CN112240654B

CN112240654B - Heat exchanger, air conditioner, indoor unit, and outdoor unit

Info

Publication number: CN112240654B
Application number: CN202010684896.5A
Authority: CN
Inventors: 横关敦彦
Original assignee: Hitachi Johnson Controls Air Conditioning Inc
Current assignee: Hitachi Johnson Controls Air Conditioning Inc
Priority date: 2019-07-17
Filing date: 2020-07-16
Publication date: 2022-05-06
Anticipated expiration: 2040-07-16
Also published as: JP6878511B2; JP2021017991A; CN112240654A

Abstract

The invention provides a heat exchanger, an air conditioner, an indoor unit and an outdoor unit capable of efficiently exchanging heat. The heat exchanger has the following multiple flow paths: when functioning as a condenser, the refrigerant flows in from the gas-side inlets of the two heat transfer tubes at the spaced-apart position at one end of the third row, is discharged from the two heat transfer tubes adjacent to each other in the third row, merges at the T-joint, flows into one heat transfer tube at one end of the second row, is discharged from one heat transfer tube at one end of the second row, flows into one heat transfer tube at one end of the first row, and is discharged from the liquid-side outlets of the heat transfer tubes at one end of the first row, and the gas-side inlet of the first refrigerant flow path is adjacent to one of the gas-side inlets of the second refrigerant flow path, the second row of the first refrigerant flow paths has jumper tubes connecting the separated heat transfer tubes, the liquid-side outlet of the first refrigerant flow path is adjacent to the liquid-side outlet of the second refrigerant flow path, and the first refrigerant flow path and the second refrigerant flow path have substantially the same length.

Description

Heat exchanger, air conditioner, indoor unit, and outdoor unit

Technical Field

The present invention relates to a heat exchanger capable of efficiently exchanging heat, and an air conditioner, an indoor unit, and an outdoor unit each including the heat exchanger.

Background

From the viewpoint of energy saving, there is a demand for improvement in APF (Annual Performance Factor) in air conditioning (hereinafter, air conditioning may be omitted and referred to as "air conditioner"). Accordingly, heat exchangers for efficient air conditioning have been developed.

For example, the following techniques are disclosed: in the heat exchanger configured by a plurality of rows, the number of refrigerant passages through which the heat exchangers of the respective rows communicate decreases as the refrigerant flows from the inlet side to the outlet side of the gas cooler (for example, patent documents 1 and 2). According to patent document 1, patent document 2, and the like, the refrigerant flowing through each heat exchanger can be maintained at a flow velocity suitable for heat exchange, and efficient heat exchange can be performed.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2000-304380

Patent document 2: japanese patent No. 6351494

Disclosure of Invention

Problems to be solved by the invention

In the conventional techniques represented by

patent documents

1 and 2, the liquid refrigerant outlet side portion in the case where the heat exchanger functions as a condenser is in contact with the middle portion of the flow path of the adjacent flow path, and therefore a temperature difference occurs between the supercooled liquid refrigerant and the refrigerant in the middle two-phase state. Therefore, at the portion adjacent to the flow path, internal heat exchange loss due to heat conduction after passing through the fins occurs due to the temperature difference. In addition, when the heat exchanger of patent document 1 is used as an evaporator, the shape of the branch portion provided in the middle of each flow path is asymmetrical, and therefore, a bias flow occurs in the two-phase flow of the refrigerant, and the heat exchange efficiency is lowered. Therefore, a technique for further improving the efficiency of the heat exchanger is required.

The present invention has been made in view of the above-described problems of the conventional art, and an object thereof is to provide a heat exchanger capable of performing efficient heat exchange, and an air conditioner, an indoor unit, and an outdoor unit each including the heat exchanger.

Means for solving the problems

That is, according to the present invention, there is provided a heat exchanger having heat transfer pipe rows of a first row, a second row, and a third row in this order from an upstream side in a predetermined air blowing direction, and having a plurality of heat transfer pipes in each of the heat transfer pipe rows, wherein a refrigerant flows through a plurality of refrigerant flow paths connecting the heat transfer pipes to exchange heat,

the first refrigerant flow path and the second refrigerant flow path of the plurality of refrigerant flow paths each have the following flow paths:

when the heat exchanger functions as a condenser, the refrigerant flows in from the gas-side inlets of the two heat transfer tubes located at the position separated from the one end portion of the third row, approaches while reciprocating between the one end portion and the other end portion of the third row, and is discharged from the two heat transfer tubes adjacent to each other in the third row,

the discharged refrigerant merges at the T-joint and flows into one heat transfer pipe at one end of the second row,

the refrigerant having flowed into one heat transfer pipe at one end portion of the second row reciprocates between the one end portion and the other end portion of the second row, and is discharged from the heat transfer pipe at the one end portion of the second row,

the discharged refrigerant flows into one heat transfer pipe at one end portion of the first row, reciprocates between the one end portion and the other end portion of the first row, and is discharged from the liquid-side outflow port of the heat transfer pipe at the one end portion of the first row,

the gas-side inlet of the first refrigerant flow path is adjacent to one of the gas-side inlets of the second refrigerant flow path,

a jumper tube for connecting the separated heat transfer tubes is provided in the second row of the first refrigerant flow path,

the liquid-side outlet port of the first refrigerant flow path is adjacent to the liquid-side outlet port of the second refrigerant flow path,

the first refrigerant flow path and the second refrigerant flow path have substantially the same length.

The effects of the invention are as follows.

As described above, according to the present invention, it is possible to provide a heat exchanger capable of efficiently exchanging heat under all conditions, and an air conditioner, an indoor unit, and an outdoor unit each including the heat exchanger.

Drawings

Fig. 1 is a perspective view illustrating a general heat exchanger.

Fig. 2 is a diagram illustrating a refrigeration cycle of the air conditioner.

Fig. 3 is a diagram illustrating an example of connection of heat transfer pipes in the outdoor heat exchanger according to the present embodiment.

Fig. 4 is a perspective view showing an example of a connection state of the heat transfer pipe in the present embodiment.

Fig. 5 is a diagram showing a configuration example of an outdoor heat exchanger provided with a plurality of flow path pairs.

Fig. 6 is a diagram showing a configuration example of an outdoor heat exchanger (upper heat exchanger) provided with a subcooler.

Fig. 7 is a diagram showing a configuration example of an outdoor heat exchanger (lower heat exchanger) provided with a subcooler.

Fig. 8 is an external view of an outdoor unit showing an example of arrangement of components of an outdoor heat exchanger in the present embodiment.

Description of the symbols

1-air conditioning apparatus, 2-outdoor unit, 3-indoor unit, 4-refrigerant piping, 4G-gas refrigerant piping, 4L-liquid refrigerant piping, 20-four-way valve, 21-compressor, 22-gas header, 23-air supply fan, 24-distributor, 25-expansion valve, 26-liquid gate valve, 27-tank (reservoir), 28-liquid side distribution pipe, 29-gas gate valve, 31-expansion valve, 32-distributor, 33-gas header, 34-air supply fan, 35-liquid side distribution pipe, 100-heat exchanger, 100' -heat exchange section, 101-heat transfer pipe, 102-fin, 103-joint, 103T-joint, 103J-jumper pipe, 200-outdoor heat exchanger, 201-subcooler, 202-subcooler, 300-indoor heat exchanger.

Detailed Description

The present invention will be described below with reference to embodiments, but the present invention is not limited to the embodiments described below. In the drawings referred to below, the same reference numerals are used for the common elements, and the description thereof will be appropriately omitted.

Fig. 1 is a perspective view showing a general heat exchanger 100. Fig. 1 (a) shows a heat exchange unit 100 'including a plurality of heat transfer tubes 101 and a plurality of fins 102, and fig. 1 (B) shows a heat exchanger 100 including a heat transfer tube 101 of the heat exchange unit 100' connected to a joint 103.

As shown in fig. 1 (a), the heat exchange portion 100' of the heat exchanger 100 includes a plurality of heat transfer tubes 101 through which refrigerant flows in the x-axis direction. Fig. 1 (a) shows an example of a heat exchanging portion 100' having the following structure: eight layers of heat transfer tubes 101 are arranged in three rows in the y-axis direction at equal intervals in the z-axis direction. In the following description, the rows of the heat transfer tubes 101 are referred to as "first row", "second row", and "third row" in terms of the direction from the near side to the far side in the y-axis direction. The heat transfer tubes 101 in the second row are "staggered" in the z-axis direction relative to the heat transfer tubes 101 in the first and third rows by a pitch that is half the pitch of the arrangement interval of the heat transfer tubes 101. This makes it possible to meander the flow of air flowing through the heat exchanging portion 100', and to guide the intake air, which has a small temperature change due to heat exchange in the previous row, to the periphery of the heat transfer tubes in the next row, thereby improving the heat exchange efficiency.

The fins 102 are arranged at equal intervals in the x-axis direction and are in contact with the heat transfer tube 101. This allows the air flowing between the fins 102 to exchange heat with the refrigerant flowing through the heat transfer tubes 101.

As shown in fig. 1 (B), the heat exchanger 100 is configured by connecting heat transfer tubes 101 of the heat exchange unit 100' shown in fig. 1 (a) to each other by joints 103. In the heat exchanger 100, the heat transfer tubes 101 are also connected by the joint 103 on the back side in the x-axis direction. The heat transfer tubes 101 in the lowermost layer in the first row are connected to liquid refrigerant piping, and the heat transfer tubes 101 in the uppermost layer in the third row are connected to gas refrigerant piping. This forms a flow path for the refrigerant, and the refrigerant can flow through the heat transfer tubes 101 of the heat exchanger 100 while reciprocating in the x-axis direction.

The joint 103 is a connection pipe connected to the heat transfer pipe 101, and can change the direction in which the refrigerant flows. The joint 103 can be selected from various shapes according to the application, and for example, a U-shape, an elbow shape, a trident shape, or the like can be used.

In the following, for convenience of describing the structure of the heat exchanger 100 by distinguishing both ends of the heat transfer pipe 101, reference is made to the front side facing the x-axis direction as the "front side" of the heat exchanger 100, and reference is made to the rear side facing the x-axis direction as the "rear side" of the heat exchanger 100. That is, in fig. 1 (a) and (B), the end portion of the heat transfer tube 101 and the joint 103 are visible as "front faces".

The direction of refrigerant flow is reversed depending on whether heat exchanger 100 functions as an evaporator or a condenser. When the heat exchanger 100 functions as an evaporator, a liquid refrigerant flows in from the lowermost heat transfer tubes 101 in the first row connected to the liquid refrigerant pipe, flows through the heat transfer tubes 101 to exchange heat, and flows out from the uppermost heat transfer tubes 101 in the third row to the gas refrigerant pipe. When the heat exchanger 100 functions as a condenser, the gaseous refrigerant flows in from the uppermost heat transfer tubes 101 in the third row connected to the gas refrigerant pipe, flows through the heat transfer tubes 101 to exchange heat, and flows out from the lowermost heat transfer tubes 101 in the first row to the liquid refrigerant pipe.

The present invention will be described below based on the structure of a general heat exchanger 100 shown in fig. 1, but the present invention is not particularly limited to the embodiment. Therefore, the number, arrangement, number of layers, number of rows, and the like of the heat transfer tubes 101 included in the heat exchanger 100 are not limited to the example shown in fig. 1, and may be arbitrary.

Next, the refrigeration cycle will be explained. Fig. 2 is a diagram illustrating a refrigeration cycle of the air conditioner 1. The air conditioner 1 includes an outdoor unit 2 and an indoor unit 3. In the air conditioning apparatus 1 shown in fig. 2, the outdoor unit 2 is installed outside the building, and the indoor units 3 are installed in a room to be air-conditioned. The outdoor unit 2 and the indoor units 3 are connected to each other via refrigerant pipes 4 through which a refrigerant flows. The refrigerant pipe 4 includes a gas refrigerant pipe 4G through which a gaseous refrigerant (gas refrigerant) flows and a liquid refrigerant pipe 4L through which a liquid refrigerant (liquid refrigerant) flows.

The outdoor unit 2 includes a four-way valve 20, a tank (accumulator) 27, a compressor 21, a gas header 22, a blower fan 23, an outdoor heat exchanger 200, a liquid-side distribution pipe 28, a distributor 24, an expansion valve 25, a liquid gate valve 26, and a gas gate valve 29. The compressor 21 compresses a refrigerant of a gas in a low-temperature and low-pressure state to change the refrigerant into a gas in a high-temperature and high-pressure state. The gas header 22 distributes the gas refrigerant of one flow path to a plurality of flow paths, or concentrates the gas refrigerant of a plurality of flow paths to one flow path. The number of branches of the gas manifold 22 is not limited to the number shown in fig. 2, and may be any number.

The outdoor heat exchanger 200 exchanges heat between the refrigerant and outdoor air. During the cooling operation of the air conditioner 1, the outdoor heat exchanger 200 functions as a condenser. In one embodiment of the present invention described below, a part of the outdoor heat exchanger 200 can be used as the

subcoolers

201 and 202.

The air-sending fan 23 sends air so that the outside air flows through the outdoor heat exchanger 200. The liquid-side distribution pipe 28 and the distributor 24 distribute the liquid refrigerant of one flow path to a plurality of flow paths or collect the liquid refrigerant of a plurality of flow paths into one flow path. The number of branches of the liquid-side distribution pipe 28 and the distributor 24 is not limited to the number shown in fig. 2, and may be any number. The expansion valve 25 is controlled to be in a fully open state during cooling and the refrigerant flows as it is, but reduces the pressure of the refrigerant during heating to control the evaporation pressure and the outlet state of the evaporator. The liquid gate valve 26 is used in a closed state during checking of airtightness of piping and indoor units during construction and during evacuation together with the gas gate valve 29, and is operated in a fully open state after completion of construction work, and during operation, the refrigerant flows as it is.

The indoor unit 3 includes an expansion valve 31, a distributor 32, a liquid-side distribution pipe 35, an indoor heat exchanger 300, a gas manifold 33, and a blower fan 34. The expansion valve 31, the distributor 32, the air manifold 33, and the blower fan 34 are the same as those described in the outdoor unit 2, and therefore, description thereof is omitted. The indoor heat exchanger 300 exchanges heat between the refrigerant and indoor air. During the cooling operation of the air conditioner 1, the indoor heat exchanger 300 functions as an evaporator.

The refrigerant pipe 4 is a pipe for passing the refrigerant between the indoor unit 3 and the outdoor unit 2. The gas gate valve 29 of the outdoor unit 2 and the gas header 33 of the indoor unit 3 are connected by a gas refrigerant pipe 4G. The liquid gate valve 26 of the outdoor unit 2 and the expansion valve 31 of the indoor unit 3 are connected by the liquid refrigerant pipe 4L. Note that, in fig. 2, the direction of movement of the refrigerant when the air conditioner 1 performs the cooling operation is shown by the shear lines shown along the

refrigerant pipes

4G and 4L. The direction of movement of the refrigerant can be reversed by the four-way valve 20, and the cooling operation and the heating operation can be switched.

Hereinafter, a refrigeration cycle of the air conditioner 1 will be described by taking a case where a cooling operation is performed as an example. In the heating operation, the flow of the refrigerant is reversed by the switching four-way valve 20, and the roles of the indoor heat exchanger and the outdoor heat exchanger are reversed.

The compressor 21 compresses a gas refrigerant in a low-temperature and low-pressure state to a high-temperature and high-pressure state, and discharges the compressed gas refrigerant. The gas refrigerant discharged from the compressor 21 flows through the four-way valve 20, is branched into a plurality of flow paths by the gas header 22, and flows into the outdoor heat exchanger 200. The gas refrigerant flowing into the outdoor heat exchanger 200 exchanges heat with the outside air supplied by the blower fan 23, condenses, and turns into a liquid refrigerant. The liquid refrigerant flows through the liquid-side distribution pipe 28, merges into one flow path by the distributor 24, passes through the expansion valve 25 and the liquid gate valve 26, flows through the refrigerant pipe 4L, is conveyed, and flows into the indoor unit 10.

The liquid refrigerant is depressurized in the expansion valve 31 of the indoor unit 3 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant. Thereafter, the refrigerant is distributed into a plurality of flow paths by the distributor 32 and the liquid-side distribution pipe 35, flows into the indoor heat exchanger 300, and exchanges heat with the indoor air supplied from the blower fan 34. When the refrigerant exchanges heat in the indoor heat exchanger 300, the refrigerant evaporates to become a gas refrigerant, and the latent heat of evaporation of the refrigerant is used to cool the air supplied by the air blowing fan 13 and to send the air as cold air into the room.

The gas refrigerant after heat exchange is carried through the gas refrigerant pipe 4G after merging the flow paths by the gas header 33, passes through the gas gate valve 29 of the outdoor unit 2, adjusts the temporarily generated excessive liquid return in the tank (accumulator) 27, and then flows into the compressor 21. By repeating the above steps, a refrigeration cycle is configured, and the air conditioner 1 can perform a cooling operation to bring the interior of the room to a desired temperature.

The movement of the refrigerant and the like in the present embodiment will be described below by taking a case where the air conditioner 1 performs a cooling operation as an example. In the following description, the outdoor heat exchanger 200 is described as an example of the heat exchanger 100, but the present invention is not limited to the embodiment, and the indoor heat exchanger 300 may be used. Fig. 3 is a diagram illustrating an example of connection of the heat transfer pipe 101 in the outdoor heat exchanger 200 according to the present embodiment. Fig. 3 is a plan view of the front surface of the outdoor heat exchanger 200 projected thereon, and illustrates the movement of the refrigerant in the outdoor heat exchanger 200 when the air conditioner 1 performs the cooling operation. That is, the outdoor heat exchanger 200 shown in fig. 3 functions as a condenser.

In the outdoor heat exchanger 200 shown in fig. 3, the rows of the eight-stage heat transfer tubes 101 are formed by three rows, as an example. In the following description, for convenience of explanation, the nth column is denoted by "Cn", the mth layer from the top is denoted by "Rm", and the heat transfer pipe 101 located at the mth position from the top in the nth column is denoted by (Cn, Rm).

The heat transfer tubes 101 of the outdoor heat exchanger 200 shown in fig. 3 are connected by joints 103. In fig. 3, the joint 103 is indicated by solid lines and broken lines connecting the heat transfer tubes 101. The solid line shows the joint 103 connected to the heat transfer pipe 101 at the front surface of the outdoor heat exchanger 200, and the broken line shows the joint 103 connected to the heat transfer pipe 101 at the rear surface of the outdoor heat exchanger 200. The bent portion on the back side of each flow path may be formed by bending the heat transfer tube 101 instead of the joint 103. This eliminates the need to braze the heat exchanger tube 101 and the joint 103 to the back surface side. For example, by configuring the heat transfer tube 101 to have a bent portion on the back surface side, the brazed portions of the joints 103 can be concentrated only on the front surface side, and the number of steps in manufacturing can be reduced.

The term "adjacent" used for the heat transfer tubes 101 in the description of the present embodiment refers to the heat transfer tubes 101 located around one heat transfer tube 101. That is, the adjacent heat transfer tubes 101 in fig. 3 include not only the vertically adjacent heat transfer tubes 101 in the same row but also the heat transfer tubes 101 located at positions shifted by half the pitch vertically in the adjacent row. For example, the heat transfer pipe 101 adjacent to (C2, R4) includes (C1, R3), (C1, R4), (C3, R3), (C3, R4) in the row adjacent to C2 in addition to (C2, R3), (C2, R5) in the same row.

In the outdoor heat exchanger 200 of the present embodiment, as shown in fig. 3, there are two refrigerant flow paths. First, the refrigerant flowing through the first flow path will be described. The gas refrigerant distributed by the gas header 22 flows in from (C3, R1) and (C3, R4), and moves between the heat transfer tubes 101 while reciprocating in the x-axis direction. Then, (C3, R2), (C3, R3), and (C2, R3) adjacent to each other are connected by a T-joint 103T, and the hot refrigerants merge into one flow path at (C2, R3).

The refrigerant merged at (C2, R3) descends while flowing through the heat transfer tubes 101, and then flows from (C2, R6) to (C2, R2). The (C2, R6) and (C2, R2) can be connected by a jumper tube 103J having a U-shape and a long side in the z-axis direction. In this way, the heat transfer tubes 101 located at the separated positions in the same row can be connected to each other by using the jumper tubes 103J.

Thereafter, the refrigerant moves to (C2, R1) and (C1, R1), and flows from (C1, R2) to the distributor 24 associated with the liquid-side distributor pipe 28. Further, while the refrigerant flows through the first flow path, the refrigerant exchanges heat with the air flowing through the heat exchanging portion 100', condenses from a superheated gas state, gradually decreases in dryness in a gas-liquid two-phase state, and finally flows out as a liquid refrigerant.

Next, the refrigerant flowing through the second flow path will be described. The gas refrigerant distributed by the gas header 22 flows in from (C3, R5) and (C3, R8) adjacent to (C3, R4) as the inlet of the gas refrigerant of the first flow path, and moves between the heat transfer tubes 101 while reciprocating in the x-axis direction. Then, (C3, R6), (C3, R7), and (C2, R7) adjacent to each other are connected by the T-joint 103T, and the refrigerants merge into one flow path in (C2, R7).

The refrigerant merged at (C2, R7) flows through joint 103 connecting (C2, R8) and (C1, R8), and moves to the first row. Thereafter, the refrigerant flows through the heat transfer tubes 101 from (C1, R8) and rises to (C1, R3). The refrigerant flows from (C1, R3) adjacent to (C1, R2) serving as an outlet port of the liquid refrigerant of the first flow path to the distributor 24 connected to the liquid-side distribution tube 28. In addition, as in the first flow path, the refrigerant condenses while flowing through the second flow path by exchanging heat with the air flowing through the heat exchanging portion 100', and changes from a gas phase to a liquid phase.

Each flow channel of the present embodiment has a structure in which gas inlets and outlets of the refrigerant are adjacent to each other. That is, as shown in fig. 3, (C3, R4) as one of the gas refrigerant inlets of the first channel is adjacent to (C3, R5) as one of the gas refrigerant inlets of the second channel, and (C1, R2) as the liquid refrigerant outlet of the first channel is adjacent to (C1, R3) as the liquid refrigerant outlet of the second channel. With such a structure, the temperature difference of the refrigerant between the respective channels in the vicinity of the gas inlet and the outlet can be reduced, and thus the internal heat exchange loss due to heat conduction via the fins 102 can be reduced.

With the structure shown in fig. 3, at least one of the heat transfer tubes adjacent to each other in the vertical direction is a gas inlet or a liquid outlet, and therefore, the refrigerant temperature is substantially equal, and the heat transfer loss after passing through the fins 102 is minimized. That is, since sensible heat changes on the gas side and the liquid side during heat radiation of the condenser, the temperature of the refrigerant changes during heat radiation, and thus, the adjacent connection between the inlet and the outlet of the other flow path contributes to prevention of useless heat exchange between the flow paths.

The number of heat transfer tubes 101 through which the refrigerant flows in the first and second channels shown in fig. 3 (hereinafter referred to as "the number of channels") is equal to 12, respectively. In particular, the number of passages on the upstream side of the T-joint 103T (from the gas refrigerant inlet to the merging portion) is two for each of the first and second flow paths, and the number of passages on the downstream side of the T-joint 103T (from the merging portion to the liquid refrigerant outlet) is 8 for each. By making the length of the first flow path substantially the same as that of the second flow path in this way, the heat exchange amount of each heat transfer tube 101 can be made substantially uniform, and the refrigerant can be distributed uniformly, so that efficient heat exchange can be performed. The phrase "the lengths of the flow paths are substantially the same" as used herein includes not only the case where the number of passages in each flow path is the same but also the case where the difference between the number of passages is one.

In the present embodiment shown in fig. 3, in the second row of the first flow path, (C2, R2) is connected to the heat transfer pipe 101(C2, R6), and the heat transfer pipe 101(C2, R6) is located at a position separated by 2 or more layers across the heat transfer pipe 101 connected to the T-joint 103T. That is, the heat transfer tubes 101 connected so as to straddle the heat transfer tube 101 connected to the T-joint 103T are provided in the same row. Thus, the first channel can have a channel length. By providing the structure having the bridge portion in this way, the gas inlets and the gas outlets of the refrigerant in the respective flow paths can be adjacent to each other, and the number of passages in the respective flow paths can be made the same.

However, in the case of causing the general heat exchanger 100 to function as a condenser, the refrigerant condenses as it goes along the flow path, the dryness decreases, and the average density increases. When the density of the refrigerant increases, the flow velocity of the refrigerant decreases, and the heat transfer rate in the heat transfer tubes 101 decreases. Therefore, the performance as a condenser is reduced, which in turn leads to a reduction in the efficiency of heat exchange.

On the other hand, as shown in fig. 3, by joining the gas refrigerant flowing in from the plurality of inlets by the T-joint 103T, it is possible to suppress a decrease in the flow velocity of the refrigerant due to condensation, and to improve the efficiency of heat exchange.

In fig. 3, the T-joint 103T connects two heat transfer tubes 101 adjacent vertically in the third row with one heat transfer tube 101 adjacent to the two heat transfer tubes in the second row. That is, the T-joint 103T may have a line-symmetric shape with respect to a line parallel to the y-axis. By using the T-shaped joint 103T having such a symmetrical shape, in the case where the heat exchanger 100 is caused to function as an evaporator (the refrigerant flows in the direction opposite to the direction shown in fig. 3, and the refrigerant is branched by the T-shaped joint 103T), the gas-liquid two-phase flow can be prevented from being biased by the vertically colliding structure. Therefore, according to the heat exchanger 100 of the present embodiment, the performance as an evaporator can be improved.

Also, as shown in fig. 3, the air flowing through the heat exchanger 100 flows in a direction from the first row toward the third row. On the other hand, in the case where the heat exchanger 100 functions as a condenser, the refrigerant flows in a direction from the third row toward the first row. Therefore, when the heat exchanger 100 functions as a condenser, a so-called counterflow refrigerant flow path is formed in which the inflow direction of air and the refrigerant flow path direction substantially face each other. By configuring such a counter-flow arrangement, the difference between the inlet temperature of air and the outlet temperature of refrigerant is reduced, and thus efficient heat exchange is possible.

Further, since the outdoor heat exchanger 200 shown in fig. 3 has a structure including three rows of eight heat transfer tubes 101, the number of heat transfer tubes 101 is twenty-four. Therefore, the number of passages of the first channel can be made equal to the number of passages of the second channel. However, this is not limited to the embodiment, and the difference between the number of passages of the first channel and the number of passages of the second channel may be equal to or less than a predetermined number. For example, the allowable difference in the number of passages may be obtained by a ratio to the number of heat transfer tubes 101 constituting the heat exchanger 100. In addition, as described above, when the turn-back portion of the flow path on the back side is formed by the bent portion of the heat transfer tube 101 instead of the joint 103, the predetermined number as the allowable difference in the number of passages is an even number, and the lowest difference is two passages.

Even if the number of rows included in the outdoor heat exchanger 200 is other than the number shown in fig. 3, the same configuration can achieve the above-described effects. That is, if the number of rows is 3 or more, the inlet ports and the outlet ports of the refrigerant of the respective channels can be adjacent to each other and the number of passages of the respective channels can be made the same by using the T-joint 103T and the jumper tube 103J.

Fig. 4 is a perspective view showing an example of the connection state of the heat transfer pipe 101 in the present embodiment. The front side of the outdoor heat exchanger 200 shown in fig. 3 is shown in perspective in fig. 4. As shown in fig. 4, in the T-joint 103T, the flow path on the liquid refrigerant side (C2 side) and the flow path on the gas refrigerant side (C3 side) preferably intersect perpendicularly. Accordingly, when the heat exchanger 100 is caused to function as an evaporator, the refrigerant in each flow path vertically collides with the T-joint 103T, and the gas-liquid two-phase flow can be equally distributed to the two flow paths, thereby providing an effect of improving the refrigerant distribution in the evaporator.

However, fig. 3 shows, as an example, the heat exchanger 100 including one pair of flow paths, in which the number of flow paths of the refrigerant is 2 when counted on the liquid side, and the embodiment is not particularly limited. For example, the number of flow paths can be appropriately selected and designed according to the type of refrigerant used, various sizes of heat exchangers, or operating environment. The number of passages of each flow path can be arbitrarily designed by selecting the connection thereof according to the number of heat transfer tubes 101 constituting the heat exchanger 100, the number of rows, the number of layers, the width of the heat exchanger 100, and the like. Therefore, the heat exchanger 100 may be configured to include a plurality of pairs of flow paths shown in fig. 3. Fig. 5 is a diagram showing a configuration example of the outdoor heat exchanger 200 provided with a plurality of flow path pairs.

The outdoor heat exchanger 200 shown in fig. 5 includes first to sixth flow paths, and includes 3 pairs of the flow paths shown in fig. 3. By configuring the outdoor heat exchanger 200 as shown in fig. 5, gas refrigerant inlets other than the gas refrigerant inlets (C3, R1) on the upper side of the first channel and the gas refrigerant inlets (C3, R24) on the lower side of the sixth channel can be adjacent to the gas refrigerant inlets of the other channels. This makes it possible to reduce the internal heat exchange loss due to heat conduction via the fins 102 while keeping the number of passages in each flow path the same, and to further improve the efficiency of heat exchange.

In the explanation drawings for explaining the present embodiment described above, an example is shown in which the fins 102 contacting the heat transfer tubes 101 in each row are continuously arranged in the row direction, but this is not limitative to the embodiment. For example, the fins 102 may be divided for each row (in the y-axis direction) of C1, C2, C3, and the like. In the case of such a configuration, heat conduction after passing through the fins 102 does not occur between the rows, and internal heat exchange loss due to heat conduction can be further reduced.

Further, by configuring the liquid-side distribution pipe 28 to have a plurality of similar pairs of flow paths as shown in fig. 5, the distribution adjustment performed between the distributor 24 and the outdoor heat exchanger 200 shown in fig. 2 can be set to be uniform. Accordingly, in both cases where the heat exchanger 100 functions as an evaporator and a condenser, the refrigerant can be distributed substantially equally even when the refrigerant circulation amount and the operating pressure are varied, and a highly efficient operation can always be performed.

Here, the distribution adjustment by the liquid-side distribution pipe means adjustment based on flow path resistance by providing a difference between the inner diameter of the distribution pipe and the length thereof for each flow path, and particularly in the case of optimizing the distribution pipe in accordance with the condition that the heat exchanger 100 functions as an evaporator, since the distribution pipe flows as a high-density liquid refrigerant in the case of functioning as a condenser, the flow velocity in the liquid distribution pipe decreases, and the resistance as the adjustment mechanism thereof becomes small. Therefore, in the case where the number of passages of each flow path is different as in the conventional technique, it is necessary to change the resistance for each flow path, and in such a case, a condition that the refrigerant distribution is likely to be deteriorated occurs depending on the operation condition such as the case of operating as a condenser. Therefore, in the heat exchanger of the present embodiment in which the lengths of the respective flow paths can be equalized, good refrigerant distribution can be achieved under all operating conditions, and high-efficiency heat exchange can be achieved.

In addition, with the configuration of fig. 5, even if the heat exchanger 100 is increased in size and the number of pairs of flow paths is increased, the refrigerant can be distributed equally for each pair of flow paths under various operating conditions, and therefore, efficient heat exchange is possible, and the heat exchanger can be used also in the large-capacity air conditioner 1. In particular, in the outdoor heat exchanger 200 in the large-capacity air conditioner 1, a part thereof may be configured as a subcooler in order to improve the performance in both the cooling operation and the heating operation. Hereinafter, an outdoor heat exchanger including a subcooler will be described with reference to fig. 6 and 7.

Fig. 6 and 7 are diagrams showing a configuration example of the outdoor heat exchanger 200 provided with the

subcoolers

201 and 202. Fig. 6 shows an upper heat exchanger 200a, fig. 7 shows a lower heat exchanger 200b, and one outdoor heat exchanger 200 is configured by disposing the lower heat exchanger 200b of fig. 7 below the upper heat exchanger 200a of fig. 6. The arrow lines in fig. 6 and 7 show the direction of movement of the refrigerant when the outdoor heat exchanger 200 functions as a condenser. The heat exchanger shown in fig. 6 and 7 also has the same structure as the heat exchanger shown in fig. 3 and the like. That is, in the heat exchanger shown in fig. 6 and 7, the gas inlets and outlets of the refrigerant in the respective channels are adjacent to each other by the jumper tubes 103J, and the number of channels is substantially the same in the respective channels, thereby constituting the counterflow refrigerant channels.

The heat exchanger 200 may be configured such that the fin 102 is divided between the upper heat exchanger 200a and the lower heat exchanger 200 b. Here, by dividing the upper heat exchanger 200a and the lower heat exchanger 200b, even in the case where the heat exchanger 200 having a size of the upper limit height or more is required due to the restrictions of the manufacturing apparatus, the heat exchanger can be provided. The heat transfer pipe 101 included in the region indicated by the dotted line in fig. 6 and 7 functions as

subcoolers

201 and 202.

In the heat exchanger 200, as shown in fig. 6, for example, a subcooler 201a is provided between the expansion valve 25 and the upper distributor 24a so as to form a flow path through the heat transfer pipe 101 in a part of the upper heat exchanger 200 a. As shown in fig. 6, a subcooler 201b is provided between the expansion valve 25 and the lower distributor 24b to form a flow path through which the heat transfer tubes 101 in a part of the upper heat exchanger 200a flow. As shown in fig. 7, a subcooler 202 is provided between the expansion valve 25 and the liquid gate valve 26 to form a flow path so as to flow through the heat transfer tubes 101 in a part of the lower heat exchanger 200 b. The distributor 24 shown in fig. 6 and 7 merges or branches 9 flow paths, but is not particularly limited to the embodiment, and other number of flow paths may be merged, and the number of flow paths may be selected so as to optimize performance in both cases of functioning as a condenser and functioning as an evaporator. That is, the heat transfer rate and the pressure loss change according to the flow velocity in the heat transfer pipe, and therefore the number of flow paths for obtaining the optimum performance of both the condenser and the evaporator is set. The number of passages and the number of passages of the subcooler 201 and the subcooler 202 are also the most suitable values, and particularly, with respect to the number of passages and the number of passages of the subcooler 201, when the heat exchanger 200 functions as an evaporator, if the pressure loss in the subcooler 201 becomes large, a part of the pressure loss functions as a radiator, and therefore, the number of passages and the number of passages of the subcooler 201 are set in consideration of the pressure loss therein without generating such unnecessary heat radiation.

Here, the flow of the refrigerant in the heat exchanger 200 configured in fig. 6 and 7 when the heat exchanger 200 functions as a condenser will be described.

As shown in fig. 6, the refrigerant flowing through the flow paths 1 to 9 flows as a gas refrigerant into the upper heat exchanger 200a from the gas-side inlet ports of the flow paths 1 to 9 located in the third row, advances while exchanging heat, and flows out as a liquid refrigerant from the liquid-side outlet port of the first row. Thereafter, the refrigerant enters the upper distributor 24a, and the flow paths merge. After that, the refrigerant branches into two paths, passes through the subcooler 201a provided in the first row of the upper heat exchanger 200a, and then enters the expansion valve 25.

On the other hand, as shown in fig. 7, the refrigerant flowing through the flow paths 10 to 18 flows as a gas refrigerant into the lower heat exchanger 200b from the gas-side inlet ports of the flow paths 10 to 18 located in the third row, advances while exchanging heat, and flows out as a liquid refrigerant from the liquid-side outlet port in the first row. Thereafter, the refrigerant enters the lower distributor 24b in fig. 6, and the flow paths merge. After that, the refrigerant branches into two flow paths, passes through the subcooler 201b provided in the first row of the upper heat exchanger 200a, and then enters the expansion valve 25.

The flow paths of the refrigerant flowing out of the subcooler 201a and the refrigerant flowing out of the subcooler 201b merge in front of the expansion valve 25. After that, the refrigerant having passed through the expansion valve 25 passes through the subcooler 202 of fig. 7, then passes through the liquid gate valve 26, and reaches the liquid refrigerant pipe 4L connected to the indoor unit 3.

In addition, as shown in fig. 6 and 7, from the viewpoint of reducing the internal heat exchange loss, it is preferable that the subcooler be provided in the first row and the liquid refrigerant outflow port of each flow path in the case where the heat exchanger 200 functions as a condenser be adjacent to the subcooler. In particular, when the heat exchanger 200 functions as a condenser, the liquid refrigerant outlet of each flow path is adjacent to the refrigerant inlet of the subcooler, so that the temperature difference between the refrigerants flowing through the flow paths can be reduced, and the internal heat exchange loss can be further reduced. In the example shown in fig. 6, the liquid refrigerant outlet ports of the channels 7 and 8 are adjacent to the refrigerant inlet port of the subcooler 201 a. The liquid refrigerant outlet of the flow path 9 is adjacent to one of the refrigerant inlets of the subcooler 201 b. In the example shown in fig. 7, the liquid refrigerant outlet of the flow path 18 is adjacent to one of the liquid refrigerant inlets of the subcooler 202. With such a configuration, as described with reference to fig. 3 and the like, internal heat exchange loss due to heat conduction via the fins 102 can be further reduced.

As shown in fig. 7, by providing the subcooler 202 at the lower layer of the lower heat exchanger 200b, it is possible to function as a heat pipe during the heating operation, and to prevent the lower portion of the outdoor heat exchanger 200 from freezing. The heat pipe is a portion where the refrigerant flows at a relatively high temperature during the heating operation, and by causing the subcooler 202 to function as a heat pipe, even when frost adheres to the evaporator under conditions where the outside air temperature is low, the adhesion of frost can be prevented by maintaining the portion of the heat pipe at a temperature equal to or higher than the freezing point. Further, since ice does not accumulate on the drain pan portion that the lowermost portion of the lower heat exchanger 200b contacts, damage to the heat transfer tubes 101 of the heat exchanger 100 and damage to the blower fan can be prevented.

In order to operate the subcooler 202 as a heat pipe, the subcooler 202 is disposed upstream of the expansion valve 25 in the refrigerant traveling direction during the heating operation, and a liquid refrigerant at a high temperature close to the indoor temperature flowing from the indoor unit 3 is circulated, thereby achieving the above-described freeze prevention.

The subcooler 202 functions as a heat pipe during a heating operation in which the outdoor heat exchanger 20 functions as an evaporator. Therefore, when the outdoor heat exchanger 20 functions as a condenser, that is, during a cooling operation, the subcooler 202 functions as a normal subcooler as in the case of the other subcoolers 201.

On the other hand, when the subcooler 202 operates as a heat pipe during the heating operation, it operates at a temperature higher than the outside air, and therefore the heat of the refrigerant is dissipated to the outside air, and a part of the heating capacity is impaired. Therefore, as shown in fig. 6, it is preferable to arrange the rows at the most upstream with respect to the inflow direction of the airflow. The reason for this is that the heat transfer tubes 101 arranged in the second row and the third row function as evaporators during heating, and therefore, most of the amount of heat dissipated by the heat transfer tubes to the outside air can be recovered. Therefore, with the above configuration, freezing prevention during heating can be achieved, and performance degradation can be minimized. The row disposed most upstream with respect to the inflow direction of the air flow is also effective in the case where the subcooler 202 is used for the cooling operation for subcooling the liquid refrigerant. The reason for this is that the condenser can achieve the maximum efficiency so as to directly exchange heat with outdoor air having the lowest air temperature in the air-feeding portion. Similarly, when the subcooler 201 is used for subcooling liquid during cooling operation, as shown in fig. 6, it is effective for improving performance to be arranged most upstream with respect to the inflow direction of the air flow, and during heating operation, since the subcooler 201 is arranged downstream of the expansion valve 25, it is used at substantially the intake air temperature or lower and does not function as a radiator (heat pipe), but when it is temporarily a radiator due to cycle fluctuations, the heat radiated therefrom is recovered by the evaporators in the second row and the third row, similarly to the operation of the subcooler 202, and thus there is an effect of suppressing a decrease in heating capacity.

On the other hand, during cooling, the outdoor heat exchanger 200 functions as a condenser, but at its outlet, the refrigerant changes to a state of a liquid refrigerant having a high density, and the flow velocity of the refrigerant decreases in the heat transfer tube 101, and the heat transfer rate in the tube tends to decrease. However, in the

subcoolers

201 and 202, the refrigerant merges and the flow paths converge, and the refrigerant flow velocity can be increased positively. By increasing the refrigerant flow rate, the heat transfer rate in the heat transfer pipe 101 is increased. This can greatly improve the performance of the outdoor heat exchanger 200 when it functions as a condenser. In particular, in the subcooler 202, since the heat dissipation during heating causes the disadvantages as described above, it is effective to reduce the area as much as possible.

In addition, in order to improve the performance during cooling, as described above, it is effective to increase the flow velocity of the refrigerant in the liquid region, and it is effective to ensure the heat transfer area to some extent, but in a configuration such as the subcooler 202 that causes a heat radiation loss during heating, if the heat transfer area is made too large, the efficiency during heating is reduced. Therefore, in order to meet the contradictory requirements of both the performance during cooling and heating and the freezing prevention of the lower portion of the heat exchanger during heating, it is effective to additionally provide the subcooler 201 to the subcooler 202 as an effective measure. That is, the subcooler 201 does not function as a heat pipe during heating, and is disposed between the expansion valve 25 and the distributor 24 of the refrigeration cycle structure, and thus functions at a low pressure and a low temperature during heating. With the above configuration, both cooling and heating performance and reliability can be achieved with high dimension.

In the outdoor heat exchanger 200, as shown in fig. 6, the subcooler 201a and the subcooler 201b are provided in the upper heat exchanger 200a, whereby the piping paths can be collected, the piping space can be secured, and the workability during manufacturing can be improved. Further, as shown in fig. 6, when the heat exchanger is divided into an upper heat exchanger 200a and a lower heat exchanger 200b, the upper distributor 24a and the lower distributor 24b are arranged so that the sides thereof connected to the expansion valve 25 face each other, and thus the space occupied by the above-described pipes can be reduced, and as a result, the installation space of other components and the heat exchangers can be further increased.

Further, by disposing the distributor 24 in this manner, when the heat exchanger 100 functions as an evaporator, the connecting piping from the

subcoolers

201, 202 to the distributor 24 can be shortened, and particularly, in a portion where the two paths of the subcooler merge, the gas-liquid two-phase flow is stirred and uniformly mixed, so that the deviation of the refrigerant flowing into the distributor 24 is reduced, and the refrigerant distribution of the evaporator can be improved.

Next, an example of a specific configuration of the

subcoolers

201, 202 is explained. Fig. 8 is an external view of the outdoor unit 2 showing an example of arrangement of the constituent members of the outdoor heat exchanger 200 in the present embodiment. Fig. 8 (a) is a perspective view of the outdoor unit 2 of the present embodiment, and fig. 8 (B) is a bottom view of the outdoor unit 2 of the present embodiment. In order to facilitate understanding of the arrangement of the outdoor heat exchanger 200, the structure of the outdoor unit 2 is shown with the metal plate members on the upper and side portions removed.

Fig. 8 (a) shows an example of the heat exchanger 200 in which the lower heat exchanger 200b is disposed below the upper heat exchanger 200 a. As shown in fig. 8 (a), by disposing the subcooler 201 in the upper heat exchanger 200a, the expansion valve 25, the distributor 24, the liquid-side distribution pipe 28, and the refrigerant pipe 4 connecting these components can be disposed while avoiding the structure such as the tank 27 such as an accumulator or an accumulator tank. In particular, as shown by the dotted line in fig. 8 (B), the space of the distributor 24, the liquid-side distribution pipe 28, and the like is collected to save space, so that the heat exchanger can be increased in size and the heat exchange efficiency can be improved. Therefore, the size of the outdoor heat exchanger 200 can be maximized while maintaining the compactness of the outdoor unit 2.

In addition, when the subcooler 201 disposed between the distributor 24 and the expansion valve 25 is additionally provided in addition to the subcooler 202 disposed at the lower portion of the outdoor heat exchanger 200, the space for the inflow and outflow pipes becomes more complicated, and more installation space is required. Therefore, when it is provided in the lower portion of the heat exchanger like the subcooler 202, the remaining space is extremely small. Therefore, as in the present embodiment, by arranging the upper heat exchanger in the case where the heat exchanger is divided into two portions, a space below the end face of the heat exchanger can be made wider. Thus, as shown in fig. 8, even when the refrigerant pipe 4 connected from the outdoor unit 2 to the indoor unit 3 is provided on the rear side while passing through the inside of the outdoor unit 2, the connection pipe can pass therethrough.

Further, when a single refrigerant such as R32, R134a, or R1234yf, or a near-azeotropic refrigerant such as R410A or R404A, is used as the refrigerant used in the heat exchanger, the effects of reducing the heat loss and improving the refrigerant distribution described above can be exhibited, but when a non-azeotropic mixed refrigerant such as R448A, R449A, R463A, R466A, R407C, R407H, R454B, R454C, or R455A, or a refrigerant that radiates heat in a supercritical range, the heat loss reduction effect when the refrigerant is used for heat radiation in a condenser, a gas cooler, or the like is greater and effective because the temperature is reduced more greatly in the latter half of the heat radiation process and the temperature difference between the refrigerant temperature in the middle of the flow path and the liquid-side outlet temperature is greater. In addition, in the case of using the above-described non-azeotropic refrigerant, when the heat exchanger is used as an evaporator, unevenness in the amount of heat exchange and the amount of frost tends to occur due to a change in the temperature of the refrigerant during evaporation, and there is a tendency that the performance and reliability are adversely affected, and in the structure of the present heat exchanger in which the flow path lengths of the respective refrigerant flow paths can be made substantially the same as described above, since the flow rates of the refrigerant flowing through the respective flow paths in the evaporator can be made substantially the same, refrigerant distribution can be made substantially uniform while maintaining substantially uniform pressure loss, and therefore, the unevenness in the amount of heat exchange and the amount of frost can be greatly improved.

As described above, according to the embodiments of the present invention, it is possible to provide a heat exchanger capable of performing efficient heat exchange, and an air conditioner, an indoor unit, and an outdoor unit each including the heat exchanger.

In summary, the present invention has been described with reference to the embodiments, but the present invention is not limited to the above-described embodiments, and is within the scope of the present invention as long as the operation and effect of the present invention are exhibited within the scope of the embodiments that can be assumed by those skilled in the art.

Claims

1. A heat exchanger having heat transfer tube rows of a first row, a second row, and a third row in this order from an upstream side in a predetermined air blowing direction, and having a plurality of heat transfer tubes in each of the heat transfer tube rows, wherein a refrigerant flows through a plurality of refrigerant flow paths connecting the heat transfer tubes to exchange heat,

the refrigerant that has flowed into one heat transfer tube at one end portion of the second row reciprocates between the one end portion and the other end portion in the second row, and is discharged from the heat transfer tube at the one end portion in the second row,

a jumper tube for connecting the heat transfer tubes separated by striding over the layers is provided only on one of the one end side of the second row of the first refrigerant flow path and the one end side of the second row of the second refrigerant flow path,

the lengths of the first refrigerant flow path and the second refrigerant flow path are substantially the same,

the T-joint is a symmetrical shape in which the refrigerant discharged from one end of the second row collides perpendicularly with a branch portion of the T-joint when the heat exchanger functions as an evaporator.

2. The heat exchanger of claim 1,

three or more rows of the heat transfer pipes are provided.

3. The heat exchanger of claim 1,

a plurality of flow path pairs each including the first refrigerant flow path and the second refrigerant flow path,

the gas-side inlet of the refrigerant passage constituting one passage pair is adjacent to one of the gas-side inlets of the refrigerant passages constituting the other passage pair.

4. The heat exchanger of claim 2,

5. The heat exchanger according to any one of claims 1 to 4,

the heat transfer tubes have bent portions that turn back flow paths, and the difference between the number of heat transfer tubes that form the first refrigerant flow path and the number of heat transfer tubes that form the second refrigerant flow path is 2 or less.

6. An air conditioning device, characterized in that,

a heat exchanger according to any one of claims 1 to 5.

7. An indoor unit is characterized in that a plurality of indoor units are arranged in the indoor unit,

a heat exchanger according to any one of claims 1 to 5.

8. An outdoor unit, characterized in that,

a heat exchanger according to any one of claims 1 to 5.

9. The outdoor unit of claim 8,

comprises an expansion valve for decompressing the refrigerant and a distributor for branching the refrigerant,

a part of the heat transfer pipes included in the heat exchanger is configured as one or more subcoolers,

the subcooler is disposed between the expansion valve and the distributor.

10. The outdoor unit of claim 9,

the liquid-side outlet of any one of the plurality of refrigerant flow paths is adjacent to the subcooler.

11. The outdoor unit of claim 9 or 10,

the heat exchanger is composed of an upper heat exchanger and a lower heat exchanger,

the subcooler is arranged on the upper heat exchanger.

12. The outdoor unit of claim 11,

the distributor connected to the upper heat exchanger and the distributor connected to the lower heat exchanger are disposed to face each other.

13. The outdoor unit of claim 9 or 10,

a part of the heat transfer tubes of the lowermost layer included in the heat exchanger functions as a subcooler when the heat exchanger functions as a condenser and functions as a heat pipe when the heat exchanger functions as an evaporator,

the heat pipe is disposed upstream of the expansion valve with respect to a direction of travel of the refrigerant when the heat exchanger functions as an evaporator.

14. The outdoor unit of claim 11,

15. The outdoor unit of claim 12,