Water migration in clay slabs during drying: A three-dimensional numerical approach

Clay products for construction offer durability, thermal and acoustic comfort as well as low cost. Drying is an important stage of the production process of these products, and it was studied herein. Experiments on convective drying of clay slabs with initial moisture content of 0.23 (db) were performed at 50, 60, 70, 80 and 90°C. Drying occurred in two distinct periods: constant and falling rate. In the first period, the process was described by an empirical equation and, in the second one, by the diffusion equation with boundary condition of the third kind. To eliminate some restrictions found in the literature, a three-dimensional numerical approach was used to describe the process. Equations were obtained to express the process parameters as a function of the drying air temperature and local moisture content. A simulation using the values obtained from these equations for the process parameters is coherent with the experimental data.