Prediction in Constant-Rate Drying Region. A granular insoluble solid material wet with water is being dried in the constant-rate period in a pan 0.61 m × 0.61 m and the depth of material is 25.4 mm. The sides and bottom are insulated. Air flows parallel to the top drying surface at a velocity of 3.05 m/s and has a dry bulb temperature of 60°C and wet bulb temperature of 29.4°C. The pan contains 11.34 kg of dry solid having a free moisture content of 0.35 kg H2O/kg dry solid, and the material is to be dried in the constantrate period to 0.22 H2O/kg dry solid.

a. Predict the drying rate and the time in hours needed.

b. Predict the time needed if the depth of material is increased to 44.5 mm.