Simulação e experimentação da secagem de cerâmica vermelha em sistemas térmicos industriais.

Abstract

This work aims to study theoretical and experimentally the drying of holed ceramic bricks in oven and in an industrial tunnel dryer (cross-flow type). A mathematical model to describe heat and mass transfer between the air and product that considers variables thermophysical properties, porosity and condensation of water vapor in the process is presented. The numerical solution of governing equations is performed using the finitevolume method. A computational code in the Mathematica® language, to obtain the numerical data was developed. To validate the numerical methodology and to study the drying process, experiments were performed in oven and industrial tunnel dryer. Results of temperature, relative humidity and absolute humidity of the air and, moisture content, size and temperature of the solid during the drying process and along the dryer are analyzed and compared with experimental data. We conclude that drying with variable temperature (50 to 100°C) and high relative humidity (70 to 85%), ensures bricks with excellent quality, and that the industrial dryer presents low energy (5,8%) and exergy (-13,6%) efficiencies, high energy consumption to evaporate water from the product and a great loss of energy in the air exhaustion showing to be drying process highly dissipative. For a total drying time of 8 to 10 hours in the industrial dryer, the shrinkage of the brick has changed from 9.15 to 14.84%.