Patent Publication Number: US-2004055322-A1

Title: Field replaceable packard refrigeration module with vapor chamber heat sink for cooling electronic components

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a refrigeration system for cooling electrical components. More particularly, the invention relates to a field and/or customer replaceable refrigeration module coupled to a vapor chamber heat sink that is suitable for use in standard electronic component environments.  
       BACKGROUND OF THE INVENTION  
       [0002] Electronic components, such as microprocessors and other various integrated circuits, have advanced in at least two significant ways. First, feature sizes have moved into the sub-micron range thereby allowing larger numbers of transistors to be formed on a given surface area. This in turn has resulted in greater device and circuit density on the individual chips. Second, in part due to the first advance discussed above, microprocessors have increased dramatically in clock speed. At present microprocessor speeds of 2.5 Gigahertz are coming to market and the 3 and 4 Gigahertz range is rapidly being approached.  
       [0003] As a result of the advances in device density and microprocessor speed discussed above, heat dissipation, which has always been a problem in the past, is rapidly becoming the limiting factor in microprocessor performance. Consequently, heat dissipation and cooling is now the foremost concern and the major obstacle faced by system designers.  
       [0004] As noted, heat dissipation has long been recognized as a serious problem limiting the performance of electronic components and systems. In the past, the solutions to the heat dissipation problem have been mostly limited to air-based cooling systems, with only the most exotic military, scientific and custom electronic systems employing the bulky and costly prior art liquid-based cooling solutions.  
       [0005] In the prior art, air-based cooling systems, such as heat sinks, cooling fins, heat pipes and fans, have been the systems of choice for several reasons. First, the air-based cooling systems of the prior art were modular and self-contained and were therefore field replaceable with minimal effort using standard tools. Second, the prior art air-based cooling systems attached directly to the components that needed cooling and a discrete cooling unit could be provided for each heat source. In addition, air-based cooling systems were compact and simple in both operation and installation, with minimal parts to fail or break and minimal added system complexity. Therefore, prior art air-based cooling systems were reliable. In addition, and probably most importantly, in the prior art, air-based cooling systems could reasonably meet the cooling needs of electronic devices and systems so there was little motivation to move to the more complex and problematic liquid-based systems. However, as noted above, due to the advances in microprocessor speeds and device density, air-based cooling systems alone will most likely not be a viable option for electronic device cooling for the next generation of microprocessors.  
       [0006] As noted above, another possible prior art cooling system that could potentially provide the level of cooling required by the next generation of microprocessors is liquid-based cooling systems. Prior art liquid-based cooling systems typically used a refrigerant, such as R134A, that was circulated by a compressor. In prior art liquid-based cooling systems the compressor was typically a crankshaft reciprocating compressor or a rotary compressor similar to those used in home refrigerators.  
       [0007] As noted above, prior art liquid-based cooling systems have far more potential cooling capability than air-based systems. However, in the prior art liquid-based cooling systems, the crankshaft reciprocating or rotary compressors were typically, by electronics industry standards, very large, on the order of tens of inches in diameter, very heavy, on the order of pounds, and often required more power to operate than the entire electronic system they would be charged with cooling. In addition, the size and design of prior art liquid-based cooling systems often required that the major components of the prior art liquid-based cooling system be centrally located, typically remote from the electronic devices to be cooled, and that a complicated system of tubing or “plumbing” be used to bring the cooling liquid into thermal contact with the heat source, i.e., with the microprocessor or other integrated circuit. Consequently, unlike prior art air-based cooling systems, prior art liquid-based cooling systems were not modular, were not self-contained, and often required special expertise and tools for maintenance and operation. In addition, unlike the prior art air-based cooling systems discussed above, prior art liquid-based cooling systems did not attach directly to the components that needed cooling and a discrete cooling unit typically could not be provided for each heat source. Also, unlike the prior art air-based cooling systems discussed above, prior art liquid-based cooling systems were not compact and were not simple in either operation or installation. Indeed, prior art liquid-based cooling systems typically included numerous parts which could potentially fail or break. This added complexity, and threat of component failure, was particularly problematic with respect to the associated plumbing discussed above because a failure of any of the tubes could result in the introduction of liquid refrigerant into, or onto, the electronic devices and could cause catastrophic system failure.  
       [0008] In addition, prior art liquid-based cooling systems employed compressors that typically were highly orientation dependent, i.e., they could not operate at angles of more than 30 or 40 degrees. Consequently, prior art liquid based cooling systems were particularly ill suited for the electronics industry that stresses flexibility and often requires orientation independent operation.  
       [0009] Given that, as discussed above, air-based cooling systems have reached their operational limits when it comes to cooling electronic components, there is a growing realization that some other form of cooling system, such as liquid-based cooling systems will need to be adopted by the electronics industry. However, as discussed above, prior art liquid-based cooling systems are far from ideal and, thus far, the industry has not adopted liquid-based cooling in any meaningful way because the problems associated with prior art liquid-based cooling systems are still thought to outweigh the advantages these systems provide in terms of increased cooling capacity.  
       [0010] What is needed is a cooling system that has the cooling capacity of a liquid-based cooling system yet has the advantages of being modular, simple, and compact like air-based cooling systems.  
       SUMMARY OF THE INVENTION  
       [0011] The present invention is directed to a field and/or customer replaceable packaged refrigeration module with vapor chamber heat sink that is suitable for use in standard electronic component environments. According to the present invention, advances in compressor technology are incorporated in a field replaceable packaged refrigeration module that is coupled to a vapor chamber heat sink cold plate evaporator to be used for cooling electronic components. According to the invention, the field replaceable packaged refrigeration module is self-contained and is specifically designed to have physical dimensions similar to those of a standard air-based cooling system, such as a fined heat sink or heat pipe.  
       [0012] In one embodiment of the invention, the addition of the field replaceable packaged refrigeration module to a vapor chamber heat sink serves to create a system wherein the vapor chamber heat sink is used to passively cool the heat source and the field replaceable packaged refrigeration module is used to lower, or maintain, the base temperature of the vapor chamber heat sink. Consequently, the field replaceable packaged refrigeration module can be operated intermittently, on an as needed basis, to minimize the power used by the system and to minimize the wear and tear of the moving parts. The net result is the ability to manage and remove heat from the heat source while saving energy since the field replaceable packaged refrigeration module does not need to operate at all times. Consequently, the use of a vapor chamber heat sink with the field replaceable packaged refrigeration module allows for more cooling capability and more efficient cooling, lowered load on the field replaceable packaged refrigeration heat sink module, and a lower failure rate of the cooling system and its moving parts.  
       [0013] The present invention can be utilized in existing electronic systems and unlike prior art liquid-based cooling systems, the various parts of the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention, including the very minimal tubing, are largely self-contained in the field replaceable packaged refrigeration module with vapor chamber heat sink. Therefore a failure of any of the tubes would typically not result in the introduction of liquid into, or onto, the electronic devices and would not cause catastrophic system failure, as was the risk with prior art liquid-based cooling systems.  
       [0014] The field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention is a modified liquid-based cooling system and therefore provides the cooling capacity of a prior art liquid-based cooling systems. However, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is modular and largely self-contained and is therefore field and/or customer replaceable with minimal effort using standard tools. In addition, unlike prior art liquid-based cooling system, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention, in one embodiment, uses the passive, simple and low energy vapor chamber heat sink to perform the majority of the routine cooling, while providing the added cooling capacity of a liquid-based cooling system in the form of the intermittently operating field replaceable packaged refrigeration module. In another embodiment, the field replaceable packaged refrigeration module is positioned directly over the main heat source, such as a CPU, while the vapor chamber heat sink is used for smaller heat sources or secondary cooling. In addition, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is compact and simple in both operation and installation, with minimal parts to fail or break and minimal added complexity. Therefore, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is sturdy and reliable.  
       [0015] In one embodiment of the invention, a single vapor chamber heat sink is coupled to a single field replaceable packaged refrigeration module as a unit. In other embodiments of the invention, multiple vapor chamber heat sinks are coupled to, and serviced by a single field replaceable packaged refrigeration module mounted in a central location. In this way, single or multiple heat sources can be serviced by a single field replaceable packaged refrigeration module.  
       [0016] In addition, the field replaceable packaged refrigeration module portion of the present invention is specifically designed to be operational in any orientation. Consequently, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module portion of the present invention can be mounted, and operated, at any angle. This makes the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention particularly well suited for use with electronic systems.  
       [0017] As discussed briefly above, and in more detail below, the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention has the cooling capacity of a liquid-based cooling system and yet is modular, compact, simple in design and simple to use, like an air-based cooling system. Consequently, the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention can readily meet the cooling needs of the next generation of electronic devices and systems. As one example, when the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention is used to cool a microprocessor or CPU, the CPU can operate at a higher frequency and speed, thereby allowing the parent electronic system to fully utilize the advances in microprocessor technology discussed above.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018] The refrigeration system of the present invention will be described in the following detailed description, with reference to the accompanying drawings. In the drawings, the same reference numbers are used to denote similar components in the various embodiments.  
       [0019]FIG. 1 is a functional diagram of a field replaceable packaged refrigeration module designed according to the principles of one embodiment of the invention;  
       [0020]FIG. 2 is a longitudinal cross sectional view of an exemplary linear compressor that may be used in the field replaceable packaged refrigeration module depicted in FIG. 1 according to the principles of one embodiment of the invention;  
       [0021]FIG. 3 is a perspective view of a field replaceable packaged refrigeration module designed according to the principles of one embodiment of the invention;  
       [0022]FIG. 4 is cross sectional view of the field replaceable packaged refrigeration module of FIG. 3 shown mounted on an exemplary electrical component according to the principles of one embodiment of the invention;  
       [0023]FIG. 5 is a computer-generated representation of one embodiment of the field replaceable packaged refrigeration module of FIG. 3 according to the principles of one embodiment of the invention.  
       [0024]FIG. 6 is cross sectional view of one embodiment of a field replaceable packaged refrigeration module with vapor chamber heat sink according to the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION  
     [0025] The field replaceable packaged refrigeration module with vapor chamber heat sink ( 600  in FIG. 6) of the present invention has the advantageous cooling capacity of a prior art liquid-based cooling system, yet, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention is suitable for use in standard electronic component environments.  
     [0026] In one embodiment of the invention, the addition of the field replaceable packaged refrigeration module ( 660  in FIG. 6) to a vapor chamber heat sink ( 690  in FIG. 6) serves to create a system wherein the vapor chamber heat sink is used to passively cool the heat source ( 62  in FIG. 6) and the field replaceable packaged refrigeration module is used to lower, or maintain, the base temperature of the vapor chamber heat sink. Consequently, the field replaceable packaged refrigeration module can be operated intermittently, on an as needed basis, to minimize the power used by the system and to minimize the wear and tear of the moving parts. The net result is the ability to manage and remove heat from the heat source while saving energy since the field replaceable packaged refrigeration module does not need to operate at all times. In another embodiment, the field replaceable packaged refrigeration module is positioned directly over the main heat source, such as a CPU, while the vapor chamber heat sink is used for smaller heat sources or secondary cooling. Consequently, the use of a vapor chamber heat sink with the field replaceable packaged refrigeration module allows for more cooling capability and more efficient cooling, lowered load on the field replaceable packaged refrigeration module, and a lower failure rate of the cooling system and its moving parts.  
     [0027] The present invention can be utilized in existing electronic systems and unlike prior art liquid-based cooling systems, the various parts of the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention, including the very minimal tubing ( 694  and  696  in FIG. 6), are largely self-contained in the field replaceable packaged refrigeration module with vapor chamber heat sink. Therefore a failure of any of the tubes would typically not result in the introduction of liquid into, or onto, the electronic devices and would not cause catastrophic system failure, as was the risk with prior art liquid-based cooling systems.  
     [0028] In one embodiment of the invention, a single vapor chamber heat sink is coupled to a single field replaceable packaged refrigeration module as a unit. In other embodiments of the invention, multiple vapor chamber heat sinks are coupled to, and serviced by a single field replaceable packaged refrigeration module mounted in a central location. In this way, single or multiple heat sources can be serviced by a single field replaceable packaged refrigeration module.  
     [0029] The field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention is a modified liquid-based cooling system and therefore provides the cooling capacity of a prior art liquid-based cooling systems. However, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is modular and self-contained and is therefore field and/or customer replaceable with minimal effort using standard tools. In addition, unlike prior art liquid-based cooling system, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention, in one embodiment, uses the passive, air cooled, and low energy vapor chamber heat sink to perform the majority of the cooling, while providing the added cooling capacity of a liquid-based cooling system in the form of the intermittently operating field replaceable packaged refrigeration heat sink module.  
     [0030] In addition, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is compact and simple in both operation and installation, with minimal parts to fail or break and minimal added complexity. Therefore, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is sturdy and reliable.  
     [0031] In addition, the field replaceable packaged refrigeration module portion of the present invention is specifically designed to be operational in any orientation. Consequently, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module portion of the present invention can be mounted, and operated, at any angle. This makes the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention particularly well suited for use with electronic systems.  
     [0032]FIG. 1 is a functional diagram of a field replaceable packaged refrigeration module  10  designed according to one embodiment of the invention. Referring to FIG. 1, field replaceable packaged refrigeration module  10  includes a compressor  12 , a condenser  14 , an optional receiver  16 , an expansion device  18  and an evaporator  20 , all of which are connected together in refrigeration loop  22  through which a refrigerant, such as R134A, is circulated.  
     [0033] As also shown in FIG. 1, compressor  12 , condenser  14 , optional receiver  16 , expansion device  18  and evaporator  20 , in a refrigeration loop  22  are self-contained in field replaceable packaged refrigeration module  10 , as indicated by dashed line  11 .  
     [0034] In one embodiment of the invention, evaporator  20  is positioned in thermal contact with a heat source  24 , such as an electronic component, or the base of a vapor chamber heat sink, as discussed below, that is to be cooled. As is well understood by those of ordinary skill in the art, compressor  12  compresses the refrigerant (not shown) into a high-pressure, high temperature liquid that is then conveyed to condenser  14 . At condenser  14 , the refrigerant is allowed to cool before being conveyed to receiver  16 . From receiver  16 , the refrigerant passes through expansion device  18 , which may be, for example, a capillary tube, and into evaporator  20 . The liquid refrigerant evaporates in evaporator  20  and in the process absorbs heat from heat source  24  to produce the desired cooling effect. From evaporator  20  the refrigerant is drawn back into compressor  12  to begin another cycle through refrigeration loop  22 .  
     [0035] In accordance with the present invention, compressor  12  is one of several new generation compressors that are relatively small, on the order of 2.0 inches in diameter and 3 to 4 inches long. In one embodiment of the invention, compressor  12  is less than 1.7 inches in diameter and less than 4 inches long. One example of this new generation of compressors is the relatively new linear compressor now being used in the more standard refrigeration, i.e., non-electronics, industry. In one embodiment of the invention, compressor  12  is a linear compressor whose operation is controlled by drive circuit  26 .  
     [0036] As discussed in more detail with respect to FIG. 2, a linear compressor is a positive displacement compressor having one or more free floating pistons that are driven directly by a linear motor. Thus, a linear compressor differs from a conventional reciprocating and rotary compressor where the pistons are driven through a crankshaft linkage, or by a rotary motor through a mechanical linkage, respectively. Since the capacity of any compressor is directly related to the size and displacement of the pistons, a linear compressor can typically be made smaller than a crankshaft reciprocating or rotary compressor but can maintain the same capacity since the displacement of the pistons is not dependent on the size of a mechanical linkage. In addition, since a linear compressor usually comprises fewer moving parts than a crankshaft reciprocating or rotary compressor, the linear compressor is typically quieter than a crankshaft reciprocating or rotary compressor. Furthermore, since the pistons of a double-piston linear compressor move in opposition to one another, the reaction forces of the pistons will cancel each other out and the vibrations that are commonly experienced with crankshaft reciprocating or rotary compressors will consequently be suppressed. Consequently, linear compressors offer many advantages over a crankshaft reciprocating compressor or a rotary compressor for application as compressor  12  in field replaceable packaged refrigeration module  10 .  
     [0037] The linear compressors suitable for use as compressor  12  in field replaceable packaged refrigeration module  10  can be any of a variety of single, double or multiple-piston linear compressors that are known in the art. For example, in one embodiment of the invention, linear compressor  12  is a single-piston linear compressor of the type disclosed in U.S. Pat. No. 5,993,178, which is hereby incorporated herein by reference, or a double-piston linear compressor of the type disclosed in U.S. Pat. No. 6,089,836 or U.S. Pat. No. 6,398,523, all of which are hereby incorporated herein by reference.  
     [0038] Referring to FIG. 2, an exemplary linear compressor  120 , suitable for use as compressor  12  in FIG. 1, comprises a housing  28 , first and second cylinders  30 ,  32  which are connected to, or formed integrally with, housing  28 , and first and second pistons  34 ,  36  which are slidably received within first and second cylinders  30 ,  32 , respectively. The ends of housing  28  are, in one embodiment, hermetically sealed, such as by end plates  38 . In addition, each cylinder  30 ,  32  has an axial centerline CL that is, in one embodiment, coaxial with that of the other cylinder. Furthermore, housing  28  is, in one embodiment, constructed of a magnetically permeable material, such as stainless steel, and pistons  34 ,  36  are optimally constructed of a magnetically indifferent material, such as plastic or ceramic.  
     [0039] In the embodiment of exemplary linear compressor  120  shown in FIG. 2, each piston  34 ,  36  is driven within its respective cylinder  30 ,  32  by linear motor  40 . Each motor  40  includes a ring-shaped permanent magnet  42  and an associated electrical coil  44 . In the embodiment of an exemplary linear compressor  120  shown in FIG. 2, magnet  42  is mounted within housing  28  and coil  44  is wound upon a portion of piston  34 ,  36 . In one embodiment, magnet  42  is radially charged, and each motor  40  includes a cylindrical core  46  mounted within housing  28  adjacent magnet  42  to direct the flux lines (not shown) from magnet  42  across coil  44 . In one embodiment, coil  44  is energized by an AC current, from drive circuit  26  (FIG. 1), over a corresponding lead wire (not shown). In one embodiment of the invention, drive circuit  26  is programmed such that, when the AC current is applied to coils  44  (FIG. 2), pistons  34 ,  36  will reciprocate toward and away from each other along the axial centerline CL of cylinders  30 ,  32 . In another embodiment, DC current is applied. In one embodiment, spring  48 , or similar means, may be connected between each piston  34 ,  36  and adjacent end plate  38  to aid in matching the natural frequency of piston  34 ,  36  to the frequency of the current from drive circuit  26  (FIG. 1).  
     [0040] The embodiment of an exemplary linear compressor  120  shown in FIG. 2 also includes a compression chamber  50  located within cylinders  30 ,  32 , between pistons  34 ,  36 . During the expansion portion of each operating cycle of linear compressor  120 , motors  40  will move pistons  34 ,  36  away from each other. This will cause the then gaseous refrigerant within evaporator  20  (FIG. 1) to be drawn into compression chamber  50  (FIG. 2), through an inlet port  52  in housing  28 . During the successive compression portion of the operating cycle of exemplary linear compressor  120 , motors  40  will move pistons  34 ,  36  toward each other. Pistons  34 ,  36  will consequently compress the then gaseous refrigerant within compression chamber  50  into a liquid and eject it into condenser  14  (FIG. 1), through an outlet port  54  (FIG. 2) in housing  28 . In one embodiment, suitable check valves  56 ,  58  are provided in inlet and outlet ports  52 ,  54 , respectively, to control the flow of refrigerant through inlet and outlet ports  52 ,  54  during the expansion and compression portions of each operating cycle.  
     [0041] While a specific embodiment of a field replaceable packaged refrigeration module  10  is discussed above that includes exemplary linear compressor  120 , those of skill in the art will recognize that the choice of a linear compressor, or any particular compressor, for use as compressor  12  in the discussion above was made for illustration simplicity and to avoid detracting from the invention by describing multiple specific embodiments at one time. In other embodiments of the invention appropriately sized rotary compressor, or other type of compressor, can be used as compressor  12 . For instance, in various embodiments of the invention, compressor  12  can be: a reciprocating compressor; a Swash-plate compressor; a rolling piston compressor; a scroll compressor; a rotary vane compressor; a screw compressor; an aerodynamic-turbo compressor; an aerodynamic-axial compressor; or any other reciprocating, volumetric or aerodynamic compressor known in the art, or developed after this application is filed. Consequently, the present invention should not be read as being limited the particular embodiments discussed above using linear, or any specific, compressor types.  
     [0042] Consequently, the present invention should not be read as being limited the particular embodiments discussed above using linear, or any specific, compressor types.  
     [0043] In one embodiment of the invention, a single vapor chamber heat sink ( 690  in FIG. 6) is coupled to a single field replaceable packaged refrigeration module  10  as a unit. In other embodiments of the invention, multiple vapor chamber heat sinks ( 690  in FIG. 6) are coupled to, and serviced by a single field replaceable packaged refrigeration module  10  mounted in a central location. In this way, single or multiple heat sources can be serviced by a single field replaceable packaged refrigeration module. In addition, according to the principles of the invention, field replaceable packaged refrigeration module can be readily adapted for use in cooling one or more integrated circuits that are mounted on a single circuit board and are part of a larger electronic system. For example, in many computer servers a number of integrated circuits are mounted on a single circuit board that, in turn, is housed within an enclosure/cabinet or “rack unit”, and a number of such rack units are, in turn, mounted in corresponding racks that are supported in the housing of the server.  
     [0044] In accordance with one industry standard, each rack unit has a height of only 1.75 inches. This fact makes use of prior art liquid-based cooling systems extremely difficult, if not impossible, and makes the extensive, and potentially disastrous, plumbing, discussed above, a system requirement. In contrast, a single, or even multiple, field replaceable packaged refrigeration heat sink modules  10 , designed according to the principles of the invention, can be positioned within the housing of the server, and/or on the rack units, to directly cool the integrated circuits that are located within or on the rack units or to provide additional cooling for vapor chamber heat sinks ( 690  in FIG. 6) cooling the integrated circuits that are located within or on the rack units. Consequently, in one embodiment of the invention, field replaceable packaged refrigeration heat sink modules  10 , designed according to the invention, are housed within a small scale cooling unit that can be located within each rack unit and connected directly to cool each integrated circuit or vapor chamber heat sink as needed.  
     [0045] One example of a physical implementation of the functional diagram of a field replaceable packaged refrigeration module  10  of FIG. 1 is shown as field replaceable packaged refrigeration module  60  of FIG. 3, FIG. 4 and FIG. 5. As shown in FIGS. 3 and 4, according to one embodiment of the invention, field replaceable packaged refrigeration module  60  is positioned adjacent an integrated circuit  62  that is mounted on a circuit board  64  or a vapor chamber heat sink ( 690  in FIG. 6) mounted on integrated circuit  62  on a circuit board  64 . As discussed above, in accordance with one embodiment of the invention, field replaceable packaged refrigeration module  60  is sized such that, when positioned as shown in FIG. 4, field replaceable packaged refrigeration module  60  will fit within a rack unit of a conventional computer server or a telecommunications rack. In one embodiment of the invention, field replaceable packaged refrigeration module  60  has a length  301  (FIG. 3) of approximately 6 inches, a width  303  of approximately 4 inches, and a height  305  of approximately 1.75 inches. In another embodiment of the invention, field replaceable packaged refrigeration module  60  has a length  301  of approximately 5 inches, a width  303  of approximately 4 inches, and a height  305  of approximately 1.75 inches. Of course, those of skill in the art will recognize that length  301 , width  303  and height  305  of field replaceable packaged refrigeration module  60  can be varied to meet the needs of specific applications.  
     [0046] As shown in FIG. 3, in one embodiment of the invention, field replaceable packaged refrigeration module  60  includes a housing  66  which has generally open front and back sides  68 ,  70 , a conventional air-cooled condenser  14 , which is mounted within housing  66  between open front and back sides  68 ,  70 , a compressor  12  which is connected to housing  66  by a suitable bracket  72 , and an evaporator  20  which is connected to housing  66 , below condenser  14 . As discussed above, in one embodiment of the invention, compressor  12  is a linear compressor driven by a drive circuit (not shown) in a manner similar to that discussed above. In one embodiment of the invention, evaporator  20  is a conventional cold plate-type evaporator that is thermally coupled to the top of integrated circuit  62  (FIG. 4) by either custom or conventional means. As discussed in more detail below, in another embodiment of the invention, field replaceable packaged refrigeration module  60  is coupled to the evaporator ( 620  in FIG. 6) of a vapor chamber heat sink ( 690  in FIG. 6) by either custom or conventional means. In one embodiment of the invention, condenser  14  is cooled by a flow of air from a system fan (not shown) that is mounted in the housing (not shown) of the server (not shown). In addition, in one embodiment of the invention, field replaceable packaged refrigeration module  60  is connected to circuit board  64  with a number of standoffs  74  and screws  76 .  
     [0047] During the normal operation of field replaceable packaged refrigeration module  60 , relatively high-pressure liquid refrigerant from compressor  12  is conveyed through a conduit  76  to condenser  14 . In one embodiment of the invention, the high-pressure liquid refrigerant is cooled in condenser  14  by the flow of air from a system fan (not shown). The refrigerant is then conveyed through a capillary tube  78  to evaporator  20 . The refrigerant evaporates in evaporator  20  and in the process absorbs heat from integrated circuit  62  to thereby cool integrated circuit  62  (FIG. 4). The now gaseous refrigerant is then drawn back into compressor  12  through conduit  80 . This cycle is then repeated as required to produce a desired cooling effect for integrated circuit  62 .  
     [0048]FIG. 5 is a computer-generated representation of one embodiment of field replaceable packaged refrigeration module  60  of FIG. 3 and FIG. 4 and therefore represents a computer-generated representation of a physical implementation of the functional diagram of field replaceable packaged refrigeration module  10  of FIG. 1. Shown in FIG. 5 are: condenser  14 ; compressor  12 ; evaporator  20 ; and tubing  501 . It is worth noting that tubing  501  is relatively minimal and, is therefore, a substantial improvement over the extensive “plumbing” associated with prior art liquid-based cooling systems. Indeed, unlike prior art liquid-based cooling systems, the various parts of field replaceable packaged refrigeration module  60  of the invention, including the very minimal tubing  501 , are self-contained in field replaceable packaged refrigeration module  60  and therefore a failure of any of the tubes  501  would typically not result in the introduction of liquid into or onto the electronic devices ( 62  in FIG. 4) and would not cause the catastrophic system failure that was the risk associated with prior art liquid-based cooling systems.  
     [0049] As noted above, it is highly desirable to provide a cooling system that uses minimal power and has a large thermal inertia. In these applications, a passive refrigeration sub-system is coupled with the field replaceable packaged refrigeration module discussed above to yield a hybrid system that is more power efficient than the field replaceable packaged refrigeration module used alone.  
     [0050]FIG. 6 is cross sectional view of one embodiment of a field replaceable packaged refrigeration module with vapor chamber heat sink  600  according to the principles of the present invention. As shown in FIG. 6, according to one embodiment of the invention, field replaceable packaged refrigeration module  660  is coupled by capillary tubing  694  to a cold plate evaporator  620  of a vapor chamber heat sink  690  positioned adjacent a heat source  62 , such an integrated circuit or CPU. As discussed above, in accordance with one embodiment of the invention, field replaceable packaged refrigeration module  660 , and field replaceable packaged refrigeration module with vapor chamber heat sink  600 , is sized such that, when positioned as shown in FIG. 6, field replaceable packaged refrigeration module  660  will fit within a rack unit of a conventional computer server or a telecommunications rack.  
     [0051] As shown in FIG. 6, in one embodiment of the invention, field replaceable packaged refrigeration module  660  includes a conventional air-cooled condenser  614  coupled to a compressor  612  by tubing  696 . As discussed above, in one embodiment of the invention, compressor  612  is a linear compressor driven by a drive circuit (not shown) in a manner similar to that discussed above. In one embodiment of the invention, condenser  614  is cooled by a flow of air from a system fan (not shown) that is mounted in the housing (not shown) of the server (not shown).  
     [0052] As also shown in FIG. 6, vapor chamber heat sink  690  includes a cold-plate evaporator  620 . In one embodiment of the invention, cold-plate evaporator  620  is a conventional cold plate-type evaporator that is thermally coupled to the top of heat source  62  by conventional means. As shown in FIG. 6, in one embodiment of the invention, vapor chamber heat sink  690  also includes: vapor container  691 , holding a refrigerant such as R134A; wick structure  693 ; and vapor chamber heat sink heat sink  695 .  
     [0053] In one embodiment of the invention, cold plate evaporator  620  of vapor chamber heat sink  690  is coupled to field replaceable packaged refrigeration module  660  by capillary tubes  694 . Vapor chambers, such as vapor chamber heat sink  690 , and their operation is well known in the art. Therefore, a detailed description of vapor chamber heat sink  690  is omitted here to avoid detracting from the invention.  
     [0054] The addition of the field replaceable packaged refrigeration module  660  to vapor chamber heat sink  690  serves to create a system  600  wherein vapor chamber heat sink  690  is used to passively cool heat source  62  and field replaceable packaged refrigeration module  660  is used to lower, or maintain, the base temperature of vapor chamber heat sink  690 . Consequently, field replaceable packaged refrigeration module  660  can be operated intermittently, on an as needed basis, to minimize the power used by field replaceable packaged refrigeration module with vapor chamber heat sink  600  and to minimize the wear and tear of the moving parts. The net result is the ability to manage and remove heat from heat source  62  while saving energy since field replaceable packaged refrigeration module  660  does not need to operate at all times.  
     [0055] In one embodiment of the invention, a temperature sensor (not shown) is used to monitor the temperature of a component, such as cold plate evaporator  620  or vapor container  691  of vapor chamber heat sink  690  or a surface of heat source  62 . In one embodiment of the invention, when a predetermined “maximum” base temperature is exceeded, compressor  612  of field replaceable packaged refrigeration module  660  is started, typically via a switch (not shown), and field replaceable packaged refrigeration module  660  operates until the base temperature of vapor chamber heat sink  690  is lowered to a predetermined level. Consequently, the use of vapor chamber heat sink  690  with field replaceable packaged refrigeration module  660  allows for more cooling capability and more efficient cooling, lowered load on field replaceable packaged refrigeration module  660 , and a lower failure rate of field replaceable packaged refrigeration module with vapor chamber heat sink  600  and its moving parts.  
     [0056] In another embodiment of the invention, heat source  62  is a microprocessor whose activity is monitored by a monitoring device implemented in hardware or software (not shown). In this embodiment of the invention, when a predetermined activity level for the processor is reached, compressor  612  of field replaceable packaged refrigeration module  660  is started, typically via a switch (not shown), and field replaceable packaged refrigeration module  660  operates until the activity level of the processor drops below a predetermined level. Consequently, in this embodiment of the invention, field replaceable packaged refrigeration module with vapor chamber heat sink  600  tries to anticipate cooling needs and operates to provide the thermal reservoir to handle increases in activity before the heat is produced. Therefore, thermal spikes, and potential thermal damage to the processor and its performance are avoided.  
     [0057] In one embodiment of the invention, a single vapor chamber heat sink  690  is coupled to a single field replaceable packaged refrigeration module  660  as a unit  600 . In other embodiments of the invention, multiple vapor chamber heat sinks  690  are coupled to, and serviced by a single field replaceable packaged refrigeration module  660  mounted in a central location. In this way, single or multiple heat sources  62  can be serviced by a single field replaceable packaged refrigeration module.  
     [0058] As discussed above, the present invention is directed to a field and/or customer replaceable packaged refrigeration module with vapor chamber heat sink that is suitable for use in standard electronic component environments. The field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is largely self-contained and is specifically designed to have physical dimensions similar to those of a standard air-based cooling system, such as a fined heat sink or heat pipe. As a result, the present invention can be utilized in existing electronic systems without the need for board or rack/cabinet modification or the “plumbing” associated with prior art liquid-based cooling systems.  
     [0059] As also discussed above, the use of a field replaceable packaged refrigeration module with a vapor chamber heat sink serves to lower the base temperature of the vapor chamber heat sink and so allows intermittent operation of the field replaceable packaged refrigeration module. The net result is the ability to manage and remove heat from the heat source while saving energy since the field replaceable packaged refrigeration module does not need to operate at all times. Consequently, the use of a vapor chamber heat sink with the field replaceable packaged refrigeration module allows for more efficient cooling, lowered load on the field replaceable packaged refrigeration heat sink module, and a lower failure rate of the cooling system and its moving parts.  
     [0060] In addition, since the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is a modified liquid-based cooling system, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention provides the cooling capacity of prior art liquid-based cooling systems. However, like prior art air-based cooling systems, the field replaceable packaged refrigeration module with vapor chamber heat sink of the invention is modular and largely self-contained and is therefore field and/or customer replaceable with minimal effort using standard tools.  
     [0061] In addition, the field replaceable packaged refrigeration module used with the present invention is self contained and specifically designed to be operational in any orientation. Consequently, unlike prior art liquid-based cooling systems, the field replaceable packaged refrigeration module portion of the present invention can be mounted, and operated, at any angle. This makes the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention particularly well suited for use with electronic systems.  
     [0062] As a result of the features of the present invention discussed in detail above, the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention provides the cooling capacity of a liquid-based cooling system and yet is modular, compact, simple in design, and simple to use, like an air-based cooling system. Consequently, the field replaceable packaged refrigeration module with vapor chamber heat sink of the present invention can meet the cooling needs of the next generation of electronic devices and systems and can make further speed and device density improvements in microprocessor design a workable possibility.  
     [0063] It should be recognized that, while the present invention has been described in relation to the specific embodiments thereof discussed above, those skilled in the art may develop a wide variation of structural and operational details without departing from the principles of the invention.  
     [0064] As one example, the choice of a linear compressor, or any particular linear compressor, for use as compressor  612  in the discussion above was made for illustration simplicity and to avoid detracting from the invention by describing multiple specific embodiments at one time. In other embodiments of the invention, appropriately sized rotary compressors, or other compressors, can be used as compressor  612 . For instance, in various embodiments of the invention, compressor  612  can be: a reciprocating compressor; a swash-plate compressor; a rolling piston compressor; a scroll compressor; a rotary vane compressor; a screw compressor; an aerodynamic-turbo compressor; an aerodynamic-axial compressor; or any other reciprocating, volumetric or aerodynamic compressor known in the art, or developed after this application is filed. Consequently, the present invention should not be read as being limited the particular embodiments discussed above using linear, or any specific, compressor types.  
     [0065] As another example, specific dimensions were discussed above as examples of possible values for length  301 , width  303  and height  305  of field replaceable packaged refrigeration module  60  or  660 . Those of skill in the art will recognize that length  301 , width  303  and height  305  of field replaceable packaged refrigeration module  60  or  660  can be varied for specific applications and that the present invention should not be read as being limited the particular embodiments discussed above with the particular dimensions discussed by way of illustration.