REVERSE CYCLE DEFROST REFRIGERATION SYSTEM

Abstract

A refrigeration system in which a refrigerant is circulatable, the refrigeration system including an indoor coil assembly with an indoor coil and a suction header subassembly connected with indoor coil circuits of the indoor coil. The suction header subassembly includes a hollow suction header body defining a suction header bore therein and one or more extended spigots defining an extended spigot bore therein for directing the refrigerant into a selected one of the indoor coil circuits when operating in a defrost mode. The extended spigot includes an open inner end that is located in the suction header bore to receive a portion of the refrigerant flowing therethrough when the refrigeration system is operating in the defrost mode.

Claims

1. A refrigeration system in which a refrigerant is circulatable, the refrigeration system comprising: an indoor coil assembly comprising: an indoor coil comprising a plurality of tubes defining respective tube bores therein through which the refrigerant is flowable, the tubes being arranged in a plurality of indoor coil circuits respectively, each said indoor coil circuit extending between an inlet end thereof, at which the refrigerant flows into each said indoor coil circuit respectively when the refrigeration system is operating in a refrigeration mode, and an outlet end thereof, via which the refrigerant exits each said indoor coil circuit respectively when the refrigeration system is operating in the refrigeration mode, the refrigerant flowing through each said indoor coil circuit from the outlet end to the inlet end thereof when the refrigeration system is operating in a defrost mode; a suction header subassembly connected with the indoor coil circuits at the outlet ends thereof, the suction header subassembly comprising: a hollow suction header body defining a suction header bore therein through which the refrigerant is flowable in a first direction when the refrigeration system operates in the refrigeration mode, and through which the refrigerant flows in a second direction, opposed to the first direction, when the refrigeration system operates in the defrost mode; a plurality of elongate spigots, each said spigot defining a spigot bore therein through which the refrigerant is flowable, the spigots being formed for connecting the tube bores of the respective indoor coil circuits in fluid communication with the suction header bore via the respective spigot bores; and the spigots comprising at least one extended spigot comprising a main body portion and an inner end portion thereof located in the suction header bore, the main body portion being connected to a selected one of the indoor coil circuits and the inner end portion comprising an open inner end in fluid communication with an extended spigot bore of said at least one extended spigot, the inner end portion being positioned to locate the open inner end facing opposite to the second direction, for receiving therein a portion of the refrigerant flowing in the second direction through the suction header bore, said portion of the refrigerant being directed via the open inner end through the extended spigot bore into the selected one of the indoor coil circuits for defrosting the selected one of the indoor coil circuits, when the refrigeration system is operating in the defrost mode.

2. The refrigeration system according to claim 1 in which: the open inner end of said at least one extended spigot is defined by an end portion axis; and the inner end portion is positioned in the suction header bore to locate the end portion axis substantially parallel with the second direction, for receiving the portion of the refrigerant in the open inner end of said at least one extended spigot when the refrigerant is flowing in the second direction.

3. The refrigeration system according to claim 1 in which: the inner end portion extends between the open inner end thereof and an outer end thereof; the inner end portion comprises an inner end portion bore extending between the open inner end and the outer end; and the main body portion extends between an outer part, at which a main body portion bore of the main body portion is in fluid communication with the tube bore of the tube of said selected one of the indoor coil circuits, and an inner part, at which the main body portion is connected with the outer end of the inner end portion and the main portion bore is in fluid communication with the inner end portion bore of the inner end portion.

4. The refrigeration system according to claim 1 in which the open inner end is substantially centered in the suction header bore.

5. The refrigeration system according to claim 2 in which the open inner end is substantially centered in the suction header bore.

6. A suction header subassembly connected with a plurality of indoor coil circuits of an indoor coil in a refrigeration system at respective outlet ends of the indoor coil circuits, each said indoor coil circuit comprising a tube defining a tube bore therein through which a refrigerant is flowable, each said indoor coil circuit extending between an inlet end thereof, at which the refrigerant flows into each said indoor coil circuit respectively when the refrigeration system is operating in a refrigeration mode, and the outlet end thereof, via which the refrigerant exits each said indoor coil circuit respectively when the refrigeration system is operating in the refrigeration mode, the refrigerant flowing through each said indoor coil circuit from the outlet end to the inlet end thereof when the refrigeration system is operating in a defrost mode, the suction header subassembly comprising: a hollow suction header body defining a suction header bore therein through which the refrigerant is flowable in a first direction when the refrigeration system operates in the refrigeration mode, and through which the refrigerant flows in a second direction, opposed to the first direction, when the refrigeration system operates in the defrost mode; a plurality of elongate spigots, each said spigot defining a spigot bore therein through which the refrigerant is flowable, the spigots being formed for connecting the tube bores of the respective indoor coil circuits in fluid communication with the suction header bore via the respective spigot bores; and the spigots comprising at least one extended spigot comprising a main body portion and an inner end portion thereof located in the suction header bore, the main body portion being connected to a selected one of the indoor coil circuits and the inner end portion comprising an open inner end in fluid communication with an extended spigot bore of said at least one extended spigot, the inner end portion being positioned to locate the open inner end facing opposite to the second direction, for receiving a portion of the refrigerant flowing in the second direction through the suction header bore in the open inner end, said portion of the refrigerant being directed via the open inner end through the extended spigot bore into the selected one of the indoor coil circuits for defrosting the selected one of the indoor coil circuits, when the refrigeration system is operating in the defrost mode.

7. The suction header subassembly according to claim 6 in which: the open inner end of said at least one extended spigot is defined by an end portion axis; and the inner end portion is positioned in the suction header bore to locate the end portion axis substantially parallel with the second direction, for receiving the portion of the refrigerant in the open end of said at least one extended spigot when the refrigerant is flowing in the second direction.

8. The suction header subassembly according to claim 6 in which: the inner end portion extends between the open inner end thereof and an outer end thereof, the inner end portion comprising an inner end portion bore extending between the open inner end and the outer end; and the main body portion extends between an outer part, at which a main body portion bore of the main body portion is in fluid communication with the tube bore of the tube of said selected one of the indoor coil circuits, and an inner part, at which the main body portion is connected with the outer end of the inner end portion and the main portion bore is in fluid communication with the inner end portion bore of the inner end portion.

9. The suction header subassembly according to claim 6 in which the open inner end is substantially centered in the suction header bore.

10. The suction header subassembly according to claim 7 in which the open inner end is substantially centered in the suction header bore.

11. An extended spigot for directing a portion of refrigerant flowing in a preselected direction of flow through a suction header bore of a suction header body to a selected one of a plurality of hollow indoor coil circuits to defrost said selected one of the indoor circuits, said selected one of the indoor coil circuits comprising a tube defining a tube bore therein through which the refrigerant is flowable, the extended spigot comprising: a main body portion extending between inner and outer parts thereof; an inner end portion extending between an outer end and an open inner end thereof, the outer end being connected with the main body portion at the inner part thereof; the outer part of the main body portion being connected with the selected one of the plurality of the indoor coil circuits; and the inner end portion being positioned to locate the open inner end facing opposite to the preselected direction of flow of the refrigerant through the suction header bore, for receiving therein the portion of the refrigerant.

12. The extended spigot according to claim 11 comprising an extended spigot bore extending between the open inner end of the inner end portion and the outer part of the main body portion, through which the portion of the refrigerant is flowable to the tube bore of the tube of the selected one of the indoor coil circuits.

13. A method of defrosting an indoor coil in a refrigeration system in which a refrigerant is circulatable, the indoor coil comprising a plurality of indoor coil circuits, each said indoor coil circuit comprising a tube defining a tube bore therein through which a refrigerant is flowable, each said indoor coil circuit extending between an inlet end thereof, at which the refrigerant flows into each said indoor coil respectively when the refrigeration system is operating in a refrigeration mode, and an outlet end thereof, via which the refrigerant exits each said indoor coil circuit respectively when the refrigeration system is operating in the refrigeration mode, the refrigerant flowing through each said indoor coil circuit from the outlet end to the inlet end thereof when the refrigeration system is operating in a defrost mode, the method comprising: (a) providing a hollow suction header body defining a suction header bore therein through which the refrigerant is flowable in a first direction when the refrigeration system operates in the refrigeration mode, and through which the refrigerant flows in a second direction, opposed to the first direction, when the refrigeration system operates in the defrost mode; (b) providing a plurality of elongate spigots, each said spigot defining a spigot bore therein through which the refrigerant is flowable, the spigots being formed for connecting the tube bores of the respective indoor coil circuits in fluid communication with the suction header bore via the respective spigot bores; (c) providing at least one extended spigot comprising a main body portion and an inner end portion thereof located in the suction header bore, the main body portion being connected to a selected one of the indoor coil circuits and the inner end portion comprising an open inner end in fluid communication with an extended spigot bore of said at least one extended spigot, the inner end portion being positioned to locate the open inner end facing opposite to the second direction; (d) permitting a portion of the refrigerant flowing in the second direction through the suction header bore to be received in the open inner end; and (e) via the extended spigot bore, directing said portion of the refrigerant from the open inner end into the selected one of the indoor coil circuits for defrosting the selected one of the indoor coil circuits, when the refrigeration system is operating in the defrost mode.

14. The method according to claim 13 in which: the open inner end of said at least one extended spigot is defined by an end portion axis; and the inner end portion is positioned in the suction header bore to locate the end portion axis substantially parallel with the second direction, for receiving the portion of the refrigerant in the open end of said at least one extended spigot when the refrigerant is flowing in the second direction.

15. The method according to claim 13 in which: the inner end portion extends between the open inner end thereof and an outer end thereof, the inner end portion comprising an inner end portion bore extending between the open inner end and the outer end; and the main body portion extends between an outer part, at which a main body portion bore of the main body portion is in fluid communication with the tube bore of the tube of the selected one of the indoor coil circuits, and an inner part, at which the main body portion is connected with the outer end of the inner end portion and the main portion bore is in fluid communication with the inner end portion bore of the inner end portion.

16. The method according to claim 13 in which the open inner end is substantially centered in the suction header bore.

17. The method according to claim 14 in which the open inner end is substantially centered in the suction header bore.

18. A header subassembly connected with a plurality of coil circuits of a tube fin coil in a refrigeration system at respective second ends of respective coil circuits of the tube fin coil, each said coil circuit comprising a tube defining a tube bore therein through which a refrigerant is flowable, each said coil circuit extending between a first end thereof, at which the refrigerant flows into each said coil circuit respectively when the refrigeration system is operating in a refrigeration mode, and the second end thereof, via which the refrigerant exits each said coil circuit respectively when the refrigeration system is operating in the refrigeration mode, the refrigerant flowing through each said coil circuit from the second end to the first end thereof when the refrigeration system is operating in a defrost mode, the header subassembly comprising: a hollow header body defining a header bore therein through which the refrigerant is flowable in a first direction when the refrigeration system operates in the refrigeration mode, and through which the refrigerant flows in a second direction, opposed to the first direction, when the refrigeration system operates in the defrost mode; a plurality of elongate spigots, each said spigot defining a spigot bore therein through which the refrigerant is flowable, the spigots being formed for connecting the tube bores of the respective indoor coil circuits in fluid communication with the header bore via the respective spigot bores; and the spigots comprising at least one extended spigot comprising a main body portion and an inner end portion thereof located in the header bore, the main body portion being connected to a selected one of the indoor coil circuits and the inner end portion comprising an open inner end in fluid communication with an extended spigot bore of said at least one extended spigot, the inner end portion being positioned to locate the open inner end facing opposite to the second direction, for receiving a portion of the refrigerant flowing in the second direction through the header bore in the open inner end, said portion of the refrigerant being directed via the open inner end through the extended spigot bore into the selected one of the indoor coil circuits for defrosting the selected one of the indoor coil circuits, when the refrigeration system is operating in the defrost mode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention will be better understood with reference to the attached drawings, in which:

[0022] FIG. 1A (also described previously) is a side view of a suction header assembly of the prior art;

[0023] FIG. 1B (also described previously) is a cross-section of the prior art suction header assembly of FIG. 1A, taken along line 1-1 in FIG. 1A;

[0024] FIG. 2A is an isometric view of an embodiment of a suction header subassembly of the invention attached to an indoor coil, drawn at a smaller scale;

[0025] FIG. 2B is another isometric view of the suction header subassembly and the indoor coil of FIG. 2A, drawn at a smaller scale;

[0026] FIG. 2C is another isometric view of the suction header subassembly and the indoor coil of FIGS. 2A and 2B;

[0027] FIG. 3A is an isometric view of the suction header subassembly of FIG. 2A and a number of spigots, drawn at a larger scale;

[0028] FIG. 3B is an isometric view of the suction header subassembly of FIG. 2A, showing interior portions of a suction header body of the suction header subassembly and an embodiment of an extended spigot of the invention;

[0029] FIG. 4A is a side view of an embodiment of the suction header subassembly and the spigots and the extended spigot of FIGS. 3A and 3B, drawn at a smaller scale;

[0030] FIG. 4B is a cross-section of the suction header subassembly and the spigots and the extended spigot of FIG. 4A, taken along line 2-2 in FIG. 4A;

[0031] FIG. 4C is a view of a portion of FIG. 4B identified as 3 therein, drawn at a larger scale;

[0032] FIG. 5A is a side view of the extended spigot of FIG. 3B, drawn at a larger scale;

[0033] FIG. 5B is an isometric view of the extended spigot of FIG. 5A;

[0034] FIG. 6 is an isometric view of an alternative embodiment of the extended spigot of the invention;

[0035] FIG. 7 is a schematic diagram of an embodiment of a reverse cycle defrost refrigeration system of the invention;

[0036] FIG. 8 is an isometric view of an embodiment of an outlet end distributor subassembly of the invention, drawn at a larger scale;

[0037] FIG. 9 is a side view of an alternative embodiment of the outlet end distributor subassembly of the invention;

[0038] FIG. 10A is a side view of an alternative embodiment of an open inner end of the extended spigot of the invention, drawn at a larger scale;

[0039] FIG. 10B is a side view of another alternative embodiment of the open inner end of the extended spigot of the invention; and

[0040] FIG. 10C is a side view of another alternative embodiment of the open inner end of the extended spigot of the invention.

DETAILED DESCRIPTION

[0041] In the attached drawings, like reference numerals designate corresponding elements throughout. To simplify the description, the reference numerals used in FIGS. 1A and 1B will generally be used in the description, except that each such reference numeral is raised by 100 (or multiples thereof, as the case may be), where the elements described correspond generally to prior art elements already described. Reference is made to FIGS. 2A-7 to describe an embodiment of a refrigeration system of the invention indicated generally by the numeral 130. An embodiment of the refrigeration system 130 of the invention is schematically illustrated in FIG. 7.

[0042] In the refrigeration system 130, a refrigerant (not shown) is circulatable in a first direction (indicated by arrows F1-F4 in FIG. 7) to transfer heat out of a volume of air in a controlled space (not shown) adjacent to an indoor coil assembly 132 of the system when the system is operating in a refrigeration mode, and the refrigerant is circulatable in a second direction (indicated by arrows S1-S4 in FIG. 7) at least partially opposite to the first direction when the system is operating in a defrost mode. The indoor coil assembly 132 (also identified by reference numeral E-4 in FIG. 7) includes an indoor coil 134 (FIGS. 2A-2C). The indoor coil 134 includes a number of indoor coil circuits C that include a number of tubes 136 respectively extending between first and second sides 138, 140 of the indoor coil assembly 132 (FIG. 2A). It will be understood that the tubes 136 define respective tube bores or cavities 137 therein, through which the refrigerant may flow (FIG. 4C). Each of the indoor coil circuits extends between an inlet end 145 and an outlet end 147 thereof (FIG. 2B). It will be understood that, although a number of the indoor coil circuits are illustrated in FIG. 2B, only one circuit C is identified in FIG. 2B, for clarity of illustration.

[0043] Those skilled in the art would appreciate that the refrigeration system 130 includes a number of additional elements. For example, as can be seen in FIG. 7, the refrigeration system 130 preferably also includes: [0044] a compressor E-1; [0045] an outdoor coil assembly E-2; [0046] a receiver E-3; [0047] a reversing valve V-1; and [0048] an expansion valve V-4.
Those skilled in the art would be aware of the manner in which these elements cooperate when the refrigeration system is operating in the refrigeration mode and in the defrost mode. Accordingly, further discussion of these elements is unnecessary.

[0049] When the refrigeration system is operating in the refrigeration mode, the refrigerant flows into the respective indoor coil circuits at the inlet ends 145 thereof, and exits the respective indoor coil circuits at the outlet ends 147 thereof. The refrigerant flows through each of the indoor coil circuits C from the outlet end 147 thereof to the inlet end 145 thereof of the indoor coil circuit when the refrigeration system is operating in the defrost mode. (It will be understood that an inlet side distributor assembly that is connected to the inlet ends 145 is omitted from FIGS. 2A-2C for clarity of illustration.)

[0050] Each of the tubes 136 preferably includes at least first and second parts 142, 144 extending between the first and second sides 138, 140 of the indoor coil 134 and at least a connecting loop 146 at the second side 140 that connects the first and second parts 142, 144 so that they are in fluid communication with each other.

[0051] Preferably, the indoor coil assembly 134 also includes a suction header subassembly 148 that is connected with the indoor coil circuits C at the outlet ends 147 thereof. In one embodiment, the suction header subassembly 148 preferably includes a hollow suction header body 150 defining a suction header bore 152 therein through which the refrigerant is flowable in a first direction when the refrigeration system 130 operates in the refrigeration mode, and through which the refrigerant flows in a second direction, opposed to the first direction, when the refrigeration system 130 operates in the defrost mode. The direction of flow of the refrigerant in the first and second directions is schematically indicated by arrows F and S respectively in FIGS. 4A and 4B. Preferably, the suction header subassembly 148 also includes a number of elongate spigots 154. Each spigot 154 defines a spigot bore 156 therein through which the refrigerant is flowable (FIG. 4B). The spigots 154 are formed for connecting the tube bores 137 of the respective indoor coil circuits C in fluid communication with the suction header bore 152 via the respective spigot bores 156.

[0052] Those skilled in the art would appreciate that the suction header body 150 may have any suitable configuration. For instance, as can be seen in FIGS. 2A-2C, in one embodiment, the suction header body preferably includes first and second straight portions 160, 162 that are joined by an elbow portion 163.

[0053] As will be described, it is preferred that the spigots 154 include one or more extended spigots 154.sub.L. Preferably, the extended spigot 154.sub.L includes a main body portion 180 and an inner end portion 182 thereof located in the suction header bore 152 (FIGS. 3A, 3B, 4B, 4C, 5A, 5B). It is also preferred that the main body portion 180 is connected to a selected one of the indoor coil circuits C, as will be described. The inner end portion 182 preferably includes an open inner end 184 that is in fluid communication with an extended spigot bore 101 of the extended spigot 154.sub.L, as will also be described. Preferably, the inner end portion 182 is positioned to locate the open inner end 184 facing opposite to the second direction, for receiving therein a portion of the refrigerant flowing in the second direction through the suction header bore 152. The portion of the refrigerant that is directed via the open inner end 184 through the extended spigot bore 101 flows into the selected one of the indoor coil circuits C for defrosting the selected one of the indoor coil circuits C, when the refrigeration system 130 is operating in the defrost mode. The portion of the refrigerant that is captured at the open inner end 184 is schematically represented by arrow D in FIGS. 3B, 4B, and 4C.

[0054] An embodiment of the extended spigot 154.sub.L of the invention is illustrated in FIGS. 3A, 3B, 4A, 4B, and 4C. The indoor coil circuit to which the extended spigot 154.sub.L is attached is identified in FIG. 4B, for clarity of illustration, by reference character C.sub.1. The extended spigot 154.sub.L is connected to the outlet end of the selected indoor coil circuit C.sub.1. As noted above, there may be one or more indoor coil circuits that are relatively slow to defrost. The selected indoor coil circuits, to which the extended spigots are attached, are selected because they are relatively slow to defrost. Although the indoor coil circuit C.sub.1 as illustrated in FIG. 4B is the lowermost indoor coil circuit, it will be understood that the selected indoor coil circuits do not necessarily include the lowermost indoor coil circuit.

[0055] As can be seen in FIG. 4C, the open inner end 184 preferably is formed and positioned in the suction header bore 152 to receive the portion of the refrigerant flowing through the suction header bore 152 in the direction indicated by the arrow S (i.e., in the second direction), i.e., while the refrigeration system 130 is operating in the defrost mode. The open inner end 184 is positioned to accept the portion of the refrigerant flowing therethrough.

[0056] Those skilled in the art would appreciate that the extended spigot 154.sub.L, and in particular the inner end portion 182, may have any suitable configuration. In one embodiment, the open inner end 184 of the extended spigot 154.sub.L preferably is defined by an end portion axis X (FIG. 4C). It is also preferred that the inner end portion 182 is positioned in the suction header bore 152 to locate the end portion axis X substantially parallel with the second direction, for receiving the portion of the refrigerant in the open inner end 184 of the extended spigot 154.sub.L when the refrigerant is flowing in the second direction. In one embodiment, and as can be seen in FIG. 4C, the open inner end 184 preferably is defined by ends 102, 103 of the extended spigot 154.sub.L that are positioned parallel to each other, to define a plane P.sub.1 that is substantially orthogonal to the end portion axis X. In one embodiment, the open inner end 184 preferably is located so that the plane P.sub.1 defined by the ends 102, 103 is substantially orthogonal to the second direction, in which the refrigerant flows during defrost mode.

[0057] The portion of the refrigerant that is captured in the open inner end 184 (represented by arrow D in FIGS. 4B and 4C) is directed through the extended spigot bore 101 to the tube bore 137 of the tube that is included in the selected indoor coil circuit C.sub.1. The flow of the captured portion of the refrigerant through the extended spigot bore 101 and into the tube bore 137 is schematically represented by arrow D.sub.1 in FIG. 4B for clarity of illustration.

[0058] As can be seen, for example, in FIGS. 5A and 5B, in one embodiment, the main body portion 180 of the extended spigot 154.sub.L preferably is substantially straight, and the inner end portion 182 preferably has an elbow shape. Preferably, the inner end portion 182 extends between the open inner end 184 thereof and an outer end 104 thereof (FIGS. 5A, 5B). It is also preferred that the inner end portion 182 includes an inner end portion bore 105 extending between the open inner end 184 and the outer end 104 thereof (FIG. 4C). Preferably, the main body portion 180 has an outer part 106, at which the main body portion 180 is connected with the tube 136 of the selected one of the indoor coil circuits C.sub.1. It is preferred that the main body portion 180 extends between the outer part 106 and an inner part 108 thereof, at which the main body portion 180 is connected with the outer end 104 of the inner end portion 182 and a main body portion bore 107 is in fluid communication with the inner end portion bore 105 of the inner end portion 182 (FIG. 4C). The extended spigot bore 101 includes the inner end bore 105 and the main portion bore 107.

[0059] Preferably, the extended spigot 154.sub.L includes the extended spigot bore 101 extending between the open inner end 184 of the inner end portion 182 and the outer part 106 of the main body portion 180, through which the portion of the refrigerant is flowable to the tube bore 137 of the tube of the selected indoor coil circuit C.sub.1 (FIG. 4C).

[0060] It will be understood that the spigots may include more than one extended spigot. It will also be understood that the one or more indoor coil circuits with insufficient refrigerant flow therethrough when the refrigeration system is operating in the defrost mode may be located at any position in the indoor coil.

[0061] It will be understood that the open inner end 184 may be positioned in any suitable location inside the suction header bore 152. In one embodiment, the open inner end 184 preferably is substantially centered in the suction header bore 152.

[0062] As noted above, the extended spigot 154.sub.L may be provided in various forms. The embodiment of the extended spigot 154.sub.L illustrated in FIGS. 5A and 5B preferably includes the main body portion 180 thereof, extending between its inner and outer parts 108, 106 respectively. As can be seen, for instance, in FIG. 5A, in one embodiment, the main body portion 180 preferably is substantially straight. When the extended spigot 154.sub.L is attached to the suction header body 150, the inner end portion 182 preferably is positioned to locate the open inner end 184 so that the open inner end 184 is facing opposite to the preselected direction of flow of the refrigerant through the suction header bore, for receiving therein the portion of the refrigerant.

[0063] It has been found that the extended spigot 154.sub.L has increased the flow rate of the refrigerant through the selected indoor coil circuit C.sub.1, when the refrigeration system is operating in the defrost mode. Without wishing to be bound by any theory, it is believed that the increased flow rate of the refrigerant is due to the location of the open inner end 184, i.e., positioning the open inner end 184 in the suction header bore 152 facing opposite to the direction of flow of the refrigerant to receive the portion of the refrigerant therein, when the refrigeration system is operating in the defrost mode. Such location and orientation of the open inner end results in the refrigerant at the open inner end being subjected to an increased dynamic pressure, which causes the flow of the refrigerant through the extended spigot to be increased.

[0064] As can be seen in FIG. 5A, in one embodiment, the main body portion 180 preferably is substantially defined by an axis Q (FIG. 5A), and the axis X of the open inner end 184 preferably is positioned substantially orthogonal to the axis Q of the main body portion.

[0065] It will be understood that the extended spigot may be provided in any suitable form. Due to variations in indoor coil design, the extended spigot may be provided in a variety of configurations. For instance, an alternative embodiment of the extended spigot 254.sub.L is illustrated in FIG. 6. As can be seen in FIG. 6, in one embodiment, the extended spigot 254.sub.L preferably includes a main body portion 280, an inner end portion 282, and an intermediate portion 209 located between, and connected with, the main body portion 280 and the inner end portion 282. Preferably, the main body portion 280 extends between an outer part 206 and an inner part 207 thereof. The intermediate portion 209 preferably extends between a first end 210 and a second end 211 thereof. The inner part 207 of the main body portion 280 is connected with the first end 210 of the intermediate portion 209. Similarly, the second end 211 of the intermediate portion 209 is connected with the outer end 204 of the inner end portion 282. As can be seen in FIG. 6, the inner end portion 282 includes an open inner end 284.

[0066] The alternative embodiment illustrated in FIG. 6 is exemplary only. It will be understood that the extended spigot 254.sub.L is formed to connect a flow-deficient indoor circuit (not shown in FIG. 6) and a suction header bore (not shown in FIG. 6) in fluid communication with each other. The extended spigot 254.sub.L is formed and positioned to locate the open inner end 284 in the suction header bore so that the open inner end 284 is facing opposite to the direction in which the refrigerant is flowing, during operation in the defrost mode, to receive a portion of the refrigerant in the open inner end 284.

[0067] It will be understood that the extended spigot 254.sub.L preferably is hollow throughout, to define an extended spigot bore therein. As can be seen in FIG. 6, each of the main body portion 280, the intermediate portion 209, and the inner end portion 282 is substantially straight. Those skilled in the art would appreciate that the extended spigot may have any suitable form required in order to connect a flow-deficient indoor coil circuit and the suction header bore in fluid communication with each other and to locate the open inner end of the extended spigot in the suction header bore facing opposite to the direction of flow of the refrigerant, when the refrigeration system is operating in the defrost mode. The extended spigot 254.sub.L is shown connecting the suction header body with an indoor coil circuit in FIGS. 2B and 2C.

[0068] It will be understood that certain elements are omitted from the drawings, for clarity. For example, in FIG. 2C, an end plate of the indoor coil assembly is omitted for clarity of illustration. It is also understood that the indoor coil may also be incorporated into other types of refrigeration systems, including but not limited to, e.g., a compressor rack, or any other multiple compressor systems.

[0069] Those skilled in the art would appreciate that, as noted above, there may be a number of reasons for an uneven defrost pattern in the indoor coil resulting from different rates of defrost in the respective indoor coil circuits. However, it is believed that the main cause (or at least one of the main causes) of the uneven defrost pattern in the prior art is the different flow rates of the refrigerant through the spigots (and ultimately through the respective indoor coil circuits) in the defrost mode. A deficiency in the flow of the refrigerant may be due to various causes.

[0070] In the foregoing description, the lowermost spigot was flow-deficient. However, it will be understood by those skilled in the art that, depending on the configuration of the suction header and related elements, the lowermost spigot is not necessarily flow-deficient. Accordingly, the foregoing description is exemplary, and one or more similarly flow-deficient spigots may be connected with the suction header body at any point in the suction header body. The extended spigot may be installed to correct a slower rate of refrigerant flow at any location on the suction header body accordingly.

[0071] Alternative arrangements may be provided to address the deficiency of refrigerant flow in the flow-deficient spigot. For example, as illustrated in FIGS. 10A-10C, alternative embodiments of the inner end portion of the extended spigot may be used to provide the additional dynamic pressure required to increase the flow of refrigerant into an otherwise flow-deficient spigot.

[0072] For instance, in FIG. 10A, an embodiment of the extended spigot 354.sub.L of the invention is illustrated in which spigot ends 302, 303 thereof define a plane P.sub.2 positioned at a predetermined acute angle relative to the direction of flow of the refrigerant through the bore 152 of the suction header body 150. The spigot ends 302, 303 of the extended spigot 354.sub.L also define an open inner end 384 therein in an inner end portion 382, positioned to receive the portion of the refrigerant, as indicated by arrow D. The flow of the refrigerant through the suction header bore 152 when the refrigeration system is operating in the defrost mode is generally indicated by arrow S. As can be seen in FIG. 10A, the inner end portion 382 preferably is curved, to position the open inner end 384 for receiving the portion of the refrigerant flowing through the suction header bore 152. The open inner end 384 is located in this way to cause the desired increase in dynamic pressure in the spigot 354.sub.L, to provide an increased flow of the refrigerant through the extended spigot 354.sub.L. The inner end portion 382 is slightly curved to locate the plane P.sub.2 at the predetermined angle .

[0073] Another alternative embodiment of the extended spigot 454.sub.L of the invention is illustrated in FIG. 10B. The extended spigot 454.sub.L preferably includes an open inner end 484 positioned to receive the portion of the refrigerant flowing through the suction header bore 152. The open inner end 484 preferably is defined by parts 412, 413 of the extended spigot 454.sub.L that are positioned substantially orthogonal to the direction of the flow of refrigerant through the suction header bore 152. The extended spigot 454.sub.L additionally includes a second aperture 414 at its inner end portion 482. In FIG. 10B, the direction of flow of the refrigerant through the suction header bore 152 is generally indicated by the arrow S, i.e., the refrigeration system is operating in the defrost mode. The portion of the refrigerant flowing into the open inner end 484 is schematically represented by arrow D in FIG. 10B. The open inner end 484 is located to cause the desired increase in dynamic pressure in the spigot 454.sub.L, to provide an increased flow of the refrigerant through the extended spigot 454.sub.L.

[0074] Another alternative embodiment of the extended spigot 554.sub.L is illustrated in FIG. 100. The extended spigot 554.sub.L preferably includes an inner end portion 582 that is located substantially orthogonal to the direction of flow of the refrigerant through the suction header bore 152. Preferably, the inner end portion 582 includes a longer part 515 that is located downstream relative to the flow of refrigerant when the refrigeration system is in the defrost most, and a shorter part that is located upstream.

[0075] As can be seen in FIG. 10C, in one embodiment, the longer part 515 preferably extends into the suction header bore 152, and the shorter part 516 does not extend into the suction header bore 152. The longer part 515 and the shorter part 516 terminate at ends 517, 518 respectively. The extended spigot 554.sub.L preferably also includes an open inner end 584 located between the spigot ends 517, 518. The spigot ends 517, 518 preferably define a plane P.sub.3 that is positioned at a preselected angle relative to the direction of flow of the refrigerant in the defrost mode, to receive the portion of the refrigerant in the open inner end 584. In FIG. 10C, the direction of flow of the refrigerant in the suction header bore 152 when the refrigeration system is operating in the defrost mode is indicated by the arrow S. The flow of the portion of the refrigerant into the open inner end 584 is schematically represented by arrow D in FIG. 10C. The open inner end 584 is located to cause the desired increase in dynamic pressure in the spigot 554.sub.L, to provide an increased flow of the refrigerant through the extended spigot 554.sub.L.

[0076] Embodiments of the extended spigot of the invention may be used to increase the flow of the refrigerant in a coil circuit when the refrigeration system is operating in either the refrigeration mode or the defrost mode. Further alternative arrangements may be used to address deficiencies of refrigerant flow in variously positioned tubes in the indoor coil. For instance, as can be seen in FIG. 8, an inlet end distributor subassembly 596 may be used to distribute the refrigerant more evenly via inlet ends of the coil circuits, when the refrigeration system is operating in the refrigeration mode. As described above, the inlet end distributor subassembly is connected with a number of spigots, and the spigots are respectively connected with the inlet ends of the coil circuits. The direction of flow of the refrigerant through the distributor subassembly 596, when the refrigeration system is operating in the refrigeration mode, is indicated by the arrows F in FIG. 8.

[0077] An alternative embodiment of the outlet end distributor subassembly 696 is illustrated in FIG. 9. The outlet end distributor subassembly 696 is also connected with the outlet end of the indoor coil circuits, via the spigots. The direction of flow of the refrigerant through the distributor subassembly 696 when the refrigeration system is operating in the defrost mode is indicated by the arrow S in FIG. 9.

[0078] The invention also includes a method of defrosting the indoor coil in the refrigeration system 130. In one embodiment, the method preferably includes providing the hollow suction header body 150 defining the suction header bore 152 therein through which the refrigerant is flowable in a first direction when the refrigeration system operates in the refrigeration mode, and through which the refrigerant flows in a second direction, opposed to the first direction, when the refrigeration system operates in the defrost mode. Also, a number of elongate spigots are provided, each spigot defining a spigot bore therein through which the refrigerant is flowable. The spigots are formed for connecting the tube bores of the respective indoor coil circuits in fluid communication with the suction header bore via the respective spigot bores. In addition, one or more extended spigots are provided. The extended spigot includes the main body portion and the inner end portion thereof, the inner end portion being at least partially located in the suction header bore. The main body portion is connected to the selected one of the indoor coil circuits. The inner end portion includes the open inner end in fluid communication with the extended spigot bore of the extended spigot. The inner end portion is positioned to locate the open inner end so that it is facing opposite to the second direction (FIG. 4C). A portion of the refrigerant flowing in the second direction through the suction header bore is permitted to be received in the open inner end. Via the extended spigot bore, the portion of the refrigerant is directed from the open inner end into the selected one of the indoor coil circuits for defrosting the selected one of the indoor coil circuits, when the refrigeration system is operating in the defrost mode.

[0079] It will be appreciated that the invention has many applications other than in connection with hot gas defrost, as described above. The extended spigot may be used in any tube fin coil (e.g., whether the tube fin coil is utilized as an evaporator or as a condenser when the refrigeration system is operating in the refrigeration mode), to increase the flow of the refrigerant through one or more selected coil circuits.

[0080] It will be appreciated by those skilled in the art that the invention can take many forms, and that such forms are within the scope of the invention as claimed. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.