This work presents a numerical study of the hydrodynamic of spouted beds using computational fluid dynamics (CFD) simulation. Scaling relationships proposed by He et al. [He et al., Chem. Eng. Sci. 1997;52:329-339] for spouted bed systems based on similitude method are numerically investigated using CFD simulation. In the present work it is verified that the spouted bed scale-up relationships of He et al. [He et al., Chem. Eng. Sci. 1997;52:329-339] produce good numerical results when all of the scale-up relationships are satisfied. It is also verified the behaviour of the numerical results when the scaling procedure is applied in a practical condition. In this case, the properties of fluid and solid are kept constant, which is a real situation of a scale-up procedure in a spouted bed used for drying of grains. In this work it is possible to verify that CFD simulation is a useful tool to evaluate similitude methods in spouted bed (multiphase flow) systems. The commercial package FLUENT 6.3.26 was used in all simulations.

It is well known that a special attention is necessary to infer process information of a spouted bed at full-column using data from semi-cylindrical vessels. In this work experimental data are obtained from a semi-cylindrical spouted bed for comparison with CFD simulations performed using a 3D simulation scheme. The purpose of this paper is to contribute on the discussing about the influence of the flat wall in the solid behaviour inside the semi-cylindrical vessel by comparing numerical results with experimental data. Simulated results of fountain height, spout diameter and particle velocities inside the bed are compared with image data obtained from a semi-cylindrical column. The simulations were accomplished using the commercial package FLUENT 6.3.26.Il est bien connu qu'une attention particulière est nécessaire pour déduire des informationsà partir d'un lit jaillissantà colonne complèteà l'aide de données venant de réservoirs semi-cylindriques. Dans ce travail, des données expérimentales sont obtenuesà partir d'un lit jaillissant hémicylindriqueà des fins de comparaison avec des simulations de CFD menées au moyen d'un schéma de simulation en 3-D. Le but de cet article est de contribuerà la discussion sur l'influence de la paroi plate dans le comportement des solidesà l'intérieur du réservoir hémicylindrique en comparant les résultats numériques aux données expérimentales. Les résultats simulés de la hauteur de fontaine, du diamètre de jet et des vitesses de particules dans le lit sont comparés aux données d'imagerie obtenuesà partir d'une colonne hémicylindrique. Les simulations ontété effectuéesà l'aide du logiciel commercial FLUENT 6.3.26.

-Drying is a single operation employed to prolong the life of a large quantity of vegetables. Carrot (Daucus carota) drying has been the subject of many studies. This plant has been highlighted in the human diet for having high nutritional value, mainly due to the high content of β-carotene. In this work, carrot drying behavior was studied in a regular microwave dryer and a vacuum microwave dryer. A vacuum of 450 mmHg was applied for drying of carrot in different geometrical shapes (cubes, discs and sticks). The samples were dried at power ratings of 1.0 W/g, 1.5 W/g and 2.0 W/g for both methods of drying. The evolution of physical properties such as density, volume and porosity was monitored and related to the moisture content of the sample and to the method of drying and power rating used. The geometric shape of the sample influenced the drying kinetics and it was verified that the cubic form was responsible for a slower drying. The application of vacuum showed no major changes in the drying kinetics in microwave but influenced the physical properties of the material. The influence of power ratings on the content of β-carotene was also evaluated and discussed. The main difference observed was the lower shrinkage of the samples dried in the vacuum microwave compared to those dried only in microwave.

Venturi scrubbers are widely used to control industrial emissions, because of their high efficiency in the removal of particles from gases. To correctly size and design these equipments, detailed information on the fluid dynamics is very important. The purpose of this article is to study, both experimentally and through CFD simulations, the fluid dynamics of the gas and liquid phases in the core of the throat of a rectangular Venturi scrubber under different experimental conditions. The variables studied were the pressure and the volumetric fraction of each phase. The standard κ–ε turbulence model and the volume of fluid (VOF) multiphase model, as implemented in the ANSYS Fluent 12.0 software, were employed. Liquid distribution inside the throat of the Venturi was studied experimentally, using optical imaging techniques. The results indicate that the model and numerical procedures were able to describe both the pressure drop profile and the liquid jet formation and trajectory successfully. The results suggest that, for the same gas and liquid flow rates, the number of liquid injection orifices does not affect the pressure drop, but affects significantly the liquid fraction distribution profile inside the equipment.

-The main objective of this study was to evaluate the effect of the drying process on the vitamin C levels and physical properties of dedo-de-moça pepper. The drying kinetics and the structural properties were determined as a function of moisture content. Convective drying was compared with freeze-drying in terms of product quality, structural properties, retention of vitamin C and rehydration characteristics. Empirical and semi-empirical equations were used to describe the drying and rehydration kinetics. Nonlinear analysis applied to results of convective drying, based on curvature measures and bias measures, showed that the only equation that gives good inference results based on least squares estimators is the Overhults equation. The characterization of the rehydration process was done by determining the indexes that take into account the water absorption capacity and solutes losses. The material dried by lyophilization show greater potential to rehydrate.