What Are the Approach and Range in a Cooling Tower?
The approach in a cooling tower is defined as the difference between the temperature of the cooled water leaving the tower and the ambient wet-bulb temperature. The lower this value, the higher the thermal efficiency of the tower, as it approaches its theoretical performance limit. On the other hand, the range corresponds to the difference between the temperature of the hot water entering the tower and the temperature of the cooled water returning to the process.
There are several factors that can affect the effectiveness of a cooling tower and increase its energy consumption. Poor water distribution over the fill media reduces the effective heat transfer surface, forcing pumps and fans to work harder to maintain the required conditions. The accumulation of sludge, dirt, and debris in the fill or distribution nozzles also interferes with both water and air flow, significantly reducing cooling capacity.
Another critical issue involves unbalanced or poorly calibrated fans, which create irregular airflow, limiting evaporation and heat exchange. Regular adjustments and maintenance help recover much of the lost efficiency. Similarly, clogged or worn water nozzles can lead to areas without proper coverage, affecting cooling performance in specific zones.
The surroundings and location of the cooling tower directly impact its performance. Installing it near structures, walls, or poorly ventilated areas encourages hot air recirculation, raising the inlet air temperature and decreasing cooling capacity. Avoiding recirculation through proper design and correct positioning of air inlets and outlets is essential to ensure optimal performance.
Benefits of Improving Range and Approach in a Cooling Tower
Optimizing these parameters has a direct impact on:
Reduction in Energy Consumption
By decreasing the load on pumps and fans, energy savings of 10% to 30% can be achieved in the tower’s operation.
Increased Cooling Capacity
Improving the range and lowering the approach allows more heat to be removed using the existing infrastructure.
Extended Equipment Lifespan
By reducing mechanical strain, wear on pumps, motors, and fans is minimized, extending their operational life.
Lower Maintenance Costs
An optimized tower operates more stably, requires fewer interventions, and reduces the frequency of cleanings and repairs.
Improved Sustainability and Lower Emissions
Lower energy consumption results in reduced indirect CO₂ emissions, supporting the plant’s sustainability goals.
Operational Stability
Maintaining more stable process temperatures enhances the performance of industrial systems and improves the quality of the final product.
Strategies to Improve Cooling Tower Efficiency
To achieve these benefits, it is recommended to:
Perform preventive maintenance and regular cleanings.
Install variable frequency drives (VFDs) on fans to adjust their speed according to temperature.
Check and optimize water distribution over the fill media.
Regularly inspect distribution nozzles and the condition of the fill.
Minimize air recirculation through proper design of the tower’s surroundings.
