Modeling fixed-bed drying of bark

A model for fixed-bed drying of bark has been developed. The model takes heat and mass transfer between the air and bark into account and the volumetric heat transfer coefficient was used as fitting parameter in the model. The assumption of adiabatic saturation of the air leads to too high drying rates but a model with three size fractions shows good agreement both between experimental laboratory data and data from an industrial dryer. A sensitivity analysis for different air temperatures, air velocities, and bed heights show how the dryer capacity depends on these parameters.