Modelling of Fluidized-bed Drying of Black Tea

Abstract A mathematical model was developed for fluidized-bed drying of tea. This was developed into a simulation model which can be used for either batch or continuous drying. The simulation model was validated on a thin-layer drying test rig, and on fluidized-bed dryers. To account for the loss of efficiency between thin layer and fluidized-bed, an efficiency factor of 0·6 was used, which was appropriate for, and validated on, an experimental batch dryer, a pilot-scale continuous dryer and a commercial dryer in a tea factory. The simulation model is useful for design, operational setting and control system design. The constant rate drying phase is shown to be a property of the drying air rather than the material being dried.