EP4641127A1

EP4641127A1 - Heat exchanger and method for producing heat exchanger

Info

Publication number: EP4641127A1
Application number: EP23906909.9A
Authority: EP
Inventors: Kentaro SAGAWA
Original assignee: Fujitsu General Ltd
Current assignee: Fujitsu General Ltd
Priority date: 2022-12-21
Filing date: 2023-12-15
Publication date: 2025-10-29
Also published as: WO2024135547A1; JP2024089436A

Abstract

[Object] To provide a heat exchanger that suppresses an increase in manufacturing costs and improves heat transfer characteristics.

[Solving Means] In order to accomplish the above-mentioned objective, a heat exchanger according to an embodiment of the present invention is a heat exchanger formed by stacking a plurality of heat transfer plates. The plurality of heat transfer plates includes a first heat transfer plate and a second heat transfer plate and the first heat transfer plate and the second heat transfer plate are alternately stacked. A first flow path is formed in the first heat transfer plate and a second flow path is formed in the second heat transfer plate. The second flow path has a flow path cross-sectional area smaller than a flow path cross-sectional area of the first flow path.

Description

Technical Field

The present invention relates to a heat exchanger and a manufacturing method for a heat exchanger.

Background Art

A stacked-type heat exchanger is formed by stacking a plurality of heat transfer plates with flow paths formed in a metal plate by an etching technique and integrating the plurality of heat transfer plates by diffusion joining or the like (e.g., see Patent Literature 1). The plurality of heat transfer plates is divided into a first heat transfer plate and a second heat transfer plate in accordance with fluids (first fluid and second fluid) for heat exchange, and the first heat transfer plate and the second heat transfer plate are alternately stacked. The first fluid and the second fluid may be the same fluid or may be different fluids. For example, the first fluid may be water and the second fluid may be a refrigerant.
In the stacked-type heat exchanger, metal plates with the same plate thickness are used as the first heat transfer plate and the second heat transfer plate and flow paths with the same depth are each formed in the metal plates. Here, in a case where water is used as the first fluid and a refrigerant is used as the second fluid, the heat transfer coefficient and the pressure loss of both can differ depending on physical properties of the fluids for heat exchange. Accordingly, the refrigeration capability and operating efficiency of a refrigeration apparatus using the heat exchanger may decrease due to insufficient heat exchange in the heat exchanger or increased power for circulating the fluids.
In such circumstances, there is a known technology of setting the flow path cross-sectional area of the first fluid to be different from the flow path cross-sectional area of the second fluid in the heat exchanger for a plate-type heat exchanger with a structure similar to the structure of the stacked-type heat exchanger (e.g., see Patent Literature 2). For example, in this technology, in a case where the heat transfer coefficient and the pressure loss of the first fluid are greater than those of the second fluid, the flow path cross-sectional area of the first fluid is set to be larger than the flow path cross-sectional area of the second fluid. Accordingly, the pressure loss of the first fluid decreases because the flow velocity of the first fluid decreases. On the other hand, the heat transfer coefficient of the second fluid does not decrease because the flow velocity of the second fluid does not decrease, so the conveyance power of the first fluid can be reduced while suppressing the deterioration of the heat transfer performance.

Citation List

Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No. 2015-190705
Patent Literature 2: Japanese Patent Application Laid-open No. HEI 10-288480

Disclosure of Invention

Technical Problem

In this regard, in the stacked-type heat exchanger, at present, metal plates with the same plate thickness are used as heat transfer plates for different fluids and flow paths with the same depth are formed in each of them. In other words, in the stacked-type heat exchanger, the flow path cross-sectional area is not changed to match the characteristics of the fluids, and optimal heat transfer design that matches the characteristics of the fluids is not performed.
In addition, in the stacked-type heat exchanger, through-holes can be formed in the heat transfer plate in addition to the flow paths. The through-holes are provided for connecting the flow paths of each heat transfer plate to the inlet and outlet of the stacked-type heat exchanger to allow the fluid to flow into or out of the stacked-type heat exchanger. It is favorable to form the flow paths and the through-holes in the same etching process in order to suppress an increase in manufacturing costs. However, in a case of forming shallow flow paths in order to obtain an optimal flow path cross-sectional area, the following problems may occur. For example, in a heat transfer plate with a bottom plate portion that functions as a partition between stacked heat transfer plates, in a case where flow paths and through-holes that penetrate the heat transfer plates are worked in the same etching process, the etching time is set to the time required to form the flow paths. Therefore, in a case of forming shallow flow paths, the etching time is shortened, and the heat transfer plates cannot be penetrated by that etching process, and in the end, it becomes impossible to form the flow paths and the through-holes in the same etching process. Here, if the process of forming the through-holes is added, the manufacturing costs increase.
Moreover, in a case of forming shallow flow paths in one of the heat transfer plates with the same plate thickness, the thickness of the bottom plate portion of the flow paths may be larger than the thickness of the bottom plate portion of the flow paths of the other heat transfer plate. The thickness of the bottom plate portion is sufficient if it is thick enough to meet the pressure resistance performance, and if it becomes thicker, it leads to an increase in material costs. Moreover, if the thickness of the bottom plate portion of the flow paths increases, the thermal resistance due to heat conduction increases, and the heat transfer performance of the heat exchanger is deteriorated.
In view of the above-mentioned circumstances, it is an objective of the present invention to provide a heat exchanger that suppresses an increase in manufacturing costs and improves heat transfer characteristics and the manufacturing method for a heat exchanger.

Solution to Problem

In order to accomplish the above-mentioned objective, a heat exchanger according to an embodiment of the present invention is a heat exchanger formed by stacking a plurality of heat transfer plates.
The plurality of heat transfer plates includes a first heat transfer plate and a second heat transfer plate and the first heat transfer plate and the second heat transfer plate are alternately stacked.
A first flow path is formed in the first heat transfer plate and a second flow path is formed in the second heat transfer plate.
The second flow path has a flow path cross-sectional area smaller than a flow path cross-sectional area of the first flow path.
With such a heat exchanger, the increase in manufacturing costs is suppressed and the heat transfer characteristics are improved.
In the heat exchanger, the second heat transfer plate may have a plate thickness different from a plate thickness of the first heat transfer plate.
With such a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
In the heat exchanger, the second heat transfer plate may have a plate thickness smaller than a plate thickness of the first heat transfer plate.
With such a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
In the heat exchanger, each of the first heat transfer plate and the second heat transfer plate may include a bottom plate portion, the bottom is a partition between the first flow path and the second flow path, and the bottom plate portion may have a thickness equal to or larger than a predetermined thickness.
With such a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
In the heat exchanger, the predetermined thickness may be 0.1 mm or more.
With such a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
In the heat exchanger, the first flow path may have a depth that is 40% or more and 70% or less of a plate thickness of the first heat transfer plate, and the second flow path may have a depth that is 40% or more and 70% or less of a plate thickness of the second heat transfer plate.
With such a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
In the heat exchanger, a through-hole may be formed in each of the first heat transfer plate and the second heat transfer plate.
With such a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
In order to accomplish the above-mentioned objective, a manufacturing method for a heat exchanger according to an embodiment of the present invention is a manufacturing method for a heat exchanger according to any one of the above configurations. The first flow path and the second flow path are formed by etching.
With such a manufacturing method for a heat exchanger, the increase in manufacturing costs is suppressed and the heat transfer characteristics are improved.
The manufacturing method for a heat exchanger may further include forming a bottom plate portion which is a partition between the first flow path and the second flow path by etching in each of the first heat transfer plate and the second heat transfer plate, the bottom plate portion being formed to have a thickness equal to or larger than a predetermined thickness.
With such a manufacturing method for a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
The manufacturing method for a heat exchanger may further include: forming a first through-holes in the first heat transfer plate by etching and forming a second through-holes in the second heat transfer plate by etching; forming the first through-holes by a same process as an etching process of forming the first flow path; and forming the second through-holes by a same process as an etching process of forming the second flow path.
With such a manufacturing method for a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.
The manufacturing method for a heat exchanger may further include forming the first flow path, the second flow path, the first through-holes, and the second through-holes by a same etching process.
With such a manufacturing method for a heat exchanger, the increase in manufacturing costs is further suppressed and the heat transfer characteristics are improved.

Advantageous Effects of Invention

As described above, in accordance with the present invention, a heat exchanger that suppresses an increase in manufacturing costs and improves heat transfer characteristics, and a manufacturing method for a heat exchanger are provided.

Brief Description of Drawings

[Fig. 1] A perspective view schematically showing an example of a heat exchanger according to the present embodiment.
[Fig. 2] Perspective view schematically showing heat transfer plates on which flow paths are formed.
[Fig. 3] Perspective view schematically showing metal plates.
[Fig. 4] Cross-sectional views schematically showing cross-sections of heat transfer plates.
[Fig. 5] Cross-sectional views schematically showing a manufacturing process of forming flow paths and through-holes in the heat transfer plate.
[Fig. 6] A cross-sectional view schematically showing another example of the heat transfer plate.

Mode(s) for Carrying Out the Invention

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each of the drawings, XYZ-axis coordinates may be introduced. Moreover, the same components or components with the same functions may be denoted by the same reference signs, and descriptions of components described once may be omitted as appropriate. Moreover, numerical values shown below are examples, and the present technology is not limited to these examples.
Fig. 1 is a perspective view schematically showing an example of a heat exchanger according to the present embodiment. In the present embodiment, a direction (stacking direction) in which a plurality of metal plates 2A and 2B is stacked corresponds to a Z-axis direction, a direction of from a tube 54 to a tube 53 corresponds to an X-axis direction and a direction of from a tube 51 to a tube 52 corresponds to a Y-axis direction.
A heat exchanger 10 shown in Fig. 1 is applied to, for example, a stacked-type microchannel heat exchanger. The heat exchanger 10 has, for example, a substantially rectangular parallelepiped shape. The heat exchanger 10 includes a main surface 1u (upper surface), a main surface 1d (lower surface) on a side opposite to the main surface 1u, and a side surface 1w along the stacking direction of the heat exchanger 10. The side surface 1w is continuously provided to the main surface 1u and the main surface 1d. The side surface 1w is formed along the direction in which the plurality of metal plates 2A and 2B is stacked, in the heat exchanger 10. Moreover, it is assumed that in the state shown in Fig. 1, the side of the main surface 1u is an upper side of the heat exchanger 10 and the side of the main surface 1d is a lower side of the heat exchanger 10.
For example, the tubes 51, 52, 53, and 54 are joined to the heat exchanger 10. For example, in the example of Fig. 1, each of the tubes 51, 52, 53, and 54 is joined to the main surface 1u of the heat exchanger 10. For example, when a high-temperature fluid (first fluid) flows in the tube 51 of the heat exchanger 10, the fluid flows out of the tube 52 through the inside of the heat exchanger 10. On the other hand, when a low-temperature fluid (second fluid) flows in the tube 53, the fluid flows out of the tube 54 through the inside of the heat exchanger 10. Examples of the high-temperature fluid include water (including hot water. Hereinafter, it will be simply referred to as water). Examples of the low-temperature fluid include a refrigerant.
The heat exchanger 10 includes a plurality of metal plates 2A, a plurality of metal plates 2B, a plurality of metal plates 3A, and a plurality of metal plates 3B. The heat exchanger 10 is a laminate formed by joining each of the plurality of metal plates 3A, the plurality of metal plates 2A, the plurality of metal plates 2B, and the plurality of metal plates 3B by diffusion joining in this stacking order. Examples of diffusion joining include solid-phase joining, hot pressing, and cold welding. The plurality of metal plates 2A and 2B stacked between the plurality of metal plates 3A and the plurality of metal plates 3B will be collectively referred to as a laminate 2. Moreover, the plurality of metal plates 3A may be formed of a single metal plate having the same thickness as the plurality of metal plates 3A and the plurality of metal plates 3B may be formed of a single metal plate having the same thickness as the plurality of metal plates 3B.
Each of the plurality of metal plates 2A and the plurality of metal plates 2B is a heat transfer plate. In the present embodiment, it is assumed that the metal plate 2A is a first heat transfer plate and the metal plate 2B is a second heat transfer plate. In other words, the laminate 2 includes a plurality of heat transfer plates and the plurality of heat transfer plates includes the first heat transfer plate and the second heat transfer plate. Moreover, the plurality of metal plates 3A is lower side outer plates. The plurality of metal plates 3B is upper side outer plates. The plurality of metal plates 2A and the plurality of metal plates 2B are alternately stacked in the Z-axis direction between the plurality of metal plates 3A and the plurality of metal plates 3B. In each of the plurality of metal plates 2A and each of the plurality of metal plates 2B, flow paths are formed (to be described later).
A space 21 leading to the tube 51, a space 22 leading to the tube 52, a space 23 leading to the tube 53, and a space 24 leading to the tube 54 are formed inside the laminate 2. Each of the spaces 21, 22, 23, and 24 is formed by forming a through-hole (to be described later) in each of the plurality of metal plates 2A and each of the plurality of metal plates 2B before diffusion joining and making these through-holes communicate with each other in the stacking direction.
Moreover, although the solid lines are drawn at the boundaries between the plurality of metal plates stacked in the stacking direction in Fig. 1, such solid lines cannot be visually recognized, i.e., are invisible in the heat exchanger 10 after the diffusion joining. Moreover, since the heat exchanger 10 is formed by stacking the plurality of metal plates in the stacking direction, the height (length in the stacking direction) of the heat exchanger 10 depends on each of the number of metal plates 2A, the number of metal plates 2B, the number of metal plates 3A, and the number of metal plates 3B.
The tubes 51, 52, 53, and 54 are inserted from, for example, the side of the main surface 1u of the heat exchanger 10. The tubes 51, 52, 53, and 54 are joined by, for example, brazing the main surface 1u. The tubes 51, 52, 53, and 54 are arranged, for example, so that a direction of from the tube 51 to the tube 52 intersects with a direction of from the tube 53 to the tube 54.
A hole portion 61 (outflow inlet) in which the tube 51 is fitted, a hole portion 62 (outflow inlet) in which the tube 52 is fitted, a hole portion 63 (outflow inlet) in which the tube 53 is fitted, and a hole portion 64 (outflow inlet) in which the tube 54 is fitted are provided from a metal plate 3B in an uppermost layer of the heat exchanger 10 to extend to the inside of the heat exchanger 10. The hole portion 61 is in communication with the space 21, the hole portion 62 is in communication with the space 22, the hole portion 63 is in communication with the space 23, and the hole portion 64 is in communication with the space 24.
A filler material (not shown) is provided between each of the tubes 51, 52, 53, and 54 and each hole portion. The hole portions in which the tubes 51, 52, 53, and 54 are fitted are not limited to the upper surface (main surface 1u) of the heat exchanger 10, and they may be provided from the metal plate 3A in the lowermost layer of the heat exchanger 10 to extend to the inside of the heat exchanger 10 or may be provided in each of the four side surfaces 1w. A structure in which the tubes 51, 52, 53, and 54 are fitted in and joined to the hole portion is also included in the heat exchanger 10 according to the present embodiment.
Fig. 2 (a) and (b) are perspective views schematically showing heat transfer plates in which flow paths are formed. Fig. 2 (a) shows a structure of the metal plate 2A and Fig. 2 (b) shows a structure of the metal plate 2B.
The outer shape of the metal plate 2A shown in Fig. 2 (a) is rectangular. The metal plate 2A includes a main surface 2ua, a main surface 2da on a side opposite to the main surface 2ua, and side surfaces 2wa continuous with the main surface 2ua and the main surface 2da.
A plurality of groove-like flow paths 25A (first flow path), which is flow paths for a high-temperature fluid, is provided in the main surface 2ua of the metal plate 2A. The number of flow paths 25A is not limited to three shown in the figure. It is sufficient that one or more flow paths 25A are formed in the metal plate 2A, and several tens of flow paths or several hundreds of flow paths may be formed. In the present embodiment, the three flow paths 25A are described below as an example. In a case where a plurality of flow paths 25A is formed in the metal plate 2A, the plurality of flow paths 25A is arranged in the X-axis direction and each of the plurality of flow paths 25A is formed extending in the Y-axis direction. The arrows shown in the flow paths 25A indicate directions in which the high-temperature fluid flows.
The depths of the plurality of flow paths 25A may be uniform at any point. Moreover, the shapes of the flow paths 25A are not limited to linear shapes, and they may be any curve shapes, such as sinusoidal wave shapes or sawtooth shapes. The plurality of flow paths 25A is formed in the one main surface 2ua of the metal plate 2A by, for example, half etching.
Moreover, through-holes 212A, 222A, 232A, and 242A are provided in vicinity of four outer peripheral sides of the metal plate 2A. The through-hole 212A and the through-hole 222A are formed to be arranged in the Y-axis direction and extend in the X-axis direction. The through-hole 232A and the through-hole 242A are formed to be arranged in the X-axis direction and extend in the Y-axis direction. The one ends of the plurality of flow paths 25A are in communication with the through-hole 212A. The other ends of the plurality of flow paths 25A are in communication with the through-hole 222A.
Each of the through-holes 212A, 222A, 232A, and 242A is formed by connecting a hole, which is formed in the one main surface 2ua of the metal plate 2A by etching, to a hole, which is formed in the other main surface 2da of the metal plate 2A by etching, between the main surfaces. That is, each of the through-holes 212A, 222A, 232A, and 242A is formed at the same time as the plurality of flow paths 25A by double-side etching on the metal plate 2A.
The outer shape of the metal plate 2B shown in Fig. 2 (b) is rectangular. The metal plate 2B includes a main surface 2ub, a main surface 2db on a side opposite to the main surface 2ub, and a side surface 2wb continuous with the main surface 2ub and the main surface 2db.
A plurality of groove-like flow paths 25B (second flow path), which is flow paths for a low-temperature fluid, is provided in the main surface 2ub of the metal plate 2B. The number of flow paths 25B is not limited to three shown in the figure. It is sufficient that one or more flow paths 25B are formed in the metal plate 2B, and several tens of flow paths or several hundreds of flow paths may be formed. Hereinafter, in the present embodiment, the three flow paths 25B are described as an example. In a case where a plurality of flow paths 25B is formed in the metal plate 2B, the plurality of flow paths 25B is arranged in the Y-axis direction and each of the plurality of flow paths 25B is formed extending in the X-axis direction. That is, the plurality of flow paths 25B is provided in the metal plate 2B so that the plurality of flow paths 25A intersects with (e.g., is orthogonal to) each other when the metal plate 2A and the metal plate 2B are stacked. The arrows shown in the flow paths 25B indicate directions in which the low-temperature fluid flows.
The depths of the plurality of flow paths 25B may be uniform at any point. Moreover, the shapes of the flow paths 25B are not limited to linear shapes, and they may be any curve shapes, such as sinusoidal wave shapes or sawtooth shapes. The plurality of flow paths 25B is formed in the one main surface 2ub of the metal plate 2B by, for example, half etching.
Moreover, through-holes 212B, 222B, 232B, and 242B are provided in four outer peripheral sides of the metal plate 2B. The through-hole 212B and the through-hole 222B are formed to be arranged in the Y-axis direction and extend in the X-axis direction. The through-hole 232B and the through-hole 242B are formed to be arranged in the X-axis direction and extend in the Y-axis direction. The one ends of the plurality of flow paths 25B are in communication with the through-hole 232B. The other ends of the plurality of flow paths 25B are in communication with the through-hole 242B.
Each of the through-holes 212B, 222B, 232B, and 242B is formed by connecting a hole, which is formed in the one main surface 2ub of the metal plate 2B by etching, to a hole, which is formed in the other main surface 2db of the metal plate 2B by etching, between the main surfaces. That is, each of the through-holes 212B, 222B, 232B, and 242B is formed at the same time as the plurality of flow paths 25B by double-side etching on the metal plate 2B.
Processing of forming the above-mentioned flow paths and the through-holes may be laser processing, precision press working, cutting in addition to etching before the diffusion joining.
Fig. 3 (a) and (b) are perspective views schematically showing metal plates. Fig. 3 (a) shows a structure of the metal plate 3B and Fig. 3 (b) shows a structure of the metal plate 3A.
The outer shape of the metal plate 3B shown in Fig. 3 (a) is rectangular. The metal plate 3B includes a main surface 3u and a main surface 3d on a side opposite to the main surface 3u. Through-holes 601, 602, 603, and 604 penetrating the area between the main surface 3u and the main surface 3d are provided in vicinity of four outer peripheral sides of the metal plate 3B. For example, the through-holes 601, 602, 603, and 604 are formed in advance in each of the plurality of metal plates 3B by laser processing, precision press working, cutting, etching, or the like before the diffusion joining. The outer shape of the metal plate 3A shown in Fig. 3 (b) is rectangular. No through-holes are formed in the metal plate 3A.
The heat transfer plates 2A and 2B and the metal plates 3A and 3B have high thermal conductivity and are, for example, metal plates made of the same material. These metal plates are, for example, aluminum, stainless, copper, aluminum alloy, titanium, or magnesium alloy.
The manufacture of the heat exchanger 10 is performed, for example, in the following order. For example, a plurality of metal plates 3A (Fig. 3 (b)), a plurality of metal plates 3B (Fig. 3 (a)), a plurality of metal plates 2A (Fig. 2 (a)), and a plurality of metal plates 2B (Fig. 2 (b)) are each prepared. Next, the metal plate 2A (Fig. 2 (a)) and the metal plate 2B (Fig. 2 (b)) are alternately stacked on a plurality of metal plates 3A stacked (Fig. 3 (b)), and a plurality of metal plates 3B (Fig. 3 (a)) is further stacked thereon. After that, the metal plates 3A, 2A, 2B, and 3B stacked in the stacking direction are pressed from the stacking direction and are diffusion-joined to each other in a high-temperature vacuum atmosphere.
After the diffusion joining, the through-holes 212A formed in the plurality of metal plates 2A and the through-holes 212B formed in the plurality of metal plates 2B are in communication with each other, such that the space 21 is formed. The through-holes 222A formed in the plurality of metal plates 2A and the through-holes 222B formed in the plurality of metal plates 2B are in communication with each other, such that the space 22 is formed. The through-holes 232A formed in the plurality of metal plates 2A and the through-holes 232B formed in the plurality of metal plates 2B are in communication with each other, such that the space 23 is formed. The through-holes 242A formed in the plurality of metal plates 2A and the through-holes 242B formed in the plurality of metal plates 2B are in communication with each other, such that the space 24 is formed. Moreover, the flow paths 25A provided in the metal plates 2A are in communication with the spaces 21 and 22 and the flow paths 25B provided in the metal plates 2B are in communication with the spaces 23 and 24.
Moreover, after the diffusion joining, the through-holes 601 formed in the plurality of metal plates 3B are in communication with each other, such that the hole portion 61 is formed. The through-holes 602 formed in the plurality of metal plates 3B are in communication with each other, such that the hole portion 62 is formed. The through-holes 603 formed in the plurality of metal plates 3B are in communication with each other, such that the hole portion 63 is formed. The through-holes 604 formed in the plurality of metal plates 3B are in communication with each other, such that the hole portion 64 is formed.
In addition, the tube 51 is joined to the hole portion 61, the tube 52 is joined to the hole portion 62, the tube 53 is joined to the hole portion 63, and the tube 54 is joined to the hole portion 64. In such a process, the heat exchanger 10 is formed.
Fig. 4 (a) and (b) are cross-sectional views schematically showing cross-sections of the heat transfer plates. Fig. 4 (a) shows a cross-sectional structure of the metal plate 2A shown in Fig. 2 (a), which is taken along the line A1-A2. Fig. 4 (b) shows a cross-sectional structure of the metal plate 2B shown in Fig. 2 (b), which is taken along the line B1-B2.
As shown in (a) of Fig. 4, the plurality of flow paths 25A, which is arranged in the X-axis direction and extends in the Y-axis direction, is formed in the heat transfer plate 2A. A depth 2A1 of each of the plurality of flow paths 25A is 40% or more and 70% or less, favorably 50% or more and 70% or less of a plate thickness 2At of the heat transfer plate 2A. Moreover, the through-holes 232A and 242A penetrating the area between the main surface 2ua and the main surface 2da are formed in the heat transfer plate 2A. The through-holes 212A and 222A shown in Fig. 2 (a) are not shown in Fig. 4 (a).
Moreover, when a broken line 2AL is drawn along the main surface 2da of the heat transfer plate 2A to be in contact with the bottom portions 25Ab of the plurality of flow paths 25A in the heat transfer plate 2A, a region between the broken line 2AL and the main surface 2da is defined as a bottom plate portion 26A of the heat transfer plate 2A. The bottom plate portion 26A functions as a partition between the flow paths 25A of the heat transfer plate 2A and the flow paths 25B of the heat transfer plate 2B when the heat transfer plate 2A and the heat transfer plate 2B are stacked. In a case where a fluid (e.g., a high-temperature fluid) flows into the flow paths 25A, a thickness 2A2 of the bottom plate portion 26A is set to be equal to or larger than a thickness (predetermined thickness) enough to meet the pressure resistance performance to the pressure of this fluid. For example, the predetermined thickness is 0.1 mm or more. Moreover, as an example, the plate thickness 2At is 0.3 mm, the depth 2A1 is 0.2 mm, and the thickness 2A2 is 0.1 mm.
As shown in Fig. 4 (b), in the heat transfer plate 2B, the plurality of flow paths 25B is formed arranged in the Y-axis direction and extending in the X-axis direction. A depth 2B1 of each of the plurality of flow paths 25B is 40% or more and 70% or less, favorably 50% or more and 70% or less of a plate thickness 2Bt of the heat transfer plate 2B. Moreover, the through-holes 212B and 222B penetrating between the main surface 2ub and the main surface 2db are formed in the heat transfer plate 2B. The through-holes 232B and 242B shown in Fig. 2 (b) are not shown in Fig. 4 (b). In the heat transfer plate 2B, the depth 2B1 is set to be shallower than the depth 2A1 of the flow paths 25A of the heat transfer plate 2A. The plate thickness 2Bt of the heat transfer plate 2B equals the plate thickness 2At of the heat transfer plate 2A and a width of the flow path 25B in the Y-axis direction equals a width of the flow path 25A in the X-axis direction.
Moreover, when a broken line 2BL is drawn along the main surface 2db of the heat transfer plate 2B to be in contact with the bottom portion 25Bb of each of the plurality of flow paths 25B in the heat transfer plate 2B, a region between the broken line 2BL and the main surface 2db is defined as a bottom plate portion 26B of the heat transfer plate 2B. When the heat transfer plate 2A and the heat transfer plate 2B are stacked, the bottom plate portion 26B functions as a partition between the flow paths 25A of the heat transfer plate 2A and the flow paths 25B of the heat transfer plate 2B. In a case where a fluid (e.g., a low-temperature fluid) flows into the flow paths 25B, a thickness 2B2 of the bottom plate portion 26B is set to be equal to or larger than a thickness (predetermined thickness) enough to meet the pressure resistance performance to the pressure of this fluid. For example, the predetermined thickness is 0.1 mm or more. Moreover, as an example, the plate thickness 2Bt is 0.3 mm, the depth 2B1 is 0.15 mm, and the thickness 2B2 is 0.15 m.
Fig. 5 (a) to (d) are cross-sectional views schematically showing a manufacturing process in which the flow paths and the through-holes are formed in the heat transfer plate. Fig. 5 (a) and (b) show a manufacturing process in which the flow paths 25A and the through-holes 232A and 242A are formed in the heat transfer plate 2A. Fig. 5 (c) and (d) show the manufacturing process in which the flow paths 25B and the through-holes 212B and 222B are formed in the heat transfer plate 2B.
As shown in Fig. 5 (a), mask members 2Am are arranged on the main surfaces 2ua and 2da and the side surfaces 2wa in the heat transfer plate 2A before etching so that the areas where the flow paths 25A and the through-holes 232A and 242A are formed are exposed. At this time, the mask members 2Am are arranged so that the areas where the through-holes 212A and 222A are formed are also exposed.
Next, as shown in Fig. 5 (b), the heat transfer plate 2A with the mask members 2Am exposed is subjected to wet etching processing, such that the flow paths 25A and the through-holes 232A and 242A are formed on the heat transfer plate 2A. At this time, the through-holes 212A and 222A (not shown) are also formed.
In the wet etching processing of the heat transfer plate 2A, half etching from the side of the main surface 2ua is performed in the formation of the flow paths 25A, and double-side etching processing from the main surface 2ua and the main surface 2da is performed in the formation of the through-holes 212A, 222A, 232A, and 242A. Here, in the formation of the flow paths 25A, the half etching is performed, such that a metal portion with a predetermined thickness remains between the flow paths 25A and the main surface 2da, and the bottom plate portion 26A is formed on the side of the main surface 2da. The flow paths 25A and the through-holes 212A, 222A, 232A, and 242A are formed in the same etching process.
Moreover, as shown in Fig. 5 (c), mask members 2Bm are arranged on the main surfaces 2ub and 2db and the side surface 2wb in the heat transfer plate 2B before etching so that the areas where the flow paths 25B and the through-holes 212B and 222B are formed are exposed. At this time, the mask members 2Bm are arranged so that the areas where the through-holes 232B, 232B are formed are also exposed.
Next, as shown in Fig. 5 (d), the heat transfer plate 2B with the mask members 2Bm exposed is subjected to wet etching processing, such that the flow paths 25B and the through-holes 212B and 222B are formed on the heat transfer plate 2B. At this time, the through-holes 232B and 242B (not shown) are also formed.
In the wet etching of the heat transfer plate 2B, half etching from the side of the main surface 2ub is performed in the formation of the flow paths 25B and double-side etching processing from the main surface 2ub and the main surface 2db is performed in the formation of the through-holes 212B, 222B, 232B, and 242B. Here, the half etching is performed in the formation of the flow paths 25B, such that a metal portion with a predetermined thickness remains between the flow paths 25B and the main surface 2db and the bottom plate portion 26B is formed on the side of the main surface 2db. The flow paths 25B and the through-holes 212B, 222B, 232B, and 242B are formed in the same etching process.
It should be noted that the time to expose the heat transfer plate 2B to the etching solution may be set to be shorter than the time to expose the heat transfer plate 2A to the etching solution, to form the flow paths 25A, the flow paths 25B, the through-holes 212A, 222A, 232A, and 242A, and the through-holes 212B, 222B, 232B, and 242B in the same etching process. Since the time to expose the heat transfer plate 2B to the etching solution is shorter than the time to expose the heat transfer plate 2A to the etching solution, the flow paths 25B are formed to be shallower than the flow paths 25A.
In the present embodiment, the number of flow paths 25A (e.g., three) formed in the heat transfer plate 2A and the number of flow paths 25B (e.g., three) formed in the heat transfer plate 2B are the same. Moreover, the width of each flow path is set to be the same. It should be noted that the depth 2B1 of the flow paths 25B in the heat transfer plate 2B is shallower than the depth 2A1 of the flow paths 25A in the heat transfer plate 2A. Accordingly, the flow path cross-sectional area of the flow paths 25B is smaller than the flow path cross-sectional area of the flow paths 25A. The flow path cross-sectional area means an area of a cross section when the flow path is taken in a direction orthogonal to the direction in which the fluid flows in the flow path and the bottom portion of the flow path (a total area of the flow path cross-sectional area of the three flow paths).
Accordingly, for example, in a case where a homogeneous fluid flows into the flow paths 25A of the heat transfer plate 2A and the flow paths 25B of the heat transfer plate 2B at the same flow rate, the flow velocity of the fluid that flows in the flow path A with a larger flow path cross-sectional area becomes lower than the flow velocity of the fluid that flows in the flow path B. Accordingly, the overall heat transfer coefficient of the fluid that flows in the flow path A decreases. Moreover, the pressure loss of the fluid that flows in the flow path A with a larger flow path cross-sectional area becomes smaller than the pressure loss of the fluid that flows in the flow path B.
In the present embodiment, for example, as the fluid, water is made to pass through the flow paths 25A with a larger flow path cross-sectional area and a refrigerant is made to pass through the flow paths 25B. In this case, when the water is made to pass through the flow paths 25A as compared to the time when the water is made to pass through the flow paths 25B, the flow velocity relatively decreases. Thus, the heat transfer coefficient of the water made to pass through the flow paths 25A relatively decreases.
However, considering the heat transfer coefficients of the water and the refrigerant, the heat transfer coefficient of the water is greater than the heat transfer coefficient of the refrigerant. Therefore, even if the heat transfer coefficient of the water relatively decreases, it does not affect the overall heat transfer coefficient of the heat exchanger as a whole. It is because the overall heat transfer coefficient of the heat exchanger as a whole is significantly affected by a fluid with a lower heat transfer coefficient.
Moreover, since the pressure loss of the fluid that flows in the flow path A decreases, the power for circulating the fluid that flows in the flow path A can be reduced.
Moreover, in the present embodiment, the flow path is formed to have a depth that is 40% or more and 70% or less of the plate thickness of the heat transfer plate by etching. For example, the plate thicknesses of the heat transfer plates 2A and 2B are both 0.3 mm. As an example, the depth 2A1 of the flow paths 25A of the heat transfer plate 2A is 0.2 mm and the depth 2B1 of the flow paths 25B of the heat transfer plate 2B is 0.15 mm. Therefore, even if the etching time is set to the time required to form the flow paths, the through-holes can be formed by the double-side etching and the through-holes and the flow paths can be formed in the same etching process. Thus, the increase in manufacturing costs is suppressed without requiring another process to form the through-holes.
Moreover, in the present embodiment, the bottom plate portion of the heat transfer plate is formed to have a thickness enough to meet the pressure resistance performance to the pressure of the fluid. For example, the thickness 2A2 of the bottom plate portion 26A of the heat transfer plate 2A is 0.1 mm and the thickness 2B2 of the bottom plate portion 26B of the heat transfer plate 2B is 0.15 mm. Thus, the thickness of the bottom plate portion is not excessive, and the increase in material costs is suppressed. Moreover, with the bottom plate portion with this thickness, the increase in thermal resistance due to the bottom plate portion is suppressed, and the deterioration of the heat exchange performance of the heat exchanger is suppressed.
Fig. 6 is a cross-sectional view schematically showing another example of the heat transfer plate.
The plate thickness of the heat transfer plate 2A may be different from the plate thickness of the heat transfer plate 2B. For example, the heat transfer plate 2B shown in Fig. 6, a plate thickness 2Bta is smaller than the plate thickness 2At of the heat transfer plate 2A. Also in that case, the bottom plate portion 26B is formed to have a thickness enough to meet pressure resistance performance to the pressure of the flowing fluid. For example, a thickness 2B2a of the bottom plate portion 26B is set to be 0.1 mm or more.
Moreover, also in the heat transfer plate 2B shown in Fig. 6, the depth 2B1a of each of the plurality of flow paths 25B is set to be 40% or more and 70% or less, favorably 50% or more and 70% or less of the plate thickness 2Bta of the heat transfer plate 2B. As an example, the plate thickness 2Bta is 0.2 mm, the depth 2B1a is 0.1 mm, and the thickness 2B2a is 0.1 m.
By setting the plate thickness of the heat transfer plate 2B to be smaller than the plate thickness of the heat transfer plate 2A in this manner, the increase in material costs is further suppressed. Moreover, also in this modified example, the flow paths 25B are formed to have a depth that is 40% or more and 70% or less of the plate thickness of the heat transfer plate 2B by etching, so the through-holes 212B, 222B, 232B, and 242B can be formed in the same etching process as the flow paths 25B by the double-side etching. Accordingly, the increase in manufacturing costs is suppressed without requiring another process to form the through-holes.
Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment and various modifications can be made as a matter of course. For example, the plate thickness of the heat transfer plate 2A and the plate thickness of the heat transfer plate 2B may be the same and the depth of the flow paths 25A and the depth of the flow paths 25B may be the same. In this case, each flow path is formed to have a depth that is 40% or more and 70% or less of the plate thickness of the heat transfer plate. Also in that case, the through-holes and the flow paths can be formed in the same etching process by using the double-side etching for forming the through-holes. The respective embodiments are not limited to independent forms and may be combined as far as technically possible.

Reference Signs List

1u, 1d, 2ua, 2ub, 2da, 2db, 3u, 3d main surface
1w, 2wa, 2wb side surface
2 laminate
2A, 2B, 3A, 3B metal plate
2Am, 2Bm mask member
10 heat exchanger
21, 22, 23, 24 space
25A, 25B flow path
25Ab, 25Bb bottom portion
26A, 26B bottom plate portion
51, 52, 53, 54 tube
61, 62, 63, 64 hole portion
212A, 212B, 222A, 222B, 232A, 232B, 242A, 242B through-hole
601, 602, 603, 604 through-hole
2At, 2Bt, 2Bta plate thickness
2AL, 2BL broken line
2A1, 2B1 depth
2A2, 2B2, 2B2a thickness

Claims

A heat exchanger formed by stacking a plurality of heat transfer plates, wherein
the plurality of heat transfer plates includes a first heat transfer plate and a second heat transfer plate and the first heat transfer plate and the second heat transfer plate are alternately stacked,

a first flow path is formed in the first heat transfer plate and a second flow path is formed in the second heat transfer plate, and

the second flow path has a flow path cross-sectional area smaller than a flow path cross-sectional area of the first flow path.
The heat exchanger according to claim 1, wherein
the second heat transfer plate has a plate thickness different from a plate thickness of the first heat transfer plate.
The heat exchanger according to claim 1, wherein
the second heat transfer plate has a plate thickness smaller than a plate thickness of the first heat transfer plate.
The heat exchanger according to claim 1, wherein
each of the first heat transfer plate and the second heat transfer plate includes a bottom plate portion, the bottom plate is a partition between the first flow path and the second flow path, and the bottom plate portion has a thickness equal to or larger than a predetermined thickness.
The heat exchanger according to claim 4, wherein the predetermined thickness is 0.1 mm or more.
The heat exchanger according to claim 1, wherein
the first flow path has a depth that is 40% or more and 70% or less of a plate thickness of the first heat transfer plate, and

the second flow path has a depth that is 40% or more and 70% or less of a plate thickness of the second heat transfer plate.
The heat exchanger according to claim 1, wherein
a through-hole is formed in each of the first heat transfer plate and the second heat transfer plate.
A manufacturing method for a heat exchanger according to any one of claims 1 to 7, comprising
forming the first flow path and the second flow path by etching.
The manufacturing method for a heat exchanger according to claim 8, further comprising
forming a bottom plate portion which is a partition between the first flow path and the second flow path by etching in each of the first heat transfer plate and the second heat transfer plate, the bottom plate portion being formed to have a thickness equal to or larger than a predetermined thickness.
The manufacturing method for a heat exchanger according to claim 8, further comprising:
forming a first through-holes in the first heat transfer plate by etching and forming a second through-holes in the second heat transfer plate by etching;

forming the first through-holes by a same process as an etching process of forming the first flow path; and

forming the second through-holes by a same process as an etching process of forming the second flow path.
The manufacturing method for a heat exchanger according to claim 10, further comprising
forming the first flow path, the second flow path, the first through-holes, and the second through-holes by a same etching process.