Air at 14.7 psia, 50F, and 60 percent relative humidity is first heated to 72F in a

Question:

Air at 14.7 psia, 50°F, and 60 percent relative humidity is first heated to 72°F in a heating section and then humidified by introducing water vapor. The air leaves the humidifying section at 75°F and 55 percent relative humidity. Determine
(a) The amount of steam added to the air, in lbm H2O/lbm dry air, and
(b) The amount of heat transfer to the air in the heating section, in Btu/lbm dry air.