Mission Critical - Winter 2008 - (Page 63)

Prepared continued 90˚F 85˚F 78˚F 73˚F 70˚F 65˚F Traditional Data Center 76˚F 76˚F 76˚F Ideal Data Center Figure 3. Inlet air temperatures are not uniform across the front of the serves, as is the ideal. ceilings can offer sufficient clearance for the return air to stratify above the cold air in the room. Several benefits come from this architecture. One such benefit is that up to 100 percent of the exposed floor can be perforated. Perforated access tiles can be located anywhere in the room. Managed exhaust airflow allows the entire data center to be cold — no more hot zones. Cold intake air can be pulled from anywhere in the room. A cabinet no longer has to obtain all of the air required from the access floor tile directly in front or adjacent to it. CFM balancing issues practically disappear. Managed exhaust airflow also creates the opportunity to deploy high-density applications in a non-access floor environment. Cold air can be delivered directly into the room. It does not require an access floor. Achieving High Performance CPI has developed and tested a ducted exhaust cabinet that utilizes managed exhaust airflow. This design avoids any dependency on booster fans, with the accompanying concerns over additional heat loads, fan failure and redundancy, thereby qualifying the ducted exhaust cabinet for Tier three and Tier four criticality applications. The basic cabinet configuration is similar to other CPI server cabinets (see figure 5). The most obvious feature is the large, lowrestriction exhaust air duct at the top rear of the cabinet. The front Figure 5. The basic cabinet door is high-flow perforated configuration. metal. The rear door is solid. The design assumptions were confirmed in third-party testing at extreme heat load densities. This testing demonstrated that the ducted exhaust cabinet can easily support 22 kW of heat load in the proper data center environment. It also indicated that the cabinet could dissipate even more heat under appropriate circumstances (figures 6 and 7). Subsequent data center installations around the world have confirmed the theory and early test results. Multiple high performance data centers are successfully using the ducted exhaust cabinet to support average heat loads of 17-25 kW. Many of these users have demonstrated their confidence in the ducted exhaust cabinet by designing future installations with planned heat loads up to 30 kW per cabinet. ■ ◗ REPRINTS OF THIS ARTICLE are available by contacting Jill DeVries at devriesj@bnpmedia.com or at 248-244-1726. www.missioncriticalmagazine.com Figure 4. Managed exhaust airflow completely segregates the hot exhaust air by directing it up an exhaust duct at the top rear of the cabinet. deliver 600-700 cubic feet per minute (CFM). That volume of cool air will only dissipate 4-8 kilowatts of heat. The actual heat dissipated depends on how the manufacturer has designed heat to transfer into the air moving through the equipment. Server manufacturers design their products to consume an appropriate volume of air for the heat that they generate. However, not all manufacturers design around the same temperature rise across their components. A typical rule of thumb is that the temperature will rise 27 deg F (15 deg C) between the intake and exhaust of a server. But actual measurement of an IBM eServer BladeCenter under full load indicated a 42 deg F temperature rise ( T). The greater the normal temperature rise designed into the equipment, the greater the amount of heat transferred into a given volume of air. Going Beyond Hot aisle/cold aisle starts with the correct premise--to segregate the cold source air from the hot exhaust air in the data center. The hot aisle/cold aisle philosophy of segregating airflows leads to managing exhaust airflow when the concept is applied at the next level. Managed exhaust airflow completely segregates the hot exhaust air by directing it up an exhaust duct at the top rear of the cabinet (see figure 4). Typically, the exhaust duct is connected to a drop ceiling return air plenum. But this is not necessary where high Winter 2008 | 63 http://www.missioncriticalmagazine.com

Table of Contents Feed for the Digital Edition of Mission Critical - Winter 2008

Mission Critical - Winter 2008 Table of Contents Editorial: What Have We Been Doing? Cronin’s Workshop: Imagining the Perfect Data Center Power And Cooling Solution Digital Power: The Next Edge in Business Resiliency Zinc Whiskers: Keeping Up With The Green Movement Mission Critical Care: Shipping, Staging, and Installation Legal Perspectives: “A Reliable Energy Supply Is Key to Data Center Success” Continued Payback, Instant Protection Beyond the Nines The Green Information Technology Revolution Health Care Network Offers Glimpse of the Future of Backup Power High-Density Data Centers – Discuss, Design, Deploy High Performance Data Centers Call for Innovative Cooling Techniques More Data in the Data Center Five Considerations for Powering Data Center Racks New Products Industry News Events Classifieds Letters Ad Index Datacenter Wiki: wiki-Mission Critical

Mission Critical - Winter 2008

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