The most common question that comes to mind while thinking about cooling towers is how cooling tower works, what is the cooling tower working principle and the classification of cooling towers.
Here is the answer to this question.
Cooling Towers work on the principle of evaporation. They use the process of heat transfer to dissipate the heat generated from industrial processes, such as power generation, or from HVAC systems, into the atmosphere. The hot water that has absorbed heat from the process, is pumped into the cooling tower and spread over a large surface area in the compact space, to allow for heat transfer between water and air.
Cooling Tower Working Principle
This process can be broken down into simpler steps for a clearer understanding:
- Hot water from processes is pumped to the top of a cooling tower where it is atomized into water droplets with the use of a rotary sprinkler or nozzles.
- The water droplets trickle down through a filling material, which provides a large surface area for heat exchange.
- The water is simultaneously exposed to airflow.
- As the water falls and is exposed to the air, heat is transferred from the water to the air.
- Some of the water evaporates and cools the remaining water.
- The cooled water is consistently collected in the basin below the air inlets and reused in the process, forming a circuit that saves water and improves efficiency.
- This way heat that was transferred from the water is dissipated into the atmosphere.
Classification of Cooling Towers
Another important question that usually arises in the minds of buyers/users is how many types of cooling towers are there, and how they are classified.
Cooling Towers are primarily classified into two main types:
Depending on the nature of the airflow making contact with the atomized water droplets, Cooling Towers are defined into different classes. Simply providing an enclosed space with controlled air inlets, with no use of propellers (no fans) in any manner, forms the basis of Natural Draft Cooling Towers. However, the use of mechanical equipment like fans to propel the air against the flow of the water spray classifies the Cooling Tower as Mechanical Draft.
Mechanical Draft Cooling Towers are further divided into two types based on the direction in which the air flows through/across the water to allow for evaporation and optimal heat transfer. These are namely Forced Draft and Induced Draft – names that accredit their properties. The Forced Draft fan arrangement pushes the air current forcefully inward, while the Induced Draft fan arrangement induces a pull of the air current vertically or horizontally.
Two of the more popular types of Cooling Towers – Counterflow and Crossflow, are both Induced Draft designs, differentiated based on the direction of airflow with respect to the spray of water.
Counterflow Cooling Towers
Counterflow Cooling Towers have Induced Draft fan arrangements and operate on the same basic principle of evaporation as all other types of cooling towers. The key difference is that in this design, the air flows vertically through and in the opposite direction of the water spray.
These are available in both round/bottle-shaped and square/rectangular shaped designs, where the water is introduced at the top of the tower and falls down with the force of gravity, while air is drawn upward through the tower by fans. The air and water never mix, but the air cools the water by absorbing its heat through evaporation. The cooled water is collected at the bottom of the tower and recycled, while the hot air is expelled from the top of the tower.
The counterflow design allows for efficient heat transfer in environments where it has an optimal area for air to enter from all sides.
Crossflow Cooling Towers
Crossflow cooling towers also have Induced Draft fan arrangements, but here the air flows horizontally across the spray of water.
These are available mainly in square/rectangular-shaped designs, where the hot water is sprayed over the fill material downward, while the air is drawn across the fill material in a perpendicular direction. The cooled water is again collected at the bottom of the tower and introduced back into the circuit.
Crossflow cooling towers are designed with a smaller footprint than counterflow cooling towers, making them a good option for facilities with limited space. They are also simpler in design and easier to maintain compared to other types of cooling towers.
What is cooling tower, its uses and its top 5 benefits- Explained
Which Cooling Towers are more efficient – Counterflow or Crossflow?
The term efficiency is relative and is entirely reliant on the needs of the end users. Counterflow designs are more suited to open spaces, and crossflow designs help fulfil the cooling requirements in restricted spaces. We at Delta aim to provide the best quality and service through our variety of designs and our wide range of products. We assure our customers of a swift response and assist them to the best of our abilities.
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