HIGH CORROSION RESISTANCE HEAT EXCHANGER

Abstract

A high corrosion resistance heat exchanger is disclosed, which has improved corrosion resistance. The improved corrosion resistance is achieved by controlling alloy components in a tube material and a fin material and inducing sacrificial corrosion of the fin material. The high corrosion resistance heat exchanger includes a tube having a channel formed therein to allow a refrigerant to flow, and a plurality of fins coupled to the outer circumferential surface of the tube. The fins may contain 0.1 wt % to 0.45 wt % of Mg, and 0.5 wt % to 0.8 wt % of Zn, a remainder wt % of Al.

Claims

1. A high corrosion resistance heat exchanger comprising: a tube in which a channel is formed to allow a refrigerant to flow; and a plurality of fins coupled to an outer circumferential surface of the tube, wherein each fin included in the plurality of fins comprises 0.1 wt % to 0.45 wt % of magnesium (Mg), more than 0.5 wt % to 0.8 wt % or less of zinc (Zn), a remainder wt % of aluminum (Al).

2. The high corrosion resistance heat exchanger of claim 1, wherein the tube is provided so that a plurality of rows are connected in a zigzag manner.

3. The high corrosion resistance heat exchanger of claim 1, wherein the plurality of fins are provided along the outer circumferential surface of the tube in a longitudinal direction of the tube.

4. The high corrosion resistance heat exchanger of claim 1, further comprising plate evaporators provided on both sides of the tube, the plate evaporators extending in a height direction orthogonal to the tube.

5. The high corrosion resistance heat exchanger of claim 1, wherein the plurality of fins are coupled to the tube by press-fitting.

6. The high corrosion resistance heat exchanger of claim 1, wherein the fin further comprises more than 0 wt % and less than 0.2 wt % of Fe, and more than 0 wt % and less than 0.1 wt % of Si.

7. The high corrosion resistance heat exchanger of claim 6, wherein each of the fins has a total sum of Mg, Zn, Fe, and Si contents that is more than 0 wt % and 1.0 wt % or less.

8. The high corrosion resistance heat exchanger of claim 1, wherein the tube comprises 0.1 wt % to 0.45 wt % of Mg, 0.1 wt % to 0.6 wt % of Zn, and a remainder wt % of Al.

9. The high corrosion resistance heat exchanger of claim 8, wherein the tube further comprises more than 0 wt % and less than 0.1 wt % of Fe, and more than 0 wt % and less than 0.1 wt % of Si.

10. The high corrosion resistance heat exchanger of claim 1, wherein a corrosion potential of each of the fins is lower than a corrosion potential of the tube.

11. The high corrosion resistance heat exchanger of claim 1, wherein the tube has a corrosion potential of ?760 millivolts (mV) to ?780 mV.

12. The high corrosion resistance heat exchanger of claim 1, wherein each of the fins has a corrosion potential of ?790 millivolts (mV) to ?810 mV.

13. The high corrosion resistance heat exchanger of claim 1, wherein a difference in corrosion potential between the tube and each of the fins ranges from 10 millivolts (mV) to 30 mV.

14. The high corrosion resistance heat exchanger of claim 1, wherein the tube has a corrosion depth of 78 micrometers (?m) to 400 ?m in a Sea Water Acetic Acid Test (SWAAT) according to the American Society for Testing and Materials (ASTM) G85.

15. A high corrosion resistance heat exchanger comprising: a tube extending in longitudinal direction, the tube including a channel formed therein to allow a refrigerant to flow; a plurality of fins coupled to an outer circumferential surface of the tube; and plate evaporators provided on both sides of the tube in a height direction extending orthogonal to the longitudinal direction, wherein the tube is provided so that a plurality of rows are connected in a zigzag manner, and wherein each fin included in the plurality of fins comprises 0.1 wt % to 0.45 wt % of magnesium (Mg), 0.1 wt % to 0.6 wt % of zinc (Zn), and remainder wt % of aluminum (Al).

16. A method of protecting a tube included in a heat exchanger from corrosion, the method comprising: forming the tube from a first weight percentage (wt %) of an alloy composition 1 to establish a first corrosion potential of the tube; and forming one or more fins included in the heat exchanger from a second weight percentage (wt %) of the alloy composition that is higher than the first weight percentage (wt %) of the heat exchanger tube to establish a second corrosion potential of the one or more fins that is lower than the first corrosion potential of the tube, wherein the second corrosion potential induces corrosion of the fin earlier than corrosion of the tube so as to protect the tube from corrosion.

17. The method of claim 16, wherein the alloy composition comprises magnesium (Mg).

18. The method of claim 16, wherein the alloy composition comprises zinc (Zn).

19. The method of claim 16, wherein the one or more fins comprises 0.1 wt % to 0.45 wt % of Mg, more than 0.5 wt % to 0.8 wt % or less of Zn, a remainder wt % of aluminum (Al).

20. The method of claim 16, wherein the first corrosion potential and the second corrosion potential have a difference ranging from 10 millivolts (mV) to 30 mV.

Description

DESCRIPTION OF DRAWINGS

[0033] FIG. 1 is a perspective view of a heat exchanger according to one embodiment of the present invention.

[0034] FIG. 2 is a graph illustrating simulation measurements of corrosion potentials of a tube and a fin of the heat exchanger according to one embodiment of the present invention.

[0035] FIG. 3 is a photograph obtained by photographing general corrosion occurring on a cross-section of the tube of the heat exchanger according to one embodiment of the present invention.

[0036] FIG. 4 is a photograph obtained by photographing pitting corrosion occurring on a cross-section of the tube of the heat exchanger according to a comparative example.

[0037] FIG. 5 is a 3D image obtained by photographing a corroded portion after performing a SWAAT corrosion test for Example 1.

[0038] FIG. 6 is a graph illustrating a corrosion depth according to a distance in a longitudinal direction of the tube for the 3D image in FIG. 5.

[0039] FIG. 7 is a 3D image obtained by photographing a corroded portion after performing the SWAAT corrosion test for Example 2.

[0040] FIG. 8 is a graph illustrating a corrosion depth according to a distance in the longitudinal direction of the tube for the 3D image in FIG. 7.

BEST MODE

[0041] A high corrosion resistance heat exchanger according to one embodiment of the present invention includes a tube in which a channel is formed to allow a refrigerant to flow and a plurality of fins coupled to an outer circumferential surface of the tube, wherein the fin may include 0.1 wt % to 0.45 wt % of Mg, more than 0.5 wt % to 0.8 wt % or less of Zn, a remainder wt % of Al.

Modes of the Invention

[0042] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are presented in order to sufficiently convey the ideas of the present invention to one of ordinary skill in the technical field to which the present invention belongs. The present invention is not limited to the embodiments shown herein and may be embodied in other forms. In order to clarify the present invention, the drawings may omit portions that are not relevant to the description, and the sizes of components may be somewhat exaggerated for ease of understanding.

[0043] Throughout the specification, when a part is said to include a certain element, this does not mean that other elements are excluded, but that other elements can be further included the presence of elements, unless otherwise specified.

[0044] Singular expressions include plural expressions unless the content clearly indicates otherwise.

[0045] The reference numerals used in operations are used for convenience of description and are not intended to describe the order of operations and the operations may be performed in a different order unless the order of operations is clearly stated.

[0046] A high corrosion resistance heat exchanger according to one embodiment of the present invention may include: a tube in which a channel is formed to allow a refrigerant to flow; and a plurality of fins coupled to an outer circumferential surface of the tube. The tube may be provided so that a plurality of rows are connected in a zigzag manner. The plurality of fins may be provided along the outer circumferential surface of the tube in a longitudinal direction of the tube.

[0047] Furthermore, the high corrosion resistance heat exchanger according to one embodiment of the present invention may further include plate evaporators provided on both sides of the tube in a height direction extending orthogonal to the longitudinal direction.

[0048] FIG. 1 is a perspective view of a heat exchanger according to one embodiment of the present invention.

[0049] Referring to FIG. 1, a high corrosion resistance heat exchanger 1 according to one embodiment of the present invention may include a tube 10 in which a channel 3 is formed to allow a refrigerant to flow, and a fin 11 coupled to an outer circumferential surface of the tube 10. The fin 11 may be provided as a plurality of fins 11.

[0050] In addition, the tube 10 may be provided so that a plurality of rows are connected in a zigzag manner to expand a heat exchange area between a refrigerant flowing inside the tube 10 and the outside air.

[0051] Furthermore, the plurality of fins 11 may be provided between a plurality of tubes 10 so as to enable efficient heat exchange between the refrigerant flowing along the channels 3 formed inside the tubes 10 and the outside air. In other words, the fin 11 may be disposed in contact with the tube 10 in a heat exchange space. In addition, the plurality of fins 11 may be provided along the outer circumferential surface of the tube 10 in the longitudinal direction of the tube 10. In this case, the shape of the fin 11 is not particularly limited. In addition, the plurality of fins 11 may be installed to be spaced a certain distance from each other to prevent corrosion of the tube 10, but the positions at which the fins are installed are not particularly limited.

[0052] The high corrosion resistance heat exchanger 1 according to one embodiment of the present invention may further include plate evaporators 12 provided on both sides of the tube 10 in a height direction that extends orthogonal to the longitudinal direction. The plate evaporator 12 not only performs a heat exchange function, but also serves to fix the tube 10 so as to maintain the shape of the heat exchanger 1. In addition, auxiliary materials such as sensors may be coupled to the plate evaporator 12.

[0053] The plurality of fins 11 may be coupled to the tube 10 by press-fitting. In other words, the tube 10 and the fin 11 may be coupled by pushing the fin 11 having a smaller hole than the outer diameter of the tube 10 onto the tube 10.

[0054] Hereinafter, the reason for limiting the numerical value of the alloy component content in an embodiment of the present invention will be described. Hereinafter, unless otherwise stated, the units are wt %.

[0055] In the high corrosion resistance heat exchanger 1 according to one embodiment of the present invention, the fin 11 may include 0.1 wt % to 0.45 wt % of Mg, more than 0.5 wt % to 0.8 wt % or less of zinc (Zn), a remainder wt % of aluminum (Al).

[0056] The content of Mg (magnesium) contained in the fin 11 may range from 0.1 wt % to 0.45 wt %.

[0057] Mg is an element having a relatively low corrosion potential. Therefore, the difference in corrosion potential between the tube 10 and the fin 11 may be adjusted by controlling the content of Mg. In the present invention, the corrosion potential of the fin 11 may be adjusted to be low by controlling the content of Mg contained in the fin 11 to be higher than the content of Mg contained in the tube 10. Since the corrosion potential of the fin 11 is lower, the fin 11 may be induced to corrode earlier than the tube 10, thereby protecting the tube 10 from corrosion.

[0058] In addition, Mg is an effective element for improving the mechanical strength of aluminum alloys. In view of this, Mg may be added at 0.1 wt % or more. However, when the Mg content is excessive, extrudability decreases due to the increase in strength. In view of this, the upper limit of Mg content may be limited to 0.45 wt %.

[0059] The content of zinc (Zn) contained in the fin 11 may range from more than 0.5 wt % to 0.8 wt % or less.

[0060] Similar to Mg, Zn is an element having a relatively low corrosion potential. Therefore, the difference in corrosion potential between the tube 10 and the fin 11 may be controlled by controlling the content of Zn. Therefore, similar to Mg, since the content of Zn contained in the fin 11 is controlled to be higher than the content of Zn contained in the tube 10, the fin 11 may be induced to corrode earlier than the tube 10, thereby protecting the tube 10 from corrosion.

[0061] In addition, Zn is an effective element for increasing resistance to pitting corrosion by inhibiting the formation of aluminum-magnesium (Al.sub.3Mg.sub.2). Pitting refers to localized corrosion that creates holes or pits in a metal surface. When pitting corrosion occurs, there is a concern that the durability of the heat exchanger 1 may be degraded, and thus it is preferable to minimize such corrosion. In view of this, Zn may be added in excess of 0.5 wt %. However, when the content of Zn is excessive, the corrosion property is degraded by continuously forming Mg32(Al, Zn)49 phases around grain boundaries. In view of this, the upper limit of Zn content may be limited to 0.8 wt %.

[0062] The remaining component contained in the fin 11 is aluminum (Al), which is lightweight and exhibits high corrosion resistance due to an oxide film formed on the surface thereof. However, in a normal manufacturing process, since unintended impurities from raw materials or the surrounding environment may inevitably be introduced and incorporated, this cannot be ruled out. Since anyone skilled in the conventional manufacturing process will know these impurities, they are not all specifically mentioned in the present specification.

[0063] In the high corrosion resistance heat exchanger 1 according to one embodiment of the present invention, the fin 11 may further include more than 0 wt % and less than 0.2 wt % of Fe, and more than 0 wt % and less than 0.1 wt % of Si.

[0064] The content of iron (Fe) contained in the fin 11 may be more than 0 wt % and less than 0.2 wt %.

[0065] Fe is a major impurity contained in industrial aluminum contained in the form of iron oxide in bauxite, which is a raw material ore of aluminum, and is an element that forms an intermetallic compound with Al and Cu to degrade the corrosion resistance of the alloy. Therefore, in the present invention, Fe is managed as an impurity, and the upper limit thereof may be limited to less than 0.2 wt %.

[0066] The content of silicon (Si) contained in the fin 11 may be more than 0 wt % and less than 0.1 wt %.

[0067] Si is a major impurity contained in industrial aluminum contained in the form of silica in bauxite, which is a raw material ore of aluminum, and is an element that forms an intermetallic compound with Al and Cu to reduce the corrosion resistance of the alloy. Therefore, in the present invention, Si is managed as an impurity, and the upper limit thereof may be limited to less than 0.1 wt %.

[0068] In the high corrosion resistance heat exchanger 1 according to one embodiment of the present invention, the fin 11 may have a total sum of Mg, Zn, Fe, and Si contents that is more than 0 wt % and 1.0 wt % or less. By managing the content of Al to 99.0 wt % or more, the high corrosion resistance by the oxide film on the surface may be implemented, and a proper level of yield strength can be maintained.

[0069] In the high corrosion resistance heat exchanger 1 according to one embodiment of the present invention, the tube 10 may include 0.1 wt % to 0.45 wt % of Mg, 0.1 wt % to 0.6 wt % of zinc (Zn), a remainder wt % of aluminum (Al).

[0070] The content of magnesium (Mg) contained in the tube 10 may range from 0.1 wt % to 0.45 wt %.

[0071] As described above, Mg is an element having a relatively low corrosion potential. Therefore, the difference in corrosion potential between the tube 10 and the fin 11 may be controlled by controlling the content of Mg. In the present invention, the corrosion potential of the tube 10 may be adjusted to be high by controlling the content of Mg contained in the tube 10 to be lower than the content of Mg contained in the fin 11.

[0072] In addition, as described above, Mg is an effective element for improving the mechanical strength of aluminum alloys. In view of this, Mg may also be added at 0.1 wt % or more to the tube 10. However, since extrudability decreases when the Mg content is excessive, the upper limit of the Mg content may be limited to 0.45 wt %.

[0073] The content of zinc (Zn) contained in the tube 10 may range from 0.1 wt % to 0.6 wt %.

[0074] As described above, similar to Mg, Zn is an element having a relatively low corrosion potential. Therefore, the difference in corrosion potential between the tube 10 and the fin 11 may be controlled by controlling the content of Zn. Therefore, similar to Mg, the content of Zn contained in the tube 10 is controlled to be lower than the content of Zn contained in the fin 11 so that the corrosion potential of the tube 10 may be adjusted to be high.

[0075] However, since Zn is an effective element for increasing resistance against pitting corrosion, Zn may be added at 0.1 wt % or more to the tube 10. However, when the content of Zn is excessive, the corrosion property is reduced and thus the upper limit of Zn content may be limited to 0.6 wt %.

[0076] The remaining component contained in the tube 10 is aluminum (Al). However, in a normal manufacturing process, since unintended impurities from the raw material or the surrounding environment may inevitably be introduced and incorporated, this cannot be ruled out. Since anyone skilled in the conventional manufacturing process will know these impurities, they are not all specifically mentioned in the present specification.

[0077] In the high corrosion resistance heat exchanger 1 according to one embodiment of the present invention, the tube 10 may further include more than 0 wt % and less than 0.2 wt % of Fe, and more than 0 wt % and less than 0.1 wt % of Si.

[0078] As described above, Fe and Si are major impurities contained in industrial aluminum. Therefore, in the present invention, Fe and Si are managed as impurities. In view of this, the upper limit of the Fe content may be limited to less than 0.2 wt %, and the upper limit of the Si content may be limited to less than 0.1 wt %.

[0079] FIG. 3 is a photograph obtained by photographing general corrosion occurring on a cross-section of the tube 10 of the heat exchanger 1 according to one embodiment of the present invention, and FIG. 4 is a photograph obtained by photographing pitting corrosion occurring on a cross-section of the tube 10 of the heat exchanger 1 according to a comparative example.

[0080] Referring to FIG. 3, general corrosion to a depth of 100 ?m occurred in the heat exchanger tube 10 according to one embodiment of the present invention. In other words, the heat exchanger tube 10 according to one embodiment of the present invention may be evaluated as a tube 10 having excellent corrosion resistance. Meanwhile, referring to FIG. 4, pitting corrosion to a depth of 700 ?m occurred in the heat exchanger tube 10 according to the comparative example. Pitting corrosion is corrosion that penetrates into the tube 10, which causes the durability of the heat exchanger tube to be degraded relatively quickly. Therefore, the heat exchanger tube 10 according to the comparative example may be evaluated as having inferior corrosion resistance.

[0081] In the present invention, when the above-described alloy compositions and composition ranges are applied, general corrosion rather than pitting corrosion may occur in the tube 10 and the fin 11. Therefore, the present invention may provide a heat exchanger 1 with improved corrosion resistance.

[0082] In the high corrosion resistance heat exchanger 1 according to one embodiment of the present invention, the corrosion potential of the fin 11 may be lower than that of the tube 10. Thereby, sacrificial corrosion of the fin 11 may be induced, thereby protecting the tube 10 from corrosion.

[0083] The sacrificial corrosion refers to corroding one metal to prevent another metal from corroding. This may be caused by an inherent potential difference between different metals. In this case, the corrosion of the lower potential metal is promoted, while the higher potential metal may be protected from corrosion.

[0084] In one example of the present invention, since the potential of the fin 11 is low, the corrosion of the fin 11 is promoted, and since the potential of the tube 10 is high, the tube 10 may be protected from corrosion. In particular, it can be said to be one feature of the present invention in which the alloy composition of the fin 11 has been designed to induce sacrificial corrosion in response to the tube 10 made of a new alloy composition with high corrosion resistance. Therefore, in addition to the high corrosion resistance of the tube 10 itself through the new alloy composition, even higher corrosion resistance may be secured by inducing sacrificial corrosion through the combination with the fin 11.

[0085] Corrosion potential is often measured in millivolts. This measurement indicates how likely a metal is to corrode. A potential difference in millivolts (mV) between two different metals can predict how they will behave when they are in contact in a specific environment. According to a non-limiting embodiment of the present invention, the corrosion potential of the tube 10 made of a new alloy composition may range from ?760 mV to ?780 mV. In addition, the corrosion potential of the fin 11, which is designed to induce sacrificial corrosion in response to the tube 10, may range from ?790 mV to ?810 mV. The measurements of the corrosion potentials were performed with a solution consisting of 1 mol/L NaCl and 10 mL of 30% hydrogen peroxide reagent at 25 degrees Celsius (? C.), according to the ASTM G69 standard.

[0086] In addition, in the high corrosion resistance heat exchanger 1 according to one embodiment of the present invention, the difference in corrosion potential between the tube 10 and the fin 11 may range from 10 mV to 30 mV.

[0087] When the difference in corrosion potential is small, since the corrosion protection effect by sacrificial corrosion is reduced, the tube 10 and the fin 11 may be corroded at the same time. In view of this, the difference in corrosion potential may be 10 mV or more. However, when the difference in corrosion potential is excessively large, since the fin 11 may rapidly corrode, the duration of corrosion protection of the tube 10 by sacrificial corrosion is shortened. In view of this, the upper limit of the difference in corrosion potential may be limited to 30 mV.

[0088] By designing the corrosion potentials of the tube 10 and the fin 11, in the high corrosion resistance heat exchanger 1 according to one example of the present invention, a corrosion depth of the tube may range from 78 ?m to 400 ?m in a SWAAT according to ASTM G85.

[0089] In another aspect of the present invention, a high corrosion resistance heat exchanger 1 according to one embodiment may include a tube 10 in which a channel 3 is formed to allow a refrigerant to flow, and a plurality of fins 11 coupled to an outer circumferential surface of the tube, and plate evaporators 12 provided on both sides of the tube 10 in a height direction, wherein the tube 10 may be provided so that a plurality of rows are connected in a zigzag manner.

[0090] In addition, the plurality of fins 11 may be provided along the outer circumferential surface of the tube 10 in a longitudinal direction of the tube 10.

[0091] Furthermore, the plurality of fins 11 may be coupled to the tube 10 by press-fitting.

[0092] In addition, the tube 10 may include 0.1 wt % to 0.45 wt % of Mg, 0.1 wt % to 0.6 wt % of Zn, a remainder wt % of Al. Furthermore, the tube 10 may further include more than 0 wt % and less than 0.1 wt % of Fe, and more than 0 wt % and less than 0.1 wt % of Si. In other words, the high corrosion resistance heat exchanger 1 may be obtained by applying the tube 10 designed with a new alloy composition and having improved corrosion resistance.

[0093] A detailed description of the shape of the heat exchanger 1 and the content of the alloy compositions of the tube 10 and the fin 11 are as described above.

[0094] Hereinafter, the present invention will be described in more detail through examples. However, the description of these examples is only for illustrating the implementation of the present invention, and the present invention is not limited by the description of these examples. This is because that the scope of rights of the present invention is determined by the matters described in the claims and matters reasonably inferred therefrom.

Examples

[0095] After preparing aluminum alloys with the compositions shown in Table 1 below, corrosion potential simulation and SWAAT according to ASTM G85 were performed.

TABLE-US-00001 TABLE 1 Component (wt %) Mg Zn Fe Si Example Tube 0.15 0.2 0.05 0.05 1 Fin 0.25 0.55 0.02 0.03 Example Tube 0.15 0.2 0.05 0.05 2 Fin 0.3 0.65 0.02 0.02 Com- Tube 0.025 0.04 0.25 0.2 parative Fin 0.0 0.1 0.6 0.8 Example

<Corrosion Potential Simulation>

[0096] FIG. 2 is a graph illustrating simulation measurements of the corrosion potentials of the tube 10 and fin 11 of the heat exchanger 1 according to Examples 1 and 2. In FIG. 2, line (A) represents an average corrosion potential of the tube of Examples 1 and 2, line (B) represents an average corrosion potential of the fin 11 of Example 1, and line (C) represents an average corrosion potential of the fin of Example 2.

[0097] Referring to FIG. 2, the change in corrosion potentials of the tube 10 and fin 11 over time can be seen. In the case of Example 1, an average difference in corrosion potential between the tube 10 and the fin 11 is 10 mV, and in the case of Example 2 in which the content of Mg and Zn included in the fin is relatively high, the average difference in corrosion potential between the tube 10 and the fin 11 is 30 mV. In other words, it can be seen that the alloy composition of the fin 11 was designed to induce efficient sacrificial corrosion in response to the tube 10 made of a new alloy composition with high corrosion resistance.

<SWAAT>

[0098] The SWAAT according to STM G85 was carried out as a cycle performed for 48 days by spraying for 30 minutes after 90 minutes of immersion at pH 2.8 to 3.0 and a relative humidity of 98% or more using a mixture of 5% NaCl and 10 mol/L acetic acid in a salt spray chamber.

[0099] FIG. 5 is a 3D image obtained by photographing a corroded portion after performing a SWAAT corrosion test for Example 1, and FIG. 6 is a graph illustrating a corrosion depth according to a distance in the longitudinal direction of the tube for the 3D image in FIG. 5. In addition, FIG. 7 is a 3D image obtained by photographing a corroded portion after performing the SWAAT corrosion test for Example 2, and FIG. 8 is a graph illustrating a corrosion depth according to a distance in the longitudinal direction of the tube for the 3D image in FIG. 7.

[0100] It can be evaluated that the shallower the corrosion depth according to the distance in the longitudinal direction of the tube 10, the better the corrosion resistance.

[0101] Referring to FIGS. 5 and 6, in the case of Example 1 in which the average difference in corrosion potential between the tube 10 and the fin 11 is 10 mV, the corrosion depth was measured to be 400 ?m. When the SWAAT was performed under the same conditions, compared to the measurement of the depth of pitting corrosion occurring on one cross-section of the heat exchanger tube 10 according to the comparative example, which was measured to be 700 ?m, it can be evaluated that corrosion resistance is good.

[0102] Referring to FIGS. 7 and 8, in the case of Example 2 in which an average difference in corrosion potential between the tube 10 and the fin 11 is 30 mV, the depth of the corrosion was measured to be 78 ?m. In other words, it can be evaluated that corrosion resistance is very excellent.

INDUSTRIAL APPLICABILITY

[0103] According to the present invention, it is possible to allow general corrosion rather than pitting corrosion to occur by designing an alloy composition with improved corrosion resistance and applying the alloy composition to a tube and a fin of a heat exchanger. It is also possible to induce sacrificial corrosion of the fin to protect the tube from corrosion by designing an alloy composition of a fin material in response to a tube composed of a new alloy composition.