Search

This article addresses how to express the behaviors that develop stresses within a porous media during convective drying processes. The work is focused on the coupling of the thermal (temperature distribution), hygroscopic (moisture, humidity), and mechanical (strains and stresses) aspects shown during the drying process of a saturated porous medium. Natural clay plate samples were used as a model material. Using two different mechanical behaviors (elastic and viscoelastic), the strain–stress equations were studied and discussed through the simulation results. Obtaining almost the same parameters of the main modeling variables (temperature, liquid pressure, and moisture content), a significant difference was observed between the results obtained for the stresses assuming the two behaviors, particularly depending on the viscoelastic parameters deduced from an experimental study. The simulation highlights a response of the medium supposed viscoelastic different to that of elastic case in intensity and response time. [ABSTRACT FROM PUBLISHER]

The present study proposes the development of a complete mathematical modelling transfer phenomena involving at the same time heat, mass and momentum transfer during the drying process of clay. Clay is a generic example of colloid materials forming particulate gels. That can be considered as bi-constituent, homogeneous, isotropic, and highly deformable. The model was numerically solved by the finite difference method and validated by comparison of the numerical results with a previous set of experiments data. The simulation has allowed the determination of spatio-temporal evolution within the solid of different variables: temperature fields, moisture contents, displacement, deformation and stresses. The parametric sensibility has been analyzed in the case of thermophysical properties and the external heat transfer coefficient. Various values of external conditions have been analyzed. [ABSTRACT FROM AUTHOR]

In this study, one got involved in the thermodynamic characterization of two types of clay to be dried. It concerns the determination of the chemical composition through X-ray diffraction, index of plasticity, volumic mass and especially the determination of the sorption isotherms of water vapor on these products at three different temperatures 30, 50 and 70°C. The isosteric enthalpy of adsorption is calculated by the Clapeyron equation it varies from 0 to 2k J/mol for Tunisian clay G, and from 0 to 3 k J/mol for French clay R. Four models provided by the literature i.e., Chung-Pfost, Henderson, Halsey and Guggenheim-Anderson and de Boer (GAB) have been tested and evaluated (correlation factor, standard deviation) to determine the best possible fitting, allowing for the interpolation of experimental results. From the comparison of the results, one noticed that both the Henderson and the GAB models perfectly described the experimental measures for the two types of clay with factors of correlation situated around one and standard deviations tending towards zero. This set of characterizations will allow us at a later stage to understand the drying process of these two types of clay. [ABSTRACT FROM AUTHOR]