Heat exchanger, outdoor unit, and refrigeration cycle device

Abstract

The present invention is provided with: a plurality of heat exchange units, each of which is connected to a lower header on the underside and includes a refrigerant inlet / outlet tube whereby a refrigerant in an external refrigerant tube can flow in / out; and a connection tube which connects a heat exchange unit serving as a main heat exchange unit that exchanges heat between air and the refrigerant and that condenses the refrigerant and a heat exchange unit serving as a supercooling heat exchange unit that exchanges heat between air and the refrigerant passing through the main heat exchange unit and that supercools the refrigerant passing through the main heat exchange unit. The supercooling heat exchange unit includes a non-connection region where a heat transfer tube is not connected to one end on the top surface of the lower header. The refrigerant inlet / outlet tube is connected to the non-connection region. The refrigerant inlet / outlet tube on the refrigerant outflow side of the main heat exchange unit and the refrigerant inlet / outlet tube on the refrigerant inflow side of the supercooling heat exchange unit can be connected by the connection tube when condensation occurs on the main heat exchange unit.

Description

Heat exchanger, outdoor unit and refrigeration cycle device

[0001] The disclosed technique relates to a heat exchanger, an outdoor unit, and a refrigeration cycle device, and in particular to a heat exchanger having a header that serves as a refrigerant distributor.

[0002] In recent years, in order to reduce the amount of refrigerant used and improve the performance of heat exchangers, the heat transfer tubes in heat exchangers for air conditioners have been made thinner. As the heat transfer tubes become thinner, the number of branches in heat exchangers increases to suppress increases in refrigerant pressure loss. To accommodate this multi-branch distribution, heat exchangers have been developed that use header-type refrigerant distributors, which have horizontally long headers that serve as refrigerant distributors and vertically long headers (see, for example, Patent Document 1).

[0003] JP 2010-107103 A

[0004] In a heat exchanger having a header with refrigerant inlet and outlet pipes connected vertically, when a high-temperature gaseous refrigerant flows through the heat transfer pipes while condensing, the liquefied refrigerant flows at a slower rate through the heat transfer pipes. In a heat exchanger having upper and lower headers, the refrigerant is subject to gravity, and the difference in flow rate reduces the heat exchange performance of the heat exchanger. In particular, in a heat exchanger having a main heat exchange section that condenses the refrigerant through heat exchange and a subcooling section that subcools the condensed refrigerant, the heat exchange performance may be reduced depending on the connection configuration of the pipes connecting the main heat exchange section and the subcooling section.

[0005] Therefore, an object of the present invention is to provide a heat exchanger, an outdoor unit, and a refrigeration cycle device that can solve the above-mentioned problems and improve heat exchange performance.

[0006] The heat exchanger according to this disclosure comprises a pair of headers arranged at a distance from each other in the vertical direction and through which a refrigerant passes, a plurality of heat transfer tubes connected in a row at intervals along the longitudinal direction of the pair of headers and having internal flow paths through which the refrigerant flows, a plurality of heat exchange sections connected to the lower header of the pair of headers and having refrigerant inlet and outlet pipes through which refrigerant in an external refrigerant piping flows in and out, a heat exchange section which serves as a main heat exchange section that exchanges heat between air and the refrigerant and condenses the refrigerant, and a heat exchange section which serves as a supercooling heat exchange section that exchanges heat between the refrigerant that has passed through the main heat exchange section and air and supercools the refrigerant that has passed through the main heat exchange section, the supercooling heat exchange section having an unconnected region at one end on the top surface of the lower header where the heat transfer tubes are not connected, the refrigerant inlet and outlet pipes being connected in the unconnected region, and the connecting pipe connecting the refrigerant inlet and outlet pipe on the refrigerant outflow side of the main heat exchange section to the refrigerant inlet and outlet pipe on the refrigerant inlet and outlet side of the supercooling heat exchange section when condensation occurs in the main heat exchange section.

[0007] An outdoor unit according to the present disclosure includes the heat exchanger according to the present disclosure as an outdoor heat exchanger.

[0008] The refrigeration cycle device according to the present disclosure includes the outdoor unit according to the present disclosure.

[0009] According to this disclosure, the lower header has refrigerant inlet and outlet pipes connected from the top surface, and the refrigerant inlet and outlet pipes on the refrigerant outlet side of the main heat exchange section and the refrigerant inlet and outlet pipes on the refrigerant inlet side of the subcooling heat exchange section are connected by connecting pipes, thereby improving heat exchange performance without obstructing the air flow path on the upstream side.

[0010] 1 is a diagram illustrating the configuration of an air conditioning apparatus according to Embodiment 1. FIG. 2 is a diagram illustrating a heat exchanger 1000 according to Embodiment 1. FIG. 3 is a diagram illustrating the relationship between the stage ratio R and heat exchange performance according to Embodiment 1. FIG. 4 is a diagram illustrating a part of a cross section of a heat exchanger 1000 according to Embodiment 2 when viewed along the Y direction. FIG. 5 is a diagram illustrating a part of a cross section of a heat exchanger 1000 according to Embodiment 2 when viewed along the X direction. FIG. 6 is a diagram illustrating corrugated fins 1500 in a heat exchange section 1010 according to Embodiment 3. FIG. 7 is a diagram illustrating the arrangement of an outdoor heat exchanger 230 in an outdoor unit 200 according to Embodiment 4. FIG. 8 is a diagram illustrating the arrangement of an outdoor heat exchanger 230 in an outdoor unit 200 according to Embodiment 5.

[0011] A heat exchanger, an outdoor unit, and a refrigeration cycle apparatus according to embodiments will be described below with reference to the drawings. In the following drawings, components with the same reference numerals are identical or equivalent and will be common throughout the following embodiments. The dimensional relationships between components in the drawings may differ from those in reality. Furthermore, in cross-sectional views, hatching is omitted in some views and devices for ease of viewing. The configurations of components shown throughout the specification are merely illustrative and are not limited to those described in the specification. In particular, the combinations of components are not limited to those in each embodiment, and components described in other embodiments may be applied to other embodiments. Furthermore, the levels of pressure and temperature are not determined in relation to absolute values, but are determined relatively based on the state, operation, etc. of the device. Furthermore, when multiple similar devices are distinguished by subscripts, the subscripts may be omitted if there is no need to distinguish or identify them.

[0012] Embodiment 1. <Configuration of Air Conditioning Apparatus> Fig. 1 is a diagram showing the configuration of an air conditioning apparatus according to Embodiment 1. Here, the air conditioning apparatus will be described as an example of a refrigeration cycle apparatus having a heat exchanger according to Embodiment 1.

[0013] As shown in FIG. 1 , the air conditioning apparatus of the first embodiment has an outdoor unit 200, an indoor unit 100, and two refrigerant pipes 300. The outdoor unit 200 is a unit having a compressor 210, a four-way valve 220, and an outdoor heat exchanger 230 as its components. The indoor unit 100 is a unit having an indoor heat exchanger 110 and an expansion valve 120 as its components. The components inside the outdoor unit 200 and the components inside the indoor unit 100 are connected by refrigerant pipes 300, forming a refrigerant circuit in which a refrigerant, a fluid that transports heat, circulates. Here, the air conditioning apparatus of the first embodiment has one outdoor unit 200 and one indoor unit 100 connected by pipes. However, the number of connected units is not limited to this.

[0014] The indoor unit 100 includes an indoor heat exchanger 110, an expansion valve 120, and an indoor fan 130. The indoor heat exchanger 110 and the expansion valve 120 are connected by piping within the indoor unit 100. The expansion valve 120, such as a throttling device, reduces the pressure of the refrigerant to expand it. If the expansion valve 120 is configured as an electronic expansion valve, for example, it adjusts its opening based on instructions from a control device (not shown). The indoor heat exchanger 110 exchanges heat between the refrigerant and the indoor air that is the space to be air-conditioned. For example, during heating operation, the indoor heat exchanger 110 functions as a condenser, condensing and liquefying the refrigerant. During cooling operation, the indoor heat exchanger 110 functions as an evaporator, evaporating and vaporizing the refrigerant. The indoor fan 130 passes indoor air through the indoor heat exchanger 110 and supplies the air that has passed through the indoor heat exchanger 110 into the room.

[0015] The outdoor unit 200 of the first embodiment has a compressor 210, a four-way valve 220, an outdoor heat exchanger 230, and an accumulator 240 as components that constitute a refrigerant circuit. These components are connected by piping inside the outdoor unit 200. The outdoor unit 200 also has an outdoor fan 250. The compressor 210 compresses and discharges the drawn refrigerant. The compressor 210 is, for example, a scroll compressor, a reciprocating compressor, or a vane compressor. Although not particularly limited, the capacity of the compressor 210 can be changed by arbitrarily changing the drive frequency using, for example, an inverter circuit or the like.

[0016] The four-way valve 220, which serves as a flow path switching device, is a valve that switches the flow of refrigerant between cooling operation and heating operation, for example. During heating operation, the four-way valve 220 connects the discharge side of the compressor 210 to the indoor heat exchanger 110 and connects the suction side of the compressor 210 to the outdoor heat exchanger 230. During cooling operation, the four-way valve 220 connects the discharge side of the compressor 210 to the outdoor heat exchanger 230 and connects the suction side of the compressor 210 to the indoor heat exchanger 110. While the four-way valve 220 is used here as an example, the flow path switching device is not limited to this. The flow path switching device may also be a device that combines multiple two-way valves, for example. The accumulator 240 is installed on the suction side of the compressor 210. The accumulator 240 allows a gaseous refrigerant (hereinafter referred to as a gas refrigerant) to pass through and stores a liquid refrigerant (hereinafter referred to as a liquid refrigerant).

[0017] The outdoor heat exchanger 230 exchanges heat between the refrigerant and outdoor air. For the outdoor heat exchanger 230, the refrigerant serves as a fluid heat exchange medium. Here, the outdoor heat exchanger 230 of the first embodiment functions as an evaporator during heating operation, evaporating and vaporizing the refrigerant. Meanwhile, the outdoor heat exchanger 230 functions as a condenser and subcooler during cooling operation, condensing and liquefying the refrigerant to perform subcooling. The outdoor heat exchanger 230 of the first embodiment includes one or more heat exchangers 1000, each of which includes a heat exchange section 1010 that serves as a main heat exchange section 1011 and a heat exchange section 1010 that serves as a subcooling heat exchange section 1012, as described below. The outdoor fan 250, when driven, sends air from outside the outdoor unit 200 to the outdoor unit 200, passing it through the outdoor heat exchanger 230 and forming a flow of air that flows out of the outdoor unit 200.

[0018] <Operation of the Air Conditioner> Next, the operation of each device in the air conditioner will be described based on the flow of refrigerant. First, the operation of each device in the refrigerant circuit during heating operation will be described based on the flow of refrigerant. The solid arrows in FIG. 1 indicate the flow of refrigerant during heating operation. High-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the indoor heat exchanger 110. While passing through the indoor heat exchanger 110, the gas refrigerant condenses and liquefies by, for example, exchanging heat with the air in the space to be air-conditioned. The condensed and liquefied refrigerant passes through the expansion valve 120. The refrigerant is decompressed as it passes through the expansion valve 120. The refrigerant, decompressed by the expansion valve 120 and brought to a gas-liquid two-phase state, passes through the outdoor heat exchanger 230. In the outdoor heat exchanger 230, the refrigerant passes through the subcooling heat exchanger 1012 and then the main heat exchanger 1011 in that order. Then, in the outdoor heat exchanger 230, the refrigerant evaporates by exchanging heat with the outdoor air sent from the outdoor fan 250, and the gaseous refrigerant passes through the four-way valve 220 and the accumulator 240, and is again drawn into the compressor 210. In this way, the refrigerant in the air conditioner circulates to perform air conditioning related to heating.

[0019] Next, cooling operation will be described. The dotted arrows in FIG. 1 indicate the flow of refrigerant during cooling operation. High-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the outdoor heat exchanger 230. In the outdoor heat exchanger 230, the refrigerant passes through the main heat exchanger 1011 of the heat exchanger 1000 (described later) and condenses and liquefies by exchanging heat with outdoor air supplied by the outdoor fan 250. The liquefied refrigerant then passes through the subcooling heat exchanger 1012 of the heat exchanger 1000 (described later) and is subcooled by exchanging heat with outdoor air supplied by the outdoor fan 250. The subcooled refrigerant passes through the expansion valve 120. Here, the refrigerant is decompressed as it passes through the expansion valve 120, becoming a two-phase gas-liquid state. The refrigerant decompressed and in a two-phase gas-liquid state by the expansion valve 120 passes through the indoor heat exchanger 110. Then, in the indoor heat exchanger 110, the refrigerant evaporates, for example, by exchanging heat with the air in the space to be air-conditioned, and becomes a gas refrigerant. The refrigerant passes through the four-way valve 220 and is sucked back into the compressor 210. In this way, the refrigerant in the air conditioner circulates to perform air conditioning related to cooling.

[0020] <Configuration of Heat Exchanger 1000> Fig. 2 is a diagram illustrating the heat exchanger 1000 according to the first embodiment. Hereinafter, the up-down direction in the heat exchanger 1000 is referred to as the Z direction (height direction or gravity direction). The direction perpendicular to the Z direction is referred to as the horizontal direction. Furthermore, a certain direction in the horizontal direction is referred to as the X direction (vertical-horizontal direction), and the direction perpendicular to the X direction is referred to as the Y direction (horizontal-vertical direction).

[0021] As described above, the outdoor heat exchanger 230 according to the first embodiment includes one or more heat exchangers 1000. In the heat exchanger 1000 shown in FIG. 2, a heat exchanger 1010 serving as a main heat exchanger 1011 and a heat exchanger 1010 serving as a subcooling heat exchanger 1012 are connected by a connecting pipe 1020. The heat exchanger 1010 (the main heat exchanger 1011 and the subcooling heat exchanger 1012) exchanges heat between the refrigerant and the air. The connecting pipe 1020 according to the first embodiment is a pipe that connects the plurality of heat exchangers 1010 together. The connection relationship of the plurality of heat exchangers 1010 by the connecting pipe 1020 in the first embodiment will be described later.

[0022] Each heat exchange unit 1010 has a fin-tube heat exchanger of a parallel piping type. The heat exchange unit 1010 has a lower header 1100, a refrigerant inlet / outlet pipe 1200, a row header 1300, a plurality of heat transfer tubes 1400, and a plurality of corrugated fins 1500. Here, the lower header 1100 and the refrigerant inlet / outlet pipe 1200 have lower headers 1100A and 1100B, respectively, and refrigerant inlet / outlet pipes 1200A and 1200B, respectively.

[0023] In the heat exchange unit 1010 according to the first embodiment, for example, a pair of headers, each consisting of two lower headers 1100 and a row-transfer header 1300, is arranged above and below in the Z direction. A plurality of heat transfer tubes 1400 are arranged in multiple rows along the Y direction between the two lower headers 1100 and the row-transfer header 1300. As will be described later, the heat transfer tubes 1400 according to the first embodiment have a flattened cross section. Here, a group of a plurality of heat transfer tubes 1400 is arranged in rows, with their flat surfaces facing each other and perpendicular to the lower headers 1100 and the row-transfer header 1300 and parallel to each other. The group of heat transfer tubes 1400 in one row is connected to one lower header 1100. While an example in which the heat transfer tubes 1400 are arranged in two rows will be described, the present invention can also be applied to a heat exchange unit 1010 arranged in three or more rows.

[0024] Each lower header 1100 is connected to other devices constituting the refrigeration cycle system and has cylindrical pipes through which a refrigerant, a fluid serving as a heat exchange medium, flows and branches or merges. When the heat exchanger 1000 in the first embodiment functions as a condenser, the lower header 1100A serves as a gas header through which gas refrigerant (including two-phase gas-liquid refrigerant) passes and branches the refrigerant. The lower header 1100B serves as a liquid header through which liquid refrigerant (including two-phase gas-liquid refrigerant) passes and merges the refrigerant. The lower headers 1100 are each connected to refrigerant inlet / outlet pipes 1200 (refrigerant inlet / outlet pipes 1200A and 1200B). The top surface of the lower header 1100 has an unconnected region 1101 at one end in the Y direction, where a heat transfer tube 1400 (described later) is not inserted and connected. The refrigerant inlet / outlet pipe 1200 in the first embodiment is a pipe whose one end is connected to the lower header 1100 in the unconnected region 1101 and whose pipe axis extends in the Z direction. The other end of the refrigerant inlet / outlet pipe 1200 is connected to a connection pipe with an external device, through which the refrigerant flows in and out.

[0025] For example, in the outdoor unit 200, within the housing housing the heat exchanger 1000, the piping for connecting the equipment is arranged in a corner that does not serve as an air flow path. Therefore, the refrigerant inlet / outlet pipe 1200 is arranged in the corner of the housing to accommodate the piping arrangement. By configuring the refrigerant inlet / outlet pipe 1200 to connect to the lower header 1100 at the top end surface of the lower header 1100, it is not necessary to ensure a large bending radius when bending piping such as the connecting pipe 1020 at the corner of the housing. Therefore, for example, the heat exchange unit 1010 installed within the housing can be made larger, thereby increasing the area occupied by the heat exchange unit 1010 on the side of the housing. In particular, the piping connecting to the lower header 1100B, which is located upstream of the air flow located outside the housing, is longer due to its location outside the housing. However, this length can be reduced, thereby allowing for more space to be created by the shorter piping length.

[0026] In addition, the row-to-row header 1300 is a header that acts as a bridge, joining the refrigerant flowing in from a group of heat transfer tubes 1400 in one row and branching it out to a group of heat transfer tubes 1400 in the other row.

[0027] The heat transfer tube 1400 is a flattened heat transfer tube having a flat cross section, a flat outer surface on the longitudinal side of the flat shape along the depth direction (the air flow direction), and a curved outer surface on the lateral side perpendicular to the longitudinal direction. The heat transfer tube 1400 of the first embodiment is a multi-hole heat transfer tube having a plurality of holes therein that serve as refrigerant flow paths. In the first embodiment, the holes of the heat transfer tube 1400 are formed facing the height direction to serve as flow paths between the lower header 1100 and the row-to-row header 1300. As described above, the heat transfer tubes 1400 are arranged horizontally at equal intervals with their outer surfaces facing each other on the longitudinal side. When manufacturing the heat exchange unit 1010 of the first embodiment, each heat transfer tube 1400 is inserted into insertion holes (not shown) in the lower header 1100 and the row-to-row header 1300, and then brazed and joined. For example, a brazing filler metal containing aluminum is used. This allows the lower header 1100, the row header 1300, and the inside of each heat transfer tube 1400 to communicate with each other.

[0028] Here, the number of stages of the heat transfer tubes 1400 is different between the main heat exchange section 1011 and the supercooling heat exchange section 1012. For example, in the heat exchanger 1000, the number of stages of the heat transfer tubes 1400 in the supercooling heat exchange section 1012 is smaller than the number of stages of the heat transfer tubes 1400 in the main heat exchange section 1011. Therefore, the volume (flow path area) of the supercooling heat exchange section 1012 of the heat exchanger 1000 is smaller than the volume of the main heat exchange section 1011 of the heat exchanger 1000. Specifically, for example, the number of heat transfer tube stages in the main heat exchange section 1011 is set to n1, and the number of heat transfer tube stages in the supercooling heat exchange section 1012 is set to n2. Then, when the stage ratio R of the heat exchanger 1000 is defined as R = n2 / (n1 + n2), the stage ratio R is configured to satisfy the relationship 0.1 < R < 0.5.

[0029] 3 is a diagram showing the relationship between the stage ratio R and heat exchange performance according to the first embodiment. The heat exchange performance is expressed, for example, by the amount of energy supplied, such as heat, relative to a change in the temperature of the refrigerant. If the number of stages of the heat transfer tubes 1400 in the subcooling heat exchange unit 1012 is smaller than the number of stages of the heat transfer tubes 1400 in the main heat exchange unit 1011, the flow rate of the liquid refrigerant flowing through the subcooling heat exchange unit 1012 increases. This allows a balance to be maintained between condensation of the gas refrigerant in the main heat exchange unit 1011 and subcooling in the subcooling heat exchange unit 1012.

[0030] Corrugated fins 1500 are arranged between the opposing flat surfaces of the arranged heat transfer tubes 1400. The corrugated fins 1500 are arranged to increase the heat transfer area between the refrigerant and the outside air. The corrugated fins 1500 are formed by corrugating a plate material and folding it into a zigzag shape with repeated mountain and valley folds, forming a wavy bellows. Here, the corrugated fins 1500 are described as being used as fins in the heat exchange unit 1010, but the shape of the fins is not particularly limited, and fins of other shapes may also be used.

[0031] In the heat exchange unit 1010 of the heat exchanger 1000 according to the first embodiment, when the heat exchange unit 1010 is used as a condenser and a subcooler, a high-temperature and high-pressure refrigerant flows through the refrigerant flow passages in the heat transfer tubes 1400. When the heat exchange unit 1010 is used as an evaporator, a low-temperature and low-pressure refrigerant flows through the refrigerant flow passages in the heat transfer tubes 1400.

[0032] The dotted arrows in Figure 2 indicate the flow of refrigerant when the heat exchanger 1000 of the first embodiment is used as a condenser and a subcooler. When the heat exchange unit 1010 functions as a condenser or a subcooler, as in the heat exchanger 1000 of the first embodiment, the refrigerant flows countercurrently to the air. Countercurrent refers to the refrigerant flowing from the heat transfer tubes 1400 in the downstream row toward the heat transfer tubes 1400 in the upstream row in the air flow. In the heat exchanger 1000, the connecting tube 1020 connects the refrigerant inlet / outlet tube 1200B, which is the refrigerant outlet side of the main heat exchange unit 1011 (which functions as a condenser), to the refrigerant inlet / outlet tube 1200A, which is the refrigerant inlet side of the subcooling heat exchange unit 1012 (which functions as a subcooler).

[0033] As shown in FIG. 2 , the refrigerant sent from the compressor 210 flows through the refrigerant inlet / outlet pipe 1200A into the lower header 1100A of the main heat exchange unit 1011, which is connected to the heat transfer tube 1400 in the row furthest downstream in the air flow. Here, since the heat exchange unit 1010 of the heat exchanger 1000 in the first embodiment has a two-row configuration, the most downstream will be referred to as downstream hereinafter. The refrigerant that flows into the lower header 1100A of the main heat exchange unit 1011 is distributed and passes through the heat transfer tube 1400 in the row furthest downstream in the air flow. The heat transfer tube 1400 exchanges heat between the refrigerant passing through the tube and the outside air passing outside the tube. During this process, the refrigerant dissipates heat to the outside air while passing through the heat transfer tube 1400.

[0034] The refrigerant then turns back at the row-to-row header 1300, passes through the heat transfer tubes 1400 in the row that is upstream in the air flow and exchanges heat, and then flows into the lower header 1100B of the main heat exchange unit 1011 and merges therewith. When three or more rows of heat transfer tubes 1400 are arranged along the air flow, the refrigerant repeatedly passes through the upstream heat transfer tubes 1400 and exchanges heat. The liquid refrigerant that merges in the lower header 1100B that is furthest upstream in the air flow passes through the refrigerant inlet / outlet pipe 1200B connected to the lower header 1100B and then passes through the connecting pipe 1020.

[0035] The refrigerant that has passed through the connecting pipe 1020 flows via the refrigerant inlet / outlet pipe 1200A into the lower header 1100A of the subcooling heat exchange unit 1012, which is connected to a group of heat transfer tubes 1400 in a row that is downstream in the air flow. The refrigerant that has flowed into the lower header 1100A of the subcooling heat exchange unit 1012 is distributed and passes through the heat transfer tubes 1400 in the row that is downstream in the air flow, where it is subcooled. The refrigerant that has passed through the heat transfer tubes 1400 in the row that is downstream in the air flow is further turned back at the row-to-row header 1300. The turned back refrigerant passes through the heat transfer tubes 1400 in the row that is upstream in the air flow, where it is subcooled, and then flows into the lower header 1100B of the subcooling heat exchange unit 1012, where it joins. The merged liquid refrigerant flows through a refrigerant inlet / outlet pipe 1200B connected to the lower header 1100B, flows out of the heat exchanger 1000, passes through the refrigerant piping 300, and is sent to the expansion valve 120 of the indoor unit 100.

[0036] In the heat transfer tubes 1400 in the row downstream in the air flow, heat exchange occurs between the refrigerant that has not undergone heat exchange and the air that has undergone heat exchange in the heat transfer tubes 1400 in the row upstream in the air flow. On the other hand, in the heat transfer tubes 1400 in the row upstream in the air flow, heat exchange occurs between the refrigerant that has undergone heat exchange in the heat transfer tubes 1400 in the row downstream in the air flow and the air that has not undergone heat exchange. Therefore, a temperature difference that allows effective heat exchange between the refrigerant and the air can be maintained in both the heat transfer tubes 1400 in the row upstream in the air flow and the heat transfer tubes 1400 in the row downstream in the air flow. In particular, even in the subcooling heat exchange unit 1012 where liquid refrigerant flows, which has poorer heat conductivity than gas refrigerant, flowing the refrigerant and air in countercurrents improves heat transfer performance.

[0037] As described above, the heat exchanger 1000 in the first embodiment is configured to connect the refrigerant inlet / outlet pipe 1200B of the main heat exchange unit 1011 and the refrigerant inlet / outlet pipe 1200A of the subcooling heat exchange unit 1012 via the connecting pipe 1020. Therefore, when the heat exchanger 1000 functions as a condenser and a subcooler, the refrigerant flow in the heat exchange unit 1010 and the air flow passing through the heat exchange unit 1010 can be countercurrent. Therefore, heat exchange can be performed while maintaining a temperature difference that allows effective heat exchange between the refrigerant and the air throughout the entire refrigerant flow path of the heat exchanger 1000, thereby improving the heat transfer performance of the heat exchanger 1000. In particular, the refrigerant inlet / outlet pipe 1200 is connected to the lower header 1100 in the unconnected region 1101 on the top surface of the lower header 1100. Therefore, when the upstream piping, which is the upstream side in the air flow, is bent and housed in a housing, the longer piping length prevents obstruction of the air flow path. Furthermore, the flow passage area for heat exchange can be increased, thereby improving the heat exchange performance.

[0038] Furthermore, according to the heat exchanger 1000 of the first embodiment, the main heat exchange section 1011 and the subcooling heat exchange section 1012 are configured so that the stage ratio R of the number of heat transfer tube stages n2 in the subcooling heat exchange section 1012 in the entire heat exchanger 1000 satisfies the relationship 0.1 < R < 0.5. In the heat exchanger 1000, the flow rate of the refrigerant, which is reduced by condensation into a liquid state in the main heat exchange section 1011, increases as the flow path area narrows in the subcooling heat exchange section 1012, thereby enabling smooth movement of the refrigerant within the heat exchanger 1000.

[0039] Embodiment 2. Fig. 4 is a diagram showing a part of a cross section of a heat exchanger 1000 according to embodiment 2 when viewed along the Y direction. Fig. 5 is a diagram showing a part of a cross section of the heat exchanger 1000 according to embodiment 2 when viewed along the X direction. Although not particularly limited, Figs. 4 and 5 show the configuration of a lower header 1100A that serves as a gas header for the subcooling heat exchange section 1012. However, the present invention is not limited to this. Other lower headers 1100 can also be used.

[0040] 4 and 5, the lower header 1100 in the heat exchanger 1000 of the second embodiment is a refrigerant distributor having a double structure including an outer pipe 1110 and an inner pipe 1120. The lower header 1100A also has a partition plate 1130.

[0041] The outer tube 1110 is a tube formed by combining a first member 1111 and a second member 1112. The first member 1111 is an inverted U-shaped semi-open member that forms the top surface and flat side surfaces of the long, cylindrical outer tube 1110 extending in the Y direction. The second member 1112 is a member that forms the bottom surface of the cylindrical outer tube 1110.

[0042] In addition, the partition plate 1130 serves as a wall that divides the space within the outer pipe 1110 between the inner pipe 1120 and the outer pipe 1110 into a second space 1150 that communicates with the heat transfer pipe 1400 and a third space 1160 that communicates with the refrigerant inlet / outlet pipe 1200.

[0043] On the other hand, the inner pipe 1120 is a long pipe that is installed inside the outer pipe 1110 along the outer pipe 1110. The inner pipe 1120 serves as a wall that divides the space inside the outer pipe 1110 into a first space 1140 and a second space 1150. Here, in the lower header 1100 of the second embodiment, the dimensional center of the inner pipe 1120 is located lower than the dimensional center of the outer pipe 1110 in the Z direction. By positioning the inner pipe 1120 in a space located lower inside the outer pipe 1110, it is possible to reduce the area where liquid refrigerant is likely to stagnate.

[0044] The inner pipe 1120 has an orifice 1121 serving as a refrigerant inlet / outlet hole. Here, the orifice 1121 in the second embodiment is not located directly below the inner pipe 1120 but is located diagonally below the inner pipe 1120 and is oriented so as to spray the gas-liquid two-phase refrigerant to the downwind side (downstream side in the air flow) of the air passing through the heat exchanger 1000.

[0045] For example, the refrigerant that flows from the refrigerant inlet / outlet pipe 1200 into the outer pipe 1110 passes through the third space 1160 and flows into the first space 1140 in the inner pipe 1120. The refrigerant that flows out from the orifice 1121 is ejected into the second space 1150 in the outer pipe 1110 and flows into the heat transfer pipe 1400. The refrigerant that flows from the heat transfer pipe 1400 into the outer pipe 1110 of the lower header 1100 passes through the second space 1150, flows from the orifice 1121 into the first space 1140 in the inner pipe 1120, passes through the third space 1160, and flows out of the refrigerant inlet / outlet pipe 1200.

[0046] In the lower header 1100 in the second embodiment, for example, when gas-liquid two-phase refrigerant flows from the refrigerant inlet / outlet pipe 1200 into the outer pipe 1110, the gas-liquid two-phase refrigerant flows into the third space 1160 in the outer pipe 1110 and then passes through the first space 1140. Therefore, the gas refrigerant and liquid refrigerant of the gas-liquid two-phase refrigerant are mixed in the third space 1160 and pass through the first space 1140. The gas-liquid two-phase refrigerant is also agitated when it passes through the first space 1140 and flows out from the orifice 1121 into the second space 1150 between the inner pipe 1120 and the outer pipe 1110. Therefore, the liquid refrigerant and the gas refrigerant become nearly homogeneous. By making the refrigerant flow ratio of the refrigerant passing through the multiple heat transfer pipes 1400 more uniform, the heat exchange performance of the heat exchanger 1000 is improved.

[0047] The heat transfer tube 1400 has multiple flow paths along the X direction, which is the direction in which air passes. By ejecting gas-liquid two-phase refrigerant toward the downwind side from orifices 1121 provided diagonally below the inner tube 1120, a gas-rich refrigerant having a higher proportion of gas refrigerant component in the gas-liquid two-phase refrigerant is supplied to the downwind flow path of the heat transfer tube 1400. On the other hand, a liquid-rich refrigerant having a higher proportion of liquid refrigerant component in the gas-liquid two-phase refrigerant is supplied to the flow path on the upwind side (upstream side in the air flow) of the heat transfer tube 1400. Therefore, more liquid refrigerant can be distributed to the upwind side where the temperature difference between the refrigerant and the air is greater, improving heat transfer performance.

[0048] Third Embodiment Fig. 6 is a diagram illustrating a corrugated fin 1500 in a heat exchanger unit 1010 according to a third embodiment. The surfaces of the flanks between the peaks of the corrugated fin 1500 are referred to as fins 1510. Fig. 6 shows the fins 1510 at a certain position in the corrugated fin 1500. As described above, the heat exchanger unit 1010 is configured with heat transfer tubes 1400, which serve as refrigerant flow paths, arranged in multiple rows in the air flow direction. Here, the heat transfer tube 1400 on the windward side, which is upstream in the air flow, is referred to as heat transfer tube 1400A, and the heat transfer tube 1400 on the leeward side, which is downstream in the air flow, is referred to as heat transfer tube 1400B.

[0049] The corrugated fins 1500 of the heat exchange unit 1010 in the heat exchanger 1000 according to the third embodiment are arranged across the heat transfer tubes 1400A and 1400B and are brazed and joined to the heat transfer tubes 1400A and 1400B. In the heat exchanger 1000 according to the third embodiment, the corrugated fins 1500 are arranged integrally in multiple rows without being separated, so that the fins 1510 can transfer heat between the rows, and heat transfer is not interrupted, thereby maintaining a large temperature difference between the air and the refrigerant.

[0050] Each fin 1510 of the corrugated fin 1500 has a louver 1511 and drainage slits 1512. Multiple louvers 1511 are arranged side by side in the airflow direction on each fin 1510. Therefore, the louvers 1511 are aligned along the airflow. The louvers 1511 have slits that allow air to pass through and plate portions that guide the air passing through the slits, thereby increasing the surface area of ​​the fin 1510.

[0051] The drainage slits 1512 also drain water generated on the fins 1510. The drainage slits 1512 are formed in a rectangular shape extending horizontally. Here, the drainage slits 1512 are arranged in each fin 1510 at a position corresponding to the center of the corresponding heat transfer tube 1400 in the air flow direction. However, this is not limited to this. For example, when multiple drainage slits 1512 are provided in the fin 1510, adjusting the spacing between the drainage slits 1512 and the slit length can improve drainage on the upwind side of the fin 1510, where heat transfer performance is higher than on the downwind side. Furthermore, heat transfer performance can be improved on the downwind side, where heat transfer performance is lower than on the upwind side. This prevents a decrease in drainage and heat exchange performance. Furthermore, improving the heat transfer performance on the downwind side can reduce the difference in heat transfer performance on the fin 1510. This allows the thickness of frost that forms on the surface of the fin 1510 to be more uniform under low-temperature air conditions, thereby improving heat exchange performance under low-temperature air conditions.

[0052] Embodiment 4. FIG. 7 is a diagram illustrating the arrangement of the outdoor heat exchanger 230 in the outdoor unit 200 according to Embodiment 4. FIG. 7 illustrates the arrangement within the housing 201 when the outdoor unit 200 is viewed from above along the height direction. The row transfer header 1300 is not illustrated in FIG. 7. In FIG. 7, white arrows indicate the flow of air, and black arrows indicate the flow of refrigerant when the heat exchanger 1000 serving as the outdoor heat exchanger 230 functions as a condenser. The outdoor unit 200 according to Embodiment 4 is a side-flow type unit having an outlet (not shown) for the outdoor fan 250 on a side surface of the housing 201. In the outdoor unit 200, the rotation axis of the outdoor fan 250 is horizontally disposed, and air flows into the housing 201 from one side surface in the longitudinal direction of the housing 201 and is blown out toward the opposite side surface.

[0053] In the outdoor heat exchanger 230 according to the fourth embodiment, two heat exchange units 1010 are arranged in an L-shape. As shown in Fig. 7 , in a side-flow type unit, the main heat exchange unit 1011 is arranged along the longitudinal direction of the housing 201, and the subcooling heat exchange unit 1012 is arranged along the lateral direction of the housing 201.

[0054] As described above, the outdoor unit 200 in embodiment 4 is a side-flow type unit in which the main heat exchange section 1011, which has a large number of heat transfer tube stages, is arranged along the longitudinal direction of the housing 201. In addition, the subcooling heat exchange section 1012, which has a small number of heat transfer tube stages, is arranged along the lateral direction of the housing 201. Therefore, the heat exchanger 1000 can be arranged efficiently within the housing 201 as the outdoor heat exchanger 230.

[0055] Fifth Embodiment. FIG. 8 is a diagram illustrating the arrangement of the outdoor heat exchanger 230 in the outdoor unit 200 according to the fifth embodiment. FIG. 8 illustrates the arrangement of the outdoor heat exchanger 230 in the housing 201 when the outdoor unit 200 is viewed from above along the Z direction. The row transfer header 1300 is not illustrated in FIG. 8. In FIG. 8, white arrows indicate the air flow, and black arrows indicate the refrigerant flow when the heat exchanger 1000 serving as the outdoor heat exchanger 230 functions as a condenser and a subcooler. The outdoor unit 200 according to the fifth embodiment is a top-flow type unit having an outlet (not shown) for the outdoor fan 250 at the top center of the housing 201. In the outdoor unit 200, the rotation axis of the outdoor fan 250 is vertically disposed, and air flows into the housing 201 from the side and is blown out toward the top.

[0056] In the heat exchanger 1000 that serves as the outdoor heat exchanger 230 in the fifth embodiment, three heat exchange units 1010 are arranged in a U-shape so that the heat exchange units 1010 surround the outdoor fan 250 at an upper position on the side surface of the housing 201 of the outdoor unit 200. Here, the allocation of the main heat exchange units 1011 and the subcooling heat exchange units 1012 in the entire outdoor heat exchanger 230 in which the heat exchange units 1010 are arranged in a U-shape will be described.

[0057] In Fig. 8, of the three heat exchange units 1010, two heat exchange units 1010 are main heat exchange units 1011 and one heat exchange unit 1010 is a subcooling heat exchange unit 1012. In Fig. 4, the subcooling heat exchange unit 1012 is disposed at the bottom of the U-shape, and the main heat exchange unit 1011 and the subcooling heat exchange unit 1012 disposed at the bottom are disposed vertically opposite each other.

[0058] 8, the gas refrigerant discharged from the compressor 210 flows into the two main heat exchange units 1011. The liquid refrigerant condensed in the two main heat exchange units 1011 and flowing out of the two main heat exchange units 1011 joins together in the connecting pipe 1020, flows into the subcooling heat exchange unit 1012, and is subcooled before flowing out.

[0059] As described above, the outdoor unit 200 in the fifth embodiment is a top-flow type unit, and can be configured by combining a plurality of heat exchange sections 1010, such as by arranging one subcooling heat exchange section 1012 in a plurality of main heat exchange sections 1011. Therefore, the heat exchanger 1000 can be efficiently arranged in the housing 201 as the outdoor heat exchanger 230.

[0060] In the first embodiment described above, the heat exchanger 1000 is used in the outdoor heat exchanger 230 of the outdoor unit 200, but this is not limiting. The heat exchanger 1000 may be used in the indoor heat exchanger 110 of the indoor unit 100, or may be used in both the outdoor heat exchanger 230 and the indoor heat exchanger 110.

[0061] Although the first embodiment has been described above in relation to an air conditioner, it can also be applied to other refrigeration cycle devices such as a refrigerator, a freezer, or a hot water supply device.

[0062] In addition, in the above-mentioned first embodiment, both the main heat exchange section 1011 and the subcooling heat exchange section 1012 are described as fin tube types using corrugated fins 1500, but either one may be a fin tube type.

[0063] 100 Indoor unit, 110 Indoor heat exchanger, 120 Expansion valve, 130 Indoor fan, 200 Outdoor unit, 201 Housing, 210 Compressor, 220 Four-way valve, 230 Outdoor heat exchanger, 240 Accumulator, 250 Outdoor fan, 300 Refrigerant piping, 1000 Heat exchanger, 1010 Heat exchange section, 1011 Main heat exchange section, 1012 Subcooling heat exchange section, 1020 Connecting pipe, 1100, 1100A, 1100B Lower header, 1101 Unconnected area, 1110 Outer pipe, 1111 First member, 1112 Second member, 1120 Inner pipe, 1121 Orifice, 1130 Partition plate, 1140 First space, 1150 Second space, 1160 Third space, 1200, 1200A, 1200B refrigerant inlet / outlet pipes, 1300 row header, 1400, 1400A, 1400B heat transfer pipes, 1500 corrugated fin, 1510 fin, 1511 louver, 1512 drainage slit.

Claims

1. A pair of headers are positioned vertically, spaced apart from each other, through which the refrigerant passes. Multiple heat exchange sections are connected in a series of intervals along the longitudinal direction of a pair of headers, each containing multiple heat transfer tubes with internal passages through which the refrigerant flows, and each heat exchange section is connected to the lower header of the pair of headers, and includes refrigerant inlet and outlet pipes through which the refrigerant flows in and out of the external refrigerant piping. A connecting pipe connects a heat exchange section which serves as a main heat exchange section that exchanges heat between air and the refrigerant and condenses the refrigerant, and a heat exchange section which serves as a subcooling heat exchange section that exchanges heat between the refrigerant that has passed through the main heat exchange section and the air and subcools the refrigerant that has passed through the main heat exchange section. Equipped with, The supercooled heat exchange section has an unconnected region at one end of the top surface of the lower header to which the heat transfer tubes are not connected. The refrigerant inlet and outlet pipes are connected in the unconnected region. The connecting pipe connects the refrigerant inlet / outlet pipe on the refrigerant outlet side of the main heat exchange section to the refrigerant inlet / outlet pipe on the refrigerant inflow side of the subcooling heat exchange section when condensation occurs in the main heat exchange section. At least the lower header on the refrigerant outlet side of the main heat exchange section and the lower header in the subcooled heat exchange section are An outer tube to which multiple heat transfer tubes are connected, An inner tube is installed inside the outer tube and serves as a wall dividing the inside of the outer tube into a first space to which the heat transfer tubes are not connected and a second space to which the heat transfer tubes are connected. A partition plate that serves as a wall divides the inside of the outer tube into a second space to which the heat transfer tubes are connected and a third space to which the refrigerant inlet and outlet pipes are connected. It has, The inner tube is a heat exchanger having a plurality of orifices that connect the first space and the second space.

2. When the number of heat transfer tube stages in the main heat exchange section is defined as n1, and the number of heat transfer tube stages in the supercooled heat exchange section is defined as n2, and the ratio of the number of stages in the supercooled heat exchange section is defined as R = n2 / (n1 + n2), The heat exchanger according to claim 1, wherein the stage ratio R is in the range of 0.1 < R < 0.

5.

3. The heat exchange section is The heat transfer tubes are flattened heat transfer tubes having a flattened cross-section, with the flattened surfaces facing each other. A heat exchanger according to claim 1 or claim 2, having a plurality of fins arranged between two adjacent flat heat transfer tubes and joined to the flat heat transfer tubes on the flat surface.

4. Multiple flattened heat transfer tubes are arranged in a row along the direction of airflow. The heat exchanger according to claim 3, wherein the fins are integrally arranged across the row of flat heat transfer tubes.

5. An outdoor unit having the heat exchanger described in claim 1 or claim 2 as an outdoor heat exchanger.

6. The outdoor unit according to claim 5, wherein the rotating shaft of the outdoor fan that generates airflow is a side-flow type unit arranged horizontally.

7. The outdoor unit according to claim 5, wherein the rotation axis of the outdoor fan that generates the aforementioned airflow is a top-flow type unit arranged in the height direction.

8. A refrigeration cycle device having an outdoor unit as described in claim 5.