Air conditioner and gas-liquid separator

Abstract

We provide air conditioners that can improve heating performance. [Solution] An air conditioner according to one embodiment comprises a first indoor heat exchanger, a second indoor heat exchanger, an outdoor heat exchanger, a first pipe, a second pipe, a third pipe, and a gas-liquid separator. The first pipe connects the first indoor heat exchanger and the outdoor heat exchanger. The second pipe connects the second indoor heat exchanger and the outdoor heat exchanger. The third pipe connects the first indoor heat exchanger and the second indoor heat exchanger. The gas-liquid separator is provided in the third pipe and supplies the gaseous phase of the refrigerant flowing from the first indoor heat exchanger to the second indoor heat exchanger to the second indoor heat exchanger, and supplies the liquid phase of the refrigerant to the second pipe.

Description

Technical Field

[0001] Embodiments of the present invention relate to an air conditioner and a gas-liquid separator.

Background Art

[0002] An air conditioner adjusts the indoor temperature by condensing and evaporating a refrigerant in a refrigeration cycle. For example, during heating operation, the refrigerant condenses in the indoor heat exchanger and evaporates in the outdoor heat exchanger.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During heating operation, the refrigerant flows into the indoor unit's heat exchanger as a superheated gas and changes from a saturated gas to a two-phase flow while exchanging heat with the room temperature air. In the two-phase flow region, the gaseous refrigerant condenses and liquefies due to heat exchange. The amount of liquid refrigerant gradually increases downstream, and beyond the point where liquefaction is complete, it becomes a supercooled liquid, and the temperature of the liquid refrigerant decreases due to heat exchange with the colder air. Therefore, in the liquid refrigerant portion of the heat exchanger, the temperature difference between the air and the refrigerant becomes small, resulting in reduced heat exchange performance. For example, when operating under conditions of low heat exchange capacity, the refrigerant flowing through the heat exchanger completely condenses in the middle of the refrigerant piping, and the refrigerant piping beyond that point is filled with liquid refrigerant. In this case, only a part of the heat exchanger contributes to condensation. The larger the area contributing to condensation, the larger the heat transfer surface area within the pipe and the smaller the temperature difference between the inner surface of the pipe and the refrigerant. Conversely, if the heat transfer surface area within the pipe is small, it is necessary to increase the temperature difference between the inner surface of the pipe and the refrigerant in order to maintain the same amount of heat exchange, which causes the condensation temperature of the refrigerant to rise. An increase in condensation temperature means an increase in internal pipe pressure, which increases the compressor input and worsens energy efficiency. Additionally, fins connected to piping filled with supercooled liquid will experience a decrease in temperature as the temperature of the liquid refrigerant, the high-temperature source, drops, resulting in reduced heat exchange performance.

[0005] Thus, during heating operation, the condensation completion point in the indoor unit's heat exchanger was too early, resulting in the heat exchanger contributing only partially, which led to problems such as an increase in condensation temperature or a decrease in fin temperature, in other words, a decrease in heating performance.

[0006] One example of a problem that the present invention aims to solve is to provide an air conditioner and a gas-liquid separation device capable of improving heating performance. [Means for solving the problem]

[0007] An air conditioner according to one embodiment comprises a first indoor heat exchanger, a second indoor heat exchanger, an outdoor heat exchanger, a first pipe, a second pipe, a third pipe, and a gas-liquid separator. The first pipe connects the first indoor heat exchanger and the outdoor heat exchanger, through which the refrigerant flows. The second pipe connects the second indoor heat exchanger and the outdoor heat exchanger, through which the refrigerant flows. The third pipe connects the first indoor heat exchanger and the second indoor heat exchanger, through which the refrigerant flows. The gas-liquid separator is provided in the third piping and, in heating operation, supplies the gaseous phase of the refrigerant flowing from the first indoor heat exchanger to the second indoor heat exchanger to the second indoor heat exchanger, and supplies the liquid phase of the refrigerant to the second piping. In cooling operation, it directly flows the gaseous-liquid two-phase refrigerant flowing from the second indoor heat exchanger to the first indoor heat exchanger to the first indoor heat exchanger. The gas-liquid separator has a bent portion, a first pipe portion extending horizontally, downward, or diagonally downward from the bent portion and communicating with the first indoor heat exchanger, a second pipe portion extending downward or diagonally downward from the bent portion and communicating with the second piping, and a third pipe portion extending inside the second pipe portion and communicating the first pipe portion and the second indoor heat exchanger. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic refrigerant system diagram showing an air conditioner during heating operation according to one embodiment. [Figure 2] Figure 2 is a schematic refrigerant system diagram showing the air conditioner during cooling operation in the above embodiment. [Figure 3] Figure 3 is a cross-sectional view showing the indoor unit of the above embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view showing the gas-liquid separation device and the third piping during heating operation in the above embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing the gas-liquid separation device and the third piping during cooling operation in the above embodiment. [Modes for carrying out the invention]

[0009] An embodiment will be described below with reference to Figures 1 to 5. In this specification, the vertically upward direction is generally defined as the upward direction, and the vertically downward direction as the downward direction. Furthermore, in this specification, the components of an embodiment and their descriptions may be described using multiple expressions. The components and their descriptions are examples and are not limited by the expressions used in this specification. Components may also be identified by names different from those used in this specification. Furthermore, components may also be described using expressions different from those used in this specification.

[0010] In the following explanation, “suppress” is defined, for example, as preventing the occurrence of an event, effect, or influence, or reducing the degree of an event, effect, or influence.

[0011] Figure 1 is a schematic refrigerant system diagram showing an air conditioner 10 during heating operation according to one embodiment. The air conditioner 10 is, for example, a household air conditioner. However, the air conditioner 10 is not limited to this example and may be other air conditioners such as commercial air conditioners.

[0012] As shown in Figure 1, the air conditioner 10 includes an outdoor unit 11, an indoor unit 12, refrigerant piping 13, and a control device 14. The outdoor unit 11 is located outdoors, for example. The indoor unit 12 is located indoors, for example.

[0013] The air conditioner 10 includes a refrigeration cycle in which an outdoor unit 11 and an indoor unit 12 are connected by refrigerant piping 13. Refrigerant flows between the outdoor unit 11 and the indoor unit 12 through the refrigerant piping 13. The outdoor unit 11 and the indoor unit 12 are also electrically connected to each other, for example, by electrical wiring.

[0014] The outdoor unit 11 includes an outdoor heat exchanger 21, an outdoor blower fan 22, a compressor 23, a four-way valve 24, and an expansion valve 25. The indoor unit 12 includes a first indoor heat exchanger 31, a second indoor heat exchanger 32, an indoor blower fan 33, a gas-liquid separator 34, and a check valve 35. That is, the heat exchanger of the indoor unit 12 is divided into two regions (the first indoor heat exchanger 31 and the second indoor heat exchanger 32). The indoor heat exchanger of the indoor unit 12 may be divided into three or more regions.

[0015] The refrigerant piping 13 is a pipe made of a metal such as copper or aluminum. The refrigerant piping 13 includes a first pipe 41, a second pipe 42, a third pipe 43, and a fourth pipe 44. The first pipe 41 may also be called a gas pipe. The second pipe 42 may also be called a liquid pipe. The third pipe 43 may also be called a connecting pipe. The fourth pipe 44 may also be called a bypass pipe.

[0016] The first piping 41 connects the outdoor heat exchanger 21 and the first indoor heat exchanger 31. The compressor 23 and the four-way valve 24 are installed in the first piping 41. The second piping 42 connects the outdoor heat exchanger 21 and the second indoor heat exchanger 32. The expansion valve 25 is installed in the second piping 42.

[0017] The third pipe 43 connects the first indoor heat exchanger 31 and the second indoor heat exchanger 32. The gas-liquid separator 34 is provided on the third pipe 43. One end 44a of the fourth pipe 44 is connected to the gas-liquid separator 34. The other end 44b of the fourth pipe 44 is connected to the portion of the second pipe 42 between the second indoor heat exchanger 32 and the expansion valve 25. The check valve 35 is provided on the fourth pipe 44.

[0018] In the heating operation, the refrigerant flows from the outdoor heat exchanger 21 through the first pipe 41 toward the first indoor heat exchanger 31, from the first indoor heat exchanger 31 through the third pipe 43 toward the second indoor heat exchanger 32, and from the second indoor heat exchanger 32 through the second pipe 42 toward the outdoor heat exchanger 21. Further, the refrigerant flows from the gas-liquid separator 34 through the fourth pipe 44 into the second pipe 42. The arrows in FIG. 1 indicate the flow of the refrigerant in the heating operation.

[0019] FIG. 2 is a refrigerant system diagram schematically showing the air conditioner 10 during the cooling operation of the present embodiment. As shown in FIG. 2, in the cooling operation, the refrigerant flows from the first indoor heat exchanger 31 through the first pipe 41 toward the outdoor heat exchanger 21, from the outdoor heat exchanger 21 through the second pipe 42 toward the second indoor heat exchanger 32, and from the second indoor heat exchanger 32 through the third pipe 43 toward the first indoor heat exchanger 31. The arrows in FIG. 2 indicate the flow of the refrigerant in the cooling operation.

[0020] The outdoor heat exchanger 21 of the outdoor unit 11 performs heat absorption of the refrigerant as an evaporator or heat dissipation of the refrigerant as a condenser according to the flow direction of the refrigerant. The outdoor blower fan 22 generates an air flow passing through the outdoor heat exchanger 21 and promotes the heat exchange between the refrigerant and the air in the outdoor heat exchanger 21. In other words, the outdoor blower fan 22 generates an air flow that exchanges heat with the outdoor heat exchanger 21.

[0021] The compressor 23 has a suction port 23a and a discharge port 23b. The compressor 23 sucks the refrigerant from the suction port 23a and compresses the refrigerant. The compressor 23 discharges the gaseous-phase refrigerant in a superheated state at a temperature higher than the saturation temperature from the discharge port 23b. Thereby, the compressor 23 compresses the refrigerant in the refrigeration cycle and causes the circulation of the refrigerant. A gas-liquid separator may be provided at the suction port 23a.

[0022] The four-way valve 24 is connected to the outdoor heat exchanger 21, the suction port 23a, the discharge port 23b, and the first indoor heat exchanger 31. The four-way valve 24 switches the flow paths connected to the outdoor heat exchanger 21, the suction port 23a, the discharge port 23b, and the first indoor heat exchanger 31 during heating operation and cooling operation, and changes the direction in which the refrigerant flows.

[0023] As shown by the solid line in FIG. 1, in the heating operation, the four-way valve 24 connects the outdoor heat exchanger 21 and the suction port 23a. Further, in the heating operation, the four-way valve 24 connects the discharge port 23b and the first indoor heat exchanger 31. Thereby, the refrigerant compressed by the compressor 23 flows to the first indoor heat exchanger 31, and the refrigerant evaporated by the outdoor heat exchanger 21 flows to the suction port 23a.

[0024] As shown by the solid line in FIG. 2, in the cooling operation, the four-way valve 24 connects the outdoor heat exchanger 21 and the discharge port 23b. Further, in the cooling operation, the four-way valve 24 connects the suction port 23a and the first indoor heat exchanger 31. Thereby, the refrigerant compressed by the compressor 23 flows to the outdoor heat exchanger 21, and the refrigerant evaporated by the first indoor heat exchanger 31 flows to the suction port 23a.

[0025] The expansion valve 25 is, for example, an electromagnetic expansion valve. Note that the expansion valve 25 may be another expansion valve. The expansion valve 25 reduces the pressure of the refrigerant. Also, the expansion valve 25 can adjust the amount of refrigerant passing through by controlling the opening degree.

[0026] The first indoor heat exchanger 31 and the second indoor heat exchanger 32 of the indoor unit 12 respectively absorb heat as evaporators or release heat as condensers according to the direction of the refrigerant flow. The indoor blower fan 33 generates an air flow passing through the first indoor heat exchanger 31 and the second indoor heat exchanger 32, and promotes the heat exchange between the first indoor heat exchanger 31 and the second indoor heat exchanger 32 and the air. In other words, the indoor blower fan 33 generates an air flow that exchanges heat with the first indoor heat exchanger 31 and the second indoor heat exchanger 32.

[0027] Figure 3 is a cross-sectional view showing the indoor unit 12 of this embodiment. As shown in Figure 3, the first indoor heat exchanger 31 and the second indoor heat exchanger 32 each have a plurality of tubes 51 and a plurality of fins 52.

[0028] Each of the multiple tubes 51 of the first indoor heat exchanger 31 extends in parallel between the first pipe 41 and the third pipe 43. Each of the multiple tubes 51 of the second indoor heat exchanger 32 extends in parallel between the second pipe 42 and the third pipe 43. The refrigerant flows in parallel through the multiple tubes 51. In this way, the first indoor heat exchanger 31 and the second indoor heat exchanger 32 can suppress the increase in refrigerant pressure loss by dividing the refrigerant path into multiple paths (multiple tubes 51).

[0029] Multiple fins 52 are arranged, for example, at approximately equal intervals. Multiple tubes 51 each pass through multiple fins 52 and are thermally connected to the multiple fins 52. Airflow passes through the gaps between the multiple fins 52. As a result, the airflow exchanges heat with the refrigerant flowing through the tubes 51 through the tubes 51 and fins 52.

[0030] The first indoor heat exchanger 31 is larger than the second indoor heat exchanger 32. For example, the first indoor heat exchanger 31 has more tubes 51 and a larger total volume of the multiple tubes 51 than the second indoor heat exchanger 32. Note that the first indoor heat exchanger 31 and the second indoor heat exchanger 32 are not limited to this example.

[0031] Figure 4 is a schematic cross-sectional view showing the gas-liquid separator 34 and the third piping 43 during heating operation in this embodiment. As shown in Figure 4, the third piping 43 has a first distributor 61, a second distributor 62, and a pipe section 63.

[0032] The first distributor 61 is provided at one end of the third pipe 43. The second distributor 62 is provided at the other end of the third pipe 43. The pipe section 63 extends, for example, substantially upward from the first indoor heat exchanger 31.

[0033] The first distributor 61 connects the pipe section 63 to the multiple tubes 51 of the first indoor heat exchanger 31. The second distributor 62 connects the gas-liquid separator 34 to the multiple tubes 51 of the second indoor heat exchanger 32. In other words, the first distributor 61 and the second distributor 62 merge or branch the refrigerant.

[0034] The gas-liquid separation device 34 has a gas-liquid separator 71. The gas-liquid separation device 34 may have a gas-liquid separator different from the gas-liquid separator 71 described below, or it may have other components. The gas-liquid separator 71 in this embodiment is formed in a substantially L-shape and has a bent portion 72, a first pipe portion 73, a second pipe portion 74, and a third pipe portion 75.

[0035] The gas-liquid separator 71 is bent at the bend 72. The first pipe section 73 extends horizontally, downward, or diagonally downward from the bend 72. The second pipe section 74 extends downward or diagonally downward from the bend 72.

[0036] In this embodiment, the first pipe section 73 and the second pipe section 74 each extend diagonally downward from the bent section 72. The angle between the first pipe section 73 and the second pipe section 74 is, for example, about 90°. Note that the first pipe section 73 and the second pipe section 74 are not limited to this example. For example, the first pipe section 73 may extend horizontally or downward from the bent section 72, or the second pipe section 74 may extend downward from the bent section 72.

[0037] The first pipe section 73 extends substantially in a straight line between two ends 73a and 73b. The first pipe section 73 may also be bent. One end 73a of the first pipe section 73 is connected to the bend 72. The other end 73b of the first pipe section 73 is connected to the pipe section 63 of the third piping 43. Thus, the first pipe section 73 connects the pipe section 63 and the bend 72. The first pipe section 73 communicates with multiple tubes 51 of the first indoor heat exchanger 31 through the pipe section 63 and the first distributor 61.

[0038] The second pipe section 74 extends substantially in a straight line between two ends 74a and 74b. The second pipe section 74 may also be curved. One end 74a of the second pipe section 74 is connected to the bend 72. The other end 74b of the second pipe section 74 is closed.

[0039] The inner diameters of the pipe section 63 of the third pipe 43, the bend 72 of the gas-liquid separator 71, the first pipe section 73, and the second pipe section 74 are approximately equal to each other and are larger than the inner diameter of the tube 51. However, the inner diameters of the pipe section 63, the bend 72, the first pipe section 73, and the second pipe section 74 are not limited to this example.

[0040] The outer diameter of the third pipe section 75 is smaller than the inner diameters of the pipe section 63, the bend 72, the first pipe section 73, and the second pipe section 74. The third pipe section 75 penetrates the end 74b of the second pipe section 74 and extends inside the second pipe section 74 and the bend 72.

[0041] One end 75a of the third pipe section 75 is located, for example, near the end 73a of the first pipe section 73 and communicates with the first pipe section 73. The other end 75b of the third pipe section 75 is connected to the second distributor 62. Thus, the third pipe section 75 communicates the first pipe section 73 with the multiple tubes 51 of the second indoor heat exchanger 32 through the second distributor 62.

[0042] As the gas-liquid separator 71 is formed as described above, it is provided with a first passage 81, a second passage 82, a third passage 83, a bend 84, a first opening 85, a second opening 86, a third opening 87, and a fourth opening 88. The fourth opening 88 is an example of an opening.

[0043] The first passage 81 is provided inside the first pipe section 73. The second passage 82 is provided around the third pipe section 75. In other words, the second passage 82 is provided between the second pipe section 74 and the third pipe section 75. For this reason, the first passage 81 and the second passage 82 in this embodiment each extend diagonally downward from the bend 72.

[0044] The third passage 83 is provided inside the third pipe section 75. The bend 84 is provided between the bend 72 and the third pipe section 75. The first passage 81 and the second passage 82 communicate with each other through the bend 84.

[0045] The first opening 85 is provided at the end 73b of the first pipe section 73. That is, the first opening 85 is provided at one end of the first passage 81. The first opening 85 connects the first passage 81 with the passage inside the pipe section 63. That is, the first opening 85 connects the first passage 81 with the outside of the gas-liquid separator 71.

[0046] The second opening 86 is provided at the lower end of the second passage 82. That is, the second opening 86 is provided at the end 74b of the second pipe section 74. Therefore, the second opening 86 is provided in the second pipe section 74 below the bent section 72.

[0047] The end 44a of the fourth pipe 44 is in communication with the second opening 86. That is, the second opening 86 connects the second passage 82 and the fourth pipe 44. In other words, the second opening 86 connects the second passage 82 and the outside of the gas-liquid separator 71. The fourth pipe 44 connects the portion of the second pipe section 74 below the bend 72 with the second pipe 42.

[0048] The third opening 87 is provided at the end 75b of the third pipe section 75. That is, the third opening 87 is provided at one end of the third passage 83. The third opening 87 connects the third passage 83 to the second distributor 62. That is, the third opening 87 connects the third passage 83 to the outside of the gas-liquid separator 71.

[0049] The fourth opening 88 is provided at the end 75a of the third pipe section 75. That is, the fourth opening 88 is provided at the other end of the third passage 83. The fourth opening 88 connects the third passage 83 and the first passage 81.

[0050] In this embodiment, the end 75a of the third pipe section 75 is provided near the end 73a of the first pipe section 73, so that the fourth opening 88 directly communicates with the first passage 81 of the first pipe section 73. The end 75a of the third pipe section 75 may be provided at another location. For example, the end 75a of the third pipe section 75 may be provided near the end 74a of the second pipe section 74. In this case as well, the fourth opening 88 communicates indirectly with the first passage 81 of the first pipe section 73.

[0051] Furthermore, in this embodiment, the fourth opening 88 faces the first passage 81 of the first pipe section 73. For example, the fourth opening 88 faces the center of the cross-section of the first passage 81. However, the fourth opening 88 may face in other directions as long as it communicates with the first passage 81.

[0052] On the other hand, in this embodiment, the fourth opening 88 does not directly communicate with the second passage 82. The fourth opening 88 communicates indirectly with the second passage 82 via the first passage 81 and the bend 84. Furthermore, the fourth opening 88 is not facing the second passage 82.

[0053] In this embodiment, the third pipe section 75 is arranged coaxially (concentrically) with, for example, the bent section 72 and the second pipe section 74. In other words, the third pipe section 75 extends along the central axis of the bent section 72 and the second pipe section 74. Therefore, the fourth opening 88 is located above the lower end 81a of the cross-section of the first passage 81 of the first pipe section 73 and the lower end 82a of the cross-section of the second passage 82 of the second pipe section 74. The third pipe section 75 may be in contact with the lower end 81a of the first passage 81 or with the lower end 82a of the second passage 82.

[0054] The check valve 35 allows the flow of refrigerant from the second passage 82 of the second pipe section 74 to the second piping 42. On the other hand, the check valve 35 blocks the flow of refrigerant from the second piping 42 to the second passage 82 of the second pipe section 74.

[0055] For example, the check valve 35 has an elastic body that biases the valve body toward the valve seat. When the load acting on the valve body from the refrigerant in the second passage 82 pulls the valve body away from the valve seat against the elastic force of the elastic body, the check valve 35 allows the flow of refrigerant from the second passage 82 to the second pipe 42. On the other hand, if the pressure in the second pipe 42 is higher than the pressure in the second passage 82, this pressure presses the valve body against the valve seat. Therefore, the check valve 35 blocks the flow of refrigerant from the second pipe 42 to the second passage 82. Note that the check valve 35 is not limited to this example.

[0056] The control device 14 shown in Figure 1 is a computer having, for example, a control device such as a CPU (Central Processing Unit) or a microcontroller, and a storage device such as ROM (Read Only Memory), RAM (Random Access Memory), and flash memory. Note that the control device 14 is not limited to this example.

[0057] The control device 14 controls the outdoor fan 22, compressor 23, four-way valve 24, and expansion valve 25 of the outdoor unit 11, and the indoor fan 33 of the indoor unit 12. By controlling the outdoor unit 11 and the indoor unit 12, the air conditioner 10 performs cooling, heating, dehumidifying, defrosting, and other operations. The control device 14 may receive signals from, for example, a remote controller, or from an information terminal such as a smartphone via a communication device.

[0058] The heating and cooling operations of the air conditioner 10 in this embodiment will be described below. As mentioned above, the air conditioner 10 can perform other operations such as dehumidification and defrosting, in addition to heating and cooling operations. Furthermore, the heating and cooling operations of the air conditioner 10 are not limited to the examples described below.

[0059] When heating operation begins, the control device 14 controls the four-way valve 24 to switch the direction of refrigerant flow to the heating direction. As a result, as shown in Figure 1, the gaseous refrigerant discharged from the discharge port 23b of the compressor 23 is supplied to the first indoor heat exchanger 31 through the first piping 41.

[0060] In the first indoor heat exchanger 31, the refrigerant condenses by exchanging heat with the airflow generated by the indoor blower fan 33. As a result, the first indoor heat exchanger 31 heats the airflow, and the indoor unit 12 supplies warm air to the room.

[0061] During heat exchange in the first indoor heat exchanger 31, the refrigerant flows from a heated gas through a saturated gas to a gas-liquid two-phase flow. During heat exchange in the first indoor heat exchanger 31, the proportion of the liquid phase in the gas-liquid two-phase refrigerant increases. The gas-liquid two-phase refrigerant flows out of the first indoor heat exchanger 31 to the third piping 43.

[0062] As schematically shown by arrows in Figure 4, the refrigerant flows from multiple tubes 51 of the first indoor heat exchanger 31 into the first distributor 61. The refrigerants merge in the first distributor 61 and rise up the pipe section 63 of the third piping 43. The refrigerant flows from the first opening 85 into the first passage 81 of the first pipe section 73. The refrigerant rises diagonally up the first passage 81 toward the bend 72.

[0063] Liquid-phase refrigerant has a higher density than gaseous-phase refrigerant. Therefore, in a gas-liquid two-phase refrigerant system, the liquid-phase refrigerant tends to be distributed lower than the gaseous-phase refrigerant due to gravity. Furthermore, as the gas-liquid two-phase refrigerant rises diagonally through the first passage 81, the liquid-phase refrigerant distributed downwards is susceptible to frictional resistance from the inner surface of the first pipe section 73. For example, due to this distribution and resistance, the liquid-phase refrigerant dispersed within the gas-liquid two-phase refrigerant system condenses at the lower end 81a of the cross-section of the first passage 81.

[0064] The liquid-phase refrigerant condensed in the first passage 81 is carried toward the end 73a of the first pipe section 73 by the flow of the gas-liquid two-phase refrigerant. At the end 73a, the liquid-phase refrigerant passes over the bend 72 and flows into the second passage 82 of the second pipe section 74. That is, the liquid-phase refrigerant flows into the second passage 82 through the bend 84 which opens below the fourth opening 88.

[0065] The second passage 82 of the second pipe section 74 extends diagonally downward from the bend 72. Therefore, the liquid phase refrigerant flows diagonally downward through the second passage 82 due to gravity. The liquid phase refrigerant flows from the second passage 82 through the second opening 86 into the fourth pipe 44.

[0066] For example, when liquid-phase refrigerant accumulates in the second passage 82 and the load acting on the valve body of the check valve 35 from the refrigerant exceeds the elastic force of the elastic body of the check valve 35, the check valve 35 opens. As a result, the liquid-phase refrigerant in the second passage 82 is discharged through the fourth pipe 44 to the second pipe 42.

[0067] As described above, the liquid refrigerant is separated from the gas-liquid two-phase refrigerant. As a result, the proportion of the gas phase (degree of dryness) in the gas-liquid two-phase refrigerant flowing through the first passage 81 increases. The gas-liquid two-phase refrigerant with a high degree of dryness flows from the fourth opening 88 into the third passage 83 of the third pipe section 75.

[0068] The refrigerant flows out through the third passage 83 and the third opening 87 and is supplied to the second distributor 62. From the second distributor 62, the refrigerant is distributed to multiple tubes 51 of the second indoor heat exchanger 32.

[0069] In the second indoor heat exchanger 32, the refrigerant with a high degree of dryness condenses by exchanging heat with the airflow generated by the indoor blower fan 33. As a result, the second indoor heat exchanger 32 heats the airflow, and the indoor unit 12 supplies warm air to the room. Because the refrigerant supplied to the second indoor heat exchanger 32 has a high degree of dryness, the amount of condensation in the second indoor heat exchanger 32 is large.

[0070] Due to heat exchange in the second indoor heat exchanger 32, the proportion of the liquid phase in the gas-liquid two-phase refrigerant increases. In the second indoor heat exchanger 32, the refrigerant may complete condensation and enter a supercooled state.

[0071] As described above, the gas-liquid separator 71 directs the liquid phase refrigerant supplied from the first opening 85 to the first passage 81 to the second passage 82 and the gas phase refrigerant to the third passage 83. In this way, the gas-liquid separator 71 supplies the gas phase refrigerant to the second indoor heat exchanger 32 and the liquid phase refrigerant to the second piping 42 from the refrigerant flowing from the first indoor heat exchanger 31 to the second indoor heat exchanger 32. The refrigerant supplied to the second indoor heat exchanger 32 through the third passage 83 may be a gas-liquid two-phase system including the liquid phase refrigerant, as described above.

[0072] The condensed refrigerant flows out from the second indoor heat exchanger 32 into the second piping 42. The refrigerant that flows out from the second indoor heat exchanger 32 and the refrigerant that flows out from the fourth piping 44 merge in the second piping 42.

[0073] The refrigerant is depressurized by the expansion valve 25 shown in Figure 1 and supplied to the outdoor heat exchanger 21. In the outdoor heat exchanger 21, the refrigerant evaporates by exchanging heat with the airflow generated by the outdoor blower fan 22.

[0074] During heat exchange in the outdoor heat exchanger 21, the refrigerant flows from a subcooled liquid to a saturated liquid, and then into a gas-liquid two-phase flow. During heat exchange in the outdoor heat exchanger 21, the proportion of the gas phase in the gas-liquid two-phase refrigerant increases. In the outdoor heat exchanger 21, the refrigerant may complete evaporation and become superheated.

[0075] A gas-liquid two-phase or gas-phase refrigerant is supplied from the outdoor heat exchanger 21 to the suction port 23a of the compressor 23. The compressor 23 pressurizes the refrigerant and supplies it again from the discharge port 23b to the first indoor heat exchanger 31.

[0076] In the heating operation described above, the gas-liquid separator 71 separates the liquid phase refrigerant from the condensed refrigerant in the first indoor heat exchanger 31. As a result, the proportion of gas phase (dryness) of the refrigerant supplied from the gas-liquid separator 71 to the second indoor heat exchanger 32 is greater than that of the refrigerant supplied from the first indoor heat exchanger 31 to the gas-liquid separator 71.

[0077] The gas-liquid separator 71 can suppress the complete condensation of the refrigerant in the second indoor heat exchanger 32, or delay the completion of condensation, by increasing the proportion of the gas phase in the refrigerant. Therefore, the gas-liquid separator 71 can suppress a decrease in the contact area between the tubes 51 of the second indoor heat exchanger 32 and the gas phase refrigerant, and consequently suppress an increase in saturation pressure and a decrease in energy consumption efficiency (COP). Thus, the gas-liquid separator 71 can suppress a decrease in the heating performance of the air conditioner 10.

[0078] On the other hand, when cooling operation is started, the control device 14 controls the four-way valve 24 to switch the direction of refrigerant flow to the direction of cooling operation. As a result, as shown in Figure 2, the gaseous refrigerant discharged from the discharge port 23b of the compressor 23 is supplied to the outdoor heat exchanger 21 through the first piping 41.

[0079] In the outdoor heat exchanger 21, the refrigerant condenses by exchanging heat with the airflow generated by the outdoor blower fan 22. The refrigerant is depressurized by the expansion valve 25 and supplied to the second indoor heat exchanger 32 through the second piping 42. The check valve 35 blocks the fourth piping 44, preventing the refrigerant in the second piping 42 from flowing into the second passage 82 of the second pipe section 74.

[0080] In the second indoor heat exchanger 32, the refrigerant evaporates by exchanging heat with the airflow generated by the indoor blower fan 33. As a result, the second indoor heat exchanger 32 cools the airflow, and the indoor unit 12 supplies cool air to the room. During the heat exchange in the second indoor heat exchanger 32, the proportion of the gas phase in the gas-liquid two-phase refrigerant increases. The gas-liquid two-phase refrigerant flows out of the second indoor heat exchanger 32 into the third piping 43.

[0081] Figure 5 is a schematic cross-sectional view showing the gas-liquid separator 34 and the third piping 43 during cooling operation in this embodiment. As schematically shown by the arrows in Figure 5, the refrigerant flows from multiple tubes 51 of the second indoor heat exchanger 32 into the second distributor 62. The refrigerants merge in the second distributor 62 and are supplied from the third opening 87 to the third passage 83 of the third pipe section 75. The refrigerant rises diagonally up the third passage 83.

[0082] The refrigerant flows out from the fourth opening 88 of the third pipe section 75 into the first passage 81 of the first pipe section 73. Because the fourth opening 88 faces the first passage 81 of the first pipe section 73, the refrigerant does not pass through the second passage 82, nor is it distributed to the second passage 82, but flows directly into the first passage 81. Furthermore, the fourth opening 88 faces the direction in which the first passage 81 of the first pipe section 73 extends. Therefore, the refrigerant flowing out from the fourth opening 88 flows smoothly through the first passage 81.

[0083] The diameter of the first passage 81 is larger than the diameter of the fourth opening 88. Therefore, the refrigerant is ejected from the fourth opening 88 in the direction that the fourth opening 88 faces. Because the first passage 81 and the fourth opening 88 are arranged concentrically (coaxially), the refrigerant is ejected from the fourth opening 88 towards the center of the cross-section of the first passage 81. Therefore, the refrigerant is less likely to flow into the second passage 82.

[0084] The refrigerant flows out through the first passage 81 and out through the first opening 85. The refrigerant is supplied to the first distributor 61 through the pipe section 63. From the first distributor 61, the refrigerant is distributed to multiple tubes 51 of the first indoor heat exchanger 31.

[0085] In the first indoor heat exchanger 31, the refrigerant evaporates by exchanging heat with the airflow generated by the indoor blower fan 33. As a result, the first indoor heat exchanger 31 cools the airflow, and the indoor unit 12 supplies cool air to the room.

[0086] Due to heat exchange in the first indoor heat exchanger 31, the proportion of the gas phase in the gas-liquid two-phase refrigerant increases. In the first indoor heat exchanger 31, the refrigerant may complete evaporation and become superheated.

[0087] The evaporated refrigerant flows out from the first indoor heat exchanger 31 into the first piping 41. The refrigerant is supplied through the first piping 41 to the suction port 23a of the compressor 23. The compressor 23 pressurizes the refrigerant and supplies it again to the outdoor heat exchanger 21 from the discharge port 23b.

[0088] In the cooling operation described above, the refrigerant that has passed through the second indoor heat exchanger 32 does not flow into the second passage 82, but flows directly into the first passage 81. In other words, the gas-liquid separator 71 can supply the entire amount of refrigerant that has passed through the second indoor heat exchanger 32 to the first indoor heat exchanger 31. As a result, the gas-liquid separator 71 can suppress a decrease in the cooling performance of the air conditioner 10.

[0089] The air conditioner 10 according to the embodiment described above comprises a first indoor heat exchanger 31, a second indoor heat exchanger 32, an outdoor heat exchanger 21, a first pipe 41, a second pipe 42, a third pipe 43, and a gas-liquid separator 71. The first pipe 41 connects the first indoor heat exchanger 31 and the outdoor heat exchanger 21. The second pipe 42 connects the second indoor heat exchanger 32 and the outdoor heat exchanger 21. The third pipe 43 connects the first indoor heat exchanger 31 and the second indoor heat exchanger 32. The refrigerant flows through the first pipe 41, the second pipe 42, and the third pipe 43. The gas-liquid separator 71 is provided in the third pipe 43. The gas-liquid separator 71 supplies the gaseous phase refrigerant from the first indoor heat exchanger 31 to the second indoor heat exchanger 32, and supplies the liquid phase refrigerant to the second piping 42.

[0090] During heating operation, when refrigerant flows from the compressor 23 to the first indoor heat exchanger 31, for example, the gaseous refrigerant condenses into a gas-liquid two-phase system in the first indoor heat exchanger 31. The gas-liquid two-phase refrigerant flows from the first indoor heat exchanger 31 through the third piping 43 toward the second indoor heat exchanger 32. A gas-liquid separator 71 installed in the third piping 43 supplies the gaseous refrigerant of the gas-liquid two-phase system to the second indoor heat exchanger 32. On the other hand, the gas-liquid separator 71 discharges the liquid refrigerant of the gas-liquid two-phase system toward the second piping 42. As a result, the proportion (dryness) of the gaseous refrigerant among the refrigerant supplied to the second indoor heat exchanger 32 increases, and the contact area between the inner surface of the second indoor heat exchanger 32 and the gaseous refrigerant increases. In other words, the air conditioner 10 can suppress the increase in pressure loss and the decrease in condensation heat transfer coefficient in the second indoor heat exchanger 32, thereby improving heating performance. Improving heating performance can improve the annual energy efficiency (AFP) more than improving cooling performance. Therefore, the air conditioner 10 can improve energy saving performance.

[0091] The gas-liquid separator 71 has a bent section 72, a first pipe section 73, a second pipe section 74, and a third pipe section 75. The first pipe section 73 extends horizontally, downward, or diagonally downward from the bent section 72 and communicates with the first indoor heat exchanger 31. The second pipe section 74 extends downward or diagonally downward from the bent section 72 and communicates with the second piping 42. The third pipe section 75 extends inside the second pipe section 74 and communicates the first pipe section 73 and the second indoor heat exchanger 32.

[0092] When the refrigerant flows from the first indoor heat exchanger 31 to the second indoor heat exchanger 32, the gas-liquid two-phase refrigerant flows through the first pipe section 73 toward the bend 72. At this time, the liquid phase of the gas-liquid two-phase refrigerant accumulates at the lower end of the cross-section of the first pipe section 73, for example, due to gravity. Since the second pipe section 74 extends downward or diagonally downward from the bend 72, the liquid phase refrigerant accumulated at the lower end of the cross-section of the first pipe section 73 flows down the second pipe section 74 due to gravity. In this way, the gas-liquid separator 71 can cause the liquid phase of the gas-liquid two-phase refrigerant to flow to the second pipe section 74 and discharge it from the second pipe section 74 to the second piping 42. On the other hand, the gas phase of the gas-liquid two-phase refrigerant is distributed to locations other than where the liquid phase refrigerant accumulates. Therefore, the gaseous refrigerant can flow from the first pipe section 73 to the third pipe section 75. In other words, the gas-liquid separator 71 can flow the gaseous refrigerant of the two-phase gas-liquid refrigerant to the third pipe section 75 and supply it from the third pipe section 75 to the second indoor heat exchanger 32.

[0093] The air conditioner 10 further includes a fourth pipe 44 and a check valve 35. The fourth pipe 44 connects the portion of the second pipe section 74 below the bend 72 to the second pipe 42. The check valve 35 is provided on the fourth pipe 44 and allows the flow of refrigerant from the second pipe section 74 to the second pipe 42, while blocking the flow of refrigerant from the second pipe 42 to the second pipe section 74. Therefore, during heating operation, the gas-liquid separator 71 can discharge the liquid phase refrigerant to the second pipe 42 through the fourth pipe 44. On the other hand, during cooling operation, when refrigerant flows from the compressor 23 to the outdoor heat exchanger 21, in the second indoor heat exchanger 32, for example, the refrigerant evaporates and becomes a gas-liquid two-phase system. The two-phase gas-liquid refrigerant is supplied from the second indoor heat exchanger 32 to the first indoor heat exchanger 31 through the gas-liquid separator 71 of the third piping 43. The check valve 35 prevents the refrigerant from the second piping 42 from flowing to the first indoor heat exchanger 31 through the fourth piping 44. Therefore, the air conditioner 10 can prevent the refrigerant from bypassing the second indoor heat exchanger 32 and being supplied to the first indoor heat exchanger 31 during cooling operation, thereby suppressing a decrease in cooling performance.

[0094] A fourth opening 88 is provided in the third pipe section 75, which faces the first pipe section 73 and communicates with the first pipe section 73. Therefore, during heating operation, at least a portion of the refrigerant in the first pipe section 73 flows toward the fourth opening 88 of the third pipe section 75. In other words, the fourth opening 88 can receive and collect the refrigerant flowing through the first pipe section 73. Consequently, the gas-liquid separator 71 can efficiently supply gaseous refrigerant to the second indoor heat exchanger 32. On the other hand, during cooling operation, the refrigerant flows from the second indoor heat exchanger 32 through the third pipe section 75 toward the first indoor heat exchanger 31. Because the fourth opening 88 faces the first pipe section 73, the refrigerant flows directly from the fourth opening 88 toward the first pipe section 73 and is less likely to flow into the second pipe section 74. Therefore, the air conditioner 10 can directly supply refrigerant from the second indoor heat exchanger 32 to the first indoor heat exchanger 31 during cooling operation, thereby suppressing a decrease in cooling performance.

[0095] A fourth opening 88 is provided in the third pipe section 75, which communicates with the first pipe section 73. The fourth opening 88 is located above the lower end of the cross-section of the first pipe section 73 and the lower end of the cross-section of the second pipe section 74. As a result, the air conditioner 10 can prevent liquid-phase refrigerant accumulated at the lower end of the cross-section of the first pipe section 73 and liquid-phase refrigerant flowing down the lower end of the cross-section of the second pipe section 74 from flowing into the opening of the third pipe section 75. Consequently, the air conditioner 10 can improve the dryness of the refrigerant supplied to the second indoor heat exchanger 32.

[0096] The first pipe section 73 extends diagonally downward from the bend 72. Therefore, when the gas-liquid two-phase refrigerant flows through the first pipe section 73 toward the bend 72, it moves upward through the first pipe section 73. As a result, the liquid phase of the gas-liquid two-phase refrigerant tends to accumulate at the lower end of the cross-section of the first pipe section 73 due to gravity and resistance. Consequently, the gas-liquid separator 71 can efficiently transfer the liquid phase of the gas-liquid two-phase refrigerant to the second pipe section 74.

[0097] The gas-liquid separation device 34 includes a gas-liquid separator 71. The gas-liquid separator 71 is provided with a first passage 81, a second passage 82, a third passage 83, a first opening 85, a second opening 86, and a third opening 87. The second passage 82 communicates with the first passage 81. The third passage 83 communicates with the first passage 81. The first opening 85 communicates the first passage 81 with the outside. The second opening 86 communicates the second passage 82 with the outside. The third opening 87 communicates the third passage 83 with the outside. The gas-liquid separator 71 flows the liquid phase refrigerant supplied from the first opening 85 to the first passage 81 to the second passage 82, and the gas phase refrigerant to the third passage 83. The gas-liquid separator 71 allows the refrigerant supplied from the third opening 87 to the third passage 83 to flow directly into the first passage 81. In other words, the gas-liquid separator 34 can separate the refrigerant supplied to the first opening 85 into liquid phase and gas phase refrigerant, while also allowing the refrigerant supplied to the third opening 87 to pass through directly. Therefore, the gas-liquid separator 34 can prevent refrigerant from accumulating inside the gas-liquid separator 71.

[0098] When the gas-liquid separator 34 is placed between the two indoor heat exchangers of the air conditioner 10 (the first indoor heat exchanger 31 and the second indoor heat exchanger 32), it can separate the two-phase gas-liquid refrigerant supplied from the upstream first indoor heat exchanger 31 to the first passage 81 into a liquid-phase refrigerant discharged from the second opening 86 through the second passage 82, and a gas-phase refrigerant supplied from the third opening 87 through the third passage 83 to the downstream second indoor heat exchanger 32. By separating the refrigerant into liquid-phase and gas-phase during heating operation, the gas-liquid separator 34 increases the dryness of the refrigerant supplied to the downstream second indoor heat exchanger 32, and increases the contact area between the inner surface of the downstream second indoor heat exchanger 32 and the gas-phase refrigerant. In other words, the air conditioner 10 can suppress the increase in pressure loss and decrease in the condensation heat transfer coefficient in the downstream second indoor heat exchanger 32, thereby improving heating performance and energy saving performance.

[0099] The gas-liquid separator 71 has a bent section 72, a first pipe section 73, a second pipe section 74, and a third pipe section 75. The first pipe section 73 extends horizontally, downward, or diagonally downward from the bent section 72. The second pipe section 74 extends downward or diagonally downward from the bent section 72. The third pipe section 75 extends inside the second pipe section 74. The first passage 81 is provided inside the first pipe section 73. The second passage 82 is provided between the second pipe section 74 and the third pipe section 75. The third passage 83 is provided inside the third pipe section 75. The second opening 86 is provided in the second pipe section 74 below the bent section 72.

[0100] When refrigerant is supplied from the first opening 85 to the first passage 81, the refrigerant flows through the first passage 81 of the first pipe section 73 toward the bend 72. At this time, the liquid phase of the refrigerant accumulates at the lower end 81a of the cross-section of the first passage 81, for example, due to gravity. Because the second pipe section 74 extends downward or diagonally downward from the bend 72, the liquid phase of the refrigerant accumulated at the lower end 81a of the cross-section of the first passage 81 flows down the second passage 82 of the second pipe section 74 due to gravity. In this way, the gas-liquid separator 71 can drain the liquid phase of the gas-liquid two-phase refrigerant to the second passage 82 and discharge it from the second passage 82 to the second opening 86. On the other hand, the gas phase of the gas-liquid two-phase refrigerant is distributed to locations other than where the liquid phase refrigerant accumulates. Therefore, the gaseous refrigerant can flow from the first passage 81 into the third passage 83 of the third pipe section 75. In other words, the gas-liquid separator 71 can drain the gaseous refrigerant of the two-phase gas-liquid refrigerant into the third passage 83 and discharge it from the third passage 83 to the second opening 86.

[0101] A fourth opening 88 is provided in the third pipe section 75, connecting the first passage 81 and the third passage 83. The fourth opening 88 faces the first passage 81. Therefore, at least a portion of the refrigerant supplied from the first opening 85 to the first passage 81 flows toward the fourth opening 88. In other words, the fourth opening 88 can receive and collect the refrigerant flowing through the first passage 81. Thus, the gas-liquid separator 34 can efficiently separate the gaseous phase refrigerant from the liquid phase refrigerant. On the other hand, the refrigerant supplied from the third opening 87 to the third passage 83 flows through the third passage 83 to the first passage 81. Because the fourth opening 88 faces the first passage 81, the refrigerant flows directly from the fourth opening 88 to the first passage 81 and is less likely to flow into the second passage 82. Therefore, the gas-liquid separator 34 can allow the refrigerant supplied to the third opening 87 to pass through as is.

[0102] A fourth opening 88 is provided in the third pipe section 75, connecting the first passage 81 and the third passage 83. The fourth opening 88 is located above the lower end 81a of the cross-section of the first passage 81 and the lower end 82a of the cross-section of the second passage 82. Therefore, the gas-liquid separator 34 can prevent the liquid phase refrigerant accumulated at the lower end 81a of the cross-section of the first passage 81 and the liquid phase refrigerant flowing down the lower end 82a of the cross-section of the second passage 82 from flowing into the fourth opening 88.

[0103] The first pipe section 73 extends diagonally downward from the bend 72. Therefore, when the refrigerant supplied from the first opening 85 to the first passage 81 flows through the first passage 81 of the first pipe section 73 toward the bend 72, it moves upward through the first passage 81. As a result, the liquid phase of the refrigerant tends to accumulate at the lower end 81a of the cross-section of the first passage 81 due to gravity and resistance. Consequently, the gas-liquid separator 34 can efficiently flow the liquid phase of the refrigerant to the second passage 82.

[0104] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0105] 10...Air conditioner, 21...Outdoor heat exchanger, 31...First indoor heat exchanger, 32...Second indoor heat exchanger, 34...Gas-liquid separator, 35...Check valve, 41...First piping, 42...Second piping, 43...Third piping, 44...Fourth piping, 71...Gas-liquid separator, 72...Bend, 73...First pipe section, 74...Second pipe section, 75...Third pipe section, 81...First passage, 81a...Lower end, 82...Second passage, 82a...Lower end, 83...Third passage, 85...First opening, 86...Second opening, 87...Third opening, 88...Fourth opening.

Claims

1. The first indoor heat exchanger, The second indoor heat exchanger, Outdoor heat exchanger, A first piping connects the first indoor heat exchanger and the outdoor heat exchanger, through which the refrigerant flows, The second indoor heat exchanger and the outdoor heat exchanger are connected by a second pipe through which the refrigerant flows, A third pipe connects the first indoor heat exchanger and the second indoor heat exchanger, through which the refrigerant flows, A gas-liquid separator is provided in the third piping, which, during heating operation, supplies the gaseous phase of the refrigerant flowing from the first indoor heat exchanger toward the second indoor heat exchanger to the second indoor heat exchanger, supplies the liquid phase of the refrigerant to the second piping, and during cooling operation, directly supplies the gas-liquid two-phase refrigerant flowing from the second indoor heat exchanger toward the first indoor heat exchanger to the first indoor heat exchanger. Equipped with, The gas-liquid separator has a bent portion, a first pipe portion extending horizontally, downward, or diagonally downward from the bent portion and communicating with the first indoor heat exchanger, a second pipe portion extending downward or diagonally downward from the bent portion and communicating with the second piping, and a third pipe portion extending inside the second pipe portion and communicating the first pipe portion and the second indoor heat exchanger. Air conditioner.

2. A fourth pipe connecting the portion of the second pipe section below the bend and the second pipe, A check valve is provided in the fourth piping, which allows the flow of the refrigerant from the second pipe section to the second piping and blocks the flow of the refrigerant from the second piping to the second pipe section. The air conditioner according to claim 1, further comprising the following:

3. The third pipe section is provided with an opening that faces the first pipe section and communicates with the first pipe section. An air conditioner according to claim 1 or claim 2.

4. The third pipe section is provided with an opening that communicates with the first pipe section. The opening is located above the lower end of the cross-section of the first pipe section and above the lower end of the cross-section of the second pipe section. An air conditioner according to claim 1 or claim 2.

5. The first tubular section extends diagonally downward from the bent section, An air conditioner according to claim 1 or claim 2.

6. A gas-liquid separator provided with a first passage, a second passage communicating with the first passage, a third passage communicating with the first passage, a first opening communicating the first passage with the outside, a second opening communicating the second passage with the outside, and a third opening communicating the third passage with the outside. Equipped with, The gas-liquid separator, in heating operation, flows the liquid phase of the refrigerant supplied from the first opening to the first passage to the second passage, and flows the gaseous phase of the refrigerant to the third passage. The gas-liquid separator, in cooling operation, directly flows the gas-liquid two-phase refrigerant supplied from the third opening to the third passage into the first passage. Gas-liquid separation equipment.

7. The gas-liquid separator has a bent portion, a first pipe portion extending horizontally, downward, or diagonally downward from the bent portion, a second pipe portion extending downward or diagonally downward from the bent portion, and a third pipe portion extending inside the second pipe portion. The first passage is provided inside the first pipe section, The second passage is provided between the second pipe section and the third pipe section. The third passage is provided inside the third pipe section, The second opening is provided in the second pipe section below the bent portion, The gas-liquid separation apparatus according to claim 6.

8. A fourth opening is provided in the third pipe section, which connects the first passage and the third passage. The fourth opening faces the first passage, The gas-liquid separation apparatus according to claim 7.

9. A fourth opening is provided in the third pipe section, which connects the first passage and the third passage. The fourth opening is located above the lower end of the cross-section of the first passage and the lower end of the cross-section of the second passage. The gas-liquid separation apparatus according to claim 7.

10. The first tubular section extends diagonally downward from the bent section, The gas-liquid separation apparatus according to claim 7.

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