A Test of Lumped-Parameter Methods for the Drying Rate in Fluidized Bed Driers for Bioproducts

ABSTRACT

For batch fluidized bed drying of bioproducts the distributed parameter model is presented, in which the internal diffusion equation is coupled to the air balance equations. In practice a large part of the process takes place at high relative humidity of the drying air, equivalent to low driving forces. The results of a number of lumped-parameter methods for the estimation of drying times are compared with those of the full model for the case of constant external conditions around a particle. For low relative humidity of the drying air predictions of drying times with the Regular Regime Power Law method correspond well with the full solution, for higher ambient RH large deviations occur. The other methods are shown to give large deviations in all cases.