Slabs of filter cake with a bone-dry density of 1,600 kg/m3 are to be dried from an initial free-moisture content of 110% (dry basis) to a final free-moisture content of 5% (dry basis) batchwise in trays that are 1 m long by 0.5 m wide with a depth of 3 cm. Drying will take place only from the top surface. The drying air conditions are 1 atm, 160oC, and a 60oC wet-bulb temperature. The air velocity across the trays is 3.5 m/s. Experiments under these drying conditions show a critical free-moisture content of 70% (dry basis), with a falling-rate period like that of Figure a, based on free-moisture content. Determine:

(a) The drying time for the constant-rate period.

(b) The drying time for the falling-rateperiod.

Transcribed Image Text:

Free-moisture content (a) Empirical case 1 Drying rate