Abstract:
An arrangement for the cooling of computer data centers. More particularly, the arrangement eliminates the problems present in the uneven or inadequate cooling of computer racks due to unwanted airflows, which are encountered between so-called hot aisles and cold aisles present in a computer data center. Specifically, this problem is solved through the provision of partitions which, under normal circumstances, prevent the unwanted airflows by standing in a vertical orientation, yet which, in the event of a fire, collapse from the vertical orientation to a horizontal orientation, thereby avoiding interference with water sprays from sprinkler heads, and thus complying with fire codes and ordinances. Moreover, also employed is a method of preventing the unwanted air flows by utilization of the novel arrangement comprising the fire-code-compatible, collapsible partitions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an arrangement for the cooling of computer data centers. More particularly, the invention relates to an arrangement that eliminates the problems present in the uneven or inadequate cooling of computer racks due to unwanted airflows, which are encountered between so-called hot aisles and cold aisles present in a computer data center. Specifically, this problem is solved through the provision of partitions which, under normal circumstances, prevent the unwanted airflows by standing in a vertical orientation, yet which, in the event of a fire, collapse from the vertical orientation to a horizontal orientation, thereby avoiding interference with water sprays from sprinkler heads, and thus complying with fire codes and ordinances. Moreover, also employed is a method of preventing the unwanted air flows by utilization of the novel arrangement comprising the fire-code-compatible, collapsible partitions. 
     2. Discussion of the Prior Art 
     In the current state of the art, computer data centers frequently contain a plurality of computer racks arranged in rows with aisles therebetween. The racks in any one of the rows are typically cooled by forced convection of air that flows from one of the two aisles adjacent to the row (called the cold aisle) to the other adjacent aisle (the hot aisle). To obtain alternating cold aisles and hot aisles, airflow in every other row is oppositely directed, so that any two adjacent rows either draw cold air from a common cold aisle, or exhaust hot air to a common hot aisle. A problem with this arrangement is that unwanted airflows may occur, over the tops of the rows, from the hot aisles, where air is at a relatively high temperature and pressure, to the cold aisles, where air is at a relatively low temperature and pressure. Such unwanted flows cause the cold aisles to be contaminated with hot air, which may be drawn into the computer racks, thus compromising cooling of electronics components therein. 
     In the prior art, to alleviate the foregoing problem, permanent vertical partitions have been erected above the rows to prevent the unwanted airflows. However, such permanent structures generally violate fire-code requirements or ordinances which stipulate that, during a fire, the gap between the top of the racks and the ceiling must be unencumbered, so as to avoid interference with spray patterns of water emanating from sprinkler heads located near the ceiling. 
     SUMMARY OF THE INVENTION 
     Accordingly, to obviate violations of fire code associated with encumbrances in the space between the top of the computer racks and the ceiling the present invention provides partitions that, in the event of fire, automatically collapse prior to activation of the sprinkler heads. During normal operation of the data center, the inventive collapsible partitions are in their un-collapsed state and thus prevent unwanted airflows. During a fire, the partitions collapse to avoid interfering with the sprinkler system, thus complying with fire-code requirements. 
     Accordingly, it is an object of the present invention to provide a novel partition structure of a collapsible nature that inhibits unwanted air flows during normal operation of a computer data center, yet does not prevent sprinkler heads from efficiently dispensing quenching water sprays in the event of a fire. 
     Another object of the invention is to provide a novel method of utilizing partition structures for deployment in computer data centers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference may now be made to the following detailed description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings; in which: 
         FIG. 1  illustrates generally diagrammatically a three-dimensional perspective view of a typical computer data center constructed in accordance with current art; 
         FIG. 2  illustrates a perspective three-dimensional view showing the intended airflow paths that are to be provided in a typical data center, pursuant to the prior art; 
         FIG. 3  illustrates a perspective representation showing the undesirable or unwanted airflow paths that are encountered in present computer data centers; 
         FIG. 4  illustrates a perspective representation of a computer center pursuant to the current technology showing prior-art solutions attempting to prevent unwanted airflow paths circulating through the data center; 
         FIG. 5  illustrates a generally diagrammatic perspective view of the invention, as applied to a row of computer racks; 
         FIG. 6  illustrates a partly exploded three-dimensional, perspective representation showing a guy-wire assembly connected to a partition plate in a channel structure for the plate pursuant to the present invention; 
         FIG. 7  illustrates a perspective fragmentary view showing an end of the guy-wire assembly of  FIG. 6 ; 
         FIG. 8  illustrates a perspective representation of a version of the channel formed on the partition structure; and 
         FIG. 9  illustrates a further perspective detailed representation of a trigger-point assembly for actuating the collapsible partition structure in the event of a fire. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , a state-of-the-art computer data center typically comprises an array of air-cooled equipment racks  10  resting on a raised floor  12  comprised of a regular array of tiles  14 . Above the racks  10  is located the ceiling  16 . According to fire code requisites, there must be provided a gap  18 , typically about 18″ in height, between the top of the racks and the ceiling, such that during a fire, a water spray pattern from sprinkler heads  20  located in the ceiling is not blocked by the presence of any encumbrances in the gap  18 . 
     The racks  10  are cooled by a flow of cold air  22  that is generated by suitable air-conditioning units  24  in such a manner that the cold air fills a plenum space  26  located below a raised floor  12 . Referring to  FIG. 2  and the xyz coordinate system thereon, this airflow emerges in the +z direction from the plenum space  26  through perforations provided in raised floor tiles that pave so-called cold aisles  30 , which alternate with so-called hot aisles  32  paved by solid, imperforated floor tiles. The intent of this arrangement is that the air should flow through the racks  10  in the +y direction, and then should flow in the +x direction along the hot aisles  32  to the air conditioning units  24  shown in  FIG. 1 , and which are located at the ends of the aisles. 
     However, because of gap  18 , the air does not flow as intended. Instead, as shown in  FIG. 3 , the air flows through gap  18  in unwanted air circulation patterns  36 , thereby creating an aerodynamic short circuit between hot aisles  32  and cold aisles  30 . Thus the upper portions  40  of the racks  10  intake hot air rather than cold air, thereby compromising the efficacy of cooling for equipment housed in the upper portions  40  of the racks. 
     Referring to  FIG. 4 , a prior-art solution to the foregoing problem comprises the installation of permanent vertical partitions  42  that prevent the unwanted air-circulation patterns  36  of  FIG. 3 . However, this kind of installation violates the aforementioned fire-code ordinances or requirements specifying that during a fire no encumbrances in gap  18  interfere with the water sprays from sprinkler heads  20 . 
     Reverting now specifically to the inventive arrangement of collapsible partitions, reference is made to  FIG. 5 , as well as the exploded, enlarged  FIG. 6 , and the detail in  FIG. 7 . Hereby, the invention solves the encountered problem as described above by replacing the prior-art permanent partitions  42  on top of a rack row  50  by a plurality of tiltable-plate assemblies  52 . In the drawings, one tiltable-plate assembly  52  for each rack  10  is shown for illustrative purposes; however, for example, one tiltable-plate assembly  52  can conceivably span two or more racks  10 . Each tiltable-plate assembly, constituted entirely of non-flammable materials, comprises a tiltable-plate  54  that is hinged by means of hinges  56  to a base plate  58 . Each tiltable plate assembly  52  further comprises a channel  60  (shown translucently for clarity in  FIGS. 6 and 7 ), which is fastened on top of the tiltable plate  54 . As shown in  FIG. 6 , channel  60  is suitable for containing and guiding a guy-wire assembly  62 , which consists of a plurality of guy-wire segments  64  and trigger-point assemblies  66 . In  FIG. 5 , one trigger-point assembly  66  for each tiltable plate assembly  52  is shown for convenience, but either more or fewer may be installed, although, in general, there is provided at least one trigger-point assembly  66  and two guy-wire segments  64  per rack row  50 . 
     Referring to  FIGS. 6 and 7 , under normal operating conditions, each tiltable plate  54  is maintained at or proximate an angular position of θ=90° by tension  70  imparted in the guy-wire segments  64 , which stretch from one end of the rack row  50  to the other end through the plurality of channels  60 , this tension being maintained by a pair of wire grippers  72  and a pair of vertical struts  74 , located one each at either end of the rack row. The two endmost guy-wire segments  64  pass through holes  76  in the two vertical struts  74 , one at each end of the rack row  50 . The two wire grippers  72 , each of which bears against the outer surface of its juxtaposed vertical strut  74 , grip the endmost segments  78  of the guy-wire assembly  62 , thereby maintaining tension  70  during normal operation. 
     The trigger-point assembly  66  is designed to split apart when the temperature surrounding it exceeds a specific trigger temperature, as in the event of a fire, thereby releasing the tension  70  in the guy-wire assembly  62 , and thereby ensuring that each of the tiltable plates  54  swings down under the action of gravity from an unstable vertical position θ=90° into one of two horizontal positions θ=0° or θ=180°. As the tiltable plates swing or tilt down, the guy-wire assembly  52 , now divided into two or more pieces, slides smoothly through the channel  60  without snagging the trigger-point assemblies, inasmuch as this would interfere with the downward tilting of plates  54 . If necessary, in order to achieve this, the channel  60  may have flared ends  80 , as shown in  FIG. 8 . When simpler to achieve flaring, the annular cross section of the channel  60  may be round rather than rectangular. 
     An important aspect of the invention is to ensure that the tiltable plates  54  tilt down well before any sprinkler head  20  sprays water, thereby restoring the unobstructed gap  18  required by the fire-code. Thus, the invention specifies that one or more trigger-point assemblies split apart at a threshold temperature that is lower than the temperature at which a sprinkler head activates, and at a faster response time. Sprinkler heads are commonly triggered either by the melting of solder, or more commonly by the breakage of a glass ampule filled with a glycerin-based liquid that expands when heated. Typical ampules, 5 mm in diameter, are designed to break within one to one-and-a half minutes of exposure to a temperature higher than 155° F. (68° C.), although various ampules are available that break at different temperatures and at faster or slower response time, as required under the circumstances. 
     Thus, the invention employs the same type of reliable, proven triggering mechanism used by sprinkler heads, but using ampules that break at a somewhat lower trigger temperature and at a faster response time than which is typical for sprinklers, in order to ensure that the tiltable plates tilt down before any sprinkler commences sprinkling. Specifically, referring to  FIG. 9 , each trigger-point assembly  66  comprises an ampule  90  (of the type described above), which is fixed between two ampule holders  92 , each ampule holder including structure  94  for the attachment of a guy-wire segment  64 . At each trigger-point assembly  66 , the channel  60  is provided with a notch  96  in order to expose the ampule  90  to ambient, (i.e., room) temperature. Each ampule holder  92  is chamfered at both its ampule end  100  and its guy-wire end  102 , and the channel  60 , ampule holders  92  and notch  96  are sized to ensure that the trigger-point assemblies  66  slide easily down the channel  60 , as they must to ensure that the entire array of tiltable plates  54  successfully swing down even when just one ampule  90  breaks. To prevent snagging of the guy-wires, edges of the notch  96  may have flared edges similar to the flared ends  80  previously described in connection with  FIG. 8 . 
     The invention thus provides the advantage of multiple trigger points, any one of which will cause the entire row of tiltable plates to swing or tilt down. This is important because frequently, during a fire, heat is generated only locally (i.e. only one or two sprinkler heads in a room may typically trigger), yet the invention succeeds in producing, from such localized heating, a global or overall result, in essence, the collapse or tilting down of the entire row of tiltable plates. 
     The invention has the additional advantage that the trigger-point assemblies  66  are located near the ceiling  16 . This is important because during normal operating conditions, but especially during a fire, the encountered temperature range is stratified from floor to ceiling. Thus, the invention places the trigger-point assemblies  66  in the same temperature stratum as the sprinkler heads  20 , thereby assuring similar ambient temperatures for the two devices  66 ,  20 , and, thus, (because the trigger-points are designed to trigger at a lower temperature than the sprinkler heads), minimizing the chance that a sprinkler head will ever trigger before the tilting of nearby tiltable plates  54 . 
     From the foregoing, it becomes readily apparent that the invention eliminates the unwanted air circulation  36  in a way that is compliant with fire codes and ordinances. That is, during normal operation, with tiltable plates  54  in their vertical orientation, the gap  18  between computer racks and ceiling is substantially closed, thereby eliminating unwanted air circulation  36 ; yet, at the onset of a fire, the gap  18  is re-opened in a very reliable way by collapse of the tiltable plates  54  to their horizontal orientation, thereby removing any impediment to the free spray of water from sprinkler heads  20 . Inasmuch as the collapse of tiltable plates  54  is triggered by the same reliable mechanism as the sprinkler heads themselves, and carried out simply by gravity, the reliability of this system is extremely high. 
     While the present invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in forms and details may be made without departing from the spirit and scope of the present invention. It is therefore intended that the present invention not be limited to the exact forms and details described and illustrated, but to fall within the spirit and scope of the appended claims.