Estudo do processo de secagem de blocos cerâmicos estruturais: modelagem e simulação.

Abstract

Several studies on the drying of ceramic materials have been developed in various engineering and manufacturing sectors. Considering that, this drying process, however, requires large investments and high energy consumption, raising the costs of this sector. In many situations, it is common to use theoretical solutions such as numerical simulations that allow, with relative ease and low cost, to change the operational and geometric conditions of the dryer or object of drying. In this sense, this work was carried out with the objective of studying the drying process of industrial ceramic structural bricks, considering as a solid medium, via Computational Fluid Dynamics (CFD), under the following experimental conditions: drying temperature of 50 °C and 100 °C , initial moisture content of 0,11723191 and 0,169366 (kg/kg, b.s) and relative humidity 18,39% and 2,34%, respectively. A mesh study was performed using the Grid Convergence Index (GCI) method. A transient three-dimensional mathematical model was adopted based on the conservation equations of mass, moment and energy, to describe the heat and mass changes during the drying process. The drying phenomenon of the structural brick was studied in two situations: the first the drying of compensating brick alone considering the model of drying by liquid diffusion. The second situation, where the domain of study considers the brick in a greenhouse, in this case making the coupling of the models of liquid diffusion to the brick and forced convection on the side of the greenhouse. The results of the field of pressure, velocity, temperature and volume fraction of the water inside the brick obtained by the commercial package Ansys CFX® 15.0 were analyzed. Comparison between the simulated moisture and temperature content with the experimental data allowed us to validate the numerical results and, thus, to estimate the mass diffusion and heat transfer coefficients on the surface of the material. The results of the simulations indicate that there are regions with important temperature and humidity gradients which can lead to cracks and deformations. ..