粉粒体層の乾燥における限界含水率について
1976 年 13 巻 6 号 p. 328-333
詳細
1976 年 13 巻 6 号 p. 328-333
The critical moisture content of drying is an essential characteristic for the design of drying equipment or the selection of optimum drying condition: nevertheless the method of predicting its value from the drying conditions and the natures of material has never been established.
This paper dealt with the method of predicting the critical moisture content by assuming the equilibrium condition between the capillary suction pressure and the gravitational force acting on the liquid moisture in the nonhygroscopic coarse granular packed beds, and by making use of the relationship between the dimensionless capillary suction pressure and the moisture saturation, which was introduced by Kubota et al.
As the results it was pointed out that if the condition of surface at critical point was determined, the critical moisture content was predictable from a dimensionless parameter X(ρwgεdpL/σcosθ(1-ε)φ) depending upon the characteristics of material etc.
Drying experiments were performed for the coarse granular materials of glass beads and calcites by varying the depth of bed, average particle diameter and initial moisture content etc. The experimental values of critical moisture content were compared with the predicted ones and the agreement proved to be satisfactory.
