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目的以二至丸为研究对象,探索丸剂热风干燥过程水分的变化规律,进行薄层干燥特性及模型研究,为改善裂丸、结壳、假干燥等现象提供理论依据。方法研究二至丸在不同热风干燥温度50、60、70、80、90℃下丸剂的水分比、干基含水率、干燥速率随干燥时间的变化曲线及干基含水率与干燥速率间的关系。利用经验模型Henderson&Pabis模型、Newton模型、Page模型、Logarithmic模型、Two term Exponential模型、Wang&Singh模型、Midilli et al.模型对丸剂干燥过程中水分比与时间的关系进行模型拟合与验证;以Fick扩散定律为依据,确定不同热风干燥温度丸剂的水分有效扩散系数(Deff)及活化能(E_a)。结果二至丸干燥曲线结果表明二至丸的水分比、干燥速率与干燥介质的温度密切相关,随着干燥时间的延长,物料的水分不断减少;由干燥速率曲线可知,随着热风温度的升高,干燥速率增加,加速水分的迁移。通过比较各模型的相关系数(R~2)、卡方(χ~2)和标准误差(RMSE),可知Midilli et al.模型的R~2平均值最大、χ~2及RMSE平均值最小,分别为0.996 86、2.43×10~(-4)及1.93×10~(-4),结果表明Midilli et al.模型能够很好地描述与预测丸剂的干燥过程;实验数据得到Deff值在8.6×10~(-11)~3.13×10~(-10) m~2/s,Ea为30.97 k J/mol。结论二至丸的热风干燥过程可以进行模型拟合并得到了验证,该研究为探索丸剂的干燥特性和品质提供新的思路。
Objective To investigate the change rule of moisture in the pellet hot air drying process with Erzhi Pills as the research object, to study the drying characteristics and model of the thin layer, and to provide a theoretical basis for the improvement of phenomena such as cracking, crusting and fake drying. Methods The relationship between the water content, dry basis moisture content and drying rate of Erzhi Pills at different hot-air drying temperatures of 50, 60, 70, 80, and 90 ℃ were studied. The relationship between dry weight-based moisture content and drying rate . The model fitting and verification were carried out by using empirical model Henderson & Pabis model, Newton model, Page model, Logarithmic model, Two term Exponential model, Wang & Singh model and Midilli et al model. The Fick’s law of diffusion As the basis, determine the effective moisture diffusion coefficient (Deff) and activation energy (E_a) of different hot air drying temperature pills. Results The drying curve of Erzhi Pills showed that the moisture content and drying rate of Erzhi Pills were closely related to the temperature of the drying medium. With the extension of drying time, the water content of the materials decreased continuously. As the drying rate curve showed, with the increase of hot air temperature High, dry rate increases, accelerate the migration of water. By comparing the correlation coefficient (R ~ 2), chi-square (χ ~ 2) and standard error (RMSE) of each model, it can be seen that the mean value of R ~ 2 and the average value of χ ~ 2 and RMSE in Midilli et al. Respectively. The results showed that Midilli et al. Model can well describe and predict the drying process of pellets. The experimental data show that the Deff value is 8.6 × 10 -4, 10 ~ (-11) ~ 3.13 × 10 ~ (-10) m ~ 2 / s, Ea was 30.97 kJ / mol. Conclusion The process of hot air drying of Erzhi Pills can be modeled and verified. This study provides new ideas for exploring the drying characteristics and quality of pills.