1. Cooling Towers: These open-loop systems dissipate heat by circulating water over a "fill" area. Fans promote evaporation, which cools the remaining water. However, cooling towers often suffer from contamination, leading to issues like fouling and corrosion.
2. Closed-Loop Systems: In contrast to cooling towers, closed-loop systems (dry, evaporative, and liquid-to-liquid) do not expose the coolant to external contaminants, preserving its quality.
3. Types of Closed-Loop Systems:
o Air-Cooled (Dry): Utilizes radiators, similar to car cooling systems, where no water is consumed. It’s best for equipment tolerating higher coolant temperatures.
o Evaporative: A closed-circuit cooler that relies on evaporation without coolant exposure to the environment. These systems do consume water, which requires periodic maintenance.
o Liquid-to-Liquid: Uses heat exchangers to transfer heat between fluids. This system allows for stable temperature control and is suitable where contamination is possible.
o Chiller: A chilled water system is similar to the Liquid-to-Liquid package, however it also includes a refrigeration circuit designed achieve cooling to 60 ˚F or lower.
4. Coolant Choices: Glycol-water mixtures are common, with ethylene glycol often preferred for its heat transfer efficiency, although propylene glycol is a less toxic alternative. Correct glycol concentration is critical for system performance and freeze protection.
It is important to understand that closed-loop systems reduce maintenance costs, increase equipment reliability, and allow for more precise temperature control.
