The dielectric fluid from 3M inside a tank boils 45C to carry heat away from the boards and allow them to operate continuously at full power without risk of failure due to overheating.
Inside the tank, the vapour rising from the boiling fluid contacts a cooled condenser in the tank lid, which causes the vapour to change to liquid and rain back onto the immersed servers, creating a closed loop cooling system.
The immersive cooling coils that run through the tank and enable the vapour to condense are connected to a separate closed loop system that uses fluid to transfer heat from the tank to a dry cooler outside the tank’s container. Because the fluid in these coils is always warmer than the ambient air, there’s no need to spray water to condition the air for evaporative cooling
“We are the first cloud provider that is running two-phase immersion cooling in a production environment,” said Husam Alissa, a principal hardware engineer on Microsoft’s team for datacentre advanced development in Redmond, Washington.
“Air cooling is not enough,” said Christian Belady, distinguished engineer and vice president of Microsoft’s datacentre advanced development group in Redmond. “That’s what’s driving us to immersion cooling, where we can directly boil off the surfaces of the chip. Liquid cooling enables us to go denser, and thus continue the Moore’s Law trend at the datacentre level,” he said.
Liquid immersive cooling is a proven technology from suppliers such as Iceotope in the UK.
Microsoft investigated liquid immersion as a cooling solution for high-performance computing applications such as AI and found two-phase immersion cooling reduced power consumption for any given server by 5 percent to 15 percent.
For example, software that manages cloud resources can allocate sudden spikes in datacentre compute demand to the servers in the liquid cooled tanks. That’s because these servers can run at elevated power via overclocking