Mentor Graphics selects Munters Oasis™ IEC to Cool High Efficiency Data Center
Mentor Graphics Corporation (MGC), a leader in Electronic Design Automation (EDA) technology, made a decision to consolidate several small data centers into a single, larger data center to improve efficiency and meet growing demand. This new, state-of-the-art data center was constructed at the company headquarters located in Wilsonville, Oregon, roughly 18 miles south of downtown Portland.
With their many data centers in operation around the world, MGC facilities engineers had experience with a variety of energy efficient design strategies. The engineers knew they needed to focus on three key aspects of the design to maximize efficiency and minimize cost in relation to the heat rejection aspect of the design: fan energy, hot-aisle containment and minimization of refrigeration cooling.
“In the past, the airflow and temperature requirements of data center cooling equipment were similar to air-conditioning equipment, so air-conditioning was the discipline chosen to fill the need. Today the needs of servers are very different from the needs of people, so air-conditioning equipment struggles to operate correctly in a data center environment." said John Wozniak, MGC’s Critical Infrastructure Technician. "While the temperature requirement of the 'intake' of servers is currently similar to the 'intake' of humans, the exhaust temperatures from servers is radically different (much hotter). The approach we took was to implement a design tailored around servers, but also comfortable for humans. Since we could not find precedent for this approach, we relied heavily on Mentor Graphics’ FloVENT® computational fluid dynamics (CFD) modeling software to validate the design.”
Munters’ Oasis™ air-handlers selected for the project operate using the principle of Indirect Air-Side Economization (IASE), where outdoor air is used to reject heat from a recirculating data center airstream by way of an air-to-air heat exchanger. With this approach there are two completely separate airstreams. With IASE systems, only a small amount of make-up air, as required for proper ventilation and space pressurization, is introduced into the data hall. Since the cooling units simply extract heat from a recirculating airstream, they do not impact room humidity levels and risk of ambient pollutants impacting the servers is greatly mitigated compared to direct air-side economizer designs.
The Oasis units were customized to provide optimal efficiency of fans and heat rejection components. For the recirculating (supply) airstream, a fan array using direct drive plenum fans was selected with EC motors (variable speed), each with an inlet back-draft damper. The fan array was configured to provide N+1 redundancy at the fan level. The supply fan motors are controlled so as to provide a slight negative pressure in the return duct. The result is optimal efficiency in the cost to circulate the cooling air, which for economizer cooled data centers is the single greatest power consumer.
The air-handlers were delivered on site in July 2012 and commissioned shortly after. Designed to meet a seismic importance factor of Ip=1.5, they are anchored to concrete roof curbs. During the first year of operation the system maintained server inlet temperatures throughout the room within +/- 1°F.
The operating efficiencies have exceeded Mentor Graphics expectations, especially in the early stages of operation when data centers are typically least efficient. At the outset the team’s initial target was for 5,000 hours per year (57%) of economizer cooling using no compressors but actually achieved nearly 8,000 hours (>90%) during the first year of operation.
“The result of using this quality equipment and the detailed design process has allowed us to be efficient on day one, and from this point on we are saving money, energy, and everything is working correctly.” said Wozniak.
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