Heat exchanger and refrigeration cycle device

Abstract

The heat exchanger (100) includes at least one heat transfer tube (10) and fins (20). Each of the at least one heat transfer tubes has a first surface (10c). The fins have a second surface (20a). The second surface is more hydrophilic than the first surface.

Description

[Technical field]

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

[0002] Japanese Patent Application Laid-Open No. 2023-100145 (Patent Document 1) describes a heat exchanger. The heat exchanger described in Patent Document 1 has a flat tube as a heat transfer tube. The flat tube has a sacrificial anode layer on the surface. The sacrificial anode layer is formed of zinc. On the sacrificial anode layer, a film of an oxide of the metal material constituting the sacrificial anode layer is formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-100145 A Summary of the Invention [Problem to be solved by the invention]

[0004] The heat exchanger described in Patent Document 1 has room for improvement in terms of the drainage of water adhering to the surfaces of the heat transfer tubes (flat tubes). The present disclosure provides a heat exchanger with improved drainage of water adhering to the surfaces of the heat transfer tubes. [Means for solving the problem]

[0005] A heat exchanger according to the present disclosure includes at least one heat transfer tube and a fin, each of the at least one heat transfer tube having a first surface, and the fin having a second surface, the second surface being more hydrophilic than the first surface. Effect of the Invention

[0006] According to the heat exchanger of the present disclosure, it is possible to improve the drainage performance of water adhering to the surface of the heat transfer tube. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view of the heat exchanger 100. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a first side view of the heat exchanger 100. [Figure 4] 4 is a second side view of the heat exchanger 100 as viewed from the opposite side to that of FIG. 3. FIG. [Diagram 5] 1 is a cross-sectional view of a heat transfer tube 10. FIG. [Figure 6] 2 is an enlarged cross-sectional view of the heat transfer tube 10 in the vicinity of the surface 10c. [Figure 7] 2 is an enlarged cross-sectional view of the fin 20 in the vicinity of the surface 20a. [Figure 8] FIG. 2 is a model diagram illustrating the hydrophilicity of the surface of an aluminum alloy. [Figure 9] FIG. 2 is a schematic diagram of a refrigeration cycle device 200. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The details of the embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant description will not be repeated.

[0009] Embodiment 1 A description will be given of a heat exchanger according to the embodiment 1. The heat exchanger according to the embodiment 1 is referred to as a heat exchanger 100.

[0010] (Configuration of heat exchanger 100) FIG. 1 is a plan view of the heat exchanger 100. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a first side view of the heat exchanger 100. FIG. 4 is a second side view of the heat exchanger 100 seen from the opposite side to that of FIG. 3. FIG. 5 is a cross-sectional view of the heat transfer tube 10. As shown in FIGS. 1, 2, 3, 4, and 5, the heat exchanger 100 has a plurality of heat transfer tubes 10 and a plurality of fins 20. The heat exchanger 100 is, for example, a heat exchanger used as a cooler. The heat exchanger 100 is, for example, a heat exchanger used in an air conditioner. However, the heat exchanger 100 may be a heat exchanger used in a cold / heating device such as a refrigerator, a freezer, a vending machine, a refrigeration device, or a water heater.

[0011] The heat transfer tubes 10 are arranged at intervals along a first direction DR1. The heat transfer tubes 10 extend along a second direction DR2. The second direction DR2 is a direction perpendicular to the first direction DR1. A plurality of refrigerant flow paths 11 are formed inside the heat transfer tubes 10. The refrigerant flow paths 11 extend along the second direction DR2 inside the heat transfer tubes 10. In a cross-sectional view perpendicular to the second direction DR2, the shape of the refrigerant flow paths 11 is, for example, rectangular.

[0012] The heat transfer tube 10 has a first surface 10a and a second surface 10b. The second surface 10b is the opposite surface of the first surface 10a. The first surface 10a and the second surface 10b form both end surfaces in the first direction DR1. The first surface 10a of one of the two adjacent heat transfer tubes 10 is disposed opposite to the second surface 10b of the other of the two adjacent heat transfer tubes 10 with a gap therebetween. In a cross-sectional view perpendicular to the second direction DR2, the longitudinal direction of the heat transfer tube 10 is along the third direction DR3. The third direction DR3 is a direction perpendicular to the first direction DR1 and the second direction DR2. From another perspective, the heat transfer tube 10 has a flat portion extending along the third direction DR3 in a cross-sectional view perpendicular to the second direction DR2. The heat transfer tube 10 has, for example, an elliptical shape whose longitudinal direction is along the third direction DR3 in a cross-sectional view perpendicular to the second direction DR2.

[0013] The distance between two adjacent heat transfer tubes 10 is, for example, 1 mm or more and 3 mm or less. The heat transfer tubes 10 are formed, for example, by extrusion molding. However, the method of forming the heat transfer tubes 10 is not limited to this. The heat transfer tubes 10 may be formed, for example, by bending a rectangular flat plate material and roll-forming it.

[0014] The fins 20 are arranged at intervals along the first direction DR1. One of two adjacent heat transfer tubes 10 may be referred to as a heat transfer tube 10A, and the other of the two adjacent heat transfer tubes 10 may be referred to as a heat transfer tube 10B. The fins 20 have a main body 21 and protruding portions 22 and 23. The fins 20 are formed, for example, by bending a rectangular flat plate material. However, the method of forming the fins 20 is not limited to this.

[0015] The main body 21 has a first surface 21a and a second surface 21b. The second surface 21b is the surface opposite to the first surface 21a. The first surface 21a and the second surface 21b form both end surfaces of the main body 21 in the first direction DR1. The main body 21 has a bent portion 24a and a base portion 25a. The number of the bent portions 24a and the number of the base portions 25a are, for example, multiple. However, the number of the bent portions 24a and the number of the base portions 25a may be single. The main body 21 and the heat transfer tubes 10 are arranged alternately in the first direction DR1.

[0016] The multiple bent portions 24a are aligned at intervals along the second direction DR2. The base portion 25a is disposed between two adjacent bent portions 24a and is continuous with both of the two adjacent bent portions 24a. The bottoms of the bent portions 24a and the base portion 25a are flat. The first surface 21a of each of the multiple base portions 25a is in contact with the heat transfer tube 10B (more specifically, the first surface 10a of the heat transfer tube 10B) with a brazing material interposed therebetween.

[0017] The main body 21 is bent in the first direction DR1 at each of the multiple bent portions 24a such that the second surface 21b at the bottom of the bent portion 24a contacts the heat transfer tube 10A (more specifically, the second surface 10b of the heat transfer tube 10A) with the brazing material interposed therebetween. From another perspective, the main body 21 extends in the second direction DR2 while meandering between the heat transfer tube 10A and the heat transfer tube 10B in a side view along the third direction DR3.

[0018] The protruding portion 22 and the protruding portion 23 are connected to both ends of the main body 21 in the third direction DR3 so as to protrude from the heat transfer tube 10A and the heat transfer tube 10B along the third direction DR3, respectively. Each of the protruding portion 22 and the protruding portion 23 has a bent portion 24b and a base portion 25b. The number of the bent portions 24b and the number of the base portions 25b are, for example, multiple. However, the number of the bent portions 24b and the number of the base portions 25b may be single.

[0019] The multiple bent portions 24b are arranged at intervals along the second direction DR2. The base portion 25b is disposed at two adjacent bent portions 24b and is connected to both of the two adjacent bent portions 24b. The bottoms of the bent portions 24b and the base portion 25b are flat. The base portion 25b is connected to the base portion 25a in the third direction DR3. From another perspective, in a side view seen along the third direction DR3, the position of the bent portion 24b in the second direction DR2 overlaps with the position of the bent portion 24a in the second direction DR2.

[0020] Each of the protrusions 22 and 23 is bent in the first direction DR1 at the bent portion 24b. From another perspective, each of the protrusions 22 and 23 extends in the second direction DR2 while meandering between the heat transfer tubes 10A and 10B in a side view along the third direction DR3. However, the bending direction of the bent portion 24b (leftward in FIG. 3) is opposite to the bending direction of the bent portion 24a (rightward in FIG. 3).

[0021] When the heat exchanger 100 operates as an evaporator, air from the blower flows between two adjacent heat transfer tubes 10 along the third direction DR3. At this time, a two-phase gas-liquid refrigerant supplied from the upstream side of the outdoor unit flows through the refrigerant flow passage 11. This refrigerant exchanges heat with the air, becoming a low-temperature, low-pressure gas refrigerant, and is sucked into the compressor. Due to this heat exchange, condensation may occur on the surface of the heat transfer tube 10 due to the temperature difference with the air.

[0022] The heat transfer tube 10 has a surface 10c. The first surface 10a and the second surface 10b form part of the surface 10c. FIG. 6 is an enlarged cross-sectional view of the heat transfer tube 10 in the vicinity of the surface 10c. As shown in FIG. 6, the heat transfer tube 10 has a surface layer 12 and a core portion 13. The surface layer 12 is formed on the surface 10c. The core portion 13 is located inside the surface layer 12, i.e., farther from the surface 10c than the surface layer 12.

[0023] The fin 20 has a surface 20a. The first surface 21a and the second surface 21b form part of the surface 20a. FIG. 7 is an enlarged cross-sectional view of the fin 20 in the vicinity of the surface 20a. As shown in FIG. 7, the fin 20 has a surface layer 26 and a core portion 27. The surface layer 26 is formed on the surface 20a. The core portion 27 is located inside the surface layer 26, i.e., farther from the surface 20a than the surface layer 26.

[0024] The material potential in the surface layer 12 is lower than the material potential in the core 13. The material potential in the surface layer 26 is lower than the material potential in the core 13 and is different from the material potential in the surface layer 12. The material potential in the surface layer 26 is lower than the material potential in the surface layer 12, for example.

[0025] The material used for the heat transfer tube 10 is, for example, an aluminum alloy. Specific examples of the aluminum alloy used for the heat transfer tube 10 include aluminum alloys of the A1000 series and aluminum alloys of the A3000 series specified in the JIS standard. The zinc concentration in the aluminum alloy in the surface layer 12 is higher than the zinc concentration in the aluminum alloy in the core portion 13. The material potential of the aluminum alloy decreases as the zinc concentration increases. Therefore, in the heat transfer tube 10, the material potential in the surface layer 12 is lower than the material potential in the core portion 13 due to the difference in zinc concentration in the aluminum alloy. The difference between the zinc concentration in the aluminum alloy in the surface layer 12 and the zinc concentration in the aluminum alloy in the core portion 13 is preferably 0.5 mass percent or more. The core portion 13 may not contain zinc. That is, the zinc concentration in the aluminum alloy in the core portion 13 may be 0 mass percent.

[0026] The surface layer 12 is formed, for example, by a zinc spraying method or a method of applying a zinc-substituted flux. In the zinc spraying method, metallic zinc is sprayed onto the surface of the aluminum alloy, and high-temperature treatment is performed to diffuse the zinc component from the surface of the aluminum alloy, thereby forming the surface layer 12 from an aluminum alloy containing zinc. In the method of applying a zinc-substituted flux, zinc is diffused from the surface of the aluminum alloy by performing sawtooth brazing using a zinc-substituted flux, thereby forming the surface layer 12 from an aluminum alloy containing zinc. In addition to these methods, the surface layer 12 can also be formed from an aluminum alloy containing zinc by forming the heat transfer tube 10 using a clad material in which an aluminum alloy containing zinc (for example, an aluminum alloy of the A7000 series specified in the JIS standard) is bonded to a plate of another aluminum alloy and alloyed.

[0027] The material used for the fin 20 is, for example, an aluminum alloy. Specific examples of the aluminum alloy used for the fin 20 include aluminum alloys of the A1000 series or A3000 series specified in the JIS standard to which zinc has been added. The zinc concentration in the aluminum alloy in the surface layer 26 is higher than the zinc concentration in the aluminum alloy in the core portion 13 and different from the zinc concentration in the aluminum alloy in the surface layer 12. The zinc concentration in the aluminum alloy in the surface layer 26 is preferably higher than the zinc concentration in the aluminum alloy in the surface layer 12. Therefore, the material potential in the surface layer 26 is lower than the material potential in the core portion 13 and different from the material potential in the surface layer 12 (lower than the material potential in the surface layer 12). The difference between the zinc concentration in the aluminum alloy in the surface layer 26 and the zinc concentration in the aluminum alloy in the core portion 13 is preferably 0.5 mass percent or more. The zinc concentration in the aluminum alloy in the surface layer 26 is preferably 10 mass percent or less. As a result, the zinc concentration in the aluminum alloy in the surface layer 12 and the zinc concentration in the aluminum alloy in the core portion 13 are also preferably 10 mass percent or less. In the fin 20, the zinc concentration (material potential) in the aluminum alloy in the surface layer 26 does not need to be different from the zinc concentration (material potential) in the aluminum alloy in the core portion 27. When the material potential in the surface layer 26 is lower than the material potential in the surface layer 12 (i.e., the zinc concentration in the aluminum alloy in the surface layer 26 is higher than the zinc concentration in the aluminum alloy in the surface layer 12), oxides are more likely to form on the surface 20a than on the surface 10c. As a result, the hydrophilicity of the surface 20c becomes higher than that of the surface 10c, and a driving force is generated that moves the water attached to the surface 10c toward the surface 20a due to this difference in hydrophilicity, thereby improving the drainage of the heat exchanger 100.

[0028] An aluminum alloy, for example, is used as the brazing material used to braze the heat transfer tube 10 and the fins 20. However, the melting point of the aluminum alloy used as the brazing material is lower than the melting point of the aluminum alloy used for the heat transfer tube 10 and the melting point of the aluminum alloy used for the fins 20. Specific examples of the aluminum alloy used as the brazing material include aluminum-silicon alloys such as aluminum alloys in the A4000 series specified in the JIS standard.

[0029] (Effect of heat exchanger 100) The effects of the heat exchanger 100 will be described below.

[0030] Aluminum is an inherently active metal. However, aluminum reacts with oxygen in the air and immediately forms a protective oxide film on its surface, so it is stable in dry air at room temperature and is considered to be a metal with high corrosion resistance. On the other hand, if the air contains salt (for example, salt in sea salt particles), the salt locally destroys the oxide film on the surface and forms pits (pitting corrosion occurs). Once pitting corrosion occurs, the active aluminum inside the oxide film is eroded, making it difficult to control and understand the progress of corrosion. Therefore, when heat transfer tubes are made of aluminum alloys, rust prevention treatment is required on the surface of the heat transfer tube.

[0031] In the heat exchanger 100, the material potential of the surface layer 12 is lower than the material potential of the core portion 13. That is, the surface layer 12 functions as a sacrificial anode layer for the core portion 13. As a result, the corrosion mode of the heat transfer tube 10 changes from a mode in which corrosion progresses locally toward the core portion 13 due to pitting corrosion to a mode in which the surface layer 12 is corroded over the entire surface. In this way, in the heat exchanger 100, the material potential of the surface layer 12 is lower than the material potential of the core portion 13 (that is, the zinc concentration in the aluminum alloy in the surface layer 12 is higher than the zinc concentration in the aluminum alloy in the core portion 13), and therefore corrosion of the heat transfer tube 10 is suppressed.

[0032] FIG. 8 is a model diagram explaining the hydrophilicity of the surface of an aluminum alloy. As shown in FIG. 8, an oxide film is formed on the surface of an aluminum alloy by aluminum oxide. The oxide film contains hydroxyl groups (OH groups). Although not shown, the oxide film also contains ether bonds (O bonds). Hydrogen atoms and oxygen atoms of polar water molecules are attracted to these functional groups to form hydrogen bonds. In this way, the oxide film formed on the surface of an aluminum alloy exerts a hydrophilic function. The hydrophilic function of an oxide film increases with the number of hydroxyl groups and ether bonds, and therefore increases with the presence of more oxides on the surface of the aluminum alloy.

[0033] When the material potential of the surface layer 26 is lower than that of the surface layer 12 (i.e., the zinc concentration in the aluminum alloy in the surface layer 26 is higher than that in the aluminum alloy in the surface layer 12), oxides are more likely to form on the surface 20a than on the surface 10c. Therefore, in this case, the generation of oxides is promoted on the surface 20a more than on the surface 10c with the passage of time due to the operation of the air conditioner, etc., so that the hydrophilicity of the surface 20a becomes higher than that of the surface 10c, and a driving force is generated that moves the water attached to the surface 10c toward the surface 20a due to the difference in hydrophilicity. More specifically, condensed water may accumulate in the minute gaps between the surface 10c and the fins 20. Such condensed water moves toward the fins 20 by the driving force described above, and is discharged to the outside of the heat exchanger 100 by the blower. In this way, according to the heat exchanger 100, the drainage performance of the heat exchanger 100 can be improved while suppressing the corrosion of the heat transfer tube 10. When the drainage performance of the heat exchanger 100 is improved, the performance degradation due to an increase in ventilation resistance and frost formation can be suppressed.

[0034] The corrosion resistance of the heat transfer tube 10 having the surface layer 12 as a sacrificial anode layer is determined by the difference between the zinc concentration in the aluminum alloy in the surface layer 12 and the zinc concentration in the aluminum alloy in the core portion 13. When the difference between the zinc concentration in the aluminum alloy in the surface layer 12 and the zinc concentration in the aluminum alloy in the core portion 13 is 0.5 mass percent or more, the surface layer 12 functions sufficiently as a sacrificial anode layer, and the corrosion of the core portion 13 can be sufficiently suppressed. In addition, the driving force of the water attached to the surface 10c to move toward the surface 20a increases as the difference between the zinc concentration in the aluminum alloy in the surface layer 26 and the zinc concentration in the aluminum alloy in the surface layer 12 increases, so that the drainage of the heat exchanger 100 can be sufficiently ensured by setting the difference between the zinc concentration in the aluminum alloy in the surface layer 26 and the zinc concentration in the aluminum alloy in the surface layer 12 to 0.5 mass percent or more.

[0035] On the other hand, if the zinc concentration in the aluminum alloy in surface layer 12 is 10 mass percent or more, the rate at which the sacrificial anode layer (surface layer 12) disappears becomes too fast. Therefore, by setting the zinc concentration in the aluminum alloy in surface layer 26 to 10 mass percent or less, the zinc concentration in the aluminum alloy in surface layer 12 becomes less than 10 mass percent, and the disappearance of the sacrificial anode layer (surface layer 12) due to short-term self-corrosion can be suppressed.

[0036] In the heat exchanger 100, each of the protrusions 22 and 23 has a plurality of bent portions 24b. Therefore, in the heat exchanger 100, the rigidity of the protrusions 22 and 23 is increased, and the heat transfer area of ​​the protrusions 22 and 23 is increased. In addition, by increasing the rigidity of the protrusions 22 and 23, the protrusions 22 and 23 are less likely to deform when subjected to an external force. In addition, by connecting the base portion 25a and the base portion 25b to each other, the protrusions 22 and 23 are firmly connected to the main body portion 21, and the rigidity of the fins 20 is increased.

[0037] In the heat exchanger 100, the heat transfer tube 10 has a flat portion, and the bottom portion and the base portion 25a of the bent portion 24a are flat, so that a jig can be easily arranged during manufacturing, and the manufacturability of the heat exchanger 100 can be improved. In the heat exchanger 100, only one heat transfer tube 10 is arranged between the protruding portion 22 and the protruding portion 23 facing each other in the third direction DR3, so that even if another heat transfer tube 10 adjacent to the one heat transfer tube moves in the third direction DR3, the other heat transfer tube 10 does not come into contact with the protruding portion 22 and the protruding portion 23. Therefore, in the heat exchanger 100, the protruding portion 22 and the protruding portion 23 are prevented from being deformed due to contact between the one heat transfer tube 10 between the protruding portion 22 and the protruding portion 23 and the other heat transfer tube 10 adjacent thereto. In the heat exchanger 100, the structure of the fin 20 as described above allows the interval between the adjacent heat transfer tubes 10 to be narrowed.

[0038] (Configuration of the refrigeration cycle device 200) The configuration of a refrigeration cycle device 200 using the heat exchanger 100 will be described below.

[0039] Fig. 9 is a schematic diagram of a refrigeration cycle apparatus 200. As shown in Fig. 9, the refrigeration cycle apparatus 200 has a refrigerant circuit configured with a compressor 210, a condenser 220, a throttling device 230, and an evaporator 240. The refrigerant flowing through the refrigerant circuit may be filled with any refrigerant.

[0040] The compressor 210 compresses the refrigerant. The compressor 210 is a rotary compressor, a scroll compressor, a screw compressor, a reciprocating compressor, or the like. The condenser 220 exchanges heat between the refrigerant and air. The condenser 220 is, for example, an outdoor heat exchanger. The throttling device 230 expands the refrigerant to reduce the pressure. The throttling device 230 is, for example, an electric expansion valve, a mechanical expansion valve, a capillary tube, or the like. The evaporator 240 exchanges heat between the refrigerant and air. The evaporator 240 is, for example, an outdoor heat exchanger. The refrigeration cycle device 200 further includes a blower 251 and a blower 252. The blower 251 and the blower 251 blow air to the condenser 220 and the evaporator 240, respectively. The evaporator 240 is, for example, a heat exchanger 100.

[0041] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of this application is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0042] 10, 10A, 10B heat transfer tube, 10a first surface, 10b second surface, 10c surface, 11 flow path, 12 surface layer, 13 core portion, 20 fin, 20a surface, 21 main body portion, 21a first surface, 21b second surface, 22, 23 protrusion portion, 24a, 24b bent portion, 25a, 25b base portion, 26 surface layer, 27 core portion, 100 heat exchanger, 200 refrigeration cycle device, 210 compressor, 220 condenser, 230 throttling device, 240 evaporator, 251, 252 blower, DR1 first direction, DR2 second direction, DR3 third direction.

Claims

1. at least one heat transfer tube; fins, each of the at least one heat transfer tubes has a first surface; the fin has a second surface; the second surface has a higher hydrophilicity than the first surface; the at least one heat transfer tube includes a first flat tube and a second flat tube; The first flat tube and the second flat tube are arranged opposite to each other at an interval along a first direction, Each of the first flat tube and the second flat tube extends along a second direction perpendicular to the first direction, and in a cross-sectional view perpendicular to the second direction, a longitudinal direction thereof is along a third direction perpendicular to the first direction and the second direction, The fin has a main body portion, a first protrusion portion, and a second protrusion portion, the main body portion has a first surface and a second surface which are end surfaces in the first direction, the main body portion has a plurality of first bent portions arranged at intervals along the second direction, the first surface is in contact with the first flat tube between two adjacent ones of the plurality of first bent portions, each of the plurality of first bent portions is bent in the first direction so that the second surface comes into contact with the second flat tube; each of the first protrusion and the second protrusion is connected to both ends of the main body in the third direction so as to protrude along the third direction; each of the first protrusion and the second protrusion has a plurality of second bent portions arranged at intervals along the second direction; A heat exchanger, wherein each of the second bent portions is bent in the first direction to a side opposite to each of the plurality of first bent portions.

2. Each of the at least one heat transfer tubes has a first surface layer on the first surface and a core portion that is farther from the first surface than the first surface layer, the fin has a second skin on the second surface; a material potential in the first surface layer is lower than a material potential in the core portion; 2. The heat exchanger according to claim 1, wherein the material potential of the second surface layer is lower than the material potential of the core portion and different from the material potential of the first surface layer.

3. The heat exchanger of claim 2 , wherein the fins and the at least one heat transfer tube are formed from an aluminum alloy.

4. the zinc concentration in the first surface layer is higher than the zinc concentration in the core portion, 4. The heat exchanger according to claim 3, wherein the zinc concentration in the second surface layer is higher than the zinc concentration in the core portion and different from the zinc concentration in the first surface layer.

5. 5. The heat exchanger according to claim 4, wherein the zinc concentration in the second surface layer is higher than the zinc concentration in the first surface layer.

6. a difference between the zinc concentration in the first surface layer and the zinc concentration in the core portion is 0.5 mass percent or more; a difference between the zinc concentration in the second surface layer and the zinc concentration in the first surface layer is 0.5 mass percent or more; The heat exchanger according to claim 5 , wherein the zinc concentration in the second surface layer is 10 mass percent or less.

7. A refrigeration cycle device comprising the heat exchanger according to any one of claims 1 to 6.

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