Question:-
In a cooling tower, the minimum temperature to which water can be cooled is equal to the
Option (A)
dew point temperature of the air at the inlet
Option (B)
dry bulb temperature of the air at the inlet
Option(C)
thermodynamic wet bulb temperature of the air at the inlet
Option(D)
mean of the dew point and dry bulb temperature of the air at the inlet
Correct Option:
(C)
Question Solution:
Theoretically, the water can be cooled to wet-bulb temperature of entering air if the air leaving the cooling tower becomes saturated. Generally the temperature (Tb) of water coming out from cooling tower is 3°C to 5°C above the WBT of the entering air (Twb or Tc)

The temperature difference between the WBT of incoming air and outgoing temperature of water is known as cooling tower ‘Approach’ – Higher the quantity of water circulated, lower will be the approach of tower.
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