Outdoor unit of air conditioner and air conditioner

Abstract

This outdoor machine for an air conditioning device comprises a heat exchanger having first and second heat exchangers connected in series. The first heat exchanger is connected to the second heat exchanger on the downstream side of a refrigerant flow when the heat exchangers function as condensers, has a plurality of flat tubes spaced apart from each other in a horizontal direction with a vertical direction set as a tube extending direction, and is provided with a plurality of heat exchange bodies arrayed in an air flowing direction and a first header provided to the lower part of, among the plurality of heat exchange bodies, a heat exchange body on the side of an inlet into which a refrigerant flows when the heat exchangers function as the condensers. The first header is formed into a double-tube structure having an inner tube formed by spacing apart a plurality of orifices through which the refrigerant flows and an outer tube into which the inner tube is inserted.

Description

Technical Field

[0001] The present disclosure relates to an outdoor unit of an air conditioner and an air conditioner configured by providing a plurality of heat exchangers each having a plurality of flat tubes.

Background Art

[0002] A heat exchanger using a flat tube as a heat transfer tube is known. Since the flat tube has a smaller diameter than a circular tube, when used as a heat transfer tube of a heat exchanger, the number of refrigerant branches increases compared to the case of using a circular tube as the heat transfer tube. In order for the performance of the heat exchanger to be efficiently exhibited, it is necessary that the gas-liquid two-phase refrigerant flowing in the manifold such as a header be appropriately distributed to each flat tube according to the amount of heat exchange in the heat exchanger.

[0003] For example, Patent Document 1 describes an outdoor unit of an air conditioner including a heat exchanger having a heat exchange body with a plurality of flat tubes whose tubes extend in the vertical direction and are arranged at intervals in the horizontal direction. The heat exchanger includes a plurality of heat exchange bodies provided in the air flow direction, and a header into which hot gas refrigerant flows from a refrigerant circuit is provided at the lower part of the most upstream heat exchange body among the plurality of heat exchange bodies. Further, a double-tube distributor for distributing the refrigerant in a gas-liquid two-phase state is provided at the lower part of the most downstream heat exchange body among the plurality of heat exchange bodies when the heat exchanger functions as an evaporator. By providing such a distributor, the heating capacity of the heat exchanger can be improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the outdoor unit of an air conditioner, a plurality of heat exchangers may be connected in series and used. Also, a partition may be provided inside the header of one heat exchanger, and one heat exchanger may be used as if it were two heat exchangers connected in series.

[0006] As the plurality of heat exchangers connected in series, the heat exchangers described in Patent Document 1 are used. When these heat exchangers function as condensers, the refrigerant in a gas-liquid two-phase state flows into the heat exchanger arranged on the downstream side of the refrigerant flow. At this time, in the header of the heat exchanger into which the refrigerant in a gas-liquid two-phase state flows, the refrigerant is distributed such that a large amount of gas refrigerant exists on the front side near the inlet and a large amount of liquid refrigerant exists on the back side.

[0007] As described above, when the heat exchanger described in Patent Document 1 functions as a condenser, the refrigerant in a gas-liquid two-phase state flowing into the downstream heat exchanger is not appropriately distributed to each flat tube depending on its distribution state, so there has been a problem that the condenser performance of the heat exchanger deteriorates.

[0008] The present disclosure has been made in view of the above problems in the conventional technology, and an object thereof is to provide an outdoor unit of an air conditioner and an air conditioner that can improve the distribution of refrigerant when a plurality of heat exchangers connected in series function as condensers and improve the heat exchange performance.

Means for Solving the Problems

[0009] The outdoor unit of an air conditioner according to the present disclosure is an outdoor unit of an air conditioner including a heat exchanger having a first heat exchanger and a second heat exchanger connected in series. The first heat exchanger is connected to the second heat exchanger on the downstream side of the refrigerant flow when the heat exchanger functions as a condenser. It has a plurality of flat tubes arranged at intervals in the horizontal direction with the vertical direction as the tube extending direction, a plurality of heat exchange bodies arranged in the air flow direction, and a first header provided at the lower part of the heat exchange body on the inlet side where the refrigerant flows in when the heat exchanger functions as a condenser among the plurality of heat exchange bodies. , a second header provided at a lower portion of the heat exchanger on the inlet side where refrigerant flows when the heat exchanger functions as an evaporator among the plurality of heat exchangers; comprises, and the first header has a double-tube structure having an inner tube in which a plurality of orifices through which the refrigerant flows are formed at intervals, and an outer tube into which the inner tube is inserted. and, the orifice formed in the first header is formed in the inner tube so as to open while being inclined in the circumferential direction by a preset first angle from the lower end of the inner tube on a vertical line passing through the center of the inner tube, the second header has a double tube structure including an inner tube in which a plurality of orifices through which the refrigerant flows are formed at intervals and an outer tube into which the inner tube is inserted, the orifice formed in the second header is formed in the inner tube so as to open while being inclined in the circumferential direction by a preset second angle from the lower end of the inner tube on a vertical line passing through the center of the inner tube of the second header, and the second angle is formed to be different from the first angle is such.

[0010] Further, the air conditioner according to the present disclosure includes the above-described outdoor unit.

Effects of the Invention

[0011] According to the present disclosure, in the first heat exchanger connected to the downstream side of the refrigerant flow when the heat exchanger functions as a condenser, the first header is provided at the lower part of the heat exchange body on the inlet side where the refrigerant flows in. Further, the first header has a double-tube structure, and a plurality of orifices through which the refrigerant flows are formed at intervals in the inner tube. Thereby, when the heat exchanger functions as a condenser, the refrigerant flowing into the first heat exchanger is uniformly distributed, so that the heat exchange performance of the heat exchanger can be improved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present disclosure. Further, the present disclosure includes all combinations of configurations that can be combined among the configurations shown in the following embodiments. Also, in each figure, those with the same reference numerals are the same or corresponding ones, which is common throughout the entire specification. Furthermore, in the following description, the upper side in FIG. 1 will be referred to as the "upper side" and the lower side as the "lower side" for explanation. Moreover, the high and low of pressure and temperature are not determined in relation to absolute values, but are relatively determined in the states and operations of the device and the like. In the cross-sectional views of the drawings, hatching is omitted as appropriate for visibility.

[0014] Embodiment 1. The air conditioner according to Embodiment 1 of the present disclosure will be described. The air conditioner according to Embodiment 1 of the present disclosure circulates refrigerant in a refrigerant circuit and transfers heat between outdoor air and indoor air via the refrigerant, thereby performing air conditioning of the air-conditioned space.

[0015] [Configuration of Air Conditioner 100] FIG. 1 is a circuit diagram showing an example of the configuration of an air conditioner according to Embodiment 1. As shown in FIG. 1, the air conditioner 100 includes an outdoor unit 10 and one or more indoor units 20. The outdoor unit 10 and the indoor units 20 are connected by refrigerant pipes through which refrigerant flows. By connecting the outdoor unit 10 and the indoor units 20 with refrigerant pipes, a refrigerant circuit through which the refrigerant circulates is formed. In this example, three indoor units 20 are connected, but the number is not limited to this, and the number of indoor units 20 may be one or two, or four or more.

[0016] (Outdoor unit 10) The outdoor unit 10 has a compressor 11, a refrigerant flow path switching device 12, an outdoor heat exchanger 13, an accumulator 14, and a fan 15.

[0017] The compressor 11 sucks in low-temperature and low-pressure refrigerant, compresses the sucked refrigerant, and discharges high-temperature and high-pressure refrigerant. The compressor 11 is composed of, for example, an inverter compressor or the like whose capacity, which is the amount of refrigerant delivered per unit time, is controlled by changing the operating frequency.

[0018] The refrigerant flow path switching device 12 is, for example, a four-way valve, and switches the direction of the refrigerant flow to switch between cooling operation and heating operation. The refrigerant flow path switching device 12 is not limited to the above-described four-way valve, and for example, other valves may be used in combination.

[0019] The outdoor heat exchanger 13 exchanges heat between the outdoor air supplied by the fan 15, which is a blower provided in the vicinity, and the refrigerant. Specifically, the outdoor heat exchanger 13 functions as a condenser that releases the heat of the refrigerant to the outdoor air during cooling operation to condense and liquefy the refrigerant. Also, the outdoor heat exchanger 13 functions as an evaporator that evaporates the refrigerant to gasify it and absorbs heat from the outdoor air as latent heat of vaporization during heating operation.

[0020] In this example, the outdoor heat exchanger 13 is configured such that the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c are connected in parallel to each other, and the first outdoor heat exchanger 13a is connected in series to the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c that are connected in parallel. Here, when the outdoor heat exchanger 13 functions as a condenser, the first outdoor heat exchanger 13a is connected to the downstream side of the refrigerant flow with respect to the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c. Note that the "first outdoor heat exchanger 13a", "second outdoor heat exchanger 13b", and "third outdoor heat exchanger 13c" may sometimes be referred to as the "first heat exchanger 13a", "second heat exchanger 13b", and "third heat exchanger 13c", respectively.

[0021] Also, the configuration of the outdoor heat exchanger 13 is not limited to this example. In the air conditioner 100 according to the first embodiment, at least two outdoor heat exchangers 13 may be connected in series. Specifically, for example, the first outdoor heat exchanger 13a and the second outdoor heat exchanger 13b may be connected in series. And when the outdoor heat exchanger 13 functions as a condenser, the first outdoor heat exchanger 13a is connected to the downstream side of the refrigerant flow with respect to the second outdoor heat exchanger 13b.

[0022] The fan 15 is a blower for supplying outdoor air to the outdoor heat exchanger 13. The rotation speed of the fan 15 is controlled by a control device (not shown). Thereby, the condensing capacity or the evaporating capacity of the outdoor heat exchanger 13 is controlled.

[0023] The accumulator 14 is provided on the suction side of the compressor 11. The accumulator 14 stores surplus refrigerant generated due to the difference in the operating states between the cooling operation and the heating operation, and surplus refrigerant for transient operation changes. Note that the accumulator 14 does not necessarily have to be provided.

[0024] (Indoor unit 20) Each indoor unit 20 has a throttling device 21 and an indoor heat exchanger 22. The throttling device 21 is, for example, an expansion valve, which reduces the pressure of the refrigerant and expands it. The throttling device 21 is composed of a valve that can control the opening degree, such as an electronic expansion valve.

[0025] The indoor heat exchanger 22 performs heat exchange between the indoor air supplied by a blower (not shown) such as a fan and the refrigerant. Thereby, warm air or cold air, which is the conditioned air supplied to the air-conditioning target space, is generated. The indoor heat exchanger 22 functions as an evaporator during the cooling operation. Also, the indoor heat exchanger 22 functions as a condenser during the heating operation.

[0026] [Structure of the outdoor unit 10] FIG. 2 is a perspective view showing an example of the appearance of the outdoor unit in FIG. 1. In FIG. 2, the arrangement state of the outdoor heat exchanger 13 inside the outdoor unit 10 is shown so as to be understandable.

[0027] As shown in FIG. 2, the outdoor unit 10 according to the first embodiment is formed in a rectangular parallelepiped shape with a rectangular shape in a top view. In the outdoor unit 10, a first outdoor heat exchanger 13a, a second outdoor heat exchanger 13b, and a third outdoor heat exchanger 13c are provided in a C shape along three of the four side faces. Also, a fan 15 is provided at the upper part of the outdoor unit 10 so as to blow air upward. Thus, the outdoor unit 10 according to the first embodiment is a top-flow type in which the fan 15 that blows air upward is arranged above the outdoor heat exchanger 13 composed of a plurality of heat exchangers.

[0028] (The first outdoor heat exchanger 13a) FIG. 3 is a perspective view showing an example of the appearance of the first outdoor heat exchanger according to the first embodiment. The white arrow in FIG. 3 indicates the flow of the wind generated by the fan 15. Also, the dotted arrow indicates the flow of the refrigerant when the outdoor heat exchanger 13 functions as a condenser.

[0029] As shown in FIG. 3, the first outdoor heat exchanger 13a has a plurality of heat exchangers 50 arranged in the air flow direction. In this example, two heat exchangers 50 are arranged in order in the air flow direction with the same size.

[0030] The heat exchanger 50 has a plurality of flat tubes 51 arranged at intervals in the horizontal direction with the vertical direction as the tube extension direction. The plurality of flat tubes 51 are arranged in parallel in the horizontal direction at intervals so that the air generated by the fan 15 flows, and the refrigerant flows in the vertical direction in the tubes extending in the vertical direction.

[0031] In addition, fins 52 joined to the flat tubes 51 for heat transfer to the flat tubes 51 are provided between the adjacent flat tubes 51. The fins 52 improve the heat exchange efficiency between the air and the refrigerant. For example, corrugated fins are used as the fins 52. Note that when sufficient heat exchange between the air and the refrigerant can be performed on the surface of the flat tube 51, the fins 52 may not be provided.

[0032] A first header 53 is provided at the lower part of the heat exchanger 50 on the leeward side among the plurality of heat exchangers 50. The first header 53 extends in the arrangement direction of the plurality of flat tubes 51, and the lower ends of the flat tubes 51 of the heat exchanger 50 arranged on the most leeward side are directly inserted into the first header 53. The first header 53 is connected to the refrigerant circuit of the air conditioner 100 via a refrigerant pipe 56.

[0033] When the air conditioner 100 performs a cooling operation and the outdoor heat exchanger 13 functions as a condenser, the two-phase refrigerant flowing out from the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c flows into the first header 53 via the refrigerant pipe 56. Further, when the air conditioner 100 performs a heating operation and the outdoor heat exchanger 13 functions as an evaporator, the first header 53 allows the two-phase refrigerant heat-exchanged in the heat exchanger 50 on the most leeward side to flow out via the refrigerant pipe 56.

[0034] At the lower part of the heat exchanger 50 on the most upstream side among the plurality of heat exchangers 50, a second header 54 is provided. The second header 54 extends in the arrangement direction of the plurality of flat tubes 51 and is arranged in parallel with the first header 53. The lower ends of the flat tubes 51 of the heat exchanger 50 arranged on the most upstream side are directly inserted into the second header 54. The second header 54 is connected to the refrigerant circuit of the air conditioner 100 via a refrigerant pipe 57.

[0035] When the outdoor heat exchanger 13 functions as a condenser, the second header 54 allows the liquid refrigerant heat-exchanged in the heat exchanger 50 on the most upstream side to flow out via the refrigerant pipe 57. Also, when the outdoor heat exchanger 13 functions as an evaporator, the two-phase refrigerant flowing out from the throttling device 21 of the indoor unit 20 flows into the second header 54 via the refrigerant pipe 57.

[0036] At the upper part of the plurality of heat exchangers 50, a third header 55 is provided into which the upper ends of the plurality of flat tubes 51 inserted into the first header 53 and the second header 54 are inserted. When the outdoor heat exchanger 13 functions as a condenser, the third header 55 causes the refrigerant flowing in from the downstream flat tubes 51 to flow back into the upstream flat tubes 51. Also, when the outdoor heat exchanger 13 functions as an evaporator, the third header 55 causes the refrigerant flowing in from the upstream flat tubes 51 to flow back into the downstream flat tubes 51.

[0037] The plurality of flat tubes 51, fins 52, first header 53, second header 54, third header 55, and refrigerant pipes 56 and 57 are each made of, for example, aluminum and are joined by brazing.

[0038] (Second outdoor heat exchanger 13b and third outdoor heat exchanger 13c) FIG. 4 is a perspective view showing an example of the appearance of the second outdoor heat exchanger or the third outdoor heat exchanger according to Embodiment 1. The white arrows in FIG. 4 indicate the flow of the wind generated by the fan 15. Since the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c have the same configuration, the second outdoor heat exchanger 13b will be described as an example here.

[0039] As shown in FIG. 4, the second outdoor heat exchanger 13b has a plurality of heat exchange elements 50, similar to the first outdoor heat exchanger 13a. In this example, two heat exchange elements 50 are arranged in the air flow direction in order with the same size.

[0040] The heat exchange element 50 is provided with a plurality of flat tubes 51 and fins 52, similar to the first outdoor heat exchanger 13a. Note that the fins 52 may not be provided.

[0041] A fourth header 63 is provided at the lower part of the heat exchange element 50 on the leeward side among the plurality of heat exchange elements 50. The fourth header 63 extends in the arrangement direction of the plurality of flat tubes 51, and the lower ends of the flat tubes 51 of the heat exchange element 50 arranged on the most leeward side are directly inserted into the fourth header 63. The fourth header 63 is connected to the refrigerant circuit of the air conditioner 100 via a refrigerant pipe 66, and hot gas refrigerant flows in from the refrigerant circuit.

[0042] When the outdoor heat exchanger 13 functions as a condenser by the air conditioner 100 performing a cooling operation, high-temperature and high-pressure gas refrigerant from the compressor 1 flows into the fourth header 63 via the refrigerant pipe 66. Also, when the outdoor heat exchanger 13 functions as an evaporator by the air conditioner 100 performing a heating operation, the fourth header 63 allows the gas refrigerant heat-exchanged in the heat exchange element 50 on the most leeward side to flow out via the refrigerant pipe 66.

[0043] A fifth header 64 is provided at the lower part of the heat exchange element 50 on the windward side among the plurality of heat exchange elements 50. The fifth header 64 extends in the arrangement direction of the plurality of flat tubes 51 and is arranged in parallel with the fourth header 63. The lower ends of the flat tubes 51 of the heat exchange element 50 arranged on the most windward side are directly inserted into the fifth header 64. The fifth header 64 is connected to the refrigerant circuit of the air conditioner 100 via a refrigerant pipe 67.

[0044] When the outdoor heat exchanger 13 functions as a condenser, the fifth header 64 causes the two-phase refrigerant heat-exchanged by the heat exchanger 50 on the most upstream side to flow out via the refrigerant pipe 67. Also, when the outdoor heat exchanger 13 functions as an evaporator, the two-phase refrigerant flowing out from the first outdoor heat exchanger 13a flows into the fifth header 64 via the refrigerant pipe 67.

[0045] At the upper part of the plurality of heat exchangers 50, a sixth header 65 into which the upper ends of the plurality of flat tubes 51 inserted into the fourth header 63 and the fifth header 64 are inserted is provided. When the outdoor heat exchanger 13 functions as a condenser, the sixth header 65 causes the refrigerant flowing in from the flat tube 51 on the downstream side to flow back into the flat tube 51 on the upstream side. Also, when the outdoor heat exchanger 13 functions as an evaporator, the sixth header 65 causes the refrigerant flowing in from the flat tube 51 on the upstream side to flow back into the flat tube 51 on the downstream side.

[0046] The plurality of flat tubes 51, fins 52, fourth header 63, fifth header 64, sixth header 65, and refrigerant pipes 66 and 67 are each made of, for example, aluminum and are joined by brazing.

[0047] [Structure of the First Header 53, Second Header 54, and Fifth Header 64] The structures of the first header 53 and second header 54 provided in the first outdoor heat exchanger 13a, and the fifth header 64 provided in the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c will be described. Note that since the first header 53, second header 54, and fifth header 64 have the same structure, the first header 53 will be described as an example here. Also, the "first header 53", "second header 54", and "fifth header 64" in the first embodiment of the present disclosure respectively correspond to the "first header", "second header", and "third header" in the present disclosure.

[0048] FIG. 5 is a perspective view showing an example of the appearance of the first header in FIG. 3. FIG. 6 is a schematic cross-sectional view schematically showing a cross-section obtained by cutting the first header with a plane perpendicular to the extending direction. In FIG. 5, the internal configuration of the first header 53 is shown by a dotted line for easy understanding of the internal configuration of the first header 53.

[0049] The first header 53 has a double-tube structure having an inner tube 71 and an outer tube 72. The inner tube 71 and the outer tube 72 extend linearly in the tube extending direction. The inner tube 71 is inserted inside the outer tube 72. The inner tube 71 and the outer tube 72 are joined by brazing.

[0050] The inner tube 71 is, for example, a circular tube and is connected to the refrigerant pipe 56. A plurality of orifices 73 through which the refrigerant flows are formed in the inner tube 71 at intervals in the extending direction. Thus, when the outdoor heat exchanger 13 functions as a condenser, the refrigerant flowing into the inner tube 71 of the first header 53 through the refrigerant pipe 56 flows into the outer tube 72 through the plurality of orifices 73.

[0051] The outer tube 72 is a tube having a U-shaped cross-section with the lower part formed in an arc shape. The outer tube 72 having a U-shaped cross-section smoothly changes the refrigerant flowing out from the inner tube 71 along the arc.

[0052] (Orifice 73) The plurality of orifices 73 are formed to open at an angle φ preset from the lower end of the inner tube 71 on the vertical line passing through the center of the inner tube 71 in the circumferential direction. Thus, by forming the orifices 73 to be inclined by the set angle φ, the liquid refrigerant and the gas refrigerant in the two-phase refrigerant flowing into the inner tube 71 are uniformly distributed regardless of the distance from the refrigerant inlet side of the first header 53. opt only opt by being inclined, the liquid refrigerant and the gas refrigerant in the two-phase refrigerant flowing into the inner tube 71 are uniformly distributed regardless of the distance from the refrigerant inlet side of the first header 53.

[0053] FIG. 7 is a schematic diagram for explaining the angle of the orifice. In the first embodiment where there are two states of refrigerant, a liquid phase and a gas phase, in the inner pipe 71, the orifice 73 is provided at a position where the refrigerant in both the liquid phase and the gas phase existing in the inner pipe 71 can pass through appropriately.

[0054] Specifically, assuming that the slip ratio of the gas and liquid of the refrigerant is 1 and the gas-liquid interface is flat and horizontal, the liquid level angle, which is the angle in this case, is defined as "φ0", and the wetting boundary angle, which is the angle in the circumferential direction of the pipe considering the slip ratio and inertial force of the gas and liquid of the refrigerant, is defined as "φ S ". When this is the case, the angle φ opt is represented by Equation (1). φ0 < φ opt < φ S ···(1)

[0055] Note that the liquid level angle φ0 is, more specifically, the angle seen from the center of the inner pipe 71 from the lower end of the inner pipe 71 on the vertical line passing through the center of the inner pipe 71 to the liquid level AL in contact with the inner pipe 71. Also, the wetting boundary angle φ S is, more specifically, the angle seen from the center of the inner pipe 71 from the lower end of the inner pipe 71 on the vertical line passing through the center of the inner pipe 71 to the position that reaches while contacting the inner pipe 71 due to inertial force or the like.

[0056] Also, when the flow path cross-sectional area of the inner pipe 71 is defined as "AS [mm 2 ", the liquid level angle φ0 is represented by Equation (2), and the wetting boundary angle φ S is represented by Equation (3). Note that Equations (2) and (3) were obtained through the study by the inventors in the document "International Publication No. 2021 / 235463". φ0 = (-0.0408 × AS + 74.124) × 0.62 ···(2) φ S = (-0.0408 × AS + 74.124) × 1.2 ···(3)

[0057] Therefore, the orifices 73 are provided at equal intervals at positions satisfying the formulas (1) to (3). As a result, the two-phase refrigerant flowing into the first header 53 is uniformly distributed to the plurality of flat tubes 51 regardless of the position inside the header.

[0058] [Refrigerant Operation of the Air Conditioner 100] Next, the operation of the air conditioner 100 configured as described above will be described with reference to FIG. 1. Here, as an example, the flow of the refrigerant when the air conditioner 100 performs a cooling operation and a heating operation will be described. Note that the air conditioner 100 is not limited to this example, and can also perform various operations possible for general air conditioners such as a blowing operation and a defrosting operation.

[0059] (Cooling Operation) When the air conditioner 100 performs a cooling operation, first, the refrigerant flow path switching device 12 is switched to the state shown by the solid line in FIG. 1. That is, the refrigerant flow path switching device 12 is switched so that the discharge side of the compressor 11 is connected to the outdoor heat exchanger 13 and the suction side of the compressor 11 is connected to the indoor heat exchanger 22.

[0060] When the compressor 11 is driven, a high-temperature and high-pressure gas refrigerant is discharged from the compressor 11. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 13 that functions as a condenser via the refrigerant flow path switching device 12. In the outdoor heat exchanger 13, heat exchange is performed between the flowing-in high-temperature and high-pressure gas refrigerant and the outdoor air supplied by the fan 15. As a result, the high-temperature and high-pressure gas refrigerant condenses into a low-temperature and high-pressure liquid refrigerant and flows out of the outdoor heat exchanger 13. Then, the low-temperature and high-pressure liquid refrigerant flowing out of the outdoor heat exchanger 13 flows out of the outdoor unit 10.

[0061] The low-temperature and high-pressure liquid refrigerant flowing out of the outdoor unit 10 flows into each indoor unit 20. In each indoor unit 20, the low-temperature and high-pressure liquid refrigerant expands in the throttling device 21 and becomes a two-phase refrigerant in which the low-temperature and low-pressure gas refrigerant and the liquid refrigerant are mixed. The low-temperature and low-pressure two-phase refrigerant flows into the indoor heat exchanger 22 that functions as an evaporator. In the indoor heat exchanger 22, heat exchange is performed between the introduced low-temperature and low-pressure two-phase refrigerant and the indoor air supplied by a blower (not shown). As a result, the liquid refrigerant among the two-phase refrigerant evaporates and becomes a high-temperature and low-pressure gas refrigerant, which flows out of the indoor heat exchanger 22. Then, the high-temperature and low-pressure gas refrigerants flowing out of the respective indoor heat exchangers 22 flow out of the indoor unit 20, merge, and flow into the outdoor unit 10.

[0062] The high-temperature and low-pressure gas refrigerant flowing into the outdoor unit 10 flows into the compressor 11 via the refrigerant flow path switching device 12 and the accumulator 14. Hereinafter, by repeating this cycle, the refrigerant circulates through the refrigerant circuit.

[0063] FIG. 8 is a schematic diagram for explaining the flow of the refrigerant in the outdoor heat exchanger when the outdoor heat exchanger functions as a condenser. In FIG. 8, the arrows indicated by solid lines indicate the flow of the refrigerant in the first to third outdoor heat exchangers 13a to 13c constituting the outdoor heat exchanger 13. The dotted lines indicate the connection states of the first to third outdoor heat exchangers 13a to 13c.

[0064] When the outdoor heat exchanger 13 functions as a condenser, such as in a cooling operation, the gas refrigerant discharged from the compressor 11 flows into the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c, respectively. At this time, the gas refrigerant flows into the fourth header 63 on the leeward side of the air flow in the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c via the refrigerant pipe 66, respectively.

[0065] The gaseous refrigerant flowing into the fourth header 63 condenses while passing through the connected flat tube 51 and the sixth header 65, becoming a two-phase refrigerant and flowing into the outer tube 72 of the fifth header 64. Then, the two-phase refrigerant flowing into the outer tube 72 of the fifth header 64 flows out from the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c via the inner tube 71 and the refrigerant pipe 66.

[0066] The two-phase refrigerant flowing out from the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c merges and flows into the first outdoor heat exchanger 13a. The two-phase refrigerant flowing into the first outdoor heat exchanger 13a flows into the inner tube 71 of the first header 53 on the leeward side of the air flow via the refrigerant pipe 56. The two-phase refrigerant flowing into the inner tube 71 of the first header 53 flows into the outer tube 72 via a plurality of orifices 73.

[0067] The two-phase refrigerant flowing into the outer tube 72 of the first header 53 condenses while passing through the connected flat tube 51 and the third header 55, becoming a liquid refrigerant and flowing into the outer tube 72 of the second header 54. Then, the liquid refrigerant flowing into the outer tube 72 of the second header 54 flows out from the first outdoor heat exchanger 13a via the inner tube 71 and the refrigerant pipe 57.

[0068] (Heating operation) Returning to FIG. 1 for the explanation, when the air conditioner 100 executes the heating operation, first, the refrigerant flow path switching device 12 is switched to the state shown by the broken line in FIG. 1. That is, the refrigerant flow path switching device 12 is switched so that the discharge side of the compressor 11 is connected to the indoor heat exchanger 22 and the suction side of the compressor 11 is connected to the outdoor heat exchanger 13.

[0069] When the compressor 11 is driven, a high-temperature and high-pressure gas refrigerant is discharged from the compressor 11. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows out of the outdoor unit 10 via the refrigerant flow path switching device 12. The high-temperature and high-pressure gas refrigerant flowing out of the outdoor unit 10 branches and flows into each indoor unit 20. In each indoor unit 20, the high-temperature and high-pressure gas refrigerant flows into the indoor heat exchanger 22 that functions as a condenser. In the indoor heat exchanger 22, heat exchange is performed between the flowing-in high-temperature and high-pressure gas refrigerant and indoor air supplied by a blower (not shown). As a result, the high-temperature and high-pressure gas refrigerant condenses into a low-temperature and high-pressure liquid refrigerant.

[0070] The low-temperature and high-pressure liquid refrigerant flowing out of the indoor heat exchanger 22 expands in the throttling device 21 and becomes a two-phase refrigerant in which a low-temperature and low-pressure gas refrigerant and a liquid refrigerant are mixed. The low-temperature and low-pressure two-phase refrigerant flows out of each indoor unit 20, merges, and flows into the outdoor unit 10. The low-temperature and low-pressure two-phase refrigerant flowing into the outdoor unit 10 flows into the outdoor heat exchanger 13 that functions as an evaporator. In the outdoor heat exchanger 13, heat exchange is performed between the flowing-in low-temperature and low-pressure two-phase refrigerant and outdoor air supplied by the fan 15. As a result, the liquid refrigerant in the two-phase refrigerant evaporates and becomes a high-temperature and low-pressure gas refrigerant. Then, the high-temperature and low-pressure gas refrigerant flows out of the outdoor heat exchanger 13.

[0071] The high-temperature and low-pressure gas refrigerant flowing out of the outdoor heat exchanger 13 flows into the compressor 11 via the refrigerant flow path switching device 12 and the accumulator 14. Hereinafter, by repeating this cycle, the refrigerant circulates through the refrigerant circuit.

[0072] FIG. 9 is a schematic diagram for explaining the flow of the refrigerant in the outdoor heat exchanger when the outdoor heat exchanger functions as an evaporator. In FIG. 9, the arrows indicated by solid lines show the flow of the refrigerant in the first to third outdoor heat exchangers 13a to 13c that constitute the outdoor heat exchanger 13. Also, the dotted lines show the connection states of the first to third outdoor heat exchangers 13a to 13c.

[0073] When the outdoor heat exchanger 13 functions as an evaporator, such as in the heating operation, etc., the two-phase refrigerant flowing out from the throttling device 21 of the indoor unit 20 flows into the first outdoor heat exchanger 13a. The two-phase refrigerant flowing into the first outdoor heat exchanger 13a flows into the inner pipe 71 of the second header 54 on the most upstream side of the air flow via the refrigerant pipe 57.

[0074] The two-phase refrigerant flowing into the inner pipe 71 of the second header 54 flows into the outer pipe 72 via a plurality of orifices 73. The two-phase refrigerant flowing into the outer pipe 72 of the second header 54 evaporates while passing through the connected flat pipe 51 and the third header 55, and flows into the outer pipe 72 of the first header 53. Then, the two-phase refrigerant flowing into the outer pipe 72 of the first header 53 flows out from the first outdoor heat exchanger 13a via the inner pipe 71 and the refrigerant pipe 56.

[0075] The two-phase refrigerant flowing out from the first outdoor heat exchanger 13a branches and flows into the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c respectively. At this time, the two-phase refrigerant flows into the inner pipe 71 of the fifth header 64 on the most upstream side of the air flow in the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c via the refrigerant pipe 67 respectively.

[0076] The two-phase refrigerant flowing into the inner pipe 71 of the fifth header 64 flows into the outer pipe 72 via a plurality of orifices 73. The two-phase refrigerant flowing into the outer pipe 72 of the fifth header 64 evaporates while passing through the connected flat pipe 51 and the sixth header 65, and becomes a gas refrigerant and flows into the fourth header 63. Then, the gas refrigerant flowing into the fourth header 63 flows out from the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c via the refrigerant pipe 66 respectively.

[0077] As described above, in the outdoor unit 10 of the air conditioner 100 according to the first embodiment, the first outdoor heat exchanger 13a is connected in series with the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c on the downstream side of the refrigerant flow when functioning as a condenser. Further, among the plurality of heat exchange elements 50 of the first outdoor heat exchanger 13a, a first header 53 is provided at the lower part of the heat exchange element on the inlet side where the refrigerant flows in when functioning as a condenser. The first header 53 has a double pipe structure having an inner pipe 71 and an outer pipe 72, and a plurality of orifices 73 are formed in the inner pipe 71 at intervals.

[0078] By having such a configuration, when the outdoor heat exchanger 13 functions as a condenser, the two-phase refrigerant flowing into the first outdoor heat exchanger 13a is uniformly distributed to the plurality of flat tubes 51 constituting the heat exchange element 50. Therefore, the heat exchange performance of the outdoor heat exchanger 13 can be improved.

[0079] Also, in the outdoor unit 10, the orifice 73 formed in the first header 53 is formed in the inner pipe 71 so as to open with an inclination of a set angle φ opt in the circumferential direction from the lower end of the inner pipe 71 on the vertical line passing through the center of the inner pipe 71. The angle φ opt at this time is set to be larger than the liquid level angle φ0 and smaller than the wetting boundary angle φ S . Thereby, the inflowing two-phase refrigerant can be more appropriately distributed to the flat tubes 51.

[0080] Embodiment 2. Next, the second embodiment will be described. The second embodiment is different from the first embodiment in that the angles of the orifices 73 provided in the inner pipes 71 of the first header 53 and the second header 54 are made different. In the second embodiment, the same reference numerals are given to the parts common to the first embodiment, and detailed descriptions thereof are omitted.

[0081] When the outdoor heat exchanger 13 functions as an evaporator, the two-phase refrigerant flowing out from the throttling device 21 of the indoor unit 20 flows into the second header 54 of the first outdoor heat exchanger 13a. On the other hand, when the outdoor heat exchanger 13 functions as a condenser, the two-phase refrigerant flowing out from the second outdoor heat exchanger 13b and the third outdoor heat exchanger 13c flows into the first header 53 of the first outdoor heat exchanger 13a.

[0082] At this time, the dryness at the inlet of the second header 54 when functioning as an evaporator is less than about 0.2, and the dryness at the inlet of the first header 53 when functioning as a condenser is about 0.2 to 0.6. That is, the ratio of the liquid refrigerant is different between the two-phase refrigerant flowing into the second header 54 when functioning as an evaporator and the two-phase refrigerant flowing into the first header 53 when functioning as a condenser. Therefore, if the angles of the orifices 73 in each header are made the same, there is a possibility that the refrigerant cannot be properly distributed depending on the operating state of the outdoor heat exchanger 13.

[0083] Therefore, in the second embodiment, the positions of the orifices 73 in the first header 53 and the second header 54 are made different, and the orifice 73 is arranged at a suitable position according to the operating state.

[0084] FIG. 10 is a schematic diagram for explaining the angles of the orifices of the first header and the second header according to the second embodiment. The dryness at the inlet of the first header 53 when the outdoor heat exchanger 13 functions as a condenser is higher than the dryness at the inlet of the second header 54 when the outdoor heat exchanger 13 functions as an evaporator. Therefore, in the second embodiment, when the angle of the orifice 73b of the second header 54 is "φ opt2 " and the angle of the orifice 73a of the first header 53 is "φ opt1 ", the relationship between the angles of the respective orifices 73 is represented by Equation (4). φ opt2 ≦φ opt1 ···(4)

[0085] Thus, in the second embodiment, the angles of the orifice 73a of the first header 53 and the orifice 73b of the second header 54 are made different. Thereby, the refrigerant flowing into the first outdoor heat exchanger 13a can be appropriately distributed regardless of whether the outdoor heat exchanger 13 functions as a condenser or as an evaporator.

[0086] As described above, the first and second embodiments have been described. However, the present disclosure is not limited to the above-described first and second embodiments, and various modifications and applications are possible without departing from the gist of the present disclosure.

Explanation of reference numerals

[0087] 10 Outdoor unit, 11 Compressor, 12 Refrigerant flow path switching device, 13 Outdoor heat exchanger, 13a First outdoor heat exchanger, 13b Second outdoor heat exchanger, 13c Third outdoor heat exchanger, 14 Accumulator, 15 Fan, 20 Indoor unit, 21 Throttling device, 22 Indoor heat exchanger, 50 Heat exchanger, 51 Flat tube, 52 Fin, 53 First header, 54 Second header, 55 Third header, 56, 57 Refrigerant pipes, 63 Fourth header, 64 Fifth header, 65 Sixth header, 66, 67 Refrigerant pipes, 71 Inner tube, 72 Outer tube, 73, 73a, 73b Orifice, 100 Air conditioner.

Claims

1. An outdoor unit of an air conditioner including a heat exchanger having a first heat exchanger and a second heat exchanger connected in series, The first heat exchanger, is connected to the downstream side of the refrigerant flow when the heat exchanger functions as a condenser with respect to the second heat exchanger, has a plurality of flat tubes arranged at intervals in the horizontal direction with the vertical direction as the tube extending direction, and a plurality of heat exchange bodies arranged in the air flow direction, Among the plurality of heat exchange bodies, a first header provided at the lower part of the heat exchange body on the inlet side where the refrigerant flows in when the heat exchanger functions as a condenser, Among the plurality of heat exchange bodies, a second header provided at the lower part of the heat exchange body on the inlet side where the refrigerant flows in when the heat exchanger functions as an evaporator, and includes, The first header, has a double tube structure having an inner tube in which a plurality of orifices through which the refrigerant flows are formed at intervals, and an outer tube into which the inner tube is inserted, The orifices formed in the first header, are formed in the inner tube so as to open at a preset first angle in the circumferential direction from the lower end of the inner tube on the vertical line passing through the center of the inner tube, The second header, has a double tube structure having an inner tube in which a plurality of orifices through which the refrigerant flows are formed at intervals, and an outer tube into which the inner tube is inserted, The orifices formed in the second header, are formed in the inner tube so as to open at a preset second angle in the circumferential direction from the lower end of the inner tube on the vertical line passing through the center of the inner tube of the second header, and the second angle is formed to be different from the first angle An outdoor unit of an air conditioner.

2. The first angle is, Larger than the liquid level angle of the refrigerant present in the inner pipe and smaller than the wetting boundary angle of the refrigerant The outdoor unit of the air conditioner according to claim 1.

3. The second angle is Equal to or less than the first angle The outdoor unit of the air conditioner according to claim 1 or 2.

4. The heat exchanger provided with the second header is Arranged on the most upstream side in the flow direction of the air for heat exchange The outdoor unit of the air conditioner according to any one of claims 1 to 3.

5. The heat exchanger provided with the first header is Arranged on the most downstream side in the flow direction of the air for heat exchange The outdoor unit of the air conditioner according to any one of claims 1 to 4.

6. The second heat exchanger is Has a plurality of flat tubes arranged at intervals in the horizontal direction with the vertical direction as the tube extension direction, and a plurality of heat exchangers arranged in the air flow direction, and Among the plurality of heat exchangers, a third header provided at the lower part of the heat exchanger on the inlet side where the refrigerant flows in when the heat exchanger functions as an evaporator And is provided with The third header is It has a double tube structure having an inner tube in which a plurality of orifices through which the refrigerant flows are formed at intervals, and an outer tube into which the inner tube is inserted The outdoor unit of the air conditioner according to any one of claims 1 to 5.

7. The heat exchanger provided with the third header is Arranged on the most upstream side in the flow direction of the air for heat exchange The outdoor unit of the air conditioner according to claim 6.

8. An air conditioner including the outdoor unit according to any one of claims 1 to 7.

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