JP2015025577A - Method of manufacturing triple tube type heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a triple tube type heat exchanger which assures high heat exchanging performance by configuring a multi-leaf tube in which an inner tube and a leakage detection tube are repeated as a mountain part and a valley part in circumferential direction.SOLUTION: A triple tube type heat exchanger 1 is configured to perform heat exchange between a fluid that flows inside an inner tube 2 and a fluid that flows a gap in a leakage detection tube 3 and an outer tube 4. A double multi-leaf tube 7 including the inner tube 2 and the leakage detection tube 3 is inserted in an outer tube material tube 4A having a circular cross section as the outer tube 4 whose inner diameter is similar to the size of the outer diameter of the double multi-leaf tube 7. By applying a diameter contraction process to the outer tube material tube 4A in which the double multi-leaf tube 7 is inserted so that a contraction rate becomes 84% or less, an inner peripheral surface of the outer tube 4 is made to tightly contact to the mountain part of the double multi-leaf tube 7.

Description

  The present invention relates to a method for manufacturing a triple tube heat exchanger, and more particularly, a triple tube in which a multi-leaf tube having a double structure including an inner tube and a leak detection tube fitted to the inner tube is accommodated inside the outer tube. The present invention relates to a method for manufacturing a tubular heat exchanger.

  In hot water storage and hot water storage devices that store hot water heated by gas combustion heat source devices, heat pump heat source devices, fuel cells, etc., heating devices that use hot water, and other various industrial fields, there is a gap between hot and cold fluids. Various heat exchangers for heat exchange are used.

  In particular, the double-pipe heat exchanger has been widely adopted because it has excellent heat exchange performance and is advantageous in terms of manufacturing cost. Recently, the pipe wall as an inner pipe has a crest and a trough in the circumferential direction. A double-tube heat exchanger in which a multi-leaf tube having a repetitive waveform shape is used and the multi-leaf tube is housed inside an outer tube is also widely used.

  For example, in the double-pipe heat exchanger disclosed in Patent Document 1, an inner tube made up of a corrugated multi-leaf tube that alternately repeats crests and valleys in the circumferential direction is housed inside the outer tube, The tops of the six peaks are brought into close contact with the inner peripheral surface of the outer tube, and the six valleys are formed in a state of being separated from each other.

  Here, for example, in a double-pipe heat exchanger used in a hot water storage hot water supply apparatus, when a coolant is passed through the inner pipe and hot water is passed through the gap between the inner pipe and the outer pipe, a crack occurs in the inner pipe. Then, there exists a possibility that a refrigerant | coolant may leak and mix with hot water.

  Therefore, in Patent Document 2, when the fluid flowing inside the tube member leaks to the outside of the tube member, the leakage is detected and the leaked fluid is prevented from being mixed into the fluid outside the tube member. In addition, a double structure leak detection tube is disclosed in which a leak detection outer tube having a large number of leak detection grooves formed on the inner peripheral surface thereof is tightly fitted to the tube member.

JP 2008-232449 A Japanese Patent No. 3933083

In the double-pipe heat exchanger described in Patent Document 1, since the inner tube made of a multi-leaf tube does not have a leakage prevention function, there is a risk of leakage of fluid flowing in the inner tube. It is desirable to have a certain inner pipe. Therefore, when the double structure leak detection tube described in Patent Document 2 is formed into a double multi-leaf tube, and a triple tube heat exchanger composed of the double multi-leaf tube and an outer tube is manufactured, Since there are air layers in the multiple leak detection grooves in the tube wall of the double pipe heat exchanger, it is difficult to ensure high heat exchange performance.

  Also, in the case of a double-pipe heat exchanger that employs a multi-leaf tube as the inner tube, stress concentration is likely to occur due to the small curvature radius of the valleys and peaks, making it difficult to increase durability, rigidity and strength, etc. There is a problem.

  The object of the present invention is a triple tube type that can ensure high heat exchange performance, high strength and durability while constituting the inner tube and the leak detection tube into a double multi-leaf tube that repeats a crest and a trough in the circumferential direction. It is to provide a method for manufacturing a heat exchanger.

  The method for manufacturing a triple-pipe heat exchanger according to claim 1 includes: an inner tube formed of a multi-leaf tube having a corrugated shape in which a tube wall repeats a crest and a trough in the circumferential direction; A leak detection pipe made of a multi-leaf pipe and externally fitted to the inner pipe and disposed in the vicinity of the outer peripheral surface of the inner pipe; and an outer pipe in which the inner pipe and the leak detection pipe are housed, In the method of manufacturing a triple pipe heat exchanger configured to perform heat exchange between a fluid flowing inside an inner tube and a fluid flowing in a gap between the leak detection tube and the outer tube, Inserting a double multi-leaf tube consisting of an inner tube and the leakage detection tube into an outer tube material tube having a circular cross section as an outer tube having an inner diameter that is substantially the same as the outer diameter of the double multi-leaf tube, By reducing the diameter of the outer tube material tube in which the double multi-leaf tube is inserted so that the diameter reduction rate is 84% or less, the inner peripheral surface of the outer tube and the mountain of the double multi-leaf tube It is characterized by adhering the and.

  A method for manufacturing a triple-pipe heat exchanger according to a second aspect is the invention according to the first aspect, wherein when the outer pipe material pipe into which the double multi-leaf pipe is inserted is reduced in diameter, a double multi-leaf pipe is used. It is characterized by contacting the valleys adjacent to each other in the circumferential direction.

According to the first aspect of the present invention, a double multi-leaf tube composed of an inner tube and a leak detection tube is formed on the outer side of a circular cross section as an outer tube having an inner diameter that is substantially the same as the outer diameter of the double multi-leaf tube. Inserting into the tube material tube, and reducing the diameter of the outer tube material tube into which the double multi-leaf tube is inserted so that the diameter reduction rate is 84% or less, and the inner peripheral surface of the outer tube and the double multi-leaf Since the ridges of the tube are brought into close contact with each other, the adhesion between the outer tube and the ridges of the double multi-leaf tube is increased, so that the rigidity, strength, and durability of the triple tube heat exchanger can be increased.
Moreover, when the double multi-leaf tube is inserted into the outer tube material tube, a predetermined gap can be secured between the double multi-leaf tube and the outer tube material tube. Can be inserted smoothly.

  According to the invention of claim 2, in order to reduce the diameter of the outer tube material tube into which the double multi-leaf tube is inserted, in order to bring the valleys adjacent in the circumferential direction of the double multi-leaf tube into contact with each other, The rigidity and strength at the center side portion of the triple pipe heat exchanger can be increased, and the valley portion of the inner pipe is less likely to vibrate due to vibration propagating from the fluid.

It is sectional drawing of the triple tube | pipe type heat exchanger which concerns on the Example of this invention. It is sectional drawing of a large diameter pipe and a small diameter pipe inserted in it. It is sectional drawing of a double multileaf tube. It is a fragmentary perspective view of a double multileaf tube. (A) is sectional drawing of an outer tube | pipe and the double multileaf tube inserted in it, (b) is sectional drawing of the triple tube | pipe type heat exchanger after diameter reduction processing. It is a fragmentary perspective view of a triple pipe type heat exchanger.

  Hereinafter, modes for carrying out the present invention will be described based on examples.

  Before explaining the manufacturing method of the triple pipe heat exchanger according to the present invention, the structure of the triple pipe heat exchanger will be explained first.

  As shown in FIG. 1, the triple tube heat exchanger 1 includes an inner tube 2, a leak detection tube 3, and an outer tube 4. The inner tube 2 is configured as a multi-leaf tube having a corrugated shape in which the tube wall repeats a crest 2b and a trough 2a in the circumferential direction. The leak detection tube 3 is a multi-leaf tube having substantially the same shape as the inner tube 2. The leak detection tube 3 is arranged in the vicinity of the outer peripheral surface of the inner tube 2 by being externally fitted to the inner tube 2. A double multi-leaf tube 7 is formed. A double multi-leaf tube 7 including an inner tube 2 and a leak detection tube 3 is accommodated in the outer tube 4.

  As shown in FIG. 4, the double multi-leaf tube 7 is configured in a spirally twisted shape with a predetermined lead angle. The predetermined lead angle is an angle that makes one rotation for every 300 to 500 mm in the axial direction, for example. However, the above twisting may be omitted.

  Inside the inner pipe 2, an inner fluid passage 5 is formed which is composed of a fluid passage 5 a surrounded by four valleys 2 a and four fluid passages 5 b inside the crest 2 b, and a leak detection pipe 3 and an outer pipe 4 are formed. The outer fluid passage 6 including four fluid passages 6a having a substantially triangular section is formed between the fluid (for example, heat pump refrigerant) flowing inside the inner tube 2 (inner fluid passage 5), and the leak detection tube. 3 is configured to be able to exchange heat with a fluid (for example, hot water for hot water supply) flowing through a gap 6a (outer fluid passage 6) between the outer pipe 4 and the outer pipe 4.

  The inner pipe 2 has four valleys 2a and four peaks 2b, the valley 2a has an arc shape, and the peaks 2b have a shape with curved portions at both ends of the arc. The four valley portions 2a are arranged at 90 ° intervals in the circumferential direction around the fluid passage 5a having a substantially square cross section at the center, and the vicinity of the tip of each valley portion 2a is in contact with the valley portion 2a adjacent in the circumferential direction. ing.

  The leak detection tube 3 has four valleys 3a and four peaks 3b, the valleys 3a have an arc shape, and the peaks 3b have a shape with curved portions at both ends of the arc. . Each trough 3a is located in the vicinity of the outer surface of the trough 2a of the corresponding inner pipe 2, and a crescent-shaped fluid is provided between each trough 2a of the inner pipe 2 and the corresponding trough 3a of the leak detection pipe 3. A gap 8 through which can be circulated is formed.

  The inner pipe 2 has a straight pipe wall 2c that connects the peak 2b and the valley 2a, and the leak detection pipe 3 has a straight pipe wall 3c that connects the peak 3b and the valley 3a, The straight tube wall 2c of the tube 2 and the straight tube wall 3c of the leak detection tube 3 opposed thereto are in close contact with each other in a surface contact state. Therefore, the heat exchange performance between the inner pipe 2 and the leak detection pipe 3 is high, and the heat exchange performance between the fluid flowing in the inner fluid passage 5 and the fluid flowing in the outer fluid passage 6 is improved. The peak portion 2b and the pair of straight tube walls 2c connected to the peak portion 2b have a shape close to a fan shape with an opening angle of about 45 °. The same applies to the leak detection tube 3.

Most of the crest 2b of the inner tube 2 is in close contact with the inner surface of the crest 3b of the leak detection tube 3, and most of the crest 3b of the leak detection tube 3 is in surface contact with the inner surface of the outer tube 4. It is closely attached to the shape. Therefore, the heat exchange performance between the fluid flowing in the inner fluid passage 5 and the fluid flowing in the outer fluid passage 6 is improved.
Further, a small crescent-shaped gap 9 is formed between the inner tube 2 and the leak detection tube 3 on both sides of each peak portion 2 b of the inner tube 3. The triple-pipe heat exchanger 1 is usually used as a coil-shaped heat exchanger wound in a plurality of spirals.

Next, a method for manufacturing the triple-pipe heat exchanger 1 will be described with reference to FIGS.
As shown in FIG. 2, a metal small-diameter pipe 2A having a circular cross section is prepared in advance as a material pipe for the inner pipe 2, and a large metal cross-section having a larger diameter than the small-diameter pipe 2A is prepared as a material pipe for the leak detection pipe 3. A diameter tube 3A is prepared in advance, and a metal outer tube material tube 4A having a circular cross section is prepared in advance as a material tube of the outer tube 4.

  The small-diameter pipe 2A is a copper pipe for water supply made of phosphorous deoxidized copper or an equivalent product (for example, an outer diameter of 18.0 mm, a pipe wall thickness of 0.6 mm, and a length of 6 m). The large-diameter pipe 3A is a copper pipe for water supply made of phosphorous deoxidized copper or an equivalent product (for example, an outer diameter of 20.7 mm, a pipe wall thickness of 0.6 mm, and a length of 6 m). The outer pipe material pipe 4A is a copper pipe for water supply made of phosphorous deoxidized copper or an equivalent product (for example, an outer diameter of 19.05 mm, a pipe wall thickness of 0.7 mm, and a length of 6 m).

  When manufacturing a double-walled multileaf tube 7 (hereinafter referred to as a double-leaflet tube) composed of the inner tube 2 and the leak detection tube 3, the material tube of the inner tube 2 is used as the material tube of the leak detection tube 3. The double tube (see FIG. 2) inserted into the tube is processed into a double multi-leaf tube 7 (see FIGS. 3 and 4). In this double multi-leaf tube 7, there is a gap between each valley 2a of the inner tube 2 and the valley 2a adjacent thereto.

  Next, as shown in FIG. 5A, the double multi-leaf tube 7 is inserted into a metal outer tube material tube 4 </ b> A having a circular cross section as the outer tube 4. In this inserted state, there is a predetermined gap 7a between the outer periphery of the double multi-leaf tube 7 and the inner peripheral surface of the outer tube material tube 4A. However, since the torsion is added to the double multi-leaf tube 7 and the linearity is lowered, the double multi-leaf tube 7 and the outer tube 4 are not always concentric over the entire length. Absent.

  Next, as shown in FIG. 5 (b), by reducing the diameter of the outer tube material tube 4A in which the double multi-leaf tube 7 is inserted, the inner peripheral surface of the outer tube material tube 4A and the double multi-leaf tube 7 is closely attached to each other, and each valley 2a of the inner pipe 2 is closely attached to the valley 2a adjacent thereto. Thus, a triple pipe heat exchanger 1 as shown in FIGS. 1 and 6 can be manufactured.

  In this diameter reduction processing, the inner peripheral surface of the outer tube 4 and the crest portion 3b of the double multi-leaf tube 7 are brought into close contact with each other by reducing the diameter of the outer tube material tube 4A to 84% or less. Let When the outer tube material tube 4A is reduced in diameter, the double multi-leaf tube 7 is slightly reduced in diameter so that the valley portions 3a adjacent to each other in the circumferential direction of the double multi-leaf tube 7 are brought into contact with each other. In this case, when the outer diameter of the double multi-leaf tube 7 is, for example, 16.0 mm as described above, the diameter reduction rate of the double multi-leaf tube 7 is 90%.

  However, it is desirable to reduce the diameter of the double multi-leaf tube 7 as described above when reducing the diameter of the outer tube material tube 4A as described above, but the diameter reduction rate of the outer tube material tube 4A is 84% or less. If the inner peripheral surface of the outer tube 4 and the peak portion 3b of the double multi-leaf tube 7 are in close contact with each other in a state of being reduced in diameter, it is not always necessary to reduce the diameter of the double multi-leaf tube 7. .

The effect | action and effect of the manufacturing method of the triple tube | pipe type heat exchanger 1 demonstrated above are demonstrated.
The double multi-leaf tube 7 is inserted into the outer tube material tube 4A with a predetermined gap 7a, and the outer tube material tube 4A into which the double multi-leaf tube 7 has been inserted is reduced in diameter, whereby the outer tube 4 A triple pipe heat exchanger having a structure in which the peak 3b of the double multi-leaf tube 7 is in close contact with the inner peripheral surface of the outer tube 4 in order to bring the inner peripheral surface into close contact with the peak 3b of the double multi-leaf tube 7. 1 and the triple tube heat exchanger 1 having excellent heat exchange performance between the double multi-leaf tube 7 and the outer tube 4 can be manufactured.

Table 1 shows the durability of a triple-tube heat exchanger that has been reduced in diameter at various reduction ratios with the double multi-leaf tube 7 inserted into the same or similar material tube as the outer tube material tube 4A. The test result about is shown.
In this test, a high pressure and a low pressure corresponding to usage conditions are repeatedly applied to the refrigerant in the double multi-leaf tube 7 every predetermined time (for example, every 2 seconds), and the number of times until the breakage (the number of durability) is determined. Measured. As a result, when the diameter reduction ratio was 99.7%, damage occurred at 86,000 times, and when the diameter reduction ratio was 94.5%, damage occurred at 230000 times. On the other hand, it was confirmed that when the diameter reduction ratio was 84%, no damage occurred until 310,000 times, and the durability performance was improved.

In the manufacturing method of the triple pipe heat exchanger 1 of the present application, the rigidity / strength of the triple pipe heat exchanger 1 is set so that the diameter reduction rate when the diameter of the outer pipe material pipe 4A is reduced is 84% or less. As a result, durability can be greatly improved.
Moreover, when the outer tube material tube 4A is reduced in diameter, the double multi-leaf tube 7 is slightly reduced in diameter so that the valleys 3a adjacent to each other in the circumferential direction of the double multi-leaf tube 7 are brought into contact with each other. The rigidity and strength at the center side portion of the triple-pipe heat exchanger 1 can be increased, and the valley portion 2a of the inner tube 2 is less likely to vibrate due to vibration propagating from the fluid.

  If the diameter reduction process is not performed, the outer peripheral surface of the double multi-leaf tube 7 is not in close contact with the inner surface of the outer tube 4, and the relative movement becomes free. Thus, the double multi-leaf tube 7 is easy to move, stress concentration occurs in the valleys 2a and 3a and the peaks 2b and 3b, and rigidity, strength, and durability are lowered. Moreover, since there is a gap between the adjacent valley portions 3a of the double multi-leaf tube 7, the structure is easily deformed and easily damaged.

Moreover, since the double multi-leaf tube 7 is twisted and its linearity is lowered, the double multi-leaf tube 7 having a length of about 6 m is replaced with an outer tube material tube 4A having a length of about 6 m. Not easy to insert into.
Therefore, by setting the reduction ratio to 84% or less as described above, when the double multi-leaf tube 7 is inserted into the outer tube material tube 4A, a predetermined gap 7a can be secured between them. Therefore, it can be inserted smoothly. When the diameter reduction ratio is larger than 84% (for example, 85 to 99%), not only the strength and durability of the triple pipe heat exchanger 1 cannot be improved much, but the predetermined gap 7a is very small. Due to the gap, it becomes difficult to insert the double multi-leaf tube 7 into the outer tube material tube 4A.

  A double multi-leaf tube 7 having excellent heat transfer (heat exchange performance) and also having leakage detection gaps 8 and 9 as described above is manufactured from a small diameter tube 2A and a large diameter tube 3A each having a circular cross section. Using the multi-leaf tube 7 and the outer tube material tube 4A, the triple-pipe heat exchanger 1 with excellent heat exchange performance is manufactured easily. Can be produced.

Next, an example in which the above embodiment is partially changed will be described.
1) The number of valleys 2a and 3a and the number of peaks 2b and 3b in the double multi-leaf tube 7 including the inner tube 2 and the leakage detection tube 3 are not limited to four, and may be three or five or more.

  2) The metal material of the material tube of the inner tube 2, the leak detection tube 3 and the outer tube 4 is not limited to phosphorous deoxidized copper, but may be other various copper materials, and may be a metal other than copper (for example, aluminum or The alloy, brass, magnesium alloy, titanium, etc.) may be used. The inner tube 2, the leak detection tube 3, and the outer tube 4 are not necessarily manufactured from a material tube of the same kind of metal material, but may be manufactured from a material tube of a different kind of metal material. Moreover, the thickness of the tube wall of the inner tube 2 and the thickness of the tube wall of the leak detection tube 3 may be the same or different.

3) The shape of the outer contour of the cross section of the triple-pipe heat exchanger 1 can be configured to have a shape other than a circle (for example, an ellipse or an oval).
4) The outer diameter, tube wall thickness and length of the small-diameter pipe 2A, large-diameter pipe 3A, and outer pipe material pipe 4A are limited to those described in the above embodiment. It can be set to various outer diameters.

  5) In addition, those skilled in the art can implement the present invention in a form in which various modifications are added without departing from the spirit of the present invention.

  A method for manufacturing a triple-pipe heat exchanger for heat exchange between two kinds of fluids, which is usable in various industrial fields, is disclosed.

DESCRIPTION OF SYMBOLS 1 Triple pipe type heat exchanger 2A Small diameter pipe 2 Inner pipe 2a Valley part 2b Mountain part 2c Straight line part 3A Large diameter pipe 3 Leakage detection pipe 3a Valley part 3b Mountain part 3c Straight line part 4A Outer pipe material pipe 4 Outer pipe 5 Inside Fluid passage 6 Outer fluid passage 7 Double multi-leaf tube 8, 9 Clearance

Claims (2)

An inner tube consisting of a multi-leaf tube having a corrugated shape in which the crest and trough are repeated in the circumferential direction in the circumferential direction, and a multi-leaf tube having substantially the same shape as this inner tube, and is fitted to the inner tube to be fitted to the inner tube. A leakage detection tube disposed in the vicinity of the outer peripheral surface; an outer tube in which the inner tube and the leakage detection tube are housed; a fluid flowing inside the inner tube; and the leakage detection tube and the outer tube A method of manufacturing a triple pipe heat exchanger configured to exchange heat with a fluid flowing in a gap between
A double multi-leaf tube comprising the inner tube and the leak detection tube is inserted into an outer tube material tube having a circular cross section as an outer tube having an inner diameter that is substantially the same as the outer diameter of the double multi-leaf tube. The outer tube material tube into which the double multi-leaf tube is inserted is reduced in diameter so that the reduction ratio is 84% or less, whereby the inner peripheral surface of the outer tube and the mountain portion of the double multi-leaf tube are formed. A method for producing a triple-pipe heat exchanger, wherein the heat exchanger is closely attached.   The trough portions adjacent to each other in the circumferential direction of the double multi-leaf tube are brought into contact with each other when the outer tube material tube into which the double multi-leaf tube is inserted is reduced in diameter. A manufacturing method of a triple tube heat exchanger.