Microsoft Corp. revealed today that it has been experimenting with what it calls a “two-phase immersion cooling technology” using a liquid that boils at extremely low temperatures to keep its data centers cool.

The company explained in a post today on its Innovation blog that it has already implemented the technology in production at its Quincy, Washington-based Azure data center.

Today, Microsoft primarily relies on air-based cooling systems in order to keep the temperature of the processors running in its data centers down to a manageable level. But it said liquid-based cooling systems have much more potential as they use less energy. Heat transfer in liquids is “orders of magnitude more efficient than air,” the company said, which means liquid cooling systems are a lot more environmentally friendly.

Microsoft said its two-phase immersion cooling technique is even more efficient than the single-phase cooling technology that Google LLC has implemented at some of its data centers. With single-phase cooling, the fluid is kept in a liquid state, with heat carried away through either natural or forced convection, Microsoft said. As such, single-phase immersion cooling works similarly to air cooling, with the hot fluid transferring heat through a heat exchanger before being circled back into the system.

Microsoft said its two-phase immersion cooling is more passive. When the fluid used in its system comes into contact with heat-generating components inside its data centers, it changes from a liquid into a vapor that naturally rises, carrying the heat away as a latent energy. The vapor ejects the heat through a condenser and then transforms back into a liquid form that can be recycled into the system.

To do this, Microsoft created an engineered solution that won’t damage server systems when they’re immersed in it. The fluid sits in a steel cooling tank has a boiling point of just 122 degrees F, which is around 90 degrees cooler than the boiling point of water. Meanwhile the coils that run through the tank and enable the vapor to condense are hooked up to a separate closed-loop system that uses fluid to transfer heat from the tank to a dry cooler that sits outside.

At present, Microsoft has implemented just one tank and is planning a series of tests to see just how useful the new cooling system will be.

Microsoft said that its tests so far indicate that two-phase liquid immersion cooling can reduce the power consumption of any server by between 5% and 15%. The servers can even be overclocked, or run at elevated power, without any risk of overheating.

“Supercomputing has used this kind of technology for decades, so the risk isn’t really that high,” said Microsoft Distinguished Engineer Christian Belady, who also is vice president of Datacenter Advanced Development. “The goal is for us to deploy this in all our data center regions, but there are a number of steps before we get there.”

There are other benefits besides more efficient heat transfer, Beladay noted. Because the system removes humidity and oxygen from the environment, corrosion declines substantially, leading to fewer mechanical failures in the system. Microsoft first discovered this with Project Natick, which was an experimental undersea data center.

“With immersion, you have a similar thing,” Belady said. “Essentially, you are displacing oxygen and moisture.”

The company is continuing its experiments with other liquid-based cooling technologies too. These include something called “cold-plates” that use tubing filled with a liquid refrigerant. Belady said that while both technologies have potential, he is most excited by two-phase immersion because it is just a onetime cost that needs to be implemented only once, with no engineering required between server generations.

“If done right, two-phase immersion cooling will attain all our cost, reliability and performance requirements simultaneously with essentially a fraction of the energy spend compared to air cooling,” said Ioannis Manousakis, a principal software engineer with Azure.

Analyst Holger Mueller of Constellation Research Inc. said one of the little known secrets of cloud computing is that it requires vast amounts of energy to run, so data center operators must be creative in coming up with ways to reduce that energy usage to be more sustainable.

“Liquid cooling has been around for a while, you can check your car in case you wonder, but expensive electronics and water usually are not best friends,” Mueller said. “So it is quite remarkable that Microsoft has found a way to immerse its servers in a liquid to run them cooler. It means they consume less energy, and with that Microsoft becomes more sustainable.”

Photo: Microsoft