1,022 research outputs found
Rossi (Mario G.) Ferrari Luigi Ferrari; dalle leghe Francesco bianche al partito popolare
No full textRossi (Mario G.) Ferrari Luigi Ferrari; dalle leghe Francesco bianche al partito popolare. In: Archives de sociologie des religions, n°24, 1967. p. 218
Rossi (Mario G.) Ferrari Luigi Ferrari; dalle leghe Francesco bianche al partito popolare
No full textRossi (Mario G.) Ferrari Luigi Ferrari; dalle leghe Francesco bianche al partito popolare. In: Archives de sociologie des religions, n°24, 1967. p. 218
Solid oxide fuel cell hybrid system: Control strategy for stand-alone configurations
No full textThe aim of this study is the development and testing of a control system for solidoxidefuelcellhybrid systems through dynamic simulations. Due to the complexity of these cycles, several parameters, such as the turbine rotational speed, the temperatures within the fuelcell, the differential pressure between the anodic and the cathodic side and the Steam-To-Carbon Ratio need to be monitored and kept within safe limits. Furthermore, in stand-alone conditions the system response to load variations is required to meet the global plant power demand at any time, supporting global load variations and avoiding dangerous or unstable conditions. The plant component models and their integration were carried out in previous studies. This paper focuses on the controlstrategy required for managing the net electrical power from the system, avoiding malfunctions or damage. Once the control system was developed and tuned, its performance was evaluated by simulating the transient behaviour of the whole hybrid cycle: the results for several operating conditions are presented and discussed
Advanced control approach for hybrid systems based on solid oxide fuel cells
No full textThis paper shows a new advanced control approach for operations in hybrid systems equipped with solid oxide fuel cell technology. This new tool, which combines feed-forward and standard proportional–integral techniques, controls the system during load changes avoiding failures and stress conditions detrimental to component life. This approach was selected to combine simplicity and good control performance. Moreover, the new approach presented in this paper eliminates the need for mass flow rate meters and other expensive probes, as usually required for a commercial plant. Compared to previous works, better performance is achieved in controlling fuel cell temperature (maximum gradient significantly lower than 3 K/min), reducing the pressure gap between cathode and anode sides (at least a 30% decrease during transient operations), and generating a higher safe margin (at least a 10% increase) for the Steam-to-Carbon Ratio. This new control system was developed and optimized using a hybrid system transient model implemented, validated and tested within previous works. The plant, comprising the coupling of a tubular solid oxide fuel cell stack with a microturbine, is equipped with a bypass valve able to connect the compressor outlet with the turbine inlet duct for rotational speed control. Following model development and tuning activities, several operative conditions were considered to show the new control system increased performance compared to previous tools (the same hybrid system model was used with the new control approach). Special attention was devoted to electrical load steps and ramps considering significant changes in ambient conditions
Design and testing of ejectors for hybrid systems
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Proceedings of the 1st European Fuel Cell Technology and Applications Conference 2005 - Book of Abstracts
Volume 2005, 2005, Page 250
1st European Fuel Cell Technology and Applications Conference 2005, EFC2005; Rome; Italy; 14 December 2005 through 16 December 2005; Code 67292
Design and testing of ejectors for hybrid systems (Conference Paper)
Ferrari, M.a,
Bernardi, D.b,
Massardo, A.c
a TPG, Università di Genova, Italy
b Università di Genova, Italy
Abstract
The recent developments of hybrid systems based on Solid Oxide Fuel Cell technology have focused the attention on the advantages coming from recirculations carried out by ejectors. In fact, these components join very low costs with high lifetime because they have no moving parts. While on the anodic side an ejector allows to avoid high temperature and expensive blowers to recirculate part of the exhausted gases, on the cathodic side a recirculation based on the ejector technology is so cheap and safe to justify an efficiency decrease. To improve the ejector performance inside the hybrid systems this activity has started at TPG with a preliminary design of an anodic ejector developed using a preliminary 0-D model based on the global balances of mass, momentum and energy. Then, the theoretical activity has been improved with the development of an experimental rig to test single stage ejectors for hybrid systems at different operative conditions of mass flow rates, pressures and temperatures. At first, an open circuit has been built to perform tests at atmospheric conditions in the secondary flow and connecting the primary inlet to the compressed air line. Then, to emulate a SOFC anodic recirculation, the circuit has been closed introducing a fuel cell volume in a reduced scale. This configuration is important to test ejectors at pressurized conditions both at primary and secondary ducts. Finally, the volume has been equipped and thermally insulated to test ejectors with high temperature secondary flow, necessary to reach values in similitude condition with the real ones. This test rig has been used to validate the 0-D ejector model with the objective to set the values of the coefficients used to take into account the primary momentum loss and the mixing chamber viscous pressure losses. On the other hand, a successful comparison with the experimental data, measured with the rig, has been used to validate the CFD models necessary to better investigate the fluid dynamic phenomena inside ejectors. In fact, the application of CFD validated models has allowed to improve the performance of ejectors for hybrid systems optimizing the geometry in terms of primary and secondary ducts, mixing chamber length and diffuser geometry
Comparison Between Uncontrolled and Controlled Solid Oxide Fuel Cell Hybrid Systems
No full textBecause of the high complexity of Solid Oxide Fuel Cell hybrid systems, a transient analysis is mandatory to implement a control system able to maintain safe operation during disturbances or regular operational load variations. In fact, several parameters, such as the turbine rotational speed, the surge margin, the temperatures within the fuel cell, the turbine inlet temperature, the differential pressure between the anodic and the cathodic side and the Steam-To-Carbon Ratio need to be monitored and kept within safe limits. On the other hand, the system response to load variations is required to be as quick as possible in order to meet the energy demand. To develop a control strategy for these cycles, the work starts from the implementation of a transient model necessary to simulate a hybrid system based on the tubular SOFC technology. In fact, the first goal of this work is the analysis of the response to a step decrease in the fuel mass flow rate of the uncontrolled system, focusing the attention on the time scales of the transient phenomena and discussing the results from electrochemical, fluid dynamic and thermal point of view. The simulation shows that while the cathodic side is driven only by the temperature variation, because of the rotational speed is assumed to be constant, the anodic side is characterized by three different time-scale phenomena. In fact, all the plant properties show a negligible fluid dynamic delay, a depressurization time delay and a thermal long time-scale effect mainly due to the high thermal inertia of the cell. The considerations, carried out with the uncontrolled system, are used in the second part of the work to develop a control strategy to follow the power demand over time avoiding malfunctions or risk situations. The paper focuses the attention on a detailed presentation of the control system layout based on the by-pass valve between the compressor outlet and the turbine inlet, necessary to overcome the difficulty due to the difference between the small mechanical inertia of the microturbine shaft and the very high thermal inertia of the fuel cell stack. The simulations, carried out with a load step decrease, show the transient behaviour of the controlled SOFC hybrid system, presenting, over time, the values of the main critical parameters. Finally, the paper presents the results obtained with a power step increase to investigate the limitations of this control strategy focusing the attention on the fuel cell average temperature and the fuel utilization factor
Cathode–anode side interaction in SOFC hybrid systems
No full textCathode-anode interaction, mainly based on cathode versus anode volume influence, recirculation performance, and turbomachinery integration, is an important issue for pressurised SOFC hybrid systems, and this aspect must be carefully considered to prevent fuel cell ceramic material failures through a reliable control system. Over the last 10 years, several theoretical analyses of this issue have been carried out at the University of Genoa. These interaction studies have been analysed and an experimental approach (for model validation, system development and prototype design activities) has been applied using emulator facilities or real plants. In particular, general hybrid system layouts based on the coupling of pressurized SOFC stacks of different geometries (planar, tubular, etc.) with a gas turbine bottoming cycle have been investigated using the hybrid system emulator facility of the University of Genoa. The experimental results are focused on the interaction between gas turbine and anodic circuit and on cathode-anode differential pressure behaviour for design, off-design and transient hybrid system operative conditions. The information obtained in these tests is essential to understand the main features of the variables that drive the phenomena and to design a suitable control system that can mitigate the differential pressure values during all plant operating conditions
Ferreira, Ferrari: ficções do exílio
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2015.Esta é uma leitura dos exílios de Ferreira Gullar e León Ferrari, durante as últimas ditaduras militares que tomaram conta do Cone Sul, incluindo Brasil e Argentina. Entre 1971 e 1977, Gullar passou por Moscou, Santiago, Lima e Buenos Aires, além de outras cidades, enquanto Ferrari, por sua vez, estabeleceu-se com sua família em São Paulo do final de 1976 até 1984, sendo que após esse período ainda dividiria por alguns anos a sua permanência entre a capital paulista e Buenos Aires. Alguns de seus mais notáveis trabalhos foram realizados no exílio, de modo que a configuração de uma paisagem ou cena exílica torna-se indissociável das experiências conduzidas com a linguagem. Em poucas palavras: embora marcado pela tanatopolítica castrense e pelo nomos gestor do capital global, é possível afirmar que o exílio não está dado de antemão e nem permanece sempre o mesmo, quer seja como dano ou como dádiva; é somente com a linguagem  a imagem, o sensível  que uma experiência exílica, sempre singular e radicalmente contemporânea, pode encontrar a sua superfície de exposição, quer dizer, a sua diferença. Conquanto sejam profundamente dessemelhantes, os exílios de Ferreira Gullar e León Ferrari não deixam de mostrar afinidades, sobretudo nos momentos em que suas experiências tocam um ponto comum: o espaço  um topos  a-tópico da impropriedade, da potência, da in-operatividade que, com a linguagem, resiste indomesticável às tentativas de cristalização da língua, do povo, do poder, da nação. Foucault, Saer, Coccia e outros autores franqueiam um pensamento da ficção enquanto construção contingencial capaz de desnaturalizar os usos do discurso e a teleologia que assedia constantemente a literatura, as artes, a história. De certo modo, a ficção ¬repete, expõe e portanto difere as fábulas, ao mesmo tempo em que expõe e difere a si mesma. É essa operação in-operante, esse trabalho afirmativo da negatividade que suspende a maquinaria imunitária, autonomista, da civilização ocidental e cristã.Abstract : This is a reading of both Ferreira Gullar and León Ferrari s exiles, during the last military dictatorships that took account of the Southern Cone, including Brazil and Argentina. Between 1971 and 1977, Gullar went through Moscow, Santiago, Lima and Buenos Aires, and other cities, while Ferrari settled with his family in São Paulo from late 1976 until 1984, and thereafter still divided for a few years his stay between São Paulo and Buenos Aires. Some of his most notable works were carried out in exile, so that the configuration of an exilic landscape or scene becomes inseparable from experiments conducted with language. In short, although marked by military thanatopolitics and the nomos of global capital manager, it is possible to say that exile is not given in advance and not always remains the same, whether as damage or as a gift; it is only with the language  the image, the sensible  that an exilic experience, always singular and radically contemporary, can find its exposure surface, that is, its difference. While they are profoundly dissimilar, Ferreira Gullar and León Ferrari s exiles show their affinities, particularly at times when their experiences play a common point: the space  a topos  a-topic of the impropriety, potency, of in-operativity that, together with language, resists untamable against all crystallization attempts on the idiom, people, power, and nation. Foucault, Saer, Coccia and other authors frank a thought of fiction as a contingency construction able to denature the uses of speech and the teleology that constantly haunts literature, arts, and history. In a way, fiction repeats, exposes and therefore differs fables, while exposes and differs itself. It is this in-operative operation, this affirmative work of negativity that suspends the immunitary machinery of Christian Western civilization
Flexible Micro Gas Turbine Rig for Tests on Advanced Energy Systems
No full textThe Thermochemical Power Group (TPG) of the University of Genoa, Italy, has developed a new flexible laboratory to study advanced energy systems based on micro gas turbine technology. In the laboratory a general-purpose experimental rig, based on a modified commercial 100 kW recuperated micro gas turbine, was installed and fully instrumented.
The main objectives of the laboratory is to perform experimental activities related to gas turbine based cycles in both steady-state and transient conditions. The rig layout was defined to include the effects of interaction between the turbomachines (especially the compressor) and further components. This approach is extremely significant for innovative cycle analyses, such as recuperated, humid air, and hybrid (with high temperature fuel cells) configurations.
The facility was partially funded by two Integrated Projects of the EU VI Framework Program (Felicitas and Large-SOFC) and the Italian Government (PRIN project). It was designed with a high flexibility approach including: flow control management, co-generative applications, downstream compressor volume variation, grid-connected or stand-alone operations, recuperated or simple cycles, and room temperature control. In the new EU VII Framework (E-HUB Project), the test rig has been improved with the installation of an absorption cooler to operate the system in tri-generative configuration.
The layout of the whole system, including connection pipes, valves, and instrumentation (in particular mass flow meter locations) was carefully designed to measure all the significant properties with high accuracy performance. Particular attention was devoted to component design, using CFD tools (Fluent), to perform emulation tests on high temperature fuel cell hybrid systems. For this reason, the facility was equipped with a modular cathodic vessel, an anodic recirculation loop (including a vessel and an ejector), and a steam injection system for chemical composition emulation.
To compare tests affected by a significant influence of the ambient temperature variation, such as the performance tests on the machine maximum electrical power and electrical efficiency or on the recuperator effectiveness, the rig was integrated with a compressor inlet temperature control system. This equipment is composed of three air/water heat exchangers located at the air intake, controlled valves and a variable speed pump operating in a closed loop. This circuit was designed to couple the machine air inlet with the absorption cooler.
The large number of experimental data available for the high flexibility test rig design is also used to validate both steady-state (design and off-design) and transient (also real-time) theoretical models. A good level of consistency can be achieved thanks to the complete knowledge of the test rig dimensions, volumes, masses, shaft inertia, thermal capacitances, and operating procedure. Such completeness is difficult to obtain in industrial plants, where details about equipment are often missing or confidential.
This facility is also essential to introduce undergraduate students to micro gas turbine technology, and Ph.D.s to advanced experimental activities in the same field. With this experimental rig, in addition to learning about the thermodynamic cycles and plant layouts, students can also become familiar with their materials, piping, gaskets, technology for auxiliaries, and instrumentation
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