The upgrading of a cooling tower’s fill media with components constructed out of robust and non-clogging materials such as polypropylene (PP), polyvinyl chloride (PVC) or stainless steel can lead to cost-effective ways of extending the life of a cooling tower.
According to cooling tower technology company IWC CEO Roger Rusch, fill media are a critical component in the heat transfer process of evaporative cooling systems and act as a medium over which the hot water is distributed as it is being cooled.
“Therefore, fill media’s primary function is to put as much water surface area in contact with as much air for the longest amount of time possible. This also improves the cooling tower’s heat transfer efficiency and reduces its maintenance downtime,” he notes.
When compared to other cooling tower components, Rusch mentions that the fill media are the most susceptible to wear and tear owing to the almost constant exposure to water at high temperatures.
In older cooling towers, fill media were typically constructed out of wood or asbestos cement, which was a disadvantage as wood deteriorates rapidly when compared to modern fill materials such as PP, PVC and stainless steel, he explains.
“We all know the dangers associated with asbestos-containing materials and therefore upgrading a cooling tower’s fill media to these more modern and robust materials can result in significant improvements in heat transfer efficiency.”
Rusch says different types of fill designs are used in cooling tower applications, with the most common being splash and film fill packs. Film packs consist of narrow, closely-placed surfaces over which the hot water spreads, forming a thin coating that comes into contact with air.
“This type of fill media creates a large surface area on which the hot water disperses itself as a thin film that interacts with the air travelling through the tower,” he points out.
In contrast, splash-fill packs are made up of layers of horizontal splash trays into which the water flows, breaking into small droplets. Here, the exchange area for cooling is provided by water droplets and heat exchange occurs on the surface of these droplets.
Rusch adds that film packs constructed out of corrosion-resistant PP or PVC are most commonly used in smaller industrial cooling towers and cooling towers used in heating, ventilating and air-conditioning applications where make-up water quality is good – for instance where the water has low levels of both suspended and dissolved solids.
In cooling tower applications where the recirculating water quality is poor and has high solids content, the non-clogging splash grids or splash tubes are well suited. In high temperature applications where the hot water temperatures exceed 60°C, metallic splash grids such as X- Grids are advisable, he concludes.