Heat exchanger and refrigeration cycle device

Abstract

A heat exchanger according to the present disclosure comprises a plurality of refrigerant path parts, a first refrigerant header, and a second refrigerant header. The plurality of refrigerant path parts include a first refrigerant path part, a second refrigerant path part located below the first refrigerant path part, and a third refrigerant path part located below the second refrigerant path part. The first refrigerant header has: a first orifice plate located in the interior of a main header part and having a first orifice hole formed therein; and a second orifice plate located in the interior of the main header part and having a second orifice hole formed therein. The interior space of the main header part is partitioned into a first space, a second space, and a third space. The first space and the second space are joined to each other through the first orifice hole, and the second space and the third space are joined to each other through the second orifice hole. Refrigerant piping is connected to the first space, the first refrigerant path part and / or the third refrigerant path part are connected to the second space, and the second refrigerant path part is connected to the third space.

Description

Heat exchanger and refrigeration cycle device

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

[0002] 2. Description of the Related Art A heat exchanger is known that has a structure in which a distributor (refrigerant header) is used to branch a refrigerant to flow among a plurality of heat transfer tubes (see, for example, Patent Document 1).

[0003] International Publication No. 2022 / 215165

[0004] In the heat exchanger described above, airflow generated by a blower passes through the heat exchanger, resulting in heat exchange between the refrigerant flowing through the heat transfer tubes and the air. In this case, due to the relative positioning of the blower and the heat exchanger, the amount of air passing through the vertical center of the heat exchanger tends to be greater than the amount of air passing through the upper and lower sections of the heat exchanger. Therefore, when the heat exchanger functions as an evaporator in a refrigeration cycle system, the refrigerant in a gas-liquid two-phase state flowing through the heat transfer tubes in the center of the heat exchanger tends to gasify more quickly than the refrigerant flowing through the heat transfer tubes in the upper and lower sections of the heat exchanger. This reduces the heat exchange efficiency in the center of the heat exchanger, thereby reducing the overall heat exchange efficiency of the heat exchanger.

[0005] In view of the above circumstances, one of the objects of the present disclosure is to provide a heat exchanger having a structure that can suppress a decrease in heat exchange efficiency, and a refrigeration cycle device including such a heat exchanger.

[0006] One aspect of a heat exchanger according to the present disclosure is a heat exchanger for a refrigeration cycle device, comprising: a plurality of refrigerant path sections each having at least one heat transfer tube and separated from one another; a first refrigerant header; and a second refrigerant header connected to the first refrigerant header via the plurality of refrigerant path sections, wherein the plurality of refrigerant path sections include a first refrigerant path section, a second refrigerant path section positioned vertically below the first refrigerant path section, and a third refrigerant path section positioned vertically below the second refrigerant path section, and the first refrigerant header comprises a cylindrical header main body section, a first orifice plate positioned inside the header main body and having a first orifice hole formed therein, and a second refrigerant header positioned inside the header main body, and a second orifice plate having a second orifice hole formed therein, wherein the internal space of the header main body is partitioned by the first orifice plate and the second orifice plate into a first space, a second space, and a third space, the first space and the second space being connected to each other via the first orifice hole, the second space and the third space being connected to each other via the second orifice hole, a refrigerant pipe through which refrigerant flows into or out of the header main body is connected to the first space, at least one of the first refrigerant path portion and the third refrigerant path portion is connected to the second space, and the second refrigerant path portion is connected to the third space.

[0007] One aspect of a refrigeration cycle apparatus according to the present disclosure includes the above-described heat exchanger and a blower that generates an airflow that passes through the heat exchanger.

[0008] According to the present disclosure, it is possible to suppress a decrease in the heat exchange efficiency of a heat exchanger of a refrigeration cycle device.

[0009] Fig. 4 is a schematic diagram showing a general configuration of a refrigeration cycle device in embodiment 1. Fig. 5 is a partial cross-sectional view showing a part of a heat exchanger in embodiment 1. Fig. 6 is a cross-sectional view showing a first refrigerant header in embodiment 1. Fig. 7 is a cross-sectional view showing a first refrigerant header in embodiment 1, taken along IV-IV in Fig. 3. Fig. 8 is a diagram showing a schematic view of a refrigerant flow during heating operation in embodiment 1. Fig. 9 is a diagram showing a schematic view of a refrigerant flow during defrosting operation in embodiment 1. Fig. 10 is a partial cross-sectional view showing a part of a heat exchanger in embodiment 2.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the scope of the present disclosure is not limited to the following embodiments and can be modified as desired within the scope of the technical concept of the present disclosure. In addition, in the following drawings, the scale and number of each structure may differ from the scale and number of the actual structure in order to make each configuration easier to understand.

[0011] The drawings also show the X-axis, Y-axis, and Z-axis as appropriate. The X-axis indicates one of the horizontal directions. The Y-axis indicates the other of the horizontal directions. The Z-axis indicates the vertical direction. In the following description, the horizontal direction along the X-axis is referred to as the "front-rear direction X," the horizontal direction along the Y-axis is referred to as the "left-right direction Y," and the vertical direction along the Z-axis is referred to as the "vertical direction Z." The front-rear direction X, left-right direction Y, and vertical direction Z are perpendicular to one another. The side of the vertical direction Z toward which the Z-axis arrow points (+Z side) is the upper side, and the side of the vertical direction Z opposite to the side toward which the Z-axis arrow points (-Z side) is the lower side. In the following description, the side of the front-rear direction X toward which the X-axis arrow points (+X side) is referred to as the "front side," and the side of the front-rear direction X opposite to the side toward which the X-axis arrow points (-X side) is referred to as the "rear side." The side of the left-right direction Y toward which the Y-axis arrow points (+Y side) is defined as the "right side," and the side opposite to the side toward which the Y-axis arrow points (-Y side) is defined as the "left side."

[0012] Embodiment 1. Fig. 1 is a schematic diagram showing a general configuration of a refrigeration cycle apparatus 100 in embodiment 1. The refrigeration cycle apparatus 100 in embodiment 1 is an air conditioner. As shown in Fig. 1, the refrigeration cycle apparatus 100 includes an outdoor unit 10, an indoor unit 20, and a circulation path section 18 connecting the outdoor unit 10 and the indoor unit 20. The outdoor unit 10 is disposed outdoors. The indoor unit 20 is disposed indoors. The outdoor unit 10 and the indoor unit 20 are connected to each other by the circulation path section 18 through which a refrigerant 19 circulates. The outdoor unit 10 and the indoor unit 20 are heat exchange units that exchange heat with air.

[0013] The refrigeration cycle apparatus 100 can adjust the temperature of indoor air by exchanging heat between the refrigerant 19 flowing through the circulation path 18 and the air in a room where the indoor unit 20 is located. Examples of the refrigerant 19 include fluorine-based refrigerants or hydrocarbon-based refrigerants with low global warming potential (GWP). Examples of the refrigerant 19 include a single refrigerant selected from R1234yf, R1234ze, R32, and R290, a mixture of two or more of these refrigerants, or a mixture of any of these refrigerants with another refrigerant. Examples of the refrigerant 19 include a mixture of R1132(E) and R1123. Examples of refrigerant 19 include a mixed refrigerant of R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, and R459A. The density of refrigerant 19 in gaseous form is greater than the density of air.

[0014] The outdoor unit 10 has a housing 11, a compressor 12, a heat exchanger 30, a throttling device 14, a blower 15, a four-way valve 16, and a control unit 17. The housing 11 houses the compressor 12, the heat exchanger 30, the throttling device 14, the blower 15, the four-way valve 16, and the control unit 17. The blower 15 generates an airflow that passes through the heat exchanger 30.

[0015] The compressor 12, the heat exchanger 30, the expansion device 14, and the four-way valve 16 are provided in a portion of the circulation path 18 that is located inside the housing 11. The compressor 12, the heat exchanger 30, the expansion device 14, and the four-way valve 16 are connected by a portion of the circulation path 18 that is located inside the housing 11.

[0016] The four-way valve 16 is provided in a portion of the circulation path section 18 that is connected to the discharge side of the compressor 12. The four-way valve 16 can reverse the direction of the refrigerant 19 flowing through the circulation path section 18 by switching a portion of the path of the circulation path section 18. When the path connected by the four-way valve 16 is the path shown by the solid line on the four-way valve 16 in Fig. 1, the refrigerant 19 flows through the circulation path section 18 in the direction shown by the solid arrow in Fig. 1. On the other hand, when the path connected by the four-way valve 16 is the path shown by the dashed line on the four-way valve 16 in Fig. 1, the refrigerant 19 flows through the circulation path section 18 in the direction shown by the dashed arrow in Fig. 1.

[0017] The indoor unit 20 includes a housing 21, a heat exchanger 22, and a blower 23. The housing 21 houses the heat exchanger 22 and the blower 23 inside. The blower 23 generates an airflow that passes through the heat exchanger 22. The indoor unit 20 is capable of cooling operation to cool the air in the room where the indoor unit 20 is located, and heating operation to warm the air in the room where the indoor unit 20 is located.

[0018] When the indoor unit 20 is in cooling operation, the refrigerant 19 flowing in the circulation path portion 18 flows in the direction shown by the solid arrow in Fig. 1. In other words, when the indoor unit 20 is in cooling operation, the refrigerant 19 flowing in the circulation path portion 18 circulates through the compressor 12, the heat exchanger 30 of the outdoor unit 10, the expansion device 14, and the heat exchanger 22 of the indoor unit 20 in that order, before returning to the compressor 12. During cooling operation, the heat exchanger 30 of the outdoor unit 10 functions as a condenser, and the heat exchanger 22 of the indoor unit 20 functions as an evaporator.

[0019] On the other hand, when the indoor unit 20 is in heating operation, the refrigerant 19 flowing in the circulation path portion 18 flows in the direction shown by the dashed line in Fig. 1. In other words, when the indoor unit 20 is in heating operation, the refrigerant 19 flowing in the circulation path portion 18 circulates through the compressor 12, the heat exchanger 22 of the indoor unit 20, the expansion device 14, and the heat exchanger 30 of the outdoor unit 10 in that order, before returning to the compressor 12. In heating operation, the heat exchanger 30 of the outdoor unit 10 functions as an evaporator, and the heat exchanger 22 of the indoor unit 20 functions as a condenser.

[0020] The state change of the refrigerant 19 flowing through the circulation path 18 during heating operation will be described in more detail. During heating operation, low-temperature, low-pressure gaseous refrigerant 19 is drawn into the compressor 12 and becomes high-temperature, high-pressure gaseous refrigerant 19. The high-temperature, high-pressure gaseous refrigerant 19 is discharged from the compressor 12, passes through the four-way valve 16, and flows into the heat exchanger 22 of the indoor unit 20. The high-temperature, high-pressure gaseous refrigerant 19 that flows into the heat exchanger 22 exchanges heat with air supplied from the blower 23 of the indoor unit 20, releasing heat and condensing, becoming high-temperature, high-pressure liquid refrigerant 19 that flows out of the heat exchanger 22. Thus, during heating operation, the heat exchanger 22 of the indoor unit 20 functions as a condenser. The liquid refrigerant 19 that flows out of the heat exchanger 22 is expanded and decompressed by the expansion device 14, becoming low-temperature, low-pressure, two-phase gas-liquid refrigerant 19, which flows into the heat exchanger 30 of the outdoor unit 10. The refrigerant 19 in a gas-liquid two-phase state that flows into the heat exchanger 30 absorbs heat and evaporates by exchanging heat with outdoor air supplied by the blower 15 of the outdoor unit 10, becoming low-temperature, low-pressure gaseous refrigerant 19 that flows out of the heat exchanger 30. In this way, the heat exchanger 30 of the outdoor unit 10 functions as an evaporator during heating operation. The low-temperature, low-pressure gaseous refrigerant 19 that flows out of the heat exchanger 30 is drawn back into the compressor 12, compressed again, and discharged. During heating operation, the above-described circulation of the refrigerant 19 is repeated.

[0021] The change in the state of the refrigerant 19 during cooling operation is similar to the change in the state of the refrigerant 19 during heating operation, except that the heat exchanger 30 of the outdoor unit 10 functions as a condenser and the heat exchanger 22 of the indoor unit 20 functions as an evaporator.

[0022] The refrigeration cycle apparatus 100 is capable of performing a defrosting operation to remove frost formed on the heat exchanger 30 of the outdoor unit 10. During the heating operation described above, the refrigerant 19 flowing through the heat exchanger 30 of the outdoor unit 10, which functions as an evaporator, removes heat from the air passing through the heat exchanger 30. As a result, the temperature of the heat exchanger 30 drops during heating operation, and frost may form on the surface of the heat exchanger 30. When frost accumulates on the surface of the heat exchanger 30, it becomes difficult for air to pass through the heat exchanger 30. This reduces the heat exchange efficiency of the heat exchanger 30, which may reduce the heating capacity during heating operation. Therefore, if frost forms on the heat exchanger 30, it is necessary to periodically perform a defrosting operation, which is the reverse cycle of the heating operation, to remove the frost formed on the heat exchanger 30.

[0023] During defrosting operation, the direction in which the refrigerant 19 flows in the circulation path portion 18 is the same as the direction in which the refrigerant 19 flows in the circulation path portion 18 during cooling operation. That is, during defrosting operation, the refrigerant 19 flows in the direction indicated by the solid arrow in FIG. 1 . During defrosting operation, as in cooling operation, the heat exchanger 30 in the outdoor unit 10 functions as a condenser, and the heat exchanger 22 in the indoor unit 20 functions as an evaporator. When the refrigerant 19 flows as in defrosting operation and cooling operation, the refrigerant 19 at a relatively high temperature flows into the heat exchanger 30. Therefore, by performing the defrosting operation, the heat of the refrigerant 19 can melt and remove frost formed on the surface of the heat exchanger 30.

[0024] Next, the heat exchanger 30 of the outdoor unit 10 will be described in more detail. Fig. 2 is a partial cross-sectional view showing a part of the heat exchanger 30. As shown in Fig. 2, the heat exchanger 30 includes a heat exchanger body 30a, a first refrigerant header 60, and a second refrigerant header 70.

[0025] The heat exchanger body 30a is a portion where heat exchange occurs between the refrigerant 19 and the air. The heat exchanger body 30a has a first heat exchange section 31 and a second heat exchange section 32. The first heat exchange section 31 is a main heat exchange area. The first heat exchange section 31 has a plurality of refrigerant path sections 40 separated from each other and a plurality of heat transfer fins 31a provided in each refrigerant path section 40. Each of the plurality of refrigerant path sections 40 has at least one heat transfer tube 40a. The refrigerant 19 flows through the heat transfer tubes 40a of each refrigerant path section 40. The heat transfer tubes 40a are, for example, flat tubes whose dimension in the vertical direction Z is smaller than their dimension in the front-rear direction X. The upper and lower surfaces of the heat transfer tubes 40a are flat surfaces perpendicular to the vertical direction Z. A plurality of heat transfer fins 31a spaced apart in the left-right direction Y are connected to each heat transfer tube 40a. The plurality of refrigerant path portions 40 include a first refrigerant path portion 41 , a second refrigerant path portion 42 , and a third refrigerant path portion 43 .

[0026] The first refrigerant path section 41 is the uppermost refrigerant path section 40 among the multiple refrigerant path sections 40. The first refrigerant path section 41 includes multiple heat transfer tubes 41a and a third refrigerant header 71. The multiple heat transfer tubes 41a connect the interior of the second refrigerant header 70 to the interior of the third refrigerant header 71. The multiple heat transfer tubes 41a are arranged side by side at intervals in the vertical direction Z. In the first embodiment, each heat transfer tube 41a extends to the right from the third refrigerant header 71, bends back at the right end, extends to the left, and is connected to the second refrigerant header 70. In the first embodiment, four heat transfer tubes 41a are provided. The number of heat transfer tubes 41a provided in the first refrigerant path section 41 is not particularly limited as long as it is one or more.

[0027] The second refrigerant path section 42 is a refrigerant path section 40 located below the first refrigerant path section 41. The second refrigerant path section 42 is arranged in a row below the first refrigerant path section 41. The second refrigerant path section 42 has a plurality of heat transfer tubes 42a and third refrigerant headers 72a, 72b. The third refrigerant header 72a is arranged in a row below the third refrigerant header 71 of the first refrigerant path section 41. The third refrigerant header 72b is arranged in a row below the third refrigerant header 72a. The plurality of heat transfer tubes 42a connect the interior of the second refrigerant header 70 to the interior of the third refrigerant header 72a or the interior of the third refrigerant header 72b. The plurality of heat transfer tubes 42a are located below the plurality of heat transfer tubes 41a of the first refrigerant path section 41. The plurality of heat transfer tubes 42a are arranged in a row at intervals in the vertical direction Z. In the first embodiment, each heat transfer tube 42a extends to the right from the third refrigerant header 72a or the third refrigerant header 72b, bends back at the right end, extends to the left, and is connected to the second refrigerant header 70. The number of heat transfer tubes 42a included in the second refrigerant path portion 42 is equal to or greater than the number of heat transfer tubes 41a included in the first refrigerant path portion 41 and the number of heat transfer tubes 43a included in the third refrigerant path portion 43. In the first embodiment, the number of heat transfer tubes 42a included in the second refrigerant path portion 42 is greater than the number of heat transfer tubes 41a included in the first refrigerant path portion 41 and the number of heat transfer tubes 43a included in the third refrigerant path portion 43. In the first embodiment, eight heat transfer tubes 42a are provided. Of the eight heat transfer tubes 42a, the four heat transfer tubes 42a located at the top are connected to the third refrigerant header 72a. The remaining four heat transfer tubes 42a located at the bottom of the eight heat transfer tubes 42a are connected to the third refrigerant header 72b. The number of heat transfer tubes 42a provided in the second refrigerant path portion 42 is not particularly limited as long as it is one or more.

[0028] The third refrigerant path section 43 is a refrigerant path section 40 located below the second refrigerant path section 42. The third refrigerant path section 43 is arranged in a row below the second refrigerant path section 42. The third refrigerant path section 43 includes a plurality of heat transfer tubes 43a and a third refrigerant header 73. The third refrigerant header 73 is arranged in a row below the third refrigerant header 72b of the second refrigerant path section 42. The plurality of heat transfer tubes 43a connect the interior of the second refrigerant header 70 to the interior of the third refrigerant header 73. The plurality of heat transfer tubes 43a are located below the plurality of heat transfer tubes 42a of the second refrigerant path section 42. The plurality of heat transfer tubes 43a are arranged in a row with intervals in the vertical direction Z. In the first embodiment, each heat transfer tube 43a extends to the right from the third refrigerant header 73, bends back at the right end, extends to the left, and is connected to the second refrigerant header 70. In the first embodiment, four heat transfer tubes 43a are provided. The number of heat transfer tubes 43a provided in the third refrigerant path portion 43 is not particularly limited as long as it is one or more.

[0029] The second heat exchange section 32 is arranged below the first heat exchange section 31. When the heat exchanger 30 functions as a condenser, the second heat exchange section 32 is a supercooling region that further cools the refrigerant 19 condensed in the first heat exchange section 31 to a temperature below the saturation temperature. The vertical dimension Z of the second heat exchange section 32 is smaller than the vertical dimension Z of the first heat exchange section 31. The vertical dimension Z of the second heat exchange section 32 is equal to or smaller than half the vertical dimension Z of the first heat exchange section 31. As an example, the vertical dimension Z of the second heat exchange section 32 is approximately one-eighth the vertical dimension Z of the first heat exchange section 31. The vertical dimension Z of the second heat exchange section 32 is not particularly limited.

[0030] The second heat exchanger 32 includes a connection path 44 and a plurality of heat transfer fins 32a provided in the connection path 44. The connection path 44 is located below the third refrigerant path 43. The connection path 44 is arranged in a row below the third refrigerant path 43. The connection path 44 includes a first heat transfer tube 51, second heat transfer tubes 52a and 52b, and a third heat transfer tube 53. A plurality of heat transfer fins 32a arranged at intervals in the left-right direction Y are connected to each of the heat transfer tubes 51, 52a, 52b, and 53 in the connection path 44. A refrigerant 19 flows through each of the heat transfer tubes 51, 52a, 52b, and 53. Each of the heat transfer tubes 51, 52a, 52b, and 53 is, for example, a flat tube whose dimension in the vertical direction Z is smaller than its dimension in the front-rear direction X. The upper and lower surfaces of each of the heat transfer tubes 51, 52a, 52b, and 53 are flat surfaces perpendicular to the vertical direction Z. The first heat transfer tube 51, the second heat transfer tubes 52a and 52b, and the third heat transfer tube 53 are arranged side by side in the vertical direction Z at intervals.

[0031] The first heat transfer tube 51 connects the first refrigerant header 60 and the first refrigerant path portion 41. In the first embodiment, the first heat transfer tube 51 is the lowest heat transfer tube among the heat transfer tubes provided in the connection path portion 44. In the first embodiment, the first heat transfer tube 51 extends to the right from the first refrigerant header 60, bends back at the right end, and extends to the left. The end of the first heat transfer tube 51 opposite to the end connected to the first refrigerant header 60 is connected to the third refrigerant header 71 of the first refrigerant path portion 41 via a connection pipe 51c. In FIG. 2, the connection pipe 51c is schematically indicated by a dashed line.

[0032] The second heat transfer pipes 52a, 52b connect the first refrigerant header 60 and the second refrigerant path portion 42. The second heat transfer pipes 52a, 52b are located above the first heat transfer pipe 51. In the first embodiment, the second heat transfer pipe 52a is the uppermost heat transfer pipe among the heat transfer pipes provided in the connection path portion 44. The second heat transfer pipe 52b is located below the second heat transfer pipe 52a. In the first embodiment, the second heat transfer pipes 52a, 52b extend to the right from the first refrigerant header 60, bend back at the right end, and extend to the left. The end of the second heat transfer pipe 52a opposite to the end connected to the first refrigerant header 60 is connected to the third refrigerant header 72a of the second refrigerant path portion 42 via the connection pipe 52c. The end of the second heat transfer tube 52b opposite to the end connected to the first refrigerant header 60 is connected via a connecting pipe 52d to a third refrigerant header 72b of the second refrigerant path portion 42. In Figure 2, the connecting pipes 52c and 52d are schematically shown by dashed lines.

[0033] The third heat transfer pipe 53 connects the first refrigerant header 60 and the third refrigerant path portion 43. The third heat transfer pipe 53 is disposed between the first heat transfer pipe 51 and the second heat transfer pipe 52b in the vertical direction Z. In the first embodiment, the third heat transfer pipe 53 extends to the right from the first refrigerant header 60, bends back at the right end, and extends to the left. The end of the third heat transfer pipe 53 opposite to the end connected to the first refrigerant header 60 is connected to the third refrigerant header 73 of the third refrigerant path portion 43 via a connection pipe 53c. In FIG. 2, the connection pipe 53c is schematically indicated by a dashed line.

[0034] Figure 3 is a cross-sectional view showing the first refrigerant header 60. Figure 4 is a cross-sectional view showing the first refrigerant header 60, taken along the line IV-IV in Figure 3. Note that although two IV-IV cross sections are shown in Figure 3, the cross sections at both locations have the same shape, and so they are shown together in Figure 4.

[0035] The first refrigerant header 60 is a liquid header into which the refrigerant 19 in a gas-liquid two-phase state flows. As shown in FIG. 3 , the first refrigerant header 60 has a first orifice plate 61, a second orifice plate 62, and a header main body 63. The header main body 63 is cylindrical. In the first embodiment, the header main body 63 has a cylindrical shape extending in the vertical direction Z. The header main body 63 has a bottom wall 63a, a top wall 63b, and a peripheral wall 63c. The peripheral wall 63c has a cylindrical shape extending in the vertical direction Z. The lower end of the peripheral wall 63c is closed by the bottom wall 63a. The upper end of the peripheral wall 63c is closed by the top wall 63b.

[0036] The first orifice plate 61 and the second orifice plate 62 are located inside the header main body 63. In the first embodiment, the plate surfaces of the first orifice plate 61 and the second orifice plate 62 face the vertical direction Z. As shown in Fig. 4, the first orifice plate 61 and the second orifice plate 62 are disk-shaped. The outer peripheral edge of the first orifice plate 61 and the outer peripheral edge of the second orifice plate 62 are fixed to the inner peripheral surface of the peripheral wall portion 63c.

[0037] As shown in FIG. 3 , the first orifice plate 61 and the second orifice plate 62 are spaced apart in the vertical direction Z. The first orifice plate 61 is spaced apart above the bottom wall portion 63 a. The second orifice plate 62 is spaced apart above the first orifice plate 61. The second orifice plate 62 is spaced apart below the top wall portion 63 b. The vertical Z distance between the first orifice plate 61 and the second orifice plate 62 and the vertical Z distance between the top wall portion 63 b and the second orifice plate 62 are greater than the vertical Z distance between the bottom wall portion 63 a and the first orifice plate 61. The vertical Z distance between the first orifice plate 61 and the second orifice plate 62 and the vertical Z distance between the top wall portion 63 b and the second orifice plate 62 may be the same or different from each other.

[0038] The first orifice plate 61 and the second orifice plate 62 divide the internal space of the header main body 63 into a first space 64a, a second space 64b, and a third space 64c. The first space 64a is the space between the bottom wall portion 63a and the first orifice plate 61 in the vertical direction Z. The second space 64b is the space between the first orifice plate 61 and the second orifice plate 62 in the vertical direction Z. The third space 64c is the space between the second orifice plate 62 and the top wall portion 63b in the vertical direction Z. The second space 64b is located above the first space 64a. The third space 64c is located above the second space 64b.

[0039] The vertical Z dimension of the first space 64a is smaller than the vertical Z dimension of the second space 64b and the vertical Z dimension of the third space 64c. The vertical Z dimension of the second space 64b and the vertical Z dimension of the third space 64c may be the same as or different from each other. The volume of the first space 64a is smaller than the volumes of the second space 64b and the third space 64c. The volumes of the second space 64b and the third space 64c may be the same as or different from each other. The size relationship between the vertical Z dimensions and volumes of the first space 64a, the second space 64b, and the third space 64c is not particularly limited, and any size relationship may be possible.

[0040] A first orifice hole 61a is formed in the first orifice plate 61. The first orifice hole 61a penetrates the first orifice plate 61 in the vertical direction Z. The cross-sectional area of ​​the first orifice hole 61a is smaller than the flow path cross-sectional area of ​​the refrigerant pipe 81, for example. The cross-sectional area of ​​the first orifice hole 61a is smaller than the flow path cross-sectional area of ​​each of the heat transfer tubes 51, 52a, 52b, and 53 connected to the first refrigerant header 60, for example. In the first embodiment, the cross-sectional area of ​​the first orifice hole 61a is the cross-sectional area of ​​the first orifice hole 61a in a cross section perpendicular to the vertical direction. The flow path cross-sectional area of ​​the refrigerant pipe 81 is larger than the flow path cross-sectional area of ​​each of the heat transfer tubes 51, 52a, 52b, and 53.

[0041] The first orifice hole 61a opens to the first space 64a and the second space 64b. The first space 64a and the second space 64b are connected to each other via the first orifice hole 61a. As shown in Fig. 4, in the first embodiment, the first orifice hole 61a is a circular hole. In the first embodiment, two first orifice holes 61a are provided side by side in the front-rear direction X.

[0042] As shown in FIG. 3 , the second orifice plate 62 has a second orifice hole 62a formed therein. The second orifice hole 62a penetrates the second orifice plate 62 in the vertical direction Z. The cross-sectional area of ​​the second orifice hole 62a is, for example, smaller than the flow path cross-sectional area of ​​the refrigerant piping 81. The cross-sectional area of ​​the second orifice hole 62a is, for example, smaller than the flow path cross-sectional area of ​​each heat transfer tube 51, 52a, 52b, and 53 connected to the first refrigerant header 60. In the first embodiment, the cross-sectional area of ​​the second orifice hole 62a is the cross-sectional area of ​​the second orifice hole 62a in a cross section perpendicular to the vertical direction. The cross-sectional areas of the first orifice hole 61a and the second orifice hole 62a may be the same or different from each other.

[0043] The second orifice hole 62a opens to the second space 64b and the third space 64c. The second space 64b and the third space 64c are connected to each other via the second orifice hole 62a. As shown in FIG. 4 , in the first embodiment, the second orifice hole 62a is a circular hole. In the first embodiment, two second orifice holes 62a are provided side by side in the front-rear direction X. In the first embodiment, each second orifice hole 62a is provided at a position overlapping with each first orifice hole 61a as viewed in the vertical direction Z. Note that the first orifice holes 61a and the second orifice holes 62a may be provided at positions that do not overlap as viewed in the vertical direction Z.

[0044] As shown in Fig. 3, a refrigerant pipe 81 is connected to the first refrigerant header 60. The refrigerant pipe 81 is a pipe through which the refrigerant 19 flows, flowing into or out of the header main body 63. In the first embodiment, the refrigerant pipe 81 is connected to the lower end of the peripheral wall portion 63c of the header main body 63 from the left side. The refrigerant pipe 81 is connected to the first space 64a. Note that the refrigerant pipe 81 may be connected to any part of the first refrigerant header 60 as long as it is connected to the first space 64a.

[0045] The first refrigerant header 60 is connected to the heat transfer tubes 51, 52a, 52b, and 53 included in the connection path 44. The heat transfer tubes 51, 52a, 52b, and 53 included in the connection path 44 are connected to the peripheral wall 63c of the header main body 63 and protrude into the first refrigerant header 60. In the first embodiment, the heat transfer tubes 51, 52a, 52b, and 53 included in the connection path 44 are connected to the peripheral wall 63c from the side opposite to the side to which the refrigerant piping 81 is connected. Specifically, the heat transfer tubes 51, 52a, 52b, and 53 penetrate the right-side portion of the peripheral wall 63c in the left-right direction Y and protrude to the left from the inner circumferential surface of the peripheral wall 63c.

[0046] The first heat transfer pipe 51 and the third heat transfer pipe 53 protrude into the second space 64b and open into the second space 64b. As a result, the first heat transfer pipe 51 and the third heat transfer pipe 53 are connected to the second space 64b. Therefore, the first refrigerant path portion 41 is connected to the second space 64b via the first heat transfer pipe 51, and the third refrigerant path portion 43 is connected to the second space 64b via the third heat transfer pipe 53. In the second space 64b, the left end of the first heat transfer pipe 51 and the left end of the third heat transfer pipe 53 are located to the right of the first orifice hole 61a and the second orifice hole 62a. In other words, the first orifice hole 61a and the second orifice hole 62a are positioned so as not to overlap in the vertical direction Z with the first heat transfer pipe 51 and the third heat transfer pipe 53 connected to the second space 64b.

[0047] The second heat transfer pipes 52a, 52b protrude into the third space 64c and open into the third space 64c. This connects the second heat transfer pipes 52a, 52b to the third space 64c. Therefore, the second refrigerant path 42 is connected to the third space 64c via the second heat transfer pipes 52a, 52b. In the third space 64c, the left ends of the second heat transfer pipes 52a, 52b are located to the right of the first orifice hole 61a and the second orifice hole 62a. In other words, the first orifice hole 61a and the second orifice hole 62a are positioned so as not to overlap in the vertical direction Z with the second heat transfer pipes 52a, 52b connected to the third space 64c.

[0048] The second refrigerant header 70 is a gas header into which the gaseous refrigerant 19 flows. As shown in FIG. 2 , the second refrigerant header 70 is tubular and extends in the vertical direction Z. Both ends of the second refrigerant header 70 in the vertical direction Z are closed. A refrigerant pipe 82 is connected to the second refrigerant header 70. The refrigerant pipe 82 is a pipe through which the refrigerant 19 flows when it flows into or out of the second refrigerant header 70. The refrigerant pipe 82 is connected to an upper portion of the peripheral wall of the second refrigerant header 70 from the left side. The refrigerant pipe 82 may be connected to any location on the second refrigerant header 70. The heat transfer tubes 40a provided in each refrigerant path section 40 are connected to the peripheral wall of the second refrigerant header 70 from the right side. The second refrigerant header 70 is connected to the first refrigerant header 60 via multiple refrigerant path sections 40.

[0049] FIG. 5 is a diagram schematically illustrating the flow of refrigerant 19 during heating operation. As shown in FIG. 5 , during heating operation, refrigerant 19 flows from refrigerant pipe 81 into first space 64a of first refrigerant header 60. At this time, refrigerant 19 flowing into first space 64a is in a gas-liquid two-phase state. The refrigerant 19 flowing into first space 64a flows into second space 64b through first orifice hole 61a. At this time, refrigerant 19 is blown upward from first orifice hole 61a and flows into second space 64b. In the first embodiment, first orifice hole 61a is positioned so as not to overlap with first heat transfer tube 51 and third heat transfer tube 53 in the vertical direction Z. This prevents the flow of refrigerant 19 blown upward from first orifice hole 61a within second space 64b from being obstructed by first heat transfer tube 51 and third heat transfer tube 53. The velocity of the refrigerant 19 that has flowed into the second space 64b through the first orifice hole 61a is higher than the velocity of the refrigerant 19 in the first space 64a.

[0050] A portion of the refrigerant 19 that flows from the first space 64a to the second space 64b flows into the first heat transfer tube 51 and the third heat transfer tube 53 connected to the second space 64b. The refrigerant 19 that flows into the first heat transfer tube 51 flows via the connecting pipe 51c to the third refrigerant header 71 of the first refrigerant path section 41, and branches from the third refrigerant header 71 to flow into the interiors of the plurality of heat transfer tubes 41a. The refrigerant 19 that flows into the third heat transfer tube 53 flows via the connecting pipe 53c to the third refrigerant header 73 of the third refrigerant path section 43, and branches from the third refrigerant header 73 to flow into the interiors of the plurality of heat transfer tubes 43a.

[0051] The remainder of the refrigerant 19 that flows from the first space 64a to the second space 64b flows into the third space 64c through the second orifice hole 62a. At this time, the refrigerant 19 is blown upward from the second orifice hole 62a and flows into the third space 64c. In the first embodiment, the second orifice hole 62a is positioned so as not to overlap with the second heat transfer tubes 52a, 52b in the vertical direction Z, thereby preventing the flow of the refrigerant 19 blown upward from the second orifice hole 62a in the third space 64c from being obstructed by the second heat transfer tubes 52a, 52b. The refrigerant 19 that flows into the third space 64c flows into the second heat transfer tubes 52a, 52b connected to the third space 64c. The refrigerant 19 that flows into each second heat transfer tube 52a, 52b flows through each connecting pipe 52c, 52d to each third refrigerant header 72a, 72b of the second refrigerant path section 42, and branches from each third refrigerant header 72a, 72b to flow into the interior of multiple heat transfer tubes 42a.

[0052] The refrigerant 19 that branches off and flows into each heat transfer tube 41a, 42a, 43a in this manner merges inside the second refrigerant header 70 and flows out of the second refrigerant header 70 through the refrigerant piping 82 connected to the second refrigerant header 70.

[0053] During heating operation when the heat exchanger 30 functions as an evaporator, the refrigerant 19 flowing from the first space 64a to the second space 64b includes both liquid and gaseous refrigerant 19. The gaseous refrigerant 19 has a lower density than the liquid refrigerant 19. Therefore, the increase in velocity of the gaseous refrigerant 19 passing through the first orifice hole 61a is greater than the increase in velocity of the liquid refrigerant 19 passing through the first orifice hole 61a. As a result, the velocity of the gaseous refrigerant 19 is greater than the velocity of the liquid refrigerant 19 in the second space 64b. The higher the velocity of the refrigerant 19, the greater the pressure loss that occurs when passing through the second orifice hole 62a. Therefore, the higher the velocity of the refrigerant 19, the more difficult it is for the refrigerant 19 to pass through the second orifice hole 62a. Therefore, gaseous refrigerant 19, which flows at a relatively high velocity, is less likely to flow from the second space 64b through the second orifice hole 62a to the third space 64c than liquid refrigerant 19, which flows at a relatively low velocity. As a result, the ratio of liquid refrigerant 19 to gaseous refrigerant 19 in the third space 64c is greater than the ratio of liquid refrigerant 19 to gaseous refrigerant 19 in the second space 64b. Therefore, the ratio of liquid refrigerant 19 in the refrigerant 19 flowing from the third space 64c into the second heat transfer tubes 52a, 52b is greater than the ratio of liquid refrigerant 19 in the refrigerant 19 flowing from the second space 64b into the first heat transfer tube 51 and the third heat transfer tube 53. Because the density of liquid refrigerant 19 is greater than the density of gaseous refrigerant 19, the mass flow rate of refrigerant 19 flowing from the third space 64c into the second heat transfer tubes 52a, 52b is greater than the mass flow rate of refrigerant 19 flowing from the second space 64b into the first heat transfer tube 51 and the third heat transfer tube 53. Here, a greater mass flow rate of refrigerant 19 means that the proportion of liquid refrigerant 19 in the gas-liquid two-phase refrigerant 19 is greater. In other words, the gas-liquid two-phase refrigerant 19 flowing in the second heat transfer tubes 52a, 52b contains a greater proportion of liquid refrigerant 19 than in the first heat transfer tube 51 and the third heat transfer tube 53.

[0054] Fig. 6 is a diagram schematically showing the flow of refrigerant 19 during defrosting operation. The flow of refrigerant 19 during defrosting operation, which will be described below, is the same as the flow of refrigerant 19 during cooling operation. As shown in Fig. 6, during defrosting operation, refrigerant 19 flows from refrigerant pipe 82 into second refrigerant header 70. At this time, refrigerant 19 flowing into refrigerant pipe 82 is in a gaseous state. The refrigerant 19 that has flowed into the second refrigerant header 70 branches and flows into each of the heat transfer tubes 41a, 42a, 43a of the multiple refrigerant path sections 40 connected to the second refrigerant header 70.

[0055] During defrosting operation, the refrigerant 19 flowing through the heat transfer tubes 41a of the first refrigerant path portion 41 join together in the third refrigerant header 71 and flow from the third refrigerant header 71 to the first heat transfer tubes 51 of the connection path portion 44 via the connection piping 51c. The refrigerant 19 flowing through the first heat transfer tubes 51 flows into the second space 64b of the first refrigerant header 60 and passes through the first orifice hole 61a into the first space 64a. The refrigerant 19 flowing into the first space 64a flows out of the first refrigerant header 60 through the refrigerant piping 81.

[0056] During defrosting operation, the refrigerant 19 flowing through the upper four heat transfer tubes 42a of the plurality of heat transfer tubes 42a of the second refrigerant path portion 42 join together in the third refrigerant header 72a and flow from the third refrigerant header 72a through the connection pipe 52c to the second heat transfer tube 52a of the connection path portion 44. The refrigerant 19 flowing through the lower four heat transfer tubes 42a of the plurality of heat transfer tubes 42a of the second refrigerant path portion 42 join together in the third refrigerant header 72b and flow from the third refrigerant header 72b through the connection pipe 52d to the second heat transfer tube 52b of the connection path portion 44. The refrigerant 19 flowing through the second heat transfer tubes 52a, 52b flows into the third space 64c of the first refrigerant header 60, flows through the second orifice hole 62a to the second space 64b, and flows from the second space 64b through the first orifice hole 61a to the first space 64a. The refrigerant 19 that has flowed into the first space 64 a flows out of the first refrigerant header 60 through the refrigerant pipe 81 .

[0057] During defrosting operation, the refrigerant 19 flowing through the heat transfer tubes 43a of the third refrigerant path portion 43 join together in the third refrigerant header 73 and flow from the third refrigerant header 73 to the third heat transfer tubes 53 of the connection path portion 44 via the connection piping 53c. The refrigerant 19 flowing through the third heat transfer tubes 53 flows into the second space 64b of the first refrigerant header 60 and into the first space 64a through the first orifice hole 61a. The refrigerant 19 flowing into the first space 64a flows out of the first refrigerant header 60 through the refrigerant piping 81. During defrosting operation, the gaseous refrigerant 19 flowing into the second refrigerant header 70 is liquefied as it flows through the refrigerant path portions 40 and the connection path portion 44, and the liquid refrigerant 19 flows into the first refrigerant header 60.

[0058] Here, the refrigerant 19 that flows into the second space 64b from the first heat transfer tube 51 and the third heat transfer tube 53 can enter the first space 64a by passing through one first orifice hole 61a, whereas the refrigerant 19 that flows into the third space 64c from the second heat transfer tubes 52a and 52b must pass through both the first orifice hole 61a and the second orifice hole 62a to enter the first space 64a. Therefore, the pressure loss of the refrigerant 19 that flows from the third space 64c into the first refrigerant header 60 until it flows out of the first refrigerant header 60 is greater than the pressure loss of the refrigerant 19 that flows from the second space 64b into the first refrigerant header 60 until it flows out of the first refrigerant header 60. As a result, the refrigerant 19 flows more easily through the path from the second refrigerant header 70 into the second space 64b than through the path from the second refrigerant header 70 into the third space 64c. Therefore, the amount of refrigerant 19 flowing through the first heat transfer tube 51 and the third heat transfer tube 53 connected to the second space 64b is likely to be greater than when multiple heat transfer tubes 51, 52a, 52b, 53 are connected to the same space within the first refrigerant header 60. Therefore, the amount of refrigerant 19 flowing through the first refrigerant path portion 41 and the third refrigerant path portion 43 connected to the first refrigerant header 60 via the first heat transfer tube 51 and the third heat transfer tube 53, respectively, is likely to be greater than when multiple heat transfer tubes 51, 52a, 52b, 53 are connected to the same space within the first refrigerant header 60.

[0059] A blower 15 is disposed in front (+X direction) of the heat exchanger 30. When the blower 15 is driven, outdoor air is drawn into the housing 11 of the outdoor unit 10 through an intake port (not shown) provided in the rear wall of the outdoor unit 10, generating an airflow that passes through the heat exchanger 30. The airflow passes through the heat exchanger main body 30a. In the first embodiment, the blower 15 is an axial flow fan, such as a propeller fan, having an impeller that rotates about an axis of rotation extending in the front-rear direction X. In this case, the amount of air in the airflow generated by the blower 15 tends to be greater in the central portion of the blower 15 in the vertical direction Z. Therefore, when the blower 15 is disposed in front of the heat exchanger main body 30a, the amount of air passing through the central portion of the heat exchanger main body 30a in the vertical direction Z tends to be greater than the amount of air passing through portions of the heat exchanger main body 30a that are located above or below the central portion. Therefore, when the first refrigerant path portion 41, the second refrigerant path portion 42, and the third refrigerant path portion 43 are provided as in the first embodiment, the amount of air passing through the second refrigerant path portion 42, which is located between the first refrigerant path portion 41 and the third refrigerant path portion 43 in the vertical direction Z, tends to be greater than the amount of air passing through the first refrigerant path portion 41 and the third refrigerant path portion 43. As a result, the amount of heat exchange between the refrigerant 19 and the air tends to be greater in the second refrigerant path portion 42 than in the first refrigerant path portion 41 and the third refrigerant path portion 43. Therefore, during heating operation in which the heat exchanger 30 functions as an evaporator, the refrigerant 19 flowing through the second refrigerant path portion 42 tends to gasify more quickly than the refrigerant 19 flowing through the first refrigerant path portion 41 and the third refrigerant path portion 43. Therefore, in the conventional heating operation, the refrigerant 19 flowing through the second refrigerant path portion 42 may become a single-phase gas before flowing into the second refrigerant header 70. The heat exchange efficiency between the refrigerant 19 and the air is highest when the refrigerant 19 is in a two-phase gas-liquid state, and therefore, if the refrigerant 19 quickly becomes a single-phase gas in the second refrigerant path portion 42, the heat exchange efficiency in the second refrigerant path portion 42 decreases, which causes a problem of a decrease in the heat exchange efficiency of the entire heat exchanger 30.

[0060] In response to the above problem, according to the first embodiment, the heat exchanger 30 is a heat exchanger 30 of a refrigeration cycle apparatus 100, and includes a plurality of refrigerant path sections 40 that are separated from one another and each have at least one heat transfer tube 40a, a first refrigerant header 60, and a second refrigerant header 70 connected to the first refrigerant header 60 via the plurality of refrigerant path sections 40. The plurality of refrigerant path sections 40 include a first refrigerant path section 41, a second refrigerant path section 42 that is positioned vertically below the first refrigerant path section 41, and a third refrigerant path section 43 that is positioned vertically below the second refrigerant path section 42. The first refrigerant header 60 includes a cylindrical header main body 63, a first orifice plate 61 that is positioned inside the header main body 63 and has a first orifice hole 61a formed therein, and a second orifice plate 62 that is positioned inside the header main body 63 and has a second orifice hole 62a formed therein. The internal space of the header main body 63 is partitioned by the first orifice plate 61 and the second orifice plate 62 into a first space 64a, a second space 64b, and a third space 64c. The first space 64a and the second space 64b are connected to each other via the first orifice hole 61a. The second space 64b and the third space 64c are connected to each other via the second orifice hole 62a. A refrigerant pipe 81 is connected to the first space 64a, through which the refrigerant 19 flows, flowing into or out of the header main body 63. At least one of the first refrigerant path portion 41 and the third refrigerant path portion 43 is connected to the second space 64b. The second refrigerant path portion 42 is connected to the third space 64c.

[0061] According to the above configuration, when the refrigerant 19 flows from the refrigerant pipe 81 into the first space 64a, the first orifice hole 61a and the second orifice hole 62a make it difficult for gaseous refrigerant 19 to flow into the third space 64c, and relatively easy for liquid refrigerant 19 to flow into the third space 64c, as described above. This makes it possible to increase the proportion of liquid refrigerant 19 contained in the refrigerant 19 in the third space 64c compared to the proportion of liquid refrigerant 19 contained in the refrigerant 19 in the second space 64b. Therefore, the mass flow rate of the refrigerant 19 flowing from the third space 64c to the refrigerant path portion 40 can be increased compared to the mass flow rate of the refrigerant 19 flowing from the second space 64b to the refrigerant path portion 40. Because the second refrigerant path portion 42 is connected to the third space 64c, the mass flow rate of the refrigerant 19 flowing from the third space 64c to the second refrigerant path portion 42 can be increased. As a result, when the heat exchanger 30 functions as an evaporator during heating operation, the amount of liquid refrigerant 19 contained in the refrigerant 19 flowing through the second refrigerant path portion 42 can be increased compared to a conventional configuration in which the refrigerant 19 flows evenly through each refrigerant path portion 40, and the timing at which the refrigerant 19 flowing through the second refrigerant path portion 42 becomes single-phase gas can be delayed. Therefore, the timing at which the refrigerant 19 becomes single-phase gas in each refrigerant path portion 40 can be made closer to each other. This prevents only the refrigerant 19 flowing through the second refrigerant path portion 42 from becoming single-phase gas first, and prevents a decrease in the heat exchange efficiency in the second refrigerant path portion 42. This prevents a decrease in the heat exchange efficiency of the heat exchanger 30. As a result, the heating capacity for heating the room can be improved during heating operation.

[0062] For example, the mass flow rate of the refrigerant 19 flowing through the second refrigerant path portion 42 can be adjusted by adjusting the opening area of ​​the first orifice hole 61 a and the opening area of ​​the second orifice hole 62 a. When the heat exchanger 30 functions as an evaporator, the amount of refrigerant 19 is adjusted so that the refrigerant 19 flowing through each of the first refrigerant path portion 41, the second refrigerant path portion 42, and the third refrigerant path portion 43 is completely gasified near the outlet where it flows out into the second refrigerant header 70, in other words, so that the quality fraction of the refrigerant 19 is 1. This makes it possible to maintain the state of the refrigerant 19 in each refrigerant path portion 40 in a gas-liquid two-phase state for a long period of time, thereby further improving the heat exchange efficiency of the heat exchanger 30.

[0063] As described above, during heating operation in which the heat exchanger 30 functions as an evaporator, frost may form on the surface of the heat exchanger 30. Frost is more likely to form in the third refrigerant path portion 43, which is located below the first refrigerant path portion 41 and the second refrigerant path portion 42, than in the first refrigerant path portion 41 and the second refrigerant path portion 42. This may be caused, for example, by the frost formed in the first refrigerant path portion 41 and the second refrigerant path portion 42 melting into water during defrosting operation and flowing downward. When the heating operation is resumed with the water still attached to the third refrigerant path portion 43, the water solidifies and forms frost. In particular, when the heat transfer tubes 43a of the third refrigerant path portion 43 are flat tubes with flat upper surfaces, water is likely to accumulate on the upper surfaces of the heat transfer tubes 43a, and a large amount of frost is likely to form in the third refrigerant path portion 43. Furthermore, it has been conventionally known that when the heat exchanger 30 functions as a condenser during defrosting operation, the refrigerant 19 that flows from the refrigerant pipe 82 into the second refrigerant header 70 tends to flow to the upper refrigerant path portion 40. This is because the higher the refrigerant path portion 40 is located, the greater the distance in the vertical direction Z from the first refrigerant header 60, and the greater the tendency for the pressure of the refrigerant 19 to drop significantly when it flows from the refrigerant path portion 40 to the first refrigerant header 60.

[0064] For the reasons described above, the third refrigerant path portion 43 is prone to frost buildup, and in the past, the amount of refrigerant 19 flowing through the third refrigerant path portion 43 during defrosting operation was likely to be smaller than that of the other refrigerant path portions 40. As a result, in the past, even if frost on the other refrigerant path portions 40 could be removed, the frost on the third refrigerant path portion 43 could not be completely removed, resulting in a problem of prolonged defrosting operation. Since the heating operation is stopped during defrosting operation, the comfort of the indoor occupants is reduced. For example, it is conceivable to terminate the defrosting operation without waiting for the frost on the third refrigerant path portion 43 to be completely removed, thereby shortening the defrosting operation time. However, in this case, when the heating operation is resumed, the frost remaining in the third refrigerant path portion 43 would further increase the amount of frost that would form on the third refrigerant path portion 43, further reducing the heat exchange efficiency of the heat exchanger 30.

[0065] To address the above problem, according to the first embodiment, the third refrigerant path portion 43 is connected to the second space 64b. As described above, during defrosting operation, the refrigerant 19 flowing from the second refrigerant header 70 through the refrigerant path portion 40 into the third space 64c of the first refrigerant header 60 cannot flow out of the first refrigerant header 60 without passing through two orifice holes, the first orifice hole 61a and the second orifice hole 62a. Therefore, the refrigerant 19 flows less easily through the path of the refrigerant 19 flowing from the second refrigerant header 70 into the third space 64c than through the path of the refrigerant 19 flowing from the second refrigerant header 70 into the second space 64b. As a result, during defrosting operation, the amount of refrigerant 19 flowing through the refrigerant path portion 40 connected to the second space 64b tends to be greater than when each refrigerant path portion 40 is connected to the same space of the first refrigerant header 60. Therefore, by connecting the third refrigerant path portion 43 to the second space 64b, it is possible to increase the amount of refrigerant 19 flowing through the third refrigerant path portion 43, where frost is likely to remain during defrosting operation. This reduces the time required to melt frost formed in the third refrigerant path portion 43, and shortens the time required to perform the defrosting operation. This reduces the time during which the heating operation function is stopped, and prevents a decrease in the comfort of users in the room.

[0066] According to the first embodiment, the first refrigerant path portion 41 is connected to the second space 64b. Connecting both the first refrigerant path portion 41 and the third refrigerant path portion 43 to the second space 64b facilitates relatively increasing the mass flow rate of the refrigerant 19 flowing through the second refrigerant path portion 42 connected to the third space 64c and the proportion of the liquid refrigerant 19 in the gas-liquid two-phase state during heating operation. This effectively prevents only the refrigerant 19 flowing through the second refrigerant path portion 42 from becoming a single-phase gas first, thereby preventing a decrease in the heat exchange efficiency in the second refrigerant path portion 42. This effectively prevents a decrease in the heat exchange efficiency of the heat exchanger 30.

[0067] According to the first embodiment, the number of heat transfer tubes 42a included in the second refrigerant path portion 42 is equal to or greater than the number of heat transfer tubes 41a included in the first refrigerant path portion 41 and the number of heat transfer tubes 43a included in the third refrigerant path portion 43. This makes it easy to increase the number of heat transfer tubes 43a through which refrigerant 19 flows from the third space 64c, i.e., the number of heat transfer tubes 43a through which the mass flow rate of refrigerant 19 and the proportion of liquid refrigerant 19 in the gas-liquid two-phase state are likely to be relatively high. This more effectively suppresses the deterioration of the heat exchange efficiency of the heat exchanger 30 than when the number of heat transfer tubes 42a included in the second refrigerant path portion 42 is smaller than the number of heat transfer tubes 40a included in the other refrigerant path portions 40.

[0068] According to the first embodiment, the heat exchanger 30 includes a connection path portion 44 located vertically below the third refrigerant path portion 43. The connection path portion 44 includes a first heat transfer pipe 51 connecting the first refrigerant header 60 and the first refrigerant path portion 41, second heat transfer pipes 52a and 52b connecting the first refrigerant header 60 and the second refrigerant path portion 42, and a third heat transfer pipe 53 connecting the first refrigerant header 60 and the third refrigerant path portion 43. The first refrigerant path portion 41 is connected to the second space 64b via the first heat transfer pipe 51, and the third refrigerant path portion 43 is connected to the third space 64c via the second heat transfer pipes 52a and 52b. Therefore, during heating operation, the refrigerant 19 that flows from the refrigerant pipe 81 into the first refrigerant header 60 flows through the heat transfer tubes 51, 52a, 52b, and 53 of the connection path portion 44 to each refrigerant path portion 40. During heating operation, the first heat transfer tube 51 is the upstream heat transfer tube of the first refrigerant path portion 41, the second heat transfer tubes 52a and 52b are the upstream heat transfer tubes of the second refrigerant path portion 42, and the third heat transfer tube 53 is the upstream heat transfer tube of the third refrigerant path portion 43. Here, as the refrigerant 19 flows through the heat transfer tubes, the pressure of the refrigerant 19 decreases due to pressure loss, and the saturation temperature of the refrigerant 19 decreases. As a result, the temperature of the refrigerant 19 decreases as it flows through the heat transfer tubes. Therefore, the temperature of the refrigerant 19 flowing through the heat transfer tubes 51, 52a, 52b, and 53, which are the heat transfer tubes on the upstream side of each refrigerant path section 40, tends to be higher than the temperature of the refrigerant 19 flowing through each refrigerant path section 40. As a result, frost is less likely to form on the connection path section 44, which includes the heat transfer tubes 51, 52a, 52b, and 53. By arranging such a connection path section 44 below the third refrigerant path section 43, frost is less likely to form on the portion of the heat exchanger body 30a located below the third refrigerant path section 43. As a result, frost formation on the third refrigerant path section 43 can be suppressed compared to when the connection path section 44 is not provided.

[0069] Embodiment 2. Fig. 7 is a partial cross-sectional view showing a part of a heat exchanger 230 according to embodiment 2. In the following description, the same components as those in the above-described embodiment will be denoted by the same reference numerals as appropriate, and the description thereof may be omitted.

[0070] As shown in FIG. 7 , in a heat exchanger body 230a of a heat exchanger 230 according to the second embodiment, a connection path portion 244 of a second heat exchange section 232 is disposed inverted in the vertical direction Z relative to the connection path portion 44 according to the first embodiment. The first heat transfer tube 251 is the uppermost heat transfer tube in the connection path portion 244. The second heat transfer tube 252a is the lowermost heat transfer tube in the connection path portion 244. The second heat transfer tube 252b is arranged adjacent to and above the second heat transfer tube 252a. The third heat transfer tube 253 is arranged adjacent to and above the second heat transfer tube 252b and below the first heat transfer tube 251. In the second embodiment, the first heat transfer tube 251 and the third heat transfer tube 253 are located between the second heat transfer tubes 252a, 252b and the third refrigerant path portion 43 in the vertical direction Z.

[0071] The first refrigerant header 260 of the second embodiment is arranged inverted in the vertical direction Z relative to the first refrigerant header 60 of the first embodiment. Inside the header main body 263, the first orifice plate 261 is arranged above and spaced apart from the second orifice plate 262. The internal space of the header main body 263 is partitioned from top to bottom into a first space 264a, a second space 264b, and a third space 264c in this order. In the second embodiment, the refrigerant piping 281 connected to the first space 264a is connected to the upper end of the first refrigerant header 260. The first heat transfer tube 251 and the third heat transfer tube 253 are connected to the second space 264b. The second heat transfer tubes 252a and 252b are connected to the third space 264c. The other configuration of the first refrigerant header 260 is similar to the other configuration of the first refrigerant header 60 of the first embodiment. The other configurations of the heat exchanger 230 are similar to the other configurations of the heat exchanger 30 in the first embodiment.

[0072] According to the second embodiment, the first heat transfer pipe 251 and the third heat transfer pipe 253 are located between the second heat transfer pipes 252a, 252b and the third refrigerant path portion 43 in the vertical direction Z. Therefore, during defrosting operation, the heat transfer pipes 251, 253 connected to the first refrigerant path portion 41 and the third refrigerant path portion 43, through which the refrigerant 19 flows more easily than through the second refrigerant path portion 42, can be positioned closer to the third refrigerant path portion 43 in the vertical direction Z. This makes it easier to melt frost formed in the third refrigerant path portion 43 during defrosting operation by the heat of the refrigerant 19 flowing through the first heat transfer pipe 251 and the third heat transfer pipe 253, through which the amount of refrigerant 19 is likely to be large. Therefore, it is easier to melt frost formed in the third refrigerant path portion 43 during defrosting operation, and the time required to perform the defrosting operation can be shortened.

[0073] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the configurations of the above-described embodiments, and the following configurations and methods may also be adopted.

[0074] The number of heat transfer tubes included in each of the first refrigerant path section, the second refrigerant path section, and the third refrigerant path section is not particularly limited as long as it is at least one. The number of heat transfer tubes included in the second refrigerant path section may be the same as the number of heat transfer tubes included in the first refrigerant path section and the number of heat transfer tubes included in the third refrigerant path section. The number of heat transfer tubes included in the first refrigerant path section and the number of heat transfer tubes included in the third refrigerant path section may be different from each other.

[0075] In the above-described embodiment, the first refrigerant header and each refrigerant path portion are connected to each other via a heat transfer tube included in the connection path portion, but this is not limited to this. The first refrigerant header and each refrigerant path portion may be connected to each other via a heat transfer tube separate from the connection path portion, or may be connected to each other directly without using another heat transfer tube.

[0076] In the connection path section, the number of first heat transfer tubes and the number of third heat transfer tubes connected to the second space of the first refrigerant header, and the number of second heat transfer tubes connected to the third space of the first refrigerant header are not particularly limited as long as they are each at least one. If the number of first heat transfer tubes α1, the number of second heat transfer tubes α2, and the number of third heat transfer tubes α3 are expressed as α1:α2:α3, the ratio α1:α2:α3 is 1:2:1 in the above-described embodiment. The ratio α1:α2:α3 may be, for example, 2:4:2, 2:2:2, or 1:4:1. The number of first heat transfer tubes α1 and the number of third heat transfer tubes α3 may be different from each other. The connection path section may not be provided. In other words, the second heat exchange section 32 that constitutes the supercooling region in the above-described embodiment may not be provided.

[0077] At least one of the first refrigerant path portion and the third refrigerant path portion may be connected to the second space of the first refrigerant header. Of the first refrigerant path portion and the third refrigerant path portion, only the first refrigerant path portion may be connected to the second space. In this case, the third refrigerant path portion is connected to the third space. Of the first refrigerant path portion and the third refrigerant path portion, only the third refrigerant path portion may be connected to the second space. In this case, the first refrigerant path portion is connected to the third space. Furthermore, in this case, when a heat exchanger according to the present disclosure is applied to an outdoor unit of an air conditioner as in the above-described embodiment, the amount of refrigerant flowing through the third refrigerant path portion during defrosting operation can be increased. This makes it easier to shorten the time required to remove frost from the third refrigerant path portion, which is prone to frost, by defrosting operation.

[0078] The first space, the second space, and the third space of the first refrigerant header may be arranged side by side in a direction other than the vertical direction. For example, the first space, the second space, and the third space may be arranged side by side in the horizontal direction. The first orifice plate may have any configuration as long as it has a first orifice hole connecting the first space and the second space. The second orifice plate may have any configuration as long as it has a second orifice hole connecting the second space and the third space.

[0079] The heat exchanger according to the present disclosure may be installed in any type of refrigeration cycle device. The refrigeration cycle device equipped with the heat exchanger according to the present disclosure may be any device that utilizes a refrigeration cycle in which a refrigerant circulates, and is not limited to an air conditioner. The refrigeration cycle device may be a refrigerator or a heat pump water heater. When the refrigeration cycle device is an air conditioner, the heat exchanger according to the present disclosure may be applied to the heat exchanger of the outdoor unit, the heat exchanger of the indoor unit, or both the heat exchanger of the indoor unit and the heat exchanger of the outdoor unit. When the heat exchanger according to the present disclosure is applied to the heat exchanger of the indoor unit of an air conditioner, the heat exchange efficiency of the heat exchanger can be improved during cooling operation in which the heat exchanger of the indoor unit functions as an evaporator, thereby improving the cooling capacity during cooling operation. When the heat exchanger according to the present disclosure is applied to the heat exchanger of an indoor unit, the indoor unit may be of any type. The indoor unit equipped with the heat exchanger according to the present disclosure may be a floor-standing indoor unit, a ceiling-mounted indoor unit, or a wall-mounted indoor unit.

[0080] The configurations and methods described in this specification can be combined as appropriate within the scope of not contradicting each other.

[0081] 15...blower, 19...refrigerant, 30, 230...heat exchanger, 40...refrigerant path portion, 40a, 41a, 42a, 43a...heat transfer tube, 41...first refrigerant path portion, 42...second refrigerant path portion, 43...third refrigerant path portion, 44, 244...connection path portion, 51, 251...first heat transfer tube, 52a, 52b, 252a, 252b...second heat transfer tube, 53, 253...third heat transfer tube, 60, 260...first refrigerant Refrigerant header, 61, 261...first orifice plate, 61a...first orifice hole, 62, 262...second orifice plate, 62a...second orifice hole, 63, 263...header body, 64a, 264a...first space, 64b, 264b...second space, 64c, 264c...third space, 70...second refrigerant header, 81, 281...refrigerant piping, 100...refrigeration cycle device, Z...vertical direction

Claims

1. A heat exchanger for a refrigeration cycle device, comprising: a plurality of refrigerant path sections each having at least one heat transfer tube and separated from one another; a first refrigerant header; and a second refrigerant header connected to the first refrigerant header via the plurality of refrigerant path sections, wherein the plurality of refrigerant path sections include a first refrigerant path section, a second refrigerant path section located vertically below the first refrigerant path section, and a third refrigerant path section located vertically below the second refrigerant path section, wherein the first refrigerant header has a cylindrical header main body section, a first orifice plate located inside the header main body and having a first orifice hole formed therein, and a second orifice plate located inside the header main body and having a second orifice hole formed therein, wherein the internal space of the header main body is partitioned by the first orifice plate and the second orifice plate into a first space, a second space, and a third space, wherein the first space and the second space are connected to one another via the first orifice hole, a heat exchanger in which the second space and the third space are connected to each other via the second orifice hole, a refrigerant pipe is connected to the first space, through which refrigerant flows into or out of the header main body, at least one of the first refrigerant path portion and the third refrigerant path portion is connected to the second space, and the second refrigerant path portion is connected to the third space.

2. A heat exchanger according to claim 1, wherein the third refrigerant path portion is connected to the second space.

3. A heat exchanger according to claim 2, wherein the first refrigerant path portion is connected to the second space.

4. A heat exchanger as described in claim 3, wherein the number of heat transfer tubes included in the second refrigerant path section is equal to or greater than the number of heat transfer tubes included in the first refrigerant path section and the number of heat transfer tubes included in the third refrigerant path section.

5. A heat exchanger as described in claim 3 or 4, comprising a connection path portion located vertically below the third refrigerant path portion, the connection path portion having: a first heat transfer pipe connecting the first refrigerant header and the first refrigerant path portion; a second heat transfer pipe connecting the first refrigerant header and the second refrigerant path portion; and a third heat transfer pipe connecting the first refrigerant header and the third refrigerant path portion, wherein the first refrigerant path portion is connected to the second space via the first heat transfer pipe and the third refrigerant path portion is connected to the third space via the third heat transfer pipe, and the second refrigerant path portion is connected to the third space via the second heat transfer pipe.

6. A heat exchanger according to claim 5, wherein the first heat transfer pipe and the third heat transfer pipe are positioned vertically between the second heat transfer pipe and the third refrigerant path portion.

7. A refrigeration cycle device comprising: a heat exchanger according to any one of claims 1 to 6; and a blower that generates an airflow passing through the heat exchanger.

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