Numerical simulation of the moisture diffusion in copra drying process

This study intends to determine the diffusion coefficient of moisture during hot air drying of copra. A computational fluid dynamic model was used to fine-tune the system parameters with experimental data. Drying experiments were performed in a laboratory scale hot air dryer. Drying rate of copra can be divided into two sub-drying periods, first and second falling rate periods and two significantly different diffusion coefficients were obtained. This study further identified the critical moisture content of 30% as the probable limit between the first and second falling rate periods. The spatial distribution of moisture in the solid phase and the spatial distribution of vapor in the gas phase were also obtained as important findings of this study.