Question

A counterflow induced-draft cooling tower operates with inlet and exit water temperatures of 105 and 85°F when the air has dry-bulb and wet-bulb temperatures, respectively, of 90 and 76°F. The tower has 4 ft of stacked plastic fill, and the flow rates are G, = 2,000 lb/h.ftand G. = 2,200 lb/h.ft. (a) Determine the number of transfer units, the height of a transfer unit based on the overall gas-phase driving force, and the temperature approach. (b) If the cooling load remains the same but the air temperature drops to 70°F with a wet-bulb temperature of 60°F, predict the water temperature and the temperature approach.

Answer 1