Drying of clay slabs: prediction by means of one-dimensional diffusion models

Abstract

The main purpose of this article is to describe convective drying of clay slabs with initial moisture content of 0.11 (db) at temperatures of 50 and 90 °C. To describe the water diffusion process, was considered: a) constant effective mass diffusivity (Model 1); b) variable effective mass diffusivity (Model 2). A numerical solution of the one-dimensional diffusion equation with boundary condition of the third kind was proposed in order to describe the drying process. The solution was coupled with an optimizer in order to estimate the process parameters for each drying air temperature using experimental datasets and the inverse method. Comparative studies were performed between Models 1 and 2 in order to define the accuracy of description of the drying process. Comparative studies are also conducted on the proposed models and on diffusive models with two- and three-dimensional geometries. An analysis of statistical indicators shows that Model 2 is comparable to models with two- and three-dimensional geometries, being in perfect agreement with the experimental results. However, the computational processing time for the proposed model is much shorter than that obtained with the use of two- and three-dimensional geometries. However, it was observed that the one-dimensional model overestimates the process parameters.