Cooling towers are commonly used when cooling water is scarce, expensive, and a temperature within __________________ of the ambient wet bulb temperature is required.

The requirement for cooling water to be maintained within a specific temperature range of the ambient wet bulb temperature is critical for optimizing the efficiency of cooling towers. When cooling water is scarce or costly, cooling towers provide an effective solution by using evaporative cooling principles.

The correct range of 4°C to 6°C is generally optimal for many industrial and HVAC applications because it allows for sufficient heat removal while minimizing the risk of thermal shock to processes or equipment that rely on cooler water. This range strikes a balance between operational efficiency and achievable cooling performance, ensuring that condensation occurs effectively without excessive water consumption.

Choosing a tighter range, such as 0°C to 1°C, would be impractical in real-world scenarios, as it may not be achievable due to environmental limits. Wider ranges are often less efficient and may not meet the specific cooling needs of certain applications, leading to increased system strain and reduced performance. Thus, the 4°C to 6°C range is the most suitable for conditions where both economic and thermal considerations are paramount.