Secagem de grãos de arroz em leito fixo: modelagem, simulação e experimentação.

Abstract

This work aims to study numerically and experimentally heat and mass transfer during drying of rice grains (BRSMG-CONAI cultivar). A transient three-dimensional mathematical model to predict mass and heat transfer and simulate the moisture content and temperature distributions inside the solid considering solid symmetry, and constants thermophysical properties and volume is presented. Were performed drying experiments with rough rice grain in the drying temperatures 40, 50, 60 and 70°C supported by IPA (Agronomic Institute of Pernambuco), placed in Goiana-PE, Brazil. The grain was considered as an ellipsoid of revolution. Results of moisture content obtained via CFD were compared to experimental. It was found that at low temperatures the drying rate is lower, decreasing of risks in defects on the product and that for higher temperatures we have higher temperature and moisture content gradients inside the grain which generate thermal-hydric stresses, causing cracks and fissures mainly in the early stages of the process. Were made comparisons between theoretical and experimental data of average moisture content and a good fit was obtained, which resulted in the estimation of the mass diffusion coefficient in several drying conditions.