Liquid-Cooled Servers Surface Again in U.K.
Researchers at the University of Leeds this week demonstrated a liquid-cooled server, developed by U.K. company Iceotope, that relies on a non-conductive liquid to route heat away from a server's components. Using the Iceotope technology, servers can eliminate the use of fans and refrigeration, saving cost and also cooling the server much more efficiently than air, which also acts as an insulator. The Inquirer reported that the liquid cooling system uses 80 watts of power to cool clusters that use 20 kilowatts of power—about 97 percent more efficient than fans in terms of cooling, and about 20 percent more efficient in terms of power savings. The university released a video demonstrating the technology in a live server environment, as well as with a small mobile phone and with an iPhone, in order to show that electronics continue to work when immersed in the liquid. 3M crafts the liquid, known as Novec, while Iceotope manufactures the systems that use Novec to exchange the heat: http://www.youtube.com/watch?feature=player_embedded&v=5rCwY4z56nw According to a statement from the university, the Novec pulls the heat away from the microprocessors and other hard drives, then exchanges it with water, via a simple low energy pump located at the bottom of the cabinet, which pumps to the water to the top where it cascades down throughout all 48 modules. The secondary coolant terminates at heat exchangers within the cabinet, transferring heat to a third and final coolant on an external loop, which takes 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, the university said. The video shows the heat being pumped into a conventional radiator, which could be used to warm a typically chilly British room, or for other purposes. Although water passing through pipes in the winter is usually rather cold, the Iceotope system will accept inlet water at temperatures up to 45 degrees Celsius (113 degrees Fahrenheit), and pump it out at temperatures about 50 degrees C (122 degrees F). “The fact that this system is completely enclosed raises a host of possibilities," Nikil Kapur, from the University of Leeds’ School of Mechanical Engineering, wrote in a statement. "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.” Dunking a server in a liquid to cool it isn't new: Intel tried it last year with great success; Facebook did the same, although it used a type of mineral oil to run the servers above 110 degrees Fahrenheit. University of Leeds said it went through two years of testing to nail down the design. (While Facebook and Intel actually immersed their servers inside of a mineral oil bath, the Leeds design uses self-contained modules inside what appears to be a more conventional cabinet.) Dunking servers may entail a host of concerns that data center operators may want answered: does the liquid's thermal properties break down over time? What happens if the pump or tubing fails? How often do they need to be replaced? How easy is it to service or upgrade a server like this? Still, the theory seems sound, and more and more practical demonstrations seem to show that this technology holds potential. Image/Video: University of Leeds