Question

PH) 3) Air at a temperature of 60 F and a relative humidity of 60% with a flow rate of 1000 # 3/min enters a warm-air furnace and humidifier unit. The air leaves the unit at a temperature of 120 F and a relative humidity of 12%. If the air flows through the unit at a pressure of 14.5 psia and if the water is supplied to the humidifier at 65 F, using the appropriate equations, determine: a) the mass of water that must be supplied per hour b) the rate at which heat must be supplied per hour (20 nts)

Answer 1

Obtain the inlet properties from the psychometric charts. At T = 60°Fando = 60% h = 21.65Btu/lb da a = 0.00667lb H2O/lb da Vi = 13.42ft / lb Obtain the oulet properties from the psychometric charts. AtT, = 120°F and g =12% h = 38.66Btu/lb da 0 = 0.00885lb H,O/lb da v2 =15.02ft / lb Calculate mass flow rate of dry air. Ó 1000 m = = = 74.52 lb/min V 13.42 a) m, = m. (0,-) = (74.52)(0.00885 -0.00667) = 0.1624 lb/min =2.71x10-3 lb/hr b) Om = m, ( hh) = (74.52)(38.66-21.65) = 1267.6Btu/min =21.13Btu/hr