Uso de mistura ternária renovável como substituta do diesel de petróleo.

O etanol é um combustível de baixo custo de produção e grande disponibilidade no Brasil, em função das altas produção e produtividade da cana-de-açúcar. Já a produção de óleos vegetais não é tão elevada e apresenta custo maior, pois a soja, oleaginosa mais cultivada, é um vegetal de baixo rendimento em óleo. Portanto, produzir sacarose é mais fácil e mais barato que produzir óleo. Todavia, para alimentar motores Diesel, é necessário um tipo de combustível com características específicas que são encontradas no petrodiesel e nos óleos vegetais transesterificados (biodiesel). Assim sendo, procurou-se formular uma mistura de combustíveis para motores Diesel que contivesse grandes proporções de etanol, porém, porção razoável de biodiesel para que os mínimos requisitos de combustão fossem atendidos. Misturas volumétricas contendo 50% de biodiesel de soja, 40% de etanol anidro e 10% de óleo refinado de soja foram empregadas em um pequeno motor Diesel para substituição do diesel convencional, o que conduziu a funcionamento regular, menor emissão de particulados, maior eficiência térmica e menor desgaste do motor. Pretende-se, agora, testar a mistura ternária renovável em veículos de diversas unidades da Embrapa, para que haja sólido embasamento a fim de propor à Petrobrás uma nova composição do óleo diesel utilizado no Brasil. O caráter inovador dessa pesquisa está em julgamento pela Área de Inovação Tecnológica com vistas a proteger intelectualmente a ideia em nome da Embrapa

Permeability and nanoparticle filtration assessment of cordierite-bonded porous SiC ceramics

Cordierite bonded porous SiC ceramics having pore fractions (epsilon) between 0.33 and 0.72 and pore sizes of 6-50 mu m, flexural strength of 5-54 MPa, and elastic modulus of 6-42 GPa were prepared by oxide bonding at 1350 degrees C in air compacts of SiC, Al2O3 and MgO powders with petroleum coke (PC) as the sacrificial pore former. To test the applicability of the porous ceramics in the fluid flow field, air permeation behavior was studied with fluid superficial velocity from 0.083 to 0.90 m s(-1) and at 26-750 degrees C. The Darcian, k(1), and the non-Darcian, k(2), permeability coefficients were evaluated by fitting Forchheimer's equation to the experimental results. The temperature dependence of the permeability coefficients was explained from structural changes occurring during test conditions. The collection efficiency of filter ceramics (epsilon = 0.62-0.68) operating on removal of nanosized aerosol particles with sizes varying from 7 to 300 nm was determined by counting particles before and after filtration at a fluid superficial velocity of 0.1 m s(-1). Experimental results showed variation of collection efficiency from 96.7 to 99.9%. The size-selective fractional collection efficiency at different porosity levels was derived by using the well-known single-collector efficiency model considering some boundary conditions, and the model data were validated with experimental results. The test results were used for examination of the applicability of the filter ceramics in nanoparticle filtration processes

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

This work investigates the catalytic activity of geopolymers produced using two different alkali components (sodium or potassium) and four treatment temperatures (110 to 700 \ub0C) for the methyl transesterification of soybean oil. The geopolymers were prepared with metakaolin as an aluminosilicate source and alkaline activating solutions containing either sodium or potassium in the same molar oxide proportions. The potassium-based formulation displayed a higher specific surface area and lower average pore size (28.64-62.54 m\ub2/g; 9 nm) than the sodium formulation (6.34-32.62 m\ub2/g; 17 nm). The reduction in specific surface area (SSA) after the heat treatment was more severe for the sodium formulation due to the higher thermal shrinkage. The catalytic activity of the geopolymer powders was compared under the same reactional conditions (70-75 \ub0C, 150% methanol excess, 4 h reaction) and same weight amounts (3% to oil). The differences in performance were attributed to the influences of sodium and potassium on the geopolymerization process and to the accessibility of the reactants to the catalytic sites. The Na-based geopolymers performed better, with FAME contents in the biodiesel phase of 85.1% and 89.9% for samples treated at 500 and 300 \ub0C, respectively. These results are competitive in comparison with most heterogeneous base catalysts reported in the literature, considering the very mild conditions of temperature, excess methanol and catalyst amount and the short time spent in reactions

Non-Darcian Behavior of Pyrolysis Gas in a Thermal Protection System

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83565/1/AIAA-44103-182.pd