Air conditioning device

Abstract

This air conditioning device has a heat transfer pipe group composed of a first heat transfer pipe and a plurality of second heat transfer pipes, and comprises a heat source heat exchanger that radiates heat to air during a cooling operation and absorbs heat from air during a heating operation, the direction of refrigerant flowing through the heat source heat exchanger during a defrosting operation for melting frost adhering to the heat source heat exchanger during the heating operation being the same as the direction of the refrigerant flowing through the heat source heat exchanger during the heating operation, wherein: the air conditioning device comprises a temperature sensor that detects the temperature of the refrigerant, a control device that controls execution and stopping of the defrosting operation on the basis of the detected temperature obtained by the sensor, a merging part that allows the refrigerant flowing out from the first heat transfer pipe and the refrigerant flowing out from the plurality of second heat transfer pipes during the defrosting operation to be merged, and a connection part that is provided downstream of the refrigerant outlet of the first heat transfer pipe and upstream of the merging part in the flow of refrigerant during the defrosting operation; and the temperature sensor is provided to the connection part and is provided with a circulation-inhibiting structure that makes it more difficult for refrigerant to flow to the first heat transfer pipe than to the plurality of second heat transfer pipes during the defrosting operation.

Description

air conditioning equipment

[0001] The present disclosure relates to an air conditioner that utilizes a heat pump.

[0002] When an air conditioner using a heat pump performs heating operation, frost forms on the outdoor heat exchanger when the outdoor temperature is low, reducing heat transfer performance. To prevent this reduction in heat transfer performance, the air conditioner performs defrosting operation. Defrosting operation includes a so-called reverse cycle defrosting operation, in which the refrigerant circulates in the same direction as in cooling operation, as well as the defrosting operation disclosed in Patent Document 1.

[0003] In the air conditioner described in Patent Document 1, the discharge side of the compressor is connected to the refrigerant inlet side of the outdoor heat exchanger during heating operation via a solenoid valve. A defrost condition detector is provided on the refrigerant inlet pipe of the outdoor heat exchanger during heating operation to detect the pipe temperature. When the defrost condition detector detects that a defrost condition is met, the solenoid valve and expansion valve are opened, and high-temperature gas refrigerant discharged from the compressor enters the outdoor heat exchanger to melt the frost, and high-temperature refrigerant from the indoor heat exchanger also flows into the outdoor heat exchanger. When the defrost condition detector detects that the defrost condition is canceled, the system returns to the original heating operation. This defrost operation allows high-temperature gas refrigerant to be supplied to both the outdoor heat exchanger and the indoor heat exchanger, preventing discomfort to indoor occupants and shortening the defrost operation time.

[0004] Japanese Unexamined Patent Publication No. 129659 / 1983

[0005] In an air conditioner having a circuit configuration that performs a defrosting operation as disclosed in Patent Document 1, when a large amount of frost has formed on the outdoor heat exchanger, it is possible to shorten the defrosting time by flowing all of the high-temperature gas refrigerant discharged from the compressor into the outdoor heat exchanger. However, because the defrosting condition detector disclosed in Patent Document 1 detects the temperature of the piping on the inlet side of the outdoor heat exchanger during defrosting operation, this defrosting condition detector cannot accurately detect when the frost has melted. If the defrosting condition cannot be accurately detected, there is a risk that defrosting will be insufficient or that energy savings will be reduced due to excessive defrosting.

[0006] The present disclosure has been made against the background of the above-mentioned problems, and provides an air conditioning apparatus that can more accurately detect the end of defrosting in an air conditioning apparatus in which refrigerant flows in the same direction through a heat source heat exchanger to be defrosted during heating operation and defrosting operation.

[0007] The air conditioner according to the present disclosure includes a heat transfer tube group consisting of a first heat transfer tube and a plurality of second heat transfer tubes, and a heat source heat exchanger that radiates heat to air during cooling operation and absorbs heat from air during heating operation, wherein the direction of refrigerant flowing through the heat source heat exchanger during defrosting operation that melts frost that has adhered to the heat source heat exchanger during the heating operation is the same as the direction of refrigerant flowing through the heat source heat exchanger during the heating operation, and the air conditioner includes a temperature sensor that detects the temperature of the refrigerant, and a temperature sensor that detects the temperature of the refrigerant and controls the temperature sensor to detect the temperature of the refrigerant during the defrosting operation. a confluence section that combines the refrigerant flowing out of the first heat transfer tube and the refrigerant flowing out of the plurality of second heat transfer tubes during the defrosting operation; and a connection section that is provided downstream of the refrigerant outlet of the first heat transfer tube and upstream of the confluence section in the flow of refrigerant during the defrosting operation, wherein the temperature sensor is provided at the connection section and the system is provided with a flow obstruction structure that makes it more difficult for the refrigerant to flow through the first heat transfer tube than through each of the plurality of second heat transfer tubes during the defrosting operation.

[0008] According to the present disclosure, a temperature sensor used to control the termination of defrosting operation is provided downstream of the refrigerant outlet of the first heat transfer tube, which has a flow obstruction structure and where defrosting ends last, so that the end of defrosting can be detected more accurately.

[0009] 1. A refrigerant circuit diagram schematically showing an example configuration of an air conditioning apparatus according to Embodiment 1. FIG. 1 is a refrigerant circuit diagram schematically showing an example configuration of an air conditioning apparatus according to Modification 1 of Embodiment 1. FIG. 2 is a refrigerant circuit diagram schematically showing an example configuration of an air conditioning apparatus according to Modification 2 of Embodiment 1. FIG. 3 is a flowchart explaining the flow of defrosting operation of an air conditioning apparatus according to Embodiment 1. FIG. 4 is a diagram showing the structure of a heat source heat exchanger according to Embodiment 1. FIG. 5 is a diagram showing the structure of a heat source heat exchanger according to Embodiment 1. FIG. 6 is a cross-sectional schematic diagram of a second heat transfer tube according to Embodiment 1. FIG. 7 is a cross-sectional schematic diagram of a first example of a first heat transfer tube according to Embodiment 1. FIG. 8 is a cross-sectional schematic diagram of a second example of a first heat transfer tube according to Embodiment 1. FIG. 9 is a cross-sectional schematic diagram of a third example of a first heat transfer tube according to Embodiment 1. FIG. 11 is a cross-sectional schematic diagram of a converging header provided with a partition plate according to Embodiment 1. FIG. 12 is a front view of the partition plate of FIG. 11 according to Embodiment 1. FIG. 13 is an exploded perspective view of a stacked header provided with an inhibition portion according to Embodiment 1. FIG. 14 is a schematic diagram of a heat source heat exchanger according to Embodiment 2.

[0010] An air conditioning apparatus according to the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to the following embodiments and can be modified in various ways without departing from the spirit of the present disclosure. Furthermore, the present disclosure includes all possible combinations of the configurations shown in the following embodiments. The air conditioning apparatus shown in the drawings is an example of an apparatus to which the air conditioning apparatus of the present disclosure can be applied, and the air conditioning apparatus shown in the drawings does not limit the applicable apparatus to which the present disclosure can be applied. In each drawing, components with the same reference numerals are identical or equivalent, and this applies throughout the entire specification. In each drawing, the relative dimensional relationships or shapes of each component may differ from those in actuality.

[0011] Embodiment 1. Fig. 1 is a refrigerant circuit diagram that schematically illustrates an example configuration of an air conditioning apparatus according to Embodiment 1. The air conditioning apparatus 100 according to Embodiment 1 performs cooling operation, heating operation, and defrosting operation using a heat pump. The air conditioning apparatus 100 has an outdoor unit 10 and an indoor unit 11. The outdoor unit 10 is installed outside a space to be air-conditioned, for example, outdoors, and the indoor unit 11 is installed in the space to be air-conditioned. In Fig. 1, the flow of refrigerant during defrosting operation is indicated by solid arrows and dashed arrows.

[0012] The air conditioning apparatus 100 includes a compressor 1, a heat source heat exchanger 20, an expansion mechanism 3, a load heat exchanger 4, and a flow path switching valve 5, which are connected by refrigerant piping 12 to form a refrigerant circuit. A first point A between the compressor 1 and the flow path switching valve 5 is connected to a second point B between the heat source heat exchanger 20 and the expansion mechanism 3 by a bypass piping 6. A valve 7 is provided in the bypass piping 6. The air conditioning apparatus 100 also includes a temperature sensor 8 and a control device 9.

[0013] The compressor 1 draws refrigerant from a refrigerant pipe 12, compresses the drawn refrigerant, and discharges the compressed refrigerant into the refrigerant pipe 12. The compressor 1 is, for example, an inverter compressor whose capacity can be controlled by an inverter.

[0014] The flow path switching valve 5 is, for example, a four-way valve that switches the direction of refrigerant flow. The air conditioning apparatus 100 switches between heating operation / defrosting operation and cooling operation by switching the refrigerant flow direction using the flow path switching valve 5. In FIG. 1 , the arrows shown on the flow path switching valve 5 indicate the refrigerant flow paths during heating operation and defrosting operation. During heating operation and defrosting operation, the flow path switching valve 5 connects the discharge side of the compressor 1 to the load heat exchanger 4 and connects the suction side of the compressor 1 to the heat source heat exchanger 20. Note that, although not shown, during cooling operation, the flow path switching valve 5 connects the discharge side of the compressor 1 to the heat source heat exchanger 20 and connects the suction side of the compressor 1 to the load heat exchanger 4.

[0015] The heat source heat exchanger 20 exchanges heat between the refrigerant and air sent from an outdoor fan (not shown). The heat source heat exchanger 20 functions as a refrigerant evaporator during heating operation and as a refrigerant condenser during cooling operation and defrosting operation.

[0016] The expansion mechanism 3 reduces the pressure of the refrigerant and expands it. The expansion mechanism 3 is, for example, an electric expansion valve that can adjust the flow rate of the refrigerant.

[0017] The load heat exchanger 4 exchanges heat between the refrigerant and a fluid. The fluid may be, for example, air sent from an indoor fan (not shown) or antifreeze sent from a pump (not shown). The load heat exchanger 4 functions as a refrigerant condenser during heating operation and as a refrigerant evaporator during cooling operation.

[0018] The bypass pipe 6 is a flow path through which the refrigerant passes during defrosting operation. The bypass pipe 6 supplies the refrigerant discharged from the compressor 1 to the heat source heat exchanger 20.

[0019] The valve 7 is provided in the bypass pipe 6 and opens and closes the flow path of the refrigerant in the bypass pipe 6. The valve 7 may be a valve whose opening degree is adjustable.

[0020] The temperature sensor 8 is provided on the refrigerant outlet side of the heat source heat exchanger 20 during heating operation and defrosting operation. Note that the position of the temperature sensor 8 is shown schematically in FIG. 1 , and the specific arrangement of the temperature sensor 8 will be described later. The temperature sensor 8 is installed in a pipe through which the refrigerant passes, and detects the temperature of the pipe to detect the temperature of the refrigerant. The refrigerant temperature detected by the temperature sensor 8 is input to the control device 9.

[0021] The control device 9 controls the operating frequency of the compressor 1, the opening of the expansion mechanism 3, and the valve state of the flow path switching valve 5 based on operation instructions input from a remote controller (not shown) via wired or wireless communication. The control device 9 also detects the state of frost formation on the heat source heat exchanger 20 based on the refrigerant temperature input from the temperature sensor 8, and controls the open / close state of the valve 7 based on the detection result. The control device 9 is configured with dedicated hardware or a CPU (Central Processing Unit) that executes programs stored in memory.

[0022] The outdoor unit 10 includes a compressor 1, a flow path switching valve 5, a heat source heat exchanger 20, and a valve 7 inside a housing indicated by a dashed line square in Fig. 1. The indoor unit 11 includes an expansion mechanism 3 and a load heat exchanger 4 inside a housing indicated by a dashed line square in Fig. 1.

[0023] During cooling operation, the valve 7 is closed, and the refrigerant does not flow through the bypass piping 6. During cooling operation, the refrigerant discharged from the compressor 1 flows into the heat source heat exchanger 20. The refrigerant that flows into the heat source heat exchanger 20 exchanges heat with air and condenses. The refrigerant that flows out of the heat source heat exchanger 20 is reduced in pressure when passing through the expansion mechanism 3, and flows into the load heat exchanger 4. The refrigerant that flows into the load heat exchanger 4 exchanges heat with a fluid and evaporates. The fluid cooled by heat exchange in the load heat exchanger 4 is used to cool the space to be air-conditioned. The refrigerant that flows out of the load heat exchanger 4 is drawn into the compressor 1 via the flow path switching valve 5 and compressed.

[0024] During heating operation, the valve 7 is closed, and the refrigerant does not flow through the bypass piping 6. During heating operation, the refrigerant discharged from the compressor 1 flows into the load heat exchanger 4. The refrigerant that flows into the load heat exchanger 4 exchanges heat with the fluid supplied to the load heat exchanger 4 and condenses. The fluid heated by the heat exchange in the load heat exchanger 4 is used to heat the space to be air-conditioned. The refrigerant that flows out of the load heat exchanger 4 is decompressed while passing through the expansion mechanism 3, and flows into the heat source heat exchanger 20. The refrigerant that flows into the heat source heat exchanger 20 exchanges heat with the air and evaporates. The refrigerant that flows out of the heat source heat exchanger 20 is drawn into the compressor 1 via the flow path switching valve 5 and compressed.

[0025] In defrosting operation, valve 7 is in an open state, allowing refrigerant to flow through bypass piping 6. In defrosting operation, as shown in Fig. 1 , flow path switching valve 5 is in the same state as in heating operation. Defrosting operation is started when frost formation on heat source heat exchanger 20 is detected during heating operation. The defrosting operation in this embodiment includes a first defrosting operation in which a large amount of heat is used to melt frost on heat source heat exchanger 20, and a second defrosting operation in which a smaller amount of heat is used to melt frost than in the first defrosting operation.

[0026] In the first defrosting operation, the expansion mechanism 3 is closed, and the refrigerant cannot flow through the load heat exchanger 4. All of the high-temperature refrigerant discharged from the compressor 1 flows into the bypass piping 6 from the first point A, passes through the valve 7, and flows into the heat-source heat exchanger 20 via the second point B. The high-temperature refrigerant that has flowed into the heat-source heat exchanger 20 melts the frost that has adhered to the heat-source heat exchanger 20. In the first defrosting operation, the refrigerant discharged from the compressor 1 is supplied to the heat-source heat exchanger 20 without passing through the load heat exchanger 4, so that substantially all of the heat of the gas refrigerant can be used as latent heat for melting the frost. Therefore, in the first defrosting operation, the time required to melt the frost that has adhered to the heat-source heat exchanger 20 can be shortened compared to the second defrosting operation described below.

[0027] In the second defrosting operation, the expansion mechanism 3 is opened to an opening degree that allows refrigerant to flow. The high-temperature refrigerant discharged from the compressor 1 branches at a first point A, with one branch flowing into the load heat exchanger 4 via the flow path switching valve 5 and the other branch flowing into the bypass piping 6. The refrigerant that flows into the load heat exchanger 4 heats the fluid supplied to the load heat exchanger 4, thereby heating the air-conditioned space. The refrigerant that has undergone heat exchange in the load heat exchanger 4 drops in temperature and flows out as a low-temperature refrigerant. The other high-temperature refrigerant that flows into the bypass piping 6 passes through the valve 7 and merges with the low-temperature refrigerant that flows out of the load heat exchanger 4 at a second point B to become a medium-temperature refrigerant and flow into the heat-source heat exchanger 20. The medium-temperature refrigerant that flows into the heat-source heat exchanger 20 melts frost that has adhered to the heat-source heat exchanger 20. In the second defrosting operation, the defrosting operation can be performed while continuing the heating operation, which is less likely to impair the comfort of people in the air-conditioned space.

[0028] In both the first defrosting operation and the second defrosting operation of this embodiment, the direction of refrigerant flowing through the heat source heat exchanger 20 is the same as the direction of refrigerant flowing through the heat source heat exchanger 20 in heating operation. In this respect, the air conditioning apparatus 100 of this embodiment differs from an apparatus that performs a so-called reverse cycle defrosting operation in which the direction of refrigerant flowing through the heat source heat exchanger 20 is the same in defrosting operation and cooling operation.

[0029] Fig. 2 is a refrigerant circuit diagram that schematically illustrates an example configuration of an air conditioning apparatus according to Modification 1 of Embodiment 1. In the air conditioning apparatus 100 shown in Fig. 2, an expansion mechanism 3 is housed in the housing of an outdoor unit 10, which is indicated by a dashed dotted line. The rest of the configuration is the same as in Fig. 1.

[0030] FIG. 3 is a refrigerant circuit diagram schematically illustrating an example configuration of an air conditioner according to Modification 2 of Embodiment 1. The air conditioner 100 shown in FIG. 3 differs from that shown in FIG. 1 in the position of a first point A of the bypass piping 6. Specifically, the first point A is located downstream of the flow path switching valve 5 and upstream of the load heat exchanger 4 in the refrigerant flow direction during heating operation. During defrosting operation, the refrigerant discharged from the compressor 1 flows into the bypass piping 6 via the flow path switching valve 5 and the first point A, and then flows into the heat source heat exchanger 20 via the valve 7 and the second point B. The expansion mechanism 3 may be housed in the housing of the outdoor unit 10 as shown in FIG. 3, or may be housed in the housing of the indoor unit 11 as shown in FIG. 1.

[0031] The air conditioning apparatus 100 having the configuration shown in FIG. 2 or FIG. 3 can also perform the defrosting operation including the first defrosting operation and the second defrosting operation described above.

[0032] FIG. 4 is a flowchart illustrating the flow of the defrosting operation of the air conditioner according to the first embodiment. While the heating operation is in progress (step ST1), it is determined whether the defrosting condition for the heat-source heat exchanger 20 is met, i.e., whether frost has formed on the heat-source heat exchanger 20 (step ST2). In step ST2, the control device 9 determines whether frost has formed on the heat-source heat exchanger 20 based on the refrigerant temperature detected by the temperature sensor 8. The temperature sensor 8 is provided on the refrigerant outlet side of the heat-source heat exchanger 20 during the heating operation. The control device 9 determines whether frost has formed on the heat-source heat exchanger 20 by comparing the temperature of the refrigerant flowing out of the heat-source heat exchanger 20 with a frost threshold temperature. The frost threshold temperature is determined, for example, by taking into account the detection error of the temperature sensor 8 and zero degrees Celsius, which is the freezing point of water. If the defrosting condition is not met (step ST2: NO), the heating operation continues. If the defrosting condition is met (step ST2: YES), the defrosting operation is initiated (step ST3).

[0033] The defrosting operation is the first defrosting operation or the second defrosting operation described above, and the refrigerant is circulated as described above in each case. Whether the first defrosting operation or the second defrosting operation is to be performed may be determined in advance for each air conditioning apparatus 100, or may be selected based on a setting by the user.

[0034] During the defrosting operation, it is determined whether the defrosting condition has been released, i.e., whether the frost on the heat source heat exchanger 20 has melted (step ST4). In step ST4, the control device 9 determines whether the frost on the heat source heat exchanger 20 has melted based on the refrigerant temperature detected by the temperature sensor 8. The control device 9 determines whether frost has adhered to the heat source heat exchanger 20 by comparing the temperature of the refrigerant flowing out from the heat source heat exchanger 20 with a defrost threshold temperature. The defrost threshold temperature is a temperature determined, for example, by adding a detection error of the temperature sensor 8 to zero degrees Celsius, which is the melting point of water. If the defrosting condition has not been released (step ST4: NO), the defrosting operation continues. If the defrosting condition has been released (step ST4: YES), the defrosting operation is terminated (step ST5) and the system returns to the heating operation.

[0035] In this way, in this embodiment, cancellation of the defrosting condition is detected using one temperature sensor 8. The arrangement of the temperature sensor 8 and the structure of the heat source heat exchanger 20 that realize this function will be described below.

[0036] (Structure of Heat Source Heat Exchanger) Figure 5 is a diagram showing the structure of the heat source heat exchanger according to the first embodiment. The heat source heat exchanger 20 includes a heat transfer tube group consisting of a first heat transfer tube 21 and a plurality of second heat transfer tubes 22, a flow divider 23, a distribution header 24, a merging header 25, a main pipe 26, and a secondary pipe 27. Connected to the heat source heat exchanger 20 are an inlet pipe 13 through which a refrigerant flowing into the heat source heat exchanger 20 flows during heating operation and defrosting operation, and an outlet pipe 14 through which a refrigerant flowing out of the heat source heat exchanger 20 flows. The inlet pipe 13 and the outlet pipe 14 are part of the refrigerant pipe 12 shown in Figure 1. Note that the functions of the inlet pipe 13 and the outlet pipe 14 are reversed during cooling operation, but in the following description, references to the flow of refrigerant refer to the flow during heating operation and defrosting operation.

[0037] The first heat transfer tube 21 and the second heat transfer tube 22 are made of a metal such as copper or aluminum and have channels through which a refrigerant flows. The channel length L1 of the first heat transfer tube 21 and the channel length L2 of the second heat transfer tube 22 are the same. The first heat transfer tube 21 is the lowest heat transfer tube, and the second heat transfer tube 22 is all heat transfer tubes except for the first heat transfer tube 21. The first heat transfer tube 21 and the second heat transfer tube 22 are arranged so that their longitudinal axes coincide with the horizontal direction. A refrigerant inlet 211 at one end of the first heat transfer tube 21 and a refrigerant inlet 221 at one end of the second heat transfer tube 22 are connected to a distribution header 24. A refrigerant outlet 212 at the other end of the first heat transfer tube 21 and a refrigerant outlet 222 at the other end of the second heat transfer tube 22 are connected to a confluence header 25.

[0038] The flow divider 23 is a mechanism that divides the flow of the refrigerant flowing from the inlet pipe 13 into the heat source heat exchanger 20. The flow divider 23 has a plurality of flow dividing pipes 231, and the refrigerant flowing from the inlet pipe 13 is divided and flows into each of the plurality of flow dividing pipes 231, and then flows into the distribution header 24.

[0039] The distribution header 24 is a member that distributes the refrigerant to the first heat transfer tubes 21 and the plurality of second heat transfer tubes 22. The distribution header 24 is a hollow member arranged so that its longitudinal direction coincides with the vertical direction, and its interior is divided into multiple sections by partitions 241. Each space within the distribution header 24 that is divided by the partitions 241 is called a sub-space 242. There is a one-to-one correspondence between the sub-spaces 242 and the diversion tubes 231, and the refrigerant flowing out of one diversion tube 231 flows into one sub-space 242. A plurality of first heat transfer tubes 21 or second heat transfer tubes 22 are connected to the sub-space 242, and the refrigerant is distributed to the connected heat transfer tubes.

[0040] The confluence header 25 is disposed at a horizontal distance from the distribution header 24 and is a component that confluences the refrigerant that has flowed in from the second heat transfer tubes 22. The confluence header 25 is a hollow component disposed so that its longitudinal direction coincides with the vertical direction, and its interior is divided into two regions by a partition 251. One region separated by the partition 251 is referred to as a first region 252, and the other region is referred to as a second region 253. Only the first heat transfer tubes 21 are connected to the first region 252. All of the plurality of second heat transfer tubes 22 are connected to the second region 253.

[0041] The main pipe 26 is a pipe that connects the merging header 25 and the outflow pipe 14. One end of the main pipe 26 is connected to the second region 253 of the merging header 25. The refrigerant that has flowed from the second heat transfer pipe 22 into the second region 253 flows through the main pipe 26.

[0042] The secondary pipe 27 is a pipe that connects the first region 252 of the confluence header 25 to the main pipe 26. The refrigerant that flows from the first region 252 into the secondary pipe 27 flows through the secondary pipe 27 and into the main pipe 26. At a confluence point P shown in Fig. 5 , the refrigerant that flows out of the first heat transfer pipe 21 and the refrigerant that flows out of the second heat transfer pipe 22 are confluent.

[0043] The refrigerant that has joined at the joining point P flows through the main pipe 26 and into the outflow pipe 14 .

[0044] The temperature sensor 8 is provided in the secondary pipe 27, which is a connection portion provided downstream of the refrigerant outlet 212 of the first heat transfer pipe 21 and upstream of the junction P in the refrigerant flow during defrosting operation. The temperature sensor 8 detects the temperature of the refrigerant flowing through the secondary pipe 27. As will be described later, the heat source heat exchanger 20 is provided with a flow obstruction structure that makes it more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through each of the plurality of second heat transfer pipes 22 during defrosting operation. The first heat transfer pipe 21, through which the refrigerant flows more difficultly, can be said to be most difficult to defrost during defrosting operation compared to each of the second heat transfer pipes 22. By providing the temperature sensor 8 downstream of the first heat transfer pipe 21, it is possible to more accurately detect the release of the defrost condition.

[0045] Furthermore, the first region 252 to which the refrigerant outlet 212 of the first heat transfer tube 21 is connected is independent from the second region 253 to which the refrigerant outlet 222 of the second heat transfer tube 22 is connected, and only the refrigerant that has flowed through the first heat transfer tube 21 flows through the secondary tube 27. Therefore, the temperature sensor 8 provided in the secondary tube 27 can detect the temperature of the refrigerant that has flowed through the first heat transfer tube 21 without being affected by the temperature of the refrigerant that has flowed through the second heat transfer tube 22.

[0046] Figure 6 is a diagram showing the structure of a heat source heat exchanger according to embodiment 1. The heat source heat exchanger 20A is used in the air conditioning apparatus 100 in place of the heat source heat exchanger 20 shown in Figure 5. The heat source heat exchanger 20A includes a heat transfer tube group consisting of a first heat transfer tube 21 and a plurality of second heat transfer tubes 22, a first header 31, and a second header 32. The flow path length L1, which is the length of the flow path of the first heat transfer tube 21, and the flow path length L2, which is the length of the flow path of the second heat transfer tube 22, are all the same.

[0047] The first header 31 is a hollow member arranged so that its longitudinal direction coincides with the vertical direction, and its interior is divided into multiple sections by partitions 311. The first header 31 is a folded header that changes the direction of the refrigerant that flows in before it flows out. The spaces within the first header 31 divided by the partitions 311 are referred to as first regions 312 and second regions 313. The first region 312 is a region connected to the refrigerant outlets 212 of the first heat transfer tubes 21. The second regions 313 are regions other than the first region 312, and three second regions 313 are shown in FIG. 6. Although three second regions 313 are provided in FIG. 6, the number of partitions 311 and second regions 313 is not limited to the illustrated example. Each second region 313 is connected to one of the multiple second heat transfer tubes 22. Of the multiple second regions 313, the one located most downstream in the refrigerant flow during defrosting operation is referred to as the downstream region 313a. The inlet pipe 13 is connected to the second region 313, which is the most upstream region, and the outlet pipe 14 is connected to the downstream region 313a.

[0048] The second header 32 is a hollow member arranged so that its longitudinal direction coincides with the vertical direction, and its interior is divided into multiple sections by partitions 321. The second header 32 is a folded header that changes the direction of the refrigerant that flows in before it flows out. The spaces within the second header 32 that are divided by the partitions 321 are called sub-spaces 322. Although two sub-spaces 322 are provided in Figure 6, the number of partitions 321 and sub-spaces 322 is not limited to the example shown in the figure.

[0049] The partitions 311 and 321 are located at different heights in the vertical direction. The lower subspace 322 in FIG. 6 is positioned so as to overlap portions of the two lower second regions 313 in the vertical direction. The second-lowest second region 313 is positioned so as to overlap portions of the two subspaces 322 in the vertical direction. The refrigerant flowing from the inlet pipe 13 into the second region 313 flows from left to right in the second heat transfer tube 22, flows upward into the subspace 322, and flows back into the second heat transfer tube 22 from right to left in the vertical direction. The refrigerant repeatedly flows back and forth between the second region 313 and the subspace 322. The refrigerant inlet 211 of the first heat transfer tube 21 is connected to one of the upper subspaces 322. The refrigerant flowing into the first heat transfer tube 21 flows from right to left in the vertical direction, exits the refrigerant outlet 212, and flows into the first region 312.

[0050] The first region 312 and the downstream region 313a are connected by a connecting pipe 314. The connecting pipe 314 is a pipe that guides the refrigerant in the first region 312 to the downstream region 313a, which is connected to the outflow pipe 14. In the downstream region 313a, the refrigerant flowing out of the first heat transfer pipe 21 and the refrigerant flowing out of the second heat transfer pipe 22 join together and flow into the outflow pipe 14. That is, in the embodiment of Fig. 6, the downstream region 313a is a junction P that joins the refrigerant flowing out of the first heat transfer pipe 21 and the refrigerant flowing out of the plurality of second heat transfer pipes 22 during the defrosting operation.

[0051] The temperature sensor 8 is provided in a connecting pipe 314 that is provided downstream of the refrigerant outlet 212 of the first heat transfer pipe 21 and upstream of the downstream region 313a, which is the junction P, in the refrigerant flow during defrosting operation. The temperature sensor 8 detects the temperature of the refrigerant flowing through the connecting pipe 314. As will be described later, the heat source heat exchanger 20 is provided with a flow obstruction structure that makes it more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through each of the multiple second heat transfer pipes 22 during defrosting operation. The first heat transfer pipe 21, through which the refrigerant flows more difficultly, can be said to be most difficult to defrost during defrosting operation compared to each of the second heat transfer pipes 22. By providing the temperature sensor 8 downstream of the first heat transfer pipe 21, it is possible to more accurately detect whether a defrosting condition is met or not.

[0052] The connecting pipe 314 may connect the first region 312 to a portion of the outflow pipe 14. In this case, the connection point between the outflow pipe 14 and the connecting pipe 314 becomes the confluence P.

[0053] (Flow obstruction structure) The heat source heat exchangers 20, 20A of the present embodiment are provided with a flow obstruction structure that makes it more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through each of the plurality of second heat transfer pipes 22. Specific examples of the flow obstruction structure will be described below.

[0054] (First Aspect of Flow Impedance Structure) In a first aspect of the flow impedance structure, the value obtained by dividing the flow path length L1 of the first heat transfer tube 21 by the flow path cross-sectional area S1 of the first heat transfer tube 21 is greater than the value obtained by dividing the flow path length L2 of each of the plurality of second heat transfer tubes 22 by the flow path cross-sectional area S2 of the second heat transfer tube 22. In other words, this structure satisfies the relationship L1 / S1>L2 / S2. An example in which a flow impedance structure is provided on the first heat transfer tube 21, which makes it more difficult for the refrigerant to flow than the second heat transfer tube 22, is shown below.

[0055] FIG. 7 is a schematic cross-sectional view of a second heat transfer tube according to the first embodiment. FIG. 7 shows a cross section perpendicular to the flow direction of the refrigerant in the second heat transfer tube 22. The second heat transfer tube 22 is a flat tube having a flat outer wall 223. The interior of the outer wall 223 is hollow, and spaces are separated by one or more partition walls 224. The spaces separated by the partition walls 224 are referred to as flow paths 225. The refrigerant flows through these flow paths 225. The flow path cross-sectional area S2 of the second heat transfer tube 22 is the sum of the cross-sectional areas of the multiple flow paths 225 in FIG. 7. Note that FIG. 7 shows an example in which seven flow paths 225 are formed by six partition walls 224, but the number of flow paths 225 is not limited to the illustrated example.

[0056] Fig. 8 is a cross-sectional schematic diagram of a first example of a first heat transfer tube according to the first embodiment. Fig. 8 shows a cross section perpendicular to the flow direction of the refrigerant in the first heat transfer tube 21. The first heat transfer tube 21 is a flat tube having a flat outer wall 213. The inside of the outer wall 213 is hollow, and spaces are separated by one or more partition walls 214. The spaces separated by the partition walls 214 are referred to as flow paths 215. The refrigerant flows through these flow paths 215. The flow path cross-sectional area S1 of the first heat transfer tube 21 is the sum of the cross-sectional areas of the multiple flow paths 215 in Fig. 8.

[0057] 8, the shape and size of the outer wall 213 are the same as those of the outer wall 223 of the second heat transfer tube 22 in FIG. 7, and the cross-sectional area of ​​each of the multiple flow paths 215 is the same as that of the corresponding flow path 225. However, the number of flow paths 215 is smaller than the number of flow paths 225 of the second heat transfer tube 22. By increasing the cross-sectional area of ​​the partition walls 214 in the cross-sectional area of ​​the first heat transfer tube 21, the flow path cross-sectional area S1 of the first heat transfer tube 21 is made smaller than the flow path cross-sectional area S2 of the second heat transfer tube 22.

[0058] FIG. 9 is a cross-sectional schematic diagram of a second example of a first heat transfer tube according to the first embodiment. The basic configuration of the first heat transfer tube 21 is as described in FIG. 8 . In the example of FIG. 9 , the shape and size of the outer wall 213 are the same as those of the outer wall 223 of the second heat transfer tube 22 in FIG. 7 , and the number of flow paths 215 is the same as the number of flow paths 225 of the second heat transfer tube 22. However, for at least some of the multiple flow paths 215, the cross-sectional area of ​​each flow path 215 is smaller than the cross-sectional area of ​​each corresponding flow path 225. With this configuration, the flow path cross-sectional area S1 of the first heat transfer tube 21 is smaller than the flow path cross-sectional area S2 of the second heat transfer tube 22.

[0059] Fig. 10 is a cross-sectional schematic diagram of a third example of a first heat transfer tube according to embodiment 1. The basic configuration of the first heat transfer tube 21 is as described in Fig. 8 . In the example of Fig. 10 , the width of the outer wall 213 is smaller than the width of the outer wall 223 of the second heat transfer tube 22 in Fig. 7 , and the number of flow paths 215 is smaller than the number of flow paths 225 of the second heat transfer tube 22. With this configuration, the flow path cross-sectional area S1 of the first heat transfer tube 21 is smaller than the flow path cross-sectional area S2 of the second heat transfer tube 22.

[0060] 8 to 10, the flow path length L1 and the flow path length L2 satisfy the relationship L1 / S1>L2 / S2, making it more difficult for the refrigerant to flow through the first heat transfer tube 21 than through the second heat transfer tube 22.

[0061] (Second embodiment of the flow obstruction structure) The second embodiment of the flow obstruction structure is an example in which a flow obstruction structure is provided in either or both of the distribution header 24 and the merging header 25 in the heat source heat exchanger 20, and in either or both of the first header 31 and the second header 32 in the heat source heat exchanger 20A.

[0062] Fig. 11 is a cross-sectional schematic diagram of a confluence header provided with a partition plate according to embodiment 1. Fig. 11 shows a longitudinal cross section of the confluence header 25 parallel to the flow paths of the first heat transfer tube 21 and the second heat transfer tube 22. Fig. 12 is a front view of the partition plate of Fig. 11 according to embodiment 1. Here, an example will be described in which a flow obstruction structure is provided in the confluence header 25 described in Fig. 5.

[0063] A partition plate 28 is provided within the confluence header 25. The partition plate 28 is a plate having a flat surface that extends vertically, i.e., in a direction intersecting the outflow direction of the refrigerant from the first heat transfer tube 21 and the second heat transfer tube 22. The partition plate 28 is provided so as to divide the inside of the confluence header 25 into an upstream side and a downstream side in the outflow direction of the refrigerant from the first heat transfer tube 21 and the second heat transfer tube 22. The partition plate 28 has an opening 281 that communicates with the first heat transfer tube 21 or the second heat transfer tube 22.

[0064] 12 , an inhibiting portion 282 is provided in the opening 281 that communicates with the first heat transfer tube 21 below the partition 251. The inhibiting portion 282 is a member that covers a portion of the downstream side of the refrigerant outlet 212 (see FIG. 11 ) of the first heat transfer tube 21. In contrast, no inhibiting portion 282 is provided in the opening 281 that communicates with the second heat transfer tube 22 above the partition 251. By providing the partition plate 28 with such an inhibiting portion 282, the outflow of refrigerant from the first heat transfer tube 21 is prevented, thereby making it more difficult for the refrigerant to flow through the first heat transfer tube 21 than through the second heat transfer tube 22.

[0065] 12 shows an example in which the confluence header 25 of the heat source heat exchanger 20 shown in FIG. 5 is provided with a partition plate 28 having an inhibition portion 282, but the distribution header 24 may also be provided with a partition plate 28 having an inhibition portion 282. In this case, the inhibition portion 282 is disposed upstream of the refrigerant inlet 211 of the first heat transfer tube 21. This prevents the refrigerant from flowing into the first heat transfer tube 21, making it more difficult for the refrigerant to flow through the first heat transfer tube 21 than through the second heat transfer tube 22. Furthermore, the confluence header 25 and the distribution header 24 may both be provided with partition plates 28 having inhibition portions 282.

[0066] 6 , a partition plate 28 having an inhibition portion 282 can be provided in either or both of the first header 31 and the second header 32. When the partition plate 28 is provided in the first header 31, the inhibition portion 282 is disposed downstream of the refrigerant outlet 212 of the first heat transfer tube 21. When the partition plate 28 is provided in the second header 32, the inhibition portion 282 is disposed upstream of the refrigerant inlet 211 of the first heat transfer tube 21.

[0067] In this way, by arranging the inhibition portion 282 upstream of the refrigerant inlet 211 of the first heat transfer tube 21 and / or downstream of the refrigerant outlet 212, it is possible to make it more difficult for the refrigerant to flow through the first heat transfer tube 21 than through the second heat transfer tube 22. In this embodiment, the first heat transfer tube 21 and the second heat transfer tube 22 may both be flat tubes of the same structure, or may be flat tubes as described in the first embodiment of the flow inhibition structure.

[0068] 13 is an exploded perspective view of a stack header provided with an inhibition portion according to embodiment 1. The stack header 40 shown in FIG. 13 is used as the distribution header 24, the merging header 25, the first header 31, or the second header 32.

[0069] The stacked header 40 is formed by stacking, for example, a plurality of rectangular plate-shaped bodies. In the example of FIG. 13 , a first plate-shaped body 41, a second plate-shaped body 42, a third plate-shaped body 43, and a fourth plate-shaped body 44 are stacked. The first plate-shaped body 41, the second plate-shaped body 42, the third plate-shaped body 43, and the fourth plate-shaped body 44 are formed with openings 411, 421, 431, and 441, respectively, which are refrigerant flow passages. The shapes of the openings 411, 421, 431, and 441 are not limited to the illustrated example. The first heat transfer tube 21 or the second heat transfer tube 22 is inserted into each of the plurality of openings 441 of the fourth plate-shaped body 44. In the example of FIG. 13 , the first heat transfer tube 21 is arranged at the bottom of the plurality of heat transfer tubes, but the arrangement of the first heat transfer tube 21 is not limited to the example of FIG. 13 .

[0070] An inhibiting portion 45 is provided in the opening 441 of the fourth plate-like body 44 connected to the first heat transfer tube 21 at a position facing the first heat transfer tube 21. The inhibiting portion 45 is provided at either or both of the refrigerant inlet 211 and the refrigerant outlet 212 of the first heat transfer tube 21. By providing such an inhibiting portion 45, it is possible to make it more difficult for the refrigerant to flow through the first heat transfer tube 21 than through the second heat transfer tube 22.

[0071] (Third Aspect of Flow Obstruction Structure) An obstacle may be provided in the flow path of the secondary pipe 27 shown in Fig. 5 to make it more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through the second heat transfer pipe 22, or the flow path cross-sectional area of ​​the secondary pipe 27 may be reduced so that it is more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through the second heat transfer pipe 22. Furthermore, among the multiple branch pipes 231 of the flow diverter 23 shown in Fig. 5, the flow path cross-sectional area of ​​the branch pipe 231 upstream of the first heat transfer pipe 21 may be made smaller than the flow path cross-sectional area of ​​the branch pipe 231 upstream of the second heat transfer pipe 22. In this case, the distribution header 24 shown in Fig. 5 is provided with a sub-space 242 to which only the first heat transfer pipe 21 is connected. This configuration also makes it more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through the second heat transfer pipe 22.

[0072] An obstacle may be provided in the flow path of the connecting pipe 314 shown in Figure 6 to make it more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through the second heat transfer pipe 22, or the flow path cross-sectional area of ​​the connecting pipe 314 may be reduced so that it is more difficult for the refrigerant to flow through the first heat transfer pipe 21 than through the second heat transfer pipe 22.

[0073] Embodiment 2. In Embodiment 1, the heat source heat exchangers 20, 20A were described that include a first heat transfer tube 21 and a second heat transfer tube 22 that are flat tubes, but in this embodiment, a heat source heat exchanger 20B that includes a first heat transfer tube 51 and a second heat transfer tube 52 that are circular tubes will be described. The heat source heat exchanger 20B is used in the air conditioning apparatus 100 in place of the heat source heat exchanger 20 shown in Figures 1 to 3. The defrosting operation shown in Figure 4 is also applied to this embodiment.

[0074] 14 and 15 are schematic diagrams of a heat source heat exchanger according to embodiment 2. The heat source heat exchanger 20B includes a heat transfer tube group consisting of a first heat transfer tube 51 and a plurality of second heat transfer tubes 52, a heat dissipation fin 53, a junction header 54, a flow divider 55, and a connection portion 56. Note that, in order to avoid complication of the drawing, only one second heat transfer tube 52 is shown in Fig. 14, but other second heat transfer tubes 52 are provided above and below the illustrated second heat transfer tube 52.

[0075] The first heat transfer pipe 51 and the second heat transfer pipe 52 are circular pipes made of a metal such as copper or aluminum, and have a flow path therein through which a refrigerant flows. A refrigerant inlet 511 at one end of the first heat transfer pipe 51 is connected to one of the shunt pipes 551 of the flow shunt 55, and a refrigerant outlet 512 at the other end of the first heat transfer pipe 51 is connected to the merging header 54. The first heat transfer pipe 51 has alternating straight portions 513 extending linearly and U-shaped folded portions 514. As a result, the first heat transfer pipe 51 forms a flow path for the refrigerant that flows while folding back and forth on the left and right sides of the page in FIG. 14 .

[0076] A refrigerant inlet 521 at one end of the second heat transfer pipe 52 is connected to one of the flow dividing pipes 551 of the flow divider 55, and a refrigerant outlet 522 at the other end of the second heat transfer pipe 52 is connected to the merging header 54. The second heat transfer pipe 52 has alternating straight portions 523 extending linearly and U-shaped folded portions 524. As a result, the second heat transfer pipe 52 forms a flow path for the refrigerant that flows while folding back and forth on the page of FIG.

[0077] The length of the first heat transfer tube 51 is longer than the length of the second heat transfer tube 52. When the flow path cross-sectional area of ​​the first heat transfer tube 51 is the same as or smaller than the flow path cross-sectional area of ​​the second heat transfer tube 52, the value obtained by dividing the flow path length of the first heat transfer tube 51 by the flow path cross-sectional area of ​​the first heat transfer tube is greater than the value obtained by dividing the flow path length of each of the multiple second heat transfer tubes by the flow path cross-sectional area of ​​the second heat transfer tube. This configuration is the flow obstruction structure of this embodiment. This makes it more difficult for the refrigerant to flow toward the first heat transfer tube 51 than toward the second heat transfer tube 52.

[0078] The plurality of heat dissipation fins 53 are joined to the outer surfaces of the first heat transfer pipe 51 and the second heat transfer pipe 52. The heat dissipation fins 53 are made of, for example, aluminum. Note that the heat dissipation fins 53 do not necessarily have to be provided.

[0079] The confluence header 54 confluences the refrigerant flowing out from the refrigerant outlet 512 of the first heat transfer tube 51 and the refrigerant outlet 522 of the second heat transfer tube 52. The refrigerant that has been confluenced in the confluence header 54 flows out into the outflow pipe 14.

[0080] The flow divider 55 is a mechanism that divides the flow of refrigerant flowing from the inlet pipe 13 into the heat source heat exchanger 20B. The flow divider 55 has the same number of flow divider pipes 551 as the total number of the first heat transfer pipes 51 and the plurality of second heat transfer pipes 52. Each of the plurality of flow divider pipes 551 is connected to the first heat transfer pipe 51 or the plurality of second heat transfer pipes 52. The refrigerant that flows into the flow divider 55 from the inlet pipe 13 passes through the flow divider pipe 551 and flows into the first heat transfer pipe 51 or the second heat transfer pipe 52.

[0081] The connection portion 56 is a pipe that connects the refrigerant outlet 512 of the first heat transfer pipe 51 and the junction header 54 .

[0082] The temperature sensor 8 is provided at a connection 56 that is provided downstream of the refrigerant outlet 512 of the first heat transfer tube 51 and upstream of the junction header 54, which is a junction P that joins the refrigerant from the first heat transfer tube 51 and the refrigerant from the second heat transfer tube 52, in the refrigerant flow during defrosting operation. The temperature sensor 8 detects the temperature of the refrigerant flowing at the connection 56. As described above, the first heat transfer tube 51, through which the refrigerant flows more slowly than the second heat transfer tube 52, is the least susceptible to defrosting during defrosting operation compared to the second heat transfer tubes 22. By providing the temperature sensor 8 downstream of the first heat transfer tube 51, it is possible to more accurately detect whether a defrosting condition is met or not.

[0083] In this embodiment, the number of diverter pipes 551 in the flow diverter 55 is equal to the total number of refrigerant outlets 512 of the first heat transfer pipe 51 and the refrigerant outlets 522 of the multiple second heat transfer pipes 52. That is, the refrigerant flowing through one diverter pipe 551 flows through one first heat transfer pipe 51 or one second heat transfer pipe 52 without merging or branching along the way. Therefore, the refrigerant temperature detected by the temperature sensor 8 downstream of the refrigerant outlet 512 of the first heat transfer pipe 51 reflects the temperature of the refrigerant in the first heat transfer pipe 51, where the refrigerant is in a difficult-to-flow state. If the number of diverter pipes 551 is different from the total number of refrigerant outlets 512 and refrigerant outlets 522, that is, if a path for merging or branching the refrigerant is provided along one or both of the first heat transfer pipes 51 and the second heat transfer pipe 52, significant refrigerant imbalance may occur at the merging or branching points. If significant refrigerant flow deviation occurs, a path other than the refrigerant path where temperature sensor 8 is installed becomes the path that is least likely to be defrosted, making it impossible for temperature sensor 8 to accurately detect whether the defrost condition has been met or not. However, according to this embodiment, such a problem does not occur, and the establishment and cancellation of the defrost condition can be detected more accurately based on the refrigerant temperature detected by temperature sensor 8.

[0084] As described above, the air conditioning apparatus 100 of the first and second embodiments includes a heat transfer tube group consisting of a first heat transfer tube and a plurality of second heat transfer tubes, and includes heat source heat exchangers 20, 20A, and 20B that radiate heat to air during cooling operation and absorb heat from air during heating operation. The air conditioning apparatus 100 includes a junction P that merges the refrigerant flowing out of the first heat transfer tube and the refrigerant flowing out of the plurality of second heat transfer tubes during defrosting operation, and a connection portion that is located downstream of the refrigerant outlet of the first heat transfer tube and upstream of the junction P in the refrigerant flow during defrosting operation. The connection part is provided with a temperature sensor 8 that detects the temperature of the refrigerant, and a control device 9 controls the stopping of the defrosting operation based on the temperature detected by this temperature sensor 8. Furthermore, a flow obstruction structure is provided in the first heat transfer pipe relative to each of the plurality of second heat transfer pipes to make it more difficult for the refrigerant to flow during the defrosting operation.

[0085] The first heat transfer tube, which has a flow obstruction structure and through which the refrigerant does not flow easily during defrosting operation, is less susceptible to defrosting than the second heat transfer tube, and defrosting ends last. The temperature sensor 8, which is used to control the termination of the defrosting operation, is provided downstream of the refrigerant outlet of this first heat transfer tube, so the end of defrosting can be detected more accurately.

[0086] As shown in Figures 5, 13, and 14, the first heat transfer tube is preferably located at the lowest position in the heat transfer tube group. Because melted frost falls due to gravity, water adheres to the lowest heat transfer tube, making it more likely to frost the next time heating operation is started. Therefore, by locating the first heat transfer tube at the lowest position, it is possible to detect a frosted state earlier. However, because the provision of the flow obstruction structure described above can make it difficult for the refrigerant to flow through the first heat transfer tube, the first heat transfer tube does not necessarily have to be located at the lowest position.

[0087] 5 may be applied to the heat-source heat exchanger 20B of embodiment 2. The structure of the first header 31 and the arrangement of the temperature sensors 8 of FIG. 6 may be applied to the heat-source heat exchanger 20B of embodiment 2. The structure of the merging header 54 and the arrangement of the temperature sensors 8 of FIG. 14 may be applied to the heat-source heat exchanger 20 or the heat-source heat exchanger 20A of embodiment 1.

[0088] In the first and second embodiments, the air conditioning apparatus 100 is described as performing cooling operation, heating operation, and defrosting operation, but the air conditioning apparatus 100 may also perform only heating operation and defrosting operation.

[0089] REFERENCE SIGNS LIST 1 Compressor, 3 Expansion mechanism, 4 Load heat exchanger, 5 Flow path switching valve, 6 Bypass piping, 7 Valve, 8 Temperature sensor, 9 Control device, 10 Outdoor unit, 11 Indoor unit, 12 Refrigerant piping, 13 Inlet piping, 14 Outlet piping, 20 Heat source heat exchanger, 20A Heat source heat exchanger, 20B Heat source heat exchanger, 21 First heat transfer pipe, 22 Second heat transfer pipe, 23 Divider, 24 Distribution header, 25 Merging header, 26 Main pipe, 27 Secondary pipe, 28 Partition plate, 31 First header, 32 Second header, 40 Stacked header, 41 First plate-shaped body, 42 Second plate-shaped body, 43 Third plate-shaped body, 44 Fourth plate-shaped body, 45 Inhibition portion, 51 First heat transfer pipe, 52 Second heat transfer pipe, 53 Heat radiation fin, 54 Merging header, 55 Flow divider, 56 Connection portion, 100 Air conditioner, 211 Refrigerant inlet, 212 Refrigerant outlet, 213 Outer wall, 214 Partition wall, 215 Flow path, 221 Refrigerant inlet, 222 Refrigerant outlet, 223 Outer wall, 224 Partition wall, 225 Flow path, 231 Flow dividing pipe, 241 Partition, 242 Sub-space, 251 Partition, 252 First region, 253 Second region, 281 Opening, 282 Blocking portion, 311 Partition, 312 First region, 313 Second region, 313a Downstream region, 314 Connecting pipe, 321 Partition, 322 Sub-space, 411 Opening, 421 Opening, 431 Opening, 441 Opening, 511 Refrigerant inlet, 512 Refrigerant outlet, 513 Straight portion, 514 Turned portion, 521 Refrigerant inlet, 522 refrigerant outlet, 523 straight section, 524 turning section, 551 dividing pipe.

Claims

1. An air conditioner having a heat source heat exchanger including a heat transfer tube group composed of a first heat transfer tube and a plurality of second heat transfer tubes, radiating heat to air during cooling operation and absorbing heat from air during heating operation, wherein during a defrosting operation for melting frost adhering to the heat source heat exchanger during the heating operation, a direction of a refrigerant flowing through the heat source heat exchanger is the same as a direction of the refrigerant flowing through the heat source heat exchanger during the heating operation, the air conditioner comprising: a temperature sensor for detecting a temperature of the refrigerant; a control device for controlling a stop of the defrosting operation based on a detected temperature of the temperature sensor; a merging portion for merging the refrigerant flowing out of the first heat transfer tube and the refrigerant flowing out of the plurality of second heat transfer tubes during the defrosting operation; and a connection portion provided downstream of a refrigerant outlet of the first heat transfer tube and upstream of the merging portion in a flow of the refrigerant during the defrosting operation, wherein the temperature sensor is provided at the connection portion, and the air conditioner comprising a flow resistance structure for making the refrigerant less likely to flow through the first heat transfer tube than through each of the plurality of second heat transfer tubes during the defrosting operation.

2. The air conditioner according to claim 1, wherein the flow resistance structure includes a structure in which a value obtained by dividing a flow path length of the first heat transfer tube by a flow path cross-sectional area of the first heat transfer tube is larger than a value obtained by dividing a flow path length of each of the plurality of second heat transfer tubes by a flow path cross-sectional area of the second heat transfer tube.

3. The air conditioner according to claim 1 or 2, wherein the flow resistance structure includes an inhibiting portion for inhibiting either or both of an outflow of the refrigerant from the first heat transfer tube and an inflow of the refrigerant into the first heat transfer tube during the defrosting operation.

4. The air conditioner according to any one of claims 1 to 3, further comprising a merging header to which the heat transfer tube group is connected, wherein the inside of the merging header is partitioned into a first region to which the first heat transfer tube is connected and a second region to which the plurality of second heat transfer tubes are connected, and the connection portion is a pipe connecting the first region and the merging portion.

5. The heat transfer tube group is connected and includes a folded header with an interior partitioned into a plurality of regions. The plurality of regions include a first region to which the first heat transfer tube is connected, and a downstream region to which a part of the plurality of second heat transfer tubes is connected and which is the most downstream region inside the folded header in the refrigerant flow during the defrosting operation. During the defrosting operation, refrigerant flows in the same direction through the first heat transfer tube and the second heat transfer tube connected to the downstream region. The confluence part is the downstream region, and the connection part is a pipe that communicates the first region and the downstream region. The air conditioner according to any one of claims 1 to 3.

6. The confluence part is a confluence header, and the connection part is a pipe that connects the refrigerant outlet of the first heat transfer tube and the confluence header. The air conditioner according to any one of claims 1 to 3.

7. The temperature sensor is one temperature sensor. The air conditioner according to any one of claims 1 to 6.

8. A refrigerant circuit having a compressor, the heat source heat exchanger, an expansion mechanism, and a load heat exchanger, a bypass pipe connecting a first point downstream of the compressor and upstream of the load heat exchanger and a second point downstream of the expansion mechanism and upstream of the heat source heat exchanger in the refrigerant flow during the heating operation, and a valve provided in the bypass pipe and being in an open state during the defrosting operation. The air conditioner according to any one of claims 1 to 7.

Images