Steam rising as liquid falls back into the tank filled with servers Allied Control/BitFury
Steam rising as liquid falls back into the tank filled with servers

A Liquid Cooling Renaissance Coming to the Data Center?

With 35-plus years as a full-service mechanical and mission critical environments contractor with a heavy emphasis on service, maintenance, and repair, I specialize in mission critical cooling (heat rejection) and electrical infrastructures, as well as the comfort cooling surrounding them.

As you know, seemingly everything in the world is becoming digitized. A talking appliance that sits on your counter top and does just about anything you ask “her” to do: play music, order pizza, or simply sing to the baby. If you can think of it, it can, has, and will become some form of synthetic and augmented reality. Welcome to the world of “Big Data.”

As part of the heat rejection/cooling industry, we cannot sit idly, watching the world go round; and we aren’t. New, increasingly more powerful technologies dig ever deeper and produce a lot of data — data that must be housed, analyzed, delivered, and stored in some form of a data center. It could be a colocation facility, your on-premises data center, an edge computing node, or a public cloud. Whatever the deployment, we must continue to work hard to understand today’s data center topologies. Air-cooled, water-cooled, or liquid cooled, it is all about heat rejection.

See also: Deep Learning Driving Up Data Center Power Density

Watching the data center cooling market over the last several years, there is currently a push toward liquid cooling that hasn’t been seen before. Why? Because IT rack power densities are growing. Five years ago, 5kw worth of load was a pretty well-loaded rack; today, that’s mid- to low-density. It is difficult for many firms to achieve much north of 10kw with air cooling, mainly because most facilities were not designed such hot components. The natural solution? Use fluid. As we know, fluid is much more efficient in heat-transfer ratios versus air.

Liquid cooling also comes in several forms. For example, it can be used in a rear-door heat exchanger. There are also techniques and designs that mount a heat exchanger onto the CPU, GPU, or FPGA and extract the heat directly from the chip. Some manufacturers do it with Novec 7000, a non-conductive fluid; some manufacturers do it with regular water. These are just additional ways to reject heat without using air. There are also a few solutions that remove heat by submerging servers in a tank of fluid.

Within the last few weeks I have had conversations with three liquid cooling-based companies that have a pipeline full of opportunities. This particular sector of the industry is to better utilize data center space, both in terms of square footage and within each rack. The thought leaders behind this newest wave in testing are in fact finding they can rack and stack at much higher densities than before.

Next up, cryptocurrency perhaps? This too is an ever-increasing portion of the IT community. It will be interesting to see how these players fare down the road. Will the frequent mining hardware refreshes continue? Will we see that sector move to a more liquid-centric mindset?

Liquid-based heat rejection is a mystical to some and appealing to many; but there’s still a lot of “aquaphobia” that must be dealt with. Over the years this phobia has grown and waned, and depending on your particular age and/or time in the IT trenches, you may have observed that dynamic. As a 55-year-old, I saw mainframes sitting around in the data center in the early years. Most of these, especially the big IBM mainframes, were chock-full of chilled water. With the onset of the PC/desktop generation, water and any liquid systems started being perceived as a big n-no. But technology is moving forward, and the younger generation and not overly seasoned IT crowd see the virtues of liquid.

Regardless of your biases, either pro or con on liquid, it is coming in an impactful way. I, for one, am excited to see where we go from here.

Until next time …

AFCOM member Greg Crumpton has 35-plus years as a full service mechanical and mission critical environments contractor with a heavy emphasis on service, maintenance and repair. He specializes in mission critical cooling (heat rejection) and electrical infrastructures, as well as the comfort cooling surrounding them.

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