Mestrado em Energia
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- ItemContribuição à rota de produção de combustível em leito fluidizado a partir de resíduo sólido: simulação numérica do reator com misturas de areia e resíduo de embalagem cartonada(Universidade Federal do Espírito Santo, 2025-03-24) Santos, Derikson Elias dos; Ribeiro, Daniel da Cunha; https://orcid.org/0000-0003-3690-1938; http://lattes.cnpq.br/8563308324482367; Bacelos, Marcelo Silveira; https://orcid.org/0000-0002-0838-6839; http://lattes.cnpq.br/3741207242086712; https://orcid.org/0000-0002-3413-0773; http://lattes.cnpq.br/1280040882834837; Faria, Rochkhudson Batista de; https://orcid.org/0000-0003-0264-9148; http://lattes.cnpq.br/4814276846825036; Siqueira, Renato do Nascimento; https://orcid.org/0000-0002-8397-8180; http://lattes.cnpq.br/9791817633014124The pyrolysis of polyethylene/aluminum composite (LDPE/Al) in a fluidized bed produces fuels derived from Tetra Pak waste and recovers aluminum with high purity, thereby reducing the environmental impacts of the extractive industry. However, binary mixtures of sand and polyethylene/aluminum composite can segregate, decreasing the heat transfer rate and leading to bed defluidization. Predicting the mixing index using a 2D-laminar model with the Syamlal drag equation aims to determine operating conditions with low segregation levels, especially during reactor startup. The prediction of the mixing index through a model associated with experimental design has not yet been explored in the literature. For this reason, using a 24 experimental design, this work aims to evaluate the model’s predictive capability, considering the effects of the restitution and specularity coefficients on the mixing index in a fluidized bed. The validated model predicts the effects of the velocity ratio (V/Vmf), diameter ratio (DC/DS), and specularity coefficient (SC) on the bed mixing index, considering a significance level of 10%. For the top region, the results show that lower SC values and higher DC/DS ratios promote particle mixing. The CFD simulation also highlights the impact of the specularity coefficient on the flow regime transition from bubbling to slugging. This research contributes to the design and proper operation of the fluidized bed reactor, strengthening the route for polyolefinic waste valorization toward fuel production and aluminum recovery from Tetra Pak packaging.
- ItemQualidade do serviço de transporte fretado: estudo de caso em uma empresa de petróleo e gás(Universidade Federal do Espírito Santo, 2025-08-28) Giuriatto, Naiara Tomazelli; Souza, Noéle Bissoli Perini de; https://orcid.org/0000-0002-4781-3987; http://lattes.cnpq.br/3709951942118061; Xavier, Thiago Padovani ; https://orcid.org/0000-0001-7148-9921; http://lattes.cnpq.br/8669754182140698; https://orcid.org/ 0009-0000-4518-2280; http://lattes.cnpq.br/0281389636002125; Faria, Rochkhudson Batista de; https://orcid.org/ 0000-0003-0264-9148; http://lattes.cnpq.br/4814276846825036; Coelho Júnior, Thalmo de Paiva ; https://orcid.org/0000-0002-3716-1882; http://lattes.cnpq.br/0305159994373514The growing demand for efficient transportation systems has led companies to consider chartered transport services as a sustainable solution to urban mobility challenges, including traffic congestion, greenhouse gas (GHG) emissions, and employee satisfaction. Despite its benefits, this service is underutilized in Brazil, especially in sectors such as oil and gas, which impact the entire transport services industry. Most studies on transport quality focus exclusively on user perception, neglecting other stakeholders such as drivers, operations staff, and the contracting company. This study evaluates the quality of chartered transport services in a Brazilian company using an adapted SERVQUAL model and data from multiple stakeholders (n=561). The research adopted the model proposed by Souza, Moraes Neto, and Cardoso (2018), which applies a case study approach through structured questionnaires. The analysis used the GAP analysis method and quadrant analysis to assess perceptions and expectations regarding various service attributes. Critical GAPs were identified in areas needing specific improvements, such as seat comfort, noise levels, travel time, and restroom cleanliness. Vehicle identification, on the other hand, was consistently rated positively. The quadrant analysis revealed that most attributes were considered strengths, although communication channels and itinerary flexibility require greater attention. The study highlights the importance of addressing stakeholder-specific GAPs to improve service performance. Regular evaluations and customized strategies are recommended to ensure continuous improvement. This research contributes to the still underexplored field of chartered transport service quality, offering a model applicable to other sectors
- ItemSíntese e otimização de compositos de ferro e bismuto para a fotodegradação de poluentes orgânicos(Universidade Federal do Espírito Santo, 2025-02-25) Costa, Kaio Reis; Proveti, José Rafael Cápua ; https://orcid.org/0000-0002-8809-9791; http://lattes.cnpq.br/2820404320026694; Muniz, Eduardo Perini ; https://orcid.org/0000-0002-0500-4786; http://lattes.cnpq.br/8285018770645807; https://orcid.org/0009-0000-0866-1442; http://lattes.cnpq.br/5804147672203766; Andrade, George Ricardo Santana ; https://orcid.org/0000-0002-1772-9477; http://lattes.cnpq.br/1419428893704446; Ferreira, Nilson dos Santos ; https://orcid.org/0000-0002-8421-2558; http://lattes.cnpq.br/1199350032937783The increasing contamination of water bodies by detergents, with linear sodium alkylbenzene sulfonate (LAS) as the main component, constitutes a major environmental challenge. This research analyzed the synthesis and optimization of iron and bismuth oxides for application in heterogeneous photocatalysis, aiming at the degradation of the detergent, having as a parameter to determine whether the destruction of the detergent molecules occurred the decrease in their absorbance and fluorescence. The composites were synthesized via the sol-gel route using iron nitrate, bismuth nitrate and pectin present in orange peel. The synthesis variables were the calcination temperature (500; 550; 600; 700; 800 °C) and the Bi/Fe molar ratio (0; 0.25; 0.5; 0.75; 1.0; 1.25). X-ray diffraction revealed the formation of a multiphase system with BiFeO₃, Bi₂Fe₄O₉, α-Fe₂O₃ and γ-Fe₂O₃. Presenting up to 88% BiFeO₃ in the bismuth-rich sample and 98% α-Fe₂O₃ in the iron-rich sample. Scanning electron microscopy (SEM) demonstrated the formation of a “flower-like” morphology for samples calcined between 500 and 600 °C. The degradation efficiency via photocatalysis was quantified in a solution of 100 mg/l of liquid detergent, using LEDs from a discarded television and 15 mg of iron-bismuth composite as radiation source. Among all the samples, the one produced with 0.5 mol of iron for 1 mol of bismuth and calcined at 500°C was the one that decreased absorbance the most, by more than 40%, with a reduction of more than 10% in fluorescence
- ItemRota de conversão de resíduos poliolefínicos em combustíveis : simulação e previsão do índice de mistura em reatores de leito de jorro(Universidade Federal do Espírito Santo, 2025-02-24) Louvem, Renata Falqueto; Ribeiro, Daniel da Cunha ; https://orcid.org/0000-0003-3690-1938; http://lattes.cnpq.br/8563308324482367; Bacelos, Marcelo Silveira ; https://orcid.org/0000-0002-0838-6839; http://lattes.cnpq.br/3741207242086712; https://orcid.org/0009-0009-9292-7586; https://orcid.org/0009-0009-9292-7586; Santos, Kassia Graciele dos ; https://orcid.org/0000-0001-7452-6900; http://lattes.cnpq.br/9680475824447820; Siqueira, Renato do Nascimento ; https://orcid.org/0000-0002-8397-8180; http://lattes.cnpq.br/9791817633014124Pyrolysis in spouted bed reactors with mixtures of polyethylene/aluminum composite particles (LDPE/Al) and sand promotes the waste valorization route for fuel production. However, unstable regimes caused by mixtures of particles with different sizes and specific masses can compromise thermal conversion in the reactor. To contribute to the carton waste management route, this work aims to validate gas-solid flow model in beds composed of sand and composite mixtures through experimental data from the literature. The 2D Euler-Euler granular model is tested with particle mixtures at 30% and 50% composite concentrations and diameter ratios of 1.39 and 2.54. The simulation can predict stable conditions and segregation levels of Mantegazini et al. (2021) and is consistent with experimental data on glass spheres reported by San José et al. (1994). The model can determine the mixing index (Im) of the bed in spouting and collapse regimes with an error of less than 10%. The results indicated that decreasing the diameter ratio and composite concentration in the bed promotes more homogeneous mixtures with Im values close to 1. This research contributes to the fuel production route, in addition to enhancing the valorization and management of solid carton-based waste
- ItemSimulação computacional do efeito da turbulência na hidrodinâmica de misturadores estáticos Kenics® aplicados à fotocatálise(Universidade Federal do Espírito Santo, 2024-11-13) Schneider, Bruno de Oliveira; Xavier, Thiago Padovani; https://orcid.org/0000-0001-7148-9921; http://lattes.cnpq.br/8669754182140698; Lira, Taisa Shimosakai de ; https://orcid.org/0000-0002-2690-242X; http://lattes.cnpq.br/8699243861996813; https://orcid.org/0009-0005-2273-2266; http://lattes.cnpq.br/7397231442316912; Bacelos, Marcelo Silveira; https://orcid.org/0000-0002-0838-6839; http://lattes.cnpq.br/3741207242086712; Santos, Kassia Graciele dos ; https://orcid.org/ 0000-0001-7452-6900; http://lattes.cnpq.br/9680475824447820The treatment of industrial effluents can be considered an essential factor for sustainable development. Among the advanced oxidative processes (AOPs) applied, heterogeneous photocatalysis stands out due to the possibility of using solar energy and because it occurs at ambient pressure and temperature. Its large-scale application depends on improving the performance of photocatalytic reactors, with the compound parabolic collector reactor being one of the most promising. In this context, the use of static mixers has emerged as an alternative to improve mixing parameters and increase the rate of pollutant degradation. Although there are studies evaluating the main commercial mixers or geometries developed by the author, there is a lack of analysis of the hydrodynamic effect of using mixers in heterogeneous photocatalysis processes. The aim of this work was to numerically evaluate the effect of static mixers on the hydrodynamics of the photocatalytic process in a compound parabolic trough reactor. To do this, the flow inside the reactor was numerically simulated using Ansys Fluent® software for Reynolds numbers of 4,500 and 30,000. The contour plots and current lines of the normalized axial velocity along the tube and in different sections of the mixer were analyzed. The pressure drop resulting from the use of mixers was also evaluated. The results showed that the static mixer promoted the formation of vortices in different regions of the tube, an increase in the velocity gradient and turbulence in the flow. In addition, the geometry of the mixer favored the direction of the fluid towards the edge of the tube, a region that is most affected by radiation. These phenomena contribute to a better dispersion of the catalyst and the effluent in this region, which favors the heterogeneous photocatalytic reaction. Increasing the Reynolds number from 4500 to 30000 contributed to the formation of well-defined vortices, a reduction of the vortices, a reduction in backflow and an increase in higher velocity zones. Therefore, there was a positive effect on the hydrodynamic performance of the reactor