Mathematical modeling of microwave-assisted inert medium fluidized bed drying of cylindrical carrot samples

Drying behavior of cylindrical samples of carrot was investigated in a microwave-assisted fluidized bed of inert particles. A pilot-scale microwave-assisted fluidized bed dryer was set up for this purpose. Glass beads particles were used as inert materials. Based on the simultaneous heat and mass transfer, a mathematical model was proposed for predicting the temperature and moisture distribution in the drying sample. Considering the carrot radiuses and the penetration depth of the electromagnetic waves, a uniform electric field strength distribution within the drying material was assumed in the proposed model. The heat loss due to surface evaporative cooling was also considered at the external boundaries. A numerical solution was developed for the proposed model using an implicit finite difference method in one-dimensional system. The model was validated by comparing the predicted data with the experimental data, obtained from different cylindrical carrot samples during drying. The effects of microwave power density and also drying air temperature on the moisture and temperature profiles were investigated. (c) 2008 Elsevier B.V. All rights reserved.