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Predicting the flow behavior of particles is important for the equipment design and optimization of processes and operations involving granular materials. Simulations using the discrete element method (DEM) have been used to gain insights about the granular flow, but the correct use of this technique requires knowledge about the input parameters. However, reliable measurements of these parameters remain a challenge. The purpose of this study was to test and validate experimental methodologies for determining important DEM parameters, including the coefficients of restitution and static and rolling friction, for the particle–particle and particle–wall interactions. The experimental tests were reproduced using DEM simulation to enable the identification of the best procedure for measuring each parameter. The influence of the thickness of the material on which the particles are colliding on the experimental measurement of the coefficient of restitution were quantified. It was also performed a deep statistical analysis of the simulations results using experimental design techniques to identify the significant input parameter in each measurement technique, using loose and grouped particles.

The particle dynamics in a flighted rotary drum operated with different numbers of flights and under different operating conditions was simulated by using both the Eulerian (computational fluid dynamics, CFD) and the Lagrangian (discrete element method, DEM) approaches. The simulated solid holdups in the flights as a function of the flights’ tip angular position were compared with experimental data. A systematic analysis of the computational demands of each approach was performed, as well as the impact of reducing the particle shear modulus in DEM simulations. Furthermore, the influence of the turbulence phenomenon on the particle behavior predicted by CFD simulations was also assessed. The choice of an appropriate numerical approach proved to be of great importance in the accuracy of particle dynamics prediction in a flighted rotary drum.

The industrial processing of acerola (Malpighia emarginata D.C.) produces huge quantities of waste material that are badly discarded or undervalued. In spite of this, acerola wastes have a high content of antioxidant compounds. The aim of this work was to study the extraction of antioxidant compounds from acerola residues using ultrasound assisted extraction. Using multiple regression techniques, the effects of ethanol concentration in the hydroethanolic solution (C), extraction time (t), temperature (T), and liquid–solid ratio (R) on the total phenolic content, total flavonoid content and antioxidant potential were investigated. The best extraction conditions were identified using the desirability function, which is a multi-response optimization technique. The optimal processing parameters were 67.5% of ethanol concentration, temperature of 80.9 °C, liquid/solid ratio of 59.8 mL/g, and extraction time of 13.6 min. HPLC–UV has been used to identify the main antioxidant compounds obtained under these optimal condition. Based on the results, acerola waste has high potential for better use, such as in food and pharmaceutical applications.

Fruit processing generates a large amount of waste that is generally discarded or underused. However the wastes of some fruits, such as acerola, contain bioactive substances with health promoting properties and potential technological applications. This paper evaluates the performance of a hybrid system composed of a microwave assisted rotary drum for the dehydration of acerola wastes and considers the efficiency of this new system and the product quality (bioactive compounds content). The mixture and segregation processes in the rotary drum induced by differences in moisture content, rotation speed, and filling degree were also evaluated. Good operating conditions for mixture were identified and they were related to the regimes of solids motion in the rotating drum. This study also analyzed the effects of power density and rotation speed on dehydration performance. Conditions with high moisture removal that lead to a product with high bioactive compounds content were also identified.