乐昌香芋热风干燥动力学及模型拟合

研究乐昌香芋在不同热风温度(50、60、70、80、90℃),不同热速率(1.5、2.0、2.5、3.0 m/s),不同切片厚度(2、3、4、5 mm)下干燥曲线和干燥速率曲线。利用干燥经验模型Logarithmic、Twoterm、Modified page、Henderson and Pabis、WeibullⅠ对干燥过程水分比与干燥时间关系进行模型拟合,以决定系数、残差平方和与加权卡方检验系数判断拟合结果优劣。结果表明,水分比随时间逐渐减少,变化逐渐变缓。香芋干燥过程以降速干燥为主,热风温度70℃时干燥速率最快,干燥时间最短;热风速率2.0m/s时干燥速率较快,有利于节能降耗;切片厚度3mm时干燥速率较快,干燥时间较短。WeibullⅠ模型能很好地描述香芋热风干燥过程,拟合的决定系数均大于0.9979,残差平方和均小于0.00288,加权卡方检验系数均小于1.69×10–4。

Drying kinetics and model fitting of Lechang taro during hot-air drying process

The drying and drying rate curves of Lechang taro were studied under different hot air temperatures(50,60,70,80,90℃),different hot air rate(1.5,2.0,2.5,3.0 m/s)and different slice thickness(2,3,4,5 mm).The relationship between water ratio and drying time in the drying process was fitted by the empirical models such as:Logarithmic,Twoterm,Modified page,Henderson and Pabis,WeibullⅠ.The fitting results were judged by the coefficient of determination,residual Sum of squares and reduced Chi-square.The results showed that the moisture ratio(MR)decreasing with drying time and the water ratio changes gradually.The hot-air drying of Lechang taro was mainly in slow-down drying stage.When the hot air temperature was 70℃,the drying rate was the fastest and the drying time was the shortest.The drying rate was faster when the hot air rate was 2.0 m/s,which was beneficial to saving energy and reducing consumption.When the slice thickness was 3 mm,the drying rate was faster and the drying time was shorter.WeibullⅠmodel could describe the hot-air drying process of taro very well.The coefficients of determination were more than 0.99791.The residual Sums of squares were less than 0.00288.The reduced Chi-squares were less than 1.69×10–4.