JP2012093053A - Heat exchanger, method for manufacturing the same, refrigerator, and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger that reduces a contact thermal resistance between a heat transfer tube and a plate fin and improves the heat transfer performance, and to provide a method for manufacturing the same, a refrigerator, and an air conditioner.SOLUTION: The heat transfer tube 3 has an outer form whose cross section is substantially elliptical, and a major axis of the ellipse is arranged along an airflow direction. In the heat transfer tube, the tube has a first and second refrigerant channel 31a and 31b formed of two symmetric substantially-D-shaped through-holes, with a partition formed along a short axis direction of the ellipse therebetween. The thickness of major axis walls 3a and 3b facing the major axis of the ellipse is formed thicker than that of short axis walls 3c and 3d facing the short axis of the ellipse. The diameters of the first and second refrigerant channels 31a and 31b are expanded using a tube-expansion buret ball 100, and thereby the heat transfer tube is joined to the plate fin 2.

Description

  The present invention relates to a heat exchanger, a manufacturing method thereof, and a refrigerator and an air conditioner equipped with the heat exchanger.

A heat exchanger constituting a conventional refrigerator, air conditioner, or the like includes a so-called fin tube heat exchanger. The heat exchanger includes plate-like fins arranged at regular intervals and through which gas (air) flows, and a plurality of circular heat transfer tubes inserted perpendicular to the plate-like fins and through which refrigerant flows. It is comprised by.
Factors affecting the heat transfer performance of such a finned tube heat exchanger include the refrigerant side heat transfer coefficient between the refrigerant and the heat transfer tube, the contact heat transfer coefficient between the heat transfer tube and the plate fin, And the air side heat transfer coefficient between air and a plate-like fin is known.
The refrigerant side heat transfer coefficient between the refrigerant and the heat transfer tube is affected by the area in the heat transfer tube. The contact heat transfer coefficient between the heat transfer tube and the plate fin is affected by the contact state between the heat transfer tube and the plate fin. The air-side heat transfer coefficient between the air and the plate-like fins is affected by the pressure loss of the air flowing on the outer surface side.

Therefore, in order to reduce the area expansion in the heat transfer tube and the pressure loss on the air side, the following studies have been made.
For example, “The tube 2 is formed in an elliptical cross section, and the thickness T1 on and near the major axis a is thicker than the thickness T2 on and near the minor axis b. There has been proposed a “heat exchanger disposed in the direction of air flow” (see, for example, Patent Document 1).

  In addition, for example, a pipe provided with “a heat transfer tube bent into a U shape provided with a plurality of flow paths through which a working fluid flows inside a flat cross section” has been proposed (for example, see Patent Document 2).

  For example, “The heat transfer tube has a flat outer surface arranged along the air flow direction, and has a substantially oval outer shape in cross section, and has two symmetrical substantially symmetrical shapes with a partition wall in between. It has the 1st and 2nd refrigerant | coolant flow path which consists of a D-shaped through-hole, and it joins to the said plate-shaped fin by expanding the said 1st and 2nd refrigerant | coolant flow path using a tube expansion bullet ball. Has been proposed (see, for example, Patent Document 3).

  Also, for example, “a copper or copper alloy belt-shaped flat plate member is bent and formed so that one side end portion of the flat plate member abuts on the center portion of one surface, and the one side end portion is welded, and the other side end portion is It is bent so that it comes into contact with the center of the other surface, and the other end is welded to form a substantially glasses-like cross-sectional shape in the longitudinal direction. There has been proposed a “method of manufacturing a heat transfer tube characterized in that two medium passages are formed in the direction” (see, for example, Patent Document 4).

JP 2000-283777 A (Claim 1) Japanese Patent No. 40555449 (Claim 1) JP 2010-002093 A (Claim 1) Japanese Patent No. 3318096 (Claim 1)

However, the above-described prior art has the following problems.
In the heat exchanger described in Patent Document 1, since the heat transfer tube is formed in an elliptical shape having one through hole through which the refrigerant flows, the heat transfer tube is easily deformed by the pressure in the heat transfer tube. There was a problem that the adhesion with the plate-like fins deteriorated, the contact thermal resistance increased, and the contact heat transfer rate decreased.

  The heat exchanger described in Patent Document 2 has a problem in that the manufacturing cost increases because the manufacture of the heat transfer tubes and the attachment of the heat transfer tubes and the plate fins are performed by brazing in the furnace.

  In the heat exchangers described in Patent Documents 3 and 4, since the heat transfer tube has a flat shape and the outer surface in the vicinity of the inner partition wall is flat, the tube is expanded by inserting a tube expansion bullet into the heat transfer tube. When expanding the tube to be in close contact with the plate fins, the contact between the heat transfer tube and the plate fins deteriorates near the partition wall of the heat transfer tube and non-contact areas occur, increasing the contact thermal resistance and decreasing the contact heat transfer coefficient. There was a problem that.

  The present invention has been made to solve the above-described problems, and can reduce the contact thermal resistance between the heat transfer tube and the plate-like fin, and can improve the heat transfer performance. It aims at providing the manufacturing method of a heat exchanger, a refrigerator, and an air conditioner.

  A heat exchanger according to the present invention includes a plurality of plate-like fins arranged side by side at a predetermined interval, and a plurality of heat transfer tubes that are inserted in a direction orthogonal to the plate-like fins and through which a refrigerant flows, The heat transfer tube has an outer shape with a substantially elliptical cross section, the major axis of the ellipse is disposed along the air flow direction, and a partition formed along the minor axis direction of the ellipse is provided inside. In the meantime, the length of the ellipse is determined by the thickness of the short axis wall having the first and second refrigerant flow paths composed of two symmetrical substantially D-shaped through holes, and facing the short axis of the ellipse. A long wall facing the shaft is formed thick, and the first and second refrigerant channels are joined to the plate fins by expanding the diameter using a tube expansion bullet ball.

  The present invention can reduce the contact thermal resistance between the heat transfer tube and the plate-like fin, and can improve the heat transfer performance.

It is a front view which shows the outline | summary of the heat exchanger which concerns on Embodiment 1. FIG. 3 is a front view of the heat transfer tube according to Embodiment 1. FIG. It is explanatory drawing of the pipe expansion means of the heat exchanger tube of FIG. It is AA sectional drawing of the pipe expansion means of FIG. 6 is a front view of a heat transfer tube according to Embodiment 2. FIG. It is a figure which shows the relationship between the height of the protrusion after pipe expansion, and a heat exchange rate. 6 is a front view of a heat transfer tube according to Embodiment 3. FIG. It is a front view of the heat exchanger tube which concerns on Embodiment 4. It is a front view of the heat exchanger tube after being expanded according to Embodiment 4. FIG. 9 is a front view of a heat transfer tube according to a fifth embodiment. FIG. 10 is an enlarged view of a tube expansion bullet according to a sixth embodiment. It is explanatory drawing of the conventional fin tube type heat exchanger. It is a front view which shows the outline | summary of the heat exchanger which concerns on Embodiment 7. FIG. FIG. 10 is a front view showing an outline of a heat exchanger according to an eighth embodiment. It is a figure explaining the shape before and behind the expansion of the conventional heat exchanger tube.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the size relationship of each component may be different from the actual one.

Embodiment 1 FIG.
1 is a front view showing an outline of a heat exchanger according to Embodiment 1. FIG.
In FIG. 1, reference numeral 1 denotes a heat exchanger, a plurality of plate-like fins 2 arranged side by side at a predetermined interval, and a plate that is inserted in a direction orthogonal to the plate-like fins 2 and expanded (also referred to as diameter expansion). And a plurality of elliptical heat transfer tubes 3 joined to the fins 2. The plate-like fin 2 is made of a metal plate such as copper, copper alloy, aluminum, or aluminum alloy (the same applies to other embodiments), and is parallel to the air flow direction A and in the vertical direction (depth) in the figure. Direction) at a predetermined interval. The plate-like fins 2 are provided with an elliptical heat transfer tube 3 described later in a plurality of stages and in one or more rows in a direction perpendicular to the air flow direction A (vertical direction in the figure). Further, a plurality of slits 4 are provided in the plate-like fins 2 by cutting and raising between the elliptical heat transfer tubes 3 at each stage. The slit 4 is provided so that the side end of the slit 4 faces the air flow direction A, and by making the velocity boundary layer and the temperature boundary layer of the air flow thin at the side end, Heat transfer is promoted and the heat exchange capacity is increased.

Here, the deterioration of the adhesiveness and the occurrence of non-contact portions that occur when the heat transfer tube and the plate-like fin are brought into close contact with each other in the prior art will be described.
As shown in FIG. 15A, in the conventional heat exchanger, the heat transfer tube 3 is elongated along the air flow direction, the upper and lower outer surfaces 3a and 3b are flat, and the cross section is almost oval (or flat). It is formed in a circular shape. That is, the upper and lower outer surfaces 3a and 3b are flat, and the windward and leeward side surfaces 3c and 3d have a flat outer shape forming a semicircle. And inside the heat transfer tube 3, the 1st, 2nd refrigerant | coolant which consists of two symmetrical substantially D-shaped through-holes on both sides of the horizontal direction (henceforth width direction) of a figure on both sides of the partition wall 32 is carried out. The flow paths 31a and 31b are provided in parallel to the axial direction.
In such a conventional heat transfer tube 3, when the expanded burette ball (described later) is inserted into the first and second refrigerant flow paths 31 a and 31 b to expand the diameter so as to be in close contact with the plate-like fin 2, FIG. ), The flat surface is bent (indented) due to the diameter expansion in the vicinity of the partition wall 32 of the outer surfaces 3a and 3b of the heat transfer tube 3, and the adhesion between the heat transfer tube 3 and the plate-like fin 2 is deteriorated or not. Contact may occur. If the adhesion between the heat transfer tube 3 and the plate fin 2 deteriorates or a non-contact portion occurs, the contact heat resistance between the heat transfer tube 3 and the plate fin 2 increases and the contact heat transfer rate decreases. The heat transfer performance will be reduced.
Next, the heat transfer tube 3 of the present embodiment that suppresses the deterioration of the adhesion between the heat transfer tube 3 and the plate-like fin 2 and the generation of non-contact portions will be described.

FIG. 2 is a front view of the heat transfer tube according to the first embodiment.
As shown in FIG. 2, the heat transfer tube 3 has an outer shape with a substantially elliptical cross section, and the major axis of the ellipse is arranged along the air flow direction A. And in the inside of the heat exchanger tube 3, two symmetrical substantially D-shapes are formed on both sides in the left-right direction (hereinafter referred to as the width direction) in the figure with a partition wall 32 formed along the minor axis direction of the ellipse. 1st, 2nd refrigerant | coolant flow paths 31a and 31b which consist of a through-hole of a shape are provided in parallel with the axial direction. That is, the heat transfer tube 3 has an elliptical two-hole structure. The elliptical heat transfer tube 3 is made of a metal material such as copper, a copper alloy, aluminum, or an aluminum alloy, and is formed of an extruded material or a drawn material (the same applies to other embodiments).
Further, the short axis walls 3c and 3d facing the short axis of the ellipse are formed in a semicircular shape with an inner surface of radius r. Moreover, the long-axis walls 3a and 3b facing the long axis of the ellipse are formed so that the inner surfaces are linear (the boundary with the partition wall 32 has a slightly rounded shape). Further, the average thickness Tw2 of the inner straight portions of the long shaft walls 3a and 3b is formed thicker than the thickness Tw1 of the inner circumferential portion of the short shaft walls 3c and 3d. Here, the definition of the average thickness Tw2 is an average value of the total thickness of the long-axis walls 3a and 3b.

  Further, the average wall thickness Tw2 of the long-axis walls 3a and 3b is 1.04 to 1.25 times the wall thickness Tw1 of the short-axis walls 3c and 3d. This is because when the average wall thickness Tw2 of the long axis walls 3a and 3b is less than 1.04 of the wall thickness Tw1 of the short axis walls 3c and 3d, the outer surface of the heat transfer tube 3 in the vicinity of the partition wall 32 and the plate fin are in close contact with each other. This is because the heat exchange performance is lowered as a result. Further, when the average thickness Tw2 of the long axis walls 3a and 3b exceeds 1.25 times the thickness Tw1 of the short axis walls 3c and 3d, the outer surface of the heat transfer tube 3 and the plate shape at the short axis walls 3c and 3d portions. This is because the adhesiveness with the fins 2 is lowered, and as a result, the heat exchange performance is lowered. Therefore, the average wall thickness Tw2 of the long axis walls 3a and 3b in the present embodiment is set to 1.04 to 1.25 times the wall thickness Tw1 of the short axis wall.

  Although the average value of the wall thickness of the long axis walls 3a and 3b is used here, the present invention is not limited to this, and the wall thickness Tw1 of the short axis walls 3c and 3d is used to determine the length of the long axis walls 3a and 3b. It is sufficient if the wall thickness is formed thick. For example, the maximum value or the minimum value of the wall thickness of the long axis walls 3a and 3b may be made thicker than the wall thickness Tw1 of the short axis walls 3c and 3d.

  The wall thickness Tw3 of the partition wall 32 between the first and second refrigerant channels 31a and 31b is 1.0 to 1.4 times the wall thickness Tw1 of the short shaft walls 3c and 3d. This is because if the wall thickness Tw3 of the partition wall 32 is less than 1.0 of the wall thickness Tw1 of the short shaft walls 3c and 3d, the pressure resistance of the heat transfer tube 3 is lowered. When the wall thickness Tw3 of the partition wall 32 exceeds 1.4 times the wall thickness Tw1 of the short shaft walls 3c and 3d, the wall thickness of the partition wall 32 increases, and the outer surface of the heat transfer tube 3 near the partition wall 32 and the plate fins This is because the adhesiveness to 2 is lowered, and as a result, the heat exchange performance is lowered. Therefore, the wall thickness Tw3 of the partition wall 32 between the first and second refrigerant channels 31a and 31b in the present embodiment is set to 1.0 to 1.4 times the wall thickness Tw1 of the short shaft walls 3c and 3d. .

Next, the procedure for expanding the diameter of the first and second refrigerant flow paths 31a and 31b of the elliptical heat transfer tube 3 as described above, and the mounting to the mounting holes (long holes) 22 provided in the plate-like fins 2 are performed. An example of the procedure will be described.
As shown in FIG. 3, the fin collar portion 21 of the pressed plate-like fin 2 is provided with a long mounting hole 22, and each plate-like fin 2 has the fin collar portion 21 aligned in the same direction. It is held with a jig. Then, the above-described elliptical heat transfer tube 3 is inserted into the mounting hole 22 of each plate-like fin 2, and then the cross-sectional shape (substantially D-shaped) similar to the first and second refrigerant flow paths 31a and 31b. 4), a pair of expanded burette balls 100 made of a metal material such as cemented carbide is used to expand the first and second expanded burette balls 100 by a mechanical method or fluid pressure. Are pushed into the refrigerant flow paths 31a and 31b. Then, the first and second refrigerant flow paths 31a and 31b are simultaneously expanded in diameter, and the heat transfer tubes 3 are sequentially joined to the plate-like fins 2 and are fixed integrally.

As described above, in the present embodiment, the heat transfer tube 3 has an outer shape having a substantially elliptical cross section, and the average thickness of the long-axis walls 3a and 3b from the thickness Tw1 of the short-axis walls 3c and 3d. Tw2 is formed thick, and the first and second refrigerant flow paths 31a and 31b are joined to the plate-like fin 2 by being expanded in diameter using the tube expansion bullet ball 100. For this reason, the adhesiveness of the heat exchanger tube 3 and the plate-like fin 2 can be improved, and the contact thermal resistance between the heat exchanger tube 3 and the plate-like fin 2 can be reduced. Therefore, the contact heat transfer coefficient between the heat transfer tube 3 and the plate fin 2 can be improved, and the heat transfer performance can be improved.
Moreover, since the pressure resistance strength of the elliptical heat transfer tube 3 can be maintained by the partition wall 32 provided between the first and second refrigerant flow paths 31a and 31b, the elliptical heat transfer tube 3 is caused by the pressure in the heat transfer tube. It is possible to maintain good adhesion to the plate-like fins 2 without deformation. Therefore, a heat transfer tube having excellent heat transfer performance can be obtained.
Further, since the elliptical heat transfer tube 3 is expanded and joined to the plate-like fin 2, the assembly is much easier than brazing. Therefore, the manufacturing cost can be reduced.
Furthermore, each plate-like fin 2 can maintain a constant interval by the fin collar portion 21 in the same direction, and the adhesion between the elliptical heat-transfer tube 3 and the plate-like fin 2 is good. Even if the ellipse is made smaller and the diameter is reduced, a heat exchanger capable of reducing the ventilation resistance and increasing the heat exchange capacity can be obtained.

Embodiment 2. FIG.
FIG. 5 is a front view of the heat transfer tube according to the second embodiment.
As in the case of FIG. 2, the heat transfer tube 3 of the present embodiment is provided with first and second refrigerant flow paths 31a and 31b each having a substantially D-shaped through hole on both sides in the width direction. ing. A plurality of inner wall surfaces of the first and second refrigerant flow paths 31a and 31b each have a substantially quadrangular cross section with a predetermined height and interval (the tip has a slightly rounded shape). The protrusion 33 is provided in the axial direction.

Such an elliptical heat transfer tube 3 is inserted into the mounting hole 22 of the plate-like fin 2 in the above-described manner, and the first and second refrigerant flow paths 31a and 31b have the same cross-sectional shape as described above (substantially D-shaped). Is fixed to the plate-like fins 2 by expanding the diameter via each protrusion 33 using the expanded pipe burette ball 100.
As shown in FIG. 6, in the elliptical heat transfer tube 3 of the present embodiment, the higher the height h (projection length) of the ridge 33 after the tube expansion, the larger the contact area, and thus the higher the heat transfer coefficient. Become. However, if the height h of the ridge 33 after tube expansion exceeds 0.3 mm, the amount of increase in pressure loss is greater than the amount of increase in heat transfer coefficient, resulting in a decrease in heat exchange rate. On the other hand, when the height h of the ridge 33 after the tube expansion is less than 0.1 mm, the heat transfer coefficient is not improved. Therefore, in the elliptical heat transfer tube 3 of the present embodiment, it is desirable that the height h (projection length) of the ridge 33 after the tube expansion is about 0.1 to 0.3 mm. In addition, the cross-sectional shape of the protrusion 33 is not limited to a quadrangular shape, and may be an appropriate cross-sectional shape such as a triangular shape, a trapezoidal shape, or a semicircular shape.

  As described above, in the present embodiment, the same effect as in the first embodiment can be obtained, and a plurality of protrusions 33 are provided on the inner wall surfaces of the first and second refrigerant flow paths 31a and 31b. By providing, the contact area with the refrigerant increases and the height h of the protrusion 33 is about 0.1 to 0.3 mm, so that the heat transfer performance is further improved without increasing the pressure in the flow path. be able to.

Embodiment 3 FIG.
FIG. 7 is a front view of the heat transfer tube according to the third embodiment.
In the heat transfer tube 3 of the present embodiment, for example, the first refrigerant flow path 31a has the same shape as that of the first embodiment, and the second refrigerant flow path 31b has the same shape as that of the second embodiment. Of course, the reverse combination may be used.

  Such an elliptical heat transfer tube 3 is inserted into the mounting hole 22 of the plate-like fin 2 in the above-described manner, and the first refrigerant flow path 31a is used with the expanded burette ball 100 having a substantially D-shaped cross section. The diameter of the second refrigerant flow path 31b is expanded using the expanded burette ball 100 having a substantially D-shaped cross section, and is fixed to the plate fin 2. In this case, the height h (projection length) of the ridge 33 is desirably about 0.1 to 0.3 mm. In addition, the cross-sectional shape of the protrusion 33 is not limited to a quadrangular shape, and may be an appropriate cross-sectional shape such as a triangular shape, a trapezoidal shape, or a semicircular shape.

According to the present embodiment, the first and second refrigerant flow paths 31a and 31b are applied in combination with the first embodiment and the second embodiment, and substantially the same effects as those of the embodiments are obtained. Obtainable. That is, the adhesion between the heat transfer tube 3 and the plate-like fin 2 can be improved, and the contact thermal resistance between the heat transfer tube 3 and the plate-like fin 2 can be reduced. Therefore, the contact heat transfer coefficient between the heat transfer tube 3 and the plate fin 2 can be improved, and the heat transfer performance can be improved.
In addition, the elliptical heat transfer tube 3 is not deformed by the pressure in the heat transfer tube, and the adhesiveness with the plate-like fins 2 can be maintained well. Therefore, a heat transfer tube having excellent heat transfer performance can be obtained.
Further, since the elliptical heat transfer tube 3 is expanded and joined to the plate-like fin 2, the assembly is much easier than brazing. Therefore, the manufacturing cost can be reduced.
Furthermore, each plate-like fin 2 can maintain a constant interval by the fin collar portion 21 in the same direction, and the adhesion between the elliptical heat-transfer tube 3 and the plate-like fin 2 is good. Even if the ellipse is made smaller and the diameter is reduced, a heat exchanger capable of reducing the ventilation resistance and increasing the heat exchange capacity can be obtained.

  Moreover, when providing the some protrusion 33 on the inner wall surface of either one of the refrigerant flow paths 31b, the contact area with a refrigerant | coolant increases and the height h of the protrusion 33 is about 0.1-0.3 mm. Therefore, the heat transfer performance can be further improved without increasing the pressure in the flow path.

Embodiment 4 FIG.
FIG. 8 is a front view of a heat transfer tube according to the fourth embodiment.
FIG. 9 is a front view of the heat transfer tube after being expanded according to the fourth embodiment.
As in the case of FIG. 2, the heat transfer tube 3 of the present embodiment is provided with first and second refrigerant flow paths 31a and 31b each having a substantially D-shaped through hole on both sides in the width direction. ing. The inner wall surfaces of the first and second refrigerant flow paths 31a and 31b have a plurality of cross sections having a substantially square shape with a predetermined height and interval (the tip portion has a slightly rounded shape). The ridges 33, 34, and 35 are provided in the axial direction.

  The heights h2 and h3 of the ridges 34 and 35 provided on the inner wall surfaces of the long shaft walls 3a and 3b are formed higher than the height h1 of the ridge 33 provided on the inner wall surfaces of the short shaft walls 3c and 3d. Has been. Moreover, the height h3 of the protrusion 35 provided on the inner wall surface of the long-axis walls 3a and 3b is formed higher than the height h2 of the protrusion 34. That is, the heights of the plurality of protrusions 34 and 35 provided on the inner wall surfaces of the long-axis walls 3 a and 3 b are formed so as to be closer to the partition wall 32. The heights h1, h2, and h3 of the plurality of protrusions 33, 34, and 35 are provided at a required height so as to be in contact with the substantially D-shaped outer peripheral surface (see FIG. 4) of the expanded bullet ball 100. . The height h (projection length) of the protrusion 33 is preferably about 0.1 to 0.3 mm. In addition, the cross-sectional shape of the protrusions 33, 34, and 35 is not limited to a quadrangular shape, and may be an appropriate cross-sectional shape such as a triangular shape, a trapezoidal shape, or a semicircular shape.

Such an elliptical heat transfer tube 3 is inserted into the mounting hole 22 of the plate-like fin 2 in the manner described above, and the first and second refrigerant flow paths 31a and 31b are expanded in a D-shaped cross section. Is fixed to the plate-like fin 2 by expanding the diameter via the ridges 33, 34 and 35.
As shown in FIG. 9, in the heat transfer tube 3 of the present embodiment, the heights of the plurality of protrusions are formed so that the height is closer to the partition wall 32, so the first and second refrigerant flow paths are formed. The closer the partition wall 32 is, the larger the diameter expansion of 31a, 31b. Thereby, the adhesiveness of the outer surface of the heat exchanger tube 3 after pipe expansion and the plate-shaped fin 2 can be improved more, and the contact thermal resistance of the heat exchanger tube 3 and the plate-shaped fin 2 can be reduced. Therefore, the contact heat transfer coefficient between the heat transfer tube 3 and the plate fin 2 can be improved, and the heat transfer performance can be improved.

Embodiment 5 FIG.
FIG. 10 is a front view of a heat transfer tube according to the fifth embodiment.
In the heat transfer tube 3 of the present embodiment, for example, the first refrigerant flow path 31a has the same shape as that of the first embodiment, and the second refrigerant flow path 31b has the same shape as that of the fourth embodiment. Of course, the reverse combination may be used.

  Such an elliptical heat transfer tube 3 is inserted into the mounting hole 22 of the plate-like fin 2 in the above-described manner, and the first refrigerant flow path 31a is used with the expanded burette ball 100 having a substantially D-shaped cross section. The diameter of the second refrigerant flow path 31b is expanded using the expanded burette ball 100 having a substantially D-shaped cross section, and is fixed to the plate fin 2. In this case, the height h (projection length) of the ridge 33 is desirably about 0.1 to 0.3 mm. In addition, the cross-sectional shape of the protrusion 33 is not limited to a quadrangular shape, and may be an appropriate cross-sectional shape such as a triangular shape, a trapezoidal shape, or a semicircular shape.

According to the present embodiment, the first and second refrigerant flow paths 31a and 31b are applied by combining the first embodiment and the fourth embodiment, and substantially the same effects as those of these embodiments are obtained. Obtainable. That is, the adhesion between the heat transfer tube 3 and the plate-like fin 2 can be improved, and the contact thermal resistance between the heat transfer tube 3 and the plate-like fin 2 can be reduced. Therefore, the contact heat transfer coefficient between the heat transfer tube 3 and the plate fin 2 can be improved, and the heat transfer performance can be improved.
In addition, the elliptical heat transfer tube 3 is not deformed by the pressure in the heat transfer tube, and the adhesiveness with the plate-like fins 2 can be maintained well. Therefore, a heat transfer tube having excellent heat transfer performance can be obtained.
Further, since the elliptical heat transfer tube 3 is expanded and joined to the plate-like fin 2, the assembly is much easier than brazing. Therefore, the manufacturing cost can be reduced.
Furthermore, each plate-like fin 2 can maintain a constant interval by the fin collar portion 21 in the same direction, and the adhesion between the elliptical heat-transfer tube 3 and the plate-like fin 2 is good. Even if the ellipse is made smaller and the diameter is reduced, a heat exchanger capable of reducing the ventilation resistance and increasing the heat exchange capacity can be obtained.

  Moreover, when providing the some protrusion 33,34,35 in the inner wall face of any one refrigerant flow path 31b, the contact area with a refrigerant | coolant increases and height h of the protrusion 33 is 0.1-0.1. Since the thickness is about 0.3 mm, the heat transfer performance can be further improved without increasing the pressure in the flow path.

Embodiment 6 FIG.
FIG. 11 is an enlarged view of the expanded burette ball according to the sixth embodiment.
As shown in FIG. 11, the expanded burette ball 100 in which the first and second refrigerant flow paths 31a and 31b are used for expanding the diameter in the present embodiment is similar to the first and second refrigerant flow paths 31a and 31b. The cross-sectional shape (two symmetrical substantially D-shapes) is provided with a surface portion 101 in contact with the inner wall surfaces of the first and second refrigerant channels 31a and 31b. An insertion portion 102 having an outer diameter smaller than that of the surface portion 101 is provided on the distal end side. In the heat transfer tube 3 of the present embodiment, the diameter of the first and second refrigerant flow paths 31a and 31b is expanded using such a tube expansion bullet ball 100.
This expanded burette ball 100 is pushed into the first and second refrigerant flow paths 31a and 31b by a mechanical method or fluid pressure in the manner described above. At this time, by using the expanded burette ball 100 provided with the insertion portion 102, the expanded burette ball 100 can be easily positioned.
In this case, the axial length L of the surface portion 101 in contact with the inner wall surfaces of the first and second refrigerant flow paths 31 a and 31 b is 1.0 to 1.05 times the outer diameter D of the expanded burette ball 100. It is desirable to set the degree. This is because, when the axial length L of the surface portion 101 of the expanded bullet ball 100 is less than 1.0 times the outer diameter D, a step is formed on the outer surface of the heat transfer tube 3 by the rotational movement of the expanded bullet ball 100 when expanding. This is because the adhesion between the outer surface of the heat transfer tube 3 and the plate-like fins 2 is reduced. Further, when the axial length L of the surface portion 101 of the expanded burette ball 100 is 1.05 times or more of the outer diameter D, when the tube is expanded, the inner surface contact area between the expanded burette ball 100 and the heat transfer tube 3 increases. This is because the insertion force increases and the equipment cost increases.

Embodiment 7 FIG.
FIG. 12 is an explanatory view of a conventional fin tube heat exchanger, in which FIG. 12 (a) shows a heat transfer tube connection state on the front side, and FIG.
FIG. 13 is a front view showing an outline of a heat exchanger according to the seventh embodiment.
First, FIG. 12 will be described. A plurality of hairpin tubes 51 are produced by bending a heat transfer tube into a hairpin shape at a predetermined bending pitch at an intermediate portion thereof, and then the plurality of hairpin tubes 51 are spaced at a predetermined interval. Then, the plate-like fins 2 arranged parallel to each other are inserted from the back side. Then, the heat transfer tube is expanded by a mechanical method or a hydraulic expansion method to join the plate-like fins 2 and the heat transfer tube. Next, by using a plurality of return bend pipes 5 bent at a predetermined length and pitch, the return bend pipe 5 in which a wax ring is attached to the outer surface of the adjacent pipe end of the hairpin pipe 51 after the pipe expansion. The heat exchanger 50 is manufactured by brazing both the tubes with a burner.

  Next, the flow of the refrigerant in the conventional fin tube type heat exchanger 50 will be described. The refrigerant enters from the inlet pipe 52, flows out from the front side a to b on the back side, and flows in from the c through the hairpin pipe 51. Then, it flows out to d on the front side, passes through the return bend pipe 5 on the front side, and flows into the hairpin pipe 51 of the next stage from e. In this way, the refrigerant flows downward in the heat transfer tube as a → b → c → d → e → f → g... Finally, the refrigerant flows out from the lower outflow pipe 53. Meanwhile, heat exchange is performed with the air passing between the plate-like fins 2.

  On the other hand, the heat exchanger 1 of the present embodiment will be described with reference to the arrangement of the heat transfer tubes 3 on the right side of the drawing, as shown in FIG. 13 (note that the arrangement of the left and right heat transfer tubes 3 is partly in the middle) The heat transfer tubes 3 are bent at a predetermined bending pitch at the intermediate portion to produce a plurality of hairpin tubes 30, and then the plurality of hairpin tubes 30 are spaced at a predetermined interval. The plate-like fins 2 arranged parallel to each other are inserted from the back side. Then, as described above, the heat transfer tube 3 is expanded by a mechanical method or a hydraulic pressure expansion method, and the plate fin 2 and the heat transfer tube 3 are joined. Further, in the adjacent hairpin tube 30, two return bend tubes made of a metal material such as copper or copper alloy, aluminum or aluminum alloy are provided at the tube ends of the second heat transfer tube 3 and the third heat transfer tube 3. Connect in a cross shape with 5a and 5b. That is, the first refrigerant flow path 31a on the windward side of the second-stage heat transfer tube 3 and the second refrigerant flow path 31b on the leeward side of the third-stage heat transfer pipe 3 are connected by the return bend pipe 5a. The second refrigerant flow path 31b on the leeward side of the heat transfer pipe 3 at the stage and the first refrigerant flow path 31a on the upwind side of the heat transfer pipe 3 at the third stage are connected by a return bend pipe 5b. The third and fourth heat transfer tubes 3 (not shown) are configured as hairpin tubes 30, and the fourth and fifth heat transfer tubes (not shown) are connected in a cross shape with return bend tubes as described above. ing. In the heat exchanger 1 of the present embodiment, a plurality of refrigerant circuits are configured in the column direction in this way.

In the heat exchanger 1 of the present embodiment, the refrigerant flows into the first and second refrigerant flow paths 31a and 31b of the first stage heat transfer tube 3 separately and simultaneously. The refrigerant that has flowed into the first refrigerant flow path 31a of the first stage heat transfer pipe 3 flows out of the first refrigerant flow path 31a of the second stage heat transfer pipe 3 via the hairpin pipe 30, and is further a return bend pipe. It flows into the 2nd refrigerant | coolant flow path 31b of the 3rd-stage heat exchanger tube 3 via 5a. On the other hand, the refrigerant that has flowed into the second refrigerant flow path 31b of the first-stage heat transfer tube 3 flows out of the second refrigerant flow path 31b of the second-stage heat transfer pipe 3 via the hairpin tube 30, and then returns. It flows into the first refrigerant flow path 31a of the third-stage heat transfer tube 3 via the bend tube 5b.
Therefore, according to the heat exchanger 1 of the present embodiment, the refrigerant flows alternately in a cross shape by the return bend pipes 5a and 5b, so that the balance between the heat exchange capacity on the windward side and the heat exchange capacity on the leeward side is balanced. Therefore, a highly efficient heat exchanger can be obtained.

Embodiment 8 FIG.
FIG. 14 is a front view showing an outline of a heat exchanger according to the eighth embodiment.
In the present embodiment, only the ends of the second and third heat transfer tubes 3 in the adjacent hairpin tubes 30 are connected by the return bend tube 5c having one flow path so that the refrigerant is mixed. However, this is different from the seventh embodiment.
As a result, the mass ratio of the gas phase and the liquid phase at the outlet side of the plurality of refrigerant circuits of the heat transfer tubes becomes the same, and enters the refrigerant inlet portion of the next stage heat transfer tube, so that the heat exchange capacity on the windward side and the leeward side Therefore, a highly efficient heat exchanger can be obtained.

In addition, the heat exchanger 1 comprised using the heat exchanger tube 3 of each above-mentioned embodiment is a working fluid in the refrigeration cycle circuit formed by connecting a compressor, a condenser, a throttling device, and an evaporator sequentially by piping. As an HC single refrigerant or a mixed refrigerant containing HC, or a non-azeotropic mixed refrigerant consisting of R32, R410A, R407C, tetrafluoropropene and an HFC refrigerant having a boiling point lower than that of tetrafluoropropene or carbon dioxide Any refrigerant can be used as the condenser or evaporator.
Moreover, in the refrigerator provided with the said refrigerating cycle circuit, the heat exchanger 1 comprised using the heat exchanger tube 3 of each above embodiment can be used as at least one of the said evaporator and the said condenser.
Moreover, in the air conditioner provided with the said refrigerating cycle circuit, using the heat exchanger 1 comprised using the heat exchanger tube 3 of each above embodiment as at least one of the said evaporator and the said condenser. it can.

  1 heat exchanger, 2 plate fin, 3 heat transfer tube, 3a long shaft wall, 3b long shaft wall, 3c short shaft wall, 3d short shaft wall, 4 slit, 5 return bend tube, 5a return bend tube, 5b return bend Pipe, 5c return bend pipe, 21 fin collar part, 22 mounting hole, 30 hairpin pipe, 31a first refrigerant flow path, 31b second refrigerant flow path, 32 partition, 33 ridge, 34 ridge, 35 ridge , 100 Expanded burette ball, 101 surface portion, 102 insertion portion.

Claims (17)

A plurality of plate-like fins arranged side by side at a predetermined interval;
A plurality of heat transfer tubes that are inserted in a direction orthogonal to the plate-like fins and in which a refrigerant flows,
The heat transfer tube is
The cross section has a substantially elliptical outer shape, the long axis of the ellipse is arranged along the air flow direction,
Inside, there are first and second refrigerant flow paths consisting of two symmetrical substantially D-shaped through holes with a partition wall formed along the minor axis direction of the ellipse in between,
The wall thickness of the long axis wall opposed to the long axis of the ellipse is formed thicker than the wall thickness of the short axis wall facing the short axis of the ellipse,
The heat exchanger according to claim 1, wherein the first and second refrigerant flow paths are joined to the plate-like fins by being expanded in diameter using an expanded burette ball. The inner surface of the short shaft wall is formed in a semicircular shape,
The inner surface of the long wall is formed in a straight line,
The heat exchanger according to claim 1, wherein an average thickness of an inner straight line portion of the major axis wall is formed thicker than a thickness of an inner circumferential portion of the minor axis wall. The heat exchanger according to claim 2, wherein an average thickness of the long axis wall is 1.04 to 1.25 times a thickness of an inner circumferential portion of the short axis wall. 4. The heat exchanger according to claim 2, wherein a thickness of the partition wall is 1.0 to 1.4 times a thickness of an inner circumferential portion of the short shaft wall. 5. The heat exchange according to claim 1, wherein both of the first and second refrigerant channels have a plurality of ridges extending in an axial direction on an inner wall surface. 6. vessel. 5. The heat according to claim 1, wherein one of the first and second refrigerant channels has a plurality of protrusions extending in an axial direction on an inner wall surface. 6. Exchanger. The heat exchanger according to claim 5 or 6, wherein the height of the protrusion after the diameter expansion is 0.1 to 0.3 mm. 8. The height of the ridge provided on the inner wall surface of the long-axis wall is higher than the height of the ridge provided on the inner wall surface of the short-axis wall. The heat exchanger according to item 1. The heat exchanger according to any one of claims 5 to 8, wherein the plurality of protrusions provided on the inner wall surface of the long-axis wall have a height that is higher as the protrusion is closer. The heat transfer tube is
Using the expanded burette ball having a cross-sectional shape similar to the first and second refrigerant flow paths and having a surface portion in contact with the inner wall surface of the first and second refrigerant flow paths, the first and second The heat exchanger according to claim 1, wherein the refrigerant flow passage is joined to the plate-like fins by expanding the diameter of the refrigerant flow path. The heat exchanger according to claim 10, wherein the surface portion of the expanded burette ball has an axial length of 1.0 to 1.05 times the outer diameter. A plurality of refrigerant circuits are configured in the column direction using the heat transfer tubes whose intermediate portions are bent, and the refrigerant outlet portions of the first and second refrigerant channels of one adjacent heat transfer tube and the other The refrigerant inlet part of the said 1st and 2nd refrigerant flow path of a heat exchanger tube is connected in a cross shape with two return bend pipes, The any one of Claims 1-11 characterized by the above-mentioned. The described heat exchanger. A plurality of refrigerant circuits are configured in the column direction using the heat transfer tubes whose intermediate portions are bent, and the refrigerant outlet portions of the first and second refrigerant channels of one adjacent heat transfer tube and the other The refrigerant inlet part of the said 1st and 2nd refrigerant | coolant flow path of a heat exchanger tube is connected with one return bend pipe | tube so that a refrigerant | coolant may mix. The heat exchanger according to item 1. A heat exchanger manufacturing method comprising a plurality of plate-like fins arranged side by side at a predetermined interval, and a plurality of heat transfer tubes that are inserted in a direction orthogonal to the plate-like fins and in which a refrigerant flows,
The cross section has a substantially elliptical outer shape, and the inside includes a first partition formed of two symmetrical substantially D-shaped through holes with a partition wall formed along the minor axis direction of the ellipse in between. The heat transfer tube having a second refrigerant flow path and having a long axis wall opposed to the major axis of the ellipse thicker than a thickness of the minor axis wall facing the minor axis of the ellipse, In the mounting hole provided in the plate fin, the step of arranging the long axis of the ellipse along the air flow direction;
And a step of expanding the diameter of the first and second refrigerant channels of the heat transfer tube using a tube expansion bullet and joining the heat transfer tube to the plate fin. Method. The inner surface of the short shaft wall of the heat transfer tube is formed in a semicircular shape,
The inner surface of the long wall of the heat transfer tube is formed in a straight line,
15. The method of manufacturing a heat exchanger according to claim 14, wherein an average thickness of the inner straight line portion of the major axis wall is formed thicker than a thickness of the inner circumferential portion of the minor axis wall. A compressor, a condenser, a throttling device, and an evaporator are provided with a refrigeration cycle sequentially connected by piping, and a refrigerant is used as a working fluid, and the heat exchanger according to any one of claims 1 to 13 is used for the evaporation. And a refrigerator used as at least one of the condenser and the condenser. A compressor, a condenser, a throttling device, and an evaporator are provided with a refrigeration cycle sequentially connected by piping, and a refrigerant is used as a working fluid, and the heat exchanger according to any one of claims 1 to 13 is used for the evaporation. An air conditioner used as at least one of a condenser and the condenser.

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