GB2591352A

GB2591352A - Refrigeration device and heat source-side unit

Info

Publication number: GB2591352A
Application number: GB2102395.7A
Authority: GB
Inventors: Egami Makoto; Ono Hideki
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2018-08-27
Filing date: 2018-08-27
Publication date: 2021-07-28
Anticipated expiration: 2038-08-27
Also published as: GB2591352B; JPWO2020044386A1; JP7229256B2; GB2591352A9; WO2020044386A1; GB202102395D0

Abstract

A refrigeration device (100) is provided with a refrigerant circuit through which a refrigerant circulates. The refrigerant circuit includes a compressor (1), a heat source-side heat exchanger (2), an auxiliary heat exchanger (3), a first pressure reduction section (4), a utilization-side heat exchanger (5), a second pressure reduction section (6), and a flow passage switching section. The flow passage switching section switches between a first state and a second state. In the first state, the heat source-side heat exchanger (2) and the auxiliary heat exchanger (3) act as a first condenser, the utilization-side heat exchanger (5) acts as a first evaporator, and the refrigerant flows through the compressor (1), the first condenser, the first pressure reduction section (4), and the first evaporator, in that order. In the second state, the utilization-side heat exchanger (5) acts as a second condenser, the auxiliary heat exchanger (3) acts as a second evaporator, and the refrigerant flows through the compressor (1), the second condenser, the second pressure reduction section (6), and the second evaporator, in that order.

Description

DESCRIPTION

TITLE OF INVENTION

Refrigeration Apparatus and Heat Source-Side Unit

TECHNICAL FIELD

[0001] The present invention relates to a refrigeration apparatus and a heat source-side unit.

BACKGROUND ART

[0002] Conventionally, a refrigeration apparatus is known that is switched between cooling operation by an evaporator (use-side heat exchanger) and defrosting operation on the evaporator.

[0003] Japanese Patent Laying-Open No. 2006-336967 discloses a refrigeration apparatus in which, during defrosting operation, high-temperature refrigerant discharged from a compressor is supplied to a heat exchanger to be defrosted.

CITATION LIST

PATENT LITERATURE

[0004] PTL 1: Japanese Patent Laying-Open No. 2006-336967

SUMMARY OF INVENTION

TECHNICAL PROBLEM

[0005] In the refrigeration apparatus described above, however, the refrigerant supplied from the compressor to the heat exchanger to be defrosted during the defrosting operation is sucked into the compressor, without flowing through any other heat exchangers, after flowing out of the heat exchanger. In the refrigeration apparatus described above, therefore, the amount of heat supplied to the heat exchanger to be defrosted needs to be limited, resulting in difficulty in improving defrosting efficiency.

[0006] A main object of the present invention is to provide a refrigeration apparatus having higher defrosting efficiency than that of a conventional refrigeration apparatus, and a heat source-side unit forming part of the refrigeration apparatus.

SOLUTION TO PROBLEM

[0007] A refrigeration apparatus according to the present invention includes a refrigerant circuit through which refrigerant circulates. The refrigerant circuit includes a compressor, a heat source-side heat exchanger, a first decompression unit, a use-side heat exchanger, a second decompression unit, an auxiliary heat exchanger, and a flow path switching unit. The flow path switching unit switches between a first state in which the heat source-side heat exchanger and the auxiliary heat exchanger act as a first condenser, the use-side heat exchanger acts as a first evaporator, and the refrigerant flows successively through the compressor, the first condenser, the first decompression unit, and the first evaporator, and a second state in which the use-side heat exchanger acts as a second condenser, the auxiliary heat exchanger acts as a second evaporator, and the refrigerant flows successively through the compressor, the second condenser, the second decompression unit, and the second evaporator. ADVANTAGEOUS EFFECTS OF INVENTION [0008] According to the present invention, the auxiliary heat exchanger acts as an evaporator in the second state. Therefore, a refrigeration apparatus having higher defrosting efficiency than that of a conventional refrigeration apparatus, and a heat source-side unit forming part of the refrigeration apparatus can be provided.

BRIEF DESCRIPTION OF DRAWINGS

[0009] Fig. 1 shows a refrigeration apparatus and a heat source-side unit according to a first embodiment.

Fig. 2 shows a first state of the refrigeration apparatus and the heat source-side unit shown in Fig. 1 Fig. 3 shows a second state of the refrigeration apparatus and the heat source-side unit shown in Fig. 1.

Fig. 4 shows a refrigeration apparatus and a heat source-side unit according to a second embodiment Fig. 5 shows a first state of the refrigeration apparatus and the heat source-side unit shown in Fig. 4 Fig. 6 shows a second state of the refrigeration apparatus and the heat source-side unit shown in Fig. 4, Fig. 7 shows a refrigeration apparatus and a heat source-side unit according to a third embodiment.

Fig. 8 shows a first state of the refrigeration apparatus and the heat source-side unit shown in Fig. 7 Fig. 9 shows a second state of the refrigeration apparatus and the heat source-side unit shown in Fig. 7.

Fig. 10 shows a refrigeration apparatus and a heat source-side unit according to a fourth embodiment.

Fig. 11 shows a first state of the refrigeration apparatus and the heat source-side unit shown in Fig. 11.

Fig. 12 shows a second state of the refrigeration apparatus and the heat source-side unit shown in Fig. 11.

Fig. 13 shows a variation of the refrigeration apparatus and the heat source-side unit according to the fourth embodiment.

Fig. 14 shows another variation of the refrigeration apparatus and the heat source-side unit according to the first embodiment.

Fig. 15 shows a first state of yet another variation of the refrigeration apparatus and the heat source-side unit according to the first embodiment.

Fig. 16 shows a second state of the refrigeration apparatus and the heat source-side unit shown in Fig. 15.

Fig. 17 shows a first state of a variation of the refrigeration apparatus and the heat source-side unit shown in Figs. 15 and 16.

Fig. 18 shows yet another variation of the refrigeration apparatus and the heat source-side unit according to the first embodiment.

DESCRIPTION OF EMBODIMENTS

[0010] In the following, embodiments of the present invention are described with reference to the drawings. Note that the same or corresponding parts are designated by the same reference characters in the drawings and description thereof will not be repeated in principle.

[0011] First Embodiment As shown in Figs. 1 to 3, a refrigeration apparatus 100 according to a first embodiment includes a refrigerant circuit through which refrigerant circulates. The refrigerant circuit includes a compressor 1, a heat source-side heat exchanger 2, an auxiliary heat exchanger 3, a first decompression unit 4, a use-side heat exchanger 5, a second decompression unit 6, a plurality of flow path switching units, and a plurality of flow directing units. Refrigeration apparatus 100 further includes a first fan 7, a second fan 8, and a third fan 9. Although not particularly limited, the refrigerant is one having a low global warming potential (GWP), for example, and includes at least one selected from the group consisting of R410A, R32 and CO2. The refrigerant may be mixed refrigerant including at least one selected from the group above.

[0012] Compressor 1 has a suction port IA through which the refrigerant is sucked, and a discharge port 1B through which the refrigerant is discharged. Compressor 1 is an inverter compressor having an inverter-controlled rotational speed, for example.

Heat source-side heat exchanger 2, auxiliary heat exchanger 3 and use-side heat exchanger 5 are provided to exchange heat between the refrigerant and the air, for example. Heat source-side heat exchanger 2 has a first flow inlet/outlet portion 2A and a second flow inlet/outlet portion 2B through which the refrigerant flows in/out.

Auxiliary heat exchanger 3 has a third flow inlet/outlet portion 3A and a fourth flow inlet/outlet portion 3B through which the refrigerant flows in/out. Use-side heat exchanger 5 has a fifth flow inlet/outlet portion SA and a sixth flow inlet/outlet portion 5B through which the refrigerant flows in/out. First decompression unit 4 and second decompression unit 6 are each an electronic expansion valve having an adjustable degree of opening, for example. Note that first decompression unit 4 and second decompression unit 6 may each be a capillary tube having a non-adjustable degree of opening.

[0013] Use-side heat exchangers is disposed in a space to be cooled by refrigeration apparatus 100, for example, in a freezer. Compressor 1, heat source-side heat exchanger 2, auxiliary heat exchanger 3, first decompression unit 4, and second decompression unit 6 are disposed outside the above-described space, for example, outside the freezer. First fan 7 supplies the air outside of the freezer to heat source-side heat exchanger 2. Second fan 8 supplies the air outside of the freezer to auxiliary heat exchanger 3. Third fan 9 supplies the air inside of the freezer to use-side heat exchanger 5.

[0014] The plurality of flow path switching units are provided to switch a circulation path of the refrigerant in the refrigerant circuit to thereby switch between a first state and a second state which will be described later. The plurality of flow path switching units include a first flow path switching unit and a second flow path switching unit, for example. A first flow path switching unit 10A has a first on-off valve 11, a second on-off valve 12, a fifth on-off valve 15 and a sixth on-off valve 16, for example. A second flow path switching unit 10B has a third on-off valve 13 and a fourth on-off valve 14, for example. Note that the first flow path switching unit may have two three-way valves instead of the four on-off valves. The second flow path switching unit may have one three-way valve instead of the two on-off valves.

[0015] The refrigerant circuit has a first flow path and a second flow path connecting discharge port 1B of compressor 1 with fifth flow inlet/outlet portion SA of use-side heat exchanger 5, and a third flow path and a fourth flow path connecting sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 with suction port IA of compressor [0016] The first flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 through auxiliary heat exchanger 3 and heat source-side heat exchanger 2. In the first flow path, discharge port 1B of compressor 1, auxiliary heat exchanger 3, heat source-side heat exchanger 2, first decompression unit 4, and fifth flow inlet/outlet portion SA of use-side heat exchanger are successively connected in series. In the first flow path, first on-off valve 11 and fifth on-off valve 15 to open and/or close the first flow path are disposed. First on-off valve 11 is disposed between discharge port 1B of compressor 1 and third flow inlet/outlet portion 3A of auxiliary heat exchanger 3. Fifth on-off valve 15 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and first decompression unit 4, and between discharge port 1B of compressor 1 and first decompression unit 4.

[0017] The second flow path connects discharge port 1B of compressor] with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 not through auxiliary heat exchanger 3 and heat source-side heat exchanger 2. In the second flow path, discharge port 1B of compressor I and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 are connected in series. In the second flow path, second on-off valve 12 and sixth on-off valve 16 to open and/or close the second flow path are disposed.

Second on-off valve 12 is disposed between discharge port 1B of compressor 1 and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5. Sixth on-off valve 16 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5, and between discharge port 1B of compressor 1 and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5.

[0018] The first flow path and the second flow path have a first branch point, a second branch point, a fifth branch point, and a sixth branch point, where branches or joins of the refrigerant occur. In the first flow path and the second flow path, the first branch point, the second branch point, the fifth branch point, and the sixth branch point are successively connected in series. The first branch point is disposed upstream of third flow inlet/outlet portion 3A of auxiliary heat exchanger 3 in the first flow path. The second branch point is disposed downstream of second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and upstream of first decompression unit 4 in the first flow path. The fifth branch point is disposed downstream of the second branch point and upstream of first decompression unit 4 in the first flow path. The sixth branch point is disposed downstream of first decompression unit 4 in the first flow path.

[0019] The first flow path and the second flow path connect the first branch point and the second branch point in parallel with each other, and connect the fifth branch point and the sixth branch point in parallel with each other. The first flow path and the second flow path connect discharge port 1B of compressor 1 with the first branch point by a common pipe passage, and connect the sixth branch point with fifth flow inlet/outlet portion SA of use-side heat exchanger 5 by a common pipe passage.

[0020] From a different viewpoint, the second flow path has a first bypass flow path and a second bypass flow path branching off from the first flow path. The first bypass flow path connects the first branch point with the second branch point. The second bypass flow path connects the fifth branch point with the sixth branch point. The first bypass flow path thus bypasses auxiliary heat exchanger 3 and heat source-side heat exchanger 2. The second bypass flow path bypasses first decompression unit 4. First flow path switching unit 10A is provided to switch between the first flow path and the first bypass flow path. A third flow path switching unit 10C is provided to switch between the first flow path and the second bypass flow path. The second flow path is formed by closing of the first flow path and opening of the first bypass flow path and the second bypass flow path by first flow path switching unit 10A and third flow path switching unit 10C.

[0021] As shown in Figs. 1 to 3, the first flow path and the second flow path have a first common flow path CI, a second common flow path C2, and a fifth common flow path CS, each formed by a common pipe passage. Further, the first flow path has a first non-common flow path L 1 and a fifth non-common flow path LS, each formed by a pipe passage different from that of the second flow path. The second flow path has a second non-common flow path L2 and a sixth non-common flow path L6, each formed by a pipe passage different from that of the first flow path.

[0022] First common flow path Cl has one end connected with discharge port 1B of compressor 1. First common flow path Cl has the other end connected with the first branch point. First common flow path C1 is disposed between discharge port 1B of compressor 1 and first flow path switching unit 10A.

[0023] Second common flow path C2 has one end connected with the second branch point. Second common flow path C2 has the other end connected with the fifth branch point. Second common flow path C2 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and first decompression unit 4 in the first flow path.

[0024] Fifth common flow path C5 has one end connected with the sixth branch point.

Fifth common flow path C5 has the other end connected with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5. Fifth common flow path C5 is disposed between first decompression unit 4 and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 in the first flow path.

[0025] First non-common flow path Ll and second non-common flow path L2 connect first common flow path Cl and second common flow path C2 in parallel with each other. First non-common flow path L t and second non-common flow path L2 each have one end connected with the first branch point. First non-common flow path Li and second non-common flow path L2 each have the other end connected with the second branch point. Second non-common flow path L2 forms the above-described first bypass flow path.

[0026] Fifth non-common flow path L5 and sixth non-common flow path L6 connect second common flow path C2 and fifth common flow path C5 in parallel with each other. Fifth non-common flow path L5 and sixth non-common flow path L6 each have one end connected with the fifth branch point. Fifth non-common flow path L5 and sixth non-common flow path L6 each have the other end connected with the sixth branch point. Sixth non-common flow path L6 forms the above-described second bypass flow path.

[0027] In the first flow path, first common flow path CI, first non-common flow path Li, second common flow path C2, fifth non-common flow path L5, and fifth common flow path C5 are connected in series. In the second flow path, first common flow path CI, second non-common flow path L2, second common flow path C2, sixth non-common flow path L6, and fifth common flow path C5 are connected in series.

[0028] First non-common flow path Li includes auxiliary heat exchanger 3 and heat source-side heat exchanger 2. Fifth non-common flow path L5 includes first decompression unit 4. That is, the first flow path connects discharge port I B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 through auxiliary heat exchanger 3, heat source-side heat exchanger 2, and first decompression unit 4. First non-common flow path Ll further includes first on-off valve 11. Fifth non-common flow path L5 further includes fifth on-off valve 15. That is, the refrigerant flows through the first flow path when first on-off valve 11 and fifth on-off valve 15 are opened.

[0029] Second non-common flow path L2 does not include auxiliary heat exchanger 3 and heat source-side heat exchanger 2. Sixth non-common flow path L6 does not include first decompression unit 4. That is, the second flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 not through auxiliary heat exchanger 3, heat source-side heat exchanger 2, and first decompression unit 4. Second non-common flow path L2 includes second on-off valve 12. Sixth non-common flow path L6 includes sixth on-off valve 16.

That is, the refrigerant flows through the second flow path when second on-off valve 12 and sixth on-off valve 16 are opened.

[0030] The third flow path connects sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 with suction port IA of compressor 1 through second decompression unit 6 and auxiliary heat exchanger 3 In the third flow path, sixth flow inlet/outlet portion 5B of use-side heat exchanger 5, second decompression unit 6, auxiliary heat exchanger 3, and suction port lA of compressor 1 are successively connected in series. In the third flow path, third on-off valve 13 to open and/or close the third flow path is disposed. Third on-off valve 13 is disposed between fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 and suction port lA of compressor 1.

[0031] The fourth flow path connects sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 with suction port IA of compressor 1 not through second decompression unit 6 and auxiliary heat exchanger 3. In the fourth flow path, sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 and suction port lA of compressor 1 are connected in series. In the fourth flow path, fourth on-off valve 14 to open and/or close the fourth flow path is disposed. Fourth on-off valve 14 is disposed between sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 and suction port IA of compressor 1.

[0032] The third flow path and the fourth flow path have a third branch point and a fourth branch point, where branches or joins of the refrigerant occur. In the third flow path and the fourth flow path, the third branch point and the fourth branch point are successively connected in series. The third branch point is disposed upstream of second decompression unit 6 in the third flow path. The fourth branch point is disposed downstream of fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 in the third flow-path.

[0033] The third flow path and the fourth flow path connect the third branch point and the fourth branch point in parallel with each other. The third flow path and the fourth flow path connect sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 with the third branch point by a common pipe passage, and connect the fourth branch point with suction port lA of compressor 1 by a common pipe passage.

[0034] From a different viewpoint, the fourth flow path has a third bypass flow path branching off from the third flow path. The third bypass flow path has one end connected with the third branch point, and the other end connected with the fourth branch point. Second flow path switching unit 10B is provided to switch between the third flow path and the third bypass flow path. The fourth flow path is formed by closing of the third flow path and opening of the third bypass flow path by second flow path switching unit 10B.

[0035] As shown in Figs. 1 to 3, the third flow path and the fourth flow path have a third common flow path C3 and a fourth common flow path C4, each formed by a common pipe passage. Further, the third flow path has a third non-common flow path L3 formed by a pipe passage different from that of the fourth flow path. The fourth flow path has a fourth non-common flow path L4 formed by a pipe passage different from that of the third flow path.

-10 - [0036] Third common flow path C3 has one end connected with sixth flow inlet/outlet portion 5B of use-side heat exchanger 5. That is, third common flow path C3 is connected with fifth common flow path C5 through use-side heat exchanger 5. Third common flow path C3 has the other end connected with the third branch point. Third common flow path C3 is disposed between sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 and second decompression unit 6 in the third flow path.

[0037] Fourth common flow path C4 has one end connected with the fourth branch point. Fourth common flow path C4 has the other end connected with suction port IA of compressor I. Fourth common flow path C4 is disposed between second flow path switching unit 10B and suction port IA of compressor 1.

[0038] Third non-common flow path L3 and fourth non-common flow path L4 connect third common flow path C3 and fourth common flow path C4 in parallel with each other. Fourth non-common flow path L4 forms the above-described third bypass flow path. In the third flow path, third common flow path C3, third non-common flow path L3, and fourth common flow path C4 are connected in series. In the fourth flow path, third common flow path C3, fourth non-common flow path L4, and fourth common flow path C4 are connected in series.

[0039] Third non-common flow path L3 includes second decompression unit 6 and auxiliary heat exchanger 3. The third flow path connects sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 with suction port IA of compressor 1 through second decompression unit 6 and auxiliary heat exchanger 3. Fourth non-common flow path L4 does not include second decompression unit 6 and auxiliary heat exchanger 3. The fourth flow path connects sixth flow inlet/outlet portion 5B of use-side heat exchanger S with suction port IA of compressor I not through second decompression unit 6 and auxiliary heat exchanger 3. Third non-common flow path L3 further includes third on-off valve 13. Fourth non-common flow path L4 further includes fourth on-off valve 14. That is, the refrigerant flows through the third flow path when third on-off valve 13 is opened, and flows through the fourth flow path when fourth on-off valve 14 is opened.

[0040] As shown in Fig. 2, in the first state, first on-off valve 11, fourth on-off valve 14, and fifth on-off valve 15 are opened, while second on-off valve 12, third on-off valve 13, and sixth on-off valve 16 are closed. As shown in Fig. 3, in the second state, first on-off valve 11, fourth on-off valve 14, and fifth on-off valve 15 are closed, while second on-off valve 12, third on-off valve 13, and sixth on-off valve 16 are opened.

[0041] First non-common flow path Li of the first flow path and third non-common flow path L3 of the third flow path commonly include auxiliary heat exchanger 3 That is, first non-common flow path Li and third non-common flow path L3 have a sixth common flow path Co including auxiliary heat exchanger 3.

[0042] The refrigerant circuit further includes a plurality of flow directing units to direct a flow of the refrigerant. The plurality of flow directing units include a first flow directing unit 17, a second flow directing unit 18, and a third flow directing unit 19.

[0043] First flow directing unit 17 is disposed between second decompression unit 6 and third flow inlet/outlet portion 3A of auxiliary heat exchanger 3, specifically, between second decompression unit 6 and sixth common flow path C6, in third non-common flow path L3. First flow directing unit 17 allows a flow of the refrigerant from second decompression unit 6 toward third flow inlet/outlet portion 3A of auxiliary heat exchanger 3, and limits a flow of the refrigerant in the opposite direction.

[0044] Second flow directing unit 18 is disposed between fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 and first flow inlet/outlet portion 2A of heat source-side heat exchanger 2, specifically, between sixth common flow path C6 and first flow inlet/outlet portion 2A of heat source-side heat exchanger 2, in first non-common flow path Ll. Second flow directing unit 18 allows a flow of the refrigerant from fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 toward first flow inlet/outlet portion 2A of heat source-side heat exchanger 2, and limits a flow of the refrigerant in the opposite direction.

[0045] Third flow directing unit 19 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and the above-described second branch -12 -point in first non-common flow path Ll. Third flow directing unit 19 allows a flow of the refrigerant from second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 toward second common flow path C2, and limits a flow of the refrigerant in the opposite direction.

[0046] Refrigeration apparatus 100 includes a heat source-side unit 200 and a decompression unit 300 that are disposed outside the space to be cooled, and a use-side unit 400 that is disposed inside the space to be cooled. Heat source-side unit 200 is configured separately from decompression unit 300, for example. Heat source-side unit 200 is housed in a first casing. Decompression unit 300 is housed in a fifth casing. The first casing forms the outer profile of heat source-side unit 200. The fifth casing forms the outer profile of decompression unit 300. The first casing houses therein: part of the above-described refrigerant circuit including compressor 1, heat source-side heat exchanger 2, auxiliary heat exchanger 3, and second decompression unit 6; and first fan 7 and second fan 8. The fifth casing houses therein part of the above-described refrigerant circuit including first decompression unit 4. Part of each of the first flow path and the second flow path, as well as the third flow path and the fourth flow path are disposed in the first casing. Another part of each of the first flow path and the second flow path is disposed in the fifth casing.

[0047] Use-side unit 400 includes a not-shown second casing. The second casing forms the outer profile of use-side unit 400. The second casing houses therein: another part of the above-described refrigerant circuit including use-side heat exchanger 5; and third fan 9. The part of the above-described refrigerant circuit disposed in the first casing and the another part of the above-described refrigerant circuit disposed in the second casing are connected with each other through two pipes.

[0048] Heat source-side unit 200 includes a first unit 500 and a second unit 600, for example, with each unit being configured as a connecting body detachably connected with each other. First unit 500 includes compressor 1, heat source-side heat exchanger 2, and first fan 7, for example. Second unit 600 includes auxiliary heat exchanger 3, second fan 8, first flow path switching unit 10A, second flow path -13 -switching unit 10B, first flow directing unit 17, second flow directing unit 18, and third flow directing unit 19. Decompression unit 300 includes first decompression unit 4 and third flow path switching unit 10C.

[0049] First unit 500 is connected with second unit 600 through a total of four pipes, which are a first pipe 2]0A forming part of first common flow path Cl, a second pipe 210B and a third pipe 210C each forming part of first non-common flow path Li, and a fourth pipe 210D forming part of fourth common flow path C4. Second unit 600 is connected with decompression unit 300 through a pipe forming part of second common flow path C2. Second unit 600 is connected with use-side unit 400 through a pipe forming part of third common flow path C3. Decompression unit 300 is connected with use-side unit 400 through a pipe forming part of fifth common flow path C5. Although first unit 500 and second unit 600 are disposed adjacent to each other, for example, they may be disposed at a distance from each other.

[0050] First unit 500 further includes a not-shown third casing, for example. Second unit 600 further includes a not-shown fourth casing. Decompression unit 300 further includes the not-shown fifth casing, for example. The third casing houses therein compressor 1, heat source-side heat exchanger 2, and first fan 7. The fourth casing houses therein auxiliary heat exchanger 3, second decompression unit 6, second fan 8, first flow path switching unit 10A, second flow path switching unit 10B, first flow directing unit 17, second flow directing unit 18, and third flow directing unit 19. The fifth casing houses therein first decompression unit 4 and third flow path switching unit 10C. The third casing and the fourth casing are housed in the first casing.

[0051] <Operation of Refrigeration Apparatus> Refrigeration apparatus 100 switches between cooling operation of cooling the space to be cooled by use-side heat exchanger 5 acting as an evaporator, and defrosting operation of melting and removing frost formed on use-side heat exchanger 5 due to the cooling operation. During the cooling operation of refrigeration apparatus 100, the refrigerant circuit is in the first state shown in Fig. 2. During the defrosting operation of refrigeration apparatus 100, the refrigerant circuit is in the second state shown in Fig. -14 - 3. Switching between the first state and the second state is done by the plurality of flow path switching units.

[0052] As shown in Fig. 2, in the first state, first on-off valve 11, fourth on-off valve 14, and fifth on-off valve 15 are opened, while second on-off valve 12, third on-off valve 13, and sixth on-off valve 16 are closed. Thus, in the first state, the refrigerant flows through the first flow path and the fourth flow path, and does not flow through the second flow path and the third flow path. That is, in the first state, the refrigerant flows successively through compressor I, auxiliary heat exchanger 3, heat source-side heat exchanger 2, first decompression unit 4, and use-side heat exchanger 5, with heat source-side heat exchanger 2 and auxiliary heat exchanger 3 acting as a first condenser, and use-side heat exchanger 5 acting as a first evaporator. As a result, when the refrigerant circuit is in the first state, refrigeration apparatus 100 can cool the space to be cooled.

[0053] As shown in Fig. 3, in the second state, second on-off valve 12, third on-off valve 13, and sixth on-off valve 16 are opened, while first on-off valve 11, fourth on-off valve 14, and fifth on-off valve 15 are closed. Thus, in the second state, the refrigerant flows through the second flow path and the third flow path, and does not flow through the first flow path and the fourth flow path. That is, in the second state, the refrigerant flows successively through compressor 1, use-side heat exchanger 5, second decompression unit 6, and auxiliary heat exchanger 3, with use-side heat exchanger 5 acting as a second condenser, and auxiliary heat exchanger 3 acting as a second evaporator. That is, when the refrigerant circuit is in the second state, refrigeration apparatus 100 can defrost use-side heat exchanger 5. Note that second fan 8 supplies a sufficient amount of air to auxiliary heat exchanger 3 in the first state and the second state. On the other hand, first fan 7 is stopped from being driven in the second state, for example. Alternatively, a rotational speed of first fan 7 in the second state is reduced compared to that in the first state.

[0054] Third on-off valve 13 and first flow directing unit 17 prevent the refrigerant discharged from compressor 1 from flowing to the third flow path from sixth common -15 -flow path C6 in the first state. Second flow directing unit 18 prevents high-pressure liquid-phase refrigerant located upstream of first flow inlet/outlet portion 2A of heat source-side heat exchanger 2 from being sucked into compressor 1 during switching from the first state to the second state. Third flow directing unit 19 prevents the refrigerant discharged from compressor 1 from flowing to first non-common flow path Li from the second flow path in the second state.

[0055] Switching from the first state to the second state and switching from the second state to the first state is done regularly, for example. The switching from the first state to the second state is done, for example, when a time elapsed since the last switching from the second state to the first state reaches a predetermined time. Alternatively, the switching from the first state to the second state may be done upon detection of the formation of frost on use-side heat exchanger 5. When the detection of frost formation is performed by a detection device, for example, the switching from the first state to the second state may be done by switching of the plurality of flow path switching units based on a control signal which is output from the detection device.

When the detection of frost formation is performed by an operator, for example, the switching from the first state to the second state may be done by switching of the plurality of flow path switching units based on a control signal which is input by the operator.

[0056] The switching from the second state to the first state is done, for example, when a refrigerant temperature at sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 (outlet pipe temperature) becomes equal to or higher than a predetermined temperature.

[0057] <Advantageous Effects> Refrigeration apparatus 100 includes the refrigerant circuit through which the refrigerant circulates. The refrigerant circuit includes compressor 1, heat source-side heat exchanger 2, auxiliary heat exchanger 3, first decompression unit 4, use-side heat exchanger 5, second decompression unit 6, and the flow path switching unit. The flow path switching unit switches between the first state and the second state. In the -16 -first state, heat source-side heat exchanger 2 and auxiliary heat exchanger 3 act as a first condenser, use-side heat exchanger 5 acts as a first evaporator, and the refrigerant flows successively through compressor 1, the first condenser, first decompression unit 4, and the first evaporator. In the second state, use-side heat exchanger 5 acts as a second condenser, auxiliary heat exchanger 3 acts as a second evaporator, and the refrigerant flows successively through compressor 1, the second condenser, second decompression unit 6, and the second evaporator.

[0058] During the defrosting operation of refrigeration apparatus 100, the refrigerant circuit is in the second state, and auxiliary heat exchanger 3 acts as an evaporator.

Thus, unlike a conventional refrigeration apparatus provided such that refrigerant flows through only a use-side heat exchanger and does not flow through any other heat exchangers during defrosting operation, refrigeration apparatus 100 performs defrosting operation utilizing a refrigeration cycle. As a result, the defrosting operation of refrigeration apparatus 100 has improved efficiency compared to that of the above-described conventional refrigeration apparatus, and refrigeration apparatus 100 has a shortened defrosting operation time compared to that of the above-described conventional refrigeration apparatus.

[0059] Further, during the cooling operation of refrigeration apparatus 100, the refrigerant circuit is in the first state, and auxiliary heat exchanger 3 acts, together with heat source-side heat exchanger 2, as the first condenser. Thus, compared to a conventional refrigeration apparatus not including an auxiliary heat exchanger, refrigeration apparatus 100 can have an increased amount of heat exchange in the first condenser during the cooling operation. In this case, the cooling operation of refrigeration apparatus 100 has improved efficiency compared to that of the above-described conventional refrigeration apparatus. Further, refrigeration apparatus 100 has reduced power consumption during the cooling operation compared to that of the above-described conventional refrigeration apparatus.

[0060] Note that during the defrosting operation of refrigeration apparatus 100, frost may be formed on auxiliary heat exchanger 3 acting as an evaporator.

-17 - [0061] In this respect, in the first state of refrigeration apparatus 100, auxiliary heat exchanger 3 is disposed upstream of heat source-side heat exchanger 2 in the refrigerant circuit. That is, in refrigeration apparatus 100, gas-phase refrigerant (hot gas) discharged from compressor 1 is supplied to auxiliary heat exchanger 3 in the first state. Refrigeration apparatus 100 can thus efficiently remove, during the cooling operation, the frost formed on auxiliary heat exchanger 3 during the defrosting operation.

[0062] Further, in refrigeration apparatus 100, the refrigerant condensed in auxiliary heat exchanger 3 is supplied to heat source-side heat exchanger 2 in the first state.

Thus, compared to when the refrigerant discharged from compressor 1 is supplied to heat source-side heat exchanger 2, temperature increase in first unit 500 is suppressed in refrigeration apparatus 100. As a result, in refrigeration apparatus 100, for example, temperature increase in first unit 500 to a level that may cause a malfunction of a controller that controls the rotational speed of compressor 1 is suppressed.

[0063] Further, in refrigeration apparatus 100, the refrigerant discharged from compressor 1 is supplied to auxiliary heat exchanger 3 in the first state, and hence the temperature in second unit 600 in the first state is relatively high. Thus, after the switching from the first state to the second state, auxiliary heat exchanger 3 acts as an evaporator under an environment of relatively high temperature. As a result, auxiliary heat exchanger 3 can evaporate the refrigerant with relatively high efficiency.

[0064] Further, in refrigeration apparatus 100, sixth non-common flow path L6 including sixth on-off valve 16 is provided, and hence a high degree of flexibility is provided in disposing first decompression unit 4 in the first flow path, compared to a refrigeration apparatus 105 shown in Fig. 14 which will be described later. Thus, in refrigeration apparatus 100, first decompression unit 4 can be disposed close to use-side heat exchanger 5 to thereby reduce pressure loss of the refrigerant in the first state. [0065] Further, in refrigeration apparatus 100, heat source-side heat exchanger 2 and auxiliary heat exchanger 3 are housed in the first casing. Thus, during the cooling operation of refrigeration apparatus 100, the temperature around heat source-side heat -18-exchanger 2 and auxiliary heat exchanger 3 is relatively high in the first casing. Thus, auxiliary heat exchanger 3 after the switching of refrigeration apparatus 100 from the cooling operation to the defrosting operation acts as an evaporator under an environment of relatively high temperature in the first casing. The refrigerant thus efficiently evaporates in auxiliary heat exchanger 3. As a result, refrigeration apparatus 100 has improved defrosting efficiency compared to that of refrigeration apparatus 100 in which heat source-side heat exchanger 2 and auxiliary heat exchanger 3 are not housed in a single casing.

[0066] Second Embodiment As shown in Figs. 4 to 6, a refrigeration apparatus 101 according to a second embodiment basically has a similar configuration to that of refrigeration apparatus 100 according to the first embodiment, but is different in that heat source-side heat exchanger 2 is disposed upstream of auxiliary heat exchanger 3 in the refrigerant circuit in the first state.

[0067] The refrigerant circuit of refrigeration apparatus 101 includes a fifth flow path and a sixth flow path instead of the first flow path and the second flow path of refrigeration apparatus 100. The fifth flow path and the sixth flow path connect discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5. As in refrigeration apparatus 100, sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 and suction port IA of compressor 1 are connected with each other by the third flow path and the fourth flow path in refrigeration apparatus 101.

[0068] The fifth flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 through auxiliary heat exchanger 3 and heat source-side heat exchanger 2. In the fifth flow path, discharge port 1B of compressor 1, heat source-side heat exchanger 2, auxiliary heat exchanger 3, first decompression unit 4, and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 are successively connected in series. In the fifth flow path, a seventh on-off valve 21 and fifth on-off valve 15 to open and/or close the fifth flow path are disposed.

-19 -Seventh on-off valve 21 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and third flow inlet/outlet portion 3A of auxiliary heat exchanger 3.

[0069] The sixth flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 not through auxiliary heat exchanger 3 and heat source-side heat exchanger 2. In the sixth flow path, discharge port 1B of compressor 1 and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 are connected in series. In the sixth flow path, an eighth on-off valve 22 and sixth on-off valve 16 to open and/or close the sixth flow path are disposed.

Eighth on-off valve 22 is disposed between discharge port 1B of compressor 1 and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5.

[0070] The fifth flow path and the sixth flow path have a seventh branch point, an eighth branch point, the above-described fifth branch point, and the above-described sixth branch point, where branches or joins of the refrigerant occur. In the fifth flow path and the sixth flow path, the seventh branch point, the eighth branch point, the fifth branch point, and the sixth branch point are successively connected in series. The seventh branch point is disposed upstream of first flow inlet/outlet portion 2A of heat source-side heat exchanger 2 in the first flow path. The eighth branch point is disposed downstream of fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 and upstream of first decompression unit 4 in the first flow path.

[0071] The fifth flow path and the sixth flow path connect the seventh branch point and the eighth branch point in parallel with each other, and connect the fifth branch point and the sixth branch point in parallel with each other. The fifth flow path and the sixth flow path connect discharge port 1B of compressor 1 with the seventh branch point by a common pipe passage, and connect the sixth branch point with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 by a common pipe passage. [0072] From a different viewpoint, the sixth flow path has a fourth bypass flow path and the above-described second bypass flow path branching off from the fifth flow path. The fourth bypass flow path has one end connected with the seventh branch -20 -point. The fourth bypass flow path has the other end connected with the eighth branch point. The fourth bypass flow path thus bypasses heat source-side heat exchanger 2 and auxiliary heat exchanger 3. Eighth on-off valve 22 opens and/or closes the fourth bypass flow path. The sixth flow path is formed by closing of the fifth flow path by seventh on-off valve 21 and fifth on-off valve 15, and opening of the fourth bypass flow path and the second bypass flow path by eighth on-off valve 22 and sixth on-off valve 16.

[0073] As shown in Figs. 4 to 6, part of each of the fifth flow path and the sixth flow path is formed by a common pipe passage, and the rest is formed by different pipe passages. The fifth flow path and the sixth flow path have a seventh common flow path C7, an eighth common flow path CS, and fifth common flow path C5, each formed by a common pipe passage. Further, the fifth flow path has a seventh non-common flow path L7 and fifth non-common flow path L5, each formed by a pipe passage different from that of the sixth flow path. The sixth flow path has an eighth non-common flow path L8 and sixth non-common flow path L6, each formed by a pipe passage different from that of the fifth flow path.

[0074] Seventh common flow path C7 has one end connected with discharge port 1B of compressor 1. Seventh common flow path C7 has the other end connected with the seventh branch point.

[0075] Eighth common flow path C8 has one end connected with the eighth branch point. Eighth common flow path C8 has the other end connected with the fifth branch point.

[0076] Seventh non-common flow path L7 and eighth non-common flow path L8 connect seventh common flow path C7 and eighth common flow path C8 in parallel with each other. Fifth non-common flow path L5 and sixth non-common flow path L6 connect eighth common flow path C8 and fifth common flow path C.5 in parallel with each other. In the fifth flow path, seventh common flow path C7, seventh non-common flow path L7, eighth common flow path C8, fifth non-common flow path L5, and fifth common flow path C5 are connected in series. In the sixth flow path, -21 -seventh common flow path C7, eighth non-common flow path L8, eighth common flow path C8, sixth non-common flow path L6, and fifth common flow path C5 are connected in series.

[0077] Seventh non-common flow path L7 includes heat source-side heat exchanger 2 and auxiliary heat exchanger 3. Fifth non-common flow path L5 includes first decompression unit 4. That is, the fifth flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 through heat source-side heat exchanger 2, auxiliary heat exchanger 3, and first decompression unit 4. Seventh non-common flow path L7 further includes seventh on-off valve 2] and fifth on-off valve 15. That is, the refrigerant flows through the fifth flow path when seventh on-off valve 21 and fifth on-off valve 15 are opened. [0078] Eighth non-common flow path L8 does not include heat source-side heat exchanger 2 and auxiliary heat exchanger 3. Eighth non-common flow path L8 forms the above-described fourth bypass flow path. That is, the sixth flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 not through heat source-side heat exchanger 2, auxiliary heat exchanger 3, and first decompression unit 4. Eighth non-common flow path L8 further includes eighth on-off valve 22 and sixth on-off valve 16. That is, the refrigerant flows through the sixth flow path when eighth on-off valve 22 and sixth on-off valve 16 are opened.

[0079] As shown in Figs. 4 to 6, seventh on-off valve 21, eighth on-off valve 22, fifth on-off valve 15, and sixth on-off valve 16 form a fourth flow path switching unit 20A provided to switch between the fifth flow path and the sixth flow path.

[0080] In the first state, seventh on-off valve 21, fifth on-off valve 15, and fourth on-off valve 14 are opened, while eighth on-off valve 22, sixth on-off valve 16, and third on-off valve 13 are closed. In the second state, seventh on-off valve 21, fifth on-off valve 15, and fourth on-off valve 14 are closed, while eighth on-off valve 22, sixth on-off valve 16, and third on-off valve]3 are opened.

[0081] Seventh non-common flow path L7 of the fifth flow path and third non- -22 -common flow path L3 of the third flow path commonly include auxiliary heat exchanger 3. That is, seventh non-common flow path L7 and third non-common flow path L3 have a ninth common flow path C9 including auxiliary heat exchanger 3. [0082] The refrigerant circuit further includes a plurality of flow directing units to direct a flow of the refrigerant. The plurality of flow directing units include first flow directing unit 17 and a fourth flow directing unit 23.

[0083] Fourth flow directing unit 23 is disposed between fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 and the above-described eighth branch point, specifically, between ninth common flow path C9 and the above-described eighth branch point, in seventh non-common flow path L7. Fourth flow directing unit 23 allows a flow of the refrigerant from fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 toward eighth common flow path C8, and limits a flow of the refrigerant in the opposite direction.

[0084] Third on-off valve 13, fourth on-off valve 14, fifth on-off valve 15, sixth on-off valve 16, first flow directing unit 17, seventh on-off valve 21, eighth on-off valve 22, and fourth flow directing unit 23 are disposed in a heat source-side unit 201, specifically, in a second unit 601.

[0085] In refrigeration apparatus 101, a first unit 501 and second unit 601 are connected with each other through a total of three pipes, which are a fifth pipe 210E forming seventh non-common flow path L7, a sixth pipe 210F forming eighth non-common flow path L8, and fourth pipe 210D forming fourth common flow path C4. [0086] <Operation of Refrigeration Apparatus> As described above, refrigeration apparatus 101 is switched between the first state shown in Fig. 5 and the second state shown in Fig. 6 by the plurality of flow path switching units.

[0087] As shown in Fig. 5, in the first state, seventh on-off valve 21, fourth on-off valve 14, and fifth on-off valve 15 are opened, while eighth on-off valve 22, third on-off valve 13, and sixth on-off valve 16 are closed. Thus, the refrigerant flows through the fifth flow path and the fourth flow path, and does not flow through the sixth flow -2,3 - path and the third flow path. That is, in the first state, the refrigerant flows successively through compressor 1, heat source-side heat exchanger 2, auxiliary heat exchanger 3, first decompression unit 4, and use-side heat exchanger 5. Heat source-side heat exchanger 2 and auxiliary heat exchanger 3 act as a first condenser, and use-side heat exchanger 5 acts as a first evaporator. As a result, in the first state, refrigeration apparatus 101 cools the space to be cooled.

[0088] As shown in Fig. 6, in the second state, eighth on-off valve 22, third on-off valve 13, and sixth on-off valve 16 are opened, while seventh on-off valve 21, fourth on-off valve 14, and fifth on-off valve 15 are closed. Thus, the refrigerant flows through the sixth flow path and the third flow path, and does not flow through the fifth flow path and the fourth flow path. That is, in the second state, the refrigerant flows successively through compressor 1, use-side heat exchanger 5, second decompression unit 6, and auxiliary heat exchanger 3. As a result, in the second state, use-side heat exchanger 5 acts as a second condenser, and auxiliary heat exchanger 3 acts as a second evaporator. That is, refrigeration apparatus 101 defrosts use-side heat exchanger 5 while the second state is implemented.

[0089] Third on-off valve 13 and first flow directing unit 17 prevent the refrigerant discharged from compressor 1 from flowing to the third flow path from ninth common flow path C9 in the first state. Fourth flow directing unit 23 prevents the refrigerant discharged from compressor 1 from flowing to third non-common flow path L3 from the sixth flow path in the second state.

[0090] <Advantageous Effects> Refrigeration apparatus 101 basically has a similar configuration to that of refrigeration apparatus 100, and can therefore produce similar effects to those of refrigeration apparatus 100.

[0091] Further, in refrigeration apparatus 101, discharge port 1B of compressor 1 and first flow inlet/outlet portion 2A of heat source-side heat exchanger 2 are directly connected with each other not through an on-off valve and the like in the first state. Thus, in refrigeration apparatus 101, the shortest distance on the refrigerant circuit -24 -between discharge port 1B of compressor 1 and the condenser in the first state can be shortened compared to that in refrigeration apparatus 100. In this case, the length of a pipe through which the gas-phase refrigerant flows in refrigeration apparatus 101 is shorter than the length of a pipe through which the gas-phase refrigerant flows in refrigeration apparatus 100. In such refrigeration apparatus 101, pressure loss of the refrigerant during the cooling operation is reduced compared to that in refrigeration apparatus 100.

[0092] Further, in refrigeration apparatus 101, first unit 501 and second unit 601 are connected with each other through a total of three pipes, which are fifth pipe 210E forming seventh non-common flow path L7, sixth pipe 210F forming eighth non-common flow path L8, and fourth pipe 210D forming fourth common flow path C4. That is, the number of pipes connecting first unit 501 with second unit 601 in refrigeration apparatus 101 is smaller than the number of pipes connecting first unit 500 with second unit 600 in refrigeration apparatus 100. Heat source-side unit 201 thus has higher assembly efficiency than that of heat source-side unit 200.

[0093] Third Embodiment As shown in Figs. 7 to 9, a refrigeration apparatus 102 according to a third embodiment basically has a similar configuration to that of refrigeration apparatus 100 according to the first embodiment, but is different in that heat source-side heat exchanger 2 and auxiliary heat exchanger 3 are connected in parallel with each other in the first state.

[0094] The refrigerant circuit of refrigeration apparatus 102 has a seventh flow path and an eighth flow path instead of the first flow path and the second flow path of refrigeration apparatus 100. The seventh flow path and the eighth flow path connect discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5. As in refrigeration apparatus 100, sixth flow inlet/outlet portion 5B of use-side heat exchanger 5 and suction port IA of compressor I are connected with each other by the third flow path and the fourth flow path in refrigeration apparatus 102.

-25 - [0095] The seventh flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 through heat source-side heat exchanger 2, and connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion SA of use-side heat exchanger 5 through auxiliary heat exchanger 3 In the seventh flow path, discharge port 1B of compressor 1, heat source-side heat exchanger 2, first decompression unit 4, and fifth flow inlet/outlet portion SA of use-side heat exchanger 5 are successively connected in series, and discharge port 1B of compressor 1, auxiliary heat exchanger 3, first decompression unit 4, and fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 are connected in series. Stated differently, in the seventh flow path, heat source-side heat exchanger 2 and auxiliary heat exchanger 3 are connected in parallel with each other.

[0096] In the seventh flow path, a ninth on-off valve 31, a tenth on-off valve 32, and fifth on-off valve 15 to open and/or close the seventh flow path are disposed. Ninth on-off valve 31 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and first decompression unit 4. Tenth on-off valve 32 is disposed between discharge port 1B of compressor 1 and third flow inlet/outlet portion 3A of auxiliary heat exchanger 3.

[0097] The eighth flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion SA of use-side heat exchanger 5 not through heat source-side heat exchanger 2 and auxiliary heat exchanger 3. In the eighth flow path, discharge port 1B of compressor 1 and fifth flow inlet/outlet portion SA of use-side heat exchanger 5 are successively connected in series.

[0098] In the eighth flow path, an eleventh on-off valve 33 and sixth on-off valve 16 to open and/or close the eighth flow path are disposed. Eleventh on-off valve 33 is disposed between discharge port 1B of compressor 1 and fifth flow inlet/outlet portion SA of use-side heat exchanger 5 third flow inlet/outlet portion 3A of auxiliary heat exchanger 3.

[0099] The seventh flow path and the eighth flow path have a ninth branch point, a tenth branch point, the above-described fifth branch point, an eleventh branch point, a -26 -twelfth branch point, and the above-described sixth branch point, where branches or joins of the refrigerant occur. In the seventh flow path and the eighth flow path, the ninth branch point, the tenth branch point, the fifth branch point, and the sixth branch point are successively connected in series. In the seventh flow path, the ninth branch point, the twelfth branch point, the tenth branch point, the fifth branch point, and the sixth branch point are successively connected in series, and the ninth branch point, the eleventh branch point, the twelfth branch point, the tenth branch point, the fifth branch point, and the sixth branch point are successively connected in series.

[0100] The ninth branch point is disposed upstream of first flow inlet/outlet portion 2A of heat source-side heat exchanger 2 and third flow inlet/outlet portion 3A of auxiliary heat exchanger 3 in the seventh flow path. The tenth branch point is disposed downstream of second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 and upstream of first decompression unit 4 in the seventh flow path. The eleventh branch point is disposed downstream of the ninth branch point and upstream of third flow inlet/outlet portion 3A of auxiliary heat exchanger 3 in the seventh flow path. The twelfth branch point is disposed downstream of second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 and upstream of the tenth branch point in the seventh flow path.

[0101] From a different viewpoint, the eighth flow path has a seventh bypass flow path and the above-described second bypass flow path branching off from the seventh flow path. The seventh bypass flow path has one end connected with the eleventh branch point. The seventh bypass flow path has the other end connected with the tenth branch point. The seventh bypass flow path thus bypasses auxiliary heat exchanger 3 and heat source-side heat exchanger 2. Eleventh on-off valve 33 opens and/or closes the seventh bypass flow path. The eighth flow path is formed by closing of the seventh flow path by ninth on-off valve 31, tenth on-off valve 32, and fifth on-off valve 15, and opening of the seventh bypass flow path and the second bypass flow path by eleventh on-off valve 33 and sixth on-off valve 16.

-27 - [0102] As shown in Figs. 7 to 9, part of each of the seventh flow path and the eighth flow path is formed by a common pipe passage, and the rest is formed by different pipe passages. The seventh flow path and the eighth flow path have a tenth common flow path C10, an eleventh common flow path C11, a twelfth common flow path C12, and fifth common flow path C5, each formed by a common pipe passage. Further, the seventh flow path has a ninth non-common flow path L9, a tenth non-common flow path LID, and fifth non-common flow path L5, each formed by a pipe passage different from that of the eighth flow path. The eighth flow path has an eleventh non-common flow path Li I and sixth non-common flow path L6, each formed by a pipe passage different from that of the seventh flow path.

[0103] Tenth common flow path C10 has one end connected with discharge port 1B of compressor 1. Tenth common flow path C10 has the other end connected with one end of each of ninth non-common flow path L9 and eleventh common flow path C11, that is, the ninth branch point. Tenth common flow path C10 is disposed between discharge port 1B of compressor 1 and first flow inlet/outlet portion 2A of heat source-side heat exchanger 2, and between discharge port 1B of compressor 1 and third flow inlet/outlet portion 3A of auxiliary heat exchanger 3, in the seventh flow path.

[0104] Eleventh common flow path C 11 has one end connected with the above-described other end of tenth common flow path CIO and the above-described one end of ninth non-common flow path L9. Eleventh common flow path CI I has the other end connected with one end of each of tenth non-common flow path L10 and eleventh non-common flow path L11, that is, the eleventh branch point. Eleventh common flow path C11 is disposed between discharge port 1B of compressor 1 and third flow inlet/outlet portion 3A of auxiliary heat exchanger 3 in the seventh flow path.

[0105] Twelfth common flow path C12 has one end connected with the other end of each of ninth non-common flow path L9, tenth non-common flow path LIO, and eleventh non-common flow path Ell, that is, the tenth branch point. Twelfth common flow path C12 has the other end connected with the above-described fifth branch point of fifth non-common flow path L5 and sixth non-common flow path L6.

-28 -Twelfth common flow path C12 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and first decompression unit 4, and between fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 and first decompression unit 4, in the seventh flow path.

[0106] Ninth non-common flow path L9, tenth non-common flow path L10, and eleventh non-common flow path L11 connect tenth common flow path C10 and twelfth common flow path C12 in parallel with each other. Further, tenth non-common flow path LIO and eleventh non-common flow path L11 connect eleventh common flow path C11 and twelfth common flow path C12 in parallel with each other. Fifth non-common flow path L5 and sixth non-common flow path L6 connect twelfth common flow path C12 and fifth common flow path CS in parallel with each other. In the seventh flow path, tenth common flow path CIO, ninth non-common flow path L9, twelfth common flow path C12, fifth non-common flow path LS, and fifth common flow path CS are connected in series, and tenth common flow path C10, eleventh common flow path C11, tenth non-common flow path LID, twelfth common flow path CU, fifth non-common flow path LS, and fifth common flow path CS are connected in series. In the eighth flow path, tenth common flow path C10, eleventh common flow path C11, eleventh non-common flow path L11, twelfth common flow path C12, sixth non-common flow path L6, and fifth common flow path CS are connected in series.

[0107] Ninth non-common flow path L9 includes heat source-side heat exchanger 2.

Tenth non-common flow path LID includes auxiliary heat exchanger 3. That is, the seventh flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion SA of use-side heat exchanger 5 through heat source-side heat exchanger 2 and first decompression unit 4, and through auxiliary heat exchanger 3 and first decompression unit 4.

[0108] Eleventh non-common flow path L11 does not include heat source-side heat exchanger 2 and auxiliary heat exchanger 3. Eleventh non-common flow path L11 forms the above-described seventh bypass flow path. That is, the eighth flow path connects discharge port 1B of compressor 1 with fifth flow inlet/outlet portion SA of -29 -use-side heat exchanger 5 not through heat source-side heat exchanger 2, auxiliary heat exchanger 3, and first decompression unit 4.

[0109] Ninth non-common flow path L9 further includes ninth on-off valve 31. Tenth non-common flow path L10 further includes tenth on-off valve 32. Eleventh non-common flow path L11 further includes eleventh on-off valve 33.

[0110] Ninth non-common flow path L9 and tenth non-common flow path L10 of the seventh flow path have a thirteenth common flow path C13 formed by a common pipe passage. Thirteenth common flow path C13 has one end connected with the twelfth branch point where ninth non-common flow path L9 and tenth non-common flow path L10 join together. Thirteenth common flow path C13 has the other end connected with the tenth branch point. Ninth on-off valve 31 is provided on thirteenth common flow path C13, for example.

[0111] As shown in Figs. 7 to 9, ninth on-off valve 31, tenth on-off valve 32, eleventh on-off valve 33, fifth on-off valve 15, and sixth on-off valve 16 form a fifth switching unit provided to switch between the seventh flow path and the eighth flow path.

[0112] In the first state, ninth on-off valve 31, tenth on-off valve 32, fifth on-off valve 15, and third on-off valve 13 are opened, while eleventh on-off valve 33, sixth on-off valve 16, and fourth on-off valve 14 are closed. In the second state, ninth on-off valve 31, tenth on-off valve 32, fifth on-off valve 15, and third on-off valve 13 are closed, while eleventh on-off valve 33, sixth on-off valve 16, and fourth on-off valve 14 are opened.

[0113] Ninth non-common flow path L9 of the seventh flow path and third non-common flow path L3 of the third flow path commonly include auxiliary heat exchanger 3. That is, ninth non-common flow path L9 and third non-common flow path L3 have a fourteenth common flow path C14 including auxiliary heat exchanger 3.

[0114] The refrigerant circuit further includes a plurality of flow directing units to direct a flow of the refrigerant. The plurality of flow directing units include first flow directing unit 17, a fifth flow directing unit 34, and a sixth flow directing unit 35. [0115] Fifth flow directing unit 34 is disposed between fourth flow inlet/outlet portion -3 - 3B of auxiliary heat exchanger 3 and the above-described joint of ninth non-common flow path L9 and tenth non-common flow path L10 in tenth non-common flow path L10. Fifth flow directing unit 34 allows a flow of the refrigerant from fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 toward thirteenth common flow path C13, and limits a flow of the refrigerant in the opposite direction.

[0116] Sixth flow directing unit 35 is disposed between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and the above-described eleventh branch point in ninth non-common flow path L9. Sixth flow directing unit 35 allows at least a flow of the refrigerant from second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 toward twelfth common flow path C]2, and limits a flow of the refrigerant in the opposite direction. Sixth flow directing unit 35 is provided on thirteenth common flow path C13, for example. Sixth flow directing unit 35 allows a flow of the refrigerant from second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 toward twelfth common flow path C12, and a flow of the refrigerant from fourth flow inlet/outlet portion 3B of auxiliary heat exchanger 3 toward twelfth common flow path C12, and limits flows of the refrigerant in the opposite directions. [0117] Ninth on-off valve 3], tenth on-off valve 32, eleventh on-off valve 33, fifth on-off valve 15, sixth on-off valve 16, third on-off valve 13, fourth on-off valve 14, first flow directing unit 17, fifth flow directing unit 34, and sixth flow directing unit 35 are disposed in a heat source-side unit 202, specifically, in a second unit 602.

[0118] In refrigeration apparatus 102, a first unit 502 and second unit 602 are connected with each other through a total of three pipes, which are an eighth pipe 210H forming tenth non-common flow path L10, a ninth pipe 2101 forming ninth non-common flow path L9, and a tenth pipe 210J forming fourth common flow path C4.

[0119] <Operation of Refrigeration Apparatus> As described above, refrigeration apparatus 102 is switched between the first state shown in Fig. 8 and the second state shown in Fig. 9 by the plurality of flow path switching units.

[0120] As shown in Fig. 8, in the first state, ninth on-off valve 31, tenth on-off valve -3 - 32, fifth on-off valve 15, and third on-off valve 13 are opened, while eleventh on-off valve 33, sixth on-off valve 16, and fourth on-off valve 14 are closed. Thus, the refrigerant flows through the seventh flow path and the fourth flow path, and does not flow through the eighth flow path and the third flow path. That is, in the first state, the refrigerant flows successively through compressor 1, heat source-side heat exchanger 2, first decompression unit 4, and use-side heat exchanger 5, and flows successively through compressor 1, auxiliary heat exchanger 3, first decompression unit 4, and use-side heat exchanger 5. Heat source-side heat exchanger 2 and auxiliary heat exchanger 3 act as a third condenser, and use-side heat exchanger 5 acts as a third evaporator. As a result, in the first state, refrigeration apparatus 102 cools the space to be cooled.

[0121] As shown in Fig. 9, in the second state, ninth on-off valve 31, tenth on-off valve 32, fifth on-off valve 15, and third on-off valve 13 are closed, while eleventh on-off valve 33, sixth on-off valve 16, and fourth on-off valve 14 are opened. Thus, the refrigerant flows through the eighth flow path and the third flow path, and does not flow through the seventh flow path and the fourth flow path. That is, in the second state, the refrigerant flows successively through compressor 1, use-side heat exchanger 5, second decompression unit 6, and auxiliary heat exchanger 3. As a result, in the second state, use-side heat exchanger 5 acts as a second condenser, and auxiliary heat exchanger 3 acts as a second evaporator. That is, refrigeration apparatus 102 defrosts use-side heat exchanger 5 while the second state is implemented.

[0122] <Advantageous Effects> Refrigeration apparatus 102 basically has a similar configuration to that of refrigeration apparatus 100, and can therefore produce similar effects to those of refrigeration apparatus 100.

[0123] Further, in refrigeration apparatus 102, when the refrigerant circuit is in the first state, heat source-side heat exchanger 2 and auxiliary heat exchanger 3 are connected in parallel with discharge port 1B of compressor 1. Thus, in refrigeration apparatus 102, pressure loss of the refrigerant during the cooling operation is reduced compared to -3 -those in refrigeration apparatuses 100 and 101.

[0124] Further, in refrigeration apparatus 102, first unit 502 and second unit 602 are connected with each other through three pipes. Thus, the number of pipes connecting first unit 502 with second unit 602 in refrigeration apparatus 102 is smaller than the number of pipes connecting first unit 500 with second unit 600 in refrigeration apparatus 100. Heat source-side unit 202 thus has higher assembly efficiency than that of heat source-side unit 200.

[0125] Fourth Embodiment As shown in Figs. 10 to 12, a refrigeration apparatus 103 according to a fourth embodiment basically has a similar configuration to that of refrigeration apparatus 100 according to the first embodiment, but is different in that it further includes a heat medium circuit through which a heat medium circulates, and that heat source-side heat exchanger 2 is provided to exchange heat between the refrigerant circulating through the refrigerant circuit and the heat medium circulating through the heat medium circuit.

[0126] The heat medium circuit is disposed in a heat source-side unit 203, specifically, in a first unit 503. The heat medium circulating through the heat medium circuit is refrigerant, for example. Refrigeration apparatus 103 is configured as a so-called cascade refrigeration apparatus, where the above-described refrigerant circuit forms a low-temperature side circuit, and the heat medium circuit forms a high-temperature side circuit. The heat medium circuit includes a high-temperature side compressor 51, a high-temperature side condenser 52, a high-temperature side decompression unit 53, and heat source-side heat exchanger 2 acting as a high-temperature side evaporator. The above-described heat medium flows successively through high-temperature side compressor Si, high-temperature side condenser 52, high-temperature side decompression unit 53, and heat source-side heat exchanger 2. Second unit 600, decompression unit 300, and use-side unit 400 have similar configurations to those of second unit 600, decompression unit 300, and use-side unit 400 of refrigeration apparatus 100, respectively.

[0127] High-temperature side compressor 51 compresses and discharges the heat -33 -medium evaporated in heat source-side heat exchanger 2. In high-temperature side condenser 52, heat is exchanged between the heat medium discharged from high-temperature side compressor 51 and the air. In first unit 503, a fourth fan 54 to supply the air outside of the freezer to high-temperature side condenser 52 is disposed instead of first fan 7 in first unit 500. High-temperature side decompression unit 53 is an electronic expansion valve, for example [0128] Heat source-side heat exchanger 2 is a plate-type heat exchanger, for example. Heat source-side heat exchanger 2 further has a seventh flow inlet/outlet portion 2C and an eighth flow inlet/outlet portion 2D through which the heat medium flows in/out.

Seventh flow inlet/outlet portion 2C is connected with high-temperature side condenser 52 through high-temperature side decompression unit 53. Eighth flow inlet/outlet portion 2D is connected with a suction port of high-temperature side compressor 51. [0129] First unit 503 and second unit 600 are housed in the same casing, for example. In this case, auxiliary heat exchanger 3 and high-temperature side condenser 52 may be integrally provided, for example. From a different viewpoint, one region of one heat exchanger may form auxiliary heat exchanger 3, and another region of this one heat exchanger may form high-temperature side condenser 52.

[0130] <Operation of Refrigeration Apparatus> In refrigeration apparatus 103, switching between the first state shown in Fig. 11 and the second state shown in Fig. 12 is done by the plurality of flow path switching units. As shown in Figs. 11 and 12, the switching between the first state and the second state in refrigeration apparatus 103 is done in a manner similar to the switching between the eleventh state and the second state in refrigeration apparatus 100.

[0131] As shown in Fig. 11, when the refrigerant circuit is in the first state, the refrigerant in the refrigerant circuit and the heat medium in the heat medium circuit each repeat a refrigeration cycle. In the first state, the refrigerant flows successively through compressor 1, auxiliary heat exchanger 3, heat source-side heat exchanger 2, first decompression unit 4, and use-side heat exchanger 5, while the heat medium flows successively through high-temperature side compressor 51, high-temperature side -3 -condenser 52, high-temperature side decompression unit 53, and heat source-side heat exchanger 2. Thus, in the first state, heat is exchanged between the refrigerant and the heat medium in heat source-side heat exchanger 2, causing condensation of the refrigerant and evaporation of the heat medium. As a result, in the first state, heat source-side heat exchanger 2 and auxiliary heat exchanger 3 act as a first condenser, and use-side heat exchanger 5 acts as a first evaporator, allowing refrigeration apparatus 103 to cool the space to be cooled.

[0132] As shown in Fig. 12, when the refrigerant circuit is in the second state, only the refrigerant in the refrigerant circuit circulates through the refrigerant circuit and repeats the refrigeration cycle, and the heat medium in the heat medium circuit does not circulate through the heat medium circuit and repeat the refrigeration cycle. That is, when the refrigerant circuit is in the second state, refrigeration apparatus 103 operates in a manner similar to refrigeration apparatus 100, and defrosts use-side heat exchanger 5.

[0133] <Advantageous Effects> Refrigeration apparatus 103 basically has a similar configuration to that of refrigeration apparatus 100, and can therefore produce similar effects to those of refrigeration apparatus 100.

[0134] Further, being configured as a cascade refrigeration apparatus, refrigeration apparatus 103 has improved cooling efficiency compared to a refrigeration apparatus operating in a single refrigeration cycle. From a different viewpoint, since auxiliary heat exchanger 3 acts as a condenser in the refrigerant circuit in refrigeration apparatus 103, refrigeration apparatus 103 has improved cooling efficiency compared to that of a conventional cascade refrigeration apparatus not including auxiliary heat exchanger 3.

Further, refrigeration apparatus 103 has improved defrosting efficiency compared to that of the above-described conventional cascade refrigeration apparatus.

<Variations> A refrigeration apparatus 104 shown in Fig. 13 is a variation of refrigeration apparatus 103 shown in Figs. 10 to 12. Refrigeration apparatus 104 basically has a -3 -similar configuration to that of refrigeration apparatus 103, but is different in that the heat medium circulating through the above-described heat medium circuit is water, brine or the like. The heat medium in refrigeration apparatus 104 does not undergo a phase change when circulating through the heat medium circuit The heat medium circuit has a pump 55 instead of high-temperature side compressor 51 shown in Figs. to 12, and has a heat exchanger 56 instead of high-temperature side condenser 52. Pump 55 causes the heat medium to circulate through the heat medium circuit Heat exchanger 56 is provided to exchange heat between the heat medium circulating through the heat medium circuit and the air outside of the freezer. Auxiliary heat exchanger 3 is provided, as described above, to exchange heat between the refrigerant circulating through the refrigerant circuit and the air outside of the freezer. Thus, as in refrigeration apparatus 100, the first state and the second state are implemented in refrigeration apparatus 104 as well. As a result, refrigeration apparatus 104 can produce similar effects to those of refrigeration apparatus 100.

[0135] When auxiliary heat exchanger 3 is provided to exchange heat between the refrigerant circulating through the refrigerant circuit and the refrigerant circulating through the heat medium circuit, there is a possibility in auxiliary heat exchanger 3 during the defrosting operation that the heat medium may exchange heat with the refrigerant condensed in use-side heat exchanger 5, and freeze In contrast, in refrigeration apparatus 104, the refrigerant condensed in use-side heat exchanger 5 is not supplied to heat source-side heat exchanger 2, and hence the freezing of the heat medium is suppressed even during the defrosting operation. As in refrigeration apparatus 100, frost may be formed on auxiliary heat exchanger 3 due to the defrosting operation on use-side heat exchanger 5 in refrigeration apparatus 104 as well, but this frost can be melted and removed by the cooling operation.

[0136] The refrigerant circuits of refrigeration apparatuses 103 and 104 may each have a similar configuration to that of the refrigerant circuit of refrigeration apparatus 101 or refrigeration apparatus 102. The heat medium circuits of refrigeration apparatuses 103 and 104 may each include heat source-side heat exchanger 2 of refrigeration -3 -apparatus 101 or refrigeration apparatus 102.

[0137] A refrigeration apparatus 105 shown in Fig. 14 is a variation of refrigeration apparatus 100 shown in Figs. Ito 3. In refrigeration apparatus 105, the second flow path has only one bypass flow path, that is, only second non-common flow path L2.

From a different viewpoint, in refrigeration apparatus 105, the first flow path and the second flow path do not have second common flow path C2, the above-described second branch point, and the above-described fifth branch point. In this case, second non-common flow path L2 has one end connected with the above-described first branch point, in a manner similar to that in refrigeration apparatus 100. Second non-common flow path L2 has the other end connected downstream of first decompression unit 4 and upstream of fifth flow inlet/outlet portion 5A of use-side heat exchanger 5 in the first flow path. Second non-common flow path L2 is provided to bypass auxiliary heat exchanger 3, heat source-side heat exchanger 2, and first decompression unit 4. Sixth on-off valve 16 is not required in refrigeration apparatus 105.

[0138] Note that refrigeration apparatuses 101, 102, 103 and 104 can also each adopt a variation similar to refrigeration apparatus 105.

[0139] A refrigeration apparatus 106 shown in Figs. 15 and 16 is a variation of refrigeration apparatus 100 shown in Figs. 1 to 3. Refrigeration apparatus 106 further includes an economizer circuit through which the refrigerant circulates. The economizer circuit includes compressor 1, heat source-side heat exchanger 2, an economizer flow path 60, an economizer heat exchanger 61, an economizer decompression unit 62, a fifth bypass flow path 63, and a twelfth on-off valve 64. [0140] Compressor 1 includes, for example, a low-pressure portion, a high-pressure portion, and an intermediate-pressure portion disposed between the low-pressure portion and the high-pressure portion. Economizer flow path 60 branches off from the above-described first flow path of the refrigerant circuit. Economizer flow path 60 has one end connected between second flow inlet/outlet portion 2B of heat source-side heat exchanger 2 and the above-described second branch point. Economizer flow path 60 has the other end connected with the intermediate-pressure portion of compressor 1, -3 -for example. The economizer circuit thus causes some of the refrigerant condensed in heat source-side heat exchanger 2 to flow into the above-described intermediate-pressure portion of compressor 1. Economizer decompression unit 62 decompresses the refrigerant flowing into the economizer flow path after being condensed in heat source-side heat exchanger 2. Economizer heat exchanger 61 is provided to exchange heat between the refrigerant decompressed by economizer decompression unit 62 and the refrigerant flowing to use-side heat exchanger 5 after being condensed in heat source-side heat exchanger 2. The economizer circuit is included in a heat source-side unit 206. Compressor 1, heat source-side heat exchanger 2, economizer flow path 60, economizer heat exchanger 61, and economizer decompression unit 62 are included in a first unit 506.

[0141] Fifth bypass flow path 63 is provided to bypass first on-off valve 11, auxiliary heat exchanger 3 and second flow directing unit 18 in the first flow path. Fifth bypass flow path 63 has one end connected between the first branch point and first on-off valve 11 in first non-common flow path Li. Fifth bypass flow path 63 has the other end connected between second flow directing unit 18 and first flow inlet/outlet portion 2A of heat source-side heat exchanger 2 in first non-common flow path L]. Twelfth on-off valve 64 opens and/or closes fifth bypass flow path 63. Fifth bypass flow path 63 and twelfth on-off valve 64 are included in a second unit 606.

[0142] The economizer circuit shares a portion located between discharge port 1B of compressor] and the above-described one end of fifth bypass flow path 63, and a portion located between the above-described other end of fifth bypass flow path 63 and the above-described one end of economizer flow path 60, with the first flow path of the above-described refrigerant circuit.

[0143] From a different viewpoint, the refrigerant circuit of refrigeration apparatus 106 further includes economizer flow path 60 and fifth bypass flow path 63. When the refrigerant circuit is in the first state, the economizer circuit is formed by: first common flow path C]; a portion located between the first branch point and the above-described one end of economizer flow path 60 in first non-common flow path Li; and -3 -economizer flow path 60. When the refrigerant circuit is in the second state, the economizer circuit is formed by: first common flow path CI; a portion located between the first branch point and the above-described one end of fifth bypass flow path 63 and a portion located between the above-described other end of fifth bypass flow path 63 and the above-described one end of economizer flow path 60 in first non-common flow path Li; fifth bypass flow path 63; and economizer flow path 60. Note that the economizer circuit of refrigeration apparatus 106 should only be configured to return some of the refrigerant condensed in heat source-side heat exchanger 2 to compressor 1. The other end of economizer flow path 60 may be connected with the low-pressure portion or suction port lA of compressor 1. In addition, compressor 1 in refrigeration apparatus 106 is not particularly limited in configuration, and may be a multi-stage compressor or a single-stage compressor, for example.

[0144] As shown in Fig. 15, during the cooling operation of refrigeration apparatus 106, first on-off valve II, fourth on-off valve 14, and fifth on-off valve 15 are opened, while second on-off valve 12, third on-off valve 13, sixth on-off valve 16, and twelfth on-off valve 64 are closed. Thus, the refrigerant discharged from compressor 1 flows successively through heat source-side heat exchanger 2 acting as a first condenser, auxiliary heat exchanger 3, first decompression unit 4, and use-side heat exchanger 5 acting as a first evaporator, and the remainder of the refrigerant discharged from compressor 1 flows successively through heat source-side heat exchanger 2 and economizer flow path 60. As a result, the cooling operation of refrigeration apparatus 106 has further improved efficiency by utilizing the economizer circuit, compared to that of the above-described conventional refrigeration apparatus.

[0145] As shown in Fig. 16, during the defrosting operation of refrigeration apparatus 106, second on-off valve 12, third on-off valve 13, sixth on-off valve 16, and twelfth on-off valve 64 are opened, while first on-off valve 11, fourth on-off valve 14, and fifth on-off valve 15 are closed. Thus, during the defrosting operation of refrigeration apparatus 106, some of the refrigerant discharged from compressor 1 flows successively through use-side heat exchanger 5 acting as a second condenser, second -3 -decompression unit 6, and auxiliary heat exchanger 3 acting as a second evaporator, and the remainder of the refrigerant discharged from compressor 1 flows successively through fifth bypass flow path 63, heat source-side heat exchanger 2, and economizer flow path 60. That is, heat source-side heat exchanger 2 does not act as a condenser when the refrigerant circuits of refrigeration apparatuses 100 to 105 are in the second state, whereas heat source-side heat exchanger 2 acts as a condenser when the refrigerant circuit of refrigeration apparatus 106 is in the second state. In the defrosting operation of refrigeration apparatus 106, it is preferable that the amount of heat exchange in heat source-side heat exchanger 2 be smaller than the amount of heat exchange in auxiliary heat exchanger 3 in order to increase the amount of heat exchange used for the defrosting in use-side heat exchanger 5. It is thus preferable that the rotational speed of first fan 7 during the defrosting operation of refrigeration apparatus 106 be lower than the rotational speed of second fan 8 during the defrosting operation of refrigeration apparatus 106, and the rotational speed of first fan 7 during the cooling operation of refrigeration apparatus 106.

[0146] Although the refrigerant flows through the first flow path and economizer flow path 60 during the defrosting operation of refrigeration apparatus 106, the amount of heat exchanger in heat source-side heat exchanger 2 is sufficiently smaller, thus allowing a sufficient amount of heat to be used for the defrosting in use-side heat exchanger 5. In addition, the defrosting operation of refrigeration apparatus 100 also utilizes a refrigeration cycle, unlike a conventional refrigeration apparatus provided such that refrigerant flows through only a use-side heat exchanger and does not flow through any other heat exchangers during defrosting operation. As a result, the defrosting operation of refrigeration apparatus 106 has improved efficiency compared to that of the above-described conventional refrigeration apparatus.

[0147] As shown in Fig. 17, the economizer circuit of refrigeration apparatus 106 may include a capillary tube 65 instead of twelfth on-off valve 64. Capillary tube 65 is disposed in fifth bypass flow path 63. Pressure loss of the refrigerant in capillary tube 65 is higher than pressure loss of the refrigerant in auxiliary heat exchanger 3.

-40 -Capillary tube 65 is provided such that, when the refrigerant circuit is in the above-described first state, the flow rate of the refrigerant flowing through fifth bypass flow path 63 does not affect the cooling performance of refrigeration apparatus 106, or stated differently, such that the flow rate of the refrigerant flowing through fifth bypass flow path 63 is less than a minimum flow rate that may affect the cooling performance of refrigeration apparatus 106. In this case, capillary tube 65 substantially cuts off the flow of the refrigerant through fifth bypass flow path 63 when first on-off valve 11 is opened, and allows the refrigerant to flow through fifth bypass flow path 63 when first on-off valve 11 is closed. Thus, refrigeration apparatus 106 including capillary tube 65 can produce similar effects to those of refrigeration apparatus 106 including twelfth on-off valve 64. Note that refrigeration apparatuses 101 to 105 can also each adopt a variation similar to refrigeration apparatus 106.

[0148] A refrigeration apparatus 107 shown in Fig. 18 is a variation of refrigeration apparatus 100 shown in Figs. Ito 3. In refrigeration apparatus 107, a plurality of compressors I are connected in parallel with each other in the first flow path and the second flow path. Further, a plurality of heat source-side heat exchangers 2 are connected in parallel with each other in the first flow path. Such refrigeration apparatus 107 also basically has a similar configuration to that of refrigeration apparatus 100, and can therefore produce similar effects to those of refrigeration apparatus 100. Note that refrigeration apparatuses 101 to 106 can also each adopt a variation similar to refrigeration apparatus 107 [0149] In refrigeration apparatuses 100 to 107, decompression unit 300 may be disposed outside the first casing. Decompression unit 300 may be disposed, together with use-side unit 400, for example, in the space to be cooled Decompression unit 300 may also be configured integrally with use-side unit 400.

[0150] In refrigeration apparatuses 100 to 107, heat source-side units 200 to 207 may each include decompression unit 300. Decompression unit 300 is, for example, configured integrally with or separately from first units 500 to 507 and second units 600 to 605 in heat source-side units 200 to 207, and is disposed in the first casing.

-41 - [0151] Although the embodiments of the present invention have been described as above, a variety of variations to the embodiments described above are possible. In addition, the scope of the present invention is not limited to the embodiments described above. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims

REFERENCE SIGNS LIST

[0152] 1 compressor; IA suction port, 1B discharge port; 2 heat source-side heat exchanger; 2A first flow inlet/outlet portion; 2B second flow inlet/outlet portion; 2C seventh flow inlet/outlet portion; 2D eighth flow inlet/outlet portion; 3 auxiliary heat exchanger; 3A third flow inlet/outlet portion; 3B fourth flow inlet/outlet portion, 4 first decompression unit; 5 use-side heat exchanger; 5A fifth flow inlet/outlet portion; 5B sixth flow inlet/outlet portion; 6 second decompression unit; 7 first fan; 8 second fan; 9 third fan; 10A first flow path switching unit; 10B second flow path switching unit; 10C third flow path switching unit; 11 first on-off valve; 12 second on-off valve; 13 third on-off valve; 14 fourth on-off valve; 15 fifth on-off valve; 16 sixth on-off valve; 17 first flow directing unit; 18 second flow directing unit; 19 third flow directing unit; 20A fourth flow path switching unit; 21 seventh on-off valve; 22 eighth on-off valve; 23 fourth flow directing unit, 31 ninth on-off valve; 32 tenth on-off valve, 33 eleventh on-off valve; 34 fifth flow directing unit; 35 sixth flow directing unit; 51 high-temperature side compressor; 52 high-temperature side condenser; 53 high-temperature side decompression unit; 54 fourth fan; 55 pump; 56 heat exchanger; 60 economizer flow path, 61 economizer heat exchanger; 62 economizer decompression unit; 63 fifth bypass flow path; 64 twelfth on-off valve; 65 capillary tube; 100, 101, 102, 103, 104, 105, 106, 107 refrigeration apparatus; 200, 201, 202 heat source-side unit; 210A first pipe; 210B second pipe; 210C third pipe: 210D fourth pipe; 210E fifth pipe; 210F sixth pipe; 210H eight pipe; 2101 ninth pipe; 210J tenth pipe; 300 use-side unit; 400, 401, 402, 403 first unit; 500, 501 502, 503 second unit; 600 third unit.

-42 -

I. A refrigeration apparatus comprising a refrigerant circuit through which refrigerant circulates, the refrigerant circuit including a compressor, a heat source-side heat exchanger, a first decompression unit, a use-side heat exchanger, a second decompression unit, an auxiliary heat exchanger, and a flow path switching unit, wherein the flow path switching unit is provided to switch between a first state in which the heat source-side heat exchanger and the auxiliary heat exchanger act as a first condenser, the use-side heat exchanger acts as a first evaporator, and the refrigerant flows successively through the compressor, the first condenser, the first decompression unit, and the first evaporator, and a second state in which the use-side heat exchanger acts as a second condenser, the auxiliary heat exchanger acts as a second evaporator, and the refrigerant flows successively through the compressor, the second condenser, the second decompression unit, and the second evaporator.

2. The refrigeration apparatus according to claim 1, wherein in the first state, the auxiliary heat exchanger is disposed upstream of the heat source-side heat exchanger in the refrigerant circuit.

3. The refrigeration apparatus according to claim 2, wherein the refrigerant circuit includes a first flow path connecting a discharge port of the compressor with the use-side heat exchanger through the auxiliary heat exchanger, the heat source-side heat exchanger, and the first decompression unit, a second flow path connecting the discharge port of the compressor with the use-side heat exchanger not through the auxiliary heat exchanger, the heat source-side heat exchanger, and the first decompression unit, -3 -a third flow path connecting the use-side heat exchanger with a suction port of the compressor through the second decompression unit and the auxiliary heat exchanger, and a fourth flow path connecting the use-side heat exchanger with the suction port of the compressor not through the second decompression unit and the auxiliary heat exchanger, the flow path switching unit has a first flow path switching unit to switch between the first flow path and the second flow path, and a second flow path switching unit to switch between the third flow path and the fourth flow path, the first flow path switching unit forms the first flow path in the first state, and forms the second flow path in the second state, and the second flow path switching unit forms the fourth flow path in the first state, and forms the third flow path in the second state.

4. The refrigeration apparatus according to claim 1, wherein in the first state, the heat source-side heat exchanger is disposed upstream of the auxiliary heat exchanger in the refrigerant circuit.

The refrigeration apparatus according to claim 1, wherein in the first state, the heat source-side heat exchanger and the auxiliary heat exchanger are connected in parallel with each other.

6. The refrigeration apparatus according to any one of claims 1 to 5, further comprising a heat medium circuit through which a heat medium circulates, wherein the heat source-side heat exchanger is provided to exchange heat between the refrigerant circulating through the refrigerant circuit and the heat medium circulating through the heat medium circuit.

7. The refrigeration apparatus according to any one of claims 1 to 6, further -44 -comprising an economizer circuit through which the refrigerant circulates, wherein the economizer circuit includes the compressor and the heat source-side heat exchanger, the economizer circuit further includes an economizer flow path to return some of the refrigerant condensed in the heat source-side heat exchanger to the compressor, in the second state, the heat source-side heat exchanger and the use-side heat exchanger act as the second condenser, and the refrigeration apparatus further comprises a first fan to blow air to the heat source-side heat exchanger and a second fan to blow air to the auxiliary heat exchanger.

8. The refrigeration apparatus according to any one of claims 1 to 7, further comprising a first casing housing therein the heat source-side heat exchanger and the auxiliary heat exchanger.

9. The refrigeration apparatus according to claim 8, wherein the first casing further houses therein the compressor, the first decompression unit, and the second decompression unit, and the refrigeration apparatus further comprises a second casing housing therein the use-side heat exchanger.

10. A heat source-side unit forming part of a refrigeration apparatus, the refrigeration apparatus comprising a refrigerant circuit through which refrigerant circulates, the refrigerant circuit including a compressor, a heat source-side heat exchanger, a first decompression unit, a use-side heat exchanger, a second decompression unit, an auxiliary heat exchanger, and a flow path switching unit, the heat source-side unit comprising: part of the refrigerant circuit including the compressor, the heat source-side heat exchanger, the auxiliary heat exchanger, the second decompression unit, and the flow -45 -path switching unit; a flow outlet through which the refrigerant flows out of the part of the refrigerant circuit to another part of the refrigerant circuit; and a flow inlet through which the refrigerant flows into the part of the refrigerant circuit from the another part of the refrigerant circuit, wherein the flow path switching unit switches between a first state in which the heat source-side heat exchanger and the auxiliary heat exchanger act as a first condenser, and the refrigerant flows successively through the flow inlet, the compressor, the first condenser, and the flow outlet, and a second state in which the auxiliary heat exchanger acts as a first evaporator, and the refrigerant flows successively through the flow inlet, the second decompression unit, the first evaporator, the compressor, and the flow outlet.

-46 -

Claims

CLAIMSI. A refrigeration apparatus comprising a refrigerant circuit through which refrigerant circulates, the refrigerant circuit including a compressor, a heat source-side heat exchanger, a first decompression unit, a use-side heat exchanger, a second decompression unit, an auxiliary heat exchanger, and a flow path switching unit, wherein the flow path switching unit is provided to switch between a first state in which the heat source-side heat exchanger and the auxiliary heat exchanger act as a first condenser, the use-side heat exchanger acts as a first evaporator, and the refrigerant flows successively through the compressor, the first condenser, the first decompression unit, and the first evaporator, and a second state in which the use-side heat exchanger acts as a second condenser, the auxiliary heat exchanger acts as a second evaporator, and the refrigerant flows successively through the compressor, the second condenser, the second decompression unit, and the second evaporator, and a direction in which the refrigerant flows through the use-side heat exchanger is constant whether in the first state or in the second state.
2. The refrigeration apparatus according to claim 1, wherein in the first state, the auxiliary heat exchanger is disposed upstream of the heat source-side heat exchanger in the refrigerant circuit.
3. The refrigeration apparatus according to claim 2, wherein the refrigerant circuit includes a first flow path connecting a discharge port of the compressor with the use-side heat exchanger through the auxiliary heat exchanger, the heat source-side heat exchanger, and the first decompression unit, a second flow path connecting the discharge port of the compressor with the use-side heat exchanger not through the auxiliary heat exchanger, the heat source-side heat exchanger, and the first decompression unit, a third flow path connecting the use-side heat exchanger with a suction port of the compressor through the second decompression unit and the auxiliary heat exchanger, and a fourth flow path connecting the use-side heat exchanger with the suction port of the compressor not through the second decompression unit and the auxiliary heat exchanger, the flow path switching unit has a first flow path switching unit to switch between the first flow path and the second flow path, and a second flow path switching unit to switch between the third flow path and the fourth flow path, the first flow path switching unit forms the first flow path in the first state, and forms the second flow path in the second state, and the second flow path switching unit forms the fourth flow path in the first state, and forms the third flow path in the second state.
4. The refrigeration apparatus according to claim 1, wherein in the first state, the heat source-side heat exchanger is disposed upstream of the auxiliary heat exchanger in the refrigerant circuit
5. The refrigeration apparatus according to claim 1, wherein in the first state, the heat source-side heat exchanger and the auxiliary heat exchanger are connected in parallel with each other.
6. The refrigeration apparatus according to any one of claims Ito 5, further comprising a heat medium circuit through which a heat medium circulates, wherein the heat source-side heat exchanger is provided to exchange heat between the refrigerant circulating through the refrigerant circuit and the heat medium circulating through the heat medium circuit.
7. The refrigeration apparatus according to any one of claims 1 to 6, further comprising an economizer circuit through which the refrigerant circulates, wherein the economizer circuit includes the compressor and the heat source-side heat exchanger, the economizer circuit further includes an economizer flow path to return some of the refrigerant condensed in the heat source-side heat exchanger to the compressor, in the second state, the heat source-side heat exchanger and the use-side heat exchanger act as the second condenser, and the refrigeration apparatus further comprises a first fan to blow air to the heat source-side heat exchanger, and a second fan to blow air to the auxiliary heat exchanger.
8. The refrigeration apparatus according to any one of claims 1 to 7, further comprising a first casing housing therein the heat source-side heat exchanger and the auxiliary heat exchanger.
9. The refrigeration apparatus according to claim 8, wherein the first casing further houses therein the compressor, the first decompression unit, and the second decompression unit, and the refrigeration apparatus further comprises a second casing housing therein the use-side heat exchanger.
10. A heat source-side unit forming part of a refrigeration apparatus, the refrigeration apparatus comprising a refrigerant circuit through which refrigerant circulates, the refrigerant circuit including a compressor, a heat source-side heat exchanger, a first decompression unit, a use-side heat exchanger, a second decompression unit, an auxiliary heat exchanger, and a flow path switching unit, the heat source-side unit comprising: part of the refrigerant circuit including the compressor, the heat source-side heat exchanger, the auxiliary heat exchanger, the second decompression unit, and the flow path switching unit; a flow outlet through which the refrigerant flows out of the part of the refrigerant circuit to another part of the refrigerant circuit; and a flow inlet through which the refrigerant flows into the part of the refrigerant circuit from the another part of the refrigerant circuit, wherein the flow path switching unit switches between a first state in which the heat source-side heat exchanger and the auxiliary heat exchanger act as a first condenser, and the refrigerant flows successively through the flow inlet, the compressor, the first condenser, and the flow outlet, and a second state in which the auxiliary heat exchanger acts as a first evaporator, and the refrigerant flows successively through the flow inlet, the second decompression unit, the first evaporator, the compressor, and the flow outlet.