Heat exchanger

Abstract

This heat exchanger according to an embodiment comprises a plurality of heat transfer tubes, a plurality of fins, and a pair of headers. The pair of headers are obtained by stacking a plurality of plate-like members, and include a first header to which an inflow pipe for a refrigerant is connected and a second header to which an outflow pipe for the refrigerant is connected. The first header has: a first plate-like member having a first flow passage to which the inflow pipe is connected and that causes the refrigerant flowing in from the inflow pipe to flow in a first direction; and a second plate-like member having a plurality of second flow passages that divide the refrigerant flowing through the first flow passage and causes the refrigerant to flow in a second direction. The second flow passage cross-sectional area of the second flow passage positioned at the highest position is greater than that of the second flow passage positioned at the lowest position, and among two second flow passages vertically adjacent to each other, the second flow passage cross-sectional area of the upper second flow passage is equal to or greater than the second flow passage cross-sectional area of the lower second flow passage.

Description

heat exchanger

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a heat exchanger.

[0002] Refrigeration cycle devices, such as air conditioners, are equipped with heat exchangers that exchange heat between a refrigerant and air. A parallel-flow heat exchanger, one example of such a heat exchanger, primarily comprises a pair of headers that stand vertically at a distance from each other, a plurality of heat transfer tubes that are horizontally suspended between the headers, and a plurality of fins that are arranged at a predetermined pitch in the direction in which the heat transfer tubes are suspended. The heat transfer tubes are arranged at intervals in the height direction of the headers. The fins are thermally connected to the heat transfer tubes by inserting them into a plurality of slits formed in the fins that correspond to the heat transfer tubes that are arranged in the height direction of the headers.

[0003] One of the pair of headers is connected to a pipe (inlet pipe) through which the refrigerant flows, and the other is connected to a pipe (outlet pipe) through which the refrigerant flows out. However, the pipes through which the refrigerant flows in and out are opposite when the heat exchanger functions as an evaporator or a condenser. One header receives the refrigerant from the connected inlet pipe and distributes the refrigerant to each heat transfer tube. The other header combines the refrigerant distributed to each heat transfer tube and distributes the refrigerant out through the connected outlet pipe.

[0004] It is desirable for the amount of refrigerant flowing through the multiple heat transfer tubes to be uniform. Therefore, for example, by providing a distributor between the inlet pipe and the header to which the inlet pipe is connected, the amount of refrigerant diverted from the header to the multiple heat transfer tubes can be made uniform. However, providing a distributor requires that a diverting pipe be installed for each heat transfer tube and that each diverting pipe be routed separately, and that piping space be secured for this.

[0005] For example, when a heat exchanger functions as an evaporator, a gas-liquid mixed (gas-liquid two-phase) refrigerant flows from the inlet pipe into a header connected to a lower portion of the header. Because the gas phase refrigerant is lighter than the liquid phase refrigerant, the gas-liquid ratio of the two-phase refrigerant flowing into the header tends to be higher at the top and higher at the bottom. Therefore, when the heat exchanger functions as an evaporator, it is difficult to distribute the two-phase refrigerant from the header to the heat transfer tubes at a uniform gas-liquid ratio, which can easily cause uneven gas-liquid ratios among the multiple heat transfer tubes.

[0006] International Publication No. 2013 / 160952

[0007] The present invention has been made based on this, and its purpose is to provide a heat exchanger that more easily achieves uniformity in the flow rate of refrigerant diverted from the header and uniformity in the gas-liquid ratio while saving space.

[0008] According to an embodiment, the heat exchanger includes a plurality of heat transfer tubes, a plurality of fins, and a pair of headers. The heat transfer tubes are arranged at intervals in a first direction along a vertical line and extend in a second direction perpendicular to the first direction, through which a refrigerant flows. The fins are arranged at intervals in the second direction and extend in the first direction. The pair of headers have flow paths through which the refrigerant flows, stand in the first direction, and connect to both ends of the plurality of heat transfer tubes in the second direction. The pair of headers are formed by stacking a plurality of plate-shaped members parallel to a plane defined by the first direction and a third direction perpendicular to both the first direction and the second direction, and include a first header to which the refrigerant inlet pipe is connected and a second header to which the refrigerant outlet pipe is connected. The first header includes a first plate-shaped member and a second plate-shaped member. The first plate-shaped member has a first flow path connected to the inlet pipe and allowing the refrigerant flowing from the inlet pipe to flow in the first direction. The second plate-shaped member has a plurality of second flow paths that split the refrigerant flowing through the first flow path and allow the refrigerant to flow in the second direction. A second flow path cross-sectional area, which is a cross-sectional area of ​​the second flow paths perpendicular to the flow direction of the refrigerant, is larger for the second flow path located at the top in the first direction than for the second flow path located at the bottom in the first direction, and the second flow path cross-sectional area of ​​the upper second flow path of two second flow paths adjacent to each other in the vertical direction is equal to or larger than the second flow path cross-sectional area of ​​the lower second flow path.

[0009] 1 is a circuit diagram showing a schematic configuration of a refrigeration cycle apparatus according to a first embodiment; FIG. 2 is a plan view showing a schematic configuration of an outdoor unit including an outdoor heat exchanger according to the first embodiment; FIG. 3 is an exploded perspective view showing a schematic configuration of a header of an outdoor heat exchanger according to the first embodiment; FIG. 4 is a cross-sectional view showing a schematic configuration of the outdoor heat exchanger at a location indicated by arrow A2 in FIG. 2 in the first embodiment, viewed from the direction of the arrow; FIG. 5 is an exploded perspective view showing a schematic configuration of the header of an outdoor heat exchanger according to a second embodiment; FIG. 6 is a cross-sectional view showing a schematic configuration of the outdoor heat exchanger at a location equivalent to the location indicated by arrow A2 in FIG. 2 in the second embodiment, viewed from the direction of the arrow; FIG. 7 is an exploded perspective view showing a schematic configuration of the header of an outdoor heat exchanger according to a third embodiment; FIG. 8 is a cross-sectional view showing a schematic configuration of the outdoor heat exchanger at a location equivalent to the location indicated by arrow A2 in FIG. 2 in the third embodiment, viewed from the direction of the arrow.

[0010] Embodiments of the present invention will be described below with reference to FIGS. 1 to 8 . (First Embodiment) FIG. 1 is a circuit diagram showing a schematic configuration of a refrigeration cycle apparatus 1 according to this embodiment. The refrigeration cycle apparatus 1 is, for example, an air conditioner capable of either or both of cooling and heating operation, and includes, as main components, a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an expansion valve 5, an indoor heat exchanger 6, a refrigerant flow path 7 connecting these components, an outdoor blower 8, and an indoor blower 9. Of these components, for example, the compressor 2, the four-way valve 3, the outdoor heat exchanger 4, the expansion valve 5, and the outdoor blower 8 constitute an outdoor unit 11 of the air conditioner. In contrast, for example, the indoor heat exchanger 6 and the indoor blower 9 constitute an indoor unit 12 of the air conditioner.

[0011] The compressor 2 includes, for example, a compressor main body 2a and an accumulator 2b. The compressor main body 2a compresses the gas-phase refrigerant supplied from the accumulator 2b and discharges the high-temperature, high-pressure gas-phase refrigerant into the refrigerant flow path 7. The accumulator 2b separates the refrigerant returned via the refrigerant flow path 7 into gas and liquid, and supplies the gas-phase refrigerant to the compressor main body 2a.

[0012] The four-way valve 3 switches between operation modes such as cooling operation and heating operation by changing the flow of refrigerant in the refrigerant flow path 7. In the example shown in Fig. 1 , the solid arrows indicate the flow of refrigerant during cooling operation, and the dashed arrows indicate the flow of refrigerant during heating operation.

[0013] For example, during cooling operation, as shown by the solid arrows in Figure 1, the refrigerant flows in the order of compressor 2, four-way valve 3, outdoor heat exchanger 4, expansion valve 5, and indoor heat exchanger 6. In this case, the outdoor heat exchanger 4 functions as a condenser, and the indoor heat exchanger 6 functions as an evaporator, thereby cooling the space to be air-conditioned.

[0014] On the other hand, during heating operation, as shown by the dashed arrows in Figure 1, the refrigerant flows in the order of compressor 2, four-way valve 3, indoor heat exchanger 6, expansion valve 5, and outdoor heat exchanger 4. In this case, the indoor heat exchanger 6 functions as a condenser, and the outdoor heat exchanger 4 functions as an evaporator, thereby heating the space to be air-conditioned.

[0015] Next, a heat exchanger according to this embodiment will be described. While such a heat exchanger can be used as the outdoor heat exchanger 4 or the indoor heat exchanger 6 of the refrigeration cycle apparatus 1 shown in Fig. 1, this embodiment assumes, as an example, that the heat exchanger is the outdoor heat exchanger 4. Fig. 2 is a plan view showing a schematic configuration of an outdoor unit 11 equipped with the outdoor heat exchanger 4 according to this embodiment.

[0016] 1 and 2 , the outdoor unit 11 includes, as main elements, a compressor 2 (a compressor main body 2 a and an accumulator 2 b), a four-way valve 3, an outdoor heat exchanger 4, an expansion valve 5, and an outdoor blower 8. Each of these elements is housed in a housing 21.

[0017] The housing 21 has a three-dimensional, approximately box-like shape formed by molding sheet metal. FIG. 2 shows a schematic vertical view of the outdoor unit 11 with the top panel, front cover, and other components removed. In the example shown in FIG. 2, the bottom plate 21a, side plates 21b and 21c, back plate 21d, and partition plate 21e of the housing 21 are made of sheet metal such as iron. The bottom plate 21a serves as a base on which the compressor 2, outdoor heat exchanger 4, outdoor blower 8, and other components are mounted. The bottom plate 21a is fixed to the mounting surface by bolts or other fastening means using mounting pieces 21f.

[0018] The side plates 21b, 21c and the back plate 21d are attached to the bottom plate 21a so as to stand vertically from the bottom plate 21a. The interior of the housing 21, which is defined by the bottom plate 21a, the side plates 21b, 21c, the back plate 21d, and a top plate and front cover (not shown), is divided by a partition plate 21e into a space (machine room) in which the compressor 2 and other components are disposed and a space (heat exchange room) in which the outdoor heat exchanger 4, the outdoor blower 8, and other components are disposed. The partition plate 21e, together with the side plates 21b, 21c and the back plate 21d, is attached to the bottom plate 21a so as to stand vertically from the bottom plate 21a.

[0019] The outdoor blower 8 includes, for example, a fan 8a and a fan motor 8b. The outdoor blower 8 is positioned opposite the outdoor heat exchanger 4. It draws air (outside air) into the housing 21 through the outdoor heat exchanger 4 via an opening 21g and discharges it to the outside through an opening 21h in the housing 21. The opening 21g is formed between an end 210b of the side plate 21b and an end 210d of the back plate 21d, sandwiched between the top plate and the bottom plate 21a. The end 210b of the side plate 21b is the end where the side plate 21b bends toward the end 210d of the back plate 21d. The opening 21h is formed between an end 211b of the side plate 21b and an end 210c of the side plate 21c, sandwiched between the top plate and the bottom plate 21a. A front cover (not shown) is attached to the opening 21h. The front cover stands vertically from the bottom plate 21a so as to face the outdoor blower 8, and covers the opening 21h so that the air (outside air) drawn in from the opening 21g can be discharged to the outside of the housing 21.

[0020] The outdoor heat exchanger 4 is disposed so as to face the opening 21g of the housing 21. In the example shown in Fig. 2, the outdoor heat exchanger 4 has a generally continuous L-shape in which the portion along the opening 21g (back plate 21d) and the portion along the side plate 21b are gently curved when viewed from above in the vertical direction.

[0021] 3 and 4 show a portion of the configuration of the outdoor heat exchanger 4 according to this embodiment. FIG. 3 is an exploded perspective view showing a schematic configuration of the header of the outdoor heat exchanger 4. FIG. 4 is a cross-sectional view showing the outdoor heat exchanger 4 at a location indicated by arrow A2 in FIG. 2 , viewed from the direction of the arrow. In the following description, a first direction D1, a second direction D2, and a third direction D3 are defined as shown in FIGS. 3 and 4 . These directions D1, D2, and D3 are perpendicular to one another. The first direction D1 is a direction along a vertical line (up-down direction). In the illustrated example, the arrow points downward (downward), and the opposite direction is upward (upward). The second direction D2 is a direction perpendicular to the first direction D1 and corresponds to the direction in which a heat transfer tube 41 (described later) extends. The third direction D3 is a direction perpendicular to both the first direction D1 and the second direction D2. The second direction D2 and the third direction D3 define a horizontal plane.

[0022] 2 to 4, the outdoor heat exchanger 4 mainly comprises a plurality of heat transfer tubes 41, a plurality of fins 42, and a pair of headers 43. The materials of the heat transfer tubes 41, the fins 42, and the headers 43 are not particularly limited, but they can all be made of aluminum or an aluminum alloy, for example.

[0023] The heat transfer tubes 41 are arranged at predetermined intervals in the first direction D1 and are tubular elements extending in the second direction D2 through which the refrigerant flows. The number of heat transfer tubes 41 included in the outdoor heat exchanger 4 is not particularly limited. In the example shown in FIGS. 2 to 4 , the heat transfer tubes 41 are arranged at predetermined intervals in the first direction D1 in the second direction D2 to connect a pair of headers 43. That is, the heat transfer tubes 41 are flow-dividing tubes that branch the refrigerant flowing into one of the pair of headers 43 in the second direction D2 between the headers 43 and flow to the other of the pair of headers 43. Note that, for convenience, the illustrated example shows an example in which eight heat transfer tubes 41 are arranged, but the number of heat transfer tubes 41 arranged is not limited to this.

[0024] In this embodiment, the heat transfer tube 41 has a flattened shape in which the dimensions (length) in the second direction D2 and the dimensions (width) in the third direction D3 are larger than the dimensions (height or thickness) in the first direction D1. For example, the heat transfer tube 41 is a flattened tube having an oval flow path (cross-sectional shape) that appears to be crushed in the first direction D1. However, the cross-sectional shape of the heat transfer tube 41 perpendicular to the refrigerant flow direction (second direction D2) is not limited to an oval shape and may be, for example, a circle, an ellipse, a rectangle, a square, or the like. Furthermore, the interior of the heat transfer tube 41 may be partitioned, for example, into multiple flow paths aligned in the third direction D3.

[0025] In the second direction D2, one end of each heat transfer tube 41 is connected to one of a pair of headers 43 (for example, the header 44 shown in FIG. 2 ), and one end of the flow path 41 a of the heat transfer tube 41 opens in the header 43 (a third plate-like member 53 described later in this embodiment). In addition, in the second direction D2, the other end of each heat transfer tube 41 is connected to the other of the pair of headers 43 (for example, the header 45 shown in FIG. 2 ), and the other end of the flow path 41 a of the heat transfer tube 41 opens in the header 43 (a third plate-like member 53 described later in this embodiment).

[0026] For example, when the refrigeration cycle apparatus 1 is in heating operation, that is, when the outdoor heat exchanger 4 functions as an evaporator, the refrigerant flows into one header 44, is divided into each of the plurality of heat transfer tubes 41, joins in the other header 45, and flows out from the outdoor heat exchanger 4. Also, for example, when the refrigeration cycle apparatus 1 is in cooling operation, that is, when the outdoor heat exchanger 4 functions as a condenser, the refrigerant flows into the other header 45, is divided into each of the plurality of heat transfer tubes 41, joins in one header 44, and flows out from the outdoor heat exchanger 4.

[0027] The fins 42 are plate-like elements arranged at predetermined intervals (fin pitch) in the second direction D2 and extending in the first direction D1. In this embodiment, the fins 42 have a generally rectangular shape with a dimension (height) in the first direction D1 greater than a dimension (width) in the third direction D3 as viewed from the second direction D2. The fins 42 may be plate-like and flat in the second direction D2, or may have an uneven portion, such as a bent portion or a stepped portion, in part.

[0028] 4, the fins 42 have a plurality of slits 42a. These slits 42a are spatial regions into which the heat transfer tubes 41 are inserted to integrally assemble the heat transfer tubes 41 and the fins 42, and are arranged at intervals equal to the intervals at which the heat transfer tubes 41 are arranged in the first direction D1.

[0029] When viewed from the second direction D2, the edge of the slit 42a is continuous along the outer periphery of the heat transfer tube 41. Also, when viewed from the second direction D2, the slit 42a has an opening on one side in the third direction D3 and a closed portion on the other side, and extends in the third direction D3 from the opening to the closed portion. The heat transfer tube 41 is inserted through the opening of the slit 42a and abuts against the closed portion. This allows the end of the heat transfer tube 41 inserted into the slit 42a (the end in the third direction D3) to be tightly fitted to the closed portion of the slit 42a. In this state, the heat transfer tube 41 is positioned relative to the slit 42a. The heat transfer tube 41 and the fins 42 are integrally assembled and thermally connected, for example, by brazing. This allows heat transfer between the heat transfer tube 41 and the fins 42.

[0030] The pair of headers 43 (44, 45) have flow paths through which the refrigerant flows, stand in the first direction D1, and connect to both ends in the second direction D2 of the plurality of heat transfer tubes 41. These headers 43 (44, 45) are configured by stacking a plurality of plate-like members 50. The plurality of plate-like members 50 are integrally assembled by, for example, brazing so that the refrigerant flow paths provided in each of these, which will be described later, communicate with each other.

[0031] Each of the plurality of plate-like members 50 extends parallel to a plane defined by the first direction D1 and the third direction D3. In other words, each of the plurality of plate-like members 50 has a pair of main surfaces parallel to the plane defined by the first direction D1 and the third direction D3. That is, each of the plurality of plate-like members 50 has a plate-like shape in which the dimension (height) in the first direction D1 and the dimension (width) in the third direction D3 are larger than the dimension (thickness) in the second direction D2.

[0032] The pair of headers 43 includes a first header to which a refrigerant inlet pipe is connected and a second header to which a refrigerant outlet pipe is connected. As described above, in this embodiment, it is assumed that the outdoor heat exchanger 4 functions as an evaporator, and the header 44 shown in FIG. 2 will be described as the first header and the header 45 as the second header. In this case, for example, the pipe 46 connected to the header 44 serves as the refrigerant inlet pipe, and the pipe 47 connected to the header 45 serves as the refrigerant outlet pipe. In contrast, when the outdoor heat exchanger 4 functions as a condenser, the pipe 47 connected to the header 45 serves as the refrigerant inlet pipe, and the pipe 46 connected to the header 44 serves as the refrigerant outlet pipe. That is, in this case, the header 45 serves as the first header and the header 44 serves as the second header.

[0033] There is no particular limitation on the number of plate-like members 50 that constitute the header 44 and the header 45. Figures 2 to 4 show an example in which five plate-like members 50 (51, 52, 53, 54, 55) are stacked.

[0034] In the illustrated example, the five plate-like members 50 have the same dimensions (heights) in the first direction D1 and the same dimensions (widths) in the third direction D3. In contrast, the dimensions (thicknesses) of these plate-like members 50 in the second direction D2 are not uniform. As an example, the first, second, and third plate-like members 51, 52, and 53 (described later) have the same thickness, while the fourth and fifth plate-like members 54 and 55 (described later) have the same thickness but thinner than these plate-like members. That is, the first, second, and third plate-like members 51, 52, and 53 have the same hexahedral (rectangular) outer shapes, and the fourth and fifth plate-like members 54 and 55 have the same hexahedral (rectangular) outer shapes. However, these outer shapes are not limited to the illustrated example and may be any shape.

[0035] 3 and 4 show an example of the configuration of the header 44, which serves as the first header into which the refrigerant flows from the pipe 46 when the outdoor heat exchanger 4 functions as an evaporator. As shown in FIGS. 3 and 4 , the header 44 is configured by stacking five plate-shaped members 50 (51 to 55). In the illustrated example, a first plate-shaped member 51, a second plate-shaped member 52, and a third plate-shaped member 53 are stacked, and a pair of a fourth plate-shaped member 54 and a fifth plate-shaped member 55 are stacked so as to sandwich these three. These plate-shaped members 51 to 55 each have a flow path through which the refrigerant flowing from the pipe 46 flows, and these flow paths guide the refrigerant so that it flows toward the multiple heat transfer tubes 41.

[0036] The pipe 46, which serves as a refrigerant inlet pipe when the outdoor heat exchanger 4 functions as an evaporator, is connected to a fourth plate-shaped member 54. Each of the heat transfer pipes 41 is connected to a fifth plate-shaped member 55. That is, the fourth plate-shaped member 54 is the plate-shaped member located most upstream of the five plate-shaped members 51 to 55 in the direction in which the refrigerant flowing from the pipe 46 into the header 44 flows through the flow path of the header 44 (hereinafter referred to as the refrigerant flow direction). The fifth plate-shaped member 55 is the plate-shaped member located most downstream of the five plate-shaped members 51 to 55 in the refrigerant flow direction. The first plate-shaped member 51, the second plate-shaped member 52, and the third plate-shaped member 53 are intermediate plate-shaped members located between the fourth plate-shaped member 54 and the fifth plate-shaped member 55.

[0037] The first plate member 51, the second plate member 52, and the third plate member 53 are arranged in this order from upstream to downstream in the refrigerant flow direction between the fourth plate member 54 located at the most upstream position and the fifth plate member 55 located at the most downstream position. That is, in the example shown in Figures 3 and 4, the five plate members 50 are stacked so that they are lined up in the order of the fourth plate member 54, the first plate member 51, the second plate member 52, the third plate member 53, and the fifth plate member 55 from upstream to downstream in the refrigerant flow direction.

[0038] In this embodiment, each of the plate-shaped members 51 to 55 has a flow path that guides the refrigerant in a predetermined direction. The refrigerant that flows in from the pipe 46 flows into the header 44 through the fourth plate-shaped member 54, passes through the flow paths of the first plate-shaped member 51, the second plate-shaped member 52, and the third plate-shaped member 53, and is guided from the fifth plate-shaped member 55 to each of the plurality of heat transfer tubes 41.

[0039] For this reason, a hole portion (hereinafter referred to as a first communication hole) 54a to which the piping 46 is connected is formed in the fourth plate-shaped member 54. The first communication hole 54a is disposed below the fourth plate-shaped member 54 in the first direction D1, and connects the piping 46 to a first flow path 51a of the first plate-shaped member 51, which will be described later.

[0040] As shown by arrow A46 in FIG. 4 , the refrigerant flows from the pipe 46 connected to the first communication hole 54a into the first flow path 51a. The shape of the first communication hole 54a may correspond to the shape of the pipe 46. The shape of the first communication hole 54a is the cross-sectional shape of the first communication hole 54a perpendicular to the flow direction of the refrigerant in the pipe 46 connected to the first communication hole 54a. The shape of the pipe 46 is the cross-sectional shape of the pipe 46 perpendicular to the extension direction of the pipe 46. For example, the cross-sectional shape may be any shape, such as a circle, an oval, an ellipse, a rectangle, or a square. In this embodiment, as an example, it is assumed that the shape of the first communication hole 54a is a circle.

[0041] The fifth plate-shaped member 55 also has a plurality of holes (hereinafter referred to as second communication holes) 55a to which the heat transfer tubes 41 are connected. The second communication holes 55a are arranged in the first direction D1 in the same number as the heat transfer tubes 41 so as to correspond one-to-one with the heat transfer tubes 41. The shape of the second communication holes 55a may correspond to the shape of the heat transfer tubes 41. The shape of the second communication holes 55a is the cross-sectional shape of the second communication holes 55a perpendicular to the refrigerant flow direction in the heat transfer tubes 41 connected to the second communication holes 55a. The shape of the heat transfer tubes 41 is the cross-sectional shape of the heat transfer tubes 41 perpendicular to the extension direction of the heat transfer tubes 41. For example, the cross-sectional shape may be any shape, such as a circle, an oval, an ellipse, a rectangle, or a square. In this embodiment, the second communication holes 55a are assumed to be oval in shape.

[0042] Each of the plurality of second communication holes 55a is connected to a respective heat transfer tube 41. Each second communication hole 55a communicates the heat transfer tube 41 connected to that second communication hole 55a with the third flow path 53a. Furthermore, each second communication hole 55a communicates the heat transfer tube 41 with the second flow path 52a corresponding to that heat transfer tube 41 via the third flow path 53a.

[0043] The center line of each second communication hole 55a coincides with the cross-sectional center line of the heat transfer tube 41 connected to that second communication hole 55a, i.e., the cross-sectional center line (dashed line C52 in FIG. 4 ) of the second flow path 52a (described later) to which that heat transfer tube 41 corresponds. The center line of the second communication hole 55a is a line passing through the center of a cross section of the second communication hole 55a that is perpendicular to the refrigerant flow direction. The center of the second communication hole 55a is the center of a circle if the shape of the second communication hole 55a is circular or elliptical, the intersection of the major and minor axes if the shape of the second communication hole 55a is elliptical, or the intersection of diagonals if the shape of the second communication hole 55a is rectangular or square.

[0044] The first plate-shaped member 51 has a flow path (hereinafter referred to as the first flow path) 51a through which the refrigerant flowing from the pipe 46 flows in the first direction D1. As shown by arrow A46 in FIG. 4 , the refrigerant flows from the pipe 46 into the first flow path 51a through the first communication hole 54a. As shown by arrow A51 in FIG. 4 , the refrigerant flowing into the first flow path 51a flows upward in the first direction D1 through the first flow path 51a. In this embodiment, it is assumed that the outdoor heat exchanger 4 functions as an evaporator, and the refrigerant flowing from the pipe 46 into the first flow path 51a is a gas-liquid two-phase refrigerant. This gas-liquid two-phase refrigerant is the return refrigerant discharged from the compressor 2 shown in FIG. 2 and guided to the indoor heat exchanger 6, where it is heat exchanged and contributes to heating the room.

[0045] The header 45, which serves as the first header when the outdoor heat exchanger 4 functions as a condenser, is configured by stacking a first plate-shaped member 51, a second plate-shaped member 52, a third plate-shaped member 53, a fourth plate-shaped member 54, and a fifth plate-shaped member 55 from upstream to downstream in the direction in which the refrigerant flowing from the pipe 47 flows through the header 45 (similar to the header 44; see FIG. 2 ). However, in the header 45, a hole (not shown) connecting the first flow path 51a to the pipe 47 is located, for example, above the fourth plate-shaped member 54 in the first direction D1. The refrigerant that flows from the pipe 47 into the first flow path 51a of the header 45 through the hole flows downward in the first direction D1 through the first flow path 51a. When the outdoor heat exchanger 4 functions as a condenser, the refrigerant flowing from the pipe 47 into the first flow path 51a of the header 45 is a gas-phase refrigerant. Such gas-phase refrigerant is the refrigerant that is discharged from the compressor 2 shown in FIG.

[0046] 3 and 4 , the first flow path 51a is a hole (through-hole) that penetrates between a contact surface 51b of the first plate-shaped member 51 with the fourth plate-shaped member 54 and a contact surface 51c of the first plate-shaped member 51 with the second plate-shaped member 52. The contact surface 51b is the surface of the first plate-shaped member 51 that faces the fourth plate-shaped member 54 in the second direction D2. The contact surface 51c is the surface of the first plate-shaped member 51 that faces the second plate-shaped member 52 in the second direction D2. The contact surfaces 51b and 51c are main surfaces (principal surfaces) that constitute the first plate-shaped member 51. The first flow path 51a extends linearly in the first direction D1 and has both ends (an upper end 51d and a lower end 51e) in the first direction D1 that butt against each other.

[0047] The first flow path 51 a is defined by an upper end 51 d, a lower end 51 e, and a pair of side ends 51 f, 51 g that surround the through hole. In other words, the first plate-shaped member 51 is configured as a frame having the upper end 51 d, the lower end 51 e, the pair of side ends 51 f, 51 g, and the first flow path 51 a surrounded by these. When the first plate-shaped member 51 is assembled with the fourth plate-shaped member 54 and the second plate-shaped member 52, the first flow path 51 a forms a space closed by the upper end 51 d, the lower end 51 e, the pair of side ends 51 f, 51 g, and these plate-shaped members 54, 52.

[0048] The cross-sectional area of ​​the first flow path 51a (hereinafter referred to as the first flow path cross-sectional area) is set to satisfy the Reynolds number range for uniformly mixing the refrigerant (gas-liquid two-phase refrigerant) flowing from the pipe 46 into gas and liquid. In other words, the first flow path cross-sectional area is set to a size that uniformly mixes the gas-liquid two-phase refrigerant, as derived from the Reynolds number relationship. The first flow path cross-sectional area is the cross-sectional area of ​​the first flow path 51a perpendicular to the refrigerant flow direction (upward in the first direction D1) in the first flow path 51a. In the illustrated example, the first flow path cross-sectional area is constant over the entire length of the first flow path in the first direction D1. However, the first flow path cross-sectional area does not have to be constant over the entire length. Such an embodiment will be described later as a third embodiment.

[0049] The shape of the first flow path cross section is not particularly limited as long as it satisfies the above range of Reynolds number. For example, the first flow path cross section can be any shape, such as a rectangle, a square, a semicircle, a semi-oval, or a semi-ellipse. In this embodiment, as an example, it is assumed that the first flow path cross section is a rectangle.

[0050] For example, the wetted perimeter length of the first flow path 51a is S [m], and the cross-sectional area of ​​the first flow path 51a (first flow path cross-sectional area) is A [m ２ ], the vapor quality of the refrigerant in the inflow pipe 46 is x, the viscosity coefficient of the vapor in the inflow pipe 46 is μv [Pa s], the viscosity coefficient of the liquid in the inflow pipe 46 is μl [Pa s], and the mass flow rate of the refrigerant at the bottom of the first flow path 51a in the first direction D1 is M [kg / s]. ２ s]), the vapor Reynolds number (Rev), and the liquid Reynolds number (Rel) are defined by the following equations (1) to (4): D = 4 x A / S (1) G = M / A (2) Rev = x x G x D / μv = 4 x x x M / (S x μv) (3) Rel = (1 - x) x G x D / μl = 4 x (1 - x) x M / (S x μl) (4)

[0051] In this case, the wetted perimeter length (S) of the first flow path 51a may be set to satisfy the following relational expression (5): ２ +Rel ２ ) ０．５ >5600 … (5)

[0052] That is, the cross section of the first flow path may have any shape as long as the wetted perimeter length (S) of the first flow path 51a satisfies the relational expression (5).

[0053] The second plate-shaped member 52 has a plurality of second flow paths 52a that split the refrigerant flowing through the first flow path 51a and flow in the second direction D2. As shown in FIGS. 3 and 4 , each of the plurality of second flow paths 52a is configured as a through-hole that penetrates between a pair of main surfaces 52b, 52c of the second plate-shaped member 52 in the second direction D2. The main surfaces 52b, 52c are main surfaces that constitute the second plate-shaped member 52. The main surface 52b contacts a contact surface 51c of the first plate-shaped member 51. The main surface 52c contacts a contact surface 53b of a third plate-shaped member 53 (described later). As indicated by arrows A52 in FIG. 4 , the refrigerant flowing through the first flow path 51a is split into a plurality of second flow paths 52a and flows through each second flow path 52a toward the third plate-shaped member 53 in the second direction D2.

[0054] In the second direction D2, one end of each second flow path 52a opens to a first flow path 51a of the first plate-shaped member 51, and the other end opens to a third flow path 53a of a third plate-shaped member 53 (described later). That is, the second flow path 52a connects the first flow path 51a and the third flow path 53a, and diverts the refrigerant flowing through the first flow path 51a and guides it to the third flow path 53a.

[0055] The shape of the second flow path cross section is not particularly limited. The second flow path cross section is a cross section of the second flow path 52a that is perpendicular to the flow direction of the refrigerant in the second flow path 52a. For example, the second flow path cross section can be any shape, such as a circle, an oval, an ellipse, a rectangle, or a square. In this embodiment, as an example, it is assumed that the second flow path cross section is a circle.

[0056] The plurality of second flow paths 52a are arranged in the first direction D1 in the same number as the plurality of heat transfer tubes 41 so as to correspond one-to-one with the plurality of heat transfer tubes 41. The cross-sectional centerline of each second flow path 52a (dotted line C52 shown in FIG. 4) coincides with the cross-sectional centerline of the corresponding heat transfer tube 41. The cross-sectional centerline of each second flow path 52a is a line passing through the center of the flow path cross section perpendicular to the refrigerant flow direction in the second flow path 52a. The cross-sectional centerline of each heat transfer tube 41 is a line passing through the center of the flow path cross section perpendicular to the refrigerant flow direction in the heat transfer tube 41. The centers of the flow path cross sections of the second flow paths 52a and the heat transfer tube 41 are the centers of circles if the cross sections are circular or elliptical, the intersection of the major and minor axes if the cross sections are elliptical, and the intersection of diagonals if the cross sections are rectangular or square.

[0057] The cross-sectional area of ​​the second flow passage 52a (hereinafter referred to as the second flow passage cross-sectional area) is larger for the second flow passage 52a located at the uppermost position in the first direction D1 (second flow passage 52au in the illustrated example) than for the second flow passage 52a located at the lowermost position in the first direction D1 (second flow passage 52al in the illustrated example). The second cross-sectional area is the cross-sectional area of ​​the second flow passage 52a perpendicular to the flow direction of the refrigerant in the second flow passage 52a (the direction indicated by arrow A52 in FIG. 4). For example, if the shape of the second flow passage cross-section is circular, the diameter of the second flow passage 52au is larger than the diameter of the second flow passage 52al.

[0058] Furthermore, for two second flow paths 52a adjacent to each other in the first direction D1, the second flow path cross-sectional area of ​​the upper second flow path 52a is equal to or greater than the second flow path cross-sectional area of ​​the lower second flow path 52a. In the illustrated example, the second flow path cross-sectional area is smaller for the second flow path 52a located lower in the first direction D1 and larger for the second flow path 52a located higher in the first direction D1. In other words, among the multiple second flow paths 52a, the second flow path 52a located higher in the first direction D1 has a larger second flow path area compared to the second flow path 52a located lower in the first direction D1. That is, the second flow path 52al has the smallest second flow path cross-sectional area, and the second flow path 52au has the largest second flow path cross-sectional area. For example, if the second flow path cross-sectional shape is circular, the second flow path 52al has the smallest diameter, and the second flow path 52au has the largest diameter.

[0059] However, the cross-sectional area of ​​the second flow path does not have to gradually increase from the lower second flow path 52 a to the upper second flow path 52 a in the first direction D1. Such an embodiment will be described later as a second embodiment.

[0060] The third plate-like member 53 has a flow path (hereinafter referred to as a third flow path) 53a that guides the refrigerant that has been diverted into the multiple second flow paths 52a to the heat transfer tubes 41 that correspond to the second flow paths 52a.

[0061] As shown by arrows A52 in Fig. 4, the refrigerant that has flowed through each second flow path 52a flows into the third flow path 53a. As shown by arrows A41 in Fig. 4, the refrigerant that has flowed into the third flow path 53a is guided from the third flow path 53a to the heat transfer tubes 41 connected to each of the plurality of second communication holes 55a.

[0062] 3 and 4 , the third flow path 53a is a hole (through-hole) that penetrates between a contact surface 53b of the third plate-shaped member 53 with the second plate-shaped member 52 and a contact surface 53c of the third plate-shaped member 53 with the fifth plate-shaped member 55. The contact surface 53b is the surface of the third plate-shaped member 53 that faces the second plate-shaped member 52 in the second direction D2. The contact surface 53c is the surface of the third plate-shaped member 53 that faces the fifth plate-shaped member 55 in the second direction D2. The contact surfaces 53b and 53c are main surfaces (principal surfaces) that constitute the third plate-shaped member 53. The third flow path 53a extends linearly in the first direction D1 and has both ends in the first direction D1 (an upper end 53d and a lower end 53e) that butt against each other.

[0063] The third flow path 53a is defined by an upper end 53d, a lower end 53e, and a pair of side ends 53f, 53g that surround the through hole. In other words, the third plate-shaped member 53 is configured as a frame having the upper end 53d, the lower end 53e, the pair of side ends 53f, 53g, and the third flow path 53a surrounded by these. By assembling the third plate-shaped member 53 with the second plate-shaped member 52 and the fifth plate-shaped member 55, the third flow path 53a forms a space closed by the upper end 53d, the lower end 53e, the pair of side ends 53f, 53g, and these plate-shaped members 52, 55. Thus, the third plate-shaped member 53 in the illustrated example is configured similarly to the first plate-shaped member 51.

[0064] The cross-sectional area of ​​the third flow path 53a (hereinafter referred to as the third flow path cross-sectional area) can be set arbitrarily. The third flow path cross-sectional area is the cross-sectional area of ​​the third flow path 53a perpendicular to the first direction D1. In the illustrated example, the third flow path cross-sectional area is set to be equal to the first flow path cross-sectional area of ​​the first flow path 51a. That is, like the first flow path cross-sectional area, the third flow path cross-sectional area is set to satisfy the range of Reynolds numbers that uniformly mix the gas-liquid two-phase refrigerant into gas and liquid.

[0065] The third flow path cross section may have any shape. As an example, similar to the first flow path cross section, there is no particular limitation as long as the above-mentioned Reynolds number range is satisfied. The first flow path cross section may have any shape, such as a rectangle, a square, a semicircle, a semi-oval, or a semi-ellipse. In this embodiment, as an example, it is assumed that the third flow path cross section is a rectangle similar to the first flow path cross section.

[0066] In the illustrated example, the third flow path cross-sectional area is constant over the entire length of the third flow path in the first direction D1. However, the third flow path cross-sectional area does not have to be constant over the entire length in this manner.

[0067] As described above, according to this embodiment, the header 43 (44, 45) is configured by stacking five plate-shaped members 50 (51 to 55). Of these, in the second plate-shaped member 52, the second flow paths 52a that split the refrigerant flowing through the first flow path 51a and flow in the second direction D2 have second flow paths 52a located higher in the first direction D1 that have larger second flow path areas than the second flow paths 52a located lower in the first direction D1. Therefore, the amount of refrigerant flowing through the second flow paths 52a located higher in the first direction D1 can be made larger than the amount of refrigerant flowing through the second flow paths 52a located lower in the first direction D1.

[0068] Therefore, more refrigerant is easily guided from the corresponding second flow paths 52a to the heat transfer tubes 41 located above the fourth plate-shaped member 54 than to the heat transfer tubes 41 located below the fourth plate-shaped member 54 in the first direction D1. For example, when the refrigeration cycle apparatus 1 is in heating operation and the outdoor heat exchanger 4 functions as an evaporator, a gas-liquid two-phase refrigerant flows into the outdoor heat exchanger 4. At this time, the gas-liquid two-phase refrigerant flows into the first flow paths 51a from the pipe 46 connected to the first communication hole 54a located below the fourth plate-shaped member 54 in the first direction D1. Because the refrigerant that flows into the first flow paths 51a flows upward against gravity, it is difficult to evenly distribute the refrigerant to the multiple second flow paths 52a.

[0069] However, according to the present embodiment, even when gas-liquid two-phase refrigerant flows into the first flow path 51a from below in the first direction D1, the amount of refrigerant flowing through the second flow paths 52a located higher than that flowing through the second flow paths 52a can be made larger. This allows the refrigerant to be uniformly guided to the heat transfer tubes 41 corresponding to each of the second flow paths 52a. In other words, the amount of refrigerant flowing through the heat transfer tubes 41 can be made uniform. As a result, the efficiency of heat exchange of the refrigerant in the outdoor heat exchanger 4 can be improved.

[0070] Furthermore, since gas phase refrigerant is lighter than liquid phase refrigerant, the gas-liquid ratio of the gas-liquid two-phase refrigerant that flows into the first flow path 51a tends to be higher in the upper part of the first direction D1 and higher in the lower part.

[0071] However, according to this embodiment, the first flow path cross-sectional area of ​​the first flow path 51a is set to satisfy the Reynolds number range for uniformly mixing the gas-liquid two-phase refrigerant. Therefore, the gas-liquid ratio of the gas-liquid two-phase refrigerant can be uniformed in the first direction D1 along the first flow path 51a. This allows the gas-liquid two-phase refrigerant to be diverted to each of the second flow paths 52a without biasing the gas-liquid ratio. Furthermore, the gas-liquid ratio of the gas-liquid two-phase refrigerant can also be appropriately uniformed in the third flow path 53a. Therefore, the refrigerant can be guided to the heat transfer tubes 41 corresponding to each of the second flow paths 52a at a uniform gas-liquid ratio. That is, the gas-liquid ratio of the refrigerant flowing through the heat transfer tubes 41 can be uniformed. As a result, the heat exchange efficiency of the refrigerant in the outdoor heat exchanger 4 can be improved.

[0072] Therefore, according to this embodiment, it is possible to achieve uniformity in the flow rate and gas-liquid ratio of the refrigerant diverted from the header 44 to the plurality of heat transfer tubes 41. Such uniformity in the flow rate and gas-liquid ratio of the refrigerant can be achieved simply by the header 44, which is formed by stacking predetermined plate-like members 50 (51 to 55). In other words, it is not necessary to provide a distributor, for example, to cause the refrigerant to flow into the header 44, and it is possible to more easily achieve uniformity in the flow rate and gas-liquid ratio of the refrigerant diverted from the header 44 to the plurality of heat transfer tubes 41 while saving space.

[0073] The configuration of the header 43 (header 44 in this embodiment, as an example) serving as the first header into which the refrigerant flows from the refrigerant inlet pipe is not limited to that of the first embodiment. For example, other configurations such as those shown in FIGS. 5 to 8 can also achieve the same effects as those of the first embodiment. These embodiments will be described below as a second embodiment and a third embodiment. The configuration of the refrigeration cycle apparatus in the second and third embodiments is the same as that of the refrigeration cycle apparatus 1 ( FIG. 1 ) according to the first embodiment, and the configuration of the outdoor heat exchanger other than the header is the same as that of the outdoor heat exchanger 4 ( FIG. 2 ) according to the first embodiment. Therefore, in the second and third embodiments, the configuration other than the header will be referred to as appropriate in the first embodiment ( FIGS. 1 to 4 ), and a description thereof will be omitted. The basic configuration of the header is the same as that of the header 44 according to the first embodiment, and the same or similar components will be denoted by the same reference numerals in the drawings and will not be described.

[0074] Second Embodiment Figures 5 and 6 show the header configuration of an outdoor heat exchanger 4 according to a second embodiment. Figure 5 is an exploded perspective view showing a schematic configuration of the header of the outdoor heat exchanger 4. Figure 6 is a cross-sectional view showing a schematic view of the header configuration of the outdoor heat exchanger 4 according to the second embodiment, taken from the direction of the arrow, at a location equivalent to the location indicated by arrow A2 in Figure 2.

[0075] As shown in Figures 5 and 6, the header 44b according to this embodiment is configured by stacking five plate-shaped members 50 (a first plate-shaped member 61, a second plate-shaped member 62, a third plate-shaped member 63, a fourth plate-shaped member 64, and a fifth plate-shaped member 65), similar to the header 44 according to the first embodiment. The first plate-shaped member 61 has a configuration similar to that of the first plate-shaped member 51. The second plate-shaped member 62 has a configuration similar to that of the second plate-shaped member 52, except for the second flow path cross-sectional area of ​​the second flow path 62a. The third plate-shaped member 63 has a configuration similar to that of the third plate-shaped member 53. The fourth plate-shaped member 64 has a configuration similar to that of the fourth plate-shaped member 54. And the fifth plate-shaped member 65 has a configuration similar to that of the fifth plate-shaped member 55.

[0076] As shown in Figures 5 and 6, each of the multiple second flow paths 62a is configured as a through-hole penetrating between the pair of main surfaces 52b, 52c of the second plate-shaped member 62 in the second direction D2, similar to the second flow paths 52a of the first embodiment. The cross-sectional centerline of each second flow path 62a (dotted line C62 shown in Figure 6) coincides with the cross-sectional centerline of the corresponding heat transfer tube 41. The cross-sectional centerline of the second flow path 62a is a line passing through the center of the flow path cross-section perpendicular to the refrigerant flow direction in the second flow path 62a. The center of the flow path cross-section of the second flow path 62a and the heat transfer tube 41 is the center of a circle if the cross-sectional shape of these flow paths is circular or elliptical, the intersection of the major axis and minor axis if the cross-sectional shape is elliptical, or the intersection of diagonals if the cross-sectional shape is rectangular or square.

[0077] Unlike the first embodiment, in this embodiment, the second flow path cross-sectional area of ​​the second flow paths 62a does not gradually increase from the lower second flow paths 62a to the upper second flow paths 62a in the first direction D1, but is the same for the intermediate second flow paths 62a. The second flow path cross-sectional area is the cross-sectional area of ​​the second flow paths 62a perpendicular to the refrigerant flow direction in the second flow paths 62a (the direction indicated by arrow A62 in FIG. 6). Here, the intermediate position in the first direction D1 refers to, for example, a middle position in the first direction D1, the middle position or its vicinity, or a position other than the lowest or highest position.

[0078] In the illustrated example, the second flow path cross-sectional area is smallest for the second flow path 62al located at the bottom in the first direction D1 and largest for the second flow path 62au located at the top. Furthermore, from the second flow path 62al to the second flow path 62au, every two adjacent second flow paths 62a in the first direction D1 are grouped into a set. In the illustrated example, the eight second flow paths 62a are divided into four sets G61, G62, G63, and G64, each consisting of two second flow paths 62a. The second flow path cross-sectional areas of the two second flow paths 62a in each set are the same. The second flow path cross-sectional areas of the second flow paths 62a in each set gradually increase from the lower set to the upper set in the first direction D1. That is, the second flow path cross-sectional area is smallest for the second flow paths 62al, 62a of the set G64 located at the lowest in the first direction D1, followed by the second flow paths 62a, 62a of the set G63 and the second flow paths 62a, 62a of the set G62, and is largest for the second flow paths 62au, 62a of the set G61 located at the highest.

[0079] The number of groups into which the multiple second flow paths 62a are divided is not particularly limited and may be any number. Furthermore, the number of second flow paths 62a in each group does not have to be uniform, and may be different in all or some of the groups. That is, for two second flow paths 62a adjacent to each other vertically in the first direction D1, the second flow path cross-sectional area of ​​the upper second flow path 62a may be equal to or greater than the second flow path cross-sectional area of ​​the lower second flow path 62a. In this case, second flow paths 62a having the same second flow path cross-sectional area are considered to be in the same group.

[0080] For example, depending on the number of heat transfer tubes 41 to which the refrigerant is diverted from the header 44b, it is possible to equalize the amount of refrigerant flowing through the plurality of heat transfer tubes 41 even if the second flow passages 62a in each intermediate set are made the same rather than gradually increasing from the lower second flow passages 62a to the upper second flow passages 62a in the first direction D1. As an example, as in this embodiment, the second flow passage cross-sectional area of ​​the second flow passages 62al is smallest, the second flow passage cross-sectional area of ​​the second flow passages 62au is largest, and the second flow passage cross-sectional area is gradually increased from the lower set to the upper set in the first direction D1, thereby making it possible to equalize the flow rate of the refrigerant flowing through the plurality of heat transfer tubes 41.

[0081] Therefore, the flow rate and the gas-liquid ratio of the refrigerant diverted from the header 44b to the plurality of heat transfer tubes 41 can be made uniform while saving space even more easily.

[0082] 7 and 8 show the header configuration of an outdoor heat exchanger 4 according to a third embodiment. Fig. 7 is an exploded perspective view showing a schematic configuration of the header of the outdoor heat exchanger 4. Fig. 8 is a cross-sectional view showing a schematic view of the header configuration of the outdoor heat exchanger 4 according to the third embodiment, taken from the direction of the arrow, at a location equivalent to the location indicated by arrow A2 in Fig. 2.

[0083] 7 and 8 , the header 44c according to this embodiment is configured by stacking five plate-shaped members 50 (a first plate-shaped member 71, a second plate-shaped member 72, a third plate-shaped member 73, a fourth plate-shaped member 74, and a fifth plate-shaped member 75), similar to the header 44 according to the first embodiment. The first plate-shaped member 71 has a configuration similar to that of the first plate-shaped member 51, except for the first flow path cross-sectional area of ​​the first flow path 71a. The second plate-shaped member 72 has a configuration similar to that of the second plate-shaped member 62. The third plate-shaped member 73 has a configuration similar to that of the third plate-shaped member 53. The fourth plate-shaped member 74 has a configuration similar to that of the fourth plate-shaped member 54. The fifth plate-shaped member 75 has a configuration similar to that of the fifth plate-shaped member 55.

[0084] In the present embodiment, unlike the first embodiment, the second flow path cross-sectional areas of the second flow paths 62 a do not gradually increase from the lower second flow path 62 a to the upper second flow path 62 a in the first direction D1, as in the second embodiment. As an example, in the present embodiment, as in the second embodiment, the second flow path cross-sectional areas of the two second flow paths 62 a in the same set are the same, and the second flow path cross-sectional areas of the second flow paths 62 a in each set gradually increase from the lower set to the upper set in the first direction D1.

[0085] 7 and 8, the first flow path 71a is a hole (through-hole) that penetrates between a contact surface 71b of the first plate-shaped member 71 with the fourth plate-shaped member 74 and a contact surface 71c of the first plate-shaped member 71 with the second plate-shaped member 72. The contact surface 71b is the surface of the first plate-shaped member 71 that faces the fourth plate-shaped member 74 in the second direction D2. The contact surface 71c is the surface of the first plate-shaped member 71 that faces the second plate-shaped member 72 in the second direction D2. The contact surfaces 71b and 71c are main surfaces (principal surfaces) that constitute the first plate-shaped member 71. The first flow path 71a extends linearly in the first direction D1 and has both ends in the first direction D1 (an upper end 71d and a lower end 71e) that butt against each other.

[0086] The first flow path 71a is defined by an upper end 71d, a lower end 71e, and a pair of side ends 71f, 71g that surround the through hole. In other words, the first plate-shaped member 71 is configured as a frame having the upper end 71d, the lower end 71e, the pair of side ends 71f, 71g, and the first flow path 71a surrounded by these. When the first plate-shaped member 71 is assembled with the fourth plate-shaped member 74 and the second plate-shaped member 72, the first flow path 71a forms a space closed by the upper end 71d, the lower end 71e, the pair of side ends 71f, 71g, and these plate-shaped members 74, 72.

[0087] The first flow path cross-sectional area is the cross-sectional area of ​​the first flow path 71a perpendicular to the flow direction of the refrigerant in the first flow path 71a (the direction indicated by arrow A71 in FIG. 8 (upward in the first direction D1)). In the illustrated example, unlike the first flow paths 51a and 61a of the first and second embodiments, the first flow path cross-sectional area is not constant over the entire length, but gradually increases from below to above in the first direction D1. However, the first flow path cross-sectional area of ​​the first flow path 71a does not have to gradually increase as in the illustrated example, and may, for example, increase in stages from below to above in the first direction D1.

[0088] Even if the first flow path cross-sectional area of ​​the first flow path 71a increases from bottom to top, the first flow path cross-sectional area is set to satisfy the range of Reynolds numbers that uniformly mixes the gas-liquid two-phase refrigerant into gas and liquid, as in the first embodiment.

[0089] This makes it easier to equalize the gas-liquid ratio of the gas-liquid two-phase refrigerant immediately after it flows into the first flow path 71a from below in the first direction D1. This makes it possible to more appropriately equalize the gas-liquid ratio of the gas-liquid two-phase refrigerant between above and below in the first direction D1 in the first flow path 71a.

[0090] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0091] DESCRIPTION OF SYMBOLS 1... Refrigeration cycle device, 2... Compressor, 2a... Compressor body, 2b... Accumulator, 3... Four-way valve, 4... Outdoor heat exchanger, 5... Expansion valve, 6... Indoor heat exchanger, 7... Refrigerant flow path, 8... Outdoor blower, 8a... Fan, 8b... Fan motor, 9... Indoor blower, 11... Outdoor unit, 12... Indoor unit, 21... Housing, 21a... Bottom plate, 21b, 21c... Side plates, 21d... Back plate, 21e... Partition plate, 21f... Mounting piece, 21g, 21h... Open Port, 210b, 210d, 210c, 211b...end portion, 41...heat transfer tube, 41a...flow path, 42...fin, 42a...slit, 43, 44, 44b, 44c, 45...header, 46...piping (refrigerant inlet pipe), 47...piping (refrigerant outlet pipe), 50...plate-like member, 51, 61, 71...first plate-like member, 51a, 71a...first flow path, 51b, 71b...contact surface, 51c, 71c...contact surface, 51d, 71d...upper end portion, 51e, 7 1e...lower end portion, 51f, 51g, 71f, 71g...side end portions, 52, 62, 72...second plate-shaped member, 52a, 52al, 52au, 62a, 62al, 62au...second flow paths, 52b, 52c...main surface of second plate-shaped member, 53, 63, 73...third plate-shaped member, 53a, 73a...third flow path, 53b...contact surface, 53c...contact surface, 53d...upper end portion, 53e...lower end portion, 53f, 53g...side end portions, 54, 64, 74...fourth plate-shaped member, 54a...hole portion (first communication hole), 55, 65, 75...fifth plate-shaped member, 55a...hole portion (second communication hole), A41...direction of refrigerant flow through heat transfer tube, A46...direction of refrigerant flow through piping (refrigerant inlet pipe), A51, A71...direction of refrigerant flow through first flow path, A52, A62...direction of refrigerant flow through second flow path, C52, C62...cross-sectional center line of second flow path, G61, G62, G63, G64...set of second flow paths.

Claims

1. A heat transfer tube comprising: a plurality of heat transfer tubes arranged at intervals in a first direction along a vertical line and extending in a second direction perpendicular to the first direction, through which a refrigerant flows; a plurality of fins arranged at intervals in the second direction and extending in the first direction; and a pair of headers having a flow path through which the refrigerant flows, standing in the first direction and connected to both ends of the plurality of heat transfer tubes in the second direction, wherein the pair of headers are formed by stacking a plurality of plate-like members parallel to a plane defined by the first direction and a third direction perpendicular to both the first direction and the second direction, the pair of headers comprising a first header to which an inlet pipe of the refrigerant is connected and a second header to which an outlet pipe of the refrigerant is connected, the first header comprising: a first plate-like member having a first flow path through which the refrigerant flowing in from the inlet pipe flows in the first direction; and a second plate-like member having a plurality of second flow paths through which the refrigerant flowing in the first flow path is split and flows in the second direction, a second flow path cross-sectional area, which is a cross-sectional area of ​​the second flow path perpendicular to the flow direction of the refrigerant, is larger in the second flow path located at the uppermost position in the first direction than in the second flow path located at the lowermost position in the first direction, and in two second flow paths adjacent to each other in the vertical direction, the second flow path cross-sectional area of ​​the upper second flow path is equal to or larger than the second flow path cross-sectional area of ​​the lower second flow path.

2. The heat exchanger according to claim 1, wherein a first flow path cross-sectional area, which is a cross-sectional area of ​​the first flow path perpendicular to the flow direction of the refrigerant, is set to satisfy a range of Reynolds numbers that uniformly mix the refrigerant flowing in from the inlet pipe into gas and liquid.

3. When the wetted perimeter length of the first flow path is S, the cross-sectional area of ​​the first flow path is A, the vapor quality of the refrigerant at the inlet pipe is x, the viscosity coefficient of the vapor at the inlet pipe is μv, the viscosity coefficient of the liquid at the inlet pipe is μl, and the mass flow rate of the refrigerant at the bottom of the first flow path in the first direction is M, then D = 4 x A / S, G = M / A, Rev = x x G x D / μv = 4 x x x M / (S x μv), Rel = (1-x) x G x D / μl = 4 x (1-x) x M / (S x μl), the wetted perimeter length (S) of the first flow path is given by: (Rev ２ +Re ２ ) ０．５ The heat exchanger according to claim 2 , which satisfies the following relationship:

4. A heat exchanger as claimed in claim 2, wherein the first flow passage cross-sectional area is constant over the entire length of the first flow passage in the first direction, or increases from the bottom to the top in the first direction.

5. A heat exchanger as claimed in any one of claims 1 to 4, wherein the cross-sectional area of ​​the second flow paths is larger for the second flow paths located higher in the first direction compared to the second flow paths located lower in the first direction.

6. A heat exchanger as described in claim 5, wherein the second flow paths are arranged in the first direction in a one-to-one correspondence with the heat transfer tubes, and the number of the second flow paths is the same as the number of the heat transfer tubes, and a line passing through the center of a cross section perpendicular to the flow direction of the refrigerant in each of the second flow paths coincides with a line passing through the center of a cross section of the corresponding heat transfer tube perpendicular to the flow direction of the refrigerant.

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