A tunnel dryer is to be used to dry 30 lb/h of raw cotton (dry basis) with

Question:

A tunnel dryer is to be used to dry 30 lb/h of raw cotton (dry basis) with a countercurrent flow of 1,800 lb/h of air (dry basis). The cotton enters at 70°F with a moisture content of 100% (dry basis) and exits at 150°F with 10% moisture (dry basis). The air enters at 200°F and 1 atm with a relative humidity of 10%. The specific heat of dry cotton can be taken constant at 0.35 Btu/lb-oF. Calculate:

(a) The rate of evaporation of moisture.

(b) The outlet temperature of the air.