A prototype cooling system for supercomputer data centres is expected to save hundreds of millions of gallons of water if widely adopted, say researchers.
In different parts of the country, people discuss gray-water recycling and rainwater capture to minimize the millions of gallons of groundwater required to cool large data centers. But the simple answer in many climates, said Sandia National Laboratories researcher David J. Martinez, is to use liquid refrigerant. Dave Martinez
Based on that principle, Martinez — engineering project lead for Sandia’s infrastructure computing services — is helping design and monitor a cooling system expected to save 4 million to 5 million gallons annually in New Mexico if installed next year at Sandia’s computing center, and hundreds of millions of gallons nationally if the method is widely adopted. It’s now being tested at the National Renewable Energy Laboratory in Colorado, which expects to save a million gallons annually.
The system, built by Johnson Controls and called the Thermosyphon Cooler Hybrid System, cools like a refrigerator without the expense and energy needs of a compressor.
Currently, many data centers use water to remove waste heat from servers. The warmed water is piped to cooling towers, where a separate stream of water is turned to mist and evaporates into the atmosphere. Like sweat evaporating from the body, the process removes heat from the piped water, which returns to chill the installation. But large-scale replenishment of the evaporated water is needed to continue the process. Thus, an increasing amount of water will be needed worldwide to evaporate heat from the growing number of data centers, which themselves are increasing in size as more users put information into the cloud.
“My job is to eventually put cooling towers out of business,” Martinez said.
“Ten years ago, I gave a talk on the then-new approach of using water to directly cool supercomputers. There were 30 people at the start of my lecture and only 10 at the end.
“‘Dave,’ they said, ‘no way water can cool a supercomputer. You need air.’
“So now most data centers use water to cool themselves, but I’m always looking at the future and I see refrigerant cooling coming in for half the data centers in the U.S., north and west of Texas, where the climate will make it work.”
The prototype method uses a liquid refrigerant instead of water to carry away heat. The system works like this: Water heated by the computing center is pumped within a closed system into proximity with another system containing refrigerant. The refrigerant absorbs heat from the water so that the water, now cooled, can circulate to cool again. Meanwhile the heated refrigerant vaporizes and rises in its closed system to exchange heat with the atmosphere. As heat is removed from the refrigerant, it condenses and sinks to absorb more heat, and the cycle repeats.