Thin Layer Drying Characteristics of Rough Rice (1)

Abstract

Using a laboratory dryer, a series of thin layer drying experiments were performed on rough rice at five constant temperatures with absolute humidity of 0.01kg/kg' of air, changing the bed depth in three levels (7mm 17mm and 27mm). As the result, it was shown that the depth of a bed considered to be a thin layer in practical use was not fixed among differnt drying conditions.
It was also found that the whole drying period was divided into two drying stages, namely drying, first, takes place mainly in the hull and then drying rate becomes governed by the internal diffusion rate of grain kernel. Since this thin layer drying characteristics are similar to the single kernel drying characteristics, they are thought to be represented as the average drying characteristics of all single kernels in the bed.