两种不同晾房中无核白葡萄薄层干燥的数学模型

Mathematical Modeling on Thin Layer Drying of Seedless Grape in Two Different Air-drying Shelters

为了分析比较两种不同的晾房(塑料膜晾房与纱网晾房)中无核白葡萄晾干的干燥曲线和有效扩散系数,并用数学模型表示出来,采用自动记录仪测定了晾房中的空气相对湿度、气流速度以及内外空气温度,同时测定了葡萄的干燥速度,并将10个常用数学模型进行拟合比较。结果表明:塑料膜晾房具有较快的干燥速度和能够使葡萄获得较大的水分迁移的有效扩散系数;Wang-Singh模型能够更好地描述葡萄晾房干燥过程。上述结果对于葡萄晾房优化设计,缩短葡萄干燥周期,提高葡萄干燥质量具有参考价值。

The objective of this work is to analyze the drying curves and effective diffusion coefficients of the Sultana grape （cv. Thompson seedless） in two different air drying shelters, namely, a shady shelter with plastic film and a shady shelter without plastic film. The air temperature, relative humidity and velocity inside and outside the two shelters were automatically recorded with an automonitor system, and their drying rates of grape were measured at the same time. And ten different thin layer mathematical drying models were compared according to their coefficient of determination to estimate solar drying curves. The results indicated that, the shady shelter with plastic film had rapidder drying velocity and can make grapes have bigger effective diffusion coefficient of moisture transfer. According to the results, a Wang and Singh drying model could satisfactorily describe the air drying curve of Sultana grapes in the shady shelter with plastic film. The above results are useful for optimal~ design of air-drying shelter so as to improve the raisin quality and to reduce the drying circle.