An Analysis of Initial Drying Charasteristitics of Rough Rice

New Basic Equations and Their Exact and Approximate Solutions

Abstract

Because of the short drying period of rough rice before tempering stage, the drying is assumed to be carried out mainly from the hull surface. A basic equation was derived assuming the uniform moisture content of the hull, and the well-known laws governing the rate of transfer of mass from a solid to a fluid that was proportional to the difference in vapour pressure between solid surface and fluid. The equilibrium moisture content v. s. relative humidity (water activity) curve was used to estimate the vapour pressure of the hull.
The numerical exact solutions were obtained from the above derived equation and the heat balance equation by Runge-Kutta-Gill method. The approximate analytical solutions were also obtained by the method of linearizing the parameters.
The computed results by the exact and the approximate solutions were in reasonable agreement with the experimental observations in initial five or seven drying range.