Enter Cooling Tower Data
Example Data Table
| Case | Flow | Hot Water | Cold Water | Wet Bulb | Cycles | Drift |
|---|---|---|---|---|---|---|
| Process condenser | 500 m³/h | 35 °C | 29 °C | 24 °C | 4 | 0.002% |
| Chilled water plant | 2200 gpm | 95 °F | 85 °F | 78 °F | 5 | 0.001% |
| Small package tower | 80 m³/h | 34 °C | 28 °C | 23 °C | 3.5 | 0.004% |
Formula Used
Range: Hot water temperature − Cold water temperature
Approach: Cold water temperature − Wet bulb temperature
Heat load: Q = m × Cp × Range
Refrigeration tons: TR = Q / 3.5168525
Evaporation loss: Evaporation = Q / Latent heat
Drift loss: Drift = Circulating flow × Drift percent / 100
Blowdown: Blowdown = Evaporation / (Cycles − 1) − Drift
Makeup water: Makeup = Evaporation + Drift + Blowdown
Cooling efficiency: Efficiency = Range / (Hot water temperature − Wet bulb temperature) × 100
Liquid to gas ratio: L/G = Water mass flow / Air mass flow
How to Use This Calculator
Enter the circulating water flow and choose the correct flow unit.
Add hot water, cold water, and wet bulb temperatures.
Select Celsius or Fahrenheit for the temperature inputs.
Keep the default water properties for ordinary cooling water.
Change specific heat, latent heat, or density for special fluids.
Enter cycles of concentration from water treatment records.
Enter drift loss from tower design data.
Add fan power and air mass flow when available.
Press the calculate button to see the result above the form.
Use the CSV and PDF buttons to save the calculated report.
Cooling Tower Formula Guide
Cooling Tower Basics
Cooling tower work starts with three temperatures. Hot water enters the tower. Cold water leaves the basin. Wet bulb temperature describes the lowest practical cooling target. The range is the drop across the tower. The approach is the gap between cold water and wet bulb temperature. A small approach often means a larger tower, cleaner fill, or more airflow.
Heat Rejection
Heat load is based on circulating water flow, water specific heat, and range. This calculator converts the selected flow unit into mass flow. It then estimates heat rejection in kilowatts and refrigeration tons. The value helps engineers compare chillers, condensers, process loops, and seasonal loads. Fan power can also be entered. The tool reports fan energy per unit of heat removed.
Water Losses
Evaporation is the main water loss. The calculator uses heat load divided by latent heat. This is stronger than a rough rule because it responds to real range and fluid data. Drift is treated as a percentage of circulation. Blowdown is estimated from cycles of concentration. Higher cycles reduce blowdown, but scale risk can rise. Makeup water is the sum of evaporation, drift, and blowdown.
Operating Meaning
Range shows how much heat the tower removed. Approach shows how close the tower came to ambient wet bulb conditions. Cooling efficiency relates range to the available cooling span. A high value can be good, yet it must be checked with water quality and tower design limits. Liquid to gas ratio is shown when air mass flow is supplied.
Best Use
Use measured temperatures during steady operation. Avoid data from startup or rapid load changes. Keep units consistent. Check sensor calibration before decisions. Compare several days of results. Look for sudden changes in approach, blowdown, or makeup. These changes can point toward fouled fill, low airflow, poor nozzles, high scaling, or incorrect bleed settings. The calculator is for planning and diagnostics. Final design should use tower manufacturer data and local water chemistry.
Safety Notes
Water treatment matters. Always review corrosion, scaling, biological control, and discharge rules. A clean tower can still waste water if cycles are too low. A stressed tower can overconcentrate minerals if cycles are too high. Balance savings with equipment protection daily.
FAQs
What is cooling tower range?
Range is the hot water temperature minus the cold water temperature. It shows the temperature drop achieved by the tower.
What is cooling tower approach?
Approach is the cold water temperature minus the wet bulb temperature. Lower approach usually means stronger tower performance.
Why is wet bulb temperature used?
Wet bulb temperature represents the practical evaporative cooling limit. A tower cannot normally cool water below this value.
How is heat rejection calculated?
Heat rejection equals water mass flow multiplied by specific heat and range. The calculator reports kilowatts, BTU per hour, and tons.
What are cycles of concentration?
Cycles compare dissolved solids in circulating water to makeup water. Higher cycles reduce blowdown but may increase scaling risk.
What is blowdown loss?
Blowdown is water intentionally discharged to control mineral buildup. It is estimated from evaporation, drift, and cycles of concentration.
What is drift loss?
Drift is water carried out with exhaust air as droplets. It is usually a small percentage of circulating flow.
Can this calculator replace tower design software?
No. It supports planning, checks, and diagnostics. Final design should use manufacturer performance curves and site water data.