Rack cooling systems earned plenty of play at the annual CeBIT technology fair held in Hannover, Germany in March. The big cooling vendors paid for plenty of real estate to display their wares, which ranged from vast hot-aisle containment cubes to rack-based supplemental units and a range of refrigerant and water-based systems.
According to Gartner, half of all data centers will need to overhaul their cooling solutions within the next couple of years. At the same time, AFCOM, an Orange, Calif. based association of data center professionals, said the number of professionals qualified to design and run modern data centers will decline by 45 percent. Thus, easy-to-operate and more efficient cooling technology is required.
At CeBIT, APC-MGE of West Kingston, R.I., for example, displayed the latest elements of its InfraStruXure system.
"InfraStruXure is like data center in a box," says APC-MGE general manager of business operations Peter Hannaford. "If you have a big application coming into an existing data center and need new blades, InfraStruXure will cool them efficiently and remain room neutral."
This is achieved in APC-MGE's hot aisle containment cube. Basically, it closes off two racks completely and covers up the hot aisle in one container. The hot aisle containment cube works with a variety of APC coolers.
The latest model, the InfraStruXure InRow RP, places cooling next to the heat source as a vertical unit placed to the side of a rack. It is available in both chilled water and refrigerant-based designs, though the company appears to favor water overall. Instead of constant speed fans, a system of sensors monitors temperature and ramps fan speed up or down and water pressure accordingly. The idea is to reduce operating costs while improving effectiveness. In addition, an integrated humidifier provides room-level moisture control. Hannaford says that the InRow RP is available in chilled water (up to a 70 kW per rack) or refrigerant (up to 37 kW).
The InRow RC units, on the other hand, are water only. If contained, a unit provides 20 kW (up to 7 kW if uncontained). The unit has no humidity controls.
"Most of our sales over the past year or so have been hot-aisle containment cubes due to their ability to address high densities while keeping cooling costs down," says Hannaford. "They are also popular because there is no need for a raised floor."
The Rittal Company That Cooled
Rittal of Herborn, Germany, is known primarily as a rack manufacturer. Rittal sells both directly to end users and big-name OEMs that include HP, IBM, Dell and NetApp, which then rebrand them. Recently, Rittal introduced chilled water coolers. These are vertical models known as the liquid cooling package (LCP). HP uses a modified version of the LCP and sells it as the HP Modular Cooling System.
The LCP provides up to 20 kW per rack. It can be purchased as a modular system with about 6 kW of cooling per module. Water is normally pumped from underneath the floor. If the end user already has a chiller system, she hooks the system up to it. Otherwise, Rittal offers a chiller unit.
Rittal's LCP Plus pushes the cooling potential up to 40 kW per rack if a 51U system is installed. A standard 42U LCP Plus delivers up to 28 kW.
"We have manufacturing facilities throughout the world, including two in the USA," says Martin Dorrich, a project manager for Climate Control IT at Rittal. "We designed the LCP Plus to make it easy to dismount and replace fans, even while the system is running."
Ich Liebert Dich
When APC-MGE and Rittal are exhibiting, you won't find Liebert, from Columbus, Ohio, far away. The company's booth was placed across the aisle from APC-MGE, and it provided an interesting comparison to the InfraStruXure architecture. While APC-MGE goes for vertical units that sit beside the racks, Liebert prefers to install systems above the racks.
Its XD Adaptive Cooling platform delivers 5 kW to 20 kW per rack. Instead of water, the company uses a refrigerant that is gaseous at room temperature. Thus, there is no worry about water spills. The coolant is pumped in from above. Ceiling-mounted cooling units (XDO) above the hot aisle and rack-mounted units (XDV) can be used as part of this approach. Liebert XD requires a network of copper pipes above the racks to feed in the refrigerant.
"The Liebert XDO overhead unit dissipates the hot air and cuts the cost of cooling," says Stefano Mozzato, marketing director of Liebert. "We also sell XDH in-row units that are placed between racks if you lack the overhead space for the XDO."
The newest Liebert product on display was the XDFN refrigerant-based or chilled-water system that can chill 10 to 30 kW.
"If you want chilled water, you need the infrastructure to support it," says Mozzato. "70 percent of our customers prefer refrigerant."
The concept with the XDFN is a cabinet that encloses several racks and includes built-in cooling. Although it is typically used with overhead piping, under-floor pipes are also an option.
Knurr AG of Lommatzsch, Germany, is another cooling vendor designing units for high-density environments. At the low end of its product range is the 3U CoolServe. It slides right into traditional racks for supplemental in-rack cooling.
"It has an air/water heat exchanger with two power supplies that you just slide into the rack and connect to the chilled water system," says Heiko Ebermann, a product manager for thermal systems at Knurr. "It fits almost any racks."
The company also sells several other models. CoolAdd has a door connected to the rack server with three large fans and a liquid cooling system inside the door. It is designed for up to 8 KW of power in the rack. The Miracel rack delivers 4.5 kWto 7 kW cooling via a vertical unit that sits beside the rack. Finally, Knurr offers CoolTherm, a closed cabinet application (i.e., an integrated rack with cooling included).