JP2001276966A - Heat exchanger tube and fin-tube type heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide heat exchanger tube and fin-tube type heat exchanger having excellent heat conductivity which narrows the air space between Cu or Cu alloy tube and fin members, thereby making heat resistance smaller, and which has smaller refrigerant leakage from Cu pipe joints. SOLUTION: The heat exchanger tube is characterized in that Cu or Cu alloy longitudinal plate which has metal or alloy film formed on at least one side surface, is rolled towards width direction, thereby formes into pipe configuration, and weld portion is formed by fusion connection at it's butt joint end. The film consists of a metal that is selected from among a group including Sn, Sn alloy and Zn, Zn alloy for example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger tube for a heat exchanger and a fin tube type heat exchanger for performing heat exchange by circulating CFCs or water, and more particularly to a fin tube type heat exchanger having a large number of fins on the outer periphery of a copper or copper alloy tube. It is possible to reduce the gap between the heat transfer tubes and the fins of the heat exchanger manufactured and disposed at predetermined intervals in the tube axis direction, and further to reduce the occurrence of defects occurring at the welded portions of the heat transfer tubes. The present invention relates to a heat exchanger tube for a heat exchanger and a fin tube type heat exchanger.

[0002]

2. Description of the Related Art Conventionally, a fin tube type heat exchanger includes:
Copper or copper alloy pipes (hereinafter collectively referred to as copper or copper alloy pipes) from the viewpoint of workability, heat transfer, workability and corrosion resistance as heat transfer pipes
Aluminum or aluminum alloy material (hereinafter, aluminum or aluminum alloy material is collectively referred to as aluminum material) is used as the fin material from the viewpoints of moldability, heat conductivity and light weight. ing.

A fin tube type heat exchanger used for an air conditioner or the like is manufactured by the following method.

[0004] First, a copper tube insertion hole is formed by pressing a thin sheet of aluminum material, and cut into predetermined dimensions to produce an aluminum fin material.

Next, several hundreds of fins are stacked at a predetermined interval according to the dimensions of the heat exchanger, cut into a predetermined length and width in advance, and the copper tube which has been subjected to hairpin processing is formed into a multilayer. Insert into the copper tube insertion hole of the arranged fin material. Alternatively, the copper tube subjected to the hairpin processing is inserted into the fin material in multiple layers.

Next, a tool called a billet for expanding the inner diameter of the copper pipe is inserted from the end of the copper pipe to expand the outer diameter of the copper pipe to about 105% of the outer diameter before expansion. Adhere to the material.

Next, a heat exchanger can be manufactured by brazing and attaching a copper tube (return vent) bent into a U-shape to the opening of the copper tube.

In the heat exchanger manufactured as described above, various measures are taken to improve the heat transfer performance between the refrigerant and the copper tube or the aluminum fin material and the atmosphere. Regarding copper tubes, in order to improve the heat transfer performance, an inner grooved tube in which a spiral groove is formed in the copper tube has been proposed. With regard to inner grooved pipes, recently, in the course of global environmental protection and energy saving efforts, for the purpose of further improving heat transfer performance, the development of complicated inner groove shapes has been carried out.
Various grooved seamless pipes and welded grooved pipes have been proposed (Japanese Patent Publication No. 7-96995, Japanese Patent Publication No. 5-71).
874, JP-B-5-10594 and JP-A-4-158193).

On the other hand, regarding aluminum fin materials,
In order to improve the heat transfer performance, studies have been made on the wettability of the surface of the aluminum fin material and the like. About this aluminum fin material. Materials that have been subjected to various surface treatments such as a hydrophilic treatment or a water-repellent treatment for improving performance have been developed.

[0010]

FIG. 1 is a schematic sectional view showing a joint state between a copper tube and a fin material in a conventional fin tube type heat exchanger.

However, in the fin tube type heat exchanger manufactured as described above, the copper tube 1 and the fin material 2 appear to be in close contact with each other in appearance, but actually, after the expansion, Springback of copper tube 1 or copper tube 1
Between the copper tube 1 and the fin material 2
There are often gaps 3 of μm to several tens μm. The heat transfer of the heat exchanger is performed between the refrigerant in the tube and the copper tube, between the copper tube and the aluminum fin material, and between the aluminum fin material and air. Regarding heat transfer between the refrigerant and the copper tube and between the aluminum fin material and the air, as described above,
They are individually researched and developed to improve performance. However, even if the heat transfer between the refrigerant and the copper tube and between the aluminum fin material and the air is improved, if there is a gap in the close contact portion between the copper tube and the aluminum fin material, the air layer in the gap will have a thermal resistance. Therefore, there is a problem that the heat transfer performance at the individual parts described above is not effectively reflected in the improvement of the performance of the entire heat exchanger. For example, when there is a gap in the contact portion between the copper tube and the aluminum fin material, the performance of the heat exchanger is reduced by about 6% as compared with the case where the copper tube and the aluminum fin material are completely in contact. Would.

[0012] In the case of a welded grooved tube to be incorporated in a heat exchanger, the width or shape of the plate after the grooved rolling depends on the refining, strip thickness distribution, groove shape and the like of the grooved rolled material. It may not be stable in the longitudinal direction of the strip because it changes. Due to such instability, when a pipe is manufactured using the above-described strip, the pressing load tends to change at the welded portion. For this reason, defects such as poor welding, shrinkage cavities and blowholes may be formed in the welded portion. In such a welding defect, the heat transfer medium inside the pipe may leak (leak). In this case, there is a problem that it cannot be used as a heat exchanger.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to reduce the thermal resistance by narrowing the gap between a copper or copper alloy tube and a fin material, and to reduce the heat resistance from the joint of the copper tube. It is an object of the present invention to provide a heat exchanger tube for a heat exchanger and a fin tube type heat exchanger having a small heat leakage and excellent heat transfer performance.

[0014]

A heat exchanger tube for a heat exchanger according to the present invention is formed by rolling a copper or copper alloy strip having a metal or alloy film formed on at least one surface in a width direction of the strip to form a tube. And having a welded portion at the butt end by fusion bonding.

In this case, the film is made of Sn, Sn alloy, Z
It is preferable to be composed of one selected from the group consisting of n and Zn alloys.

Further, it is preferable that the film has a thickness of 0.1 μm to 50 μm after the strip is formed into a tube, melt-bonded and reduced in diameter. Further, the film is preferably a film formed by melting.

A fin tube type heat exchanger according to the present invention is characterized in that the heat exchanger tube according to any one of claims 1 to 4 is incorporated therein.

Another fin tube type heat exchanger according to the present invention is a set made by inserting the heat exchanger tube for a heat exchanger according to any one of claims 1 to 4 into aluminum fins and expanding the tube. A fin tube type heat exchanger body assembled from a three-dimensional structure or the assembly, wherein the heat exchanger is heated to a temperature equal to or higher than the melting point of the film.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Usually, between the copper tube and the aluminum fin material,
Due to the spring back of the copper tube, the roundness of the copper tube and the roundness of the copper tube insertion hole formed in the aluminum fin material,
A gap of 0.1 μm to several tens μm is formed. The present inventors have conducted intensive experimental research and studied a method for reducing the thickness of these voids, and as a result, they have found that it is effective to form a metal or alloy film on the outer surface of a copper tube. .

In the heat exchanger tube for a heat exchanger of the present invention, a copper or copper alloy strip having a metal or alloy film formed on at least one surface in advance is rolled in the width direction of the strip and formed into a tubular shape. The parts are fusion bonded. This is because in the plating of the surface after the production of a long tube, processing oil adheres to the surface of the tube, and special equipment is required for degreasing, plating, washing with water, etc. This is because, for example, continuous plating is more difficult than plating on the strip material, resulting in poor plating or reduced corrosion resistance of the plating. The same applies to the case where a coating is formed on the surface of a tube by thermal spraying.

The metal or alloy film may be coated on the copper or copper alloy strip by any method such as electroplating, electroless plating, hot-dip plating, or thermal spraying. Further, the metal or alloy film produced by these methods may be melted. These coatings may be formed only on one side or both sides of the copper or copper alloy strip, and are applicable to the use of the copper or copper alloy pipe of the present invention. If the coating is formed on only one side of the front and back of the strip,
After forming the copper tube, the copper tube is manufactured so that the surface on which the coating is formed is the outer surface. When the coating is formed on both surfaces, it is desirable that the thickness of the coating on the inner surface of the copper tube be equal to or less than the thickness of the coating on the outer surface.

The copper or copper alloy is not particularly limited, and may be OFC (C1020), copper deoxidized copper (C120).
1, C1220, C1221), Cu-Fe-P-based alloys (C19210, C19400, etc.), copper (C210
0, C2200, C2300, C2400) and all copper alloys such as brass (C2600 and the like). Also, the width and plate thickness of the strip material is the target pipe outer diameter,
An appropriate value may be set in consideration of the presence or absence of the groove on the inner surface of the pipe and the shape of the groove. The refining of the strip material is not particularly limited, and a soft material (O material) to a processed material (H material) can be used. When a work material is used, it becomes even harder by the grooving process, but after the heat transfer tube is manufactured, it can be appropriately annealed and thereby softened. Further, the annealing step can also serve as a melting treatment of a metal or alloy film formed on the outer surface of the copper tube.

Hereinafter, the reasons for limiting the numerical value of the heat exchanger tube for a heat exchanger of the present invention will be described.

Coating: Sn, Sn alloy, Zn and Zn alloy
It is desirable that the coating of one kind selected from the group consisting of the following is softer, has a lower melting point, and is superior in corrosion resistance than a copper tube material for the following reasons.

In the expanding process after the copper tube of the present invention is inserted into the aluminum fin material, the metal or alloy film on the outer surface of the copper tube fills the gap between the copper tube and the aluminum fin material and has the function of improving the adhesion. . In order to achieve this function more efficiently, it is desirable that the hardness of the film is softer than that of the copper tube material.

The copper pipe of the present invention is manufactured by a welding method. However, defects such as poor welding, shrinkage cavities and blowholes may occur in the welded portion. The coating formed on the surface of the copper tube is melted in the vicinity of the welded portion and flows into and covers the defective portion, so that the copper tube of the present invention has an effect of repairing welding defects. No leak when rising. Also, at the weld on the outer surface of the pipe,
Irregularities are easily formed in the tube axis direction. However, the molten metal or alloy layer flows into these minute irregularities, and has the effect of reducing the difference in elevation. When the height difference between the irregularities is reduced in this manner, there is an effect of improving the degree of adhesion between the copper tube and the aluminum fin material in the vicinity of the welded portion.
In order to sufficiently exhibit such effects, it is desirable that the metal or alloy constituting the coating has a low melting point, good wettability with the copper tube material, and good fluidity.

Further, by heating after assembling the heat exchanger,
In order to melt the film and fill the gap between the copper tube and the aluminum fin material by capillary action, the metal or alloy constituting the film has a low melting point, has good wettability with the copper tube material, and has good fluidity. Good is desirable.

The heat exchanger of the present invention may be exposed to corrosive media such as sulfur, ammonia and organic acids that are harmful to copper,
When exposed to such a corrosive medium for a long time, the outer surface of the copper tube is reduced in thickness by corrosion, and eventually a hole is formed in the copper tube, which may lead to leakage of the refrigerant flowing inside the copper tube. In order to prevent such a problem, it is desirable that the metal or alloy constituting the film has good corrosion resistance. For this reason, the coating is preferably made of one selected from the group consisting of Sn, Sn alloy, Zn, and Zn alloy.

As the Sn alloy, for example, a Sn—Cu based alloy,
An alloy of Sn-Zn system, Sn-Pb system, Sn-Al system or the like can be given. As a Zn alloy, for example, Zn-
Al-based and Zn-Ni-based alloys are exemplified. These alloys are desirable because the melting point is lower than the melting point of the simple metal by the eutectic reaction. Further, any of the above metals or alloys is softer than the copper tube material.

Further, since the coating made of a metal or an alloy having the above-mentioned composition has good corrosion resistance, it also has an effect of suppressing corrosion of the copper tube from a corrosive medium such as sulfur, ammonia and organic acid which is harmful to the copper tube. is there.

Film thickness: 0.1 to 50 μm When the copper tube and the aluminum fin material are brought into close contact with each other by expansion, that is, when the copper tube is welded and the diameter is reduced, the thickness of the metal or alloy film is reduced to zero. When the thickness is less than 0.1 μm, the effect of narrowing the gap is not sufficient. On the other hand, if the thickness of the film exceeds 50 μm, when inserting the copper tube into the copper tube insertion hole formed in the aluminum fin, the aluminum fin material softer than copper may be deformed, or the metal or alloy layer film may be deformed. The manufacturing cost increases and the heat transfer tube cannot be provided at low cost. Therefore, the thickness of the metal or alloy film formed on the outer surface of the copper tube is preferably 0.1 μm to 50 μm.

[0032]

EXAMPLE A fin tube type heat exchanger according to an example of the present invention is manufactured, and the characteristics of the fin tube type heat exchanger are compared with those of a comparative example.

First Embodiment A phosphor-deoxidized copper strip (O) having a thickness of 0.5 mm and a width of 25 mm was used.
A Sn and Zn film of a predetermined thickness is formed on the surface of the material by thermal spraying, and the film-formed surface is formed into a tube with the surface facing outward, and then the welding (high-frequency induction welding) and diameter reduction steps are continuously performed. 7.0mm outside diameter and 0.20m inside fin height
m, bottom thickness 0.25mm, number of grooves 50, lead angle 1
An 8 ° internally grooved welded tube was produced. The aluminum fin material used was 1200 tempered H24 according to JIS H4000, had a plate thickness of 0.1 mm, and had not been subjected to surface treatment.

After processing the welded pipe to a hairpin length of 550 mm, the copper pipe is inserted into the copper pipe insertion hole formed in the aluminum fin material, and the portion of the welded pipe inserted into the aluminum fin material is replaced with the outer diameter. Tube expansion is performed at 105% of the standard, and the size of the effective heat transfer surface is 250 mm in height and 5 mm in width.
A 50 mm fin tube type heat exchanger (finned coil) was manufactured.

The fin coil is used in accordance with JIS C9612.
According to the room air conditioner performance evaluation method specified in (1), HFC410A (hydrofluorocarbon) was used as the refrigerant in the pipe, and the condensation performance when the overall wind speed was 1.0 m / sec was measured.

As a standard material for comparing the condensation performance with the present embodiment, a heat transfer tube (untreated material) having the same inner surface structure as the heat transfer tube of the present embodiment and having no coating formed on the outer surface of the tube is used. Was used to produce the same finned coil as described above. Hereinafter, the performance improvement rates of the finned coils of the example and the comparative example were calculated as a performance difference with respect to the condensation performance of the untreated material. That is, the performance improvement rate (%) is ((condensation performance (kW) of heat exchanger of Examples and Comparative Examples) / (condensation performance (kW) of heat exchanger without treatment of copper pipe outer surface) -1) × 100. Can be indicated by Table 1 shows the results.

[0037]

[Table 1]

As shown in Table 1 above, Examples Nos. 9 and 11 satisfy Claim 1 of the present application, and the performance of the heat exchanger is improved. Examples Nos. 10 and 12 satisfy claim 1 of the present application, but the film thickness was too large, and the aluminum fin material was deformed when the copper tube was inserted into the insertion hole of the aluminum fin material.

Further, Embodiment Nos. 1 to 8 correspond to claim 3 of the present application.
Was satisfied, the coating did not peel off, the air layer between the copper tube and the aluminum fin material was reduced, and the rate of improvement in heat exchanger performance was excellent.

On the other hand, Comparative Example No. 17 is an untreated material, and thus has a poor condensation performance. Comparative Example No. 18 was an untreated material, and refrigerant leakage occurred from the welded portion due to minute defects in the welded portion, and condensing performance could not be measured. Second Embodiment Sn plating was formed in various thicknesses on the surface of the same strip as in the first embodiment by thermal spraying to produce a welded pipe with an inner groove having the same dimensions and shape as the first embodiment. Then, a finned coil having the same size and shape was manufactured using the same aluminum fin material as in the first embodiment. Then, after assembling the heat exchanger, it is heated to a temperature of 245 ° C., and after the heat exchanger reaches this temperature, it is held for 3 minutes and Sn on the outer surface of the welded pipe.
The layer was melted.

The condensation performance was measured and evaluated in the same manner as in the first embodiment. Table 2 shows the results.

[0042]

[Table 2]

As shown in Table 2 above, in Examples Nos. 13 to 16, there was no peeling of the film, the air layer between the copper tube and the aluminum fin material was reduced, and the rate of improvement of the heat exchanger performance was excellent. Was. Further, since the Sn layer was melted, the performance improvement rate was higher if the film thickness was the same as in Examples Nos. 1 to 8 shown in Table 1. On the other hand, since the comparative example No. 19 is an untreated material, the condensation performance is inferior.

[0044]

As described above, according to the present invention, since a metal or alloy film is formed on at least one surface of the strip, when a copper tube is produced from this strip, copper or copper is produced. The gap between the copper alloy tube and the aluminum fin material can be narrowed, and the thermal resistance of the gap can be reduced as compared with the conventional one. For this reason, the performance as a heat exchanger can be improved. Further, by incorporating the copper or copper alloy tube of the present invention, a heat exchanger having excellent heat transfer performance can be manufactured. Further, since the metal or alloy film on the surface of the copper tube is melted at the time of tube welding and flows into and fills minute defects in the welded portion, a leak having a lower frequency of occurrence than conventional welded tubes can be obtained. Thereby, generation | occurrence | production of the defect which generate | occur | produces in the welding part of a copper or copper alloy pipe can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a joint state between a copper tube and a fin material in a conventional fin tube type heat exchanger.

[Explanation of symbols]

 1: copper tube 2: aluminum fin material 3: void

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 30/00 C23C 30/00 B F28F 1/00 F28F 1/00 E // B23K 101: 14 B23K 101: 14 103: 12 103: 12 (72) Inventor Saeki Main Tax 65 Hirasawa, Hadano-shi, Kanagawa F-term in Hadano Works, Kobe Steel Co., Ltd.F-term (reference) CA15 CA18 CA62

Claims (6)

[Claims] A copper or copper alloy strip having a metal or alloy film formed on at least one surface thereof is rolled in the width direction of the strip to be formed into a tube, and a butt end thereof is welded by fusion bonding. A heat exchanger tube for a heat exchanger, comprising: 2. The coating according to claim 1, wherein the coating comprises Sn, a Sn alloy, Zn and Z.
The heat exchanger tube for a heat exchanger according to claim 1, wherein the heat exchanger tube is made of one selected from the group consisting of n alloys. 3. The film has a thickness of 0.1 μm to 50 μm after a strip material is formed into a tube, fusion-bonded and diameter-reduced.
3. The heat exchanger tube for a heat exchanger according to claim 1, wherein the diameter is μm. 4. 4. The heat exchanger tube for a heat exchanger according to claim 1, wherein the coating is a coating formed by melting. 5. A fin tube type heat exchanger incorporating the heat exchanger tube for a heat exchanger according to any one of claims 1 to 4. 6. An assembly manufactured by inserting the heat exchanger tube for a heat exchanger according to claim 1 into an aluminum fin and expanding the tube, or a fin tube type assembled from the assembly. A fin tube type heat exchanger, wherein the heat exchanger body is heated to a temperature equal to or higher than the melting point of the coating.