Abstract:
A heat exchanger has a fin pack, with a first supply header and a first return header at the first end of the fin pack. A first group of U-shaped tubes is provided with a first segment extending from the first supply header to the second end of the fin pack, and a second segment extending from the second end of the fin pack to the first return header. A second supply header and a second return header are also provided at the first end of the fin pack. A second group of U-shaped tubes is provided with a first segment extending from the second supply header to the second end of the fin pack, and a second segment extending from the second end of the fin pack to the second return header, where the second plurality of U-shaped tubes is disposed inwardly of the first plurality of U-shaped tubes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present Application claims the benefit of priority under 35 U.S.C. §119(e)(1) of U.S. Provisional Patent Application No. 61/487,200, titled “Secondary Coolant Finned Coil” and filed on May 17, 2011, the complete disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to a refrigeration system. The present disclosure relates more particularly to a refrigeration system having improved secondary coolant finned coils. 
     It is well known to provide a refrigeration system for use with one or more temperature controlled storage devices such as a refrigerator, freezer, refrigerated merchandiser, display case, etc., that may be used in commercial, institutional, and residential applications for storing or displaying refrigerated or frozen objects. For example, it is known to provide a refrigeration system having a refrigerant for direct expansion in a single loop operation to provide cooling to a heat exchanger such as an evaporator or chiller. It is also known to provide a secondary liquid coolant loop that is cooled by the chiller and then routed to various storage devices to provide cooling to temperature controlled objects. It is also known to pass the secondary coolant through a finned coil to remove a heat load from the storage device. One continuing challenge in secondary cooling is the pressure drop associated with the fluid passing through the finned coil. A refrigeration system having improved efficiency and thermal characteristics for use with temperature controlled storage devices is provided. 
     SUMMARY 
     One embodiment of the disclosure relates to a heat exchanger having a first end, a second end located opposite the first end, and a plurality of fins located between the first end and the second end. The heat exchanger further includes a first supply header located proximate the first end and a first return header located proximate the first end. A first tube segment couples to the first supply header and extends through the plurality of fins from the first end to the second end. A second tube segment couples to the first return header and extends through the plurality of fins from the first end to the second end. A third tube segment couples the first tube segment to the second tube segment proximate second end. In one embodiment, fluid flowing from the first supply header to the first return header passes through the plurality of fins only twice. In one embodiment, the heat exchanger further includes a second supply header located proximate the first end and a second return header located proximate the first end. A fourth tube segment couples to the second supply header and extends through the plurality of fins from the first end to the second end. A fifth tube segment couples to the second return header and extends through the plurality of fins from the first end to the second end. A sixth tube segment couples the fourth tube segment to the fifth tube segment proximate the second end. In one embodiment, a fluid flowing from the second supply header to the second return header passes through the plurality of fins only twice. 
     Another embodiment of the disclosure relates to a refrigeration system having a chiller configured to receive a refrigerant for chilling a coolant, and a pump for distributing the chilled coolant to at least one heat exchanger in at least one temperature controlled storage device. The heat exchanger includes fins spaced apart from one another in a substantially parallel arrangement to form a fin pack, with a first fin at a first end of the fin pack and a last fin at the second end of the fin pack. A first supply header is provided at the first end of the fin pack and a first return header is also provided at the first end of the fin pack. A first group of U-shaped tubes is provided with a first segment extending from the first supply header at the first end of the fin pack to the second end of the fin pack, and a second segment extending from the second end of the fin pack to the first return header at the first end of the fin pack. A second supply header is provided at the first end of the fin pack and a second return header is also provided at the first end of the fin pack. A second group of U-shaped tubes is provided with a first segment extending from the second supply header at the first end of the fin pack to the second end of the fin pack, and a second segment extending from the second end of the fin pack to the second return header at the first end of the fin pack, where the second plurality of U-shaped tubes is disposed inwardly of the first plurality of U-shaped tubes. 
     Another embodiment of the disclosure relates to heat exchanger having fins spaced apart from one another in a substantially parallel arrangement to form a fin pack, with a first fin at a first end of the fin pack and a last fin at the second end of the fin pack. A first supply header is provided at the first end of the fin pack and a first return header is also provided at the first end of the fin pack. A first group of U-shaped tubes is provided with a first segment extending from the first supply header at the first end of the fin pack to the second end of the fin pack, and a second segment extending from the second end of the fin pack to the first return header at the first end of the fin pack. A second supply header is provided at the first end of the fin pack and a second return header is also provided at the first end of the fin pack. A second group of U-shaped tubes is provided with a first segment extending from the second supply header at the first end of the fin pack to the second end of the fin pack, and a second segment extending from the second end of the fin pack to the second return header at the first end of the fin pack, where the second plurality of U-shaped tubes is disposed inwardly of the first plurality of U-shaped tubes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a refrigeration system having a liquid coolant supplied to storage devices, according to an exemplary embodiment. 
         FIG. 2  is a schematic diagram of a secondary coolant finned coil as known in the prior art. 
         FIG. 3  is a schematic diagram of a secondary coolant finned coil having one inlet header and one outlet header, according to an exemplary embodiment. 
         FIG. 4  is a schematic diagram of a secondary coolant finned coil having two inlet headers and two outlet headers, according to an exemplary embodiment. 
         FIG. 5  is a schematic diagram of a secondary coolant finned coil having three inlet headers and three outlet headers, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the FIGURES, a refrigeration system is shown for use with one or more temperature controlled storage devices. The refrigeration system includes a primary cooling loop thermally coupled to a secondary cooling loop. The secondary cooling loop includes a finned coil located within a temperature controlled storage device. In use, the relatively warm air in the storage device passes across the fins of the coil. The coil may be located in the storage device such that natural convection moves air across the fins of the coil. Alternatively, a fan may be provided to circulate air within the storage device, thereby moving air across the fins of the coil. As air moves across the fins, heat from the air transfers to the relatively cooler fins. Heat from the fins transfers to the fluid of the secondary cooling loop and is thereby removed from the storage device. 
     Various storage devices may have different storage temperature requirements (e.g. “low temperature,” such as approximately −20° F., or “medium temperature,” such as approximately 25° F.). Storage devices may have a variety of applications. One example of a storage device is a refrigerated display case in a supermarket. A medium temperature refrigerated display case may have one or more glass doors and contain soft drinks, beer, water, juice, etc. A low temperature display case may contained ice cream, frozen vegetables, frozen dinners, etc. 
     The various temperatures of the storage device, refrigerants and liquid coolants illustrated or described in the various embodiments, are shown by way of example only. A wide variety of other temperatures and temperature ranges may be used to suit any particular application and are intended to be within the scope of this disclosure. Also, the various flow rates, capacity and balancing of coolants and refrigerants are described by way of example and may be modified to suit a wide variety of applications depending on the number of storage devices, the temperature requirements of the storage devices, etc. 
     Referring to  FIG. 1 , a refrigeration system  100  includes a first portion shown as portion  110  for use with temperature controlled storage devices having a “medium” storage temperature requirement (such as, for example, 25° F. and referred to herein as storage devices). According to alternative embodiments, portion  110  be used with temperature controlled storage devices having a “low” storage temperature requirement (such as, for example, −20° F.), or refrigeration system  100  may include a second portion for use with low temperature storage devices. 
     Portion  110  is shown to include a first (or primary) cooling loop  112  (e.g., formed from suitable conduits or passageways such as pipes, fittings, tubing, etc.) having a refrigerant (e.g., a direct expansion type refrigerant such as R404A, carbon dioxide, or other suitable refrigerant) as a cooling medium. The refrigerant is compressed by a compressor  114  to a high temperature and high pressure state, and is then cooled in a condenser  116 , then expanded in an expansion device (such as an expansion valve  118 ) to provide a source of cooling to a heat exchanger operating as a cooling element (such as a cooling coil, evaporator, etc), shown as a chiller  120 . According to one embodiment, the components of first cooling loop  112  operate to provide refrigerant at a temperature of approximately 13° F. to the chiller  120 . In practice, primary cooling loop  112  extends remotely from chiller  120 . For example, compressor  114  and condenser  116  may be located on the roof of a building. According to alternative embodiments, primary cooling loop  112  remains proximate chiller  120 . According to various embodiments, the primary cooling  112  may be a single-phase or two phase system. In a two phase system the refrigerant entering chiller  120  is heated from a liquid phase to a vapor (or gas) phase. In a single phase system, refrigerant entering chiller  120  is heated but remains a liquid. 
     Portion  110  also includes a second (or secondary) cooling loop  130  having a first portion  132 . According to one embodiment, the second cooling loop  130  is cooled by the refrigerant in chiller  120  to a temperature of approximately 20° F. A liquid coolant (such as glycol, water, other liquids, or other suitable refrigerant) is circulated through the first portion  132  by a pump  136  to provide cooling to a heat exchanger (such as a finned coil) within one or more storage devices (shown for example as three storage devices  138 ). According to the exemplary embodiment, secondary cooling loop  130  is a single phase loop. According to one alternative embodiment, secondary cooling loop  130  includes a second portion (e.g. circuits, branches, flow paths, etc.—formed from suitable conduits or passageways such as pipes, fittings, tubing, etc.) for circulation of a liquid coolant (such as water, glycol, etc.) as a cooling medium by pump  136 . The second portion of secondary cooling loop  130  may be thermally coupled to a condenser of a second portion (e.g., low temperature portion) of refrigeration system  100 . According to other alternative embodiments, other components or equipment such as a receiver, a sub-cooler, liquid line or suction line filter, oil management system, etc., may be included in the system. 
     Referring to  FIG. 2 , a secondary coolant finned evaporator coil, shown as coil  20 , is shown according to a prior art embodiment. Coil  20  includes a plurality of fins  24  longitudinally spaced apart and extending laterally across coil  20 . Coil  20  includes an inlet header  21  and a return header  22 , which are shown located on an inlet side of the coil. Inlet header  21  delivers coolant to a plurality of first tubes  26 , which extend longitudinally through fins  24 . At the far end of the coil, first tubes  26  couple to first bends  25  (e.g., elbows, U-tubes, return bends, etc.). First bends  25  are coupled to second tubes  27  which extend longitudinally towards the inlet end of the coil. Second tubes  27  couple to second bends  25 ′, which couple to third tubes  28 . Third tubes  28  extend longitudinally to the far end of the coil with a couple to third bends  25 ″. Third bends  25 ″ couple to fourth tubes  29  which extend longitudinally towards the inlet end where they are shown to couple outlet header  22 . As described and shown in  FIG. 2 , coil  20  is typically referred to as a four pass coil. That is, coolant passes through fins  24  four times through first tubes  26 , second tubes  27 , third tubes  28 , and fourth tubes  29 . Other conventional coils, may have additional bends and tubes to form additional passes, for example, six pass or eight pass coils, etc. 
     One factor in optimizing performance in a single phase fluid coil is minimizing the pressure drop associated with a fluid passing through the coil. Coil  20 , exemplary of other conventional coils, has a single inlet header  21  and a single outlet header  22  that feeds the tubes within the coil  20 . To minimize the pressure drop through coil  20 , inlet header  21  is designed to feed many tubes (see e.g., first tubes  26  and fourth tubes  29 ) and sometimes can feed over  12  to  16  tubes. Generally, the more tubes that inlet header  21  can feed results in less fluid pressure drop through coil  20 . The drawback is the additional cost, manufacturing time, and complexity of these headers  21 . This complexity also limits the number of tubes  26  that the header can feed and results in the coil having return bends  25 ′ on the inlet side of coil  20 . Each circuit of coil  20  includes four or more tubes and three or more bends, which may increase the residence time of the coolant within the fins, thereby increasing heat transfer to the coolant, but which also increase the pressure drop through coil  20 . 
     Referring to  FIG. 3 , an improved secondary coolant finned coil, shown as coil  30 , is shown according to an exemplary embodiment. Coil  30  includes a plurality of fins  34  longitudinally spaced apart and extending laterally across coil  30 . Coil  30  includes a supply header  31  located on an inlet side of coil  30 . Supply header  31  distributes coolant through a fluid distributor (shown as manifold  33  on the return side) to supply tubes  36  (pipes, fittings, tubing, conduits, etc.). According to the exemplary embodiment, supply tubes  36  (shown by way of example as eight supply tubes) extend in parallel and longitudinally to the far end of coil  30  where they couple to bends  35  (e.g., elbows, U-tubes, return bends, etc.). Bends  35  couple to return tubes  37  (pipes, fittings, tubing, conduits, etc.) which extend longitudinally to manifold  33 , which in turn returns coolant to return header  32 . According to alternate embodiments, supply tubes  36  and return tubes  37  may include any number of tubes which may or may not be parallel. According to one embodiment, a supply tube  36 , a bend  35 , and a return tube  37  may be segments of one tube. 
     Referring to  FIG. 4 , a secondary coolant finned coil, shown as coil  40 , is shown according to an exemplary embodiment. Coil  40  includes a plurality of fins  44  longitudinally spaced apart and extending laterally across coil  40 . Coil  40  includes a first supply header  41   a , a second supply header  41   b , a first return header  42   a , and a second return header  42   b . As shown, supply headers  41  and return headers  42  are located at an inlet end of coil  40 . Supply headers  41  distribute coolant to supply tubes  46  through fluid distributors, shown as manifolds  43 . According to the exemplary embodiment, first supply header  41   a  is coupled to parallel supply tubes  46   a  (shown by way of example as eight supply tubes), which extend longitudinally to the far end of coil  40  where they couple to bends  45   a . Bends  45   a  couple to return tubes  47   a , which extend longitudinally to a manifold  43   a  coupled to return header  42   a . Similarly, second supply header  41   b  is coupled to eight parallel supply tubes  46   b , which extend longitudinally to the far end of coil  40  where they couple to bends  45   b . Bends  45   b  couple to return tubes  47   b , which extend longitudinally to a manifold  43   b  coupled to return header  42   b . According to alternate embodiments, supply tubes  46  and return tubes  47  may include any number of tubes which may or may not be parallel. According to one embodiment, a supply tube  46 , a bend  45 , and a return tube  47  may be segments of one tube. 
     As shown, first supply header  41  a and first return header  42   a  form an inner circuit, and second supply header  42   b  and second return header  42   b  form an outer circuit. The inner circuit and outer circuit carry coolant in parallel. According to the exemplary embodiment, the inner circuit and the outer circuit pass through a common set of fins  44 . According to an alternate embodiment, the inner circuit in the outer circuit may pass through independent sets of fins. For example, the inner circuit may be the embodiment shown in  FIG. 3 , and the outer circuit may be added around the inner circuit. In this manner, the cooling capacity to storage device  138  may be increased with minimal plumbing changes and without removing the existing inner circuit. According to one embodiment, the tubes and bends of both the inner and outer circuit have substantially similar diameters. According to an alternate embodiment, the tubes and bends of the outer circuit have a greater diameter than the tubes and bends of the inner circuit. The larger diameter of the outer circuit tubes and bends may compensate for the greater distance traveled, thereby maintaining a similar pressure drop through the coil as that of the inner circuit. Furthermore, the larger diameter enables more coolant to pass through the outer circuit, which may create a similar cooling per unit length as the inner circuit, thereby reducing potential hotspots near the end of the outer circuit. 
     According to one embodiment, an overall length of coil  40  is between approximately 77 inches and approximately 94 inches. According to another embodiment, the overall length of coil  40  is between approximately 80 inches and approximately 90 inches. According to the embodiment shown, the distance from the inlet end side of manifold  43  to the far end side of bend  45   b  is approximately 85 1/16 inches. According to one embodiment, the longitudinal fin length of coil  40  is between approximately 70 inches and approximately 90 inches. According to the embodiment shown, the distance from the first fin  44  on the inlet end of coil  40  to the last fin  44  on the far end of coil  40  is approximately 80 inches. According to one embodiment, the fin height of coil  40  is between approximately 4 inches and approximately 6 inches. According to the embodiment shown, the vertical height of fins  44  of coil  40  is approximately 5 inches. Coil  40  may include members configured to support the coil. According to one embodiment, the support members are longitudinally spaced along coil  40  at intervals of between approximately 24 inches and approximately 30 inches. According to the embodiment shown, the support members are longitudinally spaced along coil  40  at intervals of approximately 26 21/32 inches. According to one embodiment, supply headers  41  and return headers  42  have outside diameters between approximately 1 inch and approximately 2 inches. According to the embodiment shown, supply headers  41  and return headers  42  have outside diameters of approximately 1⅝ inches. According to the embodiment shown, supply headers  41  and return headers  42  have inside diameters of approximately ⅞ inches. According to one embodiment, supply tubes  46  and return tubes  47  have diameters of greater than ⅜ inch. According to another embodiment, supply tubes  46  and return tubes  47  have diameters between approximately ⅜ inch and approximately ⅝ inch. According to the embodiment shown supply tubes  46  and return tubes  47  have diameters of approximately ½ inch. According to other embodiments, the coil and associated components may have different dimensions, sizes, lengths, diameters, etc. 
     Referring to  FIG. 5 , a secondary coolant finned coil, shown as coil  50 , is shown according to an exemplary embodiment. Coil  50  includes a plurality of fins  54  spaced longitudinally apart and extending laterally across coil  50 . Coil  50  includes a first supply header  51   a , a second supply header  51   b , a third supply header  51   c , a first return header  52   a , a second return header  52   b , and a third return header  52   c , which are located at an inlet end of coil  50 . Supply headers  51  distribute coolant to supply tubes  56  through fluid distributors, shown as manifolds  53 . According to the exemplary embodiment, first supply header  51   a  is coupled to parallel supply tubes  56   a  (shown by way of example as eight supply tubes), which extend longitudinally to the far end of coil  50  where they couple to bends  55   a . Bends  55   a  couple to return tubes  57   a , which extend longitudinally to a manifold  53   a  couple to return header  52   a . As shown, this forms an inner circuit. An exemplary middle circuit is formed by second supply header  51   b , a fluid distributor, eight supply tubes  56   b , bends  55   b , eight return tubes  57   b , a return manifold  53   b , and a return header  52   b . An exemplary outer circuit is formed by third supply header  51   c , a fluid distributor, eight supply tubes  56   c , bends  55   c , eight return tubes  57   c , a return manifold  53   c , and return header  52   c . According to various embodiments, one or more additional circuits may be similarly formed around the outer circuit. According to alternate embodiments, supply tubes  56  and return tubes  57  may include any number of tubes which may or may not be parallel. According to one embodiment, a supply tube  56 , a bend  55 , and a return tube  57  may be segments of one tube. 
     According to the exemplary embodiment shown, the inner circuit, the middle circuit, and the outer circuit, pass through a common set of fins  54 . The inner circuit, the middle circuit, and the outer circuit, are coupled to the secondary cooling loop  130  in parallel. According to various alternate embodiments the inner circuit, the middle circuit, and the outer circuit may pass through any combination of common or independent sets of fins. For example, the inner circuit in the middle circuit may pass through common set of fins  54 , and an outer circuit having its own set of fins may be added around the middle circuit. In this manner, the cooling capacity to storage device  138  may be increased with minimal plumbing and without removing the existing inner and middle circuits. 
     According to one embodiment, the tubes and bends of the inner, middle, and outer circuits have substantially similar diameters. According to various alternate embodiments, the circuits may have different diameter tubes and bends. As such, the diameter of a circuit&#39;s tubes and bends may be selected to compensate for the pressure drop resulting from the increased distance traveled, thereby creating substantially similar pressure drops through each circuit. According to one embodiment, the diameter of the tubes and bends of the outer circuit is greater than the diameter of the tubes and bends of the middle circuit, which in turn is greater than the diameter of the tubes and bends of the inner circuit. 
     According to the embodiment shown in  FIG. 4 , bends  45   a  and  45   b  all extend beyond the last fin at the far end of the coil. According to the embodiment shown in  FIG. 5 , bend  55   c  extends beyond the last fin, bend  55   b  extends between the last fin and the next to last fin, and bend  55   a  extends between the second to last fin and the next to last fin. According to various embodiments, the bends maybe located between any fins. Adding fins between the bends takes advantage of the space available to increase the total fin surface area and thereby increase cooling capacity. 
     As described and shown in  FIGS. 3 ,  4 , and  5 , coil  30 , coil  40 , and coil  50  are two pass coils. That is, coolant passes through the fins ( 34 ,  44 ,  54 ) two times: once through the supply tubes ( 36 ,  46 ,  56 ), and once through the return tubes ( 37 ,  47 ,  57 ). Limiting the number of passes each circuit takes through the coil reduces the number of bends and the number of tubes and the length of the circuit from inlet to outlet, thereby decreasing the pressure drop through the coil and increasing the heat transfer capability of the coil. Limiting the number of passes each circuit takes through the coil reduces the change in temperature laterally and longitudinally across the coil as coolant acquires heat traveling from the supply header ( 31 ,  41 ,  51 ) to the return header ( 32 ,  42 ,  52 ). Reducing the pressure drop through the coil enables a slower flow rate of coolant through the coil. Lower pressure drop through the coil and slower flow rate of coolant through the coil require less pumping power; therefore, less energy is used by rack equipment such as pump  136 . 
     According to the embodiments shown, all of the circuits flow laterally from left to right. According to alternative embodiments, any number of circuits may be configured to flow laterally from right to left. For example, in coil  50 , the inner circuit and the outer circuit may flow laterally from left to right, and the middle circuit may flow laterally from right to left. This may reduce the change in temperature laterally across the coil, thereby creating a more even temperature distribution in storage device  138 . 
     According to the exemplary embodiment, coil  30 , coil  40 , and coil  50  are modular and/or stackable. According to one embodiment, a first finned coil (e.g., coil  30 , coil  40 , or coil  50 ) forms a first module and a second finned coil (e.g., coil  30 , coil  40 , or coil  50 ) forms a second module. The first module and the second module may be oriented such that the relatively warm air of storage device  138 , after passing through the fins of the first module, passes through the fins of the second module, thereby being cooled even further. This increases the cooling capacity available to storage device  138 . This also increases the cooling capacity available for use in applications such as condensers, etc. Furthermore, the modularity of the stacked coils facilitates repair by enabling one module to be shut off (e.g., by valve) while maintaining coolant flow to the second module. According to various embodiments, any number of coils may be stacked to form a heat exchanger unit. According to another embodiment, the inner circuit forms a first module having a first set of fins  54   a , the middle circuit forms a second module having a second set of fins  54   b , and the outer circuit forms a third module having a third set of fins  54   c . Modules may be installed subsequently, in any order, and in any number to achieve the desired cooling capacity for storage device  138 . 
     According to the embodiments shown, the supply tubes and return tubes extend longitudinally through laterally extending fins. According to alternate embodiments, the supply tubes and return tubes extend laterally through longitudinally extending fins. In such a configuration, a module having longitudinal fins may be stacked on a module have lateral fins in order to create certain air flow and heat exchange properties. 
     Using multiple headers as shown in  FIGS. 4 and 5  reduces the complexity of conventional headers. Reducing the complexity of the header reduces cost, manufacturing time, and pressure drop. Using multiple headers facilitates larger scale manufacture of interchangeable headers rather than making complex headers dependent on the number of tubes required. This enables headers to be made in advance, reduces manufacturing time, and facilitates repair by having stock headers available for replacement. To these ends, a supply header and fluid distributor assembly may be substantially the same as a return header and manifold assembly. According to one embodiment, a return header  52  and manifold  53  may be inverted and installed as a supply header  51  and fluid distributor. Furthermore, multiple headers enables the circuits to be isolated. For example, an outer circuit could be shut off for repair while the inner and middle circuits continued to provide cooling to storage device  138 . As such, chilled product in storage device  138  may not need to be moved during repairs, thereby saving time and the costs of obtaining and cooling another refrigerated storage device. 
     It is also important to note that the construction and arrangement of the elements of the coil as shown in the exemplary embodiments are illustrative only. Although only a few embodiments of the present disclosure have been described in detail, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements. It should be noted that the elements and/or assemblies of the enclosure may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. Additionally, in the subject description, the word “exemplary” is used to mean serving as an example, instance or illustration. Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word exemplary is intended to present concepts in a concrete manner. Accordingly, all such modifications are intended to be included within the scope of the present inventions. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the appended claims. 
     The various temperatures of the storage devices and the refrigerants illustrated or described in the various embodiments, are shown by way of example only. A wide variety of other temperatures and temperature ranges may be used to suit any particular application and are intended to be within the scope of this disclosure. Also, the various flow rates, capacity and balancing of refrigerants are described by way of example and may be modified to suit a wide variety of applications depending on the number of storage devices, the temperature requirements of the storage devices, the heating demands from the heat loads, the pressure drops through the one or more sections of the heat exchanger(s), etc. 
     It should also be noted that any references to “upstream,” and “downstream” in this description are merely used to identify the various elements as they are oriented in the FIGURES, being relative to a specific direction. These terms are not meant to limit the element which they describe, as the various elements may be oriented differently in various applications. 
     As utilized herein, the terms “approximately,” “about,” “substantially,” and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims. 
     It should be noted that the term “exemplary” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples). 
     Before discussing further details of the coil, it should be noted that references to “lateral,” “right,” and “left” in this description are merely used to identify the various elements as they are oriented in the FIGURES, with “right,” “left,” and “lateral” being relative to a specific direction. These terms are not meant to limit the element which they describe, as the various elements may be oriented differently in various applications. 
     The terms “coupled,” “connected,” and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. 
     It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure. 
     The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating configuration, and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the appended claims.