Water exiting the condenser of a power plant at 38ºC enters a cooling tower with a mass flow rate of 4.5 x 107 kg/h. A stream of cooled water is returned to the condenser from a cooling tower with a temperature of 30ºC and the same flow rate. Makeup water is added in a separate stream at 20ºC. Atmospheric air enters the cooling tower at 25ºC and 35% relative humidity. Moist air exits the tower at 30ºC and 95% relative humidity.
Determine the mass flow rates of the makeup water and dry air in kg/h. The cooling tower operates at steady state. Heat transfer with the surroundings can be neglected, as can changes in kinetic and potential energy. The pressure remains constant at 1.0 atm throughout.