Beating the Heat: The Advantages of Liquid Cooling in Data Centres

Data centre operators are quickly learning the detrimental effects of increasing temperatures on their facilities. As the mission to maintain ambient temperatures for increasing IT workloads and ever-growing rack densities in data centres grows, the transition to new methods such as liquid cooling increases.

More and more, data centres are consolidating increasing workloads and process-intensive applications, into smaller but more powerful facilities. Cooling techniques that use water and other liquids are far more efficient at transferring heat than methods that use air.

According to GMI Insights , the data centre liquid cooling market is estimated to reach $3 billion by 2026.

As digital infrastructure providers increase output, they’re also increasing the power used and therefore the amount of heat produced. The change in rack power requirements is causing problems within the industry because data centre operators must maintain safe temperatures within facilities.

Previously, air cooling techniques were able to manage rack power demands of 18Kw or below. However, as hyperscalers, enterprises, cloud and content companies, and OTT players are turning up in new markets with unprecedented levels of data, air cooling is unable to take the heat. Traditional cooling techniques are now looking at chilling 20-30kW per rack, which is unmaintainable and inefficient.

So, as data centre operators begin to consider liquid cooling more seriously, how will it affect the design, safety, and overall efficiency in years to come?

Liquid Cooling Methods

Liquid cooling has a strong selling point as it promises to ensure ambient temperatures are maintained even when computing densities are at an all-time high. There are three types of liquid cooling emerging in the data centre space:?

·??????Direct-to-Chip Cooling

This method directly integrates the cooling system into the computer's framework. Cold liquid is piped to cold plates that sit next to key components of the computer.

Small tubes carry the cool liquid to each plate, where the liquid draws off the heat from the underlying components. The warm liquid is then circulated to a cooling device or heat exchange. After it's been cooled, the liquid is circulated back to the cold plates and the process repeats.?

·??????Rear-Door Heat Exchangers

Exchangers are mounted onto the back of the rack in places of a back door. Server fans blow the warm air through the exchanger, which dissipates the heat. Liquid is circulated through a?closed-loop system?that carries out the heat transfer.??

The rear-door cooling approach typically includes a contained coolant that runs through the exchanger and a system for lowering the coolant temperature as it circulates, although this process varies from system to system.

·??????Immersion Cooling

Immersion cooling is the newest of the emerging cooling technologies - all internal server components are submerged in a nonconductive dielectric fluid that is encased in a sealed container to prevent leaks.

The heat from the components is transferred to the coolant, a process that requires far less energy than other approaches. Immersion cooling can be single- or two-phase.

?With?single-phase cooling, the coolant is continuously circulated and cooled to dissipate the heat.

In a two-phase system, a coolant with a low boiling point is used. When the coolant boils, it turns to vapour and rises to the container lid, where it's cooled and condensed back to liquid.

With a variety of methods to choose from that are proven to be far more efficient than air cooling, it is unsurprising that data centre operators are widening their horizons when looking at cooling techniques.?

Chilled Facilities

A key differentiator for data centre operators is ensuring they’re consistently reliable and always performing. Otherwise, hyperscalers, enterprises, cloud and content companies, and OTT players will choose a different provider for their data storage needs.?

Liquid cooling allows facilities to increase performance more consistently because racks can be cooled down quickly if temperatures begin to rise. This ensures the entire facility is reliable for customers at all times.

The move to liquid cooling is also supportive of the ‘go-green’ initiative because it reduces the need for air conditioning which produces carbon emissions. It can accommodate denser workloads more easily while minimising the facility's footprint. Surprisingly, liquid cooling uses less water than air cooling, resulting in lower OPEX and overall, a more sustainable data centre.

Liquid cooling also allows for existing data centre space to be used more effectively without the need for expansion or further construction. The technique is future-proofing facilities for the surging temperatures that climate change is bringing and preparing data centres for the long-term.

Long-Term Success

?If data centre operators can move past the risk of bringing liquid into close proximity of high-tech racks, there is a real opportunity for long-term progression. While some data centres may not need liquid cooling right now, it is important for operators to consider the future of their facilities.

Power demand will only grow throughout the coming years as digital transformation continues to thrive. They will also need to increasingly utilise more floor space to accommodate the new levels of data hyperscalers, enterprises, cloud and content companies, and OTT players are bringing.

On top of this, as data centres are forced to become more sustainable and as carbon neutral as possible, liquid cooling may become the only feasible option for keeping facilities at an ambient temperature.