At steady state, a device for heating and humidifying air

Chapter 12, Problem 12.91

(choose chapter or problem)

At steady state, a device for heating and humidifying air has \(250 \mathrm{ft}^{3} / \mathrm{min}\) of air at \(40^{\circ} \mathrm{F}\), 1 atm, and 80% relative humidity entering at one location, \(1000 \mathrm{ft}^{3} / \mathrm{min}\) of air at \(60^{\circ} \mathrm{F}\), 1 atm, and 80% relative humidity entering at another location, and liquid water injected at \(55^{\circ} \mathrm{F}\). A single moist air stream exits at \(85^{\circ} \mathrm{F}\), 1 atm, and 35% relative humidity. Using data from the psychrometric chart, Fig. A-9E, determine

(a) the rate of heat transfer to the device, in Btu/min.

(b) the rate at which liquid water is injected, in lb/min.

Neglect kinetic and potential energy effects.