A filter cake placed in a 1-foot x 1-foot tray 1 inch deep is dried on the top surface with air at 80F wet bulb and 120F dry bulb temperatures flowing parallel to the surface of the pan drying at a speed of 2.5 ft/sec. The dry cake density is 120 lb/ft³ and the citrus moisture content is 0.20 lb water/lb dry solids.

1. What is the magnitude of the rate of drying in the period at constant rate?
2. How much time is required to dry the material from moisture 1 to critical moisture?
3. What variables of the drying process would you change to reduce the drying time? Explain your recommendation.