Outdoor heat exchanger and air conditioner

Abstract

An outdoor heat exchanger includes a plurality of fins, a blower, a plurality of heat transfer tubes arranged in an up-down direction, and a first flow divider connected to the plurality of heat transfer tubes. The plurality of heat transfer tubes includes a lowermost heat transfer tube located at a lowermost side and at least one upper heat transfer tube located at a position higher than the lowermost heat transfer tube. The upper heat transfer tube has a merging passage connected to the first flow divider, a second flow divider provided at an end portion of the merging passage, and at least two branch passages branched from the second flow divider. A flow resistance of a liquid-phase refrigerant inside the upper heat transfer tube is smaller than a flow resistance of the liquid-phase refrigerant inside the lowermost heat transfer tube.

Description

Technical Field

[0001] This disclosure relates to outdoor heat exchangers and air conditioners. Background Technology

[0002] Air conditioners typically consist of an indoor system and an outdoor unit. The outdoor unit has an outdoor heat exchanger, which is configured to exchange heat between the refrigerant and the air.

[0003] The outdoor heat exchanger disclosed in Patent Document 1 includes multiple heat-conducting pipes arranged vertically and connected in parallel. Each heat-conducting pipe has multiple fins, through which heat exchange occurs between the refrigerant and the air. In Patent Document 1, to prevent refrigerant misflow in the lowest heat-conducting pipe, the flow path length of the lowest refrigerant passage is longer than that of the other refrigerant passages.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2015-87074

[0005] In the structure proposed in Patent Document 1, the refrigerant channel at the bottom has a long flow path, resulting in a large pressure loss of the refrigerant inside its heat pipe. This large pressure loss leads to a problem where the heat exchange performance decreases due to refrigerant flow stagnation. Summary of the Invention

[0006] This disclosure is made in consideration of such circumstances and aims to provide an outdoor heat exchanger with improved heat exchange performance.

[0007] To address the aforementioned issues, the outdoor heat exchanger disclosed herein comprises: a plurality of fins arranged at intervals; an air supply mechanism for supplying air into the gaps between the fins; a plurality of heat-conducting pipes arranged in a vertical direction intersecting the direction of air flow for refrigerant to flow through the plurality of fins and exchange heat with the air; and a first distributor connected to the plurality of heat-conducting pipes, the plurality of heat-conducting pipes including: a lowermost heat-conducting pipe located at the lowest side, and at least one upper heat-conducting pipe located above the lowermost heat-conducting pipe, the upper heat-conducting pipe having: a confluence channel connected to the first distributor, a second distributor disposed at the end of the confluence channel, and at least two branch channels branching from the second distributor, wherein the flow resistance of the liquid refrigerant inside the upper heat-conducting pipe is less than the flow resistance of the liquid refrigerant inside the lowermost heat-conducting pipe.

[0008] According to this disclosure, an outdoor heat exchanger with improved heat exchange performance can be provided. Attached Figure Description

[0009] Figure 1This is a structural diagram of the refrigerant passage of the air conditioner involved in Embodiment 1.

[0010] Figure 2 This is a front view of the outdoor unit involved in Embodiment 1.

[0011] Figure 3 This is a diagram showing the main components of the outdoor unit involved in Embodiment 1.

[0012] Figure 4 This is a diagram showing the main components of the outdoor heat exchanger according to Embodiment 1.

[0013] Figure 5 This is a structural diagram showing the refrigerant passage in the outdoor heat exchanger according to Embodiment 1.

[0014] Figure 6 This is a diagram illustrating the condensation performance of the outdoor heat exchanger involved in Embodiment 1.

[0015] Figure 7 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger involved in Embodiment 2.

[0016] Figure 8 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger involved in Embodiment 3.

[0017] Figure 9 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger according to Embodiment 4.

[0018] Figure 10 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger according to Embodiment 5.

[0019] Figure 11 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger according to Embodiment 6.

[0020] Figure 12 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger according to Embodiment 7. Detailed Implementation

[0021] Hereinafter, the heat exchanger according to the embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0022] Implementation Method 1

[0023] Figure 1 This is a structural diagram of the refrigerant passage in the air conditioner according to Embodiment 1. For example... Figure 1As shown, the air conditioner according to Embodiment 1 includes an outdoor unit 10 and an indoor system 11. The outdoor unit 10 and the indoor system 11 are configured to circulate refrigerant. In the following description, the gaseous refrigerant is sometimes referred to as "refrigerant gas," and the liquid refrigerant is sometimes referred to as "refrigerant liquid." When not distinguishing between the gaseous and liquid phases, it is simply referred to as "refrigerant." Figure 1 In the example, the indoor system 11 includes multiple indoor units 100. However, the indoor system 11 may also include only one indoor unit 100. Each indoor unit 100 includes an indoor heat exchanger 7 and an indoor air supply mechanism 8. Additionally, an expansion valve 6 is provided corresponding to each indoor unit 100. The outdoor unit 10 includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, and an air supply mechanism 4. Figure 1 In the middle, the air supply mechanism 4 includes an upper air supply fan 4-1 and a lower air supply fan 4-2. Alternatively, the air supply mechanism 4 can also consist of a single air supply mechanism.

[0024] When the air conditioner is operating in cooling mode, the high-temperature, high-pressure refrigerant gas discharged from the compressor 1 flows into the outdoor heat exchanger 3 through the four-way valve 2. In the outdoor heat exchanger 3, the refrigerant gas exchanges heat with the air supplied by the air supply mechanism 4 (upper fan 4-1 and lower fan 4-2) and condenses into liquid refrigerant (liquid refrigerant). The liquid refrigerant then flows into the indoor system 11 through the liquid valve 5 of the outdoor unit 10. The liquid refrigerant flowing into the indoor system 11 flows towards each indoor unit 100 through the expansion valves 6. In the indoor heat exchanger 7, the liquid refrigerant exchanges heat with the air supplied by the indoor air supply mechanism 8 and evaporates, becoming refrigerant gas. At this time, the refrigerant draws heat energy from the indoor air, thus cooling the air. The refrigerant gas evaporated in the indoor heat exchanger 7 returns to the compressor 1 through the gas valve 9 of the outdoor unit 10. This is the refrigerant cycle when the air conditioner is operating in cooling mode.

[0025] When the air conditioner is operating in heating mode, the high-temperature, high-pressure refrigerant gas discharged from the compressor 1 flows into the indoor system 11 through the four-way valve 2 and the gas valve 9. The refrigerant gas flows towards each indoor unit 100 included in the indoor system 11. Furthermore, the refrigerant gas condenses into liquid refrigerant by exchanging heat with the air supplied by the indoor air supply mechanism 8 in each indoor heat exchanger 7. At this time, the refrigerant imparts heat energy to the indoor air, thus heating the air. The liquid refrigerant condensed in each indoor unit 100 returns to the outdoor unit 10 through the expansion valve 6. The liquid refrigerant then flows towards the outdoor heat exchanger 3 through the liquid valve 5. In the outdoor heat exchanger 3, the liquid refrigerant evaporates by exchanging heat with the air supplied by the air supply mechanism 4 (upper fan 4-1 and lower fan 4-2), becoming refrigerant gas. The refrigerant gas returns to the compressor 1 through the four-way valve 2. This is the refrigerant cycle when the air conditioner is operating in heating mode.

[0026] Figure 2 This is a front view of the outdoor unit 10 according to Embodiment 1. The outdoor unit 10 in this embodiment is a side-flow type. Figure 3 This is a schematic diagram viewed from above of the main components of the outdoor unit 10 according to Embodiment 1. A compressor 1 for circulating refrigerant is arranged next to the upper fan 4-1 in the air supply mechanism 4. The air supply mechanism 4 is configured to draw air from outside the outdoor unit 10 and discharge air towards the outdoor heat exchanger 3. Figure 3 As shown, the outdoor heat exchanger 3 is positioned to receive the air supplied by the air supply mechanism 4.

[0027] Outdoor heat exchanger 3 is a so-called finned tube heat exchanger. More specifically, such as... Figure 3 As shown in the enlarged view, the outdoor heat exchanger 3 has three finned cores 3a to 3c. Each finned core 3a to 3c has multiple heat-conducting pipes P for refrigerant flow and multiple fins 29. Heat exchange occurs between the refrigerant flowing within the heat-conducting pipes P and the air at the fins 29. Air supplied by the air supply mechanism 4 passes through the gaps between the fins 29 and is blown out of the outdoor unit 10. Each finned core 3a to 3c has the same structure. Furthermore, the number of finned cores in the outdoor heat exchanger 3 can be appropriately varied, and can be one, two, or more than four.

[0028] Figure 4 This is a schematic diagram showing the main components of the outdoor heat exchanger 3 according to Embodiment 1. Figure 4 In the figures, for ease of observation, the representation of fin 29 and part of the heat pipe P is omitted. Figure 4As shown, the outdoor heat exchanger 3 according to Embodiment 1 is divided into two sections (upper section 3-1 and lower section 3-2) in the vertical direction. A gas manifold 13-1 and a first distributor 18-1 are provided corresponding to the upper section 3-1. A gas manifold 13-2 and a first distributor 18-2 are provided corresponding to the lower section 3-2. Multiple heat-conducting pipes P are provided in the upper section 3-1, connected in parallel with the gas manifold 13-1 and the first distributor 18-1 and arranged in the vertical direction. Multiple heat-conducting pipes P are provided in the lower section 3-2, connected in parallel with the gas manifold 13-2 and the first distributor 18-2 and arranged in the vertical direction.

[0029] In the following description, the gas manifolds 13-1 and 13-2 are collectively referred to as "gas manifold 13". Similarly, the first distributors 18-1 and 18-2 are collectively referred to as "first distributor 18". Gas manifold 13 is connected to four-way valve 2 via first inlet / outlet 12. Gas manifold 13 is configured to allow refrigerant to flow into multiple heat-conducting pipes P branches of the outdoor heat exchanger 3. Furthermore, the outdoor heat exchanger 3 may not be divided into upper section 3-1 and lower section 3-2 in the vertical direction, or it may be divided into three or more sections. Similarly, the number of gas manifolds 13 may be one or more, and the number of first distributors 18 may be one or more.

[0030] When the air conditioner is in cooling operation, the outdoor heat exchanger 3 functions as a condenser, and high-temperature, high-pressure refrigerant gas flows from the four-way valve 2 toward the gas manifold 13. This refrigerant gas flows through the gas manifold 13 into the heat pipes P of the outdoor heat exchanger 3. The refrigerant gas in the heat pipes P exchanges heat with the air via fins 29, condensing into liquid refrigerant. Multiple heat pipes P are connected to the first distributor 18 via capillary tubes 17. The liquid refrigerant flows into the subcooled heat exchanger 19 through capillary tubes 17 and the first distributor 18. More specifically, the liquid refrigerant in the upper section 3-1 flows into the subcooled heat exchanger 19 through capillary tubes 17 and the first distributor 18-1, and the liquid refrigerant in the lower section 3-2 flows into the subcooled heat exchanger 19 through capillary tubes 17 and the first distributor 18-2.

[0031] In the subcooled heat exchanger 19, liquid refrigerant exchanges heat with air to become subcooled refrigerant, which then flows out from the second inlet 22 to the outside of the outdoor heat exchanger 3. By producing subcooled refrigerant through the subcooled heat exchanger 19, the refrigerant inside the liquid extension piping between the outdoor unit 10 and the indoor system 11 becomes a liquid phase. This improves the pressure loss in the high-pressure side piping. Furthermore, the refrigerant at the inlet of the expansion valve 6 in the indoor system 11 also becomes a liquid phase, which helps suppress noise generated in the expansion valve 6 when a mixture of gas and liquid phases exists.

[0032] When the air conditioner is operating in heating mode, the refrigerant liquid (or a mixture of refrigerant liquid and refrigerant gas) condensed in the indoor system 11 flows into the subcooled heat exchanger 19 through the second inlet 22. Through heat exchange in the subcooled heat exchanger 19, a portion of the refrigerant liquid evaporates. The mixture of refrigerant liquid and refrigerant gas flows from the subcooled heat exchanger 19 toward the first distributor 18. In the first distributor 18, the mixture is split and flows through multiple capillaries 17 into the heat pipes P of the outdoor heat exchanger 3. Within the heat pipes P, heat exchange occurs with air via fins 29, causing the refrigerant liquid contained in the mixture to evaporate into refrigerant gas. The refrigerant gas flows through the gas manifold 13 and the first inlet 12 to the four-way valve 2 outside the outdoor heat exchanger 3.

[0033] When the air conditioner is operating in heating mode, frost easily adheres to the bottommost fins 29 of the outdoor heat exchanger 3. Here, the subcooled heat exchanger 19 is located upstream of the first distributor 18, and each heat pipe P is located downstream of the first distributor 18. Therefore, the saturation pressure inside the subcooled heat exchanger 19 is higher than the saturation pressure inside the heat pipes P. That is, the saturation temperature of the refrigerant inside the subcooled heat exchanger 19 is higher than the saturation temperature of the refrigerant inside the heat pipes P. Therefore, by placing the subcooled heat exchanger 19 at the bottom of the outdoor heat exchanger 3, the adhesion of frost to the bottommost part of the fins 29 can be suppressed. By suppressing the adhesion of frost to the fins 29, the heating performance of the air conditioner can be improved.

[0034] Figure 5 The structure of the refrigerant passage in the lower section 3-2 is shown. Figure 5 The arrows indicating "airflow" show the direction of the airflow delivered by the air supply mechanism 4 (hereinafter simply referred to as "airflow direction"). As described above, air flows through the gaps between the fins 29 of the outdoor heat exchanger 3. A plurality of heat-conducting pipes P are arranged at intervals in the vertical direction. Each heat-conducting pipe P is connected to the first distributor 18-2 via a capillary tube 17. In this specification, the lowermost heat-conducting pipe P connected to the gas manifold 13-2 is referred to as the "lowest heat-conducting pipe PL". Furthermore, the heat-conducting pipe P located above the lowermost heat-conducting pipe PL among the plurality of heat-conducting pipes connected to the gas manifold 13-2 is referred to as the "upper heat-conducting pipe PU". Figure 5 In the gas manifold 13-2, there are a total of 10 heat pipes P connected to it, and the number of upper heat pipes PU is 9. In addition, the number of upper heat pipes PU can be changed appropriately, and it can also be 1.

[0035] The lowest heat pipe PL is connected to the gas manifold 13-2 via a single channel 31. Conversely, each upper heat pipe PU is connected to the gas manifold 13-2 via two branch channels (upper branch channel 14 and lower branch channel 15). Furthermore, each upper heat pipe PU has a second distributor 16 connecting the two branch channels 14 and 15 to a confluence channel 30. Each confluence channel 30 is connected to the upper end of the first distributor 18-2 via a capillary tube 17. In summary, the refrigerant path from the gas manifold 13-2 to the first distributor 18-2 includes a path through the upper heat pipe PU (hereinafter also referred to as the first path) and a path through the lowest heat pipe PL (hereinafter also referred to as the second path). The first path through the upper heat pipe PU includes branch channels 14 and 15, the second distributor 16, the confluence channel 30, and the capillary tube 17. In contrast, the second path through the lowest heat pipe PL does not include branch channels or splitters.

[0036] In this specification, the length of the flow path from the first splitter 18-2 through any second splitter 16 to the gas manifold 13-2 is denoted as L. When viewed from the first splitter 18-2, the second splitter 16 is positioned at approximately 0.4 to 0.6L in the aforementioned flow path.

[0037] like Figure 5 As shown, a subcooled heat exchanger 19 is positioned lower than the lowest heat pipe PL. The subcooled heat exchanger 19 is connected to the lower end of the first distributor 18-2. Each heat pipe P is connected to the upper end of the first distributor 18-2 via a capillary tube 17.

[0038] Here, gravity acts on the refrigerant flowing within the multiple heat pipes P. In particular, when the outdoor heat exchanger 3 operates as an evaporator (i.e., when the air conditioner is in heating mode), liquid refrigerant flows more easily into and accumulates in the lowest heat pipe PL compared to the upper heat pipe PU. This phenomenon of refrigerant flowing towards a specific pipe is called "refrigerant deflection." Refrigerant deflection is a significant factor reducing the heat exchange performance (evaporation performance) of the outdoor heat exchanger 3. Therefore, the outdoor heat exchanger 3 according to this embodiment is configured such that the flow resistance of the refrigerant in each upper heat pipe PU is less than the flow resistance of the refrigerant in the lowest heat pipe PL. More specifically, the lowest heat pipe PL and the gas manifold 13-2 are connected by a single channel 31, and the upper heat pipes PU and the gas manifold 13-2 are connected by branch channels 14 and 15. According to this structure, the pressure loss in the lowest heat pipe PL becomes greater than the pressure loss in the upper heat pipe PU. Therefore, it can suppress the flow rate of refrigerant liquid into the lowest heat pipe PL located at the bottom, and suppress the refrigerant deflection that is prone to occur at the bottom of the outdoor unit 10. That is, it can improve the heat exchange performance (evaporation performance) of the outdoor heat exchanger 3.

[0039] When the outdoor heat exchanger 3 operates as a condenser (i.e., when the air conditioner is in cooling mode), the refrigerant gas discharged from the compressor 1 flows into multiple heat pipes P through the first inlet / outlet 12 and the gas manifold 13, where it condenses. In the flow path between branch channels 14 and 15 and the second distributor 16, the refrigerant may also be in a state where liquid and gaseous phases are mixed. During the merging at the second distributor 16 and through the merging channel 30, the condensation of the refrigerant is further advanced. Subsequently, the refrigerant passes through the first distributor 18 and the subcooled heat exchanger 19, becoming almost liquid (or subcooled), and flows into the indoor system 11.

[0040] As described above, the outdoor heat exchanger 3 according to this embodiment includes: a plurality of fins 29 arranged at intervals; an air supply mechanism 4 that supplies air into the gaps between the fins 29; a plurality of heat-conducting pipes P arranged in a vertical direction intersecting the direction of air flow for refrigerant to flow through the plurality of fins 29 to exchange heat with the air; and a first distributor 18 connected to the plurality of heat-conducting pipes P. The plurality of heat-conducting pipes P includes a lowermost heat-conducting pipe PL located at the lowest side, and at least one upper heat-conducting pipe PU located above the lowermost heat-conducting pipe PL. The upper heat-conducting pipe PU has a confluence channel 30 connected to the first distributor 18, a second distributor 16 provided at the end of the confluence channel 30, and at least two branch channels 14, 15 branching from the second distributor 16. The flow resistance of the liquid refrigerant inside the upper heat-conducting pipe PU is less than the flow resistance of the liquid refrigerant inside the lowermost heat-conducting pipe PL.

[0041] According to this structure, the pressure loss of the refrigerant inside the lowest heat pipe PL becomes greater than the pressure loss of the refrigerant inside the upper heat pipe PU. Therefore, refrigerant deflection into the lowest heat pipe PL among the multiple heat pipes P can be suppressed. Furthermore, with the second diverter 16 provided in the upper heat pipe PU, compared to the conventional structure which only lengthens the refrigerant passage at the lowest point, the overall pressure loss of the outdoor heat exchanger 3 can be improved. That is, the evaporation performance of the outdoor heat exchanger 3 can be improved compared to the past.

[0042] In addition, the outdoor heat exchanger 3 according to this embodiment has a gas manifold 13 in which multiple heat pipes P are connected in parallel. When the length of the flow path from the first distributor 18 to the gas manifold 13 through the second distributor 16 is set to L, the second distributor 16 is set at a position of about 0.4L to 0.6L in the flow path when viewed from the first distributor 18.

[0043] Although details will be described later, this structure allows for an increase in the range of high dryness within the pipe, utilizing high thermal conductivity. In other words, it improves the condensation performance of the outdoor heat exchanger 3.

[0044] Furthermore, the air conditioner according to this embodiment includes an outdoor unit 10 and an indoor system 11. The outdoor unit 10 includes an outdoor heat exchanger 3, a compressor 1, and a four-way valve 2. The air conditioner operates in heating mode when the outdoor heat exchanger 3 functions as an evaporator, and in cooling mode when the outdoor heat exchanger 3 functions as a condenser. As described above, an air conditioner can be provided that improves heating or cooling performance by enhancing the heat exchange performance of the outdoor heat exchanger 3.

[0045] Figure 6This is a diagram illustrating the improvement of heat exchange performance through the outdoor heat exchanger 3 described in Embodiment 1. Figure 6 (a) is a schematic diagram showing the flow of refrigerant in the upper heat pipe PU. Figure 6 (b) is a schematic diagram showing the flow of refrigerant in the lowest heat pipe PL. As described above, the upper heat pipe PU has a second splitter 16 that merges the upper branch channel 14 and the lower branch channel 15 and connects to a merging channel 30. Figure 6 In (a), blocks 5 to 8 correspond to the refrigerant path through the upper branch channel 14, and blocks 1 to 4 correspond to the refrigerant path through the lower branch channel 15. Figure 6 In (a), block 9 corresponds to the second splitter 16, and blocks 10 to 12 correspond to the path of the refrigerant through the confluence channel 30. Figure 6 (b) indicates the case where the refrigerant flows in series in blocks 1 to 12, corresponding to the case where a single channel 31 in the lowest heat pipe PL does not branch but is connected to the capillary tube 17.

[0046] Figure 6 The curve for "with a second splitter" in (c) is related to the upper heat pipe PU. Figure 6 (a) corresponds to. Figure 6 The curve for "without a second splitter" in (c) is similar to the curve for the lowest heat pipe PL. Figure 6 (b) corresponds to. Figure 6 The horizontal axis of (c) and Figure 6 The corresponding blocks in (a) and (b) are shown on the vertical axis, which represents the thermal conductivity inside the pipe in each block. Figure 6 Curve (d) represents the relationship between the dryness of the refrigerant gas inside the pipe (horizontal axis) and the thermal conductivity inside the pipe (vertical axis). As the refrigerant gas condenses inside the pipe, the dryness decreases, while the amount of liquid refrigerant increases. If the amount of liquid refrigerant increases, the surface area inside the pipe available for condensation of the refrigerant gas decreases, thereby reducing the thermal conductivity. Therefore, if... Figure 6 As shown in (d), there is a trend that thermal conductivity decreases as dryness decreases. In particular, if the dryness is below 0.4, the thermal conductivity decreases significantly. Figure 6As shown in (c), in the case of "without the second splitter", the thermal conductivity of blocks 5-8 is low. This is because blocks 1-4 are connected in series with blocks 5-8, and refrigerant gas condensation occurs in the downstream blocks 5-8, resulting in reduced dryness. In contrast, in the case of "with the second splitter", blocks 1-4 are connected in parallel with blocks 5-8, so refrigerant gas condensation does not occur in blocks 5-8 compared to "without the second splitter". Therefore, in the structure "with the second splitter", the dryness within the pipe can be high over a wider range. Through the above, in the upper heat pipe PU with the second splitter 16, high thermal conductivity with a dryness range of 0.4 to 1.0 can be utilized. That is, the condensation performance of the outdoor heat exchanger 3 can be improved.

[0047] Furthermore, when the length of the flow path from the first distributor 18 through the second distributor 16 to the gas manifold 13 is set to L, the second distributor 16 is preferably positioned at approximately 0.4L to 0.6L in the flow path when viewed from the first distributor 18. According to this structure, the proportion of flow paths with a dryness of 0.4 to 1.0 can be increased.

[0048] Implementation Method 2

[0049] Next, the outdoor heat exchanger 3 according to Embodiment 2 will be described. The basic structure of Embodiment 2 is the same as that of Embodiment 1. Therefore, the same reference numerals are used to refer to the same structures and the description is omitted. The feature points of this embodiment will be described.

[0050] Figure 7 This is a structural diagram of the refrigerant passage in the lower section 3-2 of the outdoor heat exchanger 3 according to Embodiment 2. Figure 7 As shown, the capillary 17 connecting the upper heat pipe PU and the first distributor 18-2 is specifically referred to as "upper capillary 17A". The capillary 17 connecting the lower heat pipe PL and the first distributor 18-2 is specifically referred to as "lowest capillary 17B".

[0051] The outdoor heat exchanger 3 according to this embodiment is configured such that the flow resistance of the refrigerant liquid inside the lowermost capillary tube 17B is greater than the flow resistance of the refrigerant liquid inside the upper capillary tube 17A. That is, the pressure loss of the refrigerant liquid in the lowermost capillary tube 17B is greater than the pressure loss of the refrigerant liquid in the upper capillary tube 17A.

[0052] In this embodiment, the length of the refrigerant flow path from the first distributor 18-2 through the lowermost capillary tube 17B, the lowermost heat-conducting tube PL, and the single channel 31 to the gas manifold 13-2 is called the "first flow path length". Conversely, the length of the refrigerant flow path from the first distributor 18-2 through the upper capillary tube 17A, the upper heat-conducting tube PU, and the branch channels 14 or 15 to the gas manifold 13-2 is called the "second flow path length". The first flow path length is shorter than the second flow path length.

[0053] As explained above, in the outdoor heat exchanger 3 according to this embodiment, the flow resistance of the liquid refrigerant inside the capillary tube 17B connecting the lowermost heat pipe PL and the first distributor 18 is greater than the flow resistance inside the capillary tube 17A connecting the uppermost heat pipe PU and the first distributor 18. According to this structure, it is more difficult for the refrigerant to flow into the lowermost heat pipe PL, and the generation of refrigerant flow deviation can be suppressed more reliably.

[0054] Furthermore, the outdoor heat exchanger 3 according to this embodiment includes a gas manifold 13 with multiple heat pipes P connected in parallel. The length of the first flow path from the first distributor 18 through the lowest heat pipe PL to the gas manifold 13 is shorter than the length of the second flow path from the first distributor 18 through the upper heat pipe PU to the gas manifold 13. With this structure, the pressure loss of the refrigerant in the lowest heat pipe PL can be reduced. Therefore, the overall pressure loss of the outdoor heat exchanger 3 can be reduced, and the evaporation and condensation performance of the outdoor heat exchanger 3 can be improved.

[0055] Implementation Method 3

[0056] Next, the outdoor heat exchanger 3 according to Embodiment 3 will be described. The basic structure of Embodiment 2 is the same as that of Embodiment 1. Therefore, the same reference numerals are used to label the same structures and the description is omitted. The feature points of this embodiment will be described.

[0057] Figure 8 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger 3 according to Embodiment 3. Figure 8 As shown, in this embodiment, the flow path including branch channels 14 and 15, the second distributor 16, and the confluence channel 30 is referred to as the "refrigerant channel 23". In the refrigerant channel 23, the inner diameters of the upper branch channel 14 and the lower branch channel 15 are both smaller than the inner diameter of the confluence channel 30. This structure increases the flow velocity of the refrigerant liquid within the branch channels 14 and 15, thereby increasing the thermal conductivity. Therefore, the performance of the outdoor heat exchanger 3 can be improved.

[0058] Implementation Method 4

[0059] Next, the outdoor heat exchanger 3 according to Embodiment 4 will be described. The basic structure of Embodiment 4 is the same as that of Embodiment 3. Therefore, the same reference numerals are used to refer to the same structures and the description is omitted. The feature points of this embodiment will be described.

[0060] Figure 9 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger 3 according to Embodiment 4. The outdoor heat exchanger 3 is divided into three columns (column 1, 26; column 25; and column 3, 24) in the airflow direction. Column 1, 26 is located at the upstream side in the airflow direction, and column 3, 24 is located at the downstream side in the airflow direction. Column 2, 25 is located between column 1, 26 and column 3, 24. The confluence channel 30 is located in column 1, 26; the second distributor 16 is located in column 2, 25; and the branch channels 14 and 15 are located in column 3, 24.

[0061] like Figure 9 As shown in the cross-sectional view corresponding to reference numeral 27 in the accompanying drawing, the fin spacing pt1 is the interval between the fins 29 in the third column 24. The interval between the fins 29 in the second column 25 can also be the same as the fin spacing pt1. Figure 9 As shown in the cross-sectional view corresponding to reference numeral 28 in the accompanying drawing, the fin spacing pt2 is the interval between the fins 29 in the first column 26. In other words, the interval between the fins 29 connected to the upper branch channel 14 or the lower branch channel 15 is the fin spacing pt1, and the interval between the fins 29 connected to the confluence channel 30 is the fin spacing pt2. The fin spacing pt1 is smaller than the fin spacing pt2.

[0062] Furthermore, as described in Embodiment 3, the inner diameters of both the upper branch channel 14 and the lower branch channel 15 are smaller than the inner diameter of the confluence channel 30. Therefore, the height of the burring of the fins 29 through which the flow path tubes of the branch channels 14 and 15 are inserted is lower than the height of the burring of the fins 29 through which the flow path tubes of the confluence channel 30 are inserted. This burring protrudes from the opening edge of the through hole formed in the fin 29 for inserting each flow path tube towards the direction in which the multiple fins 29 are arranged. The lower the height of this burring, the smaller the fin spacing can be. Therefore, as... Figure 9 As shown, it is possible to make the fin spacing pt1 smaller than the fin spacing pt2.

[0063] Thus, in the outdoor heat exchanger 3 according to this embodiment, the spacing (pt1) between the fins 29 provided in the two branch channels 14 and 15 is smaller than the spacing (pt2) between the fins 29 provided in the confluence channel 30. According to this structure, the number of fins 29 in the outdoor heat exchanger 3 increases. Therefore, the area for heat exchange with the air increases, and the heat exchange performance of the outdoor heat exchanger 3 can be improved.

[0064] Implementation Method 5

[0065] Next, the outdoor heat exchanger 3 according to Embodiment 5 will be described. The basic structure of Embodiment 5 is the same as that of Embodiment 3. Therefore, the same reference numerals are used to refer to the same structures and the description is omitted. The feature points of this embodiment will be described.

[0066] Figure 10 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger 3 according to embodiment 5. (As shown...) Figure 10 As shown, in Embodiment 5, several construction examples (splitting modes A to C) of the second splitter 16 are proposed. In the following description, the pipes connecting the ends of the branch channels 14 and 15 included in the second splitter 16 are referred to as branch pipes T1. Furthermore, the pipe located at the end of the merging channel 30 included in the second splitter 16 is referred to as merging pipe T2. In this embodiment, the second splitter 16 is formed by inserting the merging pipe T2 into the branch pipe T1.

[0067] In flow splitting mode A, branch pipe T1 extends vertically, and confluence pipe T2 extends horizontally in a direction orthogonal to the vertical direction. In flow splitting modes B and C, branch pipe T1 extends horizontally, and confluence pipe T2 extends vertically. In flow splitting mode B, confluence pipe T2 is inserted into branch pipe T1 from above, and in flow splitting mode C, confluence pipe T2 is inserted into branch pipe T1 from below. In the case of flow splitting mode A, due to the influence of gravity, the amount of refrigerant flowing into the lower branch channel 15 tends to be larger than that flowing into the upper branch channel 14. Therefore, it is preferable to set the amount by which branch pipe T1 is inserted into confluence pipe T2 such that the refrigerant flowing out of confluence pipe T2 collides with the inner wall of branch pipe T1. This improves the branching of the refrigerant in the second splitter 16. In the split-flow modes B and C, the amount by which branch pipe T1 is inserted into the confluence pipe T2 can also be set so that the refrigerant flowing out of the confluence pipe T2 collides with the inner wall of branch pipe T1.

[0068] As explained above, in the outdoor heat exchanger 3 of the splitting mode A in this embodiment, a second splitter 16 is formed by inserting a branch pipe T1, which connects the ends of the two branch channels 14 and 15, into a confluence pipe T2 located at the end of the confluence channel 30. Furthermore, the second splitter 16 is configured such that the branch pipe T1 extends vertically, and the refrigerant flowing from the confluence pipe T2 collides with the inner wall of the branch pipe T1. According to this structure, the branching of the refrigerant in the second splitter 16 is improved, and the refrigerant flows more evenly into each branch channel 14 and 15. Therefore, the evaporation performance of the outdoor heat exchanger 3 and the heating performance of the air conditioner can be improved.

[0069] Furthermore, in the outdoor heat exchanger 3 involved in the flow splitting modes B and C of this embodiment, a second flow splitter 16 is formed by connecting the confluence pipe T2 located at the end of the confluence channel 30 to the branch pipes T1 connecting the ends of the two branch channels 14. The branch pipes T1 extend horizontally. According to this structure, the flow rate of refrigerant into the branch channels 14 and 15 is suppressed from deviating due to gravity. As a result, the branching of the refrigerant in the second flow splitter 16 is improved, and the refrigerant flows more evenly into each branch channel 14 and 15. Therefore, the evaporation performance of the outdoor heat exchanger 3 and the heating performance of the air conditioner can be improved.

[0070] Furthermore, in flow splitting modes B and C, the confluence pipe T2 may not need to be inserted into the branch pipe T1. As long as the confluence pipe T2 is configured to connect with the branch pipe T1 to prevent refrigerant leakage, it can function as the second flow splitter 16.

[0071] Implementation Method 6

[0072] Next, the outdoor heat exchanger 3 according to Embodiment 6 will be described. The basic structure of Embodiment 6 is the same as that of the outdoor heat exchanger 3 in Embodiment 5 that adopts the split-flow mode A. Therefore, the same reference numerals are used to refer to the same structures and the description is omitted. The feature points of this embodiment will be described.

[0073] Figure 11 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger 3 according to Embodiment 6. In this embodiment, the inner diameter at the upper end of the branch pipe T1 (the end connected to the upper branch channel 14) is referred to as the first inner diameter φ1, and the inner diameter at the lower end of the branch pipe T1 (the end connected to the lower branch channel 15) is referred to as the second inner diameter φ2.

[0074] When branch pipe T1 extends vertically, due to gravity, refrigerant tends to flow towards the lower branch channel 15 compared to the upper branch channel 14. Therefore, in this embodiment, as... Figure 11 As shown, a structure is proposed where the first inner diameter φ1 is larger than the second inner diameter φ2. Based on this structure, the inflow rate of refrigerant into the downward branch channel 15 can be reduced.

[0075] As explained above, in the outdoor heat exchanger 3 according to this embodiment, a second distributor 16 is formed by connecting the confluence pipe T2 located at the end of the confluence channel 30 to the branch pipes T1 connecting the ends of the two branch channels 14. The branch pipes T1 extend in the vertical direction, and the first inner diameter φ1 at the upper end of the branch pipe T1 is larger than the second inner diameter φ2 at the lower end of the branch pipe T1. According to this structure, the increase in the inflow of refrigerant into the lower branch channel 15 due to gravity can be suppressed. That is, the refrigerant can flow into each branch channel 14 and 15 more evenly. Therefore, the evaporation performance of the outdoor heat exchanger 3 and the heating performance of the air conditioner can be improved.

[0076] Implementation Method 7

[0077] Next, the outdoor heat exchanger 3 according to Embodiment 7 will be described. The basic structure of Embodiment 7 is the same as that of Embodiment 3. Therefore, the same reference numerals are used to refer to the same structures and the description is omitted. The feature points of this embodiment will be described.

[0078] Figure 12 This is a structural diagram of the refrigerant passage in the outdoor heat exchanger 3 according to Embodiment 7. In this embodiment, a third distributor 20 and a fourth distributor 21 are connected to the subcooled heat exchanger 19. The third distributor 20 branches the refrigerant passage from the first distributor 18 to the subcooled heat exchanger 19 into three branches. The fourth distributor 21 merges the three branched refrigerant passages of the subcooled heat exchanger 19 into one refrigerant passage, which is connected to the second inlet / outlet 22. Furthermore, although the outdoor heat exchanger 3 according to this embodiment has both the third distributor 20 and the fourth distributor 21, the outdoor heat exchanger 3 may also have only either the third distributor 20 or the fourth distributor 21.

[0079] As explained above, in the outdoor heat exchanger 3 according to Embodiment 7, the subcooled heat exchanger 19 has multiple refrigerant channels, and a distributor (one or both of the third distributor 20 and the fourth distributor 21) is connected to the subcooled heat exchanger 19 to merge the multiple refrigerant channels into one refrigerant channel. According to this structure, the pressure loss in the subcooled heat exchanger 19 of the outdoor heat exchanger 3 can be reduced. That is, the heat exchange performance of the outdoor heat exchanger 3, or the cooling and heating performance of the air conditioner, can be improved.

[0080] The outdoor heat exchanger 3 according to several embodiments has been described above. However, the technical scope of this disclosure is not limited to the above embodiments, and various modifications can be made without departing from the spirit of this disclosure.

[0081] For example, in the above embodiment, the number of branch channels connected to a second splitter 16 is two (upper branch channel 14 and lower branch channel 15). However, it is also possible to have three or more branch channels connected to a second splitter 16.

[0082] In addition, in the above embodiment, the second splitter 16 is provided on all the upper heat pipes PU, but the second splitter 16 may only be provided on a portion of the upper heat pipes PU.

[0083] In addition, although the outdoor heat exchanger 3 has multiple upper heat conduction pipes PU, the number of upper heat conduction pipes PU can also be at least 1.

[0084] Furthermore, in the above embodiment, the structure of the refrigerant passage in the lower section 3-2 was mainly described, but the structure of the upper section 3-1 can also be the same as that of the lower section 3-2.

[0085] Furthermore, without departing from the spirit of this disclosure, the constituent elements in the above embodiments may be appropriately replaced with known constituent elements, and the above embodiments and variations may also be appropriately combined.

[0086] For example, the same outdoor heat exchanger 3 can also be used. Figure 10 Two or more of the three diversion modes A to C shown.

[0087] Explanation of reference numerals in the attached figures

[0088] 1... Compressor; 2... Four-way valve; 3... Outdoor heat exchanger; 4... Air supply mechanism; 10... Outdoor unit; 11... Indoor system; 13, 13-1, 13-2... Gas manifolds; 14, 15... Branch channels; 16... Second distributor; 17, 17A, 17B... Capillary tubes; 18, 18-1, 18-2... First distributor; 19... Subcooled heat exchanger; 29... Fins; 30... Confluence channel; P... Heat pipe; PL... Lowermost heat pipe; PU... Upper heat pipe; T1... Branch pipe; T2... Confluence pipe.

Claims

1. An outdoor heat exchanger, wherein, The outdoor heat exchanger includes: Multiple fins are arranged at intervals; An air supply mechanism supplies air into the gaps between the fins; Multiple heat pipes are arranged in a vertical direction that intersects the direction of air flow, for the flow of refrigerant that exchanges heat with the air through the multiple fins; The first distributor is connected to the plurality of heat pipes; and A gas manifold connects the multiple heat pipes in parallel. The plurality of heat pipes includes: a bottommost heat pipe located at the bottommost side, and at least one upper heat pipe located above the bottommost heat pipe. The upper heat pipe has: a confluence channel connected to the first distributor, a second distributor disposed at the end of the confluence channel, and at least two branch channels branching from the second distributor. The two branch channels are connected to the gas manifold. The lowest heat pipe is connected to the gas manifold via a single channel. The flow resistance of the liquid refrigerant inside the upper heat pipe is less than the flow resistance of the liquid refrigerant inside the lower heat pipe.

2. The outdoor heat exchanger according to claim 1, wherein, The flow resistance of the liquid refrigerant inside the capillary tube connecting the lower heat pipe to the first distributor is greater than the flow resistance inside the capillary tube connecting the upper heat pipe to the first distributor.

3. The outdoor heat exchanger according to claim 1 or 2, wherein, The refrigerant flow path length from the first distributor through the lowest heat pipe to the gas manifold is shorter than the refrigerant flow path length from the first distributor through the upper heat pipe to the gas manifold.

4. The outdoor heat exchanger according to claim 1 or 2, wherein, When the length of the flow path from the first distributor to the gas manifold via the second distributor is set to L, the second distributor is positioned at a position of 0.4L to 0.6L in the flow path when viewed from the first distributor.

5. The outdoor heat exchanger according to claim 1 or 2, wherein, The inner diameter of each of the two branch channels is smaller than the inner diameter of the merging channel.

6. The outdoor heat exchanger according to claim 5, wherein, The spacing between the fins in the two branch channels is smaller than the spacing between the fins in the confluence channel.

7. The outdoor heat exchanger according to any one of claims 1, 2, and 6, wherein, The second splitter is formed by inserting a merging pipe located at the end of the merging channel into a branch pipe connecting each end of the two branch channels. The second distributor is constructed such that the refrigerant flowing out of the confluence pipe collides with the inner wall of the branch pipe, which extends in the vertical direction.

8. The outdoor heat exchanger according to any one of claims 1, 2, and 6, wherein, The second splitter is formed by connecting the merging pipe located at the end of the merging channel to the branch pipes connecting the ends of the two branch channels. The branch pipe extends in a horizontal direction.

9. The outdoor heat exchanger according to any one of claims 1, 2, and 6, wherein, The second splitter is formed by connecting the merging pipe located at the end of the merging channel to the branch pipes connecting the ends of the two branch channels. The branch pipe extends in the vertical direction, and the inner diameter at the upper end of the branch pipe is larger than the inner diameter at the lower end of the branch pipe.

10. The outdoor heat exchanger according to any one of claims 1, 2, and 6, wherein, Equipped with a subcooled heat exchanger connected to the first distributor, The subcooled heat exchanger has multiple refrigerant channels. A distributor is connected to the subcooled heat exchanger to merge the multiple refrigerant channels into a single refrigerant channel.

11. An air conditioner comprising an outdoor unit and an indoor system, wherein, The outdoor unit includes an outdoor heat exchanger, a compressor, and a four-way valve as described in any one of claims 1 to 10. The outdoor heat exchanger operates as an evaporator, and is used for heating. The outdoor heat exchanger operates as a condenser and is used for refrigeration.

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