Free cooling

Free cooling is an economic method of using low external air temperatures to assist in chilling water, which can then be used for industrial process, or air conditioning systems in green data centers.

When the ambient air temperature drops to a set temperature, a modulating valve allows all or part of the chilled water to by-pass an existing chiller and run through the Free Cooling system, which uses less power and uses the lower ambient air temperature to cool the water in the system.

This can be achieved by installing an air blast cooler with any existing chiller or on its own. During low ambients a processor can by-pass an existing chiller giving energy savings of up to 75%, without compromising cooling requirements.

There are four main sources of natural cooling energy

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Wikipedia