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为了研究疏解棉秆微波干燥过程中装载量对干燥时间、干燥速率、干燥效率以及单位能耗的影响,该试验采用微波频率为2 450 MHz,输出功率为1 k W的微波干燥设备,装载量范围在34~200 g的疏解棉秆进行干燥。结果显示:干燥过程经过一个短暂的升速后较长时间处于降速阶段;采用7种常见薄层干燥模型对干燥数据进行非线性拟合,通过比较决定系数、均方根误差、离差平方和,发现Midilli模型是表述疏解棉秆微波干燥的最优模型,干燥系数随着装载量的增加而减小;装载量从34 g增加到200 g时,干燥时间也随之从10 min增加到20 min;疏解棉秆的水分有效扩散系数随着装载量的增加而减小,其平均值介于1.8078×10-8~4.1997×10-8 m2/s,同时基于Arrhenius方程,求得平均活化能为4.82 W/g;装载量在34~200 g时,通过提高装载量能够提高微波干燥效率(7.52%~19.78%),同时降低微波干燥的单位能耗(12.49~35.90 MJ/kg)。研究结果为棉秆的干燥和工业化生产提供参考。
In order to study the influence of load on the drying time, drying rate, drying efficiency and energy consumption per unit area during the microwave drying process of cotton stalk, the microwave drying equipment with microwave frequency of 2 450 MHz and output power of 1 k W was used. The range of 34 ~ 200 g of cotton stalks dried. The results show that the drying process is slowed down after a brief increase in speed, and the drying data are non-linearly fitted by using seven common thin layer drying models. By comparing the coefficient of determination, the root mean square error, the square of the deviation The Midilli model was found to be the optimal model for microwave drying of cotton stalks. The drying coefficient decreased with the increase of the loading. When the loading increased from 34 g to 200 g, the drying time increased from 10 min 20 min. The effective moisture diffusion coefficient of cotton stalk decreased with the increase of loading, the average value was 1.8078 × 10-8 ~ 4.1997 × 10-8 m2 / s, meanwhile, the average activation was obtained based on Arrhenius equation (4.82 W / g). When the loading was between 34 ~ 200 g, microwave drying efficiency (7.52% ~ 19.78%) could be increased by increasing the loading, and the unit energy consumption of microwave drying could be reduced (12.49 ~ 35.90 MJ / kg). The results provide a reference for the drying and industrialization of cotton stalks.