Nonlinear analysis and control of PEM fuel cells

Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2010

Parametrierung elektrischer Äquivalentschaltbilder von PEM Brennstoffzellen

Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2007

Strukturierte Modellierung und nichtlineare Analyse von PEM-Brennstoffzellen

Fuel cell, PEM fuel cell, Network theory, Computer aided modelling, Nonlinear analysis

Pem??n en el Ateneo de Madrid : disert?? sobre la 'cuarta y definitiva salida de Don Quijote por el mundo'

Se analiza el discurso pronunciado por D. Jos?? Mar??a Pem??n, el poeta y dramaturgo Presidente de la Academia Espa??ola, que pronunci?? en el Ateneo de Madrid bajo el t??tulo 'De la cuarta y definitiva salida de Don Quijote por el mundo', del que explica y contextualiza la obra de Cervantes relacion??ndola con otros grandes autores y obras maestras como V??ctor Hugo, el Renacimiento, el Romanticismo, la Generaci??n del 98 y las reflexiones de Ortega y Gasset en su obra 'Meditaciones del Quijote'.

Microblock ionomers: a new concept in high temperature, swelling-resistant membranes for PEM fuel cells

A novel series of polyaromatic ionomers with similar equivalent weights but very different sulphonic acid distributions along the ionomer backbone has been designed and prepared. By synthetically organising the sequence-distribution so that it consists of fully defined ionic segments (containing singlets, doublets or quadruplets of sulphonic acid groups) alternating strictly with equally well-defined nonionic spacer segments, a new class of polymers which may be described as microblock ionomers has been developed. These materials exhibit very different properties and morphologies from analogous randomly substituted systems. Progressively extending the nonionic spacer length in the repeat unit (maintaining a constant equivalent weight by increasing the degree of sulphonation. of the ionic segment) leads to an increasing degree of nanophase separation between hydrophilic and hydrophobic domains in these materials. Membranes cast from ionomers with the more highly phase-separated morphologies show significantly higher onset temperatures for uncontrolled swelling in water. This new type of ionomer design has enabled the fabrication of swelling-resistant hydrocarbon membranes, suitable for fuel cell operation, with very much higher ion exchange capacities (>2 meq g(-1)) than those previously reported in the literature. When tested in a fuel cell at high temperature (120 degrees C) and low relative humidity (35% RH), the best microblock membrane matched the performance of Nafion 112. Moreover, comparative low load cycle testing of membrane -electrode assemblies suggests that the durability of the new membranes under conditions of high temperature and low relative humidity is superior to that of conventional perfluorinated materials.

Investigation of the CO tolerance mechanism at several Pt-based bimetallic anode electrocatalysts in a PEM fuel cell

The electrocatalysis of CO tolerance of Pt/C, PtRu/C, PtFe/C, PtMo/C, and PtW/C at a PEM fuel cell anode has been investigated using single cell polarization and online electrochemical mass spectrometry (EMS) measurements, and cyclic voltammetry, X-ray diffraction (XRD), in situ X-ray absorption near edge structure (XANES) analyses of the electrocatalysts. For all bimetallic electrocatalysts, which presented higher CO tolerance, EMS results have shown that the production of CO(2) start at lower hydrogen electrode overpotentials as compared to Pt/C, confirming the occurrence of the so-called bifunctional mechanism. On the other hand, XANES results indicate an increase in the Pt 5d-band vacancies for the bimetallic catalysts, particulary for PtFe/C, this leading to a weakening of the Pt-CO bond, helping to increase the CO tolerance (the so-called electronic effect). For PtMo/C and PtRu/C supplied with H(2)/CO, the formation of CO(2) is observed even when the cell is at open circuit, confirming some elimination of CO by a chemical process, most probably the water gas shift reaction. (C) 2008 Elsevier Ltd. All rights reserved.

Carbon-supported Pt-Co catalysts prepared by a modifled polyol process as cathodes for PEM fuel cells

In this work, carbon-supported Pt70Co30 nanoparticles were prepared by a polyol process using a long-chain diol as reducer (hexadecanediol) and oleic acid and oleylamine as stabilizers. Depending on the synthesis conditions, Pt70Co30/C nanocatalysts with very small particle size (1.9 +/- 0.2 nm) and narrow distribution homogeneously dispersed on the carbon support and having a high degree of alloying without the need of thermal treatments were obtained. The as-prepared catalyst presents an excellent performance as proton exchange membrane fuel cells (PEMFC) cathode material. In terms of mass activity (MA), the Pt70Co30/C electrocatalysts produced single fuel cell polarization response superior to that of commercial catalyst. To analyze alloying effects, the result of thermal treatment at low temperatures (200-400 degrees C) was also evaluated and an increase of average crystallite size and a lower degree of alloying, probably associated to cobalt oxidation, were evidenced.

Um sistema eletrônico de 2kW para emulação/simulação experimental da característica estática de saída, tensão (versus) corrente, de sistemas de geração com células combustível tipo PEM

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise termoquímica de reformador de etanol: produção de hidrogênio para acionamento de uma célula combustível do tipo PEM de 1 KW

Pós-graduação em Engenharia Mecânica - FEG

Política de saúde e a população carcerária: um estudo no Presídio Estadual Metropolitano I – PEM I – Marituba-Pará

Este trabalho, intitulado “Política de Saúde e a População Carcerária: um estudo no Presídio Estadual Metropolitano I – PEM I – Marituba-Pará”, tem como objetivo maior analisar o processo de assistência à saúde dos presos no Presídio Estadual Metropolitano I (PEM I) de Marituba/PA. Para isso, traçou-se os seguintes objetivos específicos: investigar a situação do sistema carcerário brasileiro diante do quadro de desigualdades sociais e criminalização; identificar de que forma o direito à saúde penitenciária está estruturado no Brasil; e analisar como o direito de assistência à saúde está sendo materializado enquanto direito social no PEM I. Na perspectiva de desvendar o objeto de estudo, a metodologia foi baseada na abordagem crítica, utilizando-se da aplicação de formulários com 02 (dois) internos que passavam por tratamento de saúde no interior do PEM I. Dessa forma, foi possível constatar contradições e limites na assistência à saúde enquanto direito social dos internos do PEM I, refletidos na precarização do direito à saúde no âmbito prisional.

Comparative analysis between a PEM fuel cell and an internal combustion engine driving an electricity generator: Technical, economical and ecological aspects

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caratterizzazione di membrane inorganiche per la separazione di idrogeno da gas di reforming

The work of this thesis has been focused on the characterisation of inorganic membranes for the hydrogen purification from steam reforming gas. Composite membranes based on porous inorganic supports coated with palladium silver alloys and ceramic membranes have been analysed. A brief resume of theoretical laws governing transport of gases through dense and porous inorganic membranes and an overview on different methods to prepare inorganic membranes has been also reported. A description of the experimental apparatus used for the characterisation of gas permeability properties has been reported. The device used permits to evaluate transport properties in a wide range of temperatures (till 500°C) and pressures (till 15 bar). Data obtained from experimental campaigns reveal a good agreement with Sievert law for hydrogen transport through dense palladium based membranes while different transport mechanisms, such as Knudsen diffusion and Hagen-Poiseuille flow, have been observed for porous membranes and for palladium silver alloy ones with pinholes in the metal layer. Mixtures permeation experiments reveal also concentration polarisation phenomena and hydrogen permeability reduction due to carbon monoxide adsorption on metal surface.