Understanding Cooling Tower Terminology

As commonly-used heat exchangers, cooling towers are an important part of many buildings' designs. Essentially, they bring hot water into direct contact with cooler air to reduce its temperature, often in a circulatory process. Many of the terms used in modern cooling tower design are only understood by engineers experienced with them. Architects and building designers can gain greater insight into their functions by better understanding the terminology associated with them.

Cross-flow refers to a type of tower design. The approach is to allow water to flow downwards through the tower's fill (see below) as air moves horizontally across it. Therefore, heat is exchanged in a cross flowing pattern.

Counter-flow refers to another common cooling tower principle. These towers are designed such that air is passed vertically upward in the tower. As the name implies, a counter-flow tower has falling water in its fill, meeting air coming in the opposite direction.

Drift eliminators are devices that remove water droplets from a cooling tower's air discharge. As such, they lessen losses of processed water. Drift eliminators can force air and droplets to alter their direction, and this means that drops can be captured and deposited back into the cooling system.

Driveshafts are power distribution devices which transmit force. This is usually done from the output shaft of the motor, operating within the tower itself. At full speed, driveshafts need to be well balanced to avoid vibration, as well as being corrosion resistant and adjustable to keep them in good working order.

Nozzles are often used in cross-flow towers. Their configuration allows a mere gravitational force to be used for the flow distribution system. With a nozzle-run system, the hot water distribution basins are placed above the fill. Then, nozzles located at the top of the tower allow for an even distribution of water throughout the basin floor thereby increasing the efficiency of the tower.

Fans are used in cooling towers to keep aeration working efficiently, ideally with as little vibration as possible. The materials used with cooling tower fans must be able to withstand the corrosive effects the cooling process. After all, such fans are frequently required to operate in harsh environments. Quiet running fans are increasingly popular these days.

Fill refers to a crucial component of a cooling tower. A fill allows the maximum contact surface between air and water to exist while promoting the greatest contact time between them. Essentially, a good fill design will determine efficiency, or otherwise, of a tower. The splash type fill and the film type fill are the most commonly used. The former breaks up the water, and the latter spreads it out over a thin pool in a basin.