EP4290170A1

EP4290170A1 - Heat exchanger and refrigeration cycle apparatus equipped with same

Info

Publication number: EP4290170A1
Application number: EP21924628.7A
Authority: EP
Inventors: Atsushi Morita; Tsuyoshi Maeda; Shin Nakamura; Akira YATSUYANAGI
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2021-02-04
Filing date: 2021-02-04
Publication date: 2023-12-13
Also published as: CN116802453A; WO2022168232A1; JPWO2022168232A1; US20240003636A1; EP4290170A4; JP7483062B2

Abstract

A flat heat transfer tube (21) in an outdoor heat exchanger (11) includes a main body (23) and a connecting portion (25). The flat heat transfer tube (21) has a plurality of flow paths (27) spaced from each other. The flat heat transfer tube (21) has a first side portion (29a) and a second side portion (29b) spaced from each other by a width. The connecting portion (25) connected to an opening (33) of a header (31) has an opening end face (26) in which each of the flow paths (27) opens. In the connecting portion (25), the first side portion (29a) is tapered toward the opening end face (26) to be reduced in width. A first opening end (28a) of a first flow path (27a) located closest to the first side portion (29a) has a second flow path cross-sectional area (S2) smaller than a first flow path cross-sectional area (S 1) of an opening end (28) of each of other flow paths (27).

Description

TECHNICAL FIELD

The present disclosure relates to a heat exchanger and a refrigeration cycle apparatus including the same.

BACKGROUND ART

An exemplary embodiment of a heat exchanger used in an air conditioner is a heat exchanger applying a flat heat transfer tube having a flat shape and provided with a plurality of flow paths through which refrigerant flows. When this type of heat exchanger is operated to function as an evaporator, it requires a larger amount of refrigerant to flow through a flow path located on the windward side in order to improve the heat transfer performance. For example, PTL 1 proposes a heat exchanger including a flat heat transfer tube in which a flow path located on the windward side is broader than a flow path located on the leeward side.

CITATION LIST

PATENT LITERATURE

PTL 1: Japanese Patent Laying-Open No. 2015-90219

SUMMARY OF INVENTION

TECHNICAL PROBLEM

The flat heat transfer tube is manufactured, for example, by extrusion molding of a material such as aluminum. In the case of the flat heat transfer tube in which the flow path located on the windward side is broader than the flow path located on the leeward side, for example, its cross-sectional shape becomes asymmetrical, which may make it difficult to manufacture a desired flat heat transfer tube. The heat exchanger needs to be improved in manufacturability while ensuring heat transfer performance.
The present disclosure has been made as part of such a development. One object of the present disclosure is to provide a heat exchanger improved in manufacturability while ensuring heat transfer performance, and another object thereof is to provide a refrigeration cycle apparatus to which such a heat exchanger is applied.

SOLUTION TO PROBLEM

A heat exchanger according to the present disclosure includes a flat heat transfer tube having a flat shape, a header, and a heat dissipation fin. The flat heat transfer tube having a flat shape has a first side portion and a second side portion spaced from each other by a width in a first direction, and extends in a second direction crossing the first direction. The flat heat transfer tube has a plurality of flow paths each extending in the second direction, the flow paths being spaced from each other in the first direction. The header has an opening to which the flat heat transfer tube is connected. The flat heat transfer tube includes a main body and a connecting portion. The main body is attached to the heat dissipation fin. The connecting portion has an opening end face at which each of the flow paths opens. The connecting portion is inserted into the opening of the header and connected to the header. In the main body, each of the flow paths has a first flow path cross-sectional area. In the connecting portion, the first side portion is tapered toward the opening end face to be reduced in the width. In the opening end face, a first opening end of a first flow path located closest to the tapered first side portion among the flow paths has a second flow path cross-sectional area smaller than the first flow path cross-sectional area.
A refrigeration cycle apparatus according to the present disclosure includes the heat exchanger.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the heat exchanger of the present disclosure, the flat heat transfer tube includes a main body and a connecting portion. The flat heat transfer tube has a plurality of flow paths spaced from each other. The flat heat transfer tube has a first side portion and a second side portion spaced from each other by a width. The connecting portion connected to the opening of the header has an opening end face at which each of the flow paths opens. In the connecting portion, the first side portion is tapered toward the opening end face to be reduced in width. Thereby, the connecting portion can be easily inserted into the opening of the header, which makes it possible to contribute to improvement in manufacturability. In the opening end face, the first opening end of the first flow path located closest to the first side portion has a second flow path cross-sectional area smaller than the first flow path cross-sectional area. This allows a larger amount of refrigerant to flow through the flow path located in the region under high thermal load, with the result that the heat transfer performance can be ensured.
According to the refrigeration cycle apparatus of the present disclosure, the heat exchanger is provided, so that the manufacturability can be improved while ensuring the heat transfer performance.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a diagram showing a refrigerant circuit of a refrigeration cycle apparatus including an outdoor heat exchanger according to each embodiment.
Fig. 2 is a perspective view showing an example of the outdoor heat exchanger according to each embodiment.
Fig. 3 is a partially cross-sectional top view showing a structure of a portion where a flat heat transfer tube is connected to a header in an outdoor heat exchanger according to a first embodiment.
Fig. 4 is a cross-sectional view taken along a cross-sectional line IV-IV shown in Fig. 3 in the first embodiment.
Fig. 5 is a front view showing an opening end face in a connecting portion of the flat heat transfer tube in the first embodiment.
Fig. 6 shows an example of a flowchart illustrating a method of manufacturing an outdoor heat exchanger in the first embodiment.
Fig. 7 is a partial top view showing one step of the method of manufacturing the outdoor heat exchanger in the first embodiment.
Fig. 8 is a partially cross-sectional top view showing a step performed after the step shown in Fig. 7 in the first embodiment.
Fig. 9 is a diagram for illustrating functions and effects of the outdoor heat exchanger in the first embodiment.
Fig. 10 is a partially cross-sectional top view showing a structure of a portion where a flat heat transfer tube is connected to a header in an outdoor heat exchanger according to a second embodiment.
Fig. 11 is a front view showing an opening end face in a connecting portion of the flat heat transfer tube in the second embodiment.
Fig. 12 is a partial top view showing one step of a method of manufacturing an outdoor heat exchanger in the second embodiment.
Fig. 13 is a partially cross-sectional top view showing a structure of a portion where a flat heat transfer tube is connected to a header in an outdoor heat exchanger according to a third embodiment.
Fig. 14 is a front view showing an opening end face in a connecting portion of the flat heat transfer tube in the third embodiment.
Fig. 15 is a partial top view showing one step of a method of manufacturing an outdoor heat exchanger in the third embodiment.
Fig. 16 is a partially cross-sectional partial top view showing a step performed after the step shown in Fig. 15 in the third embodiment.
Fig. 17 is a partially cross-sectional top view showing a structure of a portion where a flat heat transfer tube is connected to a header in an outdoor heat exchanger according to a fourth embodiment.
Fig. 18 is a front view showing an opening end face in a connecting portion of the flat heat transfer tube in the fourth embodiment.
Fig. 19 is a partial top view showing one step of a method of manufacturing an outdoor heat exchanger in the fourth embodiment.
Fig. 20 is a perspective view showing another example of the outdoor heat exchanger according to each embodiment.

DESCRIPTION OF EMBODIMENTS

The following first describes an example of a refrigerant circuit of a refrigeration cycle apparatus including a heat exchanger (an outdoor heat exchanger) according to each embodiment. As shown in Fig. 1, a refrigeration cycle apparatus 1 includes a compressor 3, an indoor heat exchanger 5, a fan 7, an expansion valve 9, an outdoor heat exchanger 11, a propeller fan 13, a four-way valve 15, and a refrigerant pipe 17 that connects these components. The structure of outdoor heat exchanger 11 will be described in detail in each embodiment.
The following describes the operation of the above-mentioned refrigeration cycle apparatus 1 in the case of a heating operation. The flow of refrigerant during a heating operation is indicated by a solid line. By driving compressor 3, high-temperature and high-pressure gas refrigerant is discharged from compressor 3. The discharged high-temperature and high-pressure gas refrigerant (a single phase) flows through four-way valve 15 into indoor heat exchanger 5.
Indoor heat exchanger 5 exchanges heat between the gas refrigerant flowing thereinto and the air fed thereinto by fan 7. The high-temperature and high-pressure gas refrigerant is condensed into high-pressure liquid refrigerant (a single phase). The heat-exchanged air is fed out from indoor heat exchanger 5 into an indoor side to heat the indoor side. The high-pressure liquid refrigerant fed out from indoor heat exchanger 5 is converted by expansion valve 9 into refrigerant in a two-phase state including low-pressure gas refrigerant and liquid refrigerant.
The refrigerant in the two-phase state flows into outdoor heat exchanger 11. Outdoor heat exchanger 11 functions as an evaporator. Outdoor heat exchanger 11 exchanges heat between the refrigerant in the two-phase state flowing thereinto and the air fed thereinto by propeller fan 13. From the refrigerant in the two-phase state, liquid refrigerant evaporates to become low-pressure gas refrigerant (a single phase). At this time, a larger amount of refrigerant flows through the refrigerant flow path located on the windward side than through the refrigerant flow path located on the leeward side. The low-pressure gas refrigerant is fed out from outdoor heat exchanger 11.
The low-pressure gas refrigerant fed out from outdoor heat exchanger 11 flows into compressor 3 through four-way valve 15. The low-pressure gas refrigerant having flowed into compressor 3 is compressed into high-temperature and high-pressure gas refrigerant, which is then discharged from compressor 3 again. This cycle is subsequently repeated.
The following describes the case of a cooling operation. By driving compressor 3, high-temperature and high-pressure gas refrigerant is discharged from compressor 3. The discharged high-temperature and high-pressure gas refrigerant (a single phase) flows into outdoor heat exchanger 11 through four-way valve 15. Outdoor heat exchanger 11 functions as a condenser. Outdoor heat exchanger 11 exchanges heat between the refrigerant flowing thereinto and the air fed thereinto by propeller fan 13. The high-temperature and high-pressure gas refrigerant is condensed into high-pressure liquid refrigerant (a single phase).
The high-pressure liquid refrigerant fed out from outdoor heat exchanger 11 is converted by expansion valve 9 into refrigerant in a two-phase state including low-pressure gas refrigerant and liquid refrigerant. The refrigerant in the two-phase state flows into indoor heat exchanger 5. Indoor heat exchanger 5 exchanges heat between the refrigerant in the two-phase state flowing thereinto and the air fed thereinto by fan 7. From the refrigerant in the two-phase state, liquid refrigerant evaporates to become low-pressure gas refrigerant (a single phase). The heat-exchanged air is fed out from indoor heat exchanger 5 into an indoor side to cool the indoor side.
The low-pressure gas refrigerant fed out from indoor heat exchanger 5 flows into compressor 3 through four-way valve 15. The low-pressure gas refrigerant having flowed into compressor 3 is compressed into high-temperature and high-pressure gas refrigerant, which is then discharged from compressor 3 again. This cycle is subsequently repeated. Then, the structure of outdoor heat exchanger 11 according to each embodiment will be described below. Each embodiment will be described with reference to an X-axis and a Y-axis for convenience of explanation.

First Embodiment

The following describes an example of an outdoor heat exchanger as a heat exchanger according to the first embodiment. As shown in Fig. 2, a housing 10 of an outdoor unit accommodates: outdoor heat exchanger 11 including a flat heat transfer tube 21 and a heat dissipation fin 41; and a header 31. In this case, a single row-type outdoor heat exchanger 11 is disposed. Further, housing 10 also accommodates propeller fan 13, compressor 3 (not shown), and the like. By driving propeller fan 13 (not shown), air flows inside housing 10 in the direction indicated by an arrow Y1.
As shown in Fig. 3, flat heat transfer tube 21 in outdoor heat exchanger 11 includes a main body 23 and a connecting portion 25. Flat heat transfer tube 21 has a width in a Y-axis direction as the first direction and extends in an X-axis direction as the second direction. In flat heat transfer tube 21, a plurality of flow paths 27 each extending in the X-axis direction are spaced from each other in the Y-axis direction (see Fig. 4).
Flat heat transfer tube 21 has a first side portion 29a and a second side portion 29b that are spaced from each other by a width. In this case, first side portion 29a is located on the leeward side while second side portion 29b is located on the windward side. Heat dissipation fin 41 is attached to main body 23.
Connecting portion 25 has an opening end face 26 at which an opening end 28 (see Fig. 5) of each of the plurality of flow paths 27 is located. In this case, opening end face 26 is located to extend in the Y-axis direction. Connecting portion 25 is connected to header 31 while being inserted into an opening 33 provided in header 31. First side portion 29a and second side portion 29b in connecting portion 25 are in contact with an opening inner wall surface 34 of opening 33. As shown in Fig. 4, in main body 23, each of the plurality of flow paths 27 has a first flow path cross-sectional area S1. As will be described later, when flat heat transfer tube 21 is manufactured, a molded body to be formed as main body 23 is first manufactured.
As shown in Figs. 3 and 5, connecting portion 25 is processed (shrunk) so as to shrink flat heat transfer tube 21 in a width direction (the Y-axis direction). In connecting portion 25, first side portion 29a is tapered toward opening end face 26 to be reduced in width. At opening end face 26, a first opening end 28a of a first flow path 27a located closest to first side portion 29a among flow paths 27 arranged in the Y-axis direction is narrowed in the Y-axis direction so as to conform to the tapered first side portion 29a.
Thus, first opening end 28a of first flow path 27a has a second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27. In other words, first opening end 28a of first flow path 27a located closest to first side portion 29a has second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27. Outdoor heat exchanger 11 according to the first embodiment is configured as described above.
The following describes an example of a method of manufacturing outdoor heat exchanger 11 described above based on a flowchart. As shown in Fig. 6, in step T1, a material to be formed as a flat heat transfer tube is first prepared. Then, in step T2, the material is introduced into an extruder. Then, in step T3, the material introduced into the extruder is extruded to thereby produce molded body 20 (see Fig. 7) to be formed as a flat heat transfer tube.
At this time, by performing extrusion molding such that each of flow paths 27 (see Fig. 4) has first flow path cross-sectional area S1, molded body 20 (see Fig. 7) is formed to have a cross-sectional shape that is line-symmetric with respect to the center line in the width direction as shown by the cross-sectional shape of main body 23 (see Fig. 4). This allows uniform extrusion of the material, for example, to make it possible to produce a molded body with no void.
Then, in step T4, molded body 20 is cut and shrunk (see Fig. 7). As shown in Fig. 7, in this case, molded body 20 is cut in the Y-axis direction. At the cut surface of this cut molded body 20, each of flow paths 27 (see Fig. 4 and the like) opens as opening end face 26.
At this time, molded body 20 is cut as well as shrunk. Specifically, pressure is applied (see an arrow P1), for example, with a plate member (not shown) or the like to first side portion 29a of molded body 20 so as to taper this first side portion 29a such that molded body 20 is reduced in width toward opening end face 26.
Since first side portion 29a is tapered, at opening end face 26, first opening end 28a of first flow path 27a located closest to first side portion 29a among the plurality of flow paths 27 is narrowed in the Y-axis direction (see Fig. 5). Thus, first opening end 28a of first flow path 27a located closest to first side portion 29a is to have second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27. In this way, flat heat transfer tube 21 including main body 23 and connecting portion 25 is completed (step T5).
Then, in step T6, flat heat transfer tube 21 is connected to header 31 (see Fig. 8). As shown in Fig. 8, connecting portion 25 of flat heat transfer tube 21 is inserted into opening 33 provided in header 31 as shown by an arrow P3, and first side portion 29a and second side portion 29b are brought into contact with opening inner wall surface 34 of opening 33.
At this time, since first side portion 29a is tapered, connecting portion 25 is easily inserted into opening 33 of header 31. Further, the length of the portion of connecting portion 25 that is inserted into header 31 is uniquely defined, so that connecting portion 25 can be prevented, for example, from being inserted more than necessary into opening 33 of header 31. Thus, attachment of flat heat transfer tube 21 onto header 31 ends, and the main part of outdoor heat exchanger 11 is completed.
According to the above-described outdoor heat exchanger 11, when manufacturing a molded body to be formed as flat heat transfer tube 21, a molded body having a cross-sectional shape that is line-symmetric with respect to the center line in the width direction is first molded as shown by the cross-sectional shape of main body 23 (see Fig. 4). This allows uniform extrusion of the material, for example, to make it possible to produce a molded body with no void, and also possible to contribute to improvement in manufacturability of outdoor heat exchanger 11.
Then, flat heat transfer tube 21 manufactured from the molded body is provided with tapered first side portion 29a, so that the manufacturability can be improved while ensuring the heat transfer performance, which will be described below.
As shown in Fig. 2, in outdoor heat exchanger 11 in refrigeration cycle apparatus 1, heat is exchanged between the air fed into outdoor heat exchanger 11 (see arrow Y1) and the refrigerant flowing through flat heat transfer tube 21. When outdoor heat exchanger 11 functions as an evaporator, the air fed into outdoor heat exchanger 11 exchanges heat with the refrigerant flowing through flat heat transfer tube 21, and thus, the temperature of the air lowers from the windward side to the leeward side.
In other words, as shown in Fig. 9 (in the middle stage), the thermal load decreases with increasing ventilation distance in which air flows from the windward side to the leeward side. In the region (range) under high thermal load, heat exchange between air and refrigerant is actively performed. Thus, in the case where a heat exchanger functions as an evaporator, if the refrigerant is completely gasified by heat exchange with air, the heat transfer performance cannot be improved.
Thus, as shown in Fig. 9 (in the upper stage), processing (shrinking) is performed onto the cut portion of molded body 20 to be formed as connecting portion 25 of flat heat transfer tube 21 with respect to the portion to be formed as a main body of flat heat transfer tube 21 such that the flow rate of the refrigerant flowing on the windward side is higher than the flow rate of the refrigerant flowing on the leeward side. In other words, first side portion 29a is processed (shrunk) to be tapered toward opening end face 26 to be reduced in width (from a width W1 to a width W2).
Therefore, in connecting portion 25 of flat heat transfer tube 21, first opening end 28a of first flow path 27a located closest to first side portion 29a located on the leeward side is to be narrowed in the Y-axis direction so as to conform to the tapered first side portion 29a. Thereby, first opening end 28a is to have second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27.
By the structure in which second flow path cross-sectional area S2 of first opening end 28a of first flow path 27a located on the leeward side is smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27, as shown in Fig. 9 (in the lower stage), the refrigerant less easily flows through first flow path 27a, and accordingly, more refrigerant flows through flow path 27 located on the windward side or the like under high thermal load, so that complete gasification of the refrigerant can be suppressed. As a result, the heat transfer performance as outdoor heat exchanger 11 can be ensured.
Further, in outdoor heat exchanger 11 as described above, first side portion 29a of connecting portion 25 of flat heat transfer tube 21 connected to header 31 is tapered, which makes it easy to insert it into opening 33 formed in header 31. This makes it possible to contribute to improvement in manufacturability of outdoor heat exchanger 11.
Further, since the tapered first side portion 29a of connecting portion 25 comes into contact with opening inner wall surface 34 of opening 33, the length of the portion of connecting portion 25 (flat heat transfer tube 21) that is inserted into header 31 is uniquely defined. Thereby, connecting portion 25 can be prevented, for example, from being inserted more than necessary into opening 33 of header 31. This can consequently contribute to stabilization of the flow of the refrigerant inside header 31.

Second Embodiment

The following describes an example of an outdoor heat exchanger as a heat exchanger according to the second embodiment. As shown in Figs. 10 and 11, opening end face 26 of flat heat transfer tube 21 is located to extend from first side portion 29a to second side portion 29b in a third direction inclined toward main body 23 with respect to the Y-axis direction.
In connecting portion 25 of flat heat transfer tube 21, first side portion 29a is tapered toward opening end face 26 to be reduced in width. First opening end 28a of first flow path 27a located closest to first side portion 29a has second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27.
Since the configurations other than the above are the same as those of outdoor heat exchanger 11 shown in Figs. 3 to 5, the same members are denoted by the same reference characters, and the description thereof will not be repeated unless necessary.
The following describes an example of a method of manufacturing outdoor heat exchanger 11 described above. After the processes similar to those in steps T1, T2, and T3 shown in Fig. 6 are performed, the molded body is cut and shrunk (step T4).
As shown in Fig. 12, in this case, molded body 20 is cut in a direction inclined with respect to the Y-axis direction. At the cut surface of the cut molded body 20, each of the plurality of flow paths 27 (see Fig. 11) opens as opening end face 26. At this time, molded body 20 is cut as well as shrunk. Specifically, pressure is applied (see arrow P1), for example, with a plate member (not shown) or the like to first side portion 29a of molded body 20 so as to taper this first side portion 29a such that molded body 20 is reduced in width toward opening end face 26.
By the tapered first side portion 29a, at opening end face 26, first opening end 28a of first flow path 27a located closest to first side portion 29a among the plurality of flow paths 27 is to have second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27. In this way, flat heat transfer tube 21 including main body 23 and connecting portion 25 is completed (step T5). Then, through the similar process in step T6, attachment of flat heat transfer tube 21 onto header 31 ends, and the main part of outdoor heat exchanger 11 is completed.
According to outdoor heat exchanger 11 described above, the following effects are achieved in addition to the effects achieved by outdoor heat exchanger 11 described in the first embodiment.
In connecting portion 25 of flat heat transfer tube 21 of outdoor heat exchanger 11 described above, opening end face 26 is located to extend from first side portion 29a located on the leeward side to second side portion 29b located on the windward side in the direction inclined toward main body 23 with respect to the Y-axis direction.
Thus, second flow path 27b located on the leeward side is longer than first flow path 27a located on the windward side. Thereby, the flow path resistance (friction resistance) of second flow path 27b located on the leeward side becomes higher than the flow path resistance (friction resistance) of first flow path 27a located on the windward side, so that the refrigerant easily flows through second flow path 27b located on the windward side.
Thus, by the tapered first side portion 29a, a still larger amount of refrigerant flows through flow path 27 located on the windward side under high thermal load in combination with the effect of making the refrigerant less easily flow through first flow path 27a located on the leeward side. As a result, the heat transfer performance as outdoor heat exchanger 11 can be improved.

Third Embodiment

The following describes an example of an outdoor heat exchanger as a heat exchanger according to the third embodiment. As shown in Figs. 13 and 14, opening end face 26 of flat heat transfer tube 21 is located to extend in the Y-axis direction.
In connecting portion 25 of flat heat transfer tube 21, first side portion 29a is tapered toward opening end face 26 to be reduced in width. First opening end 28a of first flow path 27a located closest to first side portion 29a has second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27.
Further, in connecting portion 25, second side portion 29b is tapered toward opening end face 26 to be reduced in width. Second opening end 28b of second flow path 27b located closest to second side portion 29b has a third flow path cross-sectional area S3 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27 and larger than second flow path cross-sectional area S2.
Since the configurations other than the above are the same as those of outdoor heat exchanger 11 shown in Figs. 3 to 5, the same members are denoted by the same reference characters, and the description thereof will not be repeated unless necessary.
The following describes an example of a method of manufacturing outdoor heat exchanger 11 described above. After the processes similar to those in steps T1, T2, and T3 shown in Fig. 6 are performed, the molded body is cut and shrunk (step T4).
As shown in Fig. 15, molded body 20 is cut in the Y-axis direction. At the cut surface of the cut molded body 20, each of the plurality of flow paths 27 (see Fig. 14) opens as opening end face 26. At this time, along with cutting of molded body 20, first side portion 29a and second side portion 29b in molded body 20 are tapered toward opening end face 26 such that molded body 20 is reduced in width.
First side portion 29a is tapered by applying pressure (pressure A: see an arrow P1). Also, second side portion 29b is tapered by applying pressure lower than pressure A (pressure B: see an arrow P2).
Under the condition that the magnitude relation of the pressure applied for tapering is pressure A > pressure B, at opening end face 26, second opening end 28b of second flow path 27b located closest to second side portion 29b is shorter in length narrowed in the Y-axis direction than first opening end 28a of first flow path 27a located closest to first side portion 29a.
Thereby, as shown in Fig. 14, second opening end 28b of second flow path 27b is formed to have third flow path cross-sectional area S3 larger than second flow path cross-sectional area S2 of first opening end 28a of first flow path 27a. Thus, flat heat transfer tube 21 including main body 23 and connecting portion 25 is completed (step T5).
Then, in step T6, flat heat transfer tube 21 is connected to header 31 (see Fig. 16). As shown in Fig. 16, connecting portion 25 of flat heat transfer tube 21 is inserted into opening 33 provided in header 31 as shown by an arrow P3, and first side portion 29a and second side portion 29b are brought into contact with opening inner wall surface 34 of opening 33.
At this time, since both first side portion 29a and second side portion 29b are tapered, connecting portion 25 is easily inserted into opening 33 of header 31. Further, the length of the portion of connecting portion 25 that is inserted into header 31 is uniquely defined, so that connecting portion 25 can be prevented, for example, from being inserted more than necessary into opening 33 of header 31. Thus, attachment of flat heat transfer tube 21 onto header 31 ends, and the main part of outdoor heat exchanger 11 is completed.
According to outdoor heat exchanger 11 described above, the following effects are achieved in addition to the effects achieved by outdoor heat exchanger 11 described in the first embodiment.
In connecting portion 25 in flat heat transfer tube 21 of outdoor heat exchanger 11 as described above, first side portion 29a and second side portion 29b each are tapered. Thereby, when connecting portion 25 of flat heat transfer tube 21 is connected to header 31, this connecting portion 25 is more easily inserted into opening 33 provided in header 31 as compared with the case where only first side portion 29a is tapered. This can consequently contribute to improvement in manufacturability of outdoor heat exchanger 11.
Further, when the tapered first side portion 29a and the tapered second side portion 29b in connecting portion 25 come into contact with opening inner wall surface 34 of opening 33, the length of the portion of connecting portion 25 (flat heat transfer tube 21) that is inserted into header 31 is more reliably defined. Thereby, connecting portion 25 can be prevented from being inserted more than necessary into opening 33 of header 31. This can consequently contribute to stabilization of the flow of the refrigerant inside header 31.
Further, at opening end face 26 in connecting portion 25, second opening end 28b of second flow path 27b located closest to second side portion 29b has third flow path cross-sectional area S3 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27 and larger than second flow path cross-sectional area S2.
Thereby, for second flow path 27b located on the windward side through which a larger amount of refrigerant is required to flow, second side portion 29b on the windward side is tapered to thereby make it possible to minimize that the refrigerant less easily flows through second flow path 27b. As a result, the heat transfer performance as outdoor heat exchanger 11 can be maintained.

Fourth Embodiment

The following describes an example of an outdoor heat exchanger as a heat exchanger according to the fourth embodiment. As shown in Figs. 17 and 18, opening end face 26 of flat heat transfer tube 21 is located to extend from first side portion 29a to second side portion 29b in the third direction inclined toward main body 23 with respect to the Y-axis direction.
In connecting portion 25 of flat heat transfer tube 21, first side portion 29a is tapered toward opening end face 26 to be reduced in width. First opening end 28a of first flow path 27a located closest to first side portion 29a has second flow path cross-sectional area S2 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27.
Second side portion 29b is tapered toward opening end face 26 to be reduced in width. Second opening end 28b of second flow path 27b located closest to second side portion 29b has third flow path cross-sectional area S3 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27 and larger than second flow path cross-sectional area S2.
Since the configurations other than the above are the same as those of outdoor heat exchanger 11 shown in Figs. 3 to 5, the same members are denoted by the same reference characters, and the description thereof will not be repeated unless necessary.
The following describes an example of a method of manufacturing outdoor heat exchanger 11 described above. After the processes similar to those in steps T1, T2, and T3 shown in Fig. 6 are performed, the molded body is cut and shrunk (step T4).
As shown in Fig. 19, in this case, molded body 20 is cut in a direction inclined with respect to the Y-axis direction. At the cut surface of the cut molded body 20, each of the plurality of flow paths 27 (see Fig. 18) opens as opening end face 26. At this time, along with cutting of molded body 20, first side portion 29a and second side portion 29b in molded body 20 are tapered toward opening end face 26 such that molded body 20 is reduced in width.
First side portion 29a is tapered by applying pressure (pressure A: see an arrow P1). Also, second side portion 29b is tapered by applying pressure lower than pressure A (pressure B: see an arrow P2).
Under the condition that the magnitude relation of the pressure applied for tapering is pressure A > pressure B, at opening end face 26, second opening end 28b of second flow path 27b located closest to second side portion 29b is shorter in length narrowed in the Y-axis direction than first opening end 28a of first flow path 27a located closest to first side portion 29a.
Thereby, as shown in Fig. 18, second opening end 28b of second flow path 27b is formed to have third flow path cross-sectional area S3 larger than second flow path cross-sectional area S2 of first opening end 28a of first flow path 27a. Thus, flat heat transfer tube 21 including main body 23 and connecting portion 25 is completed (step T5).
Then, in step T6, flat heat transfer tube 21 is connected to header 31. At this time, since both first side portion 29a and second side portion 29b are tapered, connecting portion 25 is easily inserted into opening 33 of header 31. Further, the length of the portion of connecting portion 25 that is inserted into header 31 is uniquely defined, so that connecting portion 25 can be prevented, for example, from being inserted more than necessary into opening 33 of header 31. Thus, attachment of flat heat transfer tube 21 onto header 31 ends, and the main part of outdoor heat exchanger 11 is completed.
Outdoor heat exchanger 11 described above can achieve both the effect achieved by outdoor heat exchanger 11 described in the second embodiment and the effect achieved by outdoor heat exchanger 11 described in the third embodiment.
In connecting portion 25 in flat heat transfer tube 21 of outdoor heat exchanger 11 described above, opening end face 26 is located to extend from first side portion 29a to second side portion 29b in the direction inclined toward main body 23 with respect to the Y-axis direction.
Thereby, first flow path 27a becomes longer than second flow path 27b, and the flow path resistance (friction resistance) of first flow path 27a becomes higher than the flow path resistance (friction resistance) of second flow path 27b, so that the refrigerant easily flows through second flow path 27b located on the windward side.
Further, in connecting portion 25, both first side portion 29a and second side portion 29b are tapered. At opening end face 26 in connecting portion 25, second opening end 28b of second flow path 27b located closest to second side portion 29b has third flow path cross-sectional area S3 smaller than first flow path cross-sectional area S1 of opening end 28 of each of other flow paths 27 and larger than second flow path cross-sectional area S2.
Thereby, for second flow path 27b located on the windward side through which a larger amount of refrigerant is required to flow, second side portion 29b on the windward side is tapered to thereby make it possible to minimize that the refrigerant less easily flows through second flow path 27b. As a result, the heat transfer performance as outdoor heat exchanger 11 can be maintained.
Further, in connecting portion 25, first side portion 29a and second side portion 29b each are tapered, so that this connecting portion 25 is more easily inserted into opening 33 provided in header 31. This can consequently contribute to improvement in manufacturability of outdoor heat exchanger 11.
Further, the tapered first side portion 29a and the tapered second side portion 29b in connecting portion 25 come into contact with opening inner wall surface 34 of opening 33, so that connecting portion 25 can be prevented, for example, from being inserted more than necessary into opening 33 of header 31. This can consequently contribute to stabilization of the flow of the refrigerant inside header 31.
In each of the above-described embodiments, a single-row type outdoor heat exchanger 11 has been explained by way of example (see Fig. 2). Outdoor heat exchanger 11 may however be of a multi-row type and may be a two-row type outdoor heat exchanger 11 in which an outdoor heat exchanger 11a and an outdoor heat exchanger 11b are arranged in the direction in which air flows, as shown in Fig. 20.
Also in such outdoor heat exchanger 11, each of outdoor heat exchangers 11 according to the first to fourth embodiments is applicable to: a portion of outdoor heat exchanger 11a where a flat heat transfer tube is connected to a header 31a; and a portion of outdoor heat exchanger 11b where a flat heat transfer tube is connected to a header 31b, each of these portions being shown inside a dotted-line frame DL.
Further, an outdoor heat exchanger in which three or more rows of outdoor heat exchangers are arranged may be applicable. Further, the present invention is applicable not only to outdoor heat exchanger 11 but also to indoor heat exchanger 5 as required.
The outdoor heat exchangers described in the respective embodiments can be variously combined with one another as required.
The embodiments disclosed herein are by way of example and not limited as described. The present disclosure is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims.

INDUSTRIAL APPLICABILITY

The present disclosure is effectively applicable to a heat exchanger including a flat heat transfer tube.

REFERENCE SIGNS LIST

1 refrigeration cycle apparatus, 3 compressor, 5 indoor heat exchanger, 7 fan, 9 expansion valve, 10 housing, 11 outdoor heat exchanger, 13 propeller fan, 15 four-way valve, 17 refrigerant pipe, 20 molded body, 21 flat heat transfer tube, 23 main body, 25 connecting portion, 26 opening end face, 27 flow path, 27a first flow path, 27b second flow path, 28 opening end, 28a first opening end, 28b second opening end, 29a first side portion, 29b second side portion, 31 header, 33 opening, 34 opening inner wall surface, 41 heat dissipation fin, S1 first flow path cross-sectional area, S2 second flow path cross-sectional area, S3 third flow path cross-sectional area, Y1, P1, P2, P3 arrow (insertion), DL frame.

Claims

A heat exchanger comprising:
a flat heat transfer tube
having a flat shape,

having a first side portion and a second side portion spaced from each other by a width in a first direction,

extending in a second direction crossing the first direction, and

having a plurality of flow paths each extending in the second direction, the flow paths being spaced from each other in the first direction;

a header having an opening to which the flat heat transfer tube is connected; and

a heat dissipation fin, wherein

the flat heat transfer tube comprises
a main body attached to the heat dissipation fin, and

a connecting portion having an opening end face at which each of the flow paths opens, the connecting portion being inserted into the opening of the header and connected to the header,

in the main body, each of the flow paths has a first flow path cross-sectional area,

in the connecting portion, the first side portion is tapered toward the opening end face to be reduced in the width, and

in the opening end face, a first opening end of a first flow path located closest to the tapered first side portion among the flow paths has a second flow path cross-sectional area smaller than the first flow path cross-sectional area.
The heat exchanger according to claim 1, wherein
in the connecting portion, the second side portion is tapered toward the opening end face to be reduced in the width, and

in the opening end face, a second opening end of a second flow path located closest to the tapered second side portion among the flow paths arranged in the first direction has a third flow path cross-sectional area smaller than the first flow path cross-sectional area and larger than the second flow path cross-sectional area.
The heat exchanger according to claim 1 or 2, wherein the tapered first side portion is in contact with an opening inner wall surface in the opening of the header.
The heat exchanger according to claim 2, wherein the tapered second side portion is in contact with an opening inner wall surface in the opening of the header.
The heat exchanger according to any one of claims 1 to 4, wherein the opening end face is located to extend in the first direction.
The heat exchanger according to any one of claims 1 to 4, wherein the opening end face is located to extend from the first side portion to the second side portion to extend toward the main body in a third direction crossing the first direction.
The heat exchanger according to any one of claims 1 to 6, wherein the flat heat transfer tube is disposed such that the first side portion is located on a leeward side and the second side portion is located on a windward side.
A refrigeration cycle apparatus comprising the heat exchanger according to any one of claims 1 to 7.