The end of the article takes a look at future cooling systems including those that bring water right up to the processor.
For Small Rooms
Closets and small computer rooms under about 500 square feet need cooling just like larger spaces. Yet such gear often gets neglected. According to the Uptime Institute, for every 18 degrees F above 70 degrees, electronics reliability is reduced by 50 percent. It's no wonder closet-based gear can be troublesome.
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Aside from complete neglect, a common mistake in such spaces is letting the building AC system deal with that heat. Bob Spengler, a product manager for Liebert makes the distinction between comfort AC and equipment cooling AC. The former is designed for humans, so it tends to suck all the humidity out of the air. You can't have that with computer room AC, otherwise you end up with the potential for damage due to build-up of static electricity and that can be fatal to servers and networking gear. If the humidity gets too high, on the other hand, the danger comes from condensation on cold surfaces on servers. So look for equipment that provides adequate temperature and humidity control.
For the smallest spaces, the Liebert MCR should be enough. It is a rack enclosure with integrated UPS and enough cooling built into the bottom of the unit that should be enough for whatever you can pack into the rack.
For spaces that require a ceiling-mounted or wall-mounted unit, Liebert has a couple of options. The MiniMate is ceiling mounted and can be bought to cool spaces anywhere from 3.5 kW to 28 kW. Where wall mounting is desired due to a cramped floor and ceiling situation, the DataMate has cooling capacities of 5, 7 or 10.5 kW.
Where floor space is not at a premium, the Liebert Challenger3000 is a floor model with capacities of 10.5 and 17.5 kW. UPS is also built in.
"A Challenger3000 unit can be enough for a small space, or you can use several to cool small server rooms up to 500 square feet," said Spengler.
The final small room product to be mentioned is the XDF. This comes in a couple of configurations. The XDS-S is a self-contained air-cooled unit with 14kW of cooling in a 36U rackable space enclosure. It exhausts the heat from the electronic equipment through the condenser fan at the top. The Liebert XDF-W is a water-cooled unit with 14kW of cooling in a 42U rackable space enclosure. The unit exhausts the heat from the electronic equipment through the water piping circuit connected to an external dry cooler.
Larger Cooling Systems
Moving into the Computer Room AC (CRAC) unit category, the Liebert DS can be used from spaces of a few hundred square feet all the way up to large. The product literature lists it as handling from 28 to 105 kW capacities.
It is flexible enough to be used with air, water or refrigerant.
While CRAC units would be placed around the room's perimeter, Liebert is also big in the area of supplemental cooling. Its XD system comes in several different configurations. This is particularly applicable in high-density environments. These units can be placed above, on or beside the racks, and use water or refrigerant that is piped in from above. This gear can cool up to more than 30 KW per rack.
Fred Rebarber, director of sales and marketing at Cooligy Group at Emerson Network Power provided some insight into cooling systems of the future. He pointed out that server fans alone consume 10 to 15 percent of the power provided to the server room. Eliminate those fans, and you require less power and cooling demands are reduced.
Cooligy's approach is to use what it calls microchannel coil heat exchangers to take heat right off the top of the chips via direct contact cold plates. As well as the chips, this technology can be addressed directly to other hot spots within the server.
Rebarber says this technology will begin to see the light of day next year via the Liebert XDR, which is a rear door product. This unit is attached to the rear door and has heat exchangers that are placed within an accessible door. It will have a capacity from 20 KW to 35 kW and uses a refrigerant that is fed in from above.
The next phase is to put the heat exchange coils in shelves that are placed into the racks (i.e., the heat is removed from the servers from directly above and below). The last leap of faith will be to eliminate the fans from servers all together and replace them with direct component cooling that bleeds the heat off the chips, boards and memory.
"This will be accomplished by bringing the cooling fluid to a heat exchanger interface within the server chassis," said Rebarber. "This technology will be on the market by 2010."