JP2001059687A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakdown of a header pipe and a heat exchanger, in turn by enhancing the withstand pressure strength of the header pipe and to attain lessening of the weight of the header pipe and space-saving of the heat exchanger, in the heat exchanger, which is used for heat exchange of a refrigerant (carbon dioxide or the like) usable in a supercritical region and requires pressure resistance. SOLUTION: This heat exchanger has an inflow-side header pipe, an outflow- side header pipe, at least one serpentine tube making these header pipes communicating with each other and fins interposed between tubes. In the part of the header pipe 2, 3 where a tube insertion hole 6 is formed, the sidewall is deformed in the direction where a distance between the wall and the place of the header pipe where the stress of the pipe concentrates is made short. In this case, a dimension t1 in the radial direction (the radial direction of the header pipe in the part, where the tube insertion hole is formed) in the part where the stress concentrates is made smaller than the dimension t2 in the radial direction perpendicularly intersecting the above radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger requiring pressure resistance, such as a refrigeration cycle using carbon dioxide or the like as a refrigerant, and more particularly to a serpentine type heat exchanger.

[0002]

2. Description of the Related Art When carbon dioxide is used as a refrigerant, the pressure of the refrigerant in the refrigeration cycle is significantly higher than that of conventional chlorofluorocarbons and the like. From the point of view, the design must be changed, and as a heat exchanger that can withstand such a high pressure, a serpentine-type heat exchanger is expected to be promising according to studies by the inventors.

[0003] The most orthodox configuration of the servine-type heat exchanger is, as shown in Japanese Patent Application Laid-Open No. 10-206084, an inflow-side header pipe in which a refrigerant passage through which a refrigerant flows is formed. An outflow header pipe in which an outflow refrigerant passage is formed, a serpentine-shaped flat tube that is folded in a plurality of stages to communicate between the inflow header pipe and the outflow header pipe, and an opposing outer periphery of the folded tube And a corrugated fin interposed between the surfaces, a tube insertion hole is formed in the peripheral surface of the header pipe along the axial direction,
The end of the tube is inserted and joined to the tube insertion hole.

[0004]

However, the serpentine type heat exchanger has a structure excellent in pressure resistance because the tube is formed by extrusion molding and the tube itself has no joining margin. When used in a refrigeration cycle using carbon dioxide or the like as a refrigerant, there is a concern that the header pipe provided at the end of the tube may be damaged, apart from the tube.

More specifically, as shown in FIG. 7, when the header pipe 101 into which the end of the tube is inserted and joined is enlarged, the tube insertion hole 102 for inserting the tube insertion hole by the refrigerant pressure applied from the inside of the header pipe. , A stress F acting to push and expand the tube insertion hole 102 acts, and a portion of the side wall farthest from the tube insertion hole surrounded by a broken line in the figure (a portion opposite to the tube insertion hole).
At which the moment of force is maximized. For this reason, stress concentrates on the portion surrounded by the broken line of the header pipe 101, and in the worst case, this portion is deformed or broken, and accordingly, the tube insertion hole 102 is pushed out so as to avoid it. It has been confirmed by experiments that the tube joined here by brazing or the like is also torn.

To avoid such a situation, it is conceivable to make the header pipe sufficiently thick. However, the thicker the header, the larger the weight of the header pipe and hence the weight of the heat exchanger. This is contrary to the demand for weight reduction. In addition, the thicker the wall, the larger the header pipe, which is against the demand for space saving of the heat exchanger.

Therefore, in the present invention, in a heat exchanger which requires a pressure resistance for heat exchange of a refrigerant which can be used in a supercritical region such as carbon dioxide gas, the demand for weight reduction of the header pipe and the reduction of the header pipe are required. It is an object of the present invention to provide a heat exchanger in which the pressure resistance is increased while satisfying the requirement for space, and the header pipe is prevented from being damaged and hence the heat exchanger from being damaged.

[0008]

In order to achieve the above object, a heat exchanger according to the present invention is used for exchanging heat for a refrigerant usable in a supercritical region, and a refrigerant passage into which the refrigerant flows. Is formed, an outflow header pipe in which a refrigerant passage through which a refrigerant flows is formed, and at least one which is folded back in a plurality of stages and communicates between the inflow header pipe and the outflow header pipe. A tube having a serpentine tube and fins interposed between opposed outer peripheral surfaces of the folded tube, wherein a tube insertion hole for inserting the tube is formed in a peripheral surface of the header pipe; At least one of the side walls is deformed in a direction in which a distance from a portion where the tube insertion hole is formed to a portion where the stress of the header pipe is concentrated is shortened. Is characterized in that there (claim 1).

In this case, at least one of the header pipes has a radial dimension at a location where the stress of the header pipe is concentrated (a transverse dimension perpendicular to the axial direction of the refrigerant passage) in a radial direction orthogonal to the radial direction. In particular, when one tube insertion hole is formed in the header pipe, at least one of the header pipes is connected to a portion where the tube insertion hole is formed. In this case, the header pipe may be formed so that the radial dimension of the header pipe is smaller than the radial dimension orthogonal to the header pipe.

Therefore, since the distance between the tube insertion hole and the location where the stress is concentrated is shortened by deforming the side wall of the header pipe, the stress is concentrated at a location away from the tube insertion hole, but the stress is concentrated at that location. The moment of such a force can be reduced. That is,
The concentration of the stress itself is reduced by reducing the moment of the force applied to the portion where the stress is likely to concentrate, so that the pressure resistance of the header pipe is relatively increased as compared with the related art. In addition, since the distance from the part where the tube insertion hole is formed and where the stress of the header pipe is concentrated is shortened to increase the strength, the outer shape of the header pipe is reduced by the reduced distance. The size can be reduced, the space can be saved, and the inconvenience of increasing the weight of the header pipe is eliminated.

As a specific mode of shortening the distance between the portion where the tube insertion hole is formed and the portion where the stress is concentrated, a header pipe is formed in a cylindrical shape, and the portion where the tube insertion hole is formed is flattened. (Claim 4), a configuration in which the header pipe is formed in a tubular shape, and a portion where the tube insertion hole is formed is formed into a curved surface having a larger radius of curvature than other portions (Claim 5). And so on.

According to these specific constructions, the pressure receiving area for receiving the refrigerant pressure in the refrigerant passage of the header pipe can be reduced by shortening the distance from the portion where the stress is concentrated at the tube insertion hole. In addition, since the stress F for pushing and expanding the tube insertion hole is also reduced, FIG.
The total stress applied to the portion where the stress is concentrated (portion surrounded by the broken line in FIG. 7) can be reduced as compared with the conventional device shown in FIG.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a serpentine-type heat exchanger. This heat exchanger 1 is provided on one side and has an inlet side formed with a refrigerant passage that is open on the downstream side in the ventilation direction where the refrigerant flows in. An outlet header pipe 3 in which a header pipe 2 and a refrigerant passage arranged on the other side and open on the upstream side in the ventilation direction where the refrigerant flows out are formed.
And a tube 4 which communicates between the inflow side header pipe 2 and the outflow side header pipe 3 and is folded back to form a serpentine shape, and a fin 5 interposed between opposing outer peripheral surfaces of the tube. And is configured.

The tube 4 is formed by bending a flat tube formed by extrusion so as to form a large number of refrigerant passages in a serpentine shape, and is interposed between the outer peripheral surfaces of the tube 4. Fins 5
Uses corrugated fins. In addition, as shown in FIG.
The tube insertion hole 6 into which the opening end of the tube is inserted is formed in the longitudinal direction of the outer peripheral surface of the header pipe and according to the end shape of the tube 4, and flows through the tube 4 inserted into the tube insertion hole 6. Refrigerant passages 7 of the side header pipe 2 and the outflow side header pipe 3 communicate with each other. Here, the tube 4, the fins 5, the header pipe 2,
The tube 3 and the tube 4 are integrally joined by brazing or the like.

In this example, the same inflow header pipe 2 and the outflow header pipe 3 are used, and the characteristics of these header pipes 2 and 3 are enlarged by cutting at the location where the tube insertion hole 6 is provided. Explaining with reference to a cross-sectional view (FIG. 2B), a substantially half side wall of the header pipes 2 and 3 on the side where the tube insertion hole 6 is not formed is formed in an arc shape, and the tube insertion hole 6 is formed. A substantially half side wall on the side where it is located is formed flat, and a tube insertion hole 6 is formed substantially at the center of the flat portion 8.

Therefore, in the header pipes 2 and 3, the radial dimension (t1) of the header pipe at the portion where the tube insertion hole 6 is formed is smaller than the radial dimension (t2) perpendicular to the header pipe. (T1 <t2), the refrigerant passage 7 formed inside the header pipes 2 and 3 is formed to have a substantially semicircular cross section, and extends in the axial direction of the header pipes 2 and 3.

In order to form such header pipes 2 and 3, the material of the header pipe is forged into a rod shape so that the outer shape of the cross section becomes as shown in FIG. 2 (b), and thereafter, it is drilled from the axial direction. Even if the refrigerant passage 7 is formed, if the above-described shape of the refrigerant passage 7 is not well formed by drilling, the header pipes 2 and 3 are temporarily formed into a cylindrical shape, and then the header pipes are formed into diameters. The flat portion 8 may be formed by applying a force from a direction.

In the above configuration, the refrigerant pressure is uniformly applied to the inner surface of the header pipe by the high-pressure fluid passing through the refrigerant passage 7 of the header pipes 2 and 3. At this time, the stress is concentrated on a portion opposite to the tube insertion hole 6 (a portion surrounded by a broken line in FIG. 2B) by a force (F) for pushing and expanding the tube insertion hole 6. But the tube insertion hole 6
By flattening the portion where the tube insertion hole 6 is formed, the distance from the tube insertion hole 6 to the point where the stress is concentrated can be shortened, and the radial dimension (the refrigerant passage Dimensions perpendicular to the axial direction)
Is reduced, the moment of the force applied to the portion surrounded by the broken line can be reduced, and the stress concentrated on this portion can be reduced. In other words, since the flat portion 8 is formed, the side wall is deformed in a direction (inside) in a direction of shortening the distance from the portion where the tube insertion hole 6 is formed to the portion where the stress of the header pipe is concentrated. The radial dimension at the portion surrounded by the broken line is shortened, and the stress concentrated there can be reduced. For this reason, the strength of the header pipe is relatively increased as compared with the conventional header pipe in which the side wall is not deformed inward at the tube insertion hole 6, and a header pipe that is more durable than the conventional one is provided. Becomes possible.

Further, the radial dimension (t1) of the header pipe at the portion where the tube insertion hole 6 is formed is made smaller than the radial dimension (t2) orthogonal to the header pipe. Since the pressure receiving area for receiving the refrigerant pressure in the refrigerant passage 7 can be reduced and the portion where the tube insertion hole 6 is formed is flattened, the refrigerant pressure received from the inside of the flat portion 8 is smaller than that of the flat portion 8. Since it is applied almost vertically, it does not become a force for pushing and expanding the tube insertion hole 6, and the stress F for pushing and expanding the tube insertion hole 6 can be reduced as a whole. Since the distance from the tube insertion hole 6 is reduced and the force (F) applied to the tube insertion hole 6 is reduced, the moment of the force acting on the portion surrounded by the broken line can be reduced. , It is possible to reduce the stress concentrated on this portion.

Furthermore, since the radial size of the header pipes 2 and 3 is reduced at the portion where the tube insertion hole 6 is formed to increase the strength, the header is reduced by the reduced diameter. The space saving of the pipe, and consequently the space saving of the heat exchanger can be achieved, and the header pipe is not made thicker, so the weight of the header pipe increases. Absent.

FIG. 3 shows a conventional cylindrical header pipe in which the header pipe is formed in a circular cross section (FIG. 3A), and a header pipe of the present invention in which the portion where the tube insertion hole 6 is formed is flattened (FIG. 3A). 3 (b)) shows a simulation result of analyzing the stress distribution. In this simulation, the outer diameter of the conventional header pipe was 12 mm, the diameter of the refrigerant passage 7 was 6 mm, the thickness of the header pipe was 3 mm, and in the header pipe of the present invention, the tube was inserted into the conventional header pipe. A flat portion 8 is formed by crushing the portion where the hole 6 is formed toward the center by 2 mm, and a uniform portion corresponding to the pressure near the low pressure line of the refrigeration cycle using carbon dioxide from the inside is used. Pressure is being applied.

Here, in the figure, when the stress H is applied to a portion H of 1.0 or more, A is a portion where a stress of 0.0 to 0.1 is applied, and B is a portion where a stress of 0.1 to 0.1 is applied. A portion where a stress of 0.2 is applied, C is a portion where a stress of 0.2 to 0.3 is applied, D is a portion where a stress of 0.3 to 0.4 is applied, and E is A portion where a stress of 0.4 to 0.6 is applied, F is a portion where a stress of 0.6 to 0.8 is applied,
G indicates a portion where a stress of 0.8 to 1.0 is applied.

As is apparent from the simulation results, the flat portion 8 is formed as in the present invention, and the radial dimension (t1) of the header pipe at the portion where the tube insertion hole 6 is formed is orthogonal to this. When the diameter in the radial direction (t2) is smaller than that in the conventional header pipe, the diameter in the radial direction is uniform everywhere.
Although the stress concentrates on the opposite side, the stress concentrated on this part as a whole is small, and it can be seen that the strength is relatively increased.

In the above-described configuration, the radial dimension (t) of the header pipe at the portion where the tube insertion hole 6 is formed is shown.
As a mode in which 1) is made smaller than the radial dimension (t2) perpendicular to this, a case where the portion where the tube insertion hole 6 is formed is formed flat is shown.
If <t2, the same function and effect can be achieved, and therefore, as shown in FIG.
The portion where the tube insertion hole is formed may be formed on a curved surface (curved deformation portion 9) having a larger radius of curvature than the other portions.

In such a configuration, the pressure receiving area of the refrigerant passage 7 of the header pipes 2 and 3 can be reduced, and
Since the distance between the tube insertion hole 6 and the portion where the stress is concentrated most (the portion surrounded by the broken line) can be reduced, and since the radius of curvature at the portion where the tube insertion hole is formed is large, the tube insertion hole 6 can be reduced. Is also reduced, the stress concentrated on the portion surrounded by the broken line can be made smaller than in the conventional art, and the strength can be relatively increased. Further, since the side wall is deformed toward the portion where the stress is concentrated at the portion where the tube insertion hole 6 is formed (to reduce the distance from the portion where the stress is concentrated), the header pipes 2 and 3 are pulled. As a result, the space for the heat exchanger can be saved, and the weight of the header pipe does not increase.

In the above example, an example is shown in which one tube insertion hole is formed in the header pipe. However, even when a plurality of tube insertion holes are formed, the relative strength of the header pipe is increased by utilizing the same technical idea. Can be achieved.

For example, the header pipe used in the heat exchanger shown in FIG. 5 will be described. In the example of this heat exchanger, one inflow side header pipe 11 arranged substantially at the center of the upper part of the core body, and the core body A pair of outflow header pipes 12 and 13 arranged at both lower ends of the tub, a first serpentine tube 14 communicating the inflow header pipe 11 with one of the outflow header pipes 12, and the inflow header It is composed of at least a serpentine-shaped second tube 15 that communicates the pipe 11 with the other outflow header pipe 13, and a corrugated fin 16 interposed between opposing outer peripheral surfaces of the tube. Here, outflow side header pipes 12, 13 and tubes 14, 1
5 is the same as in the above configuration example, but the connection between the inflow header pipe 11 and the tubes 14 and 15 is as shown in FIG.

That is, the inflow side header pipe 11 is oriented with respect to a plane passing through the center axis thereof (a vertical plane passing through the center axis when the header pipe is provided horizontally at the upper center as shown in FIG. 5). A first tube insertion hole 17 into which one end of the first tube 14 is inserted and a second tube insertion hole 18 into which one end of the second tube 15 is inserted extend symmetrically along the axial direction of the header pipe 11. Has been established.

In such a header pipe 11,
Due to the stress applied to each tube insertion hole 17, 18
And the first and second tube insertion holes 17 and 18 are located on the side opposite to the side where the second tube insertion hole is provided.
Since the stress concentrates on a portion (the portion surrounded by a broken line in FIG. 6B) that is at an equal distance from, the stress concentrates on the portion where the first and second tube insertion holes 17 and 18 are formed. The side wall is deformed in a direction to shorten the distance from the portion surrounded by the broken line, and the radial dimension (t1) at the portion surrounded by the broken line where the stress concentrates is changed to the radial dimension (t1) orthogonal to this.
It is formed smaller than 2). In this example, a curved deformation portion 19 having a large radius of curvature similar to the configuration of FIG. 4 is formed on the side opposite to the portion surrounded by a broken line where stress is concentrated, and two tube insertion holes 17 and 18 are formed in this portion. Like that.

Also in such a configuration, the pressure receiving area of the refrigerant passage 7 of the header pipe 11 can be reduced, and the distance between the tube insertion hole 6 and the portion where the stress is most concentrated (the portion surrounded by the broken line) is reduced. In addition, since the radius of curvature at the portion where the tube insertion holes 17 and 18 are formed is large, the force F for pushing and expanding the tube insertion holes 17 and 18 also becomes small, and concentrates on the portion surrounded by the broken line. The stress can be made smaller than before, and the strength can be relatively increased. In addition, tube insertion holes 17, 1
Since the side wall is deformed toward the portion where the stress is concentrated at the portion where the stress 8 is formed (to reduce the distance from the portion where the stress is concentrated), the header pipe 11 and, hence, the heat exchanger 1 are deformed. And the weight of the header pipe does not increase.

In the above example, the radial dimension at the location where the stress is concentrated in all the header pipes is formed smaller than the radial dimension orthogonal thereto. It is needless to say that it is also possible to deal with only a part of the above as the above configuration. In the above-described example, the tube insertion hole is inserted into the header pipe by one.
In the case where one or two tube insertion holes are provided, even when a larger number of tube insertion holes are provided, the header pipe is formed so that the portion where the tube insertion hole is formed is closer to the portion where the stress of the header pipe is concentrated. By deforming the side wall, the strength of the header pipe can be increased.

[0032]

As described above, according to the present invention,
In a heat exchanger used for heat exchange of a refrigerant usable in a supercritical region, at least one of the header pipes connected by a serpentine-like tube is connected to the header pipe at a portion where a tube insertion hole is formed. The side wall is deformed in a direction to shorten the distance from the place where the stress is concentrated, in other words, the radial dimension at the place where the stress of the header pipe is concentrated is smaller than the radial dimension orthogonal to this. In particular, if the tube insertion hole is
If it is formed, at least one of the header pipes communicating with the serpentine-like tube is formed such that the radial dimension of the tube at the portion where the tube insertion hole is formed is smaller than the radial dimension orthogonal to this. Since the size is reduced, it is possible to increase the pressure resistance without increasing the weight of the header pipe, and to prevent the header pipe from being damaged, and hence the heat exchanger from being damaged. In addition, since the side wall of the header pipe is deformed in a direction in which the distance from the location where the stress of the header pipe is concentrated at the portion where the tube insertion hole is formed is reduced, a space saving is achieved by the deformed portion. Can also.

Further, in order to shorten the distance between the portion where the tube insertion hole is formed and the portion where the stress is concentrated, the portion where the tube insertion hole is formed is formed flat or the tube insertion hole is formed. If the portion to be formed is formed into a curved surface having a larger radius of curvature than the other portion, the portion where the stress is concentrated compared to the conventional header pipe where the radial dimension is not reduced at the tube insertion hole portion To reduce the total stress applied to
The strength of the header pipe can be effectively increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a serpentine heat exchanger according to the present invention. FIG. 1 (a) is a front view thereof, and FIG. 1 (b) is a plan view thereof.

FIG. 2 shows a header pipe used in the serpentine heat exchanger of FIG. 1, and FIG. 2 (a) is a view seen from the side so that a tube insertion hole for inserting a tube can be seen; FIG. 2B is a cross-sectional view taken along line II of FIG. 2A.

FIG. 3 is an analysis result showing a distribution of stress, and FIG. 3 (a) is an analysis result when the center axis of the refrigerant flow path of the header pipe coincides with the center axis of the header pipe; FIG.
(B) is an analysis result when the center axis of the refrigerant flow path of the header pipe is shifted toward the tube insertion hole with respect to the center axis of the header pipe.

FIG. 4 shows another example of the configuration of the header pipe used in the serpentine heat exchanger of FIG. 1, and FIG.
Fig. 4B is a diagram viewed from the side so that a tube insertion hole for inserting a tube can be seen, and Fig. 4B is a view taken along the line II-II in Fig. 4A.
It is sectional drawing cut | disconnected by the line.

5 is a view showing another example of the serpentine heat exchanger according to the present invention, wherein FIG. 5 (a) is a front view thereof, and FIG. 5 (b) is a plan view thereof. .

6 shows a header pipe used in the serpentine heat exchanger of FIG. 5, and FIG. 6 (a) is a view seen from the side so that a tube insertion hole for inserting a tube can be seen; FIG. 6B is a cross-sectional view taken along the line III-III of FIG.

FIG. 7 shows a header pipe used in a conventional serpentine heat exchanger, and FIG. 7 (a) is a view seen from the side so that a tube insertion hole for inserting a tube can be seen. FIG. 7B is a cross-sectional view taken along the line IV-IV of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat exchanger 2, 11 Inflow header pipe 3, 12, 13 Outflow header pipe 4 Tube 5, 16 Fin 6, 17, 18 Tube insertion hole 7 Refrigerant passage 8 Flat part 9, 19 Curved deformation part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Kawamura 39 Higashihara, Chiyo, Odai-gun, Osato-gun, Saitama Prefecture F term (reference) 3L065 CA17 3L103 AA01 AA05 AA11 AA44 BB33 CC18 CC30 DD04 DD34 DD42 DD63

Claims (5)

[Claims] 1. An inflow header pipe, which is used for exchanging heat of a refrigerant usable in a supercritical region and in which a refrigerant passage through which the refrigerant flows is formed, and an outlet in which a refrigerant passage through which the refrigerant flows is formed. Side header pipe, at least one serpentine-shaped tube that is folded back in a plurality of stages and communicates between the inflow-side header pipe and the outflow-side header pipe, and is interposed between opposed outer peripheral surfaces of the folded-back tube. And a tube insertion hole for inserting the tube on the peripheral surface of the header pipe, wherein at least one of the header pipes has the tube insertion hole. A heat exchanger, wherein a side wall is deformed in a direction to shorten a distance from a portion where a stress of the header pipe is concentrated at a portion. 2. At least one of said header pipes comprises:
The heat exchanger according to claim 1, wherein a radial dimension of the header pipe at a location where stress is concentrated is smaller than a radial dimension orthogonal thereto. 3. At least one of said header pipes comprises:
The heat exchanger according to claim 1, wherein a radial dimension of the header pipe is smaller than a radial dimension orthogonal to the header pipe at a portion where the tube insertion hole is formed. 4. The heat exchanger according to claim 1, wherein the header pipe is formed in a cylindrical shape, and a portion where the tube insertion hole is formed is formed flat. 5. The header pipe according to claim 1, wherein a portion where the tube insertion hole is formed is formed into a curved surface having a larger radius of curvature than other portions. 4. The heat exchanger according to 2, 3 or 4.