Chilled Water System Upgrade

	The chilled water system circulates cold water out to the computer room, flows it through heat exchangers to cool the air, then returns the warm water to be cooled and recirculated. Air chilling has become a critical component of modern data centers because computers plus their associated cyberinfrastructure generate rapidly increasing amounts of heat.

As part of the late-FY 2005 effort to extend the useful life of the Mesa Lab computer room infrastructure, we completed an upgrade of the chilled water system. While that work was completed in FY 2005, the performance of the chilled water system was evaluated, tested, and improved in FY 2006. Like any complex system that integrates hardware with software, the tuning and performance of the system must be tested and retested. This is particularly challenging with a production system that must provide cooling around the clock to the high performance computers housed at the Mesa Lab. A number of tests were devised and performed primarily during the twice-annual downtimes for preventative maintenance.

During this testing, a number of anomalies were observed, evaluated, and eventually remedied. These efforts were coordinated in partnership with the vendors, outside engineering firms, commissioning experts, physical plant services, and CISL staff. It was critical that the problems were resolved during FY 2006 because the chiller's performance had to be optimal before the installation of the ICESS equipment. This equipment will require all components of the Mesa Lab infrastructure to perform continuously at full capacity. Note that the ICESS equipment will feature the first return of water-cooled equipment to NCAR's data center. Liquid-based cooling was the mainstay of high performance computing until the early 1990s.

This project supports NCAR's strategic goal to "Provide robust, accessible, and innovative information services and tools," and the related strategic priority of "Enhancing capability and capacity of NCAR supercomputing." It was made possible through NSF Core funding.