JP2014122770A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger capable of suppressing increase in cost, and capable of suppressing performance deterioration of the heat exchanger caused by refrigerant oil accumulating in a heat transfer pipe and reliability decline of a compressor.SOLUTION: An outdoor heat exchanger 34, which is the heat exchanger for condensing a gas cooling medium and discharging it as a liquid cooling medium, includes: a first header part 341; a plurality of heat transfer pipes 343a to 343j; and a lower part conduction structure 341a. The first header part 341 extends in a vertical direction and allows the gas cooling medium to flow in. The plurality of heat transfer pipes 343a to 343j extend in a horizontal direction communicating with the first header part 341, and are arranged in the vertical direction. The lower part conduction structure 341a allows the gas cooling medium to flow into the vicinity of a lowermost stage communication part CP1 in internal space of the first header part 341. Thereby, out of the plurality of heat transfer pipes 343a to 343j, the flow rate of the cooling medium increases from the heat transfer pipe 343j at the lowermost stage in the descending order, and the cooling medium and the refrigerant oil hardly stagnate in the heat transfer pipe 343 and come to flow smoothly.

Description

  The present invention relates to a heat exchanger.

  Conventionally, a heat exchanger used in a system to which a vapor compression refrigeration cycle is applied, and including a header section that allows gas refrigerant to flow in or out, and a heat transfer tube that is connected to the header section and arranged in parallel vertically is known. It has been. For example, a heat exchanger described in Patent Document 1 (Japanese Utility Model Publication No. 63-144554) includes a cylindrical header portion extending along a vertical direction, a heat transfer tube that communicates with the header portion and is arranged in parallel vertically. It is equipped with.

  By the way, when using the heat exchanger which arrange | positioned the heat exchanger tube as described in patent document 1 in parallel up and down as a condenser, the pressure of a liquid refrigerant becomes high in the downward direction in the exit side of a heat exchanger tube. Therefore, for example, when there is a small amount of gas refrigerant flowing into the heat transfer tube, the flow rate exceeding the differential pressure cannot be secured particularly in the heat transfer tube arranged at the bottom, and the liquid refrigerant is pushed back on the outlet side and stagnates in the heat transfer tube. It is possible to do. In such a state, the stagnant liquid refrigerant and the refrigerating machine oil are mixed together, and the refrigerating machine oil is accumulated in the heat transfer tube.As a result, the heat exchanging performance of the heat exchanger is lowered, and the required lubricating oil amount of the compressor is reduced. There is a concern that it cannot be held.

  As a countermeasure against this, Patent Document 2 (Japanese Utility Model Publication No. 62-83154) proposes an idea of connecting an oil return pipe to a header portion and recovering accumulated refrigeration oil to a compressor through a bypass path.

  However, as described in Patent Document 2, the means for recovering the refrigeration oil to the compressor through the bypass path may return the gas refrigerant at the same time as the refrigeration oil. In such a case, the performance of the heat exchanger decreases. Is concerned. Moreover, there is a concern about an increase in cost due to the arrangement of the oil return pipe.

  Accordingly, an object of the present invention is to provide a heat exchanger that can suppress an increase in cost and can suppress a decrease in performance of the heat exchanger and a decrease in reliability of the compressor due to the accumulation of refrigeration oil in the heat transfer tube. .

  A heat exchanger according to a first aspect of the present invention is a heat exchanger that condenses gas refrigerant and discharges it as liquid refrigerant, and includes a cylindrical header portion, a plurality of heat transfer tubes, and a lower conduction structure. Prepare. The header portion extends along the vertical direction and allows the gas refrigerant to flow in. The plurality of heat transfer tubes communicate with the header portion and extend along the horizontal direction, and are arranged along the vertical direction. The lower conductive structure allows the gas refrigerant to flow into the vicinity of the communication portion between the header portion and the lowermost heat transfer tube in the internal space of the header portion.

  The heat exchanger according to the first aspect of the present invention includes a lower conduction structure that allows the gas refrigerant to flow into the vicinity of the communication portion between the header portion and the lowermost heat transfer tube in the internal space of the header portion. Thereby, the flow volume of a refrigerant | coolant increases in descending order from the heat exchanger tube of the lowest stage among several heat exchanger tubes. For this reason, it becomes easy to flow a refrigerant | coolant and refrigerating machine oil in a heat exchanger tube easily by making it a simple structure. As a result, a decrease in performance of the heat exchanger and a decrease in reliability of the compressor are suppressed while suppressing an increase in cost.

  The heat exchanger which concerns on the 2nd viewpoint of this invention is a heat exchanger which concerns on a 1st viewpoint, Comprising: A lower conduction | electrical_connection structure is connected to the lower end vicinity of a header part, and contains refrigerant | coolant piping which flows in a gas refrigerant.

  In the heat exchanger according to the second aspect of the present invention, the lower conduction structure includes a refrigerant pipe that is connected to the vicinity of the lower end of the header portion and allows gas refrigerant to flow in. Thereby, among the plurality of heat transfer tubes, the refrigerant flow rate further increases in descending order from the lowest heat transfer tube. For this reason, the refrigerant and the refrigerating machine oil are more unlikely to stagnate in the heat transfer tube and flow easily.

  A heat exchanger according to a third aspect of the present invention is the heat exchanger according to the first aspect, wherein the lower conduction structure passes through the vicinity of the upper end of the header portion and extends to the vicinity of the lower end of the header portion to receive the gas refrigerant. Including refrigerant piping for inflow.

  In the heat exchanger according to the third aspect of the present invention, the lower conduction structure includes a refrigerant pipe that passes through the vicinity of the upper end of the header portion and extends to the vicinity of the lower end of the header portion to allow the gas refrigerant to flow. Thereby, among the plurality of heat transfer tubes, the refrigerant flow rate further increases in descending order from the lowest heat transfer tube. For this reason, the refrigerant and the refrigerating machine oil are more unlikely to stagnate in the heat transfer tube and flow easily.

  The heat exchanger which concerns on the 4th viewpoint of this invention is a heat exchanger which concerns on a 1st viewpoint, Comprising: A lower conduction | electrical_connection structure contains refrigerant | coolant piping and a partition. The refrigerant pipe is connected to the vicinity of the upper end of the header portion and allows gas refrigerant to flow in. The partition wall extends from the upper end to the vicinity of the lower end along the vertical direction in the internal space of the header portion, and divides the space from the upper end of the internal space of the header portion to the vicinity of the lower end into the first space and the second space. The second space communicates with the plurality of heat transfer tubes. The first space and the second space communicate with each other in the vicinity of the lower end of the header portion.

  In the heat exchanger according to the fourth aspect of the present invention, the lower conductive structure extends from the upper end to the vicinity of the lower end along the vertical direction in the internal space of the header portion, and the space from the upper end to the vicinity of the lower end of the internal space of the header portion is the first. A partition that separates the first space and the second space is included. Thereby, among the plurality of heat transfer tubes, the refrigerant flow rate further increases in descending order from the lowest heat transfer tube. For this reason, the refrigerant and the refrigerating machine oil are more unlikely to stagnate in the heat transfer tube and flow easily.

  The heat exchanger which concerns on the 5th viewpoint of this invention is a heat exchanger which concerns on a 4th viewpoint, Comprising: A some slit is formed in a partition.

  In the heat exchanger according to the fifth aspect of the present invention, a plurality of slits are formed in the partition wall. Thereby, when using a heat exchanger as an evaporator, even if a liquid refrigerant has accumulated in a header part or a heat exchanger tube, gas refrigerant flows out into the 1st space and refrigerant piping via a slit. For this reason, it can suppress that a liquid refrigerant flows out into a refrigerant pipe at a stretch, and as a result, the liquid back phenomenon in which a liquid refrigerant flows into a compressor is controlled.

  The heat exchanger which concerns on the 6th viewpoint of this invention is a heat exchanger which concerns on a 1st viewpoint, Comprising: Upper refrigerant | coolant piping and a 1st on-off valve are further provided. The upper refrigerant pipe is connected to the vicinity of the upper end of the header portion, and allows the gas refrigerant to flow in or out. The first on-off valve is disposed in the upper refrigerant pipe. The lower conduction structure includes a lower refrigerant pipe that is connected to the vicinity of the lower end of the header portion and allows a gas refrigerant to flow in.

  In the heat exchanger according to the sixth aspect of the present invention, the lower conduction structure includes a lower refrigerant pipe that is connected to the vicinity of the lower end of the header portion and flows in the gas refrigerant. Thereby, the flow volume of the refrigerant | coolant of the heat exchanger tube of the lowest stage among several heat exchanger tubes increases. Therefore, the refrigerant and the refrigerating machine oil are less likely to accumulate in the header section and the heat transfer tube, and flow easily.

  Further, in the heat exchanger according to the sixth aspect of the present invention, an upper refrigerant pipe connected to the vicinity of the upper end of the header portion and allowing the gas refrigerant to flow in or out, and a first on-off valve disposed in the upper refrigerant pipe, Further prepare. As a result, even if the refrigerant and the refrigerating machine oil accumulate in the heat transfer pipe, the first on-off valve can be fully closed to control the inflow of gas refrigerant from the lower refrigerant pipe. The refrigerant and the refrigerating machine oil can be flowed to the outlet side of the heat transfer tube by further increasing the flow rate of the refrigerant in descending order from the lowest heat transfer tube among the heat tubes. Therefore, the refrigerant and the refrigerating machine oil are more unlikely to stagnate in the heat transfer tube and flow easily.

  In addition, when the heat exchanger is used as an evaporator, it is possible to control the gas refrigerant to flow out from the upper refrigerant pipe by fully opening the first on-off valve. Even if is accumulated, liquid refrigerant can be prevented from flowing out from the lower refrigerant pipe at a stretch. Therefore, the liquid back phenomenon in which the liquid refrigerant flows into the compressor is suppressed.

  The heat exchanger which concerns on the 7th viewpoint of this invention is a heat exchanger which concerns on a 6th viewpoint, Comprising: The 2nd on-off valve arrange | positioned by lower refrigerant | coolant piping is further provided.

  In the heat exchanger which concerns on the 7th viewpoint of this invention, the 2nd on-off valve arrange | positioned by lower refrigerant | coolant piping is further provided. As a result, when the heat exchanger is used as an evaporator, the second on-off valve can be fully closed to allow the gas refrigerant to flow out from the upper refrigerant pipe, and the liquid refrigerant accumulates in the header section or the heat transfer pipe. Even if it is, it can suppress further more reliably that a liquid refrigerant flows out from a lower refrigerant | coolant piping at a stretch. Therefore, the liquid back phenomenon in which the liquid refrigerant flows into the compressor is further reliably suppressed.

  In the heat exchanger according to the first to seventh aspects of the present invention, the refrigerant and the refrigerating machine oil are less likely to stagnate in the heat transfer tube with a simple configuration, and the performance of the heat exchanger is suppressed while suppressing an increase in cost. The decrease and the decrease in the reliability of the compressor are suppressed.

  In the heat exchanger according to the second to fourth aspects of the present invention, the refrigerant and the refrigeration oil are more unlikely to stagnate within the heat transfer tube and flow more easily.

  In the heat exchanger according to the fifth aspect of the present invention, the liquid back phenomenon in which the liquid refrigerant flows into the compressor is suppressed.

  In the heat exchanger according to the sixth aspect of the present invention, the refrigerant and the refrigeration oil are more unlikely to stagnate in the heat transfer tube and flow easily. Further, the liquid back phenomenon in which the liquid refrigerant flows into the compressor is suppressed.

  In the heat exchanger according to the seventh aspect of the present invention, the liquid back phenomenon in which the liquid refrigerant flows into the compressor is further reliably suppressed.

The schematic structure figure of the air-conditioning system to which the outdoor heat exchanger concerning one embodiment of the present invention is applied. The perspective view of an outdoor heat exchanger. The enlarged view of the 1st header part of an outdoor heat exchanger. The enlarged view of the 1st header part of an outdoor heat exchanger. The enlarged view of the 1st header part of an outdoor heat exchanger. The enlarged view of the 1st header part of an outdoor heat exchanger. The schematic block diagram of the air-conditioning system to which an outdoor heat exchanger is applied. The enlarged view of the 1st header part of an outdoor heat exchanger. The enlarged view of the 1st header part of an outdoor heat exchanger.

  Embodiments of the present invention will be described below with reference to the drawings. The following embodiments are specific examples of the present invention and do not limit the technical scope of the present invention, and can be modified without departing from the scope of the invention. In the following description, words indicating directions such as up, down, left, and right are used. These directions mean the directions shown in FIG. 2 unless otherwise specified.

(1) Air conditioning system 1
FIG. 1 is a schematic configuration diagram of an air conditioning system 1 to which an outdoor heat exchanger 34 according to an embodiment of the present invention is applied.

  The air conditioning system 1 is a cooling-only system used for cooling indoors such as buildings by performing a vapor compression refrigeration cycle operation. The air conditioning system 1 mainly includes a plurality of (in this embodiment, three) indoor units 2a, 2b, and 2c (hereinafter, the indoor units 2a, 2b, and 2c are collectively referred to as an indoor unit 2) and one unit. An outdoor unit 3 as a heat source unit, and a refrigerant communication pipe 4 that connects the indoor unit 2 and the outdoor unit 3 are provided. That is, in the air conditioning system 1 of this embodiment, the vapor compression type refrigerant circuit is configured by connecting the indoor unit 2, the outdoor unit 3, and the refrigerant communication pipe 4. In this embodiment, it is assumed that the refrigerant is R32.

(1-1) Indoor unit 2
The indoor unit 2 is installed by being embedded or suspended in a ceiling of a room such as a building or by hanging on a wall surface of the room. The indoor units 2a, 2b, and 2c have indoor expansion valves 21a, 21b, and 21c (hereinafter, the indoor expansion valves 21a, 21b, and 21c are collectively referred to as the indoor expansion valve 21) as expansion mechanisms. The indoor units 2a, 2b, and 2c have indoor heat exchangers 22a, 22b, and 22c (hereinafter, the indoor heat exchangers 22a, 22b, and 22c are collectively referred to as the indoor heat exchanger 22). Furthermore, the indoor units 2a, 2b, and 2c have indoor fans 23a, 23b, and 23c (hereinafter, the indoor fans 23a, 23b, and 23c are collectively referred to as the indoor fan 23). Furthermore, each of the indoor units 2a, 2b, and 2c has an indoor control unit (not shown).

  The indoor expansion valve 21 is an electric expansion valve connected to the indoor heat exchanger 22 in order to adjust the flow rate of the flowing refrigerant, and can also block the passage of the refrigerant. In the present embodiment, the indoor expansion valve 21 is provided in the indoor unit 2 as an expansion mechanism. However, the present invention is not limited to this, and an expansion mechanism (including an expansion valve) may be provided in the outdoor unit 3. You may provide in the connection unit independent of the apparatus 2 and the outdoor unit 3.

  The indoor heat exchanger 22 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes (not shown) and a large number of fins (not shown), and serves as a refrigerant evaporator during cooling operation. It is a heat exchanger that functions to cool indoor air. The indoor heat exchanger 22 is not limited to a cross fin type fin-and-tube heat exchanger, but may be another type of heat exchanger.

  The indoor fan 23 serves as a blower for supplying indoor air as supply air after sucking indoor air into the indoor unit 2 and exchanging heat with the refrigerant in the indoor heat exchanger 22. The indoor fan 23 is a fan capable of adjusting the air volume supplied to the indoor heat exchanger 22 within a predetermined range, such as a centrifugal fan driven by an indoor fan motor (not shown) such as a DC fan motor. A multi-wing fan.

  The indoor unit control unit is configured by electronic components such as a CPU and a memory, and controls the operation of the indoor unit 2. Specifically, in response to an instruction from the user, the operations of the indoor expansion valve 21 and the indoor fan motor are controlled. The indoor units 2a, 2b, and 2c constitute a common refrigerant circuit, but can be operated independently.

  The indoor unit 2 is connected to the outdoor unit 3 through the refrigerant communication pipe 4.

(1-2) Outdoor unit 3
The outdoor unit 3 is installed outdoors. The outdoor unit 3 mainly includes an accumulator 32, a compressor 33, an outdoor heat exchanger 34 as a heat source side heat exchanger, an outdoor fan 35, an outdoor expansion valve 36 as an expansion mechanism, and an outdoor control unit (illustrated). (Omitted).

  The accumulator 32 is provided between the indoor heat exchanger 23 and the compressor 33, and separates the liquid refrigerant and the gas refrigerant and suppresses the liquid refrigerant from flowing into the compressor 33.

  The compressor 33 is a compressor whose operating capacity can be adjusted. In this embodiment, a positive displacement compressor driven by a compressor motor (not shown) whose rotation speed is controlled by an inverter is employed. Has been. In the present embodiment, polyvinyl ether is used as a refrigerating machine oil that lubricates each sliding portion of the compressor 33. The refrigerating machine oil is mixed with the refrigerant and flows out of the compressor 33 together with the refrigerant, and flows through the refrigerant circuit and is recovered to the compressor 33.

  The outdoor heat exchanger 34 is a cross-fin type fin-and-tube heat exchanger as shown in FIG. 2, and is a device for exchanging heat with refrigerant using air as a heat source. The outdoor heat exchanger 34 is a heat exchanger that functions as a refrigerant condenser during cooling operation. Details of the outdoor heat exchanger 34 will be described later in (2) Details of the outdoor heat exchanger 34.

  The outdoor fan 35 is a blower for sucking outdoor air into the outdoor unit 3, exchanging heat with the refrigerant in the outdoor heat exchanger 34, and then discharging it to the outside of the outdoor unit 3. The outdoor fan 35 is a fan capable of adjusting the air volume supplied to the outdoor heat exchanger 34, and is a propeller fan or the like driven by an outdoor fan motor (not shown) such as a DC fan motor.

  The outdoor expansion valve 36 is an electric expansion valve disposed on the downstream side of the outdoor heat exchanger 34 in the refrigerant flow direction in the refrigerant circuit when performing the cooling operation in order to adjust the pressure and flow rate of the flowing refrigerant. is there.

  The outdoor control unit controls the operation of each part constituting the outdoor unit 3. The outdoor control unit includes a microcomputer including a CPU and a memory, an inverter circuit for controlling a compressor motor, and the like, and is controlled via a transmission line with the indoor control unit of the indoor unit 2. Signals can be exchanged.

  In the outdoor unit 3, the accumulator 32, the compressor 33, and the outdoor heat exchanger 34 are connected by a gas refrigerant pipe 30a. The outdoor heat exchanger 34 and the outdoor expansion valve 36 are connected by a liquid refrigerant pipe 30b. The gas refrigerant pipe 30a and the liquid refrigerant pipe 30b are copper pipes.

(1-3) Refrigerant communication pipe 4
The refrigerant communication pipe 4 is a pipe formed of a metal such as copper, for example, and circulates the refrigerant. The refrigerant communication tube 4 mainly includes a gas refrigerant communication tube 4a and a liquid refrigerant communication tube 4b. As shown in FIG. 1, the gas refrigerant communication pipe 4 a mainly circulates the gas refrigerant between the indoor heat exchanger 22 and the accumulator 32. As shown in FIG. 1, the liquid refrigerant communication tube 4 b mainly circulates liquid refrigerant between the indoor expansion valve 21 and the outdoor expansion valve 36.

(2) Details of Outdoor Heat Exchanger 34 Hereinafter, the details of the outdoor heat exchanger 34 according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 2 is a perspective view of the outdoor heat exchanger 34. FIG. 3 is an enlarged view of the first header portion 341 of the outdoor heat exchanger 34.

  The outdoor heat exchanger 34 has a substantially L shape in plan view, and mainly includes a first header part 341, a heat exchange part 342, and a second header part 345. Specifically, the outdoor heat exchanger 34 has a first header part 341 at one end in the longitudinal direction thereof, a second header part 345 at the other end, and the first header part 341 and the second header part 345. And a heat exchanging part 342 connecting the two.

(2-1) First header portion 341
The first header portion 341 is a copper pipe having a substantially cylindrical shape with a height h1 of 1.5 m, and is provided at the left end portion of the outdoor heat exchanger 34. The first header portion 341 is connected to a gas refrigerant pipe 30 a extending from the compressor 33 and allows a gas refrigerant to flow in.

  The first header portion 341 has a lower conduction structure 341a through which the gas refrigerant flows from the vicinity of the lower end thereof. More specifically, the lower conductive structure 341a of the first header portion 341 has an opening formed at the lower end portion of the first header portion 341, and is connected to and communicates with the gas refrigerant pipe 30a through the opening, thereby lowering the lower end thereof. It is a structure that allows refrigerant to flow in the vicinity. That is, in this embodiment, the lower conduction structure 341a of the first header portion 341 is configured by an opening formed at the lower end of the first header portion 341 and a gas refrigerant pipe 30a connected through the opening. Yes.

  A plurality of openings are formed in a column in the side surface portion of the first header part 341 on the heat exchanging part 342 side, and the first header part 341 is connected to heat transfer tubes 343a to 343j described later through the openings. And communicated.

  The 1st header part 341 functions as an inlet of a gas refrigerant at the time of air_conditionaing | cooling operation, makes gas refrigerant flow in from the gas refrigerant piping 30a, and distribute | circulates the gas refrigerant which flowed in to the heat exchanger tubes 343a-343j. That is, the first header portion 341 serves as a distribution pipe that distributes the gas refrigerant to the heat transfer tubes 343a to 343j.

  The first header part 341 is provided with a temperature sensor 5 that detects the temperature of the refrigerant in the first header part 341. Specifically, the temperature sensor 5 is mainly composed of a thermocouple, and is disposed near the lower end of the first header portion 341. The temperature sensor 5 is connected to the outdoor control unit via a compensation lead (not shown), and transmits detected temperature information to the outdoor control unit. Thereby, the outdoor control unit measures the temperature of the refrigerant in the first header part 341, and determines whether liquid refrigerant is accumulated in the first header part 341 according to the measured temperature state. More specifically, the outdoor control unit determines that the liquid refrigerant has accumulated in the vicinity of the lower end of the first header portion 341 when the measured temperature continuously falls below a predetermined threshold value.

(2-2) Heat exchange unit 342
The heat exchanging part 342 causes the refrigerant to flow in via the first header part 341, exchanges heat between the refrigerant and the outdoor air, and flows it out to the second header part 345. The heat exchange part 342 has a substantially L shape in a plan view, and includes a plurality of heat transfer tubes 343a to 343j (hereinafter, heat transfer tubes 343a to 343j are collectively referred to as heat transfer tubes 343) and a plurality of heat transfer fins 344. It is configured.

(2-2-1) Heat transfer tube 343
The heat transfer tube 343 is, for example, a copper tube having a substantially circular cross section in the vertical direction. The heat transfer tube 343 is disposed between the first header portion 341 and the second header portion 345 and circulates the refrigerant. Specifically, the heat transfer tube 343 is connected so as to be orthogonal to the first header portion 341 at one end thereof, extends in a horizontal direction while being curved, and is orthogonal to the second header portion 345 at the other end. It is connected. As shown in FIG. 3, the heat transfer tubes 343 are configured with a total of 10 tubes, and the top heat transfer tubes 343 a to 343 b, 343 c, 343 d, 343 e, 343 f, 343 g, 343 h, 343 i, and 343 j are arranged in the vertical direction. Are arranged in parallel. Hereinafter, for convenience of explanation, a communication portion between the lowermost heat transfer tube 343j and the first header portion 341 is referred to as a lowermost communication portion CP1.

  Here, the gas refrigerant flowing into the first header portion 341 during the cooling operation is first introduced into the vicinity of the lowermost communication portion CP1 by the lower conduction structure 341a of the first header portion 341. For this reason, the gas refrigerant flowing into the first header portion 341 is distributed in descending order from the lowest heat transfer tube 343j of the heat transfer tubes 343, and the lower the heat transfer tubes 343, the lower the refrigerant flows. The flow rate and flow rate are increased.

(2-2-2) Heat transfer fin 344
The heat transfer fins 344 are fins formed from an aluminum plate material, and promote heat exchange between the refrigerant circulating in the heat transfer tube 343 and the outdoor air. A large number of heat transfer fins 344 are arranged in parallel in a direction perpendicular to the heat transfer tubes 343 and extend through the heat transfer tubes 343 from the one end to the other end in the longitudinal direction of the heat transfer tubes 343. By arranging the heat transfer fins 344 as described above, an air flow path is formed between adjacent fins, and outdoor air passes through the air flow path. Thereby, the refrigerant | coolant which distribute | circulates the inside of the heat exchanger tube 343, and outdoor air are heat-exchanged efficiently.

(2-3) Second header portion 345
Similar to the first header part 341, the second header part 345 is a copper pipe having a substantially cylindrical shape with a height h1 of 1.5 m. The second header portion 345 has an opening formed at a lower end portion thereof, and is connected to and communicates with the liquid refrigerant pipe 30b through the opening. In addition, a plurality of openings are formed in a column in the side surface portion of the second header part 345 on the heat exchanging part 342 side, and the second header part is connected to and communicates with the heat transfer tube 343 through the opening. .

The second header portion 345 functions as an outlet for the liquid refrigerant during the cooling operation, and causes the liquid refrigerant to flow from the heat transfer pipe 343 to join and flow out to the liquid refrigerant pipe 30b. That is, the second header part 345 serves as a collecting pipe that joins the liquid refrigerant flowing out of the heat transfer pipe 343. As described above, since the second header portion 345 has a height h1 of 1.5 m, the refrigerant flowing pressure increases as it approaches the lower end from the upper end of the second header portion 345. ing. For example, when the upper end vicinity is 20.0kgf / cm ² is to increase to approximately 20.15kgf / cm ² in the vicinity of the lower end, about 0.15kgf / cm ² pressure is increased.

(3) Flow of Refrigerant Hereinafter, the flow of the refrigerant during the cooling operation in the air conditioning system 1 will be described.

  When the cooling operation is started in the air conditioning system 1 and the indoor fan 23, the compressor 33, and the outdoor fan 35 are driven, the low-pressure gas refrigerant is sucked into the compressor 33 and compressed to become a high-pressure gas refrigerant. Thereafter, the high-pressure gas refrigerant is sent to the outdoor heat exchanger 34, exchanges heat with the outdoor air supplied by the outdoor fan 35, and condenses to become a high-pressure liquid refrigerant.

  Specifically, the gas refrigerant flows into the first header part 341 via the gas refrigerant pipe 30a and is distributed to the heat transfer tubes 343a to 343j. The gas refrigerant distributed to the heat transfer tubes 343a to 343j exchanges heat with outdoor air in the process of flowing to the second header portion 345, and condenses into high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows out from the heat transfer tubes 343a to 343j to the second header portion 345, joins them, and is sent to the indoor unit 2.

  Here, as described above, in the second header portion 345, the pressure at which the liquid refrigerant flows increases as the portion is closer to the lower end than to the upper end. This tendency is caused by an increase in the degree of supercooling because the flow rate of the gas refrigerant flowing into the heat transfer pipe 343 is small, for example, in a situation where only one of the indoor units 2a, 2b, 2c is in cooling operation. The more the space ratio occupied by the liquid refrigerant flowing out from the heat transfer tube 343 is more remarkable.

  In such a case, for example, when the flow rate of the gas refrigerant flowing into the heat transfer tube 343 communicating in the vicinity of the lower end of the first header portion 341 decreases, the liquid refrigerant flowing through the second header portion 345 inside the heat transfer tube 343. It may happen that the liquid refrigerant stagnates without securing a flow rate that exceeds the pressure of the liquid. In such a situation, the liquid refrigerant stagnating in the heat transfer tube 343 and the refrigerating machine oil of the compressor 33 flowing into the heat transfer pipe 343 are compatible, and the refrigerating machine oil is not recovered to the compressor 33. An event that accumulates inside the heat transfer tube 343 is induced. As a result, the heat exchanger performance of the outdoor heat exchanger 34 is deteriorated due to the attachment of the refrigeration oil to the heat transfer pipe 343, and the compressor 33 becomes insufficient in the compressor 33 and the operation of the compressor 33 becomes unstable. .

  However, in the present embodiment, the lower conductive structure 341a is provided in the first header portion 341, so that the flow rate of the gas refrigerant that flows into the heat transfer tubes closer to the lower of the heat transfer tubes 343a to 343j increases. Since it is configured, it is difficult for liquid refrigerant to stagnate in the heat transfer tube 343 without ensuring a flow rate that exceeds the pressure of the liquid refrigerant flowing through the second header portion 345.

  The high-pressure liquid refrigerant sent to the indoor unit 2 via the liquid-refrigerant communication pipe 4b is decompressed by the indoor expansion valve 21 to near the suction pressure of the compressor 33, and is a low-pressure gas-liquid two-phase refrigerant. And is sent to the indoor heat exchanger 22, where it exchanges heat with indoor air in the indoor heat exchanger 22 and evaporates to become a low-pressure gas refrigerant. This low-pressure gas refrigerant is sent to the outdoor unit 3 via the gas refrigerant communication pipe 4 a and flows into the accumulator 32. Then, the low-pressure gas refrigerant flowing into the accumulator 32 is again sucked into the compressor 33.

  Thus, the outdoor heat exchanger 34 functions as a refrigerant condenser, and the indoor heat exchanger 22 functions as a refrigerant evaporator.

(4) Features (4-1)
In the above embodiment, the first header part 341 of the outdoor heat exchanger 34 has the lower conduction structure 341a that allows the gas refrigerant to flow into the inner space of the first header part 341 in the vicinity of the lowermost communication part CP1. . Thereby, at the time of air_conditionaing | cooling operation, the flow volume of a refrigerant | coolant increases from the heat exchanger tube 343j of the lowest step among the some heat exchanger tubes 343a-343j in descending order. For this reason, in the heat transfer tube 343 connected in the vicinity of the lower end of the first header part 341, it is difficult to occur that a flow rate that exceeds the pressure of the liquid refrigerant flowing through the second header part 345 cannot be secured. The refrigerant and the refrigeration oil are less likely to stagnate in the heat transfer tube 343 and flow easily. As a result, the performance deterioration of the outdoor heat exchanger 34 is suppressed.

(4-2)
In the above-described embodiment, the lower conductive structure 341a of the first header portion 341 includes the gas refrigerant pipe 30a that is connected to the vicinity of the lower end of the first header portion 341 and into which the gas refrigerant flows. Thereby, at the time of air_conditionaing | cooling operation, the flow volume of a refrigerant | coolant further increases in descending order from the heat exchanger tube 343j of the lowest stage among several heat exchanger tubes 343a-343j. For this reason, the refrigerant and the refrigeration oil are more unlikely to stagnate in the heat transfer tube 343 and flow easily.

(5) Modification (5-1) Modification 1A
In the said embodiment, although the outdoor heat exchanger 34 was applied to what is called a multi air conditioning system which has several indoor unit 2a, 2b, and 2c, it is not limited to this. For example, instead of the multi-air conditioning system, for example, the present invention may be applied to an air conditioning system having only one indoor unit. Moreover, you may apply not in an air conditioning system but in other refrigeration apparatuses, such as a heat pump water heater, and may be applied to apparatuses other than a refrigeration apparatus.

  Moreover, in the said embodiment, although R32 was employ | adopted as a refrigerant | coolant, it is not limited to this, For example, other refrigerant | coolants, such as R410A, can be selected suitably.

(5-2) Modification 1B
In the said embodiment, although the thing made from copper was employ | adopted as the gas refrigerant piping 30a, the liquid refrigerant piping 30b, the 1st header part 341, and the 2nd header part 345, it is not limited to this. For example, you may employ | adopt what was shape | molded with other metals, such as an aluminum alloy.

(5-3) Modification 1C
In the above embodiment, a positive displacement compressor is employed as the compressor 33, but the present invention is not limited to this, and the model can be appropriately selected. Moreover, in the said embodiment, although the compressor 33 was only one, it is not limited to this, Even if two or more compressors are connected in parallel according to the number of connected indoor units, etc. good. Moreover, in the said embodiment, although polyvinyl ether was employ | adopted as refrigerating machine oil which lubricates each sliding part of the compressor 33, it is not limited to this, You may employ | adopt another kind of refrigerating machine oil.

(5-4) Modification 1D
In the above embodiment, the outdoor heat exchanger 34 is L-shaped in plan view, but is not limited to this, and can be changed as appropriate. For example, it may be U-shaped in plan view.

  Moreover, although the copper pipe | tube with the substantially circular cross section of the perpendicular direction was employ | adopted as the heat exchanger tube 343, it is not limited to this, It can change suitably. For example, a flat multi-hole tube made of an aluminum alloy may be used as the heat transfer tube 343. In the present embodiment, a total of ten heat transfer tubes 343, 343a to 343j, are provided, but the number of heat transfer tubes is not limited to this, and any number may be used.

  The outdoor heat exchanger 34 has the first header part 341 at one end in the longitudinal direction and the second header part 345 at the other end, but the first header part 341 and the second header part 345 The position is not limited to this, and can be changed as appropriate. Moreover, the magnitude | size and the length of the perpendicular direction of a 1st header part and a 2nd header part do not need to be the same, and may differ. Further, the outdoor heat exchanger 34 may be configured to omit the second header portion 345 and allow the refrigerant to flow out through a flow divider or the like.

(5-5) Modification 1E
In the said embodiment, the lower conduction | electrical_connection structure 341a of the 1st header part 341 was comprised by the opening formed in the lower end of the 1st header part 341, and the gas refrigerant piping 30a connected through the said opening. However, it is not limited to this. For example, the opening is not necessarily formed at the lower end of the first header portion 341, and may be formed in the vicinity of the lowermost communication portion CP1.

(5-6) Modification 1F
Further, the lower conductive structure 341a of the first header portion 341 in the above embodiment may be configured like a lower conductive structure 341b shown in FIG.

  In FIG. 4, an opening is formed at the upper end rather than the lower end of the first header part 341, and the gas refrigerant pipe 30 a extends through the opening to the vicinity of the lowermost communication part CP <b> 1. That is, the lower conductive structure 341b shown in FIG. 4 includes a gas refrigerant pipe 30a that passes through a portion near the upper end of the first header portion 341 and extends to the vicinity of the lower end of the first header portion 341, and into which the gas refrigerant flows.

  Accordingly, during the cooling operation, the gas refrigerant flowing into the first header portion 341 from the gas refrigerant pipe 30a first flows into the vicinity of the lowermost communication portion CP1, and the lowermost step among the plurality of heat transfer tubes 343a to 343j. The flow rate of the refrigerant further increases in descending order from the heat transfer tube 343j. For this reason, in the heat transfer tube 343 connected in the vicinity of the lower end of the first header part 341, it is further less likely that a flow rate that exceeds the pressure of the liquid refrigerant flowing through the second header part 345 cannot be ensured. The refrigerant and the refrigerating machine oil are more unlikely to stagnate in the heat transfer tube 343 and flow more easily.

(5-7) Modification 1G
Further, the lower conductive structure 341a of the first header portion 341 in the above embodiment may be configured like a lower conductive structure 341c shown in FIG.

  In FIG. 5, an opening is formed not at the lower end of the first header portion 341 but at the upper end, and communicates with and communicates with the gas refrigerant pipe 30 a through the opening, and extends from the upper end to the vicinity of the lower end inside the first header portion 341. A partition wall 346 is provided. The partition 346 partitions the first header part 341 into a first space SP1 and a second space SP2. The first space SP1 and the second space SP2 are opposed to each other with the partition wall 346 interposed therebetween, and the second space SP2 communicates with the heat transfer tube 343. Since the lower end of the partition wall 346 is located above the lower end of the first header part 341, the first space SP1 and the second space SP2 communicate with each other in the vicinity of the lower end of the first header part 341. The refrigerant flows through the first space SP1 and the second space SP2.

  In the lower conduction structure 341c shown in FIG. 5, the partition wall 346 as described above is arranged, so that the gas refrigerant flowing into the first header portion 341 from the gas refrigerant pipe 30a first enters the first space SP1 during the cooling operation. It flows into the second space SP2 in the vicinity of the lower end of the first header portion 341, and flows into the vicinity of the lowermost communication portion CP1. Thus, the gas refrigerant is distributed in descending order from the lowest heat transfer tube 343j among the plurality of heat transfer tubes 343a to 343j, and the flow rate is increased.

  That is, the lower conductive structure 341c shown in FIG. 5 extends from the upper end to the vicinity of the lower end along the vertical direction in the internal space of the first header portion 341, and the space from the upper end of the internal space of the first header portion 341 to the vicinity of the lower end is extended. A partition 346 is included to separate the first space SP1 and the second space SP2. Thereby, among the plurality of heat transfer tubes 343a to 343j, the flow rate of the refrigerant further increases in descending order from the lowest heat transfer tube 343j. For this reason, in the heat transfer tube 343 connected in the vicinity of the lower end of the first header part 341, it is further less likely that a flow rate that exceeds the pressure of the liquid refrigerant flowing through the second header part 345 cannot be ensured. The refrigerant and the refrigerating machine oil are more unlikely to stagnate in the heat transfer tube 343 and flow more easily.

(5-8) Modification 1H
Further, a plurality of slits SL1 may be formed in the partition 346 of the lower conductive structure 341c as in the lower conductive structure 341c ′ illustrated in FIG. As shown in FIG. 6, the slit SL1 is formed in the partition wall 346, so that the outdoor heat exchanger 34 can be applied to the air conditioning system 10 capable of cooling operation and heating operation illustrated in FIG. Hereinafter, the air conditioning system 10 and the lower conduction structure 341c ′ illustrated in FIG. 6 will be described.

  FIG. 7 is a schematic configuration diagram of the air conditioning system 10. The air conditioning system 10 is an apparatus used for air conditioning in a room such as a building by performing a vapor compression refrigeration cycle operation. The air conditioning system 10 has substantially the same configuration as the air conditioning system 1 except that the four-way switching valve 31 is provided.

  The four-way switching valve 31 is a valve for switching the flow direction of the refrigerant. During the cooling operation, the outdoor heat exchanger 34 is used as a refrigerant condenser compressed by the compressor 33 and the indoor heat exchanger 22. To function as an evaporator for the refrigerant condensed in the outdoor heat exchanger 34, the suction side of the compressor 33 and the indoor heat exchanger 22 are connected, and the discharge side of the compressor 33 and the outdoor heat exchanger 34 are connected. Connect. Further, the four-way switching valve 31 serves as a refrigerant condenser in which the indoor heat exchanger 22 is compressed by the compressor 33 and the outdoor heat exchanger 34 is condensed in the indoor heat exchanger 22 during the heating operation. In order to function as an evaporator, the suction side of the compressor 33 and the outdoor heat exchanger 34 are connected, and the discharge side of the compressor 33 and the indoor heat exchanger 22 are connected.

  When the heating operation is started in the air conditioning system 10 and the indoor fan 23, the compressor 33, and the outdoor fan 35 are driven, the low-pressure gas refrigerant is sucked into the compressor 33 and compressed to become a high-pressure gas refrigerant. It is sent to the indoor unit 2 via the valve 31 and the gas refrigerant communication pipe 4a. When the high-pressure gas refrigerant sent to the indoor unit 2 is condensed by exchanging heat with the indoor air in the indoor heat exchanger 22, the high-pressure gas refrigerant passes through the indoor expansion valve 21. Further, the pressure is reduced according to the opening degree of the indoor expansion valve 21.

  The refrigerant that has passed through the indoor expansion valve 21 is sent to the outdoor unit 3 via the liquid refrigerant communication pipe 4b, and further decompressed via the outdoor expansion valve 36, and then flows into the outdoor heat exchanger 34. . The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 34 exchanges heat with the outdoor air supplied by the outdoor fan 35 to evaporate into a low-pressure gas refrigerant. And flows into the accumulator 32. Then, the low-pressure gas refrigerant flowing into the accumulator 32 is again sucked into the compressor 33.

  Thus, during the heating operation, the indoor heat exchanger 22 functions as a refrigerant condenser, and the outdoor heat exchanger 34 functions as a refrigerant evaporator. That is, the 1st header part 341 at the time of heating operation functions as an exit of a gas refrigerant, makes gas refrigerant flow in from heat exchanger tubes 343a-343j, and makes the gas refrigerant which flowed in flow out into gas refrigerant piping 30a. That is, the first header part 341 serves as a collecting pipe that joins the gas refrigerant flowing out from the heat transfer pipes 343a to 343j during the heating operation. In addition, the second header portion 345 during the heating operation functions as an inlet for the refrigerant, allows the liquid refrigerant to flow from the liquid refrigerant pipe 30 b, and distributes the flowed liquid refrigerant to the heat transfer tube 343. That is, the second header part 345 serves as a distribution pipe that distributes the liquid refrigerant to the heat transfer pipes 343 during the heating operation.

  In the lower conduction structure 341c ′ shown in FIG. 6, the liquid back phenomenon in which the liquid refrigerant flows into the compressor 33 during the heating operation is suppressed. Specifically, when heating operation is performed in the air conditioning system 10 (when the outdoor heat exchanger 34 is used as an evaporator), liquid refrigerant is accumulated in the first header portion 341 or the heat transfer pipe 343 at the start of the operation. Even in this case, the liquid refrigerant is prevented from flowing out into the gas refrigerant pipe 30 a at a stretch and flowing into the compressor 33.

  That is, if the state where the air conditioning system 10 is not operated continues for a long time, the gas refrigerant in the outdoor heat exchanger 34 condenses to become liquid refrigerant, and the liquid refrigerant accumulates in the first header portion 341 and the first space SP1. The communication space with the second space SP2 may be blocked. When the heating operation is started in such a situation, for example, in the lower conductive structure 341c shown in FIG. 5, the liquid refrigerant flows into the gas refrigerant pipe 30a at a stretch and flows into the accumulator 32. However, the flow rate of the flowing liquid refrigerant is the accumulator. In the case of exceeding the holding amount of 32, it is assumed that the liquid back phenomenon in which the liquid refrigerant flows into the compressor 33 is caused. When such a liquid back phenomenon occurs, the compressor 33 is likely to be damaged, and thus it is necessary to suppress the liquid back phenomenon for safety reasons.

  Therefore, in the lower conductive structure 341c ′ shown in FIG. 6, a plurality of slits SL1 are formed in the partition wall 346 in order to suppress the liquid back phenomenon. Thereby, when heating operation is performed in the air conditioning system 10 (that is, when the outdoor heat exchanger 34 is used as an evaporator), liquid refrigerant accumulates in the first header portion 341 or the heat transfer pipe 343 and the first space SP1. Even if the communication space with the second space SP2 is blocked, the gas refrigerant flows from the second space SP2 to the first space SP1 through the slit SL1 formed in the partition wall 346 and flows out to the gas refrigerant pipe 30a. It is supposed to be. As a result, the liquid back phenomenon in which the liquid refrigerant flows into the compressor 33 is suppressed.

(5-9) Modification 1I
Moreover, you may comprise the 1st header part 341 in the said embodiment as shown in FIG. In the configuration shown in FIG. 8, openings are formed at the upper end and the lower end of the first header part 341, and are connected to and communicated with the gas refrigerant pipe 30 a through the opening, and the gas refrigerant starts from the upper end and the lower end of the first header part 341. Can flow in or out.

  More specifically, the gas refrigerant pipe 30a branches into a first gas refrigerant pipe 30a1 and a second gas refrigerant pipe 30a2, and the first gas refrigerant pipe 30a1 is connected to the opening at the upper end of the first header portion 341. Have been communicated. Further, the second gas refrigerant pipe 30a2 is connected to and communicated with the opening at the lower end of the first header portion 341. Note that the opening for connecting the second gas refrigerant pipe 30a2 is not necessarily formed at the lower end of the first header portion 341, and may be formed in the vicinity of the lowermost communication portion CP1.

  In the configuration shown in FIG. 8, the lower conductive structure 341 a includes a second gas refrigerant pipe 30 a 2 that is connected to the vicinity of the lower end of the first header portion 341 and into which the gas refrigerant flows. As a result, during the cooling operation, the gas refrigerant flowing into the first header portion 341 from the second gas refrigerant pipe 30a2 first flows into the vicinity of the lowermost communication portion CP1. Therefore, the flow rate of the gas refrigerant flowing into the lowest heat transfer tube 343j among the plurality of heat transfer tubes 343a to 343j is increased.

  In the configuration shown in FIG. 8, a first on-off valve 37 is provided in the first gas refrigerant pipe 30a1. The first opening / closing valve 37 is constituted by an electromagnetic valve, and switching between opening and closing is controlled by an outdoor control unit. By providing such a first on-off valve 37, when the liquid refrigerant is accumulated in the first header portion 341, the first on-off valve 37 is fully closed and only from the second gas refrigerant pipe 30a2. It is possible to control the gas refrigerant to flow in. As a result, the flow rate of the refrigerant is increased in descending order from the lowest heat transfer tube 343j among the plurality of heat transfer tubes 343a to 343j, so that the liquid refrigerant can flow toward the outlet side of the heat transfer tube 343.

  That is, in the configuration shown in FIG. 8, when the outdoor control unit determines that the liquid refrigerant has accumulated in the first header portion 341, the first on-off valve 37 is fully closed and the second gas refrigerant pipe 30a2 is used. It is possible to control to increase the inflow amount of the gas refrigerant. For this reason, even if liquid refrigerant accumulates in the first header part 341, the flow rate of the refrigerant is increased in descending order from the lowest heat transfer tube 343j among the plurality of heat transfer tubes 343a to 343j, and the outlet side of the heat transfer tube 343 ( The liquid refrigerant can be caused to flow to the second header portion 345 side). Therefore, the refrigerant and the refrigerating machine oil are more unlikely to stagnate in the heat transfer tube 343 and flow more easily.

  Moreover, according to the structure shown in FIG. 8, it becomes possible to apply the outdoor heat exchanger 34 in the air conditioning system 10 which can perform the cooling operation and heating operation shown in FIG. As described above, if the air conditioning system 10 is not operated for a long time, it is assumed that a liquid back phenomenon occurs. Therefore, in the configuration shown in FIG. 8, the first gas refrigerant pipe 30a1 is provided. Thereby, even if liquid refrigerant accumulates inside the 1st header part 341 or heat exchanger tube 343, gas refrigerant flows out from the 1st gas refrigerant piping 30a1.

  That is, in the configuration shown in FIG. 8, when the outdoor heat exchanger 34 is used as an evaporator, the first on-off valve 37 is fully opened and the gas refrigerant is controlled to flow out from the first gas refrigerant pipe 30a1. It is possible. For this reason, even if the liquid refrigerant is accumulated in the first header portion 341 or the heat transfer pipe 343, the liquid refrigerant is prevented from flowing out to the gas refrigerant pipe 30 through the second gas refrigerant pipe 30a2. Therefore, the liquid refrigerant is prevented from flowing into the compressor 33.

(5-10) Modification 1J
Further, as shown in FIG. 9, in the configuration shown in FIG. 8, a second on-off valve 38 may be provided in the second gas refrigerant pipe 30a2. The second on-off valve 38 in FIG. 9 is configured by an electromagnetic valve, like the first on-off valve 37, and the switching of the opening and closing is controlled by the outdoor control unit.

  Thus, by providing the 2nd on-off valve 38 in the 2nd gas refrigerant piping 30a2, the liquid back phenomenon at the time of heating operation can be suppressed more reliably in the air conditioning system 10.

  That is, as described above, it is assumed that the liquid back phenomenon occurs when the air conditioning system 10 is not operated for a long time. Therefore, in the configuration shown in FIG. 9, when the second on-off valve 38 is disposed in the second gas refrigerant pipe 30a2 and heating operation is performed (that is, when the outdoor heat exchanger 34 is used as an evaporator). The second on-off valve 38 is fully closed so that the gas refrigerant can be controlled to flow out only from the first gas refrigerant pipe 30a1. As a result, even if the liquid refrigerant is accumulated in the first header portion 341 or the heat transfer pipe 343, the liquid refrigerant is further reliably prevented from flowing out to the gas refrigerant pipe 30a through the second gas refrigerant pipe 30a2. Yes. Therefore, the liquid back phenomenon in which the liquid refrigerant flows into the compressor 33 is further reliably suppressed.

  The present invention is applicable to a heat exchanger.

1 Air Conditioning System 3 Outdoor Unit 30a Gas Refrigerant Pipe 30a1 First Gas Refrigerant Pipe 30a2 Second Gas Refrigerant Pipe 30b Liquid Refrigerant Pipe 34 Outdoor Heat Exchanger 341 First Header Portion 341a-c Lower Conducting Structure 342 Heat Exchanger 343j Heat Transfer Tube 343j Lowermost heat transfer tube 344 Heat transfer fin 345 Second header portion 346 Partition 37 First on-off valve 38 Second on-off valve 4 Refrigerant communication tube 5 Temperature sensor CP1 Lowermost-stage communication portion SL1 Slit SP1 First space SP2 Second space

Japanese Utility Model Publication No. 63-144554 Japanese Utility Model Publication No. 62-83154

Claims (7)

A heat exchanger (34) for condensing gas refrigerant to form liquid refrigerant and discharging it,
A cylindrical header portion (341) extending along the vertical direction and allowing the gas refrigerant to flow in;
A plurality of heat transfer tubes (343) communicating with the header portion and extending along the horizontal direction and arranged along the vertical direction;
A lower conductive structure (341a, 341b, 341c, 341c ′) for allowing the gas refrigerant to flow into the vicinity of the communication portion (CP1) between the header portion and the lowermost heat transfer tube (343j) in the internal space of the header portion; ,
Comprising
Heat exchanger (34). The lower conduction structure includes a refrigerant pipe (30a) that is connected to the vicinity of the lower end of the header part and allows the gas refrigerant to flow therein.
The heat exchanger according to claim 1. The lower conductive structure includes a refrigerant pipe (30a) that extends through the vicinity of the upper end of the header portion to the vicinity of the lower end of the header portion and allows the gas refrigerant to flow in.
The heat exchanger according to claim 1. The lower conductive structure is connected to a portion near the upper end of the header portion and is connected to a refrigerant pipe (30a) through which the gas refrigerant flows, and extends from the upper end to the vicinity of the lower end along the vertical direction in the internal space of the header portion. A partition wall (346) that divides the space from the upper end of the internal space to the vicinity of the lower end into the first space (SP1) and the second space (SP2),
The second space communicates with the plurality of heat transfer tubes,
The first space and the second space communicate with each other in the vicinity of the lower end of the header portion.
The heat exchanger according to claim 1. A plurality of slits (SL1) are formed in the partition wall.
The heat exchanger according to claim 4. An upper refrigerant pipe (30a1) connected to the vicinity of the upper end of the header portion and allowing the gas refrigerant to flow in or out;
A first on-off valve (37) disposed in the upper refrigerant pipe;
Further comprising
The lower conduction structure includes a lower refrigerant pipe (30a2) that is connected to the vicinity of the lower end of the header part and allows the gas refrigerant to flow in.
The heat exchanger according to claim 1. A second on-off valve (38) disposed in the lower refrigerant pipe;
The heat exchanger according to claim 6.

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