EP4001821B1

EP4001821B1 - Heat-transfer tube and heat exchanger using the same

Info

Publication number: EP4001821B1
Application number: EP19937853.0A
Authority: EP
Inventors: Atsushi Morita; Tsuyoshi Maeda; Shin Nakamura; Akira YATSUYANAGI
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-07-18
Filing date: 2019-07-18
Publication date: 2024-03-06
Anticipated expiration: 2039-07-18
Also published as: CN114072627A; EP4001821A4; JP7262586B2; EP4001821A1; CN114072627B; JPWO2021009889A1; WO2021009889A1

Description

Technical Field

The present disclosure relates to a heat transfer tube through which heat exchange fluid flows, and also to a heat exchanger employing the heat transfer tube.

Background Art

In the past, it has been known that an elongated heat transfer tube is used as a heat transfer tube included in a heat exchanger. For example, Patent Literature 1 discloses an elongated heat transfer tube that is formed by bending a single plate a number of times. The heat transfer tube disclosed in Patent Literature 1 includes a flat plate-like base portion, two bent portions that are bent from both end portions of the base portion toward a central portion of the base portion, and two partition portions that are bent from end portions of the bent portions toward the base portion, the end portions facing the central portion of the base portion. This heat transfer tube further includes layered portions which are bent from end portions of the two partition portions toward the both end portions of the base portion, which overlap the base portion, and is jointed to the base portion with a brazing material.

Citation List

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2018-204919

Summary of Invention

Technical Problem

Recently, refrigeration cycle apparatuses using a hydrofluorocarbon (HFC)-based refrigerant are required to reduce the amount of the refrigerant to be filled, in view of the effect of refrigerant on the global environment. In order to reduce the amount of refrigerant to be filled, it is necessary to decrease the inner volume of a heat transfer tube in a heat exchanger included in the refrigeration cycle apparatus. In the elongated heat transfer tube that is formed by bending a single plate material as described in Patent Literature 1, it is necessary to increase the thickness of the single plate material, or decrease the length of the short axis or the length of the long axis of a section of the heat transfer tube, in order to decrease the inner volume of the heat transfer tube.
However, in the case where a single plate material having greater thickness is applied, the material cost is increased, and the weight of the heat transfer tube is also increased. When the length of the short axis or the length of the long axis of the section of the heat transfer tube is decreased, the heat-transfer area of the outer periphery of the heat transfer tube is decreased, thus deteriorating the heat exchange performance of the heat exchanger. When the heat exchange performance is deteriorated, electric power required for the compressor may be increased.
KR 100378055 describes a coolant tube of a heat exchanger having the features of the preamble of claim 1 and a processing method thereof.
WO 2019/026239 describes a heat exchanger in which each of a plurality of heat exchange members has a flat tube that extends from a first header tank to a second header tank, and a heat transfer plate that is integral with the flat tube along the longitudinal direction of the flat tube.
The present disclosure is applied to solve the problem of the above related art, and relates to an elongated heat transfer tube that is formed by bending a plate material, and that can reduce deterioration of a heat exchange performance, and also to a heat exchanger using the heat transfer tube.

Solution to Problem

A heat transfer tube of one embodiment of the present disclosure includes: an elongated main body including a plurality of flow passages formed by bending a single plate material a number of times; and an extension portion corresponding to at least one of the end portions of the single plate material, the extension portion being formed such that the at least one of the end portions of the single plate material extends from the main body in an elongated-section long-axis direction that is a direction along a long axis of a section of the main body. The extension portion is longer than a short axis of the section of the main body.
A heat exchanger of another embodiment of the present disclosure includes a plurality of heat transfer tubes each described above. The plurality of heat transfer tubes are arranged in parallel to each other along a direction perpendicular to a flow direction of first heat exchange fluid and a flow direction of second heat exchange fluid, the first heat exchange fluid flowing through the plurality of flow passages, the second heat exchange fluid flowing over an outer surface of the main body.

Advantageous Effects of Invention

According to the embodiments of the present disclosure, the main body and the extension portion or portions are formed by bending a single plate material, and the extension portion or portions are each formed to be longer than the short axis of the section of the main body. Thus, in the elongated heat transfer tube formed by bending the single plate material, it is possible to reduce deterioration of the heat exchange performance.

Brief Description of Drawings

[Fig. 1] Fig. 1 is a perspective view illustrating an example of the configuration of a heat transfer tube according to Embodiment 1.
[Fig. 2] Fig. 2 is a schematic sectional view illustrating an example of the heat transfer tube according to Embodiment 1 as the heat transfer tube is viewed in a third direction.
[Fig. 3] Fig. 3 is a side view illustrating modification 1 of the heat transfer tube according to Embodiment 1 as the heat transfer tube is viewed in the third direction.
[Fig. 4] Fig. 4 is a side view illustrating modification 2 of the heat transfer tube according to Embodiment 1 as the heat transfer tube is viewed in the third direction.
[Fig. 5] Fig. 5 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 2 as the heat transfer tube is viewed in the third direction.
[Fig. 6] Fig. 6 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 3 as the heat transfer tube is viewed in the third direction.
[Fig. 7] Fig. 7 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 4 as the heat transfer tube is viewed in the third direction.
[Fig. 8] Fig. 8 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 5 as the heat transfer tube is viewed in the third direction.
[Fig. 9] Fig. 9 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 6 as the heat transfer tube is viewed in the third direction.
[Fig. 10] Fig. 10 is a perspective view illustrating an example of the configuration of a heat transfer tube according to Embodiment 7.
[Fig. 11] Fig. 11 is a schematic sectional view illustrating an example of the configuration of a heat exchanger according to Embodiment 8.
[Fig. 12] Fig. 12 is a schematic sectional view illustrating another example of the configuration of the heat exchanger according to Embodiment 8.
[Fig. 13] Fig. 13 is a schematic view illustrating an example of the configuration of a heat exchanger according to Embodiment 9.

Description of Embodiments

Embodiments of the present disclosure will be described with reference to the drawings. The following descriptions concerning the embodiments are not limiting, and various modifications can be made without departing from the gist of the present disclosure. In addition, the present disclosure covers all possible combinations of configurations as described below regarding the embodiments. Furthermore, heat transfer tubes and heat exchanges as illustrated in figures that will be referred to below are merely examples of devices to which the heat transfer tube and the heat exchanger as disclosed in the present disclosure are applied, and heat transfer tubes and heat exchangers according to the present disclosure are not limited to the heat transfer tubes and the heat exchangers as illustrated in the figures. In addition, in each of the figures, components that are the same as or equivalent to those in a previous figure or previous figures are denoted by the same reference signs, and the same is true of the entire text of the specification. It should be noted that relative relationships in size between the components, and the shapes of the components, etc., in the figures may differ from actual ones.

Embodiment 1

A heat transfer tube according to Embodiment 1 of the present disclosure will be described. The heat transfer tube according to Embodiment 1 is used as, for example, a heat exchanger included in a refrigeration cycle apparatus.

[Configuration of Heat Transfer Tube]

Fig. 1 is a perspective view illustrating an example of the configuration of the heat transfer tube according to Embodiment 1. As illustrated in Fig. 1, a heat transfer tube 1 includes a main body 1A and an extension portion or extension portions 1B. The main body 1A and the extension portion or portions 1B of the heat transfer tube 1 are formed by bending a single plate material a number of times. The single plate material is made of metal material having a high heat conductivity, such as aluminum, copper, or brass.

(Main body 1A)

The main body 1A is formed into an elongated shape having a substantially elliptical section. In the main body 1A, a plurality of flow passages are formed to extend in a direction along a long axis of the heat transfer tube 1. First heat exchange fluid flows through the flow passages. The first heat exchange fluid is, for example, water, brine, an HFC-based refrigerant, or a hydrocarbon (HC)-based refrigerant.
In Embodiment 1, it is assumed that a first direction is a direction along the long-axis direction of a section of the main body 1A that is taken along a plane perpendicular to the flow passages of the main body 1A, and will be also referred to as an elongated-section long-axis direction; a second direction is a direction perpendicular to the first direction and a direction along a short axis of the section of the main body 1A that is taken along the plane perpendicular to the flow passages of the main body 1A, the direction along the short axis of the section of the main body 1A being to be also referred to as an elongated-section short-axis direction; and a third direction is a direction perpendicular to the first and second directions and a flow direction of the first heat exchange fluid.
Second heat exchange fluid flows over an outer surface of the main body 1A in a direction parallel to the first direction or the third direction. The second heat exchange fluid is, for example, air. In Fig. 1, flow directions of the first heat exchange fluid and the second heat exchange fluid are indicated by respective outlined arrows.

(Extension Portion 1B)

The extension portion or portions 1B are each formed to extend from the main body 1A in the first direction. The extension portion or portions 1B are formed at one end portion or respective end portions of the single plate material that forms the main body 1A and the extension portion or portions 1B.
Fig. 2 is a schematic sectional view illustrating an example of the heat transfer tube according to Embodiment 1 as the heat transfer tube is viewed in the third direction. As illustrated in Fig. 2, the main body 1A includes an outer tube wall 10 and an inner tube wall 11. The outer tube wall 10 corresponds to an outer periphery of the heat transfer tube 1 formed by bending the single plate material a number of times. The inner tube wall 11 is a wall portion of the main body 1A that is other than the outer tube wall 10.
The outer tube wall 10 includes contact portions of the main body 1A with which the second heat exchange fluid comes into contact and other portions of the main body 1A that are adjacent to the contact portions. The inner tube wall 11 is a portion of the main body 1A that is other than the outer tube wall 10. The inner tube wall 11 has two or more layered portions 11a and at least one partition portion 11b.
The layered portions 11a of the inner tube wall 11 are portions which are in contact with the outer tube wall 10, and are joined to the outer tube wall 10 by, for example, brazing. The at least one partition portion 11b is formed by bending the plate material in such a manner as to partition the interior of the main body 1A.
As described above, inner spaces of the main body 1A are surrounded by the outer tube wall 10 and the layered portions 11a and the at least one partition portion 11b of the inner tube wall 11, and serve as flow passages through which the first heat exchange fluid flows. It should be noted that in the following descriptions, as the heat transfer tube 1 is viewed in the third direction, the length of the main body 1A in the elongated-section long-axis direction (the first direction) is defined as an elongated-section long-axis length DA and the length of the main body 1A in the elongated-section short axis direction (the second direction) is defined as an elongated-section short-axis length DB.
The extension portion or portions 1B, that is, at least one extension portion 1B, is formed such that at least one of the end portions of the plate material extends from the main body 1A in the elongated-section long-axis direction that is the first direction. Furthermore, the extension portion or portions 1B are each formed to have a greater length than the elongated-section short-axis length DB of the main body 1A in order to improve the heat transfer performance of a heat exchanger in the case where the heat transfer tube 1 is used in the heat exchanger. The heat transfer performance of the heat exchanger will be described later.
It should be noted that in the example as illustrated in Fig. 2, two extension portions 1B are provided at respective ends of the plate material, and extend in the opposite directions along the elongated-section long-axis direction, that is, the two extension portions 1B corresponds to the respective ends of the plate material. However, the number of extension portions 1B to be formed is not limited to that of the above example. For example, the heat transfer tube 1 may be formed to have only a single extension portion 1B.

Modification 1

Fig. 3 is a side view illustrating modification 1 of the heat transfer tube according to Embodiment 1 as the heat transfer tube is viewed in the third direction. In the heat transfer tube 1 as illustrated in Fig. 3, one of extension portions 1B is bent and then stacked on the other extension portion 1B to form a single extension portion 1B. In such a manner, the heat transfer tube 1 according to Embodiment 1 may be formed to have a single extension portion 1B. In the above configuration, the extension portion 1B and part of the outer tube wall 10 of the main body 1A each have a double-layered structure, and thus each have a greater thickness. Thus, the pressure resistance and durability of the heat transfer tube 1 can be improved.

Modification 2

Fig. 4 is a side view illustrating modification 2 of the heat transfer tube according to Embodiment 1 as the heat transfer tube is viewed in the third direction. The heat transfer tube 1 as illustrated in Fig. 4 is formed such that one of the end portions of the plate material is provided as the inner tube wall 11. Thus, the heat transfer tube 1 has a single extension portion 1B. Therefore, in the heat transfer tube 1 of modification 2, the extension portion 1B and part of the outer tube wall 10 of the main body 1A do not have a double-layered structure. Because of provision of the above configuration, it is possible to reduce the amount of material to be used and the amount of brazing material for use in joining portions of the double-layered structure together, and thus reduce manufacturing costs of the heat transfer tube 1, as compared with the heat transfer tube 1 of modification 1.

(Heat Transfer Performance of Heat Exchanger)

Next, the heat transfer performance of the heat exchanger employing the heat transfer tube 1 according to Embodiment 1 will be described. In general, the heat transfer performance of a heat exchanger can be determined using an overall heat transfer coefficient AoK. The overall heat transfer coefficient AoK is calculated on the basis of equation (1) below. In the expression (1), Ao is an outer heat transfer area, K is a heat transfer coefficient, Ap is a heat-transfer-tube surface area, η is a fin efficiency, A_F is a fin surface area, αo is an outer heat transfer coefficient (including a contact thermal resistance), Ai is an inner heat transfer area, and αi is an inner heat transfer coefficient.
[Math. 1] $\frac{1}{A_{o} K} = \frac{1}{(A_{p} + {ηA}_{F}) α_{o}} + \frac{1}{A_{i} α_{i}}$
It is seen from equation (1) that the heat transfer performance of a heat exchanger can be improved by increasing the heat-transfer-tube surface area Ap and the fin surface area A_F. Thus, since the heat transfer tube 1 according to Embodiment 1 is provided with the extension portion or portions 1B formed integrally with the main body 1A, even when the main body 1A has a tubular shape similar to those of existing heat transfer tubes, the outer heat transfer area Ao can still be increased, as compared with the existing heat transfer tubes. In addition, even in the case where the inner volume of the heat transfer tube 1 is decreased smaller than those of the existing heat transfer tubes in compliance with environmental regulations or other requirements, the length of the extension portion or portions 1B is further increased, whereby while the inner tube volume is decreased, the outer heat transfer area Ao can still be kept substantially equal to those of the existing heat transfer tubes.
As described above, the heat transfer tube 1 according to Embodiment 1 includes the main body 1A through which the first heat exchange fluid flows, the main body 1A being formed by bending a single plate material a number of times, and includes the at least one extension portion 1B that corresponds to at least one of end portions of the single plate material in the elongated-section long-axis direction. In such a manner, since the heat transfer tube 1 is formed to have the at least one extension portion 1B, even when the main body 1A has a tubular shape similar to those of the existing heat transfer tubes, the outer heat transfer area Ao can be made larger than those of the existing heat transfer tubes. Therefore, in the case where a heat exchanger employs the heat transfer tube 1, the heat transfer performance of the heat exchanger can be improved.
Furthermore, the extension portion or portions 1B of the heat transfer tube 1 are each formed to have a length greater than the elongated-section short-axis length DB. Thus, at the time of performing bending processing to manufacture the heat transfer tube 1, the extension portion or portions 1B is used as a grip or grips for a manufacturing device. Because of this configuration, it is possible to improve the manufacturability of the heat transfer tube 1.
It should be noted that as a plate material of which the heat transfer tube 1 is formed, a clad material may be used. In the case of using the clad material, aluminum or other material is used as a base material, and opposite sides of the base are coated with brazing material. In the case where such a clad material is used as the plate material, at the time of manufacturing of the heat transfer tube 1, it is not necessary to provide a step of applying brazing material on surfaces of the plate material. It is therefore possible to improve the manufacturability of the heat transfer tube 1.

Embodiment 2

Next, Embodiment 2 of the present disclosure will be described. In Embodiment 2, part of the outer tube wall 10 that extends in the elongated-section short axis direction is formed to have a double-layered structure. In this regard, Embodiment 2 is different from Embodiment 1. It should be noted that regarding Embodiment 2, components that are the same as those in Embodiment 1 will be denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 5 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 2 as the heat transfer tube is viewed in the third direction. As illustrated in Fig. 5, the outer tube wall 10 of the heat transfer tube 1 according to Embodiment 2 has an outer-wall layered portion or portions 10a each of which extends in the elongated-section short axis direction and has a double-layered structure.
The outer-wall layered portion or portions 10a are each formed by bending the plate material at the boundary between the main body 1A and the extension portion 1B in Embodiment 1 along the part of the outer tube wall 10 that extends in the elongated-section short axis direction. The bent portion of the plate material and the above part of the outer tube wall 10 are joined together by, for example, brazing to form the outer-wall layered portion 10a. Thus, the part of the outer tube wall 10 that extends in the elongated-section short axis direction has a higher strength, thus improving the pressure resistance and the durability of the heat transfer tube 1.
It should be noted that the longer the outer-wall layered portion 10a, the larger the contact area between materials that form layers of the double layered structure of the outer tube wall 10, and the higher the joint strength. It is therefore preferable that the length of the outer-wall layered portion 10a be, for example, greater than or equal to half of the elongated-section short-axis length DB.
As described above, in the case where the heat transfer tube 1 according to Embodiment 2 is used in a heat exchanger, the heat transfer tube 1 can improve the heat transfer performance of the heat exchanger as in Embodiment 1. In the heat transfer tube 1 according to Embodiment 2, the outer-wall layered portion 10a is provided as the part of the outer tube wall 10 that extends in the elongated-section short axis direction. Furthermore, it is preferable that the length of the outer-wall layered portion 10a is greater than or equal to half of the elongated-section short-axis length DB. In the case where the length of the outer-wall layered portion 10a is set in the above manner, the part of the outer tube wall 10 that extends in the elongated-section short axis direction has a higher strength, as a result of which it is possible to improve the pressure resistance and the durability of the heat transfer tube 1.

Embodiment 3

Next, Embodiment 3 of the present disclosure will be described. In Embodiment 3, each of end portions of the main body 1A in the elongated-section long-axis direction is rounded, and the extension portion or portions 1B are each located substantially on a central axis of the heat transfer tube that passes through the center of the part of the outer tube wall that extends in the elongated-section short axis direction. In this regard, Embodiment 3 is different from Embodiments 1 and 2. It should be noted that regarding Embodiment 3, components that are the same as those in Embodiment 1 and/or Embodiment 2 will be denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 6 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 3 as the heat transfer tube is viewed in the third direction. As illustrated in Fig. 6, in the heat transfer tube 1 according to Embodiment 3, each end portion of the main body 1A in the elongated-section long-axis direction is rounded. The extension portion or portions 1B are each formed substantially on the central axis that extends through the center of part of the heat transfer tube 1 that has the elongated-section short-axis length DB.
The outer tube wall 10 of the main body 1A is formed by bending the plate material such that each end portion of the main body 1A in the elongated-section long-axis direction is rounded. The extension portion or portions 1B are each formed in the following manner: the plate material is bent along the rounded portion of the outer tube wall 10 of the main body 1A, and from this bent portion, part of the plate material that is close to the axis extending through the center of the part of the heat transfer tube 1 that has the elongated-section short-axis length DB is bent to form the extension portion 1B.
In the case where the main body 1A and the extension portion or portions 1 B are formed in the above manner, the second heat exchange fluid first flows along the extension portion or portions 1B. Then, while flowing along the rounded shape of the main body 1A, the second heat exchange fluid strikes the main body 1A. At this time, a flow resistance generated when the second heat exchange fluid strikes the main body 1A is reduced, as compared with the case where the main body 1A is formed not to have a rounded shape.
As described above, in the case where the heat transfer tube 1 according to Embodiment 3 is used in a heat exchanger, the heat transfer tube 1 can improve the heat transfer performance of the heat exchanger as in Embodiments 1 and 2. In the heat transfer tube 1 according to Embodiment 3, each of the end portions of the main body 1A in the elongated-section long-axis direction is rounded, and the extension portion or portions 1B are each formed on the axis that passes through the center of the part of the heat transfer tube 1 that has the elongated-section short-axis length DB. This configuration reduces a flow resistance that is caused by the second heat exchange fluid that flows over the surface of the heat transfer tube 1 when the second heat exchange fluid strikes the main body 1A. It is therefore possible to reduce a drive force that is required for a fan or other devices to supply the second heat exchange fluid.

Embodiment 4

Next, Embodiment 4 of the present disclosure will be described. In Embodiment 4, after being bent toward the central axis of the heat transfer tube 1 that passes through the center of part of the heat transfer tube 1 that extends in the elongated-section short axis direction, a portion or portions of the outer tube wall 10 of the main body 1A extends along the central axis. It should be noted that regarding Embodiment 4, components that are the same as any of Embodiments 1 to 3 will be denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 7 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 4 as the heat transfer tube is viewed in the third direction. As illustrated in Fig. 7, in the heat transfer tube 1 according to Embodiment 4, after being bent toward the central axis that passes through the center of part of the heat transfer tube 1 that has the elongated-section short-axis length DB, the abovementioned portion or portions of the outer tube wall 10 of the main body 1A extends along the above axis. At this time, the above bent portion or portions of the outer tube wall 10 are brought in contact with the inner tube wall 11.
As described above, in the case where the heat transfer tube 1 according to Embodiment 4 is used in a heat exchanger, the heat transfer tube 1 can improve the heat transfer performance of the heat exchanger as in Embodiments 1 to 3. In the heat transfer tube 1 according to Embodiment 4, the abovementioned portion or portions of the outer tube wall 10 extend along the central axis that passes through the center of the part of the heat transfer tube 1 that has the elongated-section short-axis length DB, after being bent toward the central axis. Thus, the inner volume of the heat transfer tube 1, which include flow passages for the first heat exchange fluid, is reduced, with compared with the case where the outer tube wall 10 is not bent. Thus, the amount of the first heat exchange fluid to be filled can be reduced.
Furthermore, since the abovementioned portion or portions of the outer tube wall 10 are bent in the above manner, the outer heat transfer area Ao of the heat transfer tube 1 can be increased. Accordingly, in the case where the heat transfer tube 1 is used in the heat exchanger, the heat transfer tube 1 can improve the heat exchange performance of the heat exchanger. To be more specific, the above portions of the outer tube wall 10 are bent to be in contact with the inner tube wall 11, and as a result the contact area between the outer tube wall 10 and the inner tube wall 11 is increased. Accordingly, the heat transfer tube 1 can improve the pressure resistance and the durability.

Embodiment 5

Next, Embodiment 5 of the present disclosure will be described. In Embodiment 5, the entire outer tube wall 10 of the main body 1A is formed to have a double-layered structure or a multi-layered structure. In this regard, Embodiment 5 is different from Embodiments 1 to 4. It should be noted that regarding Embodiment 5, components that are the same as those in any of Embodiments 1 to 4 are denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 8 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 5 as the heat transfer tube is viewed in the third direction. As illustrated in Fig. 8, in the heat transfer tube 1 according to Embodiment 5, the outer tube wall 10 of the main body 1A is formed by bending the plate material such that two or more layers of the plate material are stacked together. In the outer tube wall 10, the stacked two or more layers of the plate material are joined together by, for example, brazing. As a result, the entire outer tube wall 10 has a double-layered structure or a multi-layered structure.
Because of the above configuration, in the case where the heat transfer tube 1 according to Embodiment 5 is used in the heat exchanger, the heat transfer tube 1 can improve the heat transfer performance of the heat exchanger as in Embodiments 1 to 4. In the heat transfer tube 1 according to Embodiment 5, the entire outer tube wall 10 has a double-layered structure or a multi-layered structure. Therefore, the heat transfer tube 1 according to Embodiment 5 can further improve the pressure resistance and the durability, as compared with Embodiments 1 to 4.

Embodiment 6

Next, Embodiment 6 of the present disclosure will be described. In Embodiment 6, the outer tube wall 10 and the inner tube wall 11 of the main body 1A are formed symmetrically with respect to the intersection of an axis that passes through the center of part of the heat transfer tube 1 that has the elongated-section long-axis length DA and the central axis that passes through the center of the part of the heat transfer tube 1 that has the elongated-section short-axis length DB. It should be noted that regarding Embodiment 6, components that are the same as those in any of Embodiments 1 to 5 will be denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 9 is a schematic sectional view illustrating an example of a heat transfer tube according to Embodiment 6 as the heat transfer tube is viewed in the third direction. As illustrated in Fig. 9, the outer tube wall 10 and the inner tube wall 11 of the main body 1A according to Embodiment 6 are formed by bending the plate material such that the outer tube wall 10 and the inner tube wall 11 are symmetrical with respect to the intersection of the axis that passes through the center of the part of the heat transfer tube 1 that has the elongated-section long-axis length DA and the central axis that passes through the center of the part of the heat transfer tube 1 that has the elongated-section short-axis length DB.
Because of the above configuration, in the case where the heat transfer tube 1 according to Embodiment 6 is used in the heat exchanger, the heat transfer tube 1 can improve the heat transfer performance of the heat exchanger as in Embodiments 1 to 5. Furthermore, in the heat transfer tube 1 according to Embodiment 6, the outer tube wall 10 and the inner tube wall 11 are formed symmetrical with respect to the intersection of the axis that passes through the center of the part of the heat transfer tube 1 that has the elongated-section long-axis length DA and the central axis that passes through the center of the part of the heat transfer tube 1 that has the elongated-section short-axis length DB. In this configuration, even when the heat transfer tube 1 is rotated by 180° about an axis that extends in the third direction and passes through the intersection of the axis passing through the center of the part of the heat transfer tube 1 that has the elongated-section long-axis length DA and the central axis passing through the center of the part of the heat transfer tube 1 that has the elongated-section short-axis length DB, the shape of the heat transfer tube 1 is the same as that before the heat transfer tube 1 is rotated. Therefore, when a heat exchanger is manufactured such that a plurality of heat transfer tubes 1 are arranged, the heat transfer tubes 1 can be arranged without the need to consider the orientation of the heat transfer tubes 1. It is therefore possible to improve the manufacturability of the heat exchanger.

Embodiment 7

Next, Embodiment 7 of the present disclosure will be described. In Embodiment 7, the extension portion or portions 1B are subjected to heat transfer promotion processing. In this regard, Embodiment 7 is different from Embodiments 1 to 6. It should be noted that regarding Embodiment 7, components that are the same as those in any of Embodiments 1 to 6 will be denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 10 is a perspective view illustrating an example of the configuration of a heat transfer tube according to Embodiment 7. As illustrated in Fig. 10, the heat transfer tube 1 includes the main body 1A and the extension portion or portions 1B as in Embodiments 1 to 6. In Embodiment 7, the extension portion or portions 1B each have a heat-transfer promotion portion 12 that promotes heat transfer from the second heat exchange fluid, such as cut-and-raised portions or irregularities.
The heat-transfer promotion portion 12 is formed by performing press working on part of the plate material that corresponds to the extension portion 1B in the plate material. It should be noted that in this example, the heat-transfer promotion portion 12 is provided at least at outer part of the extension portion 1B, however, location of the heat-transfer promotion portion 12 is not limited to that of the above example. For example, the heat-transfer promotion portion 12 may also be provided, for example, at inner part of the extension portion 1B.
In the above configuration, in the heat transfer tube 1 according to Embodiment 7, the extension portion 1B has the heat-transfer promotion portion 12. Thus, when flowing over the surface of the extension portion 1B, the second heat exchange fluid strikes the heat-transfer promotion portion 12, thereby forming a swirl flow of the fluid. Thus, the outer heat transfer coefficient of the heat transfer tube 1 is improved, and the heat transfer tube 1 for use in the heat exchanger can further improve the heat exchange performance of the heat exchanger.

Embodiment 8

Next, Embodiment 8 of the present disclosure will be described. The description concerning Embodiment 8 refers to the case where the heat transfer tube 1 described regarding each of Embodiments 1 to 7 is provided in a heat exchanger. It should be noted that regarding Embodiment 8, components that are the same as those of any of Embodiments 1 to 7 will be denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 11 is a schematic sectional view illustrating an example of the configuration of a heat exchanger according to Embodiment 8. As the example, Fig. 11 illustrates a section of a heat exchanger 20A that is taken along a plane that extends in the first and second directions as the heat exchanger 20A is viewed in the third direction. As illustrated in Fig. 11, the heat exchanger 20A is a fin-and-tube heat exchanger. The heat exchanger 20A is made up of a plurality of fins 21 and a plurality of heat transfer tubes 1 each of which is described regarding Embodiments 1 to 7 and which are arranged in parallel. Each of fins 21 is provided between associated adjacent two of the heat transfer tubes 1, and is joined to both the associated adjacent heat transfer tubes 1. The following description is made concerning the heat exchanger 20A including the heat transfer tubes 1 each of which corresponds to the heat transfer tube 1 according to Embodiment 3.
The heat transfer tubes 1 are provided to extend in the third direction. The heat transfer tubes 1 are arranged in parallel in the second direction. That is, the heat transfer tubes 1 are arranged in parallel in a direction perpendicular to both the flow direction of the first heat exchange fluid and the flow direction of the second heat exchange fluid. Furthermore, headers (not illustrated) are connected to opposite ends of each of the heat transfer tubes 1 in the third direction.
The fins 21 are, for example, corrugated fins, and each provided between associated adjacent two of the heat transfer tubes 1. Each of the fins 21 is a plate-like member made of metal material having a high heat conductivity, such as aluminum.
In order to form each fin 21, the plate-like member is bent and shaped such that flat portions and curved portions (both not illustrated) of the plate-like member are alternately arranged. The flat portions are arranged substantially in parallel and at regular intervals. The curved portions of the fins 21 are connected to the outer tube walls 10 of the heat transfer tubes 1 by brazing, welding, or other methods. The flat portions of the fins 21 are subjected to processing to form slits, cut-and-raised portions, or irregularities in order to promote heat transfer.
Fig. 12 is a schematic sectional view illustrating another example of the configuration of the heat exchanger according to Embodiment 8. As the example, Fig. 12 illustrates a section of a heat exchanger 20B that is taken along a plane that extends in the first and second directions, as the heat exchanger 20B is viewed in the third direction, as well as Fig. 11. This example is an example of the heat exchanger 20B including the heat transfer tubes 1 each of which corresponds to the heat transfer tube 1 according to Embodiment 4.
In the heat transfer tube 1 according to Embodiment 4, after being bent toward the central axis that passes through the center of the part of the heat transfer tube 1 that extends in the elongated-section short-axis direction, the abovementioned portion or portions of the outer tube wall 10 extend along the central axis. Thus, in the heat exchanger 20B, spaces 22 are provided between the heat transfer tube 1 and the fin 21. When dew condensation occurs on a surface of the heat exchanger 20B, the space 22 serves as a water passage through which dew condensation water is discharged.
As described above, each of the heat exchangers 20A and 20B according to Embodiment 8 includes the heat transfer tubes 1 each of which is described regarding Embodiments 1 to 7. Each of the fins 21 is provided between associated adjacent two of the heat transfer tubes 1. The heat transfer tubes 1 each have the extension portion or portions 1B as described regarding Embodiments 1 to 7, and thus has a larger outer heat transfer area Ao than existing fin-and-tube heat exchangers. Therefore, the heat exchangers 20A and 20B according to Embodiment 8 can improve the heat exchange performance, as compared with the existing heat exchangers.
The heat exchanger 20B including the heat transfer tubes 1 each of which corresponds to the heat transfer tube 1 according to Embodiment 4 is provided with water passages through which dew condensation water is discharged, and thus can improve a drainage performance. Since the drainage performance is improved, it is possible to improve a latent-heat exchange performance or reduce a defrosting operation time that is time in which the heat exchanger 20B is defrosted.

Embodiment 9

Next, Embodiment 9 of the present disclosure will be described. Regarding Embodiment 9, a plurality of heat transfer tubes 1 each of which is described regarding Embodiments 1 to 7 are provided in a heat exchanger. In this regard, Embodiment 9 is the same as Embodiment 8. However, unlike Embodiment 8, in Embodiment 9, a fin is not provided. It should be noted that regarding Embodiment 9, components that are the same as those in any of Embodiments 1 to 8 will be denoted by the same reference signs, and their detailed descriptions will thus be omitted.
Fig. 13 is a schematic view illustrating an example of the configuration of a heat exchanger according to Embodiment 9. As the example, Fig. 13 illustrates a side of a heat exchanger 30 as viewed in the first direction. As illustrated in Fig. 13, the heat exchanger 30 according to Embodiment 9 is configured such that only a plurality of heat transfer tubes 1 each of which is described above regarding Embodiments 1 to 7 are arranged in parallel, as well as the heat exchangers 20A and 20B according to Embodiment 8.
The heat transfer tubes 1 are provided to extend in the third direction. In Embodiment 9, the heat exchanger 30 is provided such that the third direction is parallel to the direction of gravity. The heat transfer tubes 1 are arranged in parallel to each other in the second direction. That is, the heat transfer tubes 1 are arranged in parallel in a direction perpendicular to both the flow direction of the first heat exchange fluid and the flow direction of the second heat exchange fluid. Furthermore, headers 31A and 31B are connected to opposite ends of the heat transfer tubes 1 in the third direction, respectively.
In the heat exchanger 30, no fins 21 are provided. Needless to say, the heat exchanger 30 is not configured such that fins 21 are each provided between adjacent ones of the heat transfer tubes 1. Therefore, a space or spaces are provided between the adjacent heat transfer tubes 1. Thus, it is possible to improve drainage of dew condensation water that is generated when dew condensation occurs on a surface of the heat exchanger 30.
As described above, the heat exchanger 30 according to Embodiment 9, as well as the heat exchanger according to Embodiment 8, can improve the heat exchange performance, as compared with the existing heat exchangers. The heat exchanger 30 according to Embodiment 9 is provided such that the third direction that is the flow direction of the first heat exchange fluid is parallel to the direction of gravity, and no fins are provided. Needless to say, the heat exchanger 30 is not configured such that fins are each provided between adjacent ones of the heat transfer tubes 1.
As described above, in the heat exchanger 30, fins are not provided. Needless to say, fins are not provided to extend in a direction perpendicular to the direction of gravity. Thus, as compared with the fin-and-tube heat exchangers, the heat exchanger 30 can improve drainage of dew condensation water. Furthermore, because of improvement of drainage of dew condensation water, the latent-heat exchange performance can be improved, or the defrosting operation time in which the heat exchanger 30 is defrosted can be reduced.

Reference Signs List

1: heat transfer tube, 1A: main body, 1B: extension portion, 10: outer tube wall, 10a: outer-wall layered portion, 11: inner tube wall, 11a: layered portion, 11b: partition portion, 12: heat-transfer promotion portion, 20A, 20B, 30: heat exchanger, 21: fin, 22: space, 31A, 31B: header

Claims

A heat transfer tube (1) comprising:
an elongated main body (1A) including an outer tube wall (10), an inner tube wall (11), and a plurality of flow passages, the outer tube wall (10) and the inner tube wall (11) being formed by bending a single plate material a number of times, and the plurality of flow passages being surrounded and defined by the outer tube wall (10) and the inner tube wall (11); and characterised by

an extension portion (1B) corresponding to at least one of the end portions of the single plate material, the extension portion (1B) being formed such that the at least one of the end portions of the single plate material extends from the main body (1A) in an elongated-section long-axis direction that is a direction along a long axis of a section of the main body (1A), the extension portion (1B) being formed to extend from the outer tube wall (10) in a direction parallel to the elongated-section long-axis direction, the extension portion (1B) being formed longer than a short axis of the section of the main body (1A).
The heat transfer tube (1) of claim 1, wherein part of the outer tube wall (10) that extends in an elongated-section short-axis direction that is a direction along the short axis of the section of the main body (1A) is an outer-wall layered portion (10a) having a double-layered structure.
The heat transfer tube (1) of claim 2, wherein the outer-wall layered portion (10a) has a length greater than or equal to half of a length of the short axis.
The heat transfer tube (1) of any one of claims 1 to 3, wherein part of the outer tube wall (10) extends in a direction along an axis passing through a center of the short axis, after being bent toward the axis passing through the center of the short axis.
The heat transfer tube (1) of any one of claims 1 to 4, wherein entirety of the outer tube wall (10) is formed to have a double-layered structure or a multi-layered structure.
The heat transfer tube (1) of any one of claims 1 to 5, wherein the outer tube wall (10) and the inner tube wall (11) are symmetrical with respect to an intersection of an axis that passes through a center of the long axis of the section of the main body (1A) and an axis that passes through the center of the short axis.
The heat transfer tube (1) of any one of claims 1 to 6, wherein the extension portion (1B) includes a heat-transfer promotion portion (12) configured to promote heat transfer from fluid that flows over an outer surface of the extension portion (1B).
The heat transfer tube (1) of any one of claims 1 to 7, wherein both sides of a base of the single plate material is coated with brazing material.
A heat exchanger (30) comprising a plurality of heat transfer tubes (1) identical to the heat transfer tube (1) of any one of claims 1 to 8, wherein
the plurality of heat transfer tubes (1) are arranged in parallel to each other along a direction perpendicular to a flow direction of first heat exchange fluid and a flow direction of second heat exchange fluid, the first heat exchange fluid flowing through the plurality of flow passages, the second heat exchange fluid flowing over an outer surface of the main body (1A), and

a space or spaces are each provided between associated adjacent ones of the plurality of heat transfer tubes (1) without a fin (21) or fins (21).
The heat exchanger (30) of claim 9, wherein the heat exchanger is provided such that the flow direction of the first heat exchange fluid is parallel to a direction of gravity.