Abstract:
A raised floor air handling system for use in a building that is used in combination with and set into an elevated floor assembly that is mounted on a principal floor of a building so as to provide an air plenum between the two floors. An air handling assembly is mounted below an integral raised or elevated floor tile to pull air via a radial impeller fan from the air plenum and directs it vertically through the integral raised floor tile into air distribution ducting (flexible, anti-static fabric with nozzles, linear vents, or other types of perforations) and onto the equipment/location being served air. The raised floor tile is designed to match the load rating of other floor tiles to become an integral part of the elevated floor assembly. The ducting attaches to the top of the raised floor tile via removable duct collars and is supported vertically/horizontally by miscellaneous hardware attached to existing/new structures.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/247,281, filed Nov. 9, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an air handling system. More particularly, it relates to an air conditioning/heating system for use in computer rooms and data centers to provide climate control for electronic equipment such as computers, servers, routers, switches and other networking equipment. 
     BACKGROUND OF THE INVENTION 
     Operators, managers, designers, and developers of large data centers and computer rooms are constantly striving to put as much computer hardware into their available space as they can. This has led to tall, compact, double-sided rack systems set atop raised computer room floors. At the same time, computing speed is increasing per Moore&#39;s law due to the demand for and development of more complex software and interfaces. This also leads to more heat generation. These two factors combined have greatly reduced the effectiveness of traditional cooling systems, such as Computer Room Air Conditioners (CRACs), Computer Room Air Handlers (CRAHs), In Space Units (ISUs), etc. 
     In the past, most large data centers and computer rooms have utilized many small packaged CRACs or CRAHs located atop the raised floor amongst the computer and server equipment. Both of these systems pull warm air in at the top (˜5-6′ above the raised floor), condition the air (per temperature and humidity setpoints), and provide cool air to an underfloor plenum (under the raised floor). Air is then passively allowed out of the underfloor plenum through the use of perforated floor tiles. 
     The heat that is pulled out of the air is then transferred out of each of the CRACs or CRAHs via underfloor condenser or chilled water piping systems to cooling towers and/or chillers located outside of the data center. Each CRAC or CRAH is also served by condensate and makeup water piping for humidity control. All of this piping interferes with the cool air that is being distributed under the floor and decreases the air supply or static pressure. Also, if the condenser water piping is not insulated, the heat in the condenser water can be transferred to the air under the floor before it has a chance to cool the servers and computers, thus providing warm air supply to the servers and computers. 
     Since the cool air is passively allowed out of the underfloor plenum, the distance that the air moves out of the perforated tiles relies on the pressure from the CRACs or CRAHs, the number of perforated tiles, the size/quantity of perforations, and the amount of space served by the CRACs and CRAHs. However, even if high pressure blowers were utilized in the CRACs, there can still be areas where there is not enough cool air coming out of the floorspace. 
     Also, since warm air rises and cool air drops, natural convection typically overpowers the trickle of cool air from the floor tiles. Without active circulation in place (natural or otherwise), the air stratifies into different temperature layers. This results in higher supply and operating temperatures on servers at the tops of the racks. With a traditional data center cooling system, temperatures of 80 to 90° F. (or more) have been seen at the intake of servers from the middle to the tops of the racks versus the 60 to 70° F. available under the raised floor. 
     At elevated temperatures, electronic components can fail catastrophically or the electrical characteristics of the chips can undergo intermittent or permanent changes. Manufacturers of processors and other computer components specify a maximum operating temperature for their products. Most devices are not certified to function properly beyond 50° C.-80° C. (122° F.-176° F. However, a loaded server/computer with standard cooling can easily experience operating temperatures that exceed the limits. The result can be memory errors, hard disk read-write errors, faulty video, and other problems not commonly recognized as heat related. 
     There have been many studies by public and private agencies over the years that have found that the life of an electronic device is directly related to its operating temperature. These studies, based on empirical data, were used to create models/standards for determining electronic equipment reliability. (MIL-HDBK-217, Bellcore TR-332, and the Arrhenius equation are examples.) Based on the Arrhenius equation, it can be seen that each 10° C. (18° F.) temperature rise reduces component life by 50%. Conversely, each 10° C. (18° F.) temperature reduction increases component life by 100%. Therefore, it is recommended that computer components be kept as cool as possible for maximum reliability, longevity, and return on investment. 
     It is the objective of this invention to provide cool air evenly to the electronic equipment, eliminate the air stratification, extend the life and increase the reliability of electronic equipment while minimizing the impact on the floorspace, since space on a computer room or server room floor is typically a commodity. 
     SUMMARY OF THE INVENTION 
     The present invention takes the form of raised floor air handling units. The units actively pull cool air from the underfloor plenum through a custom raised floor tile with bulkhead fittings to flexible anti-static fabric ductwork supported vertically (or other air distribution systems). This ductwork then directs the cool air equally across the face of all electronic equipment on each rack or cabinet via nozzles, reinforced linear slots, or other air distribution methods. This, coupled with a properly designed computer room cooling system, eliminates heat added to the room and the associated stratification. Therefore, with a cooler air supply to all of the servers from the raised floor air handling units, the annual cost for server replacement (not including interruption of service) could be reduced by as much as 50%. Note that additional savings can also be achieved by the elimination of problems from customer dissatisfaction associated with the equipment overheating issues, which is typically more valuable than the replacement costs. Financial losses from possible disruption in service due to overheating would also be reduced. 
     By implementing the raised floor air handling units, the typical computer room air conditioning units can be eliminated and centralized air handling or air conditioning systems can be installed remotely on roof or in a mechanical room to handle the climate control, move the cool air under the floor, and pull the warm air back from above the racks. In new construction, it not only eliminates the installation cost of the CRACs, CRAHs, and ISUs, but also the associated piping and wiring under the floor. This would, in turn, save on energy costs associated with the losses in the piping and electrical. 
     Also, since the raised floor air handling units can be installed in walkways in front of the server racks and allow a person to still use the walkway, the additional floorspace freed up by the elimination/relocation of the computer room air conditioning units can be used to generate additional revenue and/or allow the installation of more computer racks. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 provides an elevation to show the application of the raised floor air handling unit in a raised floor system providing air to server/computer racks or cabinets with air intakes on the exterior of the rack or cabinet. 
     FIG. 2 provides an elevation to show the application of the raised floor air handling unit in a raised floor system providing air to server/computer racks or cabinets with air intakes on the interior of the rack or cabinet. 
     FIG. 3 provides an elevation to show the application of the raised floor air handling unit in a raised floor system pulling air from server/computer racks or cabinets with exhaust air plenums on the interior of the rack or cabinet. 
     FIG. 4 provides an elevation to show the application of the raised floor air handling unit in a raised floor system recirculate air to and from server/computer racks or cabinets with exhaust air plenums on the interior of the rack or cabinet. 
     FIG. 5 is an isometric representation of the raised floor air handling unit assembly. 
     FIG. 6 is a partially-exploded isometric representation of the raised floor air handling unit assembly. 
     FIG. 7 is an elevation view of the supply end of the raised floor air handling unit without its air distribution ducting. 
     FIG. 8 is an elevation view of the side of the raised floor air handling unit without its air distribution ducting. 
     FIG. 9 is an elevation view of the “intake” end of the raised floor air handling unit without its air distribution ducting. 
     FIG. 10 is a cross sectional view of FIG. 9 showing the inner workings of the raised floor air handling unit. 
     FIG. 11 is a partial cross sectional view of the raised floor air handling unit to show an optional chilled water coil. 
     FIG. 12 is a plan view of the of the raised floor air handling unit from the top without the floor tile (air handling section only). 
     FIG. 13 is a plan view of the of the raised floor air handling unit from the bottom without the maintenance access cover (air handling section only). 
     FIG. 14 is a plan view of the of the raised floor air handling unit. 
     FIG. 15 is a partial cross sectional view of FIG. 14 showing the construction of the floor tile. 
     FIG. 16 is an isometric representation of the raised floor air handling unit assembly with a rectangular supply air register or exhaust air grille. 
     FIG. 17 is an isometric representation of the raised floor air handling unit assembly with two square supply air registers or exhaust air grilles. 
     FIG. 18 is an isometric representation of the raised floor air handling unit assembly with two round supply air registers or exhaust air grilles. 
     FIG. 19 is an isometric representation of the raised floor air handling unit assembly with a supply air manifold. 
     FIG. 20 is a representation of a supply air duct or manifold with nozzles for air distribution. 
     FIG. 21 is a representation of a supply air duct or manifold with a linear vent for air distribution. 
     FIG. 22 is a representation of a supply air duct or manifold with linear slots for air distribution. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The implementation of the first embodiment of the raised floor air handling unit  60  is shown in the elevation provided in FIG.  1 . In this figure, one can see that the raised floor air handling unit  60  is designed to sit in and become an integral part of an elevated floor assembly or raised floor tile system  64  that sits above the floor  68  of a building. The space between the raised floor tile system  64  and the building floor  68  is typically utilized as an underfloor cool air plenum  67 . Cool air can be distributed into the underfloor cool air plenum  67  by a separate air conditioning system or by multiple systems. However, the raised floor air handling unit can be provided with an internal chilled water coil  41  as seen in the section view provided in FIG.  11 . Although the chilled water coil  41  is not part of the all of the embodiments, the addition of this option eliminates the need for a separate air conditioning system and the air plenum  67  can be used as a return air plenum where the air is cooled inside the raised floor air handling unit  60 . In either case, FIG. 1 shows that air is pulled from the underfloor air plenum  67  into the raised floor air handling unit  60  via a fan inside of the air handler  30  and pushes up through the integral raised floor tile  20  into ducting  61  or another type of air distribution equipment, such as registers, manifold, nozzles, etc. (as seen in FIGS. 16-22) and supplies air  66  onto the face of the electronic equipment in a rack or cabinet  62 . This supply air could also be used for comfort cooling/heating of personnel, ventilation, makeup air, or other processes. One embodiment utilizes flexible anti-static fabric ducting  61  that is hung vertically by a vertical duct support arm/bracket  14  approximately the same height H 3  as the rack or cabinet  62  (typically 8′); however, the ducting can be custom built to a customer specified length. The ducting is held in place horizontally by vertical duct support arm/brackets  15  attached to the server/computer rack or cabinet  62  or some other structural component such as a cable tray; however, alternative air distribution methods and support systems can be utilized such as spring-loaded, retractable cable reels to allow access to the electronic equipment without disconnecting the ductwork. The supply air  66  would then be pulled in by the circulation fans internal to the electronic equipment located in the rack or cabinet  62  and exhausted from the rack or cabinet  62  via an exhaust air plenum  63 . 
     One option to the implementation of the raised floor air handling unit  60  is shown in the elevation in FIG.  2 . It is a similar configuration to the implementation shown in FIG. 1; however, the air handler section  30  pushes air horizontally into ducting  61  below the raised floor  64  into an underfloor air supply plenum box  69  that then directs the cool air  66  up through the raised floor tile  64  into the supply air plenum  65  of a server/computer rack or cabinet  62 . However, note that the ducting could route the air directly to the supply air plenum  65  of a server/computer rack or cabinet  62  without an underfloor air supply plenum box  69 . 
     Another option to the implementation of the raised floor air handling unit  60  is shown in the elevation in FIG.  3 . It is a similar configuration to the implementation shown in FIG. 1; however, warm air is pulled from the exhaust air plenum  63  at the bottom of the server/computer rack or cabinet  62 , into the return air plenum  67 , circulated into the air handler section  30 , cooled through a chilled water coil  41  (as seen in FIG.  11 ), pushed into ducting  61  or another type of air distribution equipment, supplied  66  onto the face of the servers/computers in a server/computer rack or cabinet  62 , into the exhaust air plenum  63 , back into underfloor return air plenum  67 , and recirculated back into the air handler section  30 . This eliminates dependence on other air distribution systems for cooling the servers/computers in a server/computer rack or cabinet  62 . Also, note that ducting could be added between the exhaust air plenum  63  and the air handler section  30  to enhance the air circulation through the server/computer rack or cabinet  62 . 
     Another option to the implementation of the raised floor air handling unit  60  is shown in the elevation in FIG.  4 . It is a similar configuration to the implementation shown in FIG. 3; however, warm air is pulled from the exhaust air plenum  63  at the bottom of the server/computer rack or cabinet  62  through ducting into the air handler section  30 , and exhausted into the return air plenum  67 . 
     The first embodiment of the raised floor air handling unit is illustrated generally in FIG.  5 . This system  60  consists of  3  main subassemblies: an air handling unit  30 , raised floor tile  20 , and ductwork  61 . As previously shown, FIG. 5 shows air being pulled into the sides of the air handling unit  30 , up through the raised floor tile  20 , and pushed out through ductwork  61  or another form of air distribution equipment. 
     This embodiment is further represented in the partially exploded view provided in FIG.  6 . The external shell of the air handling unit  30  includes a housing  44 , a removable fan access cover  50 , two duct blank-offs  31  that seal off alternate supply air openings  46  and can be interchanged with the two duct collars  23  (discussed later), and two inlet screens  33 . The radial impeller fan  32  and fan motor  40  pull air into the air handling unit  30  through the inlet screens  33 , optional filters  35 , and optional filter retaining screens  34  into the intake plenum  36  down through the inlet ring  37  and radial impeller fan  32 . This air is then directed up through the raised floor tile assembly  20  through the primary supply air openings  47 . Optional filter access covers  24  are provided for easy access to the filters  35  without removing the raised floor air handling unit  60 . Optional filter access covers  24  are provided for easy access to the filters  35  without removing the raised floor air handling unit  60 . An optional controls access cover  22  is provided for controlling the raised floor air handling unit  60 . The duct assembly  61  attaches to the raised floor assembly via duct collars  23  that channel the air from the primary supply air openings  47  into the air distribution ducts  10  and out of the supply air nozzles  16  or another type of air distribution orifice. The nozzles may be oriented horizontally or they may be angled up or down from horizontal anywhere from up 75 degrees to down 75 degrees, more preferably between up 45 degrees to down 45 degrees, and most preferably between up 25 degrees to down 25 degrees. In the embodiment shown, the nozzles are approximately horizontal. The nozzles  16  may also be oriented around the circumference of the duct  10  to provide air to a single vertical line, part or the entire surrounding area. Therefore the nozzles  16  may be in a single vertical line or the nozzles  16  may extend around 360 degrees, 270 degrees, 180 degrees, 90 degrees, etc. or any amount in between. The embodiment shown has the nozzles  16  at 19 degrees each direction from the center line. The air distribution ducts  10  are fastened to the duct collars  23  via a band clamp  12 , strap, or other similar attachment means, supported vertically by a vertical duct support clip  13 , and supported horizontally by a horizontal duct support clip  11 . These duct support clips are then attached to the vertical and horizontal duct support arm/bracket assemblies ( 14  &amp;  15 , respectively) as shown in FIGS. 1-3. 
     FIGS. 7-9 provide elevation views of the raised floor air handling unit without the ducting. In these views, one can see the relationships between the previously mentioned assemblies and parts. In the embodiment shown, dimensions L 1 , L 2 , W 1 , W 2 , H 1 , and H 2 , would accommodate a standard 24″ length×24″ width×18″ depth floor tile assembly; however, custom dimensions can be accommodated. Additionally, FIG. 9 refers to a cross section provided in FIG.  10 . 
     The internal workings of the first embodiment are shown in the cross section provided in FIG.  10 . This cross section shows the air after it has already been pulled through the optional inlet screens  33 , filters  35 , filter retainer screens  34 , and into the intake plenum  36 . The air is then pulled through the inlet ring  37  to the radial impeller fan  32 , diverted up by an airflow diverter  39  through the raised floor tile assembly  20  and duct collars  23  into the ducting  61 . Although the controls  28 , control panel  27 , and controls access cover  22  impede the air flow in this cross section, the air still flows into the duct collars  23  on either side of these controls. Additional diverters could be implemented around the control panel  27  to enhance the air flow into the duct collars. FIG. 10 also shows the fan motor  40  mounted via a fan mounting bracket  43 ; however, this can be accomplished in any other manner as necessary. 
     FIG  11  shows the implementation of an optional chilled water coil  41  where the airflow diverter  39  was shown previously in FIG.  10 . FIG. 11 also shows the implementation of insulation  45  and a condensate pan to support the implementation of the chilled water coil  41 . However, note that other components could be provided in support of the chilled water coil  41  such as a condensate pump, chilled water control valve, and additional/different controls. 
     FIGS. 12 &amp; 13 provide plan views of the first embodiment of the air handling unit  30  assembly where FIG. 12 is looking at it from the top without the raised floor tile attached and FIG.  13  is looking at it from the bottom without the fan access cover attached. In these views, one can see the relationships between the previously mentioned parts. In the embodiment shown, dimensions L 2  and W 2  would accommodate a standard 24″×24″×18″D floor tile assembly; however, larger, smaller, and different strength sizes could be created to accommodate custom dimensions and floor loads. Different size units may also be used in situations where more or less depth is available below the raised floor. One unique aspect shown in these views is the angular construction of the intake plenum  36  which allows for reduced air velocity through the optional filters  35  (as seen in FIG. 12) and diverts the airflow from the radial impeller fan  32  for better performance and reduced air noise. 
     FIG. 14 provides a plan view of the first embodiment of the raised floor tile assembly  20  with the duct collars  23  attached. The assembly  20  includes a tile plate  25  that is supported below by tubular steel framing/reinforcement  26 , which also frames  5  openings in the tile plate  25 : two primary supply air openings  47 , two filter openings  48 , and one control panel opening  29 . Covering these openings is the ducting  61  mounted to the duct collars  23 , filter access covers  24 , and the controls access cover  22 , respectively. Optional handles  21  are also shown. 
     FIG. 15 provides a cross section of the first embodiment of the raised floor tile assembly  20 . In this view, one can see the relationships between the previously mentioned parts. 
     FIG. 16 provides an isometric of a rectangular supply register or exhaust grille  80  mounted to the raised floor tile assembly  20  in lieu of the ductwork  61  previously shown. The rectangular supply register or exhaust grille  80  can be installed with or without adjustable vanes to allow for the transfer of air without installing ductwork or its associated hardware. The incorporation of the rectangular supply register or exhaust grille  80  requires the control panel opening  29  to be relocated as shown. 
     FIG. 17 provides an isometric of two square supply registers or exhaust grilles  81  mounted to the raised floor tile assembly  20  in lieu of the ductwork  61  previously shown. The square supply registers or exhaust grilles  81  can be installed with or without adjustable vanes to allow for the transfer of air without installing ductwork  61  or its associated hardware. 
     FIG. 18 provides an isometric of two round supply registers or exhaust grilles  81  mounted to the raised floor tile assembly  20  in lieu of the ductwork  61  previously shown. The square supply registers or exhaust grilles  81  can be installed with or without adjustable vanes to allow for the transfer of air without installing ductwork  61  or its associated hardware. 
     FIG. 19 provides an isometric of a supply air manifold  71  mounted to the raised floor tile assembly  20  in lieu of the ductwork  61  previously shown. The supply air manifold  71  can be connected to other supply air manifolds (as shown in the dashed lines) via removable manifold end caps  72 . In this embodiment, the manifold  71  is placed horizontally. In other embodiments, the manifold  71  or duct  61  may be placed at any angle to the floor or wall. 
     FIGS. 20 through 22 provide alternative air outlets for air distribution ducts  10  or supply air manifolds  71 . In FIG. 20, the outlets are supply air nozzles  16 . FIG. 21 shows the outlets as supply air linear vents  17 . FIG. 22 has supply air linear slits  18  as the outlets. 
     It will be readily apparent to those skilled in the air handling art that various modifications and changes can be made to the described air handling system without departing from the spirit and scope of this invention. For example, although the unit has been shown and described with a radial impeller fan, other types of fans, such as centrifugal or axial may be used. Accordingly, all such modifications and changes that fall within the scope of the appended claims are intended to be part of the present invention. 
     Reference Characters 
     H 1 —height of raised floor tile assembly (1.125″ on standard design, can be adjusted for special applications) 
     H 2 —height of air handling unit (6″ to 16″, depending on options) 
     H 3 —height of ServAire ductwork 
     W 1 —width of raised floor tile assembly (24″ on standard design, can be adjusted for special applications) 
     W 2 —width of air handling unit (20″ on standard design, can be adjusted for special applications) 
     L 1 —length of raised floor tile assembly (24″ on standard design, can be adjusted for special applications) 
     L 2 —length of air handling unit (20″ on standard design, can be adjusted for special applications) 
       10 . air distribution duct 
       11 . interstitial duct support clip 
       12 . band clamp 
       13 . vertical duct support clip 
       14 . vertical duct support arm/bracket 
       15 . horizontal duct support arm/bracket 
       16 . supply air nozzle(s) 
       17 . supply air linear vent(s) 
       18 . supply air linear slit(s) 
       20 . raised floor tile 
       21 . handle (optional, can be provided with other handle styles) 
       22 . controls access cover 
       23 . duct collar 
       24 . filter access cover 
       25 . tile plate 
       26 . tubular steel framing/reinforcement (can be modified/enhanced for special applications) 
       27 . control panel 
       28 . controls 
       29 . control panel opening 
       30 . air handling unit 
       31 . duct blank-off 
       32 . radial impeller fan 
       33 . inlet screen 
       34 . filter retainer screen 
       35 . air filter (can be disposable or re-usable) 
       36 . intake plenum 
       37 . inlet ring 
       38 . fan shroud 
       39 . air flow diverter 
       40 . fan motor 
       41 . chilled water coil 
       42 . condensate pan 
       43 . fan mounting bracket 
       44 . housing 
       45 . insulation 
       46 . alternate supply air opening 
       47 . primary supply air opening 
       48 . filter opening 
       50 . fan access cover 
       60 . raised floor air handling unit 
       61 . ductwork 
       62 . server rack 
       63 . exhaust air plenum of server rack 
       64 . raised floor tile system 
       65 . supply air plenum of server rack 
       66 . cool air distribution 
       67 . underfloor cool air plenum 
       68 . building floor 
       69 . underfloor air supply plenum box 
       70 . exhaust 
       71 . supply air manifold 
       72 . removable manifold end cap 
       80 . rectangular supply register or exhaust grille 
       81 . square supply register or exhaust grille 
       82 . round supply register or exhaust grille