Drying behaviour of maize and green peas immersed in fluidized bed of inert energy carrier particles

Drying behaviour of maize and green peas was investigated in a bench scale fluidized bed dryer with an inert energy carrier (2.7 mm glass beads and steel balls). The effects of drying solid diameter, inert material type, amount of inert material, air velocity and temperature on the rate of drying were studied. A mathematical model is proposed for predicting the drying rate and temperature variation of spherical shape drying solids. It was found that presence of inert particles enhances the rate of drying. The rate of drying increases with decreasing drying solid diameter, increasing the inert material thermal conductivity and increasing air temperature. However, air velocity, amount of inert material and initial moisture content have no appreciable effects on the rate of drying in well fluidized systems. The independence of rate of drying on air velocity especially in well-fluidized systems indicates that external convection is not a controlling step in this process. Experimental results showed that drying rate decreases by increasing the mass ratio of drying solid to inert material.