SIMULATION OF PACKED-BED DRYING OF FOODSTUFFS WITH AIR-FLOW REVERSAL

A model for the simulation of batch dryers was developed. The effect of shrinkage of the materials during drying was incorporated into the model. This model was extended to include the case of airflow reversal. The results of the simulation for constant inlet air conditions were compared with experimental data obtained during batch drying of carrot cylinders. The effect of airflow reversal on the bed-averaged drying curves as well as on the local temperature and water content profiles was analysed The results showed that both moisture and temperature profiles in the bed were flatter when airflow reversal was applied to the drying process while the average drying curves were practically unchanged. The effects of the starting time (t(1)) and period of duration (Delta t) of the airflow reversal were studied through numerical simulations for different lengths of the bed of drying.