An Empirical Equation for Thin Layer Drying of Rough Rice with Heated Air

Abstract

The purpose of this experiment was to generalize the relationship between the thin layer drying curves and some drying condition such as air temperature, initial moisture content and air velocity during the short time region when the grain temperature varies with the constant high air temperature. This generalized equation was intented to be applied for this layer drying curve to the practical rapid drying systmes such as fluidized bed and tempering drying techniques, etc.
As a result of this experiment due to faster air velocity, the rate of drying was faster. This phenomenon could be interpreted that the rate of drying varied indirectly with air velocity in order to change the increasing rate of grain temperature due to varying coefficient of heat transfer which was governed by air velocity. Consequently, the drying characteristic of rough rice could be thought of as phase falling rate, even if initial moisture content was very high. The empirical equations estimating the drying curves at any drying condition were
M-M_e/M₀-M_e=1-e-(Kt)^-n
K=exp{-6.4509×10³/T_a+273.16×G-(0.04373-0.005209M₀)+(0.0766M₀+11.5237)}
n=(0.05773-0.001342M₀)×(T_a-T_p0)0.02027M₀+0.19148