Temperature Measurement · Free Calculator
Cooling Water Flow Calculator
Size the cooling water for a heat exchanger, motor or process, or work out the heat being removed from a measured flow and temperature difference.
Heat loadWater flowTemperature riseQ = ṁ cp ΔT
kW
K
kJ/(kg·K)
Water flow10.8 m³/h
Water flow180.1 L/min
Mass flow10,750 kg/h
How this result was calculated
- ṁ = P ÷ (cp × ΔT) = 100 ÷ (4.186 × 8) = 2.986 kg/s
- Q = ṁ ÷ ρ = 10.8 m³/h
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Cooling Water Formula
ṁ = P ÷ (cp × ΔT) P = ṁ × cp × ΔT
Worked example
Removing 100 kW with an 8 K water temperature rise needs 100 ÷ (4.186 × 8) = 2.99 kg/s = 10.8 m³/h.
Key insight: halving the allowed temperature rise doubles the water flow. Check the return water temperature limit of your cooling tower or chiller before choosing ΔT.
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Frequently Asked Questions
How do I calculate cooling water flow?
Divide the heat load by specific heat times temperature rise to get mass flow, then by density for volume flow.
What temperature rise is typical?
Cooling tower circuits often use 5 to 10 K; chilled water systems commonly 5 to 6 K.
How do I measure heat removed in the field?
Measure water flow and inlet and outlet temperatures; a BTU (energy) meter does this automatically.
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