JP2001201275A - Double tube heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of a double tube heat exchanger, while suppressing the increases of the weight and cost of the heat exchanger. SOLUTION: In this double tube heat exchanger, composed of an inner tube 11 and an outer tube 12, the length of the flow passage formed between the tubes 11 and 12 is increased, and at the same time, the flow velocity and turbulent state of a fluid flowing through the flow passage are increased by interposing a heat transfer accelerating body 19 which spirally partitions the inside flow passage of the outer pipe 12 between the tubes 11 and 12. Consequently, the transfer of heat from a fluid flowing through the inner tube 11 to the fluid flowing between the tubes 11 and 12 is accelerated and the performance of the heat exchanger per unit length can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a double-pipe heat exchanger, and more particularly to a double-pipe heat exchanger used as a hot-water supply heat exchanger in a hot-water supply apparatus.

[0002]

2. Description of the Related Art For example, as shown in FIG.
A refrigerant cycle A including a heat exchanger 2 for hot water supply, an electronic expansion valve 3 and a heat source side heat exchanger 4 using outside air as a heat source, and a hot water supply cycle B including a water supply pump 5, the heat exchanger 2 for hot water supply, and a hot water tank 6 In the hot water supply heat exchanger 2, the water from the water supply pump 5 is heated by the refrigerant discharged from the compressor 1 (for example, carbon dioxide gas) to form hot water, and the hot water is stored in the hot water supply tank 6. Known hot water supply devices are known.

As shown in FIGS. 2 to 4, an inner pipe 11 is used as the hot water supply heat exchanger 2 in the hot water supply apparatus having the above-described structure.
Is concentrically inserted into the outer tube 12 and is wound into an annular shape. The inner tube 11 serves as a water flow path, and the space between the inner pipe 11 and the outer pipe 12 serves as a refrigerant flow path. Double-tube heat exchangers were usually employed. Reference numeral 13 denotes a band, 14 denotes an inner tube inlet, 15 denotes an outer tube outlet, 16 denotes an inner tube outlet, and 17 denotes an outer tube inlet.

In the case of this type of hot water supply heat exchanger, when corrosion or the like occurs in the inner pipe 11 and the inner pipe 11 and the outer pipe 12 are in communication with each other, water flowing through the inner pipe 11 has foreign matter. May be mixed, the inner pipe 11 is constituted by a leak detecting pipe formed of a double pipe having leak detecting grooves 18, 18,.・
It is obliged that when the corrosion progresses to the point where water leaks into the leak detection grooves 18, 18,..., The leak is detected to detect the leak.

[0005]

However, in order to improve the performance of the double-pipe heat exchanger having the above-described structure, a method of performing an area-enlarging process such as a spiral groove or a low fin on the inner and outer surfaces of the inner pipe. However, there is a limit to the performance improvement by this method, and the compactness of the equipment must be sacrificed without increasing the pipe length.

On the other hand, this kind of double-pipe heat exchanger is manufactured by concentrically inserting an inner pipe consisting of a double pipe (leakage detection pipe) into an outer pipe as described above. The length has a limit (for example, about 8 m).

When a high-pressure refrigerant such as carbon dioxide gas is used as the refrigerant, if the refrigerant is caused to flow through the flow path between the inner pipe and the outer pipe in the same manner as in a conventional heat exchanger for hot water supply, the pressure resistance is reduced. In order to ensure this, it is necessary to increase the thickness of the outer tube, which causes a problem that the weight and cost are significantly increased.

The present invention has been made in view of the above points, and has as its object to improve performance while suppressing an increase in weight and cost.

[0009]

According to the first aspect of the present invention, the inner tube 11 and the outer tube 1 are provided as means for solving the above problems.
2. In the double-pipe heat exchanger consisting of
A heat transfer promoting body 19 that helically partitions the inside flow path of the outer tube 12 is provided between the outer tube 12 and the outer tube 12.

With the above construction, the length of the flow path between the inner and outer pipes 11 and 12 is increased, and the flow velocity and turbulence of the fluid flowing through the flow path are increased by spiraling the flow path. It is increased by the heat transfer accelerating body 19 that partitions the shape. Therefore, the fluid flowing through the inner tube 11 is separated from the inner and outer tubes 11,
Heat transfer to the fluid flowing between the 12 is promoted,
The performance per unit length can be improved. Moreover, since the helical heat transfer enhancer 19 is interposed between the inner and outer tubes 11 and 12, concentricity of the inner and outer tubes 11 and 12 can be easily ensured even in a curved portion, for example.

As in the second aspect of the present invention, the first aspect
In the double-pipe heat exchanger described in the above, the heat transfer enhancer 19
Is provided on the outer surface of the inner pipe 11, the heat transfer promoting body 19 can be inserted simultaneously with the insertion of the inner pipe 11 into the outer pipe 12, so that the assembling work is facilitated and the heat transfer is promoted. The body 19 also functions as a heat transfer fin, and heat transfer from the fluid flowing in the inner tube 11 to the fluid flowing between the inner and outer tubes 11 and 12 is further promoted.

As in the invention of claim 3, claim 1
In the double-pipe heat exchanger described in the above, the heat transfer enhancer 19
Is projected on the inner surface of the outer tube 12, the heat transfer promoting body 19 can be inserted simultaneously with the insertion of the inner tube 11 into the outer tube 12, thereby facilitating the assembling work.

As in the fourth aspect of the present invention, in the double-pipe heat exchanger according to any one of the first, second and third aspects, the inside of the inner pipe 11 serves as a refrigerant X flow path,
When the space between the inner pipe 11 and the outer pipe 12 is a flow path of water W, even if a high-pressure refrigerant is used as the refrigerant X, it is possible to suppress an increase in pipe wall thickness for securing pressure resistance. Thus, it is possible to suppress an increase in the weight and cost of the heat exchanger and a decrease in workability at the time of coil bending.

As in the fifth aspect of the present invention, in the double-pipe heat exchanger according to any one of the first, second, third and fourth aspects, the inner pipe 11 is formed of a twisted tape or the like. When the heat transfer promoting body 21 is inserted, the performance per unit length can be further improved by the heat transfer promoting effect by increasing the speed of the fluid flowing in the inner pipe 11 and promoting the turbulence.

As in the invention of claim 6, claim 4
6. In the double-pipe heat exchanger according to any one of the above items 5, when carbon dioxide gas is employed as the refrigerant X, heat transfer performance is improved in supercritical state, and thus water heating efficiency is improved.

According to the seventh aspect of the present invention, in the double-pipe heat exchanger according to any one of the fourth, fifth and sixth aspects, the refrigerant X and the water W are allowed to flow in opposition to each other. In this case, the heat transfer performance from the refrigerant X to the water W can be improved.

As in the invention of claim 8, in the double-pipe heat exchanger according to any one of claims 1, 2, 3, 4, 5, 6, and 7, the inner pipe 11 has a leakage When a leak detecting tube having the detecting grooves 18, 18,... Is employed, the inner pipe 1 is formed due to water leaking into the leak detecting grooves 18, 18,.
1 can be found at an early stage, and safety can be ensured.

As in the ninth aspect of the present invention, in the double-pipe heat exchanger according to any one of the first, second, third, fourth, fifth, sixth, seventh and eighth aspects, the inner pipes 11 and When each of the outer tubes 12 is formed of a continuous tube having no seam in the tube length direction, the heat exchanger can be formed by two tubes, and the manufacturing cost can be reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First Embodiment FIGS. 5 and 6 show a double-pipe heat exchanger according to a first embodiment of the present invention.

This double-pipe heat exchanger is also used as the heat exchanger 2 for hot water supply in the hot water supply apparatus using carbon dioxide as a refrigerant (see FIG. 1) described in the section of the prior art. As shown in FIG. 3, the inner tube 11 is connected to the outer tube 1.
It is configured by concentrically inserted inside 2 and wound annularly.

In this double-pipe heat exchanger, as shown in FIGS. 5 and 6, an inner flow path of the outer pipe 12 is spirally provided between the inner pipe 11 and the outer pipe 12. A heat transfer promoting body 19 for partitioning in a shape is provided. 5 and 6
In the case of (1), a quadruple-wound spring is employed as the heat transfer promoting body 19. Therefore, the inner and outer tubes 1
The space between 1 and 12 is formed as a spiral flow path 20, 20.

In the present embodiment, the inside of the inner pipe 11 is used as a flow path for the refrigerant (ie, carbon dioxide gas) X, while the spiral flow paths 20, 20,. , Water W
, And the refrigerant X and the water W are made to flow in opposite directions.

The inner tube 11 is a leak detecting tube made of a double tube 11a, 11b (for example, a copper tube or the like) having good thermal conductivity and having leak detecting grooves 18, 18,... It consists of. Further, the outer tube 12 may not be a good heat conductor, but it is preferable to use the same material as the inner tube 11 in consideration of the bonding property with the inner tube 11 and the like. In addition, inner pipe 1
The outer tube 1 and the outer tube 12 are each formed of a continuous tube having no seam in the tube length direction. In this case, the heat exchanger can be constituted by the two pipes, and the manufacturing cost can be reduced.

Further, inside the inner tube 11, a heat transfer promoting body 21 for the inner tube, such as a twisted tape or a static mixer, is inserted.

In the double-pipe heat exchanger configured as described above, the following operational effects can be obtained.

Since the flow path between the inner and outer pipes 11 and 12 is divided into four helical flow paths 20, 20,..., The flow path length is increased and the helical flow paths 20, 20,. The flow velocity and turbulence of the flowing water W are increased. Accordingly, the refrigerant X flowing through the inner tube 11 is removed from the inner and outer tubes 1.
Heat transfer to the water W flowing between 1 and 12 is promoted, and performance per unit length can be improved.
Moreover, the spiral heat transfer enhancer 19 is provided between the inner and outer tubes 11 and 12.
The concentricity of the inner and outer tubes 11 and 12 is easily ensured even at the curved portion (particularly when the heat transfer promoting body 19 is a quadruple-wound spring).

In the present embodiment, since the inside of the inner tube 11 is used as the flow path of the refrigerant X as described above, when the heat transfer enhancer 19 is joined to the outer surface of the inner tube 11, the heat transfer enhancer 19 Can also act as heat transfer fins, and the refrigerant X flowing through the inner tube 11 can be
Heat transfer to the water W flowing between the two is further promoted. In addition, the heat transfer promoting body 19 can be inserted at the same time as the insertion of the inner tube 11 into the outer tube 12, thereby facilitating the assembling work.

Since the inside of the inner tube 11 is used as a flow path for the refrigerant X, and the space between the inner and outer tubes 11 and 12 is used as a flow path for the water W, the high-pressure refrigerant is used as the refrigerant X as in this embodiment. Even if carbon dioxide is used, it is possible to suppress an increase in the pipe wall thickness for securing pressure resistance, thereby suppressing an increase in the weight and cost of the heat exchanger and a decrease in workability at the time of coil bending. be able to.

Furthermore, since the heat transfer enhancer 21 for the inner pipe such as a twisted tape or a static mixer is inserted into the inner pipe 11, the speed of the refrigerant X flowing in the inner pipe 11 is increased and the turbulence is promoted. , The performance per unit length can be further improved.

Further, since a leak detecting tube having leak detecting grooves 18, 18,... Is employed as the inner tube 11, water leaks into the leak detecting grooves 18, 18,.
1 can be found at an early stage, and safety can be ensured.

As the heat transfer promoting body 19, FIG.
As shown in FIG. 8, a double-wound spring in which the space between the inner and outer pipes 11 and 12 is two spiral flow paths 20 and 20 or FIG.
As shown in FIG. 5, a single-wound spring in which the space between the inner and outer tubes 11 and 12 is a single spiral flow path 20 can be used.

As the heat transfer promoting member 21 for the inner tube, FIG.
As shown in (1), the use of a tape in which unitary lengths (for example, the length of one twist) of the torsion tapes 21a, 21a are joined orthogonally can further promote the turbulent flow of the refrigerant X.

Second Embodiment FIG. 10 shows a cross section of a double-pipe heat exchanger according to a second embodiment of the present invention.

In this case, a quadrilateral spiral projection with a quadrangular cross section is employed as the heat transfer promoting body 19. The helical projection 19 is integrally formed on the outer surface of the inner tube 11 or the inner surface of the outer tube 12. It is more effective to integrally project from the surface because it can also function as a heat transfer fin. In this case as well, the helical projections 19 are connected to the 2nd as in the first embodiment.
Double winding or single winding can also be used. The other configuration and operation and effect are the same as those in the first embodiment, and thus the description is omitted.

Third Embodiment FIG. 11 shows a cross section of a double tube heat exchanger according to a third embodiment of the present invention.

In this case, a quadrilateral spiral projection having a triangular cross section is employed as the heat transfer promoting body 19. The spiral projection 19 is integrally formed on the inner surface of the outer tube 12 with its apex facing the outer surface of the inner tube 11. By the way, when the inside of the inner tube 11 is used as a flow path for the refrigerant X, FIG.
Contrary to the above, it is more effective to integrally project from the outer surface of the inner tube 11 with the apex facing the inner surface of the outer tube 12 because it can also act as a heat transfer fin. is there. In this case as well, the spiral projection 19 is connected to the first
As in the embodiment described above, double winding or single winding may be employed. Other configurations and effects are
The description is omitted because it is the same as in the first embodiment.

Fourth Embodiment FIG. 12 shows a cross section of a double tube heat exchanger according to a fourth embodiment of the present invention.

In this case, the outer tube 11b of the inner tube 11
Are formed on the outer surface thereof. In this case, the heat transfer promoting body 19 is joined to the inner surface of the outer tube 12. By doing so, the heat transfer promoting effect on the outer surface of the inner tube 11 can be increased, and the performance per unit length can be improved. The other configuration and operation and effect are the same as those in the first embodiment, and thus the description is omitted.

[0040]

According to the first aspect of the present invention, in the double-pipe heat exchanger including the inner pipe 11 and the outer pipe 12, the outer pipe 12 is provided between the inner pipe 11 and the outer pipe 12. A heat transfer promoting body 19 that helically partitions the inner flow path of the inner and outer pipes 11
By increasing the flow path length of the flow path between the flow paths 12 and increasing the flow velocity and turbulence of the fluid flowing through the flow path, the flow from the fluid flowing through the inner pipe 11 to the fluid flowing between the inner and outer pipes 11 and 12 is increased. Is promoted, and the performance per unit length can be improved, so that a high-performance heat exchanger with a compact configuration can be obtained. In addition, since the helical heat transfer promoting body 19 is interposed between the inner and outer tubes 11 and 12, there is also an effect that the concentricity of the inner and outer tubes 11 and 12 can be easily ensured even in a curved portion, for example.

As in the invention of claim 2, claim 1
In the double-pipe heat exchanger described in the above, the heat transfer enhancer 19
Is provided on the outer surface of the inner pipe 11, the heat transfer promoting body 19 can be inserted simultaneously with the insertion of the inner pipe 11 into the outer pipe 12, so that the assembling work is facilitated and the heat transfer is promoted. The body 19 also functions as a heat transfer fin, and heat transfer from the fluid flowing in the inner tube 11 to the fluid flowing between the inner and outer tubes 11 and 12 is further promoted.

As in the invention of claim 3, claim 1
In the double-pipe heat exchanger described in the above, the heat transfer enhancer 19
Is projected on the inner surface of the outer tube 12, the heat transfer promoting body 19 can be inserted simultaneously with the insertion of the inner tube 11 into the outer tube 12, thereby facilitating the assembling work.

As in the fourth aspect of the present invention, in the double-pipe heat exchanger according to any one of the first to third aspects, the inside of the inner pipe 11 serves as a flow path for the refrigerant X,
When the space between the inner pipe 11 and the outer pipe 12 is a flow path of water W, even if a high-pressure refrigerant is used as the refrigerant X, it is possible to suppress an increase in pipe wall thickness for securing pressure resistance. Thus, it is possible to suppress an increase in the weight and cost of the heat exchanger and a decrease in workability at the time of coil bending.

As in the fifth aspect of the present invention, in the double-pipe heat exchanger according to any one of the first, second, third and fourth aspects, the inner pipe 11 includes a twisted tape or the like for the inner pipe. When the heat transfer promoting body 21 is inserted, the performance per unit length can be further improved by the heat transfer promoting effect by increasing the speed of the fluid flowing in the inner pipe 11 and promoting the turbulence.

As in the invention of claim 6, claim 4
6. In the double-pipe heat exchanger according to any one of the above items 5, when carbon dioxide gas is employed as the refrigerant X, heat transfer performance is improved in supercritical state, and thus water heating efficiency is improved.

In the double-pipe heat exchanger according to any one of claims 4, 5 and 6, as in the invention of claim 7, the refrigerant X and the water W are circulated so as to face each other. In this case, the heat transfer performance from the refrigerant X to the water W can be improved.

As in the invention of claim 8, in the double-pipe heat exchanger according to any one of claims 1, 2, 3, 4, 5, 6, and 7, the inner pipe 11 has a leakage. When a leak detecting tube having the detecting grooves 18, 18,... Is employed, the inner pipe 1 is formed due to water leaking into the leak detecting grooves 18, 18,.
Corrosion and the like can be detected at an early stage, and safety can be ensured.

As in the ninth aspect of the present invention, in the double-pipe heat exchanger according to any one of the first, second, third, fourth, fifth, sixth, seventh and eighth aspects, the inner pipes 11 and When each of the outer tubes 12 is formed of a continuous tube having no seam in the tube length direction, the heat exchanger can be formed by two tubes, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a general hot water supply apparatus.

FIG. 2 is a side view of a double-pipe heat exchanger used as a hot water supply heat exchanger in a general hot water supply apparatus.

FIG. 3 is a plan view of a double-pipe heat exchanger used as a heat exchanger for hot water supply in a general hot water supply apparatus.

FIG. 4 is a cross-sectional view of a conventional double tube heat exchanger.

FIG. 5 is a partially cutaway perspective view showing a main part of the double-pipe heat exchanger according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view of the double-pipe heat exchanger according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view showing another example of the double-pipe heat exchanger according to the first embodiment of the present invention.

FIG. 8 is a sectional view showing another example of the double-pipe heat exchanger according to the first embodiment of the present invention.

FIG. 9 is a perspective view showing another example of the heat transfer enhancer for the inner pipe in the double-pipe heat exchanger according to the first embodiment of the present invention.

FIG. 10 is a sectional view of a double-pipe heat exchanger according to a second embodiment of the present invention.

FIG. 11 is a sectional view of a double-pipe heat exchanger according to a third embodiment of the present invention.

FIG. 12 is a sectional view of a double-pipe heat exchanger according to a fourth embodiment of the present invention.

[Explanation of symbols]

11 is an inner tube, 12 is an outer tube, 18 is a leak detection groove, 19 is a heat transfer enhancer, 21 is a heat transfer enhancer for the inner tube, X is a refrigerant (carbon dioxide), and W is water.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3L065 EA12 3L103 AA01 AA05 AA35 AA39 AA44 BB43 CC02 CC40 DD04 DD19 DD38

Claims (9)

[Claims] 1. An inner pipe (11) and an outer pipe (12), and an inner flow path of the outer pipe (12) is spirally provided between the inner pipe (11) and the outer pipe (12). A double-pipe heat exchanger comprising a heat transfer promoting body (19) for partitioning the heat exchanger into a shape. 2. The heat transfer promoting body (19) is connected to the inner pipe (1).
2. The method as claimed in claim 1, wherein the projection is provided on the outer surface.
The double tube heat exchanger as described. 3. The heat transfer promoting body (19) is connected to the outer tube (1).
2. The method according to claim 1, wherein the projection is provided on the inner surface of the structure.
The double tube heat exchanger as described. 4. A space between the inner pipe (11) and the outer pipe (12) is defined as a flow path for water (W) while the inside of the inner pipe (11) serves as a flow path for the refrigerant (X). The double-pipe heat exchanger according to any one of claims 1, 2 and 3, characterized in that: 5. The heat transfer promoting member (21) for an inner pipe made of a twisted tape or the like is inserted into the inner pipe (11). The double-pipe heat exchanger according to the above item. 6. The double-pipe heat exchanger according to claim 4, wherein carbon dioxide gas is employed as the refrigerant (X). 7. The method according to claim 4, wherein the refrigerant (X) and the water (W) are circulated so as to face each other.
The double-pipe heat exchanger according to any one of claims 5 and 6. 8. A leak detecting tube having leak detecting grooves (18), (18),... As said inner tube (11). The double-pipe heat exchanger according to any one of claims 1 to 6, 6 and 7. 9. The inner pipe (11) and the outer pipe (12).
Wherein each of the pipes is constituted by a continuous pipe body having no seam in the pipe length direction.
The double-pipe heat exchanger according to any one of 4, 5, 6, 7, and 8.