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  • 1
    Online Resource
    Online Resource
    Emerald ; 2008
    In:  Aircraft Engineering and Aerospace Technology Vol. 80, No. 2 ( 2008-03-21), p. 139-157
    In: Aircraft Engineering and Aerospace Technology, Emerald, Vol. 80, No. 2 ( 2008-03-21), p. 139-157
    Type of Medium: Online Resource
    ISSN: 0002-2667
    Language: English
    Publisher: Emerald
    Publication Date: 2008
    detail.hit.zdb_id: 241346-2
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  • 2
    Online Resource
    Online Resource
    Emerald ; 2008
    In:  Aircraft Engineering and Aerospace Technology Vol. 80, No. 3 ( 2008-05-16), p. 280-294
    In: Aircraft Engineering and Aerospace Technology, Emerald, Vol. 80, No. 3 ( 2008-05-16), p. 280-294
    Abstract: To advance the design of heat exchanged gas turbine propulsion aeroengines utilising experience gained from early development testing, and based on technologies prevailing in the 1970‐2000 time frame. Design/methodology/approach With emphasis on recuperated helicopter turboshaft engines, particularly in the 1,000 hp (746 kW) class, detailed performance analyses, parametric trade‐off studies, and overall power plant layouts, based on state‐of‐the‐art turbomachinery component efficiencies and high‐temperature heat exchanger technologies, were undertaken for several engine configuration concepts. Findings Using optimised cycle parameters, and the selection of a light weight tubular heat exchanger concept, an attractive engine architecture was established in which the recuperator was fully integrated with the engine structure. This resulted in a reduced overall engine weight and lower specific fuel consumption, and represented a significant advancement in technology from the modified simple‐cycle engines tested in the late 1960s. Practical implications While heat exchanged engine technology advancements were projected, there were essentially two major factors that essentially negated the continued study and development of recuperated aeroengines, namely again as mentioned in Part I, the reduced fuel consumption was not regarded as an important economic factor in an era of low‐fuel cost, and more importantly in this time frame very significant simple‐cycle engine performance advancements were made with the use of significantly higher pressure ratios and increased turbine inlet temperatures. Simply stated, recuperated variants could not compete with such a rapidly moving target. Originality/value Establishing an engine design concept in which the recuperator was an integral part of the engine structure to minimise the overall power plant weight was regarded as a technical achievement. Such an approach, together with the emergence of lighter weight recuperators of assured structural integrity, would find acceptance around the year 2000 when there was renewed interest in the use of more efficient heat exchanged variants towards the future goal of establishing “greener” aeroengines, and this is discussed in Part III of this paper.
    Type of Medium: Online Resource
    ISSN: 0002-2667
    Language: English
    Publisher: Emerald
    Publication Date: 2008
    detail.hit.zdb_id: 241346-2
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  • 3
    Online Resource
    Online Resource
    Emerald ; 2008
    In:  Aircraft Engineering and Aerospace Technology Vol. 80, No. 4 ( 2008-07-04), p. 408-426
    In: Aircraft Engineering and Aerospace Technology, Emerald, Vol. 80, No. 4 ( 2008-07-04), p. 408-426
    Abstract: This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on reduced emissions, lower fuel burn, and less noise. Design/methodology/approach Aeroengine performance analyses were carried out covering a wide range of parameters for more complex thermodynamic cycles. This led to the identification of major component features and the establishing of preconceptual aeroengine layout concepts for various types of recuperated and ICR variants. Findings Novel aeroengine architectures were identified for heat exchanged turboshaft, turboprop, and turbofan variants covering a wide range of applications. While conceptual in nature, the results of the analyses and design studies generally concluded that heat exchanged engines represent a viable solution to meet demanding defence and commercial aeropropulsion needs in the 2015‐2020 timeframe, but they would require extensive development. Research limitations/implications As highlighted in Parts I and II, early development work was focused on the use of recuperation, but this is only practical with compressor pressure ratios up to about 10. For today's aeroengines with pressure ratios up to about 50, improvement in SFC can only be realised by incorporating intercooling and recuperation. The new aeroengine concepts presented are clearly in an embryonic stage, but these should enable gas turbine and heat exchanger specialists to advance the technology by conducting more in‐depth analytical and design studies to establish higher efficiency and “greener” gas turbine aviation propulsion systems. Originality/value It is recognised that meeting future environmental and economic requirements will have a profound effect on aeroengine design and operation, and near‐term efforts will be focused on improving conventional simple‐cycle engines. This paper has addressed the longer‐term potential of heat exchanged aeroengines and has discussed novel design concepts. A deployment strategy, aimed at gaining confidence with emphasis placed on assuring engine reliability, has been suggested, with the initial development and flight worthiness test of a small recuperated turboprop engine for UAVs, followed by a larger recuperated turboshaft engine for a military helicopter, and then advancement to a larger and far more complex ICR turbofan engine.
    Type of Medium: Online Resource
    ISSN: 0002-2667
    Language: English
    Publisher: Emerald
    Publication Date: 2008
    detail.hit.zdb_id: 241346-2
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  • 4
    Online Resource
    Online Resource
    Elsevier BV ; 2013
    In:  Applied Energy Vol. 105 ( 2013-5), p. 369-379
    In: Applied Energy, Elsevier BV, Vol. 105 ( 2013-5), p. 369-379
    Type of Medium: Online Resource
    ISSN: 0306-2619
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2013
    detail.hit.zdb_id: 190936-8
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  • 5
    Online Resource
    Online Resource
    Elsevier BV ; 2005
    In:  Applied Thermal Engineering Vol. 25, No. 14-15 ( 2005-10), p. 2054-2071
    In: Applied Thermal Engineering, Elsevier BV, Vol. 25, No. 14-15 ( 2005-10), p. 2054-2071
    Type of Medium: Online Resource
    ISSN: 1359-4311
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2005
    detail.hit.zdb_id: 2019322-1
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  • 6
    Online Resource
    Online Resource
    Elsevier BV ; 2003
    In:  Applied Thermal Engineering Vol. 23, No. 10 ( 2003-7), p. 1275-1293
    In: Applied Thermal Engineering, Elsevier BV, Vol. 23, No. 10 ( 2003-7), p. 1275-1293
    Type of Medium: Online Resource
    ISSN: 1359-4311
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2003
    detail.hit.zdb_id: 2019322-1
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  • 7
    Online Resource
    Online Resource
    ASME International ; 2011
    In:  Journal of Engineering for Gas Turbines and Power Vol. 133, No. 2 ( 2011-02-01)
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 133, No. 2 ( 2011-02-01)
    Abstract: This paper is focused on the performance of the 1 MW plant designed and developed by Rolls-Royce Fuel Cell Systems Limited. The system consists of a two stage turbogenerator coupled with pressure vessels containing the fuel cell stack, internal reformer, cathode ejector, anode ejector, and off-gas burner. While the overall scheme is relatively simple, due to the limited number of components, the interaction between the components is complex and the system behavior is determined by many parameters. In particular, two important subsystems such as the cathode and the anode recycle loops must be carefully analyzed also considering their interaction with and influence on the turbogenerator performance. The system performance model represents the whole, and each physical component is modeled in detail as a subsystem. The component models have been validated or are under verification. The model provides all the operating parameters in each characteristic point of the plant and a complete distribution of thermodynamics and chemical parameters inside the solid oxide fuel cell (SOFC) stack and reformer. In order to characterize the system behavior, its operating envelope has been calculated taking into account the effect of ambient temperature and pressure, as described in the paper. Given the complexity of the system, various constraints have to be considered in order to obtain a safe operating condition not only for the system as a whole but also for each of its parts. In particular each point calculated has to comply with several constraints such as stack temperature distribution, maximum and minimum temperatures, and high and low pressure spool maximum rotational speeds. The model developed and the results presented in the paper provide important information for the definition of an appropriate control strategy and a first step in the development of a robust and optimized control system.
    Type of Medium: Online Resource
    ISSN: 0742-4795 , 1528-8919
    Language: English
    Publisher: ASME International
    Publication Date: 2011
    detail.hit.zdb_id: 2010437-6
    detail.hit.zdb_id: 165371-4
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  • 8
    Online Resource
    Online Resource
    ASME International ; 2008
    In:  Journal of Fuel Cell Science and Technology Vol. 5, No. 4 ( 2008-11-01)
    In: Journal of Fuel Cell Science and Technology, ASME International, Vol. 5, No. 4 ( 2008-11-01)
    Abstract: The aim of this work is the experimental validation of a steady-state and transient ejector model for high temperature fuel cell hybrid system applications. This is a mandatory step in performing the steady state and the transient analysis of the whole plant to avoid critical situations and to develop the control system. The anodic recirculation test rig, developed at TPG-University of Genoa, and already used in previous works to validate the ejector design models (0D and computational fluid dynamics), was modified and used to perform tests at transient conditions with the aim of ejector transient model validation. This ejector model, based on a “lumped volume” technique, has been successfully validated against experimental data at steady-state and transient conditions using air or CO2 at room temperature and at 150°C in the secondary duct inlet. Then, the ejector model was integrated with the models of the connecting pipes, and with the volume simulation tool, equipped with an outlet valve, in order to generate an anodic recirculation model. Also in this case, the theoretical results were successfully compared with the experimental data obtained with the test rig. The final part of the paper is devoted to the results obtained with square wave functions generated in the ejector primary pressure. To study the effects of possible fast pressure variations in the fuel line (ejector primary line), the test rig was equipped with a servo-controlled valve upstream of the ejector primary duct to generate different frequency pressure oscillations. The results calculated with the recirculation model at these conditions were successfully compared with the experimental data too.
    Type of Medium: Online Resource
    ISSN: 1550-624X , 1551-6989
    Language: English
    Publisher: ASME International
    Publication Date: 2008
    detail.hit.zdb_id: 2168548-4
    detail.hit.zdb_id: 2166032-3
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  • 9
    Online Resource
    Online Resource
    ASME International ; 2010
    In:  Journal of Fuel Cell Science and Technology Vol. 7, No. 2 ( 2010-04-01)
    In: Journal of Fuel Cell Science and Technology, ASME International, Vol. 7, No. 2 ( 2010-04-01)
    Abstract: The University of Genoa (TPG) has designed and developed an innovative test rig for high temperature fuel cell hybrid system physical emulation. It is based on the coupling of a modified commercial 100 kW recuperated micro gas turbine to a special modular volume designed for the experimental analysis of the interaction between different dimension fuel cell stacks and turbomachines. This new experimental approach that generates reliable results as a complete test rig also allows investigation of high risk situations with more flexibility without serious and expensive consequences to the equipment and at a very low cost compared with real hybrid configurations. The rig, developed with the support of the European Integrated Project “FELICITAS,” is under exploitation and improvement in the framework of the new European Integrated Project “LARGE-SOFC” started in January 2007. The layout of the system (connecting pipes, valves, and instrumentation) was carefully designed to minimize the pressure loss between compressor outlet and turbine inlet to have the highest plant flexibility. Furthermore, the servocontrolled valves are useful for performing tests at different operative conditions (i.e., pressures, temperatures, and pressure losses), focusing the attention on surge and thermal stress prevention. This work shows the preliminary data obtained with the machine connected to the volume for the test rig safe management to avoid surge or excessive stress, especially during the critical operative phases (i.e., start-up and shutdown). Finally, the attention is focused on the valve control system developed to emulate the start-up and shutdown phases for high temperature fuel cell hybrid systems. It is necessary to manage the flows in the connecting pipes, including an apt recuperator bypass, to perform a gradual heating up and cooling down as requested during these phases. It is an essential requirement to avoid thermal stress for the fuel cell stack. For this reason, during the start-up, the volume is gradually heated by the compressor outlet flow followed by a well managed recuperator outlet flow and vice versa for the shutdown. Furthermore, operating with a constant rotational speed control system, the machine load is used to reach higher temperature values typical of these kinds of systems.
    Type of Medium: Online Resource
    ISSN: 1550-624X , 1551-6989
    Language: English
    Publisher: ASME International
    Publication Date: 2010
    detail.hit.zdb_id: 2168548-4
    detail.hit.zdb_id: 2166032-3
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  • 10
    Online Resource
    Online Resource
    ASME International ; 2012
    In:  Journal of Fuel Cell Science and Technology Vol. 9, No. 1 ( 2012-02-01)
    In: Journal of Fuel Cell Science and Technology, ASME International, Vol. 9, No. 1 ( 2012-02-01)
    Abstract: This paper presents the steady state and transient model of a natural gas fuel processing system of a solid oxide fuel cell (SOFC) hybrid system, and its validation using data obtained through the use of a real plant. The model was developed by the Thermochemical Power Group of the University of Genoa, Italy, using the in-house tool TRANSEO working in the Matlab/Simulink environment, whereas the real plant was designed and built by Rolls-Royce Fuel Cell Systems Limited (RRFCS) to feed a 250 kWe SOFC hybrid system with a methane stream undergoing requirements about composition, pressure, and temperature. The paper presents in detail the fuel processing system and, with particular emphasis, the selective catalytic sulphur oxidation (SCSO) and the catalytic partial oxidation (CPOx) subsystems. Thanks to the collaboration between the University and RRFCS, in the model the real physical properties of the different materials and geometry of the components have been carefully used. The transient model has been fully validated against experimental data obtained from long duration tests, which included the warm-up, part and full load operation, and cool-down phases of the external fuel processing system. In the validation process both gas and wall temperatures have been taken into account. The transient model has shown the ability to predict satisfactorily the plant behavior both at steady-state and transient conditions. The validated model is now under further development to be used for dynamic control system applications.
    Type of Medium: Online Resource
    ISSN: 1550-624X , 1551-6989
    Language: English
    Publisher: ASME International
    Publication Date: 2012
    detail.hit.zdb_id: 2168548-4
    detail.hit.zdb_id: 2166032-3
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