The reproductive biology of Cybistax antisyphilitica (Bignoniaceae), a characteristic tree of the South American savannah-like "Cerrado" vegetation

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

Determination of the activation energies of beef tallow and crude glycerin combustion using thermogravimetry

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Experimental aspects of partially premixed pulsating combustion

The pulsating combustion process has won interest in current research due to indications that its application in energy generation can offer several advantages, such as: fuel economy, reduced pollutants formation, increased rate of convective heat transfer and reduced investment, when compared with conventional techniques. An experimental study has been conducted with the objective of investigating the effects of combustion driven acoustic oscillations in the emission rates of combustion gases, especially carbon monoxide and nitrogen oxides. The experiments were conducted in a water-jacketed 1-m long by 25-cm internal diameter stainless steel vertical tube. The combustor operated with liquefied petroleum gas (LPG) in both oscillatory and non oscillatory conditions, under the same input conditions. Part of the reactant mixture was excited acoustically, before the burner exit, by a speaker positioned strategically. The burner was aligned with the chamber longitudinal axis and positioned at its bottom. The experiments were conducted for 0.16 g/s of LPG burning in stoichiometric equivalence ratio. The main conclusions were: a) the pulsating combustion process produces more uniform fuel/air profile than the non pulsating process, b) close to stoichiometric equivalence ratio the pulsating combustion process generates higher rates of NO x; c) the frequency has a strong influence in NO x emission, but the pressure amplitude has a weak influence; d) the presence of the acoustic field may change drastically the combustion gas emissions in diffusion flames, but in pre-mixed flames the influence is not as strong.

Sintering of cobalt and strontium doped lanthanum chromite obtained by combustion synthesis

Lanthanum chromite (LaCrO3) is one of the most adequate materials for use as interconnector in solid oxide fuel cell (SOFC) applications, due to its intrinsic properties, namely its good electrical conductivity and resistance to environment conditions in fuel cell operations. Due to difficulties in sintering, additives are usually added to help in the densification process. In this work, the influence of added cobalt and strontium, in the sintering of LaCrO3 obtained by combustion synthesis was studied. The starting materials were respectively nitrates of chromium, lanthanum, cobalt and strontium, and urea was used as fuel. The results show that by increasing the strontium and cobalt concentrations it is possible to reduce the temperature of sintering. Using both additives, the sintering processes took place in lesser times than normally used for this material, as well as greater values of density were attained.

The influence of the flame structure on the combustion oscillations in a cylindrical chamber

An experimental study has been conducted with the objective of investigating the effects of the flame structure in the combustion oscillation conditions into a laboratorial scale cylindrical chamber. The experiments were conducted in a water-jacketed 1-m long by 25-cm internal diameter stainless steel vertical tube. The combustor operated with liquefied petroleum gas (LPG) in both oscillatory and non oscillatory conditions, under the same input conditions. Part of the reactant mixture was excited acoustically, before the burner exit, by a speaker positioned strategically. The burner was aligned with the chamber longitudinal axis and positioned at its bottom. The experiments were conducted for 0.16 g/s of LPG burning in stoichiometric equivalence ratio. To analyze the flame structure the image tomographic reconstruction process were used, and the resultant images were associated to the oscillatory conditions (frequency and amplitude) into the combustion chamber. The main conclusions were: 1) when the flame premixed condition increase, for example 60% of the total air flow rate is premixed with LPG, the region of intense energy released is close to burner exit and strong amplitudes of oscillation (close to 50 mbar) were obtained into the chamber; 2) for long flames, predominantly diffusive flames, just weak amplitudes were detected, in the spite of the speaker exiting the premixed flow; 3) when the energy is released distributed through the combustion chamber, the long flame acts like a baffle. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Influence of specimen size, tray inclination and air flow rate on the emission of gases from biomass combustion

Experiments of biomass combustion were performed to determine whether specimen size, tray inclination, or combustion air flow rate was the factor that most affects the emission of carbon dioxide, carbon monoxide, and methane. The chosen biomass was Eucalyptus citriodora, a very abundant species in Brazil, utilized in many industrial applications, including combustion for energy generation. Analyses by gas chromatograph and specific online instruments were used to determine the concentrations of the main emitted gases, and the following figures were found for the emission factors: 1400 ± 101 g kg-1 of CO2, 50 ± 13 g kg-1 of CO, and 3.2 ± 0.5 g kg-1 of CH4, which agree with values published in the literature for biomass from the Amazon rainforest. Statistical analysis of the experiments determined that specimen size most significantly affected the emission of gases, especially CO2 and CO. •Statistical analysis to determine effects on emission factors.•CO2, CO, CH4 emission factors determined for combustion of Eucalyptus.•Laboratory results agreed with data for Amazonian biomass combustion in field tests.•Combustion behavior under flaming and smoldering was analyzed. © 2013 Elsevier Ltd.

Glycerol: Production, consumption, prices, characterization and new trends in combustion

The demand for petroleum has been rising rapidly due to increasing industrialization and modernization. This economic development has led to a huge demand for energy, most of which is derived from fossil fuel. However, the limited reserve of fossil fuel has led many researchers to look for alternative fuels which can be produced from renewable feedstock. Increasing fossil fuel prices have prompted the global oil industry to look at biodiesel, which is from renewable energy sources. Biodiesel is produced from animal fats and vegetable oils and has become more attractive because it is more environmentally friendly and is obtained from renewable sources. Glycerol is the main by-product of biodiesel production; about 10% of the weight of biodiesel is generated in glycerol. The large amount of glycerol generated may become an environmental problem, since it cannot be disposed of in the environment. In this paper, an attempt has been made to review the different approaches and techniques used to produce glycerol (hydrolysis, transesterification, refining crude glycerol). The world biodiesel/glycerol production and consumption market, the current world glycerin and glycerol prices as well as the news trends for the use of glycerol mainly in Brazil market are analyzed. The technological production and physicochemical properties of glycerol are described, as is the characterization of crude glycerol obtained from different seed oil feedstock. Finally, a simple way to use glycerol in large amounts is combustion, which is an advantageous method as it does not require any purification. However, the combustion process of crude glycerol is not easy and there are technological difficulties. The news and mainly research about the combustion of glycerol was also addressed in this review. © 2013 Elsevier Ltd.

Economy of combustion processes

Includes bibliography

Renewable energy sources in Latin America and the Caribbean: situation and policy proposals

Includes bibliography

Balanço de espécies químicas em microbacias sob utilização agrícola - região de Botucatu/SP

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

Preparação pelo processo sol-gel de pós redispersáveis, filmes finos densos e materiais mesoporosos de óxido de titânio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparative study for hardwood and softwood forest biomass: Chemical characterization, combustion phases and gas and particulate matter emissions

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

Internal Combustion Engine's Throttle Control as a Motivational Theme for Teaching Microprocessors Systems Lab Classes

The increased fuel economy and driveability of modern internal combustion engine vehicles (ICEVs) are the result of the application of advanced digital electronics to control the operation of the internal combustion engine (ICE). Microprocessors (and micro controllers) play a key role in the engine control, by precisely controlling the amount of both air and fuel admitted into the cylinders. Air intake is controlled by utilizing a throttle valve equipped with a motor and gear mechanism as actuator, and a sensor enabling the measurement of the angular position of the blades. This paperwork presents a lab setup that allows students to control the throttle position using a microcontroller that runs a program developed by them. A commercial throttle body has been employed, whereas a power amplifier and a microcontroller board have been hand assembled to complete the experimental setup. This setup, while based in a high-tech, microprocessor-based solution for a real-world, engine operation optimization problem, has the potential to engage students around a hands-on multidisciplinary lab activity and ignite their interest in learning fundamental and advanced topics of microprocessors systems.