Heat exchanger, outdoor unit, and air conditioner

Abstract

A heat exchanger according to the present disclosure includes: a plurality of heat transfer tubes that are arranged side by side with space therebetween along a horizontal direction and include a flow path through which a refrigerant flows in a height direction; and a header that includes a cylindrical header tube extending along the direction in which the plurality of heat transfer tubes are arranged. The header tube includes: a first member having a top surface wall into which lower end sides of the plurality of heat transfer tubes are inserted, and two opposing first side surface walls that extend downward from both ends of the top surface wall; and a second member including a bottom surface wall and two opposing second side surface walls that extend upward from both ends of the bottom surface wall. A distance between the two second side surface walls is less than a distance between the two first side surface walls, and a height of the first side surface walls is greater than a height of the second side surface walls. The first side surface walls cover a portion of the second side surface walls to form a cylindrical shape. A distance from the lower end of the heat transfer tubes to the bottom surface wall in the header tube is greater than the distance between the two first side surface walls.

Description

Heat exchanger, outdoor unit and air conditioning device

[0001] This technology relates to a heat exchanger, an outdoor unit, and an air conditioner, and in particular to a heat exchanger having a header that serves as a refrigerant distributor.

[0002] In recent years, heat exchangers for air conditioners have been designed with thinner heat transfer tubes to reduce the amount of refrigerant used and improve heat exchanger performance. As heat transfer tubes become thinner, the number of branches in heat exchangers increases to suppress increases in refrigerant pressure loss. To accommodate this multi-branch distribution, heat exchangers have been developed that have a pair of headers arranged vertically (vertically) to distribute the refrigerant. In such heat exchangers, the longitudinal direction of the cylindrical, long-sided tubes is aligned horizontally (see, for example, Patent Document 1).

[0003] When a heat exchanger functions as an evaporator, a two-phase refrigerant, consisting of a mixture of liquid and gaseous refrigerant, flows into the tubes of the header located at the bottom in the vertical direction. At this time, the liquid refrigerant tends to accumulate in the lower part of the tubes in the header. When refrigerant accumulates in the heat exchanger, the amount of refrigerant circulating in the refrigerant circuit decreases. To maintain the amount of refrigerant circulating in the refrigerant circuit, the refrigerant circuit must initially have an amount of refrigerant that takes into account the amount of refrigerant accumulated in the heat exchanger, which increases the amount of refrigerant. Therefore, heat exchangers that aim to reduce the amount of refrigerant accumulating in the header have been proposed (see, for example, Patent Documents 2 and 3).

[0004] Japanese Patent Application Laid-Open No. 08-005194 Japanese Patent Application Laid-Open No. 2014-512502 International Publication No. 2019 / 078066

[0005] As described above, the heat exchanger can prevent refrigerant retention by reducing the internal volume by reducing the cross-sectional area of ​​the tubes in the header. However, simply reducing the cross-sectional area of ​​the tubes in the header to prevent refrigerant retention may increase pressure loss of the refrigerant within the tubes, which may result in poor refrigerant distribution.

[0006] Therefore, the disclosed heat exchanger, outdoor unit, and air conditioning device aim to solve the above-mentioned problems, suppress deterioration of refrigerant distribution, maintain high heat exchange performance, and reduce the amount of refrigerant remaining in the heat exchanger.

[0007] The heat exchanger disclosed herein comprises a plurality of heat transfer tubes arranged side by side and spaced apart horizontally, with flow paths through which a refrigerant flows in the vertical direction, and a header having a cylindrical header tube extending in the direction in which the heat transfer tubes are arranged. The header tube has a first member having a top wall into which the lower ends of the heat transfer tubes are inserted and two first side walls extending downward from both ends of the top wall and facing each other, and a second member having a bottom wall and two second side walls extending upward from both ends of the bottom wall and facing each other, wherein the distance between the two second side walls is narrower than the distance between the two first side walls, the height of the first side wall is greater than the height of the second side walls, the first side wall covers a portion of the second side wall to form a cylindrical shape, and the distance within the header tube from the lower ends of the heat transfer tubes to the bottom wall is greater than the distance between the two first side walls.

[0008] An outdoor unit according to the present disclosure includes the above-described heat exchanger as an outdoor heat exchanger.

[0009] The air conditioner according to this disclosure comprises the outdoor unit described above, and an indoor unit that has an indoor heat exchanger and a throttling device and conditions the air in a space to be air-conditioned.

[0010] According to the disclosed heat exchanger, outdoor unit, and air conditioner, the distribution header has a first member that forms the top and two side surfaces and a second member that forms the bottom surface, with the first member covering the second member. By installing the second member as the bottom surface of the distribution header, the area where liquid refrigerant accumulates below the distribution header can be reduced, thereby reducing the amount of refrigerant that accumulates. By making the distribution header vertically elongated, the amount of refrigerant that accumulates can be reduced without reducing the cross-sectional area, thereby reducing pressure loss. This improves the distribution of refrigerant flowing into the heat transfer tubes, maintaining high heat exchange performance while reducing the amount of refrigerant that accumulates in the heat exchanger. This reduces the amount of refrigerant in the entire refrigerant circuit.

[0011] 1 is a diagram illustrating a configuration of an air conditioning apparatus according to a first embodiment. FIG. 2 is a diagram illustrating a configuration of an outdoor unit 200 according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of a heat exchanger 1000 according to the first embodiment. FIG. 4 is a diagram illustrating a portion of a cross section of the heat exchanger 1000 according to the first embodiment when viewed from the X direction. FIG. 5 is a diagram illustrating a portion of a cross section of the heat exchanger 1000 according to the first embodiment when viewed from the Y direction. FIG. 6 is a diagram illustrating the aspect ratio of a header pipe 1110 of a distribution header 1100 according to the first embodiment. FIG. 7 is a diagram illustrating a state of a refrigerant in the distribution header 1100 according to the first embodiment (part 1). FIG. 8 is a diagram illustrating a state of a refrigerant in the distribution header 1100 according to the first embodiment (part 3). FIG. 9 is a diagram illustrating a state of a refrigerant in the distribution header 1100 according to the first embodiment (part 4). FIG. 10 is a diagram illustrating a portion of a cross section of the heat exchanger 1000 according to the second embodiment when viewed from the X direction. FIG. 11 is a diagram illustrating a portion of a cross section of the heat exchanger 1000 according to the second embodiment when viewed from the Y direction. FIG. 1 is a diagram (part 1) illustrating the state of the refrigerant in the distribution header 1100 according to embodiment 2. FIG. 2 is a diagram (part 2) illustrating the state of the refrigerant in the distribution header 1100 according to embodiment 2. FIG. 3 is a diagram (part 4) illustrating the state of the refrigerant in the distribution header 1100 according to embodiment 2. FIG. 4 is a diagram (part 4) illustrating the state of the refrigerant in the distribution header 1100 according to embodiment 2. FIG. 5 is a diagram illustrating a part of a cross section of the heat exchanger 1000 according to embodiment 3 when viewed from the Y direction. FIG. 6 is a diagram illustrating a part of a cross section of the heat exchanger 1000 according to embodiment 4 when viewed from the Y direction.

[0012] Hereinafter, heat exchangers, outdoor units, and air conditioners according to embodiments will be described with reference to the drawings. In the following drawings, components with the same reference numerals are identical or equivalent and will be common throughout the following embodiments. Furthermore, the dimensional relationships between components in the drawings may differ from those in reality. Furthermore, the configurations of components shown throughout the specification are merely illustrative and are not limited to those described in the specification. In particular, the combinations of components are not limited to those in each embodiment, and components described in other embodiments may be applied to other embodiments. Furthermore, the upper side in the drawings will be referred to as "top" and the lower side as "bottom." Furthermore, the levels of pressure and temperature are not determined in relation to absolute values, but are determined relatively in terms of the state, operation, etc. of the device. Furthermore, when multiple similar devices are distinguished by subscripts, the subscripts may be omitted if there is no need to distinguish or identify them.

[0013] Embodiment 1. <Configuration of Air Conditioning Apparatus> Fig. 1 is a diagram showing the configuration of an air conditioning apparatus according to Embodiment 1. Here, an air conditioning apparatus will be described as an example of a refrigeration cycle apparatus. As shown in Fig. 1, the air conditioning apparatus according to Embodiment 1 has an outdoor unit 200, an indoor unit 100, and two refrigerant pipes 300. The compressor 210, four-way valve 220, and outdoor heat exchanger 230 of the outdoor unit 200 are connected to the indoor heat exchanger 110 and expansion device 120 of the indoor unit 100 via the refrigerant pipes 300 to form a refrigerant circuit. Here, the air conditioning apparatus according to Embodiment 1 is assumed to have one outdoor unit 200 and one indoor unit 100 connected via pipes. However, the number of connected units is not limited to this.

[0014] The indoor unit 100 is an air-conditioning device installed in a space to be air-conditioned. The indoor unit 100 includes an indoor heat exchanger 110 and a throttling device 120 that constitute a refrigerant circuit, as well as an indoor blower 130. The throttling device 120 is a device that includes an expansion valve that reduces the pressure of the refrigerant and expands it. If the throttling device 120 is configured as an electronic expansion valve, for example, it adjusts its opening based on instructions from a control device 400 (described below). The indoor heat exchanger 110 is a load-side heat exchanger that exchanges heat between the refrigerant and the indoor air in the space to be air-conditioned. For example, during heating operation, the indoor heat exchanger 110 functions as a condenser, condensing and liquefying the refrigerant. During cooling operation, the indoor heat exchanger 110 functions as an evaporator, evaporating and vaporizing the refrigerant. The indoor blower 130 passes indoor air through the indoor heat exchanger 110 and supplies the air that has passed through the indoor heat exchanger 110 to the room. Here, the indoor heat exchanger 110 is described as directly exchanging heat between the refrigerant and the indoor air, but this is not limited to this. For example, the indoor heat exchanger 110 may exchange heat between the refrigerant and water via water, and the water may exchange heat with the indoor air.

[0015] FIG. 2 is a diagram illustrating the configuration of an outdoor unit 200 according to the first embodiment. The outdoor unit 200 is a device installed outside an air-conditioned space. Here, the outdoor unit 200 according to the first embodiment is, for example, a top-flow type device having an outlet for an outdoor blower 280 at the center of the top of the housing. As shown in FIG. 1 , the outdoor unit 200 according to the first embodiment includes a compressor 210, a four-way valve 220, an outdoor heat exchanger 230, an auxiliary heat exchanger 240, a refrigerant amount control valve 250, a bypass pipe 260, and an accumulator 270 as components constituting a refrigerant circuit. The outdoor unit 200 also includes the outdoor blower 280. The compressor 210 compresses and discharges the drawn refrigerant. The compressor 210 may be, for example, a scroll compressor, a reciprocating compressor, or a vane compressor. Here, the air conditioning apparatus in Embodiment 1 has, for example, an inverter device (not shown) or the like, and can arbitrarily change the drive frequency of the power supplied to compressor 210. By changing the drive frequency, the motor (not shown) of compressor 210 can change the rotation speed, and the drive capacity of compressor 210 can be changed.

[0016] The four-way valve 220, which serves as a refrigerant flow switching device, is a valve that switches the flow of refrigerant depending on, for example, whether the system is in cooling operation or heating operation. During heating operation, the four-way valve 220 connects the discharge side of the compressor 210 to the indoor heat exchanger 110 and connects the suction side of the compressor 210 to the outdoor heat exchanger 230. During cooling operation, the four-way valve 220 connects the discharge side of the compressor 210 to the outdoor heat exchanger 230 and connects the suction side of the compressor 210 to the indoor heat exchanger 110. While the four-way valve 220 is used here as an example, the flow switching device is not limited to this. The flow switching device may also be, for example, a combination of multiple two-way valves.

[0017] The outdoor heat exchanger 230 exchanges heat between the refrigerant and outdoor air. Here, the outdoor heat exchanger 230 in the first embodiment functions as an evaporator during heating operation, evaporating and vaporizing the refrigerant. Meanwhile, during cooling operation, the outdoor heat exchanger 230 functions as a condenser, condensing and liquefying the refrigerant. As shown in FIG. 1 , the outdoor heat exchanger 230 includes two heat exchangers: a heat exchanger 1000A and a heat exchanger 1000B. The heat exchanger 1000A and the heat exchanger 1000B are connected in parallel in the refrigerant circuit. Details of the heat exchangers 1000 (heat exchanger 1000A and heat exchanger 1000B) will be described later. Here, the outdoor heat exchanger 230 is described as exchanging heat between the refrigerant and outdoor air, but it may also exchange heat between the refrigerant and another external fluid. Furthermore, when driven, the outdoor blower 280 passes air from outside the outdoor unit 200 through the outdoor heat exchanger 230 , forming a flow of air that flows out from inside the outdoor unit 200 .

[0018] The auxiliary heat exchanger 240 has, for example, a double-pipe or plate heat exchanger. During cooling operation, the auxiliary heat exchanger 240 subcools the refrigerant flowing out from the outdoor heat exchanger 230. The auxiliary heat exchanger 240 is an inter-refrigerant heat exchanger that exchanges heat between the refrigerant flowing out from the outdoor heat exchanger 230 and flowing through the main refrigerant circuit toward the indoor heat exchanger 110 and the refrigerant that has passed through the bypass piping 260 and the refrigerant quantity control valve 250. The bypass piping 260 forms a bypass flow path. During cooling operation, a portion of the refrigerant that has passed through the main refrigerant circuit side of the auxiliary heat exchanger 240 branches off, passes through the refrigerant quantity control valve 250 and the bypass flow path side of the auxiliary heat exchanger 240, and flows into a pipe on the refrigerant inlet side of the accumulator 270. The refrigerant quantity control valve 250 is disposed in the bypass piping 260 and is a refrigerant quantity control device that adjusts the amount of refrigerant passing through the bypass piping 260. At this time, the refrigerant amount adjustment valve 250 reduces the pressure of a portion of the refrigerant that has passed through the auxiliary heat exchanger 240 and branched off, and causes the refrigerant to pass through the bypass flow path side of the auxiliary heat exchanger 240 .

[0019] The accumulator 270 is disposed on the suction side of the compressor 210. The accumulator 270 passes a gaseous refrigerant (hereinafter referred to as a gas refrigerant) and stores a liquid refrigerant (hereinafter referred to as a liquid refrigerant).

[0020] The control device 400 controls the devices of the air conditioning system. For example, the control device 400 controls the throttling device 120, the compressor 210, the refrigerant amount control valve 250, etc. The control device 400 can be configured with hardware such as a circuit device that realizes its functions. It can also be configured with a computing device having a microcomputer, CPU, etc., and software. The computing device executes and processes the software to realize control.

[0021] <Operation of the Air Conditioner> Next, the operation of each device in the air conditioner will be described based on the flow of refrigerant. First, the operation of each device in the refrigerant circuit during heating operation will be described based on the flow of refrigerant. During heating operation, the control device 400 closes the refrigerant amount control valve 250. The solid arrows in FIG. 1 indicate the flow of refrigerant during heating operation. High-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the indoor heat exchanger 110. While passing through the indoor heat exchanger 110, the gas refrigerant condenses and liquefies by, for example, exchanging heat with the air in the space to be air-conditioned. The condensed and liquefied refrigerant passes through the throttling device 120. The refrigerant is decompressed as it passes through the throttling device 120. The refrigerant, decompressed and in a gas-liquid two-phase state by the throttling device 120, passes through the auxiliary heat exchanger 240 and the outdoor heat exchanger 230. Here, because the refrigerant amount control valve 250 is closed, heat exchange does not occur between refrigerants in the auxiliary heat exchanger 240. In the outdoor heat exchanger 230, the refrigerant evaporates by exchanging heat with the outdoor air sent from the outdoor blower 280, and the gasified refrigerant passes through the four-way valve 220 and the accumulator 270, and is again drawn into the compressor 210. In this way, the refrigerant in the air conditioner circulates to perform air conditioning related to heating.

[0022] Next, cooling operation will be described. During cooling operation, the control device 400 adjusts the refrigerant quantity control valve 250 to allow a portion of the refrigerant passing through the main refrigerant circuit to pass through the bypass pipe 260. The dotted arrows in FIG. 1 indicate the flow of refrigerant during cooling operation. The high-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the outdoor heat exchanger 230. The refrigerant then passes through the outdoor heat exchanger 230 and condenses and liquefies by exchanging heat with outdoor air supplied by the outdoor blower 280. A portion of the refrigerant that passed through the main refrigerant circuit side of the auxiliary heat exchanger 240 passes through the bypass pipe 260 and is decompressed by the refrigerant quantity control valve 250, becoming low-temperature, low-pressure refrigerant and passing through the bypass pipe side of the auxiliary heat exchanger 240. This allows heat exchange between the refrigerants, and the refrigerant that passed through the main refrigerant circuit side of the auxiliary heat exchanger 240 is subcooled. The liquefied refrigerant passes through the expansion device 120. Here, the refrigerant is decompressed and enters a gas-liquid two-phase state as it passes through the expansion device 120. The refrigerant that has been decompressed and entered a gas-liquid two-phase state by the expansion device 120 passes through the indoor heat exchanger 110. In the indoor heat exchanger 110, the refrigerant evaporates, for example, by exchanging heat with the air in the space to be air-conditioned. The gasified refrigerant passes through the four-way valve 220 and is again drawn into the compressor 210. In this way, the refrigerant in the air conditioner circulates, performing air conditioning related to cooling.

[0023] <Configuration of Heat Exchanger 1000> Figure 3 is a diagram illustrating the configuration of the heat exchanger 1000 according to the first embodiment. The outdoor heat exchanger 230 has a corrugated fin tube heat exchanger 1000 of a parallel piping type. Hereinafter, the up-down direction of the heat exchanger 1000 is referred to as the Z direction (height direction). The direction perpendicular to the Z direction is referred to as the horizontal direction. In addition, within the horizontal direction, a certain direction is referred to as the X direction (vertical-horizontal direction), and the direction perpendicular to the X direction is referred to as the Y direction (horizontal-vertical direction).

[0024] As described above, the outdoor heat exchanger 230 of the outdoor unit 200 has two heat exchangers 1000 (heat exchanger 1000A and heat exchanger 1000B). The heat exchanger 1000A and the heat exchanger 1000B are connected in parallel by piping in the refrigerant circuit. However, the number and configuration of connections in the refrigerant circuit of the first embodiment are not limited to this.

[0025] Each heat exchanger 1000 has two distribution headers 1100 (distribution header 1100A and distribution header 1100B), a folded header 1200, a plurality of heat transfer tubes 1300, and a plurality of corrugated fins 1400.

[0026] In the heat exchanger 1000 of the outdoor heat exchanger 230 in the first embodiment, a pair of headers consisting of two distribution headers 1100 and a turn-back header 1200 are arranged above and below in the Z direction. For example, in the outdoor unit 200, devices such as the compressor 210 are installed below the outdoor unit 200. Therefore, due to piping connections and the like, the turn-back header 1200 is located above, and the two distribution headers 1100, which serve as refrigerant distributors, are located below the turn-back header 1200.

[0027] A plurality of heat transfer tubes 1300 are arranged in line along the Y direction between the two distribution headers 1100 and the turn-back header 1200. As will be described later, the heat transfer tubes 1300 in the first embodiment have a flattened cross section. Here, a group of a plurality of heat transfer tubes 1300 is arranged in two rows, with the flat surfaces facing each other and perpendicular to the distribution header 1100 and the turn-back header 1200 and parallel to each other. The group of heat transfer tubes 1300 in one row is connected to one distribution header 1100.

[0028] The distribution header 1100, which serves as a refrigerant distributor, is connected to the other devices constituting the refrigeration cycle system via pipes. The refrigerant, a fluid that serves as a heat exchange medium, flows in and out, branching or merging the refrigerant. The distribution header 1100 has header pipes 1110 (header pipes 1110A and 1110B) and refrigerant inlet / outlet pipes 1120 (refrigerant inlet / outlet pipes 1120A and 1120B). The header pipes 1110 are long, cylindrical pipes. Each distribution header 1100 also has refrigerant inlet / outlet pipes 1120 through which refrigerant flows in and out from the outside. Here, the longitudinal direction of the header pipes 1110 is assumed to be along the Y direction, which is the arrangement direction of the multiple heat transfer pipes 1300. The structure of the distribution header 1100 will be described in more detail below.

[0029] In addition, the turnaround header 1200 is a header that acts as a bridge, joining the refrigerant flowing in from a group of heat transfer tubes 1300 in one row and branching it out to a group of heat transfer tubes 1300 in the other row.

[0030] The heat transfer tube 1300 in the first embodiment has a flat cross section, with the outer surface on the long side of the flat shape along the depth direction (the air flow direction) being flat, and the outer surface on the short side perpendicular to the long side being curved. The heat transfer tube 1300 in the first embodiment is a multi-hole flat heat transfer tube having a plurality of holes therein that serve as refrigerant flow paths. In the first embodiment, the holes of the heat transfer tube 1300 are formed facing the Z direction to serve as flow paths between the distribution header 1100 and the turn-back header 1200. As described above, the heat transfer tubes 1300 are arranged at equal intervals in the X direction with their outer surfaces facing each other on their long sides. When manufacturing the heat exchanger 1000 of the outdoor heat exchanger 230 in the first embodiment, each heat transfer tube 1300 is inserted into insertion holes (not shown) in the distribution header 1100 and the turn-back header 1200, and then brazed and joined. As described above, since the distribution header 1100 is disposed on the lower side, each heat transfer tube 1300 is inserted into the top surface of the distribution header 1100 and joined to a top wall 1111B (described later). A brazing filler metal containing aluminum, for example, is used for brazing. This allows the distribution header 1100 and the turn-back header 1200 to communicate with the interior of each heat transfer tube 1300.

[0031] Corrugated fins 1400 are arranged between the opposing flat surfaces of the arranged heat transfer tubes 1300. The corrugated fins 1400 are arranged to increase the heat transfer area between the refrigerant and the outside air. The corrugated fins 1400 are formed by corrugating a plate material, folding it into a wave-like, bellows-like shape through repeated mountain and valley folds. The bent portions due to the unevenness created by the wave-like shape become the peaks of the wave-like shape. In the first embodiment, the peaks of the corrugated fins 1400 are aligned along the Z direction. The peaks of the wave-like shape of the corrugated fins 1400 are in surface contact with the flat surfaces of the heat transfer tubes 1300. The contact portions are brazed and joined using a brazing material. The plate material of the corrugated fin 1400 is made of, for example, an aluminum alloy. A brazing material layer is clad on the surface of the plate material. The clad brazing material layer is based on, for example, an aluminum-silicon-based brazing material containing aluminum.

[0032] Fig. 4 is a diagram showing a part of a cross section of the heat exchanger 1000 according to the first embodiment when viewed from the X direction. Fig. 5 is a diagram showing a part of a cross section of the heat exchanger 1000 according to the first embodiment when viewed from the Y direction. The header pipe 1110 of the distribution header 1100 is a refrigerant distribution pipe having a long tubular shape. The header pipe 1110 has a first member 1111, a second member 1112, and a cover 1113.

[0033] The lids 1113 shown in Fig. 4 close the openings at both ends of the tube formed by combining the first member 1111 and the second member 1112, and serve as lids that separate the space inside the tube from the space outside the tube. The lids 1113 are joined to the first member 1111 and the second member 1112 at both ends of the tube. One of the two lids 1113 has the refrigerant inlet / outlet pipe 1120 described above.

[0034] The first member 1111 is an inverted U-shaped semi-open member that forms the top surface and flat side surfaces of the header pipe 1110, which is a long pipe extending in the Y direction. The first member 1111 has a first side wall 1111A and a top wall 1111B. The top wall 1111B is a wall into which the multiple heat transfer tubes 1300 are inserted and joined. As shown in FIG. 5 , the top wall 1111B in the first embodiment is a curved wall that forms an arc shape when the heat exchanger 1000 is viewed from the Y direction. The two first side walls 1111A extend downward from first connection portions 1111C, which are connection portions at both ends of the top wall 1111B, and are opposite walls. When the heat exchanger 1000 is viewed from the Y direction, each of the first side walls 1111A has a bent shape in which a lower end 1111D of the first side wall 1111A, which is the lower end of the first side wall 1111A, is bent in a direction that shortens the distance between the walls. As a result, each of the first side walls 1111A covers a portion of a bottom wall 1112B of the second member 1112 (described later), and can support the second member 1112 by embracing it. This also increases the bonding area between the inner surface of the first side wall lower end 1111D and the outer surface of the bottom wall 1112B.

[0035] The second member 1112 forms the bottom surface of the cylindrical header pipe 1110. The second member 1112 has a second side wall 1112A and a bottom wall 1112B. The bottom wall 1112B forms the bottom surface of the header pipe 1110. As shown in FIG. 5 , the bottom wall 1112B in the first embodiment is a curved wall that forms an arc when the heat exchanger 1000 is viewed from the Y direction. The two second side walls 1112A extend upward from second connection portions 1112C, which are connecting portions at both ends of the bottom wall 1112B, and are opposite walls. The distance between the two second side walls 1112A is narrower than the distance between the two first side walls 1111A. Furthermore, the height of each second side wall 1112A is shorter than the height of the first side wall 1111A.

[0036] Here, the second member 1112 is placed in the space formed by the first side wall 1111A and the top wall 1111B of the first member 1111 and is joined to the first member 1111. Therefore, a portion of the inner wall surface of the first side wall 1111A of the first member 1111 is joined to the outer wall surfaces of portions of the second side wall 1112A and the bottom wall 1112B of the second member 1112. By placing the second member 1112 in the space formed by the first side wall 1111A and the top wall 1111B of the first member 1111, the lower portion of the header pipe 1110 is narrowed by the amount of the second member 1112, as shown in FIG.

[0037] 5, the bending radius of the first connection portion 1111C of the first member 1111 is R1, and the bending radius of the second connection portion 1112C of the second member 1112 is R2. In this case, the bending radius R1 and the bending radius R2 have a relationship of R2<R1. By reducing the bending radius R2 of the second member 1112 and reducing the volume of the lower part of the header pipe 1110, it is possible to reduce the accumulation of liquid refrigerant.

[0038] Furthermore, as described above, the top wall 1111B of the first member 1111 and the bottom wall 1112B of the second member 1112 are arc-shaped when viewed from the Y direction. The radius of the arc of the bottom wall 1112B is larger than the radius of the arc of the top wall 1111B. Therefore, the curve of the bottom wall 1112B is gentler and closer to a straight line. This reduces the volume of the lower part of the header pipe 1110.

[0039] FIG. 6 is a diagram illustrating the aspect ratio of the header pipe 1110 of the distribution header 1100 according to the first embodiment. In the distribution header 1100 according to the first embodiment, the distance H in the Z direction between the heat transfer tube lower end 1310 (the lower end of the heat transfer tube 1300) and the bottom wall 1112B is longer than the widthwise distance W between the two first side walls 1111A in the space within the header pipe 1110. Therefore, as shown in FIG. 5 , the header pipe 1110 of the distribution header 1100 has a long, flat shape with a different aspect ratio when viewed from the X direction, with a long vertical length (length in the Z direction) and a short horizontal length (length in the X direction). For example, in FIG. 5 , the aspect ratio (vertical length / horizontal length) of the header pipe 1110 of the distribution header 1100 is approximately 1.41 when viewed from the outer surface of the pipe. Furthermore, the aspect ratio is approximately 1.47 when viewed from the inner surface of the pipe. However, the aspect ratio of the header pipe 1110 is not limited to the ratio shown in FIG. 5 . For example, it can be said that a distribution deviation of less than 30% results in little bias in refrigerant distribution. As a result of trials, as shown in FIG. 6 , it was found that the distribution deviation is less than 30% when the aspect ratio (length / width) of the header pipe 1110 is in the range of 1 < aspect ratio (length / width) ≦ 2.4, and therefore refrigerant distribution is effective within this aspect ratio range. In particular, it is found that the aspect ratio (length / width) within the space within the pipe is more preferably 1.2 or more and 2 or less. This range is effective in terms of both good refrigerant distribution and suppressing an increase in refrigerant accumulation.

[0040] FIGS. 7 to 10 are diagrams (1) to (4) illustrating the state of the refrigerant in the distribution header 1100 according to the first embodiment. FIGS. 7 to 10 schematically illustrate the first and second members 1111 and 1112 of the distribution header 1100 and the heat transfer tubes 1300. As described above, when the heat exchanger 1000 functions as an evaporator, a gas-liquid two-phase refrigerant flows into the distribution header 1100. Due to factors such as gravity, the gas refrigerant in the gas-liquid two-phase refrigerant is concentrated at the top and the liquid refrigerant is concentrated at the bottom within the distribution header 1100. The liquid refrigerant forms a wavy flow within the distribution header 1100. In FIGS. 7 to 10, the positional relationship between the liquid refrigerant collecting at the bottom and the lower end portions 1310 of the heat transfer tubes 1300 is represented as a liquid level 2000. However, the liquid level 2000 is a virtual surface, and in reality, as shown by the liquid level 2000 in FIGS. 7 to 10, the boundary surface between the gas refrigerant and the liquid refrigerant is not fixed.

[0041] Fig. 7 is a view from the Y direction showing the state of the refrigerant in the distribution header 1100 according to embodiment 1, where the distance H in the Z direction between the heat transfer tube lower end 1310 and the bottom wall 1112B is longer than the distance W in the X direction between the two first side walls 1111A. Fig. 8 is a view from the X direction showing the state of the refrigerant shown in Fig. 7. Fig. 9 is a view from the Y direction showing the state of the refrigerant in a distribution header having the same cross-sectional area as the distribution header 1100 of Fig. 7, where the distance H is shorter than the distance W. Fig. 10 is a view from the X direction showing the state of the refrigerant shown in Fig. 9.

[0042] When the distance H is shorter than the distance W, the distance between the heat transfer tube lower end 1310 of the heat transfer tube 1300 and the liquid level 2000 becomes closer, as shown in Fig. 9. Therefore, as shown in Fig. 10, a large amount of liquid refrigerant passes through the heat transfer tubes 1300 close to the refrigerant inlet / outlet pipe 1120 on the refrigerant inlet side, and there are portions within the tube where the liquid refrigerant is less at positions away from the refrigerant inlet / outlet pipe 1120. Therefore, in the header pipe 1110 of the distribution header 1100, the change in the liquid level 2000 in the Y direction becomes large, and less liquid refrigerant passes through the heat transfer tubes 1300 that are not close to the refrigerant inlet / outlet pipe 1120. Therefore, a bias in the ratio of gas refrigerant to liquid refrigerant occurs depending on the position of the heat transfer tube 1300.

[0043] On the other hand, when the distance H is longer than the distance W, as shown in Fig. 7, the distance between the heat transfer tube lower end 1310 of the heat transfer tube 1300 and the liquid level 2000 becomes greater than in the case of Fig. 9. Therefore, the liquid refrigerant that did not pass through the heat transfer tubes 1300 close to the refrigerant inlet / outlet pipe 1120 reaches a position away from the refrigerant inlet / outlet pipe 1120, thereby reducing the change in the liquid level 2000 in the Y direction in the header pipe 1110 of the distribution header 1100. Therefore, the liquid refrigerant can pass through even the heat transfer tubes 1300 that are not close to the refrigerant inlet / outlet pipe 1120, and the ratio of gas refrigerant to liquid refrigerant passing through each heat transfer tube 1300 can be made more uniform.

[0044] As described above, according to the heat exchanger 1000 of the first embodiment, the distribution header 1100 has a first member 1111 that forms the top surface and two side surfaces, and a second member 1112 that forms the bottom surface, and is configured so that the first member 1111 covers the second member 1112. By installing the second member 1112 as the bottom surface of the distribution header 1100 in the semi-open space formed by the first member 1111, the area where liquid refrigerant stagnates below the distribution header 1100 can be reduced, and the amount of stagnant refrigerant can be reduced. In this case, the distribution header 1100 is shaped so that the distance H between the heat transfer tube lower end 1310 of the heat transfer tube 1300 and the bottom wall 1112B is longer than the distance W between the two first side walls 1111A. By making the distribution header 1100 elongated, the lower region within the distribution header 1100 is reduced, which makes it possible to reduce the cross-sectional area and pressure loss compared to simply reducing the pipe diameter. This makes it possible to reduce the uneven distribution of the refrigerant flowing into each heat transfer tube 1300 while reducing the amount of refrigerant remaining in the heat exchanger 1000. This makes it possible to reduce the amount of refrigerant in the entire refrigerant circuit.

[0045] Furthermore, the first side wall 1111A of the first member 1111 is configured such that opposing lower end portions 1111D of the first side wall 1111A are bent in a direction narrowing the gap between them. As a result, the first side wall 1111A covers a portion of the outer surface of the bottom wall 1112B of the second member 1112 at the lower end portions 1111D of the first side wall 1111A, thereby embracing the second member 1112 and increasing the bonding area with the second member 1112.

[0046] Furthermore, the second connection portion 1112C has a bend radius R2 and the first connection portion 1111C has a bend radius R1 such that R2 < R1. The arc radius of the bottom wall 1112B of the second member 1112 is larger than the arc radius of the top wall 1111B of the first member 1111. This reduces the lower area within the distribution header 1100.

[0047] Embodiment 2 Fig. 11 is a diagram showing a part of a cross section of a heat exchanger 1000 according to embodiment 2 when viewed from the X direction. Fig. 12 is a diagram showing a part of a cross section of a heat exchanger 1000 according to embodiment 2 when viewed from the Y direction. In Figs. 11 and 12, components and the like having the same reference numerals as those in Figs. 4 and 5 perform the same functions and operations as those described in embodiment 1.

[0048] 11 , the distribution header 1100 in the heat exchanger 1000 of the second embodiment is a double-structure refrigerant distributor having an outer pipe 1110C and an inner pipe 1120C. The outer pipe 1110C is a pipe formed by combining a first member 1111 and a second member 1112, similar to the header pipe 1110 described in the first embodiment. Meanwhile, the inner pipe 1120C is a long pipe that is installed inside the outer pipe 1110C along the outer pipe 1110C. Although not particularly limited, in the distribution header 1100 of the second embodiment, the refrigerant inlet / outlet pipe 1120 is assumed to be integral with the inner pipe 1120C.

[0049] Here, the positional relationship between the outer pipe 1110C and the inner pipe 1120C of the distribution header 1100 in the second embodiment will be described. As shown in FIG. 12 , the dimensional centerline of the outer pipe 1110C in the Z direction is taken as line E-E, and the dimensional centerline of the inner pipe 1120C in the Z direction is taken as line F-F. In this case, line F-F is lower than line E-E in the Z direction. By positioning the inner pipe 1120C at the bottom of the space within the outer pipe 1110C, it is possible to reduce the area where liquid refrigerant is likely to stagnate.

[0050] The inner tube 1120C has an orifice 1121 that serves as a refrigerant outflow hole. The refrigerant flowing out from the orifice 1121 is sprayed into the space between the inner tube 1120C and the outer tube 1110C, and flows from the outer tube 1110C into the heat transfer tube 1300. The gas-liquid two-phase refrigerant that flows into the interior of the inner tube 1120C from the refrigerant inlet / outlet tube 1120 is agitated when it flows out from the orifice 1121 into the space between the inner tube 1120C and the outer tube 1110C. As a result, the liquid refrigerant and the gas refrigerant become nearly homogeneous. By making the refrigerant flow ratio of the refrigerant passing through the multiple heat transfer tubes 1300 more uniform, the heat exchange performance of the heat exchanger 1000 is improved.

[0051] Here, in embodiment 2, the orifice 1121 is not directly below the inner pipe 1120C, but is diagonally below the inner pipe 1120C, and is oriented to spray gas-liquid two-phase refrigerant onto the downwind side of the air passing through the heat exchanger 1000.

[0052] As described above, the heat transfer tube 1300 is a multi-hole flat heat transfer tube. Therefore, the heat transfer tube 1300 has multiple flow paths along the X direction, which is the direction in which air passes. By ejecting the gas-liquid two-phase refrigerant from the orifice 1121 to the downwind side, as shown by the solid arrows in FIG. 12 , a gas-rich refrigerant having a higher proportion of gas refrigerant in the gas-liquid two-phase refrigerant is supplied to the downwind flow path of the heat transfer tube 1300. On the other hand, as shown by the dotted arrows in FIG. 12 , a liquid-rich refrigerant having a higher proportion of liquid refrigerant in the gas-liquid two-phase refrigerant is supplied to the upwind flow path of the heat transfer tube 1300. Therefore, a larger amount of liquid refrigerant can be distributed to the upwind side, where the temperature difference between the refrigerant and the air is larger, thereby improving heat transfer performance.

[0053] Furthermore, by ejecting the gas-liquid two-phase refrigerant from the orifice 1121 into the lower region of the annular flow path, the force of the ejection prevents the liquid refrigerant from accumulating. This reduces the amount of refrigerant used. Furthermore, the orifice 1121 is located at a position S in the Z direction that is higher than a position T of the second side wall upper end 1112D, which is the upper end of the second side wall 1112A of the second member 1112 of the outer tube 1110C. This allows the gas-liquid two-phase refrigerant to be ejected from the orifice 1121 without reducing its force, preventing the liquid refrigerant from accumulating.

[0054] 13 to 16 are diagrams (1) to (4) illustrating the state of the refrigerant in the distribution header 1100 according to the second embodiment. 13 to 16 schematically illustrate the outer tube 1110C (first member 1111 and second member 1112), inner tube 1120C, and heat transfer tube 1300 of the distribution header 1100. The liquid level 2000 is the same as that described in the first embodiment.

[0055] Fig. 13 is a view from the Y direction showing the state of the refrigerant in the distribution header 1100 according to embodiment 2, where the distance H in the Z direction between the heat transfer tube lower end 1310 and the bottom wall 1112B is longer than the distance W in the X direction between the two first side walls 1111A. Fig. 14 is a view from the X direction showing the state of the refrigerant shown in Fig. 13. Fig. 15 is a view from the Y direction showing the state of the refrigerant in a distribution header having the same cross-sectional area as the distribution header 1100 of Fig. 13, where the distance H is shorter than the distance W. Fig. 16 is a view from the X direction showing the state of the refrigerant shown in Fig. 15.

[0056] When the distance H is shorter than the distance W, the distance between the lower end 1310 of the heat transfer tube 1300 and the orifice 1121 of the inner tube 1120C becomes shorter, as shown in FIG. 15 . This significantly affects the refrigerant ejected from the orifice 1121. For example, as shown in FIG. 16 , a large amount of liquid refrigerant passes through the heat transfer tube 1300 close to the refrigerant inlet / outlet tube 1120 on the refrigerant inlet side, while portions of the tube farther from the refrigerant inlet / outlet tube 1120 experience less liquid refrigerant. This results in a large change in the liquid level 2000 in the Y direction in the outer tube 1110C of the distribution header 1100, and less liquid refrigerant passes through the heat transfer tube 1300 that is not close to the refrigerant inlet / outlet tube 1120. This causes a bias in the ratio of gas refrigerant to liquid refrigerant depending on the position of the heat transfer tube 1300.

[0057] On the other hand, when the distance H is longer than the distance W, as shown in FIG. 13 , the distance between the heat transfer tube lower end 1310 of the heat transfer tube 1300 and the orifice 1121 of the inner tube 1120C is greater than in the case of FIG. 15 . Therefore, the orifice 1121 has less effect on the refrigerant passing through the heat transfer tube 1300. Liquid refrigerant that does not pass through the heat transfer tube 1300 close to the refrigerant inlet / outlet tube 1120 reaches a position away from the refrigerant inlet / outlet tube 1120, thereby reducing the change in the liquid level 2000 in the Y direction in the outer tube 1110C of the distribution header 1100. Therefore, liquid refrigerant can pass through even the heat transfer tubes 1300 that are not close to the refrigerant inlet / outlet tube 1120, and the ratio of gas refrigerant to liquid refrigerant passing through each heat transfer tube 1300 can be made more uniform.

[0058] As described above, in the heat exchanger 1000 according to the second embodiment, the distribution header 1100 is a refrigerant distributor with a double-pipe structure including an outer pipe 1110C and an inner pipe 1120C. In the distribution header 1100, the outer pipe 1110C includes a first member 1111 that forms the top and two side surfaces, and a second member 1112 that forms the bottom surface. The first member 1111 covers the second member 1112. The distribution header 1100 is shaped such that the distance H between the heat transfer tube lower end 1310 of the heat transfer tube 1300 and the bottom wall 1112B is longer than the distance W between the two first side walls 1111A. A gap is provided within the outer pipe 1110C between the heat transfer tube lower end 1310 of the heat transfer tube 1300 and the orifice 1121 of the inner pipe 1120C. This makes it possible to reduce the amount of refrigerant remaining in the heat exchanger 1000 while improving the distribution of the refrigerant flowing into each heat transfer tube 1300 so as to reduce the unevenness of the distribution. Therefore, it is possible to reduce the amount of refrigerant in the entire refrigerant circuit.

[0059] Because the second member 1112 of the outer pipe 1110C is located lower in the Z direction than the positions of the multiple orifices 1121, it is possible to reduce the amount of liquid refrigerant by maintaining the momentum of the two-phase gas-liquid refrigerant being ejected from the orifices 1121. Furthermore, because the dimensional center of the inner pipe 1120C in the Z direction is located lower than the dimensional center of the outer pipe 1110C in the Z direction, the internal volume of the space below the outer pipe 1110C is reduced, and the amount of refrigerant remaining in the heat exchanger 1000 can be reduced.

[0060] Furthermore, the position of the orifice 1121 of the inner pipe 1120C in the Z direction is higher than the position of the second side wall upper end 1112D of the second side wall 1112A in the Z direction. By ejecting the gas-liquid two-phase refrigerant from the orifice 1121 while maintaining its momentum, liquid refrigerant can be reduced. Furthermore, the multiple orifices 1121 of the inner pipe 1120C are installed in a direction that faces downwind in the airflow. Therefore, in the heat transfer pipe 1300, gas-liquid two-phase refrigerant with a higher proportion of liquid refrigerant flows into the upwind flow path, and gas-liquid refrigerant with a higher proportion of gas refrigerant flows into the downwind flow path. This improves the heat exchange efficiency of the heat exchanger 1000.

[0061] Embodiment 3 Fig. 17 is a diagram showing a part of a cross section of a heat exchanger 1000 according to embodiment 3 when viewed from the Y direction. In Fig. 17, components and the like having the same reference numerals as those in Figs. 5 and 12 perform the same functions and operations as those described in embodiment 1 and embodiment 2.

[0062] As shown in FIG. 17 , the heat exchanger 1000 of the third embodiment has a chamfered second side wall upper end 1112D of the second side wall 1112A of the second member 1112 of the outer tube 1110C. By chamfering and inclining the second side wall upper end 1112D of the second side wall 1112A, the diameter of the inner tube 1120C can be increased by the amount of the corner removed. This increases the internal volume of the space within the inner tube 1120C. Increasing the internal volume of the space within the inner tube 1120C reduces the internal volume of the space outside the inner tube 1120C within the outer tube 1110C. In particular, reducing the internal volume of the lower portion of the space within the outer tube 1110C reduces the area where liquid refrigerant is likely to stagnate.

[0063] Embodiment 4 Fig. 18 is a diagram showing a part of a cross section of a heat exchanger 1000 according to embodiment 4 when viewed from the Y direction. In Fig. 18, components and the like having the same reference numerals as those in Figs. 5 and 12 perform the same functions and operations as those described in embodiment 1 and embodiment 2.

[0064] As shown in Figure 18, in the heat exchanger 1000 of the fourth embodiment, the inner tube 1120C has a flat upper surface and curved other surfaces, resulting in a D-shaped cross section. The D-shaped cross section of the inner tube 1120C allows for a larger cross-sectional area of ​​the inner tube 1120C, thereby increasing the internal volume of the space within the tube. Increasing the internal volume of the space within the inner tube 1120C allows for a reduction in the internal volume of the space within the outer tube 1110C, except for the inner tube 1120C. In particular, the reduction in the internal volume of the lower portion of the space within the outer tube 1110C reduces the area where liquid refrigerant is likely to stagnate.

[0065] 100 Indoor unit, 110 Indoor heat exchanger, 120 Throttle device, 130 Indoor blower, 200 Outdoor unit, 210 Compressor, 220 Four-way valve, 230 Outdoor heat exchanger, 240 Auxiliary heat exchanger, 250 Refrigerant amount control valve, 260 Bypass piping, 270 Accumulator, 280 Outdoor blower, 300 Refrigerant piping, 400 Control device, 1000, 1000A, 1000B Heat exchanger, 1100, 1100A, 1100B Distribution header, 1110, 1110A, 1110B Header pipe, 1110C Outer pipe, 1111 First member, 1111A First side wall, 1111B Top wall, 1111C First connection portion, 1111D Lower end of first side wall, 1112 second member, 1112A second side wall, 1112B bottom wall, 1112C second connection portion, 1112D upper end of second side wall, 1113 lid body, 1120, 1120A, 1120B refrigerant inlet / outlet pipes, 1120C inner pipe, 1121 orifice, 1200 folded header, 1300 heat transfer pipe, 1310 lower end of heat transfer pipe, 1400 corrugated fin, 2000 liquid level.

Claims

1. A heat exchanger comprising: a plurality of heat transfer tubes arranged side by side and spaced apart along a horizontal direction, with a flow path through which a refrigerant flows in a vertical direction; and a header having a cylindrical header tube extending in the direction in which the plurality of heat transfer tubes are arranged, wherein the header tube has: a first member having a top wall into which lower ends of the plurality of heat transfer tubes are inserted and two first side walls extending downward from both ends of the top wall and opposing each other; and a second member having a bottom wall and two second side walls extending upward from both ends of the bottom wall and opposing each other, wherein the distance between the two second side walls is narrower than the distance between the two first side walls, the height of the first side wall is greater than the height of the second side wall, and the first side wall covers a portion of the second side wall to form the cylindrical shape, and the distance within the header tube from the lower ends of the heat transfer tubes to the bottom wall is longer than the distance between the two first side walls.

2. A heat exchanger as described in claim 1, wherein the lower ends of the two first side walls of the first member are bent in a direction narrowing the distance between the walls, and the lower ends of the first side walls cover a portion of the outer surface of the bottom wall of the second member.

3. A heat exchanger comprising: a header having a plurality of heat transfer tubes arranged side by side with spaces between them along the horizontal direction and having a flow path through which a refrigerant flows in the vertical direction; an outer tube extending in the direction in which the plurality of heat transfer tubes are arranged; and an inner tube installed within the outer tube, wherein the outer tube has a first member having a top wall into which the lower ends of the plurality of heat transfer tubes are inserted and two first side walls extending downward from both ends of the top wall and opposing each other, and a second member having a bottom wall and two second side walls extending upward from both ends of the bottom wall and opposing each other, wherein the first side walls cover a portion of the second side walls to form a cylindrical shape, and the inner tube has a plurality of orifices that allow the refrigerant to communicate between the outer tube and the inner tube.

4. A heat exchanger as described in any one of claims 1 to 3, wherein a second connection portion which is a connection portion between the bottom wall of the second member and each of the two second side walls, and a first connection portion which is a connection portion between the top wall of the first member and each of the two first side walls, have inner surfaces formed with a curved surface, and a bending radius R2 of the second connection portion and a bending radius R1 of the first connection portion satisfy the relationship R2 < R1.

5. A heat exchanger as described in any one of claims 1 to 4, wherein the top wall of the first member is a wall having a curved surface that protrudes upward in the height direction, and the bottom wall of the second member is a wall having a curved surface that protrudes downward in the height direction, and the radius of the arc of the bottom wall is larger than the radius of the arc of the top wall.

6. A heat exchanger as described in any one of claims 1 to 5, wherein the ratio of the distance between the top wall and the bottom wall on the outer surface of the header to the distance between the first side walls is greater than 1 and not greater than 2.

4.

7. A heat exchanger as claimed in claim 3, wherein the position of the dimensional center in the height direction of said inner tube is lower than the position of the dimensional center in the height direction of said outer tube.

8. A heat exchanger as described in claim 3 or claim 7, wherein the height position of the orifice of the inner tube is higher than the height position of the upper end of the second member.

9. A heat exchanger as described in claim 3, claim 7 or claim 8, wherein the inner tube is on the downwind side of the air flow passing through the heat transfer tube and has the plurality of orifices located below the dimensional center of the inner tube in the height direction.

10. A heat exchanger as described in any one of claims 3 and 7 to 9, wherein the second member has a shape in which a portion of the upper end portion of the second side wall in each of the two second side walls is chamfered.

11. A heat exchanger as claimed in any one of claims 3 and 7 to 10, wherein the inner tube is a tube having a flat upper surface and curved other surfaces, and having a D-shaped cross section.

12. An outdoor unit having a heat exchanger according to any one of claims 1 to 11 as an outdoor heat exchanger.

13. An air conditioner comprising: an outdoor unit according to claim 12; and an indoor unit having an indoor heat exchanger and a throttling device, for conditioning the air in a space to be air-conditioned.

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