DESCRIPTION
Title of Invention
LAMINATED HEADER, HEAT EXCHANGER, AND AIR-CONDITIONING APPARATUS
Technical Field [0001]
The present invention relates to a laminated header, a heat exchanger, and an air-conditioning apparatus.
Background Art
[0002]
A laminated header configured to distribute and supply refrigerant to each heat transfer tube of a heat exchanger has hitherto been known. In this laminated header, which is configured to distribute and supply refrigerant to each heat transfer tube of the heat exchanger, there are laminated a plurality of piate-like members having formed therein distribution flow passages that are branched into a plurality of outlet flow passages for one inlet flow passage (see, for example, Patent Literature 1).
Citation List Patent Literature [0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No. Hei 9-189463 (see, for example, Fig. 1)
Summary of Invention Technical Problem [0004]
In such a laminated header, in order to ensure the performance of the heat exchanger that functions as an evaporator, keeping a ratio of flow rates of flows of liquid refrigerant that flows out of each of the plurality of outlet flow passages, that is, a

distribution ratio uniform such that the refrigerant is uniformly supplied to each heat transfer tube of the heat exchanger is crucial.
In the related-art laminated header, liquid refrigerant concentrates hin the distribution flow passages as the refrigerant repeatedly branches in the branching flow passages, and the liquid refrigerant nonuniformly flows out of the plurality of outlets of the laminated header. Then, the refrigerant is nonuniformly supplied to each heat transfer tube of the heat exchanger, leading to a problem in that the heat exchange performance of the heat exchanger is reduced.
[0005]
The present invention has been made in view of the above-mentioned problem, and has an object to obtain a compact laminated header configured to uniformly distribute refrigerant to each heat transfer tube of a heat exchanger, to thereby ensure the heat exchange performance of the heat exchanger. Further, the present invention has an object to provide the heat exchanger including the laminated header as described above. Still further, the present invention has an object to provide an air-conditioning apparatus including the heat exchanger as described above.
Solution to Problem [0006]
According to one embodiment of the present invention, there is provided a laminated header, including: a plurality of plate-like members, each of which being laminated with each other; one first opening; a plurality of second openings; and a distribution flow passage connecting the one first opening and each of the plurality of second openings to each other, the distribution flow passage including: a first passage having a straight line shape; a first branching flow passage for the first passage to branch into a plurality of passages; a second passage that has a straight line shape and is connected to each of the plurality of passages branched in the first branching flow passage; a second branching flow passage for the second passage to branch into a plurality of passages; and a third passage that has a straight line shape and is

connected to each of the plurality of passages branched in the second branching flow passage, in which refrigerant flowing into the distribution flow passage flows through the first passage and the second passage in directions opposite to and reverse to each other, and flows through the second passage and the third passage in directions opposite to and reverse to each other.
Advantageous Effects of Invention [0007]
In the laminated header according to the present invention, refrigerant flowing into the distribution flow passage flows through the first passage and the second passage in directions opposite to and reverse to each other, and flows through the second passage and the third passage in directions opposite to and reverse to each other. Thus, the laminated header can be reduced in size, and the straight portion of the distribution flow passage can have a certain length. As a result, refrigerant can be prevented from concentrating, and a distribution ratio can be uniform over the branching flow passage.
Brief Description of Drawings [0008]
[Fig. 1] Fig. 1 is a view for illustrating a configuration of a heat exchanger according to Embodiment 1 of the present invention.
[Fig. 2] Fig. 2 is an exploded perspective view of a laminated header according to Embodiment 1.
[Fig. 3] Fig. 3 is a front sectional view and a side sectional view of distribution flow passages of the laminated header according to Embodiment 1.
[Fig. 4] Fig. 4 is a graph for showing a relationship between a distribution ratio of flows of refrigerant to respective heat transfer tubes according to Embodiment 1 and L/D (L: length of straight portion S, D: inner diameter of passage).
[Fig. 5] Fig. 5 is a diagram for illustrating a configuration of an air-conditioning apparatus to which the heat exchanger according to Embodiment 1 is applied.

[Fig. 6] Fig. 6 is an exploded perspective view for illustrating Modified Example of the laminated header according to Embodiment 1.
[Fig. 7] Fig. 7 is an exploded perspective view for illustrating Comparative Example of the laminated header according to Embodiment 1.
Description of Embodiments [0009]
Now, a laminated header 2 according to the present invention is described with reference to the drawings.
In the following, there is described a case where the laminated header 2 according to the present invention distributes refrigerant flowing into a heat exchanger 1, but the laminated header 2 according to the present invention may distribute refrigerant flowing into other devices. Further, the configuration, operation, and other matters described below are merely examples, and the laminated header 2 according to the present invention is not limited to such configuration, operation, and other matters. Further, in the drawings, the same or similar components are denoted by the same reference symbols, or the reference symbols therefor are omitted. Further, the illustration of details in the structure is appropriately simplified or omitted. Further, overlapping description or similar description is appropriately simplified or omitted. [0010] Embodiment 1
The heat exchanger 1 according to Embodiment 1 of the present invention is described. Configuration of Heat Exchanges
Now, the configuration of the heat exchanger 1 according to Embodiment 1 is described.
Fig. 1 is a view for illustrating the configuration of the heat exchanger according to Embodiment 1.
As illustrated in Fig. 1, the heat exchanger 1 includes the laminated header 2, a cylindrical header 3, a plurality of heat transfer tubes 4, a retaining member 5, and a

plurality of fins 6. [0011]
The laminated header 2 includes one refrigerant inflow port 2A (corresponding to a first opening of the present invention) and a plurality of refrigerant outflow ports 2B (corresponding to a second opening of the present invention). The cylindrical header 3 includes a plurality of refrigerant inflow ports 3A and one refrigerant outflow port 3B. Refrigerant pipes of a refrigeration cycle apparatus are connected to the refrigerant inflow port 2A of the laminated header 2 and the refrigerant outflow port 3B of the cylindrical header 3. The heat transfer tubes 4 are connected between the refrigerant outflow ports 2B of the laminated header 2 and the refrigerant inflow ports 3A of the cylindrical header 3. [0012]
The heat transfer tube 4 is a flat tube or a circular tube having a plurality of flow passages formed therein. The heat transfer tube 4 is made of, for example, copper or aluminum. End portions of the heat transfer tubes 4 on the laminated header 2 side are connected to the refrigerant outflow ports 2B of the laminated header 2 under a state in which the end portions are retained by the plate-like retaining member 5. The retaining member 5 is made of, for example, aluminum. The plurality of fins 6 are joined to the heat transfer tubes 4. The fin 6 is made of, for example, aluminum. In Fig. 1, there is illustrated a case where eight heat transfer tubes 4 are provided, but the present invention is not limited to such a case. For example, two heat transfer tubes 4 may be provided. [0013]
Now, the configuration of the laminated header 2 of the heat exchanger 1 according to Embodiment 1 is described.
Fig. 2 is an exploded perspective view of the laminated header 2 according to Embodiment 1. [0015]
The laminated header 2 illustrated in Fig. 2 includes, for example, first plate-like members 111, 112, 113, 114, 115, and 116 and second plate-like members 121, 122,
123, 124, and 125 sandwiched by the first plate-like members. The plate-like members
each have, for example, a rectangular shape.
One or both surfaces of each of the second plate-like members 121, 122, 123,
124, and 125 are applied with a brazing material. The first plate-like members 111,
112, 113, 114, 115, and 116 are laminated via the second plate-like members 121, 122,
123, 124, and 125, and integrally joined together by brazing. The first plate-like
members 111, 112, 113, 114, 115, and 116 and the second plate-like members 121,
122, 123, 124, and 125 each have a thickness of from about 1 mm to about 10 mm, and
are made of aluminum, for example.
[0016]
In the laminated header 2, distribution flow passages are formed by a first passage 10A, second passages 11 A, third passages 12A, and fourth passages 13A that are circular through holes formed in the first plate-like members 111, 112, 113, 114, 115, and 116 and the second plate-like members 121, 122, 123, 124, and 125, and

branching flow passages 10B, 11B, and 12B that are substantially Z-shapecf through grooves. Each plate-like member is processed by pressing or cutting. When the plate-like member is processed by pressing, a plate having a thickness of 5 mm or less is used, which can be processed by pressing. When the plate-like member is processed by cutting, a plate having a thickness of 5 mm or more may be used. [0017]
The refrigerant pipe of the refrigeration cycie apparatus is connected to the first passage 10Aof the first plate-like member 111. The first passage 10Aof the first plate-like member 111 corresponds to the refrigerant inflow port 2A of Fig. 1. [0018]
The first passage 10A opens at substantially the centers of the first plate-like members 111, 112, and 113 and the second piate-like members 121, 122, and 123. Further, the pair of second passages 11A opens in the first plate-like member 113 and the second plate-like members 122 and 123 at positions opposed to each other across the first passage 10A.
In addition, the third passages 12A open in the first plate-like members 113 and 114 and the second plate-like members 122, 123, and 124 at four positions opposed to each other across the second passages 11 A.
Further, the fourth passages 13A open in the first plate-like member 116 and the second plate-like member 125 at eight positions. [0019]
The first passage 10A, the second passages 11 A, the third passages 12A, and the fourth passages 13A open at positions that are determined such that those passages communicate with the corresponding passages when the first plate-like members 111, 112, 113, 114, 115, and 116 and the second plate-like members 121, 122, 123, 124, and 125 are laminated. [0020]
Further, the first branching flow passage 10B is formed in the first plate-like member 114 (corresponding to first branching plate-like member of the present invention), the second branching flow passages 11B are formed in the first plate-like

member 112 (corresponding to second branching plate-like member of the present invention), and the third branching flow passages 12B are formed in the first plate-like member 115. [0021]
Here, when the plate-like members are laminated to form the distribution flow passages, the first passage 10Ais connected to the center of the first branching flow passage 10B formed in the first plate-like member 114, and the second passages 11A are connected to both the end portions of the first branching flow passage 10B.
Further, the second passages 11A are connected to the centers of the second branching flow passages 11B formed in the first piate-like member 112, and the third passages 12A are connected to both the end portions of each of the second branching flow passages 11B.
In addition, the third passages 12Aare connected to the centers of the third branching flow passages 12B formed in the first plate-like member 115, and the fourth passages 13Aare connected to both the end portions of each of the third branching flow passages 12B.
Accordingly, the distribution flow passages may be formed by laminating the first plate-like members 111, 112, 113, 114, 115, and 116 and the second plate-like members 121, 122, 123, 124, and 125 and joining the units together by brazing such that the passages are connected to the corresponding passages. [0022]
Next, the distribution flow passages and flow of refrigerant in the laminated header 2 are described.
When the heat exchanger 1 functions as the evaporator, two-phase gas-liquid refrigerant flows into the laminated header 2 through the first passage 10Aof the first plate-like member 111. The flowed refrigerant travels straight in the first passage 10A, and collides with the surface of the second plate-like member 124 in the first branching flow passage 10B of the first plate-like member 114 to vertically branch in the gravity direction.

The branched refrigerant travels to each of both the end portions of the first branching flow passage 10B and fiows into the pair of second passages 11 A. [0023]
The refrigerant flowed into the second passages 11A travels straight in the second passages 11A in a direction opposite to and reverse to that of refrigerant traveling in the first passage 10A. The refrigerant collides with the surface of the second plate-like member 121 in the second branching flow passages 11B of the first plate-like member 112 to vertically branch in the gravity direction.
The branched refrigerant travels to each of both the end portions of the second branching flow passages 11B and flows into the four third passages 12A. [0024]
The refrigerant flowed into the third passages 12A travels straight in the third passages 12A in a direction opposite to and reverse to that of refrigerant traveling in the second passages 11 A. The refrigerant collides with the surface of the second plate¬like member 125 in the third branching flow passages 12B of the first plate-like member 115 to vertically branch in the gravity direction.
The branched refrigerant travels to each of both the end portions of the third branching flow passages 12B and flows into the eight fourth passages 13A. [0025]
The refrigerant flowed into the fourth passages 13A travels straight in the fourth passages 13Ain a direction opposite to and reverse to that of refrigerant traveling in the second passages 11A. Then, the refrigerant flows out of the fourth passages 13Aand flows into the plurality of heat transfer tubes 4 with uniform distribution through the passages of the retaining member 5.
In the distribution flow passages of Embodiment 1, the laminated header 2 in which refrigerant passes through the three branching flow passages and branches eight times is exemplified. However, the number of times of branching is not particularly limited. [0026]

Now, a state of a liquid film in the passages in the laminated header 2 is described with reference to Fig. 3.
Fig. 3 is a front sectional view and a side sectional view of the distribution flow passages of the laminated header according to Embodiment 1.
As illustrated in Fig. 3, the distribution flow passages for refrigerant in the laminated header 2 bend at a right angle and branch at a plurality of positions to be connected to the plurality of refrigerant outflow ports 2B. When refrigerant flows through the distribution flow passages, as illustrated in Fig. 3, a liquid film of the refrigerant concentrates in the outward direction of the passages in the bending portions and the branching portions of the passages and tends to travel on the outer peripheral side of such portions due to the centrifugal force. If the refrigerant flows into the next branching flow passages under this state, the liquid refrigerant concentratedly flows into one of the branching flow passages by a large amount. As a result, the two-phase gas-liquid refrigerant cannot be uniformly distributed to the plurality of heat transfer tubes 4. [0027]
In view of the above, in the laminated header 2 according to Embodiment 1, straight portions S having certain lengths, which are indicated by the broken lines of Fig. 2, are formed between the bending portions or the branching portions of the passages and portions at which refrigerant flows into the next branching flow passages.
Specifically, certain lengths are ensured for the first passage 10A, the second passages 11A, and the third passages 12A.
Accordingly, through formation of the straight portions S having certain lengths between the bending portions or the branching portions of the passages for refrigerant and the portions at which refrigerant flows into the next branching flow passages, concentration of a liquid fiim is eliminated in those straight portions S, and the two-phase gas-liquid refrigerant is uniformly distributed to flow into the next branching flow passages. [0028]

The index of the length of the straight portion S for rectifying a two-phase gas-liquid flow is a ratio of a value of the length L of the straight portion S to the inner diameter D of the passage, and is represented by L/D (L: length [m] of straight portion S of passage, D: inner diameter [m] of passage, illustrated in Fig. 3). A stronger rectifying effect is obtained as the length L of the straight portion S is increased or the inner diameter D of the passage is reduced. [0029]
Now, pressure loss AP of a two-phase gas-liquid flow in the straight portion S of the passage is considered.
The pressure loss AP of the two-phase gas-liquid flow in the straight portion S of the passage is expressed by the following expression (1). [0030] [Math. 1]
w = fLLpU*.f = fLLj>-GLJ$.f=2fLp9!L.f ... ci)
D2 r 52 U" D/2J V D" n1
f: friction coefficient, p: density [kg/m3], u: flow velocity [m/s], Gr: refrigerant circulating amount [kg/h], cp: enhancement factor of two-phase flow, L: length [m] of straight portion S, D: inner diameter [m] of passage [0031]
From the expression (1), it is found that when the inner diameter D of the passage is reduced in order to obtain the rectifying effect for the two-phase gas-liquid flow, contribution to increase in pressure loss AP is significantly increased. Accordingly, the length L of the straight portion S is increased so that the rectifying effect for the two-phase gas-liquid flow may be obtained while suppressing increase in pressure loss AP. [0032]
In addition, plates of the laminated header 2 of the present invention are joined together in a furnace by brazing in an integral manner. In order to prevent a brazing material from closing the passages, the passages each need to have an inner diameter

D of 2 [mm] or more, and hence the inner diameter D of the passages cannot be significantly small. Thus, it is difficult to cause refrigerant flowing through the passages to have a flow condition of homogeneous flow, e.g., annular dispersed flow, with the use of a restriction function, and hence the refrigerant flows through the passages as annular flow, slug flow, or stratified flow. As a result, the straight portions S for rectifying the two-phase gas-iiquid flow are needed. [0033]
Now, an optimal value of L/D is described with reference to Fig. 4.
Fig. 4 is a graph for showing a relationship between a distribution ratio of flows of refrigerant to the respective heat transfer tubes according to Embodiment 1, and L/D (L: length [m] of straight portion S, D: inner diameter [mj of passage).
As is understood from Fig. 4, as the length L of the straight portion of the passage is increased, a stronger rectifying effect for a liquid film is obtained, but the increase in rectifying effect remains at the same level in a range of 5
Now, the configuration of Modified Example of the laminated header 2 according to Embodiment 1 is described.
Fig. 6 is an exploded perspective view for illustrating Modified Example of the laminated header according to Embodiment 1.
The laminated header 2 includes, for example, first plate-like members 111, 112, 114, 115, and 116 and second plate-like members 121, 123, 124, and 125 sandwiched by the first piate-like members.
One or both surfaces of each of the second plate-like members 121, 123, 124, and 125 are applied with a brazing material. The first plate-like members 111, 112, 114, 115, and 116 are laminated via the second plate-like members 121, 123, 124, and 125, and integrally joined together by brazing. [0047]
In the laminated header 2, there are formed distribution flow passages configured by a first passage 10A, second passages 11 A, third passages 12A, and fourth passages 13A that are circular through holes formed in the first plate-like members 111, 113, 114, 115, and 116 and the second plate-like members 121, 123, 124, and 125, and branching flow passages 10B, 11B, and 12B that are substantially S-shaped or substantially Z-shaped through grooves. [0048]
As described above, in the laminated header 2 according to Modified Example illustrated in Fig. 6, the distribution flow passages similar to those of the laminated header 2 according to Embodiment 1 are formed, and through adjustment of the thickness of the one second plate-like member 123, the first passage 10A, which is the

straight portion S of the passage indicated by the circle of the broken lines, is set to the range of 2
Now, the configuration of Comparative Example of the laminated header 2 according to Embodiment 1 is described.
Fig. 7 is an exploded perspective view for illustrating Comparative Example of the laminated header according to Embodiment 1.
The laminated header 2 includes, for example, first plate-like members 111, 112, 113, 114, 115, 116, 117, 118, and 119 and second piate-like members 121, 122, 123, 124, 125, 126, 127, and 128 sandwiched by the first plate-like members.
One or both surfaces of each of the second plate-like members 121, 122, 123,

124, 125, 126, 127, and 128 are applied with a brazing material. The first plate-like members 111, 112, 113, 114, 115, 116, 117, 118, and 119 are laminated via the second plate-like members 121, 122, 123, 124, 125, 126, 127, and 128 and integrally joined together by brazing. [0052]
In the laminated header 2, there are formed distribution flow passages configured by a first passage 10A, second passages 11A, third passages 12A, and fourth passages 13A that are circular through holes formed in the first plate-like members 111, 112, 113, 114, 115, 116, 117, 118, and 119 and the second plate-like members 121, 122, 123, 124, 125, 126, 127, and 128, and branching flow passages 10B, 11B, and 12B that are substantially S-shaped or substantially Z-shaped through grooves. [0053]
In the distribution flow passages of the laminated header 2 according to Comparative Example illustrated in Fig. 7, unlike the laminated header 2 according to Embodiment 1 in which refrigerant flows in the opposite directions, refrigerant flows through the first passage 10A, the second passages 11 A, the third passages 12A, and the fourth passages 13Ain the same direction. [0054]
Here, in Comparative Example, when each of the first passage 10A, the second passages 11 A, and the third passages 12A, which are the straight portions S indicated by the circles of the broken lines illustrated in Fig. 7, is set to the range of 2