Does Liquid Cooling Have a Future in the Data Center?

For most enterprises, the job of updating data environments for the 21st Century involves retrofitting existing infrastructure with low-power virtual- and cloud-ready systems. Economics being what they are, the prospect of a complete do-over in the data center just isn’t in the cards.

At some point, however, deployment of new physical layer infrastructure simply can’t be avoided any longer. And it’s here that enterprise managers are seeing a range of new options governing many long-standing design practices.

In this age of high energy costs and growing environmental awareness, power and cooling have taken on greater urgency. So much so that enterprises are taking a hard look at the tried and true air-cooling methods that have been the mainstay of data center design for the past few decades, the central question being: Is it time to switch over the liquid cooling?

There’s no question that both oil- and water-based coolants are much more efficient than air. As Iceotope’s Richard Barrington points out, liquids are about 4,000 times more effective at capturing and removing heat than air, and they foster even denser room and rack designs within existing footprints. As well, it is much easier to capture and reuse heater water for other purposes such as central heating or even electricity generation. And perhaps best of all for those who spend long hours in the data center, liquid cooling runs a lot quieter than air.

Liquid cooling also makes it easier to take advantage of another recent energy efficiency trend: free cooling. Most instances of free cooling are based on cold, even arctic, weather conditions in which warm internal air is simply exchanged for cold outside air, but this only works if the outside temperature is 45 degrees or less. However, with liquid-cooled chillers like Inertech’s eOPTI-TRAX, free cooling can be effective up to 85 degrees, which would make the practice economical on a year-round basis throughout large swaths of the northern and southern temperate zones.

Indeed, liquid cooling is becoming a viable alternative even for the transformer substations that power some of the larger facilities, according to Consulting-Specifying Engineer Magazine’s Joe Guentert. Air-cooled substations have a long history of failure due to switch-induced transient voltage spikes. Liquid systems are proving much more reliable, and new hardened data center (HDC) designs are making it possible to locate the substation within the data center itself, eliminating overloads and secondary faults with new voltage suppression technology. Efficiencies are coming in at about 99.4 percent at peak load, and again, they run so quietly they can’t be heard above the ambient noise of a typical data center.

As for data equipment itself, the idea of full liquid immersion is quickly moving from the crackpot file into the definite-maybe category. None other than Intel has just finished up a year-long study of a mineral oil-based immersion coolant from Green Revolution and found that its servers maintained nearly a 1.0 PUE rating for the duration without any appreciable damage to the hardware. The company is still crunching numbers to determine if widescale deployment of the system is feasible, but if it pans out there is a strong chance that Intel could be a leading force in pushing the technology to the broader market.

The typical knee-jerk reaction to placing liquid of any kind in close proximity, let alone inside, sophisticated electronics is to shudder uncontrollably and then laugh hysterically at the very notion. However, the advanced dielectrics available today have made liquid-cooling technology practically idiot-proof, although it’s never wise to underestimate the ingenuity of idiots.

Nevertheless, liquid cooling is proving to be both reliable and highly efficient, which should be enough to at least warrant strong consideration as enterprises struggle to maintain control of energy consumption.