Comparison

Summary: For the following conditions of water, and air:

Water: in = 50\(^\circ\)C, out = 35\(^\circ\)C
Air: in = 30\(^\circ\)C; 60% RH, out = 45\(^\circ\)C; 90% RH

For a reduction of 1\(^\circ\)C of water, and increase of air temperature by 1\(^\circ\)C:

In indirect contact arrangement with heat exchanger, we need 4.2 kg of air / kg of water.

In direct contact arrangement with cooling tower, we need 0.62 kg of air / kg of water. (which is only 15% of 4.2 kg).

Hence there is a huge reduction in air requirement, which is simply the reduction in size of the equipment.

Comparison of cooling of cooling-water by using a heat-exchanger and by cooling-tower. For reducing the temperature of 1 kg of water by 1oC, it needs 4.2 kg of air allowing for 1oC rise, using a heat exchanger. Whereas with cooling water it's enough to have 0.7 kg of air. By humidification of air, we can achieve a lot of cooling, using about only (1/6)th of air.  Humidification is having a great role in cooling of cooling-waters used in chemical process and power plants.