(författare)
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Impact of boundary layer ingestion on the performance of propeller systems for hybrid electric aircraft
- 2022
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Ingår i: Proceedings of the ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791885970
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Konferensbidrag (refereegranskat)abstract
- Boundary layer ingestion (BLI) has demonstrated potential for reduced thrust requirements, fuel consumption and environmental impact. An integrated approach is developed for evaluating the performance of propeller systems including BLI propulsors. A rotor model based on lifting-line theory is coupled with a high-order panel method and an integral boundary layer formulation. The impact of BLI on single propeller performance maps is quantified, with efficiencies up to 15% higher compared to uniform freestream conditions. A design space exploration framework is developed for the analysis of BLI effects at propeller system level, including the impact of weight differentiation, installation technology factors, thrust split between rotors and electrical transmission losses. A reference 19-passenger aircraft featuring two wing-mounter propellers is compared with a series of conceptual designs featuring an aftfuselage BLI propeller and two wing-mounted propellers. A system-wide power saving coefficient is derived for the quantification of performance deltas between the conceptual and the reference system, including all propulsors. For systems with BLI aerodynamic benefits entirely negated by weight penalties, and electrical transmission losses of 10%, power savings of 1.5% are accrued. In a technologically advanced system with 2% reduced thrust requirements due to BLI and 3% transmission losses, power savings rise to 6.5%. This work reveals the anticipated performance potential and limitations of BLI propeller systems for the electrified future fleet.
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| 7. |
- Vouros, Stavros, et al.
(författare)
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Teaching optimization of thermal and fluid machinery in the post-pandemic era
- 2023
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Ingår i: Proceeding of the ASME Turbo Expo 2023. - : AMER SOC MECHANICAL ENGINEERS. - 9780791886991
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Konferensbidrag (refereegranskat)abstract
- Higher education has been crucially impacted by the pandemic during the past years. Despite the associated challenges, a wide portfolio of digital literacies has been developed for the delegates. This work evaluates the introduction of digital tools into in-person education. The “Process Optimization” course at Mälardalen University is reformed to operate in a digitally enhanced classroom mode. The course covers a variety of optimization methods applied on thermal and fluid machinery such as systems of compressors, pumps and heat exchangers, heat and power plants, aircraft trajectories and propulsion systems. The constructive alignment is presented to illustrate links between learning objectives, learning activities, and assessment tasks. A series of digital tools is introduced to elevate learning experience prior, during, and after class time. Those comprise digital quizzes, a video channel, polls, a digital whiteboard, and a digital forum. The course is systematically instrumented, yielding a vast set of statistics for evaluating the effectiveness of digital tools as well as engagement levels for learners. The contribution of digitalization into standardizing the formative and summative assessment is discussed. It is observed that digital tools complement the participation into pre- and post-classroom activities. An interactive and digitalized course evaluation activity is also designed. This allowed learners and educators to productively exchange feedback in an inclusive manner. The accrued data provides insight into the impact of digitalization on the delivery of an applied engineering course. Lessons learnt comprise quantitative and qualitative outcomes arising from the perspectives of both learners and teachers. Guidelines and recommended practices are provided for the penetration of digital tools into synchronous and asynchronous learning activities. This paper identifies opportunities as well as space for improvement arising from the penetration of digital tools into the new era for education.
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