What’s hot in data center cooling?
You might be surprised to hear that evaporative cooling is, indeed, catching on, at least in some data center scenarios.
Data center wholesaler Server Farm Realty of El Segundo, Calif., is breaking from tradition and implementing direct/indirect evaporative cooling for a facility under development.
The new 26,900-square-foot facility in Santa Clara, Calif., will have no computer room air conditioning (CRAC) units on the floor, relying instead on evaporative cooling systems from San Diego-based Energy Labs.
With evaporative cooling, air is cooled by blowing a fan over water. Traditional air conditioning systems, in contrast, rely on vapor compression to circulate a liquid refrigerant, which absorbs heat and subsequently directs it elsewhere.
Evaporative cooling systems tend to use much less energy than traditional air conditioning. Compared with traditional mechanical cooling, “the amount of water used [by evaporative cooling systems] is insignificant compared to the amount of electricity that is saved -- even in places like California where the water costs are high,” said Bob McFarlane, data center design principal at Shen Milsom & Wilke LLC, a consulting firm in New York City.
There are other benefits in the data center, said Avner Papouchado, CEO of Server Farm Realty. Because the water evaporates, there’s no need to store it in traditional chiller systems, which in large facilities can hold as much as 200,000 gallons, he said. And because each unit is a standalone system, evaporative cooling does not require extensive piping and air-handlers. Papouchado said that going with evaporative cooling will free up 10% more rentable space in the Santa Clara facility.
Of course, evaporative cooling isn’t for everyone. It assumes a reliable, plentiful water supply. And because it injects humidity into the atmosphere, it works best in hot, arid climates.
And, when it comes to data centers, evaporative cooling units need to be close to the building’s air-handling unit. “It’s hard to do evaporative cooling in high-rise buildings, or if you can’t stand the air-handling units very close to your servers,” said Papouchado.
As such, evaporative cooling is still used very rarely in today’s data centers, said McFarlane. “If you’re in a dry, warm climate, it works beautifully,” but the number of data centers locations that fit that description are few and far between. That could change as vendors start delivering hybrid cooling systems that incorporate evaporative cooling in conjunction with another cooling method, he said.
APC, for example, announced its EcoBreeze hybrid cooling system in November. It combines air-side free cooling and indirect evaporative cooling, as well as a compressor when neither of the other cooling techniques are appropriate. The unit includes sensors and automatically switches between the cooling systems depending on conditions.
“I think we’ll start to see more evaporative cooling systems,” McFarlane said. “Just not as the be-all and end-all.”