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This work performed a three-dimensional numerical study to describe the hydrodynamics of upflow anaerobic sludge blanket reactor treating domestic wastewater. The simulations were made in the commercial software Ansys CFX&reg, Different inclinations of the gas deflector were considered, to assess its influence on the velocity field inside the reactor. In order to validate the numerical study, we used experimental data regarding the inflow, the inlet and outlet concentrations of the organic matter, the concentration of solids at the liquid-gas interface and at the reactor outlet, and the pressure field inside it. The comparison between the numerical and experimental results demonstrated small differences. The mathematical model used to describe the hydrodynamics flow in the UASB reactor was quite satisfactory since it adequately has reproduced the physical behavior inside the reactor.

A fabricação dos materiais cerâmicos, como atividade industrial, se deu em função do crescimento das grandes construções civis. A manufatura desses materiais compreende as etapas de extração, beneficiamento, homogeneização, conformação, secagem e queima. A secagem é um processo termodinâmico que antecede a queima, na qual, em função do fornecimento de energia térmica, ocorre a evaporação da água que foi adicionada ao sólido durante a sua conformação. É um processo que envolve fenômenos complexos de transferência de calor e massa e, por isso requer a geração de modelos matemáticos que descrevam o processo com grande realismo físico. A existência dos modelos matemáticos se dá, sobretudo, com o intuito de descrever determinados fenômenos, buscando entender e solucionar irregularidades existentes durante o processo. A estimação de parâmetros é uma técnica que possibilita a obtenção das variáveis de controle de processo e a descrição do fenômeno de secagem com precisão. Neste contexto, o presente estudo teve como objetivo, através da modelagem matemática e simulação numérica, analisar o comportamento térmico e gravimétrico de tijolos cerâmicos industriais durante o processo de secagem e estimar os parâmetros de processo. Para isso, modelos matemáticos baseados no método de análise concentrada foram propostos e ajustados aos dados experimentais obtidos na literatura, via software Statistica®. Resultados referentes ao comportamento dos tijolos cerâmicos durante o processo de secagem, foram expostos e analisados. Foi possível concluir que o modelo matemático proposto ajustou-se adequadamente aos dados experimentais coletados, com coeficiente de determinação superior à 0.9 e que, através da estimação de parâmetros, foi possível definir as variáveis de controle do processo, e obter os coeficientes convectivos de transferência de calor e massa.

A deposição de cristais estáveis de parafina nas paredes das linhas de produção, é um problema atual na indústria do petróleo. Isto impulsiona pesquisas em dutos e equipamentos, que buscam ampliar o entendimento sobre esse fenômeno e desenvolver atividades de manutenção preventiva, com maior eficiência. Este trabalho apresenta um estudo teórico do transporte de óleo parafínico em um duto horizontal de seção circular. Para descrição do fenômeno, em um sistema bidimensional, utilizou-se um modelo matemático que considera a difusão molecular como mecanismo dominante na deposição da parafina. O escoamento do óleo em regime laminar, completamente desenvolvido, é analisado a partir da consideração de que, para temperaturas superiores a temperatura de início de aparecimento dos cristais (TIAC), o petróleo (solvente) e a parafina (soluto) formam uma mistura binária e homogênea. As equações que descrevem o problema são formuladas e resolvidas, numericamente. Resultados de espessura da camada de parafina, distribuição de temperatura e pressão do óleo, ao longo do duto, no decorrer do tempo, são apresentados e analisados para diferentes condições de operação, descritas pelos valores iniciais dos números de Reynolds (Rec), Peclet (Pec) e coeficiente de solubilidade adimensional (S*). Verificou-se que a variação do Rec, em regime laminar, é irrelevante para o comportamento da camada de parafina depositada. Uma redução no Pec, promove a concentração da deposição em uma pequena região do duto, o que se evidencia em quedas bruscas na pressão do óleo, no decorrer do tempo. O parâmetro S* mostrou estar diretamente ligado a um maior alcance da espessura do depósito, em relação ao raio do tubo, sendo o mesmo, função do gradiente de temperatura entre o óleo e o ambiente externo e de propriedades físicas do depósito formado.

This project proposes the numerical reproduction development of the water flow in a shell-and-tube heat exchanger 2:1 according to the CLASS C TEMA standard (for moderate operation conditions, with commercial application). With baffles in aluminum and copper tube for the cold fluid flow, the shell is in acrylic, and with thermal analysis efficiencies with regard to the presence or not of the baffles, that is to analyze the efficiency with only, the tubes and the shell and soon after the analysis with tubes and baffles. Heat exchangers are widely used equipment on an industrial and commercial scale, the application of these equipments on an industrial scale represents innovative processing solutions reflecting the processes efficiency, producing significant savings and lower cost, supporting the business success, and consequently offering opportunities, social responsibility, which are the pillars of sustainability. For the development of this work the methodology was used to calculate effectiveness, following the design parameters and contour conditions, it was analyzed the fluids behavior in the shell and the tube, through computational fluid dynamics (CFD) using the software ANSYS CFX 15.0. The results were compared with Excel generated worksheets calculated using the existing equations and correlations.

In the present work, it was developed a numerical study on separation processes using ceramic membranes. The study apparatus consisted of a separation module formed by four concentric tubes, where the most inner one corresponds to the ceramic membrane. The system was applied to the treatment of oil and water mixtures. The separation module had a tangential effluent input and a tangential concentrate output. The filtered fluid was collected inside the membrane after filtration. The numerical study used a 3-D computational domain, and it was executed by means of the commercial software ANSYS CFX 12. In the numerical test, the porosity of the membrane was considered as a constant and the permeability as a function of the resistance of the porous media to the flow. At last, it were presented and analyzed the results for pressure, velocity, oil concentration distribution inside the device, permeation velocity, and pressure profiles at the surface of the membrane. The numerical results obtained indicate that the mathematical model used was capable of predicting the deposition of the oil at the surface of the tubular membrane. A geometric analysis of the separation module, supported by the system operation conditions, showed an important influence of this parameter on the dispersion of the concentration polarization at the surface of the equipment. The results showed that the geometric aspects of the proposed microfiltration module and the membrane distribution within the separation module had a significant influence on the hydrodynamic flow leading to polarized layer dispersion.

This work aims to numerically study the moisture absorption in polymer composites reinforced with vegetal fiber, using the diffusive model of Langmuir, which considers the existence of water molecules inside the material free to diffuse and adsorb at the capillaries walls, in the solid. A three-dimensional and transient mathematical modelling to describe the water absorption process by the composite and its numerical solution via finite volume method are presented and discussed. Results of the free solute concentration, entrapped solute concentration, local moisture content and average moisture content obtained at different instants of the process are presented and analyzed. It was verified that the concentration gradients of the molecules (free and entrapped) are higher at the material surface. In addition, as the concentration of free water increases, there is also an increase in entrapped water concentration within the material at any time of the process.

This work aims to study numerically the moisture absorption in polymer composite reinforced with vegetable fibers using the Langmuir model which considers the existence of free and entrapped water molecules inside the material. A three-dimensional and transient modeling for describing the water absorption process inside the composite and its numerical solution via finite volume method were presented and discussed. Application has been made for polymer composites reinforced with sisal fiber. Emphasis was given to the effect of the layer thickness of fluid close to the wall of the composite in the progress of water migration. Results of the free and entrapped solute (water) concentration, local moisture content and average moisture content, at different times of process, and inside the composite were presented and analyzed. It was verified that concentration gradients of the molecules (free and entrapped) are higher in the material surface, at any time of the process, and concentration of free solute is greater than the concentration of entrapped solute. It was verified that the water layer thickness surrounding the composite strongly affects the moisture absorption rate.

The drying process is a step of ceramic brick production which requires the control of process variables to provide a final product with a porous uniform structure, reducing superficial and volumetric defects and production costs. Computational fluid dynamics (CFD) is an important tool in this process control, predicting the drying physical phenomenon and providing data that improve the industrial efficiency production. Furthermore, research involving CFD brick drying has neglected the effects of oven parameters, limiting the analysis only to the bricks. In this sense, the aim of this work is to numerically study the hot air-drying process of an industrial hollow ceramic brick in an oven at 70 &deg, C. The results of the water mass and temperature distributions inside the brick, as well as moisture, temperature, velocity and pressure fields of the oven drying air at different process times are shown, analyzed and compared with experimental data, presenting a good agreement.

In this chapter, based on the rigorous theory of fluid flow through porous media and the computational fluid dynamic technique, different numerical approaches for description of air and resin flow in fibrous media will be presented. In the analyses, both fibrous media and fluids (resin and air) are considered to be incompressible. Different 2D and 3D simulations by using CFD are presented and the predicted results of the flow front position are analyzed and compared with experimental data.

This chapter provides experimental information concerned with fluid flow in unsaturated porous media, with particular reference to resin transfer molding. Herein, two important topics will be presented: the rectilinear and radial infiltration processes. Results of the flow front position and injection pressure, with or without fillers, in different instants of infiltration process are shown and analyzed. The study is essential to evaluate the mechanical performance of fiber-reinforced polymer composites and to validate new and advanced mathematical modeling related to fluid flow in porous media.

This chapter, based on the rigorous theory of fluid flow through porous media (continuum theory), different approaches (analytical) for description of air and resin flow in fibrous media will be presented. In the macroscopic mathematical modeling, both fibrous media and fluids (resin and air) are considered to be incompressible and the effect of resin sorption by fibers has been considered. Herein, by using a relevant and advanced mathematical treatment, different effects of the process parameters (injection pressure, fluid viscosity, porous media permeability, and porosity) and mold geometry in the fluid infiltration process has been analyzed.

This chapter focuses on the liquid composite molding technique with special attention to resin transfer molding process (RTM). Herein, the main issues related to this manufacturing technique such as foundations, processing stages, main control variables, problems and advantages associated with the use of the RTM technique, and finally applications of fiber-reinforced polymer composite at different areas are presented and discussed.

Neste estudo estimou-se a variacao da umidade de solidos elipsoidais prolatos durante o processo de secagem continua e intermitente com uma pausa. Para tanto foi proposto um modelo matematico que considera a equacao de difusao bidimensional em coordenadas cilindricas com propriedades termo fisicas constantes. O modelo foi resolvido atraves do metodo integral baseado em Galerkin. Foi desenvolvido um codigo computacional na plataforma Mathematica para implementacao do metodo e realizacao das simulacoes. Para as condicoes investigadas neste trabalho, verificou-se que a secagem intermitente reduz o tempo de processo quando comparada com a secagem continua, e consequentemente, reduz o consumo de energia.

Possuindo produtos com um custo de produção relativamente baixo, a indústria cerâmica é um segmento com participação fundamental na economia nacional. Todavia, trata-se de indústrias que, em sua maioria possuem processos de fabricação ultrapassados, sem controle de qualidade adequado, e que geram um elevado desperdício de recursos e baixa qualidade da peça final. Sendo uma das etapas do processo de fabricação de um material cerâmico, a secagem é definida como o processo de redução do teor de umidade de um sólido em função do fornecimento de energia ao mesmo. Trata-se de um processo que envolve fenômenos complexos de transferência de calor e massa, assim como variações dimensionais, e que, quando realizado de forma incorreta, acarreta danos estruturais ao produto, os quais são os principais responsáveis pelo descarte de peças na indústria cerâmica. Logo, é de suma importância descrever detalhadamente o processo de secagem, fornecendo informações necessárias para que o processo ocorra de forma adequada. Destarte, a presente pesquisa teve como objetivo, através da modelagem matemática e simulação numérica, analisar a variação dimensional de um bloco cerâmico estrutural durante o processo de secagem, onde modelos matemáticos para volume e área superficial do produto foram ajustados via software Statistica® aos dados experimentais obtidos na literatura, em diversas condições experimentais. Resultados referentes às variações das áreas superficiais externa e interna e volume foram expostos e analisados. Pode-se concluir que o modelo matemático escolhido ajustou-se adequadamente aos dados experimentais coletados, com coeficiente de determinação superior à 0.9; e que, apesar de sofrer reduções dimensionais, o bloco cerâmico estudado manteve sua geometria inicial sem apresentar deformações.

This article aims to study the non-Fickian water absorption process in vegetable fiber-reinforced polymer composite using the Langmuir-type model, evaluating the influence of mass diffusivity on the process. The numerical solutions of the governing equations were obtained using the finite-volume method. Transient results of the local and average moisture content, free and entrapped water molecules concentration considering the constant diffusivity and as a function of the average and local moisture content were presented and analyzed. It was observed that the mass diffusivity effectively influences the water absorption behavior, especially in the initial time of the process, where higher differences in the water migration rates into the material are found. The largest free and entrapped water molecule concentration gradients were found close to the composite surface, especially when considering constant mass diffusivity.

O objetivo deste trabalho foi estudar a transferência de calor em um reator cilíndrico elíptico de leito recheado de partículas. Foi desenvolvido um modelo matemático heterogêneo (modelo de duas fases), aplicado para as fases sólida e fluida separadamente. Para resolver as equações diferenciais parciais foi utilizado o método de volume finito, a formulação totalmente implícita, e o esquema WUDS para interpolação para os termos convectivos e difusivos. Resultados da distribuição de temperatura nas fases fluida e sólida, ao longo do reator, para partículas com forma esferoidal prolata e esférica são apresentados e analisados. Verificou-se que a forma da partícula que compõe o leito poroso afeta levemente a distribuição de temperatura no interior do reator e que a temperatura adimensional da fase fluida é levemente menor que a da fase sólida.

Hidrociclones são equipamentos usados em processos de separação óleo-água. São considerados eficientes, compactos, seguros, de simples construção e manutenção, e baixo custo, quando comparados a outros equipamentos de semelhante aplicação. Diante disso, este trabalho tem como objetivo analisar numericamente o processo de separação da mistura óleo-água em um hidrociclone, quanto ao seu aspecto fluidodinâmico. Para a solução numérica das equações governantes utilizou-se o software Ansys CFX. Resultados dos campos de pressão e fração volumétrica da fase óleo, e do desempenho de separação do equipamento são apresentados e analisados. Dos resultados obtidos verificou-se que as maiores pressões ocorrem próximo as paredes e entrada do equipamento, que as maiores frações volumétricas do óleo ocorrem na região central e próximo a saída do hidrociclone, e que este equipamento apresentou uma eficiência de separação superior a 99,8%.

One approach to improve sustainable agro-industrial fruit production is to add value to the waste generated in pulp extraction. The processing of cumbeba (Tacinga inamoena) fruits generates a significant amount of waste, which is discarded without further application but can be a source of bioactive compounds, among other nutrients. Among the simplest and most inexpensive forms of processing, convective drying appears as the first option for the commercial utilization of fruit derivatives, but it is essential to understand the properties of mass transfer for the appropriate choice of drying conditions. In this study, cumbeba waste was dried at four temperatures (50, 60, 70 and 80 &deg, C). Three diffusion models were fitted to the experimental data of the different drying conditions. Two boundary conditions on the sample surface were considered: equilibrium condition and convective condition. The simulations were performed simultaneously with the estimation of effective mass diffusivity coefficients (Def) and convective mass transfer coefficients (h). The validation of the models was verified by the agreement between the theoretical prediction (simulation) and the experimental results. The results showed that, for the best model, the effective mass diffusivities were 2.9285 &times, 10&minus, 9, 4.1695 &times, 9, 8.1395 &times, 9 and 1.2754 &times, 8 m2/s, while the convective mass transfer coefficients were 6.4362 &times, 7, 8.7273 &times, 7, 8.9445 &times, 7 and 1.0912 &times, 6 m/s. The coefficients of determination were greater than 0.995 and the chi-squares were lower than 2.2826 &times, 2 for all simulations of the experiments.

A secagem é uma operação de transferência de calor e massa envolvendo a remoção de umidade, sendo uma etapa importante e de elevado custo no processo de manufatura de diversos produtos. Para materiais cerâmicos, o processo de secagem é necessário para retirar a água que foi adicionada a argila na etapa de moldagem e conferir a resistência necessária para reduzir as chances de falhas durante a etapa de queima do produto. O controle do processo de secagem é essencial para reduzir defeitos no material, perda de produtividade e consumo energético. Devido à importância, esse trabalho tem por objetivo apresentar uma revisão de diversos tópicos relacionados com a secagem de materiais cerâmicos. Aqui são discutidos diferentes aspectos tais como: os fundamentos, as cinéticas de remoção de umidade, os defeitos, o controle e a otimização do processo de secagem, com ênfase a produtos de argila. A ideia é fornecer subsídios para que pesquisadores e industriais possam melhorar seus conhecimentos e tomar decisões apropriadas sobre este tópico de grande importância para a economia do país.

Oil spill at sea by pipeline cracks can cause environmental damage. Knowledge of interfacial phenomena of immiscible liquids helps to study the dispersion of pollutants in oceans, favoring thus flow behavior of the forecast in the vicinity of the leak in submerged pipelines. This study aims to numerically study the leakage of behavior in a submerged pipeline carrying oil. It adopted a two-dimensional model based on mass conservation equations, linear momentum and the model k-ε standard turbulence. We used the Ansys CFX for meshing with 40,510 hexahedral elements. The results of pressure fields and volumetric fraction of oil are analyzed and discussed.

The oil industry has sought to minimize the environmental impact from mining activities and oil transportation. Oil transportation by pipelines is subject to failures and leaks which cause financial losses and environmental damage, often irreparable. Currently, the study of leaks in pipelines has attracted the attention of many researchers. The aim of this study is to evaluate the influence of the curved curvature radius connection in pipeline leakage. We used a mathematical model of multiphase flow to describe the two-phase flow, based on the particle model. Oil is the continuous phase while water a dispersed phase. To model this effect we used the turbulence model SST. All simulations were carried out using the Ansys CFX ® commercial code. Results of the total pressure and pressure drop are presented and discussed. The results confirm the influence of the bending radius of curved connection on the behavior of the total pressure and the total pressure drop in two-phase flow in pipelines with and without leakage.

Oil transport is used mainly by pipeline networks to transport oil from refineries and distributions points to the consumers. This is the main way to transport oils especially in areas of difficult access, ensuring efficiency, lowest cost and safety. In the chemical and petroleum industry it is possible to observe the presence of leak in the pipes, which has stimulated the development of reliable techniques for the rapid and accurate detection of leaks along the pipe in order to eliminate or minimize loss and environmental damage. In this context, this study aims to evaluate the effect of the numerical presence of leakage of two-phase flow (oil-water) pipe connections using the commercial software ANSYS CFX. The results from the fields of pressure, velocity and volume fraction are presented and assessed for illustrating the effect of the presence of the leak in the dynamic flow in the pipe with a curved connection.

The growing global demand for energy has led researchers to seek the improvement of technology in order to maximize the generation of electricity by different ways. Among the different methods of production is the energy produced by thermal power plants, which account for more than 60% of the energy produced in the world. This energy is generated through combustion of fuels such as coal, diesel oil, natural gas and others. The main problem caused by the production of thermal energy is the emission of gaseous pollutants into the atmosphere, such as carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and also particulate matter which causes environmental problems such as acid rain, greenhouse effect, and health problems, especially respiratory diseases. Computational fluid dynamics (CFD) is presented as an important tool in solving problems involving the dispersion of chemicals into the atmosphere. In this sense, this study aims to evaluate the thermofluid dynamics of pollutants’ dispersion emitted from the chimney of a thermal power plant, based on numerical simulations using the Ansys CFX 12.0 commercial code. Fields of velocity and mass concentration of the component involved in the process are presented and analyzed.

The growing demand for oil brings the need for discovery of deeper reservoirs, especially of ultra-deepwater reservoirs. Thus, production in marine systems using components such as risers (flexible or rigid pipes) has been the focus of many studies in different areas. These ducts are used in the transportation of multiphase fluids (oil, water and gas) produced from the oil well located on the seabed to the platform surface. Due to the extreme conditions present in the offshore fields of production, the equipments that transport produced fluids operate close to their limits. So eventually, the flexible pipes may have structural integrity faults like leaks, which can cause production losses, accidents with victims and environmental disasters. The leak depends of a number of properties or parameters measured at the site of the leak, for example, integrity of the pipe material, release of fluids and noise emission characteristics or manifestation of some other type of signal behavior, variation of pressure drops close to the leak, among others. There are a variety of techniques available for detecting leaks, among which there is the mathematical modeling approach using computational techniques. In this context, this paper aims to study the fluid dynamics of a transient multiphase flow in a catenary riser in the presence of leakage. Herein a 3D Eulerian-Eulerian model was applied, including the turbulent model (RNG k-ε), using the commercial package ANSYS CFX® 15 to perform all simulations. The numerical results of velocity, volume fraction and pressure of the involved phases are presented and discussed.

The onshore and offshore production of oil and natural gas is characterized by the multiphase flow in ducts and pipes, which are interconnected by various equipments such as wellhead, pumps, compressors, processing platforms, among others. The transport of oil and oil products is essential to the viability of the sector, but is susceptible to failures, that can cause great environmental damage. Considering this necessity of the transportation sector of oil and derivatives, leakage in pipelines with curved connections, are the object of study for various researchers. In this sense, this work contributes to the study of three-phase flow (oil-water-gas) in a curved pipe (90°) using Computational Fluid Dynamics. The physical domain is constituted by two tubes of 4 meters trenched by a 90° curve, with the poring whole in the curvated accessory. The mathematical model is based on a particle model, where the oil is considered as a continuous phase and the water and gas as a particulate phase. The SST (Shear Stress Transport) turbulence model was adopted. All simulations were carried out using the Ansys CFX® 12.1 commercial code. Results of the pressure, velocity and volumetric fraction of the phases are presented and discussed.

Bananas frescas são frutas com elevado teor de umidade após a colheita, e são submetidas ao processo de secagem para minimizar desperdício e a deterioração, e aumentar a vida de prateleira. Este trabalho apresenta um estudo de secagem de banana em estufa. As bananas inteiras foram descascadas manualmente e secas nas temperaturas de 50 e 60ºC. Modelos concentrados de transferência de calor e massa e variações do volume da banana foram propostos e ajustados aos dados experimentais apresentando uma boa concordância. Os resultados revelaram que a temperatura do ar de secagem e a relação área/volume afetam significativamente a secagem, aquecimento e encolhimento da banana.

A necessidade de investimento na melhoria de qualidade, produtividade, redução de custos e economia de energia de processo é uma preocupação crescente do setor ceramista. O processo de secagem consiste na remoção de umidade de um material através do aquecimento, envolvendo alto consumo de energia. Neste sentido, este trabalho tem como objetivo estudar teoricamente a secagem de sólidos cerâmicos vazados e com forma arbitrária utilizando uma modelagem matemática fenomenológica baseando-se no método da capacitância global. Resultados cinéticos de perda de massa e aquecimento do sólido vazado em diferentes condições operacionais são apresentados e analisados. Observou-se que a perda de umidade ocorre numa menor velocidade que o aquecimento do material, que o formato do sólido e sua relação área/volume afetam fortemente os fenômenos de transporte de calor e massa e que, dependendo da severidade, pode ocasionar danos na estrutura como deformações, trincas, empenamentos e perda do produto.

Este trabalho apresenta um estudo teórico da transferência de calor e massa durante a secagem de tijolos cerâmicos industriais em estufa. Foram propostos modelos matemáticos para descrever as cinéticas de secagem e aquecimento do tijolo em função do tempo de processo, considerando a existência das áreas superficiais interna e a externa e variações dimensionais do tijolo. Foram propostos modelos empíricos para predizer o comportamento do teor de umidade, temperatura superficial, volume e áreas superficiais interna e externa do produto. O estudo foi conduzido em diferentes condições operacionais do ar de secagem (50 a 100°C). Toda a modelagem foi ajustada a dados experimentais do teor de umidade médio, temperatura na superfície e dimensões médias do tijolo durante a secagem, em cada condição experimental, obtendo-se um bom ajuste e elevado coeficiente de determinação, evidenciando sua confiabilidade para ser usada na predição do problema físico. Da comparação, estimou-se o volume, as áreas superficiais interna e externa e os parâmetros de transferência de calor e de massa do tijolo.

O ensino da matemática na educação fundamental é um desafio para docentes e pesquisadores. Para superar essas barreiras técnicas metodológicas o lúdico tem sido utilizado. O lúdico está associado a dança, a música e ao jogar, consiste em um mecanismo poderoso para aumentar o interesse dos alunos por alguma disciplina ou conteúdo. Essa metodologia torna o aprendizado mais divertido e interessante, possibilitando o ensino do conteúdo de uma maneira leve. Devido a sua importância, este trabalho tem como objetivo utilizar o lúdico como ferramenta no auxílio do ensino de frações. A pesquisa foi realizada em uma Escola Municipal, com 30 alunos da turma do 6º ano, sendo 13 do sexo masculino e 17 do sexo feminino. Foi feito uma análise da temática, através de um questionário, a aplicação do jogo e uma avaliação no final das atividades. Verificou-se que, com a inserção dos jogos nas aulas, elas se tornaram mais dinâmica e prazerosa, promovendo uma maior interação entre os alunos/material-manipulável/professor, que contribuiu para uma melhora na aprendizagem do conteúdo de frações.

Fibras de sisal tem despertado o interesse da academia e indústria, devido as suas excelentes características para uso em diversas aplicações. Essas fibras, ao serem extraídas da planta, estão úmidas e, são submetidas a secagem para redução do teor de umidade. O controle do processo de secagem é de grande importância para garantir a qualidade das fibras em termos de resistência mecânica e coloração. Nesse sentido, este trabalho tem como objetivo estudar teoricamente a secagem de fibras de sisal em estufa com circulação forçada de ar. Foram propostos modelos matemáticos para predizer o comportamento transiente do teor de umidade médio e temperatura superficial, e do teor de umidade de equilíbrio das fibras, em função da temperatura do ar de secagem e concentração de vapor de água no leito de fibras. Resultados preditos das cinéticas de secagem e aquecimento, e do teor de umidade de equilíbrio higroscópico das fibras são apresentados e comparados com os dados experimentais, em diferentes condições operacionais. Verificou-se que um bom ajuste foi obtido, com coeficiente de correlação maior que 0,99, para todos os modelos analisados.

The purpose of this article was to theoretically study the non-Fickian moisture absorption process in vegetable-fiber-reinforced polymer composites using a Langmuir-type model. Here, the focus was on evaluating the effect of the water layer thickness that surrounds the composite during the water migration process. The solutions of the governing equations were obtained using the finite volume method, considering constant thermophysical properties and non-deformable material. The results for the local and average moisture content and concentration, gradient values, and the transient rates of the free and bound (water) molecules in the process were presented and analyzed. It was observed that the water layer thickness strongly influenced the water absorption kinetics, the moisture content gradient values, and the equilibrium moisture content inside the material. It is envisaged that this new approach will contribute to better interpretation of experimental data and a better understanding of the physical phenomenon of water absorption, which directly affects the properties of composite materials.

Nos últimos anos, com a crescente conscientização de preservação do meio ambiente, e controle de poluição, o interesse pelo uso de fibras naturais tem aumentado significativamente. No entanto, fibras vegetais são altamente higroscópica e o seu uso, quando úmida, afeta fortemente as propriedades desses materiais. Buscando melhoria para o processo de secagem de fibras vegetais, este trabalho apresenta um estudo experimental da secagem de corpos fibrosos com particular referência a fibras de sisal variedade Agave sisalana. Foram realizados experimentos de secagem de fibras de sisal com teor de umidade médio de 11,19% (base seca). As fibras foram submetidas à secagem em estufa com circulação forçada de ar nas temperaturas de 50, 60, 70, 80 e 90°C. Resultados experimentais das cinéticas de secagem e aquecimento das fibras foram apresentados e analisados. Verificou-se que as curvas de perda de umidade e temperatura das fibras de sisal foram influenciadas pela temperatura do ar de secagem, sendo mais acentuada nas maiores temperaturas, e que todo a remoção de umidade ocorre no período de taxa decrescente. Aspectos da qualidade das fibras pós-secagem também foram avaliadas.

The choice of the drying process plays a key role in reducing the costs of electricity consumption in the food industry. Thus, this study aimed to evaluate continuous and intermittent drying of rough rice, using empirical and diffusion models to describe the drying kinetics, considering only effective time of operation to compare and evaluate these processes. Experiments were carried out during the month of April 2018, in Campina Grande, Paraiba Brazil, and were conducted with continuous and intermittent drying of rough rice grains (about 20 g, each experiment) using a fixed-bed dryer with constant power, at temperatures of 50 and 70 &deg, C. For the intermittent experiments, the intermittency ratio was &alpha, = 2/3 and the drying periods were 10 and 20 min, with intermittency periods of 20 and 40 min, respectively. Comparison between continuous and intermittent drying kinetics indicated reduction in the effective time of all intermittent drying experiments, reaching up to 32.2%, hence promoting energy saving. It was also found that a one-dimensional diffusion model with boundary condition of the first kind properly described all rough rice drying processes and that the effective mass diffusivity is higher in intermittent drying, compared to continuous drying at the same temperature.

In the manufacturing process of ceramic brick, the step of drying needs the control of process variables to uniformly dry the porous material, producing a good end-product. The majority of numerical simulations involving drying of ceramic materials is performed considering only the solid domain, resulting in a very simplified and limited study. This way, the objective of this work is the analysis of the drying process with hot air of an industrial hollow clay brick inside the oven at different temperatures by using computational fluid dynamic (CFD). The results of the temperature and water mass distribution inside the brick and of air in the oven at different times of the drying process are shown, analyzed and checked with experimental data, and it was obtained in a concordance with the data. An equation to calculate the brick water mass diffusivity depending on the drying air temperature was proposed.

The aim of this paper was to prepare, by the freeze-drying method, ionically crosslinked chitosan membranes with different contents of pentasodium tripolyphosphate (TPP) and loaded with 1,4-naphthoquinone (NQ14) drug, in order to evaluate how the physical crosslinking affects NQ14 release from chitosan membranes for cancer therapy application. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), swelling degree, and through in vitro drug release and cytotoxicity studies. According to the results, the molecular structure, porosity and hydrophilicity of the chitosan membranes were affected by TPP concentration and, consequently, the NQ14 drug release behavior from the membranes was also affected. The release of NQ14 from crosslinked chitosan membranes decreased when the cross-linker TPP quantity increased. Thus, depending on the TPP amount, the crosslinked chitosan membranes would be a potential delivery system to control the release of NQ14 for cancer therapy application. Lastly, the inhibitory potential of chitosan membranes ionically crosslinked with TPP and loaded with NQ14 against the B16F10 melanoma cell line was confirmed through in vitro cytotoxicity studies assessed via MTT assay. The anti-proliferative effect of prepared membranes was directly related to the amount of cross-linker and among all membranes prepared, such that one crosslinked with 0.3% of TPP may become a potential delivery system for releasing NQ14 drug for cancer therapy.

Nickel–titanium shape memory alloys (NiTi SMA) working in superelastic regime have been applied in several fields, such as health (medicine and dentistry) and engineering, in a static or dynamic way. The aim of this paper is to study the behavior of these smart metals when subjected to dynamic mechanical stresses (fatigue). Cyclic stress-controlled tensile tests were performed to evaluate the functional and structural superelastic fatigue properties of NiTi SMA wires. The functional parameters were defined as energy dissipation, transformation stresses, residual strain, and superelastic strain, for peak stresses between 500 and 800 MPa, at frequencies of 1, 2, and 3 Hz. These frequencies were determined after a preliminary evaluation of self-heating of the NiTi wires. The number of cycles until failure (Nf) was plotted as a function of peak stresses (S) in an S–Nf fatigue curve, for each studied frequency. It was verified that both frequency and peak stress affected the functional behavior of the NiTi wires. However, the fatigue life was between 5.0 × 103 and 1.6 × 104 cycles, with a faster degradation in this range as higher is the applied peak stress, irrespective of the loading frequency.

This chapter presents four mathematical approaches to describe processes of osmotic dehydration and complementary drying of agricultural products with cylindrical geometry. For this, four solutions for diffusion equation (in cylindrical coordinates) were proposed, two analytical solutions and two numerical solutions. All the formalism necessary to obtain these four solutions were presented. The most suitable models to describe the osmotic pretreatment and the complementary drying were determined using data of the osmotic dehydration of banana in solutions with 40 °Brix of sucrose and at temperature of 40 °C and data of the complementary drying at 40 °C. Programs developed in the FORTRAN language were used for optimization processes. Finally, the results obtained for the four models in the optimization processes were compared in order to obtain the best model.

Transport phenomena in porous media represent an important research area related to heat and mass transfer, and fluid flow fields. This chapter presents information about anomalous behaviour of moisture transient diffusion in vegetable fiber-reinforced composites materials. Composites reinforced with natural fibers are sensitive to influences from environmental agents such as moisture and temperature. Herein, topics related to theory, experiments, mathematical modeling and solution procedures, and technological applications are presented and discussed in detail. An advanced model that (Langmuir-type model) to describe water absorption in polymer composites and the analytical (Laplace transform technique) and numerical (finite-volume method) solutions of the governing equation has been obtained, considering constant thermo-physical properties. In the Langmuir model, moisture sorption can be explained by assuming that water exists in the free and bound phases inside the material. Application has been done to water uptake in Caroa fiber-reinforced polymer composites. Results of the absorption kinetics and concentration distribution of water (free and trapped water molecules) within the material along the process are presented and analyzed. Predicted results compared to experimental data of average moisture content have shown that the model was effective for description of the phenomenon, allowing a better understanding about the effects of moisture migration mechanisms.

Transport phenomena through porous media has been of continuing interest for scientists, researchers and engineers due to the wide range of industrial applications. This chapter presents information about unsteady-state heat transfer and fluid flow inside of packed-bed reactors. The topics covered are related to fundamentals of porous media, chemical reactors, including mathematical modeling and applications. Emphasis is placed on packed-bed elliptic-cylindrical reactor. Based on the concept of local thermal equilibrium, a general mathematical formulation for a pseudo-homogeneous heat transfer model written in elliptic-cylindrical coordinates along with the numerical solution of the governing equation has been presented. Herein, an overview of currently-used models and the pertinent transient conductive transport processes inside the reactor were explored. A numerical example of heat transfer and fluid flow in a multiphase system (elliptic-cylindrical reactor filled with particles) was performed, and results of the temperature distribution inside the equipment at different instant of process are presented and discussed.

This chapter provides information related to simultaneous heat and mass transfer in unsaturated porous bodies with particular reference to drying process of arbitrarily-shaped solids. Several important topics such as drying theory, moisture migration mechanisms, lumped and distributed modeling for homogeneous and heterogeneous bodies, and applications are presented and discussed. Herein, a new phenomenological and advanced lumped-parameter model written in any coordinate system is presented, and the analytical solutions of the governing equations, limitations of the modeling and general theoretical results are discussed. The proposed model includes different effects such as shape of the body (hollow or not hollow), heat and mass generation, and coupled heating, evaporation and convection phenomena.

Porous membranes are equipment used to separate different phases, restricting, totally or partially, the transport of one or more species present in a fluid solution. Separation processes can be classified in microfiltration, ultrafiltration, nanofiltration and reverse osmosis Filtration using porous membranes has presented promising results in many industrial sectors, especially in water treatment. This chapter provides theoretical and experimental information about ceramic and polymer membranes, with particular reference to separation process. Herein, several topics related to this theme, such as, theory, experiments, macroscopic mathematical modeling, and technological applications are presented and well discussed. CFD simulations of the water/oil separation process using a tubular ceramic membrane have been performed. The study clarified the importance of the CFD technique to elucidate the fluid flow phenomena in porous membrane as used in liquid filtration processes.

The purpose of this chapter is to provide theoretical and experimental information about polymer composite manufacturing reinforced with fiber by using Resin Transfer Molding process. It is a process, in which the liquid resin is injected in a closed mold with a fibrous preform inserted. This physical process is similar to the fluid flow in porous media, thus, the process control becomes essential. Here, diverse topics related to this theme, such as, theory, experiments, advanced macroscopic mathematical modeling, in which is included the effect of the resin sorption by fibers, exact solution of the governing equations, and technological applications are presented and well discussed. The study clarifies the importance of the resin sorption effect on the hydrodynamic of the resin flow inside the mold cavity and fibrous preform.