We always come across a common myth / common question —
1. will your cooling tower give this much of delta T?
2. Our cooling tower is not giving right delta T.
To understand more on this, below article will help you understand the functioning of cooling tower in depth.
We have seen amongst users complaining that they are not getting range or allegation that CT is not performing. It is designed for 10°C range & giving only 4°C range.
Let me clarify basic thermal engineering, that cooling tower work as a system. There are two important concepts how they work.
1. CT will not set heat load; it is heat exchanger whatever is the heat gained by water the process will be rejected the air into the atmosphere.
2. All components work as a system.
This can be explained with a revamping example. When the tower gets upgraded or revamped, all other things being same, what happens is the range gets shifted. Let us Say initial range is 10°C i.e. inlet 45°C and outlet 35°C subsequently It gets shifted to 44°C – 34°C or 40°C – 30°C or 42°C – 32°C with same WBT as 28°C. This mean heat load is same, but a good cooling tower improves approach & not the range. It improves absolute value of the cold water temperature.
There will be a variation in wet bulb per season, and hence the how water temperature, cold water temperature will change. The normal curve is approach is lowest at highest WBT and approach is highest at lowest WBT. However the absolute value will always be lowest at any other WBT than design WBT
Hence tower does not set heat load. Heat load is formulized as
Heat Load = Flow Rate x Range x sp heat of water (k)
Hence when the water flow reduces, range increases & vice a versa for constant heat load.
There is theory by which one concludes how tower will operate at off design conditions. If the tower is not working as per design, need a total performance evaluation & than any comment can be made. Incase anyone needs to carry performance evaluation , contact us for availing the services