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  • 1.
    Aslanidou, Ioanna
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Pontika, E.
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    Zimmerman, Nathan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kalfas, A. I.
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Teaching gas turbine technology to undergraduate students in Sweden2018In: Proceedings of the ASME Turbo Expo, American Society of Mechanical Engineers (ASME) , 2018, Vol. 6Conference paper (Refereed)
    Abstract [en]

    This paper addresses the teaching of gas turbine technology in a third-year undergraduate course in Sweden and the challenges encountered. The improvements noted in the reaction of the students and the achievement of the learning outcomes is discussed. The course, aimed at students with a broad academic education on energy, is focused on gas turbines, covering topics from cycle studies and performance calculations to detailed design of turbomachinery components. It also includes economic aspects during the operation of heat and power generation systems and addresses combined cycles as well as hybrid energy systems with fuel cells. The course structure comprises lectures from academics and industrial experts, study visits, and a comprehensive assignment. With the inclusion of all of these aspects in the course, the students find it rewarding despite the significant challenges encountered. An important contribution to the education of the students is giving them the chance, stimulation, and support to complete an assignment on gas turbine design. Particular attention is given on striking a balance between helping them find the solution to the design problem and encouraging them to think on their own. Feedback received from the students highlighted some of the challenges and has given directions for improvements in the structure of the course, particularly with regards to the course assignment. This year, an application developed for a mobile phone in the Aristotle University of Thessaloniki for the calculation of engine performance will be introduced in the course. The app will have a supporting role during discussions and presentations in the classroom and help the students better understand gas turbine operation. This is also expected to reduce the workload of the students for the assignment and spike their interest.

  • 2.
    Aslanidou, Ioanna
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Rahman, Moksadur
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Oostveen, Mark
    Micro Turbine Technology bv, Eindhoven, Netherlands.
    Olsson, Tomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE SICS, Västerås, Sweden.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Towards an Integrated Approach for Micro Gas Turbine Fleet Monitoring, Control and Diagnostics2018Conference paper (Refereed)
    Abstract [en]

    Real-time engine condition monitoring and fault diagnostics results in reduced operating and maintenance costs and increased component and engine life. Prediction of faults can change the maintenance model of a system from a fixed maintenance interval to a condition based maintenance interval, further decreasing the total cost of ownership of a system. Technologies developed for engine health monitoring and advanced diagnostic capabilities are generally developed for larger gas turbines, and generally focus on a single system; no solutions are publicly available for engine fleets. This paper presents a concept for fleet monitoring finely tuned to the specific needs of micro gas turbines. The proposed framework includes a physics-based model and a data-driven model with machine learning capabilities for predicting system behaviour, combined with a diagnostic tool for anomaly detection and classification. The integrated system will develop advanced diagnostics and condition monitoring for gas turbines with a power output under 100 kW.

  • 3.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zhang, Yang
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Flexibility Services Provided by Building Thermal Inertia2018Conference paper (Refereed)
  • 4.
    Cuneo, A.
    et al.
    Thermochemical Power Group, Università di Genova, Italy.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Tucker, D.
    U.S. DOE National Energy Technology Laboratory, Morgantown, United States.
    Sorce, A.
    Thermochemical Power Group, Università di Genova, Italy.
    Gas turbine size optimization in a hybrid system considering SOFC degradation2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 230, p. 855-864Article in journal (Refereed)
    Abstract [en]

    The coupling of a pressurized solid oxide fuel cell (SOFC) and a gas turbine has been proven to result in extremely high efficiency and reduced emissions. The presence of the gas turbine can improve system durability compared to a standalone SOFC, because the turbomachinery can supply additional power as the fuel cell degrades to meet the power request. Since performance degradation is an obstacles to SOFC systems commercialization, the optimization of the hybrid system to mitigate SOFC degradation effects is of great interest. In this work, an optimization approach was used to innovatively study the effect of gas turbine size on system durability for a 400 kW fuel cell stack. A larger turbine allowed a bigger reduction in SOFC power before replacing the stack, but increased the initial capital investment and decreased the initial turbine efficiency. Thus, the power ratio between SOFC and gas turbine significantly influenced system economic results.

  • 5.
    Rahman, Moksadur
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Xin, Zhao
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Diagnostics-Oriented Modelling of Micro Gas Turbines for Fleet Monitoring and Maintenance Optimization2018In: Processes, ISSN 2227-9717, E-ISSN 1099-5862, Vol. 6, no 11Article in journal (Refereed)
    Abstract [en]

    The market for the small-scale micro gas turbine is expected to grow rapidly in the coming years. Especially, utilization of commercial off-the-shelf components is rapidly reducing the cost of ownership and maintenance, which is paving the way for vast adoption of such units. However, to meet the high-reliability requirements of power generators, there is an acute need of a real-time monitoring system that will be able to detect faults and performance degradation, and thus allow preventive maintenance of these units to decrease downtime. In this paper, a micro gas turbine based combined heat and power system is modelled and used for development of physics-based diagnostic approaches. Different diagnostic schemes for performance monitoring of micro gas turbines are investigated.

  • 6.
    Rossi, I.
    et al.
    University of Genoa, Genova, Italy.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Traverso, A.
    University of Genoa, Genova, Italy.
    Advanced Control for Clusters of SOFC/Gas Turbine Hybrid Systems2018In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 140, no 5, article id 051703Article in journal (Refereed)
    Abstract [en]

    The use of model predictive control (MPC) in advanced power systems can be advantageous in controlling highly coupled variables and optimizing system operations. Solid oxide fuel cell/gas turbine (SOFC/GT) hybrids are an example where advanced control techniques can be effectively applied. For example, to manage load distribution among several identical generation units characterized by different temperature distributions due to different degradation paths of the fuel cell stacks. When implementing an MPC, a critical aspect is the trade-off between model accuracy and simplicity, the latter related to a fast computational time. In this work, a hybrid physical and numerical approach was used to reduce the number of states necessary to describe such complex target system. The reduced number of states in the model and the simple framework allow real-time performance and potential extension to a wide range of power plants for industrial application, at the expense of accuracy losses, discussed in the paper. 

  • 7.
    Zaccaria, Valentina
    et al.
    U.S. Department of Energy, US.
    Branum, Zachary
    Arizona State University, USA.
    Tucker, David
    U.S. Department of Energy, US.
    Fuel Cell Temperature Control with a Pre-Combustor in SOFC Gas Turbine Hybrids during Load Changes2017In: Journal of electrochemical energy conversion and storage, ISSN 2381-6872, Vol. 14, p. 031006-031014Article in journal (Refereed)
    Abstract [en]

    The use of high temperature fuel cells, such as Solid Oxide Fuel Cells (SOFCs), for power generation is considered a very efficient and clean solution to conservation of energy resources. When the SOFC is coupled with a gas turbine, the global system efficiency can go beyond 70% on natural gas LHV. However, durability of the ceramic material and system operability can be significantly penalized by thermal stresses due to temperature fluctuations and non-even temperature distributions. Thermal management of the cell during load following is therefore essential.The purpose of this work was to develop and test a pre-combustor model for real-time applications in hardware-based simulations, and to implement a control strategy to keep constant cathode inlet temperature during different operative conditions. The real-time model of the pre-combustor was incorporated into the existing SOFC model and tested in a hybrid system facility, where a physical gas turbine and hardware components were coupled with a cyber-physical fuel cell for flexible, accurate, and cost-reduced simulations.The control of the fuel flow to the pre-combustor was proven to be effective in maintaining a constant cathode inlet temperature during a step change in fuel cell load. With a 20 A load variation, the maximum temperature deviation from the nominal value was below 0.3% (3K). Temperature gradients along the cell were maintained below 10 K/cm. An efficiency analysis was performed in order to evaluate the impact of the pre-combustor on the overall system efficiency.

  • 8.
    Zaccaria, Valentina
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Cuneo, Alessandra
    University of Genoa, Italy.
    Sorce, Alessandro
    University of Genoa, Italy.
    Influence of multiple degrading components on fuel cell gas turbine hybrid systems lifetime2018In: Proceedings of GPPS Forum 18 Global Power and Propulsion Society Zurich, 10th-12th January 2018, 2018Conference paper (Refereed)
    Abstract [en]

    Energy system reliability and operational cost depend highly on the performance degradation experienced by system components. In complex systems, degradation of each single component affects matching and interactions of different system parts. Gas turbine fuel cell hybrid systems combine two different technologies to produce power with an extremely high conversion efficiency. Severe performance decay over time currently limits high temperature fuel cells lifetime; although at a different rate, gas turbine engines also experience gradual deterioration phenomena such as erosion, corrosion, and creep. This work aims at evaluating, for the first time, the complex performance interaction between degrading components in a hybrid system. The effect of deterioration in gas turbine pressure ratio and efficiency on fuel cell performance was analyzed, and at the same time, the impact of the degrading fuel cell thermal output on turbine blade aging was modeled to estimate a remaining useful lifetime.

  • 9.
    Zaccaria, Valentina
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dik, Andreas
    Mälardalen University, School of Business, Society and Engineering.
    Bitén, Nikolas
    Mälardalen University, School of Business, Society and Engineering.
    Aslanidou, Ioanna
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Conceptual Design of a 3-Shaft Turbofan Engine with Reduced Fuel Consumption for 20252017In: Energy Procedia / [ed] Elsevier, 2017Conference paper (Refereed)
    Abstract [en]

    In the past decade, aircraft fuel burn has been continually decreased, mainly by improving thermal and propulsion efficiencies with consequent decrement in specific fuel consumption. In view of future emission specifications, the requirements for SFC in the forthcoming years are expected to become more stringent. In this paper, a preliminary design of a turbofan engine for entry in service in 2025 was performed. The design of a baseline 2010 EIS engine was improved according to 2025 specifications. A thermodynamic analysis was carried out to select optimal jet velocity ratio, pressure ratio, and temperatures with the goal of minimizing specific fuel consumption. A gas path layout was generated and an aerodynamic analysis was performed to optimize the engine stage by stage design. The optimization resulted in a 3-shaft turbofan jet engine with a 21% increase in fan diameter, a 2.2% increment in engine length, and a fuel burn improvement of 11% compared to the baseline engine, mainly due to an increment in propulsive efficiency. A sensitivity analysis was also conducted to highlight what the focus of technology development should be.

  • 10.
    Zaccaria, Valentina
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stenfelt, Mikael
    Mälardalen University, School of Business, Society and Engineering.
    Aslanidou, Ioanna
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Fleet monitoring and diagnostics framework based on digital twin of aero-engines2018In: Proceedings of the ASME Turbo Expo, American Society of Mechanical Engineers (ASME) , 2018, Vol. 6Conference paper (Refereed)
    Abstract [en]

    Monitoring aircraft performance in a fleet is fundamental to ensure optimal operation and promptly detect anomalies that can increase fuel consumption or compromise flight safety. Accurate failure detection and life prediction methods also result in reduced maintenance costs. The major challenges in fleet monitoring are the great amount of collected data that need to be processed and the variability between engines of the fleet, which requires adaptive models. In this paper, a framework for monitoring, diagnostics, and health management of a fleet of aircrafts is proposed. The framework consists of a multi-level approach: starting from thresholds exceedance monitoring, problematic engines are isolated, on which a fault detection system is then applied. Different methods for fault isolation, identification, and quantification are presented and compared, and the related challenges and opportunities are discussed. This conceptual strategy is tested on fleet data generated through a performance model of a turbofan engine, considering engine-to-engine and flight-to-flight variations and uncertainties in sensor measurements. Limitations of physics-based methods and machine learning techniques are investigated and the needs for fleet diagnostics are highlighted. 

  • 11.
    Zaccaria, Valentina
    et al.
    University of Genova, Italy.
    Traverso, Alberto
    University of Genova, Italy.
    Tucker, David
    U.S. Department of Energy, US.
    Advanced gas turbine hybrid power systems to improve SOFC economic viability2017In: Journal of the Global Power and Propulsion Society, ISSN 2515-3080, Vol. 1, p. 28-40Article in journal (Refereed)
    Abstract [en]

    Coupling a solid oxide fuel cell (SOFC) with a gas turbineprovides a substantial increment in system efficiency comparedto the separate technologies, which can potentiallyintroduce economic benefits and favor an early market penetrationof fuel cells. Currently, the economic viability of suchsystems is limited by fuel cell short lifetime due to a progressiveperformance degradation that leads to cell failure.Mitigating these phenomena would have a significant impacton system economic feasibility. In this study, the lifetime of astandalone, atmospheric SOFC system was compared to apressurized SOFC gas turbine hybrid and an economic analysiswas performed. In both cases, the power production wasrequired to be constant over time, with significantly differentresults for the two systems in terms of fuel cell operating life,system efficiency, and economic return. In the hybrid system,an extended fuel cell lifetime is achieved while maintaininghigh system efficiency and improving economic performance.In this work, the optimal power density was determined forthe standalone fuel cell in order to have the best economicperformance. Nevertheless, the hybrid system showed bettereconomic performance, and it was less affected by the stackcost.

  • 12.
    Zaccaria, Valentina
    et al.
    U.S. Department of Energy, United States.
    Tucker, David
    U.S. Department of Energy, United States.
    Traverso, Alberto
    University of Genoa, Italy.
    Transfer function development for SOFC/GT hybrid systems control using cold air bypass2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 165, p. 695-706Article in journal (Refereed)
    Abstract [en]

    Fuel cell gas turbine hybrids present significant challenges in terms of system control because of the couplingof different time-scale phenomena. Hence, the importance of studying the integrated systemdynamics is critical. With the aim of safe operability and efficiency optimization, the cold air bypass valvewas considered an important actuator since it affects several key parameters and can be very effective incontrolling compressor surge. Two different tests were conducted using a cyber-physical approach. TheHybrid Performance (HyPer) facility couples gas turbine equipment with a cyber physical solid oxide fuelcell in which the hardware is driven by a numerical fuel cell model operating in real time. The tests wereperformed moving the cold air valve from the nominal position of 40% with a step of 15% up and down,while the system was in open loop, i.e. no control on turbine speed or inlet temperature. The effect of thevalve change on the system was analyzed and transfer functions were developed for several importantvariables such as cathode mass flow, total pressure drop and surge margin. Transfer functions can showthe response time of different system variables, and are used to characterize the dynamic response of theintegrated system. Opening the valve resulted in an immediate positive impact on pressure drop andsurge margin. A valve change also significantly affected fuel cell temperature, demonstrating that the coldair bypass can be used for thermal management of the cell.

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