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The currently reported work involved fundamental study of auto-ignition under unusually high knock intensities in an optical spark ignition engine. The single cylinder research engine adopted included full bore overhead optical access capable of withstanding continuous peak in-cylinder pressure and knock intensity of up to 150 bar and 60 bar respectively. Heavy knock was deliberately induced under relatively low loads (5 bar IMEP) using inlet air heating up to 66 °C and a primary reference fuel blend of reduced octane rating (75 RON). High speed chemiluminescence natural light imaging was used together with simultaneous heat release analysis to evaluate the combustion events. The key out comes of this study could be listed as follow: • Proof and improved understanding of multi centred auto-ignition events under high KIs • Improved understanding of the potential pitfalls of over-fuelling for heavy knock suppression • Optical validation of 'natural' oil droplet release and on-off behaviour of knocking cycles Multiple centred auto-ignition events were regularly observed to lead in to violent knocking events, with knock intensities above 140 bar observed. The ability to directly image the events associated with such high magnitude of knock is believed to be a world first in a full bore optical engine. The multiple centred events were in good agreement with the developing detonation theory to be the key mechanism leading to heavy knock in modern downsized SI engines. The accompanying thermodynamic analysis indicated lack of relation between knock intensity and the remaining unburned mass fraction burned at the onset of the auto-ignition. Spatial analysis of the full series of images captured demonstrated random location of the first captured auto-ignition sites during developing auto-ignition events. Under such circumstances new flame kernels formed at these sites, with initial steady growth sometimes observed to suppress the growth of the earlier spark initiated main flame front prior to violent end gas auto-ignition. It was found that pre-ignition most commonly initiated in the area surrounding the exhaust valve head and resulted in a deflagration that caused the overall combustion phasing to be over advanced. In the cycles after heavy knock, droplets of what appeared to be lubricant were sometimes observed moving within the main charge and causing pre-ignition. These released lubricant droplets were found to survive within the combustion chamber for multiple cycles and were associated with a corresponding "on-off" knocking combustion pattern that has been so widely associated with super-knock in real downsized spark ignition engines. This research also concerned with improving understanding of the competing effects of latent heat of vaporization and auto-ignition delay times of different ethanol blended fuels during heaving knocking combustion. Under normal operation the engine was operated under port fuel injection with a stoichiometric air-fuel mixture. Additional excess fuel of varied blend was then introduced directly into the end-gas in short transient bursts. As the mass of excess fuel was progressively increased a trade-off was apparent, with knock intensity first increasing by up to 60% before lower unburned gas temperatures suppressed knock under extremely rich conditions (γ=0.66). This trade-off is not usually observed during conventional low intensity knock suppression via over-fuelling and has been associated with the reducing auto-ignition delay times outweighing the influence of charge cooling and ratio of specific heats. Ethanol had the highest latent heat of vaporization amongst the other fuels directly injected and was more effective to reduce knock intensity albeit still aggravating knock under slightly rich conditions. Overall, the results demonstrate the risks in employing excess fuel to suppress knock deep within a heavy knocking combustion regime (potentially including a Super-Knock regime).

Made available in DSpace on 2014-06-11T19:26:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-23Bitstream added on 2014-06-13T19:54:23Z : No. of bitstreams: 1 ferreira_fm_me_bauru.pdf: 1454449 bytes, checksum: 05f6f32198a1e9239476329103f79d6d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Cadeias de suprimentos são identificadas e estruturadas para entregar aos consumidores finais que satisfaçam suas necessidades pelo preço que este aceite pagar. A mensuração de custos em cadeia de suprimentos pode apoiar a gestão de operações para garantir competitividade, lucratividade, rentabilidade e atratividade para todos os participantes da cadeia. Este trabalho revisa a literatura de custos, cadeia de suprimentos, mensuração e gestão de custos em cadeia de suprimentos. Apresenta a proposta para mensuração de custos em cadeia de suprimentos por meio do Custeio Variável e para demonstrar a proposta, analisa a cadeia de suprimentos do Etanol Hidratado Combustível. Foram utilizados dados públicos obtidos na Agência Nacional do Petróleo, Gás Natural e Biocumbustível (ANP), Centros de Estudos Avançados em Economia Aplicada - ESALQ (CEPEA) e Conselho dos Produtores de Cana-de-Açúcar, Açúcar e Álcool do Estado de São Paulo (CONSECANA), a partir das usinas, passando pelas distribuidoras e postos de combustíveis até alcançar o consumidor final na cidade de Bauru, comparativamente, no estado de São Paulo, entre janeiro de 2010 e março de 2011. Para compreender a interpretação dos participantes da cadeia de suprimentos sobre preços, custos, margem de contribuição e impacto dos preços de venda na cadeia, entrevistas foram realizadas com representantes dos participantes desta cadeia. A análise dos resultados interpreta as informações obtidas com a proposta para mensuração de custos na cadeia sucroalcooleira, demonstrando as margens de contribuição de cada participante. O uso da proposta para mensuração de custos em cadeia de suprimentos revelou que as maiores margens de contribuição da cadeia são das usinas, que distribuidoras comercializaram o Etanol Hidratado Combustível... / Supply chains are identified and structured to deliver products to end consumers that meet their needs at a price that it agreed to pay. The cost measurement in the supply chain can support operations management to ensure competitiveness, profitability, rentability and attractiveness for all chain participants. This paper reviews the literature of costs, supply chain, measurement and cost management in the supply chain. Presents the proposal for cost measurement in the supply chain through variable costing and to demonstrate the proposal, analyzes the supply chain of Fuel ethanol hydrated. Public data was obtained from the Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (National Agency of Petroleum, Natural Gas and Biofuels - ANP), Centro de Estudos Avançados em Economia Aplicada (Centre for Advanced Studies in Applied Economics) - ESALQ (CEPEA) and Conselho dos Produtores de Cana-de-Açúcar, Açúcar e Álcool do Estado de São Paulo (Council of Producers of Sugar Cane, Sugar and Alcohol of the State of São Paulo - CONSECACA) from plants, through the distributors and gas stations until you reach the end consumer in the city of Bauru, comparatively, in the state of São Paulo, between January 2010 and March 2011. To understand the interpretation of the participants in the supply chain of price, cost, margin contribution and impact of selling prices in chain, interviews were conducted with representatives of the participants in this chain. The analysis of the results interprets the information obtained with the proposal for cost measurement in the sugarcane chain, demonstrating the cotribution, margins of each participant. The use of the proposal for cost measurement in the supply chain revealed that the largest contribution margins in the chain are the plants... (Complete abstract click electronic access below)

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-01T19:55:26Z No. of bitstreams: 1 RaelsonCosta.pdf: 2023784 bytes, checksum: f94eb25d7d645bc252a2d1a75f80a8ee (MD5) / Made available in DSpace on 2017-06-01T19:55:26Z (GMT). No. of bitstreams: 1 RaelsonCosta.pdf: 2023784 bytes, checksum: f94eb25d7d645bc252a2d1a75f80a8ee (MD5) Previous issue date: 2017-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This work presents the development of an electrochemical sensor obtained from the modification of the polyurethane graphite composite electrode with Ag-A zeolite, an aluminosilicate of LTA structure modified with Silver, and its application in the determination of chloride ions, Cl-, in samples of Fuel ethanol. The aluminosilicates were synthesized by the hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy. The obtained materials were then used as modifiers in the proportion of 10% in GPU electrodes, in order to make a comparison between the electrodes without modification and modified with Na-A and Ag-A using the technique of voltammetry of Cyclic. The results showed that the incorporation of Ag into the pores of the material promotes an improvement in the electrical and analytical properties of the electrode. The analytical response of the sensor in the determination of the Clion showed that the GPU-Ag-A electrode responds selectively to the chloride in terms of the decrease in peak current compared to the GPU or GPU-Na-A electrodes. The best response was obtained with electrodes modified with 10% Ag-A. With this percentage composition, the experimental conditions, deposition potential, deposition time, ladder potential, frequency and pH were optimized for analysis by square wave voltammetry in an electrochemical cell containing 2.0 mL of ethanol, 8.0 mL of NaNO3 1.0 mol L-1 and a Clconcentration of 2.5 × 10-5 mol L-1. The Ag-A modified sensor was then evaluated for electroanalytical determination of Clions in fuel ethanol samples presenting linear response. Good results were obtained for the detection limit (3,21 x 10-6 mol L-1), quantification limit (1.07 x 10-5 mol L-1), recovery (87%) and linearity (0.998) . Cu+2 and SO4-2 ions, present in the analysis matrix, did not present significant interference in chloride determination. / Este trabalho apresenta o desenvolvimento de um sensor eletroquímico obtido a partir da modificação do eletrodo compósito de grafite poliuretana com zeólita Ag-A, um aluminosilicato de estrutura LTA modificado com Prata, e sua aplicação na determinação de íons cloreto, Cl-, em amostras de etanol combustível. Os aluminosilicatos foram sintetizados através do método hidrotérmico e caracterizados por difração de raios-X, microscopia eletrônica de varredura. Os materiais obtidos foram, então, utilizados como modificadores na proporção de 10% em eletrodos GPU, a fim de realizar-se uma comparação entre os eletrodos sem modificação e modificados com Na-A e Ag-A mediante a utilização da técnica de voltametria de cíclica. Os resultados mostraram que a incorporação do Ag aos poros do material promove uma melhora nas propriedades elétricas e analíticas do eletrodo. A resposta analítica do sensor na determinação do íon Cl-, mostrou que o eletrodo GPU-Ag-A responde de maneira seletiva ao cloreto, em termos de diminuição de corrente de pico, comparado aos eletrodos GPU ou GPU-Na-A. A melhor resposta foi obtida com eletrodos modificados com 10% de Ag-A. Com esta composição percentual, as condições experimentais, potencial de deposição, tempo de deposição, potencial de escada, frequência e pH, foram otimizadas para analise por voltametria de onda quadrada, em uma célula eletroquímica contendo 2,0mL de etanol, 8,0mL de NaNO3 1,0 mol L-1 e uma concentração de Clde 2,5×10-5 mol L-1. O sensor modificado com Ag-A foi então avaliado para determinação eletroanalítica de íons Clem amostras de etanol combustível apresentando resposta linear. Bons resultados foram obtidos para o limite de detecção (3,21×10-6 mol L-1), limite de quantificação (1,07×10-5 mol L-1 ), recuperação (87%) e linearidade (0,998). Íons Cu2+ e SO4-2, presentes na matriz de analise, não apresentaram interferência significativa na determinação do cloreto.

Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Ragauskas, Arthur; Committee Member: Bunz, Uwe; Committee Member: Deng, Yulin; Committee Member: Singh, Preet; Committee Member: Soper, Jake. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Orientador: José Anchieta Gomes Neto / Banca: Solange Cadore / Banca: Marisa Spirandeli Crespi / Resumo: Este trabalho propõe um método para a determinação direta e simultânea de Al, As, Cu, Fe, Mn e Ni em álcool etílico hidratado combustível (AEHC) por espectrometria de absorção atômica em forno de grafite (GFAAS), empregando tubo de grafite com aquecimento transversal (THGA) e corretor de fundo por efeito Zeeman longitudinal. Foram avaliados dois tipos de modificadores: a mistura nitrato de paládio + nitrato de magnésio, e o modificador permanente W/Rh. No primeiro caso, as curvas analíticas foram obtidas injetando-se 10 mL das soluções de referência (2,0, 5,0, 10, 20, 30, 40 e 50 mg L-1 Al, As, Cu, Fe, Mn e Ni em meio 0,28 mol L-1 HNO3 ) + 10 mL de etanol P.A. + 5 mL Pd(NO3)2+ 3 mL Mg(NO3)2. Para determinar os analitos, foram injetados 10 mL de amostra + 10 mL de solução 0,28 mol L-1 HNO3 + 5 mL Pd(NO3)2 + 3 mL Mg(NO3)2. No teste de adição e recuperação, foram injetados 10 mL de amostra + 10 mL de solução 60 mg L-1 Al, As, Cu, Fe, Mn e Ni em meio 0,28 mol L-1 HNO3+ 5 mL Pd(NO3)2 + 3 mL Mg(NO3)2. Todas as medidas foram feitas em absorbância integrada e em triplicata. O programa de aquecimento otimizado (temperatura, tempo de rampa, tempo de patamar) foi o seguinte: secagem 1 (120oC, 1 s, 10 s); secagem 2 (150oC, 5 s, 25 s); pirólise (1200oC, 10 s, 20 s); atomização (2200oC, 1 s, 6 s) e limpeza (2550oC, 1 s, 3 s). As massas características foram 37 pg Al, 73 pg As, 31 pg Cu, 16 pg Fe, 9 pg Mn e 44 pg Ni e o tempo de vida do atomizador foi equivalente a aproximadamente 250 ciclos de aquecimento. Os desvios padrões relativos (n=12) foram £3%, £6%, £2%, £3,4%, £1,3% e £2% para Al, As, Cu, Fe, Mn e Ni, respectivamente. As recuperações dos analitos adicionados às amostras coletadas em postos de abastecimento da cidade de Araraquara variaram entre 77-112%, 92-114%, 104-113%, 91-116%, 91-122% e 93-116% para Al, As, Cu, Fe, Mn e Ni, respectivamente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work describes a method for direct and simultaneous determination of Al, As, Cu, Fe, Mn and Ni in fuel ethanol by electrothermal atomic absorption spectrometry (GFAAS) with transversely heated graphite atomizer (THGA) and longitudinal Zeeman-effect background corrector. The following modifiers were evaluated: a) the mixture Pd(NO3)2 + 3 æL Mg(NO3)2; b) W/Rh as permanent modifier. Regards to Pd/Mg(NO3)2, analytical curves were obtained by injecting 10 æL of each analytical solutions (2.0, 5.0, 10, 20, 30, 40 and 50 æg L-1 Al, As, Cu, Fe, Mn, Ni in 0.28 mol L-1 HNO3) plus 10 æL of ethanol P.A. plus 5 æL Pd(NO3)2 plus 3 æL Mg(NO3)2. For determination, 10 æL of samples plus 10 æL of 0.28 mol L-1 nitric acid solution plus 5 æL Pd(NO3)2 + 3 æL Mg(NO3)2 were sequentially injected. For analyte addition tests, 10 æL sample plus 10 æL of 60 æg L-1 Al, As, Cu, Fe, Mn e Ni containing 0.28 mol L-1 HNO3 plus 5 æL Pd(NO3)2 plus 3 æL Mg(NO3)2 were sequentially injected. All measurements were carried out in triplicate and integrated absorbance. The optimized heating program of graphite tube (temperature, ramp time, hold time) was: dry 1 (120oC, 1 s, 10 s); dry 2 (150oC, 5 s, 25 s); pirolysis (1200oC, 10 s, 20 s); atomization (2200oC, 1 s, 6 s) and clean (2550oC, 1 s, 3 s). The characteristic masses were calculated as 37 pg Al, 73 pg As, 31 pg Cu, 16 pg Fe, 9 pg Mn and 44 pg Ni. The lifetime of atomizer was equivalent to ca. 250 heating cycles. Relative standard deviations (n=12) were =3%, =6%, =2%, =3.4%, =1.3% and =2% for Al, As, Cu, Fe, Mn and Ni, respectively. The recoveries of Al, As, Cu, Fe, Mn and Ni added to fuel ethanol samples varied from 77 to 112%, 92 to 114%, 104 to 113%, 91 to 116%, 91 to 122% and 93 to 116%, respectively. Accuracy was checked for Al, As, Cu, Fe, Mn and Ni determination in 20 samples purchased at a local gas stations in Araraquara city, Brazil... (Complete abstract, access undermentioned electronic address) / Mestre

Made available in DSpace on 2014-06-11T19:29:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-07Bitstream added on 2014-06-13T19:38:10Z : No. of bitstreams: 1 oliveira_ap_me_araiq.pdf: 969605 bytes, checksum: 08894db2e370b558f0425c8e9627ff5d (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho propõe um método para a determinação direta e simultânea de Al, As, Cu, Fe, Mn e Ni em álcool etílico hidratado combustível (AEHC) por espectrometria de absorção atômica em forno de grafite (GFAAS), empregando tubo de grafite com aquecimento transversal (THGA) e corretor de fundo por efeito Zeeman longitudinal. Foram avaliados dois tipos de modificadores: a mistura nitrato de paládio + nitrato de magnésio, e o modificador permanente W/Rh. No primeiro caso, as curvas analíticas foram obtidas injetando-se 10 mL das soluções de referência (2,0, 5,0, 10, 20, 30, 40 e 50 mg L-1 Al, As, Cu, Fe, Mn e Ni em meio 0,28 mol L-1 HNO3 ) + 10 mL de etanol P.A. + 5 mL Pd(NO3)2+ 3 mL Mg(NO3)2. Para determinar os analitos, foram injetados 10 mL de amostra + 10 mL de solução 0,28 mol L-1 HNO3 + 5 mL Pd(NO3)2 + 3 mL Mg(NO3)2. No teste de adição e recuperação, foram injetados 10 mL de amostra + 10 mL de solução 60 mg L-1 Al, As, Cu, Fe, Mn e Ni em meio 0,28 mol L-1 HNO3+ 5 mL Pd(NO3)2 + 3 mL Mg(NO3)2. Todas as medidas foram feitas em absorbância integrada e em triplicata. O programa de aquecimento otimizado (temperatura, tempo de rampa, tempo de patamar) foi o seguinte: secagem 1 (120oC, 1 s, 10 s); secagem 2 (150oC, 5 s, 25 s); pirólise (1200oC, 10 s, 20 s); atomização (2200oC, 1 s, 6 s) e limpeza (2550oC, 1 s, 3 s). As massas características foram 37 pg Al, 73 pg As, 31 pg Cu, 16 pg Fe, 9 pg Mn e 44 pg Ni e o tempo de vida do atomizador foi equivalente a aproximadamente 250 ciclos de aquecimento. Os desvios padrões relativos (n=12) foram £3%, £6%, £2%, £3,4%, £1,3% e £2% para Al, As, Cu, Fe, Mn e Ni, respectivamente. As recuperações dos analitos adicionados às amostras coletadas em postos de abastecimento da cidade de Araraquara variaram entre 77-112%, 92-114%, 104-113%, 91-116%, 91-122% e 93-116% para Al, As, Cu, Fe, Mn e Ni, respectivamente... / This work describes a method for direct and simultaneous determination of Al, As, Cu, Fe, Mn and Ni in fuel ethanol by electrothermal atomic absorption spectrometry (GFAAS) with transversely heated graphite atomizer (THGA) and longitudinal Zeeman-effect background corrector. The following modifiers were evaluated: a) the mixture Pd(NO3)2 + 3 æL Mg(NO3)2; b) W/Rh as permanent modifier. Regards to Pd/Mg(NO3)2, analytical curves were obtained by injecting 10 æL of each analytical solutions (2.0, 5.0, 10, 20, 30, 40 and 50 æg L-1 Al, As, Cu, Fe, Mn, Ni in 0.28 mol L-1 HNO3) plus 10 æL of ethanol P.A. plus 5 æL Pd(NO3)2 plus 3 æL Mg(NO3)2. For determination, 10 æL of samples plus 10 æL of 0.28 mol L-1 nitric acid solution plus 5 æL Pd(NO3)2 + 3 æL Mg(NO3)2 were sequentially injected. For analyte addition tests, 10 æL sample plus 10 æL of 60 æg L-1 Al, As, Cu, Fe, Mn e Ni containing 0.28 mol L-1 HNO3 plus 5 æL Pd(NO3)2 plus 3 æL Mg(NO3)2 were sequentially injected. All measurements were carried out in triplicate and integrated absorbance. The optimized heating program of graphite tube (temperature, ramp time, hold time) was: dry 1 (120oC, 1 s, 10 s); dry 2 (150oC, 5 s, 25 s); pirolysis (1200oC, 10 s, 20 s); atomization (2200oC, 1 s, 6 s) and clean (2550oC, 1 s, 3 s). The characteristic masses were calculated as 37 pg Al, 73 pg As, 31 pg Cu, 16 pg Fe, 9 pg Mn and 44 pg Ni. The lifetime of atomizer was equivalent to ca. 250 heating cycles. Relative standard deviations (n=12) were =3%, =6%, =2%, =3.4%, =1.3% and =2% for Al, As, Cu, Fe, Mn and Ni, respectively. The recoveries of Al, As, Cu, Fe, Mn and Ni added to fuel ethanol samples varied from 77 to 112%, 92 to 114%, 104 to 113%, 91 to 116%, 91 to 122% and 93 to 116%, respectively. Accuracy was checked for Al, As, Cu, Fe, Mn and Ni determination in 20 samples purchased at a local gas stations in Araraquara city, Brazil... (Complete abstract, access undermentioned electronic address)

Orientador: Vagner Cavenaghi / Banca: Welington Rocha / Banca: Fernando Bernardi de Souza / Resumo: Cadeias de suprimentos são identificadas e estruturadas para entregar aos consumidores finais que satisfaçam suas necessidades pelo preço que este aceite pagar. A mensuração de custos em cadeia de suprimentos pode apoiar a gestão de operações para garantir competitividade, lucratividade, rentabilidade e atratividade para todos os participantes da cadeia. Este trabalho revisa a literatura de custos, cadeia de suprimentos, mensuração e gestão de custos em cadeia de suprimentos. Apresenta a proposta para mensuração de custos em cadeia de suprimentos por meio do Custeio Variável e para demonstrar a proposta, analisa a cadeia de suprimentos do Etanol Hidratado Combustível. Foram utilizados dados públicos obtidos na Agência Nacional do Petróleo, Gás Natural e Biocumbustível (ANP), Centros de Estudos Avançados em Economia Aplicada - ESALQ (CEPEA) e Conselho dos Produtores de Cana-de-Açúcar, Açúcar e Álcool do Estado de São Paulo (CONSECANA), a partir das usinas, passando pelas distribuidoras e postos de combustíveis até alcançar o consumidor final na cidade de Bauru, comparativamente, no estado de São Paulo, entre janeiro de 2010 e março de 2011. Para compreender a interpretação dos participantes da cadeia de suprimentos sobre preços, custos, margem de contribuição e impacto dos preços de venda na cadeia, entrevistas foram realizadas com representantes dos participantes desta cadeia. A análise dos resultados interpreta as informações obtidas com a proposta para mensuração de custos na cadeia sucroalcooleira, demonstrando as margens de contribuição de cada participante. O uso da proposta para mensuração de custos em cadeia de suprimentos revelou que as maiores margens de contribuição da cadeia são das usinas, que distribuidoras comercializaram o Etanol Hidratado Combustível... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Supply chains are identified and structured to deliver products to end consumers that meet their needs at a price that it agreed to pay. The cost measurement in the supply chain can support operations management to ensure competitiveness, profitability, rentability and attractiveness for all chain participants. This paper reviews the literature of costs, supply chain, measurement and cost management in the supply chain. Presents the proposal for cost measurement in the supply chain through variable costing and to demonstrate the proposal, analyzes the supply chain of Fuel ethanol hydrated. Public data was obtained from the Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (National Agency of Petroleum, Natural Gas and Biofuels - ANP), Centro de Estudos Avançados em Economia Aplicada (Centre for Advanced Studies in Applied Economics) - ESALQ (CEPEA) and Conselho dos Produtores de Cana-de-Açúcar, Açúcar e Álcool do Estado de São Paulo (Council of Producers of Sugar Cane, Sugar and Alcohol of the State of São Paulo - CONSECACA) from plants, through the distributors and gas stations until you reach the end consumer in the city of Bauru, comparatively, in the state of São Paulo, between January 2010 and March 2011. To understand the interpretation of the participants in the supply chain of price, cost, margin contribution and impact of selling prices in chain, interviews were conducted with representatives of the participants in this chain. The analysis of the results interprets the information obtained with the proposal for cost measurement in the sugarcane chain, demonstrating the cotribution, margins of each participant. The use of the proposal for cost measurement in the supply chain revealed that the largest contribution margins in the chain are the plants... (Complete abstract click electronic access below) / Mestre

Doctor of Philosophy / Department of Chemical Engineering / Peter H. Pfromm / The expanded Renewable Fuel Standard (RFS2), established under the Energy Independence and Security Act (EISA) of 2007, mandates the production of 136.3 GL/year of renewable fuels in the U.S. in 2022: 56.8 GL/year of corn-ethanol, 60.6 GL/year of second generation biofuels such as cellulosic ethanol, and 18.9 GL/year of advanced biofuels such as biomass-based diesel. One of the several challenges when a biochemical conversion technique is used to produce bioethanol from corn and cellulosic feedstock is the high energy demand for recovering and purifying ethanol, which is mainly due to the low concentration of ethanol in the fermentation broth and the challenging water-ethanol vapor liquid equilibrium. Dilute ethanol from the fermentation broth can be separated and concentrated aided by salt extractive distillation to directly produce fuel ethanol leading to significant energy savings. Techniques other than highly energy intensive evaporative salt concentration/crystallization and solids drying for recovering salt, which is used to facilitate distillation, have rarely been considered. In this study, a novel combination of electrodialysis and spray drying was investigated to recover the salt. Salt extractive distillation – with salt recovery enabled by electrodialysis – was conceptually integrated in the fermentation broth-ethanol separation trains of corn and cellulosic ethanol facilities and investigated through process simulation with Aspen Plus® 2006.5 to reduce the recovery and purification energy demand of bioethanol. Experiments for the electrodialytic concentration of calcium chloride from high diluate concentrations, prevalent in the salt recovery process when calcium chloride is used as the salt separating agent in the salt extractive distillation of bioethanol, were carried out to determine the fundamental transport properties of an ion exchange membrane pair comprising commercially available membranes for implementation in the conceptual process designs. The maximum calcium chloride concentration achievable through electrodialytic concentration is 34.6 wt%, which is mainly limited by the water transport number. In case of corn-ethanol, retrofitted salt extractive distillation resulted in an energy demand reduction of about 20% and total annual cost savings on the order of MM$0.5 per year when compared with the state-of-the-art rectification/adsorption process for producing fuel ethanol from the beer column distillate. In case of cellulosic ethanol, salt extractive distillation with direct vapor recompression provided the highest energy savings of about 22% and total annual cost savings on the order of MM$2.4 per year when compared with the base case comprising conventional distillation and adsorption for recovering and purifying ethanol from the fermentation broth. Based on the conceptual process design studies, an overall maximum energy savings potential of 1.5*10[superscript]17 J or about 0.14 Quad (as natural gas higher heating value) per year could be estimated for the targeted 56.8 GL of corn-ethanol and 60.6 GL of cellulosic ethanol to be produced in the U.S in 2022 when salt extractive distillation enabled by electrodialysis is implemented in the fermentation broth-ethanol separation trains of the corn and cellulosic ethanol facilities.

No presente trabalho procurou-se avaliar os tipos de metabolismo existentes em espécies e linhagens de Latobacillus isoladas de ambiente de fermentação alcoólica industrial. Para tal, 17, linhagens foram crescidas por 24 horas a 32 ºC, em meio de glicose e frutose (1% de cada açúcar) suplementado com extrato de levedura, minerais e tampão. O crescimento bacteriano foi estimado por plaqueamento e abosrbância a 600 nm, enquanto que no meio de crescimento foram estimados, mediante cromatografia de alta eficiência, os teores de ácido lático, ácido acético e etanol. Os isômeros óticos D(-)- e L(+)-lactato foram dosados enzimaticamente mediante espectrofotometria a 340nm, empregando-se desidrogenases estereoespcíficas. Os resultados mostraram que entre as 17 linhagens de Latobacillus avaliadas foram observados os três tipos de metabolismo : homofermentativo obrigatório (8 linhagens), heterofermentativo facultativo (1 linhagem) e heterofermentativo obrigatório (8 linhagens). Observou-se também uma relação estequiométrica dos produtos formados (lactato, acetato e etanol), condizente com os passos metabólicos característicos de cada grupo. Os resultados também permitem deduzir que quanto à formação dos isômeros óticos, houve predominância das linhagens tipo DL (produção simultânea dos dois isômeros), sobre as linhagens D e L. No entanto foram encontradas linhagens produzindo 100% de um dado isômero (D e L), descortinando a possibilidade de que linhagens isoladas de processo industrial de produção de etanol, possam atender demandas biotecnológicas que requeiram proporções definidas dos isômeros. Foi possível deduzir que a utilização dos teores de ácido lático na avaliação da contaminação bacteriana deve ser considerada com ressalvas, especialmente no caso do emprego do ácido L(+)-lático, e notadamente no caso de comunidades bacterianas complexas. / The aim of the present work was to evaluate the metabolism type of 17 Lactobacilli strains isolated from industrial ethanol fermentation plants. The strains were grown, at 32°C for 24 hours, on a mixture of equal amounts of glucose and fructose as the carbon source, and supplemented with yeast extract, mineral nutrients and buffer. Bacterial growth was estimated either by absorbance at 600nm and by plating. The main end products of bacterial metabolism (lactate, acetate and ethanol) were measured by high performance liquid chromatography, while the stereoisomers, D(-)- and L(+)-lactate were assayed by an enzymatic methodology using stereospecific lactatedehydrogenases. According to the results, all the three types of metabolism were found among the bacteria investigated: obligately homofermentative (8 strains), facultative heterofermentative (1 strain) and obligately heterofermentative (8 strains). Additionally, it was observed a stoichiometric relationship between the major end products (lactate, acetate and ethanol) in agreement with the metabolic pathway proposed for the different bacterial types (homo- and heterofermentative strains). The results have showed a predominance of strains of DL type, regarding the stereoisomers production. However, it was found strains producing a single type of the isomeric form. These findings suggest the possibility to explore the Lactobacilli biodiversity in fuel ethanol fermentation plants for lactate production of chemically pure optical isomers. It was also observed that the use of lactate content for a chemical evaluation of bacterial contamination may be considered with some restrictions, mainly in the case of L(+)-lactate, and particularly in the case of complex bacterial communities.