Patent Publication Number: US-2005123418-A1

Title: Compact compressors and refrigeration systems

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 60/527,798, entitled COMPACT REFRIGERATION SYSTEMS AND HEAT EXCHANGERS, filed on Dec. 8, 2003, assigned to the assignee of the present patent application, the disclosure of which is expressly incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to compact, modular cooling systems, and in particular, to compact compressors and refrigeration systems for electronic equipment cooling.  
      2. Description of the Related Art  
      Conventional refrigeration systems are typically semi-permanent or permanent systems. For example, in a typical refrigerator, it is not necessary to be able to independently move the refrigeration components with respect to the rest of the refrigerator and the components of such refrigeration systems are permanently installed in the refrigerator. In the quickly changing electronics industry, however, it would be useful to have a compact modular cooling unit mounted in thermal communication with a piece of electronic equipment that the user can independently install and remove.  
      Also, as electronic equipment has become increasingly smaller, the heat dissipation requirements of such equipment is exceeding the capacity of cooling systems which employ only forced air to convectively cool the equipment.  
      What is needed is an improved compact compressor and/or compact cooling system that can be employed to cool electronic equipment.  
     SUMMARY OF THE INVENTION  
      The present invention provides compact compressors and refrigeration systems that can be used to cool computers, servers, and other electronic equipment. Each compact compressor or refrigeration system includes a compact, substantially enclosed hermitic housing having a simple geometry profile, such as a rectilinear profile, which enables the compact compressor or refrigeration system to be easily inserted within a slot, for example, of an electronic component such as a computer server. In one embodiment, a compact compressor is provided, which includes a motor-compressor unit within the housing, including a stator, a rotor disposed interiorly of the stator, and a compressor mechanism disposed interiorly of the rotor to provide a compact profile. In another embodiment, the housing includes the foregoing compact motor-compressor unit, and further includes a condenser formed within one of the walls of the housing and an evaporator formed within another wall of the housing such that the housing defines a completely contained, compact refrigeration system. Alternatively, in another embodiment, the housing may include only one of the condenser and evaporator, with the other of the condenser and evaporator configured as a modular component which is attached to the housing.  
      One embodiment of the invention provides a compact refrigeration system that may be fit within a standard sized slot of a computer server. The system includes enclosure walls that define at least one heat exchanger, such as a condenser or evaporator, and each heat exchanger may define a temperature gradient that has a localized maximum or minimum at the center of the heat exchanger, and wherein the heat exchanger defines substantially similar temperatures at locations that are at substantially similar radial distances from the center and local maximum, minimum temperature of the heat exchanger.  
      In one form thereof, the present invention provides a compact compressor unit, including a substantially enclosed housing including an inlet and an outlet; and a motor-compressor unit disposed within the housing, including a stator; a rotor disposed substantially interiorly of the stator; and a compressor mechanism driven by the rotor and disposed substantially interiorly of the rotor, the compressor mechanism in fluid communication with the inlet and the outlet, whereby the compressor mechanism receives fluid from the inlet at suction pressure, compresses the fluid to discharge pressure, and discharges the fluid at discharge pressure through the outlet.  
      In another form thereof, the present invention provides a compact refrigeration system, including a substantially enclosed housing having a simple geometry profile including at least first and second sides; a motor-compressor unit disposed within the housing, including a stator; a rotor disposed substantially interiorly of the stator; and a compressor mechanism driven by the rotor, the compressor mechanism having an inlet and an outlet; a condenser formed at least partially within the first side of the housing, the condenser in fluid communication with the compressor mechanism outlet; an evaporator formed at least partially within the second side of the housing, the evaporator in fluid communication with the compressor mechanism inlet; and an expansion device in fluid communication with the condenser and with the evaporator.  
      In a further form thereof, the present invention provides a compact refrigeration system, including a substantially enclosed housing having a simple geometry profile, including an inlet and an outlet and at least a first side; a motor-compressor unit disposed within the housing, including a stator; a rotor disposed substantially interiorly of the stator; and a compressor mechanism driven by the rotor; and a first heat exchanger formed substantially within the first side of the housing, the first heat exchanger in fluid communication with the compressor mechanism.  
      In a further form thereof, the present invention provides a compact refrigeration system, including a housing, including a first housing component including at least a first pair of opposite sides of the housing; and a second housing component including at least another side of the housing, the first and second housing components insertable one into the other; and a compressor mechanism disposed within the housing.  
      In a further form thereof, the present invention provides a compact refrigeration system, including a housing, including a first housing component including at least a first pair of opposite sides of the housing; and a second housing component including at least another side of the housing, the first and second housing components insertable one into the other; and a heat exchanger at least partially integrated into one of the sides of the housing, the heat exchanger including a passage extending from proximate a central portion of the housing side toward a peripheral portion of the housing side.  
      In a further form thereof, the present invention provides a compact refrigeration system, including a housing including an inlet and an outlet; a compressor unit disposed within the housing, the compressor unit including a stator; a rotor disposed substantially interiorly of the stator; and a compressor mechanism driven by the rotor and disposed interiorly of the stator; and a first heat exchanger configured as a modular unit attached to a wall of the housing, the heat exchanger in fluid communication with the inlet and with the outlet.  
      In a further form thereof, the present invention provides a compact refrigeration system, including a first housing component having a simple geometry profile including an exterior wall, and a groove formed within the exterior wall; a second housing component into which the first housing component is received, the second housing component having a wall in abutment with the exterior wall of the first housing component and enclosing the groove to define a heat exchanger passage; and a compressor mechanism disposed within the first housing component and in fluid communication with the heat exchanger passage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:  
       FIG. 1  is a perspective view of a compact compressor according to a first embodiment of the present invention, showing the components of the compressor housing;  
       FIG. 2  is a sectional view taken along line  2 - 2  of  FIG. 1 , showing an exemplary manner in which a fluid line or fluid fitting may be attached to the inlet or outlet of the compact compressor;  
       FIG. 3  is a perspective cutaway view of the compact compressor;  
       FIG. 4  is a further perspective cutaway view of the compact compressor, showing components of the compressor mechanism;  
       FIG. 5  is a further perspective cutaway view of a portion of the compact compressor, showing components of the compressor mechanism;  
       FIG. 6  is a perspective view of a portion of the compressor mechanism of  FIG. 5 ;  
       FIG. 7  is a first exploded view of a compact refrigeration system according to a second embodiment, viewed from a first direction;  
       FIG. 8  is a second exploded view of the compact refrigeration system, viewed from a second direction;  
       FIG. 9  is a perspective view of the compact refrigeration system, showing the components of the refrigeration system housing;  
       FIG. 10  is a perspective view of a first side of the inner housing component of the compact refrigeration system, showing the condenser;  
       FIG. 11  is a perspective view of a second side of the inner housing component of the compact refrigeration system, showing the evaporator;  
       FIG. 12  is a perspective view similar to  FIG. 10 , showing exemplary weld lines for securing the outer housing component to the inner housing component of the compact refrigeration system;  
       FIG. 13  is a perspective view similar to  FIG. 11 , showing exemplary weld lines for securing the outer housing component to the inner housing component of the compact refrigeration system;  
       FIG. 14  is a perspective view of one compact refrigeration system according to a third embodiment, showing the housing of the compact refrigeration system including a condenser and a modular heat exchanger configured as an evaporator, wherein a portion of the housing of the compact refrigeration system is broken away to show the terminal assembly; and  
       FIG. 15  is a perspective view of another compact refrigeration system according to the third embodiment, showing the housing of the compact refrigeration system including an evaporator and a modular heat exchanger configured as a condenser, wherein a portion of the housing of the compact refrigeration system is broken away to show the terminal assembly. 
    
    
      Although the exemplification set out herein illustrates embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed.  
     DETAILED DESCRIPTION  
      The present invention provides both compact compressors and compact refrigeration systems which, in the exemplary application described below, may be used to provide cooling to electronic equipment. A compact compressor  20  according to a first embodiment of the present invention is shown in  FIGS. 1-8 . With initial reference to  FIGS. 1-4 , compressor  20  generally includes a hermetic enclosure or housing  22  and a motor-compressor unit  24  disposed within hermetic housing  22 . Referring to  FIG. 1 , housing  22  generally includes a first or inner housing component  26  and a second or outer housing component  28 . To assemble compact compressor  20 , first housing component  26  is insertable within second housing component  28 , and the foregoing are secured to one another such as by welding in the manner described below.  
      As shown in  FIGS. 1 and 3 , compressor housing  22  has a simple geometry profile, shown herein as a rectilinear profile. In this manner, compact compressor  20  may be inserted into a slot in an electronics device in a cartridge-type manner, and be easily removed therefrom for repair or replacement, for example. First housing component  26  is shown in  FIGS. 1 and 3 , and has a box-type, rectilinear profile generally including three pairs of opposing side walls, including front wall  30 , rear wall  32 , left side wall  34 , right side wall  36 , top wall  38 , and bottom wall  40  ( FIG. 4 ). Although the words “front”, “back”, “left”, etc., are used herein to designate sides and/or walls of the compact compressors and refrigeration systems of the present invention, same are necessarily arbitrary designations, and the present invention is not limited orientationally to such terms. Front side wall  30  includes inlet  42  and outlet  44 , and an electrical terminal assembly  46  is recessed into a cavity defined between left side wall  34  and rear side wall  32 , which is surrounded by shoulder  48 . First housing component  26  contains motor-compressor unit  24  therein, as described below.  
      Compact compressor  20  is a removable compressor that can be slid into a electronic component using a suitable slot and latch-type mechanism to allow non-destructive replacement of compressor  20 . The electrical terminal assembly  46 , as shown in  FIGS. 1, 3 , and  4 , is embedded within the walls of compressor  20  and, when compressor  20  is properly installed, the terminals of electrical terminal assembly  46  mate with corresponding terminals of the electronic component.  
      As shown in  FIG. 1 , second housing component  28  includes top wall  50 , bottom wall  52 , left side wall  54  and right side wall  56 . In assembling compact compressor  20 , first or inner housing component  26  is inserted within second or outer housing component  28  as shown in  FIG. 1  in a “matchbox”-type manner, wherein cutout portions of top wall  50  and left side wall  54  of second housing component  28  abut shoulder  48  of first housing component  26 . Thereafter, first and second housing components  26  and  28  are secured to one another in the manner described below.  
      In the compact compressors and refrigeration systems disclosed herein, after first and second housing components  26  and  28  are assembled together, each component  26  and  28  has walls or outer surface regions that are exposed to ambient pressure and, during operation, are exposed to internal pressure forces, as described below. The side walls of each component  26  and  28  are configured such that the internal and external pressure forces acting upon one wall are balanced by an opposed pressure force acting upon an opposite wall. In the illustrated embodiments, this is accomplished by having the exposed surfaces or outer walls of housing  22  parallel and of substantially equal surface area. For example, the front and rear side walls  30  and  32  of housing  22  are both defined by first housing component  26 , while the top and bottom walls  50  and  52  and the left and right side walls  54  and  56  are both defined by second housing component  28 . By configuring the enclosure in this manner, the pressure forces acting on the front and back walls  30  and  32  are balanced by first component  26  without having to transmit these forces through a joint or other interface between first and second housing components  26  and  28 . Similarly, the pressure forces acting on the top and bottom walls  50  and  52  and the left and right side walls  54  and  56  are balanced by second housing component  28  without having to transmit these forces through a joint or other interface between first and second components  26  and  28 .  
      A significant advantage of this design is that it reduces the forces acting at the interface or seal between first and second housing components  26  and  28 . Because the pressure forces acting upon each individual housing component  26  and  28  are balanced, the pressure forces do not tend to pull apart the housing components  26  and  28  as is typical in a conventional hermetically sealed compressor housing. This balancing of the forces on the individual components  26  and  28  allows the joint between the housing components  26  and  28  to be welded or otherwise sealed in a manner that ensures the seal between the two components without having to compensate for stress due to pressure forces. The forces acting on the joints between the two components  26  and  28  will be mostly mechanical, such as shock, vibration, handling, and securing forces.  
      Although compact compressor  20  and the compact refrigeration systems described below have a rectilinear configuration, alternative embodiments may employ enclosure walls that balance the pressure forces acting on each individual housing component without the use of enclosure walls that are parallel or flat. The exposed walls of the enclosure merely have to be configured such that the overall effective pressure forces acting on individual component walls are substantially balanced to thereby minimize the forces transmitted through the interface between the individual components.  
      Referring to  FIGS. 3-8  first housing component  26  includes motor-compressor unit  24 , which generally includes a motor and a compressor mechanism  60 , as described below. Motor-compressor unit  24  shown in  FIGS. 7 and 8  is shown as a portion of CRS  120  described below, however, motor-compressor unit  24  of compact compressor  20  an CRS  120  are substantially identical. Referring primarily to  FIGS. 7 and 8 , bottom wall  40  of first housing component  26  includes a pair of concentric, annular outer and inner stator flanges  62  and  64  extending therefrom. An annular stator  66  is mounted within the space between annular stator flanges  62  and  64 , and is secured thereto in a suitable manner, such as via an interference fit. Stator  66  generally includes a stator body with windings. Referring to  FIG. 4 , electrical leads  68  extend from electrical terminal assembly  46  to the windings of stator  66  for providing electrical power to the windings of stator  66 . An annular rotor  70  is disposed within stator  66 , and generally includes an annular body having a plurality of magnets  72  attached to the body of rotor  70  around the outer periphery thereof. As shown, magnets  72  are received within complementary shaped, dovetail-shaped recesses around the body of rotor  70  in a press-fit manner, by suitable fasteners, or in another suitable manner.  
      First housing component  26  additionally includes a pair of body portions  74  and  76 , one body portion  74  including electrical terminal assembly  46 , and the other body portion  76  including inlet  42  and outlet  44  of compact compressor  20  ( FIG. 1 ). Annular needle bearing race  78  is fixed within interior stator flange  62 , and includes a plurality of needle bearings. An eccentric  80  is fitted within rotor  70  and fixed thereto, and is bearingly supported by bearing race  78 . Eccentric  80  includes a central opening  82 , a portion of which has an axis which is offset from the rotational axis A 1 -A 1  of rotor  66 , as may be seen in  FIG. 8 . Roller  84  is fitted within the portion of central opening  82  of eccentric  80  which is offset from the rotational axis A 1 -A 1  of rotor  66 . A circular discharge valve plate  86  is also received within a portion of central opening  82  of eccentric  80  which is coaxial with rotational axis A 1 -A 1  of rotor  66 , and includes a discharge port  88 . A flapper-type discharge check valve  90  is secured to discharge valve plate  86 , and the movement thereof is limited by valve stop plate  92  also secured to discharge valve plate  86 . Discharge housing  94  is disposed over discharge valve plate  86 , and includes an arcuate-shaped recess  96  ( FIG. 8 ) therein which defines a discharge muffler chamber. Discharge housing may include a boss (not shown) which fits within an opening in wall  38  of first housing component  26  with an O-ring seal therebetween.  
      Hub  98  is disposed within the inner annular space of roller  84  and is captured between top wall  38  of first housing component  26  and discharge valve plate  86 . Hub  98  includes slot  100  therein in which vane  102  is fitted, with vane  102  biased outwardly of slot  100  by a spring (not shown), such that the tip of vane  102  is in sliding contact with the interior surface of roller  84 .  
      In operation, electrical power supplied to the windings of stator  66  generates a magnetic field therein which rotates rotor  70  within stator  66  about rotational axis A 1 -A 1 . Eccentric  80  is rotated concurrently with rotor  70 , and causes roller  84  to orbit about the rotational axis A 1 -A 1  of rotor  70 . The orbital movement of roller  84  about hub  98  causes vane  102  to reciprocate within slot  98  to define a pair of crescent-shaped, variable-volume working pockets between roller  84 , hub  98 , and vane  102  for compressing refrigerant within compression mechanism  60 .  
      Referring to  FIGS. 1, 5 ,  7 , and  8 , compact compressor  20  is connected to other components of a refrigeration system which are disposed externally of compressor  20 , such as condenser, an expansion device, and an evaporator (not shown). Refrigerant at suction pressure enters compressor housing  22  through inlet  42 , and passes through passages  104  and  106  ( FIG. 5 ) in body portion  76  and bottom wall  40  of housing component  26 , respectively, to the inlet of compressor mechanism  60 . The refrigerant is compressed by compressor mechanism  60  in the manner described above, and is discharged through discharge port  88  and check valve  90  into discharge muffler chamber  96 . Thereafter, the compressed refrigerant passes through discharge passages  108  and  110  ( FIG. 5 ) in top wall  38  and body portion  76 , respectively, and outlet  44  of compressor housing  22 . The compressed refrigerant then passes through the condenser, expansion device, and evaporator of the refrigeration system before being drawn into inlet  42  of housing  22  to repeat the foregoing cycle.  
      The interior volume  112  of housing  22  defines an oil sump which is in fluid communication with the refrigerant, and may be at either suction pressure or discharge pressure. Oil within the oil sump may be entrained within the refrigerant for lubricating the moving parts of compressor mechanism  60 . For example, referring to  FIG. 4 , body portion  76  of first housing component  26  may include an oil hole  101 , such that refrigerant passing through inlet  42  at suction pressure may entrain oil from the oil sump within interior volume  112  of housing  22  through oil hole  101  into the refrigerant stream to lubricate the moving parts of compressor mechanism  60 .  
      Referring to  FIGS. 1 and 2 , inlet and outlet  42  and  44  are recessed into front wall  30  of housing  22 . In the compact compressor  20  of  FIGS. 1-6  and the modular refrigeration system or CRS  120  of  FIGS. 7-14 , the recessed nature of inlet  42  and outlet  44  avoids having inlet and outlet tubes projecting outwardly from housing  22  and thereby facilitates the installation of the compact compressor  20  or CRS  120 . Moreover, as best seen in  FIG. 2 , the recessed nature of inlet  42  and outlet  44  allow external conduits, or the fittings of an external heat exchanger such as that shown in  FIG. 14 , to be easily mounted to inlet  42  and outlet  44 . In the illustrated embodiment, such conduits or fittings  114  are located in a cylindrical recess  116  that surrounds the outer radial surface of inlet  42  and outlet  44  with O-rings  118  providing a seal therebetween. This allows the external conduit or fitting  114  to be inserted over inlet  42  or outlet  44  with one O-ring  118  being positioned between the internal surface of external conduit or fitting  114  and the external surface of inlet  42  or outlet  44  and a second O-ring  118  positioned between the outer surface of external conduit or fitting  114  and the inner surface of recess  116  without requiring brazing or other similar means of sealing and securing the foregoing components together.  
      A compact refrigeration system (“CRS”)  120  according to a second embodiment of the present invention is shown in  FIGS. 7-13 . Except as described below, CRS  120  includes a housing  22  with a compact motor-compressor unit  24  which is substantially identical to that of compact compressor  20  described above, and the same reference numerals will be used below to designate identical or substantially identical features between compact compressor  20  and CRS  120 . Housing  22  of CRS  120 , similar to that of compact compressor  20 , is both compact and modular to facilitate its use in changing environments and smaller spaces associated with electronic equipment. As described below, housing  22  of CRS  120  includes a compact compressor mechanism  60  substantially identical to that described above with respect to compact compressor  20 , and additionally includes other refrigeration system components, including a condenser, expansion device, and evaporator, which are located within housing  22  to hermetically seal CRS  120  from the outside environment and reduce the potential for leaks from the system.  
      Further, as described below, the outer surfaces of CRS  120  include high-density heat flux surfaces to provide heat transfer between CRS  120  and components of the electronic equipment being cooled, and also between CRS  120  and a suitable heat sink or the ambient environment. By locating all of the refrigeration components of CRS  120  within a single enclosure, the potential for leaks is reduced, and CRS  120  may advantageously be formed of stamped parts to thereby reduce the time and cost of manufacture. Similar to compact compressor  20 , the outer configuration of CRS  120  may altered to adapt it to its intended application, for example, CRS  120  may be shaped as a parallelepiped, cylinder or other shape, and may define hot and/or cold surfaces on various locations on the exterior of its enclosure.  
      Referring to  FIGS. 7-11 , CRS  120  includes a condenser  122  ( FIGS. 7 and 10 ) defined within top walls  38  and  50  of first and second housing components  26  and  28 , respectively, and an evaporator  124  ( FIGS. 8, 9 , and  11 ) defined within bottom walls  40  and  52  of first and second housing components  26  and  28 , respectively. Bottom walls  40  and  52  of first and second housing components  26  and  28 , respectively, including evaporator  124 , define a cold face or “cold plate” of CRS  120  which may be placed in thermal communication with the surfaces of electrical components, such as computer chips or other electrical circuitry which require cooling, to facilitate transfer of heat from the electrical component to a suitable refrigerant via evaporator  124  of CRS  120 . Top walls  38  and  50  of first and second housing components  26  and  28 , respectively, including condenser  122 , define a hot face or “hot plate” of CRS  120  which may be placed in thermal communication with a suitable heat sink or with the ambient atmosphere to facilitate transfer of heat from the refrigerant to the heat sink or ambient atmosphere via condenser  122 .  
      Referring to  FIG. 10 , condenser  122  includes an inlet  126  disposed in a central portion of top wall  38  of first housing component  26 , which is in fluid communication with discharge muffler chamber  96  of compressor mechanism  60  ( FIG. 7 ). A spiral condenser passage  128  is shown as a groove which is cast or milled within top wall  38  of first housing component  26 , and is enclosed by top wall  50  of second housing component  28 . Outlet  130  of condenser passage  128  is in fluid communication with passage  132  in body portion  74  of first housing component  26 , which leads to evaporator  124 .  
      Referring to  FIG. 11 , evaporator  124  includes a restrictor passage  134 , shown as a thin groove which is cast or milled within bottom wall  40  of first housing component  26 , and is enclosed by bottom wall  52  of second housing component  28 . Restrictor passage  134  is in fluid communication with passage  132  in body portion  74  of first housing component  26 . Restrictor passage  134  extends around the outer periphery of first housing component  26 , and terminates in expansion device  136 , which is configured as the entrance to a relatively wide evaporator passage  138 , shown as a relatively wide groove which is cast or milled within bottom wall  40  of first housing component  26 , and is enclosed by bottom wall  52  of second housing component  28 , as shown in  FIG. 9 . Evaporator passage  138  extends from the central portion of bottom wall  40  of first housing component  26  in an arcuate, alternating manner as shown in  FIG. 11  toward the outer periphery of first housing component  26 . The outlet  140  of evaporator passage communicates with a deep, substantially annular recess  142  formed within outer stator flange  64  such that, in operation, refrigerant passing through deep recess  142  around outer stator flange  64  cools stator  66 . Recess  142  communicates with the inlet of compressor mechanism  60  via a shallow, wide suction line passage  144 . Optionally, the bottom of recess  142  may include openings therein in communication with internal volume  112  of housing  22 , such that recess  142  may function as an oil separator.  
      In operation, compressed refrigerant discharged from compressor mechanism  60  passes through inlet  126  of condenser passage  128  and thence through condenser passage  128  to allow heat from the refrigerant to diffuse through top wall  50  of second housing component  28  to a suitable heat sink or the ambient atmosphere. As shown in  FIG. 10 , because inlet  126  of condenser passage  128  is disposed near the central portion of top wall  38  of first housing component  26 , and condenser passage  128  extends in a spiral manner outwardly from the central portion of top wall  38  of first housing component  26 , passage of high pressure refrigerant from inlet  126  through condenser passage  128  will generate a heat gradient in top wall  50  of second housing component  28 . In this manner, top wall  50  of second housing component  28  will be relatively hotter near the center thereof, and progressively less hot toward the outer periphery thereof.  
      In other words, CRS  120  may employ heat exchangers, such as condenser  122  and evaporator  124 , which are formed in or proximate a wall or face of housing  22  and where the hottest or coolest point (depending upon whether the refrigerant is losing or absorbing thermal energy) of the heat exchanger is in the middle of the wall or face. Because potential heat transfer losses may be due to conduction in the enclosure walls, keeping the temperature gradients in the enclosure walls forming parts of the heat exchangers as low as possible will optimize the performance of the heat exchangers. As described above, for the heat exchanger functioning as condenser  122  or gas cooler, the hottest point of the heat exchanger would be near or at the middle of the wall or face of housing  22 , and the refrigerant would travel radially outward, such as in the spiral shaped condenser passage  128 , as it cools. Thus, when the refrigerant has reached the outer radial edges of the heat exchanger face and enclosure wall, it will have been cooled and will not increase, or will minimally increase, the temperature gradient within the enclosure walls.  
      The high pressure refrigerant then passes through outlet  130  of condenser passage  128  and through passage  132  in body portion  74  of first housing component  26  into narrow restrictor passage  134  in bottom wall  40  of first housing component  26 . Upon encountering expansion device  136 , the pressure of the refrigerant rapidly decreases, and the low pressure refrigerant then passes through evaporator groove  138  of evaporator  124  allowing the low pressure refrigerant to take up heat from an electronics component to be cooled which is disposed adjacent bottom wall  40  of second housing component  28 . As shown in  FIG. 11 , because expansion device  136  is disposed near the central portion of bottom wall  40  of first housing component  26 , and evaporator passage  138  extends in an arcuate, alternating manner outwardly from the central portion of bottom wall  40  of first housing component  26 , passage of low pressure refrigerant through evaporator passage  138  will generate a cooling gradient in bottom plate  52  of second housing component  28 . In this manner, bottom plate  52  of second housing component  28  will be relatively cooler near its center, and progressively less cool toward its outer periphery.  
      Thereafter, the low pressure refrigerant passes into deep recess  142  within stator flange  64  to cool stator  66 , and thence through suction line passage  144  into the inlet of compressor mechanism  60  where the refrigerant is compressed to repeat the foregoing cycle. Alternatively, stator  66  itself may include a passage therein, through which some or a portion of the refrigerant is directed to cool stator  66 . Also, instead of directing refrigerant from the outlet of evaporator  124  to recess  142  or a passage in the stator  66 , high pressure refrigerant from condenser  122  can be expanded, such as by passage through a capillary tube, and then directed directly to stator  66  for cooling purposes without first passing through evaporator  124 . This arrangement may be used to provide additional cooling capacity for motor-compressor unit  24 . If the pressure of refrigerant which is used to cool stator  66  of motor-compressor unit  24  is higher than the compression suction pressure, an additional expansion device may be used to further reduce the pressure of the refrigerant to the desired suction pressure after it has cooled motor-compressor unit  24 .  
      In the manner described above, heat from an electronics component to be cooled is absorbed by evaporator  124 , which defines a “cold plate” of CRS  120 , and the heat is conveyed to a suitable heat sink or to the ambient environment via condenser  122 , which functions as a “hot plate” of CRS  120 . The foregoing refrigeration cycle can be a conventional cycle with the refrigerant undergoing a phase change in both condenser  122  and evaporator  124 , a transcritical system wherein the refrigerant, such as carbon dioxide, is compressed to a supercritical pressure, or a system wherein the refrigerant remains a gas and does not undergo a phase change.  
      Referring to  FIGS. 12 and 13 , an exemplary manner in which first housing component  26  and second housing component  28  may be secured together is shown. Referring to  FIG. 12 , welding, such as laser welding, may be performed along the dashed lines  146  around the outer periphery of condenser passage  128  and optionally, between each of the concentric portions of condenser passage  128  to secure top wall  50  of second housing component  28  to top wall  38  of first housing component  26 , while concurrently isolating the high pressure condenser passage  128  from communication with other portions of CRS  120 . In a similar manner, referring to  FIG. 13 , welding, such as laser welding, may be performed along the dashed lines  148  around restrictor passage  134 , evaporator passage  138 , and passage  144  as shown to thereby secure bottom wall  52  of second housing component  28  to bottom wall  40  of first housing component  26  while concurrently isolating restrictor passage  134 , evaporator passage  138 , and passage  144  from fluid communication with other portions of CRS  120 . A similar laser welding technique may be used to secure first and second housing components  26  and  28  of compact compressor  20  of  FIGS. 1-6 , described above. Further characteristics of CRS  120  are discussed below.  
      Although condenser passage  128  of condenser  122  is described above as a groove formed within top wall  38  of first housing component  26 , which is enclosed by top wall  50  of second housing component  28 , and similarly, restrictor passage  134  and expansion groove  138  are described above as grooves in bottom wall  40  of first housing component  26  which are enclosed by bottom wall  52  of second housing component  28 , the foregoing passages may be constructed in alternative configurations. For example, one or more of the foregoing passages may be formed completely within either top wall  38  of first housing component  26 , top wall  50  of second housing component  28 , or in bottom wall  40  of first housing component  26  or bottom wall  52  of second housing component  28 . Still further, the foregoing passages may be formed in top and bottom walls  50  and  52  of second housing component  28 , and enclosed by top and bottom walls  38  and  40  of first housing component  26 , respectively.  
      Similar to compact compressor  20  described above, housing  22  of CRS  120  may have an outer surface or envelope that defines simple geometric shape or profile. The use of a simple geometric shape or profile for the outer envelope facilitates the assembly and interchangeability of the system. The purpose of the simple geometry envelope is to ensure positioning and alignment of the enclosure to other surfaces in the environment. For example, computer servers have slots with predefined dimensions in which electronic components can be inserted. By reducing the height of compact compressor  20  and CRS  120  to less than 1U, i.e., less than about 1.75 inches (4.45 cm), by positioning compression mechanism  60  inside rotor  70  as best seen in  FIG. 4 , compact compressor  20  and CRS  120 , such as those shown in  FIGS. 1-9 , may have dimensions that allow same to be slid into such a server slot, for example, to provide cooling to the server.  
      As described above, CRS  120  is configured to locate the low pressure regions thereof in the corners of housing  22  between first and second housing components  26  and  28 . This location for the low-pressure regions will help to keep housing  22  free of leaks by lowering the volume of the high pressure regions and thus the effective surface areas of the high-pressure regions. By locating the low pressure regions in the corners of housing  22 , the overall force exerted by the high pressure refrigerant biasing first and second housing components  26  and  28  apart from one another can be reduced. The low pressure in these regions may be maintained by sealing these areas off from the high pressure regions and providing fluid communication between the low pressure regions and a volume of the system that is at suction pressure during operation of the compressor, such as a suction line or evaporator  124 .  
      When the object to be cooled by CRS  120  is a computer, the limits on power consumption may be relatively restrictive. In such situations, it may be desirable to trade refrigeration system efficiency for reduced power consumption. For example, it may be desirable to cool the refrigerant as it is being compressed so that the compression process approaches an isothermal process to reduce power consumption at the expense of refrigeration system efficiency. The refrigerant may be cooled by convection with refrigerant in internal volume  112  of housing  22 , by suction gas diverted to cool compression mechanism  60  before compression of the suction gas, by conduction that vents thermal energy to the ambient environment, evaporator  124  or other heat sink, by thermoelectric devices, or other suitable means.  
      The refrigerant used with CRS  120  may also be selected to reduce the power consumption of CRS  120 . For example, R245fa may be used as the refrigerant. This freon is conventionally used in heat pump applications or as an insulation blowing agent, not as a refrigerant for a refrigeration system. It has a Global Warming Potential less than R134a. The normal boiling temperature of R245fa is relatively high (15° C.) and it also has a relatively low density in comparison to conventional refrigerants commonly used in refrigeration systems. The lower density of R245fa requires that this refrigerant be used with a compressor having a relatively large volumetric displacement and thus negatively impacts its performance as a refrigerant in common refrigeration cycles. For CRS  120  of the present invention, however, a reduction in power consumption by the compressor is highly desirable and although a motor-compressor unit  24  which is designed for use with R245fa will require a large volumetric displacement due to the lower density of the refrigerant, this lower density will also result in a motor that has relatively reduced power requirements. Furthermore, the operating pressures employed when using R245fa are relatively low and the pressure difference across the system is also relatively low in comparison to refrigerants conventionally employed in common refrigeration cycles and the reduced operating pressures and pressure differences facilitate the manufacture of a lightweight and compact CRS  120 .  
      Modified versions of CRS  120 , namely, CRS  150 , are shown in  FIGS. 14 and 15  which include only condenser  122  ( FIG. 14 ) or evaporator  124  ( FIG. 15 ). A modular heat exchanger  152 , which may be either a condenser or an evaporator, is attached to housing  22  of CRS  150 . Except as described below, CRS  150  of  FIGS. 14 and 15  each include a motor-compressor unit  24  therein which is substantially identical to that of compact compressor  20  and CRS  120  described above, and further, except as described below, CRS  150  functions in the same manner as CRS  120  described above, and identical reference numerals are used in  FIGS. 14 and 15  to designate identical or substantially identical components therebetween.  
      As shown in  FIGS. 14 and 15 , housing  22  of CRS  150  includes inlet  42  and outlet  44  similar to those of compact compressor  20 . Modular heat exchanger  152 , which may be configured as a condenser or evaporator, is secured to housing  22  via a suitable latching mechanism, for example, and includes an inlet fitting  154  and an outlet fitting  156  in fluid communication with outlet  44  and inlet  42  of housing  22 , such as in the manner described above with respect to  FIG. 2 . Modular heat exchanger  152  generally includes a refrigerant passage therethrough, and a plurality of heat spreading means such as fins  158  to facilitate thermal exchange between the refrigerant within modular heat exchanger  152  and the ambient environment surrounding modular heat exchanger  152 .  
      In one embodiment, shown in  FIG. 14 , modular heat exchanger  152  is an evaporator. In this embodiment, CRS  150  includes motor-compressor unit  24  and condenser  122 . In operation, compressed refrigerant passes from motor-compressor unit  24  through condenser  122  as described above to transfer heat from the refrigerant to a suitable heat sink or the ambient environment. Thereafter, the refrigerant passes through outlet  44  of housing  22  of CRS  150  and into inlet  154  of modular heat exchanger  152 . Modular heat exchanger  152  may include an expansion device therein to allow expansion of refrigerant before the refrigerant passes through the internal passages of modular heat exchanger  152  to take up heat from the area surrounding modular heat exchanger  152 . Thereafter, the refrigerant passes through outlet  156  of modular heat exchanger  152 , into inlet  42  of housing  22  of CRS  150  and into the inlet of motor-compressor unit  24  to repeat the foregoing refrigeration cycle.  
      In one embodiment, shown in  FIG. 15 , modular heat exchanger  152  is a condenser. In this embodiment, CRS  150  includes motor-compressor unit  24  and evaporator  124  and, in operation, refrigerant compressed by motor-compressor unit  24  passes through outlet  44  of housing  22  of CRS  150  and into inlet  154  of modular heat exchanger  152 . In modular heat exchanger  152 , the heat from the refrigerant diffuses into the ambient atmosphere. Thereafter, the refrigerant flows through outlet  156  of modular heat exchanger  152  and into inlet  42  of CRS  150 , and passes through restrictor passage  134 , expansion device  136 , evaporator passage  138 , and suction line passage  144  and into the inlet of motor-compressor unit  24  as described above, wherein evaporator  124  of CRS  150  functions as a “cold plate” in the manner described above.  
      In a still further embodiment, CRS  150  may be configured with both condenser  122  and evaporator  124  as described above with respect to CRS  120 , and may additionally include modular heat exchanger  152  to provide a supplemental condenser or evaporator to the system. In a further alternative, modular heat exchanger  152  may be configured as a suction line heat exchanger (“SLHX”) to allow both further cooling of the refrigerant after same passes through condenser  122 , and further warming of the refrigerant after same passes through evaporator  124  to thereby increase the efficiency of CRS  150 .  
      While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles.