Heat exchanger and refrigeration cycle device

Abstract

This heat exchanger comprises: a plurality of heat transfer tubes in which a refrigerant flows; a lower header into which the lower ends of the plurality of heat transfer tubes are inserted and to which refrigerant piping for the inflow of the refrigerant is connected; and an upper header into which the upper ends of the plurality of heat transfer tubes are inserted. The average insertion length of the plurality of heat transfer tubes inserted into the lower header is shorter than the average insertion length of the plurality of heat transfer tubes inserted into the upper header.

Description

Heat exchanger and refrigeration cycle device

[0001] The present disclosure relates to a heat exchanger and a refrigeration cycle device that exchange heat between a refrigerant and air.

[0002] Conventionally, heat exchangers have been known to have a configuration in which multiple heat transfer tubes are inserted into a header. In the header of a heat exchanger, the cross-sectional area of ​​the flow path through which the refrigerant flows changes depending on the portions of the multiple heat transfer tubes that protrude into the header. This increases the pressure loss of the refrigerant flowing through the header, resulting in a decrease in refrigerant distribution performance. In response to this issue, the heat exchanger disclosed in Patent Document 1 adjusts the spacing between the heat transfer tubes inserted into the header to suppress the generation of vortices within the header and reduce pressure loss.

[0003] Japanese Patent Application Laid-Open No. 2005-241089

[0004] However, in Patent Document 1, the insertion intervals of the heat transfer tubes into the header vary depending on the location, which makes the processing of openings in the header for inserting the heat transfer tubes complicated.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a heat exchanger and a refrigeration cycle device that can improve refrigerant distribution performance while suppressing a decrease in the processability of the header.

[0006] The heat exchanger according to the present disclosure comprises a plurality of heat transfer tubes through which a refrigerant flows, a lower header into which the lower ends of the heat transfer tubes are inserted and to which a refrigerant pipe through which the refrigerant flows, and an upper header into which the upper ends of the heat transfer tubes are inserted, and the average insertion length of the plurality of heat transfer tubes inserted into the lower header is shorter than the average insertion length of the plurality of heat transfer tubes inserted into the upper header.

[0007] According to the heat exchanger of the present disclosure, the insertion length of the lower header is shorter than the insertion length of the upper header, thereby improving the refrigerant distribution performance while suppressing a decrease in the workability of the header.

[0008] Fig. 1 is a circuit diagram showing an air conditioning apparatus according to embodiment 1. Fig. 2 is a schematic configuration diagram showing a heat exchanger according to embodiment 1. Fig. 3 is a perspective view showing a row-to-row header according to embodiment 1. Fig. 4 is a cross-sectional view of a heat exchanger according to embodiment 1. Fig. 5 is a diagram for explaining the upper limit of the insertion length of a heat transfer tube according to embodiment 2. Fig. 6 is a graph showing the relationship between δ / δy and pressure loss. Fig. 7 is a cross-sectional view of a heat exchanger according to embodiment 3. Fig. 8 is a cross-sectional view of a heat exchanger according to embodiment 4.

[0009] Embodiment 1. An air conditioning apparatus 100 according to embodiment 1 will now be described with reference to the drawings. FIG. 1 is a circuit diagram showing the air conditioning apparatus 100 according to embodiment 1. The air conditioning apparatus 100 is an example of a refrigeration cycle apparatus. As shown in FIG. 1, the air conditioning apparatus 100 has an outdoor unit 110, an indoor unit 120, and refrigerant piping 130.

[0010] 1 , the outdoor unit 110 has a compressor 111, a flow path switching valve 112, a heat exchanger 1, a blower 113, and an expansion valve 114. The indoor unit 120 has a heat exchanger 121 and a blower 122. The refrigerant piping 130 connects the flow path switching valve 112, the heat exchanger 1, the expansion valve 114, and the heat exchanger 121, and is a piping through which a refrigerant flows.

[0011] The compressor 111 draws in a low-temperature, low-pressure refrigerant, compresses it, and discharges it as a high-temperature, high-pressure refrigerant. The flow path switching valve 112 switches the flow direction of the refrigerant in the refrigerant circuit and is, for example, a four-way valve. The heat exchanger 1 exchanges heat between the refrigerant and outdoor air. The heat exchanger 1 acts as a condenser during cooling operation and as an evaporator during heating operation. The blower 113 is a device that sends outdoor air to the heat exchanger 121. The expansion valve 114 decompresses and expands the refrigerant and is, for example, an electronic expansion valve.

[0012] The heat exchanger 121 exchanges heat between the indoor air and the refrigerant. The heat exchanger 121 acts as an evaporator during cooling operation and as a condenser during heating operation. The blower 122 is a device that sends indoor air to the heat exchanger 121, and is, for example, a cross-flow fan.

[0013] The heat exchanger 1 according to the first embodiment will be further described below. FIG. 2 is a schematic diagram illustrating the heat exchanger 1 according to the first embodiment. The heat exchanger 1 functions as a condenser or an evaporator in a refrigeration cycle device such as an air conditioning device 100 or a refrigerator. As shown in FIG. 2 , the heat exchanger 1 includes heat transfer tubes 2, fins 3, a first lower header 4, a second lower header 5, and a row header 6. In the following drawings, the Z axis indicates the vertical direction of the heat exchanger 1, the X axis indicates the short side direction of the heat exchanger 1, and the Y axis indicates the longitudinal direction of the heat exchanger 1, which are directions perpendicular to the vertical direction. The solid arrows indicate the flow of refrigerant when the heat exchanger 1 functions as a condenser, and the dashed arrows indicate the flow of refrigerant when the heat exchanger 1 functions as an evaporator.

[0014] The heat transfer tubes 2 are, for example, flat tubes, and have multiple flow paths (not shown) formed therein through which the refrigerant flows. The heat transfer tubes 2 extend in the vertical direction. The heat transfer tubes 2 perform heat exchange between the refrigerant flowing through the internal flow paths and the air. The heat exchanger 1 has multiple heat transfer tubes 2. The multiple heat transfer tubes 2 aligned in the longitudinal direction of the heat exchanger 1 form a first row 2A and a second row 2B. The first row 2A and the second row 2B are aligned in the lateral direction of the heat exchanger 1.

[0015] The fins 3 promote heat exchange between the refrigerant flowing inside the heat transfer tubes 2 and the air. The fins 3 are, for example, corrugated fins. The heat exchanger 1 has a plurality of fins 3. The plurality of fins 3 are provided between two heat transfer tubes 2 forming a first row 2A and between two heat transfer tubes 2 forming a second row 2B. Note that while FIG. 2 only shows some of the heat transfer tubes 2 and fins 3, in reality, the heat transfer tubes 2 and fins 3 are alternately arranged in the longitudinal direction without any gaps. Furthermore, the plurality of heat transfer tubes 2 are arranged at equal intervals in the longitudinal direction.

[0016] The first lower header 4 is a header disposed below the heat exchanger 1. The lower ends of the heat transfer tubes 2 forming the first row 2A are inserted into the first lower header 4. The first refrigerant pipe 11, which is part of the refrigerant pipe 130, is connected to the first lower header 4. When the heat exchanger 1 functions as a condenser, the first lower header 4 functions as a gas header that distributes the gaseous refrigerant that flows in from the first refrigerant pipe 11 to the heat transfer tubes 2 forming the first row 2A. When the heat exchanger 1 functions as an evaporator, the first lower header 4 functions as a liquid header that distributes the liquid refrigerant that has merged from the heat transfer tubes 2 forming the first row 2A to the first refrigerant pipe 11.

[0017] The second lower header 5 is a header disposed below the heat exchanger 1. The lower ends of the heat transfer tubes 2 forming the second row 2B are inserted into the second lower header 5. A second refrigerant pipe 12, which is part of the refrigerant pipe 130, is connected to the second lower header 5. When the heat exchanger 1 functions as a condenser, the second lower header 5 functions as a liquid header that allows liquid refrigerant that has joined from the heat transfer tubes 2 forming the second row 2B to flow out to the second refrigerant pipe 12. When the heat exchanger 1 functions as an evaporator, the second lower header 5 functions as a gas header that distributes gas refrigerant that has flowed in from the second refrigerant pipe 12 to the heat transfer tubes 2 forming the second row 2B. The first lower header 4 and the second lower header 5 correspond to the "lower headers" in this disclosure.

[0018] The row-transfer header 6 is a header provided at the top of the heat exchanger 1, facing the first lower header 4 and the second lower header 5. The upper ends of the heat transfer tubes 2 forming the first row 2A and the second row 2B are inserted into the row-transfer header 6. The row-transfer header 6 relays the flow of refrigerant between the heat transfer tubes 2 inserted in the first lower header 4 and the heat transfer tubes 2 inserted in the second lower header 5. Specifically, when the heat exchanger 1 functions as a condenser, the row-transfer header 6 distributes the refrigerant that has merged from the heat transfer tubes 2 forming the first row 2A to the heat transfer tubes 2 forming the second row 2B. When the heat exchanger 1 functions as an evaporator, the row-transfer header 6 distributes the refrigerant that has merged from the heat transfer tubes 21 forming the second row 2B to the heat transfer tubes 2 forming the first row 2A. The row-transfer header 6 corresponds to the “upper header” in this disclosure.

[0019] FIG. 3 is a perspective view showing the row-connection header 6 according to the first embodiment. FIG. 3 shows a cross section of the heat exchanger 1 cut along the XZ plane. For simplicity, FIG. 3 shows only the front heat transfer tube 2 of the multiple heat transfer tubes 2 inserted into the row-connection header 6. As shown in FIG. 3 , the row-connection header 6 includes a base 61 and a cover plate 62. The base 61 forms the bottom and sides of the row-connection header 6 and has an open top. The bottom of the base 61 is formed with openings (not shown) through which the heat transfer tubes 2 are inserted. As described above, the multiple heat transfer tubes 2 are disposed at equal intervals in the longitudinal direction. Therefore, the multiple openings through which the multiple heat transfer tubes 2 are inserted are also formed at equal intervals. The upper ends of the heat transfer tubes 2 are located inside the row-connection header 6. The cover plate 62 is a flat member that covers the openings formed in the upper surface of the base 61. The cover plate 62 forms the upper portion of the row-connection header 6.

[0020] Returning to FIG. 2 , the flow of refrigerant in the heat exchanger 1 will be described. Here, only the flow of refrigerant when the heat exchanger 1 functions as a condenser will be described. First, the refrigerant flowing in from the first refrigerant pipe 11 flows into the first lower header 4. The refrigerant flowing in the first lower header 4 is distributed to the plurality of heat transfer tubes 2 forming the first row 2A. The refrigerant that has flowed through the plurality of heat transfer tubes 2 forming the first row 2A joins together at the row-to-row header 6 and is distributed to the plurality of heat transfer tubes 2 forming the second row 2B. The refrigerant that has flowed through the plurality of heat transfer tubes 2 forming the second row 2B joins together at the second lower header 5 and flows out from the second refrigerant pipe 12.

[0021] At this time, the pressure loss of the refrigerant flowing through the first lower header 4 in the longitudinal direction of the heat exchanger 1 is affected by the heat transfer tubes 2 inserted into the first lower header 4. For this reason, for example, in the first lower header 4, the degree of pressure loss of the refrigerant flowing from point P1 to point P2 varies depending on the insertion length of the heat transfer tubes 2 into the first lower header 4. Point P1 is a point directly below the heat transfer tube 2 in the first row 2A that is closest to the first refrigerant pipe 11. Point P2 is a point directly below the heat transfer tube 2 in the first row 2A that is farthest from the first refrigerant pipe 11. The insertion length refers to the length by which the heat transfer tube 2 is inserted into the header.

[0022] Furthermore, the pressure loss of the refrigerant flowing through the row-to-row headers 6 in the short direction of the heat exchanger 1 is affected by the heat transfer tubes 2 inserted into the row-to-row headers 6. Therefore, for example, in the row-to-row headers 6, the pressure loss of the refrigerant flowing from point P3 to point P4 varies depending on the insertion length of the heat transfer tubes 2 into the row-to-row headers 6. Point P3 is a point directly above the heat transfer tube 2 in the first row 2A that is farthest from the first refrigerant pipe 11. Point P4 is a point directly above the heat transfer tube 2 in the second row 2B that is farthest from the second refrigerant pipe 12. Note that the change in pressure loss depending on the insertion length is not limited to the section between points P3 and P4 corresponding to the heat transfer tube 2 farthest from the refrigerant pipe.

[0023] As with the first lower header 4, the pressure loss of the refrigerant flowing through the second lower header 5 in the longitudinal direction of the heat exchanger 1 is affected by the heat transfer tubes 2 inserted into the second lower header 5. For this reason, for example, in the second lower header 5, the pressure loss of the refrigerant flowing from point P5 to point P6 varies depending on the insertion length of the heat transfer tubes 2 into the second lower header 5. Point P5 is a point directly below the heat transfer tube 2 in the second row 2B that is farthest from the second refrigerant pipe 12. Point P6 is a point directly below the heat transfer tube 2 in the second row 2B that is closest to the second refrigerant pipe 12.

[0024] The insertion length of the heat transfer tubes 2 and the improvement of the distribution performance of the heat exchanger 1 will be described using FIG. 4 . FIG. 4 is a cross-sectional view of the heat exchanger 1 according to the first embodiment. FIG. 4 shows a cross section of the heat exchanger 1 cut along the YZ plane. As shown in FIG. 4 , the insertion length t1 of the heat transfer tubes 2 inserted into the first lower header 4 corresponds to the length from the upper surface of the first lower header 4 to the lower ends of the heat transfer tubes 2. Although not shown, the insertion length of the heat transfer tubes 2 inserted into the second lower header 5 also corresponds to the vertical length from the upper surface of the second lower header 5 to the lower ends of the heat transfer tubes 2. Furthermore, the insertion length t2 of the heat transfer tubes 2 inserted into the row-to-row header 6 corresponds to the vertical length from the lower surface of the row-to-row header 6 to the upper ends of the heat transfer tubes 2.

[0025] In the heat exchanger 1, the average insertion length tm1 of the heat transfer tubes 2 inserted into the first lower header 4 is shorter than the average insertion length tm2 of the heat transfer tubes 2 inserted into the row-to-row headers 6. Note that the average insertion length of the heat transfer tubes 2 inserted into the second lower header 5 instead of the first lower header 4 may be shorter than the average insertion length tm2 of the heat transfer tubes 2 inserted into the row-to-row headers 6. Furthermore, the average insertion length of the heat transfer tubes 2 inserted into both the first lower header 4 and the second lower header 5 may be shorter than the average insertion length tm2 of the heat transfer tubes 2 inserted into the row-to-row headers 6.

[0026] In the first embodiment, by making the insertion length of the lower header shorter than the insertion length of the upper header, the insertion length of the heat transfer tubes 2 inserted into the lower header is limited so as not to become excessively long. Therefore, while the cross-sectional area of ​​the flow path of the lower header changes depending on the portion of the heat transfer tubes 2 protruding into the lower header, the change in cross-sectional area is reduced by reducing the amount of heat transfer tubes 2 inserted into the lower header. This reduces the pressure loss of the refrigerant flowing through the lower header. Furthermore, by making the insertion length of the lower header shorter than the insertion length of the upper header, the insertion length of the heat transfer tubes 2 inserted into the upper header is limited so as not to become excessively short. This increases the pressure loss of the refrigerant flowing through the upper header.

[0027] A common problem with heat exchangers 1 is that a difference in the amount of refrigerant distributed between heat transfer tubes 2 located near the refrigerant pipe that introduces refrigerant into the header and heat transfer tubes 2 located farther from the refrigerant pipe. In contrast, in the first embodiment, the pressure loss of the refrigerant flowing through the lower header is reduced, and the pressure loss of the refrigerant flowing through the upper header is increased. Therefore, in the first embodiment, the refrigerant flowing from the first refrigerant pipe 11 to the lower header is less likely to flow from the lower header to the heat transfer tubes 2, but is more likely to flow to the back of the lower header (the portion farther from the first refrigerant pipe 11). In other words, in the first embodiment, the amount of refrigerant flowing from the lower header toward the heat transfer tubes 2 inserted near the first refrigerant pipe 11 is reduced compared to the first embodiment, in which the pressure losses of the lower and upper headers are not adjusted. The reduced amount of refrigerant then flows deeper into the lower header, increasing the amount of refrigerant flowing toward the heat transfer tubes 2 inserted farther from the first refrigerant pipe 11. Therefore, in the lower header, the amount of refrigerant distributed can be made similar between the heat transfer tubes 2 inserted at a position far from the first refrigerant pipe 11 and the heat transfer tubes 2 inserted at a position close to the first refrigerant pipe 11.

[0028] As described above, according to the heat exchanger 1 of the first embodiment, the insertion length of the lower header is shorter than the insertion length of the upper header. Therefore, even when the heat transfer tubes 2 are evenly arranged in the longitudinal direction, the heat exchanger 1 can distribute the refrigerant evenly between the heat transfer tubes 2 inserted far from the first refrigerant pipe 11 and the heat transfer tubes 2 inserted close to the first refrigerant pipe 11. Therefore, according to the heat exchanger 1 of the first embodiment, it is possible to improve the refrigerant distribution performance while suppressing a decrease in the workability of the headers.

[0029] Embodiment 2. Embodiment 2 differs from embodiment 1 in that an upper limit is set for the insertion length of the heat transfer tubes 2 into the row headers 6. The following mainly describes the differences from embodiment 1, and the same or corresponding parts as embodiment 1 are denoted by the same reference numerals and will not be described again.

[0030] FIG. 5 is a diagram illustrating the upper limit of the insertion length of the heat transfer tubes 2 according to the second embodiment. As shown in FIG. 5 , the distance between the upper inner wall surface 62a (the inner wall surface of the cover plate 62) constituting the upper portion of the interior of the row header 6 and the upper end of the heat transfer tube 2 is defined as δ. The distance between the upper inner wall surface 62a and the lower inner wall surface 61a (the bottom surface of the base 61) constituting the lower portion of the interior of the row header 6 is defined as δy. That is, δ is the length obtained by subtracting the insertion length t2 from δy. In this case, in the second embodiment, δ / δy≦0.75, and preferably 0.6≦δ / δy≦0.75. Note that δ may be the average distance between the plurality of heat transfer tubes 2 and the upper inner wall surface 62a.

[0031] FIG. 6 is a graph showing the relationship between δ / δy and pressure loss. In the first embodiment, it was explained that limiting the insertion length of the heat transfer tubes 2 inserted into the row-by-row header 6 so as not to be excessively short can make the amount of refrigerant distributed to the multiple heat transfer tubes 2 in the lower header more uniform. However, the graph in FIG. 6 shows that the slope of the pressure loss in the row-by-row header 6 becomes steep when δ / δy exceeds 0.75. If the pressure loss in the row-by-row header 6 becomes excessively large, the velocity of the refrigerant flowing through the heat transfer tubes 2 may decrease significantly, resulting in a deterioration in the heat exchange performance of the heat exchanger 1. According to the second embodiment, as described above, by satisfying δ / δy≦0.75, it is possible to prevent the pressure loss from becoming excessively large and the heat exchange performance of the heat exchanger 1 from decreasing.

[0032] 6 also shows that the slope of the pressure loss in the row-to-row headers 6 becomes smaller when δ / δy is below 0.6. When the pressure loss in the row-to-row headers 6 becomes smaller, the bias in the amount of refrigerant distributed to the heat transfer tubes 2 inserted in the first lower header 4 close to the first refrigerant pipe 11 and into which the refrigerant easily flows becomes greater. According to the second embodiment, as described above, a lower limit value of a more preferable range of δ / δy may be set to 0.6≦δ / δy≦0.75. In this case, the amount of refrigerant distributed can be made closer between the heat transfer tubes 2 inserted in the lower header far from the first refrigerant pipe 11 and the heat transfer tubes 2 inserted in the lower header close to the first refrigerant pipe 11.

[0033] Embodiment 3. Figure 7 is a cross-sectional view of a heat exchanger 1A according to embodiment 3. Figure 7 shows a cross section of the heat exchanger 1A cut along the YZ plane. As shown in Figure 7, embodiment 3 differs from embodiment 1 in that an inner tube 7 is inserted inside the first lower header 4. The following description will focus on the differences from embodiment 1, and the same or corresponding parts as in embodiment 1 will be denoted by the same reference numerals and will not be described again.

[0034] The inner pipe 7 has a hollow cylindrical shape and is formed with a plurality of orifices 71. The interior space of the inner pipe 7 is in communication with the interior space of the first refrigerant pipe 11, and the refrigerant flows into the inner pipe 7 through the first refrigerant pipe 11. The plurality of orifices 71 are formed at intervals in the axial direction of the inner pipe 7. The inner pipe 7 may be provided in the second lower header 5 instead of the first lower header 4. Alternatively, the inner pipe 7 may be provided in both the first lower header 4 and the second lower header 5.

[0035] According to the third embodiment, by providing the inner tube 7, the refrigerant that has flowed into the inner tube 7 in the first lower header 4 is ejected through the plurality of orifices into the space between the inner tube 7 and the first lower header 4, and flows from this space into the plurality of heat transfer tubes 2. As a result, the refrigerant passing through the space between the inner tube 7 and the first lower header 4 is mixed, and the phase state of the refrigerant flowing through the plurality of heat transfer tubes 2 is homogenized. Therefore, it is possible to suppress a decrease in heat exchange performance downstream of the position where the inner tube 7 is provided.

[0036] Furthermore, in general, there may be differences in insertion length among the heat transfer tubes 2 during assembly of the heat exchanger 1A. According to the third embodiment, the inner tube 7 is inserted into the lower header, which prevents the heat transfer tubes 2 from being inserted too far into the lower header. In other words, providing the inner tube 7 in the lower header improves the positioning of the heat transfer tubes 2.

[0037] Fourth Embodiment Fig. 8 is a cross-sectional view of a heat exchanger 1B according to a fourth embodiment. Fig. 8 shows a cross section of the heat exchanger 1B cut along the YZ plane. As shown in Fig. 8, the fourth embodiment differs from the third embodiment in that the insertion length of the heat transfer tubes 2 into the row headers 6 is changed depending on the insertion position of the heat transfer tubes 2. The following description will focus on the differences from the third embodiment, and the same or corresponding parts as those in the third embodiment will be denoted by the same reference numerals and will not be described again.

[0038] The heat transfer tubes 2 forming the first row 2A are inserted into the row header 6 so that their insertion lengths gradually decrease with increasing distance from the first refrigerant pipe 11. Therefore, in the row header 6, the insertion length of the first heat transfer tube 2a inserted closer to the first refrigerant pipe 11 is longer than the insertion length of the second heat transfer tube 2b inserted farther from the first refrigerant pipe 11 than the first heat transfer tube 2a. The first heat transfer tube 2a is, for example, the heat transfer tube 2 inserted closest to the first refrigerant pipe 11 among the multiple heat transfer tubes 2. The second heat transfer tube 2b is, for example, the heat transfer tube 2 inserted farthest from the first refrigerant pipe 11 among the multiple heat transfer tubes 2.

[0039] In the row-to-row header 6, by making the insertion length of the first heat transfer tube 2a in the first row 2A longer than the insertion length of the second heat transfer tube 2b in the first row 2A, the pressure loss at the location where the first heat transfer tube 2a is inserted can be made higher than the pressure loss at the location where the second heat transfer tube 2b is inserted. As a result, the refrigerant flows more slowly through the first heat transfer tube 2a, reducing the amount of refrigerant distributed from the first lower header 4 to the first heat transfer tube 2a. The reduced amount of refrigerant flows from the first heat transfer tube 2a toward the heat transfer tube 2 farther from the first refrigerant pipe 11. Therefore, in the first lower header 4, the amount of refrigerant distributed can be made closer to the heat transfer tube 2 inserted farther from the first refrigerant pipe 11 than to the heat transfer tube 2 inserted close to the first refrigerant pipe 11.

[0040] In the row header 6, the insertion length of the first heat transfer tube 2a may be longer than the insertion length of the second heat transfer tube 2b, so that the heat transfer tube 2 may come into contact with the inner tube 7. However, in the fourth embodiment, the inner tube 7 may be omitted.

[0041] Alternatively, the plurality of heat transfer tubes 2 forming the second row 2B, rather than the first row 2A, may be inserted into the row-to-row header 6 so that their insertion lengths become gradually shorter as they become farther from the second refrigerant pipe 12. Furthermore, both the plurality of heat transfer tubes 2 forming the first row 2A and the plurality of heat transfer tubes 2 forming the second row 2B may be inserted into the row-to-row header 6 so that their insertion lengths become gradually shorter as they become farther from the second refrigerant pipe 12.

[0042] Furthermore, when the lengths of the heat transfer tubes 2 themselves are allowed to be changed, the inserted length of the heat transfer tubes 2 forming the first row 2A in the first lower header 4 may also be gradually shortened as the distance from the first refrigerant pipe 11 increases. That is, longer heat transfer tubes 2 may be inserted into the first lower header 4 and the row-to-row header 6 as the distance from the first refrigerant pipe 11 increases. In this case, the pressure loss of the refrigerant flowing at a position far from the first refrigerant pipe 11 in the first lower header 4 can be reduced with priority over the pressure loss of the refrigerant flowing at a position close to the first refrigerant pipe 11. Therefore, the refrigerant distribution amount can be made similar between the heat transfer tubes 2 inserted at a position far from the first refrigerant pipe 11 in the first lower header 4 and the heat transfer tubes 2 inserted at a position close to the first refrigerant pipe 11. Note that the inserted length of the heat transfer tubes 2 forming the second row 2B in the second lower header 5, rather than the first lower header 4, may also be gradually shortened as the distance from the second refrigerant pipe 12 increases. In addition, in both the first lower header 4 and the second lower header 5, the insertion length of the multiple heat transfer tubes 2 may be gradually shortened as they become farther away from the first refrigerant pipe 11 or the second refrigerant pipe 12.

[0043] However, in any of the combinations of headers and heat transfer tubes 2 described above, the insertion length may be changed every several heat transfer tubes 2 rather than for each individual heat transfer tube 2 .

[0044] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the configurations of the above embodiments and various modifications are possible within the scope of the technical concept. For example, in the heat exchanger 1 described in the third and fourth embodiments, an upper limit may be set for the insertion length of the heat transfer tubes 2 into the row headers 6, as described in the second embodiment.

[0045] Furthermore, in the first embodiment, the case where the heat transfer tubes 2 constitute the first row 2A and the second row 2B has been described, but the second row 2B of the heat transfer tubes 2 and the second lower header 5 may be omitted. In this case, the row-to-row header 6 is provided with the second refrigerant pipe 12 and functions as a header that allows the refrigerant that has joined from the first row 2A to flow out into the second refrigerant pipe 12. Furthermore, the heat transfer tubes 2 may not be flat tubes, but may be tubes of other shapes, such as circular tubes.

[0046] 1, 1A, 1B Heat exchanger, 2 Heat transfer tube, 2A First row, 2B Second row, 2a First heat transfer tube, 2b Second heat transfer tube, 3 Fin, 4 First lower header, 5 Second lower header, 6 Row-to-row header, 7 Inner tube, 11 First refrigerant piping, 12 Second refrigerant piping, 61 Base, 61a Lower inner wall surface, 62 Cover plate, 62a Upper inner wall surface, 71 Orifice, 100 Air conditioning device, 110 Outdoor unit, 111 Compressor, 112 Flow path switching valve, 113 Blower, 114 Expansion valve, 120 Indoor unit, 121 Heat exchanger, 122 Blower, 130 Refrigerant piping.

Claims

1. Multiple heat transfer tubes through which a refrigerant flows, A lower header into which the lower ends of multiple heat transfer tubes are inserted and to which refrigerant piping for introducing refrigerant is connected, An upper header into which the upper ends of multiple heat transfer tubes are inserted, The average insertion length of the multiple heat transfer tubes inserted into the lower header is shorter than the average insertion length of the multiple heat transfer tubes inserted into the upper header. Let δ be the distance between the upper inner wall surface that constitutes the upper part of the inner surface of the upper header and the upper end of the heat transfer tube. If δy is the distance between the upper inner wall surface and the lower inner wall surface that constitutes the lower part of the inner surface of the upper header, then 0.6 ≤ (δy - δ) / δy ≤ 0.

75. heat exchanger.

2. As the aforementioned lower header, The first lower header and, A second lower header is provided, The upper header relays the flow of refrigerant between the heat transfer tube inserted in the first lower header and the heat transfer tube inserted in the second lower header. The heat exchanger according to claim 1.

3. The lower header is provided with an inner tube having an orifice formed inside. A heat exchanger according to claim 1 or 2.

4. The lower header is provided with an inner tube having an orifice formed therein, The inner pipe is provided in the first lower header and the second lower header. The heat exchanger according to claim 2.

5. The plurality of heat transfer tubes include a first heat transfer tube and a second heat transfer tube inserted in the upper header at a position further from the refrigerant piping than the first heat transfer tube. The insertion length of the first heat transfer tube into the upper header is longer than the insertion length of the second heat transfer tube into the upper header. A heat exchanger according to claim 1 or 2.

6. The plurality of heat transfer tubes include a first heat transfer tube and a second heat transfer tube inserted in the lower header at a position further from the refrigerant piping than the first heat transfer tube. The insertion length of the first heat transfer tube into the lower header is longer than the insertion length of the second heat transfer tube into the lower header. A heat exchanger according to claim 1 or 2.

7. A heat exchanger according to claim 1 or 2, Compressor and, Expansion valve and, The heat exchanger comprises a heat exchanger that functions as an evaporator when the heat exchanger functions as a condenser, and a heat exchanger that functions as a condenser when the heat exchanger functions as an evaporator. Refrigeration cycle device.

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