Thesis (M. Sc.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 119-127).

Thesis (Ph.D.)--University of Melbourne, Dept. of Mechanical Engineering, 2009. / Typescript. Includes bibliographical references (leaves 231-245)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work two differents solvents were used for extraction, carbon dioxide (CO2) in the supercritical state and pressurized liquefied petroleum gas (LPG). The purpose was to extract the oil from the dried avocado pulp comparing these two solvents regarding yield, the time at which the process occurs, adequacy of adjustment of the proposed model to plotted kinetic and the quality of the product obtained by the analysis of their antioxidant activity and gas chromatography analysis coupled with mass spectrometry. Two experimental designs were used, one for each solvent, having as variables the pressure and the temperature with two levels (-1 and +1), and triplicate of the central point (2² + 3 central point), with response the extraction yield of oil. The construction of the kinetic extraction profiles based on the pressure and temperature conditions of experimental design. For the extraction with supercritical CO2 pressure varied in the range of 15 to 25MPa and the temperature ranged from 313 to 353 K, while for extraction with pressurized LPG, pressure and temperature ranged from 0.5 to 2.5 MPa and 293 and 313 K, respectively. It was possible to observe a significant reduction in extraction time using LPG as a solvent, when compared with CO2, and even better extraction yield (57.95%) for LPG and (39.76%) for CO2 in their best extraction conditions experienced. With regard to modeling, it can be seen the appropriateness of the model Sovová the kinetic extraction profiles by means of the adjustment and the kinetic parameters obtained. / Neste trabalho, dois diferentes solventes foram utilizados para a extração, dióxido de carbono (CO2) no estado supercrítico e gás liquefeito de petróleo (GLP) pressurizado. A finalidade do trabalho foi extrair o óleo da polpa de abacate seca, comparando esses dois solventes com relação ao rendimento da extração, o tempo no qual o processo ocorre, a adequação do ajuste do modelo proposto às cinéticas plotadas e à qualidade do óleo obtido, sendo o último avaliado por meio da análise da atividade antioxidante e da análise em cromatografia gasosa acoplada ao espectrômetro de massas. Foram utilizados dois planejamentos experimentais, um para cada solvente, tendo como variáveis a pressão e a temperatura, com dois níveis (-1 e +1) e triplicata do ponto central (2²+3 ponto central), tendo como resposta o rendimento na extração de óleo. A construção dos perfis cinéticos de extração também foi nas condições de pressão e temperatura estabelecidas no planejamento, sendo que para a extração com CO2 supercrítico a pressão variou na faixa de 15 a 25 MPa e a temperatura variou entre 313 a 353 K. Já para a extração com GLP pressurizado, a pressão e temperatura variaram na faixa de 0,5 a 2,5 MPa e 293 e 313 K, respectivamente. Foi possível observar redução significativa no tempo de extração utilizando GLP como solvente quando comparado com CO2, e ainda um melhor rendimento na extração (57,95%) para o GLP e (39,76%) para o CO2 em suas melhores condições de extração testadas. Com relação à modelagem, pode-se observar a adequação do modelo de Sovová aos perfis cinéticos de extração, por meio do ajuste e dos parâmetros cinéticos obtidos.

Orientador: Maria Regina Wolf Maciel / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T22:53:00Z (GMT). No. of bitstreams: 1 Vasconcelos_ClaudiaJovitaGarcia_D.pdf: 8017563 bytes, checksum: dec61d2c1c5b8497e070bd8166b7a606 (MD5) Previous issue date: 2006 / Resumo: A otimização de processes em tempo real tem como objetivo o estudo de técnicas para a integração dos objetivos de controle aos interesses econômicos em aplicações industriais. Neste trabalho, o problema da otimização em tempo real foi abordado para um sistema complexo, com correntes de reciclo de massa e integração energética...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The goal of real-time processes optimization studies is the way to integrate control objectives and economic aspects. In this work, the real-time optimization problem was applied to a high complex system, including mass recycle streams and heat integration...Note: The complete abstract is available with the full electronic document / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

An energy transition can be defined as the adoption of a new primary energy system. As such, it is a structural change that implies a broad shift in technologies and behaviors in order to replace one source of energy with another. Energy transitions motivated by economic, climate, and/or health goals are taking place everywhere in the world. Air pollution, a consequence of fossil fuel-based and solid fuel-based energy use among other sources, is the largest environmental health risk accounting for 6.4 million premature deaths annually. Given the health implications of our energy systems and the social drivers of energy use, access, and burden, energy transitions have the potential to impact health outcomes and associated disparities in a context-dependent manner. The research presented in this dissertation has two objectives: 1) to evaluate the distribution of benefits from energy transitions in the United States (US) and in Ghana; 2) to identify and characterize health outcomes that are relevant to these transitions but are currently understudied. Chapters 2 and 3 are anchored in the US energy policy context. Chapter 2 focuses on the transition away from coal as the primary source of energy in the US and its implications for particulate matter pollution and preterm births. Leveraging a novel dispersion model, I assessed the association between coal PM2.5 and preterm birth rates along with effect modification by race/ethnicity. We observed a positive non-linear relationship between coal PM2.5 and preterm birth rate, which plateaued at higher levels of pollution. The findings of this study suggest that the transition away from coal may have reduced preterm birth rates in the US, but that the association was stronger among non-Hispanic White women compared to non-Hispanic Black women. In Chapter 3, I use a mixed-methods framework to evaluate the first pilot of gas-to-electric stove transition in low-income housing in the US. Through a collaboration with a community-based environmental justice group in New York City, we monitored indoor air quality in participants homes pre- and post-intervention, conducted controlled cooking tests, and carried out focus groups to characterize their experience. Post-intervention, daily NO2 concentrations were 46.3% (95% CI: -67.8%, -10.3%) lower in the intervention arm compared to the control arm. Participants were unanimously pleased with the transition, which had simultaneously improved their cooking experience and partially addressed energy insecurity concerns that plagued their building. Chapters 4 and 5 contribute to the characterization of the health implications associated with Ghana’s commitment to increase access to liquified petroleum gas (LPG) nationally. In Chapter 4, we aimed to describe the country-level incidence of severe cooking-related burns by fuel type in use and to identify effect modifiers. We conducted a nationally representative (n = 7,389) household energy use survey in all 16 regions of Ghana. The incidence rate (95% CI) of cooking-related burns per 1000 person-years among working age females was 8.3 (7.2; 12.0) per 1000 person-years, which was 8 times higher than that of working age males. Among adults, the odds of experiencing a cooking-related burn were doubled among solid fuel users compared to primary LPG users. In Chapter 5, we aimed to understand the effect of an LPG intervention on personal exposure to household air pollution in a peri-urban setting of Ghana and to characterize the distribution of benefits between male and female household members quantitatively and qualitatively. The difference-in-differences results suggested a reduction in exposure to carbon monoxide due to the intervention (-14.2%, 95% CI: -44.1%, 31.6%), which might have benefited male and female participants to the same extent. Importantly, focus group discussions suggested that the ability that LPG affords to cook “on demand” could negatively impact intra-household dynamics and expectations in a way that has not been previously documented. Taken together, our findings from two distinct socioeconomic contexts, highlight the non-uniform distribution of benefits from energy transitions, especially when benefits that are not mediated by air pollution are considered. These results contribute to the understanding that social drivers of inequities should be integrated in the design of energy policies and interventions aimed at generating equitable outcomes. Future directions include a detailed characterization of the context-dependent relative contributions of indoor and outdoor air pollution sources as well as a more systematic integration of quantitative and qualitative methods in policy evaluation.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Made available in DSpace on 2014-12-17T14:08:43Z (GMT). No. of bitstreams: 1 AluisioAN_DISSERT.pdf: 2010955 bytes, checksum: 9d4c76c749552efd65c7156a389b51c8 (MD5) Previous issue date: 2010-11-19 / Universidade Federal do Rio Grande do Norte / Biomass is considered the largest renewable energy source that can be used in an environmentally sustainable. From the pyrolysis of biomass is possible to obtain products with higher energy density and better use properties. The liquid resultant of this process is traditionally called bio-oil. The use of infrared burners in industrial applications has many advantages in terms of technical-operational, for example, uniformity in the heat supply in the form of radiation and convection, with a greater control of emissions due to the passage of exhaust gases through a macroporous ceramic bed. This paper presents a commercial infrared burner adapted with an ejector proposed able to burn a hybrid configuration of liquefied petroleum gas (LPG) and bio-oil diluted. The dilution of bio-oil with absolute ethanol aimed to decrease the viscosity of the fluid, and improving the stability and atomization. It was introduced a temperature controller with thermocouple modulating two stages (low heat / high heat), and solenoid valves for fuels supply. The infrared burner has been tested, being the diluted bio-oil atomized, and evaluated its performance by conducting energy balance. The method of thermodynamic analysis to estimate the load was used an aluminum plate located at the exit of combustion gases and the distribution of temperatures measured by thermocouples. The dilution reduced the viscosity of the bio-oil in 75.4% and increased by 11% the lower heating value (LHV) of the same, providing a stable combustion to the burner through the atomizing with compressed air and burns combined with LPG. Injecting the hybrid fuel there was increase in the heat transfer from the plate to the environment in 21.6% and gain useful benefit of 26.7%, due to the improved in the efficiency of the 1st Law of Thermodynamics of infrared burner / A biomassa ? considerada a maior fonte renov?vel de energia, podendo ser usada de forma ambientalmente sustent?vel. A partir da pir?lise da biomassa ? poss?vel a obten??o de produtos com maior densidade energ?tica e propriedades de uso melhores. O l?quido resultante do seu processo ? tradicionalmente chamado de bio-?leo. A utiliza??o de queimadores infravermelhos em aplica??es industriais apresenta muitas vantagens do ponto de vista t?cnico-operacional, como por exemplo, homogeneidade no fornecimento de calor, na forma de radia??o e convec??o, apresentando um maior controle das emiss?es devido ? passagem dos gases de exaust?o atrav?s de um leito cer?mico macroporoso. O presente trabalho apresenta um queimador infravermelho comercial adaptado com um ejetor proposto capaz de queimar numa configura??o h?brida de g?s liquefeito de petr?leo (GLP) e bio-?leo dilu?do. A dilui??o do bio-?leo com ?lcool et?lico absoluto teve como principal objetivo diminuir a viscosidade do fluido, e melhorar a estabilidade e a atomiza??o. Foi introduzido um controlador de temperatura com termopar modulando dois est?gios (fogo baixo/alto), e eletrov?lvulas para alimenta??o dos combust?veis. O queimador infravermelho foi submetido a testes e ensaios, sendo atomizado o bio-?leo dilu?do, e avaliado o seu desempenho mediante a realiza??o de balan?o de energia. Como m?todo de an?lise termodin?mica para estimativa de carga foi utilizado uma placa de alum?nio localizada na sa?da dos gases de combust?o, sendo a distribui??o de temperaturas medida por termopares. A dilui??o reduziu a viscosidade do bio-?leo em 75,4% e aumentou em 11% o poder calor?fico inferior do mesmo, propiciando ao queimador uma combust?o est?vel atrav?s da atomiza??o com o ar comprimido e queima conjunta com GLP. Injetando o combust?vel h?brido houve aumento na transfer?ncia de calor da placa para o meio ambiente em 21,6% e ganho energ?tico ?til de 26,7%, em fun??o da melhora na efici?ncia da 1? Lei da Termodin?mica do queimador infravermelho

Made available in DSpace on 2015-05-14T13:21:38Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 6846990 bytes, checksum: aec1aa41c1eb06b9173fca41e6af79b0 (MD5) Previous issue date: 2014-06-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Concern about environmental problems triggered the search for new sources of energy and consequently caused an increase in the use of gaseous fuels such as natural gas (NG) and liquefied petroleum gas (LPG). Given this reality, there is growing demand for quality monitoring and supervision of this type of fuel. This paper proposes a flow system for the screening of samples of LPG and NG by near infrared spectrometry (NIR) analysis in order to verify the quality of these fuels in relation to its major concentration of hydrocarbons, propane and methane, respectively. For this, one spectrophotometric flow cell for gas, seven NG containers collectors and one flow system for injection and mixture of gases, as well as its automation (SAIMG) and building management software (GasMixer) were developed. The gas handling equipment and systems for flow enabled the development of SPA-LDA and SIMCA models for screening analysis of samples of LPG and NG. The classification models were constructed and tested with commercial samples that have been previously grouped and analyzed by gas chromatography. Adulterated NG mixtures with nitrogen, compressed air, ethane and lighter fluid were also created. LPG samples were grouped into two different classes depending on the concentration of propane, which have been termed "rich LPG" and "poor LPG" The NG samples were analyzed according to the specified limit for the concentration of methane, which resulted in negative cases ( NG -) and positive (NG +) when they are considered respectively higher or lower than the limits set limit. The results showed that the screening analysis was efficient and robust, reaching 100% accuracy compared samples of LPG and NG test. In addition, the automation of the flow system optimizes all stages of the analysis and enhances their use in future applications / A preocupação com os problemas ambientais impulsionaram a busca por novas fontes de energia e consequentemente provocaram um aumento no uso de combustíveis gasosos como o gás natural veicular (GNV) e gás liquefeito de petróleo (GLP). Diante dessa realidade, cresce também a demanda pelo monitoramento da qualidade e fiscalização desse tipo de combustível. Esse trabalho propõe um sistema em fluxo para a análise screening de amostras de GLP e GNV através da espectrometria no infravermelho próximo (NIR), a fim de verificar a qualidade desses combustíveis em relação a concentração de seus hidrocarbonetos majoritários, o propano e o metano, respectivamente. Para tanto, foram desenvolvidos uma célula espectrofotométrica de fluxo para gás, sete recipientes coletores de GNV e um sistema em fluxo para introdução e mistura de gases, bem como sua automação (SAIMG) e criação de um software de gerenciamento (GasMixer). Os equipamentos de manipulação gasosa e o sistemas em fluxo possibilitaram o desenvolvimento dos modelos SIMCA e SPA-LDA para análise screening de amostras de GLP e GNV. Os modelos de classificação foram construidos e testados com amostras comerciais que foram agrupadas e analisadas previamente por cromatografia gasosa. Também foram criadas misturas adulteradas de GNV com nitrogênio, ar comprimido, etano e fluido de isqueiro. As amostras de GLP foram agrupadas em duas classes distintas em função da concentração de propano, as quais foram denominadas GLP rico e GLP pobre . As amostras de GNV foram analisadas de acordo com o limite especificado para a concentração de metano, o que resultou em casos negativos (GNV !) e positivos (GNV +) quando são considerados respectivamente superiores ou inferiores aos limites estabelecidos. Os resultados demonstraram que a análise screening foi eficaz e robusta, alcançando 100% de acerto em relação as amostras de teste de GLP e GNV. Além disso, a automação do sistema em fluxo otimiza todas as etapas da análise e potencializa seu uso em aplicações futuras.

Orientador: João Batista Fogagnolo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-23T06:53:34Z (GMT). No. of bitstreams: 1 Alcatrao_MaurodosSantos_M.pdf: 3580618 bytes, checksum: b8c15735174b64bdbb58cb26181043c5 (MD5) Previous issue date: 2013 / Resumo: A grande expansão da malha de duto terrestre que vem ocorrendo nos últimos anos no Brasil, principalmente com a construção de linhas únicas para o escoamento de gás natural, representa um novo desafio às equipes de manutenção. A interrupção do fornecimento de gás, devido à parada para manutenção pode representar o colapso de muitas cidades. Situações programadas de paradas operacionais são muito comuns porem envolve recursos humanos e financeiros vultosos, nem sempre disponíveis. Os riscos envolvidos no preparo e condicionamento para a retirada de operação de um gasoduto ou oleoduto, alem dos mesmos cuidados ao retorno normal às atividades requer planejamento minucioso. Nas aplicações envolvendo processos de soldagem sobre o duto em operação, isto é , com fluxo interno na forma gás ou liquido, é necessário garantir a ausência de vazamento de produto, ou seja, onde se tenha o produto totalmente confinado no interior da linha, viabilizando a execução de soldagem e, portanto, não ocorrendo à possibilidade de ignição do produto nela contido. Em uma soldagem executada diretamente sobre uma tubulação com fluxo interno é necessário considerar-se dois tipos de riscos de origem antagônica: Perfuração e trincas a frio. O objetivo deste trabalho é discutir a aplicação do processo de soldagem MAG mecanizado com transferência metálica por curto-circuito com controle de corrente, alternativo ao comumente utilizado, eletrodo revestido, com intuito de obtenção de maior segurança nas aplicações para baixas espessuras na parede do duto, além de almejar maior produtividade e qualidade das soldagens / Abstract: The great expansion of the onshore pipeline grid that has been occurring in recent years in Brazil, especially with the construction of single lines for the flow of natural gas, represents a new challenge to the maintenance teams. The interruption of gas supply due to maintenance downtime can represent the collapse of many cities. Scheduled stops operating situations are very common however involve financial and human resources heavily, not always available. The risks involved in the preparation and conditioning for the withdrawal of operation of a pipeline or pipeline, besides the same care to return to normal activities require careful planning. In applications involving welding process on the pipe in operation, ie, internal flow with the gas or liquid form, it is necessary to ensure no leakage of product, ie, where the product has completely confined within the line, allowing performing welding and therefore not occurring the possibility of ignition of the product contained therein. In welding performed directly on a pipe with internal flow is necessary to consider two types of risks antagonistic source: Drilling and cracking cold. The objective of this study and discuss the application of mechanized MAG welding process with metal transfer short-circuit with current control, alternative to the commonly used electrode coated with the aim of achieving greater safety in applications for low thicknesses in the duct wall , and aim for higher productivity and quality of the welds / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica