Numerical Calculation of Internal Stresses in Brown Rice Kernel During Drying Process (Part 1)

On the Moisture Movement in a Brown Rice Kernel

Abstract

In order to investigate the internal stresses of a rice kernel, the moisture movement in the kernel was studied during the drying process. The results obtained were summarized as follows:
(1) It could be considered that the moisture content reached an equilibrium value on the surface of the kernel with the drying condition.
(2) It could be assumed that the mechanism of moisture movement was given by a diffusion model based on the gradient of the moisture content in the kernel.
(3) The effective diffusivity of the kernel could be estimated by observing the drying curve and measuring the dimensions (length, width and thickness) of the kernel, and an equivalent radius of the kernel could be also determined by the above experimental results.
(4) It was found that the temperature of the rice kernel would reach that of the air in a few minutes after drying at the air velocity above 0.5m/sec.