The Cooling Water Consumption Calculator is a valuable tool for estimating the total water usage in cooling systems, particularly in cooling towers. It calculates water consumption by accounting for evaporation loss, drift loss, and blowdown loss, helping facility managers, engineers, and technicians manage water resources more effectively.
This tool is essential for reducing operational costs, improving water efficiency, and ensuring compliance with environmental regulations.
Formula of Cooling Water Consumption Calculator
The total water consumption in a cooling tower can be calculated using the following formula:
Total Water Consumption = Evaporation Loss + Drift Loss + Blowdown Loss
Detailed Calculation Components
- Evaporation Loss: Evaporation Loss = (0.00085 × Water Flow Rate × Temperature Difference)
- Water Flow Rate: The volume of water circulating through the cooling tower, 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: Water lost as vapor during the cooling process.
- Drift Loss: Drift Loss = Drift Rate × Water Flow Rate
- Drift Rate: A small fraction of water lost as droplets carried with exhaust air, typically 0.001% to 0.005% for modern cooling towers.
- Drift Loss: Water lost due to drift.
- 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 control mineral buildup and maintain water quality.
Pre-Calculated Values Table
Here’s a table showing typical water consumption metrics for different scenarios:
| Water Flow Rate (GPM) | Temp Difference (°F) | CoC | Drift Rate (%) | Evaporation Loss (GPM) | Drift Loss (GPM) | Blowdown Loss (GPM) | Total Water Consumption (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 Water Consumption Calculator
Scenario:
A cooling tower circulates water at a 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 the total water consumption.
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 Consumption:
Total Water Consumption = Evaporation Loss + Drift Loss + Blowdown Loss
Total Water Consumption = 2.55 + 0.004 + 0.85 = 3.404 GPM
Result:
The total water consumption is 3.404 GPM.
Most Common FAQs
Accurately calculating water consumption helps optimize cooling tower operations, reduce costs, and ensure environmental compliance.
Key factors include water flow rate, temperature difference, drift rate, and Cycle of Concentration. Proper maintenance and operation can reduce unnecessary losses.
Improving CoC management, using high-efficiency drift eliminators, and recovering blowdown water for reuse can significantly reduce water consumption.