Programa de Pós-Graduação em Engenharia de Recursos Naturais da Amazônia - PRODERNA/ITEC

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/4044

O Programa de Pós-Graduação em Engenharia de Recursos Naturais da Amazônia (PRODERNA) do Instituto de Tecnologia da UFPA (ITEC) da Universidade Federal do Pará (UFPA), em nível de Doutorado, tem como objetivos principais: formar quadros profissionais qualificados na área de Engenharia de Recursos Naturais; incentivar a pesquisa e o aprofundamento dos estudos técnicos e científicos relacionados ao uso e a transformação de recursos naturais; e contribuir para o desenvolvimento científico e tecnológico da região Norte.

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Acesso aberto (Open Access)
Uma abordagem matemática aplicada ao projeto de turbinas hidrocinéticas e eólicas com difusor utilizando a teoria do elemento de pá
(Universidade Federal do Pará, 2019-04-30) VAZ, Déborah Aline Tavares Dias do Rio; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975
It is known surrounding a turbine with diffuser may significantly increase its power. This effect has attained considerable attention as it shows theoretically the possibility of achieving a power coefficient about 2 times greater than an ordinary turbine. However, the effect of the diffuser efficiency has not been implemented into blade element momentum yet, as well as the use of minimum pressure coefficient criterion to avoid cavitation during the optimization of the hydrokinetic chord along the blade. Hence, this work presents a novel approach to design diffuser-augmented hydro turbines considering the diffuser efficiency. Based on the blade element momentum, new expressions for the axial induction factor and thrust are obtained. In addition, both efficiency and load generated on a diffuser are considered to the extension of existing formulation to determine power coefficient in cases where diffuser losses are taken into account through efficiency (ηd) and area ratio (β). To assess the proposed model, a comparative evaluation of two different diffusers (flanged conical diffuser and flanged lens diffuser) is performed. Numerical and theoretical results are compared for a shrouded turbine equipped with 83% efficiency diffuser. The relative difference observed for the maximum power coefficient between the proposed model and an actuator disk model with diffuser is about 5.3%. For the hydro turbine with flanged conical diffuser, the mass flow rate is about 20% higher than for a bare turbine, while for the turbine with flanged lens diffuser the increase is only 2.4%. Also, for the flanged conical diffuser the power is increased by 53%. Furthermore, it is observed that the proposed blade element momentum with diffuser achieved good agreement with the numerical model, providing improved results compared to other models available in the literature. The optimization model of hydrokinetic chord shows relevant results in relation to the prevention of cavitation.
Acesso aberto (Open Access)
Aço inoxidável nanoestruturado produzido via soldagem a arco elétrico.
(Universidade Federal do Pará, 2021-07-08) LOAYZA, Cristhian Ricardo; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
Manufacturing methods of nanostructured stainless-steel composites (NSSC) have not yet been developed with industrial applicability. To overcome this shortage, the possibility of incorporating nanoparticles by electric arc welding was investigated, using a tubular rod filled with nanostructured flux composed of multi-walled carbon nanotubes (MWCNT) and 304L stainless steel particles. This flux was manufactured by two different methods: mechanical alloying (MA) and chemical treatment (CT) with hydrogen peroxide. The second showed more promising results using control of kinetic parameters of time and temperature, obtaining a lower degree of amorphous carbon, impurities, and crystalline defects, increasing their crystallinity and interaction of the nanotubes with the metallic matrix. MWCNT incorporation decreased the grain size by 64% when compared to the stainless-steel coating, possessing an austenitic matrix with carbide precipitation in the interdendritic spaces and grain boundaries. The microhardness increased 45% and the rate of erosion by vibratory cavitation decreased 64%, in relation to the AISI 304L coating. Additionally, XRD analyses showed a reduction of the γ{200} phase and a growth of γ{111} after the cavitation process. The method of manufacture of the nanocomposites proved to be economically viable and with the possibility of immediate application on a large scale.
Acesso aberto (Open Access)
Adsorção de ciprofloxacino e norfloxacino em solução aquosa por carvão ativado produzido a partir da casca do cupuaçu (theobroma grandiflorum)
(Universidade Federal do Pará, 2024-09-19) NASCIMENTO, Rafael Alves do; COSTA, Cristiane Maria Leal; http://lattes.cnpq.br/0581730621014796; FARIA, Lênio José Guerreiro de; http://lattes.cnpq.br/7428609361678173; https://orcid.org/0000-0002-9534-9998
The extensive use of antibiotics has caused several negative consequences for the environment and human health. Fluoroquinolones (FQs), present in the aquatic environment, are of particular concern. This study investigated the removal of ciprofloxacin (CIP) and norfloxacin (NOR) from aqueous solutions using activated carbon derived from cupuaçu bark (CAC), an unconventional and low-cost adsorbent. The CAC was characterized physicochemically and the adsorption experiments followed the Box-Behnken design, evaluating the effects of contact time, adsorbate concentration and adsorbent dosage on the removal and adsorption capacity of CIP and NOR. The optimal conditions of the adsorption process were determined by the desirability function, and under these conditions the kinetic, isothermal and thermodynamic adsorption experiments were carried out. CAC showed a similar yield (50.22%) to other activated carbons with H3PO4, low humidity (4.81%) and ash (4.27%). Acidic functional groups were identified in CAC in greater quantities (3.982 mg Eq/g) than basic ones (0.092 mg Eq/g), and the pHPcz was found to be 3.85. A high surface area was quantified (1335.66 m²/g), with an average pore volume and diameter of 0.753 cm³/g and 2.206 nm, respectively. Due to the zwitterionic characteristics of CIP and NOR, adsorption was more efficient at pH 5.0. In this condition, the CAC assumes a basic character and as the CIP and NOR molecules are predominantly in their cationic forms, the electrostatic interaction is facilitated. The optimal conditions for CIP adsorption were: time of 266.40 min, concentration of 192 mg/L and dosage of 0.57 g/L; for NOR, 273.60 min, 186 mg/L and 0.55 g/L. The pseudo-second order (PSO) model and the external mass transfer resistance (EMTR) model best fitted the experimental data, indicating that external mass diffusion was the controlling step of adsorption. The Langmuir model indicated that adsorption occurred in a monolayer, with CIP adsorption capacities of 6.02 mg/g and NOR of 5.70 mg/g. Thermodynamic analysis revealed that the adsorption of CIP and NOR on CAC predominantly involves physisorption. The suggested mechanism for the adsorption of CIP and NOR on CAC may involve electrostatic forces, π-π interactions and hydrogen bonds. CAC regeneration was more effective with NaOH, but after two cycles of use, the percentage of CIP and NOR removal decreased to less than 50%. Thus, CAC proved to be an effective and low-cost adsorbent for the removal of CIP and NOR, also contributing to the reuse of cupuaçu biomass.
Acesso aberto (Open Access)
Análise da transferência de calor convectiva por transformada integral em canais com paredes onduladas
(Universidade Federal do Pará, 2019-12-13) MIYAGAWA, Helder Kiyoshi; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785; https://orcid.org/0000-0001-9365-7498
The hybrid numerical-analytical approach known as the Generalized Integral Transformation Technique (GITT) is employed in the solution of the Navier-Stokes and energy equations that mathematically model the convective heat transfer in corrugated wall channels. The flow is considered laminar, incompressible, and two-dimensional involving a Newtonian fluid with temperature-independent physical properties, while wall temperatures are kept constant along the length of the channel. The streamfunction formulation is adopted, which eliminates the pressure field and automatically satisfies the continuity equation. Extensive convergence analyses are performed for the streamfunction and temperature fields, as well as for the product of friction factor by the Reynolds number and the local Nusselt number to demonstrate the robustness of the method. Verification of GITT results is also performed by comparing the centerline velocity, product of friction factor by the Reynolds number, average temperature, and local Nusselt number with those results obtained with the commercial COMSOL Multiphysics simulation software showing good agreement. The influence of parameters such as Reynolds number, wavy wall amplitude, number of waves, and phase between wall corrugations on the fields of velocity, temperature, and entropy generation are also analyzed, demonstrating their importance for convective heat transfer intensification and energy optimization.
Acesso aberto (Open Access)
Análise das distorções e tensões residuais em painéis enrijecidos soldados com FCAW robotizado e CW-FCAW
(Universidade Federal do Pará, 2022-04-22) RODRIGUES, Lino Alberto Soares; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
Once the influence of welding imperfections in the form of distortions and residual stresses on the resistance of stiffened panels has been proven, monitoring the levels of these imperfections becomes a safety criterion, in view of the uncertainty of the real resistance losses of the panel, without having to measure the magnitudes of these welding imperfections. Thus, this work deals with the measurement of distortion levels and residual stresses by X-ray diffraction and ultrasonic birefringence in stiffened panels. First, the best of three welding sequences were selected using robotic FCAW welding. Sequence 03 showed distortion levels up to 10 times less and a residual stress level closer to neutrality (±100 MPa) compared to sequences 01 and 02. Then, using sequence 03, panels were welded using the CW-FCAW process with 40% cold wire and welding speeds of 100 m/min and 120 m/min. The results showed that the percentage of cold wire with high welding speeds did not reduce distortions, but influenced the level of residual stresses, leading to stresses closer to the neutral line (±100 MPa) on average.
Acesso aberto (Open Access)
Análise de vibrações mecânicas em estruturas esbeltas e flexíveis, como cordas e vigas, sujeitas à movimentação axial utilizando a técnica da transformada integral generalizada
(Universidade Federal do Pará, 2024-05-28) PORFÍRIO, Rogilson Nazaré da Silva; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785; https://orcid.org/0000-0001-9365-7498
The dynamic analysis of vibrations on flexible structures is of an extreme importance in engineering and its solution represents a significant challenge to be tackled. This study has the objective to investigate thin and flexible structures such as beams and ropes, that oscillate in supports clamped-clamped and clamped-concentrated mass, which determine the boundary conditions of the analysis problem. Using the generalized integral transformation technique (GITT) that converts the partial differential equation (PDE) developed by the Hamiltonian method in an Ordinary Differential Equation (ODE), it optimizes the numerical process andcontrols efficiently the relative error of the calculations. In this study, it was developed and applied an innovative method that treats the boundary conditions without the use of filters to homogenize the equations. The calculations methodology was implemented in Fortran, utilizing a sub-routine DIVPAG of IMSL. As reference, a thorough analysis of convergence and stableness was applied, considering the behavior of four different models of ropes and two models of beams. The validation of methodology was approached comparing functional aspects such as transversal displacement, system velocities, frequencies, and damping, with results obtained by GITT and other studies that applied the same simulation conditions. The results of this study were found to be satisfactory, which highlights the relevancy of application of this vibration analysis method. It was also assessed the application of this method in different vibration configurations in each model, which exemplifies its broad potential in problems involving the structures analyzed. Therefore, this study represents a significant contribution to the advance of knowledge in dynamic modeling of thin and flexible structures and highlights the influence of boundary conditions in vibrational characteristics of these structures.Furthermore, it introduces an innovative methodology for treating boundary conditions without the use of filters, expanding the analysis possibilities in this field of engineering.
Acesso aberto (Open Access)
Análise do escoamento magnetohidrodinâmico micropolar de sangue e da captura magnética de nanopartículas em vasos sanguíneos
(Universidade Federal do Pará, 2025-05-09) PONTES, Fábio de Andrade; MIYAGAWA, Helder Kiyoshi; http://lattes.cnpq.br/5848592858919971; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The aim of this work is to numerically analyze the transient two-dimensional magnetohydrodynamic pulsatile flow of micropolar blood considering the heat, mass and momentum transfers through a blood vessel in the presence of a magnetic field applied in the region of a symmetrical stenosis. The flow is considered laminar and incompressible and the magnetic nanoparticles are injected into the blood vessel and captured by the action of the magnetic field in the stenosis. The Method of Lines (MOL) was applied in the spatial discretization of the radial variable of the original 2D-transient model transforming it into a system of 1D-transient PDEs, which was solved numerically by the NDSolve subroutine of the Mathematica 13.1 software. The results of the converged MOL are verified with the results generated by the NDSolve subroutine applied directly to the original 2D-transient model and both are also compared with an analytical solution obtained for the limiting case, obtaining a good agreement between them. The effects of physical model parameters such as Lewis, Hartmann and Womersley numbers, the nanoparticle death kinetic constant and the mass Biot number are studied. The results show that in stenosis the flow is decelerated due to the magnetic field, as well as the microrotation velocity. The nanoparticle fraction field is also affected by the presence of the magnetic field, with concentration being increased in the stenosis region. The average velocity and microrotation increase in stenosis due to the narrowing of the arterial lumen. The average temperature and volumetric nanoparticles fraction are also elevated in the stenotic region due to the action of the magnetic field.
Acesso aberto (Open Access)
Análise do processo de despolimerização de resíduos de resinas dentárias à base de pmma em diferentes escalas de produção
(Universidade Federal do Pará, 2024-06-26) RIBEIRO, Haroldo Jorge da Silva; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065; BORGES, Luiz Eduardo Pizarro; http://lattes.cnpq.br/8756886156388456; https://orcid.org/0000-0002-2337-4238
In recent years, the increasing use of plastics has brought economic and industrial benefits but has also led to a significant rise in waste, representing a global environmental challenge. In this context, pyrolysis emerges as a promising technology, offering potential solutions to address the growing problem of plastic waste and promote a more sustainable circular economy. This study investigated the thermal decomposition of dental waste based on poly(methyl methacrylate) (PMMA), focusing on the thermodynamic characterization and optimization of pyrolysis processes at different production scales. Thermogravimetric analysis (TG) showed that PMMA waste remains stable up to 200 ºC, with degradation starting as mass loss occurs beyond this temperature. Thermal decomposition was observed to occur in a single stage, with a decomposition peak at 366 ºC, within the range of 327 ºC to 405 ºC, primarily due to radical depolymerization under inert nitrogen and argon atmospheres. Differential Scanning Calorimetry (DSC) analysis revealed an endothermic peak between 370 ºC and 433 ºC, highlighting the complexity of the pyrolysis processes. The energy characterization showed specific values of 423 J/g for total heat, 1748 J/g for gasification heat, and approximately 820 J/g for decomposition heat, indicating discrepancies that require further investigation for a more complete understanding. In studies using semi-batch fixed-bed reactors, a temperature gradient along the bed was observed to have an adverse impact on the liquid yield and MMA concentration, especially in technical and pilot scales, where the gradient was more pronounced due to the thicker bed. Two critical variables were identified: reactor load and power load, both of which decreased as the process scale increased, leading to lower pyrolysis temperatures and negatively affecting MMA production. Additionally, higher temperatures were found at the edges of the fixed bed, which increased gas production and reduced liquid yield. The liquid fraction analysis revealed a predominance of MMA at the beginning of the reaction, with a gradual transition to aromatic hydrocarbons in the final stages, associated with the pyrolysis of residual char, which increased with the scale of production. The results highlight the effectiveness of temperatures below 450 ºC in producing MMA-rich liquid fractions, even under temperature gradient conditions, emphasizing the importance of moderate heating rates for efficient PMMA depolymerization in semi-batch systems. These findings provide valuable insights for reactor design and are essential for the economic evaluation and optimization of PMMA recycling processes through pyrolysis at various production scales.
Acesso aberto (Open Access)
Análise energética, exergética e tecnoeconômica de um sistema de condicionamento de ar baseado na regulação natural da energia solar em condições climáticas da Amazônia
(Universidade Federal do Pará, 2023-09-01) SANTOS, Elson Costa dos; MACÊDO, Wilson Negrão; http://lattes.cnpq.br/3386249951714088
This work investigates the behavior of a photovoltaic air conditioning system, without batteries or connection to the electrical grid, operating according to the natural regulation of solar energy, in climatic conditions in the Amazon, a region with significant energy challenges, where in many locations, children, adolescents, adults and the elderly live without one of the main inputs for the development of productive, educational, leisure and even subsistence activities. The simulation results indicate that a system powered by a 1400 Wp photovoltaic generator can maintain thermal comfort conditions, with temperatures between 20 °C and 26 °C and relative humidity between 40% and 80%, for almost half of the operating time. and without any active control. Exergy analyses reveal variations in efficiency and irreversibility of components throughout the day, with the greatest impact on the photovoltaic system, followed by the compressor, condenser, evaporator, and expansion valve. Furthermore, the economic analysis shows that the implementation of these systems in parallel to systems powered by the conventional electrical grid can reduce grid energy consumption by 60.76%, and is strongly related to the tariff charged by the energy concessionaire. Finally, the research demonstrates the use of photovoltaic air conditioning systems as a sustainable solution for cooling, showing its effectiveness with the natural regulation of solar energy and its economic contribution to reducing the consumption of non-renewable energy
Acesso aberto (Open Access)
Análise quase-estacionária de pequena turbina eólica com pás curvadas
(Universidade Federal do Pará, 2023-10-20) VELOSO, Mauro José Guerreiro; CHAVES NETO, Antônio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975
The installed power generation capacity in renewable energy has stood out in Brazil lately. The Anuário Estatístico Energético Nacional 2023 reported that wind energy improved by 14.3% from 2021 to 2022. Despite the wind energy potential generation in Brazil, there are still obstacles to overcome, including challenges in research and development. So, researchers have conducted investigations on renewable energy, focusing on studying wind turbines' design and performance evaluation and other efforts to alleviate that task. Hence, research has not been conducted on the dynamic starting behavior of small wind turbines with different blade curvatures in wind power systems. In this sense, the main objective of this work is to analyze the influence of different angles of blade curvature on the dynamic response on starting the coupled turbine-generator set. Newton's second law, the blade element theory, and the extension of the Palmgren method are applied to obtain the wind turbine behavior at the start. The dynamic behavior measurements available in the literature at the start of the straight-blade wind turbine is been applied as a reference baseline to validate the methodology. Numerical simulations demonstrate that during start-up, turbines with straight blades and forward-swept blades start in less time, are approximately 19.9% faster at starting, and require 10.7% less wind speed than turbines with backward-swept blades. Compared to straight-blade turbines, backward-swept blade turbines increase the dissipative torque up to 5.86% and the dynamic efforts by 22%. These results indicate the significance of blade geometry on turbine performance and the existence of a swept angle at which the turbine performs better than other angles of the swept blade.
Acesso aberto (Open Access)
Aplicação de destilados provenientes do bio- óleo de pirólise de resíduos de gordura animal no asfalto diluído de petróleo
(Universidade Federal do Pará, 2024-08-12) VALENTE, Alex Lopes; MACHADO, Nélio Teixeira; http://lattes.cnpq.bhttp://lattes.cnpq.br/1500327307736428r/5698208558551065; https://orcid.org/0009-0002-4461-7611; BERNAR, Lucas Pinto
Waste animal fats (WAF) can be converted into distillate fractions similar to petroleum solvents and used as biofuels or in other applications through pyrolysis and fractional distillation. The distillate fractions from the pyrolysis of triglycerides exhibit adequate viscosity and volatility compared to petroleum-derived fuels but show acid values between 60-140 mg KOH/g, preventing their direct use as biofuels without considerable purification of the distilled fractions. Diluted petroleum asphalt (DPA), used for priming soil in the construction of flexible pavement, requires adequate viscosity, volatility, and penetration, and the distillate fractions from WAF pyrolysis oil can be used as partial or full substitutes for the standard solvent (kerosene) in DPA production. The aim of this study was to test the compliance of DPAs prepared by substituting kerosene with bio-oil fractions from WAF according to DPA standards. First, WAF is obtained from meat waste through the rendering process. Then, WAF is subjected to pyrolysis in a semi-batch fixed-bed reactor (2L), and the resulting bio-oil is fractionally distilled into gasoline, kerosene, and diesel fractions. The pyrolysis process is analyzed concerning the type of reactor used, with a focus on the influence of temperature and reaction time, as well as the distillation profile. The distilled fractions are characterized by density, viscosity, and acid value before being used in the preparation of DPAs by partial and/or total (0-40% by weight) substitution of standard kerosene. The mixtures were tested for kinematic and Saybolt-Furol viscosity, flash point, and penetration, according to road pavement standards. The results showed that the kerosene and diesel fractions from WAF can be adequately used in the preparation of DPAs as a total substitute for the petroleum kerosene typically used.
Acesso aberto (Open Access)
Avalanche como rede de percolação não homogênea
(Universidade Federal do Pará, 2019-09-13) SOUZA, Raimundo Nonato Carneiro de; TAVARES, Heliton Ribeiro; http://lattes.cnpq.br/1313373547379006; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
Avalanches can be considered as a percolation process. This hypothesis will be posted to evaluate if this approach is possible and what are its advantages. Some literature speculates that there is the possibility of considering avalanches as a percolation event. However, there is no clear distinction from the percolation model that these events describe, either a homogeneous or non-homogeneous process. This work deals with avalanche simulations as physical cases of percolation. To characterize the avalanches, two percolation models were simulated: homogeneous and heterogeneous. Simulations were developed to compare avalanches in both models. To perform these simulations, the probability of a site being open equal to 0:5 was used. The sizes and transients were measured for each avalanche in the different models. To close the work, experiments were carried out to create avalanches, in order to better calibrate the simulations using real avalanche data. For when comparing the simulated results with existing data in the literature, a typical behavior of a probability function was perceived. Given this behavior one can make predictions about the size of the avalanches. Analyzing the results obtained, it is possible that the behavior of avalanches created with non-homogeneous probability presented well defined characteristics, having larger values of size and transient. It was concluded that the non-homogeneous model has a high stability and is better in the evolution aspect of the avalanche, so with some adjustments the heterogeneous model can approach a real avalanche with greater accuracy.
Acesso aberto (Open Access)
Avaliação de potencial hidrocinético à jusante de centrais hidrelétricas
(Universidade Federal do Pará, 2017-12) HOLANDA, Patrícia da Silva; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662; SECRETAN, Yves; BLANCO, Claudio José Cavalcante; http://lattes.cnpq.br/8319326553139808
The maximization of the performance of hydropower projects by taking advantage of the remaining energy downstream of dams via the installation of hydrokinetic turbines is feasible. In this context, two case studies of the hydroelectric power plants are presented, one of large Tucuruí in the Tocatins river, Amazonia, and another of medium size Bariri in the Tietê river, in the Southeast of Brazil.In central hydrokinetic projects, the design of the rotor diameter and velocity of the water are fundamental and depend on the depth and velocity of the river, respectively. Thus, the Saint-Venant model has been applied to these areas of studies. The calibration of the model was performed by linear regression of the measured and simulated flow rates for both, resulting in a correlation of 0.99. Validation was performed for a point on the Tocantins river using velocities measured with an acoustic Doppler current profiler (ADCP). The measured velocities are comparable to the velocities simulated by the model. Thus, a power curve was generated for the measured flow rates and the simulated velocities for the point at which the velocities were validated, thus obtaining a correlation of 0.96. This same curve was used for estimates of velocity, calculation of the energy density, and defining a design velocity for Tucuruí HPP equal to 2.35 m/s and Bariri 2.25 m/s. After the design was velocity defined, 10 points were selected Tucuruí and 1 point Bariri for the location of hydrokinetic turbines. The velocities of these points were determined with the same method used for the validation of the velocities. The points were selected based on the channel downstream of the reservoir and at the end of the Bariri dissipation basin, with the largest depth and velocity, which are characteristics favorable for greater power generation. Considering the rivers depth and available manufacturing technology, the rotor diameter was defined for the large study in 10 m and for the medium 2.1 m. After the design velocity was defined, the rotor design was implemented using the blade element method (BEM Blade Element Momentum), allowing for the definition of an installed power curve of the turbine as a function of the river velocity. In terms of generated energy, the 10 turbines can generate 2.04 GWh/year. These numbers demonstrate the potential for utilizing the remaining energy of hydroelectric plants.
Acesso aberto (Open Access)
Biocompósito a partir de PLA, Biovidro e Nanotubos de Carbono por Impressão 3D visando Regeneração Óssea
(Universidade Federal do Pará, 2023-03-31) VASCONCELOS, Esleane Vilela; REIS, Marcos Allan Leite; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
Bone involvement promoted by aging and accidents has aroused interest in biomaterials and technologies for bone regeneration purposes. Thus, 3D printing technology gained prominence in the production of scaffolds due to its versatility in the production of complex geometries with interconnected pores. In this work, scaffolds composed of poly (lactic acid) (PLA), bioglass (BV) and carbon nanotubes (NTC) were produced by 3D printing, using hexagonal geometry, similar to honeycomb, interleaved. Poly (lactic acid) is a biopolymer already used in biomaterials, while bioglass has proven to be an excellent strategy for use in bone regeneration due to its excellent properties of biocompatibility, bioactivity and osteointegration, however they have low mechanical resistance and carbon nanotubes have shown excellent mechanical reinforcement in composite biomaterials. Thus, the main objective of this study was to produce and characterize a biocomposite of PLA, bioglass and carbon nanotubes by 3D printing and to study its chemical structure, crystallineity and morphology, using fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction and scanning electron microscope. The thermal stability of the composite was evaluated by thermogravimetry, mechanical properties by compression tests and cell viability was determined by the Alamar Blue test. The bioglass was synthesized by sol-gel method presenting bioactive phases of silicate. The scaffolds were produced by 3D printing with hexagonal structures in honeycomb in PLA, PLA/BV and PLA/NTC that were impregnated with bioglass on its surface. The results of the scaffolds demonstratedinterconnected and well-defined pores, ranging from 130 μm to 800 μm. Raman spectroscopy confirmed the interaction of BV in the polymer matrix through new peaks in the spectrum between 1400 and 2600 cm-1 and the presence of the D, G and 2D bands of NTC. In the compression assay, PLA scaffolds with 2 mm diameter showed higher compression stress of 14.88 ± 2.35 MPa, while PLA/NTC higher modulus of apparent compression, 0.58 ± 0.36 GPa. In cell viability, statistical tests showed that there was no significant difference between scaffolds with 2 and 4 mm diameter. The results reveal promising results for the use of 3D printed composites in bone repair sponges. Thus, we suggest the composite of PLA/NTC of 4mm impregnated with BV on the surface as the best bone substitute, however, the application in implants remains limited in relation to osteogenic integration.
Acesso aberto (Open Access)
Caracterização de material compósito incorporado com fibras de bambu (Bambusa Vulgaris) e resíduos sólidos industriais para utilizacao como componente estrutural para a construcao civil
(Universidade Federal do Pará, 2020-03-12) SANTOS, Alessandro José Gomes dos; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
In the industry, the production of materials that bring less environmental impacts and that have high sustainability has been growing, mainly with regard to vegetable fibers and industrial waste. In this work, full isophthalic unsaturated polyester matrix, composites with bamboo vegetable fiber, composites with industrial residues (red mud, kaolin and copper) and hybrid composites with variation in the proportion of residues and fibers were made. The residues were used with granulometry of 100 MESH and the fibers in the lengths of 15mm and 30 mm, randomly arranged within the matrix. These fibers were used in natura and treated with 5% NaOH during the period of 2 (two) hours. The fibers were characterized in terms of their physical, mechanical and morphological properties. The composites were made by hand (hand lay-up) in the form of rectangular plates in metallic mold and pressed. The proportions of the mass fractions of the residues varied by 10%, 20%, 30% and 40%, whereas the mass fraction of fibers was varied by 1%, 2% and 3%. For the production of hybrid composites, the variation occurred up to the maximum saturation level of the matrix, with the proportion of residues / fibers of 10% / 3%, 20% / 3%, 30% / 3% and 40% / 3%, respectively. Bamboo fibers were chemically characterized by analyzing the levels of extractives, lignin and holocellulose. The residues were characterized mineralogically by means of X-Ray Diffraction (XRD). The composites were characterized physically (apparent porosity, water absorption and apparent specific mass), mechanically (traction, flexion and impact), flame retardancy and morphologically through Scanning Electron Microscopy (SEM) analysis. For physical characterization analyzes, 10 specimens (CP’s) were produced for each series. In the mechanical tests, 10 CP's were manufactured for the tensile tests, while for the flexion and impact tests, there were 8 CP's for each series. This same amount was used for the flame retardancy tests. After the physical tests, a small variation was observed with the addition of fibers and an increase in the Apparent Specific Mass with the addition of residues and fibers in the matrix. In the analysis by means of mechanical traction characterization, the best results of resistance limits in the values of 33.05 MPa were obtained for composites with 3% bamboo fibers treated with 15 mm in length and 33.11 MPa with bamboo fibers 30mm long without treatment. With the incorporation of waste, it reached a value of 40.25 MPa. In hybrid fractions the value reached 41.07 MPa with the addition of 20% kaolin residue / 3% bamboo fibers in the 15mm lengths with treatment. In flexion tests, the results were 150.94 MPa for the addition of treated 30mm fibers, 140.34 MPa for the addition of 20% kaolin residue and in the hybrids of 137.27 MPa for the addition of 30% kaolin residue / 3% bamboo fibers with 30mm treated. In the impact tests, the best results were 23.02 kJ / m² for the addition of 10% copper residue and 38.56 kJ / m² for the addition of 20% copper residue / 3% bamboo fibers with 30 mm long treated.
Acesso aberto (Open Access)
. Caracterização física, aspectos morfológicos, comportamentos térmico e mecânico do pecíolo do miriti como um material potencial para aplicações em pás de turbinas eólicas.
(Universidade Federal do Pará, 2024-10-28) GOMES, Igor dos Santos; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975; WOOD, David Home
In many small wind turbine blades, the internal space between the laminated shells is filled with a core material. In this context, with the aim of enabling the application in both small and large blades, this thesis presents the petiole of the miriti palm (PMP) as a potential material for such applications. PMP is abundant in the Amazon region, and its harvesting does not harm the palm, as the petiole regrows, making the process fully sustainable. This could play an important role in enhancing the sustainability of wind turbine manufacturing. The physical properties, morphological aspects, and thermal and mechanical behaviors of PMP were determined and compared to balsa wood (BW). Additionally, the advantages of using the easily worked petiole for the core in manufacturing were considered, as demonstrated by the construction of a 0.598 m blade and starting performance tests of the turbine in both computational simulations and wind tunnel experiments. The results showed that PMP is about 50% less dense than BW. Consequently, turbine starting simulations indicated that the low density of the small blade made from PMP reduces starting time by 10% compared to EPS and by 42% compared to BW. While PMP and BW have similar morphological aspects as they are natural materials, BW tends to absorb about 3.6% more moisture and around 9% more water than PMP. The thermal behavior of PMP shows stability up to approximately 200°C, making it suitable for most wind turbine manufacturing processes. Regarding mechanical properties such as tensile, compression, bending, and shear strength, both BW and PMP exhibited elastoplastic behavior. Although BW generally possesses higher mechanical properties than PMP, the specific properties of PMP are greater than those of BW, except in cases where the load application does not align with the vascular bundle direction. For instance, the specific elastic strength and specific elastic modulus in tensile with a load applied at 90° in relation to the vascular bundle and in tensile with a load applied at 0° in relation to the vascular bundle of the PMP are approximately 13.5%, 3%, 30% and 61% higher than those of the BW, respectively. PMP’s specific elastic strength in GS compression is approximately 18.5% higher than BW. In shear strength, the specific elastic strength and specific modulus of elasticity of PMP are 20% and 54.5% higher compared to BW. Fatigue results indicate that PMP has a fatigue life of around 106 cycles. Wind tunnel tests showed that, regardless of wind speed, the best results for power coefficient, torque, and thrust were observed in 6-blade configurations, with values of 0.3083, 0.1224, and 2.2993 for λopt equal to 2.519. In analyzing the experimental results for rotation, thrust, torque, and kinetic energy ratio during turbine starting, the periods through which the turbine transitions between transient and steady states were observed, aligning with literature findings. The results presented in this work show that PMP has potential for application in wind turbine blades, as the combination of sustainable materials with significant specific mechanical properties, such as low density, has the potential to improve turbine design, reduce starting time, and extend the high-efficiency operating range.
Acesso aberto (Open Access)
Caracterização morfológica, cristalina e textural de bio-adsorventes produzidos via processamento hidrotérmico de resíduos de palha de milho com H2O sub-crítica: Aplicação na adsorção de ácido acético.
(Universidade Federal do Pará, 2021-12-06) COSTA, Maria Elizabeth Gemaque; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This work aims to investigate the influence of temperature on the textural, morphological and crystalline characterization of bioabsorbents produced by hydrothermal processing of corn husk residues with hot compressed H2O. The experiments were carried out at 175, 200, 225 and 250 ºC, 240 minutes, heating rate of 2.0 ºC/min and biomass/H2O ratio of 1:10, using a pilot scale reactor of 18,927 L. The process is analyzed in terms of yields of reaction products as a function of temperature. The results showed yields of solids ranging from 62.92 to 35.82% (weight), gas yields ranging from 1.49 to 9.59% (weight) and liquid products ranging from 35.43 to 54.59% ( Weight). The yield of the solid phase decreases with temperature, presenting an inflection region between 200 and 225 °C, in which a drastic change occurs, while that of the liquid phase increases, presenting the same inflection region between 200 and 225 °C. The gas phase yield increases exponentially with temperature up to approximately 10% (weight) in the investigated temperature range. Elemental analysis of solid products shows that the carbon content increases, while the oxygen and hydrogen content decreases with temperature. The textural, morphological and crystalline characterization of solid phase products analyzed by TG/TDG, SEM/EDX, XRD and BET. The solid phase product (bio-adsorbent) obtained by hydrothermal processing of corn husk residues at 225 and 250 °C, 240 minutes, and biomass/H2O ratio of 1:10, were chemically activated with 2.0 NaOH solutions. M and 2.0 M HCl to investigate the adsorption of acetic acid solutions (1.0; 2.0; 3.0; and 4.0 mg/mL). The adsorption kinetics investigated at 30, 60, 120, 240, 480 and 960 seconds. The adsorption isotherm showed that chemically activated carbons were able to remove acetic acid from aqueous solutions.
Acesso aberto (Open Access)
Carbonização hidrotérmica dos caroços de açaí (Euterpe oleracea, mart) com H20 quente comprimida
(Universidade Federal do Pará, 2021-08-13) SILVA, Conceição de Maria Sales da; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This work aims to investigate systematically the influence of process temperature, biomass-to-water ratio, and production scales (laboratory and pilot) on the chemical composition of aqueous and gaseous phases and mass production of chemical by hydrothermal processing of Açaí (Euterpe Oleraceae, Mart.) seeds. The hydrothermal carbonization carried out at 175, 200, 225, and 250 °C, 2 °C/min, biomass-to-water ratio of 1:10, and at 250 °C, 2 °C/min, and biomass-to-water ratios of 1:10, 1:15, and 1:20, in technical scale, as well as at 200, 225, and 250 °C, 2 °C/min, biomass-to-water ratio of 1:10, in laboratory scale. The elemental composition (C, H, N, S) of solid phase determined to compute the HHV. The chemical composition of aqueous phase determined by GC and HPLC and the volumetric composition of gaseous phase by using an infrared gas analyzer. For the experiments in pilot scale with constant biomass-to-water ratio of 1:10, the yields of solid, liquid, and gaseous phases varied between 53.39 and 37.01% (wt.), 46.61 and 59.19% (wt.), and 0.00 and 3.80% (wt.), respectively. The yield of solids shows a smooth exponential decay with temperature, while that of liquid and gaseous phases a smooth growth. By varying the biomass-to-water ratios, the yields of solid, liquid, and gaseous reaction products varied between 53.39 and 32.09% (wt.), 46.61 and 67.28% (wt.), and 0.00 and 0.634% (wt.), respectively. The yield of solids decreases exponentially with increasing waterto-biomass ratio and that of liquid phase increases in a sigmoid fashion. For constant biomass-to-water ratio, the concentrations of Furfural and HMF decrease drastically with increasing temperature, reaching a minimum at 250 °C, while that of phenols increases. In addition, the concentrations of CH3COOH and total carboxylic acids increase, reaching a maximum at 250 °C. For constant process temperature, the concentrations of aromatics vary smoothly with the temperature. The concentrations of furfural, HMF, and cathecol decrease with temperature, while that of phenols increases. The concentrations of CH3COOH and total carboxylic acids decrease exponentially with temperature. Finally, for the experiments with varying water-tobiomass ratios, the productions of chemicals (furfural, HMF, phenols, cathecol, and acetic acid) in the aqueous phase is highly dependent on the biomass-to-water ratio. For the experiments in laboratory scale with constant biomass-to-water ratio of 1:10, the yields of solid ranged between 55.9 and 51.1% (wt.), showing not only a linear decay with temperature, but also a lower degradation grade. The chemical composition of main organic compounds (furfural, HMF, phenols, cathecol, and acetic acid) dissolved in the aqueous phase in laboratory scale shows the same behavior of those in obtained in pilot scale.
Acesso aberto (Open Access)
Compósitos híbridos reforçados com tecidos de curauá, carnaúba e aramida com aplicações em blindagem balística
(Universidade Federal do Pará, 2023-01-31) OLIVEIRA FILHO, Edwillson Gonçalves de; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809
The development of effective ballistic armor systems is essential to ensure human and vehicle protection. These shields are usually made up of different materials, such as fiber-reinforced polymeric composites, which are used when a good weight/ballistic protection ratio is desired. In addition, the search for ecologically correct materials, which associate good mechanical performance with sustainability, has been very frequent nowadays. The present work was directed to the study of the mechanical and ballistic properties presented by composites reinforced with lignocellulosic fibers, intended for armoring applications. An investigation was carried out regarding the characteristics of curaua (Ananas erectifolium) and carnauba (Copernicia prunifera) fibers, examining the average diameter, morphological and chemical analyses. The mechanical characterization of the composites was carried out using curaua and carnauba fibers in continuous and aligned distributions through manual production of polyester-fiber composites with 10, 20 and 30%v/v, through tensile, flexural and Charpy impact. From these results, laminated polyester composites were produced for the first time, using hybrid systems with layers of Aramid-Curaua, Aramid-Carnauba and Curaua-Carnauba fabrics, adopting the molding process by cold pressing. All proposed hybrid composites have 30%v/v of fibers and were produced in non-alternating configuration, being submitted to ballistic impact tests considering the level of protection and residual velocity. The ballistic results showed that the Curaua-Carnauba systems were perforated, unlike the Aramid-Curaua and Aramid-Carnauba systems, which were not pierced, which obtained a level I of ballistic protection. In addition, through the residual velocity results, it confirmed the need for fabrics, not blankets, to be used for ballistic applications of these composites. The results are a strong indication of the possible potential of similar hybrid composite solutions.
Acesso aberto (Open Access)
Concentração e bioensaios alelopáticos e antifúngicos de princípios ativos da raiz de timbó via extração com CO2 supercrítico, extração com solventes e adsorção de soluções diluídas em leito fixo.
(Universidade Federal do Pará, 2014-12-18) ALMEIDA, Ossalin; ARAÚJO, Marilena Emmi; MACHADO, Nélio Teixeira