Drying of Clay Slabs during the Falling Rate Period: Optimization and Simulation of the Process Using Diffusion Models

Mass transfer in clay slabs during drying is described using diffusion models with equilibrium (model 1) and convective (model 2) boundary conditions. Drying experiments using hot air were performed for clay slabs with initial moisture content of 0.11 (dry basis, db) at 50, 60, 70, 80 and 90 °C. For this initial moisture content, drying occurred in falling rate. For the slabs, the one-dimensional solutions referring to models 1 and 2 were coupled to optimizers to determine the process parameters in each temperature. Thus, equations can be obtained to express these parameters as a function of the drying air temperature. The analyses of drying processes have indicated that there is a good agreement between the experimental results and the corresponding simulations using the model 2, for all temperatures