The Cooling Tower Water Loss Calculator helps quantify the amount of water lost in cooling tower operations due to evaporation, drift, and blowdown. By using this calculator, facility managers, engineers, and technicians can optimize water usage, reduce operating costs, and maintain system efficiency.
Cooling towers lose water through three primary mechanisms:
- Evaporation Loss: Water evaporates during the cooling process.
- Drift Loss: Small water droplets are carried away with exhaust air.
- Blowdown Loss: Water is discharged to control mineral concentration.
This calculator combines these factors to estimate total water loss and assist in water management planning.
Formula of Cooling Tower Water Loss Calculator
1. Evaporation Loss
Evaporation Loss = (0.00085 × Water Flow Rate × Temperature Difference)
- Water Flow Rate: The volume of circulating water, typically measured in cubic meters per hour (m³/h) or gallons per minute (GPM).
- Temperature Difference: The difference between the hot water entering and the cold water leaving the cooling tower, measured in °C or °F.
- Evaporation Loss: The amount of water lost due to evaporation, typically in m³/h or GPM.
2. Drift Loss
Drift Loss = Drift Rate × Water Flow Rate
- Drift Rate: The percentage of circulating water lost as droplets, often 0.002% for modern cooling towers.
- Drift Loss: Water lost as droplets carried out with exhaust air.
3. Blowdown Loss
Blowdown Loss = Evaporation Loss / (Cycle of Concentration – 1)
- Cycle of Concentration (CoC): The ratio of dissolved solids in circulating water to those in makeup water.
- Blowdown Loss: Water discharged to maintain water quality.
4. Total Water Loss
Total Water Loss = Evaporation Loss + Drift Loss + Blowdown Loss
Pre-Calculated Values Table
This table provides common water loss values for typical scenarios:
| Water Flow Rate (GPM) | Temp Difference (°F) | CoC | Drift Rate (%) | Evaporation Loss (GPM) | Drift Loss (GPM) | Blowdown Loss (GPM) | Total Water Loss (GPM) |
|---|---|---|---|---|---|---|---|
| 100 | 10 | 3 | 0.002 | 0.85 | 0.002 | 0.425 | 1.277 |
| 200 | 15 | 4 | 0.002 | 2.55 | 0.004 | 0.85 | 3.404 |
| 300 | 20 | 5 | 0.002 | 5.1 | 0.006 | 1.02 | 6.126 |
| 400 | 25 | 6 | 0.002 | 8.5 | 0.008 | 1.417 | 9.925 |
Example of Cooling Tower Water Loss Calculator
Scenario:
A cooling tower operates at a water flow rate of 200 GPM with a temperature difference of 15°F. The drift rate is 0.002%, and the Cycle of Concentration (CoC) is 4. Calculate total water loss.
Step-by-Step Solution:
- Calculate Evaporation Loss:
Evaporation Loss = 0.00085 × Water Flow Rate × Temperature Difference
Evaporation Loss = 0.00085 × 200 × 15 = 2.55 GPM - Calculate Drift Loss:
Drift Loss = Drift Rate × Water Flow Rate
Drift Loss = 0.002% × 200 = 0.004 GPM - Calculate Blowdown Loss:
Blowdown Loss = Evaporation Loss / (CoC – 1)
Blowdown Loss = 2.55 / (4 – 1) = 0.85 GPM - Calculate Total Water Loss:
Total Water Loss = Evaporation Loss + Drift Loss + Blowdown Loss
Total Water Loss = 2.55 + 0.004 + 0.85 = 3.404 GPM
Result:
The total water loss is 3.404 GPM.
Most Common FAQs
Calculating water loss helps manage water consumption, optimize cooling tower operations, and ensure compliance with environmental regulations.
To reduce water loss, maintain proper CoC levels, use drift eliminators, minimize evaporation, and recycle blowdown water where possible.
Yes, the calculator is versatile and applies to most cooling tower types, provided accurate input values are used.