JP2009243715A - Leakage detecting tube and heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage detecting tube having high heat exchanging performance, and a heat exchanger using the leakage detecting tube. <P>SOLUTION: In this leakage detecting tube 1A comprising an inner tube 7B and an outer tube 2A fitted to an outer side of the inner tube 7B, and detecting the leakage of water or a refrigerant circulated inside of the inner tube 7B or outside of the outer tube 2A through a leakage pathway 6 formed between the inner tube 7B and the outer tube 2A, the outer tube 2A includes an outer tube irregularities 3 composed of a number of recesses 4 and protrusions 5 formed along the tube circumferential direction on at least part of a region of the total length, the recesses and the protrusions 5 of the outer tube irregularities 3 extend along the tube axial direction of the outer tube 2A, the outer tube 2A is kept into contact with the inner tube 7B at inner faces of bottom sections of the recesses of the outer tube irregularities 3, and the leakage pathway 6 is formed by an outer peripheral face of the inner tube 7B and inner faces of the protrusions 5 of the outer tube irregularities 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a leak detection tube used for detecting leakage of water and refrigerant in a heat exchanger configured using water and refrigerant as a heat medium, and a heat exchanger provided with the leak detection tube. .

  Generally, a heat exchanger having a large-diameter tube and a small-diameter tube as a leak detection tube inside the large-diameter tube is known. For example, in a heat exchanger for a water heater, generally, a first heat medium (for example, water) is allowed to flow inside a large diameter pipe, and a second heat medium is disposed inside a small diameter pipe (leakage detection pipe, heat transfer pipe). (For example, a refrigerant such as carbon dioxide or alternative chlorofluorocarbon) is flowed to exchange heat between them.

  In such a heat exchanger, it is required to improve the heat exchange performance between the heat media from the viewpoint of increasing the operation efficiency. As an example, a plurality of leak detection tubes (= A heat exchanger having a structure in which a small-diameter pipe is included and an inner material and a baffle material are arranged inside the large-diameter pipe is known (for example, see Patent Document 1). As another example, a heat exchanger having a structure in which a small-diameter pipe (= leakage detection pipe) is included in a large-diameter pipe is known (for example, see Patent Document 2).

The heat exchanger disclosed in Patent Document 1 increases the heat transfer area by increasing the number of small-diameter pipes (leakage detection pipes), and the heat medium flows through the large-diameter pipes by an inner material or a baffle material. The heat transfer performance is improved by generating a turbulent flow. Further, in the heat exchanger disclosed in Patent Document 2, a leak detection tube is configured by fitting a smooth tube to the outer periphery of a heat transfer tube subjected to corrugation, and the leak detection tube is arranged inside the large diameter tube. The refrigerant is arranged between the leak detection tube and the large-diameter tube, and water is allowed to flow in the heat transfer tube, and it is said that excellent heat exchange performance can be obtained even at a low flow rate.
Japanese Unexamined Patent Publication No. 2006-46888 (paragraphs [0069], [0076], FIG. 3, FIG. 5, etc.) JP 2007-218486 A (Claim 6, paragraph [0024], FIG. 4 etc.)

  However, in the heat exchanger disclosed in Patent Document 1, since the smooth tube is used as the leak detection tube, the heat transfer area cannot be widened. Therefore, the inner material and the baffle material are disposed inside the large diameter tube. Even if it is provided, it is difficult to dramatically improve the heat transfer performance. Moreover, the problem that the pressure loss of the heat medium which flows through a large diameter pipe becomes large by the inner material and baffle material which are arrange | positioned inside a large diameter pipe also arises.

  In the heat exchanger disclosed in Patent Document 2, since the refrigerant flows through the large-diameter pipe, the heat of the refrigerant is radiated to the outside through the large-diameter pipe, thereby causing the leak detection pipe (heat transfer pipe) to be dissipated. There is a problem that the amount of heat transfer to the flowing water is reduced and the heat transfer performance is reduced. In order to improve the heat transfer performance to water, it is conceivable to increase the outer diameter of the leak detection tube to increase its surface area. However, in that case, the diameter of the heat transfer tube inside the leak detection tube becomes large, and the flux of water flowing in the heat transfer tube becomes slow, so that the heat transfer performance is not improved. Further, although it is conceivable to improve the heat transfer performance by a method such as providing a baffle plate on the outer surface of the leak detection tube, there is a problem that it is difficult to obtain an effect commensurate with an increase in manufacturing cost.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a leak detection tube having high heat exchange performance and a heat exchanger using the leak detection tube.

  In the leak detection pipe according to the present invention, the leak detection pipe according to claim 1 includes an inner pipe and an outer pipe fitted to the outer side of the inner pipe, and circulates inside the outer pipe or outside the outer pipe. A leakage detection tube that detects leakage of water or refrigerant through a leakage path formed between the inner tube and the outer tube, and the outer tube is in at least a part of its entire length. An outer tube concavo-convex portion comprising a large number of concave portions and convex portions formed along the pipe circumferential direction, and the concave and convex portions of the outer pipe concavo-convex portion extend along the tube axis direction of the outer tube. The outer tube has an inner surface of the bottom portion of the concave portion of the outer tube concavo-convex portion that contacts the inner tube, and the leakage path includes an outer peripheral surface of the inner tube and an inner surface of the convex portion of the outer tube concavo-convex portion. It is formed by.

  According to such a configuration, the outer tube constituting the leak detection tube includes the outer tube uneven portion, so that water or refrigerant flowing outside the outer tube is agitated and the outer surface area of the outer tube is increased. To increase. This improves the heat transfer performance of the leak detection tube.

In the leak detection tube according to claim 2, the outer tube uneven portion has a ratio (HS ₁ / OD ₁₎ between the recess depth HS ₁ of the recess and the maximum outer diameter OD ₁ of the outer tube in a cross section orthogonal to the tube axis. ) Is 0.02 to 0.1, and the number of the recesses is 4 to 32.

  According to such a configuration, since the shape of the outer tube uneven portion is optimized, the water or refrigerant flowing outside the outer tube is further stirred, so the heat transfer performance of the leak detection tube is further improved. To do.

The leak detection tube according to claim 3 is characterized in that the outer tube uneven portion is formed in a spiral shape along the tube axis direction, and the twist angle γ _{1 of the} recess with respect to the tube axis is 30 degrees or less. To do.

According to such a configuration, the outer tube uneven portion, by being formed with a predetermined twist angle gamma ₁ spirally, water or refrigerant flowing in the outer of the outer tube is further stirred, leak detection tube The heat transfer performance is further improved. In addition, by making the outer tube uneven portion spiral, the pressure loss of water or refrigerant flowing outside the outer tube can be reduced.

  The leak detection tube according to claim 4 includes an inner tube and an outer tube fitted to the outside of the inner tube, and leaks water or refrigerant flowing inside the inner tube or outside the outer tube. A leak detection pipe for detecting through a leak path formed between an inner pipe and the outer pipe, wherein the inner pipe is formed along the pipe circumferential direction in at least a part of its entire length. An inner tube concavo-convex portion comprising a large number of concave portions and convex portions, wherein the concave portion and the convex portion of the inner pipe concavo-convex portion extend along a tube axis direction of the inner tube, and the inner tube is the inner tube The outer surface of the top of the convex portion of the concavo-convex portion is in contact with the outer tube, and the leakage path is formed by the inner peripheral surface of the outer tube and the outer surface of the concave portion of the inner tube concavo-convex portion. And

  According to such a configuration, the inner tube constituting the leak detection tube is provided with the inner tube uneven portion, whereby water or refrigerant flowing inside the inner tube is agitated and the inner surface area of the inner tube is increased. To do. This greatly improves the heat transfer performance.

According to a fifth aspect of the present invention, in the leak detection tube, the inner tube uneven portion has a ratio (HS ₂ / OD ₂₎ between the recess depth HS ₂ of the recess and the maximum outer diameter OD ₂ of the inner tube in the cross section orthogonal to the tube axis. ) Is 0.02 to 0.1, and the number of the recesses is 4 to 32.

  If comprised in this way, since the shape of the uneven | corrugated | grooved part of an inner pipe is optimized, since the water or refrigerant | coolant which distribute | circulates the inner side of an inner pipe is further stirred, the heat-transfer performance of a leak detection pipe improves further. .

The leak detection tube according to claim 6 is characterized in that the inner tube uneven portion is formed in a spiral shape along the tube axis direction, and the twist angle γ _{2 of the} recess with respect to the tube axis is 30 degrees or less. To do.

With this configuration, the inner tube irregularities are spirally formed at a predetermined twist angle γ ₂ , so that the water or refrigerant flowing inside the inner tube is further agitated, and the leakage detection tube Heat transfer performance is further improved. Moreover, the pressure loss of the water or the refrigerant | coolant which distribute | circulates the inner side of an inner pipe | tube can be restrained small by making an inner pipe | tube uneven | corrugated part helical.

  The leak detection tube according to claim 7 includes an inner tube and an outer tube fitted outside the inner tube, and leaks water or refrigerant flowing inside the inner tube or outside the outer tube. A leak detection pipe for detecting through a leak path formed between an inner pipe and the outer pipe, wherein the outer pipe and the inner pipe are arranged in at least a partial region of the entire length in the pipe circumferential direction. A plurality of recesses and projections formed along the outer tube irregularities and inner tube irregularities, and the recesses and projections of the outer tube irregularities are in the axial direction of the outer tube. And the concave and convex portions of the inner tube uneven portion extend along the tube axis direction of the inner tube, and the leakage path includes an outer peripheral surface of the inner tube and an inner peripheral surface of the outer tube. It is formed by these.

  If comprised in this way, the outer pipe | tube which comprises a leak detection pipe | tube is provided with an outer pipe | tube uneven | corrugated | grooved part, and while the water or refrigerant | coolant which distribute | circulates the outer side of an outer pipe | tube is further stirred, the pipe | tube outer surface area of an outer pipe | tube is To increase. In addition, by providing the inner tube uneven portion that fits with the outer tube uneven portion, the water or refrigerant flowing inside the inner tube is further stirred, and the inner surface area of the inner tube is increased. This further improves the heat transfer performance of the leak detection tube.

The leak detection tube according to claim 8 is characterized in that the outer tube uneven portion has a ratio (HS ₁ / OD ₁₎ between the recess depth HS ₁ of the recess and the maximum outer diameter OD ₁ of the outer tube in a cross section orthogonal to the tube axis. ) Is 0.02 to 0.1, the number of the recesses is 4 to 32, and the inner tube uneven portion has a recess depth HS ₂ of the recess and the maximum outer diameter of the inner tube in the cross section perpendicular to the tube axis. the ratio of the _{OD 2 (HS 2 / OD 2} ) is 0.02 to 0.1, the number of said recesses, characterized in that it is 4 to 32.

  With this configuration, the shape of the outer tube uneven portion and the inner tube uneven portion is optimized, so that the water or the refrigerant flowing through the outer tube and the inner tube is further stirred. The heat transfer performance of the leak detection tube is further improved.

The leak detection tube according to claim 9, wherein the outer tube uneven portion and the inner tube uneven portion are each formed in a spiral shape along the tube axis direction, and the outer tube uneven portion has the concave portion with respect to the tube axis. The twist angle γ ₁ of the inner tube is 30 degrees or less, and the twist angle γ _{2 of the} recess with respect to the tube axis is 30 degrees or less in the inner tube uneven portion.

If comprised in this way, the outer pipe | tube uneven | corrugated | grooved part and the inner pipe | tube uneven | corrugated | grooved part are helically formed with predetermined torsion angle γ ₁ and torsion angle γ ₂ , Since the water or refrigerant flowing inside the inner pipe is further stirred, the heat transfer performance of the leak detection pipe is further improved. In addition, by forming the outer tube concavo-convex portion and the inner tube concavo-convex portion in a spiral shape, it is possible to suppress the pressure loss of water or refrigerant flowing through the outer side of the outer tube and the inner side of the inner tube.

  The leak detection tube according to claim 10 is characterized in that a groove is formed in the tube axis direction on the inner peripheral surface of the outer tube.

  According to such a structure, the said groove | channel becomes a leak path formed between an inner pipe and an outer pipe, and the water or the refrigerant | coolant which leaked from the corrosion hole reaches | attains the end of a leak detection pipe rapidly. Therefore, it becomes easy to detect leakage of water or refrigerant.

  The leak detection tube according to claim 11 is characterized in that a rib is formed in the tube axis direction on the outer peripheral surface of the inner tube.

  According to such a configuration, a space is formed between the inner tube and the outer tube by the rib, and this space becomes a leakage path, so that water or refrigerant leaked from the corrosion hole can be quickly discharged from the end of the leakage detection tube. To reach. Therefore, it becomes easy to detect leakage of water or refrigerant.

  The leak detection tube according to claim 12 is characterized in that one or both of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube is a rough surface.

  According to such a configuration, a space derived from the surface roughness is formed between the inner tube and the outer tube, and this space becomes a leakage path, so that water or refrigerant leaked from the corrosion hole is quickly detected. Reach the end of the tube. Therefore, it becomes easy to detect leakage of water or refrigerant.

  The heat exchanger according to claim 13 is a heat exchanger that uses water and a refrigerant as a heat medium, and performs heat exchange between these heat mediums, wherein one of the water and the refrigerant is circulated inside the heat exchanger. And the other flow path of water or refrigerant containing the leak detection pipe.

  According to such a configuration, as described above, since the leak detection tube excellent in heat transfer performance is used, a heat exchanger excellent in heat exchange performance between water and the refrigerant is realized.

  A heat exchanger according to a fourteenth aspect is characterized in that one of water or refrigerant flowing through the leak detection tube and the other of water or refrigerant flowing through the flow path are opposed to each other.

  According to such a structure, the area | region where the temperature difference of water and a refrigerant | coolant is large in a pipe-axis direction can be produced over a long range. Therefore, the heat exchange performance is further improved.

  The heat exchanger according to a fifteenth aspect is characterized in that the flow path is formed by a tubular large-diameter pipe that encloses the leak detection pipe.

  According to such a configuration, the heat transfer coefficient between the water and the refrigerant is improved by configuring the flow path containing the leak detection tube with a tubular large-diameter tube. Therefore, the heat exchange performance is further improved.

  The heat exchanger according to a sixteenth aspect is characterized in that the large-diameter pipe includes a processed portion that is corrugated along the pipe axis direction in at least a partial region of the entire length thereof.

  According to such a structure, the water or the whole refrigerant | coolant which distribute | circulates the inside of a large diameter pipe is further stirred by the process part with which the large diameter pipe was equipped. Therefore, the heat exchange performance is further improved.

  The heat exchanger according to claim 17 is characterized in that a groove is formed on an inner peripheral surface of the large-diameter pipe.

  According to such a configuration, the water or refrigerant flowing in the large-diameter pipe is further agitated by the grooves formed on the inner peripheral surface of the large-diameter pipe. Therefore, the heat exchange performance is further improved.

The heat exchanger according to claim 18 is characterized in that the refrigerant is carbon dioxide.
The heat exchanger according to the present invention can achieve good heat exchange performance even when carbon dioxide, which is a natural refrigerant, is used.

  According to the leak detection tube according to claim 1, by providing the outer tube with the outer tube uneven portion, it is possible to increase the heat transfer area and to stir the water or refrigerant flowing outside the outer tube. Heat transfer performance can be improved. According to the leak detection pipe | tube which concerns on Claim 2, 3, since the shape of an outer pipe | tube uneven | corrugated | grooved part is optimized, while the heat-transfer performance improves further, the pressure loss of water or a refrigerant | coolant is suppressed.

  According to the leak detection pipe of the fourth aspect, by providing the inner pipe with the concave and convex portions on the inner pipe, the heat transfer area can be increased and the water or the refrigerant circulating inside the inner pipe can be stirred. Heat transfer performance can be improved. According to the leak detection pipe | tube concerning the 5th, 6th, since the shape of an inner pipe | tube uneven | corrugated | grooved part is optimized, while heat-transfer performance improves further, the pressure loss of water or a refrigerant | coolant is suppressed.

  According to the leak detection tube according to claim 7, by providing the outer tube concavo-convex portion and the inner tube concavo-convex portion, the heat transfer area is increased and the water flowing outside the outer tube and inside the inner tube or Since the refrigerant can be stirred, the heat transfer performance can be improved. According to the leak detection pipes according to claims 8 and 9, since the shapes of the outer tube uneven portion and the inner tube uneven portion are optimized, the heat transfer performance is further improved and the pressure loss of water or refrigerant is suppressed. It is done.

  According to the leak detection pipe | tube which concerns on Claim 10, since the groove | channel is provided in the internal peripheral surface of an outer pipe | tube, the leaked water or refrigerant | coolant can be detected rapidly. According to the leak detection pipe of the eleventh aspect, since the outer peripheral surface of the inner pipe is provided with the rib, the leaked water or refrigerant can be detected quickly. According to the leak detection tube of the twelfth aspect, since at least one of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube is a rough surface, the leaked water or refrigerant can be detected quickly.

  According to the heat exchanger according to the thirteenth aspect, since the leak detection tube with high heat transfer performance is used, a heat exchanger with high heat exchange performance can be obtained. According to the heat exchanger according to the fourteenth aspect, since the flow directions of water and the refrigerant are reversed, the heat exchange performance is further improved. According to the leak detection pipe of the fifteenth aspect, since the flow path is formed of a large diameter pipe, the heat exchange performance is further improved. According to the leak detection pipe of the sixteenth aspect, since the large diameter pipe is provided with the processed portion that is corrugated, the heat exchange performance is further improved. According to the leak detection pipe of the seventeenth aspect, since the groove is formed in the pipe axial direction on the inner peripheral surface of the large diameter pipe, the heat exchange performance is further improved. According to the heat exchanger according to claim 18, good heat exchange performance is realized even when carbon dioxide is used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the leak detection tube according to the present invention will be described. Here, FIG. 1 is a cross-sectional view orthogonal to the tube axis showing the configuration of the leak detection tube, FIGS. 2 and 3 are front views along the tube axis direction of the leak detection tube, and FIG. 4 is another embodiment of the leak detection tube. FIG. 5 is a front view along the tube axis direction of the inner tube of FIG. 4, and FIG. 6 is a tube axis orthogonal cross-sectional view showing the configuration of another embodiment of the leak detection tube.

<< Leakage Detector Tube: First Embodiment >>
As shown in FIG. 1, the leak detection tube 1A includes an inner tube 7B and an outer tube 2A that fits outside the inner tube 7B, and water or a refrigerant (hereinafter referred to as a heat medium) inside the inner tube 7B. Is used for a heat exchanger (the structure of the heat exchanger will be described in detail later) for circulating the other heat medium outside the outer tube 2A and exchanging heat between these heat mediums. In this case, the leakage of the heat medium is detected through the leakage path 6 formed between the inner tube 7B and the outer tube 2A. Each configuration will be described below.

[Outer tube]
The outer tube 2A includes an outer tube uneven portion 3 including a plurality of concave portions 4 formed along the pipe circumferential direction and convex portions 5 formed between the concave portions 4 in at least a part of the entire length thereof. The concave portion 4 and the convex portion 5 of the outer tube uneven portion 3 extend along the tube axis direction of the outer tube 2A. In the outer tube 2A, the inner surface of the bottom of the recess 4 of the outer tube uneven portion 3 is in contact with the inner tube 7B. In other words, the minimum inner diameter portion of the outer tube 2A is in contact with the inner tube 7B. A leakage path 6 is formed by the outer peripheral surface of the inner tube 7 </ b> B and the inner surface of the convex portion 5 of the outer tube uneven portion 3.

The outer diameter of the outer tube 2A is specified by the maximum outer diameter OD ₁ (the outer diameter of the circumscribed circle circumscribed at the apex of the convex portion 5 of the outer tube uneven portion 3), and the flow path (outside It is set so that a necessary amount of the heat medium flows through the outside of the pipe 2A (see FIG. 9). The inner diameter of the outer tube 2A is specified by the minimum inner diameter (the outer diameter of the inscribed circle inscribed at the bottom of the concave portion 4 of the outer tube uneven portion 3), and is determined relative to the outer diameter of the inner tube 7B. When the outer diameter of the inner tube 7B is determined in advance, the minimum diameter of the outer tube 2A is set to a dimension that can be fitted to the outer surface of the inner tube 7B. The thickness of the outer tube 2A is preferably a thickness that takes into account the corrosion allowance due to the heat medium that flows outside the outer tube 2A, and is fitted to the outer peripheral surface of the inner tube 7B by the outer tube uneven portion 3. Therefore, it is preferable to set the thickness to allow easy processing. For example, the maximum outer diameter OD1 of the outer tube 2A is preferably 3 to 20 mm, the wall thickness is 0.2 to 2.5 mm, and the length is ₁ to 30 m.

  The material of the outer tube 2A is not particularly limited as long as the outer tube uneven portion 3 can be formed as described above, and the strength, corrosion resistance, brazing property, bending workability required for use in a heat exchanger. For example, oxygen-free copper of alloy number C1101 and phosphorus-deoxidized copper of alloy numbers C1201 and C1220 defined in JISH3300 widely used as heat exchangers are preferable. Moreover, it is not necessary to limit only to the said material, and when especially heat conductivity and a pressure | voltage resistant strength are required, the copper or copper alloy prescribed | regulated to JISH3300, for example, Cu, Fe, P, Ni, Co, Mn It is also possible to use a copper alloy not defined in JISH3300 containing one or more selected from elements such as Sn, Si, Mg, Ag, Al, etc. in a total of several percent or less. Further, when particularly corrosion resistance and pressure strength are required, Cu—Ni alloys such as alloy numbers C7060, C7100, and C7150 defined in JISH3300, Ti or Ti alloys, stainless steel, and the like can be used. When weight reduction is required, it is possible to select one having predetermined characteristics from aluminum and aluminum alloys in consideration of characteristics such as corrosion resistance, strength, and workability.

  Since the heat exchanger is often operated by increasing the internal pressure of the inner tube 7B provided inside the outer tube 2A, the outer tube 2A often increases the wall thickness relative to the tube outer diameter. The thickness of the outer tube 2A may be determined from the pressure resistance calculated based on the operating pressure of the heat exchanger. In general, the outer pipe 2A is often a seamless pipe produced by rolling and drawing an extruded raw pipe, but a welded pipe may be used as long as the pressure strength satisfies a required value.

The outer tube concavo-convex portion 3 provided along the circumferential direction of the outer tube 2A has an action of stirring the heat medium flowing outside the outer tube 2A and an action of increasing the outer surface area of the outer tube 2A. Have. Thereby, the heat transfer rate of the heat medium which distribute | circulates the outer side of 2 A of outer tubes improves. The outer tube uneven portion 3 has a ratio (HS ₁ / OC ₁ ) between the recess depth HS ₁ of the recess 4 and the maximum outer diameter OD ₁ of the outer tube 2A in the tube axis orthogonal cross section of 0.02 to 0.1. The number of recesses 4 is preferably 4 to 32.

When the ratio (HS ₁ / OD ₁ ) is less than 0.02, the stirring effect of the heat medium flowing outside the outer tube 2A is small, and the surface area outside the leakage detection tube 1A (the surface area outside the tube 2A) Since the increase is small, it is difficult to expect an improvement in the heat transfer coefficient of the heat medium. On the other hand, when the ratio (HS ₁ / OD ₁ ) exceeds 0.1, the recess depth HS ₁ becomes too large, and the manufacture of the outer tube 2A tends to be difficult. Further, the pressure loss of the heat medium flowing outside the outer tube 2A tends to increase.

  If the number of the recesses 4 is less than 4, the increase in the outer surface area of the leak detection tube 1A (the outer surface area of the outer tube 2A) is small, and it is difficult to expect an improvement in the heat transfer coefficient of the heat medium. Moreover, when the number of the recessed parts 4 exceeds 32, manufacture of 2 A of outer tubes will become difficult easily.

In FIG. 2, the outer tube uneven portion 3 is formed in parallel along the tube axis direction, and the torsion angle γ ₁ (see FIG. 3) of the recess 4 with respect to the tube axis is 0 degree, but as shown in FIG. It is preferably formed in a spiral shape along the tube axis direction, and the twist angle γ _{1 of the} recess 4 with respect to the tube axis (the angle formed by the recess 4 and the tube axis of the outer tube 2A) is preferably 30 degrees or less. By forming the outer tube uneven portion 3 in a spiral shape, a swirling flow is given to the heat medium flowing outside the outer tube 2A, and the heat transfer coefficient of the heat medium is further improved while suppressing pressure loss to a small level. Can do. When the twist angle γ ₁ exceeds 30 degrees, it is difficult to manufacture the outer tube 2A. Further, the pressure loss of the heat medium flowing outside the outer tube 2A tends to increase.

  Further, by forming the outer tube uneven portion 3 in a spiral shape, the leakage path 6 (see FIG. 1) formed by the outer peripheral surface of the inner tube 7B and the convex portion 5 of the outer tube uneven portion 3 becomes a spiral shape. The leakage of the heat medium can be detected quickly. Therefore, compared to the leak detection tube 1C according to the third embodiment described later (see FIG. 6), the formation of the groove 12A on the inner peripheral surface of the outer tube 2A, the formation of the rib on the outer peripheral surface of the inner tube 7A, There is an advantage that the roughening of one or both of the inner peripheral surface of the outer tube 2A and the outer peripheral surface of the inner tube 7A can be omitted.

[Inner pipe]
As shown in FIG. 1, a smooth tube is used as the inner tube 7B in the leak detection tube 1A. The inner diameter of the inner tube 7B is set to a dimension that allows the required amount of heat medium to flow through the inner tube 7B. Further, the thickness of the inner tube 7B is determined in consideration of the strength of the selected material (material) so as to withstand the pressure of the heat medium flowing through the inner tube 7B. The material of the inner tube 7B is not particularly limited, and the same material as that of the outer tube 2A may be used, or a different material may be used. For example, the outer diameter is preferably 1.5 to 18 mm, the thickness is 0.2 to 2 mm, and the length is preferably 1 to 30 m. As the inner pipe 7B, a seamless pipe is often used in the same manner as the outer pipe 2A, but a welded pipe may be used as long as the required value of the pressure resistance is satisfied. The details of the heat medium circulated in the inner pipe 7B will be described later when the heat exchanger 20A (see FIG. 9) provided with the leak detection pipe 1A is described later.

  The inner tube 7B preferably projects at least one tube end at both ends thereof in the tube axis direction from the tube end of the outer tube 2A (see FIG. 10). With such a configuration, when the heat exchanger 20A is manufactured, the leakage detection tube 1A can be easily connected to other components. The protruding length of the inner tube 7B depends on the size of the heat exchanger 20A to be manufactured, but can be set to, for example, 10 to 100 mm.

  Although leak detection pipe 1A is not illustrated, a groove may be formed along the pipe axis direction on the inner surface of inner pipe 7B. By forming the groove, the heat medium flowing inside the inner tube 7B is agitated, and the heat transfer performance of the leak detection tube 1A is improved. The depth of the groove is preferably 0.01 to 0.2 mm. If the depth of the groove is less than 0.01 mm, the stirring effect of the heat medium flowing inside the inner tube 7B is small, and it is difficult to expect improvement in heat transfer performance. If the depth of the groove exceeds 0.2 mm, the formability of the groove is liable to deteriorate. In addition, the twist angle of the groove in the tube axis parallel section is 0 ° (parallel groove formed in parallel to the tube axis direction) to 45 °, and the peak angle of the fin formed between the grooves in the tube axis orthogonal section is It is preferable that the number of grooves is 10 to 45 ° and 30 to 70. In addition, about the formation method of a groove | channel, it is the same as that of the groove | channel 12A formed in the leak detection pipe | tube 1C which concerns on 3rd Embodiment mentioned later.

Next, another embodiment of the leak detection tube according to the present invention will be described.
<< Leakage detection tube: Second embodiment >>
As shown in FIG. 4, the leak detection tube 1B includes an inner tube 7A and an outer tube 2B that fits outside the inner tube 7A, and circulates one of the heat medium inside the inner tube 7A. 2B is used for a heat exchanger in which the other of the heat medium is circulated to the outside of 2B and heat exchange is performed between these heat mediums. At that time, leakage of the heat medium is caused between the inner pipe 7A and the outer pipe 2B. It detects through the leak path 11 formed. Each configuration will be described below.

[Outer tube]
The outer tube 2B uses a smooth tube in the leak detection tube 1B. Except for using a smooth tube as the outer tube 2B, the characteristics required for the outer tube 2B are the same as those of the outer tube 2A of the above-described leak detection tube 1A.

[Inner pipe]
The inner tube 7A is provided with an inner tube uneven portion 8 composed of a large number of recessed portions 9 formed along the tube circumferential direction and protruding portions 10 formed between the recessed portions 9 in at least a partial region of the entire length thereof. The concave portion 9 and the convex portion 10 of the inner tube uneven portion 8 extend along the tube axis direction of the inner tube 7A. In the inner tube 7A, the outer surface of the top portion of the convex portion 10 of the inner tube uneven portion 8 is in contact with the outer tube 2B. In other words, at the maximum outer diameter OD ₂ of the portion of the inner tube 7A, it is in contact with the outer tube 2B skilled. A leak path 11 is formed by the inner peripheral surface of the outer tube 2 </ b> B and the outer surface of the recess 9 of the inner tube uneven portion 8.

The outer diameter of the inner tube 7A is specified by the maximum outer diameter OD ₂ (the outer diameter of the circumscribed circle circumscribed at the apex of the convex portion 10 of the inner tube uneven portion 8, in other words, the inner diameter of the outer tube 2B). Is specified by the minimum inner diameter (the outer diameter of the inscribed circle inscribed at the bottom of the concave portion 9 of the inner tube uneven portion 8).

The inner tube uneven portion 8 provided along the pipe circumferential direction of the inner tube 7A has an action of stirring the heat medium flowing inside the inner pipe 7A and an action of increasing the inner surface area of the inner pipe 7A. . Thereby, the heat transfer rate of the heat medium which distribute | circulates the inner side of 7 A of inner pipes improves. The inner tube concavo-convex portion 8 has a ratio (HS ₂ / OC ₂ ) between the recess depth HS ₂ of the recess 9 and the maximum outer diameter OD ₂ of the inner tube 7 A in the tube axis orthogonal cross section of 0.02 to 0.1. The number of recesses 4 is preferably 4 to 32.

When the ratio (HS ₂ / OD ₂ ) is less than 0.02, the stirring effect of the heat medium flowing inside the inner tube 7A is small, and the surface area of the leak detection tube 1B (the surface area of the inner tube 7A) increases. Therefore, it is difficult to expect an improvement in the heat transfer coefficient of the heat medium. On the other hand, if the ratio (HS ₂ / OD ₂ ) exceeds 0.1, the recess depth HS ₂ becomes too large, and the manufacture of the inner tube 7A tends to be difficult. Further, the pressure loss of the heat medium that circulates inside the inner pipe 7A tends to increase.

  If the number of the recesses 9 is less than 4, the increase in the surface area of the leak detection tube 1B (the surface area of the inner tube 7A) is small, so it is difficult to expect an improvement in the heat transfer coefficient of the heat medium. Moreover, when the number of the recessed parts 9 exceeds 32, manufacture of the inner tube | pipe 7A will become difficult easily.

The inner tube uneven portion 8 is formed in parallel along the tube axis direction, and the torsion angle γ ₂ (see FIG. 5) of the recess 9 with respect to the tube axis is 0 degree. However, as shown in FIG. The twist angle γ _{2 of the} recess 9 with respect to the tube axis (angle formed by the recess 9 and the tube axis of the inner tube 7A) is preferably 30 degrees or less. By forming the inner tube uneven portion 8 in a spiral shape, a swirling flow is given to the heat medium flowing inside the inner tube 7A, and the heat transfer coefficient of the heat medium is further improved while suppressing pressure loss to a small level. Can do. When the twist angle γ ₂ exceeds 30 degrees, it is difficult to manufacture the inner tube 7A. Further, the pressure loss of the heat medium that circulates inside the inner pipe 7A tends to increase.

  Further, by forming the inner tube uneven portion 8 in a spiral shape, the leakage path 11 (see FIG. 4) formed by the inner peripheral surface of the outer tube 2B and the recess 9 in the inner tube uneven portion 8 becomes a spiral shape. The leakage of the heat medium can be detected quickly. Therefore, compared to the leak detection tube 1C according to the third embodiment described later (see FIG. 6), the formation of the groove 12A on the inner peripheral surface of the outer tube 2A, the formation of the rib on the outer peripheral surface of the inner tube 7A, There is an advantage that the roughening of one or both of the inner peripheral surface of the outer tube 2A and the outer peripheral surface of the inner tube 7A can be omitted.

Except for the maximum outer diameter OD ₂ , the minimum inner diameter, and the inner tube uneven portion 8, the characteristics required for the inner tube 7 A are the same as those of the inner tube 7 B of the leak detection tube 1 A described above. Is omitted.

<< Leakage Detector Tube: Third Embodiment >>
As shown in FIG. 6, the leak detection tube 1C includes an inner tube 7A and an outer tube 2A that fits outside the inner tube 7A. Each of the outer tube 2A and the inner tube 7A is at least part of its entire length. The region includes an outer tube uneven portion 3 and an inner tube uneven portion 8 which are formed of a large number of concave portions and convex portions formed along the pipe circumferential direction and are fitted to each other, and the concave portion 4 and the convex portion 5 of the outer tube uneven portion 3. Extends along the tube axis direction of the outer tube 2A, and the concave portion 9 and the convex portion 10 of the inner tube uneven portion 8 extend along the tube axis direction of the inner tube 7A.

  As with the leak detection tubes 1A and 1B described above, the leak detection tube 1C allows one of the heat medium to flow inside the inner tube 7A and allows the other heat medium to flow outside the outer tube 2A. It is used in a heat exchanger that performs heat exchange between media, and at that time, leakage of the heat medium is detected through a leakage path 12 formed between the inner tube 7A and the outer tube 2A. The leakage path 12 is formed by the outer peripheral surface of the inner tube 7A and the inner peripheral surface of the outer tube 2A, that is, by the fine unevenness of the fitting surface between the outer peripheral surface of the inner tube 7A and the inner peripheral surface of the outer tube 2A. Is formed.

The outer tube concavo-convex portion 3 and the inner tube concavo-convex portion 8 are fitted so that the concave portions 4, the concave portions 9, the convex portions 5, and the convex portions 10 overlap each other. In the leak detection tube 1C, the outer tube uneven portion 3 has a ratio (HS ₁ / OC ₁ ) between the recess depth HS ₁ of the recess 4 and the maximum outer diameter OD ₁ of the outer tube 2A in the cross section orthogonal to the tube axis. 0.02 to 0.1, the number of recesses 4 is 4 to 32, and the inner tube uneven portion 8 has a recess depth HS ₂ of the recess 9 and a maximum outer diameter OD ₂ of the inner tube 7A in the cross section perpendicular to the tube axis. (HS ₂ / OD ₂ ) is preferably 0.02 to 0.1, and the number of recesses 9 is preferably 4 to 32.

The outer tube uneven portion 3 and the inner tube uneven portion 8 are in the ratio (HS ₁ / OD ₁ , HS ₂ / OD ₂ ) and the number of the recessed portions, so that the outer tube 2A and the inner tube 7A are circulated. As the heat medium to be stirred is stirred, the outer surface area of the outer tube 2A and the inner surface area of the inner tube 7A increase. For this reason, the heat transfer coefficient of the heat medium is further improved. The reasons for limiting the numerical values of the ratio (HS ₁ / OD ₁ , HS ₂ / OD ₂ ) and the number of recesses are the outer tube 2A of the first embodiment (leakage detection tube 1A), and the second embodiment (leakage detection). This is the same as the inner tube 7A of the tube 1B).

The outer tube concavo-convex portion 3 and the inner tube concavo-convex portion 8 are each formed in a spiral shape along the tube axis direction, and the torsion angle γ ₁ of the recess 4 with respect to the tube axis in the outer tube concavo-convex portion 3 is 30 degrees or less, In the inner tube uneven portion 8, the twist angle γ ₂ of the recess 9 with respect to the tube axis is preferably 30 degrees or less. Thereby, a swirl flow is given to the heat medium flowing through the outer side of the outer pipe 2A and the inner side of the inner pipe 7A, and the heat transfer coefficient of the heat medium can be further improved while suppressing the pressure loss. In particular, when the refrigerant as the heat medium is carbon dioxide containing refrigeration oil, the heat transfer performance can be improved while suppressing an increase in pressure loss. The reasons for limiting the numerical values of the twist angles γ ₁ and γ ₂ are the same as those of the outer tube 2A of the first embodiment (leakage detection tube 1A) and the inner tube 7A of the second embodiment (leakage detection tube 1B). .

  Except that the outer tube 2A and the inner tube 7A are provided with the outer tube uneven portion 3 and the inner tube uneven portion 8, the characteristics required as the outer tube 2A and the inner tube 7A are the same as those of the leak detection tube 1A. Since it is the same as the pipe 2A and the inner pipe 7A of the leak detection pipe 1B, description thereof is omitted.

  The leak detection tube 1C is an outer tube 2A that secures a leak path 12 between the outer peripheral surface of the inner tube 7A and the inner peripheral surface of the outer tube 2A so that the detection of the leaked heat medium is not delayed. It is preferable to use an internally grooved tube having a spiral groove 12A formed in the tube axis direction on the inner peripheral surface thereof.

  The inner grooved tube used as the outer tube 2A is a method of rolling a groove by inserting a grooved plug inside a smooth tube and pressing a rolled body (rolling ball, rolling roll) rotating on the outer surface of the tube, or It can be manufactured by rolling grooves on the surface of the strip and welding the ends of the strip. The groove 12A may be provided so that leakage can be detected in any part of the outer tube 2A or the inner tube 7A and the heat transfer between the outer tube 2A and the inner tube 7A is not lowered. The depth of the groove is 0.01 to 0.2 mm, the twist angle of the groove 12A in the tube axis parallel section is 0 ° (parallel groove formed in parallel to the tube axis direction) to 45 °, the tube axis orthogonal section It is preferable that the crest angle of the fin formed between the groove 12A in the case is 10 to 45 °, and the number of grooves in the groove 12A is 30 to 70. Within these ranges, the leak detection tube 1C can be manufactured without causing a large cost increase.

  Although not shown, when the groove 12A is not formed on the inner peripheral surface of the outer tube 2A, the inner tube 7A preferably has a rib formed in the tube axis direction on the outer peripheral surface thereof. This rib forms a space between the outer tube 2A and the inner tube 7A in the same manner as the groove 12A formed on the inner peripheral surface of the outer tube 2A, and this space functions as a leakage path. The height of the rib in the cross section perpendicular to the tube axis is preferably 0.01 to 0.2 mm. When the height of the rib is less than 0.01 mm, the action as a leakage path of the space formed between the outer tube 2A and the inner tube 7A is small, while when the height exceeds 0.2 mm. There is a possibility that the moldability of the ribs may be deteriorated and the heat transfer performance may be deteriorated. The ribs may be parallel to the tube axis direction or may be formed in a spiral shape so as to form a predetermined angle.

  Further, although not shown, when the groove 12A is not formed on the inner peripheral surface of the outer tube 2A or the outer peripheral surface of the inner tube 7A is not formed with ribs, the inner peripheral surface of the outer tube 2A and the outer periphery of the inner tube 7A It is preferable that either one or both of the surfaces are roughened. Such a roughened surface forms a leakage path due to minute irregularities on the surface. The size of the leakage path formed in this way is larger than, for example, the gap formed on the fitting surface of the double tube structure in which a smooth tube that has not been roughened is fitted.

  The surface roughness of the roughening is preferably 4 μm or more, more preferably 6 μm or more in terms of the maximum cross-sectional height Rt measured in the tube axis direction. Further, when the surface roughness is measured by the arithmetic average roughness Ra, the arithmetic average roughness Ra is preferably 0.8 μm or more, and more preferably 1.2 μm or more. Note that the roughened surface can be formed by performing shot blasting, chemical polishing, chemical etching, or the like.

《Leak detector tube manufacturing method》
Next, a method for manufacturing the above-described leak detection tube will be described. Here, FIG. 7A is a front view schematically showing a method for manufacturing a leak detection tube according to the present invention, FIG. 7B is a plan view of a processing jig used for manufacturing, and FIG. 8A is a leak detection. The front view which shows another manufacturing method of a pipe | tube typically, (b) is sectional drawing along the roll axis | shaft of the roll for a process used for manufacture.

  As shown in FIGS. 7A and 7B, in manufacturing the leak detection tube 1A, first, the inner tube 7B is inserted inside the original tube 2 of the outer tube 2A. The original pipe 2 into which the inner pipe 7B is inserted is inserted inside the processing jig 30. The processing jig 30 includes a plurality of balls 31 or bars (not shown) having a spherical surface corresponding to the cross-sectional shape of the recess 4 (outer tube uneven portion 3). Next, the ball 31 or the rod is pressed against the outer peripheral surface of the original pipe 2 with a predetermined pressure, and at the same time, the original pipe 2 is moved in the pipe axis direction at a predetermined speed. As a result, the original tube 2 is processed into the outer tube 2A having the outer tube uneven portion 3, and at this time, the inner tube 7B is formed so that the tube axis of the inner tube 7B and the tube axis of the outer tube 2A substantially coincide with each other. The outer tube 2A and the inner tube 7B are fitted to each other at the bottom (inner surface) of the recess 4 in the outer tube uneven portion 3 and arranged at the center of the tube 2A. A leakage path 6 (see FIG. 1) is formed between the outer periphery of the tube 7B, and the leakage detection tube 1A is manufactured. Further, when the spiral outer tube uneven portion 3 is formed, the original tube 2 (outer tube 2A) is moved in the tube axis direction while rotating at a predetermined speed.

  For forming the outer tube uneven portion 3, a pair of processing rolls 32 and 32 shown in FIGS. 8A and 8B may be used instead of the processing jig 30 described above. The processing roll 32 includes a groove portion in the roll circumferential direction, and the groove portion includes a plurality of spherical protrusions 33 corresponding to the cross-sectional shape of the recess 4.

In manufacturing the leak detection tube 1 </ b> A using the processing roll 32, the original tube 2 of the outer tube 2 </ b> A into which the inner tube 7 </ b> B is inserted is inserted inside the groove portions of the pair of processing rolls 32 and 32. Next, by closing the pair of processing rolls 32 and 32 and rotating the processing rolls 32 and 32 at a predetermined speed, the original pipe 2 is moved in the tube axis direction. Thereby, the original tube 2 is processed into the outer tube 2A having the outer tube uneven portion 3, the outer tube 2A and the inner tube 7B are fitted, and the leak detection tube 1A in which the leak path 6 is formed is manufactured. When the spiral outer tube uneven portion 3 is formed, the original tube 2 (outer tube 2A) is rotated in conjunction with the rotation of the processing roll 32. Further, although not shown, as the processing roll 32, a projection roll 33 inclined at a predetermined angle along the groove is used.
In manufacturing the leak detection pipe 1A, an inner grooved pipe may be used as the inner pipe 7B.

  In the manufacture of the leak detection pipe 1B (see FIG. 4), although not shown, the inner pipe (original pipe) is changed to the inner pipe 7A as described above by using the processing jig 30 or the processing roll 32 described above. Processing (forms the inner tube uneven portion 8). The inner pipe 7A is inserted inside the outer pipe (original pipe), and the outer pipe (original pipe) is reduced in diameter by roll fitting or drawing fitting to obtain an outer pipe 2B. As a result, the inner tube 7A and the outer tube 2B are fitted to each other at the top (outer surface) of the convex portion 10 in the inner tube uneven portion 8, and the concave portion 9 (outer surface) of the inner tube uneven portion 8 and the inner peripheral surface of the outer tube 2B. The leakage path 11 is formed between the two and the leakage detection tube 1B is manufactured.

  In manufacturing the leak detection pipe 1C (see FIG. 6), although not shown, the inner pipe (original pipe) is inserted inside the outer pipe (original pipe), and the outer pipe (original pipe) is fitted by roll fitting or drawing fitting. ) Is reduced in diameter, and the inner pipe (original pipe) and the outer pipe (original pipe) are fitted into a double pipe. Next, the double pipe is processed as described above using the processing jig 30 or the processing roll 32 described above. As a result, the outer tube uneven portion 3 is formed in the outer tube (original tube), and at the same time, the inner tube uneven portion 8 is formed in the inner tube (original tube), and the outer tube 2A (outer tube uneven portion 3) and the inner tube A leak detection tube 1C in which the tubes 7A (inner tube uneven portions 8) are fitted is manufactured.

Further, the recess depths HS ₁ and HS ₂ of the outer tube uneven portion 3 and the inner tube uneven portion 8 are substantially the same, and the torsion angles γ ₁ and γ ₂ when they are formed in a spiral shape are also substantially the same. (HS ₁ = HS ₂ , γ ₁ = γ ₂ ). The leak path 12 is formed at the time of roll fitting or drawing fitting, and even if the outer tube uneven portion 3 and the inner tube uneven portion 8 are formed, the leak path 12 between the outer tube 2A and the inner tube 7A is Maintained. In such a manufacturing method of the leak detection pipe 1C, an inner grooved pipe may be used as the outer pipe (original pipe).

  In addition, as a method of forming the outer tube uneven portion 3 and the inner tube uneven portion 8 described above, if the outer tube uneven portion 3 and the inner tube uneven portion 8 having the shapes shown in FIGS. 1, 4, and 6 can be formed, FIG. It is not limited to the method using the processing jig 30 shown to (a), (b) and the processing roll 32 shown to Fig.8 (a), (b).

Next, a heat exchanger using the above-described leak detection tube will be described with reference to the drawings.
<< Heat Exchanger: First Embodiment >>
9 is a cross-sectional view orthogonal to the tube axis showing the configuration of the heat exchanger, FIG. 10A is a perspective view showing the configuration of the tube end portion of the heat exchanger according to the embodiment of the present invention, and FIG. The perspective view showing the schematic structure of the exchanger, FIG. 11 is sectional drawing along the pipe-axis direction of the heat exchanger which concerns on another embodiment.

  The heat exchanger uses water or a refrigerant as a heat medium, and performs heat exchange between these heat mediums, and includes the leak detection pipe that circulates either water or the refrigerant inside and the leak detection pipe. And the other flow path of water or refrigerant. Moreover, it is preferable that the other flow path of water or a refrigerant | coolant is comprised by the tubular large diameter tube 13 (refer FIG. 9).

  Hereinafter, a heat exchanger using the leak detection tube 1A shown in FIG. 1 as a leak detection tube will be described as an example. As shown in FIGS. 9 and 10A, the heat exchanger 20 </ b> A has a double-pipe structure in which the leak detection pipe 1 </ b> A is disposed inside the large-diameter pipe 13. And the cap 15 for isolating the flow path of water and a refrigerant | coolant is provided in the pipe end part of 20 A of heat exchangers. The leak detection pipe 1 </ b> A passes through the cap 15, the large diameter pipe 13 is opened in the cap 15, and water or refrigerant is supplied into the large diameter pipe 13 from the opening provided in the cap 15.

  In at least one tube end of both ends of the leak detection tube 1A, it is preferable that the tube end of the inner tube 7B protrudes from the tube end of the outer tube 2A. This facilitates joining of the pipe end portion of the leak detection pipe 1A and a component (for example, a U vent pipe or the like) that supplies water or a refrigerant into the leak detection pipe 1A (inner pipe 7B).

  As shown in FIG. 10A, in the heat exchanger 20A, it is preferable that the direction of flowing water and the direction of flowing refrigerant are reversed so that the water and the refrigerant flow oppositely. Thereby, since the area | region where the temperature difference of water and a refrigerant | coolant is large in a pipe axis direction can be created over a long range, heat exchange performance can be improved.

[Leak detection tube]
Water or refrigerant is circulated in the leak detection pipe 1A. As the refrigerant, natural refrigerant such as carbon dioxide, alternative chlorofluorocarbon, or the like is used, and when the heat exchanger 20A is used for a water heater, it is preferable to use carbon dioxide from the environmental viewpoint, and carbon dioxide is supercritical. It is more preferable to use in a state from the viewpoint of thermal efficiency. The supercritical state is a state in which the boundary between the gas phase and the liquid phase has disappeared, and the heat transfer coefficient is more than twice that of the gas phase, despite the low density and viscosity that are close to the gas phase. A state showing a high value.

  The outer tube uneven portion 3 (see FIGS. 1 to 3) provided in the leak detection tube 1A is a local heat of carbon dioxide when carbon dioxide is used as a refrigerant in the actual operation of the heat exchanger 20A. It is preferable to form it in a region that satisfies an allowable temperature range (20 to 80 ° C.) in which the transmission rate is maximized.

  In the case where carbon dioxide is used as the heat medium, the carbon dioxide itself does not have a lubricating action, so that the compressor of the heat exchange system may be worn. Therefore, it is preferable to contain 0.1 to 6.0% by mass of refrigerating machine oil in carbon dioxide. For the refrigerating machine oil, polyalkylene glycol (PAG) or the like is generally used. When the content of the refrigerating machine oil is less than 0.1% by mass, the lubrication effect is low and the compressor of the heat exchange system is easily worn. On the other hand, if the refrigerating machine oil is contained in an amount exceeding 6.0 mass%, the heat transfer coefficient of the entire refrigerant tends to be lowered.

  When using alternative chlorofluorocarbon as the refrigerant, it is preferable to use a hydrofluorocarbon (HFC) refrigerant in consideration of the performance efficiency (COP) of the heat exchanger 20A. A typical HFC refrigerant is R410A which is a non-azeotropic refrigerant mixture in which R32 and R125 are mixed. It is preferable to use the HFC refrigerant in an almost critical state.

  The heat exchanger 20A has a structure in which one leak detection tube 1A is arranged in the large-diameter pipe 13, but may have a configuration in which a plurality of leak detection tubes 1A are arranged in the large-diameter pipe 13. . In the case where a plurality of leak detection pipes 1A are provided, it is preferable that the flow path of water or refrigerant in the large diameter pipe 13 is equally divided from the viewpoint of heat transfer and pressure loss.

  Since the details of the structure of the leak detection tube 1A itself have already been described, description thereof is omitted here. Further, the heat exchanger using the leak detection tubes 1B and 1C shown in FIGS. 4 and 6 instead of the leak detection tube 1A is the same as the heat exchanger 20A described above. Furthermore, in the heat exchanger using the leak detection tubes 1B and 1C, it is preferable that the inner tube uneven portion 8 is not formed at the tube ends of the leak detection tubes 1B and 1C (inner tube 7A). This facilitates joining between the end portions of the leak detection tubes 1B and 1C and components (for example, a U vent tube) for supplying water or refrigerant into the leak detection tubes 1B and 1C (inner tube 7A). .

[Large diameter pipe]
The large-diameter pipe 13 forms a flow path of water or refrigerant between the leak detection pipe 1A. The inner diameter of the large-diameter pipe 13 is larger than the outer diameter of the leak detection pipe 1A, and may be large enough to allow water or a refrigerant to flow through the flow path. As long as it has. The dimensions of the large-diameter pipe 13 are determined in consideration of the relationship with the dimensions of the leak detection pipe 1A, the dimensions of the water heater in which the heat exchanger 20A is incorporated, the heat capacity, and the workability. From the viewpoint of heat exchange performance and pressure loss of the heat exchanger 20A, the cross-sectional area of the leak detection tube 1A in the cross section orthogonal to the tube axis (the number of the leak detection tubes 1A × the leak detection tube 1A in the cross section orthogonal to the tube axis of the large diameter tube 13) The ratio of the cross-sectional area) to the cross-sectional area of the flow path between the large-diameter pipe 13 and the leak detection pipe 1A (outer flow path area / leakage detection pipe cross-sectional area) satisfies the range of 2 to 10. It is more preferable to set. As an example, the large-diameter tube 13 preferably has an inner diameter of φ8 to 30 mm, a wall thickness of 0.2 to 2.5 mm, and a length of 1 to 30 m.

  As shown in FIG. 10B, the heat exchanger 20A has a large-diameter tube 13 wound in a spiral shape so that a cross-sectional shape orthogonal to the winding axis Y is circular or oval. By having such a structure, it is possible to secure a wide heat transfer area while downsizing the heat exchanger 20A. In addition, since there is no portion bent at a steep angle in the winding portion, each pressure loss of water and refrigerant can be reduced. Further, the large-diameter tube 13 may be wound in a spiral shape.

  The minimum inner diameter ID of the winding portion of the large-diameter pipe 13 depends on the outer diameter, thickness, mechanical properties (tensile strength, proof stress, spring limit value, etc.) of the large-diameter pipe 13 and the leak detection pipe 1A. However, for example, when the outer diameter of the large-diameter pipe 13 is a constant “a”, the minimum inner diameter ID of the winding portion can be reduced to about six times “a”. Further, in order to reduce the height H of the winding portion, the single winding structure is shown in FIG. 10B, but a double winding structure is also preferable. In the winding part of the large-diameter pipe 13, the large-diameter pipes 13 may be in contact with each other or may be separated by a certain gap. From the point of downsizing of the heat exchanger 20A, it is preferable to bring the large diameter tubes 13 into contact with each other.

  The material of the large diameter tube 13 is not particularly limited, and a material having the strength, corrosion resistance, brazing property, and bending workability necessary for the heat exchanger 20A may be used. For example, the outer tube 2A of the leak detection tube 1A And it can select from the above-mentioned material suitably as what is used for the inner tube | pipe 7B. The large-diameter pipe 13 may be a seamless pipe manufactured by rolling and drawing an extruded element pipe, or a welded pipe manufactured by welding end faces in the width direction of a plate having a predetermined width. In heat exchangers, oxygen-free copper with alloy number C1101 and phosphorus-deoxidized copper with alloy numbers C1201 and C1220 specified in JISH3300 are widely used.

  As the large diameter tube 13, a smooth tube having a smooth tube inner surface is often used, and the heat exchanger 20A also uses a smooth tube as shown in FIG. Alternatively, an internally grooved tube having a groove formed on the inner peripheral surface may be used. By using such an internally grooved tube, the water or refrigerant flowing in the large-diameter tube 13 is agitated and a swirling flow is given, so that the heat transfer performance of the water or the refrigerant can be improved.

Next, another embodiment of the heat exchanger according to the present invention will be described.
<< Heat Exchanger: Second Embodiment >>
As shown in FIG. 11, the heat exchanger 20B has a double-pipe structure in which the leak detection pipe 1A is disposed inside the large diameter pipe 13A.

[Leak detection tube]
Since the leak detection pipe 1A has already been described with reference to FIGS. 1 to 3, the description thereof is omitted here.

[Large diameter pipe]
The large-diameter pipe 13A includes a processed portion 14 that is corrugated along the pipe axis direction in at least a partial region of the entire length thereof. With such a configuration, the water or the refrigerant flowing in the large-diameter pipe 13A is agitated by the processing unit 14, and the flow length of the water or the refrigerant is substantially increased. Can be further improved.

  The processed portion 14 has a ratio (HC / DC) between the groove depth HC and the maximum outer diameter (the tube outer diameter of the unprocessed portion that has not been corrugated) DC in the cross section perpendicular to the tube axis of the large diameter tube 13A. It is preferably 0.02 or more (HC / DC ≧ 0.02). Thereby, even when the difference between the outer diameter of the leak detection pipe 1A and the inner diameter of the large-diameter pipe 13A is large, the water or the refrigerant can be sufficiently stirred to improve the heat transfer performance of the water or the refrigerant.

In addition, with respect to the twist angle γ ₃ when the processed portion 14 is formed in a spiral shape, the water or the refrigerant is sufficiently stirred to improve the heat transfer coefficient of the water or the refrigerant, so that it is 40 degrees or more (γ ₃ ≧ 40 °), and the number of strips formed in the tube axis direction of the processed portion 14 may be one or more. In the present invention, the corrugating process includes the twist angle γ ₃ = 90 degrees, that is, the formation of the non-spiral processed part 14.

  Except for the provision of the processed portion 14 described above, the characteristics required for the large-diameter pipe 13A are the same as those of the large-diameter pipe 13 of the heat exchanger 20A of the first embodiment. To do. Although not shown in the drawing, the inner diameter grooved tube having a groove formed on the inner peripheral surface may be used as the large diameter tube 13A, although not shown.

  EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to a following example.

Example 1
The outer tube composing the leak detection tube is made of phosphorous deoxidized copper, the outer diameter is φ6mm, the inner diameter is φ4.8mm smooth tube (thickness: 0.6mm), and the inner tube is made of phosphorous deoxidized copper. A smooth tube (wall thickness: 0.5 mm) having an outer diameter of φ4.0 mm and an inner diameter of φ3.0 mm was prepared. With the inner tube inserted into the outer tube, the outer tube uneven portion 3 is formed using the processing jig 30 (see FIG. 7), the outer tube 2A is fitted into the inner tube 7B, and the leakage detection tube 1A (FIG. 1, see FIG. 2).
At this time, the outer tube uneven portion 3 of the leak detection tube 1A has a recess depth (HS ₁ ): 0.4 mm, a twist angle: 0 degree, the number of recesses: 16, an uneven portion length (fitting portion length): 5 m. It was. Further, in the leak detection tube 1A, the inner tube 7B protrudes from the outer tube 2A by 25 mm at both tube ends (see FIG. 10).
The two leak detection tubes 1A thus manufactured were inserted into a large-diameter tube having an outer diameter of φ15.88 mm and an inner diameter of φ14.68 mm, thereby forming a double-tube heat exchanger 20A.

Example 2
The outer tube constituting the leak detection tube is made of phosphorous deoxidized copper. The outer tube is a smooth tube (wall thickness: 0.6 mm) with an outer diameter of φ6.3 mm and the inner diameter: 5.1 mm. The inner tube is phosphorous-deoxidized copper. A smooth tube (wall thickness: 0.5 mm) having an outer diameter of φ4.8 mm and an inner diameter of φ3.8 mm was prepared. On the inner tube, an inner tube uneven portion was formed using a processing jig 30 (see FIG. 7). The inner tube with the inner tube irregularities formed is inserted inside the outer tube, and the outer tube and the inner tube are fitted using a roll, and a leak detection tube 1B (see FIG. 4) having an outer diameter of φ6 mm is used. Manufactured.
At this time, the inner tube uneven portion 8 of the leak detection tube 1B has a recess depth (HS ₂ ): 0.4 mm, a twist angle: 0 degree, the number of recesses: 16, an uneven portion length (fitting portion length): 5 m. It was. Further, in the leak detection tube 1B, the inner tube 7A protrudes from the outer tube 2B by 25 mm at both tube ends (the inner tube uneven portion 8 is not formed on the protruding portion of the protruding inner tube 7A).
The two leak detection tubes 1B thus manufactured were inserted into a large-diameter tube having an outer diameter of φ15.88 mm and an inner diameter of φ14.68 mm to obtain a double tube heat exchanger.

Example 3
The outer tube constituting the leak detection tube is made of phosphorous deoxidized copper. The outer tube is a smooth tube (wall thickness: 0.6 mm) with an outer diameter of φ6.3 mm and the inner diameter: 5.1 mm. The inner tube is phosphorous-deoxidized copper. A smooth tube (wall thickness: 0.5 mm) having an outer diameter of φ4.8 mm and an inner diameter of φ3.8 mm was prepared. Insert the inner tube into the outer tube, fit the outer tube and inner tube using a roll, outer diameter: φ6mm, fitting part length by roll fitting: 5m, the inner tube is the outer tube at both tube ends It was set as the double tube made to protrude from 25 mm. An outer tube uneven portion and an inner tube uneven portion were formed on the double tube using a processing jig 30 (see FIG. 7), and a leakage detection tube 1C (see FIG. 6) having an outer diameter of 6 mm was manufactured.
At this time, the outer tube uneven portion of the leak detection tube 1C has a recess depth (HS ₁ ): 0.4 mm, the number of recesses: 16, a twist angle: 0 degree, and the inner tube uneven portion 8 has a recess depth ( HS ₂ ): 0.4 mm, twist angle: 0 degree, number of recesses: 16.
The two leak detection tubes 1C thus manufactured were inserted into a large-diameter tube having an outer diameter of φ15.88 mm and an inner diameter of φ14.68 mm to obtain a double tube heat exchanger.

《Comparative example》
The outer tube constituting the leak detection tube is made of phosphorous deoxidized copper, and is an inner grooved tube having an outer diameter of φ6.3 mm. The inner groove shape has a bottom wall thickness of 0.6 mm and a groove depth: A 0.15 mm, groove number: 50, lead angle: 20 ° tube is prepared, and the inner tube is made of phosphorous-deoxidized copper and has an outer diameter of φ4.8 mm and an inner diameter of φ3.8 mm. (Thickness: 0.5 mm) was prepared. The inner tube was inserted into the outer tube and fitted using a roll, and the outer diameter was 6 mm. At this time, the length of the fitting portion by roll fitting was set to 5 m, and a leak detection tube in which the inner tube protruded from the outer tube by 25 mm at both tube ends was manufactured.
The two leak detection tubes thus manufactured were inserted into a large-diameter tube having an outer diameter of φ15.88 mm and an inner diameter of φ14.68 mm to obtain a double-tube heat exchanger.

<Evaluation of heat exchange performance>
Two heat exchangers of Examples 1 to 3 and Comparative Example were arranged in series. Supercritical water is flown at a rate of 1 L (liter) / min through an annular channel formed inside the large-diameter tube at a rate of 1 L (min) / min. Carbon dioxide (pressure: 9 MPa, flow rate: 1 kg / min) was flowed in the state, the temperature at the outlet side of water was measured, and the heat exchange amount was calculated. The heat exchange amount of the comparative example was set to 100, and the heat exchange amounts of Examples 1 to 3 were calculated as relative values. The results are shown in Table 1.

  From the results in Table 1, it was confirmed that the heat exchangers of Examples 1 to 3 had a larger amount of heat exchange than the heat exchangers of the comparative examples and were excellent in heat exchange performance.

It is a pipe axis orthogonal sectional view showing the composition of the leak detection pipe concerning the present invention. It is a front view along the pipe axis direction of the leak detection pipe concerning the present invention. It is a front view along the pipe axis direction of the leak detection pipe concerning the present invention. It is a pipe axis orthogonal sectional view showing composition of another embodiment of a leak detection pipe concerning the present invention. It is a front view along the pipe-axis direction of the inner pipe of FIG. It is a pipe axis orthogonal sectional view showing composition of another embodiment of a leak detection pipe concerning the present invention. (A) is a front view which shows typically the manufacturing method of the leak detection pipe | tube which concerns on this invention, (b) is a top view of the processing jig used for manufacture. (A) is a front view which shows typically another manufacturing method of the leak detection pipe | tube which concerns on this invention, (b) is sectional drawing along the roll axis | shaft of the roll for a process used for manufacture. It is a pipe axis orthogonal sectional view showing the composition of the heat exchanger concerning the present invention. (A) is the perspective view showing the structure of the pipe end part of the heat exchanger which concerns on one Embodiment of this invention, (b) is the perspective view showing the schematic structure of the heat exchanger. It is sectional drawing along the pipe-axis direction of the heat exchanger which concerns on another embodiment.

Explanation of symbols

1A, 1B, 1C Leakage detection tube 2A, 2B Outer tube 3 Outer tube uneven part 4 Concave part 5 Convex part 6 Leakage path 7A, 7B Inner pipe 8 Inner pipe uneven part 9 Concave part 10 Convex part 11, 12 Leakage path 13 Large diameter pipe 20A, 20B heat exchanger

Claims (18)

An inner pipe and an outer pipe fitted to the outside of the inner pipe, and leakage of water or refrigerant flowing inside the inner pipe or outside the outer pipe between the inner pipe and the outer pipe. A leak detection tube that detects through a leak path formed,
The outer tube is provided with an outer tube concavo-convex portion including a plurality of concave portions and convex portions formed along the pipe circumferential direction in at least a partial region of the entire length, and the concave portion of the outer pipe concavo-convex portion and the The convex portion extends along the tube axis direction of the outer tube,
In the outer tube, the inner surface of the bottom of the concave portion of the outer tube uneven portion is in contact with the inner tube,
The leak detection tube according to claim 1, wherein the leak path is formed by an outer peripheral surface of the inner tube and an inner surface of the convex portion of the outer tube uneven portion. The outer tube uneven portion has a ratio (HS ₁ / OD ₁ ) between the recess depth HS ₁ of the recess and the maximum outer diameter OD ₁ of the recess in the tube axis orthogonal cross section of 0.02 to 0.1, The leak detection tube according to claim 1, wherein the number of the concave portions is 4 to 32. The said outer tube | pump uneven | corrugated | grooved part is formed in a spiral shape along a pipe-axis direction, and twist angle (gamma) ₁ of the said recessed part with respect to a pipe axis is 30 degrees or less, The Claim 1 or Claim 2 characterized by the above-mentioned. Leak detection tube. An inner pipe and an outer pipe fitted to the outside of the inner pipe, and leakage of water or refrigerant flowing inside the inner pipe or outside the outer pipe between the inner pipe and the outer pipe. A leak detection tube that detects through a leak path formed,
The inner tube includes an inner tube uneven portion formed of a large number of recesses and protrusions formed along the tube circumferential direction in at least a partial region of the entire length thereof, and the recesses of the inner tube uneven portion and the The convex portion extends along the tube axis direction of the inner tube,
In the inner tube, the outer surface of the top of the convex portion of the inner tube uneven portion is in contact with the outer tube,
The leak detection tube according to claim 1, wherein the leak path is formed by an inner peripheral surface of the outer tube and an outer surface of the concave portion of the inner tube uneven portion. The inner tube uneven portion has a ratio (HS ₂ / OD ₂ ) between the recess depth HS ₂ of the recess and the maximum outer diameter OD ₂ of the inner tube of 0.02 to 0.1 in the cross section orthogonal to the tube axis. 5. The leak detection tube according to claim 4, wherein the number of the recesses is 4 to 32. The said inner pipe | tube uneven | corrugated | grooved part is formed in a spiral shape along a pipe-axis direction, and twist angle (gamma) ₂ of the said recessed part with respect to a pipe axis is 30 degrees or less, The Claim 4 or Claim 5 characterized by the above-mentioned. Leak detection tube. An inner pipe and an outer pipe fitted to the outside of the inner pipe, and leakage of water or refrigerant flowing inside the inner pipe or outside the outer pipe between the inner pipe and the outer pipe. A leak detection tube that detects through a leak path formed,
The outer tube and the inner tube have an outer tube uneven portion and an inner tube uneven portion that are fitted to each other and include a large number of concave portions and convex portions formed along the pipe circumferential direction in at least a partial region of the entire length. The concave portion and the convex portion of the outer tube uneven portion extend along the tube axis direction of the outer tube, and the concave portion and the convex portion of the inner tube uneven portion are in the tube axis direction of the inner tube. Stretches along,
The leak detection pipe, wherein the leak path is formed by an outer peripheral surface of the inner pipe and an inner peripheral face of the outer pipe. The outer tube concavo-convex portion has a ratio (HS ₁ / OC ₁ ) between a recess depth HS ₁ of the recess and a maximum outer diameter OD ₁ of the outer tube of 0.02 to 0.1 in a cross section orthogonal to the tube axis. The number of the recesses is 4 to 32,
The inner tube uneven portion has a ratio (HS ₂ / OD ₂ ) between the recess depth HS ₂ of the recess and the maximum outer diameter OD ₂ of the inner tube of 0.02 to 0.1 in the cross section orthogonal to the tube axis. The leak detection tube according to claim 7, wherein the number of the recesses is 4 to 32. The outer tube uneven portion and the inner tube uneven portion are each formed in a spiral shape along the tube axis direction,
In the outer tube uneven portion, the twist angle γ1 of the recess with respect to the tube axis is 30 degrees or less,
The leak detection tube according to claim 8, wherein in the inner tube uneven portion, a twist angle γ2 of the recess with respect to the tube axis is 30 degrees or less.   The leak detection pipe according to any one of claims 7 to 9, wherein a groove is formed in a pipe axis direction on an inner peripheral surface of the outer pipe.   The leak detection pipe according to any one of claims 7 to 9, wherein a rib is formed in a pipe axis direction on an outer peripheral surface of the inner pipe.   The leakage detection tube according to any one of claims 7 to 9, wherein one or both of an outer peripheral surface of the inner tube and an inner peripheral surface of the outer tube is a rough surface. A heat exchanger that uses water and a refrigerant as a heat medium, and performs heat exchange between these heat mediums,
The leak detection tube according to any one of claims 1 to 12, wherein one of water and a refrigerant is circulated inside the inside.
A heat exchanger comprising the other flow path of water or refrigerant containing the leak detection pipe.   14. The heat exchanger according to claim 13, wherein one of the water and the refrigerant flowing through the leak detection tube and the other of the water and the refrigerant flowing through the flow path are opposed to each other.   The heat exchanger according to claim 13 or 14, wherein the flow path is formed by a tubular large-diameter tube that includes the leak detection tube.   The heat exchanger according to claim 15, wherein the large-diameter pipe includes a processing portion that is corrugated along the pipe axis direction in at least a partial region of the entire length thereof.   The heat exchanger according to claim 15, wherein a groove is formed on an inner peripheral surface of the large-diameter pipe.   The heat exchanger according to any one of claims 13 to 17, wherein the refrigerant is carbon dioxide.

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