Mestrado em Engenharia Mecânica
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- ItemUma avaliação experimental da rota de repotenciação baseada em recuperação de calor residual para o condicionamento do ar de combustão em um motor alternativo de grande porte(Universidade Federal do Espírito Santo, 2024-12-16) Fonseca, Francisco Mello; Donatelli, João Luiz Marcon; Cunha, Carla César Martins; Santos, José Joaquim Conceição Soares; https://orcid.org/0000-0003-3695-2014; Venturini, Osvaldo José; Pérez, Silvia Azucena Nebra deInternal combustion engines (ICEs) in thermal power plants located in regions with high temperatures and humidity, as is the case for some plants in Brazil, operate under preventive derating to avoid the occurrence of knocking. On the other hand, these engines reject a significant amount of heat to the atmosphere, primarily through exhaust gases, which can be recovered to produce chilled water for cooling and dehumidifying intake air, aiming to increase power generation. A research and development project was conducted to design and install an experimental thermal system to evaluate performance improvements in a generating unit of a thermal power plant. This experimental thermal system was designed, its equipment acquired, installed, and instrumented for testing purposes. The system is composed of an absorption chiller, which recovers heat from the engine’s exhaust gases, a cooling coil for conditioning the engine’s intake air, and a cooling tower to cool the chiller and assist the engine radiator. The described experimental thermal system was installed and coupled to one of the generating units equipped with a Wärtsilä 20V34SG engine, which generates 8.5 MW of electric power, considering the derating conditions caused by the hot and humid climate at the plant site. Two experimental test campaigns were conducted. This dissertation aims to present and discuss the procedures and results of these tests, demonstrating that during the experiments, the maximum average cylinder pressure – one of the engine’s operational safety limits – was reached when the electric power output was 9.6 MW, representing nearly a 13% increase in power. The installed thermal system achieved a specific investment cost with savings of approximately 28% compared to recent investments in new generating sets, demonstrating the economic feasibility of the project.
- ItemModelagem computacional da formação de torta de filtração em filtros de manga(Universidade Federal do Espírito Santo, 2024-10-25) Zanete, Hóliver Zambon; Rocha, Sandra Mara Santana ; https://orcid.org/0000-0001-8787-7849; http://lattes.cnpq.br/9653853675618723; Siqueira, Renato do Nascimento ; https://orcid.org/; https://orcid.org/0000-0002-8397-8180; http://lattes.cnpq.br/9791817633014124; https://orcid.org/0009-0007-9184-6210; http://lattes.cnpq.br/3841315513918026; Sartim, Rafael ; https://orcid.org/0000-0002-5678-2027; http://lattes.cnpq.br/0380809249444032; Fernandes, Leandro Marochio ; https://orcid.org/0000-0003-4965-7233; http://lattes.cnpq.br/5933630468428555The growing concern about the impacts of atmospheric pollution on the environment has driven the development of efficient technologies for controlling particulate emissions. Among these technologies, bag filters stand out as effective devices for removing particles from gas streams. These filters consist of a set of filter bags, usually made of fabric or felt, that retain solid particles while clean air passes through the filtering medium. As particles deposit on the surface of the filtering medium, they form a layer known as the filtration cake. This cake increases the resistance to airflow, leading to a higher pressure drop in the system. In this context, a detailed understanding of cake formation is essential for the design and optimization of bag filters. In this work, the implementation of a subroutine based on CFD (Computational Fluid Dynamics) was proposed to predict the formation of the filtration cake in bag filters. Darcy’s law was modified to incorporate particle deposition’s effects on the filter media’s surface on its permeability. The developed subroutine was validated against experimental data available in the literature and subsequently applied to a real bag filter. Three different superficial filtration velocities (5, 10, and 15 cm/s) were evaluated. Initially, the simulations were conducted under singlephase flow conditions (without particle injection), allowing for the fluid dynamics analysis at the beginning of the filtration process. Higher filtration velocities resulted in greater pressure drop. Additionally, the effect of the energy equation on the distribution of flow along the filter surface was observed. After the convergence of the single-phase simulations, particles with a diameter of 5,7 µm and a density of 2,79 g/cm3 were injected at a rate of 0,00127 kg/s for 250 seconds. The results indicated that the formation of the cake redistributed the airflow through the bags, promoting uniformity of the flow along the section of the filter element. It was found that the filling of the filtration chamber alters the pressure drop profile at the beginning of filtration and that, after the stabilization of the particle deposition rate, the increase in pressure drop begins to exhibit linear behavior. The identification of preferential zones for cake formation can significantly contribute to the optimization of bag filter designs
- ItemMetamodelagem para análise térmica no torneamento com ferramenta de aço rápido usando redes LSTM(Universidade Federal do Espírito Santo, 2024-12-13) Santos, Hugo dos Anjos; Dutra, Júlio Cesar Sampaio; Silva, Wellington Betencurte da; Macedo, Marcelo Camargo Severo de; Abreu, Luiz Alberto da SilvaThe prediction of temperature distribution during the turning process is essential for optimizing machining operations and extending tool life. This study investigates the application of LSTM neural networks to model the temperature field in turning operations using high-speed steel tools. The research compares numerical simulations conducted with ANSYS® software against simulated data generated by the software, enabling a comprehensive analysis of heat transfer mechanisms. The results reveal that the LSTM neural network is highly effective, achieving low root mean square error (RMSE) values and processing data more efficiently compared to traditional numerical methods. This dissertation proposes a metamodel that maintains prediction accuracy while significantly reducing computational costs compared to conventional simulations. This approach has the potential to enhance thermal monitoring in industrial processes, optimizing production and improving machining quality. Additionally, the study contributes to Sustainable Development Goal (SDG) No. 9 – Industry, Innovation, and Infrastructure – by promoting innovative technologies that strengthen industrial competitiveness and sustainability.
- ItemUma proposta para medição in-line da distribuição do tamanho de gotas em escoamentos de emulsões e seu desempenho(Universidade Federal do Espírito Santo, 2024-12-03) Pimentel, Cláudio Benincá; Loureiro, Bruno Venturini; Ramos, Rogério; https://orcid.org/0000-0003-4493-2435; Siqueira, Renato do Nascimento; Silva, Fabricio Soares daOil production is generally associated with the co-production of water, and its proportion increases as wells mature. Flow disturbances such as bends, valves, and equipment, which are crucial for controlling production in a safe and sustainable manner, increase shear stresses during flow, leading to the formation of stable emulsions due to the breakage of water droplets dispersed in the oil. Stable emulsions are unfavorable for the oil and gas industry as they hinder the phase separation process (oil/gas/water), resulting in higher consumption of chemical inputs and increased maintenance costs. The efficiency of the separation process is associated with the Droplet Size Distribution (DSD). However, most DSD measurement instruments currently operate through sampling, which exposes the emulsion to the risk of altered characteristics during sample handling. In this study, a device is proposed for measuring DSD using in-line optical microscopy, obtaining DSD through a computer vision-based algorithm from micrographs of droplets dispersed in the emulsion. Experimental procedures for commissioning and performance evaluation of the device, comparing it with conventional DSD measurement techniques, are carried out in a laboratory-scale emulsion experimental circuit available at the Center for Studies in Oil&Gas Flow and Measurement- Núcleo de Estudos em Escoamento e Medição de Óleo e Gás (NEMOG/UFES). The results obtained with the device demonstrate its ability to provide accurate in-line DSD information for water-in-oil emulsions, though with a more limited measurement range compared to the laser diffraction technique. The results are assessed using dimensionless numbers such as Reynolds and Weber, allowing for extrapolation across different scales. The developed device stands out for its simplicity, speed of measurement, and capability for in-line monitoring of emulsions.
- ItemSimulação e avaliação termodinâmica de configurações de sistemas de cogeração a vapor para recuperação energética dos gases exaustos dos fornos de uma carboquímica(Universidade Federal do Espírito Santo, 2024-08-30) Quintão, Alexsander Luíz; Faria, Pedro Rosseto de; Santos, José Joaquim Conceição Soares; https://orcid.org/0000-0003-3695-2014; Donatelli, João Luiz Marcon; Silva, Júlio Augusto Mendes daEnergy efficiency plays a crucial role in the transition to more sustainable energy sources and in the decarbonization of industries. Within this context, the recovery of residual energy from processes stands out as a strategy, as is the case of the carbochemical plant, which is the subject of this study, where the calcination furnaces release exhaust gases containing thermal and chemical energy. These gases, originating from six furnaces, have a total flow rate of 1.36 kg/s at 800°C, with a volumetric composition of 26% H2, 4.2% CH4, and 5% CO, among other gases, resulting in a total energy potential of 8.30 MW. of which 1.63 MW is thermal and 6.67 MW is chemical. This study aims to analyze cogeneration system configurations based on steam cycles for this energy recovery, aiming to heat the thermal oil of the process, in addition to generating electricity. To this end, four configurations were simulated based on an example from Norway, using the IPSEpro software, followed by evaluation based on the first and second laws of thermodynamics to assess their performance and identify opportunities for future optimizations. The results indicated that, in addition to providing useful heat of 70 kW for heating the oil, it is possi-ble to obtain an electrical power of up to 2.654 MW. The energy and exergy efficiencies of the steam cycles reach up to 43.35% and 80.45%, respectively, while the system as a whole achieves up to 32.8% and 32.03% energy and exergy efficiencies, respectively. The exergy analysis revealed opportunities to improve various processes, with the greatest exergy des tructions occurring in the combustion chambers and boilers, in addition to the recoverable heat in the exhaust gases from the boilers. Although the environmental assessment was not the main objective of the study, qualitatively, it was observed that there is a drastic reduction in the temperature of the gases currently released into the atmosphere, as well as the combustion of combustible elements present, mainly methane, drastically reducing thermal and chemical pollution. Furthermore, quantitatively, by generating electricity and thus reducing the demand on the power grid, more than 3,234 tons/year of CO₂ emissions can be avoided. These indicators, as well as the thermodynamic evaluation of these four simulated configurations, demonstrate the significant theoretical potential for recovering this residual energy, which brings substantial benefits in terms of both effici-ency and reduction of environmental impacts. This potential also suggests the need for further studies for other assessments, particularly regarding economic viability, especially if the project is to be enabled for integration into a carbon market.