JP3046471B2 - Fin tube type heat exchanger with excellent ant-nest corrosion resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fin tube type heat exchanger used for an air conditioner, and more particularly to a fin tube type heat exchanger having excellent corrosion resistance against ant nest corrosion, that is, excellent ant nest corrosion resistance . About the vessel.

[0002]

2. Description of the Related Art Generally, a fin tube type heat exchanger used for an air conditioner is provided with a tube insertion hole in a plate-like fin made of aluminum or aluminum alloy, and a cylindrical fin collar in the insertion hole. The copper tubing is inserted into the fin collar so as to connect the fins, and the tubes are expanded and fixed to the fins. Assembled.
Then, a heat medium is caused to flow in the tube, and the heat is transmitted to the fins to radiate the heat.

In this fin tube type heat exchanger, the plate-shaped fin is made of aluminum or an aluminum alloy in terms of heat conductivity and cost, and the tube is made of copper in terms of heat conductivity and corrosion resistance. Tubes are widely used. In addition, this copper tube is a tube of pure copper mainly called phosphorus deoxidized copper.

[0004]

However, in these conventional fin tube type heat exchangers, organic substances such as lubricating oil and organic solvents remain inevitably remaining in the fin punching process and the tube expanding process. However, during storage of the fins and tubes or during use as a heat exchanger,
Repeated adhesion and evaporation of water. In addition, during use as a heat exchanger, it is exposed to a peculiar temperature and humidity, a ventilation environment, and the like. Under such conditions, the organic matter is decomposed to contain carboxylic acid, peculiar ant-like corrosion locally occurs, and the tube often leaks.

As described above, many lubricating oils are used in the assembly process of the fin tube type heat exchanger. However, due to recent environmental problems, degreasing and washing with an organic solvent tends to be avoided. Lubricating oils tend to be used. Among these volatile lubricating oils, there are those in which the base oil is volatile but the oily additive remains on the material surface. Therefore, as compared with the case where degreasing and washing have been performed with an organic solvent, the residual amount of organic substances on the surface of the material tends to increase, and the danger of ant-nest corrosion has increased more than before.

Against this background, fin tube type heat exchangers have recently attracted attention as a major problem in terms of ant nest corrosion, and fin tube type heat exchangers have excellent fin nest corrosion resistance. The development of a heat exchanger is desired.

[0007] The present invention has been made in view of such a problem, and is a phenomenon peculiar to a fin tube type heat exchanger.
That is, the lubricating oil inevitably remaining in the heat exchanger assembling process is repeatedly subjected to adhesion and evaporation of moisture, and is further exposed to an environment of unusual temperature and humidity conditions and ventilation conditions, and contains carboxylic acid. However, it has excellent corrosion resistance to ant-nest corrosion, and its reliability and life can be increased .
And to provide a finned tube heat exchanger focal corrosion resistance was excellent.

[0008]

According to the present invention, there is provided a fin tube type heat exchanger excellent in termite nest-like corrosion resistance, in which a plurality of plate-like fins made of aluminum or aluminum alloy are arranged in parallel. In a fin tube type heat exchanger in which a copper alloy tube for contacting and connecting the copper alloy tube is arranged, the copper alloy tube contains only the following components:
Or a copper alloy tube containing the following content by combined addition, with the balance being Cu and unavoidable impurities. The composition of this copper alloy tube is as follows:
is there. 0.05 to 5% by weight of Mn 0.05 to 5
0.05 to 5 wt% Mn and 0.0 wt% Mg
5 to 5% by weight of Mg 0.05 to 5% by weight of Mn and
0.05 to 5 wt% Zn 0.05 to 5 wt%
% Mg and 0.05 to 10% by weight Zn, or
0.05 to 5 wt% Mn, 0.05 to 5 wt%
Mg and 0.05-10% by weight Zn and
In the case of complex addition of, the content of these components in total
0.05 to 10% by weight. In the following description,
Regarding Zn, only compound addition, added alone
It does not do.

In order to improve the heat transfer performance as a heat exchanger, the copper alloy tube has a plurality of grooves parallel to the inner surface of the tube, the outer diameter of which is 4 to 25.4 mm, and the groove depth. H, the ratio h of the pipe diameter Di defined by the peak between the grooves.
Preferably, the inner grooved pipe has a / Di of 0.01 ≦ h / Di ≦ 0.05 and a torsion angle γ of the groove with respect to the pipe axis direction of 0 ° ≦ γ ≦ 30 °.

[0010]

The inventor of the present application has proposed a nest resistant to ant nest corrosion.
In order to obtain a fin tube type heat exchanger with excellent corrosivity ,
As a result of various studies, the following facts were found.

That is, ant-nest-like corrosion is caused by the carboxylic acid generated by the decomposition of organic substances such as lubricating oils and organic solvents, which are inevitably left in the assembly process of the heat exchanger, during storage and during use. It occurs locally, regardless of the inner and outer surfaces of the tube, and often causes the tube to leak.

The inventors of the present invention have conducted various experimental studies from the viewpoint that it is necessary to improve the corrosion resistance of the tube material itself. As a result, copper contained at least one of Zn, Mn and Mg. It has been found that the use of a tube made of a copper alloy containing a predetermined amount of as a tube significantly improves the corrosion resistance of the fin tube type heat exchanger. That is, a copper alloy tube containing at least one of Zn, Mn and Mg even in a corrosive environment in which ant-nest corrosion occurs in a fin tube type heat exchanger using a conventional phosphorus deoxidized copper tube. In the fin tube type heat exchanger using, the local corrosion does not progress, but shows a form of general corrosion.

As described above, the corrosion resistance of the copper alloy tube can be improved by adding a predetermined amount of Zn, Mn and Mg, because Zn, Mn and Mg are lower in potential than Cu. Because it is dissolved in Cu and is uniformly distributed,
This is considered to be because the material surface is uniformly corroded, and the corrosion products are also uniformly dissolved.

If the composition of the copper alloy tube contains less than 0.05% by weight of Zn, Mn and Mg, the effect of improving the corrosion resistance is not sufficient. On the other hand, as the content of these components increases, the effect of improving the corrosion resistance of the copper alloy tube increases. However, in the manufacturing process of the fin tube type heat exchanger, workability and brazing property of the tube are required, and these workability and brazing property are deteriorated as the amount of Zn, Mn and Mg increases. Therefore, in order to ensure the workability and brazing properties of the tube in the manufacturing process, the content of Zn is 10% by weight or less, the content of Mn and Mg is 5% by weight or less, and the total amount is 10% by weight or less. It is necessary to. In addition, since all of these additional components have the same function and effect, at least one of these components may be added. Therefore, the copper alloy which is a constituent material of the tube contains at least one component of 0.05 to 10% by weight of Zn, 0.05 to 5% by weight of Mn, and 0.05 to 5% by weight of Mg in total amount. The content is 0.05 to 10% by weight.

Further, it is preferable to use an inner grooved tube as the copper alloy tube of the fin tube type heat exchanger according to the present invention. This inner grooved tube has an outer diameter of 4 to 25 mm.
4 mm, having a plurality of grooves parallel to each other on the inner surface of the tube,
Relationship between the groove depth h and the minimum inner diameter Di (inner diameter defined by the peak) is 0.01 ≦ h / Di ≦ 0.05, and the torsion angle γ in the tube axis direction is 0 ° ≦ γ ≦ 30 °. It satisfies. Thereby, the heat transfer performance can be significantly improved.

When the outer diameter of the inner grooved tube is less than 4 mm,
The pressure loss of the heat medium increases, and sufficient heat transfer performance cannot be obtained. On the other hand, when the outer diameter exceeds 25.4 mm, the heat exchanger becomes large, which is uneconomical as a fin tube type heat exchanger. Therefore, the tube outer diameter needs to be 4 to 25.4 mm.

Further, the ratio h / to the groove depth h and the minimum inner diameter Di is defined as h /
If Di is less than 0.01, the heat transfer performance is not sufficiently improved. Conversely, if it exceeds 0.05, the pressure loss increases and the heat transfer performance tends to decrease. Further, when the torsion angle γ in the tube axis direction exceeds 30 °, the pressure loss increases, so that sufficient heat transfer performance cannot be obtained. Therefore, the ratio h / D
i is 0.01 ≦ h / Di ≦ 0.05 and the torsion angle γ
Is preferably 0 ° ≦ γ ≦ 30 °.

The use of a tube having an inner groove having such a groove formed on the inner surface as a tube provides excellent corrosion resistance against ant nest corrosion as described above, and furthermore, heat transfer as a heat exchanger. A high-performance fin tube type heat exchanger having excellent performance can be obtained.

The copper alloy tube constituting this tube may contain P and B, which are usually used as a deoxidizing agent, as unavoidable impurities, in addition to Zn, Mn, and Mg. Even if it contains the impurities described above, there is no problem in improving the corrosion resistance.

[0020]

Next, examples of the present invention will be described in comparison with comparative examples. Using a tube (annealed material) having the composition shown in Table 1 below, a fin tube type heat exchanger as shown in the plan view of FIG. 1 was prepared, and the corrosion resistance against ant nest corrosion, the heat transfer performance, and the production were made. Workability and brazing properties, which are required properties, were evaluated. FIG. 2 is a sectional view of the fin tube type heat exchanger in the axial direction of the tube, FIG. 3 is a transverse sectional view of the tube, and FIG. 4 is a partially enlarged view thereof.
Each plate-like fin 1 is substantially plate-shaped,
A plurality of tube insertion holes are formed at the center in the height direction, and a cylindrical fin collar 5 is provided on a peripheral edge of the insertion hole with its axial direction perpendicular to the fin 1. Then, the plate-shaped fins 1 are arranged so as to be parallel to each other, and the tube 2 is inserted into the fin collar 5 of each fin 1. This tube 2 has a U-shape having a hairpin bent portion 3, is inserted into a fin collar 5, expanded and fixed to the fin 1, and then both end portions of the tube 2 and the end portion of the adjacent tube 2. Are brazed to a semicircular tube 4 so that each tube 2 is connected to one tube.

The tube 2 is provided with a plurality of grooves 7 on its inner surface, and these grooves 7 extend spirally on the inner surface of the tube. The pipe inner diameter Di is defined by the crests 6 between the grooves 7, and is the minimum inner diameter.

The outer diameter of the inner grooved tube used in the fin tube type heat exchanger of this embodiment is 7 mm, the inner diameter Di is 6.14 mm, and the number of grooves is 50 in a cross section orthogonal to the tube axis.
Individual, groove depth h is 0.18 mm, bottom thickness t is 0.25 m
m, the groove bottom width W is 0.23 mm, and the torsion angle γ of the groove with respect to the tube axis direction is 18 °.

The composition of the copper alloy of the tube 2 is shown in Table 1 below. However, in Examples 1 and 2, Zn was solely added.
It is not in the scope of the present invention because it is a case.
It is just a reference example.

[0024]

[Table 1]

In the manufacture of the fin tube type heat exchanger, a volatile lubricating oil was used at the time of punching the fins and at the time of bending the tubes and expanding the tubes, and the subsequent solvent degreasing step was omitted. In addition, the brazing of the tube is a type of phosphor copper brazing (BCuP-2; a type of phosphor copper brazing specified in JIS-Z3264, containing 6.8 to 7.5% of P, the balance being mainly Cu, Other elements are 0.
(Less than 2%). Table 2 below shows the evaluation results of the various characteristics. However, the heat transfer amount in Table 2 is the heat transfer amount when the wind speed is 1.0 m / sec.

[0026]

[Table 2]

The methods for evaluating the characteristics described in Table 2 are as follows. Corrosion resistance to ant nest corrosion A fin tube type heat exchanger using tubes having the composition shown in Table 1 was operated as an indoor unit under the following conditions, and the maximum corrosion depth due to ant nest corrosion was measured. Operating environment: 30 ° C., relative humidity 80% Operating condition: Cooling operation 5 minutes and blowing operation 10 minutes were repeated for 6 months.

Heat transfer performance In a wind tunnel test apparatus, the amount of heat transfer (evaporation / condensation) as a heat exchanger was measured. The refrigerant is R-22 (CFC HCFC)
-22: The molecular formula is CHClF ₂ ), and the measurement conditions are as follows.・ Evaporation test Air side: Dry bulb temperature / wet bulb temperature 27.0 ° C
/19.0°C Refrigerant side: Heat exchanger outlet pressure 5.4kgf / cm ² Superheat degree 5.0deg ・ Condensation test Air side: Dry bulb temperature / wet bulb temperature 20.0 ° C
/15.0°C Refrigerant side: Heat exchanger inlet pressure 18.8kgf / cm ² Supercooling degree 5.0deg

Required properties and workability in production (hairpin bending: radius 10.5 mm): The occurrence of wrinkles inside the bent portion was observed. -Brazing property: A breaking test was performed by applying an internal pressure to the tube of the heat exchanger, and the fracture site was observed.

As is apparent from Table 2, examples of the present invention are shown.
Each of Nos. 3 to 7 has extremely excellent corrosion resistance against ant nest corrosion as compared with the case where conventional phosphorus deoxidized copper is used (Comparative Example 8), and the heat transfer performance which is a necessary property as a heat exchanger. Also, the workability and the brazing properties required during the production are as good as those in the case where the conventional phosphor deoxidized copper is used (Comparative Example 8).

On the other hand, in Comparative Examples 9 to 11, Zn, Mn, M
Since a tube containing a large amount of g was used, the heat transfer performance, workability, and brazing properties were reduced, and the tube was not suitable for practical use. Further, the reason why the corrosion resistance was reduced in Comparative Example 11 is considered to be that the Mg content was too large and exceeded the solid solution amount to Cu, and that Mg was precipitated.

[0032]

As described above, the termite proof according to the present invention is provided.
The fin tube type heat exchanger, which has excellent nest-like corrosiveness, has less lubricating oil and organic solvent remaining in the assembling process than the heat exchanger using conventional phosphor deoxidized copper tubes. Due to organic matter, it has extremely excellent corrosion resistance against ant-nest corrosion, which is apt to occur when repeatedly exposed to moisture and evaporation or exposed to an environment with unique temperature, humidity and ventilation conditions. It is extremely useful as a heat exchanger used in some kinds of environments.

Further, the nest-like corrosion resistance of termites according to the present invention is excellent.
The fin tube type heat exchanger uses a tube containing an element which is more potential than Cu, unlike a heat exchanger using a conventional phosphor deoxidized copper tube. Aluminum or aluminum alloy)
And the electric erosion of the fin is suppressed,
The heat transfer performance during use is not significantly reduced, and the initial heat transfer performance can be maintained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a plan view showing a fin tube type heat exchanger according to an embodiment of the present invention.

FIG. 2 is a sectional view of the tube in the tube axis direction.

FIG. 3 is a cross-sectional view of the tube.

FIG. 4 is a partially enlarged view of a cross section of the tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Plate-like fin 2; Tube 3; Hairpin bending part 4; Semicircular tube 5; Fin collar 6; Peak 7; Groove Di;

──────────────────────────────────────────────────続 き Continuing on the front page (72) Motohisa Miyafuji 14-1, Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Inside Kobe Steel, Ltd. Chofu Works (56) References JP-A-4-190096 (JP, A) JP-A-3-291345 (JP, A) JP-A-62-142995 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F28F 19/00 F28F 21/08 F28F 19/06 F28F 1/40

Claims (2)

(57) [Claims] 1. A fin tube type heat exchanger in which a plurality of plate fins made of aluminum or an aluminum alloy are arranged in parallel, and a copper alloy tube that contacts and connects each fin is arranged. The alloy tube is 0.05 to 5 wt% Mn, 0.05 to 5 wt%
Wt% Mg, 0.05-5 wt% Mn and 0.0
5 to 5% by weight of Mg, 0.05 to 5% by weight of Mn and
0.05 to 10% by weight Zn, 0.05 to 5% by weight
% Mg and 0.05 to 10% by weight Zn, or 0.1% by weight.
05 to 5% by weight of Mn, 0.05 to 5% by weight of Mg
And 0.05 to 10% by weight of Zn, combined addition
In the case of, the content of these components is 0.05 to 1 in total.
A fin tube type heat exchanger excellent in termite nest-like corrosion resistance, characterized by being a copper alloy tube containing 0% by weight and the balance being Cu and inevitable impurities. 2. The copper alloy tube has a plurality of grooves parallel to the inner surface of the tube, the outer diameter of which is 4 to 25.4 mm, and the inner diameter of the tube defined by the groove depth h and the crest between the grooves. It is characterized in that it is an internally grooved tube having a ratio h / Di to Di of 0.01 ≦ h / Di ≦ 0.05 and a torsion angle γ of the groove with respect to the tube axis direction of 0 ° ≦ γ ≦ 30 °. The fin tube type heat exchanger according to claim 1, which is excellent in termite nest-like corrosion resistance.