What Cooling Towers Do?
A cooling tower is a heat removal system used to remove heat from a production or manufacturing process. The process can be a simple heating and air condition system in a building or a complex industrial process such the cooling of water used in the oil refinery process, a chemical plant or a power plant. A cooling tower will vary in size according to the needs of the process it cools for. Some cooling towers are found on the roof tops of high rise office buildings and others are as tall as an office building or even larger. Cooling towers allow the water to be cooled and then returned for use in the industrial or air conditioning process. This saves enormous amounts of money, time and energy.

Removing The Heat
There are two ways in which cooling towers work to remove heat---evaporation or the use of air. Temperature measurements taken during each of these cooling process are called the wet-bulb air temperature and the dry-bulb air temperature. The dry-bulb air temperature is used when heat is removed by exposing the water to air. The wet-bulb temperature is used when heat is removed by the process of evaporation. Cooling towers are often seen in pairs or cells. Each of these cells are independent of each other and provide the possibility of backup if one should fail.

Cooling With Air
Water needing to be cooled is pumped to the top of the tower and then directed to flow down a designated path where the water forms into droplets. These droplets are met by a current of air that is blowing upward and past the water. The water is cooled by the air as it passes. It then collects at the bottom of the cooling tower structure where it is returned to the production process. Some air-cooled towers use large fans at the top of the structure to draw the air up.

Cooling With Evaporation
Cooling through the evaporative process is taking advantage of a physical phenomenon. The evaporation of water (molecules in a liquid state change and become a gas, rising into the air) causes the water to automatically cool. The determining factor of how well this phenomenon works depends on the contrast of temperatures between the air and the water. The greater the difference, the better the cooling effect. Humid climates are not places in which to use this cooling process. The evaporative process transfers the heat from the water to the air and can be compared to the process and purpose of perspiration in the human body. A production process with lots of heated water to cool and located in a dry climate will cool well with an evaporative process. Evaporative processes are either open circuits or closed circuits. Some systems use both types of circuits and are referred to as two-stage evaporative cooling.