JP2012112579A - Flat tube for heat exchanger and heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger in which heat exchange efficiency is improved by increasing a surface area by grooves formed on a surface of a flat tube and generating a turbulent flow, and which has an excellent bondability with a fin.SOLUTION: The plurality of grooves 14 are formed extending while meandering along a flat surface in the longitudinal direction, projection parts are formed at a part of an internal flow path 13 by the grooves 14, and a plane part excluding the grooves 14 on the flat surface is formed so as to have an occupancy ratio to the flat surface 40% or more and 95% or less in any width direction.

Description

  The present invention relates to a heat exchanger flat tube and a heat exchanger formed by bonding fins to the surface of the flat tube, and more particularly to a flat tube having a groove formed on the surface and a heat exchanger.

  As a heat exchanger used for an air conditioner for automobiles or buildings, a heat exchanger in which a fin member such as a corrugated fin is brazed to a flat tube formed by extrusion molding of an aluminum alloy is known. There exist a thing of patent document 1 and patent document 2 as such a heat exchanger.

In the heat exchanger described in Patent Document 1, flat tubes are provided in parallel between a pair of headers, and corrugated fins are joined between the flat tubes. The corrugated fin is formed by bending a thin aluminum alloy plate in a wavy shape by pressing and is brazed to the surface of both flat tubes so as to communicate between two adjacent flat tubes. Thus, a large number of flow paths are formed in a direction orthogonal to the longitudinal direction of the flat tube. And it is the structure heat-exchanged between the fluid which distribute | circulates the inside of a flat tube, and the fluid which distribute | circulates the inside of the flow path formed with a corrugated fin.
In addition, a plurality of grooves are formed on both sides of each flat tube along the width direction or in an oblique direction intersecting the width direction, and the corrugated fin has an uneven surface due to the grooves. It is brazed.

  Also in the heat exchanger of patent document 2, the groove | channel along the diagonal direction which cross | intersects the width direction is formed in the surface of the flat tube, and the corrugated fin is brazed on the groove | channel.

JP 2004-3787 A JP 2008-101820 A

  In each of the heat exchangers described in these patent documents, a groove is formed on the surface of the flat tube so as to increase the surface area of the flat tube and generate turbulence to increase the heat exchange efficiency. Since the surface of the tube is also a joint surface with the fin to be brazed thereon, the fin and the tube are not brought into contact with each other by the groove, and the joint is likely to be poor.

  The present invention has been made in view of the above circumstances, and the groove formed on the surface of the flat tube increases the surface area and generates turbulent flow to increase heat exchange efficiency, and also has good fin bondability. The purpose is to provide an exchanger.

  The flat tube for a heat exchanger of the present invention is characterized in that a plurality of grooves extending while meandering along the longitudinal direction are formed on the flat surface.

  The fin joined to the flat tube is bent while being folded in a wave shape, and the folded portion is brazed along the width direction of the flat tube. In this case, if the longitudinal direction of the groove on the tube surface and the folded portion of the fin are arranged so as to partially overlap in the longitudinal direction of the groove, the fin and the tube do not contact with each other, resulting in poor bonding. On the other hand, in the flat tube of the present invention, since the groove is formed along the longitudinal direction of the flat tube, the folded portion of the fin brazed on the flat tube is arranged in a direction intersecting the groove. . Accordingly, the folded portions of the fins are not disposed so as to overlap in the longitudinal direction of the groove, and the bonding can be reliably performed without insufficient brazing.

  In the flat tube for a heat exchanger according to the present invention, a protrusion is formed in a part of the internal flow path by the groove, and the flat portion excluding the groove in the flat surface has any width occupied by the width of the flat surface. It may be formed so as to be 40% or more and 95% or less in the direction.

  If the plane portion occupies 40% or more in any width direction, a sufficient bonding area can be secured for the folded portion of the fins arranged along the width direction. If the occupation ratio of the planar portion is less than 40%, the refrigerant flow path becomes narrow, the pressure loss increases, and the heat exchange efficiency decreases. On the other hand, the protrusion formed on the internal flow path side by the formation of this groove has the effect of increasing the heat exchange efficiency by generating turbulent flow in the fluid flowing through the internal flow path. If it exceeds 95%, the effect of turbulent flow in the internal flow path is small, and the heat exchange efficiency is low. For this reason, the occupation ratio of the plane portion is preferably 40% or more and 95% or less.

  In the flat tube for a heat exchanger of the present invention, the front and back surfaces at both ends in the longitudinal direction are preferably flat surfaces not having the groove.

  Both ends of the flat tube are parts to be joined to the header of the heat exchanger. If grooves are formed at both ends, it is necessary to join the grooves in a filled state. By using a flat surface, it is possible to join the header without any gap.

  The heat exchanger of the present invention includes the flat tube, and a fin that is bent while being folded in a wave shape, and the folded portion is brazed to the surface of the flat tube along the width direction. To do.

  According to the present invention, the heat exchange efficiency is enhanced by the grooves formed on the flat tube surface, and the grooves are formed along the longitudinal direction, so that the folded portions of the fins are arranged in the longitudinal direction of the grooves. There is no, and it can join reliably and bondability is also favorable.

It is a disassembled perspective view which abbreviate | omitted a part of heat exchanger of embodiment of this invention. It is a whole front view of the heat exchanger of an embodiment. It is a top view of the flat tube used for the heat exchanger of an embodiment. FIG. 4 is an enlarged cross-sectional view of the vicinity of a joint portion with a fin along the line XX in FIG. 3. FIG. 4 is an enlarged cross-sectional view of the vicinity of a joint portion with a fin along the line YY in FIG. 3. It is a top view which shows the relationship between the plane part and groove | channel in the junction part of a flat tube and a fin. It is a perspective view explaining the manufacturing method of a flat tube. It is a schematic diagram of the test apparatus used in order to perform the heat exchange test of an Example. It is a graph which shows the relationship between the plane part occupation rate and temperature efficiency in the junction part of a flat tube.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIGS. 1 and 2, the heat exchanger 1 includes a plurality of flat tubes 2 through which a fluid as a heat medium passes, and fins 3 that contact the outer surface of the flat tubes 2 to dissipate heat. The fluid is distributed and supplied to each flat tube 2, and a set of headers 4 and 5 for reassembling the fluid passing through each flat tube is provided. These flat tubes 2, fins 3, and headers 4 and 5 are made of an aluminum alloy, and the flat tubes 2 are arranged in the longitudinal direction of the headers 4 and 5 between the headers 4 and 5 arranged in parallel in the vertical direction. The flat tubes 2 are arranged in parallel with each other in the vertical direction and are fixed to the headers 4 and 5 so that both ends of the flat tubes 2 communicate with the headers 4 and 5, respectively. The fins 3 are arranged between the two.

  Each flat tube 2 has a flat shape with a small height relative to the width dimension, and a plurality of partition walls 12 are formed at intervals in the width direction inside the peripheral wall 11 forming the outer periphery thereof. This is a so-called multi-hole tube in a state where the inner space of the peripheral wall 11 is divided into a plurality of internal flow paths 13 parallel to each other. In addition, a plurality of grooves 14 extending while meandering along the longitudinal direction are formed in the flat surface 2a of the flat tube 2 as shown in FIG. The flat tube 2 is formed by extrusion molding, and the groove 14 is also continuously formed while being pressed by a roll 16 having a convex portion 15 for groove formation at the time of extrusion molding as shown in FIG.

  Since the groove 14 is formed by pressing the peripheral wall 11 of the flat tube 2 from the outside in this way, the portion where the groove 14 is formed is outside the peripheral wall 11 as shown in FIGS. Although the surface is recessed in a concave shape, the inner surface of the peripheral wall 11 is formed so that a part of the peripheral wall 11 protrudes inward so as to narrow the internal flow path 14, and a part of the partition wall 12 is also pressed in the surface direction. It is buckled and bent.

  Various dimensions of the flat tube 2 are not particularly limited. For example, the width is 15 mm, the height is 1.5 mm, the wall thickness is 0.3 mm, and the number of the internal flow paths 13 is 20. The groove 14 has a width of 0.5 mm and a depth of 0.5 mm. However, as will be described later, in order to ensure a good bonding rate with the fin 3, the plane portion remaining other than the groove 14 has an occupation ratio with respect to the width of the flat surface 2a of 40% to 95% in any width direction. It is important to be formed so that

  The flat surfaces 17 are formed by crushing the grooves 14 on the front and back surfaces of both ends of each flat tube 2. On the other hand, the both ends of each flat tube 2 are inserted into the walls of the headers 4 and 5. A rectangular hole 18 is formed, and both ends of the flat tube 2 are inserted into the hole 18 and fixed by brazing.

  The fin 3 is formed by bending the strip while bending the strip a plurality of times, so that the folded portions 21 of mountain folds or valley folds are formed in a continuous wave shape through the flat portions 22, and each folded portion 21 is formed into a flat tube 2. Are fixed to the flat surface 2a by brazing. In this case, each folded-back portion 21 of the fin 3 is disposed along the width direction of the flat tube 2 and is fixed so as to intersect the groove 14 formed on the surface of the flat tube 2.

  The fin 3, the flat tube 2, and the headers 4, 5 are brazed with the fin 3 having a brazing material clad beforehand on both sides of the core material, while the flat tube 2 has a brazing material on its flat surface 2 a. The brazing material is melted and solidified by heating in a state where these are combined, and the contact portions of the fin 3, the flat tube 2, and the headers 4 and 5 are integrated. 4 and 5 indicates a solidified brazing material.

  In the heat exchanger 1 configured as described above, the fin 3 has the folded portion 21 disposed along the width direction of the flat tube 2, so that the brazed portion A between the flat surface 2 a is a flat tube. 2 along the width direction. On the other hand, since the groove 14 on the surface of the flat tube 2 is formed along the longitudinal direction, the brazed portion A and the groove 14 are arranged in an intersecting state. Further, since the flat portion other than the groove 14 occupies 40% or more of the width of the flat tube 2, at least 40% or more of the brazed portion A is bonded to the flat portion and the fin 3. Thus, it is possible to obtain a strong joint.

  In FIG.3 and FIG.6, the brazing part A of the flat tube 2 and the fin 3 is shown with the chain line (only one place is shown in FIG. 3). In FIG. 6, a plane portion other than the groove 14 is hatched in the brazed portion A, and the hatched area is 40% or more of the entire area of the brazed portion A.

  In addition, since the groove 14 is formed in the flat surface 2a, the air flowing in the direction orthogonal to the groove 14 is disturbed by the unevenness of the groove 14, so that the air flow with the outer surface of the flat tube 2 is reduced. Heat transfer between is promoted. On the other hand, in the internal flow path 13 of the flat tube 2, the protruding portion 23 is formed on a part of the peripheral wall 11 due to the formation of the groove 14, and the partition wall 12 is also buckled. For this reason, irregularities are also formed on the inner peripheral surface of the internal flow path 13 and a turbulent flow is generated, so that heat transfer between the fluid and the wall is also promoted, and heat exchange efficiency is improved.

  In order to ensure the joining by brazing as described above, the occupation ratio of the flat portion in the flat surface 2a is preferably large. However, in order to improve the heat exchange efficiency by this turbulent flow, the unevenness by the groove 14 is large. Therefore, the occupation ratio of the planar portion is preferably 40% or more and 95% or less.

  Thus, the heat exchanger 1 is configured such that the flat portion remaining due to the formation of the groove 14 is formed with an occupation ratio of 40% or more and 95% or less with respect to the width of the flat tube 2. 3 are joined to each other with a sufficient joint area, and heat is quickly transferred between them, and turbulence is generated on the inner flow path 13 of the flat tube 2 and the outer surface of the flat tube 2 to promote heat transfer. , Heat exchange efficiency can be increased.

  A flat tube having a width of 15 mm, a height of 1.5 mm, and 20 internal flow paths is produced by extrusion molding of an aluminum alloy, and the flat surface is left flat without processing grooves. A sinusoidal groove extending in a meandering direction was formed in parallel. In that case, by changing the width and number of each groove, a plurality of types from 35% occupancy ratio of the plane portion other than the groove to 100% having no groove were prepared, and the heat exchange amount was measured.

  In the measurement of the heat exchange amount, as shown in FIG. 8, a heat exchanger 32 was installed in the wind tunnel 31, and the total amount of air in the wind tunnel 31 was controlled to pass through the fins in the heat exchanger 32. . Further, as a fluid circulated in the flat tube, a refrigerant passing through the compressor 33 and the regulator 34 was supplied, while air was circulated through the fins by a sirocco fan 36 at a wind speed of 10 m / sec. And about the refrigerant | coolant which distribute | circulates the inside of a flat tube, header inlet temperature (T1) and header outlet temperature (T2) are measured on conditions with constant pressure, and fin inflow temperature (T3) of the air which distribute | circulates a fin and fin are measured. The temperature after passing (T4) was measured.

From these measurement results, the temperature efficiency η = (T1−T2) / (T1−T3) was calculated, and the relationship with the occupancy ratio of the planar portion remaining by the grooves was examined.
The results are shown as a graph in FIG.

  As shown in FIG. 9, the temperature efficiency η reaches its maximum value when the occupation ratio of the plane portion remaining by the groove is less than 80%, and the temperature efficiency η is lower or higher than that. As a result, it was found that when the occupation ratio is 40% or more and 95% or less, the temperature efficiency η can be 40% or more. In addition, no bonding failure was observed at the brazed portion.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, although the fin has a configuration in which the V-shaped folded portion of the mountain fold and the valley fold is made continuous in the plane portion, the folded portion is bent in a crank shape to form a shape in which a plurality of planar portions are made continuous, You may make it braze the flat part formed in the crank-shaped folding | turning part to a flat tube.

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Flat tube 2a Flat surface 3 Fin 4, 5 Header 11 Peripheral wall 12 Partition wall 13 Internal flow path 14 Groove 15 Flat part 16 Hole 21 Folding part 22 Flat part 23 Projection part

Claims (4)

  A flat tube for a heat exchanger, wherein a plurality of grooves extending while meandering along a longitudinal direction are formed on a flat plane.   A protrusion is formed in a part of the internal flow path by the groove, and the flat portion excluding the groove in the flat surface has an occupation ratio with respect to the width of the flat surface of 40% or more and 95% or less in any width direction. The flat tube for a heat exchanger according to claim 1, wherein the flat tube is formed as follows.   The flat tube for a heat exchanger according to claim 1 or 2, wherein the front and back surfaces of both end portions in the longitudinal direction are flat surfaces not having the groove.   The flat tube for a heat exchanger according to any one of claims 1 to 3, and a fin that is bent while being folded back in a wave shape, and the folded portion is brazed to the surface of the flat tube along the width direction. A heat exchanger characterized by comprising.

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