Global ETD Search

1	Thermoeconomic Modeling and Parametric Study of Hybrid Solid Oxide Fuel Cell – Gas Turbine – Steam Turbine Power Plants Ranging from 1.5 MWe to 10 MWe Arsalis, Alexandros 15 February 2007 (has links) Detailed thermodynamic, kinetic, geometric, and cost models are developed, implemented, and validated for the synthesis/design and operational analysis of hybrid solid oxide fuel cell (SOFC) – gas turbine (GT) – steam turbine (ST) systems ranging in size from 1.5 MWe to 10 MWe. The fuel cell model used in this thesis is based on a tubular Siemens-Westinghouse-type SOFC, which is integrated with a gas turbine and a heat recovery steam generator (HRSG) integrated in turn with a steam turbine cycle. The SOFC/GT subsystem is based on previous work done by Francesco Calise during his doctoral research (Calise, 2005). In that work, a HRSG is not used. Instead, the gas turbine exhaust is used by a number of heat exchangers to preheat the air and fuel entering the fuel cell and to provide energy for district heating. The current work considers instead the possible benefits of using the exhaust gases in an HRSG in order to produce steam which drives a steam turbine for additional power output. Four different steam turbine cycles are considered in this M.S. thesis work: a single-pressure, a dual-pressure, a triple-pressure, and a triple-pressure with reheat. The models have been developed to function both at design (full load) and off-design (partial load) conditions. In addition, different solid oxide fuel cell sizes are examined to assure a proper selection of SOFC size based on efficiency or cost. The thermoeconomic analysis includes cost functions developed specifically for the different system and component sizes (capacities) analyzed. A parametric study is used to determine the most viable system/component syntheses/designs based on maximizing total system efficiency or minimizing total system life cycle cost. / Master of Science hybrid fuel cell systems Design synthesis thermodynamic analysis Solid oxide fuel cells (SOFC) thermoeconomic analysis
2	CFD Analysis of the Performance of passive H2 Recirculation Jet Pumps for FC Systems Maroni, Adrian, Hrdlicka, Jiri, von Unwerth, Thomas 27 May 2022 (has links) Jet pumps are among the components of automotive FC systems (FCS) whose design need to be optimally tailored in order to improve the system efficiency. We had concluded that the ejector CFD model needed to optimize the design had to meet the requirements of being both complete enough, so that a realistic simulation of the FC system is attained, and computationally light, so that the CFD computations could be run embeded into real-time dynamic simulations of the FCS anode loop. Whereas we previously employed unstructured tetrahedral meshes, leading to excessive cell counts, our present work involves block-structured grids of purely hexahedral cells, resulting in a cell count an order of magnitude smaller. To ease our block-structure strategy, the previous geometry was slightly simplified. Our results agree with performance data already published. / Strahlpumpen gehören zu den Komponenten von Automotive FC-Systemen (FCS), deren Konstruktion optimal zugeschnitten werden muss, um die Systemeffizienz zu verbessern. Wir hatten zu dem Schluss gekommen, dass das Ejector CFD-Modell, das zur Optimierung des Designs benötigte, die Anforderungen des Seins vollständig genug erfüllen musste, so dass eine realistische Simulation des FC-Systems erreicht wird, und rechenlich leicht, so dass die CFD-Berechnungen eingebettet werden könnten Echtzeit-dynamische Simulationen der FCS-Anodenschleife. Während wir zuvor unstrukturierte Tetraedral-Meshes eingesetzt hatten, was zu übermäßigen Zellzählungen führte, beinhaltet unsere vorliegende Arbeit blockstrukturierte Gitter aus rein hexaedrischen Zellen, was zu einer Zelle führt, die eine größere Größenordnung darstellt. Um unsere Blockstrukturstrategie zu erleichtern, wurde die vorherige Geometrie leicht vereinfacht. Unsere Ergebnisse stimmen mit bereits veröffentlichten Leistungsdaten überein. Brennstoffzellensystem, CFD info:eu-repo/classification/ddc/620 ddc:620
3	Energy management of lossy multi-port to fuel cell-based systems / Gestion de l'énergie d'un système multi-port à pertes intégrant une pile à combustible Ramirez Rivera, Victor Manuel 16 May 2014 (has links) Dans de nombreux réseaux, la régulation efficace du transfert d'énergie entre les sous-systèmes de production, de stockage et d'utilisation demeure un sujet difficile à traiter. Dans cette thèse on a proposent une nouvelle stratégie pour atteindre cet objectif, ainsi que sa mise en œuvre. Le dispositif est appelé routeur d'énergie dynamique (RED), parce que, contrairement à la pratique actuelle, l'asservissement de l'écoulement de puissance se fait sans s'appuyer sur des hypothèses stationnaire. Une hypothèse clé pour le bon fonctionnement du RED est que la dissipation du système est négligeable. Toutefois, en présence de pertes en ligne le RED initial n'est plus opérationnel, car il est base sur l'hypothèse clé de non dissipation des interconnections. Dans ce travail, un nouveau RED prenant en compte la présence de pertes est proposé. Des preuves de l'amélioration des performances sont présentées en simulation comme en expérimentation. Un complément de ce travail a été réalisée sur l'estimation des paramètres d'une pile à combustible du type Polymer Exchange Membrane (PEM) dans le but de concevoir un estimateur convergeant sur un grand domaine (convergence globale). Ce dernier utilise des principes d'immersion et d'invariance développés récemment dans la théorie des asservissements. / Efficient regulation of the energy transfer between generating, storage and load subsystems is a topic of current practical interest. A new strategy to achieve this objective, together with its corresponding power electronics implementation, was recently proposed in this thesis work. The device is called dynamic energy router (DER) because, in contrast with current practice, the regulation of the direction and rate of change of the power flow is done without relying on steady–state considerations. A key assumption for the correct operation of the DER is that dissipation in the system is negligible. Unfortunately, in the presence of dissipation the original DER ceases to be operational. In this thesis a new DER that takes into account the presence of losses is proposed. Simulation and experimental evidence of the performance improvement with the new DER are presented. As a complement of this work a global convergent estimator of parameters of Polymer Exchange Membrane Fuel Cell (PEMFC) was designing by using the principles or “Immersion and Invariance” recently reported in control theory. Commande des systèmes non linéaires Système de la pile à combustible Gestion de l'énergie Électronique de puissance Commande passive Nonlinear control Fuel cell systems Energy managment Power electronics Passivity control
4	System studies of MCFC power plants Fillman, Benny January 2005 (has links) <p>Die Brennstoffzelle ist ein elektrochemischer Reaktor und wandelt chemisch gebundene Energie direkt in elektrische Energie um. In der stationären Energieerzeugung ist der Brennstoffzellenstapel selbst nur ein kleiner Bestandteil des vollständigen Systems. Die Integration aller zusätzlichen Bestandteile, der Peripheriegeräte (Balance-of-Plant) (BoP), ist eine der Hauptaufgaben in der Studie der Brennstoffzellenkraftwerke.</p><p>Diese Untersuchung betrifft die Systemstudie des auf der Schmelz-Karbonat-Brennstoffzelle (MCFC) basierten Kraftwerks. Die Systemstudie ist mit dem Simulationprogramm Aspen PlusTM durchgeführt worden.</p><p>Artikel I beschreibt die Implementierung eines in Aspen PlusTM entwickelten MCFC Stapelmodells, um ein MCFC Kraftwerk zu studieren, das Erdgas als Brennstoff verwendet.</p><p>Artikel II beschreibt, wie unterschiedliche Prozeßparameter, wie Brenngasnutzung und dieWahl des Brennstoffes, die Leistung eines MCFC Kraftwerks </p> / <p>A fuel cell is an electrochemical reactor, directly converting chemically bound energy to electrical energy. In stationary power production the fuel cell stack itself is only a small component of the whole system. The integration of all the auxiliary components, the Balance-of-Plant (BoP), is one of the main issues in the study of fuel cell power plants.</p><p>This thesis concerns the systems studies of molten carbonate fuel cell (MCFC) based power plants. The system studies has been performed with the simulation software Aspen PlusTM.</p><p>Paper I describes on the implementation of a developed MCFC stack model into Aspen PlusTM in order to study an MCFC power plant fueled with natural gas.</p><p>Paper II describes how different process parameters, such as fuel cell fuel utilization, influence the performance of an MCFC power plant.</p> / <p>Bränslecellen är en elektrokemisk reaktor som kan direkt omvandla kemiskt bunden energi till elektrisk energi. I stationär kraftproduktion är själva bränslecellsstapeln endast en mindre komponent i systemet. Integrationen av kringutrustningen, den s.k. Balance-of-Plant (BoP), som tex. pumpar, kompressorer och värmeväxlare är en av huvudfrågeställningarna i studierna av bränslecellskraftverk. Denna avhandling avser systemstudier av mältkarbonatbränslecellsbaserade (MCFC) kraftverk. Systemstudierna har utförts med processimuleringprogramet Aspen PlusTM.</p><p>Artikel I beskriver en utvecklad MCFC-cellmodell, som implementeras som "user model" i Aspen Plus, för att studera ett naturgasbaserat bränslecellskraftverk.</p><p>Artikel II beskriver hur olika processparametrar, som tex bränsleutnyttjande och val av bränsle, påverkar ett MCFC-kraftverks prestanda.</p> Fuel cells fuel cell systems system studies process simulation molten carbonate Brennstoffzellen Brennstoffzellensystem Systemanalyse Prozeßsimulation, Bränsleceller bränslecellssystem systemstudier processimulering smältkarbonatbränslecell, Chemical engineering Kemiteknik
5	System studies of MCFC power plants Fillman, Benny January 2005 (has links) Die Brennstoffzelle ist ein elektrochemischer Reaktor und wandelt chemisch gebundene Energie direkt in elektrische Energie um. In der stationären Energieerzeugung ist der Brennstoffzellenstapel selbst nur ein kleiner Bestandteil des vollständigen Systems. Die Integration aller zusätzlichen Bestandteile, der Peripheriegeräte (Balance-of-Plant) (BoP), ist eine der Hauptaufgaben in der Studie der Brennstoffzellenkraftwerke. Diese Untersuchung betrifft die Systemstudie des auf der Schmelz-Karbonat-Brennstoffzelle (MCFC) basierten Kraftwerks. Die Systemstudie ist mit dem Simulationprogramm Aspen PlusTM durchgeführt worden. Artikel I beschreibt die Implementierung eines in Aspen PlusTM entwickelten MCFC Stapelmodells, um ein MCFC Kraftwerk zu studieren, das Erdgas als Brennstoff verwendet. Artikel II beschreibt, wie unterschiedliche Prozeßparameter, wie Brenngasnutzung und dieWahl des Brennstoffes, die Leistung eines MCFC Kraftwerks / A fuel cell is an electrochemical reactor, directly converting chemically bound energy to electrical energy. In stationary power production the fuel cell stack itself is only a small component of the whole system. The integration of all the auxiliary components, the Balance-of-Plant (BoP), is one of the main issues in the study of fuel cell power plants. This thesis concerns the systems studies of molten carbonate fuel cell (MCFC) based power plants. The system studies has been performed with the simulation software Aspen PlusTM. Paper I describes on the implementation of a developed MCFC stack model into Aspen PlusTM in order to study an MCFC power plant fueled with natural gas. Paper II describes how different process parameters, such as fuel cell fuel utilization, influence the performance of an MCFC power plant. / Bränslecellen är en elektrokemisk reaktor som kan direkt omvandla kemiskt bunden energi till elektrisk energi. I stationär kraftproduktion är själva bränslecellsstapeln endast en mindre komponent i systemet. Integrationen av kringutrustningen, den s.k. Balance-of-Plant (BoP), som tex. pumpar, kompressorer och värmeväxlare är en av huvudfrågeställningarna i studierna av bränslecellskraftverk. Denna avhandling avser systemstudier av mältkarbonatbränslecellsbaserade (MCFC) kraftverk. Systemstudierna har utförts med processimuleringprogramet Aspen PlusTM. Artikel I beskriver en utvecklad MCFC-cellmodell, som implementeras som "user model" i Aspen Plus, för att studera ett naturgasbaserat bränslecellskraftverk. Artikel II beskriver hur olika processparametrar, som tex bränsleutnyttjande och val av bränsle, påverkar ett MCFC-kraftverks prestanda. / QC 20101129 Fuel cells fuel cell systems system studies process simulation molten carbonate Brennstoffzellen Brennstoffzellensystem Systemanalyse Prozeßsimulation Bränsleceller bränslecellssystem systemstudier processimulering smältkarbonatbränslecell Chemical Engineering Kemiteknik
6	Fuel Cells and Biogas Hedström, Lars January 2010 (has links) This thesis concerns biogas-operated fuel cells. Fuel cell technology may contribute to more efficient energy use, reduce emissions and also perhaps revolutionize current energy systems. The technology is, however, still immature and has not yet been implemented as dominant in any application or niche market. Research and development is currently being carried out to investigate whether fuel cells can live up to their full potential and to further advance the technology. The research of thesis contributes by exploring the potential of using fuel cells as energy converters of biogas to electricity. The work includes results from four different experimental test facilities and concerns experiments performed at cell, stack and fuel cell system levels. The studies on cell and stack level have focused on the influence of CO, CO2 and air bleed on the current distribution during transient operation. The dynamic response has been evaluated on a single cell, a segmented cell and at stack level. Two fuel cell systems, a 4 kW PEFC system and a 5 kW SOFC system have been operated on upgraded biogas. A significant outcome is that the possibility of operating both PEFCs and SOFCs on biogas has been established. No interruptions or rapid performance loss could be associated with the upgraded biogas during operation. From the studies at cell and stack level, it is clear that CO causes significant changes in the current distribution in a PEFC; air bleed may recover the uneven current distribution and also the drop in cell voltage due to CO and CO2 poisoning. The recovery of cell performance during air bleed occurs evenly over the electrode surface even when the O2 partial pressure is far too low to fully recover the CO poisoning. The O2 supplied to the anode reacts on the anode catalyst and no O2 was measured at the cell outlet for air bleed levels up to 5 %. Reformed biogas and other gases with high CO2 content are thus, from dilution and CO-poisoning perspectives, suitable for PEFC systems. The present work has enhanced our understanding of biogas-operated fuel cells and will serve as basis for future studies. / QC20100708 air bleed biogas carbon dioxide carbon monoxide current distribution dilution efficiency energy conversion energy systems experimental fuel cell fuel cell systems PEFC poisoning reformate SOFC Chemical energy engineering Kemisk energiteknik
7	Bringing fuel cells to reality and reality to fuel cells : A systems perspective on the use of fuel cells Saxe, Maria January 2008 (has links) With growing awareness of global warming and fear of political instability caused by oil depletion, the need for a society with a sustainable energy system has been brought to the fore. A promising technology often mentioned as a key component in such a system is the fuel cell technology, i.e. the energy conversion technology in focus in this thesis. The hopes and expectations on fuel cells are high and sometimes unrealistically positive. However, as an emerging technology, much remains to be proven and the proper use of the technology in terms of suitable applications, integration with society and extent of use is still under debate. This thesis is a contribution to the debate, presenting results from two fuel cell demonstration projects, looking into the introduction of fuel cells on the market, discussing the prospects and concerns for the near-term future and commenting on the potential use in a future sustainable energy system. Bringing fuel cells to reality implies finding near-term niche applications and markets where fuel cell systems may be competitive. In a sense fuel cells are already a reality as they have been demonstrated in various applications world-wide. However, in many of the envisioned applications fuel cells are far from being competitive and sometimes also the environmental benefit of using fuel cells in a given application may be questioned. Bringing reality to fuel cells implies emphasising the need for realistic expectations and pointing out that the first markets have to be based on the currently available technology and not the visions of what fuel cells could be in the future. The results from the demonstration projects show that further development and research on especially the durability for fuel cell systems is crucial and a general recommendation is to design the systems for high reliability and durability rather than striving towards higher energy efficiencies. When reliability and durability are achieved fuel cell systems may be introduced in niche markets where the added values presented by the technology compensate for the initial high cost. / QC 20100909 / Energy Systems Programme / Clean Urban Transport for Europe / GlashusEtt Assessment CUTE Demonstration projects Emerging technology Evaluation Fuel cell buses Fuel cell systems Fuel cells Hype Interdisciplinary Niche markets PEM Radical technologies SOFC Strategic niche markets Sustainability Chemical energy engineering Kemisk energiteknik
8	Thermal energy management and chemical reaction investigation of micro-proton exchange membrane fuel cell and fuel cell system using finite element modelling McGee, Seán January 2015 (has links) Fuel cell systems are becoming more commonplace as a power generation method and are being researched, developed, and explored for commercial use, including portable fuel cells that appear in laptops, phones, and of course, chargers. This thesis examines a model constructed on inspiration from the myFC PowerTrekk, a portable fuel cell charger, using COMSOL Multiphysics, a finite element analysis software. As an educational tool and in the form of zero-dimensional, two-dimensional, and three-dimensional models, an investigation was completed into the geometric construction, air conditions and compositions, and product materials with a best case scenario completed that summarizes the results identified. On the basis of the results of this research, it can be concluded that polyoximetylen and high-density polyethylene were considered as possible materials for the majority of the product, though a more thorough investigation is needed. Air flow of above 10 m/s, air water vapour mass fraction below 50% and initial temperature between 308K and 298K was considered in this best scenario. Suggestions on future expansions to this project are also given in the conclusion. 0D model 2D model 3D model chemical engineering Comsol Multiphysics energy environment FC fluid dynamics fuel cell systems heat transfer JAQ laboratory experiments mobile charging modeling modelling myFC PEM polymer electrolyte membrane PowerTrekk process engineering proton exchange membrane sustainability 0D-Modell 2D-Modell 3D-Modell Chemieingenieurwesen COMSOL Multiphysics Energie Umwelt FC Fluiddynamik Brennstoffzellensysteme Wärmeübertragung JAQ Laborexperimente mobile Ladesysteme Modellieren myFC PEM Feststoffpolymer-Brennstoffzelle PowerTrekk Verfahrenstechnik Protonenaustauschmembran-Brennstoffzelle Nachhaltigkeit 0D-modell 2D-modell 3D-modell kemiteknik Comsol Multiphysics energi miljö FC fluiddynamik bränslecellssystem värmeöverföring JAQ laboratorieförsök mobil laddning modellering myFC PEM polymerelektrolytmembran PowerTrekk processteknik protonväxlingsmembran hållbarhet Chemical Engineering Kemiteknik

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