MODELING OF THE DRYING PROCESS THE SEEDS OF COWPEA

ABSTRACT: The study aimed to model the drying curves of cowpea beans (Vigna unguiculata (L.) Walp.) in different temperatures determine the coefficient of effective diffusion and the activation energy. For this, we used seeds of beans-cowpea cultivar BRS Guariba, harvested manually, with a water content of 21% (wet basis), dried until the water content 11% (wet basis). Drying was performed in the experimental dryer under controlled temperatures of 30, 40 and 50 °C ± 1 °C, and relative humidity of the air drying between 14 and 59%. 12 models of non-linear regression were tested and for selection the best model was considered to: the significance of the regression coefficient t test, the magnitude of the adjusted coefficient of determination (R²), the average relative error (P) and the estimated average error (SE). It was observed that the drying time for of the beans-cowpea seeds was 10,4 ; 5,6 ; and 2,1 h to the temperatures of 30, 40 and 50 °C, respectively; among the number tested, the mathematical model the Midilli was the best fit to experimental data. The coefficient of diffusion increases with temperature, with values between 5,047 x 10-11 to 12,011 x 10-11 m² s-1 for the temperature range from 30 to 50 °C. The relationship between the coefficient of diffusion effective and the drying temperature can be described by Arrhenius equation, which presents activation energy of 35,04 kJ mol-1 for spreading the liquid in the drying process of the of beans-cowpea seeds.摘要：本研究旨在对豇豆（Vigna unguiculata (L.) Walp.）籽粒的干燥曲线进行建模，以确定有效扩散系数与活化能。为此，我们采用了手工收获的BRS Guariba品种豇豆种子，其初始湿基含水率为21%，经干燥至湿基含水率11%。干燥实验在可控温度的实验干燥装置中进行，温度分别设置为30、40和50℃±1℃，干燥空气的相对湿度介于14%至59%之间。本研究共测试了12种非线性回归模型，模型筛选标准包括：回归系数t检验的显著性、调整决定系数（R²）的大小、平均相对误差（P）以及平均估计误差（SE）。结果显示，在30℃、40℃和50℃条件下，豇豆种子的干燥时长分别为10.4、5.6和2.1小时；在所测试的所有模型中，Midilli数学模型对实验数据的拟合效果最优。扩散系数随温度升高而增大，在30℃至50℃的温度区间内，其数值介于5.047×10^-11至12.011×10^-11 m²·s^-1之间。有效扩散系数与干燥温度之间的关系可通过阿伦尼乌斯（Arrhenius）方程描述，该方程得出豇豆种子干燥过程中水分迁移的活化能为35.04 kJ·mol^-1。