Página 1 dos resultados de 10 itens digitais encontrados em 0.052 segundos

Desenvolvimento de um modelo numérico computacional aplicado a uma célula combustível unitária de 144 CM2 tipo PEM; DEVELOPMENT OF A COMPUTATIONAL MODEL APPLIED TO A UNITARY 144 CM2 PROTON EXCHANGE MEMBRANE FUEL CEL

Robalinho, Eric
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/05/2009 Português
Relevância na Pesquisa
75.74%
Este trabalho apresenta o desenvolvimento de um modelo numérico computacional e respectiva metodologia para estudo e projeto de células a combustível a membrana polimérica trocadora de prótons PEM. Para a validação dos resultados experimentais, descreveu-se uma seqüência de rotinas de programação, adequadas ao ajuste dos dados obtidos em laboratório. Com relação à implementação computacional criou-se uma estratégia inovadora de acoplamento com dois modelos tridimensionais, de forma a satisfazer as exigências do modelo completo de célula a combustível, comportando suas diversas geometrias e materiais, assim como os diversos processos físicoquímicos simulados. Com a finalidade de avaliação eficaz da analogia da célula real com o modelo numérico, foram realizados estudos numéricos, comparações com valores obtidos na literatura, caracterização de variáveis por meio de experimentos laboratoriais e estimativas com base em modelos já estudados na literatura. Para a parte experimental, um protótipo de célula a combustível unitária de 144 cm2 de área geométrica foi projetado, produzido e operado em bancada com a finalidade de validação do modelo numérico computacional proposto, apresentando resultados positivos. Os resultados das simulações para as geometrias 2D e 3D propostas são apresentados em forma de curvas de polarização...

Water management in PEMFC

Falcão, D. S.; Rangel, C. M.; Pinho, C.; Pinto, A.M.F.R.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 01/04/2009 Português
Relevância na Pesquisa
45.75%
The potential of fuel cells for clean and efficient energy conversion is generally recognized. Proton-exchange membrane (PEM) Fuel Cells are among the different types of fuel cells one of the most promising. The water management is a critical problem to overcome in the PEM fuel cell technology. Despite several studies on this topic effective water management is still elusive. Models play an important role in fuel cell development since they enable the understanding of the influence of different parameters on the cell performance allowing a systematic simulation, design and optimization of fuel cells systems. In this work, a model previously developed and validated [1], is used to predict the water transport through the cell. The model takes into account heat and mass transport effects The influence of membrane thickness and transport properties, GDL thickness and structure, reactants pressure and humidification temperatures, on the water content through the membrane and on the cell performance was studied. All these parameters have an important impact in the cell water management. The model predicts the membrane water contents and water concentration profiles along the MEA. This work represents a useful tool to set-up suitable operating conditions and optimized tailored MEAs to produce a better performance of PEM fuel cells.

Novel data-driven methodologies for parameter estimation and interpretation of fuel cells performance

Lopes, Vitor V.; Novais, Augusto Q.; Rangel, C. M.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 17/10/2011 Português
Relevância na Pesquisa
95.71%
Fuel cell based power generation systems are expected to become more widespread in the near future. Stationary fuel cells may be used as an uninterruptible or back-up power supply, or to supply micro-grids. In particular, proton exchange membrane fuel cells (PEMFC) are an attractive technology due to its high energy density, rigid and simple structure, low operating temperature and fast start-up characteristics. The power quality assessment of fuel cells as a viable power sources requires a good understanding of the fuel cell performance characteristics. This paper presents two novel data-driven methodologies for the identification of the main steady state (polarization curve) and the dynamic (impedance response) characteristics for fuel-cells allowing the development of rapid, accurate and empirical models based on the experimental data. M-NMF is a modified non-negative matrix factorization technique developed for the analysis of polarization curve data that allows to identify the three main contributions for the fuel-cell power degradation, while for impedance spectroscopy data, this paper proposes the use of fractional order transfer functions (FC-FOTC) to describe the main dynamic modes present in the fuel-cell. A brief description of these two approaches is presented...

Detección y control del estado de una Pila PEM para funcionamiento óptimo: arquitectura de agentes de percepción y control

Agila Gálvez, Wilton Edixon
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
35.71%
En esta memoria se presenta una estrategia de detección de estado de una Pila de Combustible de Membrana de Intercambio Protónico (PEMFC) en tiempo real, a partir de un método de perturbaciones y un algoritmo de clasificación de estados basado en un árbol de decisión borrosa. Se analiza la respuesta eléctrica de la pila, en distintos estados de humedad de la membrana, ante una secuencia de perturbaciones, a fin de extraer los mejores descriptores para la etapa de clasificación de estado de la pila. Las características seleccionadas se utilizan como entradas del modelo de clasificación, basado en un árbol de decisión borroso, que se encuentra encapsulado como agente de percepción de estado en una arquitectura de control basada en agentes expertos. Este agente de percepción de estado se integra con otros agentes expertos en la generación y gestión de alertas ante fallos y en el control de eficiencia, en una arquitectura de percepción, supervisión y control, en tiempo real, para lograr su funcionamiento autónomo en condiciones óptimas de humectación. La arquitectura integra algoritmos de percepción y control que utilizan información sensorial y de contexto y se encuentra estructurada en una jerarquía de niveles con distinta ventana temporal y nivel de abstracción. Estas arquitecturas están especialmente indicadas para sistemas complejos...

Comparative design analysis of a fuel cell powered Coast Guard cutter

Comar, John Francis.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 194 p.
Português
Relevância na Pesquisa
45.68%
This investigation studied the impact of using fuel cells as the primary power source in a ship design. Three different fuel cells were modeled: Phosphoric Acid, Proton Exchange Membrane, and Molten Carbonate. These models were compared against a baseline design containing a more conventional powerplant. The models were built and optimized using the 'Advanced Surface Ship Evaluation Tool' (ASSET/MONOSC). Specifically, payload, endurance, sustained speed, and hull depth were held constant, while length, beam, and draft were optimized to provide a balanced design. Full load displacement and required fuel load were compared against the baseline values. Conclusions concerning the potential value of a fuel cell powerplant were drawn.; NA; U.S. Coast Guard (U.S.C.G.) author

Modelação de células de combustível

Campos, Daniel José Batista da Costa
Fonte: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto Publicador: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
Tipo: Dissertação de Mestrado
Publicado em //2009 Português
Relevância na Pesquisa
65.8%
Neste trabalho serão apresentados e discutidos vários aspectos relacionados com células de combustível, com particular enfoque na modelação de células de combustível de membrana de permuta protónica. Este trabalho está dividido em vários capítulos. No Capítunlo 1 são apresentadas as motivações e os objectivos da tese. No Capítulo 2 serão apresentadas as células de combustível em geral, a sua origem, os diversos tipos, o que as diferencia das restantes tecnologias de geração de energia e as suas vantagens e desvantagens. No Capítulo 3 discute-se a modelação de células de combustível. Serão expostos e explicados os diferentes tipos de modelos, seguindo-se uma apresentação do modelo selecionado para estudo, com referência aos fundamentos teóricos exposição detalhada da fórmulação matemática e os parâmetros que caracterizam o modelo. É também apresentado a implementação do modelo em Matlab/Simulink. No Capítulo 4 será discutida e apresentada a abordagem utilizada para a identificação dos parâmetros do modelo da célula de combustível. Propõe-se e prova-se que uma abordagem baseada num algoritmo de optimização inteligente proporciona um método eficaz e preciso para a identificação dos parâmetros. Esta abordagem requer a existência de alguns dados experimentais que são também apresentados. O algoritmo utilizado designa-se por Optimização por Enxame de Partículas – Particle Swarm Optimization (PSO). São apresentados os seus fundamentos...

Modeling and control of an automotive fuel cell thermal system

Nolan, John
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
95.81%
This work develops an 8th order, non-linear thermal model of an automotive Proton Exchange Membrane (PEM) fuel cell system. Subsystem models were developed from first principals where ever possible and validated against data from a physical system. The entire model was then validated against system data from a General Motor's 120kW fuel cell system. The system model was analyzed in both the time and frequency domain. Next, a reduced, 3rd order model was constructed from the full model and then linearized. The performances of all three models were compared and it was found that the 3rd order linear model provided an acceptable representation of the full non-linear model. Using the models developed in the first section, different control strategies were examined. A proportional-integral (PI) controller was developed as a baseline and compared to a full state feedback Linear Quadratic controller. This controller was augmented to include output variable feedback to improve the steady state performance of the controller. The state feedback controller was found to have faster response and less interaction between the controlled variables than the baseline controller. Because some of the states are unmeasured, an estimator was developed to determine the state values for the full state feedback controller.

RIT Undergraduate Symposium 2008; Investigation of the serotonin 2b receptor for an effect on the risk of developing presbycusis; Investigation of the mitochondrial genome for variants that protect against hearing loss; A Comparison of baits for sampling isopods; Conducting polymerase chain reaction to examine the temporal expression pattern of delta, a signaling ligand, in eucidaris tribuloides; Spatial expression of delta in e. tribuloides using wholemount in situ hybridization; ALDH18A1- A Possible role in age related hearing loss; Antibiotic use in agriculture; ConSCRIPT: A RasMol to PyMOL translator; Characterization of the dbc1-induced cell death pathway; Glutamate signaling and signal transduction in arabidopsis thaliana and mentha spicata: Preliminary work; Role of the vsv m protein on NF-kB regulation in l929 cells; Identification of single nucleotide polymorphisms from patient samples with autoimmune disease of the liver primary sclerosing cholangitis (psc); Molecular phylogeny of terestrial isopods; GJB2 (connexin 26) does not appear to influence susceptibility to presbycusis; Protein expression analysis of the [psi+] and [psi-] yeast strains using 2-d gel electrophoresis; The Vesicular stomatitis virus matrix protein alone is not able to suppress IFN MRNA expression; Production of isogenic prion strains for transcriptional profiling studies; Job satisfaction and detrimental self-reward: A Hidden issue; The Effects of terrorism on foreign direct investment in an andean nation: Colombia; Polyethylene/starch nanocomposites made in-situ using single-site catalysts; Proteomic analysis of an e. coli orf135 knockout mutant; Novel solvent shifting technique for suspended ceo2 nanoparticles from aqueous to organic solvent media; Utilizing swcnt properties in Li-ion batteries; Studies in the synthesis of kdp nano-crystals; Enhanced passivation of p3ht:pcbm bulk heterojunction photovoltaic devices; Nephrogenic systemic fibrosis and omniscan: Part 2; Studies toward the total synthesis of a cross-membrane fluorometric probe; A Study of the efficacy of 3-d virtual models as an additional tool toward visuospatial learning in an undergraduate setting; Synthesis of nickel based salicylaldiminate single-site catalysts; Biodegradability studies of polyethylene/biomass composites; Electrochemical analysis of near-infrared dyes for polymer solar cells; The Effect of rhodamine 101 concentration on its interactions with single wall carbon nanotubes; Nephrogenic systemic fibrosis and omniscan: Part 1; Surface functionalization of carbon nanotubes with nitrogen atoms; Studies toward the total synthesis of eletefine; Polymer/nanoclay adhesive with moisture barrier properties; Ink-jet printing of polymer solar cells; Connecting the real and virtual: Interfacing simulated systems with real systems; Understanding user viewing behavior with regard to online newspaper advertising; Re-examining gaze behavior during locomotion; A Multicamera system using immersive projection to create natural views for steering a remote vehicle; Human visualization project: models for gross anatomy; Principal component analysis of multispectral images of unidentified leaves from the archimeded palimpsest; The Correlation and underlying distribution of luminosity for fr1 and fr2 radio galaxies; Principal component analysis of combined imaging modalities of leaf 57 verso in the archimedes palimpsest; The Role of Seventeen magazine on female adolescent self image: Images of models and their impact; Identity formation and expression through baggy clothing in the inner-city African-American adolescent male; The Dream, the reality, the actions: a study of changing American values and attitudes in the 21st century; Services provided for the health-related consequences of community violence among the Hispanic youth of the city of Rochester; Spectrally accurate initial data for numerical relativity; A Network theoretic approach to hyperspectral image classification; Investigation into un-induced eccentric radial motion of a magnetically levitated ventricle assist device; Novel ventricular cannulae design for use with ventricular assist devices; Modeling the intrusion of a gas diffusion layer into flow channels of a proton exchange membrane fuel cell; Determination of 3-dimensional deformations of the alveolar sac during simulated breathing; Two-phase flow regime classification using fast fourier power spectra; Modeling of polarization curves of a proton exchange membrane fuel cell; A System for measuring smoke deposition in a realistic lung cast to compare “safer” and “conventional” cigarettes; Simulation of heat and mass transport in gas flow streams of a pemfc from a water management perspective; The Effect of cilia coordination and mucus rheology on clearance in the respiratory tract; Ex-situ investigation of gas diffusion layer and channel water management in proton exchange membrane fuel cells; Fluid flow and particle deposition in the human oral cavity and oropharynx; High temperature characterization of III-V on si esaki diodes; Mechanical polishing for omvpe grown polycrystalline III-V photovolatics on low-cost substrates; Circuit simulations using an empirical model of a gaas esaki diode; Optimization of grid finger design and fabrication for iii-v based solar cells; Self-organized ni nanodots for carbon nanotubes growth by atmospheric plasma; Automated electrical characterization of silicon-onglass micro-fabricated devices; Proton irradiation tolerance of InAs quantum dots in GaAs solar cells for space; Thermal sio2 growth rate enhancement at low temperatures using an nf3 additive; Investigation of the electrical properties of e-beam evaporated sio2 as a function of deposition parameters such as oxygen flow, bias voltage, and deposition rate; Vehicle data modeling: A Tool to aid researchers in transportation policy analysis and decision-making; Gas chromatography-mass spectrometry (gc-ms) analysis of four carcinogens in cigarette smoke; Controllable linear nanowire frabraction by diblock copolymer polystyrene-b-poly(2-vinypyridine); Paraphyletic relationships within ctenosaura pectinata; Towards achieving high compression ratios for digital video using a combined planar and sequential d-transform algorithm; Digital principles for health related behavior change; Analysis of the pretreatment process for haylage, wheat straw, sweet corn sialge, and varieties of conventional corn silage; Process intensification of solid extraction of ensiled materials by microwave heating; BookIt! : An Open source software platform for the collection, reformatting, and publishing of content from online data repositories; Constructing a diskless high-performance computing cluster using recycled hardware; Security solution for cluster based wireless sensor networks using random pre-distributed key management; Life cycle perspective analysis of single wall carbon nanotube Li-ion battery anode energy consumption; Characterization and analysis of solar cells using isc-voc and dark diode curves; A Geometric and probablistic approach to the filtration of rods; Random packings of spherocylinders; Theoretical studies of the electrostatic properties of the eye-lens protein gamma-b crystallin; Filtration of rods; Using spectroscopy to investigate gas flows around supermassive blackholes; Star formation analysis in the brightest galaxies and clusters from infrared and ultraviolet emissions; Jamming and flow of rod-like granular materials in a hopper; Static light scattering studies of the molecular weight and second virial coefficient of eye lens alpha crystallin, as functions of ph and ionic strength; Towards the dependence of phase separation of eye lens gamma b crystallin on ionic strength

Braganza, Andrea; Souza, Amanda; Birdsall, Laura; Stevens, Eric; Newman, Dina; Razali, Ayman; Waud, John; Rapp, William; Pough, Harvey; Chen, YuLin; Sweet, Hyla; Albanese, P.; Riordan, Matthew; Easton, Roger; Madigan, Mandy; Koroleski, Alex; Cummings, Dan
Fonte: Rochester Institute of Technology Publicador: Rochester Institute of Technology
Tipo: Abstract
Português
Relevância na Pesquisa
55.89%
The Undergraduate Research Symposium was founded to honor student achievement in scientific research and to further RIT's goal of combining traditional laboratory work and classroom instruction with experiential learning. The symposium now hosts over 40 presentations a year and includes representatives from industry leaders including Eastman Kodak and Xerox.

Modeling and optimization of the PEM fuel cell catalyst layer

Cetinbas, Cankur Firat
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
95.79%
Prasad, Ajay; Advani, Suresh; As the demand for clean energy grows rapidly, proton exchange membrane (PEM) fuel cell technology is seen as a viable candidate for an alternative energy conversion device. Despite much research progress in the past two decades, several remaining technical challenges must be overcome for the successful commercialization of PEM fuel cells. In particular, computational models play an important role in PEM fuel cell research by decreasing the dependence on expensive and time-consuming experimental approaches to develop a cost-effective and efficient PEM fuel cell. The goal of this research study is to formulate multiscale catalyst layer (CL) modeling strategies to provide more accurate predictions for the effects of variations in the loading of platinum, carbon and ionomer, as well as porosity, within the catalyst layer. The ultimate goal is to provide guidelines for the design of an improved CL with better performance and lower cost. The well-known agglomerate approach was chosen to model the CL. First, we conducted micro and macroscale numerical studies to investigate the shortcomings of the classical agglomerate approach which lead to unrealistic predictions of the effects of catalyst loading on performance. The investigation showed that the agglomerate model predictions can be improved either by employing relations between agglomerate parameters and compositional variables...

Performance and degradation of Proton Exchange Membrane Fuel Cells: State of the art in modeling from atomistic to system scale

JAHNKE Thomas; FUTTER Georg; LATZ Arnulf; MALKOW Thomas; PAPAKONSTANTINOU GEORGIOS; TSOTRIDIS Georgios; SCHOTT Pascal; GÉRARD Mathias; QUINAUD Manuelle; QUIROGA Matías; FRANCO Alejandro A; MALEK Kourosh; CALLE VALLEJO Federico; FERREIRA DE MORAIS R; KER
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Articles in periodicals and books Formato: Printed
Português
Relevância na Pesquisa
105.74%
Proton Exchange Membrane Fuel Cells (PEMFC) are energy efficient and environmentally friendly alternatives to conventional energy conversion systems in many yet emerging applications. In order to enable prediction of their performance and durability, it is crucial to gain a deeper understanding of the relevant operation phenomena, e.g., electrochemistry, transport phenomena, thermodynamics as well as the mechanisms leading to the degradation of cell components. Achieving the goal of providing predictive tools to model PEMFC performance, durability and degradation is a challenging task requiring the development of detailed and realistic models reaching from the atomic/molecular scale over the meso scale of structures and materials up to components, stack and system level. In addition an appropriate way of coupling the different scales is required. This review provides a comprehensive overview of the state of the art in modeling of PEMFC, covering all relevant scales from atomistic up to system level as well as the coupling between these scales. Furthermore, it focuses on the modeling of PEMFC degradation mechanisms and on the coupling between performance and degradation models.; JRC.F.2-Energy Conversion and Storage Technologies