How to do cooling tower tonnage calculation?
Well, please study the following formula and explanation.
The following design data is required for cooling tower tonnage calculations.
- Flow rate in GPM
- Range of cooling in °F (T1-T2) [ Also known as Delta T ]
Cooling tower tonnage calculation
There are two ways to calculate tonnage
- Cooling tower tonnage = GPM/3 (only when the temperature difference is 10 F), otherwise please follow
- Cooling tower tonnage = GPM* Delta T *500 (constant) /15000
Now you may ask, how 500 came? here in formula
Because there are, 8.33 (Pounds in gallon) * 1 (water specific heat) * 60 (mins)
When we run above calculation, we would get 499.8.
Hence 500 = 499.8, used in cooling tower tonnage calculation
How to calculate design heat load of cooling tower?
Heat load (BTU/hr) = GPM X 500 X Range (T1-T2) °F
If the range of cooling or heat load, one of the other factors are known. Then can be calculated using this following formula.
- GPM = Heat load ( BTU/hr) / 500 X Range (T1-T2) °F
- Range of cooling = Heat load ( BTU/hr) / 500 X GPM
Heat load is directly proportional to the range of the cooling tower.
Once you get the heat load of cooling tower, then can easily calculate cooling tower tonnage.
How many BTU per ton of cooling ?
1 ton = 15000 BTU
So, we can use formula like this.
Cooling tower tonnage calculation formula
Cooling tower tonnage = GPM X 500 X Range (T1-T2) °F / 15000
The result is tons of cooling capacity for cooling tower.
500 is a “fluid factor”, it’s based on water as we using water as heat transfer fluid in cooling towers.
The fluid factor is derived by using the weight of a gallon of water, which is 8.33 lbs. then multiply weight of water by specific heat of water, which is 1.To convert it in hr multiply it to 60 ( minutes/ hour)
Fluid factor calculation for cooling capacity
8.33 X 1 X 60 = 499.8
Round figure 500
Hence we use 500 as a fluid factor for cooling tower tonnage calculation. or to calculate the heat load of the cooling tower.
Please also check,