Techn. University, Diss., 2001--Berlin.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Techn. University, Diss., 2003--Berlin. / Erscheinungsjahr der Haupttitelstelle : 2003.

Techn. University, Diss., 2005--Berlin.

Techn. University, Diss., 2005--Berlin.

Techn. Universiẗat, Diss., 2006--Darmstadt.

<p>Tremendous research efforts have been conducted studying the capturing and conversion of solar energy. Solar thermal power systems offer a compelling opportunity for renewable energy utilization with high efficiencies and excellent cost-effectiveness. The goal of this work was to design a non-concentrating collector capable of reaching temperatures above 250 °C, use this collector to power methanol steam reforming, and operate a proton exchange membrane (PEM) fuel cell using the generated hydrogen. The study presents the construction and characterization of a non-concentrating, intermediate-temperature, fin-in-tube evacuated solar collector, made of copper and capable of reaching stagnation temperatures of 268.5 °C at 1000 W/m2 irradiance. The collector was used to power methanol steam reforming, including the initial heating and vaporization of liquid reactants and the final heating of the gaseous reactants. A preferential oxidation (PROX) catalyst was used to remove CO from simulated reformate gas, and this product gas was used to operate a PEM fuel cell. The results show 1) that the outlet temperature is not limited by heat transfer from the absorber coating to the heat transfer fluid, but by the amount of solar energy absorbed. This implicates a constant heat flux description of the heat transfer process and allows for the usage of materials with lower thermal conductivity than copper. 2) It is possible to operate a PEM fuel cell from reformate gas if a PROX catalyst is used to remove CO from the gas. 3) The performance of the fuel cell is only slightly decreased (~4%) by CO2 dilution present in the reformate and PROX gas. These results provide a foundation for the first renewable electricity generation via solar-powered methanol reforming through a hybrid PEM fuel cell system based on novel non-concentrating, intermediate-temperature solar collectors.</p> / Dissertation

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-04-19Bitstream added on 2014-06-13T18:50:39Z : No. of bitstreams: 1 antoniassi_bs_me_bauru.pdf: 1977733 bytes, checksum: 9dd271c973d63a540d0f517fcfe56409 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O grande desafio a ser vencido para a utilização de células a combustível de oxidação direta de álcoois (DAFC) refere-se ao desenvolvimento de eletrocatalisadores que favoreçam a oxidação direta do combustível a CO2 e que sejam menos susceptíveis ao envenenamento por intermediários/produtos de reação. Fases intermetálicas ordenadas de Pt têm sido propostas como materiais eletrocatalisadores para estas reações pelo fato de poderem aliar a excelente capacidade de adsorção do orgânico pelos sítios de platina e minimizarem a ação de bloqueadores superficiais. Não menos importante, essa classe de materiais apresenta uma estabilidade físico-química acentuadamente superior a materiais obtidos por deposição de íons metálicos e, desta forma, é mais apropriada para ser empregada diretamente em sistemas reais. Baseado em estudos anteriores a respeito dos materiais obtidos por deposição de íons metálicos sobre a superfície de platina e também estudos preliminares de oxidação de orgânicos em fases intermetálicas ordenadas de PtBi, este trabalho apresenta os resultados obtidos através do estudo da eletrocatálise das reações de oxidação do ácido fórmico e do metanol sobre as fases intermetálicas PtMn, PtMo, PtPb, PtSb e PtSn, em meio ácido... / The great challenge to be won for the use of direct oxidation of alcohols fuel cells (DAFC) refers to the electrocatalytic development that favor the direct oxidation of the fuel CO2 and that are less susceptible to the poisoning by intermediates/products of reaction. Ordered intermetallic phases of Pt have been proposed as electrocatalytic materials for these reactions for the fact of they could ally the excellent capacity of adsorption of the organic for the platinum sites and they minimize the action of blocking superficial. No less important, that class of materials presents a physicochemical stability strongly to materials obtained by deposition of metallic íons and, this way, it is more appropriate to be used directly in real systems. Based on previous studies regarding the materials obtained by deposition of metallic íons on the platinum surface and also preliminary studies of oxidation of organic in ordered intermetallic phases of PtBi, this work presents the results obtained through the study of the electrocatalysis of the reactions of oxidation of the formic acid and of the methanol on the intermetallic phases PtMn, PtMo, PtPb, PtSb and PtSn, in acid middle... (Complete abstract, click eletronic address below)

Methanol poisoning usually comes to the forefront of both professional and general public interest at times, when there is a larger outbreak, outside of these periods these cases appear sporadically. They occur in the whole world, in the developed countries as well as in the developing ones, independently of any restriction on the consumption of alcoholic beverages by the state. In Czech society this topic came to surface especially in 2012, when as a result of methanol intoxication the minimum of 50 people died and many more suffer permanent damage. The trickiness of methanol lies in the fact, that it is not possible to recognize it from ethanol in an alcoholic drink or in any other mixture. Most often it penetrates the organism by way of ingestion; it can also be absorbed through the skin or by inhalation. Methanol itself is not toxic; its metabolites (formaldehyde and formic acid) however present a problem. Typical symptoms include visual disturbances, deepening metabolic acidosis with an increased anion gap and damage to basal ganglia, particularly the putamen. The intoxication is further accompanied by a range of nonspecific symptoms such as stomach pain, nausea, vomiting, impairment of consciousness and cognitive functions. The gravity of the intoxication depends on the amount of ingested methanol and on the mixing ratio with ethanol. Therapy consists of administering specific antidotes ethanol or fomepizole, modifying of the internal environment, continuous or intermittent hemodialysis, if necessary and allowed by the patient's condition and in supportive treatment for maintaining the stability of vital functions. Nursing care has an unreplaceable role in treatment of these patients. Nurses come to contact with these patients in every sector of healthcare, they take part in admission, stabilization and monitoring of vital functions, they tend to the invasions as well as to maximal psychic and physical comfort of the patient. They take part in rehabilitation and also help patients returning into normal life. This thesis deals with the properties of methanol, its production and toxicity, it explores methanol intoxication, its symptoms and sequelae, diagnostics and therapy as well as nursing care in detail. It follows the role of nurses of all the sectors of health care in managing all the stages of the intoxication with emphasis on selected nursing activities in the intensive, standard or aftercare. The thesis concludes with 4 documented case studies. The aim of this thesis was to process the information collected on this topic into a complex and current overview of knowledge on methanol poisoning and the possibilities of dealing with it all of the phases of the poisoning including the aftercare of the patients who were affected. A summary of procedures and variations thereof was acquired on the theoretical basis of Czech and foreign sources such as books, renowned periodicals in paper or electronic form and by means of web sites of professional societies. The sum of knowledge this thesis provides can serve for teaching needsor continuing education of healthcare workers concerning diagnostics, therapy and management of the sequelae of this intoxication with special emphasis on the possibilities of nurse´s intervention in any of the phases of it, or to provide base for further research in this area.

Neste trabalho apresenta-se a modelagem de chamas difusivas na forma de jato, para baixo número de Mach e elevado número de Damköhler. O modelo é baseado na solução das equações na forma flamelet para a parte química e na fração de mistura para o fluxo. Este modelo descreve bem o comportamento de chamas difusivas, exceto na sua extremidade (ponta), onde geralmente surgem instabilidades. Resultados numéricos são apresentados para uma cinética química de uma e multietapas, utilizando a técnica LES (Large-Eddy Simulation) com o modelo de Smagorinsky para a viscosidade turbulenta. A discretização das equações governantes é feita em diferenças finitas, com a aplicação da técnica TVD (Total Variation Diminishing). Além disso, apresentamse mecanismos reduzidos multietapas para o metano, o metanol e o etanol, visando obter resultados realistas. A modelagem de chamas de metanol e etanol diferencia-se da modelagem de chamas de metano por ocorrer uma mudança de fase antes da combustão. Modela-se o efeito global das gotas usando uma descrição Lagrangeana que é incorporada à descrição Euleriana do escoamento, via termos fonte. Testes numéricos foram realizados para chamas difusivas de metano, metanol e etanol, e os resultados estão em concordância com os dados encontrados na literatura. / This work presents a model for a jet diffusion flame, for low Mach and high Damköhler numbers. The model is based on the solution of the flamelet equations for the chemistry and on the mixture fraction for the flow. This model describes well the behavior of diffusion flames, except at the flame tip, where instabilities can often occur. Numerical results are presented for an one-step and multi-step chemical kinetic models, using the LES (Large-Eddy Simulation) technique with the Smagorinsky model for the turbulent viscosity. The discretization of the governing equations follows the finite difference method, with the application of the TVD (Total Variation Diminishing) technique. Besides, multi-step reduced mechanisms for the methane, the methanol and the ethanol are employed, obtaining realistic results. The flame modeling of methanol and ethanol differs from the modeling of methane flames because of a phase change occurs before the combustion. The droplets global effect is modeled based on a Lagrangian description, which is incorporated into the Eulerian description of the flow through source terms. Numerical tests were carried out for methane, methanol and ethanol diffusion flames, and the results compare well with data in the literature.