Question

This is problem 7-13 from El-Wakil’s Powerplant Technology book -- a wet-dry cooling tower receives 20x10⁶ lb_m/h of condenser cooling water at 110 degF. The water is cooled in the dry section to 90 degF and in the wet section to 70 degF. The outside air is at 1 standard atmosphere, 60 degF, and 40 percent relative humidity. The air leaves both dry and wet sections at 81 degF. Calculate (a) for the dry section the outside cooling air required, in pound mass per hour, and the relative humidity leaving it, (b) for the wet section the outside cooling air required, in pound mass per hour, (c) the condition (temperature and relative humidity) of the air leaving the tower, (d) the required makeup of condenser cooling water due to evaporation, in pound mass per hour, and (e) the percentage savings in that makeup because of the use of a wet-dry instead of an all-wet tower.

Answer 1