Investigation of the effect of temperature on Tunisian clay product during drying process

Abstract

The aim of this work was to evaluate the influence of drying temperature on the convective drying process of clay sample as well as on the effective diffusivity. The study was performed on Tunisian raw-clay product in here simple spherical geometry with initial moisture content of 0.35 kg water/kg d.b. Air-drying characteristics were investigated in a laboratory convective dryer for a temperature range varying from 30 to 60 °C at a constant air velocity of 1,44 m/s with an air humidity ratio of 50%. Four analytical solutions based on Fick’s and Crank’s diffusion equations were proposed to describe the drying process. The first and the second equations neglected shrinkage effect while the two other equations consider it as a fundamental parameter. According to the obtained results, it was proved that the increase in air temperature increases the drying rate, as well as the effective diffusion coefficients. Based on the analytical solutions used in this study, it was concluded that the model including the shrinkage effect gives the lowest value of the effective diffusion coefficient.