Corrosion evaluation parts, heat exchangers and air conditioners

Abstract

A corrosion evaluation part capable of evaluating the corrosion state of the sacrificial anode layer of the heat transfer tube in the region where a plurality of fins are arranged is obtained. The corrosion evaluation part (4) includes a first metal layer (1), a second metal layer (2), and an insulating layer (5). The second metal layer (2) is arranged on the first metal layer (1) and has a lower potential than the first metal layer (1). The insulating layer (5) covers the second metal layer (2). The second metal layer (2) has an upper surface (2a). The upper surface (2a) is located opposite the surface in contact with the first metal layer (1). The insulating layer (5) is provided with a through hole (H). A part of the upper surface (2a) is exposed from the through hole (H).

Description

[Technical field]

[0001] The present disclosure relates to a corrosion evaluation part, a heat exchanger, and an air conditioner. [Background technology]

[0002] Conventionally, a corrosion evaluation part that simulates the base material of a heat transfer tube used in a heat exchanger and a sacrificial anode layer formed on the surface of the base material has been known (for example, WO 2015 / 063903). The corrosion evaluation part described in WO 2015 / 063903 can evaluate the corrosion state of the sacrificial anode layer of the heat transfer tube by placing the corrosion evaluation part in an area of ​​the heat transfer tube where multiple fins are not arranged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 063903 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the minute gaps formed between adjacent fins, oxygen is not easily supplied, and corrosion may progress quickly due to the difference in oxygen concentration from the outside. Therefore, there is room for improvement in evaluating the corrosion state of the sacrificial anode layer of the heat transfer tube in the area where multiple fins are arranged.

[0005] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a corrosion evaluation part capable of evaluating the corrosion state of a sacrificial anode layer of a heat transfer tube in an area where multiple fins are arranged, and a heat exchanger and an air conditioner equipped with the corrosion evaluation part. [Means for solving the problem]

[0006] A corrosion evaluation component according to the present disclosure includes a first metal layer, a second metal layer, and an insulating layer. The second metal layer is disposed on the first metal layer and has a lower potential than the first metal layer. The insulating layer covers the second metal layer. The second metal layer has an upper surface. The upper surface is located opposite to the surface in contact with the first metal layer. The insulating layer has a through hole. A portion of the upper surface is exposed from the through hole.

[0007] A heat exchanger according to the present disclosure includes a corrosion evaluation component, a heat transfer tube, and a plurality of fins. The plurality of fins are attached to the heat transfer tube. The heat transfer tube includes a fin-covered region and an exposed region other than the fin-covered region. The plurality of fins are attached to the fin-covered region. The corrosion evaluation component is disposed in the exposed region.

[0008] An air conditioner according to the present disclosure includes a heat exchanger. Effect of the Invention

[0009] According to the above, it is possible to obtain a corrosion evaluation part capable of evaluating the corrosion state of the sacrificial anode layer of a heat transfer tube in an area where a plurality of fins are arranged, and a heat exchanger and an air conditioner equipped with the corrosion evaluation part. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an example of an air conditioner according to a first embodiment. [Diagram 2] 1 is a schematic external view of an outdoor unit according to a first embodiment. [Diagram 3] FIG. 3 is a schematic cross-sectional view taken along line III-III in FIG. 2. [Figure 4] 1 is a schematic front view of a heat exchanger according to a first embodiment. [Diagram 5] 5 is a schematic cross-sectional view of the heat exchanger taken along line VV in FIG. 4. [Figure 6] 1 is a schematic external view of a corrosion evaluation part according to embodiment 1. FIG. [Figure 7] FIG. 7 is a schematic cross-sectional view of the corrosion evaluation part taken along line VII-VII in FIG. [Figure 8] 1 is a schematic external view of a metal body in a corrosion evaluation part according to embodiment 1. FIG. [Figure 9] 1 is a schematic front view of a corrosion evaluation part according to a first embodiment attached to a heat transfer tube. [Figure 10] FIG. 4 is a partially enlarged schematic cross-sectional view of a corrosion evaluation component, showing the state of corrosion in a second metal layer. [Figure 11] FIG. 4 is a partially enlarged schematic cross-sectional view of a corrosion evaluation component, showing the state of corrosion in a second metal layer. [Figure 12] FIG. 4 is a partially enlarged schematic cross-sectional view of a corrosion evaluation component, showing the state of corrosion in a second metal layer. [Figure 13] FIG. 11 is a schematic cross-sectional view of a corrosion evaluation part according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described. Note that unless otherwise specified, the same or corresponding parts in the following drawings are given the same reference numerals, and the description thereof will not be repeated.

[0012] Embodiment 1 <Air conditioner configuration> FIG. 1 is a schematic diagram showing an example of an air conditioner 300 according to the first embodiment.

[0013] The air conditioner 300 is, for example, a refrigeration cycle device for air conditioning, and as shown in Fig. 1, mainly includes an outdoor unit 100 and an indoor unit 200. The outdoor unit 100 and the indoor unit 200 are connected using a liquid pipe 201 and a gas pipe 202.

[0014] The outdoor unit 100 has a compressor 203, a condenser 204 which is a heat exchanger, and an outdoor blower (fan 103). The compressor 203 is connected to the condenser 204 by piping. The indoor unit 200 has an expansion valve 206, an evaporator 207 which is a heat exchanger, and an indoor blower 208. The expansion valve 206 is connected to the evaporator 207 by piping.

[0015] The compressor 203 of the outdoor unit 100 and the evaporator 207 of the indoor unit 200 are connected by a gas pipe 202. The condenser 204 of the outdoor unit 100 and the expansion valve 206 of the indoor unit 200 are connected by a liquid pipe 201. A refrigerant circuit is formed by such a configuration of the air conditioner 300. Refrigerant circulates in the refrigerant circuit via the liquid pipe 201 and the gas pipe 202.

[0016] The compressor 203 compresses the gaseous refrigerant supplied from the gas pipe 202. The condenser 204 cools the gaseous refrigerant compressed by the compressor 203 to change the refrigerant from a gaseous state to a high-pressure liquid state or a two-phase gas-liquid state. The expansion valve 206 reduces the pressure of the high-pressure liquid state or the two-phase gas-liquid state refrigerant. The evaporator 207 heats the reduced pressure refrigerant to change it to a low-pressure gaseous state refrigerant. The compressor 203 sucks in the refrigerant that has been reduced to a low-pressure gaseous state by the evaporator 207 and compresses it again.

[0017] The outdoor blower (fan 103) sends air to the condenser 204. The outdoor blower (fan 103) is provided to facilitate heat exchange between the refrigerant flowing through the condenser 204 and the air, thereby facilitating the absorption or release of heat. The indoor blower 208 sends air to the evaporator 207. The indoor blower 208 is provided to facilitate heat exchange between the refrigerant flowing through the evaporator 207 and the air, thereby facilitating the absorption or release of heat.

[0018] The condenser 204 and the evaporator 207 are a heat exchanger 10 that exchanges heat with air. A corrosion evaluation part 4 (see FIG. 9) is installed in the heat exchanger 10 as described later.

[0019] Although the air conditioner 300 according to the first embodiment has been described as being used for cooling, it may also be used for heating. Specifically, for example, a switching mechanism (not shown) may be provided for the outdoor unit 100 as described above.

[0020] The switching mechanism is a combination of a four-way valve or a plurality of valves, and switches between the suction pipe and the discharge pipe of the compressor 203. By providing the switching mechanism, the heat exchanger 10 in the outdoor unit 100 can function as an evaporator, and the heat exchanger in the indoor unit 200 can function as a condenser.

[0021] In this way, the air conditioner 300 according to the first embodiment can be used as a heater that uses outdoor heat to heat the room. In other words, the air conditioner 300 according to the first embodiment may be, for example, a device capable of both cooling and heating, a device capable of only cooling, or a device capable of only heating.

[0022] <Outdoor unit configuration> Next, a description will be given of the configuration of the outdoor unit 100 used in the air conditioner 300. Fig. 2 is a schematic external view of the outdoor unit 100 according to embodiment 1. Fig. 3 is a schematic cross-sectional view showing the internal structure of the outdoor unit 100 taken along line III-III in Fig. 2.

[0023] The outdoor unit 100 mainly includes a housing 101, two support stands 102, a fan 103, a fan guard 104, and a heat exchanger 10. The two support stands 102 are disposed, for example, on the ground or a floor. The housing 101 is disposed on the support stand 102, whereby the support stand 102 supports the housing 101. The two support stands 102 are disposed spaced apart from each other in the x direction.

[0024] As shown in Figure 2, the upward vertical direction is defined as the z direction. The downward vertical direction (-z direction) is the direction in which gravitational acceleration is applied. The directions perpendicular to the z direction are defined as the x and y directions. The y direction is perpendicular to the x direction.

[0025] The housing 101 has a bottom wall 101a, a top wall 101b, a front wall 101c, and a side wall 101d. The bottom wall 101a is disposed on a support base 102. The top wall 101b is disposed at a position facing the bottom wall 101a in the z direction. The front wall 101c and the side wall 101d each connect the top wall 101b and the bottom wall 101a. In this way, an internal space surrounded by the bottom wall 101a, the top wall 101b, the front wall 101c, and the side wall 101d is formed inside the housing 101.

[0026] An opening area is provided in the housing 101. The opening area communicates with the internal space of the housing 101. The opening area is formed by an area facing the front wall 101c in the y direction and an area facing the side wall 101d in the x direction.

[0027] A fan guard 104 is provided on the front wall 101c. The fan guard 104 is provided with a plurality of through holes that communicate between the outside of the housing 101 and the internal space of the housing 101, and the fan guard 104 is formed in a lattice shape when viewed from the front in the y direction.

[0028] In the internal space of the housing 101, a heat exchanger 10 as a condenser and a fan 103 are arranged. As shown in FIG. 3, the heat exchanger 10 is provided along the opening area so as not to impede heat exchange by the heat exchanger 10. In other words, the heat exchanger 10 is provided so as to be exposed from the housing 101. The heat exchanger 10 may be provided along a wall that forms the internal space. The fan 103 is surrounded by the heat exchanger 10 and the housing 101.

[0029] <Heat exchanger configuration> Next, the configuration of the heat exchanger 10 used in the outdoor unit 100 will be described. FIG. 4 is a schematic front view of the heat exchanger 10 according to the first embodiment. FIG. 5 is a schematic cross-sectional view of the heat exchanger 10 taken along line VV in FIG. 4. The heat exchanger 10 shown in FIG. 4 and FIG. 5 is, for example, a heat transfer fin-and-tube type heat exchanger, and includes a plurality of heat transfer tubes 13, a plurality of fins 14, a distributor 11, and a header 12. The distributor 11 and the header 12 are arranged to sandwich the heat transfer tube 13. Specifically, one end of the heat transfer tube 13 is connected to the distributor 11. The other end, which is located opposite to the one end in the direction in which the heat transfer tube 13 extends, is connected to the header 12.

[0030] The heat transfer tube 13 may be, for example, a circular tube in which one refrigerant flow path 21 is formed, or a flat tube in which a plurality of refrigerant flow paths 21 are formed. If the heat transfer tube 13 is a flat tube, the heat exchange efficiency of the heat exchanger 10 can be improved and the cost can be reduced.

[0031] As shown in Fig. 4, the heat transfer tube 13 extends in a serpentine manner from the distributor 11 toward the header 12. Specifically, the heat transfer tube 13 has a plurality of straight portions 13a and a plurality of hairpin portions 13b. The straight portions 13a extend linearly. The straight portions 13a are disposed adjacent to each other in the z direction. One ends of the straight portions 13a disposed adjacent to each other are connected to each other via the hairpin portions 13b. The hairpin portions 13b extend in a curved manner.

[0032] 4, the heat transfer tube 13 includes a fin-covered region 17 and a pair of exposed regions 18 other than the fin-covered region 17. The fin-covered region 17 is a region where the multiple fins 14 are attached. The exposed regions 18 are regions where the multiple fins 14 are not arranged and where the heat transfer tube 13 is exposed from the multiple fins 14.

[0033] 4, the fin covering region 17 is located between a pair of exposed regions 18. One of the pair of exposed regions 18 is located between the fin covering region 17 and the distributor 11. The other of the pair of exposed regions 18 is located between the fin covering region 17 and the distributor 11.

[0034] One end and the other end of straight portion 13a in the extending direction of straight portion 13a are located in exposed region 18. Hairpin portion 13b is located in exposed region 18.

[0035] As described above, the multiple fins 14 are attached to the fin covering area 17. The multiple fins 14 are arranged at equal intervals along the direction in which the straight portions 13a extend. Each of the multiple fins 14 is joined to the multiple straight portions 13a arranged side by side in the z direction.

[0036] When the air conditioner 300 is in a cooling operation, a gaseous, high-temperature, high-pressure refrigerant flows into the heat exchanger 10. Specifically, the refrigerant flows into the distributor 11 along the direction indicated by the arrow 15a in FIG. 4. The distributor 11 causes the refrigerant to flow into the heat transfer tubes 13. The refrigerant that has flowed into the heat transfer tubes 13 exchanges heat with the air by passing through the fin-covered region 17. The refrigerant that has flowed into the heat transfer tubes 13 then merges with the header 12. The refrigerant that has flowed into the header 12 flows out of the header 12 along the direction indicated by the arrow 15b in FIG. 4. In this way, when the air conditioner 300 is in a cooling operation, the heat exchanger 10 functions as a condenser.

[0037] 5, the heat transfer tube 13 has a base material 20 and a sacrificial anode layer 19. A refrigerant flow path 21 is formed inside the base material 20. The refrigerant flow path 21 is an area surrounded by an inner wall 20b of the base material 20. A sacrificial anode layer 19, which has a lower potential than the base material 20, is formed on the surface of the base material 20.

[0038] The material constituting the base material 20 is an aluminum alloy. The material constituting the sacrificial anode layer 19 is, for example, an aluminum alloy containing zinc. In the natural environment, zinc has a lower potential than aluminum. Therefore, the sacrificial anode layer 19 has a lower potential than the base material 20. In other words, the sacrificial anode layer 19 corrodes preferentially, thereby preventing corrosion of the base material 20. As a result, leakage of the refrigerant from the refrigerant flow path 21 can be suppressed.

[0039] In the fin coating region 17, the fin 14 is attached to the heat transfer tube 13. The fin 14 is brazed to the sacrificial anode layer 19, thereby joining the fin 14 to the heat transfer tube 13. As shown in FIG. 5, the fin 14 is bent. Specifically, the fin 14 includes a main body portion 14a and a fin collar portion 14b. The main body portion 14a extends along a direction perpendicular to the surface of the heat transfer tube 13. The fin collar portion 14b extends along a direction parallel to the surface of the heat transfer tube 13.

[0040] The fin collar portion 14b is formed by bending one end of the fin 14 (for example, a portion adjacent to an opening formed in the fin 14 for inserting the heat transfer tube 13 therethrough). The fin 14 is joined to the sacrificial anode layer 19 at the fin collar portion 14b. In this manner, the fin 14 is attached to the heat transfer tube 13. Furthermore, by joining the bent end of the fin 14 (fin collar portion 14b) to the heat transfer tube 13, the contact area between the fin 14 and the heat transfer tube 13 increases. This improves the heat exchange efficiency of the heat exchanger 10.

[0041] In the fin covering region 17, the entire surface of the heat transfer tube 13 may be covered with the fins 14. However, since the fins 14 are bent, exposed portions 19a in which parts of the heat transfer tube 13 are exposed are formed between adjacent fins 14. The exposed portions 19a are regions of the surface of the sacrificial anode layer 19 to which the fin collar portions 14b are not joined. In other words, the exposed portions 19a are the surfaces of the sacrificial anode layer 19 formed between adjacent fins 14.

[0042] Specifically, since the fin 14 is bent, the fin 14 includes a curved portion 14c. The curved portion 14c is connected to the main body portion 14a and the fin collar portion 14b. The curved portion 14c has a curvature. A gap region Q is formed between adjacent fins 14. The gap region Q is a region surrounded by the curved portion 14c of one fin 14, the fin collar portion 14b of the other fin 14 disposed adjacent to the fin 14, and the exposed portion 19a (the surface of the sacrificial anode layer 19) disposed between these fins 14.

[0043] When droplets 7 (see FIG. 10) containing corrosion factors adhere to exposed portion 19a, corrosion of the sacrificial anode layer 19 progresses. In particular, since gap region Q is a minute space, oxygen is not easily supplied to said gap region Q. Therefore, the progress of corrosion of the sacrificial anode layer 19 in said exposed portion 19a may progress faster than the progress of corrosion of the sacrificial anode layer 19 in exposed region 18. This phenomenon in which corrosion is accelerated in a gap portion such as a minute gap region Q is called crevice corrosion.

[0044] <Components for corrosion evaluation> Next, the configuration of the corrosion evaluation component 4 attached to the heat exchanger 10 will be described. Fig. 6 is a schematic external view of the corrosion evaluation component 4 according to embodiment 1. Fig. 7 is a schematic cross-sectional view of the corrosion evaluation component 4 taken along line VII-VII in Fig. 6. Fig. 8 is a schematic external view of the metal body 3 in the corrosion evaluation component 4 according to embodiment 1.

[0045] 7, the corrosion evaluation component 4 includes a metal body 3 and an insulating layer 5. The metal body 3 is covered with the insulating layer 5. The metal body 3 includes a first metal layer 1 and a second metal layer 2. The second metal layer 2 is disposed on the first metal layer 1.

[0046] 7, the second metal layer 2 has an upper surface 2a, a lower surface 2b, and a side surface 2c. The direction perpendicular to the upper surface 2a is the Z direction. The directions perpendicular to the Z direction are the X direction and the Y direction. In a plan view seen from the Z direction, the Y direction is perpendicular to the X direction. The upper surface 2a extends along the X direction and the Y direction.

[0047] The corrosion evaluation part 4 may have any shape as long as it can be attached to the heat transfer tube 13, and the shape of the corrosion evaluation part 4 may be rectangular, circular, or elliptical in a plan view seen from the Z direction. As shown in Fig. 6, when the corrosion evaluation part 4 has a rectangular shape in a plan view seen from the Z direction, the X direction may be, for example, the short side direction of the corrosion evaluation part 4. The Y direction may be, for example, the long side direction of the corrosion evaluation part 4. The Z direction may be, for example, the thickness direction of the corrosion evaluation part 4.

[0048] The second metal layer 2 has a lower surface 2b in contact with the first metal layer 1. The upper surface 2a is located opposite the lower surface 2b in the Z direction. The side surface 2c is a surface that is continuous with the upper surface 2a and the lower surface 2b.

[0049] The metal body 3 has a configuration simulating the heat transfer tube 13. Specifically, the material constituting the first metal layer 1 is the same as the material constituting the base material 20. That is, when the material constituting the base material 20 is an aluminum alloy, the material constituting the first metal layer 1 may also be an aluminum alloy. The material constituting the second metal layer 2 is the same as the material constituting the sacrificial anode layer 19. That is, when the material constituting the sacrificial anode layer 19 is an aluminum alloy containing zinc, the material constituting the second metal layer 2 may also be an aluminum alloy containing zinc. In this way, the second metal layer 2 has a lower potential than the first metal layer 1. The material constituting the insulating layer 5 is, for example, a resin having insulating properties that does not corrode itself.

[0050] In the natural environment, zinc has a lower electric potential than aluminum. Therefore, the lower the concentration of zinc in an aluminum alloy, the higher the electric potential of the aluminum alloy. When different metal materials are in contact with each other, the electric potential of each metal material determines whether it is an anode or a cathode.

[0051] In metal materials with a high potential, cathodic reactions such as reduction reactions take place. On the other hand, in metal materials with a low potential, anodic reactions such as metal oxidation reactions take place. That is, an anodic reaction takes place in the second metal layer 2. On the other hand, a cathodic reaction takes place in the first metal layer 1. As a result, the second metal layer 2 corrodes preferentially, and the first metal layer 1 can be protected from corrosion. This function is called a sacrificial corrosion protection function.

[0052] Here, a feature of the corrosion evaluation part 4 according to the present embodiment 1 is that a through hole H is provided in the insulating layer 5. As shown in Figs. 6 and 7, a plurality of through holes H are provided in the insulating layer 5. The upper surface 2a includes a covered portion 9 that is covered by the insulating layer 5 and an exposed portion 6 that is exposed from the insulating layer 5. The covered portion 9 is a region of the upper surface 2a that is covered by the insulating layer 5. The exposed portion 6 is a region of the upper surface 2a that is not covered by the insulating layer 5.

[0053] By attaching the corrosion evaluation component 4 having the through hole H provided in the insulating layer 5 to the heat exchanger 10, the corrosion state of the sacrificial anode layer 19 of the heat transfer tube 13 can be evaluated as described later.

[0054] The number of through holes H provided in the insulating layer 5 needs to be at least one, and may be six as shown in Fig. 6. The greater the number of exposed portions 6, the greater the number of locations at which the corrosion state can be evaluated. By evaluating the corrosion state at a plurality of exposed portions 6, the accuracy of the evaluation of the corrosion state can be improved.

[0055] 5, adjacent exposed portions 19a in the heat exchanger 10 are spaced apart from each other by the fins 14. Therefore, it is unlikely that the liquid droplets 7 will adhere across two exposed portions 19a that are spaced apart from each other. Therefore, the through holes H in the corrosion evaluation component 4 may be spaced apart from each other by 10 mm or more. In this way, the liquid droplets 7 are prevented from adhering across the exposed portions 6 that are adjacent to each other in the corrosion evaluation component 4.

[0056] The inner circumferential width W2 of the through hole H may be the same as the distance W1 between adjacent fins 14. In other words, if the distance W1 between adjacent fins 14 is the same as the inner circumferential width W2 of the through hole H, it is possible to simulate the corrosion state of the sacrificial anode layer 19 in the actual heat exchanger 10. The inner circumferential width W2 of the through hole H is, for example, the diameter of the through hole H, and may be the maximum diameter. The distance W1 between adjacent fins 14 is the width of the exposed portion 19a in the direction in which the heat transfer tube 13 extends.

[0057] In a plan view seen from the Z direction, the shape of the exposed portion 6 may be circular or elliptical. In this way, it is possible to simulate the corrosion state of the sacrificial anode layer 19 in the actual heat exchanger 10.

[0058] 6 and 7 , when the short side direction of the corrosion evaluation part 4 is the X direction, the width of the corrosion evaluation part in the X direction may be equal to or smaller than the width of the heat transfer tube 13 so that the corrosion evaluation part 4 can be attached to the heat transfer tube 13. The thickness of the first metal layer 1 in the Z direction may be equal to or smaller than the thickness of the base material 20 of the heat transfer tube 13. In order to accurately grasp the corrosion state of the sacrificial anode layer 19 in an actual environment, the thickness of the second metal layer 2 in the Z direction may be the same as the thickness of the sacrificial anode layer 19 of the heat transfer tube 13.

[0059] 8, the metal body 3 includes a first metal layer 1 and a second metal layer 2. The second metal layer 2 is disposed on the first metal layer 1. The sacrificial anode layer 19 of the heat transfer tube 13 is formed, for example, by zinc spraying or cladding. Therefore, the second metal layer 2 may be formed in a similar manner to the sacrificial anode layer 19 of the heat transfer tube 13 so that the second metal layer 2 simulates the sacrificial anode layer 19 of the heat transfer tube 13.

[0060] The second metal layer 2 may be a zinc sprayed layer formed by zinc spraying. Here, zinc spraying is a method of forming a zinc sprayed layer as the second metal layer 2 by spraying zinc onto the metal body 3. By heating the metal body 3 after the zinc spraying, the zinc is diffused into the metal body 3. In this way, the second metal layer 2 containing zinc is formed. In the surface layer of the metal body 3, the concentration of zinc is not uniformly diffused, and the concentration of zinc is highest in the surface layer. In this way, the metal body 3 as shown in FIG. 8 can be manufactured.

[0061] The second metal layer 2 may be a clad layer bonded to the first metal layer 1 by clad. Here, clad refers to a method of forming a clad layer as the second metal layer 2 bonded to the first metal layer 1 by bonding two metal plates made of different materials. The metal plate as the first metal layer 1 and the metal plate as the second metal layer 2 can be bonded to each other by using a pressure welding method or the like. The two bonded metal plates can be heat-treated to produce a clad plate as the metal body 3. In this way, the metal body 3 as shown in FIG. 8 can be produced.

[0062] FIG. 9 is a schematic front view of the corrosion evaluation part 4 according to the first embodiment attached to the heat transfer tube 13. As shown in FIG. 9, the corrosion evaluation part 4 is attached to the heat transfer tube 13. The corrosion evaluation part 4 is arranged in the exposed area 18 so as not to interfere with the operation of the heat exchanger 10. In this manner, the corrosion evaluation part 4 is used to evaluate the corrosion state of the heat exchanger 10. The number of corrosion evaluation parts 4 attached to one outdoor unit 100 may be one or more, and may be two or three. In addition, the corrosion evaluation part 4 according to the present disclosure can be applied to an air conditioner having a configuration different from that shown in FIG. 1, or a refrigeration cycle device having any configuration including the heat exchanger 10.

[0063] The corrosion evaluation part 4 may be disposed in either the hairpin portion 13b or the straight portion 13a of the heat transfer tube 13 in the exposed region 18. As shown in Fig. 9, the corrosion evaluation part 4 may be disposed in the exposed region 18 so that the upper surface 2a faces vertically upward (z direction).

[0064] The corrosion evaluation component 4 is fixed to the heat transfer tube 13 by a fixing device 30. As shown in FIG. 9, the corrosion evaluation component 4 may be attached to the heat transfer tube 13 using two fixing devices 30. The corrosion evaluation component 4 may be fixed to the heat transfer tube 13 by wrapping the fixing device 30 around the heat transfer tube 13. In order to prevent corrosion of the fixing device 30 itself, it is preferable that the fixing device 30 is not made of metal. The fixing device 30 may be, for example, a cable tie made of resin. The fixing device 30 is arranged so as not to block the through hole H of the corrosion evaluation component 4.

[0065] The corrosion rate of the second metal layer 2 simulating the sacrificial anode layer 19 in the corrosion evaluation component 4 is higher than the corrosion rate of the sacrificial anode layer 19 in an actual environment. The corrosion evaluation component 4 attached to the heat transfer tube 13 may be collected after a certain period of time has elapsed. In this manner, the corrosion state of the second metal layer 2 is evaluated, and the corrosion state of the exposed portion 19a of the gap region Q in an actual environment can be estimated.

[0066] If the corrosion of the exposed portion 19a of the gap region Q progresses quickly and the sacrificial anticorrosion mechanism of the sacrificial anode layer 19 does not work, the corrosion of the base material 20 will progress. If the base material 20 corrodes, a through hole communicating with the refrigerant flow path 21 will be formed, and there is a risk of the refrigerant leaking.

[0067] By recovering the corrosion evaluation part 4 according to the first embodiment attached to the heat transfer tube 13, it is possible to estimate the corrosion state of the sacrificial anode layer 19 in the heat transfer tube 13 from the corrosion state of the second metal layer 2 in the corrosion evaluation part 4. As a result, it is possible to prevent the refrigerant from leaking from the heat transfer tube 13 in advance.

[0068] The corrosion state of the second metal layer 2 in the recovered corrosion evaluation part 4 can be evaluated by observing a cross section of the corrosion evaluation part 4. Specifically, the recovered corrosion evaluation part 4 is embedded in resin. The embedded corrosion evaluation part 4 is cut and polished to expose a cross section of the corrosion evaluation part. The corrosion depth of the second metal layer 2 can be measured by observing the cross section using, for example, a digital microscope (model number: VHX-X1) manufactured by Keyence Corporation.

[0069] The corrosion state of the base material 20 in the actual environment can be estimated by collating with the test results obtained from the accelerated corrosion test. Specifically, an accelerated corrosion test simulating the actual environment is performed on the manufactured corrosion evaluation part. The accelerated corrosion test is, for example, a continuous neutral salt water spray test or a neutral salt water spray cycle test. By performing the accelerated corrosion test in this manner, the time until a predetermined amount of corrosion is reached can be obtained.

[0070] By determining the ratio between the time to reach a specified amount of corrosion in an actual environment and the time to reach the amount of corrosion obtained in the accelerated corrosion test, the period during which corrosion of the sacrificial anode layer 19 in the gap region Q in an actual environment will progress can be estimated from the corrosion condition of the second metal layer 2 in the recovered corrosion evaluation part 4.

[0071] <Manufacturing method for corrosion evaluation parts> Next, a description will be given of a manufacturing method of the corrosion evaluation component 4 according to the present embodiment 1. In the manufacturing method of the corrosion evaluation component 4 according to the present embodiment 1, first, a metal body 3 including a first metal layer 1 and a second metal layer 2 as shown in Fig. 8 is prepared.

[0072] Next, the metal body 3 is covered with an insulating layer 5. The insulating layer 5 may have a through hole H formed therein in advance. The through hole H may be formed in an adhesive tape serving as the insulating layer 5 using a drill or the like. The tape may be attached to the metal body 3 to produce a corrosion evaluation part 4 as shown in Figs. 6 and 7.

[0073] Alternatively, a part of the second metal layer 2 may be masked and an insulating layer 5 may be formed in the other area, thereby covering the metal body 3 with the insulating layer 5. Specifically, the area of ​​the upper surface 2a that will become the exposed portion 6 is covered with an adhesive tape. An insulating paint is applied to the area (the covered portion 9 of the upper surface 2a and the side surface 2c) other than the area where the tape is formed (the exposed portion 6). Then, the adhesive tape is removed. By removing the adhesive tape in this manner, a through hole H is formed and the exposed portion 6 is exposed from the insulating layer 5. In this manner, the corrosion evaluation part 4 as shown in FIG. 6 and FIG. 7 may be manufactured.

[0074] By covering the areas other than the exposed portion 6 (the covered portion 9 of the upper surface 2a and the side surface 2c) with the insulating layer 5, it is possible to prevent the occurrence of corrosion in the covered portion 9 of the upper surface 2a and the side surface 2c. By allowing water containing corrosion factors to remain in the through hole H, crevice corrosion occurs in the exposed portion 6. Therefore, the thickness of the insulating layer 5 may be such that water is allowed to accumulate in the through hole H. In other words, a method for forming the insulating layer 5 may be selected taking into consideration the thickness of the insulating layer 5.

[0075] 7, insulating layer 5 covers first metal layer 1 and second metal layer 2 so as to cover the areas other than exposed portion 6, but it is sufficient that insulating layer 5 is disposed so as to prevent side surface 2c of second metal layer 2 from being corroded, and it is not necessary for insulating layer 5 to cover first metal layer 1. Part of insulating layer 5 may cover part of the side surface of first metal layer 1 so as to prevent corrosion from occurring in the contact portion where side surface 2c of second metal layer 2 continues to the side surface of first metal layer 1.

[0076] <Corrosion status of the second metal layer> Next, a description will be given of the state of corrosion in the second metal layer 2 when a droplet 7 adheres to the exposed portion 6. Figures 10 to 12 are partially enlarged schematic cross-sectional views of the corrosion evaluation part 4, showing the state of corrosion in the second metal layer.

[0077] Fig. 10 shows a state before the second metal layer 2 is corroded by the liquid droplet 7. As shown in Fig. 10, the liquid droplet 7, such as water, is retained inside the through-hole H. The liquid droplet 7 is in contact with the upper surface 2a of the exposed portion 6. The liquid droplet 7 contains corrosion factors such as chloride ions.

[0078] FIG. 11 shows a state where corrosion of the second metal layer 2 has started due to the droplet 7. When the droplet 7 stays inside the through hole H, as shown in FIG. 11, corrosion occurs in the second metal layer 2. In this way, the second metal layer 2 in the exposed portion 6 in contact with the droplet 7 is thinned in the -Z direction, forming a corrosion hole h on the upper surface 2a. The depth t1 of the corrosion hole h is the distance from the upper surface 2a to the deepest position of the corrosion hole h from the upper surface 2a. The corrosion hole h does not reach the first metal layer 1. The width t2 of the corrosion hole h is equal to or less than the inner circumferential width of the through hole H.

[0079] 12 shows a state in which corrosion of the second metal layer 2 has progressed due to the droplet 7. As the corrosion of the second metal layer 2 progresses, a corrosion hole h reaches the first metal layer 1. Due to the sacrificial corrosion protection function of the second metal layer 2, which will be described later, the second metal layer 2 at the covered portion 9 is thinned, as shown in FIG. 12. The width t2 of the corrosion hole h becomes larger than the inner circumferential width of the through hole H.

[0080] Corrosion in the coating portion 9 progresses according to the following mechanism. Compared to the covered portion 9, oxygen is more easily supplied from the outside to the exposed portion 6. Therefore, in the exposed portion 6, the reduction reaction of oxygen (cathode reaction) represented by the following formula (1) proceeds predominantly.

[0081]

number

[0082] On the other hand, the coated portion 9 is sandwiched between the first metal layer 1 and the insulating layer 5 in the Z direction. Therefore, oxygen is not easily supplied to the coated portion 9 from the outside. Therefore, in the coated portion 9, the oxidation reaction of aluminum (anodic reaction) shown in the following formula (2) and the oxidation reaction of zinc (anodic reaction) shown in the following formula (3) proceed predominantly.

[0083]

number

[0084]

number

[0085] In this manner, an oxygen concentration cell is formed by exposed portion 6 and covered portion 9. As a result, corrosion of second metal layer 2 progresses, as shown in FIG.

[0086] The second metal layer 2 has a lower potential than the first metal layer 1. Therefore, even if the surface of the first metal layer 1 is exposed from the second metal layer 2 as shown in FIG. 12, the sacrificial anticorrosion function of the second metal layer 2 accelerates corrosion in the second metal layer 2. On the surface of the first metal layer 1 exposed due to the thinning of the second metal layer 2, the reduction reaction of oxygen shown in formula (1) proceeds. On the other hand, in the second metal layer 2 in the covering portion 9, the oxidation reaction of aluminum shown in formula (2) and the oxidation reaction of zinc shown in formula (3) proceed.

[0087] The aluminum ions (Al +3 ) and zinc ions (Zn +2 ) accumulate in the second metal layer 2 in the covered portion 9. As a result, in order to satisfy the electrical neutrality condition, for example, chloride ions (Cl - ) migrates from the exposed portion 6 to the droplet 7 in the covered portion 9. That is, the chloride ions (Cl - ) concentration increases.

[0088] In addition, the hydrolysis reaction of zinc shown in the following formula (4) and the hydrolysis reaction of aluminum shown in the following formula (5) proceed. As a result, the hydrogen ions (H + ) increases, and the pH (hydrogen ion exponent) in the droplet 7 decreases.

[0089]

number

[0090]

number

[0091] In this way, the chloride ions (Cl - ) and a decrease in the pH of the droplets 7 cause further corrosion of the second metal layer 2. In this manner, the corrosion evaluation component 4 can be used to cause corrosion to occur in the exposed portion 6 and cause it to progress. In the corrosion evaluation component 4, the area other than the exposed portion 6 is covered with the insulating layer 5. Therefore, the corrosion evaluation component 4 can be used to simulate a state in which the droplets 7 are attached to the gap region Q formed between adjacent fins 14 in a heat transfer tube 13 operating in an actual environment.

[0092] The fins 14 are made of an aluminum alloy containing zinc, similar to the sacrificial anode layer 19. The concentration of zinc contained in the fins 14 is often equal to or higher than the concentration of zinc contained in the sacrificial anode layer 19.

[0093] As mentioned above, zinc has a lower potential than aluminum in the natural environment. Therefore, if the concentration of zinc in an aluminum alloy is high, the corrosion rate increases. In other words, the corrosion rate of the fin 14 is higher than the corrosion rate of the sacrificial anode layer 19. As a result, the fin 14 has a sacrificial anticorrosion function, and the sacrificial anode layer 19 can be protected from corrosion. In this way, the life of the sacrificial anode layer 19 can be extended.

[0094] The corrosion rates of the base material 20, the sacrificial anode layer 19, and the fins 14 have a relationship of fins 14≧sacrificial anode layer 19>base material 20. In an actual environment, the fins 14 corrode faster than the sacrificial anode layer 19, or the fins 14 corrode simultaneously with the sacrificial anode layer 19. As a result, the corrosion rate of the sacrificial anode layer 19 is small. Meanwhile, in the corrosion evaluation component 4, the insulating layer 5 simulates the fins 14. Since the insulating layer 5 does not corrode, the corrosion rate of the second metal layer 2 is greater than in an actual environment.

[0095] <Action and effect> A corrosion evaluation component 4 according to the present disclosure includes a first metal layer 1, a second metal layer 2, and an insulating layer 5. The second metal layer 2 is disposed on the first metal layer 1 and has a lower potential than the first metal layer 1. The insulating layer 5 covers the second metal layer 2. The second metal layer 2 has an upper surface 2a. The upper surface 2a is located opposite the surface in contact with the first metal layer 1. The insulating layer 5 has a through hole H. A part of the upper surface 2a is exposed from the through hole H.

[0096] In this way, the corrosion state of the sacrificial anode layer 19 of the heat transfer tube 13 in the region where the multiple fins 14 are arranged can be evaluated.

[0097] In the corrosion evaluation part 4, the material constituting the first metal layer 1 is an aluminum alloy, and the material constituting the second metal layer 2 is an aluminum alloy containing zinc.

[0098] In this way, the second metal layer 2 has a lower potential than the first metal layer 1. In addition, since the metal body 3 has a configuration simulating the heat transfer tube 13, it is possible to simulate the corrosion state of the sacrificial anode layer 19 in the actual heat exchanger 10.

[0099] In the corrosion evaluation component 4, the second metal layer 2 is joined to the first metal layer 1 by cladding.

[0100] In this way, a metal body 3 in which the second metal layer 2 simulates the sacrificial anode layer 19 of the heat transfer tube 13 can be obtained.

[0101] In the corrosion evaluation part 4, the second metal layer 2 is formed by zinc spraying. In this way, a metal body 3 in which the second metal layer 2 simulates the sacrificial anode layer 19 of the heat transfer tube 13 can be obtained.

[0102] A heat exchanger 10 according to the present disclosure includes a corrosion evaluation component 4, a heat transfer tube 13, and a plurality of fins 14. The plurality of fins 14 are attached to the heat transfer tube 13. The heat transfer tube 13 includes a fin-covered region 17 and an exposed region 18 other than the fin-covered region 17. The fin-covered region 17 has the plurality of fins 14 attached thereto. The corrosion evaluation component 4 is disposed in the exposed region 18.

[0103] In this manner, the corrosion evaluation part 4 does not interfere with the operation of the heat exchanger 10. According to the heat exchanger 10, the distance W1 between adjacent fins 14 is the same as the inner circumferential width W2 of the through hole H.

[0104] In this way, the corrosion evaluation part 4 can more accurately simulate the corrosion state of the sacrificial anode layer 19 in the actual heat exchanger 10.

[0105] According to the heat exchanger 10, the heat transfer tube 13 has a base material 20 and a sacrificial anode layer 19. The material constituting the base material 20 is the same as the material constituting the first metal layer 1. The material constituting the sacrificial anode layer 19 is the same as the material constituting the second metal layer 2.

[0106] In this way, the second metal layer 2 has a lower potential than the first metal layer 1. In addition, since the metal body 3 has a configuration simulating the heat transfer tube 13, it is possible to simulate the corrosion state of the sacrificial anode layer 19 in the actual heat exchanger 10.

[0107] According to the heat exchanger 10, the corrosion evaluation component 4 is placed in the exposed region 18 so that the upper surface 2a faces vertically upward (z direction).

[0108] In this way, the droplets 7 can be retained in the through-holes H. An air conditioner 300 according to the present disclosure includes a heat exchanger 10 .

[0109] In this way, by attaching the corrosion evaluation part 4 inside the heat exchanger 10, for example to the heat transfer tube 13, it is possible to estimate the corrosion state of the heat exchanger 10 in the air conditioner 300.

[0110] Embodiment 2 <Components for corrosion evaluation> Fig. 13 is a schematic cross-sectional view of a corrosion evaluation component 4 according to embodiment 2. Fig. 13 corresponds to Fig. 7. The corrosion evaluation component 4 shown in Fig. 13 basically has the same configuration as the corrosion evaluation component 4 shown in Fig. 6 and Fig. 7 and can obtain the same effects, but differs in that the insulating layer 5 is provided with through holes H having different inner periphery widths.

[0111] 13, the through hole H includes a first through hole H1 and a second through hole H2. An inner peripheral width W4 of the second through hole H2 is different from an inner peripheral width W3 of the first through hole H1. That is, in a plan view seen from the Z direction, an area of ​​the exposed portion 6 exposed from the first through hole H1 is different from an area of ​​the exposed portion 6 exposed from the second through hole H2. In this manner, in one corrosion evaluation component 4, through holes H having different inner peripheral widths may be provided in the insulating layer 5.

[0112] It is considered that the corrosion rate of each exposed portion 6 differs when the size of the exposed portion 6 differs. As described above, as the corrosion of the second metal layer 2 progresses, zinc ions (Zn +2 ) accumulates. The accumulated zinc ions (Zn +2 ) migrates from the covered portion 9 to the exposed portion 6, and the chloride ions (Cl - ) concentration of the droplet 7 in the covered portion 9 is suppressed. Also, the decrease in pH in the droplet 7 is suppressed. In other words, when the area of ​​the exposed portion 6 is large, the chloride ion (Cl -) and the decrease in pH in droplet 7 are greatly suppressed, so that the corrosion rate in second metal layer 2 is reduced. On the other hand, if the area of ​​exposed portion 6 is small, the corrosion rate in second metal layer 2 is increased.

[0113] In this way, by providing a plurality of exposed portions 6 with different exposed areas, it is possible to obtain the relationship between the corrosion rate of the second metal layer 2 and the area of ​​the exposed portions 6. In other words, it is possible to grasp the size of the gap region Q where crevice corrosion is unlikely to occur. As a result, it is possible to design a heat exchanger 10 in which crevice corrosion is unlikely to occur.

[0114] <Action and effect> In the corrosion evaluation component 4, the through hole H includes a first through hole H1 and a second through hole H2. An inner peripheral width W4 of the second through hole H2 is different from an inner peripheral width W3 of the first through hole H1.

[0115] In this way, by providing a plurality of exposed portions 6 with different exposed areas, it is possible to obtain the relationship between the corrosion rate of the second metal layer 2 and the area of ​​the exposed portions 6. In other words, it is possible to grasp the size of the gap region Q where crevice corrosion is unlikely to occur. As a result, it is possible to design a heat exchanger 10 in which crevice corrosion is unlikely to occur.

[0116] In order to verify the effect of the corrosion evaluation part 4 described above, the following experiment was carried out. (experiment) <Sample> Three corrosion evaluation parts 4 according to sample 1 having the same configuration as the corrosion evaluation parts 4 shown in Figs. 6 and 7 were prepared. A3003 alloy used in an actual heat exchanger 10 was used as the metal body 3 according to sample 1. The A3003 alloy is an aluminum alloy to which manganese is added. The A3003 alloy is a single plate. The dimensions of the A3003 alloy used were 40 mm long x 20 mm wide x 1 mm thick.

[0117] A second metal layer 2 was formed on the surface of the A3003 alloy using zinc spraying. The first metal layer 1 was an A3003 alloy. The second metal layer 2 included sprayed zinc. The concentration of zinc in the second metal layer 2 was 2 mass percent. The thickness of the first metal layer 1 was about 0.9 mm, and the thickness of the second metal layer 2 was about 0.1 mm.

[0118] The metal body 3 was covered with an insulating layer 5. A polyester tape for plating was used as the insulating layer 5. The insulating layer 5 had a thickness of 0.1 mm. As shown in FIG. 6, the insulating layer 5 having six through holes H was attached to the metal body 3 using an awl. Then, a tape was attached to cover the area other than the area where the through holes H were provided. In a plan view seen from the Z direction, the shape of the through holes H is circular. The diameter (inner circumference width W2) of each of the through holes H is about 0.5 mm. The distance between the multiple through holes H is 10 mm.

[0119] In order to confirm that the corrosion evaluation part 4 according to Sample 1 can simulate the corrosion state of the sacrificial anode layer 19 in the heat exchanger 10, the heat exchanger 10 according to Sample 2 was prepared. The heat exchanger 10 according to Sample 2 was a part of the heat exchanger 10 cut out before being used in an actual environment. The dimensions of the heat exchanger 10 according to Sample 2 were length (length along the z direction) approximately 150 mm x width (length perpendicular to the z direction and along the direction in which the heat transfer tube 13 extends) approximately 150 mm x thickness (length along the depth direction in FIG. 4) approximately 30 mm.

[0120] An accelerated corrosion test was carried out using the corrosion evaluation parts 4 according to Sample 1 and the heat exchanger 10 according to Sample 2. Aluminum corrodes at a high rate in a salt damage environment. Therefore, artificial seawater (Aquamarine, manufactured by Yashima Pharmaceutical Co., Ltd.) was used as the spray liquid. After placing three corrosion evaluation parts 4 according to Sample 1 and three heat exchangers 10 according to Sample 2 in a test tank, three steps of spraying, wetting, and drying were carried out in order under the test conditions shown in Table 1, and these three steps were repeated.

[0121] [Table 1]

[0122] After 500 hours, 1000 hours, and 2000 hours from the start of the test, the corrosion evaluation part 4 of Sample 1 and the heat exchanger 10 of Sample 2 were each removed from the test tank. The corrosion evaluation part 4 of Sample 1 and the heat exchanger 10 of Sample 2 removed from the test tank were each embedded in resin. The embedded corrosion evaluation part 4 and the heat exchanger 10 were each polished to expose their cross sections. The cross sections were examined using a digital microscope to measure the depth t1 and width t2 of corrosion holes h formed in the second metal layer 2 and the sacrificial anode layer 19.

[0123] In the corrosion evaluation part 4 of Sample 1, the maximum depth and maximum width of the corrosion pit h were measured in exposed portion 6, where corrosion had progressed particularly among the six exposed portions. In the heat exchanger 10 of Sample 2, the depth t1 and width t2 of the corrosion pit h in any three gap regions Q were measured.

[0124] <Test Results>

[0125] [Table 2]

[0126] The test results of the accelerated corrosion test are shown in Table 2. Table 1 shows the depth t1 and width t2 of corrosion pits h after each time elapsed in each of the corrosion evaluation part 4 of Sample 1 and the heat exchanger 10 of Sample 2.

[0127] 500 hours after the start of the test, the maximum depth of the corrosion pit h formed in the second metal layer 2 of the corrosion evaluation part 4 of Sample 1 was 0.075 mm, and the maximum width was 0.847 mm. The corrosion pit h formed in the second metal layer 2 was a wide opening corrosion pit h in which the width t2 of the corrosion pit h was larger than the inner peripheral width W2 of the through hole H, similar to the corrosion pit h shown in FIG.

[0128] At a test time of 2000 hours, the morphology of the corrosion pits h formed in the sacrificial anode layer 19 of the heat exchanger 10 of Sample 2 was similar to the morphology of the corrosion pits h formed in the second metal layer 2 of the corrosion evaluation component 4. Therefore, it was found that, depending on the corrosion evaluation component 4, the corrosion pits h formed in the second metal layer 2 were able to reproduce the morphology of the corrosion pits h formed in the sacrificial anode layer 19 of the heat exchanger 10.

[0129] As shown in Table 1, it can be seen that the depth t1 and width t2 of the corrosion pit h increase with the passage of test time in each of the corrosion evaluation part 4 of sample 1 and the heat exchanger 10 of sample 2. After the same test time has elapsed, the width t2 of the corrosion pit h formed in the second metal layer 2 of the corrosion evaluation part 4 of sample 1 is about twice the width t2 of the corrosion pit h formed in the sacrificial anode layer 19 of the heat exchanger 10 of sample 2. From this result, it was found that the corrosion rate in the second metal layer 2 of the corrosion evaluation part 4 is greater than the corrosion rate in the sacrificial anode layer 19 of the heat exchanger 10. From the above results, the effect of the corrosion evaluation part 4 was confirmed.

[0130] Next, the corrosion state of the corrosion evaluation part 4 in an actual environment was evaluated. The corrosion evaluation part 4 was attached to the hairpin part 13b of the heat exchanger 10 operating in an actual environment using a fastener 30, as shown in FIG. 9. A weather-resistant cable tie was used as the fastener 30. The corrosion evaluation part 4 was manufactured to the same dimensions as the corrosion evaluation part 4 used in the above-mentioned accelerated corrosion test. The outdoor unit 100 was operated, and the corrosion evaluation part 4 was collected after one year.

[0131] The depth t1 and width t2 of the corrosion pit h formed in the exposed portion 6 of the recovered corrosion evaluation part 4 were observed and measured using the same method as in the above-mentioned accelerated corrosion test. The maximum depth of the corrosion pit h formed in the second metal layer 2 was 0.075 mm, and the maximum width was 0.423 mm. From this result, it is possible to evaluate the corrosion state of the heat transfer tube 13 of the outdoor unit 100 operating in an actual environment at an early stage.

[0132] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Unless inconsistent, at least two of the embodiments disclosed herein may be combined. The basic scope of the present disclosure is indicated 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]

[0133] 1 first metal layer, 2 second metal layer, 2a upper surface, 2b lower surface, 2c side surface, 3 metal body, 4 corrosion evaluation part, 5 insulating layer, 6 exposed portion, 7 droplet, 9 coated portion, 10 heat exchanger, 11 distributor, 12 header, 13 heat transfer tube, 13a straight portion, 13b hairpin portion, 14 fin, 14a main body portion, 14b fin collar portion, 14c curved portion, 15a arrow, 15b arrow, 17 fin coated area, 18 exposed area, 19 sacrificial anode layer, 19a exposed portion, 20 base material, 20b inner wall, 21 refrigerant flow path, 30 fixing device, 100 outdoor unit, 101 housing, 101a lower wall, 101b upper wall, 101c front wall, 101d side wall, 102 Support base, 103 fan, 104 fan guard, 200 indoor unit, 201 liquid pipe, 202 gas pipe, 203 compressor, 204 condenser, 206 expansion valve, 207 evaporator, 208 indoor blower, 300 air conditioner, H through hole, h corrosion hole, H1 first through hole, H2 second through hole, Q gap area, W1 distance, W2, W3, W4 inner width, t1 depth, t2 width.

Claims

1. The first metal layer and A second metal layer is disposed on the first metal layer and has a lower potential than the first metal layer, The facility comprises an insulating layer covering the second metal layer, The second metal layer has an upper surface located opposite to the surface in contact with the first metal layer, The insulating layer is provided with through holes, A corrosion evaluation component in which a portion of the upper surface is exposed through the aforementioned through hole.

2. The aforementioned through hole includes a first through hole and a second through hole. The corrosion evaluation component according to claim 1, wherein the inner circumference width of the second through hole is different from the inner circumference width of the first through hole.

3. The material constituting the first metal layer is an aluminum alloy. The corrosion evaluation component according to claim 1, wherein the material constituting the second metal layer is an aluminum alloy containing zinc.

4. The corrosion evaluation component according to claim 1, wherein the second metal layer is joined to the first metal layer by cladding.

5. The corrosion evaluation component according to claim 1, wherein the second metal layer is formed by zinc spraying.

6. A corrosion evaluation component according to any one of claims 1 to 5, Heat transfer tubes, The heat transfer tube is equipped with a plurality of fins attached to it, The heat transfer tube includes a fin-covered region to which a plurality of fins are attached, and an exposed region other than the fin-covered region. The corrosion evaluation component is a heat exchanger located in the exposed area.

7. The heat exchanger according to claim 6, wherein the distance between a plurality of adjacent fins is the same as the inner circumferential width of the through hole.

8. The heat exchanger according to claim 6, wherein the heat transfer tube has the same base material as the material constituting the first metal layer and the same sacrificial anode layer as the material constituting the second metal layer.

9. The heat exchanger according to claim 6, wherein the corrosion evaluation component is arranged in the exposed area such that the upper surface is facing vertically upward.

10. An air conditioner comprising the heat exchanger described in claim 6.

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