Heat exchanger, outdoor unit of refrigeration cycle system, and refrigeration cycle system

Abstract

The heat exchanger consists of multiple flat tubes arranged vertically in the vertical direction and spaced apart in a direction perpendicular to the airflow direction. It comprises multiple groups of flat tubes spaced apart in the airflow direction, corrugated fins placed between the flat tubes in each of the groups of flat tubes, and a pair of headers placed above and below each of the groups of flat tubes. One of the headers on the upstream side has a refrigerant inlet for use as an evaporator, and a temperature difference forming structure is provided between the upstream group of flat tubes and the second upstream group of flat tubes.

Description

Technical Field

[0001] The present disclosure relates to a heat exchanger having corrugated fins, an outdoor unit of a refrigeration cycle device, and a refrigeration cycle device.

Background Art

[0002] For example, a corrugated fin tube type heat exchanger configured by alternately laminating flat tubes and corrugated fins has become widespread. When such a heat exchanger functions as an evaporator, the surface temperature of the corrugated fins may drop below the freezing point, and the dew condensation water on the surface of the corrugated fins may freeze and frost may form. When frost forms on the surface of the corrugated fins, it becomes a resistance to the air passing through the heat exchanger and is a factor in reducing the heat transfer performance of the corrugated fins. Therefore, conventionally, there is a heat exchanger with improved frost resistance (see, for example, Patent Document 1).

[0003] The heat exchanger of Patent Document 1 has a structure in which the leading edge of the corrugated fin protrudes beyond the tip of the flat tube. When it functions as an evaporator, the temperature of the leading edge of the corrugated fin becomes higher than the flat tube temperature (refrigerant temperature), and the temperature difference between the air and the refrigerant becomes smaller on the upwind side of the corrugated fin. Therefore, it suppresses the sudden blockage of frost at the leading edge portion (upwind portion) of the heat exchanger and improves the frost resistance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, depending on the protruding length of the leading edge of the corrugated fin, residual frost may occur at the leading edge of the corrugated fin during the defrosting operation, and there is also a problem that the effect of suppressing the sudden blockage of frost is not large in the first place.

[0006] This disclosure was made to solve the above-mentioned problems and aims to provide a heat exchanger, an outdoor unit for a refrigeration cycle system, and a refrigeration cycle system that can sufficiently suppress rapid blockage due to frost. [Means for solving the problem]

[0007] The heat exchanger according to this disclosure comprises a plurality of flat tubes arranged vertically in the vertical direction and spaced apart in a direction perpendicular to the airflow direction, a plurality of groups of flat tubes spaced apart in the airflow direction, corrugated fins arranged between each of the plurality of flat tubes in each of the plurality of groups of flat tubes, and a pair of headers arranged above and below each of the plurality of groups of flat tubes, wherein a refrigerant inlet for use as an evaporator is formed in one of the pair of headers on the upstream side, and a temperature difference forming structure is provided between the upstream group of flat tubes and the second upstream group of flat tubes.

[0008] Furthermore, the outdoor unit of the refrigeration cycle system relating to this disclosure is equipped with the heat exchanger described above.

[0009] Furthermore, the refrigeration cycle system according to this disclosure includes a compressor, an outdoor unit of the refrigeration cycle system, a throttle device, and an indoor unit of the refrigeration cycle system, all connected by refrigerant piping, and is equipped with a refrigerant circuit through which the refrigerant circulates. [Effects of the Invention]

[0010] According to this disclosure, in a heat exchanger, one of the pair of headers on the upstream side has a refrigerant inlet formed when it functions as an evaporator, and a temperature difference forming structure is provided between the upstream flat tube group and the second upstream flat tube group. As a result, the refrigerant temperature (saturation temperature) in the upstream flat tube group can be increased, thereby suppressing the temperature difference between the air and the refrigerant in the upstream flat tube group and sufficiently suppressing rapid blockage by frost. [Brief explanation of the drawing]

[0011] [Figure 1] This is a refrigerant circuit diagram showing a refrigeration cycle system equipped with a heat exchanger according to Embodiment 1. [Figure 2] This is a schematic front view showing a heat exchanger according to Embodiment 1. [Figure 3] This is a schematic perspective view showing the refrigerant flow when the heat exchanger according to Embodiment 1 functions as an evaporator. [Figure 4] This figure shows the temperature relative to the position of the refrigerant path in a heat exchanger according to Embodiment 1 and in a conventional heat exchanger. [Figure 5] This is a schematic front view showing a heat exchanger according to Embodiment 2. [Figure 6] This is a schematic perspective view showing the refrigerant flow when the heat exchanger according to Embodiment 2 functions as an evaporator. [Figure 7] This is an enlarged cross-sectional perspective view of the upper part of the heat exchanger according to Embodiment 2, schematically showing the refrigerant flow when the heat exchanger functions as an evaporator. [Figure 8] This figure shows the pressure loss in the column header with respect to the distance between the upper end of the flattened tube of the heat exchanger according to Embodiment 2 and the inner wall of the column header. [Figure 9] This is an enlarged cross-sectional side view of the upper part of a heat exchanger according to Embodiment 3. [Figure 10] This is a schematic front view showing a heat exchanger according to Embodiment 4. [Figure 11] This is a schematic perspective view showing the refrigerant flow when the heat exchanger according to Embodiment 4 functions as an evaporator. [Figure 12] This is an enlarged cross-sectional perspective view of the upper part of the heat exchanger according to Embodiment 4, schematically showing the refrigerant flow when the heat exchanger functions as an evaporator. [Figure 13] This is a schematic perspective view showing the refrigerant flow when the heat exchanger according to Embodiment 5 functions as an evaporator. [Figure 14] This is a schematic plan view of the flattened tube of the heat exchanger according to Embodiment 5. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present disclosure will be described based on the drawings. Note that the present disclosure is not limited by the embodiments described below. Also, in the following drawings, the size relationships of the respective components may be different from the actual ones. Further, in the following description, for ease of understanding, terms indicating directions such as "upper", "lower", "right", "left", "front", "rear", etc. are used as appropriate, but this is for the purpose of explanation, and these terms do not limit the embodiments. Also, in the embodiments, "upper", "lower", "right", "left", "front", "rear", etc. are used in the state of viewing the heat exchanger from the front.

[0013] Embodiment 1. <Configuration of Refrigeration Cycle Device 100> FIG. 1 is a refrigerant circuit diagram showing a refrigeration cycle device 100 including a heat exchanger 30 according to Embodiment 1. The solid arrows in FIG. 1 indicate the refrigerant flow during the cooling operation, and the dashed arrows in FIG. 1 indicate the refrigerant flow during the heating operation.

[0014] First, the refrigeration cycle device 100 including the heat exchanger 30 will be described using FIG. 1. In Embodiment 1, an air conditioner is exemplified as the refrigeration cycle device 100, but the refrigeration cycle device 100 is used for refrigeration applications or air conditioning applications such as, for example, a refrigerator or freezer, a vending machine, an air conditioner, a refrigeration device, a water heater, etc. Note that the illustrated refrigerant circuit 101 is an example, and the configuration of circuit elements and the like are not limited to the content described in the embodiments, and can be appropriately changed within the scope of the technology according to the embodiments.

[0015] As shown in FIG. 1, the refrigeration cycle device 100 according to Embodiment 1 includes an outdoor unit 10 and an indoor unit 20. The outdoor unit 10 includes a compressor 11, a flow path switching device 12, a fan 13, and a heat exchanger 30. The indoor unit 20 includes a throttling device 21, an indoor heat exchanger 22, and an indoor fan 23.

[0016] Furthermore, the refrigeration cycle system 100 consists of an outdoor unit 10 and an indoor unit 20, and is equipped with a refrigerant circuit 101 through which the refrigerant circulates. Specifically, the refrigerant circuit 101 is composed of a compressor 11, a flow path switching device 12, a heat exchanger 30, a throttling device 21, and an indoor heat exchanger 22, all connected by refrigerant piping. This refrigeration cycle system 100 can operate in both cooling and heating modes by switching the flow path switching device 12.

[0017] The refrigerant circulating in the refrigerant circuit 101 is a single refrigerant of R1234yf, R1234ze, and R290, or a mixture of two or more of these, or a mixture of one of these with another refrigerant, or a mixture containing R1132(E), or a mixture containing R1123. By using the above refrigerants, the low boiling point refrigerants have a low vapor density and a high flow velocity, so the effect of inertial force becomes large, and the improvement in refrigerant distribution performance can be greatly enhanced. In addition, with mixed refrigerants, concentration variations occur as distribution deteriorates, so the effect of performance improvement through improved refrigerant distribution performance can be greatly enhanced.

[0018] The compressor 11 draws in a low-temperature, low-pressure refrigerant, compresses the drawn-in refrigerant, and discharges a high-temperature, high-pressure refrigerant. The compressor 11 is, for example, an inverter compressor whose capacity, which is the amount of refrigerant delivered per unit time, is controlled by changing the operating frequency.

[0019] The flow path switching device 12 is, for example, a four-way valve, and switches between cooling and heating operation by switching the direction of refrigerant flow. During cooling operation, the flow path switching device 12 switches to the state shown by the solid line in Figure 1, and the discharge side of the compressor 11 is connected to the heat exchanger 30. During heating operation, the flow path switching device 12 switches to the state shown by the dashed line in Figure 1, and the discharge side of the compressor 11 is connected to the indoor heat exchanger 22.

[0020] The heat exchanger 30 performs heat exchange between the outdoor air and the refrigerant. During cooling operation, the heat exchanger 30 functions as a condenser, releasing the heat from the refrigerant to the outdoor air and condensing the refrigerant. During heating operation, the heat exchanger 30 functions as an evaporator, evaporating the refrigerant and cooling the outdoor air with the heat of vaporization.

[0021] The fan 13 supplies outdoor air to the heat exchanger 30, and the amount of air supplied to the heat exchanger 30 is adjusted by controlling its rotation speed.

[0022] The throttling device 21 is, for example, an electronic expansion valve that can adjust the throttling opening, and by adjusting the opening, it controls the pressure of the refrigerant flowing into the heat exchanger 30 or the indoor heat exchanger 22. In this embodiment, the throttling device 21 is provided on the indoor unit 20, but it may also be provided on the outdoor unit 10, and the installation location is not limited.

[0023] The indoor heat exchanger 22 performs heat exchange between indoor air and refrigerant. During cooling operation, the indoor heat exchanger 22 functions as an evaporator, evaporating the refrigerant and cooling the outdoor air with the heat of vaporization. During heating operation, the indoor heat exchanger 22 functions as a condenser, releasing the heat from the refrigerant to the outdoor air and condensing the refrigerant.

[0024] The indoor fan 23 supplies indoor air to the indoor heat exchanger 22, and the amount of air supplied to the indoor heat exchanger 22 is adjusted by controlling its rotation speed.

[0025] Figure 2 is a schematic front view of the heat exchanger 30 according to Embodiment 1. Figure 3 is a schematic perspective view showing the refrigerant flow when the heat exchanger 30 according to Embodiment 1 functions as an evaporator. In Figure 3, dashed arrows indicate the refrigerant flow, and white arrows indicate the air flow direction. In Figure 3, components on the windward side of the heat exchanger 30 are labeled "A," and components on the leeward side are labeled "B."

[0026] As shown in Figures 2 and 3, the heat exchanger 30 according to Embodiment 1 consists of a plurality of flat tubes 38 (38A, 38B) arranged vertically in the vertical direction and spaced apart in a direction perpendicular to the airflow direction, a plurality (two in Embodiment 1) of groups of flat tubes 31 (31A, 31B) spaced apart in the airflow direction, corrugated fins 39 (39A, 39B) arranged between each of the plurality of flat tubes 38 (38A, 38B) in the plurality of groups of flat tubes 31 (31A, 31B), and a pair of headers arranged above and below each of the plurality of groups of flat tubes 31 (31A, 31B). The pair of headers consists of a lower header 34 (34A, 34B) and an upper header 35 (35A, 25B). The upper end of the upwind flattened tube group 31A is inserted into the upwind upper header 35A, and the lower end of the upwind flattened tube group 31A is inserted into the upwind lower header 34A. Similarly, the upper end of the downwind flattened tube group 31B is inserted into the downwind upper header 35B, and the lower end of the downwind flattened tube group 31B is inserted into the downwind lower header 34B. A lower refrigerant inlet / outlet 34Aa is formed at one end of the upwind lower header 34A, and an upper refrigerant inlet / outlet 35Aa is formed at one end of the upwind upper header 35A. Similarly, an upper refrigerant inlet / outlet 35Ba is formed at one end of the downwind upper header 35B, and a lower refrigerant inlet / outlet 34Ba is formed at one end of the downwind lower header 34B. Furthermore, the upper refrigerant inlet / outlet 35Aa of the upper header 35A on the windward side and the upper refrigerant inlet / outlet 35Ba of the upper header 35B on the leeward side are connected by a connecting pipe 41, and a flow resistance element 42 is provided on the connecting pipe 41. The flow resistance element 42 is, for example, a capillary tube or a flow control valve. Hereinafter, the connecting pipe 41 and the flow resistance element 42 will also be referred to as a temperature difference forming structure.

[0027] When the heat exchanger 30 functions as an evaporator, a gaseous two-phase refrigerant flows in from the lower refrigerant inlet 34Aa (hereinafter also referred to as the refrigerant inlet) of the upper-wind side lower header 34A, and flows in the following order: upper-wind side lower header 34A, upper-wind side flattened tube group 31A, upper-wind side upper header 35A, temperature difference forming structure, lower-wind side upper header 35B, lower-wind side flattened tube group 31B, and lower-wind side lower header 34B, and gaseous refrigerant flows out from the lower refrigerant inlet 34Ba of the lower-wind side lower header 34B.

[0028] In Embodiment 1, the upper refrigerant inlet / outlet 35Aa of the upwind upper header 35A and the upper refrigerant inlet / outlet 35Ba of the downwind upper header 35B are connected by a connecting pipe 41, but the embodiment is not limited to this. It is sufficient that one of the lower refrigerant inlet / outlet 34Aa and upper refrigerant inlet / outlet 35Aa of the pair of upwind headers is connected by a connecting pipe 41 to one of the lower refrigerant inlet / outlet 34Ba and upper refrigerant inlet / outlet 35Ba of the pair of downwind headers. However, by connecting the upper refrigerant inlet / outlet 35Aa of the upwind upper header 35A with the upper refrigerant inlet / outlet 35Ba of the downwind upper header 35B with a connecting pipe 41, or by connecting the lower refrigerant inlet / outlet 34Aa of the upwind lower header 34A with the lower refrigerant inlet / outlet 34Ba of the downwind lower header 34B with a connecting pipe 41, the length of the connecting pipe 41 can be shortened compared to the configuration in which the upper refrigerant inlet / outlet 35Aa of the upwind upper header 35A with the lower refrigerant inlet / outlet 34Ba of the downwind lower header 34B with a connecting pipe 41, or the lower refrigerant inlet / outlet 34Aa of the upwind lower header 34A with the upper refrigerant inlet / outlet 35Ba of the downwind upper header 35B with a connecting pipe 41, thereby saving space.

[0029] Furthermore, in Embodiment 1, the heat exchanger 30 has two groups of flat tubes 31 spaced apart in the airflow direction, but it is not limited to this, and there may be three or more. In that case, one of the lower refrigerant inlet / outlet and upper refrigerant inlet / outlet of the pair of headers on the upstream side is connected to one of the lower refrigerant inlet / outlet and upper refrigerant inlet / outlet of the pair of headers second upstream side by a connecting pipe 41, and a flow resistance body 42 is provided on the connecting pipe 41. In other words, a temperature difference forming structure is provided between the group of flat tubes 31 on the upstream side and the group of flat tubes 31 second upstream side.

[0030] Figure 4 shows the temperature relative to the position of the refrigerant path in the heat exchanger 30 according to Embodiment 1 and in a conventional heat exchanger. Here, the position of the refrigerant path refers to the position of the refrigerant path within the heat exchanger when the heat exchanger functions as an evaporator. In other words, the left side of Figures 4(a) and (b) shows the inlet side when the heat exchanger functions as an evaporator, and the right side of Figures 4(a) and (b) shows the outlet side when the heat exchanger functions as an evaporator. Note that Figure 4(a) is a diagram of a conventional heat exchanger, that is, a heat exchanger in which a temperature difference forming structure is not provided between the pair of headers on the upwind side and the pair of headers on the leeward side, and Figure 4(b) is a diagram of the heat exchanger 30 according to Embodiment 1, that is, a heat exchanger 30 in which a connecting pipe 41 and a flow resistance body 42, which are temperature difference forming structures, are provided between the pair of headers on the upwind side and the pair of headers on the leeward side.

[0031] In the heat exchanger 30 according to Embodiment 1, by providing a connecting pipe 41 and a flow resistance body 42, which are temperature difference forming structures, between a pair of headers on the windward side and a pair of headers on the leeward side, the refrigerant temperature (saturation temperature) in the windward flattened pipe group 31 can be increased compared to the conventional one shown in Figure 4(a), as shown in Figure 4(b). By increasing the refrigerant temperature (saturation temperature) in the windward flattened pipe group 31, the temperature difference between the air and the refrigerant in the windward flattened pipe group 31 can be suppressed, thereby sufficiently suppressing rapid blockage by frost. In other words, the temperature difference forming structure suppresses the temperature difference between the air and the refrigerant in each flattened pipe group 31 by forming a temperature difference between the flattened pipe groups 31.

[0032] Furthermore, by configuring the flow resistance element 42 with a flow control valve whose opening degree can be adjusted, the flow resistance element 42 can provide a flow resistance suitable for the operating conditions, thereby improving frost resistance.

[0033] As described above, the heat exchanger 30 according to Embodiment 1 consists of a plurality of flat tubes 38 arranged vertically in the vertical direction and spaced apart in a direction perpendicular to the air flow direction, a plurality of groups of flat tubes 31 spaced apart in the air flow direction, corrugated fins 39 arranged between each of the plurality of flat tubes 38 in the plurality of groups of flat tubes 31, and a pair of headers arranged above and below each of the plurality of groups of flat tubes 31, with a refrigerant inlet formed in one of the pair of headers on the upstream side when it functions as an evaporator, and a temperature difference forming structure is provided between the upstream group of flat tubes 31 and the second upstream group of flat tubes 31.

[0034] According to the heat exchanger 30 of Embodiment 1, a refrigerant inlet for use as an evaporator is formed in one of the pair of headers on the upstream side, and a temperature difference forming structure is provided between the upstream flat tube group 31 and the second upstream flat tube group 31. As a result, the refrigerant temperature (saturation temperature) in the upstream flat tube group 31 can be increased, thereby suppressing the temperature difference between the air and the refrigerant in the upstream flat tube group 31 and sufficiently suppressing rapid blockage by frost.

[0035] Furthermore, in the heat exchanger 30 according to Embodiment 1, the connecting pipe 41 connects the upper side of the pair of headers on the windward side to the upper side of the pair of headers on the second windward side, or connects the lower side of the pair of headers on the windward side to the lower side of the pair of headers on the second windward side.

[0036] According to the heat exchanger 30 of Embodiment 1, the length of the connecting pipe 41 can be shortened, thereby saving space.

[0037] Furthermore, in the heat exchanger 30 according to Embodiment 1, the flow resistance element 42 is a flow control valve.

[0038] According to the heat exchanger 30 of Embodiment 1, by configuring the flow resistance element 42 with a flow control valve whose opening degree can be adjusted, the flow resistance element 42 can provide a flow resistance suitable for the operating conditions, thereby improving frost resistance.

[0039] Furthermore, in the refrigeration cycle device 100 according to Embodiment 1, the refrigerant is a mixture of two or more of R1234yf, R1234ze, and R290, or a mixture of any of these with another refrigerant, a mixture containing R1132(E), or a mixture containing R1123.

[0040] According to the refrigeration cycle device 100 of Embodiment 1, by using the above-mentioned refrigerant, the low boiling point refrigerant has a low vapor density and a high flow velocity, so the effect of inertial force becomes large, and thus the effect of improving the refrigerant distribution performance can be greatly enhanced. Furthermore, with mixed refrigerants, concentration variations occur as the distribution deteriorates, so the effect of performance improvement through improved refrigerant distribution performance can be greatly enhanced.

[0041] Embodiment 2. Embodiment 2 will be described below, but the explanation will be omitted for parts that overlap with Embodiment 1, and the same reference numerals will be used for parts that are the same as or corresponding to Embodiment 1.

[0042] Figure 5 is a schematic front view showing the heat exchanger 30 according to Embodiment 2. Figure 6 is a schematic perspective view showing the refrigerant flow when the heat exchanger 30 according to Embodiment 2 functions as an evaporator. In Figure 6, dashed arrows indicate the refrigerant flow, and white arrows indicate the air flow direction. In Figure 6, components on the windward side of the heat exchanger 30 are labeled "A," and components on the leeward side are labeled "B."

[0043] As shown in Figures 5 and 6, the heat exchanger 30 according to Embodiment 2 consists of a plurality of flat tubes 38 (38A, 38B) arranged vertically in the upright direction and spaced apart in a direction perpendicular to the airflow direction, a plurality (two in Embodiment 2) of flat tube groups 31 (31A, 31B) spaced apart in the airflow direction, corrugated fins 39 (39A, 39B) arranged between the plurality of flat tubes 38 (38A, 38B) of each of the plurality of flat tube groups 31 (31A, 31B), and a pair of headers arranged above and below each of the plurality of flat tube groups 31 (31A, 31B). The pair of headers consists of a lower header 34 (34A, 34B) and a row-pass header 36. The upper end of the upwind flat tube group 31A and the upper end of the downwind flat tube group 31B are inserted into the row-pass header 36. Furthermore, the lower end of the upwind flattened pipe group 31A is inserted into the upwind lower header 34A, and the lower end of the downwind flattened pipe group 31B is inserted into the downwind lower header 34B. A lower refrigerant inlet outlet 34Aa is formed at one end of the upwind lower header 34A. A lower refrigerant inlet outlet 34Ba is formed at one end of the downwind lower header 34B.

[0044] When the heat exchanger 30 functions as an evaporator, a gaseous two-phase refrigerant flows in from the lower refrigerant inlet 34Aa (hereinafter also referred to as the refrigerant inlet) of the upper-wind side lower header 34A, flows in the order of upper-wind side lower header 34A, upper-wind side flattened tube group 31A, row header 36, leeward side flattened tube group 31B, and leeward side lower header 34B, and gaseous refrigerant flows out from the lower refrigerant inlet 34Ba of the leeward side lower header 34B.

[0045] Figure 7 is an enlarged cross-sectional perspective view of the upper part of the heat exchanger 30 according to Embodiment 2, schematically showing the refrigerant flow when it functions as an evaporator. Figure 8 is a diagram showing the pressure loss in the column header 36 with respect to the distance between the upper end 38a of the flattened tube 38 of the heat exchanger 30 according to Embodiment 2 and the inner wall 36a of the column header 36. The white arrows in Figure 7 indicate the refrigerant flow.

[0046] As shown in Figure 7, the heat exchanger 30 according to Embodiment 2 is configured such that the distance δ between the upper end 38a of each flattened tube 38 and the inner wall 36a of the column header 36 is 2 mm or less. As shown in Figure 8, the pressure loss in the column header 36 increases or decreases depending on the above distance δ, so flow resistance can be provided without additional parts by adjusting the distance δ between the upper end 38a of each flattened tube 38 and the inner wall 36a of the column header 36. Also, as shown in Figure 8, if the above distance δ becomes larger than 2 mm, the pressure loss in the column header 36 increases sharply, so by keeping the above distance δ at 2 mm or less, the pressure loss in the column header 36 can be suppressed. Note that the heat exchanger 30 according to Embodiment 2 is configured such that the distance δ between the upper end 38a of each flattened tube 38 and the inner wall 36a of the column header 36 is 2 mm or less, but is not limited to this. Row-passing headers 36 may be provided at the lower ends of the flat pipe group 31A on the windward side and the flat pipe group 31B on the leeward side, and configured so that the distance δ between the lower end of each flat pipe 38 and the inner wall 36a of the row-passing header 36 is 2 mm or less.

[0047] As described above, the temperature difference forming structure according to Embodiment 2 is a structure in which the distance between the end of the furthest upwind flattened pipe group 31 and the end of the second furthest upwind flattened pipe group 31 and the inner wall 36a of the row-pass header 36 facing them is 2 mm or less. By making the temperature difference forming structure such a structure, flow resistance can be provided without additional parts, thereby reducing the number of parts while suppressing the temperature difference between the air and the refrigerant in the upwind flattened pipe group 31 and sufficiently suppressing rapid blockage by frost.

[0048] As described above, the heat exchanger 30 according to Embodiment 2 is configured such that the upper side of the pair of headers on the windward side and the upper side of the second windward pair of headers, or the lower side of the pair of headers on the windward side and the lower side of the second windward pair of headers are connected by a common row-pass header 36, and the temperature difference forming structure is configured such that the distance between the end of the flattened tube group 31 on the windward side and the end of the flattened tube group 31 on the second windward side and the inner wall 36a of the row-pass header 36 facing them is 2 mm or less.

[0049] According to the heat exchanger 30 of Embodiment 2, the number of parts can be reduced while suppressing the temperature difference between the air and the refrigerant in the flattened tube group 31 on the windward side, thereby sufficiently suppressing rapid blockage due to frost.

[0050] Embodiment 3. Embodiment 3 will be described below, but the explanation will be omitted for parts that overlap with Embodiments 1 and 2, and the same reference numerals will be used for parts that are the same as or corresponding to Embodiments 1 and 2.

[0051] Figure 9 is an enlarged cross-sectional side view of the upper part of a heat exchanger 30 according to Embodiment 3. As shown in Figure 9, the inner wall 36a of the row-pass header 36 is provided with a plurality of projections 36b that protrude downward. The plurality of projections 36b position each flat pipe 38 relative to the row-pass header 36, so that the distance δ between the upper end 38a of each flat pipe 38 and the inner wall 36a of the row-pass header 36 can be easily set to a predetermined value.

[0052] In the heat exchanger 30 according to Embodiment 3, the row header 36 is provided with a plurality of protrusions 36b that define the distance between the end of the furthest upwind flattened tube group 31 and the second furthest upwind flattened tube group 31 and the inner wall 36a of the row header 36 facing them.

[0053] According to the heat exchanger 30 of Embodiment 3, since each flattened tube 38 is positioned relative to the row-pass header 36, the distance δ between the end of each flattened tube 38 and the inner wall 36a of the row-pass header 36 can be easily set to a predetermined value.

[0054] Embodiment 4. Embodiment 4 will be described below, but the explanation will be omitted for parts that overlap with Embodiments 1 to 3, and the same reference numerals will be used for parts that are the same as or corresponding to Embodiments 1 to 3.

[0055] Figure 10 is a schematic front view of the heat exchanger 30 according to Embodiment 4. Figure 11 is a schematic perspective view showing the refrigerant flow when the heat exchanger 30 according to Embodiment 4 functions as an evaporator. In Figure 11, dashed arrows indicate the refrigerant flow, and white arrows indicate the air flow direction. In Figure 11, components on the windward side of the heat exchanger 30 are labeled "A," and components on the leeward side are labeled "B."

[0056] As shown in Figures 10 and 11, the heat exchanger 30 according to Embodiment 4 consists of a plurality of flat tubes 38 (38A, 38B) arranged vertically in the upright direction and spaced apart in a direction perpendicular to the airflow direction, a plurality (two in Embodiment 2) of groups of flat tubes 31 (31A, 31B) spaced apart in the airflow direction, corrugated fins 39 (39A, 39B) arranged between the plurality of flat tubes 38 (38A, 38B) in each of the plurality of groups of flat tubes 31 (31A, 31B), and a pair of headers arranged above and below each of the plurality of groups of flat tubes 31 (31A, 31B). The pair of headers consists of a lower header 34 (34A, 34B) and a row-pass header 36. The upper end of the upwind group of flat tubes 31A and the upper end of the downwind group of flat tubes 31B are inserted into the row-pass header 36. Furthermore, the lower end of the upwind flattened pipe group 31A is inserted into the upwind lower header 34A, and the lower end of the downwind flattened pipe group 31B is inserted into the downwind lower header 34B. A lower refrigerant inlet outlet 34Aa is formed at one end of the upwind lower header 34A. A lower refrigerant inlet outlet 34Ba is formed at one end of the downwind lower header 34B.

[0057] When the heat exchanger 30 functions as an evaporator, a gaseous two-phase refrigerant flows in from the lower refrigerant inlet 34Aa (hereinafter also referred to as the refrigerant inlet) of the upper-wind side lower header 34A, flows in the order of upper-wind side lower header 34A, upper-wind side flattened tube group 31A, row header 36, leeward side flattened tube group 31B, and leeward side lower header 34B, and gaseous refrigerant flows out from the lower refrigerant inlet 34Ba of the leeward side lower header 34B.

[0058] Figure 12 is an enlarged cross-sectional perspective view of the upper part of the heat exchanger 30 according to Embodiment 4, schematically showing the refrigerant flow when it functions as an evaporator. The white arrows in Figure 12 indicate the refrigerant flow.

[0059] As shown in Figure 12, the heat exchanger 30 according to Embodiment 4 has a plate material 37 extending in the direction in which a plurality of flattened pipes 38 (38A, 38B) are arranged side by side inside the row-pass header 36. This plate material 37 is provided between the plurality of flattened pipes 38A on the windward side and the plurality of flattened pipes 38B on the leeward side. In addition, a plurality of small holes 37a are formed in the plate material 37 at intervals in the direction in which the plurality of flattened pipes 38 (38A, 38B) are arranged side by side. The plurality of small holes 37a are formed to provide flow resistance.

[0060] As described above, the temperature difference forming structure according to Embodiment 4 is a plate material 37 provided within the row-pass header 36 between the end of the furthest upwind group of flat pipes 31 and the end of the second furthest upwind group of flat pipes 31, and having a plurality of small holes 37a formed in the direction in which the plurality of flat pipes 38 are arranged side by side. By making the temperature difference forming structure such a structure, the temperature difference between the air and the refrigerant in the upwind group of flat pipes 31 can be suppressed with a simple structure, and rapid blockage by frost can be sufficiently suppressed.

[0061] In the heat exchanger 30 according to Embodiment 4, the upper side of the pair of headers on the windward side and the upper side of the pair of headers on the second windward side, or the lower side of the pair of headers on the windward side and the lower side of the pair of headers on the second windward side, are composed of a common row-pass header 36, and the temperature difference forming structure is a plate material 37 provided within the row-pass header 36 between the end of the group of flat tubes 31 on the windward side and the end of the group of flat tubes 31 on the second windward side, and has a plurality of small holes 37a formed in the direction in which the plurality of flat tubes 38 are arranged side by side.

[0062] According to the heat exchanger 30 of Embodiment 4, the temperature difference between the air and the refrigerant in the upwind flattened tube group 31 can be suppressed with a simple structure, and rapid blockage by frost can be sufficiently suppressed.

[0063] Embodiment 5. Embodiment 5 will be described below, but the explanation will be omitted for parts that overlap with Embodiments 1 to 4, and the same reference numerals will be used for parts that are the same as or corresponding to Embodiments 1 to 4.

[0064] Figure 13 is a schematic perspective view showing the refrigerant flow when the heat exchanger 30 according to Embodiment 5 functions as an evaporator. Figure 14 is a schematic plan view of the flattened tube 38 of the heat exchanger 30 according to Embodiment 5. In Figure 13, the dashed arrows indicate the refrigerant flow, and the white arrows indicate the air flow direction. In Figure 13, components on the windward side of the heat exchanger 30 are labeled "A," and components on the leeward side are labeled "B." Figure 14(a) is a diagram of the windward flattened tube 38A, Figure 14(b) is a diagram of a modified example of the windward flattened tube 38A, and Figure 14(c) is a diagram of the leeward flattened tube 38B.

[0065] As shown in Figures 13 and 14, the heat exchanger 30 according to Embodiment 5 is configured such that the sum of the flow path cross-sectional areas S of the upwind flattened tube group 31A, that is, the sum of the flow path cross-sectional areas S of each flattened tube 38A, is smaller than the sum of the flow path cross-sectional areas S of the downwind flattened tube group 31B, that is, the sum of the flow path cross-sectional areas S of each flattened tube 38B. By making the sum of the flow path cross-sectional areas S of the upwind flattened tube group 31A smaller than the sum of the flow path cross-sectional areas S of the downwind flattened tube group 31B, the temperature difference between the air and the refrigerant in the upwind flattened tube group 31 can be suppressed with a simple structure, and rapid blockage by frost can be sufficiently suppressed.

[0066] In Embodiment 5, the heat exchanger 30 has two groups of flattened tubes 31 spaced apart in the airflow direction, but it is not limited to this and may have three or more. In that case, it is configured such that the sum of the flow path cross-sectional areas S of the furthest upwind group of flattened tubes 31 is smaller than the sum of the flow path cross-sectional areas S of the second furthest upwind group of flattened tubes 31.

[0067] As described above, in the heat exchanger 30 according to Embodiment 5, the sum of the flow path cross-sectional areas S of the flattened tube group 31 on the windward side is smaller than the sum of the flow path cross-sectional areas S of the flattened tube group 31 on the second windward side.

[0068] According to the heat exchanger 30 of Embodiment 5, the temperature difference between the air and the refrigerant in the upwind flattened tube group 31 can be suppressed with a simple structure, and rapid blockage by frost can be sufficiently suppressed. [Explanation of Symbols]

[0069] 10 Outdoor unit, 11 Compressor, 12 Flow path switching device, 13 Fan, 20 Indoor unit, 21 Throttle device, 22 Indoor heat exchanger, 23 Indoor fan, 30 Heat exchanger, 31 Flat tube group, 31A Flat tube group, 31B Flat tube group, 34 Lower header, 34A Lower header, 34Aa Lower refrigerant inlet / outlet, 34B Lower header, 34Ba Lower refrigerant inlet / outlet, 35 Upper header, 35A Upper header, 35Aa Upper refrigerant inlet / outlet, 35B Upper header, 35Ba Upper refrigerant inlet / outlet, 36 Row header, 36a Inner wall, 36b Protrusion, 37 Plate material, 37a Small hole, 38 Flat tube, 38A Flat tube, 38B Flat tube, 38a Upper end, 39 Corrugated fin, 41 Connecting piping, 42 Flow resistance element, 100 refrigeration cycle device, 101 refrigerant circuit.

Claims

1. It consists of multiple flattened tubes arranged vertically in the vertical direction and spaced apart in a direction perpendicular to the airflow direction, and multiple groups of flattened tubes arranged spaced apart in the airflow direction, Corrugated fins are arranged between each of the multiple flattened tubes in the group of the multiple flattened tubes, Each of the aforementioned group of flattened tubes comprises a pair of headers positioned above and below it, One of the pair of headers on the windward side has a refrigerant inlet formed therein when it functions as an evaporator. A temperature difference formation structure is provided between the group of flattened pipes on the windward side and the group of flattened pipes on the second windward side. heat exchanger.

2. The aforementioned temperature difference forming structure is A connecting pipe that connects one of the pair of headers on the windward side to the other of the pair of headers on the second windward side, A flow resistance body provided on the connecting pipe, The heat exchanger according to claim 1.

3. The aforementioned connecting pipe is This involves connecting the upper part of the pair of headers that is furthest upwind to the upper part of the pair of headers that is second furthest upwind, or connecting the lower part of the pair of headers that is furthest upwind to the lower part of the pair of headers that is second furthest upwind. The heat exchanger according to claim 2.

4. The aforementioned flow resistance body, It is a flow control valve. The heat exchanger according to claim 2 or 3.

5. The upper part of the pair of headers on the windward side and the upper part of the pair of headers on the second windward side, or the lower part of the pair of headers on the windward side and the lower part of the pair of headers on the second windward side, are composed of a common column pass header. The aforementioned temperature difference forming structure is The distance between the end of the furthest upwind group of flattened pipes and the end of the second furthest upwind group of flattened pipes, and the inner wall of the row-to-row header facing them, is set to 2 mm or less. The heat exchanger according to claim 1.

6. The upper part of the pair of headers on the windward side and the upper part of the pair of headers on the second windward side, or the lower part of the pair of headers on the windward side and the lower part of the pair of headers on the second windward side, are composed of a common column pass header. The aforementioned temperature difference forming structure is Within the aforementioned row-pass header, it is provided between the end of the furthest upwind group of flattened pipes and the end of the second furthest upwind group of flattened pipes, and is a plate material having multiple small holes formed in the direction in which the multiple flattened pipes are arranged side by side. The heat exchanger according to claim 1.

7. The aforementioned column-pass header is, It includes a plurality of protrusions that define the distance between the end of the furthest upwind group of flattened pipes and the end of the second furthest upwind group of flattened pipes, and the inner wall of the row-pass header facing them. The heat exchanger according to claim 5 or 6.

8. The sum of the flow cross-sectional areas of the flattened pipes on the windward side is smaller than the sum of the flow cross-sectional areas of the flattened pipes on the second windward side. A heat exchanger according to any one of claims 1 to 3.

9. A heat exchanger according to any one of claims 1 to 3 Outdoor unit of a refrigeration cycle system.

10. A compressor, an outdoor unit of the refrigeration cycle apparatus described in claim 9, a throttle device, and an indoor unit of the refrigeration cycle apparatus are connected by refrigerant piping and comprise a refrigerant circuit through which the refrigerant circulates. Refrigeration cycle device.

11. The aforementioned refrigerant is It is a single refrigerant of R1234yf, R1234ze, and R290, or a mixture of two or more of these, or a mixture of one of these with another refrigerant, a mixture containing R1132(E), or a mixture containing R1123. The refrigeration cycle apparatus according to claim 10.

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