Heat exchanger and air conditioner equipped therewith

Abstract

To provide a heat exchanger which can suppress a decrease in heat exchange amount of the heat exchanger, and an air conditioner having the same.SOLUTION: An air conditioner of one embodiment of the present invention comprises a first heat exchange part having a plurality of first flat pipes which are arranged in a vertical direction, a second heat exchange part having a plurality of second flat pipes which are arranged in the vertical direction, and a wrap header whose inside is partitioned by a plurality of space parts. In the plurality of first flat pipes and the plurality of second flat pipes, a plurality of refrigerant flow passages extending in a fore-and-aft direction are formed while being aligned in a left-and-right direction. The first heat exchange part and the second heat exchange part are aligned in parallel with each other in the left-and-right direction. One first flat pipe out of the plurality of first flat pipes and one second flat pipe out of the plurality of second flat pipes are connected to one space part out of the plurality of space parts, and a first buffer part is arranged between the first flat pipe and the second flat pipe in the space part.SELECTED DRAWING: Figure 18

Description

Technical Field

[0001] The present invention relates to a heat exchanger and an air conditioner equipped with the same.

Background Art

[0002] There is known a heat exchanger in which a plurality of stages of flat tubes arranged in the vertical direction are arranged in two rows in the air flow direction, and a folding header for folding the refrigerant flow direction between columns is provided at one end of each row of flat tubes (see, for example, Patent Document 1).

[0003] Further, there is known a heat exchanger having a folding header including a first plate through which one end of each flat tube penetrates and a second plate joined to the first plate (see, for example, Patent Document 2). In this heat exchanger, a space portion is formed in which the first plate and the second plate are joined to communicate the ends of each row of flat tubes with each other, and an arch-shaped recess for partitioning this space portion is formed in the second plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Inside each flattened tube, multiple rows of refrigerant flow paths are formed, arranged in the direction of airflow. Therefore, in a heat exchanger using flattened tubes as heat transfer tubes, the amount of heat exchange between air and refrigerant is greater on the windward side than on the leeward side due to the greater airflow between the refrigerant flow paths inside each flattened tube. For this reason, during both cooling and heating operations, it is preferable that more of the refrigerant to be phase-changed flows through the windward refrigerant flow paths, where the amount of heat exchange is greater, than through the leeward refrigerant flow paths.

[0006] Furthermore, in air conditioners that employ a heat exchanger consisting of multiple rows of flat tubes arranged in the direction of airflow, either as an outdoor or indoor heat exchanger, the refrigerant flowing out of the heat exchanger, which functions as an evaporator, is usually compressed by the compressor and then first flows into the flat tubes in the leeward row of the heat exchanger, which functions as a condenser. The reason for this is that when the heat exchanger functions as a condenser, if the flat tube into which the refrigerant discharged from the compressor first flows is set to the leeward flat tube, the air heated by heat exchange with the refrigerant flowing in the leeward flat tube flows into the leeward flat tube. As a result, the temperature difference between the refrigerant flowing in the leeward flat tube and the air becomes smaller, and the amount of heat exchange decreases. Meanwhile, the refrigerant flowing out of the heat exchanger, which functions as a condenser, is depressurized by the expansion valve and then first flows into the flattened tubes in the upwind row of the heat exchanger, which functions as an evaporator.

[0007] In the above air conditioner, the refrigerant flowing into the flat tubes of one row of the heat exchanger is reversed and directed back by the return header before flowing into the flat tubes of the other row. When the refrigerant flowing into the return header is in a gas-liquid two-phase state, the liquid refrigerant, which has a higher specific gravity than the gaseous refrigerant, is more strongly affected by the inertial force during reversal and is more likely to be swung outwards. As a result, when the heat exchanger functions as a condenser, the return header causes more gaseous refrigerant to flow into the leeward refrigerant channel, i.e., the refrigerant channel with a smaller heat exchange rate, among the multiple refrigerant channels in the flat tubes of the upwind row. Similarly, when the heat exchanger functions as an evaporator, the return header causes more liquid refrigerant to flow into the leeward refrigerant channel, i.e., the refrigerant channel with a smaller heat exchange rate, among the refrigerant channels of the flat tubes of the downwind row. Thus, when the heat exchanger functions as an evaporator, the refrigerant that is to undergo phase change flows more into the leeward refrigerant channel with a smaller heat exchange rate, rather than the upwind refrigerant channel with a larger heat exchange rate, resulting in a problem of reduced heat exchange in the heat exchanger.

[0008] In view of the above circumstances, the object of the present invention is to provide a heat exchanger that can suppress the reduction in the amount of heat exchanged in the heat exchanger, and an air conditioner equipped therewith. [Means for solving the problem]

[0009] An air conditioner according to one embodiment of the present invention is A first heat exchange section having a plurality of first flattened tubes arranged in the vertical direction, A second heat exchange section having a plurality of second flattened tubes arranged in the vertical direction, It comprises a folded header whose interior is divided into multiple spatial sections, Multiple refrigerant flow paths extending in the front-to-back direction are formed inside each of the multiple first flattened tubes and the multiple second flattened tubes, arranged in the left-to-right direction. The first heat exchange section and the second heat exchange section are arranged side by side in the left-right direction. One of the plurality of first flattened tubes and one of the plurality of second flattened tubes are connected to one of the plurality of spaces. A first buffer is provided between the first flattened pipe and the second flattened pipe in the aforementioned space.

[0010] The first buffer portion may be formed to resist the flow of refrigerant between the first flattened pipe and the second flattened pipe in the space.

[0011] The first buffer section may include a collision section that obstructs the flow of refrigerant between the first flattened pipe and the second flattened pipe, a first flow passage for liquid refrigerant between the first flattened pipe and the second flattened pipe, and a second flow passage for gaseous refrigerant between the first flattened pipe and the second flattened pipe.

[0012] Each of the aforementioned spatial portions has a first inner surface portion connected to the first flattened pipe and the second flattened pipe, a second inner surface portion facing the first inner surface portion, and a top surface portion and a bottom surface portion facing each other in the vertical direction. The collision portion may have a first wall portion formed between the top portion and the bottom portion, and a second wall portion of a predetermined height formed between the first wall portion and the first inner surface portion.

[0013] The first wall portion is positioned away from the second inner surface portion, The second wall portion may be positioned between the bottom portion and the first flattened tube and the second flattened tube.

[0014] The predetermined height may be greater than or equal to the height from the bottom surface to the connection point between the first flattened pipe and the second flattened pipe in the first inner surface.

[0015] A second buffer portion may be provided between the first buffer portion and the first flattened pipe or the second flattened pipe.

[0016] In the plurality of spaces, the second buffer portion may be provided on the second inner surface so as to face the first flow passage in the left-right direction. [Effects of the Invention]

[0017] According to the present invention, it is possible to suppress a decrease in the heat exchange amount in the heat exchanger.

Brief Description of the Drawings

[0018] [Figure 1] It is a refrigerant circuit diagram showing the configuration of an air conditioner. [Figure 2] It is a perspective view showing a heat exchanger according to an embodiment of the present invention. [Figure 3] It is a schematic cross-sectional perspective view showing the internal structure of a flat tube in the heat exchanger. [Figure 4] It is a partial perspective view of a folding header in a heat exchanger according to an embodiment of the present invention. [Figure 5] It is a partial perspective view of an intermediate plate constituting the folding header. [Figure 6] It is a perspective view of a main part showing the internal structure of the folding header. [Figure 7] It is a side cross-sectional view of a main part of the folding header. [Figure 8] It is a front view showing the opening shapes of the first plate member (A), the second plate member (B), and the third plate member (C) constituting the intermediate plate. [Figure 9] It is a front view of the through holes of the intermediate plate as viewed from the side of the first plate member. [Figure 10] It is a front view of the through holes of the intermediate plate as viewed from the side of the third plate member. [[ID=TY]] [Figure 11] It is a cross-sectional view taken along line A-A in FIG. 10. [Figure 12] It is a perspective view for explaining the flow of refrigerant when the heat exchanger functions as a condenser. [Figure 13] It is a perspective view for explaining the flow of refrigerant when the heat exchanger functions as an evaporator. [Figure 14] It is an explanatory diagram showing the shape of the space part of the folding header in a conventional heat exchanger, and is a cross-sectional view of the main part as viewed from the longitudinal direction of the flat tube. [Figure 15]This is an explanatory diagram showing the shape of the space in the folded header of a conventional heat exchanger, and is a cross-sectional view of the main part as seen from the thickness direction of the flattened tube. [Figure 16] This is a cross-sectional view of the main part of a conventional heat exchanger, illustrating the behavior of the refrigerant within the folded header, and is a cross-sectional view of the main part as seen from the longitudinal direction of the flattened tube. [Figure 17] This is a cross-sectional view of a key part illustrating the behavior of the refrigerant in the folded header of a conventional heat exchanger, and is a cross-sectional view of the key part as seen from the thickness direction of the flattened tube. [Figure 18] This is a cross-sectional view of the main part illustrating the behavior of the refrigerant in the folded header when the heat exchanger of the embodiment functions as a condenser, where (A) is a cross-sectional view of the main part viewed from the longitudinal direction of the flattened tube, and (B) is a cross-sectional view of the main part viewed from the thickness direction of the flattened tube. [Figure 19] This is a cross-sectional view of the main part illustrating the behavior of the refrigerant in the folded header when the heat exchanger of the embodiment functions as an evaporator, where (A) is a cross-sectional view of the main part viewed from the longitudinal direction of the flattened tube, and (B) is a cross-sectional view of the main part viewed from the thickness direction of the flattened tube. [Modes for carrying out the invention]

[0019] Embodiments of the present invention will be described below with reference to the drawings.

[0020] Figure 1 is a refrigerant circuit diagram showing the configuration of an air conditioner 1 to which a heat exchanger according to one embodiment of the present invention is applied. The air conditioner 1 will be described in general terms below.

[0021] [Air conditioner] As shown in Figure 1, the air conditioner 1 comprises an indoor unit 2 and an outdoor unit 3. The indoor unit 2 is equipped with an indoor heat exchanger 4, and the outdoor unit 3 is equipped with an outdoor heat exchanger 5, as well as a compressor 6, an expansion valve 7, and a four-way valve 8.

[0022] During heating operation, in Figure 1, the four-way valve 8 switches to the state shown by the solid line, and the refrigerant flows in the direction of the black arrow. The gaseous refrigerant discharged from the compressor 6 of the outdoor unit 3 flows through piping P1, the four-way valve 8, and piping P2 and flows into the indoor heat exchanger 4. During heating operation, the indoor heat exchanger 4 functions as a condenser, and the refrigerant that has exchanged heat with the indoor air condenses and liquefies. The liquid refrigerant then flows through piping P3, passes through the expansion valve 7 of the outdoor unit 3, is depressurized to become a gaseous two-phase refrigerant, and flows through piping P4 and flows into the outdoor heat exchanger 5. During heating operation, the outdoor heat exchanger 5 functions as an evaporator, and the refrigerant that has exchanged heat with the outside air gasifies. The gaseous refrigerant then flows through piping P5, the four-way valve 8, and piping P6 and is drawn into the compressor 6.

[0023] During cooling operation, the four-way valve 8 in Figure 1 switches to the state shown by the dashed line, and the refrigerant flows in the direction of the white arrow. The gaseous refrigerant discharged from the compressor 6 of the outdoor unit 3 flows through piping P1, the four-way valve 8, and piping P5 and flows into the outdoor heat exchanger 5. During cooling operation, the outdoor heat exchanger 5 functions as a condenser, and the refrigerant that has exchanged heat with the outside air condenses and liquefies. The liquid refrigerant then flows through piping P4, passes through the expansion valve 7 of the outdoor unit 3, is depressurized to become a gaseous two-phase refrigerant, and flows through piping P3 and flows into the indoor heat exchanger 4. During cooling operation, the indoor heat exchanger 4 functions as an evaporator, and the refrigerant that has exchanged heat with the indoor air gasifies. The gaseous refrigerant then flows through piping P2, the four-way valve 8, and piping P6 and is drawn into the compressor 6.

[0024] [Heat exchanger] The indoor heat exchanger 4 and the outdoor heat exchanger 5 are composed of heat exchangers with the structure shown in Figure 2. Figure 2 is a perspective view showing a heat exchanger 100 according to one embodiment of the present invention. In the figure, the X, Y, and Z axes represent three mutually orthogonal axes, with the X axis corresponding to the left-right direction, the Y axis corresponding to the front-back direction, and the Z axis corresponding to the up-down direction. Arrow A indicates the direction of airflow parallel to the X axis. The airflow is formed by the indoor fan 4F positioned opposite the indoor heat exchanger 4 and the outdoor fan 5F positioned opposite the outdoor heat exchanger 5 (see Figure 1). The following describes the details of the heat exchanger 100.

[0025] The heat exchanger 100 comprises a first heat exchange section 10, a second heat exchange section 20, a first header 30, a second header 40, and a folded header 50. The first heat exchange section 10 and the second heat exchange section 20 of the heat exchanger 100 are arranged side by side in the left-right direction (X-axis direction), which is the direction of airflow, and in this embodiment, the first heat exchange section 10 is located downwind of the second heat exchange section 20.

[0026] (1st heat exchange section, 2nd heat exchange section) The first heat exchange section 10 has first flattened tubes 11 arranged in multiple stages with spacing in the vertical direction (Z-axis direction). Each first flattened tube 11 is a metal heat transfer tube having a width direction in the X-axis direction, a length direction in the Y-axis direction, and a thickness direction in the Z-axis direction.

[0027] Inside the first flattened tube 11, as shown in Figure 3, there are multiple refrigerant flow paths 11p arranged along the width direction. Each first flattened tube 11 is positioned so that the multiple refrigerant flow paths 11p intersect with the airflow indicated by arrow A in Figure 2, thereby allowing heat exchange between the air passing between each first flattened tube 11 and the refrigerant flowing through each refrigerant flow path 11p. The number of first flattened tubes 11 is not particularly limited, and in the illustrated example there are 14.

[0028] Although not shown in Figure 2, the first heat exchange section 10 further includes a plurality of heat transfer fins attached to the plurality of first flattened tubes 11. The plurality of heat transfer fins may be plate-shaped fins perpendicular to the plurality of first flattened tubes 11, or they may be corrugated fins (wavy fins) arranged between the plurality of first flattened tubes 11.

[0029] The second heat exchange section 20 has a multi-stage arrangement of second flattened tubes 21 spaced apart in the vertical direction. Each second flattened tube 21, like the first flattened tube 11, is a metal heat transfer tube with a width in the X-axis direction, a length in the Y-axis direction, and a thickness in the Z-axis direction, and is positioned opposite each first flattened tube 11 in the left-right direction (X-axis direction), which is the direction of airflow.

[0030] Inside the second flattened tube 21, as shown in Figure 3, there are multiple refrigerant flow paths 21p arranged along the width direction. Each first flattened tube 21 is positioned so that the multiple refrigerant flow paths 21p intersect with the airflow indicated by arrow A in Figure 2, thereby allowing heat exchange between the air passing between each second flattened tube 21 and the refrigerant flowing through each refrigerant flow path 21p. The number of second flattened tubes 21 is the same as the number of first flattened tubes 11, which is 14.

[0031] Similarly, the second heat exchange section 20 further has a plurality of heat transfer fins attached to a plurality of second flattened tubes 21. The plurality of heat transfer fins may be plate-shaped fins perpendicular to the plurality of second flattened tubes 21, or they may be corrugated fins (corrugated fins) arranged between the plurality of second flattened tubes 21.

[0032] (First header, second header) The first header 30 is used to divert the refrigerant to each first flat pipe 11, or to merge the refrigerant that has flowed out of each first flat pipe 11, and is connected to one end of each first flat pipe 11 in the longitudinal direction (the right side in Figure 2). The first header 30 has a cylindrical header pipe 31 that extends in the vertical direction and a plurality of partition plates 32 arranged inside the header pipe 31.

[0033] The multiple partition plates 32 divide the inside of the header pipe 31 into six spaces S11 to S16 from top to bottom. In the example in Figure 2, two first flat pipes 11 are connected to spaces S11, S14 to S16, and three first flat pipes 11 are connected to spaces S12 and S13. As a result, the set of first flat pipes 11 is divided into six flow distribution lines 11a to 11f, each consisting of two or three first flat pipes 11, depending on the space to which it is connected.

[0034] The number of spaces S11 to S16 is not limited to the above example and can be arbitrarily determined according to the number of first flattened pipes 11, etc. Also, the number of first flattened pipes 11 connected to each space S11 to S16 is not limited to the above example and may be connected to each space in equal numbers depending on the number of first flattened pipes 11.

[0035] The second header 40 is used to divert the refrigerant to each second flat pipe 21, or to combine the refrigerant that has flowed out of each second flat pipe 21, and is connected to one end of each second flat pipe 21 in the longitudinal direction (the right side in Figure 2). The second header 40 has a cylindrical header pipe 41 that extends in the vertical direction and a plurality of partition plates 42 arranged inside the header pipe 41.

[0036] The multiple partition plates 42 divide the inside of the header pipe 41 into six spaces S21 to S26 from top to bottom. Although not shown in Figure 2, two second flat pipes 21 are connected to spaces S21, S24 to S26, and three second flat pipes 21 are connected to spaces S22 and S23. As a result, each set of second flat pipes 21 is divided into six flow distribution lines consisting of two or three second flat pipes 21, depending on the space to which they are connected. These six flow distribution lines correspond to the six flow distribution lines 11a to 11f of the first heat exchange section 10 in terms of position and the number of flat pipes, respectively.

[0037] Similar to the first header 30, the number of spaces S21 to S26 in the second header 40 is not limited to the above example and can be arbitrarily determined according to the number of second flattened pipes 21, etc. The number of second flattened pipes 21 connected to each space S21 to S26 is also not limited to the above example and may be connected in equal numbers to each space depending on the number of second flattened pipes 21.

[0038] Refrigerant supply and discharge pipes 33 are installed in the three upper spaces S11 to S13 of the first header 30. Each supply and discharge pipe 33 is connected to piping P2 that connects to the four-way valve 8 when the heat exchanger 100 is used as an indoor heat exchanger 4, and to piping P5 that connects to the four-way valve 8 when the heat exchanger 100 is used as an outdoor heat exchanger 5.

[0039] Meanwhile, refrigerant supply and discharge pipes 43 are installed in the three lower spaces S24 to S26 of the second header 40. Each supply and discharge pipe 43 is connected to a pipe P3 that connects to the expansion valve 7 when the heat exchanger 100 is used as an indoor heat exchanger 4, and to a pipe P4 that connects to the expansion valve 7 when the heat exchanger 100 is used as an outdoor heat exchanger 5.

[0040] Meanwhile, connecting pipes 34 to 36 are connected to the three lower spaces S14 to S16 of the first header 30 and the three upper spaces S21 to S23 of the second header 40, respectively. Connecting pipe 34 connects space S14 of the first header 30 and space S21 of the second header 40. Connecting pipe 34 connects space S15 of the first header 30 and space S22 of the second header 40. Connecting pipe 35 connects space S16 of the first header 30 and space S23 of the second header 40.

[0041] (Wrap header) Figure 4 is a partial perspective view of the folded header 50 as seen from the side where the first header 30 and the second header 40 are located. The folded header 50 is used to fold back and reverse the flow of refrigerant between the first flat pipe 11 and the second flat pipe 21, and is connected to the other end (left side in Figure 2) in the longitudinal direction of each first flat pipe 11 and each second flat pipe 21. The folded header 50 connects the first flat pipe 11 and the second flat pipe 21 to each other and has a plurality of spaces S50 (see Figures 5-7) at each stage that fold back the flow of refrigerant between the first flat pipe 11 and the second flat pipe 21.

[0042] The folded header 50 of this embodiment includes a header body 51, a cover 52, and an intermediate plate 53 positioned between the header body 51 and the cover 52. Figure 5 is a partial perspective view of the intermediate plate 53 as seen from the header body 51 side (the header body 51 and cover 52 are not shown). Figure 6 is a partial perspective view of the header body 51 and the intermediate plate 53 housed therein as seen from the cover 52 side (the cover 52 is not shown). Figure 7 is a side cross-sectional view of the main part of the folded header 50 including the space S50.

[0043] The header body 51 is a rectangular box-shaped body made of a metal material such as an aluminum alloy, with its longer side in the vertical direction (Z-axis direction). The header body 51 has a bottom plate portion 51a, an opening 51b (see Figure 6) on the side opposite the bottom plate portion 51a that is open to the outside, and a circumferential surface portion 51s. The bottom plate portion 51a has a plurality of connection holes 51h through which one end of the first flattened pipe 11 and the second flattened pipe 21 each passes. The circumferential surface portion 51s has a plurality of notches 51p (see Figure 4) at predetermined positions.

[0044] The cover 52 is a rectangular plate member made of a metal material such as an aluminum alloy, with its longer side in the vertical direction (Z-axis direction). The cover 52 is joined to the opening 51b of the header body 51 by welding or the like, thereby closing the opening 51b of the header body 51 and creating a space inside the header body 51. Multiple fitting protrusions 52p are provided at predetermined positions on the periphery of the cover 52, which fit into multiple notches 51p of the header body 51. The engagement between these notches 51p and fitting protrusions 52p positions the cover 52 on the header body 51 (see Figure 4).

[0045] The intermediate plate 53 is made of a metal material such as an aluminum alloy and is a rectangular plate member with its longer side in the vertical direction (Z-axis direction). The short and long sides of the intermediate plate 53 are formed to be the same size as the short and long sides of the lid 52. The intermediate plate 53 is housed inside the header body 51 and is supported between the bottom plate portion 51a of the header body 51 and the lid 52.

[0046] The intermediate plate 53 has a plurality of through holes 53h of a predetermined shape that penetrate in the front-to-back direction (Y-axis direction). Each through hole 53h has a roughly oval shape that is long in the X-axis direction and is arranged at intervals along the vertical direction (Z-axis direction) (see Figure 5). The arrangement interval of each through hole 53h is the same as the arrangement interval of the first flattened pipe 11 and the arrangement interval of the second flattened pipe 21. The arrangement interval referred to here is the distance (pitch) between the centers of adjacent through holes 53h in the vertical direction, or between each flattened pipe.

[0047] Each through-hole 53h is joined to a pair of ends from the first flattened pipes 11 and second flattened pipes 21 of each stage that penetrate the connection portion 51h of the header body 51. As a result, one of the multiple first flattened pipes 11 and one of the multiple second flattened pipes 21 are connected to the same single space S50 of the multiple spaces S50 of the folded header 50 (see Figure 6). The connection portion 51h is formed by drilling holes in the bottom plate portion 51a of the header body 51 according to the end shapes of the first flattened pipes 11 and second flattened pipes 21, and raising the periphery of these holes toward the space S50 side (see Figure 7). Each through-hole 53h is provided with a first buffer portion 81 and a second buffer portion 82, as shown in Figures 5 and 6, but their details will be described later.

[0048] As shown in Figure 7, each space S50 of the folded header 50 has an inner wall surface 501 which is the inner circumferential surface of each through hole 53h, a first inner surface portion 71 which is connected to the first flattened pipe 11 and the second flattened pipe 21, and a second inner surface portion 72 which is opposite to the first inner surface portion 71. The first inner surface portion 71 is formed from a part of the bottom plate portion 51a of the header body 51 which closes one opening of each through hole 53h. The second inner surface portion 72 is formed from a part of the cover 52 which closes the other opening of each through hole 53h. The inner wall surface 501 of the through hole 53h includes a top surface portion 73 and a bottom surface portion 74 which are opposite to each other in the vertical direction in the space S50.

[0049] In this embodiment, the intermediate plate 53 is a laminate of a first plate member 531, a second plate member 532, and a third plate member 533 (see Figure 5). The first plate member 531 is positioned adjacent to the bottom plate portion 51a of the header body 51. The third plate member 533 is positioned adjacent to the lid 52. The second plate member 532 is positioned between the first plate member 531 and the third plate member 533.

[0050] The first plate member 531, the second plate member 532, and the third plate member 533 each have a first opening 531h, a second opening 532h, and a third opening 533h, respectively, as shown in Figures 8(A) to (C). By stacking the first plate member 531, the second plate member 532, and the third plate member 533 in that order, a through hole 53h having the internal shape shown in Figures 5 and 6 is formed.

[0051] Figures 8(A) to 8(C) are front views showing the opening shapes of the first plate member 531, the second plate member 532, and the third plate member 533, respectively, which form the through holes 53h. The first opening 531h, the second opening 532h, and the third opening 533h all have a roughly oval shape that is elongated in the left-right direction (X-axis direction), but their shapes differ in the center in the left-right direction.

[0052] The first opening 531h has a vertical wall portion 531v of a predetermined height Z1, as shown in Figure 8(A). The vertical wall portion 531v forms a part of the collision portion 810 (second wall portion) in the first buffer portion 81, which will be described later (see Figures 9-11). The height Z1 is formed to create a gap G of a predetermined height Z2 between the vertical wall portion 531v and the top surface of the first opening 531h. The height Z1 is set to a size that makes it difficult for liquid refrigerant moving in the left-right direction (X-axis direction) within the through hole 53h to pass over the vertical wall portion 531. On the other hand, the height Z2 is set to a size that is sufficient for gaseous refrigerant to flow through the through hole 53h moving in the left-right direction (X-axis direction). The relative sizes of heights Z1 and Z2 are not particularly limited, and in this embodiment, Z1 > Z2. The vertical wall portion 531v is formed with a width X1 at a position offset to one side (to the right in the example shown in the figure) from the left-right center of the first opening 531h.

[0053] As shown in Figure 8(B), the second opening 532h is divided into two sections horizontally by a partition 532v that extends vertically. The partition 532v forms the other part (first wall) of the collision section 810 in the first buffer section 81, which will be described later (see Figures 9-11). The partition 532v is formed with a width X2 that is greater than the width X1, and is positioned off-center to one side (the right side in the example shown in the figure) of the horizontal center of the second opening 532h.

[0054] As shown in Figure 8(C), the third opening 533h is divided into two sections horizontally by a partition 533v that extends vertically. The partition 533v forms a second buffer section 82, which will be described later (see Figures 9-11). The partition 533v is positioned on the other side (the left side in the example shown in the figure) of the center of the third opening 533h, at a distance T from the partition 532v, so as not to face the partition 532v of the second opening 532h in the front-to-back direction (Y-axis direction). The width X3 of the partition 533v is not particularly limited and may be the same size as the width X2 of the partition 532v, for example.

[0055] The vertical wall portion 531v of the first opening 531h, the partition portion 532v of the second opening 532h, and the partition portion 533v of the third opening 533h form a first buffer portion 81 and a second buffer portion 82 inside the through hole 53h when the first plate member 531, the second plate member 532, and the third plate member 533 are superimposed on each other. The details of the first buffer portion 81 and the second buffer portion 82 will be described below.

[0056] (1st buffer section, 2nd buffer section) Figure 9 is a front view of the through-hole 53h of the intermediate plate 53 as seen from the first plate member 531 side. Figure 10 is a front view of the through-hole 53h of the intermediate plate 53 as seen from the third plate member 533 side. Figure 11 is a cross-sectional view taken along line AA in Figure 10.

[0057] The heat exchanger 100 of this embodiment is provided with a first buffer section 81 and a second buffer section 82 in each of the multiple spaces S50. As shown in Figures 6, 9 to 11, the first buffer section 81 is provided between the first flattened pipe 11 and the second flattened pipe 21 in each space S50. The second buffer section 82 is provided between the first buffer section 81 and the first flattened pipe 11. The first buffer section 81 and the second buffer section 82 are formed to resist the flow of refrigerant between the first flattened pipe 11 and the second flattened pipe 21 in the space S50.

[0058] As shown in Figures 9 to 11, the space S50 has a first space S51 facing the end of the first flattened pipe 11 and a second space S52 facing the end of the second flattened pipe 21. The first buffer section 81 has a collision section 810 that obstructs the flow of refrigerant between the first space S51 and the second space S52, a first flow passage 811 through which mainly liquid refrigerant flows between the first space S51 and the second space S52, and a second flow passage 812 through which mainly gaseous refrigerant flows between the first space S51 and the second space S52.

[0059] The collision section 810 has a first wall section and a second wall section. The first wall section corresponds to the partition section 532v (Figure 8(B)) in the second opening 532h, and is formed between the top surface 73 and the bottom surface 74 of the space section S50, partially closing the space between the first space section S51 and the second space section S52. On the other hand, the second wall section corresponds to the vertical wall section 531v (Figure 8(A)) in the first opening 531h, and is formed between the first wall section (partition section 532v) and the first inner surface 71, partially closing the space between the first space section S51 and the second space section S52 on the side of the first and second flattened pipes 11 and 21 from the first wall section (partition section 532v).

[0060] The first wall portion (partition portion 532v) is part of the second plate member 532 of the intermediate plate 53, and is therefore positioned at a distance equivalent to the thickness of the third plate member 533 from the second inner surface portion 72, which is part of the lid 52 (see Figure 11). On the other hand, the second wall portion (vertical wall portion 531v) is part of the first plate member 531 of the intermediate plate 53, and is therefore positioned between the first inner surface portion 71, which is part of the bottom plate portion 51a of the header body 51, and the first wall portion (partition portion 532v) (see Figure 11).

[0061] Furthermore, the second wall (vertical wall 531v) is positioned between the bottom surface 74 and the first flattened pipe 11 and the second flattened pipe 21. In other words, the height Z1 of the second wall (vertical wall 531v) is set to the height from the bottom surface 74 to the first flattened pipe 11 and the second flattened pipe 21. In this embodiment, the height Z1 is set to the height from the bottom surface 74 to the top surfaces of the first flattened pipe 11 and the second flattened pipe 21 (see Figures 9 and 10). This makes it difficult for the gaseous refrigerant flowing through the second flow passage 812 to flow into the flow path on the windward side of the first flattened pipe 11 and the second flattened pipe 21.

[0062] Next, the first flow passage 811 is formed between the first wall portion (partition portion 532v), the second inner surface portion 72, the top surface portion 73, and the bottom surface portion 74 of the collision portion 810. The flow width of the first flow passage 811 along the front-rear direction (Y-axis direction) is determined by the thickness of the third plate member 533.

[0063] Furthermore, the second flow passage 812 is formed between the second wall (vertical wall 531v), the partition 532v, the first inner surface 71, and the top surface 73. The width of the flow path in the front-rear direction of the second flow passage 812 is determined by the thickness of the first plate member 531, and the height of the flow path in the vertical direction of the second flow passage 812 is the height Z2 obtained by subtracting the height of the second wall (vertical wall 531v) from the vertical height dimension of the space S50. In other words, a gap G of height Z2 (Figure 8(A)) is formed above the vertical wall 531v.

[0064] Furthermore, the second buffer portion 82 corresponds to the partition portion 533v (Figure 8(C)) in the third opening 533h and is positioned adjacent to the second inner surface portion 72. Similar to the first wall portion (partition portion 532v) in the collision portion 810 of the first buffer portion 81, the second buffer portion 82 partially closes the space between the top surface portion 73 and the bottom surface portion 74 of the space portion S50. The second buffer portion 82 further forms a refrigerant inlet 813 between itself and the first wall portion (partition portion 532v) from the first space portion S51 to the second space portion S52, or from the second space portion S52 to the first space portion S51. The inlet 813 has a flow path width corresponding to the interval T (Figure 8(B), (C)).

[0065] As shown in Figures 9 to 11, the first buffer section 81 and the second buffer section 82 are provided between the first space section S51 and the second space section S52. The second buffer section 82 is provided between the first buffer section 81 and the first space section S51. The space section S50 connects the refrigerant flow path 11p of the first flattened pipe 11 and the refrigerant flow path 21p of the second flattened pipe 21 to each other via the first space section S51, the second space section S52, the first buffer section 81 and the second buffer section 82.

[0066] [Function of a heat exchanger] Next, the operation of the heat exchanger 100 of this embodiment, which is configured as described above, will be explained.

[0067] (Basic operation) Figure 12 is an explanatory diagram showing the flow of refrigerant R when the heat exchanger 100 functions as a condenser. When the heat exchanger 100 is the indoor heat exchanger 4, it corresponds to heating operation, and when the heat exchanger 10 is the outdoor heat exchanger 5, it corresponds to cooling operation. On the other hand, Figure 13 is an explanatory diagram showing the flow of refrigerant R when the heat exchanger 100 functions as an evaporator. When the heat exchanger 100 is the indoor heat exchanger 4, it corresponds to cooling operation, and when the heat exchanger 100 is the outdoor heat exchanger 5, it corresponds to heating operation. First, the basic operation of the heat exchanger 100 will be explained.

[0068] When the heat exchanger 100 functions as a condenser, it is supplied with a refrigerant (typically a gaseous refrigerant) R discharged from the compressor 6. The heat exchanger 100 exchanges heat between the refrigerant R and air in the first heat exchange section 10 and the second heat exchange section 20, causing the refrigerant R to change phase from a gaseous state to a liquid state.

[0069] When the heat exchanger 100 functions as a condenser, as shown in Figure 12, the first flat pipes into which the refrigerant R flows are the eight first flat pipes 11 connected to the space S11-S13 of the first flat pipes 11 located on the leeward side. The refrigerant flowing through the condenser undergoes a phase change from gaseous refrigerant to liquid refrigerant through heat exchange with the air, and after it has all become liquid refrigerant, it is cooled by the air. For this reason, the temperature of the refrigerant flowing out of the condenser is lower than the temperature of the refrigerant flowing into the condenser.

[0070] Furthermore, if the flat pipe into which the refrigerant R first flows is located on the upwind side, the high-temperature refrigerant flowing through this flat pipe exchanges heat with the air, causing the temperature of the air flowing in direction A in Figure 12 to rise. This heated air then flows to the flat pipe located on the downwind side, resulting in a smaller temperature difference between the air temperature and the refrigerant flowing through the downwind flat pipe, thus reducing the amount of heat exchange. On the other hand, if the heat exchanger 100 functions as an evaporator as shown in Figure 13, and the flat pipe into which the refrigerant R first flows is the flat pipe on the upwind side (the second flat pipe 21 in this embodiment), the temperature of the refrigerant flowing through the upwind flat pipe will be lower than the temperature of the refrigerant flowing through the downwind flat pipe. As a result, the temperature of the air that has exchanged heat with the refrigerant flowing through the upwind flat pipe is lower than when the refrigerant R initially flows into the upwind flat pipe. Consequently, the temperature difference between the air flowing through the downwind flat pipe and the refrigerant flowing through the downwind flat pipe also increases, leading to a greater amount of heat exchange compared to when the refrigerant R initially flows into the flat pipe located on the upwind side.

[0071] When the heat exchanger 100 functions as a condenser, the refrigerant R, indicated by the white arrows in Figure 12, flows into the spaces S11-S13 of the first header 30 via the supply and discharge pipes 33, passes through the first flat pipe 11 (distribution lines 11a-11c) on the leeward side connected to spaces S11-S13, is returned to the second flat pipe 21 on the leeward side by the return header 50, reverses direction, and flows out into spaces S21-S23 of the second header 40. The refrigerant R that has flowed out into spaces S21-S23 flows again into the first flat pipe 11 (distribution lines 11d-11f) on the leeward side via the connecting pipes 34-36 and spaces S14-S16 of the first header 30. The refrigerant R, which has been returned to the second flat pipe 21 on the upwind side by the return header 50, then flows out from the supply and discharge pipe 43 through the space S24-S26 of the second header 40.

[0072] On the other hand, when the heat exchanger 100 functions as an evaporator, the heat exchanger 100 is supplied with a refrigerant (typically a liquid refrigerant) R that has been depressurized by the expansion valve 7. The heat exchanger 100 performs heat exchange between the refrigerant R and air in the first heat exchange section 10 and the second heat exchange section 20, causing the refrigerant R to undergo a phase change from a liquid state to a gaseous state.

[0073] On the other hand, when the heat exchanger 100 functions as an evaporator, as shown in Figure 13, the first flat pipes into which the refrigerant R flows are the six second flat pipes 21 located on the upwind side, connected to the spaces S24 to S26. The refrigerant flowing through the evaporator undergoes a phase change from liquid refrigerant to gaseous refrigerant through heat exchange with the air, and after becoming entirely gaseous refrigerant, it is superheated through heat exchange with the air. For this reason, the temperature of the refrigerant flowing out of the evaporator is higher than the temperature of the refrigerant flowing into the evaporator.

[0074] When the heat exchanger 100 functions as an evaporator, as shown by the black arrows in Figure 13, the refrigerant R that flows into the space S24~S26 of the second header 40 via the supply and discharge pipes 43 passes through the upwind second flat pipe 21 connected to the space S24~S26, is returned by the return header 50 to the downwind first flat pipe 11 (distribution lines 11d~11f), reverses direction, and flows out into the space S14~S16 of the first header 30. The refrigerant R that has flowed out into the space S14~S16 flows back into the upwind second flat pipe 21 through the connecting pipes 34~36 and the space S21~S23 of the second header 40. The refrigerant R, which has been returned again to the first flattened pipe 11 (flow diversion lines 11a to 11c) on the leeward side by the return header 50, flows out from the supply and discharge pipe 33 through the spaces S11 to S13 of the first header 30.

[0075] Here, among the multiple refrigerant flow paths 11p and 21p inside the flattened pipes 11 and 21, the refrigerant flowing through the upwind refrigerant flow paths 11p and 21p has a larger temperature difference with the air compared to the refrigerant flowing through the downwind refrigerant flow paths 11p and 21p. Therefore, the amount of heat exchange between the refrigerant flowing through the upwind refrigerant flow paths 11p and 21p and the air is greater than the amount of heat exchange between the refrigerant flowing through the downwind refrigerant flow paths 11p and 21p and the air. For this reason, during heating operation, it is preferable that gaseous refrigerant, or a gas-liquid two-phase refrigerant with a higher proportion of gaseous refrigerant than liquid refrigerant, flows more through the upwind refrigerant flow paths 11p and 21p, where the amount of heat exchange is greater, and during cooling operation, it is preferable that liquid refrigerant, or a gas-liquid two-phase refrigerant with a higher proportion of liquid refrigerant than gaseous refrigerant, flows more through the upwind refrigerant flow paths 11p and 21p, where the amount of heat exchange is greater, than through the downwind refrigerant flow paths.

[0076] Furthermore, in an air conditioner 1, as in this embodiment, in which an outdoor heat exchanger 5 and an indoor heat exchanger 4 are each employed, each heat exchanger 100 is made up of multiple rows of flattened tubes 11, 21 arranged in two rows in the front-to-back direction (direction of airflow), when the heat exchanger 100 functions as a condenser, the refrigerant compressed by the compressor 6 first flows into the flattened tubes (first flattened tubes 11) in the row on the leeward side of the heat exchanger 100 (Figure 12). On the other hand, when the heat exchanger 100 functions as an evaporator, the refrigerant depressurized by the expansion valve 7 first flows into the flattened tubes (second flattened tubes 21) in the row on the leeward side of the heat exchanger 100 (Figure 13).

[0077] Furthermore, the refrigerant flowing into one row of flattened pipes in the heat exchanger 100 (for example, the second flattened pipe 21 on the upwind side) is returned by the return header 50 to the flattened pipes in the other row (for example, the first flattened pipe 11 on the downwind side). When the refrigerant flowing into the return header 50 is in a gas-liquid two-phase state, the liquid refrigerant, which has a higher specific gravity than the gaseous refrigerant, is strongly affected by inertial force and swung outward when the flow of the refrigerant is returned and reversed by the return header 50. Therefore, in a heat exchanger (hereinafter also referred to as the heat exchanger of the comparative example) in which the space connecting the flattened pipes located on the upwind side and the flattened pipes located on the downwind side within the return header 50 has the shape shown in Figures 14 and 15, the amount of heat exchanged in the heat exchanger decreases, as will be described in detail below.

[0078] (Comparative example) Figures 14 and 15 are explanatory diagrams showing the shape of the space S60 of a conventional folded header 60. Figure 14 is a cross-sectional view of the main part as seen from the longitudinal direction (Y-axis direction) of the flattened pipes 11 and 21, and Figure 15 is a cross-sectional view of the main part as seen from the thickness direction (Z-axis direction) of the flattened pipes 11 and 21. The folded header 60 of the comparative example differs from the folded header 50 of this embodiment in that the shape of the through-hole 61 forming the space S60 is different. In other words, the folded header 60 of the comparative example differs from this embodiment in that the first buffer portion 81 and the second buffer portion 82 are not provided in the space S60.

[0079] When a conventional heat exchanger equipped with a folded header 60 functions as a condenser, the refrigerant R passing through the first flattened tube 11 and the second flattened tube 21 undergoes a phase change to liquid refrigerant through heat exchange with air. In this case, of the refrigerant flow paths 11p of the first flattened tube 11, the gaseous refrigerant flowing through the refrigerant flow path 11p located on the windward side undergoes a greater amount of heat exchange with air than the gaseous refrigerant flowing through the refrigerant flow path 11p located on the leeward side, and therefore more gaseous refrigerant undergoes a phase change to liquid refrigerant. Similarly, of the refrigerant flow paths 21p of the second flattened tube 21, the gaseous refrigerant flowing through the refrigerant flow path 21p located on the windward side undergoes a greater amount of heat exchange with air than the gaseous refrigerant flowing through the refrigerant flow path 21p located on the leeward side, and therefore more gaseous refrigerant undergoes a phase change to liquid refrigerant.

[0080] Here, the upwind refrigerant flow path 11p refers to the refrigerant flow path 11p located in the upwind region when the widthwise center of the first flat pipe 11 is used as the boundary, and the downwind refrigerant flow path 11p refers to the refrigerant flow path 11p located in the downwind region when the widthwise center of the first flat pipe 11 is used as the boundary. Similarly, the upwind refrigerant flow path 21p refers to the refrigerant flow path 21p located in the upwind region when the widthwise center of the second flat pipe 21 is used as the boundary, and the downwind refrigerant flow path 21p refers to the refrigerant flow path 21p located in the downwind region when the widthwise center of the second flat pipe 21 is used as the boundary.

[0081] Then, when the gas-liquid two-phase refrigerant R that has flowed out from the first flattened pipe 11 on the leeward side into the space S60 is reversed and folds back toward the second flattened pipe 21 on the windward side (see arrow B in Figure 15), the liquid refrigerant, which has a higher specific gravity than the gaseous refrigerant, is more strongly affected by the inertial force during reversal in the space S60 and is more likely to be swung outwards. For this reason, most of the liquid refrigerant is guided to the second flattened pipe 21 along the inner wall surface of the space S60. As a result, as schematically shown in Figure 16, the liquid refrigerant of the refrigerant R accumulates in the windward region of the space S60, and a large amount of gaseous refrigerant flows into the refrigerant flow path located on the leeward side of the refrigerant flow path 21p of the second flattened pipe 21, that is, the refrigerant flow path with a small heat exchange rate. In this way, in the conventional reversed header 60, the gaseous refrigerant that is to be phase-changed flows more in the leeward refrigerant flow path, which has a smaller heat exchange rate, than in the windward refrigerant flow path, and the amount of heat exchange as a condenser decreases.

[0082] On the other hand, when the heat exchanger with the folded header 60 of the comparative example functions as an evaporator, the refrigerant R passing through the first flattened tube 11 and the second flattened tube 21 undergoes a phase change to a gaseous refrigerant through heat exchange with the air. In this case, of the refrigerant flow paths 11p of the first flattened tube 11, the liquid refrigerant flowing through the refrigerant flow path 11p located on the upwind side undergoes a greater amount of heat exchange with the air than the liquid refrigerant flowing through the refrigerant flow path 11p located on the downwind side, and therefore more liquid refrigerant undergoes a phase change to a gaseous refrigerant. Similarly, of the refrigerant flow paths 21p of the second flattened tube 21, the liquid refrigerant flowing through the refrigerant flow path 21p located on the upwind side undergoes a greater amount of heat exchange with the air than the liquid refrigerant flowing through the refrigerant flow path 21p located on the downwind side, and therefore more liquid refrigerant undergoes a phase change to a gaseous refrigerant.

[0083] Then, when the gas-liquid two-phase refrigerant R that has flowed out from the upwind second flat pipe 21 into the space S60 is returned towards the downwind first flat pipe 11 (see arrow B in Figure 17), the liquid refrigerant, which has a higher specific gravity than the gaseous refrigerant, is more strongly affected by the inertial force during reversal in the space S60 and is more likely to be swung outwards. For this reason, most of the liquid refrigerant is guided along the inner wall surface of the space S60 to the first flat pipe 11. As a result, the liquid refrigerant of the refrigerant R accumulates in the downwind region of the space S60, and a large amount of liquid refrigerant flows into the refrigerant flow path located on the downwind side of the refrigerant flow path 11p of the first flat pipe 11, that is, the refrigerant flow path with a small heat exchange rate. In this way, in the conventional folded header 60, more of the liquid refrigerant that is to undergo phase change flows into the downwind refrigerant flow path, which has a smaller heat exchange rate, than into the upwind refrigerant flow path, thus reducing the amount of heat exchanged as an evaporator.

[0084] (Operation of this embodiment) In contrast, in the heat exchanger 100 of this embodiment, as described above, a first buffer section 61 and a second buffer section 62 are provided in each space S50 of the folded header 50 (see Figures 6, 9-11). The operation of the folded header 50 of this embodiment will now be described.

[0085] When the heat exchanger 100 functions as a condenser, the refrigerant R flowing out from the first flattened tube 11 flows into the first space S51, passes through the first buffer section 81 and the second buffer section 82 to reach the second space S52, and flows from the second space S52 into the refrigerant flow path 21p of the second flattened tube 21. Figure 18 is a schematic partial cross-sectional view showing the behavior of the refrigerant R in the folded header 50 when the heat exchanger 100 functions as a condenser, where (A) is a front view corresponding to Figure 10 and (B) is a cross-sectional view corresponding to Figure 11.

[0086] Of the gaseous and liquid two-phase refrigerant R that flows out from the first flattened pipe 11 into the space S50, the liquid refrigerant, which has a higher specific gravity than the gaseous refrigerant, is strongly affected by the inertial force during reversal in the space S50 and is biased toward the inner wall surface 501 of the first space S51. Then, most of the liquid refrigerant biased toward the inner wall surface 501 of the first space S51 is guided to the second space S52 along the second inner surface 72, top surface 73, and bottom surface 74 of the first space S51. In addition, since the second space S52 is at a lower pressure than the first space S51, the movement of refrigerant R from the first space S51 to the second space S52 is promoted.

[0087] At this time, a portion of the refrigerant R moving from the first space S51 to the second space S52 collides with the collision section 810 of the first buffer section 81. Another portion of the refrigerant R moving from the first space S51 to the second space S52 collides with the second buffer section 82. The collisions with the collision section 810 and the second buffer section 82 reduce the flow velocity of the refrigerant R. As a result, when the refrigerant R flows into the second space S52, most of the liquid refrigerant flows to the bottom of the second space S52 due to gravity, while most of the gaseous refrigerant, which has a lower specific gravity than the liquid refrigerant, flows to the top of the second space S52.

[0088] Most of the liquid refrigerant in the first space S51 moves to the second space S52 through the first flow passage 811 and inlet 813 formed between the first buffer section 81 and the second buffer section 82, as shown by the dashed arrows in Figures 18(A) and (B). Similarly, the gaseous refrigerant also moves from the first space S51 to the second space S52 through the first flow passage 811 and inlet 813. Furthermore, because the gaseous refrigerant has a lower specific gravity than the liquid refrigerant, it tends to be distributed more towards the top surface 73 (upper side) than towards the bottom surface 74. For this reason, some of the gaseous refrigerant moves to the second space S52 through the second flow passage 812 (gap G) of the first buffer section 81.

[0089] In this way, the refrigerant R flowing from the first space S51 to the second space S52 is subjected to resistance from the first buffer section 81 and the second buffer section 82, which reduces the flow velocity of the refrigerant R. As a result, most of the liquid refrigerant moves from the bottom of the first space S51 to the second space S52 due to gravity, and most of the gaseous refrigerant moves from the top of the first space S51 to the second space S52. Consequently, more gaseous refrigerant tends to accumulate on the upwind side (left side in the figure) of the second space S52 than liquid refrigerant. Furthermore, the gaseous refrigerant flowing into the second space S52 pushes the liquid refrigerant that has flowed into the second space S52 back downwind, causing the liquid level of the liquid refrigerant located downwind of the second space S52 to rise (see Figure 18(A)). As a result, in the folded header 50, the liquid refrigerant flowing out from the first flattened pipe 11 flows more easily into the refrigerant flow path 21p on the leeward side of the second flattened pipe 21, and the gaseous refrigerant flowing out from the first flattened pipe 11 flows more easily into the refrigerant flow path 21p on the leeward side of the second flattened pipe 21, where the heat exchange rate is higher. Consequently, the condensation efficiency of the refrigerant is increased, and the decrease in the heat exchange rate of the heat exchanger 100, which acts as a condenser, can be suppressed.

[0090] On the other hand, when the heat exchanger 100 functions as an evaporator, the refrigerant R that flows out from the second flattened pipe 21 flows into the second space S52, and from this second space S52 it passes through the first buffer section 81 and the second buffer section 82 to reach the first space S51, and from this first space S51 it flows into the refrigerant flow path 11p of the first flattened pipe 11. Figure 19 is a schematic partial cross-sectional view showing the behavior of the refrigerant R in the folded header 50 when the heat exchanger 100 functions as an evaporator, where (A) is a front view corresponding to Figure 10 and (B) is a cross-sectional view corresponding to Figure 11.

[0091] Of the gaseous and liquid two-phase refrigerant R that flows out from the second flattened pipe 21 into the space S50, the liquid refrigerant, which has a higher specific gravity than the gaseous refrigerant, is strongly affected by the inertial force during reversal in space S50 and is biased toward the inner wall surface 501 of the second space S52. Then, most of the liquid refrigerant biased toward the inner wall surface 501 of the second space S52 is guided to the first space S51 along the second inner surface 72, top surface 73, and bottom surface 74 of the second space S52. In addition, since the first space S51 is at a lower pressure than the second space S52, the movement of refrigerant R from the second space S52 to the first space S51 is promoted.

[0092] At this time, a portion of the refrigerant R moving from the second space S52 to the first space S51 collides with the collision section 810 of the first buffer section 81. Another portion of the refrigerant R moving from the second space S52 to the first space S51 collides with the second buffer section 82. The collisions with the collision section 810 and the second buffer section 82 reduce the flow velocity of the refrigerant R. As a result, when the refrigerant R flows into the first space S51, most of the liquid refrigerant flows to the bottom of the first space S51 due to gravity, while most of the gaseous refrigerant, which has a lower specific gravity than the liquid refrigerant, flows to the top of the first space S51.

[0093] Most of the liquid refrigerant in the second space S52 moves to the first space S51 through the first flow passage 811 and inlet 813 formed between the first buffer section 81 and the second buffer section 82, as shown by the dashed arrows in Figures 19(A) and (B). Similarly, the gaseous refrigerant also moves from the second space S52 to the first space S51 through the first flow passage 811 and inlet 813. Furthermore, because the gaseous refrigerant has a lower specific gravity than the liquid refrigerant, it tends to be distributed more towards the top surface 73 (upper side) than towards the bottom surface 74. For this reason, some of the gaseous refrigerant moves to the first space S51 through the second flow passage 812 (gap G) of the first buffer section 81.

[0094] In this way, the refrigerant R flowing from the second space S52 to the first space S51 is subjected to resistance from the first buffer section 81 and the second buffer section 82, which reduces the flow velocity of the refrigerant R. As a result, most of the liquid refrigerant moves from the bottom of the second space S52 to the first space S51 due to gravity, and most of the gaseous refrigerant moves from the top of the second space S52 to the first space S51. Consequently, more gaseous refrigerant tends to accumulate on the downwind side (right side in the figure) of the first space S51 than liquid refrigerant. Furthermore, the gaseous refrigerant flowing into the first space S51 pushes the liquid refrigerant that has flowed into the first space S51 back upwind, causing the liquid level of the liquid refrigerant located on the upwind side of the first space S51 to rise (see Figure 19(A)). As a result, within the folded header 50, the gas medium flowing out from the second flattened pipe 21 flows more easily into the refrigerant flow path 21p on the leeward side of the first flattened pipe 11, and the liquid refrigerant flowing out from the second flattened pipe 11 flows more easily into the refrigerant flow path 21p on the leeward side of the second flattened pipe 21, where the heat exchange rate is higher. Consequently, the evaporation efficiency of the refrigerant is increased, and the decrease in the heat exchange rate of the heat exchanger 100, which acts as an evaporator, can be suppressed.

[0095] As described above, according to this embodiment, since a first buffer section 81 and a second buffer section 82 are provided in each space S50 of the folded header 50, when the heat exchanger 100 functions as a condenser, the folded header 50 causes a large amount of gaseous refrigerant to flow through the upwind refrigerant flow path, i.e., the refrigerant flow path with a large heat exchange rate, among the multiple refrigerant flow paths 11p of the first flat pipe 11 in the upwind row. Also, when the heat exchanger 100 functions as an evaporator, the folded header 50 causes a large amount of liquid refrigerant to flow through the upwind refrigerant flow path, i.e., the refrigerant flow path with a large heat exchange rate, among the refrigerant flow paths 21p of the second flat pipe 21 in the downwind row. In this way, since a large amount of the refrigerant to be phase-changed flows through the upwind refrigerant flow path with a large heat exchange rate, the decrease in the amount of heat exchanged in the heat exchanger 100 can be suppressed.

[0096] Furthermore, according to this embodiment, since the intermediate plate 53 that forms each space S50 of the folded header 50 is made up of a laminate of multiple plate members 531 to 533, the first buffer portion 81 and the second buffer portion 82 can be easily formed in any shape at any position in the space S50.

[0097] Furthermore, in the space section S50, the flow velocity of the refrigerant flow path formed by the first flow passage 811 and the inlet 813 is reduced by the first buffer section 81 and the second buffer section 82. As a result, the liquid refrigerant flowing at the bottom of the space section S50 flows due to the effect of gravity, and the gaseous refrigerant separated from the liquid refrigerant flows through the second flow passage 812 to the first space S51 or the second space S52. Consequently, when the heat exchanger 100 functions as a condenser, the amount of gaseous refrigerant increases on the upwind side of the first space section S51 (see Figure 18(A)), and when the heat exchanger 100 functions as an evaporator, the amount of liquid refrigerant increases on the upwind side of the second space section S52 (see Figure 19(A)). Therefore, it is possible to easily direct the refrigerant to be phase-changed into the upwind refrigerant flow paths 11p and 21p, which have a larger heat exchange rate.

[0098] Furthermore, the height of the second wall portion (vertical wall portion 531v) of the first buffer portion 81 is set to be greater than or equal to the height from the bottom portion 74 to the connection portion between the first flattened pipe 11 and the second flattened pipe 21 in the first inner surface portion 71. Therefore, when the heat exchanger 100 functions as a condenser, most of the refrigerant flowing from the first space portion S51 to the second space portion S52 flows through the first flow passage 811 and the inlet 813, so the liquid level of the liquid refrigerant can be set to a height that can reach the refrigerant flow path 21p on the leeward side of the second flattened pipe 21, making it easier for the liquid refrigerant to flow into the leeward side refrigerant flow path 21p (see Figure 18(A)). Furthermore, when the heat exchanger 100 functions as an evaporator, much of the liquid refrigerant flowing from the second space S52 to the first space S51 flows through the first flow passage 811 and the inlet 813. This allows the liquid level of the liquid refrigerant to reach the refrigerant flow path 11p on the upwind side of the first flattened pipe 11, making it easier for the liquid refrigerant to flow into the refrigerant flow path 11p on the upwind side (see Figure 19(A)).

[0099] Furthermore, according to this embodiment, the above-mentioned effects can be maintained without depending on the circulation rate of the refrigerant R in the heat exchanger 100. The inventors set the circulation rate of the refrigerant to three stages: low circulation (compressor 6 rotation speed: minimum to intermediate rotation speed), medium circulation (compressor 6 rotation speed: intermediate to rated rotation speed), and high circulation (compressor 6 rotation speed: rated to maximum rotation speed), and measured the amount of refrigerant that was returned by the return header 50 flowing through the refrigerant flow path on the upstream side of the flat tube for each stage. In this experiment, the heat exchanger 100 was used as a condenser, and the amount of refrigerant flowing through the refrigerant flow path on the upstream side of the flat tube was defined as the upstream flow rate ratio, which is the ratio of the amount of refrigerant flowing through the refrigerant flow path on the leeward side. The upstream flow rate ratio was defined by dividing the multiple refrigerant flow rates 11p of the first flat tube 11 equally between the upstream and leeward sides, and defining it as the ratio of the amount of refrigerant flowing through them.

[0100] The experimental results showed that, at low circulation rates, the conventional heat exchanger without the first buffer section 81 and the second buffer section 82 (see Figures 14 and 15) had a circulation rate of 33%, while the heat exchanger 100 of this embodiment had a rate of 79%. At medium circulation rates, the conventional heat exchanger had a circulation rate of 65%, while the heat exchanger 100 of this embodiment had a rate of 78%. At high circulation rates, the conventional heat exchanger had a circulation rate of 30%, while the heat exchanger 100 of this embodiment had a rate of 72%.

[0101] As is clear from these experimental results, the heat exchanger 100 of this embodiment provides higher heat exchange performance compared to conventional heat exchangers, and also provides stable heat exchange performance regardless of the refrigerant circulation rate. Furthermore, because stable heat exchange performance is obtained regardless of the refrigerant circulation rate, even if there is variation in the amount of refrigerant in the space S50 of each stage of the folded header 50, the heat exchange performance in the flattened pipes 11 and 21 of each stage can be kept almost constant. In addition, almost constant heat exchange performance can be ensured regardless of the operating conditions of the air conditioner 1.

[0102] Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the embodiments described above and can be modified in various ways.

[0103] For example, in the above embodiment, a first buffer portion 61 and a second buffer portion 62 are provided in each space S50 of the folded header 50, but the second buffer portion 62 may be omitted. Furthermore, the size (flow path cross-section) of the second flow passage 812 through which the gaseous refrigerant flows in the first buffer section 61 is set by the height of the vertical wall section 531v, but is not limited to this. For example, the vertical wall section 531v may be a partition section similar to the partition section 532v, and the size may be set by the size of a hole (round hole, square hole, etc.) formed at an appropriate position in the partition section. [Explanation of symbols]

[0104] 1…Air conditioner 4…Indoor heat exchanger 5…Outdoor heat exchanger 10…First heat exchange section 11...First flat tube 11p, 21p… Refrigerant flow path 21…Second flat tube 20…Second heat exchange section 30…First Header 40…Second Header 50... Header 53…Intermediate plate 53h…Through hole 71...First inner wall section 72...Second inner part 73...Top section 74…Bottom part 81...1st buffer section 82...Second buffer section 100...Heat exchanger 531v…Vertical wall section 532v, 533v... partition section 810...Collision part 811…1st flow path 812…Second flow path 813…Third distribution path R... Refrigerant S50…Space part S51...first space part S52…Second space part

Claims

1. A first heat exchange section having a plurality of first flattened tubes arranged in the vertical direction, A second heat exchange section having a plurality of second flattened tubes arranged in the vertical direction, It comprises a folded header whose interior is divided into multiple spatial sections, Inside each of the multiple first flattened tubes and the multiple second flattened tubes, multiple refrigerant flow paths extending in the front-to-back direction are formed, arranged in the left-to-right direction. The first heat exchange section and the second heat exchange section are arranged side by side in the left-right direction. One of the plurality of first flattened tubes and one of the plurality of second flattened tubes are connected to one of the plurality of spaces. A first buffer is provided between the first flattened pipe and the second flattened pipe in the aforementioned space. The first buffer portion has a first wall portion and a second wall portion that is lower in height than the first wall portion. Each of the aforementioned spatial portions has a first inner surface portion connected to the first flattened pipe and the second flattened pipe, a second inner surface portion facing the first inner surface portion, and a top surface portion and a bottom surface portion facing each other in the vertical direction. A first flow passage for flowing liquid coolant into the space is formed between the first wall portion, the second inner surface portion, the top surface portion, and the bottom surface portion. A second flow passage for refrigerant gas is formed between the first wall portion, the second wall portion, the first inner surface portion, and the top surface portion. heat exchanger.

2. A heat exchanger according to claim 1, The first buffer portion is formed to resist the flow of refrigerant between the first flattened tube and the second flattened tube in the space. heat exchanger.

3. A heat exchanger according to claim 1, The first wall portion is positioned away from the second inner surface portion, The second wall portion is positioned on the bottom portion between the bottom portion and the first flattened pipe and the second flattened pipe. heat exchanger.

4. A heat exchanger according to claim 1 or 3, The height of the second wall portion is greater than or equal to the height from the bottom portion to the connection portion between the first flattened pipe and the second flattened pipe in the first inner surface portion. heat exchanger.

5. A heat exchanger according to any one of claims 1 to 4, A second buffer is provided between the first buffer and the first flattened pipe or the second flattened pipe. heat exchanger.

6. A heat exchanger according to claim 5, In the plurality of spaces, the second buffer portion is provided on the second inner surface so as to face the first flow passage in the left-right direction. heat exchanger.

7. A first heat exchange section having a plurality of first flattened tubes arranged in the vertical direction, A second heat exchange section having a plurality of second flattened tubes arranged in the vertical direction, It comprises a folded header whose interior is divided into multiple spatial sections, Inside each of the multiple first flattened tubes and the multiple second flattened tubes, multiple refrigerant flow paths extending in the front-to-back direction are formed, arranged in the left-to-right direction. The first heat exchange section and the second heat exchange section are arranged side by side in the left-right direction. One of the plurality of first flattened tubes and one of the plurality of second flattened tubes are connected to one of the plurality of spaces. A first buffer is provided between the first flattened pipe and the second flattened pipe in the aforementioned space. The first buffer section has a collision section that obstructs the flow of refrigerant between the first flattened pipe and the second flattened pipe, a first flow passage for flowing liquid refrigerant between the first flattened pipe and the second flattened pipe, and a second flow passage for flowing gaseous refrigerant between the first flattened pipe and the second flattened pipe. Each of the aforementioned spatial portions has a first inner surface portion connected to the first flattened pipe and the second flattened pipe, a second inner surface portion facing the first inner surface portion, and a top surface portion and a bottom surface portion facing each other in the vertical direction. The collision portion has a first wall portion formed between the top portion and the bottom portion, and a second wall portion of a predetermined height formed between the first wall portion and the first inner surface portion. A second buffer is provided between the first buffer and the first flattened pipe or the second flattened pipe. heat exchanger.

8. An air conditioner equipped with a heat exchanger according to any one of claims 1 to 7.

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