1,721,079 research outputs found
I biocarburanti. Le filiere produttive, le tecnologie, i vantaggi ambientali e le prospettive di diffusione
No full textDistributed generation: prospects for fuel cells based micro-cogeneration systems
Full text linkDistributed generation can be an option to reduce energy consumption and facilitate the introduction of bigger amount of electricity produced with renewable energy sources.
In the first part of the thesis an overview on fossil fuels power plants and primary movers for distributed micro-cogeneration systems is given. Then, the effect of renewable energy sources on the operation of the European power plants and grid is discussed.
In the second part of the thesis generators based on PEM fuel cells are considered and analyzed from a theoretical and experimental point of view to what concerns performance and life span.
Experimental data on a micro generator are presented. Control complexity and performance degradation over time are, in particular, studied. Degradation is also studied considering the effect of load cycles profile over performance.
The research is completed with the analysis of the energy saving achievable by fuel cell micro-cogeneration systemsLa generazione distribuita di energia è da molti considerata una delle soluzioni per ridurre i consumi energetici e per agevolare l’introduzione di quote sempre più importanti di elettricità provenienti da fonti rinnovabili di energia. Nella prima parte della tesi viene fatta una panoramica sulle tecnologie oggi più adatte alla generazione distribuita e viene fatta un’analisi su alcune delle problematiche che la massiccia introduzione di elettricità da fonti rinnovabili sta comportando nella gestione della rete di distribuzione e delle centrali di produzione, a livello europeo.
Nella seconda parte delle tesi, si va ad analizzare un particolare tipo di impianto per la micro-cogenerazione distribuita: i generatori elettrici basati su celle a combustibile ad elettrolita polimerico.
Si vanno ad analizzare, sia dal punto di vista teorico che sperimentale, le prestazioni, la vita utile ed alcune delle problematiche relative al degrado funzionale nel tempo.
Si presentano dei dati sperimentali su un micro-cogeneratore di piccola taglia e se ne evidenziano le problematiche di controllo e di degrado delle prestazioni nel tempo. In particolare, a questo riguardo, vengono riportati alcuni dati sperimentali atti a valutare l’effetto dei cicli di carico sul degrado delle prestazioni delle celle.
La ricerca si completa con la presentazione di una metodologia per il calcolo del risparmio energetico in funzione delle caratteristiche del generatore e delle scelte di gestione dello stess
On Energy Diagnosis of Steam Power Plants: A Comparison Among Three Global Losses Formulations
No full textAllestimento di un banco prova per il rilievo delle prestazioni di una cella a combustibile ad elettrolita polimerico
No full textProduzione ed utilizzo oli vegetali e biodiesel a scopi energetici in Friuli Venezia Giulia. Potenzialità e prospettive economiche ed ambientali
No full textExperimental Test Facility for the Analysis of Transient Behaviour of High Temperature Fuel Cell/Gas Turbine Hybrid Power Plants
No full textPressurised high temperature fuel cells and gas turbine integrated power systems are receiving a growing attention as capable of reaching very high electrical conversion efficiency even in small size power plants. In this system the fuel and the oxidant (air) enter the cell after being compressed. The fuel oxidation reaction occurs predominantly within the fuel cell. The reaction is completed in a combustion chamber and the pressurised combustion products are exhausted through a turbine. The dynamic interdependences related to the integration of the fuel cell and the gas turbine are not completely understood and unexpected complications and dangers might arise. In fact as a consequence of both the relatively large volume of the pressurized portion of the plant and the shape of the stalled characteristic of available compressors, the plant could be affected by the inception of fluid-dynamic instabilities. In particular surge could be detected in the transient off-design operational conditions occurring during plant regulation, start up and shut down.
The paper presents a new experimental fuel cell gas turbine simulation facility that has been constructed at the Mechanical Engineering Department of the University of Trieste, Italy. The facility was designed to examine the effects of transient events on the dynamics of these systems. The theoretical analysis of the plant is completed using a dynamic model of the system purposely developed
Improving the Energy Diagnosis of Steam Power Plants Using the Lost Work Impact Formula
No full textIn this paper, the energy diagnosis improvement of an existing steam power plant is faced on the basis of the Lost work Impact Formula, developed in the ambit of thermo-economics and presented in a previous paper. Three strategies for improving diagnostic accuracy are discussed and exemplified. Some cases of simultaneous malfunctioning of two components are introduced, to test the accuracy of energy recovery evaluation when intrinsic malfunction affects more than one component. The improved results show that the effect of the functional decay can be quantified with sufficient approximation also in that case where the first diagnostic attempt did not give meaningful answers
I biocarburanti: Le filiere produttive, le tecnologie, i benefici ambientali e le prospettive di diffusione
No full textAnalisi sperimentale del funzionamento di una cella a combustibile ad elettrolita polimerico
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