How do Cooling Towers Work?
Cooling towers are water-cooled systems that take waste heat away from a building. They’re most commonly used in industrial applications, but larger commercial and residential areas also install cooling towers to increase the efficiency of their larger HVAC system.
In a short summary, the purpose of a cooling tower is to cool down water that gets heated up by industrial equipment and processes. Water comes into the cooling tower hot (from the industrial process) and goes out of the cooling tower cold (back into the industrial process).
Whilst only trained specialists should work on cooling towers, it’s beneficial to understand how these units work to better appreciate the importance of looking after them.
How do Cooling Towers Work?
Cooling towers work by having water and air contact each other in a very particular way. Hot water enters the unit, dispersed as droplets through nozzles. This increases surface area, leading to greater heat transfer. Meanwhile, a top fan draws the air upwards, which absorbs the heat of the water as it rises.
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The air effectively hijacks waste heat, which is ultimately ejected into the atmosphere. The remaining water simply falls to the bottom of the chamber. It is collected in a basin, before being pumped back into the building, where it will be used elsewhere in the HVAC system.
Although there are various types of cooling towers, they mainly differ in terms of how they direct air. Crossflow towers have air pass horizontally over the vertical water (hence the name), whilst counterflow designs use vertical airflow beneath the fill media. In any case, the underlying principles are heat transfer through evaporation.
What are the Components of a Cooling Tower?
Here are the key components of a cooling tower:
- Fill Media: Cooling towers are capable of evaporating large amounts of heat rapidly thanks to the fill media, a highly angular structure that allows far greater contact between the flowing water and drawn-through air. The surface area is dramatically increased by either a splash or film fill, meaning heat and moisture are evaporated at a much faster rate.
- Fan: Cooling towers can either be induced, forced, or natural draft. Induced draft means that an axial fan is positioned at the top of the system, pulling air upwards. Conversely, forced draft means either an axial or centrifugal fan is pushing the air. In any case, fans help air to navigate the equipment.
- Nozzles: hot water goes through pipework and eventually makes it to the nozzles, which disperse water as small droplets. Nozzles effectively atomize the water meaning that heat can be transferred from the water to the air far more easily.
- Drift Eliminators: In an ideal world cooling towers would lose only heat, but there is inevitably some water waste. Drift eliminators cause the air stream to suddenly change direction, causing water to separate from the air and remain in the system.
Properly Maintaining a Cooling Tower
There are several issues of running a cooling tower, namely water conservation and corrosion. Continuous evaporation of water leaves behind a mass of dissolved impurities, such as calcium and magnesium. These mineral deposits can cause scaling and reduce the lifespan of components.
Although the principle of cooling towers is simple, they require specialist maintenance in order to run safely and reliably. Otherwise, you will compromise the efficiency of the system before equipment ultimately fails, causing huge disruption to production.
Cooling towers require proper maintenance to ensure the most efficient operation and to reduce downtime. If you need any advice on cooling systems and looking after your investment, contact Baikal Mechanical, specialist HVAC engineers committed to excellent design and long-term service.