The thin layer hot-air drying characteristics of rough rice as a function of hot-air temperature,initial moisture content and air velocity were investigated by using an orthogonal array design and the applicability of 10 mathematical models for the hot-air drying process of rough rice was compared.The results showed that no apparent constant-rate drying period existed in the hot-air drying process,and moisture removal mainly occurred in the falling-rate drying period;hot-air temperature was the main factor that affects the hot-air drying,followed by air velocity.The optimal hot-air drying conditions for rough rice were determined as follows:initial moisture content,20％;hot-air temperature,50 C and air velocity,1.4 m/s.The Page Model was found to be the best mathematical model for describing the drying characteristics of rough rice under these conditions;tempering could effectively inhibit the occurrence of fissuring,and a better effect was observed by raising tempering temperature and prolonging tempering time.Under the conditions of initial moisture content of 24％ and air velocity of 1.4 m/s,the relative mean deviation between the experimental and predicted results were 1.563％ and 1.474％,respectively.The predictive drying curves fitted well the experimental data.With temperature increase from 40 C to 60 C,the effective moisture diffusion coefficient of rough rice increased from 9.69 × 10-10 to 10.77 × 10-10 m2/s,and the activation energy for rough rice drying was 47.1 kJ/mol.%对稻谷进行薄层热风干燥,采用正交试验方法研究稻谷在不同热风温度、初始含水率和热风风速条件下的热风干燥特性,比较10种数学模型在稻谷热风干燥中的适用性.结果表明:稻谷在热风干燥过程中没有出现明显的恒速干燥阶段,且干燥主要发生在降速干燥阶段;热风温度是影响稻谷热风干燥的最主要因素,其次是初始含水率;取初始含水率20％、热风温度50℃、热风风速1.4 m/s的方案为稻谷的最优热风干燥工艺,此时的最佳数学模型为Page模型;缓苏可有效抑制稻谷的爆腰率,缓苏温度越高,缓苏时间越长,缓苏效果越好;当初始含水率24％、热风温度40℃时,实验值和模型值的相对平均误差分别为1.563％和1.474％,表明模型预测的干燥曲线和实验所得的干燥曲线一致性较好;随着热风温度的升高,稻谷的有效水分扩散系数变大,经热风温度从40℃升高到60℃,其有效水分扩散系数由9.69×10-10 m2/s增加到10.77×10-10m2/s,稻谷的干燥活化能为47.1 kJ/mol.
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