Cooling Towers – A Boon to the HVAC Industry

A cooling tower is a device designed to cool water by removing heat through evaporative cooling.
Cooling towers are essential for dissipating excess heat from various systems, including industrial
processes, power plants, and heating, ventilation, and air conditioning (HVAC) systems.

Main Components of a Closed-Loop Condenser Water Cycle

Shell & Tube Heat Exchanger
Main Pipe in Distribution Manifold
Spray Nozzle
Fill Media
Water Collection Basin
Centrifugal/Condenser Pump

The repetitive use of water in a closed cycle significantly conserves natural water resources, saving up to 25-50 times more water compared to once-through cooling methods. This process also helps prevent thermal pollution in water bodies. Typically, only about 5% of the water is lost through evaporation, with losses replenished by fresh water.

The Process of Evaporation in a Cooling Tower

Air enters the cooling tower through the lower portion and flows upward. Water is introduced through the main pipe, distributed evenly, and then sprayed through the nozzles. It then passes through the fill media, where the water is broken into small droplets, greatly increasing the surface

area. At this stage, the water and air flow in opposite directions, which facilitates efficient heat transfer. The cooled water is collected in the basin at the bottom and is recirculated. Meanwhile, the humid, warm air, having absorbed the heat, is expelled from the tower. Although the exhaust air may appear similar to smoke, it is, in fact, evaporated cooling water. In this sense, a cooling tower can be likened to a "cloud-making machine."

Convection in Cooling Towers

Natural Convection occurs due to buoyant forces, where air rises because of density
differences created by temperature variations.

Forced Convection is induced using fans, which help move the air through the system. These
fans can be controlled with a Variable Frequency Drive (VFD) by linking them to temperature
sensors.

Drift eliminators are installed in cooling towers to minimize the escape of water droplets with the
exhaust air, ensuring more efficient operation.

Forced Convection in HVAC Cooling Towers

Forced convection is preferred in HVAC cooling towers because it allows for greater heat exchange in
a smaller area and in a shorter time. Unlike natural convection, which is slower and requires more
space, forced convection is ideal for cooling towers used in chiller systems, which are typically more
compact.

Key Processes & Principles

Convection
Evaporation
Heat Transfer
Latent Heat
Sensible Heat
Mass Transfer
Counterflow
Crossflow