University of Waterloo researchers develop hybrid liquid cooling for AI data centres

Researchers at the University of Waterloo are developing a new way to keep computer chips from overheating, using tiny drops of boiling liquid to target particularly hot areas.

The research comes amid growing demand for artificial intelligence, putting more pressure on the massive data centres that power the technology. Those facilities house thousands of computers to process information, which generates a significant amount of heat. If certain areas of a computer chip become too hot, it can affect performance and reliability.

How the system works

The technology uses water to manage everyday heat, while tiny drops of a specialized coolant target areas that become particularly hot. The researchers selected an electronics coolant with a much lower boiling point than water. The coolant is also heavier than water, so it does not mix with it and stays put when placed on a hotspot.

Researchers used an encapsulation technique to wrap coolant drops in a thin skin of silicone oil. Adding tiny, heat-conducting ceramic particles to the coating helps control how quickly the drops boil.

In laboratory testing, a single drop of coolant boiled and reduced the temperature of a simulated computer chip hotspot submerged in a tank of water by up to 17° C in 15 seconds, several times faster than conventional immersion.

"Boiling soaks up a lot of heat and the rising bubbles stir the surrounding water so it carries heat away faster," said Dr. Sushanta Mitra, executive director of the Waterloo Institute for Nanotechnology. "We get the punch of boiling, but only where and when it's needed."

Cost and next steps

Current immersion cooling systems require more of the specialized coolant, while the University of Waterloo method requires much smaller amounts.

"You don't need to use that expensive coolant across the entire loop," Mitra explained. "You only need to use this at the drop."

The drops are only about one to two millimetres in size, meaning the amount of specialized coolant used is significantly reduced.

The research is still in its early stages, with testing focused on a single computer chip. The next step is to develop a larger system that mimics how the coolant would circulate through a data centre.

The team hopes the technology could eventually be adopted by data centres around the world, as well as other applications involving electronics that generate significant amounts of heat. Researchers envision the system ultimately working in one of two ways – either coolant drops that circulate through water and activate when they hit hotspots, or drops that are delivered directly to hotspots detected by sensors.

The hybrid cooling approach also has potential applications in technologies including electric vehicles, batteries, high-powered lasers and LED lighting.

The study, A hybrid immersion cooling assisted by liquid-liquid encapsulation: A game changer for thermal management of transient hotspots, was recently published online in the Journal of Colloid and Interface Science.

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Sources

• ctvnews.ca: University of Waterloo researchers develop new way to cool AI computer chips
• uwaterloo.ca: Waterloo innovation could make cooling AI data centres cheaper and more efficient | Waterloo News | University of Waterloo

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