Moisture Transfers of Rough rice

Abstract

The aspects of the moisture transfers between the dry rough rice and the wet rough rice during the storage, when the inequality of dryness was occured, were investigated in this report with the contact in layers and in mixture.
The results are as follows:
(1) A moisture gradient which occurs in case of the drying in layers is not vanished by means of leaving as it is.
However, during the long time storage, wetting or drying by the atmospheric effect reaches to about 10cm deep.
(2) when the dry rough rice contact with the wet rough rice in layers, the moisture transfer is observed.
The quantity of the transferred depends on surrounding temperature, moisture difference between the dry and the wet rough rice, contact area and elapsed time after the contact. The quantity of the transferred moisture is represented with the linear equation, i. e.
Q₁=(a+bx) A (Ma-Mb) in early state, and by the constant exponential equation i. e. Q₂=C₁x^dA (Ma-Mb) in later state, where Q₁, Q₂: the quantity of transferred moisture (10^-4gr.), x: the elapsed time (hr.), A: the contact area(cm²), Ma: the dry basis moisture content of the wet material (%), Mb: the dry basis moisture content of the dry material (%), a, b, C₁, α: the constant numbers which depend on surrounding temperature and elapsed time.
(3) When the dry rough rice and the wet rough rice are contacted in mixture, the velocity of the transfer is faster than that in layers. The curve of the moisture transfer is changed by the moisture difference between the dry rough rice and the wet rough rice, and by the surrounding temperature; its empirical formula may be written as follows: Q₃=C₂x^β (D.Ma-E.Mb), Where Q₃: the quantity of transferred moisture (gr.), D: the weigh tof the dried matter of the wet material(kg), E: the weight of the dried matter of the dry material(kg) (4) Although the moisture transfer between the dry rough rice and the wet rough rice is observed to some extent, both moisture contents do not agree with the mean moisture content because of the difference of the dry course and the wet course of the equilibrium moisture content. However, the higher the surrounding temperature, the closer the both curves.