Viabilidade técnica e econômica da substituição de fontes convencionais de energia por biogás em assentamento rural do Estado de São Paulo

O objetivo deste estudo foi avaliar a viabilidade econômica da implantação de dois biodigestores com uso de dejetos animais em área do Assentamento de Trabalhadores Rurais no município de Itaberá - SP, no ano de 2005; um deles para o fornecimento de energia para os domicílios e outro para as atividades produtivas. Foram avaliados os benefícios referentes ao fornecimento de energia elétrica e térmica, a partir do biogás, para cinco domicílios da agrovila do assentamento e para as atividades produtivas, comparativamente aos custos de construção e operação para produção de biogás. Os resultados mostraram a viabilidade econômica da produção de gás em ambos os biodigestores. Foram gerados benefícios no valor de R$ 3.698,00 por ano e R$ 9.080,57 por ano, nos biodigestores para os domicílios e produção, respectivamente; bem como o equivalente a R$ 1.478,28 por ano referentes à produção de biofertilizante. O custo anual do processo é de R$ 1.218,50 em cada biodigestor. O prazo de recuperação do investimento é de 2,5 anos e 11 meses, para a produção de biogás nos domicílios e na produção, respectivamente. Os resultados podem ser utilizados para subsidiar políticas públicas direcionadas ao aproveitamento de biomassa para a produção de energia a baixos custos no segmento da agricultura familiar.

Production and characterization of glucoamylase from fungus Aspergillus awamori expressed in yeast Saccharomyces cerevisiae using different carbon sources

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

On the entropy operator for the general SU(1,1) TFD formulation

In this Letter, an entropy operator for the general unitary SU(1, 1) TFD formulation is proposed and used to lead a bosonic system from zero to finite temperature. Namely, considering the closed bosonic string as the target system, the entropy operator is used to construct the thermal vacuum. The behaviour of such a state under the breve conjugation rules is analyzed and it was shown that the breve conjugation does not affect the thermal effects. From this thermal vacuum the thermal energy, the entropy and the free energy of the closed bosonic string are calculated and the appropriated thermal distribution for the system is found after the free energy minimization. (C) 2004 Elsevier B.V. All rights reserved.

Optical studies of the correlation between interface disorder and the photoluminescence line shape in GaAs/InGaP quantum wells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

ZERO SOUND-VELOCITY IN PI, RHO-MESON GASES

Sharp transitions are perhaps absent in QCD, so that one looks for physical quantities which may reflect the phase change. One such quantity is the sound velocity which was shown in lattice theory to become zero at the transition point for pure glue. We show that even in a simple bag model the sound velocity goes to zero at temperature T = T(v) not-equal 0 and that the numerical value of this T(v) depends on the nature of the meson. The average thermal energy of mesons goes linearly with T near T(v), with much smaller slope for the pion. The T(v) - s can be connected with the Boltzmann temperatures obtained from transverse momentum spectrum of these mesons in heavy-ion collision at mid-rapidity. It would be interesting to check the presence of different T(v) - s in present day finite T lattice theory.

Drying kinetics of tomato by using electric resistance and heat pump dryers

Drying kinetics of tomato was studied by using heat pump dryer (HPD) and electric resistance dryers with parallel and crossed airflow. The performance of both systems was evaluated and compared and the influence of temperature, air velocity, and tomato type on the drying kinetics was analyzed. The use of HPD showed to be adequate in the drying process of tomatoes, mainly in relation to the conversion rate of electric energy into thermal energy. The heat pump effective coefficient of performance (COPHT,EF) was between 2.56 and 2.68, with an energy economy of about 40% when compared to the drying system with electric resistance. The Page model could be used to predict drying time of tomato and statistical analysis showed that the model parameters were mainly affected by drying temperature.

Cogeneration for small users: case studies for Brazilian tertiary sector

In this paper we present technical and economic studies of cogeneration systems utilizing combustion engines and gas turbines, applied in two establishments of the tertiary sector, regarding Brazilian conditions (according to Silveria, 1994). In the first step cogeneration systems utilizing combustion engines associated to absorption refrigeration systems are studied, in which electricity and cold air for a university building rate produced. In the second step some possibilities of the use of the gas turbine in cogeneration systems for a hospital are shown. In this case, the exhaust gases are utilized for the production of steam in a heat recovery steam generator (HRSG) or cold water in an absorption refrigeration system (for air conditioning) for the hospital building. The dynamic increment of the energy demand of Brazilian tertiary sector in last years can increase the installation of these cogeneration system (in compact version) as well as strengthen the development of the decentralized energy generation in Brazil.

Relaxation effects on the negatively charged Mg impurity in zincblende GaN

The electronic structure of Mg impurity in zincblende (c-)GaN is investigated by using the ab initio full potential linear-augmented plane-wave method and the local density-functional approximation. Full geometry optimization calculations, including nearest and next-nearest neighbor displacements, are performed for the impurity in the neutral and negatively charged states. A value of 190 ± 10 meV was obtained for the Franck-Condon shift to the thermal energy, which is in good agreement with that observed in recent low temperature photoluminescence and Hall-effect measurements. We conclude that the nearest and next-nearest neighbors of the Mg impurity replacing Ga in C-GaN undergo outward relaxations which play an important role in the determination of the center acceptor energies.

Análise econômico-energética de utilização de resíduo industrial florestal para geração de energia térmica: um estudo de caso

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Estudo da viabilidade técnica e econômica para aproveitamento de cascas de eucalyptus gerados no processo de fabricação de painéis de madeira

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Alternativas para a cogeração de energia em uma indústria de chapas de fibra de madeira

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Levantamento de coeficientes de desempenho de armazenador térmico associado a refrigerador doméstico modificado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise das perdas na produção contínua de extração de óleo de soja: estudo de caso no método de extração por solvente

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Controle nebuloso aplicado em asas adaptativas utilizando ligas de memória de forma

Pós-graduação em Engenharia Mecânica - FEIS

Modelagem de ciclos combinados integrados à incineração de resíduos sólidos municipais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)