A cooling tower is a tall cylindrical structure with an open top. The use of cooling towers is critical to all industrial processes. They cool the water needed for numerous types of systems to operate including HVAC and industrial. Each system operates differently and uses different technology.
The HVAC Cooling Tower
This system uses evaporative cooling. The water needed is pumped all the way to the top of the tower and as it flows back down it fills the basin. Air is used as the water works its way back down and will release heat as it evaporates.
Once this heat has been released by the water it is pumped through the pipes to a chiller. After the water has absorbed additional heat it is sent back to the tower.
To prevent the water from evaporating a float is used so the water levels in the basin are controlled. The fresh water added to the system is called make-up water. When the water drops below a specific level a valve opens and the make-up water is then added to the system. The water usually comes from a well or the cities supply.
The highest efficiency cooling tower repairs are equipped with a drive capable of various frequencies. These are controlled by using a schedule based on the temperature of the air outside of the tower.
This lets the fan run at a much lower speed and saves energy. This type of tower does need chemicals to treat the water and a solid schedule for maintenance. Some towers are designed to use filters to remove any unwanted particles out of the water.
The Natural Draft Towers
This type of cooling tower uses natural convection. The water is cooled by the circulation of natural air. The difference in air density inside and outside of the tower moves the air and cools the water
Moist, warm air has a higher density than cooler air and rises inside the tower. The cooler air falls and a consistent cycle of air flow is created.
The Mechanical Draft Tower
Fans are the most common mechanism used for air circulation in this type of tower. The most popular are centrifugal and propeller fans. They are a lot more effective than a natural draft cooling tower.
When they are properly exhausted they can be used inside of a building. For this reason they use more power and are more expensive to operate. Mechanical towers are categorized as either Counterflow or Crossflow.
The Crossflow Tower
This tower has the air flowing in a horizontal pattern throughout the structure. Distribution bases are used to send the hot water down. This type of tower is a lot less efficient and the water can freeze causing problems.
The Counterflow Tower
This tower cools air by sending it upward while the water flows down. They are a lot more compact with a much smaller footprint than a Crossflow cooling tower. For this reason they use less energy and are more inexpensive to use.