Issue 7, Dec 09/Jan 10
FOCUS COOLING UPDATE
SYSKA FINDS THAT CRAC-COOLED CABINETS STILL WORK BEST
Research by Morgan Stanley compares conventional cooling to in-row, close-coupled and in-rack fan solutions
About two years ago, Morgan Stanley commissioned the Syska Hennessy Group to investigate the performance of five different equipment racks it was looking at purchasing for a data center.
The group’s associate partner and PE, Vali Sorell, shared the results of the experiment at the Silicon Valley Leadership Group’s Data Center and Energy Efficiency Summit in October 2009.
The test included a fan-assisted cabinet, two cabinets with different water-chilled in- row coolers and two close-coupled cooling solutions. The testers compared these products to a conventional, open four-post cabinet, used in conjunction with a CRAC – all tested at 8.5kW.
To level the playing field, the researchers used the previous set of ASHRAE guidelines for temperature, humidity and maximum temperature change rate (9o
Fahrenheit per
hour). ASHRAE has since expanded the envelope.
Sorell focused on the products’ ability to maintain stable temperatures.
The traditional open cabinet, in conjunction with a CRAC, turned out to be most stable. Without airflow hindrances within the cabinet, temperatures fluctuated by less than two degrees. It was also the most energy- efficient solution.
Second in stability came the in-row cooled cabinets. One of them, however, was more stable than the other, as it did not contain hot air in the rear of the cabinet.
The solution that contained hot air allowed overall temperature to jump up when chilled water was cut off and took a long time to stabilise.
“It puts the hot air right back to the front,” Sorell says. “It had a real hard time trying to maintain some level of stability.”
The fan-assisted cabinet and one of the close- coupled solutions were unable to maintain temperatures stable enough to stay within
EMERSON REVEALS ITS LATEST HEAT EXCHANGER SYSTEM
In early November, global giant Emerson rolled out Liebert XDR – a rear-door heat exchanger system that removes heat from IT equipment racks before it enters the aisle.
The exchanger, mounted on a moveable door, receives hot air from server fans via a cooling coil that uses pumped refrigerant.
Emerson says the refrigerant is seven times more efficient in removing heat than water. Its other advantage over water is reduced danger of equipment damage by water leakage.
The system eliminates the need for fans that move air across the room to wall or floor- mounted cooling systems, as air exiting Liebert XDR has about the same temperature as the air entering the front of the rack, according to Emerson’s director of product marketing, Bob Blough.
The vendor says its system is capable of cooling up to 20kW per rack and is adaptable to hot-aisle/cold-aisle containment designs.
The Network Power segment of Emerson ASHRAE’s maximum change rate.
One of the close-coupled cabinets had fans along the side carriage, and in some cases allowed temperature to change by 10 degrees within two or three minutes. The other close- coupled solution showed variations, but not quite as wide.
The fan-assisted cabinet had a tray of fans at the top. “Despite the constant supply of temperature that we put into the space with the CRAC unit... the cabinet itself was not capable of maintaining uniform temperature from bottom to top. The temperatures were pretty much all over the chart,” says Sorell.
In conclusion, Sorell recommended open cabinets in conjunction with large-scale air handlers for greenfield developments and in- row cooled solutions when there is a need to increase density in an existing facility.
reported sales of $5.4m in fiscal 2009, which the company finished in the end of September. The figure represented a 15% decline from last year’s sales.
In October, Emerson announced an agreement to buy data center monitoring and management solutions provider Avocent for about $1.2bn. The deal is expected to close in January 2010.
A major data center project announced earlier this year will include a rear door-mounted heat exchanger system, but it will not be the Liebert one.
VETTE GOES TO UNIVERSITY
Syracuse University in Syracuse, NY, will deploy a water-based system designed by Portsmouth, New Hampshire-based Vette Corp in its new 6,000 sq ft data center.
The vendor’s LiquiCool Rear Door Heat Exchanger also removes heat from air exhausted by servers before it enters the computer room.
The water will be cooled by double-effect absorption chillers that convert exhaust heat from micro-turbines fuelled by natural gas.
Besides cooling the data center, the micro- turbines will also generate enough power to feed the IT equipment, according to a statement issued by IBM – a partner in the project.
The system will generate enough excess cooling to satisfy the needs of an adjacent building.
The $12.4m data center’s on-site electrical co-generation system is expected to enable the facility to function completely off-grid, while using half the energy consumed by a comparable facility.
The data center is expected to come online by the end of 2009. IBM is working with the private university through its Smarter Planet initiative – a programme through which the company works with public and private sectors to leverage technology, to increase efficiency in healthcare, traffic, energy delivery and other systems.
www.datacenterdynamics.com 49
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