In some modern power plants equipped with gas purification ducts such as the Staudinger Power Plant Grosskrotzenburg and the Rostock Power Plant the cooling tower is also used as a chimney. In plants that do not have gas purification ducts this causes problems with corrosion.

Quantitatively, the material balance around a wet cooling tower system is controlled by the structural operating variables: flow rate, evaporation and wind losses, racking rate, and concentration cycles:

In the sketch above, the water pumped from the tower reservoir is cooling water routed through process chillers and condensers in an industrial facility. The cold water absorbs heat from the hot process streams that need to be cooled or condensed, and the absorbed heat heats the circulating water (C). The heated water returns to the top of the cooling tower and falls in fine jets—presenting a large surface area for air cooling—onto the fill material inside the tower. As it drips, it comes into contact with the air that rises through the tower, by natural draft or forced by large fans. This contact causes a small amount of water to be lost through wind drag (W) and another part of the water (E) through evaporation. The heat necessary to evaporate the water is derived from the water itself, which cools the water upon its return to the original tank and where it is available for circulation again. The evaporated water leaves the salts it contains dissolved among the bulk of the water that has not undergone evaporation, which causes the concentration of salts to increase in the circulating cooling water. To prevent the concentration of salts in the water from becoming too high, part of the water is removed (D) for discharge. A new quota of fresh water (M) is supplied to the tower reservoir to compensate for losses due to evaporated water, wind, and withdrawn water.

The balance of water in the entire system is:.

Since the evaporated water (E) has no salts, the chloride balance of the system is:.

and, consequently:

From a simplified tower heat balance:

Wind losses (W), in the absence of manufacturer data, can be estimated to be:.

The concentration cycles in the cooling towers in an oil refinery are normally between 3 to 7. In some large power plants. Cooling tower concentration cycles can be much higher.

With respect to the heat transfer mechanism used, the main types are:.

• - Wet cooling towers or evaporative cooling towers work on the principle of evaporative cooling. The working coolant (usually water) is the evaporated fluid and is exposed to the elements.

• - Closed-loop cooling towers (also called fluid coolers) pass the working coolant through a large heat exchanger, usually a radiator, over which clean water is distributed. sprayed and applied a fan-induced draft. The resulting heat transfer performance is similar to that of a wet cooling tower, with the advantage of protecting the working fluid from environmental exposure and contamination.

• - adiabatic cooling towers") spray water into incoming air or onto a cardboard pad to cool the air before it passes through an air-cooled heat exchanger. Adiabatic cooling towers use less water than other cooling towers, but do not cool the fluid as close to the wet bulb temperature. Most adiabatic cooling towers are also hybrid cooling towers.

• - dry cooling towers (or dry chillers) are closed-loop cooling towers that operate by heat transfer through a heat exchanger that separates the working coolant from ambient air, as in a radiator, using convection heat transfer. They do not use evaporation.

• - Hybrid Cooling Towers are closed-loop cooling towers that can switch between wet or adiabatic and dry operation. This helps balance water and energy savings in a variety of weather conditions. Some hybrid cooling towers can switch between dry, wet and adiabatic modes.

In a wet cooling tower (or open circuit cooling tower), hot water can be cooled to a temperature "lower" than the dry bulb temperature of the ambient air, if the air is relatively dry (see dew point and psychrometry). As ambient air passes through a flow of water, a small portion of the water evaporates and the energy required to evaporate that portion of the water is taken from the remaining mass of water, thereby reducing its temperature. Approximately 2300 kilojoules per kilogram of thermal energy is absorbed by the evaporated water. Evaporation results in saturated air conditions, which reduces the temperature of the water processed by the tower to a value close to the wet bulb temperature, which is lower than the ambient dry bulb temperature, the difference determined by the initial humidity of the ambient air.

To achieve better performance (more cooling), a medium called "filling" is used to increase the surface area and contact time between air and water flows. "Splash fill" consists of material placed to disrupt the flow of water and cause splashing. "Film fill" is made up of thin sheets of material (usually PVC) over which water flows. Both methods create a greater surface area and contact time between the fluid (water) and the gas (air), to improve heat transfer.

• - Dew point.

• - Psychrometry.

• - Evaporative cooling.

• - Types of cooling towers and their installation.

• - Cooling towers: Design and operation considerations (in English).

• - What is a cooling tower? Archived May 7, 2010, at the Wayback Machine.

• - Cooling water. Tower work scheme.

• - Cooling tower (includes diagrams).

• - Cooling tower in Türkiye.

In some modern power plants equipped with gas purification ducts such as the Staudinger Power Plant Grosskrotzenburg and the Rostock Power Plant the cooling tower is also used as a chimney. In plants that do not have gas purification ducts this causes problems with corrosion.

Quantitatively, the material balance around a wet cooling tower system is controlled by the structural operating variables: flow rate, evaporation and wind losses, racking rate, and concentration cycles:

In the sketch above, the water pumped from the tower reservoir is cooling water routed through process chillers and condensers in an industrial facility. The cold water absorbs heat from the hot process streams that need to be cooled or condensed, and the absorbed heat heats the circulating water (C). The heated water returns to the top of the cooling tower and falls in fine jets—presenting a large surface area for air cooling—onto the fill material inside the tower. As it drips, it comes into contact with the air that rises through the tower, by natural draft or forced by large fans. This contact causes a small amount of water to be lost through wind drag (W) and another part of the water (E) through evaporation. The heat necessary to evaporate the water is derived from the water itself, which cools the water upon its return to the original tank and where it is available for circulation again. The evaporated water leaves the salts it contains dissolved among the bulk of the water that has not undergone evaporation, which causes the concentration of salts to increase in the circulating cooling water. To prevent the concentration of salts in the water from becoming too high, part of the water is removed (D) for discharge. A new quota of fresh water (M) is supplied to the tower reservoir to compensate for losses due to evaporated water, wind, and withdrawn water.

The balance of water in the entire system is:.

Since the evaporated water (E) has no salts, the chloride balance of the system is:.

and, consequently:

From a simplified tower heat balance:

Wind losses (W), in the absence of manufacturer data, can be estimated to be:.

The concentration cycles in the cooling towers in an oil refinery are normally between 3 to 7. In some large power plants. Cooling tower concentration cycles can be much higher.

With respect to the heat transfer mechanism used, the main types are:.

• - Wet cooling towers or evaporative cooling towers work on the principle of evaporative cooling. The working coolant (usually water) is the evaporated fluid and is exposed to the elements.

• - Closed-loop cooling towers (also called fluid coolers) pass the working coolant through a large heat exchanger, usually a radiator, over which clean water is distributed. sprayed and applied a fan-induced draft. The resulting heat transfer performance is similar to that of a wet cooling tower, with the advantage of protecting the working fluid from environmental exposure and contamination.

• - adiabatic cooling towers") spray water into incoming air or onto a cardboard pad to cool the air before it passes through an air-cooled heat exchanger. Adiabatic cooling towers use less water than other cooling towers, but do not cool the fluid as close to the wet bulb temperature. Most adiabatic cooling towers are also hybrid cooling towers.

• - dry cooling towers (or dry chillers) are closed-loop cooling towers that operate by heat transfer through a heat exchanger that separates the working coolant from ambient air, as in a radiator, using convection heat transfer. They do not use evaporation.

• - Hybrid Cooling Towers are closed-loop cooling towers that can switch between wet or adiabatic and dry operation. This helps balance water and energy savings in a variety of weather conditions. Some hybrid cooling towers can switch between dry, wet and adiabatic modes.

In a wet cooling tower (or open circuit cooling tower), hot water can be cooled to a temperature "lower" than the dry bulb temperature of the ambient air, if the air is relatively dry (see dew point and psychrometry). As ambient air passes through a flow of water, a small portion of the water evaporates and the energy required to evaporate that portion of the water is taken from the remaining mass of water, thereby reducing its temperature. Approximately 2300 kilojoules per kilogram of thermal energy is absorbed by the evaporated water. Evaporation results in saturated air conditions, which reduces the temperature of the water processed by the tower to a value close to the wet bulb temperature, which is lower than the ambient dry bulb temperature, the difference determined by the initial humidity of the ambient air.

To achieve better performance (more cooling), a medium called "filling" is used to increase the surface area and contact time between air and water flows. "Splash fill" consists of material placed to disrupt the flow of water and cause splashing. "Film fill" is made up of thin sheets of material (usually PVC) over which water flows. Both methods create a greater surface area and contact time between the fluid (water) and the gas (air), to improve heat transfer.

• - Dew point.

• - Psychrometry.

• - Evaporative cooling.

• - Types of cooling towers and their installation.

• - Cooling towers: Design and operation considerations (in English).

• - What is a cooling tower? Archived May 7, 2010, at the Wayback Machine.

• - Cooling water. Tower work scheme.

• - Cooling tower (includes diagrams).

• - Cooling tower in Türkiye.