Pneumatic drying of meals: Application of the variable diffusivity model

The superficial and bound moisture removal from soya meal was studied in a pneumatic dryer. The effect of external condition over the effective diffusivity in drying kinetics prediction has been demonstrated and a model that considers time variable diffusion coefficient was developed and correlated with gas temperature and velocities. A simple experimental technique using a pulse injection of humected solid was utilized to determine real drying kinetics under steady state operation with solids recycling. The model fitted the experimental data well over a gas temperature range between 100 degrees C and 300 degrees C and gas velocities of 3.5 m/s and 20 m/s.