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.

中文翻译：

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干燥过程中温度对突尼斯黏土产品影响的研究

摘要

这项工作的目的是评估干燥温度对粘土样品的对流干燥过程以及有效扩散率的影响。这项研究是在突尼斯的原始粘土产品上进行的，其简单的球形几何形状的初始含水量为0.35 kg水/ kg db。在实验室对流干燥机中，在30至60°C的温度范围内，研究了空气干燥特性。恒定风速为1.44 m / s，空气湿度比率为50％。提出了基于Fick和Crank扩散方程的四个解析解来描述干燥过程。第一个和第二个方程忽略了收缩效应，而其他两个方程则将其视为基本参数。根据获得的结果，事实证明，空气温度的升高增加了干燥速率以及有效的扩散系数。根据本研究中使用的解析解，可以得出结论，包括收缩效应的模型给出了最低的有效扩散系数值。