What is Cooling Tower Fill, and Which Type is Best?
Cooling towers are designed to cool water as quickly and efficiently as possible. To accomplish this, the water needs to flow over as much surface area as possible — in order to provide the maximum possible contact between the air and the water. “Fill” is a medium that’s used in cooling towers to increase the surface area available for the water.
Two Types of Fill
Fill comes in two primary types: splash and film. Either type can be used in both crossflow and counterflow towers. But each type of fill has distinct advantages that make it more advantageous for specific conditions.
Splash fill works by causing the flowing water to cascade through a series of parallel splash bars, which, in turn, causes the water to splash (hence, the name). Because splash fill provides the least opposition to airflow in a horizontal direction, it’s primarily used in crossflow cooling towers.
A big advantage of splash fill is that it’s very forgiving of insufficient initial water distribution, since the splashing activity redistributes the water at each level of splash bars. Because of this, a cooling tower with splash fill effectively handles water containing debris (which has a tendency to interrupt the normal flow pattern of the water). Maintenance is also easier, because its open nature offers easy visual inspection of the water flow pattern and the condition of the fill.
Film fill provides sheets of material that are shaped into a corrugated pattern for the water to travel across. It can be combined and stacked into blocks, to create various thicknesses and heights to fit individual cooling towers.
Despite the advantage of splash fill in water distribution, film fill is by far the more popular type of fill, mainly due to its ability to expose greater water surface within a given packed volume. How much more popular is film fill? About half of the fill used in crossflow cooling towers, and nearly all of the fill used in counterflow cooling towers, is film.
The largest disadvantage of film fill is that it doesn’t provide an opportunity for the water to redistribute itself. The initial water distribution at the top of the fill must be uniform, or the process won’t work well. The close spacing created by the narrow passages of film fill also makes film fill more challenging to maintain. If the water includes large debris like leaves, the fill is prone to clogging.
What If the Water is Excessively Dirty?
Another type of fill should be mentioned. If the water contains excessive debris, bar fill can be used. Bar fill is a variation of splash fill, and it allows much larger debris to pass through. It’s the least effective, and is only recommended for use with very dirty water. But it serves this purpose well.
In need of a cooling tower? Give us a call at 864-249-0943 and we’ll be happy to talk with you.