EP2902741A1

EP2902741A1 - Heat exchanger

Info

Publication number: EP2902741A1
Application number: EP13841913.0A
Authority: EP
Inventors: Tomoaki Kitano; Toyoaki Takeshita; Kazuhiko Machida; Akihiro Shigeta
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2012-09-28
Filing date: 2013-09-18
Publication date: 2015-08-05
Anticipated expiration: 2033-09-18
Also published as: WO2014050026A1; JP6057154B2; EP2902741A4; JP2014070779A; EP2902741B1; CN104704316B; CN104704316A

Abstract

A heat exchanger of the present invention includes a flow path forming portion 40 which separates a first flow path 11 of one row into a one-directional flowing portion 81 formed around an other-directional pipe portion 22 and an other-directional flowing portion 82 formed around a one-directional pipe portion 21, a flow path cross-sectional area of the one-directional flowing portion 81 is made smaller toward a downstream side, a flow path cross-sectional area of the other-directional flowing portion 82 is made greater toward the downstream side and hence, it is possible to enhance a heat transfer facilitating effect and to reduce a pressure loss.

Description

[TECHNICAL FIELD]

The present invention relates to a heat exchanger which can be used as a water heater for example.

[BACKGROUND TECHNIQUE]

A heat exchanger used for a water heater is required to possess pressure resistance and heat resistance and therefore, a double pipe composed of a copper pipe is generally used.
On the other hand, there is proposed a heat exchanger in which a resin case for accommodating a metal pipe is used, heat medium flows through the pipe and water to be heated flows between the pipe and the resin case (patent document 1).

[PRIOR ART DOCUMENT]

[PATENT DOCUMENT]

[PATENT DOCUMENT 1] Japanese Patent Application Laid-open No. 2002-333290

[DISCLOSURE OF THE INVENTION]

[PROBLEM TO BE SOLVED BY THE INVENTION]

According to patent document 1, a bending operation can easily be carried out as compared with formation of a double pipe composed of a metal pipe, and it is possible to finely bend the metal pipe and to make an outer shape size of a heat exchanger compact.
However, to make the heat exchanger compact and to enhance heat exchange efficiency, it is necessary to enhance a heat transfer facilitating effect and to reduce a pressure loss.
Hence, it is an object of the present invention to provide a heat exchanger capable of enhancing a heat transfer facilitating effect and reducing a pressure loss.

[MEANS FOR SOLVING THE PROBLEM]

A first aspect of the present invention provides a heat exchanger comprising a resin case forming a first flow path through which first fluid flows, and a pipe forming a second flow path through which second fluid flows, the pipe being placed in the first flow path, wherein the first flow path is separated into a plurality of rows in the resin case, the pipe is composed of a one-directional pipe portion through which the second fluid flows in a one direction, an other-directional pipe portion through which the second fluid flows in an other direction, and a bent portion connecting the one-directional pipe portion and the other-directional pipe portion to each other, the heat exchanger also includes a flow path forming portion which separates the first flow path of the one row into a one-directional flowing portion formed around the other-directional pipe portion and an other-directional flowing portion formed around the one-directional pipe portion, a flow path cross-sectional area of the one-directional flowing portion is made smaller toward a downstream side, and a flow path cross-sectional area of the other-directional flowing portion is mage greater toward the downstream side.
According to a second aspect of the invention, in the heat exchanger of the first aspect, the heat exchanger further includes a lid which covers an opened end of the first flow path and which is fixed to the resin case, wherein the lid is provided with a convex portion on which the bent portion is placed.
According to a third aspect of the invention, in the heat exchanger of the second aspect, a seal portion is provided on a portion of the pipe projecting from the resin case, the lid includes a wall surface located on the opened end, and a pipe-penetrating portion projecting from the wall surface, and the seal portion and the pipe-penetrating portion are sealed.
According to a fourth aspect of the invention, in the heat exchanger of the second or third aspect, a one end of the flow path forming portion is opposed to the bent portion, and the lid is fixed to the resin case such that the lid is opposed to the opened end and an other end of the flow path forming portion.
According to a fifth aspect of the invention, in the heat exchanger of the fourth aspect, outer shapes of both ends of the one-directional flowing portion and the other-directional flowing portion are substantially semi-circular.
A sixth aspect of the invention provides a water heater including the heat exchanger according to any one of the first to fifth aspects.

[EFFECT OF THE INVENTION]

According to the present invention, the flow path cross-sectional area of the one-directional flowing portion is made smaller toward the downstream side, and the flow path cross-sectional area of the other-directional flowing portion is made greater toward the downstream side. According to this, flowing speed is increased and the heat transfer facilitating effect is enhanced at the one-directional flowing portion, a pressure loss is reduced at the other-directional flowing portion, and it is possible to realize a heat exchanger having high heat transfer efficiency and a small pressure loss as a whole.

[BRIEF DESCRIPTION OF THE DRAWINGS]

Fig. 1 is a perspective view of an outward appearance of a heat exchanger according to an embodiment of the present invention;
Fig. 2 is a perspective view of a resin case used for the heat exchanger;
Fig. 3 is a perspective view of a pipe used for the heat exchanger;
Fig. 4 is a perspective view of a lid used for the heat exchanger;
Fig. 5 is an exploded perspective view of the heat exchanger;
Figs. 6 are perspective views showing assembling procedure of the heat exchanger;
Fig. 7 is a plan view of a resin case used for the heat exchanger;
Fig. 8 is a side view of the resin case;
Fig. 9 is a sectional view of the resin case as viewed from above;
Fig. 10 is a sectional view of the resin case as viewed from side;
Fig. 11 is a sectional view taken along line X-X in Fig. 9;
Fig. 12 is a plan view of a flow path forming portion used for the heat exchanger;
Fig. 13 is a side view of the flow path forming portion;
Fig. 14 is a sectional view taken along line Y-Y in Fig. 13;
Fig. 15 is a sectional view taken along line Z-Z in Fig. 13;
Fig. 16 is a sectional view of the flow path forming portion as viewed from above;
Fig. 17 is a sectional view of the flow path forming portion as viewed from side;
Fig. 18 is a sectional view of the heat exchanger as viewed from above; and
Fig. 19 is a sectional view of a first flow path of a first row in Fig. 18.

[EXPLANATION OF SYMBOLS]

10: resin case
11: first flow path
12: partition walls
13: opened end
15: ribs
16a: one end
16b: other end
17a: one end
17b: other end
20: pipe
21: one-directional pipe portion
22: other-directional pipe portion
23: bent portion
24: seal portion
30: lid
31: wall surface
32: pipe-penetrating portion
33: convex portion
40: flow path forming portion
41: hollow portion
50: packing
81: one-directional flowing portion
82: other-directional flowing portion

[MODE FOR CARRYING OUT THE INVENTION]

The heat exchanger according to a first aspect of the invention, the heat exchanger also includes a flow path forming portion which separates the first flow path of the one row into a one-directional flowing portion formed around the other-directional pipe portion and an other-directional flowing portion formed around the one-directional pipe portion, a flow path cross-sectional area of the one-directional flowing portion is made smaller toward a downstream side, and a flow path cross-sectional area of the other-directional flowing portion is mage greater toward the downstream side. According to this aspect, flowing speed is increased and the heat transfer facilitating effect is enhanced at the one-directional flowing portion, a pressure loss is reduced at the other-directional flowing portion, and it is possible to realize a heat exchanger having high heat transfer efficiency and a small pressure loss as a whole.
According to a second aspect of the invention, in the heat exchanger of the first aspect, the lid is provided with a convex portion on which the bent portion is placed. According to this aspect, a temperature difference is generated between the inlet side and the outlet side by the heat exchange, but since the bent portion is placed outside the resin case, the temperature difference of the pipe in the lid can be made small. Since the bent portion is placed on the convex portion, the heat exchanger can be made compact and the assembling performance can be enhanced.
According to the third aspect of the invention, in the heat exchanger of the second aspect, a seal portion provided on a portion of the pipe which projects from the resin case and a pipe-penetrating portion projecting from a wall surface are sealed. According to this aspect, sealing performance and assembling performance of the heat exchanger can be enhanced.
According to a fourth aspect of the invention, in the heat exchanger of the second or third aspect, a one end of the flow path forming portion is opposed to the bent portion, and the lid is fixed to the resin case such that the lid is opposed to the opened end and an other end of the flow path forming portion. According to this aspect, the pipe is inserted into the resin case and then, the flow path forming portion is inserted such that it is opposed to the bent portion and lastly, the lid is fixed to the resin case, thereby assembling the heat exchanger. Hence, it is possible to enhance the assembling performance of the heat exchanger.
According to a fifth aspect, in the heat exchanger of the fourth aspect, outer shapes of both ends of the one-directional flowing portion and the other-directional flowing portion are substantially semi-circular. According to this aspect, even if first fluid remaining in the one-directional flowing portion and the other-directional flowing portion is frozen and volume expands in winter, stress generated by the volume expansion can be dispersed. Hence, it is possible to prevent the resin case from being damaged.
A water heater of a sixth aspect of the invention includes the heat exchanger according to any one of the first to fifth aspects. According to this aspect, it is possible to provide a water heater including the heat exchanger capable of enhancing the heat transfer facilitating effect and reducing a pressure loss.

[Embodiment]

An embodiment of the present invention will be described below using the drawings.
Fig. 1 is a perspective view of an outward appearance of a heat exchanger according to the embodiment.
As shown in Fig. 1, the heat exchanger of the embodiment includes a resin case 10 forming first flow paths through which first fluid flows, a pipe 20 forming a second flow path through which second fluid flows. The pipe 20 is placed in the first flow path. The heat exchanger also includes a lid 30 fixed to the resin case 10. A parallel portion 20a is formed on a portion of the pipe 20 which projects from the lid 30.
The heat exchanger of the embodiment uses water as the first fluid and refrigerant as the second fluid for example. In the heat exchanger of the embodiment, a compressor, an expansion valve and an evaporator are connected to one another through a pipe, thereby configuring a refrigeration cycle. High temperature refrigerant which is compressed by the compressor is introduced into the heat exchanger of the embodiment. If the heat exchanger is utilized as a radiator as in this embodiment, it is possible to heat first fluid. Water as the first fluid is made to flow in a direction opposite from a flow of the introduced high temperature refrigerant, and the introduced water takes heat from the refrigerant and becomes hot water. The heat exchanger which produces hot water can be utilized as a water heater such as a heat pump water heater and a hot water room heater.
When the heat exchanger of the embodiment is utilized as an evaporator, it is possible to cool the first fluid.
Vapor and high temperature hot water generated by a boiler can be used as the second fluid in addition to refrigerant.
Fig. 2 is a perspective view of the resin case used in the heat exchanger of the present invention.
In the resin case 10, the first flow paths 11 are separated into a plurality of rows by partition walls 12.
In this embodiment, the first flow paths 11 are separated into five rows by the four partition walls 12. One surface of the resin case 10 is an opened end 13, and the first flow paths 11 are opened. A surface of the resin case 10 opposed to the opened end 13 is a closed end 14 which is closed. A plurality of ribs 15 project from an outer periphery of the resin case 10 other than the opened end 13 and the closed end 14. The plurality of ribs 15 are provided at equal distances from one another, and the ribs 15 are provided over an upper surface, a lower surface and both side surfaces of the resin case 10. The ribs 15 straddle the first flow paths 11 which are separated into the plurality of rows.
The resin case 10 is made of thermoplastic crystalline plastic, and polyphenylene sulfide resin (PPS) is suitable. The resin case 10 is integrally molded using a mold.
Fig. 3 is a perspective view of the pipe used for the heat exchanger.
The pipe 20 is composed of a one-directional pipe portion 21 through which second fluid flows in one direction, an other-directional pipe portion 22 through which second fluid flows in the other direction, and a bent portion 23 which connects the one-directional pipe portion 21 and the other-directional pipe portion 22 to each other. The pipe 20 is made of metal, and a copper pipe is suitable as the pipe 20.
Here, the one direction is a direction extending from the opened end 13 toward the closed end 14 in a state where the pipe 20 is placed in the resin case 10. The other direction is a direction extending from the closed end 14 toward the opened end 13 in a state where the pipe 20 is placed in the resin case 10. Therefore, the one direction and the other direction are opposite from each other.
A portion of the pipe 20 which projects from the resin case 10 is provided with seal portions 24. A coming-in connecting pipe portion 25a is formed on one end of the pipe 20, and a coming-out connecting pipe portion 25b is formed on the other end of the pipe 20. The seal portions 24 are provided on the coming-in connecting pipe portion 25a and the coming-out connecting pipe portion 25b. Portions of the coming-in connecting pipe portion 25a and the coming-out connecting pipe portion 25b which are located closer to ends than the seal portions 24 project from the lid 30.
The seal portion 24 is composed of a sealing plate which is concentrically welded to a periphery of the pipe 20 and an O-ring placed in a groove formed in an outer periphery of the sealing plate.
In this embodiment, the pipe 20 is parallely branched into four rows.
According to the pipes 20, a first bent portion 23 is connected to a downstream side end of a first one-directional pipe portion 21, an upstream side end of a first other-directional pipe portion 22 is connected to the first bent portion 23, and a second bent portion 23 is connected to a downstream side end of the first other-directional pipe portion 22. An upstream side end of the second one-directional pipe portion 21 is connected the second bent portion 23, a third bent portion 23 is connected to a downstream side end of the second one-directional pipe portion 21, an upstream side end of a second other-directional pipe portion 22 is connected to the third bent portion 23, and a fourth bent portion 23 is connected to a downstream side end of the second other-directional pipe portion 22. The pipes 20 are connected such that the one-directional pipe portions 21, the bent portions 23 and the other-directional pipe portions 22 are continuously connected to one another so that second fluid flowing through the one-directional pipe portions 21 and second fluid flowing through the other-directional pipe portions 22 flow in opposite directions.
Therefore, the pipes 20 of the embodiment are configured such that the following portions are continuous from one another in this order: the coming-in connecting pipe portion 25a, the first one-directional pipe portion 21, the first bent portion 23, the first other-directional pipe portion 22, the second bent portion 23, the second one-directional pipe portion 21, the third bent portion 23, the second other-directional pipe portion 22, the fourth bent portion 23, the third one-directional pipe portion 21, a fifth bent portion 23, a third other-directional pipe portion 22, a sixth bent portion 23, a fourth one-directional pipe portion 21, a seventh bent portion 23, a fourth other-directional pipe portion 22, an eighth bent portion 23, a fifth one-directional pipe portion 21, a ninth bent portion 23, a fifth other-directional pipe portion 22, a tenth bent portion 23, and a coming-out connecting pipe portion 25b.
From respective structures and functions of the pipes 20, the pipes 20 are described as the coming-in connecting pipe portion 25a, the one-directional pipe portion 21, the bent portion 23, the other-directional pipe portion 22 and the coming-out connecting pipe portion 25b, but it is preferable that the pipes 20 are not connected to one another by welding, and that the pipes 20 are configured by bending one copper pipe. Since the pipe 20 is parallely branched into four rows in this embodiment, the pipes 20 include four first one-directional pipe portions 21, four first bent portions 23 and four first other-directional pipe portions 22.
The one-directional pipe portion 21 and the other-directional pipe portion 22 are not straight in shape but they are formed into corrugated shapes.
Fig. 4 is a perspective view of the lid used for the heat exchanger.
The lid 30 includes a wall surface 31 located at the opened end 13, and pipe-penetrating portions 32 projecting from the wall surface 31. The wall surface 31 covers the opened end 13 of the first flow path 11. The pipe-penetrating portions 32 are placed on both sides of the wall surface 31. The wall surface 31 of the lid 30 is provided with convex portions 33. The convex portions 33 are placed between the two pipe-penetrating portions 32. The bent portions 23 are placed on the convex portions 33 on the side of the opened end 13. The seal portions 24 are placed on the pipe-penetrating portions 32.
The pipe-penetrating portion 32 includes a cylindrical portion 32a through which the pipe 20 penetrates, a cylindrical portion 32b from which first fluid comes in or a cylindrical portion 32c from which first fluid comes out. The cylindrical portion 32a through which the pipe 20 penetrates and the cylindrical portion 32b from which first fluid comes in, or, the cylindrical portion 32a and the cylindrical portion 32c from which first fluid comes out have axes extending in a direction perpendicular to the wall surface 31. The pipe-penetrating portion 32 includes a hole-forming cylindrical portion 32d for forming a hole, at the time of integral resin molding, through which the cylindrical portion 32a through which the pipe 20 penetrates and the cylindrical portion 32b from which first fluid comes in is communicated with each other. The pipe-penetrating portion 32 also includes a hole-forming cylindrical portion 32d for forming a hole, at the time of integral resin molding, through which the cylindrical portion 32a through which the pipe 20 penetrates and the cylindrical portion 32c from which first fluid comes out is communicated with each other. These hole-forming cylindrical portions 32d are closed with plugs 32e. Seal members are provided on outer peripheries of the plug 32e.
The pipe-penetrating portion 32 which is placed on one of sides of the wall surface 31 is composed of the cylindrical portion 32a from which second fluid comes out, the cylindrical portion 32b from which first fluid comes in, and the hole-forming cylindrical portion 32d.
The pipe-penetrating portion 32 which is placed on the other side of the wall surface 31 is composed of the cylindrical portion 32a from which second fluid comes in, the cylindrical portion 32c from which first fluid comes out, and the hole-forming cylindrical portion 32d.
The lid 30 is made of the same material as that of the resin case 10. For example, thermoplastic crystalline plastic, especially polyphenylene sulfide resin (PPS) is suitable.
The lid 30 is integrally molded using resin.
An outer periphery of the wall surface 31 has a plurality of fastening holes 34 for fixing the lid 30 to the resin case 10.
Fig. 5 is an exploded perspective view of the heat exchanger of the present invention.
The heat exchanger of the present invention is composed of the resin case 10, the pipes 20, flow path forming portions 40, a packing 50 and the lid 30.
Each of the flow path forming portions 40 is placed in the resin case 10. The flow path forming portion 40 separates one row of the first flow path 11 into a one-directional flowing portion formed around the other-directional pipe portion 22 and the other-directional flowing portion formed around the one-directional pipe portion 21.
The packing 50 is placed between the resin case 10 and the lid 30, and secures airtightness between the resin case 10 and the lid 30, and airtightness between the flow path forming portions 40 and the lid 30.
The heat exchanger of the present invention includes a first fluid coming-in pipe 61 from which first fluid comes in, a first fluid coming-out pipe 62 from which first fluid comes out, a second fluid coming-in pipe 71 from which second fluid comes in, and a second fluid coming-out pipe 72 from which second fluid comes out.
The first fluid coming-in pipe 61 is connected to the cylindrical portion 32b from which first fluid comes in. The first fluid coming-out pipe 62 is connected to the cylindrical portion 32c from which first fluid comes out. The second fluid coming-in pipe 71 is connected to the coming-in connecting pipe portion 25a. The second fluid coming-out pipe 72 is connected to the coming-out connecting pipe portion 25b.
The first fluid coming-in pipe 61 has an L-shaped bent portion, and is connected to the pipe-penetrating portion 32 placed on one of sides of the wall surface 31. Since the first fluid coming-in pipe 61 has the L-shaped bent portion, the first fluid coming-in pipe 61 has a parallel portion 61a which is substantially parallel to the wall surface 31. The parallel portion 61a has a length extending from the one side of the wall surface 31 to the other side of the wall surface 31.
The convex portions 33 project into a space generated between the wall surface 31 and the parallel portion 61a.
As shown in Fig. 1, an L-shaped bent portion is formed also on the coming-out connecting pipe portion 25b from which second fluid comes out. According to this, the parallel portion 20a which is substantially parallel to the wall surface 31 is formed. The parallel portion 20a extends from the one side of the wall surface 31 to the other side of the wall surface 31.
Next, an assembling method of the heat exchanger of the present invention will be described using Figs. 6.
Figs. 6 are perspective views showing assembling procedure of the heat exchanger of the invention.
First, as shown in Fig. 6(a), the pipes 20 are inserted from the opened end 13 and placed in the resin case 10. The first one-directional pipe portion 21 and the first other-directional pipe portion 22 are placed in every one row of the first flow path 11.
Next, as shown Fig. 6 (b), the flow path forming portions 40 are inserted from the opened end 13, one ends of the flow path forming portions 40 are opposed to the bent portions 23 located on the side of the closed end 14, and the flow path forming portions 40 are placed in the resin case 10. Each of the flow path forming portions 40 is placed between the first one-directional pipe portion 21 and the first other-directional pipe portion 22 placed in one row of the first flow path 11. By placing the flow path forming portion 40, one row of the first flow path 11 can be separated into the one-directional flowing portion formed around the other-directional pipe portion 22 and the other-directional flowing portion formed around the one-directional pipe portion 21.
In Fig. 6(c), the packing 50 is placed on the opened end 13. The packing 50 is located on the outer periphery of the opened end 13 and the flow path forming portions 40, and it is possible to secure airtightness between the resin case 10 and the lid 30 and airtightness between the flow path forming portions 40 and the lid 30.
In Fig. 6(d), the lid 30 is abutted against the opened end 13 and the flow path forming portions 40 such that the lid 30 is opposed to the other ends of the flow path forming portions 40, and the lid 30 is fixed to the resin case 10 using fastening tools 35. Both ends of the each of the pipes 20 pass through the cylindrical portion 32a from which second fluid comes in and the cylindrical portion 32a from which second fluid comes out, and project from the resin case 10. The seal portion 24 is located in the cylindrical portion 32a.
As shown in Fig. 6(e), the pipe 20 placed in the cylindrical portion 32a from which second fluid comes out is provided with the L-shaped bent portion, thereby forming the parallel portion 20a. The pipe 20 having the parallel portion 20a is connected to the second fluid coming-out pipe 72 from which second fluid comes out. The pipe 20 placed in the cylindrical portion 32a from which second fluid comes in is connected to the second fluid coming-in pipe 71 from which second fluid comes in.
By connecting the first fluid coming-in pipe 61 and the first fluid coming-out pipe 62 to each other from a state shown Fig. 6(e), a state shown in Fig. 1 is obtained.
Details of essential constituent members will be described below.
Fig. 7 is a plan view of the resin case used for the heat exchanger of the present invention, Fig. 8 is a side view of the resin case, Fig. 9 is a sectional view of the resin case as viewed from above, Fig. 10 is a sectional view of the resin case as viewed from side and Fig. 11 is a sectional view taken along line X-X in Fig. 9.
As shown especially in Figs. 7 and 8, the resin case 10 is provided with the plurality of ribs 15 between the opened end 13 and the closed end 14. The plurality of ribs 15 have surfaces which are perpendicular to a flowing direction of first fluid at right angles.
It is not absolutely necessary that the surfaces of the plurality of ribs 15 are perpendicular to the flowing direction of first fluid at right angles. That is, it is only necessary that the plurality of ribs 15 straddle at least two rows of the first flow paths 11, e.g., a first row of the first flow path 11a and a second rows the first flow path 11b.
In addition to these ribs 15, it is preferable that the first row of the first flow path 11a, the second row of the first flow path 11b, the third row of the first flow path 11c and other rows of the first flow paths 11 are provided with ribs 15 which are parallel to a flowing direction of first fluid.
As shown in Figs. 9 to 11, the partition walls 12 separate the first row of the first flow path 11a and the second row of the first flow path 11b from each other. The partition walls 12 are composed of a partition wall 12a forming the first row of the first flow path 11a and a partition wall 12b forming the second row of the first flow path 11b.
Similarly, the partition walls 12 separate the second row of the first flow path 11b and the third row of the first flow path 11c from each other. The partition walls 12 are composed of a partition wall 12c forming the second row of the first flow path 11b and a partition wall 12d forming the third row of the first flow path 11c. Other partition walls 12 have the same configurations.
The partition wall 12a forming the first row of the first flow path 11a and the partition wall 12b forming the second row of the first flow path 11b are connected to each other through the plurality of ribs 15. The partition wall 12c forming the second row of the first flow path 11b and the partition wall 12d forming the third row of the first flow path 11c are connected to each other through the plurality of ribs 15. Other partition walls 12 have the same configurations.
Therefore, the first flow paths 11 separated into the plurality of rows are connected to each other through the ribs 15. Since spaces are formed between the first flow paths 11 except the ribs 15, it is possible to prevent heat from transferring between the adjacent first flow paths 11, e.g. between the first row of the first flow path 11a and the second row of the first flow path 11b.
Although the spaces are formed between the first flow paths 11 which are separated into the plurality of rows except the ribs 15 in this embodiment, the first flow paths 11 may be connected to each other without forming the spaces.
The first flow paths 11 have such a temperature gradient that the temperature becomes high from low from an inlet toward an outlet, and temperatures of the first flow paths 11 are different not only in the respective rows of the first flow paths 11, but also in the one row of the first flow path 11. Although it is not illustrated in the drawings, a heat insulating material is placed on the outer periphery of the resin case 10 or the outer periphery of the resin case 10 is covered with an outer case.
Therefore, by separating the outer periphery of the resin case 10 into a plurality of spaces by the plurality of ribs 15, it is possible to prevent heat from transferring at the outer periphery of the resin case 10 and to reduce a heat radiation loss.
A width of the first flow path 11 is defined as W, a height of the first flow path 11 is defined as H, a width of the first flow path 11 on the side of the opened end 13 is defined as W1, a height of the first flow path 11 on the side of the opened end 13 is defined as H1, a width of the first flow path 11 on the side of the closed end 14 is defined as W2, a height of the first flow path 11 on the side of the closed end 14 is defined as H2, W1 is set greater than W2, and H1 is set greater than H2.
The width W1 and the height H1 of the first flow path 11 on the side of the opened end 13 are set greater than the width W2 and the height H2 of the first flow path 11 on the side of the closed end 14 in this manner. According to this, a flow path cross-sectional area on the side of the opened end 13 becomes greater than a flow path cross-sectional area on the side of the closed end 14. That is, the flow path cross-sectional area of the first flow path 11 becomes continuously smaller from the opened end 13 toward the closed end 14.
Therefore, when the first flow path 11 is separated by the flow path forming portion 40 into the one-directional flowing portion formed around the other-directional pipe portion 22 and the other-directional flowing portion formed around the one-directional pipe portion 21, the flow path cross-sectional area of the one-directional flowing portion becomes smaller toward the downstream side, i.e., toward the closed end 14 from the opened end 13, and the flow path cross-sectional area of the other-directional flowing portion becomes greater toward the downstream side, i.e., toward the opened end 13 from the closed end 14. Hence, at the one-directional flowing portion, flowing speed is increased, the heat transfer facilitating effect is enhanced, and at the other-directional flowing portion, a pressure loss is reduced, and a heat exchanger having high heat exchanging efficiency and a small pressure loss can be realized as a whole.
Fig. 12 is a plan view of the flow path forming portion used for the heat exchanger, Fig. 13 is a side view of the flow path forming portion, Fig. 14 is a sectional view taken along line Y-Y in Fig. 13, Fig. 15 is a sectional view taken along line Z-Z in Fig. 13, Fig. 16 is a sectional view of the flow path forming portion as viewed from above, and Fig. 17 is a sectional view of the flow path forming portion as viewed from side.
A hollow portion 41 which is a hollow is formed in the flow path forming portion 40, and the flow path forming portion 40 is formed into a columnar shape by an upper surface 42, a lower surface 42 and a side surface 43. Both end surfaces 44 of the flow path forming portion 40 are closed. Enlarged portions 41a are formed at upper and lower portions of the hollow portion 41.
Convex portions 42a are formed in central portions of the upper surface 42 and the lower surface 42 in the longitudinal direction. Concave portions 43a are formed in the side surface 43 in the longitudinal direction.
Since the hollow portion 41 is formed in the flow path forming portion 40 by the space, the flow path forming portion 40 is easily deformed by the hollow portion 41. Therefore, even if volume of first fluid is expanded by freezing in winter, it is possible to prevent the resin case 10 from being damaged.
Fig. 18 is a sectional view of the heat exchanger as viewed from above, and Fig. 19 is a sectional view of the first flow path of the first row in Fig. 18.
One flow path forming portion 40 is placed in the first row first flow path 11a. In the first flow path 11a, one end of the flow path forming portion 40 is opposed to the bent portion 23 and the other end of the flow path forming portion 40 is opposed to the lid 30.
As shown in Fig. 19, the first row first flow path 11a is separated by the flow path forming portion 40 into a one-directional flowing portion 81 formed around the other-directional pipe portion 22 and the other-directional flowing portion 82 formed around the one-directional pipe portion 21.
One flow path forming portion 40 is placed in each of the second row first flow path 11b, the third row first flow path 11c, and first flow paths 11 of other rows, and the one-directional flowing portion 81 and the other-directional flowing portion 82 are formed similarly.
Outer shapes and inner shapes of one end 16a and the other end 16b in a cross section of the one-directional flowing portion 81 which is perpendicular to a flowing direction are substantially semi-circular in shape. Outer shapes and inner shapes of the one end 16a and the other end 16b of the one-directional flowing portion 81 are circles which are concentric to the pipe 20, and thicknesses of the substantially semi-circular one end 16a and the other end 16b are constant.
Outer shapes and inner shapes of one end 17a and the other end 17b in a cross section of the other-directional flowing portion 82 which is perpendicular to a flowing direction are substantially semi-circular in shape. Outer shapes and inner shapes of the one end 17a and the other end 17b of the other-directional flowing portion 82 are circles which are concentric to the pipe 20, and thicknesses of the substantially semi-circular one end 17a and the other end 17b are constant.
Case-side convex portions 18 are formed between the one end 16a of the one-directional flowing portion 81 and the one end 17a of the other-directional flowing portion 82, and between the other end 16b of the one-directional flowing portion 81 and the other end 17b of the other-directional flowing portion 82. The case-side convex portions 18 project outward at positions corresponding to the convex portions 42a of the flow path forming portion 40.
Both the ends 16a and 16b of the one-directional flowing portion 81 and both the ends 17a and the 17b of the other-directional flowing portion 82 are substantially semi-circular in outer shape. According to this, even when volumes of the one-directional flowing portion 81 and the other-directional flowing portion 82 are expanded by freezing of first fluid which remains therein in winter, stress caused by the volume expansion can be distributed, and it is possible to prevent the resin case 10 from being damaged.
By the case-side convex portions 18 provided at the positions corresponding to the convex portions 42a of the flow path forming portion 40, it is possible to precisely place the flow path forming portion 40 in the resin case 10 and to uniformly form the one-directional flowing portion 81 and the other-directional flowing portion 82.
Although a projecting height of the case-side convex portion 18 is low in this embodiment, since the height of the case-side convex portion 18 is similar to that of the rib 15, it is possible to prevent heat from transferring around the outer periphery of the resin case and to reduce a loss of radiation heat.

[INDUSTRIAL APPLICABILITY]

According to the present invention, vapor and high temperature hot water generated by a boiler can be used as the second fluid in addition to refrigerant, and the invention can be utilized in a water heater and a cooler.

Claims

A heat exchanger comprising a resin case forming a first flow path through which first fluid flows, and a pipe forming a second flow path through which second fluid flows, the pipe being placed in the first flow path, wherein
the first flow path is separated into a plurality of rows in the resin case,
the pipe is composed of a one-directional pipe portion through which the second fluid flows in a one direction, an other-directional pipe portion through which the second fluid flows in an other direction, and a bent portion connecting the one-directional pipe portion and the other-directional pipe portion to each other,
the heat exchanger also includes a flow path forming portion which separates the first flow path of the one row into a one-directional flowing portion formed around the other-directional pipe portion and an other-directional flowing portion formed around the one-directional pipe portion,
a flow path cross-sectional area of the one-directional flowing portion is made smaller toward a downstream side, and a flow path cross-sectional area of the other-directional flowing portion is mage greater toward the downstream side.
The heat exchanger according to claim 1, further comprising a lid which covers an opened end of the first flow path and which is fixed to the resin case, wherein the lid is provided with a convex portion on which the bent portion is placed.
The heat exchanger according to claim 2, wherein a seal portion is provided on a portion of the pipe projecting from the resin case, the lid includes a wall surface located on the opened end, and a pipe-penetrating portion projecting from the wall surface, and the seal portion and the pipe-penetrating portion are sealed.
The heat exchanger according to claim 2 or 3, wherein a one end of the flow path forming portion is opposed to the bent portion, and the lid is fixed to the resin case such that the lid is opposed to the opened end and an other end of the flow path forming portion.
The heat exchanger according to claim 4, wherein outer shapes of both ends of the one-directional flowing portion and the other-directional flowing portion are substantially semi-circular.
A water heater including the heat exchanger according to any one of claims 1 to 5.