Thesis (Ph. D.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains vii, 199 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references.

Orientador: Rodnei Bertazzoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T20:26:59Z (GMT). No. of bitstreams: 1 Assis_CamilaMolenade_M.pdf: 5677748 bytes, checksum: 86d7040f9e8479ed7064ba9503bfbe62 (MD5) Previous issue date: 2012 / Resumo: Neste trabalho foi estudada a corrosão do metal cobre em meio alcoólico utilizando um arranjo de microeletrodos construídos por fotolitografia. Foi avaliada a influência da área do arranjo de microeletrodos na queda ôhmica e no comportamento da resistência do meio eletrolítico. Os resultados obtidos foram plotados, analisados e comparados com metodologias teóricas obtendo uma boa concordância. Conclui-se que a resistência do meio aumenta, a medida que diminui-se o diâmetro do microeletrodo quando considerado um eletrodo unitário, no entanto, a resistência diminui com o diâmetro do microeletrodo quando considerado num arranjo. Em relação à queda ôhmica, esta diminui com a diminuição do diâmetro e através da compensação da queda ôhmica observa-se que as compensações tiveram menor efeito nos microeletrodos de menor área / Abstract: This work presents an investigation on the corrosion of cooper metal, using a microelectrode array building using lithography technique. The influence of microelectrode array area was investigated on the ohmic drop and resistance of ethanol. The results were then compared with existing theoretical methodologies and good agreements were found. It was concluded that resistance of ethanol increases with decreases single microelectrodes diameter and decreases with decreases array microelectrodes diameter. The ohmic drop decreases with diameter decreases and the ohmic drop compensation had the smallest effect on microelectrodes with smaller area / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

The objective of this research is to determine the effect the North Dakota Ethanol Production Incentive has on ethanol plant survivability. This thesis uses a stochastic simulation to show the financial performance of an ethanol plant with and without subsidy support. Historical corn and ethanol prices are used to simulate market conditions a typical ethanol might face. Using the forecast prices, an ethanol plant balance sheet was created to show how a plant would perform in normal market conditions, as well as how the plant would perform with the Ethanol Production Incentive and also with alternative subsidy structures that were developed. The results showed the Ethanol Production Incentive was the most effective subsidy tested and it does appear to improve plant balance sheets to a certain extent during a downturn.

Current ethanol oxidation catalysts in direct ethanol fuel cells (typically platinum-based) suffer from low conversion and are susceptible to CO poisoning. Therefore we determined to find viable alternative catalysts for ethanol oxidation based on iridium using density functional theory to model bimetallic alloy (111) surfaces. Iridium was alloyed with another transition metals M in an overlayer (one layer of metal M on top of bulk iridium) or subsurface configuration (M is inserted under the first layer of iridium). Complete oxidation of ethanol is limited by the breaking of strong C-C bonds, so any catalyst must lower the barriers for C-C bond breaking. We modeled the reaction CH+CO →CHCO.Segregation energies were calculated and the subsurface configuration was the most stable configuration in the vast majority of alloy cases. CO adsorption was also studied and a lower CO adsorption energy was found in many alloy cases compared to pure Pt (, providing encouraging results about the possibility of reducing CO poisoning. Activation energies were lowered for the vast majority of the alloys used in an underlayer structure, reinforcing our interest in the underlayer structures or “subsurfaceâ€� alloys. Finally, we found, based on the CO adsorption energies, activation energies of the C-C breakage reaction, and metal cost, three important catalyst descriptors, a number of promising catalysts for the ethanol oxidation reaction. The most interesting alloys all adopted the underlayer structure Ir/M/Ir. With M = Ta, Hf, Nb, V, Zr, they demonstrated enhanced reactivity and high CO tolerance, having the advantage of reducing the cost of the catalyst, potentially substituting expensive platinum group metals by more affordable components.

No description available.

New federal legislation proposes to reduce greenhouse gas (GHG) emissions associated with biofuel production. To comply, existing corn ethanol plants will have to invest in new more carbon efficient production technology such as dry fractionation. However, this will be challenging for the industry given the present financial environment of surplus production, recent profit declines, numerous bankruptcies, and lender imposed covenants. This study examines a dry-mill ethanol firm's ability to invest in dry fractionation technology in the face of declining profitability and stringent lender cash flow repayment constraints. Firm level risk aversion also is considered when determining a firm's willingness to invest in dry fractionation technology. A Monte Carlo simulation model is constructed to estimate firm profits, cash flows, and changes in equity following new investment in fractionation to determine an optimal investment strategy. The addition of a lender-imposed sweep, whereby a percentage of free cash flow is used to pay off extra debt in high profit years, reduces the firm's ability to build equity and increases bankruptcy risk under investment. However, the sweep increases long-run equity because total financing costs are reduced with accelerated debt repayment. This thesis shows that while ethanol firm profits are uncertain, the lender's imposition of a sweep combined with increased profit from dry fractionation technology help the firm increase long-run financial resiliency.

Neste trabalho foi desenvolvido um método de preparação de eletrocatalisadores de Platina e Estanho suportados em carbono para a oxidação de etanol. Este método utiliza a decomposição térmica de precursores poliméricos, conhecido como método Pechini, para a produção de pós com tamanho de partículas da ordem de nanômetros. Foram preparados diversos catalisadores variando-se a proporção entre platina e estanho, e a proporção entre metal e carbono. Os eletrocatalisadores foram caracterizados por técnicas de Espectroscopia de Energia Dispersiva de raios X (EDX), Difração de raios X (DRX) e Microscopia Eletrônica de Transmissão (MET). Os resultados mostram que o método utilizado produziu catalisadores com composição nominal próxima da composição real, que os tamanhos de cristalitos estão na ordem de 5 nm e os tamanhos de partículas apresentados estão na ordem de 5 nm. As atividades eletrocatalíticas dos catalisadores foram investigadas utilizando-se técnicas eletroquímicas convencionais (voltametria cíclica e cronoamperometria) assim como através de testes em célula a combustível a etanol direto. Após os testes de cronoamperometria foram analisadas as concentrações de etanol e dos produtos formados através de Cromatografia Líquida de Alta Eficiência (CLAE). Os voltamogramas cíclicos na presença de etanol apresentaram correntes de oxidação de etanol próximos de 0,2 V vs. ERH e os resultados de cronoamperometria mostraram que há grandes diferenças de desempenho entres os eletrocatalisadores. Os resultados de eletrólise mostraram que o produto principal é o acetaldeido, e que a quebra da ligação C-C do etanol ocorreu em pequenas proporções. O melhor desempenho nos testes de célula a combustível foi encontrado utilizando-se PtSnO2/C com uma proporção de estanho de 10 % /platina 90 % (mol) e com uma porcentagem de 30 % (massa) de metal em relação ao carbono. A densidade de potência obtida neste caso foi de aproximadamente 72 mW cm-2. / In this work, a method for the preparation of eletrocatalysts containing platinum and tin supported on carbon was developed aiming at the ethanol oxidation. This method uses the thermal decomposition of polymeric precursors, known as the Pechini method, for the production of powders with particle size lying in the range of nanometers. Several catalysts were prepared by varying the platinum and tin ratio, as well as the metal and carbon proportion. The eletrocatalysts were characterized by Energy Dispersive X-ray Spectroscopy (EDX), X-ray diffraction (DRX) and Transmission Electron Microscopy (TEM). Our results showed that the method employed in the study produced catalysts with compositions close to the nominal one, with particle size in the order of 5 nm. The electrocatalytic activities of the catalysts were investigated by conventional electrochemistry techniques (cyclic voltammetry and chronoamperometry) and by tests in direct ethanol fuel cells. After the chronoamperometric tests, the ethanol and the products were analyzed by High Performance Liquid Chromatography (HPLC). Results obtained by cyclic voltammetry in the presence of ethanol showed that currents of ethanol oxidation at approximately 0.2 V vs. RHE were achieved and the chronoamperometry results gave evidence of large differences in the electroactivity of the eletrocatalysts. The electrolysis results showed that the main product was acetaldehyde, and that the break of the C-C bond of the ethanol occured in small proportions. The best result in the cell tests was found by using the catalyst PtSnO2/C with a tin / platinum molar ratio of 1:9 and 30% (mass) metal loading in relation to carbon. The power density obtained in this case was approximately 72 mW cm-2.

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 74-78).

Made available in DSpace on 2014-10-09T12:35:43Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:54Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:41:23Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:56Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP