Communications and information technology equipment is commonly mounted in racks or enclosures. Equipment racks and enclosures are used to contain and to arrange communications and information technology equipment, such as servers, CPUs, networking equipment and storage devices in small wiring closets as well as equipment rooms and large data centers. A standard rack typically includes front-mounting rails to which multiple units of equipment, such as servers, are mounted and stacked vertically within the rack. A standard rack can be sparsely or densely populated with a variety of different components including components from different manufacturers.
Most rack-mounted communications and information technology equipment consumes electrical power and generates heat. The heat collectively generated in densely packed equipment racks can have adverse effects on the performance, reliability and useful life of the equipment in the racks. Accordingly, air cooling systems are often a part of an efficient data center, design. In particular, many air conditioning (e.g. cooling) systems, such as described in U.S. Pat. No. 6,374,627, include a raised floor to facilitate the system's air cooling and circulation functions. These systems typically use open floor tiles and floor grilles, perforated tiles, or vents to deliver cool air into the room of racks from the air passageway disposed below the raised floor of an equipment room. Perforated tiles are typically located in front of the equipment racks and enclosures. The cool air flows from below the raised floor to the front side of the equipment racks or enclosures.
As shown in FIGS. 1-2, rack-mounted equipment 101 is often cooled by air that flows along a front side or air inlet side of a rack, through the rack, and out the rear or exhaust side of the rack. Often, the rate of the airflow across the heat generating components within the rack is dependent on the size and speed of one or more fans located within the equipment. Consequently; the ability for the airflow to transfer heat away from the heat-sensitive components is heavily dependent on the inlet temperature of the air. In addition, the heat released from each, rack is released into the same environment which is being cooled, causing increased energy consumption due to mixed cool and hot air flows entering the racks.
Referring to FIGS. 3-4, to lower this energy consumption, a common configuration of equipment in a data center has the racks in rows 201, where the inlet sides of the rows are arranged face to face. Grilles or perforated tiles are located in the raised floor 215 between the two faces of the rows. This configuration, is commonly called a “cold aisle” because the cool air from the air cooling system flows into a cold air plenum 217 of the raised floor 215, through the perforated tiles and into an aisle 210 between the rows. The cool air is then drawn into the rack mounted equipment and exhausted to the space behind (typically a “hot aisle”) or above the rows.
Placing racks into these cold aisle and hot aisle configurations provides a more efficient environment for the rack mounted equipment and codling equipment, such as computer room air conditioning (CRAC) unit. However, just creating the aisles is not sufficient to completely separate the mixture of the cold and hot air within a room. Recent developments have shown that further separation and containment of the cold aisles and hot aisles greatly improves efficiency and functionality of the rack mounted equipment and the CRAC units. Hot air from the hot aisles may be directed towards the inlet of the CRAC unit and the cold air release from the CRAC unit may be directed to the inlets of the rack mounted equipment. This may be done through doors 220 placed on the ends of the cold and hot aisles, along with ceilings and/or separators of various forms above the racks (not shown), which aid in containing the air within specific locations. For example, as shown in commonly owned U.S. patent application Ser. No. 11/131,503, filed May 17, 2005, entitled “COLD AISLE ISOLATION,” baffles may be placed above or along the ends of the rows of racks:
Creating complete separation of cold and hot air is challenging, especially in areas of rack mounted equipment that may not be disconnected or re-located in the process. Referring again to FIG. 3, many of these areas include various sizes, shapes and numbers of racks, which do not follow the ideal configuration of equipment to form the aisles implementing the most efficient sealing techniques (i.e., doors). Often, stand alone 220 racks are located in the data center and the cold aisle containment does not provide a source of cold air for these racks. This occurs primarily in older data centers, which include large amounts of racks that accumulate over time out of necessity. Accordingly, as newer racks, rack systems and equipment are developed, variations in the data centers are inevitable, unless a completely new system is installed. Installation of an entire new system is extremely costly and, as previously mentioned, some rack mounted equipment may not be disconnected in the process.