Chill-off winners provide university data centre with energy-efficient cooling
The removal of heat and saving energy are major environmental challenges facing data centres. So, when Warwick University needed to expand its facilities it called in Eaton-Williams Process Cooling to supply energy efficient cooling and saw a 50% reduction in heat generated.
Warwick University’s Centre for Scientific Computing (CSC) was one of the first to benefit from Process Cooling’s rear door heat exchangers. Rapid growth in the use of High Performance Computing (HPC) resources in the CSC by academics; post-doctoral researchers and PhD students, meant that the department’s existing data centre facilities needed to expand but the problem facing the university was to temper the need for expansion with the control of heat and limited floor space.
Warwick, working closely with its consulting engineers, Couch Perry Wilkes Partnership (CPWP) sought the solution from Process Cooling who’s approach moved away from traditional CRAC (Computer Room Air Conditioning) units and uses rear door heat exchangers (RDHx) and CDUs which offer a more robust, compact and energy efficient solution. (Process Cooling’s RDHx units won the Silicon Valley Leadership Group’s (SVLG) sponsored “Chill-Off” in 2008 for being the most energy efficient data centre cooling product).
With initially six cabinets housing forty servers in each, six RDHx units were installed in conjunction with a Downflow CRAC arrangement to remove up to 15kW of heat from each rack using a traditional chilled water system.
Each RDHx offers condense free operation using controlled water from the CDUs. The RDHx high specifications include refrigeration grade coils pressure tested to 45, hermetic construction, sealed copper brazed, under floor manifolds pressure-tested to 20-bar, leak detection and leak-free quick release couplings and hose sets rated to 53 bar. The secondary circuit working pressure fed by the CDUs in ‹4 bar gives an excellent safety margin.
The units substantially reduce the heat output from the servers which can be in excess of 45°C by as much as 50%, removing it from the hottest part of the servers (back) and rejecting it into the cooling coils in the rear door which then cools the rejected air down to close to room temperature (approximately 20°C).
In an adjacent room as well as two CRAC units two Process Cooling CDUs are controlling the temperature of the water for the RDHx units. The RDHx requires no additional fans or electricity and is designed to cool without opening or removing the doors. Because the heat exchangers are in the back of the racks and in the door itself, the actual footprint of the racks and floor space is barely impacted.
A major benefit is that as the RDHx cools the air before it leaves the rack there are no hot spots and cooling air at source is very energy efficient. (150kW of heat can be rejected to the primary chilled water system via RDHx and a CDU, consuming only 2.6kW of pump power. A CRAC system would consume around 10-15kW to do the same job and with a much larger footprint.)
Process Cooling’s solution has enabled Warwick to introduce high density equipment with zero thermal impact into its data centre and has set a benchmark which the university plans to implement in its other data centres.
Working closely with IBM in the US, Process Cooling has developed a number of products specifically for data centre environments including CDUs (Cooling Distribution Units) and rear door heat exchangers (RDHx) that remove heat at source using chilled water as the coolant. This approach has proved so successful in reducing costs, energy consumption and freeing up floor space that its RDHx won the Silicon Valley Leadership Group’s (SVLG) sponsored “Chill-Off” in 2008 for being the most energy efficient data centre cooling product.