Free Cooling Tower Calculator

Estimate the evaporation rate and makeup water requirement for a cooling tower.

L/s
deg C

Evaporation Rate

1.22 m^3/h

Heat Rejected1,672 kW
Blowdown Rate0.41 m^3/h
Total Makeup Water1.63 m^3/h

Evaporation Rate vs Circulation Flow Rate

Cooling Tower Water Balance

Cooling towers reject heat through evaporation, requiring continuous makeup water.

Formulas

Heat rejected = m_dot cp delta_T

Evaporation rate = 0.00085 x Circulation (m^3/h) x Range (deg C)

The 0.00085 factor is an approximation for the fraction evaporated per degree of cooling. Blowdown removes concentrated water to limit mineral buildup: Blowdown = Evaporation / (Cycles - 1)

Makeup = Evaporation + Blowdown

Example Calculation

50 L/s circulation, 8 deg C range, 4 cycles of concentration.

  1. 01Heat rejected = 50 x 4.18 x 8 = 1672 kW
  2. 02Circulation = 50 x 3.6 = 180 m^3/h
  3. 03Evaporation = 180 x 8 x 0.00085 = 1.224 m^3/h
  4. 04Blowdown = 1.224 / (4-1) = 0.408 m^3/h
  5. 05Makeup = 1.224 + 0.408 = 1.632 m^3/h

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