Energy
Cooling Tower Efficiency Calculator
Calculate cooling tower effectiveness, range, approach and heat rejection from water and wet-bulb temperatures.
Use ambient entering-air wet-bulb temperature at the tower.
Optional. Enter flow if you also want estimated heat rejection.
Tower Effectiveness
—
Actual cooling range relative to the maximum temperature reduction theoretically available from the entering wet-bulb condition.
Tower effectiveness
—
Cooling range
—
Approach
—
Hot water temperature
—
Cold water temperature
—
Wet-bulb temperature
—
Heat rejection
—
Heat rejection
—
Method:
Cooling tower range is:
Range =
Hot Water Temperature −
Cold Water Temperature
Cooling tower approach is:
Approach =
Cold Water Temperature −
Wet-Bulb Temperature
Tower effectiveness is:
Effectiveness =
Range ÷
(Range + Approach) × 100
which is equivalent to:
Effectiveness =
(Hot Water Temperature − Cold Water Temperature) ÷
(Hot Water Temperature − Wet-Bulb Temperature)
× 100
If circulating-water flow is entered, heat rejection is estimated from:
Q =
ṁ × cp × ΔT
using water density of approximately 1,000 kg/m³ and specific heat capacity of approximately 4.186 kJ/kg·K.
The calculated percentage is commonly referred to as cooling tower efficiency, but technically it represents tower effectiveness based on the entered water temperatures and ambient wet-bulb temperature.
Actual tower performance is also affected by air flow, water distribution, fill condition, recirculation, wind, fan performance, fouling, drift, tower design and measurement location.