Secagem de mamona da variedade BRS energia: experimentação e simulação.

Abstract

Castor oil-based by-products are used in the manufacture of several commercially important commodities like surfactants, coatings, greases, pharmaceuticals, cosmetics, polyesters, polymers, etc . The castor bean has in the compositions approximately 50% oil, with special characteristics such as high viscosity, heat and pressure stability, low freezing point and ability to form waxy substances after chemical treatments. The castor bean is a potential candidate for the production of biodiesel; However, this product must be dried, in order, to reduce moisture content (10%), for safe storage. Drying is a complex operation involving transient transfer of heat and mass that provokes physical and chemical transformations in the product, which, in turn, may cause changes in the quality thereof, as well as the mechanisms of heat and mass transfer. This work presents an experimental and numerical study of castor bean fruits drying (Ricinus communis L., variety "BRS Energia"). A three-dimensional transient mathematical model is presented to predict the heat and mass transfer and to simulate the distribution of temperature and moisture content inside the solid, considering the constant thermophysical properties, using ANSYS CFX® software. For validation of the numerical methodology were performed drying experiments with castor bean fruits of the variety BRS Energy. In the experiments, were used drying temperatures of 40, 50, 60, 70, 80, 90 and 100ºC. The experimental data of drying were adjusted to the empirical mathematical model of Page, presenting for all treatments, coefficients of determination (R2) greater than 99.60% and standard deviation values of the estimate (SE) lower than 0.0165. The drying kinetics of temperature and moisture content obtained by CFX® were compared with the experimental drying kinetics and a good approximation has been obtained. Diffusive mass coefficients were obtained for different drying conditions. It was found that the diffusive mass transport coefficients tend to increase with increasing drying air temperature.