Immersion cooling in the rack

Data centers are energy-intensive operations and the majority still rely on electricity generated from fossil fuels to power their hardware and cooling systems. One of the primary concerns for data centres is maintaining an optimal temperature inside to avoid overheating. As global temperatures as well as density and the overall number of high-end GPUs and CPUs inside the data centre increase, cooling systems must work harder to maintain a stable environment. Data centres currently account for 1% to 3% of global electricity consumption, and as data volumes as well as the demand for digital services increases, the International Energy Agency (IEA) projects that data centre energy usage could account for 3% to 8% of global electricity demand by 2030. The expanding demand for digital services contributes to greenhouse gas emissions and directly impacts any data centre’s carbon footprint, amplifying the climate challenges our planet is already facing.

Reducing the energy demand for the Information and Communication Technology (ICT) sector, including data centres, is an important step in achieving the Energy Efficiency Directive of the EU.

Efficient solution for modern data centres?

Immersion cooling emerges as a compelling answer to the question of modern data center infrastructure cooling following simple physics: to transport heat, liquids are significantly more effective than air which saves a huge amount of energy.

While immersion cooling solutions were considered novel just a few years ago, by the end of the 1960’s one of the world’s largest computer innovators at the time, IBM, was the first to develop a hybrid air-to-water solution to cool the energy-hungry and ‘hot’ inside the server with heat exchangers. Not earlier than in the 1990’s it was supercomputer manufacturer CRAY that started using immersive technology for their supercomputers.

Challenges

Today, complete servers are immersed in a dielectric, electrically non-conductive fluid and the heat is absorbed by the fluid which allows to switch off the fans or build servers with no fans at all. Although this technology is proven and very energy efficient, many data centre providers still struggle with the idea of putting electronic components into the fluid. The biggest challenges are:

• Fluid leakage and disposal
• Maintenance, inspection, and repair
• Space and weight constraints

Rack mountable immersion cooling chassis for data centers

A very effective way to overcome these challenges is the flexible rack mountable immersion cooling solution from our partner iXora based in Ede, The Netherlands. Instead of big open tanks, iXora designed easy-to-install cassettes that fit in a standard 19” rack and can be individually removed. Each closed cassette holds up to 4kW in compute power and has a convenient handle for carrying them away from the data floor.

Additionally, by isolating the devices, they can be managed individually, just like regular servers. All current workflows can remain more or less unchanged and the existing 19” racks can continue to be used. Maintenance, inspection, or repair can now be performed anywhere and without spilling liquids where they’re not wanted.

The liquid used in the iXora solution starts flowing upwards when getting hot and flows over the vertically mounted electronic components. Once reaching the top it flows back down through the heat exchanger side where it cools down. The hot and cold sides are separated by an insulation layer to prevent mixing the flow and keep the hot part flowing effectively, just like a chimney, and without any pumps or other moving parts that require energy.