What is Cooling Tower
Industrial cooling tower are an effective way to remove unwanted heat from one place to another using water as transport media in applications where there is a need to have a reliable source of cool water year round in the 70°F to 100°F temperature range. Cooling towers are commonly used to cool products and machinery in a multitude of applications, including injection molding, tool and die cutting, food and beverage, chemicals, lasers, machine tool, semi-conductors and more. While there are a number of different manufacturers using various designs, all cooling towers operate using the same principle of evaporative cooling.
How Does A Cooling Tower Work?
Evaporative cooling is a natural process that provides cooling evaporating water into air. A good example of this is the sudden sensation of getting cold when we step out of a hot shower, or misting fans used to help keep football players cool on the sidelines. While we are in the shower, our skin is wet and not readily exposed to air, but when we step out into the air, the water on our skin begins to evaporate and pulls heat out of our bodies and we feel the cooling effect. Cooling towers use this same principle of evaporative cooling to cool a continuous flow of water.
Cooling towers are essentially large boxes designed to maximize evaporation of water. To do this, they contain material, typically PVC plastic sheets, that create large surface areas for water evaporation to occur. This material is what fills the inside of the cooling tower and is called “Cooling Tower Fill”.
Large cooling towers, like those at nuclear power plants, rely on a natural draft or flow of air through the cooling tower; however, this is only effective on certain very large cooling towers. Most cooling towers use an electrical fan motor to create an air draft or airflow through the cooling tower. This type of cooling tower is called an “Induced or Force Draft” cooling tower.
What is the Purpose of a Cooling Tower
If you are ever looking down from a high-rise building, you might notice square units with fans on top of them on the buildings below. Most people assume cooling towers can only be found on a city building but they can be found on buildings everywhere. Basically, a cooling tower is used to cool water and is a huge heat exchanger, expelling building heat into the atmosphere and returning colder water to the chiller. A cooling tower receives warm water from a chiller. This warm water is known as condenser water because it gets heat in the condenser of the chiller. The chiller is typically at a lower level, like in a basement. The cooling tower’s role is to cool down the water, so it can return to the chiller to pick up more heat.
When the warm condenser goes into the cooling tower, the water is passed through some nozzles which is sprayed into small droplets across the fill, which increases the surface area of water and allows for better heat loss thru greater evaporation. The purpose of the fan on top of the cooling tower is to bring in air from the bottom of the tower and move it up and out in the opposite direction of the warm condenser water of the top of the unit. The air will carry the heat thru evaporating water of the cooling tower into the atmosphere. For every pound of water evaporated approximately 1,000 BTU of water cooling occurs. The heat that gets rejected into the atmosphere is all the unwanted heat from the building.
Water costs money so in order to keep costs and water consumption down, cooling towers will use drift eliminators, which are located above the fill packaging and spray nozzles below the fan. The drift eliminators push some of the water moisture out of the air which then runs back into the fill for further cooling and eventually will gather in the basin of the cooling tower to go back to the chiller. Once it returns to the chiller it will pickup heat and the cycle will begin again.
Different Parts of Cooling Tower
- Eliminator: It is not allowed to pass water. Eliminator is placed the at top of tower, from which only hot air can pass.
- Spray Nozzles and Header: These parts are used to increase the rate of evaporation by increasing surface area of water.
- PVC Falling: It reduces the falling speed of hot water and it is similar to beehive.
- Mesh: When the fan is ON, it uses atmosphere air which contains some unwanted dust particles. Mesh is used to stop these particles and do not allow to enter dust in to cooling tower.
- Float Valve: It is used to maintain level of water.
- Bleed Valve: It is used to control the concertation of minerals and salt.
- Body: Body or outer surface of cooling tower is often made up from FRP (fiber reinforced plastic), which protects the internal parts of cooling tower.