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Free Cooling from Aermec




Free cooling offers a holistic solution which can not only significantly decrease energy usage on a datacentre wide basis but also measurably reduce C02 emissions. As a technology, free cooling is not new: however, the high efficiency cooling it offers make it particularly worth considering for high demand applications.

The basic principle behind free cooling is the use of the external air temperature to chill water through air/water heat exchangers. Conventional cooling relies on compressors to achieve the required water temperatures for chilling, while free cooling uses the temperature difference between the outside air and the return water from the building to cool the water and return it at a lower temperature.

Decreasing the use of mechanical power by taking the cooling load away from the compressors in this way can deliver energy efficiencies up to 15 times greater than compressor-only chillers.

Historically, free cooling has sometimes been seen as a relatively expensive solution, offering a simple on/off choice which may lead to over capacity and a longer payback period. Modern systems such as the Aermec NRUNSB and Close Control units now deliver greater control and adaptability through automation. In the case of the Aermec system , variable cooling is enabled through a 3-way valve and electronic expansion valve which allows partial use of the compressor when free cooling is not sufficient on its own, typically where the outside air temperature is between 5-16° C. The water temperature inlet probe determines the working mode, while a second water probe determines the cooling capacity required by the chiller.

By enabling the use of free cooling at a higher ambient temperature, this dynamic approach allows the advantages of free cooling to be accessed virtually all year round . In addition, such systems may also include a variable fan speed control which can deliver significant additional savings by regulating the speed of the fan as required rather than running it at full speed as the temperature drops.

Implementing an intelligent water cooled chiller system of this kind effectively enables data centres to change energy consumption from a fixed to a variable cost. Infinitely more flexible, such systems are also by their nature scaleable, enabling them to be adapted to future needs more easily. Additional benefits to be derived from variable control include less wear and tear on compressors, extending plant life while offering protection through constant monitoring against extreme conditions which could otherwise affect equipment resilience.

By limiting the use of compressors in cooler days & evenings and taking advantage of renewable (free) energy sources, annual energy savings of up to 60% can be made, with very short initial payback periods. The result is a boost to organisational green credentials and a visible contribution to bottom line savings -making ‘intelligent’ free cooling well worth a second look.