Liquid keeps computer servers cool and quiet

U. LEEDS (UK) — Researchers are testing a liquid-cooled computer server that could reduce energy used for cooling by as much as 97 percent, experts calculate.

While most computers use air to cool their electronics, all of the components in the new server are completely immersed in liquid. The power-hungry fans of traditional computing are replaced by a silent next-generation liquid cooling process that relies on the natural convection of heat.


But the significance of the new Iceotope server lies less in the novelty of its design than in the bite it could take out of the huge electricity demands of the internet servers that form the fabric of our online lives.

Its designers calculate that the server cuts energy consumption for cooling by between 80 percent and 97 percent.

While the information industry enjoys an image of hyper efficiency and environmental friendliness, all Internet use relies on remote servers, which are usually housed in large data centers that must be constantly cooled to remain operational.

The reality is that the mobile apps, networked devices, and 24-hour Internet access on which we have come to rely are very energy hungry.

The UK company Iceotope designed and built its new server working with team of researchers led by Jon Summers from the University of Leeds’ School of Mechanical Engineering. The first production system has now been installed at Leeds after two years of testing prototypes.

Summers, whose team used computational fluid dynamics to model how the coolant flows through the new server’s components, says: “The liquid we are using is extraordinary stuff. You could throw your mobile phone in a tub of it and the phone would work perfectly.

“But the important thing for the future of computing and the Internet is that it is more than 1,000 times more effective at carrying heat than air.

“The cooling of servers is traditionally done using fans and air conditioning units, but air is a great insulator. We use it in double glazing. Why would you use it to cool a server?”

The non-flammable liquid coolant, called 3MTM NovecTM, can be in direct contact with electronics because it does not conduct electricity.

There is no equivalent of the noisy fans required by traditional computers and the server does not require an elaborate pump to move the coolant over its components.

Instead, a simple low energy pump, located at the bottom of the cabinet, pumps a secondary coolant (water) to the top where it cascades down throughout all 48 modules due to gravity.

The secondary coolant terminates at heat exchangers within the cabinet for transfer of heat to a third and final coolant, on an external loop, taking the heat away for external cooling or reuse.

The third coolant can be drawn from “grey water” sources such as rainwater or river water, further reducing the environmental impact of the server. Because of the high cooling efficiency of the system, the output water can reach temperatures of up to 50 degrees Centigrade, which can be used for heating and other uses.

“The fact that this system is completely enclosed raises a host of possibilities. It does not interact with its environment in the way an air-cooled server does, so you could put it in an extreme environment like the desert. It is also completely silent. You could have it on a submarine or in a classroom,” says Nikil Kapur, also from the University of Leeds’ School of Mechanical Engineering.

Source: University of Leeds