Dissertações em Engenharia Mecânica (Mestrado) - PPGEM/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2342

O Mestrado Acadêmico pertence ao Programa de Pós-Graduação em Engenharia Mecânica (PPGEM) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA).

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Agora exibindo 1 - 14 de 14

Acesso aberto (Open Access)
Análise da influência dos solutos Zr e Ti sobre as propriedades mecânica, elétrica e de termorresistência de uma liga Al-Cu-Fe-Si destinada a Tx e a Dx de energia elétrica
(Universidade Federal do Pará, 2012-01-10) MACHADO, Paulo Cordeiro; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
The global energy context presents a steady increase in electricity consumption in the last century, thus requiring the search for new materials for use in wire and cable conductors of electricity. From these demands for new materials, was developed an analysis of the influence of solute titanium and zirconium in the modification of important characteristics of the Al-Cu-Fe-Si alloy, destined to be the middle conductor of electricity, aiming to get properties resistant to heat. For this study, the alloys were obtained by direct casting in Ushaped metal ingots, from the Al-EC, standing at the base levels of 0.05 wt% Cu, [0.24 to 0.28] wt% Fe and 0.7 wt% Si, and then inserting the contents of 0.26 wt% Zr and 0.26 wt% Ti. The experiments were, divided in two steps, STEP A and STEP B , respectively. In order to characterize mechanical, electrical and structure of alloys. The specimens after cold rolling (in diameters of 2.7, 3.0, 3.8 and 4.0 mm) were analyzed without heat treatment (STT) and with heat treatment (CTT): 230 °C for one hour, according to the protocol COPEL (Companhia Paranaense de Energia Elétrica), 310 °C and 390 °C for one hour, to evaluate the heat resistance at higher temperatures, thermal stability and analyze the microstructures developed in these heat treatments (TT). It was found that Ti has more capacity to refine the grain compared to Zr, which has less refined grains, but with better physical properties are presented and heat resistant.
Acesso aberto (Open Access)
Análise experimental das emissões de uma microturbina a gás utilizando biodiesel
(Universidade Federal do Pará, 2011) FERREIRA, Ricardo Wallace Machado; NOGUEIRA, Manoel Fernandes Martins; http://lattes.cnpq.br/2324813094737469; GUERRA, Danielle Regina da Silva; http://lattes.cnpq.br/6750321690921056
This work presents an experimental study with the use of biodiesel, diesel, natural gas and mixtures operating in a gas microturbine as fuel. The main objective of the study is to understand the emissions produced by the fuels. The experimental apparatus was constructed entirely for the purpose of performing tests with natural gas and changes in the supply line were made for the supply of liquid fuel, no changes were made in the combustion chamber. The experiments were performed for rotations of 45.000rpm, 50.000rpm, 55.000rpm and 60.000rpm. By the experimental difficulties encountered in understanding the combustion process and its emissions, a complementary procedure for the emissions estimation is presented, resolving and estimating the composition of emissions through ComGas V1.0 software which calculates combustion in the equilibrium. As a contribution, we present experimental data for CO, CO2, O2, gas exhaust temperature, mass flow rates, molar flow rates, and energy characterizing of fuels and mixtures.
Acesso aberto (Open Access)
Caracterização da liga 6101 refinada com a adição de diferentes teores de cobre e solidificadas em molde unidirecional horizontal e em molde "U"
(Universidade Federal do Pará, 2007) FEITOSA, Johnyson Pereira; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
The 6101 alloy (series 6xxx) was modified with addition of 0.05% and 0.3% of copper and with additions of grain refiners as Al-Ti-B. The alloys were thermally characterized (heat transfer coefficient of metal / mold, displacement speed of liquidus isothermal and cooling rate), mechanically (tensile strength and toughness module) and electrically (electric resistivity, specific resistance and power conductivity) using two forms of pouring out: one is horizontal directional solidification and the other into the "U" mold. By horizontal directional solidification was possible characterize the macrostructure, influenced by refiners of grain and by viscosity that copper provides in the metal / mold efficiency of alloys researched, modifying the thermal, mechanical and electrical properties. The solidification in "U" mold makes possible evaluates the mechanical and electrical properties, seeing the forming process variables of alloys, as forming rate, tensile strength, toughness and electric resistivity, power conductivity and electric resistance, using the specimens obtained in several diameters. For the “U” mold were casting more two alloys to evaluation, Al-0,6Mg-0,4Si-0,1Cu and Al-0,6Mg-0,4Si-0,2Cu. The mechanical and electrical properties had been influenced by cold working, copper content and shrinkage void presents into alloys structures.
Acesso aberto (Open Access)
Caracterização de um gaseificador do tipo downdraft
(Universidade Federal do Pará, 2010) ALVES, Charles Denys da Luz; NOGUEIRA, Manoel Fernandes Martins; http://lattes.cnpq.br/2324813094737469
The gasification is a thermo-chemical conversion of biomass in fuel gas which can be used as a fuel in internal combustion engines or as a syngas for chemical industry. To quantify the performance of a gasifier we must quantify the energy contained in the gas produced and relate to the amount of energy contained in the biomass that feeds the gasifier, Energy Efficiency, and even with regard to levels of carbon converted from biomass into the gas produced, Carbon Conversion. This paper assesses the energy efficiency and carbon conversion in a prototype of an Indian downdraft gasifier type produced by a local company (Floragás). The gasifier nominal parameters are: gas production capacity of 45 kWt, açaí seeds consumption of 15 kg/h. The gasifier reactor dimensions are ID 150 mm and height in 2000 mm). Its energy efficiency and rate of carbon conversion were quantified, the drop in pressure due to the reactor bed and the gas temperature were also measured at the reactor exit and quantified the concentration of tar, particulate and not condensable gases (CO, CO2, CH4, SO2, N2 and NOx) in the flue gas after cleaning system.
Acesso aberto (Open Access)
Desenvolvimento e caracterização acústica de painéis multicamadas unifibra, multifibras e mesclados, fabricados a partir de fibras vegetais
(Universidade Federal do Pará, 2009-12-01) BASTOS, Leopoldo Pacheco; MELO, Gustavo da Silva Vieira de; http://lattes.cnpq.br/8850986817571748
In a time when high noise levels are part of people’s daily lives, the search for noise control is not only evident, but providential. Currently, noise pollution, to a worldwide level, is not more serious than air and water pollution only. In Brazil, the situation is not different because it is estimated that more than 15 million people have some kind of hearing loss degree due to this environmental problem. Acoustic devices such as panels, barriers, etc., when of high efficiency, generally, are of difficult acquisition due to high costs, turning, in many cases, their use impracticable, mainly for limited budget small-sized companies. Thus, alternative solutions, starting with new acoustic materials that are less costly and have satisfactory performance, emerge as a great option. Considering the global environmental trends, the use of vegetable fibers is a great opportunity to aggregate value, and technological development for agricultural producing countries, like Brazil. Beyond that, such fibers are easy to get, exist in abundance, are non toxic and derive from renewable sources. This work will present the methodology of development of panels made from vegetable fibers (açaí, coconut, sisal and palm) and binding agent based on acrylate and water, as well as the methodology used to characterize them acoustically on a scale model reverberant chamber, based on ISO 354/1999. These panels are made of pressed layers of fibers interspersed with layers of binding agent. The fibers are extracted, washed, dried, and treated when necessary, while the binding agent is obtained commercially. The panels sound absorption data are obtained through a four channel frequency analyzer using the noise interruption method. Comparison of results between alternative and conventional material based panels allows to the conclusion that the acoustical performance shown by some newly developed panels are very satisfactory, since their sound absorption coefficients were compatible, and in some cases, higher to those presented by conventional materials in a given frequency range. Finally, a numerical-experimental comparison is performed in order to evaluate the influence of sisal absorbing panels over the acoustics characteristics of a small classroom.
Acesso aberto (Open Access)
Efeito de teores de Zr sobre as propriedades mecânicas e elétricas de ligas Al-Ec-Si aplicadas na elaboração de ligas para Tx e Dx de energia elétrica
(Universidade Federal do Pará, 2010) SANTOS, Washington Luis Reis; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
This paper aims to develop an analysis of the influence of Zr in the modification of important characteristics of Al-EC-Si alloys used in electrical conductors, aiming to obtain heat resistant properties. For this study, the alloys were obtained by direct casting in a U-shaped ingot mold, from the Al-EC, with a base Si content of 0,7%, and then varying with different amounts of Zr. Intending o precipitate second phase particles called dispersoid, whose main characteristic is the retention of the deformed microstructure when exposed to high temperatures, it was necessary to submit the alloys to a heat treatment of 310 ºC for 24 hours in order to cause the appearance of fine dispersoids of Al3Zr. Two steps were established to obtain the results: The Step I was composed of solidification, machining and deformation obtained with the alloys, generating the wires used in all tests. The Step II repeats the same processes adopted in the Step I, however a heat treatment of 310 ºC for 24 hours was made before deformation. The heat resistance characterization of the specimens of each alloy followed the requirements of COPEL (Companhia Paranaense de Energia Elétrica ) when submitted to temperatures of 230 ºC for 24 hours, and heat treatments at temperatures of 310 ºC and 390 ºC were also made to evaluate the thermal stability of the alloys. In general, it was observed that crescent contents of Zr results in a grain refinement and a increase of the Ultimate Tensile Strength and thermal stability of the alloy, both in the Step I and Step II. It was also observed that in Step I, the electrical conductivity was severely affected by the Zr contents and the addition of heat treatment in Step II increased the electrical conductivity of the alloy, particularly to diameters that suffered higher deformation.
Acesso aberto (Open Access)
Estudo de técnicas de análise modal operacional em sistemas sujeitos a excitações aleatórias com a presença de componente harmônico
(Universidade Federal do Pará, 2006-02-17) CRUZ, Sérgio Luiz Matos da; MESQUITA, Alexandre Luiz Amarante; http://lattes.cnpq.br/3605920981600245
Traditional modal parameter identification usually require measurements of both the input force and the resulting response in laboratory conditions. However, when modal properties are to be identified from large structures in operation, usually the possibilities to control and measure the loading on the structure is rather limited. In this case, the modal testing is usually performed using response data only. Operational Modal Analysis (OMA) or Operational Modal Testing is a method where no artificial excitation needs to be applied to the structure or force signals to be measured. In this case, the modal parameters estimation is based upon the response signals, thereby minimizing the work of preparation for the test. However, standard OMA techniques, such as NExT, are limited to the case when excitation to the system is a white stationary noise. The NexT assumes that the correlation functions are similar to the impulse response functions, and then, traditional time domain identification methods can be applied. However, if harmonic components are present in addition to the white noise, these components can be misunderstood as natural modes in the plot of response spectrum. In this work, it is shown that it is possible identify if a peak in the response spectrum correspond to a natural mode or an operational mode. It is achieved through the application of the probability density function. It is also presented a modification in the LSCE algorithm in such manner that it can support harmonics in the operational excitation. In order to validate the methods presented in this work, it is shown numerical and experimental cases. In the former, results for a mass-spring-damper of five degree of freedom are presented, and in the latter a beam supporting an unbalanced motor is analyzed.
Acesso aberto (Open Access)
Implementação e análise do desempenho de técnicas de monitoramento através de medição de vibração e correlação com corrente estatórica
(Universidade Federal do Pará, 2010-06-16) JESUS, Keliene Maria Sousa de; SOEIRO, Newton Sure; http://lattes.cnpq.br/7303174583088137
The growing demand for electricity coupled with the great importance of this sector to the national economic system has led the government and private companies to invest in studies for improving the performance of the systems involved in this process, given the important gains that this initiative can produce. In this context, this work is a contribution to the study of the development of a methodology for diagnosis of defects to the machine number three hydro Hydropower Plant Coaracy Nunes, located in Amapa State. In many situations the methods of vibration analysis is used to detect the presence of faults in this type of machine, this work will also be used to analyze the current signals to provide similar indications. This work aims to present a methodology for fault diagnosis in electrical machines using the vibration signals and correlation with the analysis of the stator current. Throughout this work presents a review of techniques for monitoring and diagnosis of the condition of electrical machinery, through vibration tests correlated with the characteristics of the stator current. The result of the correlation of vibration measurement with the current measurement is based on a methodology implemented by a system of acquisition and data processing platform developed in LabView. The experimental results were obtained from mechanical defects (unbalance and mechanical defects on the slopes, and internal bearings) induced in an experimental device designed with the intention to represent a generation system. Finally, the vibration and current signals were analyzed and compared to verify that the defects that were detected by the conventional vibration altered the behavior of current signals. The good results of this study demonstrate the feasibility of future studies in this area.
Acesso aberto (Open Access)
Influência da variação da razão de alimentação ar/serragem de um combustor ciclônico na composição dos seus produtos gasosos
(Universidade Federal do Pará, 2008) VASCONCELOS, Adriano Akel; NOGUEIRA, Manoel Fernandes Martins; http://lattes.cnpq.br/2324813094737469
In this work it was made an analysis of the combustion in a cyclonic combustor through experimental measures of the temperature and gases concentration in the internal wall of the combustion chamber. With the objective of finding an appropriate operational parameters for the proposed design, the feeding of air and sawdust of combustor was varied in a poor equivalence ratio (with excess of air) while the experimental data were computed. The data profiles obtained were confronted with the theory of the combustion of solids and with the temperature fields and gases concentration founded by Cunha (2005) numerically in the code Fluent V.6.0. In this comparison it was possible to find good qualitative value among the temperatures measured and the one from calculations, however there were differences in the topic concentration of gases. It was possible also to identify the minimum equivalence rate that the cyclonic combustor had in their gaseous products low pollutant tenors, like CO. Besides, at the end of this work a methodology was proposed to find the appropriate size of a cyclonic combustor in agreement with the strip of sawdust consumption that it wants to incinerate.
Acesso aberto (Open Access)
Metodologia para análise exergética-econômica de plantas a vapor para geração de eletricidade consumindo resíduo de biomassa amazônica
(Universidade Federal do Pará, 2009) MENDES, Manoel do Espírito Santo dos Santos; RENDEIRO, Gonçalo; http://lattes.cnpq.br/3093595858773332; NOGUEIRA, Manoel Fernandes Martins; http://lattes.cnpq.br/2324813094737469
The availability of energy resources price increasing promotes directly impacts the social-economic development. The rise for energy in Brazil, the efficient use of energy as strategic activity for the industrial sector. The energy evaluations employed in this sector aims to optimize the efficiency of its thermal systems. This energy performance assessments is based on the First Law of Thermodynamics and are able to quantify only the loss of energy, different from exergetic evaluation that allowing qualify this energy lost. The exergetic analysis is difficult and time consuming, requiring the development of a protocol to be performed quickly. In this case, the protocol must attend particularitities of the Amazon biomass, as well as it´s environment. This paper proposes and applies a methodology of energy and exergetic analysis as well as exergo-economic analysis a steam power plant installed at Belém, Pa funning on Rankine cycle. After these evaluations, the energy rate and energy losses are gotten, and also exergy rate and it’s rate destruction, the cost rate for each product and the monetary cost of the energy produced by the plant in R$/kWh. Such results, make possible to identify the largest energy losses of the power plant, quantify the cost of destruction of exergy in key equipment and the rate of cost of main products of the plant that are thermal energy and electricity. This allows quantify the energetic, economic and exergetic performance in each of the plant equipment and indicating the processes that deserve a development work to improve their economic efficiency. Moreover, the cost of the energy capacity in R$/kWh produced by power plant steam was compared with the value charged for the local energy utility. This comparison showed that power plant has energy cost less than the utility price.
Acesso aberto (Open Access)
Modelagem hidrodinâmica e estudo morfológico do Lago Água Preta: um dos mananciais da Grande Belém
(Universidade Federal do Pará, 2010) HOLANDA, Patrícia da Silva; BLANCO, Claudio José Cavalcante; http://lattes.cnpq.br/8319326553139808
The natural conditions of water resources can be modified with the unsustainable use of them. For example, in Belém, capital of Pará State, Água Preta Lake has a history of degradation jeopardize the drinking water supply in Belém. Thus, the main contribution of this work is to develop a study on modeling hydrodynamic and morphological study of Água Preta Lake. Such study is carrid out through two data sources. The first is a bathymetric chart to date from 1975. This chart is avaliable in the archives of COSANPA. The second was performed with an ADCP and the dates from 2009. The modeling began with the development of models of terrain elevation to date from 1975 and 2009, also used for the morphological study of the lake. To assemble the hydrodynamic model were needed bathymetrics data, substrates data for the friction model of the underwater relief of the lake to calculate the coefficient of Manning; and boundary conditions. The hydrodynamic simulations, depths and velocities, are performed using the model of Saint-Venant shallow water. The simulated depths were compared to data available in the literature. The simulated depths and velocities and the morphological study were used to analysis water flow pattern and sedimentation trends in the lake.
Acesso aberto (Open Access)
Projeto e construção de câmaras reverberantes em escala reduzida para o estudo das características de perda de transmissão de divisórias confeccionadas a partir de materiais regionais
(Universidade Federal do Pará, 2006-09-05) TOUTONGE, José de Aviz; SOEIRO, Newton Sure; http://lattes.cnpq.br/7303174583088137
To project and build reverberant chambers, in scaled model, for the determination of materials transmission loss used for noise control purposes was the objective of this research. Besides, the research seeks to establish a methodology of analysis and interpretation of the acoustic parameters starting from the theory of scaled models, in such way that one can infer the transmission loss of the studied materials. The necessity of this construction occurs due to the non availability of real scale reverberant chambers (only available in some regions of Brazil), making it difficult and raising the costs of material performance tests in other Brazilian regions. Therefore, reverberant chambers were constructed in a reduced scale of 1:6, in order to allow the transmission loss study of party walls, developed with regional materials, confronting their performances and, simultaneously, their use in academic activities. Despite the fact of the chambers have been constructed in reduced scale, the scale factor (1:6) was not considered, meaning that measurements had been carried through in the real octave bands between 125 Hz and 8 kHz. Party walls had been assayed for the determination of the acoustic parameters, based on ISO 140 and 354. Finally, from experimental results, it was possible to prove the efficiency of materials used in the construction of partitions, which could be used for noise isolation purposes in buildings and industrial enclosures. Apart from the experimental assays, analytical calculations had been fulfilled according to the formulation of Analysis Energy Statistics (SEA) in order to provide evidence and validation of the results.
Acesso aberto (Open Access)
Simulação numérica da gaseificação de biomassa em leito fixo
(Universidade Federal do Pará, 2011) ITAI, Yuu; MALICO, Isabel; BRASIL, Augusto César de Mendonça; http://lattes.cnpq.br/0571960641751286
The objective of this study was to evaluate the potential of açaí seeds rejected after processing in Belém - Pará, in order to be used as a source of biomass for energy production by gasification. Elemental analysis results obtained in LABCAT - UNB on a dry basis were obtained with percentages of Carbon, 46.06% Hydrogen, 6.01%, Oxygen, 43.37% , Nitrogen 4.33%and Sulfur 0.08%. These values and other parameters obtained in an experimental study carried out by the studies of Santos (2011) and Cruz (2010), were used to perform a numerical simulation of the gasification process by means of a zero dimensional FORTRAN code developed specifically for this purpose. Variations of the influence of equivalence ratio and moisture content in the concentrations of CO, H2 and CH4 were compared with experimental results. A transient one-dimensional model developed by Hla (2004) was also analyzed. Using the application of a mechanism of two steps pyrolysis where the primary tar (or oxygenated) are initially formed and then cracked into secondary tar (or oil) and other combustible gases. Thus is revealed the complexity of physical and chemical processes that occur in the reactor by the use of energy and mass balance information and rates of chemical reaction of the recommendations and the physical transport processes. The computer model can predict the profile of the gas composition, temperature, primary and secondary tar along the longitudinal axis of the gasifier. Data results have been obtained from both models and after the phenomena behaviour was analyzed in comparison with the experimental data obtained by Santos (2011).
Acesso aberto (Open Access)
Variáveis térmicas de solidificação, espaçamento dentríticos secundários e resistência à corrosão de ligas hipoeutéticas Al-Ni
(Universidade Federal do Pará, 2008-08-14) COSTA, Giselle Barata; SÁ, Fernando Antonio de; http://lattes.cnpq.br/8275621144223544
In this research is carried out a sequence of experiments with Al-Ni hypoeutectic alloys to analyze the upward vertical directional solidification on transient conditions of heat flow. Experimental approaches were developed to quantitative the thermal variables of solidification, as follow: local time solidification; dislocation rate of liquidus isotherms, tip cooling rates and thermal gradients. This study analyzes the dendrite secondary arms spacing in relation to solidification thermal variables and to alloy composition, beyond link these parameters with corrosion resistance of these alloys. These experimental dendrite parameters, concerning to alloys solidification as Al - 1, 1,4 and 1,8%Ni, couldn’t be compared with the main theoretical model of dendrite growth by others researches, because, to alloy studied there shortage of thermophysic properties, impossible this comparison. The corrosive behavior is analyzed by potentiodynamic polarization technique and cyclic polarization technique lead into 3,5%NaCl solution on room temperature, coarse structure dendritics tend to increase the corrosion rates of Al-Ni hypoeutectic alloys. The experimental results obtained by the corrosion tests were correlated with dendrite microstructure. This way, experimental tendencies of growth dendrite were determined to upward vertical directional solidification.

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