Many data centers are welcoming liquid cooling into their infrastructures to achieve better cooling efficiency. This buyer's guide to liquid cooling in the data center looks at some of the available products. There are a couple different approaches to data center liquid cooling, and finding a product isn't always straightforward. See our liquid cooling product chart for a quick comparison.
Sidecar heat exchangers
Sidecar heat exchange units are enclosures that deliver cooling from the side. The apparatus is side-mounted in order to provide redundancy, which is achieved with a heat-exchanger/servers/heat-exchanger configuration. These are closed systems, meaning that the server environment is completely contained, which keeps the cooling from dissipating into the server room.
Rittal Liquid Cooling Packages: Has a useful cooling range from 30 to 37kW, depending on the environment, with a nominal cooling range listed at 30kW. Like systems of similar design, chilled air is fed to the rack enclosure, which cools the air that gets fanned over server components. The resulting hot air is circulated back into the system without mixing with the data center environment. No additional modifications need to be made except solid doors on the rack to keep the circulation loop closed. If this setup sounds familiar, it's because Hewlett-Packard's Modular Cooling System (MCS) is actually Rittal's. Pricing for the system from Rittal is in the 20 to $30,000 range, but a search on the HP website listed the MCS rack at $30,499.
APC InfraStruXure InRow RP: APC might argue that all cooling, with the exception of chip-level systems, is both water and air-cooling. In any case, InfraStruXure InRow RP is available as an air-conditioning unit or a chilled water unit. The chilled water system's capacity is up to 70kW, uses up to 2054 watts of power and can cost in somewhere in the ballpark of $23,000 in North America. There are smaller units in the InRow family, such as the chilled water RC, which cools up to 30kW and runs in the neighborhood of $9000; or the tiny SC for the 7kW jobs.
Contractor installation is recommended, which has an effect on the overall cost of the system. In theory, the InRow line doesn't require additional components, but it is unlikely that you will be able to deploy these cooling products without the use of APC's "accessories," i.e. piping, support bridges, etc.
Liebert XDK System: Liebert offers a wide range of liquid cooling products that carry the moniker XD (see Egenera BladeFrame EX below for another specific application). The XDK is a water heat exchange system rated at 17kW of cooling capacity, draws a maximum of 1400 watts of power and requires no additional equipment to function. The XDH is a similar cooler that can use either water or the refrigerant glycol and boasts up to 14kW of cooling capacity.
IBM eServer Rear Door Heat Exchanger aka Cool Blue: This liquid cooling product is essentially a door with a connectivity to a chilled water supply that hinges to a server rack. There are tubes through which cold water runs through, just above dew point to prevent condensation, thereby removing the heat given off by servers in the rack.
Egenera BladeFrame EX: This system is essentially Egenera blade servers integrated with a Liebert XD chassis. The Liebert XD pumps liquid refrigerant that is converted to a gas within the heat exchangers, and then it is returned to the pumping station where it is re-condensed to a liquid.
Chip-level cooling and bottom mount heat exchangers
Many of the products on the market deliver cooling from the side, but other products deliver cooling in different ways; including direct chip cooling.
Knurr CoolTherm: Available in four cooling capacities ranging from 10kW to 35kW, this enclosure uses a bottom mount heat exchanger system which they claim is safer than sidecar enclosures because in the "highly unlikely" event of a water leak, components won't get dripped on.
SprayCool M-Series by ISR Inc.: This rack server attachment sprays a fine mist of 3M's nonconductive, noncorrosive Fluorinert liquid onto chip components. Fluorinert is odorless, tasteless and evaporates almost as quickly as it's spilled. Liquid is pumped from a reservoir at the bottom of the server rack to each box. The liquid hits a nozzle, spraying Fluorinert, though other refrigerants can be used, over the component and heat sink. Components are cooled during the phase change from liquid to gas. The gas exits through the same tube that the liquid was delivered in and back to the reservoir where it is cooled by the building's chilled water supply.