It is a common misconception that liquid cooling technologies are somewhat ‘futuristic’. Something that we can anticipate to come into common practice soon, that will help reduce data center emissions.
But the reality is that liquid cooling is nothing new. It has been around for decades, we have just forgotten.
John Bean is the Chief Technology Officer for Green Revolution Cooling (GRC) and is close to celebrating a ruby anniversary with liquid cooling technologies.
“Back in the 80s, we knew that liquid cooling existed then. We had the big IBM mainframes, the 3090 was one of the more prevalent models at the time, and that was a liquid-cooled mainframe.
“We developed precision chillers to keep their high heat electronics, primarily their processing units, cool enough. Back then it was still bipolar technology, but the bipolar matured to the point where they were beginning to push heat fluxes up quite substantially.
“The technology of today isn't, in terms of liquid cooling, what we saw deployed back in the 80s and early 90s. Back in those days, we had a fairly complicated thermal path from the CPUs to the outdoors, with many steps of handoff from heat.
“Even the mainframes themselves had coolant distribution units within them that had a heat exchanger, a pumping network, and then it would go to a chiller that had a vapor compression cycle, a couple of heat exchangers, and then it would go to the outdoors. These were fairly complicated and consumed an awful lot of power.”
So while liquid cooling technologies were in use, they were not necessarily the representation of green cooling methods at the time. They were complicated, and costly, and used a lot of energy to keep running effectively. As demand increased and therefore so did the temperature of the technology, a new approach had to be developed.
This development has taken different routes, including cold plate, two-phase and single-phase, and other significant changes.
“Another key thing is that some of the liquid cooling technologies were penetrating into the IT equipment with water, which is conductive. So one of the things that you're seeing today is a lot of the fluids that are used in immersion are dielectric fluids so that they don't conduct electricity very well.
“So you can sleep well, knowing that if there is an inadvertent wetting of the electronics, with these fluids they were designed to do that now. That's positioning it as well to have the scalability too, because these things can be like cookie cutters. There is not quite as much specialized knowledge needed to tweak them and get them to work.”
Liquid cooling still isn’t universal. But it is becoming increasingly popular, and likely to continue to do so.
“Within the next five to ten years, we will see broader adoption of liquid cooling. I believe immersion will be the primary player, and there are a couple of things that will help facilitate that. I think you will see more and more IT vendors getting out-of-the-box immersion cooling ready so that there is not necessarily the need to do these changes in the field.
“In the short term, these changes will be simpler, better defined, and with clear expectations of how they will work. But ultimately, we will see more and more stuff coming out ready to be immersed, and that's going to serve the industry.”