Mathematical modelling of thin-layer drying in peanut fruit

ABSTRACT The aim of this study was to fit mathematical models to the experimental data from the thin-layer drying of peanut fruit subjected to different drying-air temperatures. Peanut fruit from the IAC 505 cultivar were used. The peanut fruit were subjected to drying in a forced ventilation oven at different temperature levels (40, 50, 60 and 70 ºC). Ten mathematical models, traditionally used to represent the kinetics of thin-layer drying, were fit to the experimental data. Based on the results, it can be concluded that among the models adjusted to the experimental data, the Page model was chosen to represent the phenomenon of thin-layer drying in peanut fruit. The effective diffusion coefficient increases with the rise in temperature, and its relation to the drying temperature can be described by the Arrhenius equation. The values for the thermodynamic properties, enthalpy and entropy, were reduced with the increasing temperature of the drying air, while the values for Gibbs free energy increased with the increase in temperature.摘要 本研究旨在针对不同干燥空气温度下花生果实薄层干燥的实验数据拟合数学模型。实验采用IAC 505品种的花生果实，将其置于强制通风烘箱中，在40、50、60、70℃四个不同温度梯度下进行干燥处理。选取10种常用于描述薄层干燥动力学的经典数学模型对实验数据进行拟合。基于拟合结果可知，在所有适配实验数据的模型中，Page模型最适合描述花生果实的薄层干燥过程。有效扩散系数随干燥温度升高而增大，其与干燥温度的关联可通过阿伦尼乌斯（Arrhenius）方程描述。干燥空气温度升高时，焓、熵等热力学参数的数值随之降低，而吉布斯自由能（Gibbs free energy）的数值则随温度升高而增大。