Papers by Electo Silva Lora
In this study, a CFD model is developed to evaluate the performance of an industrial boiler furna... more In this study, a CFD model is developed to evaluate the performance of an industrial boiler furnace running on sugarcane bagasse. The model was developed in the commercial software ANSYS FLUENT and includes user-defined functions programmed in C language defining devolatilization phenomenon as well as combustion on the grate. The simulation results suggests that devolatilization is the dominant phenomenon through the largest portion of the particle trajectory, and hence an important factor in predicting the thermal fields. On the other hand, the char is burned on the grate or entrained through the furnace outlet. The general efficiency indicators obtained from particle combustion description could then allow us to compare different design and operational alternatives.
The introduction of the negentropy in thermoeconomics represented a great advance in the discipli... more The introduction of the negentropy in thermoeconomics represented a great advance in the discipline, since this magnitude allows quantifying the condenser product in a steam cycle plant, which was not possible before because the condenser is a dissipative component, whose product cannot be expressed in terms of exergy. However, most authors have been applying the negentropy as a fictitious flow, joined up with the exergy flow. This paper aims at opening a discussion about the procedure for negentropy application in thermoeconomics, by showing that: (i) the original procedure leads to some inconsistencies; and (ii), a more recent approach takes all the negentropy advantages, without leading to inconsistencies, by applying the negentropy as a physical exergy component flow.
Fuel and Energy Abstracts, Jan 1, 2011
A thermodynamic information system for diagnosis and prognosis of an existing power plant was dev... more A thermodynamic information system for diagnosis and prognosis of an existing power plant was developed. The system is based on an analytic approach that informs the current thermodynamic condition of all cycle components, as well as the improvement that can be obtained in the cycle performance by the elimination of the discovered anomalies. The effects induced by components anomalies and repairs in other components efficiency, which have proven to be one of the main drawbacks in the diagnosis and prognosis analyses, are taken into consideration owing to the use of performance curves and corrected performance curves together with the thermodynamic data collected from the distributed control system. The approach used to develop the system is explained, the system implementation in a real gas turbine cogeneration combined cycle is described and the results are discussed.► We show how to perform thermodynamic diagnosis of real cycle. ► How to carry on cycle prognosis using corrected performance curves. ► How to account induced malfunctions. ► A real application of the approach is provided.
Energy, Jan 1, 2008
Many performance and emission tests have been carried out in reciprocating diesel engines that us... more Many performance and emission tests have been carried out in reciprocating diesel engines that use biodiesel fuel over the past years and very few in gas turbine engines. This work aims at assessing the thermal performance and emissions at full and partial loads of a 30 kW diesel micro-turbine engine fed with diesel, biodiesel and their blends as fuel. A cycle simulation was performed using the Gate Cycle GE Enter software to evaluate the thermal performance of the 30 kW micro-turbine engine. Performance and emission tests were carried out on a 30 kW diesel micro-turbine engine installed in the NEST laboratories of the Federal University of Itajubá, and the performance results were compared with those of the simulation. There was a good agreement between the simulations and the experimental results from the full load down to about 50% of the load for diesel, biodiesel and their blends. The biodiesel and its blends used as fuel in micro-turbines led to no significant changes in the engine performance and behaviour compared to diesel fuel. The exhaust emissions were evaluated for pure biodiesel and its blends and conventional diesel. The results revealed that the use of biodiesel resulted in a slightly higher CO, lower NOx and no SO2 emissions.
Biomass & Bioenergy, Jan 1, 2007
The palm oil mills are characterized by the availability of considerable amounts of by-products o... more The palm oil mills are characterized by the availability of considerable amounts of by-products of high-energy value such as empty fruit bunches (EFB), fibers, shells and liquid effluents with high content of organics called palm oil mill effluent (POME). A palm oil mill produces residues equivalent to almost three times the amount of oil produced by biomass, showing a huge potential for increasing the power efficiency of the plants and installed power, mainly by the use of by-products in cogeneration plants with high steam parameters and by reducing steam consumption in process. The objective of this paper is to present the results of the study about the cogeneration potential for three representative palm oil mills located in two important palm oil producing regions in Colombia (South-America), fifth palm oil producers of the world. The sizing of the cogeneration system was made assuming it operation during the greatest possible number of hours throughout the year (based on the seasonal availability of fruit) considering parameters for the steam at 2 MPa and 350 °C, using a condensing-extraction turbine. The balance of mass and energy was made by using the Gate Cycle Enter Software, version 5.51, to estimate the potential of electricity generation. The results showed that for fresh fruit bunch (FFB) processing capacities between 18 and 60 t FFB h−1, it is possible to have surplus power ranging between 1 and 7 MW, if the plants are self-sufficient in electric energy and steam for process. With an average Capacity Factor (approximately 0.4), it is possible to expect a generation index of 75 and 160 kWh t−1 FFB when the processing plant is operating or shutdown, respectively, 3 or 4 times better than when a traditional system with a back-pressure steam turbines is used. This analysis used up to 60% of EFB produced in plant as fuel, considering its value as fertilizer for the palm crop. Several economic conditions were considered to estimate the economic and technical feasibility of cogeneration systems in palm oil mill for Colombian palm oil sector.
Renewable & Sustainable Energy Reviews, Jan 1, 2009
The objective of this paper is to give an overview of the programs, projects and technologies rel... more The objective of this paper is to give an overview of the programs, projects and technologies related to the use of biofuels in Brazil. An evaluation of the biomass availability and electricity generation potential for different industrial and agricultural sectors is also presented. As a result an estimation of the overall technical potential for electricity generation based on biofuels in Brazil is presented as well. In addition, the state-of-the-art of different biomass electricity conversing technologies is discussed. A diagram is presented about the organization links and funding of biomass energy research activities in Brazil. Main development and research activities being carried out in this area at the Excellence Group in Thermal Power and Distributed Generation - NEST at the Mechanical Engineering Institute of the Federal University of Itajubá - UNIFEI, located in the city of Itajubá, Brazil are presented.
Energy for Sustainable Development, Jan 1, 1994
Energy for Sustainable Development, Jan 1, 1995
Resumo: As principais fontes de emissões de poluentes atmosféricos das unidades sucro-alcooleiras... more Resumo: As principais fontes de emissões de poluentes atmosféricos das unidades sucro-alcooleiras são as caldeiras a vapor que utilizam bagaço de cana como combustível e emitem, como resultado da combustão, óxidos de carbono (CO e CO 2 ), óxidos de nitrogênio (NO x ) e material particulado. Com este artigo objetivou-se determinar os efeitos da emissão de óxidos de nitrogênio de uma usina de açúcar e álcool na qualidade do ar da região circundante, através do estudo de dispersão de poluentes atmosféricos. Estudou-se o caso de uma usina de grande porte localizada no Estado de São Paulo, Brasil. Na base de medições das concentrações de NO x nos produtos de combustão, avaliaram-se os mecanismos de formação e controle. O estudo de dispersão atmosférica foi realizado com o uso do modelo de dispersão ISCST3 -Industrial Source Complex Short Term version 3, recomendado pela USEPA -United States Environmental Protection Agency, com base em dados meteorológicos horários do local no período de 2002 a 2004. Foram feitos dois tipos de análise da quantidade de NO 2 presente na atmosfera. Primeiro, considerando que há conversão total do NO x em NO 2 , como a maioria das agências recomenda, sendo, neste caso, necessária a aplicação de tecnologias de prevenção e controle da emissão de NO x . Em outra análise considerou-se o fator de Janssen, que descreve a conversão do NO x em NO 2 e NO, considerando as características atmosféricas locais e a concentração de ozônio (O 3 ). Os resultados do estudo de dispersão são apresentados como curvas de isoconcentração de NO x , e com base nessas curvas conclui-se sobre a adequação das tecnologias de prevenção e controle.
Fuel and Energy Abstracts, Jan 1, 2011
Nowadays one of the most important environmental issues is the exponential increase of the greenh... more Nowadays one of the most important environmental issues is the exponential increase of the greenhouse effect by the polluting action of the industrial and transport sectors. The production of biofuels is considered a viable alternative for the pollution mitigation but also to promote rural development. The work presents an analysis of the environmental impacts of the methanol production from sugarcane bagasse, taking into consideration the balance of the energy life cycle and its net environmental impacts, both are included in a LCA (Life Cycle Assessment) approach. The evaluation is done as a case study of a 100,000 t/y methanol plant, using sugarcane bagasse as raw material. The methanol is produced through the BTL (Biomass to Liquid) route. The results of the environmental impacts were compared to others LCA studies of biofuel and it was showed that there are significant differences of environmental performance among the existing biofuel production system, even for the same feedstock. The differences are dependent on many factors such as farming practices, technology of the biomass conversion. With relation to the result of output/input ratio, the methanol production from sugarcane bagasse showed to be a feasible alternative for the substitution of an amount of fossil methanol obtained from natural gas.► High and favorable energy ratio value of methanol from bagasse. ► Sugarcane production has a low participation on environmental impacts. ► The gasification and methanol synthesis can be combined in a biorefinery. ► Farming biomass could cause the environmental impact land competition. ► The trash of sugarcane can be used successfully in methanol production.
Biomass & Bioenergy, Jan 1, 2011
This work presents an experimental study of the gasification of a wood biomass in a moving bed do... more This work presents an experimental study of the gasification of a wood biomass in a moving bed downdraft reactor with two-air supply stages. This configuration is considered as primary method to improve the quality of the producer gas, regarding its tar reduction. By varying the air flow fed to the gasifier and the distribution of gasification air between stages (AR), being the controllable and measurable variables for this type of gasifiers, measuring the CO, CH4 and H2 gas concentrations and through a mass and energy balance, the gas yield and its power, the cold efficiency of the process and the equivalence ratio (ER), as well as other performance variables were calculated. The gasifier produces a combustible gas with a CO, CH4 and H2 concentrations of 19.04, 0.89 and 16.78% v respectively, at a total flow of air of 20 Nm3 h−1 and an AR of 80%. For these conditions, the low heating value of the gas was 4539 kJ Nm−3. Results from the calculation model show a useful gas power and cold efficiency around 40 kW and 68%, respectively. The resulting ER under the referred operation condition is around 0.40. The results suggested a considerable effect of the secondary stage over the reduction of the CH4 concentration which is associated with the decreases of the tar content in the produced gas. Under these conditions the biomass devolatilization in the pyrolysis zone gives much lighter compounds which are more easily cracked when the gas stream passes through the combustion zone.► Obtained results an important for a better phenomenological understanding of processes occurring in two stage gasification reactors. ► The air flow is the fundamental parameter in the operation of downdraft gasifiers. ► CH4 reduction is associated with a decreases in the tar content. ► An enhancement in the thermal cracking of tar is carried out in the two-air downdraft gasifier.
Energy, Jan 1, 2011
Biofuels world production has increased sharply in recent years. Oil reserves depletion, the oil ... more Biofuels world production has increased sharply in recent years. Oil reserves depletion, the oil high price and the confidence in biofuels “carbon neutrality” are the main causes of this phenomenon. However, claims related to the negative consequences of biofuel programs are frequent; mainly those related to the biofuels/food competition and sustainability. This paper aims to contribute for the development of a framework for sustainability indicators as a tool for performance assessment. The most used indicators to measure the biofuels sustainability are: Life Cycle Energy Balance (LCEB), quantity of fossil energy substituted per hectare, co-product energy allocation, life cycle carbon balance and changes in soil utilization. On the other hand, existing assessment tools, such as Life Cycle Assessment (LCA) and Integrated Environmental Assessment (IEA), are compared emphasizing their advantages and disadvantages. Main constraints related to the studied frontiers, as well as the lack of reliable data and their effects are also discussed. Discussions are held on the basis of real life cycle studies carried out by the authors about palm oil biodiesel and different alternatives for the stillage treatment and disposal. Finally, suggestions and recommendations are made to improve existing methodologies for biofuels sustainability evaluation, all this from a south perspective.
Biomass & Bioenergy, Jan 1, 2009
The increasing interest in the recuperation of the biogas coming from organic residues, associate... more The increasing interest in the recuperation of the biogas coming from organic residues, associated with its energetic use is a subject that has been widely discussed. Biogas was merely seen as a sub-product obtained from anaerobic decomposition (without oxygen) of organic residue. In the paper is carried out an evaluation of the quantities of organic residues coming out from the sugar and alcohol industry (vinasse), urban solid and liquid wastes (garbage and sewage) and livestock residues (bovine and swine manure) in Brazil. Finally the electricity generation potential of biogas out of the evaluated sources of organic residues in Brazil is estimated. The results of this study indicate that the potential regarding the production of biogas out of the aforementioned organic residues of electricity production using could meet an energy demand of about 1.05 to 1.13 %. Constraints for biogas energy utilization are identified and discussed.
Renewable Energy, Jan 1, 2009
The use of biodiesel produced from the transesterification of vegetable oils with methanol and et... more The use of biodiesel produced from the transesterification of vegetable oils with methanol and ethanol is currently seen as an interesting alternative to fossil fuels. The output/input energy relation in the biodiesel production life cycle can be an important indicator of the techno-economic and environmental feasibility evaluation of production of biodiesel from different oleaginous plants. Due to increasing environmental concerns about the emissions from fuel-derived atmospheric pollutants, alternative sources of energy have been receiving greater attention. This work does not look to carry out a complete life cycle assessment (LCA) but rather just to focus on the energy balance in the Palm Oil-Derived Methyl Ester (PME) life cycle, taking into account practices in Brazil and Colombia. This work will show the differences between the results attained for the two cases. The output/input energy relation for the evaluated case studies ranged from 3.8 to 5.7, with an average value of 4.8.
Energy Policy, Jan 1, 2006
This work presents an evaluation of the development of Stirling engines and the advantages and th... more This work presents an evaluation of the development of Stirling engines and the advantages and the main obstacles against their widespread introduction in energy-generation practices. It also shows how the economic, technical and environmental characteristics presented by these engines support their insertion in the energy sector. An economic and environmental evaluation of this technology aiming at introducing it in the Brazilian energy scenario is also presented. Changes in legislation, financing and technology within the next few years must encourage the implementation of alternative generation technologies that present lower environmental impacts. Also, tendencies and economical studies are presented, trying to find the optimal condition for this technology to be feasible. The option regarding the trading of carbon credits when biomass is used as fuel is analyzed as well.
Energy Conversion and Management, Jan 1, 1999
This paper discusses the performance characteristics of a 280 kWth fluidized bed gasifier fueled ... more This paper discusses the performance characteristics of a 280 kWth fluidized bed gasifier fueled with bagasse pellets. The gasifier was designed by the State University of Campinas (UNICAMP) and built by TERMOQUIP Energia Alternativa Ltda, based in Campinas, Brazil. Preliminary tests were performed in 1996 to determine the reactor performance as part of the gasification pilot plant test programme. A series of parameters, such as the lower heating value, heat losses, cold and hot gas thermal efficiency and gas yield, were measured as a function of the gasification air factor.
Biomass & Bioenergy, Jan 1, 2004
The Nitrogen Oxides (NOX) have been considered worldwide as one of the major causes of acid rain;... more The Nitrogen Oxides (NOX) have been considered worldwide as one of the major causes of acid rain; one must also acknowledge both its phytotoxic effect and it role in the ozone formation process in the stratosphere. In that way, some countries are monitoring and restricting the emission of such pollutant gases within pre-established standards. Nevertheless, in Brazil, little has been done with relation to the NOX control and the Brazilian and International technical data on bagasse-fuelled boiler emission do not suffice. This work compare measured data on performance and emissions at the Monte Alegre sugarcane mill located in Minas Gerais, with predicted values from empirical correlations of NOX emissions. The influence of both boiler control, such as excess air ratio, and boiler load on emissions was also evaluated.
Energy Conversion and Management, Jan 1, 2005
Global warming and the consequent climatic changes that will come as a result of the increase of ... more Global warming and the consequent climatic changes that will come as a result of the increase of CO2 concentration in the atmosphere have increased the world’s concern regarding reduction of these emissions, mainly in developed countries that pollute the most. Electricity generation in thermal power plants, as well as other industrial activities, such as chemical and petrochemical ones, entail the emission of pollutants that are harmful to humans, animals and plants. The emissions of carbon oxides (CO and CO2) and nitrous oxide (N2O) are directly related to the greenhouse effect. The negative effects of sulfur oxides (SO2 and SO3 named SOx) and nitrogen oxides (NOx) are their contribution to the formation of acid rain and their impacts on human health and on the biota in general. This study intends to evaluate the environmental impacts of the atmospheric pollution resulting from the burning of fossil fuels. This study considers the emissions of CO2, SOx, NOx and PM in an integral way, and they are compared to the international air quality standards that are in force using a parameter called ecological efficiency (ε).
Renewable & Sustainable Energy Reviews, Jan 1, 2009
The imminent decline of the world's oil production, its high market prices and environmental impa... more The imminent decline of the world's oil production, its high market prices and environmental impacts have made the production of biofuels to reach unprecedent volumes over the last 10 years. This is why there have been intense debates among international organizations and political leaders in order to discuss the impacts of the biofuel use intensification.Besides assessing the causes of the rise in the demand and production of biofuels, this paper also shows the state of the art of their world's current production. It is also discussed different vegetable raw materials sources and technological paths to produce biofuels, as well as issues regarding production cost and the relation of their economic feasibility with oil international prices. The environmental impacts of programs that encourage biofuel production, farmland land requirements and the impacts on food production are also discussed, considering the life cycle analysis (LCA) as a tool.It is concluded that the rise in the use of biofuels is inevitable and that international cooperation, regulations and certification mechanisms must be established regarding the use of land, the mitigation of environmental and social impacts caused by biofuel production. It is also mandatory to establish appropriate working conditions and decent remuneration for workers of the biofuels production chain.
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Papers by Electo Silva Lora