Unidade microcontroladora para gerenciamento eletrônico de um motor de combustão interna ciclo Otto.

Nas últimas décadas, a indústria automobilística mundial vem investindo no desenvolvimento tecnológico dos motores, com o objetivo de alcançar melhor eficiência energética e atender às legislações que limitam a quantidade de resíduos tóxicos nos gases de exaustão e menor consumo de combustível. Isso resultou na implantação dos sistemas de gerenciamento eletrônico do motor, que possibilitam funcionalidades para se controlar diversas variáveis do motor, aumentando consideravelmente o rendimento do motor. Este trabalho tem como objetivos explorar a dinâmica de um motor de combustão interna ciclo Otto, os sinais elétricos associados, e os componentes de seu gerenciamento eletrônico. A partir dessas informações, o trabalho apresenta o processo de analise dos sinais elétricos e as estratégias de controle utilizadas em um sistema de gerenciamento real. Assim, são desenvolvidos o hardware e o firmware de uma unidade microcontroladora para gerenciamento eletrônico do motor. O hardware foi elaborado com uma concepção centralizada, ou seja, foi usado apenas um microcontrolador de 32-bit para gerenciar todas as funções. O firmware de controle foi desenvolvido de forma modular baseado em modelos de malha fechada. O modelo matemático do motor foi identificado utilizando técnicas de controle em um veículo real, e a avalidação do modelo foi obtida através de testes em um dinamômetro inercial.

Controle da mistura ar/combustível em um motor a combustão interna: sistema em malha fechada.

O controle da mistura ar/combustível é muito importante para o correto funcionamento dos motores à combustão interna ciclo Otto. A relação entre o ar e o combustível influencia diretamente no funcionamento do motor, na emissão de poluentes e no consumo de combustível. Este trabalho apresenta o desenvolvimento de um controle da mistura ar/combustível a partir do estudo de modelos de malha fechada deste sistema. Esse controle tem por objetivo manter a mistura o mais próxima possível do ponto estequiométrico, a fim de otimizar a taxa de conversão de gases poluentes pelo catalisador, e utiliza um sensor de oxigênio, conhecido como sonda lambda, para realizar a realimentação do sistema, indicando se a mistura está no ponto estequiométrico. Este trabalho também apresenta o desenvolvimento de um compensador em malha fechada para controlar a mistura a/c (ar/combustível) em outros pontos, além do estequiométrico, através do uso de uma sonda lambda de banda larga.

Biodiesel production by acid catalysis with heteropolyacids supported on activated carbon fibers

Different catalysts, based on heteropolyacids supported on activated carbon fibers, have been prepared for palmitic acid esterification reaction. The influence of the catalyst (heteropolyacid) and the support on the catalytic activity have been analyzed. The results prove that an adequate combination of both is required to achieve the most suitable catalysts. Regarding to the heteropolyacid, phosphomolybdic acid seems to be the most suitable appropriate taking into account its lowest leaching. About the support, it must show an optimum microporosity, which must be wide enough to allow the entrance and exit of the reagents and products but not too wide in order to avoid the leaching of the catalyst. In addition, both decreasing of the catalytic activity and its recovery over several cycles have been analyzed.

Biodiesel production by transesterification of sludge in supercritical conditions

In this study wastewater treatment plant (WWTP) sludge was subjected to a reactive pyrolysis treatment to produce a high quality pyro-oil. Sludge was treated in supercritical conditions in the presence of methanol using hexane as cosolvent in a high pressure lab-autoclave. The variables affecting the pyro-oil yield and the product quality, such as mass ratio of alcohol to sludge, presence of cosolvent and temperature, were investigated. It was found that the use of a non-polar cosolvent (hexane) presents advantages in the production of high quality pyro-oil from sludge: increase of the non-polar pyro-oil yield and a considerable reduction of the amount of methanol needed to carry out the transesterification of fatty acids present in the sludge.

Biodiesel wastes: An abundant and promising source for the preparation of acidic catalysts for utilization in etherification reaction

Environmentally friendly sulfonated black carbon (BC) catalysts were prepared from biodiesel waste, glycerol. These black carbons (BCs) contain a high amount of acidic groups, mainly sulfonated and oxygenated groups. Furthermore, these catalysts show a high catalytic activity in the glycerol etherification reaction with tert-butyl alcohol, the activity being larger for the sample prepared with a higher glycerol:sulfuric acid ratio (1:3). The yield for mono-tert-butyl glycerol (MTBG), di-tert-butyl glycerol (DTBG) and tri-tert-butyl-glycerol (TTBG) were very similar to those obtained using a commercial resin, Amberlyst-15. Furthermore, experimental results show that the carbon with the lowest acidic surface group content, BC prepared in minor glycerol:sulfuric acid ratio (10:1), can be chemically treated after carbonization to achieve an improved catalytic activity. The activity of all BCs is high and very similar, about 50% and 20% for the MTBG and DTBG + TTBG, respectively.

Characterization and Degradation of Fatty Acid Methyl Esters and Biodiesel in Artificial Seawater Under UV Exposure Using Raman Spectroscopy

Thesis (Master's)--University of Washington, 2016-06

Upgrading fast pyrolysis liquids:blends of biodiesel and pyrolysis oil

Fast pyrolysis liquid or bio-oil has been used in engines with limited success. It requires a pilot fuel and/or an additive for successful combustion and there are problems with materials and liquid properties. It is immiscible with all conventional hydrocarbon fuels. Biodiesel, a product of esterification of vegetable oil with an alcohol, is widely used as a renewable liquid fuel as an additive to diesel at up to 20%. There are however limits to its use in conventional engines due to poor low temperature performance and variability in quality from a variety of vegetable oil qualities and variety of esterification processes. Within the European Project Bioliquids-CHP - a joint project between the European Commission and Russia - a study was undertaken to develop small scale CHP units based on engines and microturbines fuelled with bioliquids from fast pyrolysis and methyl esters of vegetable oil. Blends of bio-oil and biodiesel were evaluated and tested to overcome some of the disadvantages of using either fuel by itself. An alcohol was used as the co-solvent in the form of ethanol, 1-butanol or 2-propanol. Visual inspection of the blend homogeneity after 48 h was used as an indicator of the product stability and the results were plotted in a three phase chart for each alcohol used. An accelerated stability test was performed on selected samples in order to predict its long term stability. We concluded that the type and quantity of alcohol is critical for the blend formation and stability. Using 1-butanol gave the widest selection of stable blends, followed by blends with 2-propanol and finally ethanol, thus 1-butanol blends accepted the largest proportion of bio-oil in the mixture. © 2013 Elsevier Ltd. All rights reserved.