Cooling Water Requirement Calculator

Work out cooling water requirement instantly with clear inputs, formula shown and shareable results.

About Cooling Water Requirement Calculator

Circulating water flow is heat rejected divided by water's specific heat and the allowable temperature rise. A once-through system consumes nothing but discharges warm water; a wet tower evaporates roughly one kilogram per 2300 kilojoules rejected, and blowdown to control dissolved solids adds to make-up demand.

Formulas

Circulation rate

Flow (kg/s) = heat rejected (kW) / (4.18 x temperature rise)

Tower water balance

Evaporation = heat / 2300; blowdown = evaporation / (cycles - 1); make-up = evaporation + blowdown

Worked example

With the default values below, Cooling Water Requirement Calculator returns Circulation Rate of 29,904.3. Change any input above and every figure here is recalculated in your browser.

Inputs used

Heat To Be Rejectedminimum 0 MW thermal: 1,000 MW thermal
Cooling Water Temperature Riseminimum 0 degrees C: 8 degrees C
Cooling Systemone of Once-through, Wet cooling tower, Air-cooled condenser: Once-through
Cycles Of Concentrationminimum 1.01: 4

Results

Circulation Rate: 29,904.3
Make-Up Water Required: 0.000
Evaporation Rate: 0.000
Blowdown Rate: 0.000

Step by step

1Values used
2Circulation rate
3Tower water balance
4Circulation Rate= 29,904.3
5Make-Up Water Required= 0.000
6Evaporation Rate= 0.000
7Blowdown Rate= 0.000

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Cooling water abstraction and thermal discharge are subject to environmental permits, including temperature limits and impingement protection requirements.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Cooling water abstraction and thermal discharge are subject to environmental permits, including temperature limits and impingement protection requirements.

Frequently Asked Questions

Why do cooling towers consume so much water?

Cooling is achieved by evaporating water, so consumption is inherent to the mechanism. A 1000 MW thermal rejection evaporates about 430 kg/s, over 37,000 tonnes a day.

What limits cycles of concentration?

Scaling and corrosion as dissolved solids concentrate. Higher cycles save water but need better chemical treatment and may hit calcium carbonate or silica saturation limits.