JP2020020576A - Refrigeration cycle device and air conditioner including the same - Google Patents

Abstract

To provide a refrigeration cycle device and an air conditioner capable of enhancing heat transfer performance.SOLUTION: A compressor 5 and a heat exchanger group 10 are accommodated in an outdoor unit 4 of an outdoor device 3 of an air conditioner 1. The heat exchanger group 10 includes a first heat exchanger 11, a second heat exchanger 12 and a third heat exchanger 13. In a cooling operation, a refrigerant R discharged from the compressor 5 is branched into two refrigerants. One refrigerant R is sent to the second heat exchanger 12, and the other refrigerant R is sent to the third heat exchanger 13. In the second heat exchanger 12, heat exchange is performed so that the refrigerant R is converted to a two-phase refrigerant. In the third heat exchanger 13, heat exchange is performed so that the refrigerant R is converted to a two-phase refrigerant. The refrigerant R caused to flow in the second heat exchanger 12 and the refrigerant R caused to flow in the third heat exchanger 13 are merged with each other and then sent to the first heat exchanger 11. In the first heat exchanger 11, heat exchange is performed so that the two-phase refrigerant R is converted to a liquid refrigerant and then caused to flow in the first heat exchanger 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration cycle apparatus and an air conditioner including the same, and more particularly, to a refrigeration cycle apparatus including an outdoor unit including a plurality of heat exchangers, and an air conditioner including such a refrigeration cycle apparatus. Things.

  BACKGROUND ART An air conditioner is widely used for cooling or heating a room or the like. The air conditioner includes an indoor unit that houses an indoor heat exchanger, and an outdoor unit that houses an outdoor heat exchanger, a compressor, and the like.

  First, in the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor flows into the outdoor heat exchanger of the outdoor unit, exchanges heat with the outside air, and condenses to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is converted into a two-phase refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by the expansion device. The refrigerant in the two-phase state flows into the indoor heat exchanger of the indoor unit, performs heat exchange with indoor air, evaporates the liquid refrigerant, and turns into a low-pressure gas refrigerant. The room is cooled by this heat exchange. The low-pressure gas refrigerant is sent to the compressor and compressed again.

  In the heating operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor flows into the indoor heat exchanger of the indoor unit, exchanges heat with indoor air, and condenses to become a high-pressure liquid refrigerant. By this heat exchange, the room is heated. The high-pressure liquid refrigerant is converted into a two-phase refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by the expansion device. The refrigerant in the two-phase state flows into the outdoor heat exchanger of the outdoor unit, performs heat exchange with the outside air, evaporates the liquid refrigerant, and turns into a low-pressure gas refrigerant. The low-pressure gas refrigerant is sent to the compressor and compressed again.

  BACKGROUND ART In an air conditioner, there is an outdoor heat exchanger including a plurality of heat exchangers as an outdoor heat exchanger in order to improve heat exchange performance according to a situation. For example, in an air conditioner described in Patent Document 1, two heat exchangers, a first heat exchanger and a second heat exchanger, are arranged in an outdoor unit.

  The first heat exchanger includes a plurality of first unit flow paths. The second heat exchanger is provided with a plurality of second unit flow paths. The number of the first unit channels and the number of the second unit channels are set to the same number (number A). The length of the first unit channel and the length of the second unit channel are set to the same length (length L).

  During the heating operation, the refrigerant flows to the first heat exchanger or the second heat exchanger connected in parallel. At this time, the number of flow paths through which the refrigerant flows is twice the number A (2 × A), and the length of the flow path through which the refrigerant flows is length L. In the heating operation, it is said that an increase in the number of flow paths reduces the flow velocity of the refrigerant, thereby suppressing pressure loss.

  On the other hand, in the cooling operation, the refrigerant flows through the first heat exchanger and the second heat exchanger connected in series. At this time, the number of flow paths through which the refrigerant flows is the number A, and the length of the flow path through which the refrigerant flows is twice as long as the length L (2 × L). In the cooling operation, compared to the heating operation, the number of flow paths is reduced, so that the flow velocity of the refrigerant is increased, and heat transfer can be promoted.

JP-A-2005-117936

  The conventional air conditioner has the following problems. When the air conditioner performs the cooling operation, the outdoor heat exchanger functions as a condenser. At this time, the high-temperature and high-pressure gas refrigerant discharged from the compressor first flows into the first heat exchanger. In the first heat exchanger, heat exchange is performed between the outside air and the gas refrigerant, the gas refrigerant starts to condense, gradually liquefies, and becomes a two-phase refrigerant of the liquid refrigerant and the gas refrigerant.

  The refrigerant in the two-phase state flows from the first heat exchanger to the second heat exchanger. In the second heat exchanger, heat exchange is performed between the outside air and the refrigerant in the two-phase state, and the remaining gas refrigerant is further liquefied, and finally becomes a single-phase liquid refrigerant. That is, in the second heat exchanger, a single-phase liquid refrigerant (subcool) flows from the middle of the second unit flow path.

  As described above, when the outdoor heat exchanger functions as a condenser, it is necessary to increase the flow rate of the liquid refrigerant in order to increase the heat transfer performance. However, the number of the first unit channels of the first heat exchanger and the number of the second unit channels of the second heat exchanger are set to the same number (number A). For this reason, it is difficult to increase the flow rate of the single-phase liquid refrigerant from the middle of the second unit flow path of the second heat exchanger, and the heat transfer performance in the portion flowing through the second unit flow path as the liquid refrigerant Was difficult to raise.

  The present invention has been made in order to solve such problems, and one object is to provide a refrigeration cycle device capable of improving heat transfer performance, and another object is to provide such a device. An object of the present invention is to provide an air conditioner equipped with a simple refrigeration cycle device.

  The refrigeration cycle device according to the present invention is an refrigeration cycle device including an outdoor unit including a heat exchanger group including a plurality of heat exchangers and a refrigerant circuit connecting the heat exchanger group with piping. In the first operation in which the group of heat exchangers is operated as a condenser, the refrigerant flowing in the pipe flows through the first number of heat exchangers connected in parallel, and then flows through the second number of heat exchangers. . In the case of the second operation in which the heat exchanger group operates as an evaporator, the refrigerant flowing in the pipe flows through the third number of heat exchangers connected in parallel. The third number is the sum of the first number and the second number. The second number is less than the first number.

  An air conditioner according to the present invention is an air conditioner including the refrigeration cycle device.

  According to the refrigeration cycle apparatus of the present invention, in the first operation in which the group of heat exchangers is operated as a condenser, the refrigerant flowing in the pipe has flowed through the first number of heat exchangers connected in parallel. Later, it flows through a second number of heat exchangers less than the first number. Accordingly, the flow velocity of the refrigerant that becomes the liquid refrigerant and flows through the third heat exchanger increases, and the heat transfer performance when the heat exchanger group operates as a condenser can be improved.

  According to the refrigeration cycle apparatus of the present invention, the provision of the outdoor unit improves heat transfer performance when the heat exchanger group is operated as a condenser.

FIG. 3 is a diagram illustrating a configuration including a refrigerant circuit of the air-conditioning apparatus including the outdoor unit according to Embodiment 1. FIG. 3 is a diagram illustrating a flow of a refrigerant for describing a first example of a cooling operation in the first embodiment. It is a figure which shows the outdoor unit of the air conditioner which concerns on a comparative example, and the flow of the refrigerant | coolant in the outdoor unit at the time of cooling operation. FIG. 3 is a diagram illustrating a flow of a refrigerant for describing a first example of a heating operation in the first embodiment. FIG. 4 is a diagram illustrating a flow of a refrigerant for describing one of a second example of a cooling operation in the first embodiment. FIG. 9 is a diagram illustrating a flow of a refrigerant for describing another example of the second example of the cooling operation in the first embodiment. FIG. 5 is a diagram illustrating a flow of a refrigerant for describing a second example of the heating operation in the first embodiment. FIG. 5 is a diagram illustrating a flow of a refrigerant for describing a third example of the heating operation in the first embodiment. It is a figure which shows the structure containing the refrigerant circuit of the air conditioner provided with the outdoor unit which concerns on Embodiment 2. FIG. 13 is an enlarged perspective view showing an example of a three-branch distributor used for the outdoor unit according to Embodiment 2. FIG. 14 is a diagram illustrating a flow of a refrigerant for describing one of fourth examples of a heating operation in the second embodiment. FIG. 13 is a diagram illustrating a flow of a refrigerant for describing another example of the fourth example of the heating operation in the second embodiment.

Embodiment 1 FIG.
(Constitution)
First, the overall configuration of an air conditioner as a refrigeration cycle device will be described. As shown in FIG. 1, the air conditioner 1 includes an indoor unit 2 and an outdoor unit 3 including an outdoor unit 4. The indoor unit 2 contains an indoor heat exchanger (not shown). Here, for convenience of explanation, one outdoor unit 4 is typically given as an example.

  The air conditioner 1 includes a compressor 5, a first four-way valve 31, a second four-way valve 32, a third four-way valve 33, a first heat exchanger 11, an outdoor heat exchanger, a second heat exchanger 12, and a third heat exchanger. A heat exchanger 13 (heat exchanger group 10), a first expansion valve 51, a second expansion valve 52, and an indoor heat exchanger (not shown) are provided. The compressor 5, the first four-way valve 31, the second four-way valve 32, and the third four-way valve 33, the heat exchanger group 10, the first expansion valve 51, the second expansion valve 52, and the indoor heat exchanger The refrigerant circuit is sequentially connected by the refrigerant pipe 70 to form a refrigerant circuit. In the refrigerant pipe 70, the path of the refrigerant flowing between the components connected to the refrigerant pipe 70 will be described as a flow path.

  Specifically, the first four-way valve 31, the first heat exchanger 11, and the first expansion valve 51 are connected in series between the compressor 5 and the heat exchanger group 10, and the second four-way valve 32 The second heat exchanger 12 is connected in series, and the third four-way valve 33 and the third heat exchanger 13 are connected in series. The first four-way valve 31, the first heat exchanger 11, the first expansion valve 51, the second four-way valve 32, the second heat exchanger 12, the third four-way valve 33, the third heat exchanger 13, Are connected in parallel. The first expansion valve 51 and the second expansion valve 52 are connected in parallel.

  A refrigerant pipe 70 (flow path 77) extending from the second heat exchanger 12 to the second expansion valve 52; a refrigerant pipe 70 (flow path 79) extending from the third heat exchanger 13 to the second expansion valve 52; Are joined and connected to a refrigerant pipe 70 (flow path 80) connected to the second expansion valve 52. A refrigerant pipe 70 (flow path 80) connecting the second heat exchanger 12 and the third heat exchanger 13 to the second expansion valve 52, and a refrigerant pipe 70 connecting the first four-way valve 31 and the first heat exchanger 11 A refrigerant pipe 70 (flow path 81) as a bypass pipe is connected between the (flow path 74).

  Further, a third solenoid valve 43 is provided in a refrigerant pipe (flow path 77) extending from the second heat exchanger 12 toward the second expansion valve 52. A fourth solenoid valve 44 is provided in the refrigerant pipe 70 (flow path 79) extending from the third heat exchanger 13 toward the second expansion valve 52. A second solenoid valve 42 is provided in the refrigerant pipe 70 (flow path 81) as a bypass pipe. A first solenoid valve 41 is provided in the refrigerant pipe 70 (flow path 74) connecting the first four-way valve 31 and the first heat exchanger 11.

  The first solenoid valve 41, the second solenoid valve 42, the third solenoid valve 43, and the fourth solenoid valve 44 are valves that control the flow of the refrigerant flowing through the flow path in the refrigerant pipe 70. When the first solenoid valve 41, the second solenoid valve 42, the third solenoid valve 43, and the fourth solenoid valve 44 are opened, the refrigerant flows through a predetermined flow path in the refrigerant pipe 70. By closing the first solenoid valve 41, the second solenoid valve 42, the third solenoid valve 43, and the fourth solenoid valve 44, the flow of the refrigerant in the predetermined flow path is stopped. In the air conditioner 1, the refrigerant pipe 70 (flow path 81) serving as a bypass pipe, and the first and second solenoid valves 41 and 42 are connected in parallel to the second heat exchanger 12 and the third heat exchanger 13. The performed first heat exchanger 11 can be connected in series to the second heat exchanger 12 and the third heat exchanger 13.

  The details will be described below. The outdoor unit 3 houses a first heat exchanger 11, a second heat exchanger 12, and a third heat exchanger 13 as a heat exchanger group 10. The first heat exchanger 11, the second heat exchanger 12, and the third heat exchanger 13 have uniform heat having the same physical structure such as size, number of refrigerant paths (PN), and fin arrangement. Exchanger is used.

  A first fan 21, a first motor 22, a second fan 23, and a second motor 24 for sending outside air are arranged in the heat exchanger group 10. Further, a compressor 5 for compressing the refrigerant and an accumulator 6 for storing the liquid refrigerant are accommodated.

  A flow path 71 is connected to the discharge side of the compressor 5. A flow path 72 is connected to the suction side of the compressor 5 via the accumulator 6. Further, the outdoor unit 3 and the indoor unit 2 are connected by the flow path 73 and the flow path 82.

  The channel 74 and the channel 75 are connected to the first heat exchanger 11. The flow path 76 and the flow path 77 are connected to the second heat exchanger 12. The flow path 78 and the flow path 79 are connected to the third heat exchanger 13.

  When operating the heat exchanger group 10 as a condenser (cooling operation), in the first heat exchanger 11, the refrigerant flows from the flow path 74 through the first heat exchanger 11 to the flow path 75. Become. In the second heat exchanger 12, the refrigerant flows from the flow path 76 to the flow path 77 via the second heat exchanger 12. In the third heat exchanger 13, the refrigerant flows from the channel 78 to the channel 79 via the third heat exchanger 13.

  On the other hand, when operating the heat exchanger group 10 as an evaporator (heating operation), in the first heat exchanger 11, the refrigerant flows from the flow path 75 to the flow path 74 via the first heat exchanger 11. Will be. In the second heat exchanger 12, the refrigerant flows from the flow channel 77 through the flow channel 76 via the second heat exchanger 12. In the third heat exchanger 13, the refrigerant flows from the flow path 79 through the third heat exchanger 13 to the flow path 78.

  A first operation for switching the flow of refrigerant between a first operation (cooling operation) in which the heat exchanger group 10 operates as a condenser and a second operation (heating operation) in which the heat exchanger group 10 operates as an evaporator. A four-way valve 31, a second four-way valve 32, and a third four-way valve 33 are provided.

  In the first four-way valve 31, during the cooling operation, the flow path 71 and the flow path 74 are connected, and the flow path 72 and the flow path 73 are connected. On the other hand, during the heating operation, the flow path 71 and the flow path 73 are connected, and the flow path 72 and the flow path 74 are connected.

  In the second four-way valve 32, during the cooling operation, the flow path 71 and the flow path 76 are connected, and the flow path 72 and the flow path 73 are connected via the check valve 55. On the other hand, during the heating operation, the flow path 76 and the flow path 72 are connected. In the third four-way valve 33, the channel 71 and the channel 78 are connected during the cooling operation. On the other hand, during the heating operation, the flow path 78 and the flow path 72 are connected.

  In addition, a first electromagnetic valve 41, a second electromagnetic valve 42, a third electromagnetic valve 43, and a fourth electromagnetic valve 44 for switching the flow of the refrigerant are provided to cope with various operation operations. Further, a first expansion valve 51 and a second expansion valve 52 for adjusting the flow rate of the refrigerant are provided.

  The first solenoid valve 41 is provided in the flow path 74. The second solenoid valve 42 is provided in the flow path 81. The third solenoid valve 43 is provided in the flow channel 77. The fourth solenoid valve 44 is provided in the flow channel 79. The first expansion valve 51 is a linear electronic expansion valve provided in the flow channel 75. The second expansion valve 52 is a linear electronic expansion valve provided in the flow path 80. The flow path 80 is connected to the flow path 77 and the flow path 79 and the flow path 82. The flow path 81 is connected to the flow path 74 and the flow path 80. The air conditioner 1 according to Embodiment 1 is configured as described above.

(Cooling operation operation 1)
Next, as an operation of the above-described air conditioner 1, a first operation (cooling operation) of operating the heat exchanger group 10 as a condenser will be described. As shown in FIG. 2, in this case, the first solenoid valve 41 is closed. The second solenoid valve 42, the third solenoid valve 43, and the fourth solenoid valve 44 are "open". The first expansion valve 51 is set to “full open”. The second expansion valve 52 is set to “fully closed”. In each of the first four-way valve 31, the second four-way valve 32, and the third four-way valve 33, a solid line indicates ON (open), and a dotted line indicates OFF (closed). Hereinafter, the same applies.

  The refrigerant R in a high-temperature and high-pressure gas state discharged from the compressor 5 flows through the flow path 71 and is branched into a flow path 76 and a flow path 78. The refrigerant R flows through the second four-way valve 32 and the flow path 76 and is sent to the second heat exchanger 12. The refrigerant R flows through the third four-way valve 33 and the flow path 78 and is sent to the third heat exchanger 13.

  In the second heat exchanger 12, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in a gas state starts to condense, gradually liquefies, and the two-phase state of the liquid refrigerant and the gas refrigerant Refrigerant. In the third heat exchanger 13, heat exchange is performed between the refrigerant R and the outside air, the refrigerant R in a gaseous state starts to condense and gradually liquefies, and a two-phase state of the liquid refrigerant and the gaseous refrigerant Refrigerant.

  The two-phase refrigerant R flowing through the second heat exchanger 12 and the two-phase refrigerant R flowing through the third heat exchanger 13 flow through the flow path 80 and merge. The joined refrigerant R flows through the flow path 81 and the flow path 74 and is sent to the first heat exchanger 11. In the first heat exchanger 11, heat exchange is performed between the refrigerant R and the outside air, the remaining gas refrigerant is further liquefied, and the refrigerant R finally becomes a single-phase liquid refrigerant (subcool). It flows through the first heat exchanger 11.

  The refrigerant R flowing through the first heat exchanger 11 flows through the flow path 75 (the first expansion valve 51) and the flow path 82, and is sent to the indoor unit 2 (see FIG. 1). In the indoor unit 2, the refrigerant R in the liquid state undergoes heat exchange with indoor air and evaporates to become a low-pressure gas refrigerant. The room is cooled by this heat exchange. The refrigerant R that has become a low-pressure gas refrigerant flows through the flow path 73, the first four-way valve 31 or the second four-way valve 32, and the flow path 72, is sent to the compressor 5, and is compressed again. Hereinafter, this operation is repeated.

  In the air conditioner 1 described above, when performing the cooling operation, the refrigerant discharged from the compressor 5 joins after flowing through the second heat exchanger 12 or the third heat exchanger 13 in parallel, and the joined refrigerant is the second refrigerant. By flowing through one heat exchanger 11, heat transfer performance can be improved. This will be described in comparison with the air conditioner according to the comparative example.

  As illustrated in FIG. 3, in the air-conditioning apparatus 101 according to the comparative example, when performing the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor (not illustrated) is first arranged in the outdoor unit 104. Into the first heat exchanger 111. In the first heat exchanger 111, the gas refrigerant exchanges heat with the outside air and is condensed to be a two-phase refrigerant of a liquid refrigerant and a gas refrigerant.

  The refrigerant in the two-phase state flows from the first heat exchanger 111 to the second heat exchanger 112 as indicated by the arrow. In the second heat exchanger 112, the two-phase refrigerant exchanges heat with the outside air, the remaining gas refrigerant is further liquefied, and a single-phase liquid refrigerant is supplied from the middle of the second heat exchanger 112. (Sub-cool).

  Here, the number of the first unit channels of the first heat exchanger 111 and the number of the second unit channels of the second heat exchanger 112 are set to the same number. For this reason, it becomes difficult to increase the flow velocity of the liquid refrigerant that has become a single-phase liquid refrigerant in the middle of the second heat exchanger 112. As a result, it becomes difficult to improve the heat transfer performance in the portion flowing through the second heat exchanger 112 as the liquid refrigerant.

  Further, when the number of the first unit channels and the number of the second unit channels are the same, the pressure loss of the refrigerant flowing in the two-phase state increases. In order to suppress the pressure loss, the number increases, and the heat transfer performance of a portion flowing as a liquid refrigerant (subcool) deteriorates. That is, there is a trade-off between the pressure loss of the refrigerant flowing in the two-phase state and the heat transfer performance of the portion flowing as the liquid refrigerant (subcool).

  In contrast to the air conditioner 101 according to the comparative example, in the air conditioner 1 described above, three equal heat exchangers are used as the first heat exchanger 11, the second heat exchanger 12, and the third heat exchanger 13. The number of refrigerant paths through which the refrigerant flows is the same (PN).

  In the cooling operation, the refrigerant discharged from the compressor 5 joins after flowing in parallel through the second heat exchanger 12 and the third heat exchanger 13, and the joined refrigerant flows through the first heat exchanger 11. At this time, the number of refrigerant paths (2 × PN) when flowing in parallel through the second heat exchanger 12 and the third heat exchanger 13 is different from the number of refrigerant paths when flowing through the first heat exchanger 11. The number (PN) is halved.

  As a result, the flow velocity when finally becoming a single-phase liquid refrigerant (subcool) and flowing through the first heat exchanger 11 increases. By increasing the flow rate of the liquid refrigerant, the heat transfer performance when operating the heat exchanger group 10 as a condenser can be improved.

(Heating operation 1)
Next, as the operation of the above-described air conditioner 1, a first operation of a second operation (heating operation) in which the heat exchanger group 10 operates as an evaporator will be described.

  As shown in FIG. 4, in this case, the first solenoid valve 41, the third solenoid valve 43, and the fourth solenoid valve 44 are “open”. The second solenoid valve 42 is closed. The first expansion valve 51 and the second expansion valve 52 are “fully opened”.

  The refrigerant R, which is in a high-temperature and high-pressure gas state, discharged from the compressor 5 flows through the flow path 71 and the first four-way valve 31, and is sent to the indoor unit 2 (see FIG. 1). In the indoor unit 2, the refrigerant R in a gaseous state exchanges heat with indoor air to be condensed to become a high-pressure liquid refrigerant. By this heat exchange, the room is heated. The refrigerant R that has become the liquid refrigerant is turned into a two-phase refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by a throttle device (not shown), and flows through the flow path 82 to the outdoor unit 3.

  The refrigerant R sent to the outdoor unit 3 is branched into a flow path 80 and a flow path 75. The refrigerant R flowing through the flow path 75 (the first expansion valve 51) is sent to the first heat exchanger 11. The refrigerant R flowing through the flow path 80 (the second expansion valve 52) is further branched into a flow path 77 and a flow path 79. The refrigerant R flowing through the flow path 77 (the third solenoid valve 43) is sent to the second heat exchanger 12. The refrigerant R flowing through the flow path 79 (the fourth solenoid valve 44) is sent to the third heat exchanger 13.

  In the first heat exchanger 11, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant. In the second heat exchanger 12, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant. In the third heat exchanger 13, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant.

  The refrigerant R flowing through the first heat exchanger 11 and becoming a gas refrigerant flows through the flow path 74 (the first electromagnetic valve 41) and the first four-way valve 31. The refrigerant R flowing through the second heat exchanger 12 and becoming the gas refrigerant flows through the flow path 76 and the second four-way valve 32. The refrigerant R flowing through the third heat exchanger 13 and becoming a gas refrigerant flows through the flow path 78 and the third four-way valve 33.

  The refrigerant R flowing through the first four-way valve 31, the refrigerant R flowing through the second four-way valve 32, and the refrigerant R flowing through the third four-way valve 33 merge and flow through the flow path 72. The refrigerant R flowing through the flow path 72 is sent to the compressor 5 via the accumulator 6, and is compressed again. Hereinafter, this operation is repeated.

  In the above-described air conditioner 1, when performing the heating operation, in the outdoor unit 3, the refrigerant R sent from the indoor unit 2 is supplied to the first heat exchanger 11, the second heat exchanger 12, the third heat exchanger 13, Flow in parallel. At this time, the number of refrigerant paths is three times the number of paths PN per heat exchanger (3 × PN). For this reason, in the heating operation, the number of refrigerant paths increases as compared with the cooling operation. Thereby, in the heating operation in which the heat exchanger group 10 functions as an evaporator, the pressure loss of the refrigerant is reduced, and the performance of the heat exchanger group 10 as the evaporator can be improved, thereby improving the heating performance. be able to.

  Next, an effect obtained by using three four-way valves of the first four-way valve 31, the second four-way valve 32, and the third four-way valve 33 in the outdoor unit 3 will be described.

  As described above, in the first example of the cooling operation, the high-temperature and high-pressure refrigerant R discharged from the compressor 5 and branched flows through the second four-way valve 32 and the third four-way valve 33. The low-pressure refrigerant R sent from the indoor unit 2 flows through the first four-way valve 31 and the second four-way valve 32.

  Thereby, the pressure loss of the high-temperature and high-pressure refrigerant R can be reduced as compared with the case where the high-temperature and high-pressure refrigerant R discharged from the compressor 5 flows through one four-way valve. Further, the pressure loss of the low-pressure refrigerant R can be reduced as compared with the case where the low-pressure refrigerant R sent from the indoor unit 2 flows through one four-way valve.

  On the other hand, in the first example of the heating operation, the high-temperature and high-pressure refrigerant R discharged from the compressor 5 flows through the first four-way valve 31. The low-pressure refrigerant R flowing through the first heat exchanger 11 flows through the first four-way valve 31. The low-pressure refrigerant R flowing through the second heat exchanger 12 flows through the second four-way valve 32. The low-pressure refrigerant R flowing through the third heat exchanger 13 flows through the third four-way valve 33. Thereby, the pressure loss of the low-pressure refrigerant R can be reduced as compared with the case where the refrigerant R flows through one four-way valve.

  The high-temperature and high-pressure refrigerant R flows through the first four-way valve 31 and does not flow through the second four-way valve 32 and the third four-way valve 33. Thereby, the low-pressure refrigerant R flowing through the second four-way valve 32 does not exchange heat with the high-temperature and high-pressure refrigerant R inside the second four-way valve 32. Further, the low-pressure refrigerant R flowing through the third four-way valve 33 does not exchange heat with the high-temperature and high-pressure refrigerant R inside the third four-way valve 33. As a result, the heat exchange loss inside the second four-way valve 32 and the third four-way valve 33 can be reduced.

(Cooling operation operation 2)
Next, a second operation performed when the load of the first operation (cooling operation) for operating the heat exchanger group 10 of the above-described air conditioner 1 as a condenser is low will be described.

  For example, there is a case where a cooling load that occurs throughout the year such as a computer room server room occurs. Even in summer, the outside temperature may be relatively low. Further, even when the outside air temperature is not low, the load on the indoor unit may be low. Under such a situation, the load during the cooling operation becomes small. When the load of the cooling operation is low, the performance of the heat exchanger group 10 and the like is reduced in order to maintain the compression ratio of the compressor.

  As one of means for lowering the performance of the heat exchanger group 10 and the like, there is a method of reducing the air volume by the first fan 21 and the second fan 23. However, there are limits to reducing the air volume. In such a case, a method that does not use a part of the heat exchangers of the heat exchanger group 10 is adopted.

  As shown in FIG. 5, in this case, the first solenoid valve 41 and the fourth solenoid valve 44 are “closed”. The second solenoid valve 42 and the third solenoid valve 43 are set to “open”. The first expansion valve 51 is set to “full open”. The second expansion valve 52 is set to “fully closed”.

  The refrigerant R in a high-temperature and high-pressure gas state discharged from the compressor 5 flows through the flow path 71, the second four-way valve 32, and the flow path 76, and is sent to the second heat exchanger 12. In the second heat exchanger 12, heat is exchanged between the refrigerant R and the outside air to condense. The refrigerant R flowing through the second heat exchanger 12 flows through the flow path 77 (third electromagnetic valve 43), the flow path 81 (second electromagnetic valve 42), and the flow path 74, and is sent to the first heat exchanger 11. . In the first heat exchanger 11, heat exchange is further performed between the refrigerant R in a gaseous state and the outside air to condense, and the refrigerant R becomes a liquid refrigerant.

  The refrigerant R flowing through the first heat exchanger flows through the flow path 75 and the flow path 82, and is sent to the indoor unit 2 (see FIG. 1). In the indoor unit 2, the refrigerant R in a gaseous state exchanges heat with indoor air and evaporates to become a low-pressure gas refrigerant. The room is cooled by this heat exchange. The refrigerant R that has become a low-pressure gas refrigerant flows through the flow path 73, the first four-way valve 31 or the second four-way valve 32, and the flow path 72, is sent to the compressor 5, and is compressed again. Hereinafter, this operation is repeated.

  In the air conditioner 1 described above, when the load of the cooling operation is low, the second heat exchanger 12 and the first heat exchanger 11 in the heat exchanger group 10 are used, and the third heat exchanger is used. 13 is not used. Thereby, the cooling operation according to the load is performed, the compression ratio of the compressor 5 can be maintained, and the desired high-temperature and high-pressure refrigerant R can be discharged from the compressor 5.

  Further, the third four-way valve 33 is in a closed state so that the flow path 71 and the flow path 78 are not connected. This can prevent the high-pressure refrigerant R from flowing into the third heat exchanger 13. As a result, it is possible to prevent the refrigerant R from staying in the third heat exchanger 13, and prevent the amount of the refrigerant required for the air conditioner 1 from becoming insufficient. That is, stagnation of the refrigerant can be prevented.

(Cooling operation operation 3)
Here, the third operation performed when the load of the cooling operation is lower than the second operation will be described. As shown in FIG. 6, in this case, the first solenoid valve 41 is opened. The second solenoid valve 42, the third solenoid valve 43, and the fourth solenoid valve 44 are closed. The first expansion valve 51 is set to “full open”. The second expansion valve 52 is set to “fully closed”.

  The refrigerant R in a high-temperature and high-pressure gas state discharged from the compressor 5 flows through the flow path 71, the first four-way valve 31, and the flow path 74 (the first solenoid valve 41), and is sent to the first heat exchanger 11. In the first heat exchanger 11, heat exchange is performed between the refrigerant R and the outside air to condense. The refrigerant R flowing through the first heat exchanger 11 flows through the flow path 75 (the first expansion valve 51) and the flow path 82, and is sent to the indoor unit 2 (see FIG. 1).

  In the indoor unit 2, the refrigerant R in a gaseous state exchanges heat with indoor air and evaporates to become a low-pressure gas refrigerant. The room is cooled by this heat exchange. The refrigerant R that has become a low-pressure gas refrigerant flows through the flow path 73, the first four-way valve 31 or the second four-way valve 32, and the flow path 72, is sent to the compressor 5, and is compressed again. Hereinafter, this operation is repeated.

  In the air conditioner 1 described above, when the load of the cooling operation is further reduced, only the first heat exchanger 11 of the heat exchanger group 10 is used, and the second heat exchanger 12 and the third heat exchange The vessel 13 is not used. Thereby, the cooling operation according to the lower load is performed, the compression ratio of the compressor 5 can be maintained, and the desired high-temperature and high-pressure refrigerant R can be discharged from the compressor 5.

  Further, the third four-way valve 33 is in a closed state so that the flow path 71 and the flow path 78 are not connected. This can prevent the high-pressure refrigerant R from flowing into the third heat exchanger 13. The second four-way valve 32 is in a closed state so that the flow path 71 and the flow path 76 are not connected. This can prevent the high-pressure refrigerant R from flowing into the second heat exchanger 12. As a result, in the third heat exchanger 13 and the second heat exchanger 12, the refrigerant R can be prevented from staying, and the amount of the refrigerant required for the air conditioner 1 becomes insufficient. Can be prevented. That is, stagnation of the refrigerant can be prevented.

  When the performance of the heat exchanger group 10 or the like is lowered by lowering the air volume, for example, when a strong wind is blowing, the air volume may increase. In such a case, it is assumed that the performance of the group of heat exchangers is increased and a desired compression ratio cannot be obtained. In the heat exchanger group 10 of the air conditioner described above, since the heat exchanger group 10 is divided into the three heat exchangers of the first heat exchanger 11 to the third heat exchanger 13, the performance of the heat exchanger group increases. Can be minimized.

(Heating operation 2)
Next, as the operation of the above-described air conditioner 1, a second operation (heating operation) of operating the heat exchanger group 10 as an evaporator will be described.

  When operating the air conditioner, in order to perform efficient operation, the temperature of the refrigerant flowing through each heat exchanger such as the first heat exchanger may be set to the same degree of dryness or superheat. Desired.

  When the refrigerant R in the liquid state does not stay in the accumulator 6, the outlet of the refrigerant of the heat exchanger group functioning as an evaporator is generally in a dry state. In such a case, the opening degree of the first expansion valve 51 and the opening degree of the second expansion valve 52 are set so that the temperatures of the refrigerant flowing through the first to third heat exchangers 11 to 13 are the same. The opening degree is adjusted.

  As shown in FIG. 7, in this case, the first solenoid valve 41, the third solenoid valve 43, and the fourth solenoid valve 44 are “open”. The second solenoid valve 42 is closed. The opening degree of the first expansion valve 51 and the second expansion valve 52 is adjusted.

  The refrigerant R in a high-temperature and high-pressure gas state discharged from the compressor 5 flows through the flow path 71, the first four-way valve 31, and the flow path 73, and is sent to the indoor unit 2 (see FIG. 1). In the indoor unit 2, the gaseous refrigerant R exchanges heat with indoor air to be condensed and becomes a high-pressure liquid refrigerant. By this heat exchange, the room is heated. The refrigerant R that has become the liquid refrigerant is turned into a two-phase refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by a throttle device (not shown), and flows through the flow path 82 to the outdoor unit 3.

  The refrigerant R sent to the outdoor unit 3 is branched into a flow path 75 and a flow path 80. At this time, the flow rate of the refrigerant R flowing through the flow path 75 is determined by the opening degree of the first expansion valve 51. The flow rate of the refrigerant R flowing through the flow path 80 is determined by the opening degree of the second expansion valve 52. Each opening degree will be described later.

  The refrigerant R flowing through the flow path 75 (the first expansion valve 51) is sent to the first heat exchanger 11. The refrigerant R flowing through the flow path 80 (the second expansion valve 52) is further branched into a flow path 77 and a flow path 79. The refrigerant R flowing through the flow path 77 (the third solenoid valve 43) is sent to the second heat exchanger 12. The refrigerant R flowing through the flow path 79 (the fourth solenoid valve 44) is sent to the third heat exchanger 13.

  In the first heat exchanger 11, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant. In the second heat exchanger 12, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant. In the third heat exchanger 13, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant.

  The refrigerant R flowing through the first heat exchanger 11 flows through the flow path 74 (the first solenoid valve 41) and the first four-way valve 31. The refrigerant R flowing through the second heat exchanger 12 flows through the flow path 76 and the second four-way valve 32. The refrigerant R flowing through the third heat exchanger 13 flows through the flow path 78 and the third four-way valve 33.

  After the refrigerant R flows through the first four-way valve 31, the temperature (temperature T1) of the refrigerant R is measured at the measurement point P1. After the refrigerant R flows through the second four-way valve 32, the temperature (temperature T2) of the refrigerant R is measured at the measurement point P2. After the refrigerant R flows through the third four-way valve 33, the temperature (temperature T3) of the refrigerant R is measured at the measurement point P3.

  In the air conditioner 1, the temperature difference between the measured temperature T1 and the saturation temperature Ts of the low-pressure side pressure Ps (near the accumulator ACC) of the compressor 5, and the temperature difference between the temperature T2 and the saturation temperature Ts of the low-pressure side pressure Ps. The opening of the first expansion valve 51 and the opening of the second expansion valve 52 are adjusted such that the temperature difference between the temperature T3 and the saturation temperature Ts of the low-pressure side pressure Ps becomes the same temperature.

  The refrigerant R flowing through the first four-way valve 31, the refrigerant R flowing through the second four-way valve 32, and the refrigerant R flowing through the third four-way valve 33 merge and flow through the flow path 72. The refrigerant R flowing through the flow path 72 is sent to the compressor 5 via the accumulator 6, and is compressed again. Hereinafter, this operation is repeated.

  In the air conditioner 1 described above, the first expansion valve 51 is controlled so that the temperature of the refrigerant flowing through each of the first heat exchanger 11, the second heat exchanger 12, and the third heat exchanger 13 becomes the same. The opening and the opening of the second expansion valve 52 are adjusted. Thereby, the performance of the heat exchanger group 10 as an evaporator can be improved.

  Here, when the refrigerant (liquid refrigerant) does not stay in the accumulator 6, that is, when the outlet of the heat exchanger group 10 of the outdoor unit 3 is in the superheat state, the opening degree of the first expansion valve 51 is set. It is assumed that the opening degree of the second expansion valve 52 is set to the same opening degree.

  In that case, the refrigerant of 50% of the refrigerant amount sent to the outdoor unit 3 flows through the first heat exchanger 11. The refrigerant of 25% of the refrigerant amount sent to the outdoor unit 3 flows through the second heat exchanger 12. In the third heat exchanger 13, 25% of the refrigerant flowing to the outdoor unit 3 flows.

  Then, although the refrigerant flowing through the second heat exchanger 12 and the refrigerant flowing through the third heat exchanger 13 are sent out in the same superheat state, the refrigerant flowing through the first heat exchanger 11 is It is supposed that an undesired situation occurs in which the superheat is small and the liquid is sent out in a wet state containing the liquid refrigerant.

  In the air conditioner 1 described above, when the refrigerant R in the liquid state does not accumulate in the accumulator 6, the opening degree of the first expansion valve 51 and the opening degree of the second expansion valve 52 are determined by the respective superheats. By adjusting the value to be constant, each of the first heat exchanger 11, the second heat exchanger 12, and the third heat exchanger 13 has 33% (1%) of the refrigerant amount sent to the outdoor unit 3. The refrigerant R of (/ 3) flows.

  As a result, the refrigerant R flowing through each of the first heat exchanger 11, the second heat exchanger 12, and the third heat exchanger 13 can be sent out in the same dry state, and the evaporator of the heat exchanger group 10 Performance can be improved. Further, when the refrigerant (liquid refrigerant) stays in the accumulator 6, since the superheat at the outlet of the heat exchanger group 10 is hard to be generated, the opening degree of the first expansion valve 51 is set to the second expansion valve 52. By adjusting the opening degree to about half the Cv value (capacity coefficient), the same effect as when the refrigerant (liquid refrigerant) does not stay in the accumulator 6 can be obtained.

  In the above-described air-conditioning apparatus 1, the case where the temperature of the refrigerant R at the measurement point P2 and the temperature of the refrigerant R at the measurement point P3 are measured has been described. The temperature may be measured.

(Heating operation 3)
Next, the third operation of the second operation (heating operation) of operating the heat exchanger group 10 as an evaporator when the air conditioner 1 includes a plurality of outdoor units will be described.

  As an air conditioner, for example, there is an air conditioner provided with a plurality of outdoor units as outdoor units, such as a multi air conditioner for buildings. Here, an air conditioner including such a plurality of outdoor units will be described as an example.

  FIG. 8 shows an air conditioner 1 including at least a first outdoor unit 4a and a second outdoor unit 4b as the outdoor unit 4 of the outdoor unit 3. Each of the first outdoor unit 4a and the second outdoor unit 4b has the same configuration as the outdoor unit 4 shown in FIG. For this reason, the same members are denoted by the same reference numerals, and the description thereof will not be repeated unless necessary.

  Note that the heat exchanger group 10 of the first outdoor unit 4a is a first heat exchanger group, and the heat exchanger group 10 of the second outdoor unit 4b is a second heat exchanger group. The accumulator provided in the first outdoor unit 4a is referred to as a first accumulator, and the accumulator provided in the second outdoor unit 4b is referred to as a second accumulator.

  When the heat exchanger group 10 is operated as an evaporator, the flow of the refrigerant in each of the first outdoor unit 4a and the second outdoor unit 4b is basically the same as the flow of the refrigerant described with reference to FIG. . Therefore, the flow of the refrigerant will be briefly described.

  The high-temperature and high-pressure refrigerant R discharged from the compressor 5 of each of the first outdoor unit 4a and the second outdoor unit 4b flows through the flow paths 71 and 73 and joins the flow path 90. The combined refrigerant R is sent to the indoor unit 2 and exchanges heat with indoor air, and then flows through the flow path 91. While flowing through the flow path 91, the refrigerant R is branched and flows through the flow path 82 of the first outdoor unit 4a or the flow path 82 of the second outdoor unit 4b.

  In the first outdoor unit 4a, the refrigerant R flowing through the flow path 82 is branched into a flow path 75 and a flow path 80. At this time, the flow rate of the refrigerant R flowing through the flow path 75 is determined by the opening degree of the first expansion valve 51. The flow rate of the refrigerant R flowing through the flow path 80 is determined by the opening degree of the second expansion valve 52. Each opening degree will be described later.

  The refrigerant R flowing through the flow path 75 (the first expansion valve 51) is sent to the first heat exchanger 11. The refrigerant R flowing through the flow path 80 (the second expansion valve 52) is branched into a flow path 77 and a flow path 79. The refrigerant R flowing through the flow path 77 (the third solenoid valve 43) is sent to the second heat exchanger 12. The refrigerant R flowing through the flow path 79 (the fourth solenoid valve 44) is sent to the third heat exchanger 13.

  In the first heat exchanger 11, heat is exchanged between the refrigerant R and the outside air. In the second heat exchanger 12, heat exchange is performed between the refrigerant R and the outside air. In the third heat exchanger 13, heat exchange is performed between the refrigerant R and the outside air. The refrigerant R that has undergone heat exchange in the first heat exchanger 11 flows through the flow path 74 (the first solenoid valve 41) and the first four-way valve 31. The refrigerant R that has undergone heat exchange in the second heat exchanger 12 flows through the flow path 76 and the second four-way valve 32. The refrigerant R that has undergone heat exchange in the third heat exchanger 13 flows through the flow path 78 and the third four-way valve 33.

  The refrigerant R flowing through the first four-way valve 31, the refrigerant R flowing through the second four-way valve 32, and the refrigerant R flowing through the third four-way valve 33 merge and flow through the flow path 72. The refrigerant R flowing through the flow path 72 is sent to the compressor 5 via the accumulator 6, and is compressed again. Hereinafter, this operation is repeated in the first outdoor unit 4a.

  On the other hand, in the second outdoor unit 4b, the refrigerant R flowing through the flow path 82 is branched into a flow path 75 and a flow path 80. At this time, the flow rate of the refrigerant R flowing through the flow path 75 is determined by the opening degree of the first expansion valve 51. The flow rate of the refrigerant R flowing through the flow path 80 is determined by the opening degree of the second expansion valve 52. Each opening degree will be described later.

  The refrigerant R flowing through the flow path 75 (the first expansion valve 51) is sent to the first heat exchanger 11. The refrigerant R flowing through the flow path 80 (the second expansion valve 52) is branched into a flow path 77 and a flow path 79. The refrigerant R flowing through the flow path 77 (the third solenoid valve 43) is sent to the second heat exchanger 12. The refrigerant R flowing through the flow path 79 (the fourth solenoid valve 44) is sent to the third heat exchanger 13.

  In the first heat exchanger 11, heat is exchanged between the refrigerant R and the outside air. In the second heat exchanger 12, heat exchange is performed between the refrigerant R and the outside air. In the third heat exchanger 13, heat exchange is performed between the refrigerant R and the outside air. The refrigerant R that has undergone heat exchange in the first heat exchanger 11 flows through the flow path 74 (the first solenoid valve 41) and the first four-way valve 31. The refrigerant R that has undergone heat exchange in the second heat exchanger 12 flows through the flow path 76 and the second four-way valve 32. The refrigerant R that has undergone heat exchange in the third heat exchanger 13 flows through the flow path 78 and the third four-way valve 33.

  The refrigerant R flowing through the first four-way valve 31, the refrigerant R flowing through the second four-way valve 32, and the refrigerant R flowing through the third four-way valve 33 merge and flow through the flow path 72. The refrigerant R flowing through the flow path 72 is sent to the compressor 5 via the accumulator 6, and is compressed again. Hereinafter, this operation is repeated in the second outdoor unit 4b.

  In each of the first outdoor unit 4a and the second outdoor unit 4b of the air conditioner 1, the accumulator 6 is connected to the suction side of the compressor 5. When the group of heat exchangers 10 is operated as an evaporator (heating operation), liquid refrigerant is usually stored in the accumulator 6.

  As described above, during the heating operation, the refrigerant flowing through the indoor unit 2 is branched and sent to the first outdoor unit 4a or the second outdoor unit 4b. In the first outdoor unit 4a, after flowing through the heat exchanger group 10, it is sent to the suction side of the compressor 5 via the accumulator 6. Also in the second outdoor unit 4b, after flowing through the heat exchanger group 10, the air is sent to the suction side of the compressor 5 via the accumulator 6.

  When a plurality of outdoor units 4 are arranged like the first outdoor unit 4a and the second outdoor unit 4b, the pressure of the branched refrigerant depends on the position where the refrigerant flowing through the indoor unit 2 is branched. May be different. For this reason, the amount of the refrigerant R branched from the flow path 91 and sent to the first outdoor unit 4a may be different from the amount of the refrigerant R branched from the flow path 91 and sent to the second outdoor unit 4b. That is, the refrigerant R may not be evenly distributed to the first outdoor unit 4a and the second outdoor unit 4b.

  At this time, for example, assuming that the amount of the refrigerant R sent to the first outdoor unit 4a is relatively large, the amount of the liquid refrigerant in the accumulator 6 of the first outdoor unit 4a increases and becomes full, and the liquid refrigerant is compressed. It is assumed that there is a risk of flowing into the compressor 5 and damaging the compressor 5.

  In the air conditioner 1 described above, for example, the liquid level is detected in the accumulator 6 so that the amount of the liquid refrigerant in the accumulator 6 disposed in each of the first outdoor unit 4a and the second outdoor unit 4b is the same. The amount of the refrigerant R sent to the first outdoor unit 4a and the second outdoor unit are set so that the liquid level is constant by inserting the vessel and the discharge superheat of the compressor 5 has the same value. 4b is adjusted.

  That is, the opening degree of the first expansion valve 51 and the opening degree of the second expansion valve 52 of each of the first outdoor unit 4a and the second outdoor unit 4b are set so that the amount of the refrigerant R branched is the same. Is adjusted.

  When the amount of the refrigerant R sent to each of the first outdoor unit 4a and the second outdoor unit 4b becomes the same amount, the amount of the liquid refrigerant in the accumulator 6 becomes the same amount, and the compressor 5 is damaged. Can be prevented.

Embodiment 2 FIG.
(Constitution)
An air conditioner according to Embodiment 2 will be described. As shown in FIG. 9, the air conditioner 1 is provided with a three-branch distributor 61 that branches the refrigerant into three. In the three-branch distributor 61, a flow path 75 connected to the first heat exchanger 11, a flow path 77 connected to the second heat exchanger 12, and a flow path connected to the third heat exchanger 13. 79 and a flow path 82 connected to the indoor unit 2 is connected.

  As shown in FIG. 10, in the three-branch distributor 61, three openings 63 a, 63 b, and 63 c are formed at one end of the hollow tube 62 at equal circumferential distances. Each of the openings 63a, 63b, 63c communicates with the hollow portion of the hollow tube 62. For example, the channel 75 is connected to the opening 63a. The channel 77 is connected to the opening 63b. The channel 79 is connected to the opening 63c. A channel 82 is connected to the other end of the hollow tube 62.

  The flow path 75 is provided with a first expansion valve 51. The flow path 77 is provided with a second expansion valve 52. The third expansion valve 53 is provided in the flow path 79. The channel 81 is connected to the channel 77 and the channel 79. Since the other configuration is the same as that of the air conditioner 1 shown in FIG. 1, the same members are denoted by the same reference numerals, and the description thereof will not be repeated unless necessary.

(Heating operation 1)
Next, as an operation of the air-conditioning apparatus 1 according to Embodiment 2, a second operation (heating operation) of operating the heat exchanger group 10 as an evaporator will be described.

  As shown in FIG. 11, in this case, the first solenoid valve 41, the third solenoid valve 43, and the fourth solenoid valve 44 are "open". The second solenoid valve 42 is closed. The opening degrees of the first expansion valve 51, the second expansion valve 52, and the third expansion valve 53 are not particularly adjusted.

  The refrigerant R in a high-temperature and high-pressure gas state discharged from the compressor 5 flows through the flow path 71, the first four-way valve 31, and the flow path 73, and is sent to the indoor unit 2 (see FIG. 1). In the indoor unit 2, the refrigerant R exchanges heat with indoor air to be condensed and becomes a high-pressure liquid refrigerant. By this heat exchange, the room is heated. The refrigerant R that has become the liquid refrigerant is turned into a two-phase refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by a throttle device (not shown), and flows through the flow path 82 to the outdoor unit 3.

  In the outdoor unit 3, the refrigerant R flowing through the flow path 82 is divided into three equal parts of the flow path 75, the flow path 77, and the flow path 79 by the three-branch distributor 61. The refrigerant R flowing through the flow path 75 (the first expansion valve 51) is sent to the first heat exchanger 11. The refrigerant R flowing through the flow path 77 (the second expansion valve 52) is sent to the second heat exchanger 12. The refrigerant R flowing through the flow path 79 (the third expansion valve 53) is sent to the third heat exchanger 13.

  In the first heat exchanger 11, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant. In the second heat exchanger 12, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant. In the third heat exchanger 13, heat exchange is performed between the refrigerant R and the outside air, and the refrigerant R in the two-phase state evaporates to a gas refrigerant.

  The refrigerant R flowing through the first heat exchanger 11 flows through the flow path 74 (the first solenoid valve 41) and the first four-way valve 31. The refrigerant R flowing through the second heat exchanger 12 flows through the flow path 76 and the second four-way valve 32. The refrigerant R flowing through the third heat exchanger 13 flows through the flow path 78 and the third four-way valve 33.

  The refrigerant R flowing through the first four-way valve 31, the refrigerant R flowing through the second four-way valve 32, and the refrigerant R flowing through the third four-way valve 33 merge and flow through the flow path 72. The refrigerant R flowing through the flow path 72 is sent to the compressor 5 via the accumulator 6, and is compressed again. Hereinafter, this operation is repeated.

  In the above-described air-conditioning apparatus 1, the refrigerant R sent from the indoor unit 2 is equally divided by the three-branch distributor 61 into three channels, that is, the channel 75, the channel 77, and the channel 79. Thereby, the first heat exchanger 11, the second heat exchanger 12, and the third heat exchanger 13 can be adjusted without adjusting the openings of the first expansion valve 51, the second expansion valve 52, and the third expansion valve 53. Each can be fed with the same amount of refrigerant. As a result, the refrigerant can be efficiently evaporated, and the evaporation performance of the heat exchanger group 10 as an evaporator can be improved.

(Heating operation 2)
Here, the second operation performed when the load of the second operation (heating operation) for operating the heat exchanger group 10 as an evaporator is low will be described. Specifically, the low-load heating operation is a heating operation when the temperature of the outside air is relatively high, and is a time when the compressor frequency is low.

  As shown in FIG. 12, in this case, the first solenoid valve 41 is closed. The second solenoid valve 42, the third solenoid valve 43, and the fourth solenoid valve 44 are "open". The opening degree of the first expansion valve 51 is “full open”. The opening degrees of the second expansion valve 52 and the third expansion valve 53 are set to “fully closed”.

  The refrigerant R in a high-temperature and high-pressure gas state discharged from the compressor 5 flows through the flow path 71, the first four-way valve 31, and the flow path 73, and is sent to the indoor unit 2 (see FIG. 1). In the indoor unit 2, the refrigerant R exchanges heat with the indoor air and condenses to become a high-pressure liquid refrigerant. By this heat exchange, the room is heated. The refrigerant R that has become the liquid refrigerant is turned into a two-phase refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by a throttle device (not shown), and flows through the flow path 82 to the outdoor unit 3.

  In the outdoor unit 3, the refrigerant R flowing through the flow path 82 flows through the three-branch distributor 61 and the first expansion valve 51, and flows into only the flow path 75. The refrigerant R flowing through the flow path 75 is sent to the first heat exchanger 11. In the first heat exchanger 11, heat is exchanged between the refrigerant R and the outside air. The refrigerant R that has flowed through the first heat exchanger 11 flows through the flow path 74 and the flow path 81 (the second solenoid valve 42), and is branched into two, a flow path 77 and a flow path 79.

  The refrigerant R flowing through the flow path 77 (the third solenoid valve 43) is sent to the second heat exchanger 12. The refrigerant R flowing through the flow path 79 (the fourth solenoid valve 44) is sent to the third heat exchanger 13. In the second heat exchanger 12, heat exchange is performed between the refrigerant R and the outside air. In the third heat exchanger 13, heat exchange is performed between the refrigerant R and the outside air.

  The refrigerant R having undergone heat exchange in the second heat exchanger 12 flows through the flow path 76 and the second four-way valve 32. The refrigerant R that has undergone heat exchange in the third heat exchanger 13 flows through the flow path 78 and the third four-way valve 33. The refrigerant R flowing through the second four-way valve 32 and the refrigerant R flowing through the third four-way valve 33 merge and flow through the flow path 72. The refrigerant R flowing through the flow path 72 is sent to the compressor 5 via the accumulator 6, and is compressed again. Hereinafter, this operation is repeated.

  In the air conditioner 1 described above, the refrigerant R sent from the indoor unit 2 flows through the first heat exchanger 11, and then branches into two, and one refrigerant flows through the second heat exchanger 12, The other refrigerant flows through the third heat exchanger 13. At this time, the number of refrigerant paths through which the refrigerant R flows becomes twice as many as the number of paths PN. Thereby, the flow rate of the refrigerant R can be reduced.

  Here, the characteristics of the pressure loss with respect to the dryness will be described. Generally, the pressure loss increases as the dryness increases. In the air-conditioning apparatus 1, after the two-phase refrigerant having a dryness of about 0.2 flows through the first heat exchanger 11, the two-branched refrigerant having a reduced flow velocity flows through the second heat exchanger and the third heat exchanger. Since it flows into the vessel, it is possible to suppress an increase in pressure loss.

  In each of the above-described embodiments, three uniform first heat exchangers 11, second heat exchangers 12, and third heat exchangers 13 are given as examples of the heat exchangers of the heat exchanger group 10. Although described, the heat exchangers are not necessarily required to be uniform, and heat exchangers having different physical structures such as sizes and the number of refrigerant paths may be included.

  Further, in each of the above-described embodiments, three heat exchangers have been described as examples of the heat exchangers of the heat exchanger group 10. However, the number of heat exchangers is not necessarily three, and a plurality (third heat exchanger) may be used. ) Heat exchangers connected in series, the number (first number) of heat exchangers through which the refrigerant flows after the number (first number) of heat exchangers connected in parallel through which the refrigerant first flows If the number of (2) is small, the same effect can be obtained. The first number, the second number, and the third number are natural numbers, and the third number is a sum of the first number and the second number.

  The air conditioners described in each embodiment can be variously combined as needed. In addition, each embodiment is applicable not only to an air conditioner but also to a refrigeration cycle device including a refrigeration cycle such as a refrigerator or a freezer.

  The embodiment disclosed this time is an example, and the present invention is not limited to this. The present invention is defined by the terms of the claims, rather than the range described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  INDUSTRIAL APPLICABILITY The present invention is effectively used for a refrigeration cycle device including a heat exchanger group including a plurality of heat exchangers, and an air conditioner including such a refrigeration cycle device.

  Reference Signs List 1 air conditioner, 2 indoor unit, 3 outdoor unit, 4 outdoor unit, 4a first outdoor unit, 4b second outdoor unit, 5 compressor, 6 accumulator, 10 heat exchanger group, 11 first heat exchanger, 12 2nd heat exchanger, 13 3rd heat exchanger, 21 1st fan, 22 1st motor, 23 2nd fan, 24 2nd motor, 31 1st 4-way valve, 32 2nd 4-way valve, 33 3rd 4-way valve , 41 first solenoid valve, 42 second solenoid valve, 43 third solenoid valve, 44 fourth solenoid valve, 51 first expansion valve, 52 second expansion valve, 53 third expansion valve, 55 check valve, 613 Branch distributor, 62 hollow pipe, 63a, 63b, 63c opening, 70 refrigerant pipe, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 90, 91 , R refrigerant.

Claims (11)

An refrigeration cycle apparatus comprising: an outdoor unit having a heat exchanger group including a first heat exchanger, a second heat exchanger, and a third heat exchanger; and a refrigerant circuit connecting the heat exchanger group by piping. hand,
In the case of the first operation in which the heat exchanger group operates as a condenser,
Refrigerant flowing in the pipe flows through the first heat exchanger after flowing through the second heat exchanger and the third heat exchanger connected in parallel,
In the case of the second operation in which the heat exchanger group operates as an evaporator,
The refrigerant flowing in the pipe flows through the first heat exchanger, the second heat exchanger, and the third heat exchanger connected in parallel,
In the case of the first operation, one of the second heat exchanger and the third heat exchanger is stopped or the second heat exchanger and the third heat exchanger are stopped according to the load of the first operation. A refrigeration cycle device that stops both operations of the heat exchanger. An refrigeration cycle apparatus comprising: an outdoor unit having a heat exchanger group including a first heat exchanger, a second heat exchanger, and a third heat exchanger; and a refrigerant circuit connecting the heat exchanger group by piping. hand,
In the case of the first operation in which the heat exchanger group operates as a condenser,
Refrigerant flowing in the pipe flows through the first heat exchanger after flowing through the second heat exchanger and the third heat exchanger connected in parallel,
In the case of the second operation in which the heat exchanger group operates as an evaporator,
The refrigerant flowing in the pipe flows through the first heat exchanger, the second heat exchanger, and the third heat exchanger connected in parallel,
In the case of the second operation,
A first expansion valve for adjusting an amount of refrigerant flowing to the first heat exchanger;
A refrigeration cycle apparatus comprising a second expansion valve for adjusting the amount of refrigerant flowing to the second heat exchanger and the third heat exchanger.   The refrigeration cycle apparatus according to claim 2, wherein the temperature of the refrigerant flowing through the first heat exchanger, the temperature of the refrigerant flowing through the second heat exchanger, and the temperature of the refrigerant flowing through the third heat exchanger are equal. . The outdoor unit includes a compressor,
In the case of the second operation,
A first temperature difference between a temperature of the refrigerant after flowing through the first heat exchanger and a saturation temperature at a pressure on a suction side of the compressor; and a temperature of the refrigerant after flowing through the second heat exchanger. The second temperature difference between the refrigerant and the saturation temperature and the third temperature difference between the temperature of the refrigerant after flowing through the third heat exchanger and the saturation temperature are the same temperature difference. Refrigeration cycle equipment. The outdoor unit is
A first unit;
And a second unit,
The first unit has a first heat exchanger group including the first heat exchanger as the heat exchanger group, the second heat exchanger, and the third heat exchanger,
The second unit has a second heat exchanger group including a first heat exchanger, a second heat exchanger, and a third heat exchanger,
In the second unit,
In the case of the second operation, the first heat exchanger in the second heat exchanger group, the second heat exchanger in the second heat exchanger group, and the third heat exchange in the second heat exchanger group And are connected in parallel,
A first expansion valve for adjusting an amount of the refrigerant flowing into the first heat exchanger of the second heat exchanger group;
3. The fuel cell system according to claim 2, further comprising: a second expansion valve that adjusts an amount of the refrigerant flowing into the second heat exchanger of the second heat exchanger group and the third heat exchanger of the second heat exchanger group. 4. A refrigeration cycle apparatus as described in the above. The first unit includes a first accumulator connected to the first heat exchanger group to store the refrigerant,
The second unit includes a second accumulator connected to the second heat exchanger group to store the refrigerant,
The refrigeration according to claim 5, wherein the amount of the refrigerant flowing from the first heat exchanger group to the first accumulator and the amount of the refrigerant flowing from the second heat exchanger group to the second accumulator are the same. Cycle equipment. An refrigeration cycle apparatus comprising: an outdoor unit having a heat exchanger group including a first heat exchanger, a second heat exchanger, and a third heat exchanger; and a refrigerant circuit connecting the heat exchanger group by piping. hand,
In the case of the first operation in which the heat exchanger group operates as a condenser,
Refrigerant flowing in the pipe flows through the first heat exchanger after flowing through the second heat exchanger and the third heat exchanger connected in parallel,
In the case of the second operation in which the heat exchanger group operates as an evaporator,
The refrigerant flowing in the pipe flows through the first heat exchanger, the second heat exchanger, and the third heat exchanger connected in parallel,
The first operation includes a first operation performed when the load of the first operation is high, and a second operation performed when the load of the first operation is lower than the case where the first operation is performed,
In the second operation,
The refrigeration cycle apparatus, wherein the refrigerant sent to the heat exchanger group does not flow into the third heat exchanger, flows through the second heat exchanger, and then flows through the first heat exchanger. The first operation includes a third operation performed when the load of the first operation is further lower than the case where the second operation is performed,
The said 3rd operation | movement, the said refrigerant | coolant sent to the said heat exchanger group does not flow into the said 2nd heat exchanger and the said 3rd heat exchanger, but flows through the said 1st heat exchanger. Refrigeration cycle device. An refrigeration cycle apparatus comprising: an outdoor unit having a heat exchanger group including a first heat exchanger, a second heat exchanger, and a third heat exchanger; and a refrigerant circuit connecting the heat exchanger group by piping. hand,
In the case of the first operation in which the heat exchanger group operates as a condenser,
Refrigerant flowing in the pipe flows through the first heat exchanger after flowing through the second heat exchanger and the third heat exchanger connected in parallel,
In the case of the second operation in which the heat exchanger group operates as an evaporator,
The refrigerant flowing in the pipe flows through the first heat exchanger, the second heat exchanger, and the third heat exchanger connected in parallel,
In the case of the second operation,
A first expansion valve for adjusting an amount of the refrigerant flowing to the first heat exchanger;
A second expansion valve for adjusting the amount of the refrigerant flowing to the second heat exchanger;
A refrigeration cycle apparatus comprising: a third expansion valve that adjusts an amount of the refrigerant flowing to the third heat exchanger. In the second operation,
In the case of a low-load heating operation, the refrigerant flowing in the pipe flows through the first heat exchanger, and then flows through the second heat exchanger and the third heat exchanger connected in parallel. Item 10. A refrigeration cycle apparatus according to item 9. An air conditioner comprising the refrigeration cycle device according to claim 1.

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