Cooling Tower Efficiency
Reference data and engineering information about cooling tower efficiency for hvac systems applications.
Overview
Engineering reference data for Cooling Tower Efficiency in HVAC systems.
Key Formulas
Sensible Heat
Heat causing temperature change.
Latent Heat
Heat causing moisture change.
COP (Cooling)
Coefficient of performance.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Heat transfer | W | |
| Mass flow rate | kg/s | |
| Specific heat of air | J/(kg·K) | |
| Temperature difference | K |
Types of Cooling Towers
Cooling towers are primarily categorized into two types: forced draught and natural draught. Both rely on evaporative cooling. Forced draught towers utilize fans to circulate air, while natural draught towers depend on temperature gradients and wind forces. Natural draught towers exhibit more variable efficiency over time and are generally less efficient than forced draught systems.
Water Consumption and Make-Up Water
The make-up water requirement for a cooling tower is approximately 0.2–0.3 liters per minute per ton of refrigeration. This represents a significant reduction in water usage compared to traditional city water systems, with potential savings of 90–95%.
Temperature Ranges and Efficiency Limits
The temperature difference between inlet and outlet water, known as the range, is typically 10–15°F (approximately 5.5–8.3°C). The approach is the difference between the cooled water outlet temperature and the entering air wet bulb temperature. For evaporative cooling, the maximum achievable efficiency is inherently limited by the wet bulb temperature of the ambient air.
Safety and Maintenance Note
Cooling towers, due to their medium-temperature operation, can harbor pathogenic bacteria such as those causing Legionnaires' disease. Rigorous cleaning and regular maintenance are essential to mitigate this risk and ensure system safety.