JP2000111169A - Water tube for heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water tube for a heat exchanger capable of improving a thermal efficiency and expecting a corrosion resistance to a drain and easily brazing an end of the exchanger to a bend. SOLUTION: The water tube A is constituted in a double structure of an inner tube 1 made of a material having good processsability and connectability and an outer tube 2 made of a material having good corrosion resistance. The tube 2 is constituted in a shorter size than the tube 1 so that the tube 1 is exposed at an end of the tube A. An annular or spiral flare 3 is compression formed in a fin-like state to bulge toward an outside by flaring an outer periphery of the tube 2, and the tube 1 is brought into close contact with the tube 2 in an enlarged state to be superposed with the tube 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water pipe for a heat exchanger which is less likely to be corroded by drainage and which can be easily brazed and joined with a bend or the like.

[0002]

2. Description of the Related Art Conventionally, most heat exchangers mounted on water heaters and the like use a water pipe with fins mounted around the heat exchanger, and are usually designed with a thermal efficiency of about 80%. Copper, which has a very high thermal conductivity, is exclusively used as a material for forming the water pipe. Various improvements have been made in the past to improve the heat efficiency of the heat exchanger. For example, a high efficiency heat exchanger as shown in FIG. 3 has been proposed.
3A and 3B show an overall view of the high-efficiency heat exchanger, in which FIG. 3A is a front view, and FIG. In the high-efficiency heat exchanger shown in FIG. 3, the heat exchanger is connected to a drain generator (second
(A heat exchanger) 10 and a drain non-generating section (first heat exchanger) 11 and receive a drain so that generated drain does not drip.
12 and the like are provided so that the drain from the drain receiver 12 can be discharged from the drain outlet 13 to the outside. Incoming water from outside the system is taken in through the water inlets 14 and 15 and supplied to the water pipes on the first heat exchanger 11 side and the water pipes of the second heat exchanger 10, respectively. At the outlet 16 and 17. The drain generated on the second heat exchanger 10 side accumulates in the drain receiver 12 and is discharged from the drain outlet 13. The first
The water tubes of the heat exchanger 11 and the second heat exchanger 10 are both formed of copper water tubes. Reference numeral 18 denotes a bend for connecting the water tubes. By separating the heat exchanger into the drain generation unit (second heat exchanger) 10 and the drain non-generation unit (first heat exchanger) 11 as described above, the heat efficiency of the heat exchanger is dramatically improved. On the other hand, a large amount of condensed water (hereinafter referred to as “drain”) generated by condensing moisture in the heat gas in the heat exchanger is generated in the heat exchanger. As shown in the above, there is a problem that the copper water pipe is corroded by the drain and has poor durability. Therefore, as a heat exchanger that solves the above-mentioned problem, there has been proposed a heat exchanger in which the water pipe portion forming the second heat exchanger is formed of titanium having high corrosion resistance in place of a conventional copper material.
The heat exchanger can be protected from drain corrosion.

[0003]

However, as described above, by replacing the water tube constituting the second heat exchanger with copper which has been conventionally used, and using titanium having high corrosion resistance, corrosion due to drainage can be caused. Even if the disadvantages can be solved, the improvement of the heat efficiency of the heat exchanger cannot be expected because the material of titanium is extremely poor in heat efficiency, and titanium has poor brazing and joining properties, so the second heat exchanger is composed. In addition, it has become difficult to braze / join with a bend or the like at the end of the water pipe, which causes new manufacturing defects.

[0004] The present invention has solved the disadvantages of the above-mentioned heat exchanger such as difficulty in brazing and joining, and is intended to be used as a water pipe of a second heat exchanger constituting a high-efficiency heat exchanger. Not only can thermal efficiency be improved,
An object of the present invention is to provide a water pipe for a heat exchanger which can be expected to have remarkable corrosion resistance against drainage and can easily perform brazing / joining between the end of the water pipe and a bend.

[0005]

In order to achieve the above object, a water pipe for a heat exchanger according to the present invention comprises an inner pipe made of a material having good workability and bonding property and an outer pipe made of a material having good corrosion resistance. The outer tube is configured to have a double structure, and the outer tube is configured to be shorter than the inner tube so that the inner tube is exposed at the end of the water tube, and the outer periphery of the outer tube is flared. The ring-shaped or spiral-shaped flare portion is formed in a fin-like shape so as to bulge outward, and the inner tube is tightly overlapped with the outer tube in an expanded state. It has one feature.

A second feature of the water pipe for a heat exchanger of the present invention is that, in addition to the first feature, an inner pipe is provided for a predetermined length from an end of the water pipe to form a double structure.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a structural diagram showing a procedure for manufacturing a water pipe for a heat exchanger according to a first embodiment of the present invention.
(A) is a cross-sectional view showing a stage where an inner tube is inserted into an outer tube having a fin-shaped flare portion formed outward, and (B) is a cross-sectional view showing a stage where the inner tube is expanded with respect to the outer tube. And FIG.
It is sectional drawing of the water pipe for heat exchangers in 2nd embodiment.

First, the configuration of a water pipe for a heat exchanger according to a first embodiment of the present invention will be described with reference to FIG.
The outer periphery of the outer tube 2 made of a material having good corrosion resistance such as titanium is subjected to a ring-shaped or spiral-shaped flare process to form a fin-shaped compressed flare portion 3, and the inside of the outer tube 2 is formed. By inserting the inner tube 1 made of a material having good workability and bonding properties such as copper and expanding the inner tube 1,
Both tubes are tightly connected. Thereby, the water pipe A having a double structure is obtained. In the water pipe A, the outer pipe 2 is set to be shorter than the inner pipe 1 so that the surface of the inner pipe 1 is always exposed from the end of the outer pipe 2 over a certain width. The exposed portion of the tube 1 is used as a brazed portion 3a for brazing to the bend 18 and the like.

According to the above embodiment,
The heat transfer area can be increased by inserting the inner tube 1 into the outer tube 2 having the flare portion 3 formed on the outer periphery and expanding the inner tube 1 to form a water tube having a double structure in which both are brought into close contact with each other.
Since the flare portion 3 is formed in a fin-shaped compression, the inner surface of the outer tube is kept relatively smooth, the contact state between the inner tube and the outer tube is improved, and the thermal efficiency can be improved. In addition, inner pipe 1
The processing is extremely easy and the inner surface of the water pipe A is smooth as compared with the case where the pipe is expanded and brought into close contact with the outer pipe 2 to form a double-structured water pipe and then flared. And the erosion phenomenon hardly occurs. Further, at the end of the water tube A having the double structure, the surface of the inner tube 1 is a brazed portion 3a exposed at a constant width, and the inner tube 1 is made of a material having excellent brazing properties such as copper. Since it is formed, joining with the bend 18 for connecting the water pipes A becomes extremely easy. Since the outer tube 2 covering the inner tube 1 is formed of a material having good corrosion resistance such as titanium, the outer tube 2 exhibits a sufficient corrosion resistance effect to the drain generated in the heat exchanger, and prevents corrosion caused by the drain. Can be avoided. As described above, the water pipe for the heat exchanger according to the present embodiment is optimally used as a water pipe for the second heat exchanger constituting the high-efficiency heat exchanger, but it can be used as a water pipe for the first heat exchanger. Not even.

According to the second embodiment shown in FIG. 2, the water pipe A is provided with the inner pipe 1 only at its end, and has a double structure with the outer pipe 2. This facilitates the joining of the end of the water pipe A with a bend or the like by brazing, and can reduce the material cost of the inner pipe 1. And since the outer tube 2 is formed of a material having good corrosion resistance such as titanium, the outer tube 2 exerts a sufficient corrosion resistance effect on the drain generated in the heat exchanger and aims to avoid corrosion due to the drain. Can be. Further, the thermal efficiency is improved as compared with the case where the water pipe A has a double structure over the entire length.

[0011]

According to the present invention, there is provided the above construction.
The water pipe for a heat exchanger according to the above is configured as a water pipe having a double structure of an inner pipe made of a material having good workability and bonding property and an outer pipe made of a material having good corrosion resistance, and an end of the water pipe. The outer tube is configured to be shorter than the inner tube so that the inner tube is exposed at the inner tube, and a ring-shaped or spiral-shaped flare portion formed by flaring on the outer periphery of the outer tube expands outward. The inner tube is formed in a fin-like shape so as to come out, and the inner tube is in close contact with the outer tube in an expanded state, so that the heat transfer area can be increased and the flare portion is As a result, the inner surface of the outer tube is kept relatively smooth, the contact between the inner tube and the outer tube is improved, and the thermal efficiency can be improved. At the end of the water tube having the double structure, the surface of the inner tube is a brazed portion exposed at a constant width, and the inner tube is formed of a material having excellent brazing properties such as copper. Therefore, joining with the bend becomes easy. Since the outer tube covering the inner tube is formed of a material having good corrosion resistance, such as titanium, the outer tube exhibits a sufficient corrosion resistance effect even for the drain generated in the heat exchanger, and protects from corrosion due to the drain. be able to. Furthermore, since the inner tube is not flared, the inside of the water tube becomes smooth and the erosion phenomenon is less likely to occur, and the durability is improved. Further, according to the water pipe for a heat exchanger according to the second aspect, the joining of the end of the water pipe by brazing with a bend or the like becomes easy, and the material cost of the inner pipe can be reduced. Since the outer tube is made of a material having good corrosion resistance such as titanium, the outer tube exerts a sufficient corrosion resistance effect on drain generated in the heat exchanger, and can be protected from corrosion due to drain. Further, the thermal efficiency is improved as compared with the case where the water pipe has a double structure over the entire length.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a procedure for assembling a water pipe for a heat exchanger according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a water pipe for a heat exchanger showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a high-efficiency heat exchanger to which the water pipe for a heat exchanger shown in the embodiment of the present invention is optimally applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner pipe 2 Outer pipe 3 Flare part 3a Brazing part A Water pipe

Claims (2)

[Claims] 1. A water pipe having a double structure comprising an inner pipe made of a material having good workability and bonding properties and an outer pipe made of a material having good corrosion resistance, and an inner pipe formed at an end of the water pipe. The outer tube is configured to be shorter than the inner tube so that is exposed.
On the outer periphery of the outer tube, a ring-shaped or spiral flare portion formed by flaring is formed into a fin shape so as to bulge outward, and the inner tube is expanded with respect to the outer tube. A water pipe for a heat exchanger, wherein the water pipe is a closely-coupled heavy pipe. 2. The water pipe for a heat exchanger according to claim 1, wherein an inner pipe is provided for a predetermined length from an end of the water pipe to form a double structure.