Heat exchanger and refrigeration cycle device

Abstract

A heat exchanger (HE) comprises a heat exchange unit (10), a distributor (20), and a merging unit (30). The heat exchange unit (10) has a first heat exchange region (10a) and a second heat exchange region (10b). The first heat exchange region (10a) has a plurality of first refrigerant paths (RP1). The second heat exchange region (10b) has a plurality of second refrigerant paths (RP2). The heat exchange unit (10) is configured such that, when the heat exchange unit (10) is functioning as an evaporator, refrigerant flows from the lowermost first refrigerant path (RP1) of the plurality of first refrigerant paths (RP1) to the lowermost second refrigerant path (RP2) of the plurality of second refrigerant paths (RP2) via the distributor (20). The heat exchange unit (10) is configured such that, when the heat exchange unit (10) is functioning as a condenser, refrigerant flows from the merging unit (30) without diverging to the lowermost second refrigerant path (RP2) of the plurality of second refrigerant paths (RP2).

Description

Heat exchanger and refrigeration cycle device

[0001] The present disclosure relates to a heat exchanger and a refrigeration cycle device.

[0002] Conventionally, heat exchangers with multiple refrigerant paths have been used. For example, Japanese Patent Application Laid-Open No. 2016-84970 (Patent Document 1) describes a heat exchanger with multiple refrigerant paths. In the heat exchanger described in this publication, during heating operation in which the heat exchanger functions as an evaporator, refrigerant flows from a row on the windward side of the heat exchanger through a first flow divider and is then diverted to a refrigerant path on the windward side of the heat exchanger. In the heat exchanger described in this publication, the refrigerant path in the lowest row on the downwind side branches into two.

[0003] JP 2016-84970 A

[0004] The heat exchanger described in the publication can suppress the deterioration of heat exchange performance by suppressing the influence of pressure loss in the distributor. However, during defrosting operation, the refrigerant flows into the refrigerant path on the downwind side, where ice is most likely to form. Therefore, the amount of refrigerant flowing through the refrigerant path on the downwind side is reduced, which reduces the melting rate of frost during dehumidification operation.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a heat exchanger and a refrigeration cycle device equipped with the same that can promote the melting of frost during dehumidification operation while suppressing a decrease in heat exchange performance.

[0006] The heat exchanger of the present disclosure includes a heat exchange unit, a distributor connected to the heat exchange unit, and a confluence connected to the heat exchange unit. The heat exchange unit has a first heat exchange area arranged upwind and a second heat exchange area arranged downwind. The first heat exchange area has a plurality of first refrigerant paths arranged in a vertical direction. The second heat exchange area has a plurality of second refrigerant paths arranged in a vertical direction. The distributor is connected to at least one of the plurality of first refrigerant paths and the plurality of second refrigerant paths. The confluence is connected to the plurality of second refrigerant paths. When the heat exchange unit functions as an evaporator, the heat exchange unit is configured so that refrigerant flows from the lowest first refrigerant path of the plurality of first refrigerant paths to the lowest second refrigerant path of the plurality of second refrigerant paths via the distributor. When the heat exchange unit functions as a condenser, the heat exchange unit is configured so that refrigerant flows from the confluence to the lowest second refrigerant path of the plurality of second refrigerant paths without branching.

[0007] According to the heat exchanger of the present disclosure, it is possible to promote melting of frost during dehumidifying operation while suppressing a decrease in heat exchange performance.

[0008] FIG. 1 is a refrigerant circuit diagram of a refrigeration cycle device according to embodiment 1. FIG. 2 is a schematic diagram of a heat exchanger according to embodiment 1 functioning as an evaporator. FIG. 3 is a schematic diagram of a heat exchanger according to embodiment 1 functioning as a condenser. FIG. 4 is a schematic diagram of a heat exchanger according to embodiment 2 functioning as an evaporator. FIG. 5 is a schematic diagram of a heat exchanger according to embodiment 2 functioning as a condenser. FIG. 6 is a schematic diagram of a heat exchanger according to embodiment 3 functioning as an evaporator. FIG. 7 is a schematic diagram of a heat exchanger according to embodiment 3 functioning as a condenser. FIG. 8 is a schematic diagram of a heat exchanger according to embodiment 4 functioning as an evaporator. FIG. 9 is a schematic diagram of a heat exchanger according to embodiment 5 functioning as an evaporator. FIG. 10 is a schematic diagram of a heat exchanger according to embodiment 5 functioning as a condenser.

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated in principle.

[0010] In the following embodiments, an air conditioner will be described as an example of a refrigeration cycle apparatus. The heat exchanger described in the claims will be applied to an outdoor heat exchanger. However, the heat exchanger described in the claims may also be applied to an indoor heat exchanger.

[0011] Embodiment 1. The overall configuration (refrigerant circuit) of an air conditioner (101) as a refrigeration cycle apparatus 100 according to Embodiment 1 will be described with reference to Fig. 1. As shown in Fig. 1, the air conditioner 101 includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3 (heat exchanger HE), an expansion valve 4, an indoor heat exchanger 5, an outdoor blower 6, and an indoor blower 7. The compressor 1, the four-way valve 2, the outdoor heat exchanger 3 (heat exchanger HE), the expansion valve 4, and the indoor heat exchanger 5 are connected by piping to form a refrigerant circuit.

[0012] The air conditioner 101 is configured to be able to selectively perform heating operation, cooling operation, and defrosting operation.

[0013] In cooling operation, the refrigerant circulates through the refrigerant circuit in the order of compressor 1, four-way valve 2, outdoor heat exchanger 3 (heat exchanger HE), expansion valve 4, and indoor heat exchanger 5. In cooling operation, the outdoor heat exchanger 3 (heat exchanger HE) functions as a condenser. In cooling operation, the indoor heat exchanger 5 functions as an evaporator. Heat exchange occurs between the refrigerant flowing through the outdoor heat exchanger 3 (heat exchanger HE) and air blown by the outdoor fan 6. Heat exchange occurs between the refrigerant flowing through the indoor heat exchanger 5 and air blown by the indoor fan 7.

[0014] In heating operation, the four-way valve 2 is switched, and the refrigerant circulates through the refrigerant circuit in the order of the compressor 1, the four-way valve 2, the indoor heat exchanger 5, the expansion valve 4, and the outdoor heat exchanger 3 (heat exchanger HE). In heating operation, the indoor heat exchanger 5 functions as a condenser. In heating operation, the outdoor heat exchanger 3 (heat exchanger HE) functions as an evaporator.

[0015] During heating operation, moisture in the condensed air may adhere to the outdoor heat exchanger 3 (heat exchanger HE) as frost. In this case, the air conditioning apparatus 101 performs a defrosting operation to remove the frost. In this embodiment, the same operation as in cooling operation is performed during defrosting operation. Specifically, during defrosting operation, high-temperature, high-pressure gas refrigerant flows from the compressor 1 through the four-way valve 2 to the outdoor heat exchanger 3 (heat exchanger HE). This melts the frost that has adhered to the outdoor heat exchanger 3 (heat exchanger HE), thereby removing the frost. During defrosting operation, the outdoor heat exchanger 3 (heat exchanger HE) functions as a condenser.

[0016] The outdoor heat exchanger 3 (heat exchanger HE) will be described with reference to Figures 2 and 3. Figure 2 shows the flow of refrigerant and air during heating operation when the outdoor heat exchanger 3 (heat exchanger HE) functions as an evaporator. Figure 3 shows the flow of refrigerant and air during cooling operation when the outdoor heat exchanger 3 (heat exchanger HE) functions as a condenser. In Figures 2 and 3, the flow of refrigerant is indicated by solid arrows, and the flow of air is indicated by hollow arrows. Note that in the subsequent figures, the flow of refrigerant is indicated by solid arrows, and the flow of air is indicated by hollow arrows.

[0017] As shown in FIGS. 2 and 3 , the outdoor heat exchanger 3 (heat exchanger HE) includes a heat exchange section 10 , a distributor 20 , and a junction section 30 .

[0018] The heat exchange unit 10 has a first heat exchange area 10a and a second heat exchange area 10b. The first heat exchange area 10a is arranged upwind in the flow of air blown by the outdoor blower 6. The first heat exchange area 10a has a plurality of first refrigerant paths RP1 arranged in the vertical direction.

[0019] The second heat exchange area 10b is arranged downwind in the flow of air blown by the outdoor blower 6. The second heat exchange area 10b has a plurality of second refrigerant paths RP2 arranged in the vertical direction. Each of the plurality of first refrigerant paths RP1 and each of the plurality of second refrigerant paths RP2 are connected to one another.

[0020] The first heat exchange area 10a and the second heat exchange area 10b each include a plurality of plate-shaped fins F and heat transfer tubes P. The plate-shaped fins F are stacked on top of each other. The heat transfer tubes P penetrate the plurality of fins F. The heat transfer tubes form a refrigerant path.

[0021] The distributor 20 is connected to the heat exchange unit 10. The distributor 20 is connected to at least one of the plurality of first refrigerant paths RP1 and the plurality of second refrigerant paths RP2. In the present embodiment, the distributor 20 is connected to the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1. The distributor 20 is connected to the lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2. The distributor 20 is connected to the highest first refrigerant path RP1 of the plurality of first refrigerant paths RP1. The distributor 20 is connected to the second to fourth first refrigerant paths RP1 from the bottom of the plurality of first refrigerant paths RP1.

[0022] The junction unit 30 is connected to the heat exchange unit 10. The junction unit 30 is connected to a plurality of second refrigerant paths RP2. The junction unit 30 is, for example, a gas header. In this embodiment, the junction unit 30 is connected to the second refrigerant path RP2 that is the lowest of the plurality of second refrigerant paths RP2. The junction unit 30 is connected to the second refrigerant path RP2 that is the highest of the plurality of second refrigerant paths RP2. The junction unit 30 is connected to the second to fourth second refrigerant paths RP2 from the bottom of the plurality of second refrigerant paths RP2.

[0023] 2, when the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured so that the refrigerant flows from the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 to the lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2 via the distributor 20. When the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured so that the refrigerant flows from the bottom into the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1.

[0024] 3, when the heat exchange unit 10 functions as a condenser, the heat exchange unit 10 is configured so that the refrigerant flows from the junction 30 to the lowest second refrigerant path RP2 among the plurality of second refrigerant paths RP2 without branching. In other words, the heat exchange unit 10 is configured so that the refrigerant flows from the junction 30 to the lowest second refrigerant path RP2 among the plurality of second refrigerant paths RP2 in a single flow path.

[0025] Next, the operation of the air conditioner 101 will be described with reference to FIG. 1 . First, the operation of the air conditioner 101 during heating operation will be described. As shown in FIG. 1 , during heating operation, a high-temperature, high-pressure gas refrigerant is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant flows to the indoor heat exchanger 5 via the four-way valve 2. In the indoor heat exchanger 5, heat exchange occurs between the high-temperature, high-pressure gas refrigerant and air supplied by the indoor blower 7, and the high-temperature, high-pressure gas refrigerant condenses into high-pressure liquid refrigerant. This heat exchange warms the indoor air. The high-pressure liquid refrigerant discharged from the indoor heat exchanger 5 is decompressed by the expansion valve 4 and becomes a two-phase refrigerant consisting of low-pressure gas refrigerant and liquid refrigerant. The two-phase refrigerant flows to the outdoor heat exchanger 3 (heat exchanger HE). In the outdoor heat exchanger 3 (heat exchanger HE), heat is exchanged between the two-phase refrigerant and air supplied by the outdoor blower 6, and the two-phase refrigerant evaporates from the liquid refrigerant to become low-pressure gas refrigerant. The low-pressure gas refrigerant flows through the four-way valve 2 to the compressor 1, where it is compressed to become high-temperature, high-pressure gas refrigerant, and is discharged from the compressor 1 again. This cycle is repeated.

[0026] Next, the flow of refrigerant in the outdoor heat exchanger 3 (heat exchanger HE) during heating operation will be described in detail. As shown in FIGS. 1 and 2 , during heating operation, refrigerant flows from the expansion valve 4 to the outdoor heat exchanger 3 (heat exchanger HE). The refrigerant flows from the lowest first refrigerant path RP1 of the multiple first refrigerant paths RP1 in the first heat exchange area 10a to the distributor 20, where it is distributed to the topmost first refrigerant path RP1, the second to fourth lowest first refrigerant paths RP1 of the multiple first refrigerant paths RP1, and the bottommost second refrigerant path RP2. The refrigerant flowing through the topmost first refrigerant path RP1 flows to the topmost second refrigerant path RP2 and then flows to the junction 30. The refrigerant flowing through each of the second to fourth first refrigerant paths RP1 from the bottom among the plurality of first refrigerant paths RP1 flows to each of the second to fourth second refrigerant paths RP2 from the bottom among the plurality of second refrigerant paths RP2, and then flows to the junction 30. The refrigerant flows from the junction 30 to the compressor 1 via the four-way valve 2.

[0027] Next, the operation of the air conditioner 101 during cooling operation will be described. As shown in FIG. 1 , during cooling operation, high-temperature, high-pressure gas refrigerant is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant flows through the four-way valve 2 to the outdoor heat exchanger 3 (heat exchanger HE). In the outdoor heat exchanger 3 (heat exchanger HE), heat exchange occurs between the high-temperature, high-pressure gas refrigerant and air supplied by the outdoor fan 6, and the high-temperature, high-pressure gas refrigerant condenses into high-pressure liquid refrigerant. The high-pressure liquid refrigerant discharged from the outdoor heat exchanger 3 (heat exchanger HE) is decompressed by the expansion valve 4 and becomes a two-phase refrigerant consisting of low-pressure gas refrigerant and liquid refrigerant. The two-phase refrigerant flows to the indoor heat exchanger 5. In the indoor heat exchanger 5, heat exchange occurs between the two-phase refrigerant and air supplied by the indoor fan 7, and the liquid refrigerant evaporates into low-pressure gas refrigerant. This heat exchange cools the indoor air. The low-pressure gas refrigerant flows through the four-way valve 2 to the compressor 1, where it is compressed into high-temperature, high-pressure gas refrigerant, which is then discharged again from the compressor 1. This cycle is repeated.

[0028] Next, the flow of refrigerant in the outdoor heat exchanger 3 (heat exchanger HE) during cooling operation will be described in detail. As shown in FIGS. 1 and 3 , during cooling operation, refrigerant flows from the compressor 1 to the outdoor heat exchanger 3 (heat exchanger HE) via the four-way valve 2. The refrigerant flows from the confluence 30 through the lowest second refrigerant path RP2 of the second heat exchange areas 10b to the distributor 20. The refrigerant also flows from the confluence 30 to the top second refrigerant path RP2 and the second to fourth second refrigerant paths RP2 from the bottom of the second heat exchange areas 10b. The refrigerant flowing through the top second refrigerant path RP2 flows to the top first refrigerant path RP1 and then to the distributor 20. The refrigerant flowing through each of the second to fourth second refrigerant paths RP2 from the bottom among the plurality of second refrigerant paths RP2 flows to each of the second to fourth first refrigerant paths RP1 from the bottom among the plurality of first refrigerant paths RP1, and then flows to the distributor 20. The refrigerant flows from the distributor 20 to the expansion valve 4.

[0029] The operation of the air conditioner 101 in defrosting operation is similar to the operation of the air conditioner 101 in cooling operation described above.

[0030] Next, the effects of the first embodiment will be described. Referring to Fig. 2, in the outdoor heat exchanger 3 (heat exchanger HE) according to the first embodiment, when the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured so that the refrigerant flows from the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 via the distributor 20 to the lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2. Therefore, since the refrigerant flows from the lowest first refrigerant path RP1 to the distributor 20, the influence of pressure loss in the distributor 20 can be suppressed, thereby suppressing a decrease in heat exchange performance, compared to when the refrigerant flows directly to the distributor 20. Referring to Fig. 3, when the heat exchange unit 10 functions as a condenser, the heat exchange unit 10 is configured so that the refrigerant flows from the confluence 30 to the lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2 without branching. Therefore, the amount of refrigerant flowing through the second refrigerant path RP2 at the lowest stage is greater than when the second refrigerant path RP2 at the lowest stage is branched, which can promote melting of frost during defrosting operation. Therefore, it is possible to promote melting of frost during dehumidifying operation while suppressing a decrease in heat exchange performance.

[0031] Due to the influence of pressure loss in the heat transfer tube P and the distributor 20, the refrigerant temperature at Point A is higher than at Point B, and the temperature difference between the refrigerant and the air is larger at Point B than at Point A. Because the air temperature decreases from upwind to downwind during the heat exchange process, the refrigerant temperature must be lower downwind than upwind to ensure effective heat exchange. The refrigerant path including Point A functions to prevent water generated during defrosting from freezing in the lowest stage under frosting conditions, so the refrigerant temperature in the lowest stage is set to 0°C or higher. Therefore, under frosting conditions, the moisture contained in the air is not sufficiently dehumidified in the refrigerant path including Point A, which may increase the amount of frost formation in the downwind refrigerant path connected to Point B. This increases the effectiveness of accelerating frost melting during defrosting operation.

[0032] Furthermore, during defrosting operation, gas refrigerant discharged from the compressor 1 flows into the second refrigerant path RP2 at the lowest stage. Therefore, the refrigerant temperature at point C is higher than that at point D. This makes it possible to more reliably melt the frost in the second refrigerant path RP2 at the lowest stage.

[0033] According to the outdoor heat exchanger 3 (heat exchanger HE) of Embodiment 1, when the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured so that the refrigerant flows into the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 from the bottom. This prevents a decrease in the temperature of the refrigerant flowing through the bottommost path due to pressure loss. This prevents freezing in the bottommost portion, where freezing is most likely to occur.

[0034] The air conditioning apparatus 101, which is an example of the refrigeration cycle apparatus 100 according to the first embodiment, includes the outdoor heat exchanger 3 (heat exchanger HE), which can promote melting of frost during defrosting operation while suppressing deterioration of heat exchange performance.

[0035] Embodiment 2 Unless otherwise specified, the outdoor heat exchanger 3 (heat exchanger HE) according to Embodiment 2 has the same configuration, operation, and effects as the outdoor heat exchanger 3 (heat exchanger HE) according to Embodiment 1.

[0036] An outdoor heat exchanger 3 (heat exchanger HE) according to the second embodiment will be described with reference to Figures 4 and 5. As shown in Figures 4 and 5, in the outdoor heat exchanger 3 (heat exchanger HE), the distributor 20 is connected only to the first refrigerant paths RP1 of the first heat exchange area 10a. All of the pipes connecting the distributor 20 and the first heat exchange area 10a are connected to the first refrigerant paths RP1.

[0037] In this embodiment, the second-lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 is connected to the lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2. The plurality of second refrigerant paths RP2 includes four second refrigerant paths RP2. The junction 30 is connected to the lowest, uppermost, and second and third-lowest second refrigerant paths RP2 of the plurality of second refrigerant paths RP2.

[0038] Next, the flow of refrigerant in the outdoor heat exchanger 3 (heat exchanger HE) according to the second embodiment will be described in detail.

[0039] 4, during heating operation, the refrigerant flows from the lowest first refrigerant path RP1 of the multiple first refrigerant paths RP1 in the first heat exchange area 10a to the distributor 20, where it is distributed to the topmost first refrigerant path RP1 and the second to fourth lowest first refrigerant paths RP1 of the multiple first refrigerant paths RP1. The refrigerant flowing through the topmost first refrigerant path RP1 flows to the topmost second refrigerant path RP2 and then flows to the junction 30. The refrigerant flowing through the second lowest first refrigerant path RP1 of the multiple first refrigerant paths RP1 flows to the bottommost second refrigerant path RP2 of the multiple second refrigerant paths RP2 and then flows to the junction 30. The refrigerant flowing through each of the third and fourth first refrigerant paths RP1 from the bottom among the plurality of first refrigerant paths RP1 flows into each of the second and third second refrigerant paths RP2 from the bottom among the plurality of second refrigerant paths RP2, and then flows into the confluence section 30.

[0040] 5, during cooling operation, the refrigerant flows from the junction 30 to the lowest second refrigerant path RP2 of the second heat exchange area 10b, the highest second refrigerant path RP2, and the second and third lowest second refrigerant paths RP2 of the second heat exchange area 10b. The refrigerant flowing through the lowest second refrigerant path RP2 flows to the second lowest first refrigerant path RP1 of the first refrigerant paths RP1 and then flows to the distributor 20. The refrigerant flowing through the highest second refrigerant path RP1 and then flows to the distributor 20. The refrigerant flowing through each of the second and third lowest second refrigerant paths RP2 of the second heat exchange area 10b flows to the third and fourth lowest first refrigerant paths RP1 of the first refrigerant paths RP1 and then flows to the distributor 20.

[0041] The flow of the refrigerant during the defrosting operation is the same as the flow of the refrigerant during the cooling operation. Next, the effects of the second embodiment will be described.

[0042] In the outdoor heat exchanger 3 (heat exchanger HE) according to the second embodiment, the distributor 20 is connected only to the first refrigerant paths RP1 of the first heat exchange area 10a. This makes it easier to assemble the distributor 20 to the heat exchange unit 10 than when the distributor 20 is connected to the second refrigerant paths RP2 of the second heat exchange area 10b. This makes it easier to manufacture the outdoor heat exchanger 3 (heat exchanger HE).

[0043] Embodiment 3 Unless otherwise specified, the outdoor heat exchanger 3 (heat exchanger HE) according to Embodiment 3 has the same configuration, operation, and effects as the outdoor heat exchanger 3 (heat exchanger HE) according to Embodiment 2.

[0044] An outdoor heat exchanger 3 (heat exchanger HE) according to embodiment 3 will be described with reference to Figures 6 and 7. As shown in Figures 6 and 7, in the outdoor heat exchanger 3 (heat exchanger HE), the heat exchange unit 10 has a third heat exchange area 10c. The third heat exchange area 10c is disposed between the first heat exchange area 10a and the second heat exchange area 10b and adjacent to the first heat exchange area 10a. The third heat exchange area 10c is disposed downwind of the first heat exchange area 10a and upwind of the second heat exchange area 10b.

[0045] The third heat exchange area 10c has a plurality of third refrigerant paths RP3 arranged in the vertical direction. When the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured so that the refrigerant flows from the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 to the lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3, and then flows via the distributor 20 to the lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2.

[0046] Next, the flow of refrigerant in the outdoor heat exchanger 3 (heat exchanger HE) according to the third embodiment will be described in detail.

[0047] 6, during heating operation, the refrigerant flows from the lowest first refrigerant path RP1 of the multiple first refrigerant paths RP1 in the first heat exchange area 10a through the lowest third refrigerant path RP3 of the multiple third refrigerant paths RP3 in the third heat exchange area 10c to the distributor 20, where it is distributed to the topmost first refrigerant path RP1 and the second to fourth lowest first refrigerant paths RP1 of the multiple first refrigerant paths RP1. The refrigerant flowing through the topmost first refrigerant path RP1 flows through the topmost third refrigerant path RP3 to the topmost second refrigerant path RP2 and then flows to the junction 30. The refrigerant flowing through the second-lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 passes through the second-lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3, flows into the lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2, and flows to the junction 30. The refrigerant flowing through the third-lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 passes through the third-lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3, flows into the second-lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2, and flows to the junction 30. The refrigerant flowing through the fourth-lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 passes through the fourth-lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3, flows into the third-lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2, and flows to the junction 30.

[0048] 7, during cooling operation, the refrigerant flows from the confluence 30 to the lowest second refrigerant path RP2 of the second heat exchange area 10b, the highest second refrigerant path RP2, and the second and third lowest second refrigerant paths RP2 of the second heat exchange area 10b. The refrigerant flowing through the lowest second refrigerant path RP2 passes through the second lowest third refrigerant path RP3 of the third refrigerant paths RP3, flows into the second lowest first refrigerant path RP1 of the first refrigerant paths RP1, and then flows into the distributor 20. The refrigerant flowing through the highest second refrigerant path RP2 passes through the highest third refrigerant path RP3, flows into the topmost first refrigerant path RP1, and then flows into the distributor 20. The refrigerant flowing through the second-lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2 passes through the third-lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3, flows into the third-lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1, and then flows into the distributor 20. The refrigerant flowing through the third-lowest second refrigerant path RP2 of the plurality of second refrigerant paths RP2 passes through the fourth-lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3, flows into the fourth-lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1, and then flows into the distributor 20. The refrigerant flows from the distributor 20 through the lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3, and then through the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1, to the outside of the outdoor heat exchanger (heat exchanger HE).

[0049] The flow of the refrigerant during the defrosting operation is the same as the flow of the refrigerant during the cooling operation. Next, the effects of the third embodiment will be described.

[0050] According to the outdoor heat exchanger 3 (heat exchanger HE) of the third embodiment, when the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured so that the refrigerant flows from the lowest first refrigerant path RP1 among the plurality of first refrigerant paths RP1 to the lowest third refrigerant path RP3 among the plurality of third refrigerant paths RP3, and then flows via the distributor 20 to the lowest second refrigerant path RP2 among the plurality of second refrigerant paths RP2. Therefore, when the heat exchange unit 10 functions as an evaporator, the refrigerant flows through the first refrigerant path RP1 of the first heat exchange area 10a and the third refrigerant path RP3 of the third heat exchange area 10c before flowing into the distributor 20. This allows for an increase in the number of heat exchange areas through which the refrigerant flows, the temperature of which is higher than after flowing into the distributor 20. Therefore, even when the number of heat exchange areas is increased, freezing of the lowest refrigerant path during frost formation can be more effectively suppressed.

[0051] Embodiment 4 Unless otherwise specified, the outdoor heat exchanger 3 (heat exchanger HE) according to Embodiment 4 has the same configuration, operation, and effects as the outdoor heat exchanger 3 (heat exchanger HE) according to Embodiment 3.

[0052] An outdoor heat exchanger 3 (heat exchanger HE) according to the fourth embodiment will be described with reference to Figures 8 and 9. As shown in Figures 8 and 9, the outdoor heat exchanger 3 (heat exchanger HE) further includes a primary distributor 40. When the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured such that one of the refrigerants distributed by the primary distributor 40 flows from the lowest first refrigerant path RP1 among the plurality of first refrigerant paths RP1 to the distributor 20, and the other of the refrigerant distributed by the primary distributor 40 flows from the lowest third refrigerant path RP3 among the plurality of third refrigerant paths RP3 to the distributor 20.

[0053] Next, the flow of refrigerant in the outdoor heat exchanger 3 (heat exchanger HE) according to the fourth embodiment will be described in detail.

[0054] 8, during heating operation, the refrigerant is distributed by the primary distributor 40, and one of the refrigerants distributed by the primary distributor 40 flows from the lowest first refrigerant path RP1 of the multiple first refrigerant paths RP1 in the first heat exchange area 10a to the distributor 20. The other of the refrigerant distributed by the primary distributor 40 flows from the lowest third refrigerant path RP3 of the multiple third refrigerant paths RP3 in the third heat exchange area 10c to the distributor 20. The refrigerant distributed by the distributor 20 flows to the uppermost first refrigerant path RP1 and the second to fourth first refrigerant paths RP1 from the bottom of the multiple first refrigerant paths RP1.

[0055] As shown in FIG. 9 , during cooling operation, the refrigerant flows from the confluence 30 to the lowest second refrigerant path RP2, the highest second refrigerant path RP2, and the second and third lowest second refrigerant paths RP2 of the second heat exchange area 10b, and then flows through a third refrigerant path RP3 to the first refrigerant path RP1 and then to the distributor 20. One of the refrigerants distributed by the distributor 20 flows through the lowest first refrigerant path RP1 of the multiple first refrigerant paths RP1 to the primary distributor 40 and then flows from the primary distributor 40 to the outside of the outdoor heat exchanger (heat exchanger HE). The other of the refrigerant distributed by the distributor 20 flows through the lowest third refrigerant path RP3 of the multiple third refrigerant paths RP3 to the primary distributor 40 and then flows from the primary distributor 40 to the outside of the outdoor heat exchanger (heat exchanger HE).

[0056] The flow of the refrigerant during the defrosting operation is the same as the flow of the refrigerant during the cooling operation. Next, the effects of the fourth embodiment will be described.

[0057] In the outdoor heat exchanger 3 (heat exchanger HE) according to the fourth embodiment, when the heat exchange unit 10 functions as an evaporator, the heat exchange unit 10 is configured such that one of the refrigerants distributed by the primary distributor 40 flows from the lowest first refrigerant path RP1 of the plurality of first refrigerant paths RP1 to the distributor 20, and the other of the refrigerant distributed by the primary distributor 40 flows from the lowest third refrigerant path RP3 of the plurality of third refrigerant paths RP3 to the distributor 20. In the refrigerant path through which the refrigerant flows before flowing into the distributor 20, pressure loss occurs as the refrigerant passes through the heat transfer tubes P, and the saturation temperature of the refrigerant gradually decreases from upstream to downstream of the refrigerant flow. The pressure loss increases as the refrigerant flow velocity increases and the heat transfer tubes P through which the refrigerant passes are longer. In the outdoor heat exchanger 3 (heat exchanger HE) according to the fourth embodiment, the primary distributor 40 is provided further upstream of the refrigerant path through which the refrigerant flows before flowing into the distributor 20, thereby reducing pressure loss. Therefore, by suppressing the decrease in the saturation temperature of the refrigerant, it is possible to more effectively suppress freezing of the lowest refrigerant path when frost forms.

[0058] Fifth Embodiment Unless otherwise specified, the outdoor heat exchanger 3 (heat exchanger HE) according to the fifth embodiment has the same configuration, operation, and effects as the outdoor heat exchanger 3 (heat exchanger HE) according to the fourth embodiment.

[0059] An outdoor heat exchanger 3 (heat exchanger HE) according to embodiment 5 will be described with reference to Figures 10 and 11 . As shown in Figures 10 and 11 , the outdoor heat exchanger 3 (heat exchanger HE) further includes a plurality of capillary tubes 50. The plurality of capillary tubes 50 are connected to a plurality of first refrigerant paths RP1 and a distributor 20. Of the plurality of capillary tubes 50, the capillary tube 50 connected to the first refrigerant path RP1 that is connected to the lowest second refrigerant path RP2 among the plurality of second refrigerant paths RP2 is the shortest among the plurality of capillary tubes 50.

[0060] As shown in FIG. 10, during heating operation, the refrigerant distributed by the distributor 20 passes through the multiple capillary tubes 50 and flows into the topmost first refrigerant path RP1 and the second to fourth first refrigerant paths RP1 from the bottom among the multiple first refrigerant paths RP1.

[0061] As shown in Figure 11, during cooling operation, refrigerant flows from the topmost first refrigerant path RP1 and the second to fourth first refrigerant paths RP1 from the bottom among the multiple first refrigerant paths RP1, through multiple capillary tubes 50, and into the distributor 20.

[0062] Next, the effects of the fifth embodiment will be described. In the outdoor heat exchanger 3 (heat exchanger HE) according to the fifth embodiment, the capillary tube 50 connected to the first refrigerant path RP1 connected to the lowest second refrigerant path RP2 among the plurality of second refrigerant paths RP2 is the shortest among the plurality of capillary tubes 50. The pressure losses of the refrigerant paths are made approximately the same by the plurality of capillary tubes 50, thereby making the refrigerant flow rates of the refrigerant paths approximately the same. This improves heat exchange efficiency. The lowest second refrigerant path RP2 among the plurality of second refrigerant paths RP2 is longer than the other second refrigerant paths RP2 and therefore experiences a greater pressure loss. Therefore, the capillary tube 50 connected to the first refrigerant path RP1 connected to the lowest second refrigerant path RP2 can be made the shortest among the plurality of capillary tubes 50. This reduces the amount of capillary tubes 50 used. As a result, the cost of the capillary tubes 50 can be reduced.

[0063] The above-described embodiments can be combined as appropriate. The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0064] 1 Compressor, 2 Four-way valve, 3 Outdoor heat exchanger, 4 Expansion valve, 5 Indoor heat exchanger, 6 Outdoor blower, 7 Indoor blower, 10 Heat exchange section, 10a First heat exchange area, 10b Second heat exchange area, 10c Third heat exchange area, 20 Distributor, 30 Confluence section, 40 Primary distributor, 50 Capillary tube, 100 Refrigeration cycle device, 101 Air conditioning device, HE Heat exchanger, RP1 First refrigerant path, RP2 Second refrigerant path, RP3 Third refrigerant path.

Claims

1. A heat exchanger comprising: a heat exchange unit; a distributor connected to the heat exchange unit; and a confluence connected to the heat exchange unit, wherein the heat exchange unit has a first heat exchange area arranged upwind and a second heat exchange area arranged downwind, the first heat exchange area has a plurality of first refrigerant paths arranged in a vertical direction, the second heat exchange area has a plurality of second refrigerant paths arranged in the vertical direction, the distributor is connected to at least one of the plurality of first refrigerant paths and the plurality of second refrigerant paths, and the confluence is connected to the plurality of second refrigerant paths, wherein when the heat exchange unit functions as an evaporator, the heat exchange unit is configured so that refrigerant flows from the lowest first refrigerant path of the plurality of first refrigerant paths to the lowest second refrigerant path of the plurality of second refrigerant paths via the distributor, and when the heat exchange unit functions as a condenser, the heat exchange unit is configured so that the refrigerant flows from the confluence to the lowest second refrigerant path of the plurality of second refrigerant paths without branching.

2. A heat exchanger as described in claim 1, wherein when the heat exchange unit functions as an evaporator, the heat exchange unit is configured so that the refrigerant flows into the lowest first refrigerant path among the plurality of first refrigerant paths from the bottom.

3. A heat exchanger according to claim 1 or 2, wherein the distributor is connected only to the plurality of first refrigerant paths of the first heat exchange area.

4. A heat exchanger according to any one of claims 1 to 3, wherein the heat exchange unit is arranged between the first heat exchange area and the second heat exchange area and has a third heat exchange area adjacent to the first heat exchange area, the third heat exchange area has a plurality of third refrigerant paths arranged in the vertical direction, and when the heat exchange unit functions as an evaporator, the heat exchange unit is configured so that refrigerant flows from the lowest first refrigerant path of the plurality of first refrigerant paths to the lowest third refrigerant path of the plurality of third refrigerant paths, and then flows via the distributor to the lowest second refrigerant path of the plurality of second refrigerant paths.

5. A heat exchanger according to any one of claims 1 to 3, further comprising a primary distributor, wherein the heat exchange unit is arranged between the first heat exchange area and the second heat exchange area and has a third heat exchange area adjacent to the first heat exchange area, and the third heat exchange area has a plurality of third refrigerant paths arranged in the vertical direction, and when the heat exchange unit functions as an evaporator, the heat exchange unit is configured so that one of the refrigerants distributed by the primary distributor flows from the lowest first refrigerant path of the plurality of first refrigerant paths to the distributor, and the other of the refrigerants distributed by the primary distributor flows from the lowest third refrigerant path of the plurality of third refrigerant paths to the distributor.

6. A heat exchanger as described in claim 5, further comprising a plurality of capillary tubes connected to the plurality of first refrigerant paths and the distributor, and the capillary tube connected to the first refrigerant path connected to the second refrigerant path at the lowest stage among the plurality of second refrigerant paths is the shortest of the plurality of capillary tubes.

7. A refrigeration cycle device comprising the heat exchanger according to any one of claims 1 to 6.

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