If you have a cooling tower, one of the most important factors affecting its performance is the thermal fill material. The fill material is the medium which the cooling tower itself is built around to facilitate heat transfer. Other than the fill, there are nozzles which function in delivering hot water/liquid to the fill for cooling, and so these are just as important to the entire tower's performance. This article describes exactly how this occurs, and what you can do to optimize their function.
Choose nozzle size and location to give uniform distribution
The nozzles' primary task is getting water/liquid to the thermal fill. Thus, their size and location should be engineered so as to allow uniform spraying over the fill without any gaps in areas covered. If the nozzles aren't working properly, the fill will not be wetted at a constant rate, which will reduce the efficiency of the entire system.
Any gaps in fill coverage will cause air (which is supposed to cool the water) to bypass wet fill in favour of dry fill which has a lower resistance. This will result in non-uniform cooling in the fill, promoting scale formation within the thermal fill. Scale build-up in turn lowers thermal capacity of the fill material and can even block airflow through the fill, causing structural damage in the tower if left unchecked.
Choose nozzles that spray smaller droplets
The nozzles' spraying ability also contributes to actual water cooling, and hence the thermal performance of the cooling tower. The very action of spraying into the fill from the nozzle is supposed to reduce water temperature by a small fraction, reducing the amount of work to be done in the rest of the tower.
For effective cooling, the interaction between water and cold air during spraying should be maximized. To ensure this, select nozzles which spray out the smallest possible droplets to increase water surface area that comes into contact with the air around the nozzles, as opposed to nozzles that produce bigger water droplets.
Install mist eliminators to minimize drift emissions
Nozzle spraying ability also plays a role in drift emission from the tower – drift refers to emission of the liquid being cooled into the atmosphere outside the cooling tower. Unfortunately, using nozzles that let out liquid in small droplets makes drift control a lot more difficult, since smaller droplets can be easily carried away from the cooling tower unit in form of drift.
If the water/liquid circulating has low surface tension (such as after water treatment), even smaller droplets can result. These are let out as fine mists that easily escape into the atmosphere, even if you have proper-functioning drift eliminators. Drift eliminators tend to work more efficiently in capturing larger droplets compared with smaller droplets. If you want to use fine-spraying nozzles to maximize thermal efficiency, therefore, you will have to invest in mist eliminators, which are designed to work with mist-like droplets, reducing the tower's drift emission.
For more information, talk to a professional who sells cooling tower spare parts.