In this work, recycled poly(ethylene terephthalate) (PETR) was blended with virgin high-density polyethylene (HDPE) in an internal mixer in an attempt to obtain a material with improved properties. A compatibilizer (PE-g-MA) and a chain extender (Joncryl) were added to the PETR/HDPE blend and the rheological and thermal properties of the modified and unmodified blends as well as those of virgin PET with virgin HDPE (PETV/HDPE). All the blends were characterized by torque rheometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The data obtained indicate that the incorporation of either the chain extender or the compatibilizer agent led to increases in torque (and hence in viscosity) of the blend compared to that of the neat polymers. The joint incorporation of the chain extender and compatibilizer further increased the viscosity of the systems. Their effect on the crystallinity parameters of HDPE was minimal, but they reduced the crystallinity and crystallization temperature of virgin and recycled PET in the blends. The thermal stability of the PETR/HDPE blend was similar to that of the PETV/HDPE blend, and it was not affected by the incorporation of the chain extender and/or compatibilizer.

The conformation of a ceramic piece follows the steps of preparing the raw material, molding, lamination, drying, and firing. Drying is a thermodynamic process of heat and mass transfer, with dimensional variations of the product that requires a large amount of energy. Ceramic materials when exposed to non-uniform drying may suffer cracks and deformations, reducing their post-drying quality. Thus, this work aimed to study the drying of industrial ceramic blocks in an oven with forced air circulation. Experiments were carried out to characterize the clay and drying of the ceramic block at temperatures ranging from 50 °C to 100 °C. Results of the chemical, mineralogical, granulometric, differential thermal, and thermogravimetric analysis of the clay, and heating kinetics, mass loss, and dimensional variation of the industrial ceramic block are presented and analyzed in detail. It was found that the clay is basically composed of silica and alumina (≈ 80.96%), with an average particle diameter of 13.36 μm. The study proved that drying at high temperature and low relative humidity of the air generates high rates of mass loss, heating, and volumetric shrinkage in the ceramic product, and high thermo-hydraulic stresses, which cause the appearance and propagation of cracks, gaps, and cleavages, compromising the final quality of the product.

In the oil industry and academy, the treatment of water contaminated with oil using conventional hydrocyclones and membranes has been an alternative to meet the requirements established by environmental control agencies. However, such equipment is not fully efficient in the treatment of much diluted oily water, with both presenting restrictions in their performance. In this sense, the present work proposes to study the separation process of oily water using a new configuration of hydrocyclone, equipped with a porous ceramic membrane in the conical part’s wall (filtering hydrocyclone). For the theoretical study, a Eulerian–Eulerian approach was applied to solve the mass and momentum conservation equations, and the turbulence model, using the computational fluid dynamics technique. The results of the velocity, pressure and volumetric fraction of the involved phases, and the separation performance of the hydrocyclone, are presented, analyzed, and compared with those obtained with a conventional hydrocyclone. The results confirmed the high potential of the proposed equipment to be used in the separation of the water and oil mixture.

Fresh bananas are fruits with high moisture content after harvest and are submitted to a drying process to minimize waste and increase shelf life. This work aims to experimentally study the convective drying of bananas in an oven with hot-air recirculation, evaluating the geometric shape during moisture removal and product heating. Hand-peeled whole-banana samples, cut into longitudinal and transversal slices were dried at temperatures of 40 and 70 °C. Results of drying kinetics, heating and dimensional variations in terms of surface area and volume are presented and analyzed. It was found that cut bananas dry, heat up and change their dimensions faster than bananas in their natural form and that the area/volume relationships and the air temperature influence the drying kinetics, heating and volumetric variations of the fruit.

Due to the increase in the number of people affected by chronic renal failure, the demand for hemodialysis treatment has increased considerably over the years. In this sense, theoretical and experimental studies to improve the equipment (hemodialyzer) are extremely important, due to their potential impact on the patient’s life quality undergoing treatment. To contribute to this research line, this work aims to study the fluid behavior inside a hollow fiber dialyzer using computational fluid dynamics. In that new approach, the blood is considered as multiphase fluid and the membrane as an extra flow resistance in the porous region (momentum sink). The numerical study of the hemodialysis process was based on the development of a mathematical model that allowed analyzing the performance of the system using Ansys^® Fluent software. The predicted results were compared with results reported in the literature and a good concordance was obtained. The simulation results showed that the proposed model can predict the fluid behavior inside the hollow fiber membrane adequately. In addition, it was found that the clearance decreases with increasing radial viscous resistance, with greater permeations in the vicinity of the lumen inlet region, as well as the emergence of the retrofiltration phenomenon, characteristic of this type of process. Herein, velocity, pressure, and volumetric fraction fields are presented and analyzed.

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.