Water from the condenser of a power plant enters a cooling t

Water from the condenser of a power plant enters a cooling tower at 95degreeF with a mass flow rate of 1 times 10^6 lb./hr. An equal amount of an at 75degreeF dry bulb, 52degreeF wet bulb enters the bottom of the natural draft tower and exits as saturated air at 90degreeF. Calculate the mass flow rate and temperature of the condenser water leaving the cooling tower.|

Solution

I will be solving in SI units.

Wi = 95 F = 35 deg C Wo = ??

Ai = 52 F = 11.11 deg C Ao = 32.22 deg C

Please not that as per working principle of cooling tower, it cools the working fluid to near the wet-bulb air temperature. So we will use wet bult temp for calculations.

Heat transfer balance -> m Cp dT (air) = m Cp dT (water)

m is same for both,

Cp air = 1 kJ/Kg K

Cp water = 4.17 kJ/Kg K

So equation becomes -> 1 * (32.22-11.11) = 4.17 * (35-Wo)

Solving for Wo, we get, Wo = 29.93 deg C = 85.87 F