Drying Kinetics of Silica Gel: Statistical Discrimination Using Nonlinearity Measures

Abstract

The objective of the present work was to analyze the drying kinetics of silica gel based on an experimental study performed in a thin-layer dryer and a statistical discrimination of the main drying kinetic equations. Most semi-empirical drying kinetics equations presented in the literature are nonlinear; thus, care should be taken when estimating parameters, since in some situations the estimators may not be appropriate. There are procedures available to validate the statistical properties of the least squares estimators of nonlinear models. In this study, five semi-empirical drying kinetics equations were discriminated using measures of curvature and bias. The results showed that the Overhults equation is the best one to describe the drying kinetics of silica gel.

On the Influence of Particles Characteristics on Moisture Diffusivity during Drying of Granular Porous Media

“…Especially for drying processes, this may be a very interesting practice, since the operational conditions of the air influence the drying kinetics significantly [1]. An appropriate use of these conditions favors the reduction of the total process time and operational costs, promotes an increase in drying capacity, and provides a better control of the operational variables of entry and a final product of better characteristics.…”

“…Air humidity is then removed by means of physical attraction of water molecules to the adsorbent surface of particles and a balance between water and air is established. When the available pores are filled with water, moisture is removed by capillary condensation when the pressure of the saturated vapor is reduced due to surface tension effects [1]. Once partially saturated with moisture, the adsorption columns must be thermally regenerated upon drying so that they can be used again in the desorption process of moist air.…”