After crossing long white corridors elegantly decorated with bluish light projections, the server room of the Leonardo supercomputer in Bologna (Italy), ranked the 4th most powerful in the world, is surprising by the near silence that reigns there. A calm that contrasts with the usual deafening noise of the air conditioning used to cool data centers. Based on fans and chillers, air cooling systems are today the standard in around 98% of infrastructures. Leonardo benefits from a direct liquid cooling system.
On a demonstration cold plate, Nvidia graphics cards (GPUs) and central processing units (CPUs) can be seen, directly connected to cooling pipes. “The cold glycol water comes into contact with the microprocessors which heats it. It then passes back through a heat exchanger which cools the liquid and the system equipment.specifies Nicolas Roger, Equinix technical director for France. A closed loop water circuit, more energy efficient than air cooling.
Investments at Schneider Electric and Vertiv
Today rare, liquid cooling could become widespread in the years to come. Because faced with the development of AI, densified cloud and high performance computing (HPC) needs, current solutions are not the most suitable. “With air cooling systems, we can cool up to 25 kW per rack [sorte d’armoire dans laquelle sont stockées les équipements informatiques, ndlr.] Beyond and up to 50 kW, we use refrigerated doors which are added as close as possible to the servers“, introduces Fabrice Coquio, president of Digital Realty, one of the largest colocation data center operators in the world. However, according to several players in the sector, customers are increasingly demanding densities ranging from 50 to 120 kW per bay.
Model weather forecasts, optimize transport flows, detect cancers, but also develop and deploy conversational robots like ChatGPT…. «New applications developing on a large scale involve turning to liquid cooling, the only one capable of cooling electrical densities greater than 50 kW», Points out François Salomon, director of the refrigeration and air conditioning activity at Schneider Electric.
Integrate liquid cold into the existing system
The latter estimates that the place of AI and supercomputers in data centers will increase from 7% to 20% in the next four years, increasing the capacity of these infrastructures from 54 to 90 gigawatts (GW). As a sign of this development, Schneider Electric will release its first direct liquid cooling range next year. Its main competitor, the American equipment manufacturer Vertiv, for its part bought the English start-up CoolTerra, a specialist in liquid cooling, a year ago. And recruits at all costs for its R&D. Because while liquid cooling techniques are not new, the race is on to make them more efficient.
This includes optimizing liquid cooling consumption. Leonardo, for example, still consumes 6 megawatts (MW), the equivalent of a city of 6,000 inhabitants. The other challenge is to see how to integrate this technology into existing data centers. The move towards water cooling requires the installation of heat exchangers, but also the replacement of servers to allow piping to pass through. More broadly, the endless increase in electrical density ultimately raises the question of the obsolescence of current installations.
France
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