ASHRAE Journal - January 2009 - (Page 40) • Provide exhaust deἀection devices to direct hot exhaust air upwards toward the ceiling and the return air path. It is a passive device in that no cooling is involved. Benefits include an inexpensive and robust solution that does not require any infrastructure changes and little, if any, maintenance. The thermal effectiveness is remarkable; the RCI improves to 99% (Figure 4). Drawbacks include no room-load reduction, no reduction in HVAC airflows, and no reduction in air ducting. • Migrate to highly organized equipment en vironments with alternating hot and cold aisles using only optimal EC-Class equipment. Figure 5 shows equipment lined up front-to-front with hot and cold aisles. Besides numerous other benefits, including thermal and energy, organizing the environment this way creates a striking physical simplicity of the overhead ductwork. This configuration should be the long-term goal, and it can readily be phased in when new network equipment is installed. Minor hot-air recirculation and an elevated design supply temperature (55°F → 60°F [13°C → 16°C]) contribute to an RCI below the ideal of 100%. Conclusions ment aisles and optimized EC-Classes, measures that are readily available in many existing network rooms are more modest. Understanding how to address equipment and infrastructure issues is imperative when new high-density equipment arrives at the loading dock. Improper placement of point loads within the existing environment can greatly reduce the reliability of the network under normal operation and cooling outage situations. A well considered plan for the analysis and placement of high-density equipment is critical to ensure network availability and reliability. Today, tools are readily available to develop key placement strategies similar to those outlined in this article. 1. ASHRAE. 2004. Thermal Guidelines for Data Processing Environments. 2. Telcordia. (Herrlin, M.) 2001. “GR-3028-CORE, Thermal Management in Telecommunications Central Offices, Issue 1.” Piscataway, N.J.: Telcordia Technologies. 3. Telcordia. (Kluge, R.) 2006. “GR-63-CORE, NEBS™ Requirements: Physical Protection, Issue 3.” Piscataway, N.J.: Telcordia Technologies. 4. Herrlin, M.K. 2005. “Rack cooling effectiveness in data centers and telecom central offices: the rack cooling index (RCI).” ASHRAE Transactions 111( 2):725 – 731. 5. Herrlin, M.K. 2006. “A new tool for evaluating and designing the thermal environment in telecom central offices.” IEEE-INTELEC, Telecommunications Energy Conference. http://tinyurl.com/intelec-herrlin. References Although the long-term goal is to migrate the network room to an organized environment with alternating hot and cold equip- FLOWHOOD ELECTRONIC FLOWHOOD DIRECT DIGITAL READOUT 25-2500 CFM When it has to be stainless, it has to be A-J! The experts in stainless steel clean air systems waste water treatment facilities, for plus: • Custom fabrication • Rush deliveries A-J Manufacturing offers a complete line of custom and standard stainless steel air distribution products, all designed and manufactured to offer durable, dependable and low maintenance performance necessary for waste water treatment facilities. What’s more, with our state-of-the-art manufacturing capabilities, we can also offer you the industry’s shortest lead times for custom orders. So for continuous linear, security grilles, modular diffusers and much more, contact A-J Manufacturing today! AUTOMATICALLY CORRECTS FOR AIR DENSITY & BACKPRESSURE CHOICE OF METERS - AIR FLOW ONLY, OR AIR FLOW, VELOCITY, PRESSURE & TEMPERATURE OPTIONS INCLUDE: MEMORY, AVERAGE & SUM TO 2000 READINGS, SEQUENTIAL RECALL, AUTO-READ REPAIR POLICY - TWO WEEK TURNAROUND OR LESS CUSTOM TOPS MADE TO ORDER Shortridge Instruments, Inc. 7855 East Redfield Road • Scottsdale, Arizona 85260 (480) 991-6744 A-J Manufacturing 800-247-5746 • www.ajmfg.com www.info.hotims.com/22183-115 www.shortridge.com FAX (480) 443-1267 www.info.hotims.com/22183-130 40 ASHRAE Journal January 2009 http://tinyurl.com/intelec-herrlin http://www.shortridge.com http://www.ajmfg.com http://www.ajmfg.com http://www.shortridge.com http://www.info.hotims.com/22183-130 http://www.info.hotims.com/22183-115
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