Abstract:
The disclosure provides an improved cooling system and associated cabinet for electronic equipment, and optionally, a backup ventilation system for cooling related failures. Generally, the disclosure includes a high capacity closed loop refrigeration system in a modified cabinet, while accommodating standard sized computer equipment. Further, the system provides directed heat removal by altering typical airflow paths within the cabinet. The backup ventilation system is powered by auxiliary power in the case of power failure and uses the same fan(s) for ventilation as is used for cooling. The disclosure provides a more efficient, higher capacity cooling cabinet in less space than otherwise known in the art. Further, the cooling system can anticipate heat loads and therefore operate in a predictive capacity by monitoring input power to the electronic equipment and adjusting the cooling for the expected increase or decrease in heat load generated based on the input power.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This patent claims the benefit of U.S. Provisional Appl. No. 60/705,339 filed Aug. 4, 2005. 
     
    
     FIELD  
       [0002]     The present invention relates generally to electronic equipment cabinets and housings, and, more particularly to electronic equipment cabinets having cooling systems.  
       BACKGROUND  
       [0003]     With the expansion of telecommunication and computer technology, increasing amounts of electronic equipment are required at businesses and other facilities. Large amounts of electronic equipment are often stored in a room devoted to that purpose. As shown in  FIG. 1 , the equipment is generally organized in a cabinet  2  of standard dimensions with multiple horizontal trays  4  to support multiple rows of equipment. The cabinet  2  generally includes sides,  6 , back  8 , top  10 , bottom  12 , and a door  14  to gain access to the equipment therein. Power rails, uninterruptible power supplies, and other features can be included. This equipment generates heat, which must be removed from the room in order to maintain stable conditions in the rooms. Because advances in technology have lead to an increased density of the amount of electronic equipment that can be provided in a set amount of space, it has become increasingly difficult to remove this heat by means of the conventional room air conditioning alone. Therefore, it is often necessary to install localized cooling for the cabinets that house this electronic equipment.  
         [0004]     General purpose cooling systems for rooms and open spaces are often inadequate for single racks of critical electronic equipment. Cooling systems designed for room size data centers may be adequate for overall critical equipment needs in the data centers, but are often too large for single stacks of equipment in a single cabinet. Such cooling systems generally use an external connection for heat rejection, for example, with chilled water or a cooling tower.  
         [0005]     Some existing commercial suppliers have provided a closed loop refrigerated cooling system coupled to the cabinets. The refrigeration system typically includes a compressor for compressing refrigerant in the system to an elevated pressure, a condenser to cool the refrigerant that is heated by the act of compression, an expansion device that thermodynamically cools the refrigerant, an evaporator that is cooled by the cooled refrigerant flowing therethrough, a fan to move air across the evaporator&#39;s surfaces to cool the air whereby the refrigerant in turn absorbs heat from the warmer air, various refrigeration lines for carrying the refrigerant between the components, and a system controller, such as a thermostat. These systems are generally mounted in the bottom or on top of the cabinet. A typical cabinet is about 24″ wide and 78″ to 84″ high. The cooling module can consume about 12″-15″ in the bottom of the cabinet or add such amount to the overall height if mounted on top of the cabinet.  
         [0006]     While these systems have been well received in the marketplace, they were designed for cooling capacities of electronic equipment up to about 3.0 KW. The cooling capacity of these existing electronic equipment cabinets with self-contained cooling solutions are insufficient for some newer computing devices, which consume more power and produce higher levels of heat. Some of the power requirements require a cooling capacity many times the existing amounts approaching an order of magnitude change, such as 10 KW to 15 KW. Simply making the cooling system bigger would consume about half of the cabinet space or, if mounted on the top, would cause clearance problems with room ceilings-both commercially unsatisfactory solutions.  
         [0007]     Also, existing computer equipment cabinets with built-in cooling coils and fans do not provide satisfactory means of ventilation when the cooling system fails. These existing solutions typically use cabinet doors designed to open outwardly automatically for ventilation if there is a failure in the cooling system. However, such systems are subject to doors being blocked, rendering the emergency cooling means ineffective. One known backup solution is mounted to a vertical portion of the cabinet with a damper that opens inwardly. Air flows downwardly, across the bottom of the unit, up the wall opposite the entering wall, across the top, down the entering wall, and out an exit. The damper is limiting and the length of the airflow causes inefficient removal of the generated heat.  
         [0008]     Another challenge with existing electronic equipment cabinets with built-in cooling coils and fans is that they typically do not respond quickly to large, instantaneous changes in heat load. The cooling system senses the heat after the heat has been generated and then attempts to compensate by extra cooling to lower the temperature back down to an intended set point. The cooling system is therefore responsive to thermal heat after it has been produced. The result can be a wide fluctuation of temperatures in the cabinet, as the cooling system&#39;s control system responds to the load change.  
         [0009]     Therefore, there remains a need for an improved cooling system for electronic equipment cabinets.  
       SUMMARY  
       [0010]     The disclosure provides an improved cooling system and associated cabinet for electronic equipment, and optionally, a backup ventilation system for power failures and other cooling related failures. Generally, the disclosure includes a high capacity closed loop refrigeration system in a modified cabinet, while accommodating standard sized computer equipment. Further, the system provides directed heat removal by altering typical airflow paths within the cabinet. The backup ventilation system can be powered by auxiliary power in the case of power failure and uses the same fan(s) for ventilation as is used for cooling. The disclosure provides a more efficient, higher capacity cooling cabinet in less space than otherwise known in the art. Further, the cooling system can anticipate heat loads and therefore operate in a predictive capacity by monitoring input power to the electronic equipment and adjusting the cooling for the expected increase or decrease in heat load generated based on the input power.  
         [0011]     The disclosure provides a cooling system for electronic equipment, comprising: a closed loop refrigeration system comprising a compressor, a condenser coupled to the compressor, an expansion device coupled to the condenser, an evaporator coupled to the expansion device and to the compressor, and a cooling system controller adapted to control operation of the refrigeration system, the refrigeration system being coupled to the cabinet; a cabinet having a width, depth, and height, the cabinet comprising: a first portion having a plurality of horizontal spaces adapted to contain electronic equipment; and a second portion extending at least partially along the height of the cabinet and adapted to house the evaporator, wherein the evaporator extends at least partially along the height; and at least one fan adapted to flow air through a first flow path through the evaporator in a circumferential horizontal direction around at least a partial periphery of the first portion and through the second portion.  
         [0012]     The disclosure also provides a method of controlling temperature in an electronic equipment cabinet having a closed loop refrigeration system coupled thereto, comprising: compressing and heating a refrigerant in the closed loop refrigeration system coupled to the cabinet; flowing the refrigerant into a condenser of the refrigeration system; flowing the refrigerant through an expansion device to cool the refrigerant; flowing the refrigerant through an evaporator and flowing air across surfaces of the evaporator to cool the air and heat the refrigerant; flowing the cooled air into the cabinet through a first flow path having a plurality of horizontal flow streams at different elevations in the cabinet across heated surfaces of the electronic equipment, the cooled air flowing in a circumferential horizontal direction around a periphery of the cabinet; and returning at least a portion of the refrigerant for compressing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     A more particular description, briefly summarized above, may be had by reference to the embodiments illustrated in the appended drawings, forming part of the present specification and described herein. It is to be noted, however, that the appended drawings illustrate only some embodiments described herein and are therefore not to be considered limiting of the disclosure&#39;s scope, in that there can be other equally effective embodiments.  
         [0014]      FIG. 1  is a perspective view of an existing stack of cabinets to support electronic equipment.  
         [0015]      FIG. 2  is a schematic frontal perspective view of an exemplary embodiment of a cooling system for electronic equipment, according to the present disclosure.  
         [0016]      FIG. 3  is a schematic frontal perspective view of different flow paths and elements of the cooling system of  FIG. 2 .  
         [0017]      FIG. 4  is a schematic rearward perspective view of different flow paths and elements of the cooling system.  
         [0018]      FIG. 5  is a schematic top view of an exemplary flow path in the cooling system through a horizontal cross section of the embodiment shown in  FIG. 4 .  
         [0019]      FIG. 6  is a schematic side view of an alternate exhaust flow path in the cooling system through a vertical cross section of the embodiment shown in  FIG. 4 . 
     
    
     DETAILED DESCRIPTION  
       [0020]      FIG. 2  is a schematic frontal perspective view of an exemplary embodiment of a cooling system for electronic equipment, according to the present disclosure. A cooling system  20  for electronic equipment generally includes a cabinet to support the electronic equipment and a refrigeration system described with its various elements below.  
         [0021]     The cabinet  22  can include a first portion  24  to support the equipment, a second portion  26  to enclose a portion of the refrigeration system such as a compressor and an evaporator, and a third portion  28  that can include a condenser and an exhaust fan. In at least one embodiment, the second portion is disposed horizontally to the first portion, such as to the side, and the third portion is disposed vertically to the first portion, such as above the first portion. The first portion  24  generally includes a series of horizontal spaces  30  disposed in the cabinet. The horizontal spaces can be pre-assembled with various racks and trays for mounting equipment, circuit boards, and other electronic equipment. Alternatively, the horizontal spaces  30  can include mounting brackets and runners with, for example, pre-drilled openings to mount equipment. The cabinet  22  generally includes sides  32 , a back  34 , a top  36 , a bottom  38 , and a door  40  to gain access to the electronic equipment disposed therein. The door can include a security latch for restricted access. The system  20  can include a system indicator  42 . The system indicator  42  monitors, for example, temperature, humidity, voltage, and/or other operating aspects of the system  20  as may be desired. It can provide input to a system controller to control at least some of the conditions.  
         [0022]      FIG. 3  is a schematic frontal perspective view of different flow paths and elements of the cooling system of  FIG. 2 . The cooling system  20  includes a first portion  24 , a second portion  26 , and a third portion  28 . The first portion  24  contains and supports the electronic equipment exposed therein. The first portion can include one or more horizontal spaces  30 A,  30 B,  30 C,  30 D. The horizontal spaces are generally used to mount electronic equipment in a horizontal fashion thereon. The second portion  26  includes various refrigeration equipment and helps establish a first flow path  70  described below. The third portion  28  is used to flow air through a condenser and for exhaust from the system  20  of the condenser air.  
         [0023]     The refrigeration system  48  generally includes a series of components coupled together that use a refrigerant in a closed loop refrigeration cycle. The refrigeration system  48  can include a compressor  50 , a condenser  62  coupled to the compressor, an expansion device  54  coupled to the condenser, an evaporator  56  coupled on an inlet port to the expansion device and coupled on an output port to the compressor. The various components of the refrigeration system can be coupled together through intermediate refrigeration lines, such as refrigeration lines  52 ,  60 , and other lines as appropriate that flow the refrigeration therebetween. The system can further include a fan  58  for moving air through the evaporator, an exhaust fan  64  for moving air through the condenser, and a controller  66  with one or more valves  68  for flow control of refrigerant. The term “coupled,” “coupling,” and like terms are used broadly herein and can include any method or device for securing, binding, bonding, fastening, attaching, joining, inserting therein, forming thereon or therein, communicating, or otherwise associating, for example, mechanically, fluidicly, magnetically, electrically, chemically, directly or indirectly with intermediate elements, one or more pieces of members together and can further include integrally forming one functional member with another in a unitary fashion.  
         [0024]     In at least one embodiment, the compressor  50  can be disposed in the second portion  26 . In addition to being compactly installed therein, the cooled air in the second portion flowing past the compressor during operation can help cool the compressor. The compressor can be a fixed displacement compressor or advantageously a variable flow compressor, sometimes referred to as a modulated or digital scroll compressor. The variable flow compressor can allow the cooling system  20  to operate more efficiently in that the compressor can be modulated more closely to variable load conditions. For example, the modulation can be controlled by controlling the duty cycle of the compressor with a bypass valve that opens and closes to at least partially bypass the compression stage of the compressor.  
         [0025]     The condenser  62  is used to cool the refrigerant, heated by the compressor compressing the refrigerant. Generally, a second flow path  72  (a first flow path  70  being through the evaporator as described below) is established through the condenser by flowing air or other fluid across its surfaces and through an exhaust fan  64 . The condenser  62  can be subdivided into one or more modules, so that refrigerant can be selectively controlled to each of the modules to control the amount of cooling from the refrigerant and hence head pressure on the refrigeration system. The condenser  62  can include, therefore, modules  62 A,  62 B,  62 C.  
         [0026]     The expansion device  54 , such as an expansion valve, can expand the refrigerant to a lower pressure and thermodynamically cool the refrigerant. The cooled refrigerant flows from the expansion device to the evaporator  56 . The evaporator  56  is generally a heat exchanger that allows cool refrigerant flowing internally to the evaporator to cool warmer air or another medium flowing across the evaporator external surfaces. Conversely, the flowing medium transfers its higher heat into the refrigerant. In at least one embodiment, the evaporator  56  can be mounted vertically along the height of the cabinet  22 , so that air flows past the surfaces of the evaporator horizontally to align with the one or more fans.  
         [0027]     The air flowing past the evaporator  56  can enter an intake of one or more fans  58 . The fans  58  can then increase velocity of the flow toward a periphery of the cabinet  22  and particularly the first portion  24 . Further, the velocity from various fans can be varied, for example, by installing higher flow rate fans or otherwise controlling the fans&#39; capacities in particular areas that may generate more heat. For example, a higher flow rate fan near the upper portion of the cabinet may be appropriate where higher temperatures may exist. The flow path through the evaporator  56  and the fans  58  around at least the periphery of the cabinet  22  establishes a first flow path  70 . When the air is flowing at different elevations, for example, by using a plurality of fans, the first flow path can be divided into flow paths  70 A,  70 A, and  70 C, and others. The air can also flow through various interior portions of the first portion  24  across the electronic equipment.  
         [0028]     The evaporator  56  can be installed at a turn  74  in the first flow path, such as in a corner of the cooling system  20 . Generally, the evaporator will be sealingly disposed across the flow path of the second portion  26 . Installing the evaporator at the turn can advantageously accomplish at least two benefits. First, when the air turns, its velocity generally decreases due to turbulence and friction. The decreased velocity allows a longer contact time of the air with the cooled evaporator to transmit further cooling into the air. Secondly, the evaporator can be wider by being mounted across the hypotenuse of a triangle (as shown in  FIG. 5 ) and offer additional surface area by mounting it at the turn of the airflow. The refrigerant, heated after passing through the evaporator, flows to the compressor  58  for recompression.  
         [0029]     A controller  66  can be used to control the flow of refrigerant through the system, the operation of the compressor, the operation of the fans, and other operational factors. Further, the controller  66  can control one or more valves, such as valve  68 , that control the flow of refrigerant through the condenser and particularly through one or more of the condenser modules.  
         [0030]     One or more dampers can be included in the cooling system  20  to adjust the first and/or second flow paths. A first damper  80  can be installed in the first flow path  70  to allow fresh air into the first flow path as required. For illustrative purposes, the damper  80  is shown partially open with the edge of the evaporator  56  shown behind it. The relative positions are further seen in  FIG. 5 . The damper  80  can be mounted in proximity to the evaporator  56  at the turn  74 . A second damper  82  described in reference to  FIG. 4  can be mounted on an opposite flow side of the evaporator  56  from the first damper  80 . The second damper  82  can allow exhausting of the air flowing through the cooling system  40  in the first flow path  70 .  
         [0031]     Advantageously, the first and second dampers  80 ,  82  can be opened when main power to the cooling system is off, such as in a power failure, when the refrigeration system malfunctions, or other impediments to the cooling system&#39;s ability to cool under normal operating conditions (herein “cooling related failures”). The opening of one or more of the dampers can allow ambient air into the cabinet for some measure of cooling in such an event. Further, auxiliary power supply  78 , such as an uninterruptible power supply, can provide power to one or more of the fans  58 ,  64  to provide continued circulation of air during the power failure or other cessation of power to the cooling system  20 . An alternative first damper  84  can be disposed between the first portion  24  and the third portion  28  in conjunction with an alternative second damper  94 , shown in  FIG. 6 . The dampers  84 ,  94  can further be designed to open during a power failure and allow air to escape the first portion  24  through third portion  28 . Further, the exhaust fan  64 , coupled to the auxiliary power supply, can assist in evacuating warm air from the first portion  24  during such power failure or at other times.  
         [0032]     The cooling system  20  can further include a line power monitor  92 . The line power monitor  92  can monitor incoming power from a main line  90  that provides main power to the power outlets in the cabinet for the various electronic equipment disposed therein, and to the cooling system  20 . Advantageously, the line power monitor  92  can use changes in power flowing through the main line  90  to anticipate heat loads. For example, if an operating conditions occurs that requires more power by the electronic equipment, it will have a direct correlation on the amount of heat generated by the electronic equipment. The line power monitor  92  can signal such a change to the system controller  66  in anticipation of the heat load and increase the cooling capacity before the heat increase is actually sensed. In some embodiments, the signal from the line power monitor  92  can override a standard operating condition established in the cabinet through the controller  66 , such as one based on temperature in the cabinet. Conversely, the line power monitor  92  can signal when a reduced load occurs and provide such input to the system controller to decrease cooling capacity. Such variations in operating conditions can further be modulated when using a variable capacity compressor, described above.  
         [0033]      FIG. 4  is a schematic rearward perspective view of different flow paths and elements of the cooling system. Similar to  FIG. 3  but from a different viewpoint, a first flow path  70  is established through the cooling system  20  that flows through the second portion  26  and around a periphery of the first portion  24 . The compressor  50  can be mounted in the second portion along with refrigerant lines and the evaporator  56  (disposed behind the dampers  80 ,  82  in this view). For example, the evaporator can be mounted in a corner  86  of the cooling system  20  where a turn in the flow direction of the first flow path  70  occurs.  
         [0034]     The system discloses a highly efficient cooling system  20  that alters the typical flow path in such cabinets. Generally, existing cooling systems for electronic cabinets include a single main fan that flows air into the cooling system in a generally vertical direction that disperses across the various horizontal elevations, while incrementally losing heat as it flows vertically. Thus, some horizontal zones receive less cooling than others. Further, the return flow path is generally along a vertical surface distal from the first vertical surface where incoming air can be mixed with outgoing air through such a long return flow path.  
         [0035]     The present invention alters the flow paths in such a way to relatively quickly supply cool air to the horizontal surfaces in a more direct fashion. Further, the present disclosure can provide for a plurality of fans  58  at various elevations that can provide more intense and directed horizontal flow through the unit. The horizontal flow through the unit across the horizontal trays and horizontally mounted equipment is a relatively short direct path from the evaporator to the fans to the equipment. With a plurality of fans, such as stacked above each other, it is believed that a somewhat laminar airflow develops through at least a portion of the cabinet. Further, the cooling system allows for a generally larger evaporator with small space requirements (i.e., small footprint) by using a generally vertically oriented evaporator along the height of the cabinet and yet still direct flow therethrough to correspond with the desired horizontal flow.  
         [0036]      FIG. 5  is a schematic top view of an exemplary flow path in the cooling system through a horizontal cross section of the embodiment shown in  FIG. 4 . The cooling system  20  generally flows air through the second portion  26  by flowing through the evaporator  56 , through the fan  58 , around the periphery of the first portion  24 , and back through the evaporator  56  to establish the first flow path  70 . For efficiency, the evaporator  56  can be mounted at a turn  74  in the flow path  70 . Under other operating conditions, such as providing fresh air, one or more of the dampers  80 ,  82  can open. Under such circumstances, if both dampers  80 ,  82  were open the first flow path  70  would include air entering through the first damper  80 , circulating through the fan  58 , around the periphery of the first portion  24 , and out the second damper  82 . Advantageously, an auxiliary power supply (shown in  FIG. 3 ) can provide power to the one or more fans  58  to help circulation through the cabinet, when the main power is off The position of the first and/or second dampers  80 ,  82  can restrict flow across the evaporator  56  to encourage separation between the incoming air and the outgoing air.  
         [0037]      FIG. 6  is a schematic side view of an alternate exhaust flow path through a vertical cross section of the embodiment shown in  FIG. 4 . The condenser  62  can include one or more condenser modules  62 A,  62 B,  62 C for different operating conditions. For example, high heat loads may require refrigerant flow through all modules, and low heat loads may require only one module. The flow of refrigerant to each of the condenser modules can be turned on or off to maintain the desired conditions and resultant head pressure on the refrigeration system. This control can be accomplished by valves, such as solenoid valves and check valves, on various refrigeration lines to the condenser and/or condenser modules.  
         [0038]     The second flow path  72  can include exemplary flow path segments  72 A,  72 B,  72 C that correspond with flow through the exemplary condenser modules  62 A,  62 B,  62 C. Generally, the segments will converge and be exhausted through the exhaust fan  64 .  
         [0039]     Under some operating conditions, such as a power outage, an alternative first damper  84  can be disposed to automatically open and allow a flow path between the first portion  24  and the third portion  28 . An alterative second damper  94  can allow air or other another medium to flow into the first portion  24 . The air or other medium can flow through the first damper  84  into the third portion  28  to be exhausted therefrom. Further, auxiliary power can be provided to the exhaust fan  64 , such as through an uninterruptible power supply, generator, or other device to encourage the flow path therethrough.  
         [0040]     The condenser, exhaust fan, valves, and associated hardware can be mounted in the third portion  28  above the first portion  24  of the cabinet  22 . In other embodiments, the third portion  28  can be located remote from the first portion  24 , such as the condenser  62  being located external to a room containing the cabinet  22 . Still further, the condenser  62  can be a liquid-liquid type condenser that is cooled by a liquid such as water and glycol mixtures through a separate flow path in the condenser isolated from the refrigerant. In turn, the liquid can be then cooled by a second condenser (not shown), such as external air-cooled condenser coupled to the separate flow path.  
         [0041]     The various steps described or claimed herein can be combined with other steps, can occur in a variety of sequences unless otherwise specifically limited, various steps can be interlineated with the stated steps, and the stated steps can be split into multiple steps. Unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, should be understood to imply the inclusion of at least the stated element or step or group of elements or steps or equivalents thereof, and not the exclusion of any other element or step or group of elements or steps or equivalents thereof. Also, any directions such as “top,” “bottom,” “left,” “right,” “upper,” “lower,” and other directions and orientations are described herein for clarity in reference to the figures and are not to be limiting of the actual device or system or use of the device or system. The device or system may be used in a number of directions and orientations.  
         [0042]     The invention has been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intends to protect all such modifications and improvements to the full extent that such falls within the scope or range of equivalent of the following claims.  
         [0043]     Further, any documents to which reference is made in the application for this patent as well as all references listed in any list of references filed with the application are hereby incorporated by reference. However, to the extent statements might be considered inconsistent with the patenting of this invention such statements are expressly not to be considered as made by the Applicants.