Enter Cooling Tower Inputs
The form uses a responsive input grid: three columns on large screens, two on smaller screens, and one on mobile devices.
Plotly Graph
This chart compares the tower temperature profile and water loss components from the current result set.
Example Data Table
| Case | Hot Inlet (°C) | Cold Outlet (°C) | Wet Bulb (°C) | Flow (m³/h) | Cycles | Range (°C) | Approach (°C) | Heat Rejected (kW) | Makeup (m³/h) |
|---|---|---|---|---|---|---|---|---|---|
| Sample Plant Loop | 37 | 29 | 24 | 450 | 4 | 8 | 5 | 4170.84 | 6.13 |
| Higher Load Day | 40 | 30 | 25 | 520 | 5 | 10 | 5 | 6029.68 | 8.06 |
Example values are illustrative engineering estimates for screening and comparison only.
Formula Used
Range = Hot Water Inlet Temperature − Cold Water Outlet Temperature
Approach = Cold Water Outlet Temperature − Wet Bulb Temperature
Effectiveness (%) = Range ÷ (Hot Water Inlet Temperature − Wet Bulb Temperature) × 100
Mass Flow (kg/s) = Flow Rate (m³/h) × Density ÷ 3600
Heat Rejected (kW) = Mass Flow (kg/s) × Specific Heat (kJ/kg·K) × Range (°C)
Evaporation (m³/h) = 0.00153 × Circulating Flow (m³/h) × Range (°C)
Drift (m³/h) = Circulating Flow × Drift Percentage ÷ 100
Blowdown (m³/h) = [Evaporation ÷ (Cycles − 1)] − Drift
Makeup (m³/h) = Evaporation + Drift + Blowdown
These equations are standard engineering approximations for screening tower performance, water balance, and operating trends. Final design should still be checked against site data, water chemistry limits, and manufacturer curves.
How to Use This Calculator
- Enter the hot water inlet temperature from the process return line.
- Enter the expected cold water outlet temperature leaving the tower.
- Provide the ambient wet bulb temperature for the design condition.
- Add circulating water flow, cycles of concentration, and drift rate.
- Keep density and specific heat at default values unless fluid properties differ.
- Optionally enter fan power and daily operating hours for deeper utility estimates.
- Press the calculate button to show results above the form.
- Use the CSV and PDF buttons to export the calculated summary.
Frequently Asked Questions
1. What does cooling tower range mean?
Range is the temperature drop across the tower. It equals hot water inlet temperature minus cold water outlet temperature. A larger range generally means more heat is removed from the circulating water.
2. What is approach in a cooling tower?
Approach is the difference between cold water outlet temperature and wet bulb temperature. A smaller approach indicates better thermal performance, but it usually requires more tower capacity or higher operating energy.
3. Why is wet bulb temperature used instead of dry bulb?
Wet bulb better represents the lowest practical temperature the tower can approach through evaporative cooling. Dry bulb matters for weather conditions, but wet bulb is the key thermal reference for tower performance.
4. What does cycles of concentration affect?
Cycles of concentration control blowdown volume and makeup water demand. Higher cycles reduce blowdown, but they may increase scaling or corrosion risk if water treatment is not properly managed.
5. Is the evaporation formula exact?
No. It is a practical estimate used for quick engineering calculations. Actual evaporation depends on site conditions, airflow, tower design, and operating load. Detailed design should use verified manufacturer or operating data.
6. Why can blowdown become very small?
Blowdown drops when cycles rise because the system tolerates higher dissolved solids before purging water. Very small blowdown should still be checked against chemistry targets and control settings.
7. What is fan specific performance?
Fan specific performance shows how many refrigeration tons are rejected per kilowatt of fan power. It helps compare operating efficiency between cases or estimate whether airflow energy is reasonable.
8. Can this calculator be used for final equipment selection?
It is best for preliminary screening, training, and operating comparisons. Final equipment selection should include vendor rating curves, local climate data, water quality limits, and process safety margins.