From fresh air cooling to fully submersed IT equipment, the way data centres are cooled has changed and it is set to be revamped once more in the near future.
The data centre cooling market is predicted to grow from $6.26 billion in 2015 to $11.85 billion in 2020, at a CAGR of 13.6%.
Steve Webb, CIO of Ark Data Centres, told CBR: "If you are looking for ways to cool down your data centre, then look with the future in mind. Whichever solution you choose must have the technology to adapt to the ever changing IT power requirements. A rack that today may only need 4 kW of electricity and heat load, tomorrow may need 10+kW.
"With IT upgrades happening every nine months to three years, your cooling solution must be able to keep up with the pace of change that comes with high density computing. To lose sight of this could be a highly costly miscalculation as you will find yourself needing to regularly update your cooling technology to match the pace of change in IT power consumption."
CBR compiles a list of the main topical current cooling trends in the data centre space.
1. Fresh Air Cooling
There are two different types of free cooling systems: direct and indirect. As for the first, the system filters fresh air directly into the building. The indirect way uses a plate heat exchanger, to achieve a fully re-circulating system, according to Keysource.
A direct fresh air approach was found to be more expensive from an initial CAPEX cost perspective, and full mechanical backup is required.
As for indirect fresh cooling, the free cooling and any mechanical systems can be integrated into one system. This will leverage the chances of total chillerless of the data centre and focus can be shifted away from air pollutants and contaminants to external ambient temperatures.
2. Liquid Immersion Cooling
Plunging the whole IT equipment into a water tank seems extreme, but that time has arrived and uses mineral oil instead. Using a submerged solution to cool down infrastructure could cut cooling overhead by up to 95% and reduce server power draw by 10%, according to Green Revolution Cooling.
Immersion cooling works by directly immersing IT equipment into a bath of cooling fluid. Companies can do this over a single phase immersion or two-phase immersion. David Prucnal, Engineer at NSA, explained in a whitepaper that while mineral oil does not have the heat capacity of water, it still holds over 1,000 times more heat than air.
The engineer said this technology can help to do more computation with less energy and infrastructure. One example of this, is that with immersive cooling there is no need for cooling fans to be deployed in the data centre.
Chillers are used in data centres to exchange heat between units. There are three main types of chillers distinguished by their use of water or air to reject heat, according to a Schneider Electric whitepaper.
First, water-cooled chillers reject heat removed from the returning chilled water to a condenser water loop for transport to the outside atmosphere. The condenser water is then cooled using a cooling tower – the final step in rejecting the heat to the outdoors.
Secondly, glycol-cooled chillers (which look identical to water-cooled chillers) reject heat removed from the returning chilled water to a glycol loop for transport to the outside atmosphere. The glycol flows via pipes to an outdoor-mounted device called a dry cooler also known as a fluid cooler
Lastly, air-cooled chillers reject heat removed from the returning chilled water to a device called an air-cooled condenser that is typically integrated with the chiller.
4. Hot and Cold Aisles
A hot and cold aisles approach literally means separating hot and cold aisles with a containment solution, according to AIT.
By adopting such an approach, providers stop hot air recirculating within the data centre from mixing with the cold inlet air. The solution drives energy costs down by using less power consumption offering a more efficient way to manage the hub’s temperature through improved high-volume air conditioning (HVAC).
The company also refers that hot and cold aisles offer a greater deal of security, as doors are required for the system to work, enabling providers to include locks and/or other electronic security systems to get access into the cabin.
5. Evaporative Cooling
Evaporative cooling is an emerging data centre technology, which is set to significantly disrupt the traditional methods of cooling forever, both financially and environmentally, according to Jack Bedell-Pearce, MD at 4D-DC.
This technology draws warm ambient air through a wetted filter or fine mist, which in turn causes some of the water to evaporate and cool the ambient air down. It is the process of spraying water onto a surface or into the airstream, which evaporates and cools the air passing across the surface or spray stream.
The MD added that compared with traditional ‘compressor’ based air conditioning units, evaporative chillers use up to 90% less power.
6. Adiabatic Cooling
An adiabatic cooling system is suitable for hot and dry climates, but it can also be used in locations like the UK, when the weather gets warmer and fresh air cooling solutions need an alternative. The main disadvantage of an adiabatic cooling unit, is the amount of water required for the effective use of the system.
The system works by evaporating water with a corresponding reduction in temperature. The system places a water distributer that keeps pouring over to a water reservoir. Hot air crosses way with the water in an evaporative pad and it is cooled down instantly, according to AIT. The cooled air is then distributed around the data centre via a fan.
Matthew Larbey, Director of Product Strategy at VIRTUS Data Centres, told CBR: "Using advanced indirect ‘air to air’ heat exchange techniques ensures that the external and internal data centre atmospheres are not mixed, safeguarding against contamination and external pollution and ensuring the running efficiencies can be realised irrespective of outside air quality."