Heat Transfer
In a laboratory test run, the rate of drying was found to be 0.5 x 10-3 kg/m².s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry basis. A tray dryer is used to dry 100 kg (dry basis) of the same material under identical conditions. The surface area of the material is 0.04 m²/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is

5000
2000
4000
6000

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is

Finned tube heat exchanger with air inside and steam outside
Shell and tube heat exchanger with air on shell side and steam inside tubes
Finned tube heat exchanger with air outside and steam inside
Shell and tube heat exchanger with air inside tubes and steam on shell side

ANSWER DOWNLOAD EXAMIANS APP