Now, it’s not so much a question of “if” as of “how”

Mr. Guth, why are more and more data centres turning to liquid cooling?

Philipp Guth: More high-performance AI applications are leading to ever greater performance density in data centres. From 30 kW per rack, air cooling reaches its limits – but we’re already discussing rack performance levels in excess of 150 kW with our customers. Nvidia GPUs are one example. While air cooling was still predominantly used for the last generation of Nvidia chips, use of liquid cooling is set to increase massively with the Blackwell generation.

In terms of liquid cooling for data centres, what options are available?

Philipp Guth: Currently, the main alternatives are direct liquid cooling (DLC) of the processors – the type of solution Rittal is offering with its new CDU – and immersion cooling. For DLC, a water/polyglycol mix that has already proved successful in industry and the automotive engineering sector is generally used. This mix flows from the distribution unit into the rack and through the heat sinks directly onto the components that generate heat. From there, it carries the heat to the heat exchanger, where it is dissipated. Immersion cooling allows for simpler system designs – but this technology still has disadvantages and needs further development with regard to the substances in which the entire installation is immersed. Our current focus is therefore on DLC with water. The technology can be retrofitted and is closer to the technology that users are accustomed to.

Liquid cooling is often still thought of as unusual, expensive and potentially dangerous. How can these misgivings be addressed?

Philipp Guth: These basic misgivings have quickly given way to an understanding that it’s quite simply a necessity. Now, in discussions with planners and customers, it’s not so much a question of “if” as “how”. And that doesn’t just apply to the actual cooling solution, for which no single design has become established as the standard. This is where most questions arise, and very specific answers are often needed. For example, how does the high performance density affect the power distribution technology? Or how does the pipework in the building need to be designed? When answering these questions, we draw on our many years of experience of data centres as complete systems. We also understand the relevant facility trades, for example, and can arrange these where necessary to provide our customers and partners with the best possible support.