Data centres, the unsung heroes of a world propelled by AI, cloud computing, and high-performance computing, serve as the invisible glue that holds the digital world together. Like any complex machinery, these digital powerhouses require an optimal operating environment – one that’s decidedly cool. Enter the intricate world of data centre cooling, a crucial element in maintaining the health and efficiency of these computational behemoths.
Liquid cooling infrastructure at a Google data centre. Source: blog.google.com
Data centres have traditionally relied on air-cooled servers to deliver compute power, but the acceleration AI and subsequent boost in thermal design power (TDP) is fuelling a trend toward liquid cooling.
Utilising water or other cooling liquids, liquid cooling can remove significantly more heat compared than traditional air cooling – 23-times, in fact.
Imagine you kept a 40W incandescent lightbulb lit for a few hours and then touched it.
Now, imagine that same scenario but with a 500W lightbulb. That’s what a high-performance CPU will feel like.
Now put that that hot lightbulb in the middle of a small, steel box and blow air across it to cool it. It would only remove a portion of the heat, and it would take a while.
This is what happens if you try to move the heat in a data centre full of high-performance server racks, it will feel like a supersonic wind tunnel.
And even then, it won’t be enough.
Not the same
Liquid cooling offers a way to increase heat rejection by 23 times because of the thermal conductivity of water versus air.
Air has a thermal conductivity of 0.01580Btu/h ft2 °F.
Water has a thermal conductivity of 0.3632 Btu/h ft2 °F.
This means that water will conduct heat 23 times more efficiently than air (23 = 0.3632/0.01580).
Also, it also allows cooling systems to extract heat as close to the generation source as possible.
It is more than just cooling
Liquid cooling also aligns with companies’ sustainability efforts, it provides an avenue to cut down on power consumption, align with ESG goals, and reduce overall carbon footprints.
For example, as a closed-loop system, liquid cooling minimises water consumption, offering a sustainable option without wastage.
This also brings us to the next pertinent point: cost.
When building new data centres, the upfront cost of implementing liquid cooling is comparable to that of traditional cooling systems.
However, retrofitting existing data centres (for liquid cooling) can be more expensive as huge portion of the current infrastructure might need be overhauled.
Not throwing the baby out
That said, organisations don’t have to overhaul their entire data centre to adopt the technology.
Instead, liquid cooling can be implemented selectively for high-performance environments.
This modular approach allows businesses to scale their cooling solutions based on the specific needs of their most compute-intensive applications.
With liquid cooling comes a different skills set.
For example, technicians must be trained to handle liquid immersion, which can involve more complex procedures, such as using cranes to remove servers from cooling oil baths for maintenance.
But despite the above obstacles, the long-term savings and benefits of liquid cooling are clear.
Clear case
In many cases, liquid cooling can significantly reduce operational costs, extend equipment lifespan (by eliminating parts like fans that can fail), and improve overall reliability.
It also leads to a reduction in total energy usage, cooling 20kW of equipment with liquid results in far more heat removal than the same amount of air-cooled equipment.
This translates into smaller data centre footprints, allowing for greater compute density and freeing up valuable floor space for additional operations.
