About Plume Abated Cooling Towers:
The cooling tower with plume abatement (also called hybrid or wet/dry) is an evaporative cooling tower combined with a dry heat exchanger, used to abate the cooling tower plume. This is the best available solution where local constraints are such that the presence of plume is not accepted in normal conditions (along motorways, airports, close to residential areas). Plume abatement can be offered with mechanical draft cooling tower (cells) as well as with fan assisted natural draft.
Advantages
- no plume visibility
- outstanding performance of an evaporative cooling tower
- cost attractiveness
- all types of heat exchange media
- for cell CT :
- same flexibility as an induced draft cooling towers
- all types of structure (wood – frp – concrete – steel)
Capacity Control Strategy:
Capacity control of the evaporative cooling equipment has a considerable influence on plume formation.
->No capacity control results in the lowest heat load / air flow ratio and low plume potential.
->Dual drives and two speed motors result in higher heat load / air flow ratio; acceptable plume elimination is
achieved with plume abatement coils.
->Modulating airside capacity control results in highest heat load / air w ratio which gives the highest plume potential.
Plume Abatement Coils:
Large surface area plume abatement coils are installed in the air discharge of the evaporative coil products and piped in series with the “wet” coil. To be effective they must have low air and fluid side pressure drops. This results in:
– Significant extension of dry operation capacity.
– Effective increase of discharge air temperature to reduce / eliminate plume during wet operation.
– Additional sensible heat transfer during wet operation which saves water and treatment costs.
– Plume abatement coil sizing and performance prediction require a thorough evaluation of thermodynamic and airside behaviour as well as an understanding of climate condition influences.
At the air discharge water droplets can be formed by condensation of warm humid discharge air by contact with the colder ambient air upon leaving the equipment. This type of condensation is the visible plume that often can be seen rising above evaporative cooling equipment during the winter season. The water vapour caused by condensation contains droplets of pure water and is harmless. In some instances visible plumes are considered as a hinder, in which case measures must be taken to minimise or eliminate the occurrence of plume.