Heat exchanger and refrigeration device

Abstract

This outdoor heat exchanger (20) comprises: an upwind tube row (55) and a downwind tube row (56) that are configured from a plurality of flat tubes (52); and fins (54) that have tube insertion parts (61) into which the flat tubes (52) are inserted. The fins (54) are arranged such that a tube insertion part (61) on the upwind-tube-row (55) side and a tube insertion part (61) on the downwind-tube-row (56) side face each other. The upwind tube row (55) is divided into an upwind main row section (55a) and an upwind auxiliary row section (55b), and the downwind tube row (56) is divided into a downwind main row section (56a) and a downwind auxiliary row section (56b). During use as an evaporator, refrigerant flows in order from the upwind auxiliary row section (55b) to the upwind main row section (55a). During use as a condenser, the refrigerant flows in order from the upwind main row section (55a) to the upwind auxiliary row section (55b).

Description

Heat exchanger and refrigeration apparatus

[0001] The present invention relates to a heat exchanger and a refrigeration apparatus.

[0002] A heat exchanger in which flat tubes are inserted into a plurality of notches formed on the long sides of fins is known. For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2019-132511) discloses a heat exchanger in which two heat exchange sections each constituted by a fin into which a flat tube is inserted are arranged side by side in the air flow direction.

[0003] When the heat exchanger of Patent Document 1, in which the exposed side of the flat tubes in the heat exchange section is arranged facing leeward, is used as an evaporator, there is no fin communication portion on the leeward side of the heat exchange section, which causes a problem in the drainage performance of condensed water. On the other hand, when a heat exchanger in which the exposed side of the flat tubes in the heat exchange section is arranged facing windward is used as an evaporator, the low-temperature flat tubes are exposed on the windward side, which causes a problem that frosting on the heat exchange section is accelerated.

[0004] A heat exchanger according to a first aspect includes a windward tube row, a leeward tube row, and fins. The windward tube row and the leeward tube row are each constituted by a plurality of flat tubes arranged in the vertical direction. The windward tube row and the leeward tube row are arranged in the air flow direction. Each fin has an opening formed on one of a pair of long sides that serves as an insertion port for a flat tube, and a tube insertion portion formed from the opening toward the other long side into which the flat tube is inserted. The flat tubes are joined to the fin in each of the windward tube row and the leeward tube row.

[0005] The fins are arranged such that the tube insertion portion of the windward tube row and the tube insertion portion of the leeward tube row face each other. The windward tube row is divided into a windward main row portion and a windward auxiliary row portion each constituted by a plurality of flat tubes arranged in the vertical direction. The leeward tube row is divided into a leeward main row portion and a leeward auxiliary row portion each constituted by a plurality of flat tubes arranged in the vertical direction. When used as an evaporator, the refrigerant flows in order from the windward auxiliary row portion to the windward main row portion. When used as a condenser, the refrigerant flows in order from the windward main row portion to the windward auxiliary row portion.

[0006] In the first type of heat exchanger, the side with exposed flat tubes in the upwind row and the side with exposed flat tubes in the downwind row face each other. As a result, since the flat tubes are not exposed on the upwind side of the heat exchanger, frost formation on the heat exchanger can be delayed. In addition, since the fin connections can be placed on the downwind side of the heat exchanger, the drainage performance of the heat exchanger can be improved.

[0007] The heat exchanger in the second aspect is the heat exchanger in the first aspect, and the refrigerant is a non-azeotropic mixed refrigerant.

[0008] When using a non-azeotropic refrigerant mixture, the refrigerant temperature tends to drop at the evaporator inlet side (liquid piping connection side) due to temperature glide, making frost formation more likely. In the heat exchanger described in the second perspective, the flat pipe is not exposed on the upwind side of the heat exchanger where the evaporator inlet is located, thus delaying frost formation on the heat exchanger when using a non-azeotropic refrigerant mixture.

[0009] A heat exchanger according to the third view is a heat exchanger according to the first or second view, further comprising a first header and a second header. The first header communicates with a plurality of flattened tubes constituting the upwind main row and a plurality of flattened tubes constituting the downwind main row. The second header communicates with a plurality of flattened tubes constituting the upwind auxiliary row and a plurality of flattened tubes constituting the downwind auxiliary row.

[0010] The heat exchanger in the fourth view is a heat exchanger in either the first or third view, wherein the heat transfer coefficient of the fins on the downwind side is higher than the heat transfer coefficient of the fins on the upwind side.

[0011] The leeward side of the piping row, through which dehumidified air passes from the windward side, is less prone to frost formation compared to the windward side. In the fourth aspect of the heat exchanger, the performance of the heat exchanger can be improved by increasing the heat transfer coefficient of the fins on the leeward side of the piping row.

[0012] The heat exchanger in the fifth view is a heat exchanger according to any of the first, fourth, or fourth views, wherein louvers or slits are formed on the fins on the downwind side of the pipe row.

[0013] In the fifth aspect of the heat exchanger, the performance of the heat exchanger can be improved.

[0014] The heat exchanger in the sixth view is a heat exchanger from either the first view or the fifth view, wherein the fins on the upwind side and the fins on the downwind side are arranged with a gap between them.

[0015] In the heat exchanger described in the sixth perspective, contact between the fins on the upwind side and the fins on the downwind side can be suppressed.

[0016] The refrigeration system according to the seventh aspect comprises a heat exchanger according to either the first or sixth aspect.

[0017] This is a schematic diagram of an air conditioning system according to one embodiment of a refrigeration system. This is a perspective view showing the external appearance of the air conditioning outdoor unit. This is a schematic top cross-sectional view illustrating the arrangement of each component of the air conditioning outdoor unit. This is a schematic external perspective view showing the outdoor heat exchanger. This is a schematic configuration diagram showing the flattened pipes and fins that constitute the outdoor heat exchanger. This is a diagram conceptually showing the flow of refrigerant in the upwind auxiliary row and the downwind auxiliary row. This is a diagram conceptually showing the flow of refrigerant in the upwind main row and the downwind main row.

[0018] (1) Overall configuration diagram 1 of the air conditioning system is a schematic configuration diagram of an air conditioning system 1 according to one embodiment of a refrigeration system.

[0019] The air conditioning system 1 is a device used for heating and cooling a building in which an indoor air conditioning unit 3 is installed, by operating a vapor compression type refrigeration cycle. The air conditioning system 1 is composed of an outdoor air conditioning unit 2 as a heat source unit and an indoor air conditioning unit 3 as a user unit, connected by refrigerant connecting pipes 6 and 7.

[0020] The refrigerant circuit, which is formed by connecting the outdoor unit 2, the indoor unit 3, and the refrigerant connecting pipes 6 and 7, consists of a compressor 91, a four-way switching valve 92, an outdoor heat exchanger 20, an expansion valve 33, an indoor heat exchanger 4, and an accumulator 93, all of which are connected by refrigerant piping. Refrigerant is sealed within this refrigerant circuit, and a refrigeration cycle operation is performed in which the refrigerant is compressed, cooled, depressurized, heated and evaporated, and then compressed again. The refrigerant sealed within the refrigerant circuit is a non-azeotropic mixed refrigerant, such as R454C. A non-azeotropic mixed refrigerant is a mixture of multiple types of refrigerants with different boiling points. In Figure 1, the air conditioning system 1 has one outdoor unit 2 and one indoor unit 3, but the number is merely illustrative. The air conditioning system 1 may have multiple outdoor units 2 or multiple indoor units 3.

[0021] (2) Detailed configuration of the air conditioning system (2-1) Indoor air conditioning unit The indoor air conditioning unit 3 is installed on the wall of a room by being mounted on the wall, or by being embedded in or suspended from the ceiling of a room in a building, etc. The indoor air conditioning unit 3 has an indoor heat exchanger 4 and an indoor fan 5. The indoor heat exchanger 4 is a cross-fin type fin-and-tube heat exchanger composed of, for example, heat transfer tubes and a large number of fins. The indoor heat exchanger 4 is a heat exchanger that functions as a refrigerant evaporator to cool the indoor air during cooling operation and as a refrigerant condenser to heat the indoor air during heating operation.

[0022] (2-2) Air Conditioning Outdoor Unit The air conditioning outdoor unit 2 is installed outside a building or the like and is connected to the air conditioning indoor unit 3 via refrigerant connecting pipes 6 and 7. As shown in Figures 2 and 3, the air conditioning outdoor unit 2 has a roughly rectangular parallelepiped unit casing 10.

[0023] In the following explanation, expressions such as "up," "down," "left," "right," "front," "back," "front view," and "rear view" may be used to describe directions and positional relationships. Unless otherwise specified, the directions indicated by these expressions follow the directions of the arrows shown in the drawings.

[0024] As shown in Figure 3, the air conditioning outdoor unit 2 has a structure (a so-called trunk-type structure) in which the internal space of the unit casing 10 is divided into two by a partition plate 18 extending vertically to form a blower room S1 and a machine room S2. The air conditioning outdoor unit 2 has an outdoor heat exchanger 20 and an outdoor fan 95 located in the blower room S1 of the unit casing 10. The air conditioning outdoor unit 2 also has a compressor 91, a four-way switching valve 92, an accumulator 93, an expansion valve 33, gas refrigerant piping 31, and liquid refrigerant piping 32 located in the machine room S2 of the unit casing 10.

[0025] The unit casing 10 comprises a bottom plate 12, a top plate 11, a side plate 13 on the blower room side, a side plate 14 on the machine room side, a front plate 15 on the blower room side, and a front plate 16 on the machine room side, forming the enclosure.

[0026] The air conditioning outdoor unit 2 is configured to draw in outdoor air from the back and a portion of the sides of the unit casing 10 into the fan chamber S1 inside the unit casing 10, and to blow out the drawn-in outdoor air from the front of the unit casing 10. Specifically, an intake port 10a, an intake port 10b, and an outlet port 10c are formed in the fan chamber S1 inside the unit casing 10. The entire intake ports 10a and 10b extend from the rear end of the side plate 13 on the fan chamber side to the end of the side plate 14 on the machine chamber side that is on the fan chamber S1 side. The outlet port 10c is provided on the front plate 15 on the fan chamber side, and its front side is covered by a fan grille 15a.

[0027] The compressor 91 is a sealed compressor driven by, for example, a compressor motor, and is configured to allow its operating capacity to be changed by inverter control. By changing the operating capacity in this way, it is possible to respond to fluctuations in the air conditioning load.

[0028] The four-way diverter valve 92 is a mechanism for switching the direction of refrigerant flow. During cooling operation, the four-way diverter valve 92 connects the refrigerant piping on the discharge side of the compressor 91 to the gas refrigerant piping 31 extending from one end (gas side end) of the outdoor heat exchanger 20, and also connects the refrigerant communication piping 7 of the gas refrigerant to the refrigerant piping on the suction side of the compressor 91 via the accumulator 93 (see the solid line of the four-way diverter valve 92 in Figure 1). During heating operation, the four-way diverter valve 92 connects the refrigerant piping on the discharge side of the compressor 91 to the gas refrigerant communication piping 7, and also connects the suction side of the compressor 91 to the gas refrigerant piping 31 extending from one end (gas side end) of the outdoor heat exchanger 20 via the accumulator 93 (see the dashed line of the four-way diverter valve 92 in Figure 1).

[0029] The outdoor heat exchanger 20 is an example of a heat exchanger. The outdoor heat exchanger 20 is positioned vertically in the fan chamber S1, facing the intake ports 10a and 10b. A gas refrigerant pipe 31 extends from one end (the gas side end) of the outdoor heat exchanger 20 to connect to a four-way switching valve 92. A liquid refrigerant pipe 32 extends from the other end (the liquid side end) of the outdoor heat exchanger 20 to connect to an expansion valve 33.

[0030] The accumulator 93 is connected between the four-way switching valve 92 and the compressor 91. The accumulator 93 has a gas-liquid separation function that separates the refrigerant into a gas phase and a liquid phase. The refrigerant flowing into the accumulator 93 is separated into a liquid phase and a gas phase, and the gas phase refrigerant that collects in the upper space is supplied to the compressor 91.

[0031] The expansion valve 33 is a mechanism for reducing the refrigerant pressure in the refrigerant circuit and is an electrically operated valve with adjustable opening. The expansion valve 33 is installed between the outdoor heat exchanger 20 and the liquid refrigerant refrigerant communication pipe 6 to adjust the refrigerant pressure and flow rate, and has the function of expanding the refrigerant during both cooling and heating operations.

[0032] The outdoor fan 95 supplies outdoor air to the outdoor heat exchanger 20 for heat exchange with the refrigerant flowing through the outdoor heat exchanger 20. The outdoor fan 95 is positioned in the fan chamber S1 facing the outdoor heat exchanger 20. The outdoor fan 95 draws outdoor air into the unit casing 10 from the rear side, allows heat exchange to occur between the refrigerant and the outdoor air in the outdoor heat exchanger 20, and then discharges the heat-exchanged air outside the unit casing 10 from the front side. This outdoor fan 95 is a fan capable of changing the airflow rate of the outdoor air supplied to the outdoor heat exchanger 20, and is, for example, a propeller fan driven by a motor such as a DC fan motor.

[0033] (3) Operation of the air conditioning system 1 (3-1) Cooling operation During cooling operation, the four-way switching valve 92 is in the state shown by the solid line in Figure 1. Specifically, the discharge side of the compressor 91 is connected to the gas side of the outdoor heat exchanger 20 via the gas refrigerant piping 31, and the suction side of the compressor 91 is connected to the gas side of the indoor heat exchanger 4 via the refrigerant connecting piping 7.

[0034] In this refrigerant circuit configuration, when the compressor 91, outdoor fan 95, and indoor fan 5 are operated, the low-pressure gaseous refrigerant is compressed by the compressor 91 to become high-pressure gaseous refrigerant. This high-pressure gaseous refrigerant is sent to the outdoor heat exchanger 20 via the four-way switching valve 92. Thereafter, the high-pressure gaseous refrigerant exchanges heat with the outdoor air supplied by the outdoor fan 95 in the outdoor heat exchanger 20 and condenses to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant is sent from the outdoor heat exchanger 20 to the expansion valve 33. The refrigerant, which is reduced in pressure by the expansion valve 33 to become a low-pressure gas-liquid two-phase state, is sent to the indoor heat exchanger 4, where it exchanges heat with the indoor air and evaporates to become low-pressure gaseous refrigerant. This low-pressure gaseous refrigerant is sent to the air conditioning outdoor unit 2 via the refrigerant communication pipe 7 and is again drawn into the compressor 91. In this way, during cooling operation, the air conditioning system 1 causes the outdoor heat exchanger 20 to function as a condenser for the refrigerant compressed in the compressor 91, and the indoor heat exchanger 4 to function as an evaporator for the refrigerant condensed in the outdoor heat exchanger 20.

[0035] (3-2) Heating Operation During heating operation, the four-way switching valve 92 is in the state shown by the dashed line in Figure 1. Specifically, the discharge side of the compressor 91 is connected to the gas side of the indoor heat exchanger 4 via the refrigerant communication pipe 7, and the suction side of the compressor 91 is connected to the gas side of the outdoor heat exchanger 20 via the gas refrigerant pipe 31.

[0036] In this refrigerant circuit configuration, when the compressor 91, outdoor fan 95, and indoor fan 5 are operated, the low-pressure gaseous refrigerant is drawn into the compressor 91 and compressed to become high-pressure gaseous refrigerant. This high-pressure gaseous refrigerant is sent to the air conditioning indoor unit 3 via the four-way switching valve 92 and the refrigerant communication piping 7. The high-pressure gaseous refrigerant sent to the air conditioning indoor unit 3 condenses in the indoor heat exchanger 4 through heat exchange with the indoor air to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant is sent from the indoor heat exchanger 4 to the expansion valve 33. The refrigerant, which is reduced in pressure by the expansion valve 33 to become a low-pressure gas-liquid two-phase state, is sent to the outdoor heat exchanger 20, where it evaporates through heat exchange with the outdoor air to become low-pressure gaseous refrigerant. This low-pressure gaseous refrigerant is drawn into the compressor 91 again via the four-way switching valve 92. In this way, during heating operation, the air conditioning system 1 causes the indoor heat exchanger 4 to function as a condenser for the refrigerant compressed in the compressor 91, and the outdoor heat exchanger 20 to function as an evaporator for the refrigerant condensed in the indoor heat exchanger 4.

[0037] (4) Detailed Configuration of the Outdoor Heat Exchanger 20 The outdoor heat exchanger 20 is a heat exchanger that performs heat exchange between the refrigerant and the outdoor air. The outdoor heat exchanger 20 functions as a condenser (heat radiator) during cooling operation and as an evaporator (heat absorber) during heating operation. Figure 4 is a schematic external perspective view showing the outdoor heat exchanger 20. Figure 5 is a schematic configuration diagram showing the flattened tubes 52 and fins 54 that constitute the outdoor heat exchanger 20. Figure 6A is a diagram conceptually showing the flow of refrigerant in the upwind auxiliary row section 55b and the downwind auxiliary row section 56b. Figure 6B is a diagram conceptually showing the flow of refrigerant in the upwind main row section 55a and the downwind main row section 56a. Note that the arrows showing the flow of refrigerant in Figures 4, 6A and 6B indicate the direction of refrigerant flow during heating operation (when the outdoor heat exchanger 20 functions as a refrigerant evaporator). During cooling or defrosting operation, the refrigerant flows in the opposite direction to the arrows indicating refrigerant flow shown in Figures 4, 6A, and 6B.

[0038] The outdoor heat exchanger 20 mainly comprises multiple rows (two rows in this case) of heat exchange sections 21 that exchange heat between outdoor air and refrigerant, an inlet / outlet header pipe 26, a folded header 24, a connecting header 23, a connecting section 25, and a flow divider 22. The inlet / outlet header pipe 26 and the folded header 24 are provided on the first end 27 side, which is one end in the extension direction of the heat exchange section 21. The connecting header 23 is provided on the second end 28 side, which is the other end in the extension direction of the heat exchange section 21. The connecting section 25 connects the lower space of the folded header 24 and the upper space of the folded header 24. The flow divider 22 is located below the inlet / outlet header pipe 26.

[0039] (4-1) Heat exchange section The heat exchange section 21 has an upwind heat exchange section 21a that is provided to frame the upwind portion in the direction of airflow generated by the outdoor fan 95 (flow from the back and left side of the housing toward the fan grill 15a on the front of the housing), and a downwind heat exchange section 21b that is provided to frame the downwind portion. In other words, the upwind heat exchange section 21a and the downwind heat exchange section 21b are arranged in two rows in the direction of airflow.

[0040] The upwind heat exchange section 21a extends along the upwind side and has a plurality of vertically aligned flat tubes 52 and fins 54 fixed to these flat tubes 52. Similarly, the downwind heat exchange section 21b extends along the downwind side and has a plurality of vertically aligned flat tubes 52 and fins 54 fixed to these flat tubes 52.

[0041] The flattened tubes 52 function as heat transfer tubes, transferring heat moving between the fins 54 and the outside air to the refrigerant flowing inside. The flattened tubes 52 are flattened multi-hole tubes having upper and lower flat surfaces 50 that serve as heat transfer surfaces and multiple inlets 51 through which the refrigerant flows (see Figure 5). In both the upwind heat exchange section 21a and the downwind heat exchange section 21b, the multiple flattened tubes 52 are arranged at predetermined intervals in the vertical direction. Hereinafter, the multiple flattened tubes 52 constituting the upwind heat exchange section 21a will be referred to as the upwind tube row 55, and the multiple flattened tubes 52 constituting the downwind heat exchange section 21b will be referred to as the downwind tube row 56.

[0042] The fins 54 are components that increase the heat transfer area of ​​the heat exchange section 21. The fins 54 divide the space between adjacent flat pipes 52 in the vertical direction into multiple air passages through which air flows. Multiple flat pipes 52 are joined to the fins 54. In both the upwind heat exchange section 21a and the downwind heat exchange section 21b, the multiple fins 54 are arranged in a line along the direction in which the flat pipes 52 extend. As shown in Figure 5, the fins 54 are flat plate members. Hereinafter, the multiple fins 54 constituting the upwind heat exchange section 21a (fins 54 on the upwind pipe row 55 side) will be called upwind fins 54a, and the multiple fins 54 constituting the downwind heat exchange section 21b (fins 54 on the downwind pipe row 56 side) will be called downwind fins 54b.

[0043] Each fin 54 mainly includes a plurality of openings 60, a plurality of tube insertion portions 61, and a communication portion 57. The opening 60 is a portion formed on one of the pair of long sides of the fin 54 and serves as an insertion opening for the flat tube 52. The tube insertion portion 61 is a portion formed from the opening 60 toward the other long side of the fin 54, into which the flat tube 52 is inserted. In other words, the tube insertion portion 61 is a notch for inserting the flat tube 52 extending in the horizontal direction. A plurality of tube insertion portions 61 are formed on each fin 54 so as to be arranged in the vertical direction. The shape of the tube insertion portion 61 substantially matches the outer shape of the cross-section of the flat tube 52. The flat tube 52 is inserted into the tube insertion portion 61 and fixed thereto by brazing or the like. The communication portion 57 is a part of the fin 54.

[0044] In the leeward fin 54b, a plurality of slits 59 are provided in the central portion 58b between two adjacent flat tubes 52. The slits 59 are portions cut and raised from the flat portion of the leeward fin 54b in the plate thickness direction in order to improve the heat transfer performance of the leeward fin 54b. In contrast, in the windward fin 54a, the central portion 58a between two adjacent flat tubes 52 is flat, and no slit 59 is provided. In other words, the thermal conductivity of the leeward fin 54b is configured to be higher than that of the windward fin 54a.

[0045] The pipe insertion section 61 of the upwind fin 54a has a flat pipe 52 from the upwind pipe row 55 inserted into it. The pipe insertion section 61 of the downwind fin 54b has a flat pipe 52 from the downwind pipe row 56 inserted into it. The upwind fin 54a and the downwind fin 54b are positioned with a gap between them. Furthermore, the pipe insertion section 61 of the upwind fin 54a (the pipe insertion section 61 on the upwind pipe row 55 side) and the pipe insertion section 61 of the downwind fin 54b (the pipe insertion section 61 on the downwind pipe row 56 side) are positioned to face each other. In other words, the opening 60 of the upwind fin 54a and the opening 60 of the downwind fin 54b are positioned to face each other. To put it another way, in the upwind heat exchange section 21a, the side where the flat pipes 52 of the upwind pipe row 55 are exposed and in the downwind heat exchange section 21b, the side where the flat pipes 52 of the downwind pipe row 56 are exposed are arranged to face each other. In the upwind fin 54a, the communication section 57 is a portion that extends continuously in the vertical direction further upwind than the upwind end of the flat pipe 52 of the upwind pipe row 55. In the downwind fin 54b, the communication section 57 is a portion that extends continuously in the vertical direction further downwind than the downwind end of the flat pipe 52 of the downwind pipe row 56.

[0046] An inlet / outlet header pipe 26 is located at the first end 27 of the upwind heat exchange section 21a. One end of each flat pipe 52 of the upwind pipe row 55 is connected to the inlet / outlet header pipe 26. In other words, the internal space of the inlet / outlet header pipe 26 is in communication with each flat pipe 52 that makes up the upwind pipe row 55. A connecting header 23 is located at the second end 28 of the upwind heat exchange section 21a. The other end of each flat pipe 52 of the upwind pipe row 55 is connected to the connecting header 23. In other words, the internal space of the connecting header 23 is in communication with each flat pipe 52 that makes up the upwind pipe row 55.

[0047] A turn-back header 24 is arranged on the first end 27 side of the leeward heat exchange section 21b. One end of each flat tube 52 of the leeward tube row 56 is connected to the turn-back header 24. In other words, the internal space of the turn-back header 24 communicates with each flat tube 52 constituting the leeward tube row 56. Further, a connection header 23 is arranged on the second end 28 side of the leeward heat exchange section 21b. The other end of each flat tube 52 of the leeward tube row 56 is connected to the connection header 23. In other words, the internal space of the connection header 23 communicates with each flat tube 52 constituting the leeward tube row 56.

[0048] (4-2) Flow divider 22 The flow divider 22 is connected so as to connect the liquid refrigerant pipe 32 and the lower part of the inlet / outlet header pipe 26. For example, when the outdoor heat exchanger 20 functions as a refrigerant evaporator, the flow divider 22 divides the refrigerant flowing in from the liquid refrigerant pipe 32 in the height direction. Each refrigerant flow divided by the flow divider 22 in this manner is guided to each height position of the lower part of the inlet / outlet header pipe 26. Further, for example, when the outdoor heat exchanger 20 functions as a refrigerant condenser, the refrigerant flowing in from the outdoor heat exchanger 20 merges and is guided to the liquid refrigerant pipe 32.

[0049] (4-3) Inlet / outlet header pipe 26 The inlet / outlet header pipe 26 is connected to the end of the windward heat exchange section 21a on the opposite side (first end 27 side) to the side where the connection header 23 is provided (second end 28 side). The inlet / outlet header pipe 26 is a cylindrical member extending in the vertical direction, and the interior thereof is divided into an upper part (hereinafter referred to as a first space SP1) and a lower part (hereinafter referred to as a second space SP2). Specifically, the interior of the inlet / outlet header pipe 26 is vertically partitioned by a baffle extending in the horizontal direction.

[0050] When the outdoor heat exchanger 20 functions as a refrigerant evaporator, the second space SP2 functions as a refrigerant inlet, and when the outdoor heat exchanger 20 functions as a refrigerant condenser, the second space SP2 functions as a refrigerant outlet. Further, when the outdoor heat exchanger 20 functions as a refrigerant evaporator, the first space SP1 functions as a refrigerant outlet, and when the outdoor heat exchanger 20 functions as a refrigerant condenser, the first space SP1 functions as a refrigerant inlet.

[0051] The second space SP2 is connected to the liquid refrigerant piping 32 via the flow divider 22. The first space SP1 is connected to the gaseous refrigerant piping 31.

[0052] Hereinafter, the multiple flattened pipes 52 of the upwind pipe row 55 connected to the first space SP1 will be referred to as the upwind main row 55a. Also, the multiple flattened pipes 52 of the upwind pipe row 55 connected to the second space SP2 will be referred to as the upwind auxiliary row 55b.

[0053] (4-4) Connecting Header 23 The connecting header 23 is provided on the second end 28 side of the upwind heat exchange section 21a and on the second end 28 side of the downwind heat exchange section 21b. In other words, the connecting header 23 is provided on the opposite side (the blower room side in Figure 3) of the outdoor heat exchanger 20 from the end on the side (the machine room side in Figure 3) where the inlet / outlet header pipes 26 and the folded header 24 of the heat exchange section 21 are provided. The connecting header 23 is a cylindrical member that extends vertically, and its interior is divided into an upper part (hereinafter referred to as the fifth space SP5) and a lower part (hereinafter referred to as the sixth space SP6). Specifically, the interior of the connecting header 23 is divided vertically by baffles that extend horizontally. Note that each of the fifth space SP5 and the sixth space SP6 may be further divided into multiple spaces by multiple baffles.

[0054] The connecting header 23 is configured to guide the refrigerant that has flowed through the flat pipes 52 of the upwind pipe row 55 to the flat pipes 52 of the downwind pipe row 56. Hereinafter, the multiple flat pipes 52 of the downwind pipe row 56, which are located at the same height as the multiple flat pipes 52 of the upwind main row 55a, will be referred to as the downwind main row 56a. The multiple flat pipes 52 of the downwind pipe row 56, which are located at the same height as the multiple flat pipes 52 of the upwind auxiliary row 55b, will be referred to as the downwind auxiliary row 56b. The flat pipes 52 of the upwind main row 55a and the downwind main row 56a are connected to the fifth space SP5. The flat pipes 52 of the upwind auxiliary row 55b and the downwind auxiliary row 56b are connected to the sixth space SP6. Hereinafter, the connecting header 23 that connects to the upwind main row 55a and the downwind main row 56a will be referred to as the first header 23a. The connecting header 23 that connects to the upwind auxiliary row section 55b and the downwind auxiliary row section 56b is called the second header 23b.

[0055] When the outdoor heat exchanger 20 is functioning as a refrigerant evaporator, the second header 23b is configured to guide the refrigerant that has flowed through the flat pipes 52 of the upwind auxiliary row 55b to the flat pipes 52 of the downwind auxiliary row 56b. The first header 23a is configured to guide the refrigerant that has flowed through the flat pipes 52 of the downwind main row 56a to the flat pipes 52 of the upwind main row 55a. When the outdoor heat exchanger 20 is functioning as a refrigerant condenser, the flow is reversed.

[0056] As described above, the direction of the refrigerant flow through the first header 23a and the direction of the refrigerant flow through the second header 23b are opposite to each other. In other words, the direction of the refrigerant flow in the upwind main row 55a and the direction of the refrigerant flow in the upwind auxiliary row 55b are opposite to each other. Also, the direction of the refrigerant flow in the downwind main row 56a and the direction of the refrigerant flow in the downwind auxiliary row 56b are opposite to each other.

[0057] (4-5) Folded Header 24 The folded header 24 is connected to the end of the downwind heat exchange section 21b that is opposite to the side where the connecting header 23 is provided (the second end 28 side) (the first end 27 side). The folded header 24 is a cylindrical member that extends vertically, and its interior is divided into an upper part (hereinafter referred to as the third space SP3) and a lower part (hereinafter referred to as the fourth space SP4). Specifically, the interior of the folded header 24 is divided vertically by baffles that spread horizontally. Note that each of the third space SP3 and the fourth space SP4 may be further divided into multiple spaces by multiple baffles. The flat pipe 52 of the downwind main row section 56a is connected to the third space SP3. The flat pipe 52 of the downwind auxiliary row section 56b is connected to the fourth space SP4. The third space SP3 and the fourth space SP4 are connected via connecting piping of the connecting section 25. In other words, the third space SP3 and the fourth space SP4 are connected.

[0058] When the outdoor heat exchanger 20 is functioning as a refrigerant evaporator, the refrigerant flowing into the fourth space SP4 is sent to the third space SP3 via the connecting pipe of the connecting section 25. However, when the outdoor heat exchanger 20 is functioning as a refrigerant condenser, the flow is reversed.

[0059] With the above configuration, the upwind main row 55a, the downwind main row 56a, the return header 24, the downwind auxiliary row 56b, and the upwind auxiliary row 55b are arranged in series in the refrigerant flow path.

[0060] (5) Refrigerant flow The refrigerant flow of the outdoor heat exchanger 20 having the above configuration will be described.

[0061] (5-1) Heating Operation During heating operation, the outdoor heat exchanger 20 functions as an evaporator for the refrigerant that has been depressurized in the expansion valve 33. During heating operation, the refrigerant flows in the direction of the arrows showing the flow of the refrigerant in Figures 4, 6A, and 6B.

[0062] The refrigerant, depressurized in the expansion valve 33, flows through the liquid refrigerant piping 32 of the refrigerant circuit and is sent to the second space SP2 of the inlet / outlet header pipe 26. The refrigerant sent to the second space SP2 is divided into a plurality of flat pipes 52 (flat pipes 52 of the upwind auxiliary row section 55b) that communicate with the second space SP2. The refrigerant that flows through the flat pipes 52 of the upwind auxiliary row section 55b is sent to the sixth space SP6 of the second header 23b. The refrigerant sent to the sixth space SP6 flows into the flat pipes 52 of the downwind auxiliary row section 56b that communicate with the sixth space SP6. The refrigerant that flows through the flat pipes 52 of the downwind auxiliary row section 56b is sent to the fourth space SP4 of the return header 24. The refrigerant sent to the fourth space SP4 is sent to the third space SP3 of the return header 24 via the connecting piping of the connecting section 25. The refrigerant sent to the third space SP3 is divided into a plurality of flat pipes 52 (flat pipes 52 in the downwind main row section 56a) that communicate with the third space SP3. The refrigerant that has flowed through the flat pipes 52 in the downwind main row section 56a is sent to the fifth space SP5 of the first header 23a. The refrigerant sent to the fifth space SP5 flows into the flat pipes 52 in the upwind main row section 55a that communicate with the fifth space SP5. The refrigerant that has flowed through the flat pipes 52 in the upwind main row section 55a is sent to the first space SP1 of the inlet / outlet header pipe 26. The refrigerant sent to the first space SP1 is sent to the compressor 91 through the gas refrigerant piping 31.

[0063] As described above, when the outdoor heat exchanger 20 is used as an evaporator, the refrigerant flows sequentially from the upwind auxiliary row 55b to the upwind main row 55a. In this case, in the section where the refrigerant flows sequentially from the downwind main row 56a to the upwind main row 55a, the airflow and the refrigerant flow in the outdoor heat exchanger 20 form a counterflow relationship as a whole.

[0064] (5-2) Cooling Operation During cooling operation, the outdoor heat exchanger 20 functions as a condenser for the refrigerant discharged from the compressor 91. During cooling operation, the refrigerant flows in the opposite direction to the arrows indicating the flow of refrigerant in Figures 4, 6A, and 6B.

[0065] The refrigerant discharged from the compressor 91 is sent to the first space SP1 of the inlet / outlet header pipe 26 through the gas refrigerant piping 31 of the refrigerant circuit. The refrigerant sent to the first space SP1 is divided into a plurality of flat pipes 52 (flat pipes 52 of the upwind main row section 55a) that communicate with the first space SP1. The refrigerant that has flowed through the flat pipes 52 of the upwind main row section 55a is sent to the fifth space SP5 of the first header 23a. The refrigerant sent to the fifth space SP5 flows into the flat pipes 52 of the downwind main row section 56a that communicate with the fifth space SP5. The refrigerant that has flowed through the flat pipes 52 of the downwind main row section 56a is sent to the third space SP3 of the return header 24. The refrigerant that has been sent to the third space SP3 is sent to the fourth space SP4 of the return header 24 via the connecting piping of the connecting section 25. The refrigerant sent to the fourth space SP4 is divided and flows into a plurality of flat pipes 52 (flat pipes 52 of the downwind auxiliary row section 56b) that communicate with the fourth space SP4. The refrigerant that flows through the flat pipes 52 of the downwind auxiliary row section 56b is sent to the sixth space SP6 of the second header 23b. The refrigerant sent to the sixth space SP6 flows into the flat pipes 52 of the upwind auxiliary row section 55b that communicate with the sixth space SP6. The refrigerant that flows through the flat pipes 52 of the upwind auxiliary row section 55b is sent to the second space SP2 of the inlet / outlet header pipe 26. The refrigerant sent to the second space SP2 is sent to the expansion valve 33 through the liquid refrigerant piping 32.

[0066] As described above, when the outdoor heat exchanger 20 is used as a condenser, the refrigerant flows sequentially from the upwind main row 55a to the upwind auxiliary row 55b. In this case, in the section where the refrigerant flows sequentially from the downwind auxiliary row 56b to the upwind auxiliary row 55b, the airflow and the refrigerant flow in the outdoor heat exchanger 20 form a counterflow relationship as a whole.

[0067] During defrost operation, the outdoor heat exchanger 20 functions as a condenser for the refrigerant discharged from the compressor 91, just as it does during cooling operation. The refrigerant flow in the outdoor heat exchanger 20 during defrost operation is the same as during cooling operation, so a detailed explanation is omitted here.

[0068] (6) Features (6-1) The outdoor heat exchanger 20 of this embodiment comprises an upwind pipe row 55 and a downwind pipe row 56, and fins 54. The upwind pipe row 55 and the downwind pipe row 56 are each composed of a plurality of flat pipes 52 arranged in the vertical direction. The upwind pipe row 55 and the downwind pipe row 56 are arranged in the direction of airflow. The fins 54 have an opening 60 formed on one of a pair of long sides which serves as an insertion point for the flat pipes 52, and a pipe insertion portion 61 formed from the opening 60 toward the other long side into which the flat pipes 52 are inserted. The flat pipes 52 are joined to the fins 54 in each of the upwind pipe row 55 and the downwind pipe row 56.

[0069] The fins 54 are arranged such that the pipe insertion portion 61 on the upwind pipe row 55 side and the pipe insertion portion 61 on the downwind pipe row 56 side face each other. The upwind pipe row 55 is divided into an upwind main row 55a and an upwind auxiliary row 55b, each composed of multiple flat pipes 52 arranged vertically. The downwind pipe row 56 is divided into a downwind main row 56a and a downwind auxiliary row 56b, each composed of multiple flat pipes 52 arranged vertically. When used as an evaporator, the refrigerant flows sequentially from the upwind auxiliary row 55b to the upwind main row 55a. When used as a condenser, the refrigerant flows sequentially from the upwind main row 55a to the upwind auxiliary row 55b.

[0070] In this outdoor heat exchanger 20, the side of the flat pipes 52 exposed in the upwind pipe row 55 and the side of the flat pipes 52 exposed in the downwind pipe row 56 are arranged to face each other. As a result, the flat pipes 52 are not exposed on the upwind side of the outdoor heat exchanger 20, which can delay frost formation on the outdoor heat exchanger 20. In addition, the connecting portion 57 of the fins 54 can be arranged on the downwind side of the outdoor heat exchanger 20, which can improve the drainage performance of the outdoor heat exchanger 20. Furthermore, whether the outdoor heat exchanger 20 functions as a condenser or an evaporator, the performance of the heat exchanger can be improved by having a portion in which the airflow and the refrigerant flow in the outdoor heat exchanger 20 are in a counterflow relationship as a whole.

[0071] (6-2) In the outdoor heat exchanger 20 of this embodiment, the refrigerant is a non-azeotropic mixed refrigerant.

[0072] When using a non-azeotropic refrigerant mixture, the refrigerant temperature tends to drop at the evaporator inlet side (liquid piping connection side) due to temperature glide, making frost formation more likely. In this outdoor heat exchanger 20, the flat pipe 52 is not exposed on the upwind side of the outdoor heat exchanger 20 where the evaporator inlet side is located, thus delaying frost formation on the outdoor heat exchanger 20 when using a non-azeotropic refrigerant mixture.

[0073] (6-3) The outdoor heat exchanger 20 of this embodiment further comprises a first header 23a and a second header 23b. The first header 23a communicates with a plurality of flat pipes 52 constituting the upwind main row 55a and a plurality of flat pipes 52 constituting the downwind main row 56a. The second header 23b communicates with a plurality of flat pipes 52 constituting the upwind auxiliary row 55b and a plurality of flat pipes 52 constituting the downwind auxiliary row 56b.

[0074] (6-4) In this embodiment, the outdoor heat exchanger 20 has a higher heat transfer coefficient for the fins 54 on the downwind pipe row 56 side (downwind fins 54b) than for the fins 54 on the upwind pipe row 55 side (upwind fins 54a).

[0075] The downwind pipe row 56, through which dehumidified air passes on the upwind pipe row 55 side, is less prone to frost formation compared to the upwind pipe row 55 side. In this outdoor heat exchanger 20, by increasing the heat transfer coefficient of the fins 54 on the downwind pipe row 56 side, it is possible to suppress frost formation on the outdoor heat exchanger 20 while improving the performance of the outdoor heat exchanger 20.

[0076] (6-5) In this embodiment, the outdoor heat exchanger 20 has slits 59 formed in the fins 54 on the leeward pipe row 56 side (leeward fins 54b). This increases the heat transfer coefficient of the fins 54 on the leeward pipe row 56 side, thereby improving the performance of the outdoor heat exchanger 20.

[0077] (6-6) In this embodiment, the outdoor heat exchanger 20 is arranged with a gap between the fins 54 on the windward pipe row 55 side (windward fin 54a) and the fins 54 on the leeward pipe row 56 side (leeward fin 54b). This prevents the fins 54 on the windward pipe row 55 side and the fins 54 on the leeward pipe row 56 side from coming into contact.

[0078] (6-7) An example of a refrigeration system in this embodiment is an air conditioning system 1 which includes an outdoor heat exchanger 20 in this embodiment.

[0079] (7) Modifications The above embodiments can be modified as appropriate, for example, as shown in the following modifications. Each modification may be combined with other modifications as appropriate, within the limits of what is not contradictory.

[0080] (7-1) Modification A In the above embodiment, the refrigerant sealed in the refrigerant circuit was a non-azeotropic mixed refrigerant. However, the type of refrigerant may be a single refrigerant such as R32, HFO1234yf, HFO1234ze(E) or a mixture thereof, or a natural refrigerant, etc.

[0081] (7-2) Modification B In the above embodiment, a case was described in which a plurality of slits 59 are provided in the central portion 58b of the leeward fin 54b as a structure to promote heat exchange. However, the structure to promote heat exchange is not limited to slits 59. For example, the structure to promote heat exchange may be a louver cut and raised at an angle to the plane of the fin 54. Alternatively, the structure to promote heat exchange may be a waffle composed of a raised portion and a non-raised portion. The waffle is composed of a raised portion and a non-raised portion. The raised portion is a portion that is raised in the thickness direction of the fin 54. The non-raised portion is a flat portion that is not raised in the thickness direction of the fin 54. In the central portion 58b of the leeward fin 54b, louvers and / or a waffle may be provided instead of the slits 59, or in addition to the slits 59.

[0082] (7-3) Modification C In the above embodiment, the case in which the central portion 58a of the windward fin 54a is flat was described. However, a slit may be provided in the central portion 58a of the windward fin 54a. Alternatively, louvers and / or waffles may be provided in place of a slit, or in addition to a slit, in the central portion 58a of the windward fin 54a.

[0083] In this modified example, the performance of the outdoor heat exchanger 20 can be improved.

[0084] (7-4) Modification D In the above embodiment, the heat exchange portion 21 of the outdoor heat exchanger 20 is formed in an L-shape by being bent at one place, but it is not limited to this. For example, the heat exchange portion 21 may be bent at two places to form a substantially U-shape. Also, the heat exchange portion 21 may be bent at three or more places.

[0085] (7-5) Modification E In the above embodiment, the refrigeration system was described using the air conditioning system 1 as an example, but the features of the above embodiment may be applied to other types of refrigeration systems. For example, the features of the above embodiment may be applied to a hot water supply system as an example of a refrigeration system.

[0086] (7-6) Modification F In the above embodiment, the air conditioning outdoor unit 2 is a trunk-type horizontal-blowing unit, which draws in outdoor air from the back and a part of the sides of the unit casing 10 and blows out air from the front of the unit casing 10. However, the air conditioning outdoor unit 2 is not limited to the horizontal-blowing type, and may be an upward-blowing unit, for example.

[0087] (7-7) Modification G In the above embodiment, the internal space of the inlet / outlet header pipe 26 is divided into a first space SP1 and a second space SP2 by a baffle. In other words, the first space SP1 and the second space SP2 are formed by dividing the same object with a baffle. However, the first space SP1 and the second space SP2 of the inlet / outlet header pipe 26 may each be formed by separate objects.

[0088] (7-8) Modification H In the above embodiment, the internal space of the folded header 24 is divided into a third space SP3 and a fourth space SP4 by a baffle. In other words, the third space SP3 and the fourth space SP4 are formed by dividing the same object with a baffle. However, the third space SP3 and the fourth space SP4 of the folded header 24 may each be formed from separate objects.

[0089] (7-9) Modification I In the above embodiment, the internal space of the connecting header 23 is divided into a fifth space SP5 and a sixth space SP6 by a baffle. In other words, the first header 23a and the second header 23b are made of the same material. However, the first header 23a and the second header 23b may each be made of separate materials.

[0090] While embodiments and variations of this disclosure have been described above, it should be understood that various changes in form and details are possible without departing from the spirit and scope of this disclosure as described in the claims.

[0091] 1 Air conditioning system (refrigeration system) 20 Outdoor heat exchanger (heat exchanger) 23 Connecting header 23a First header 23b Second header 52 Flat pipe 54 Fin 54a Upwind fin 54b Downwind fin 55 Upwind pipe row 55a Upwind main row 55b Upwind auxiliary row 56 Downwind pipe row 56a Downwind main row 56b Downwind auxiliary row 59 Slit 60 Opening 61 Pipe insertion section

[0092] Japanese Patent Publication No. 2019-132511

Claims

1. Each of the upwind and downwind rows of pipes (56) is composed of a plurality of flattened pipes (52) arranged vertically and arranged in the direction of airflow, and the upwind row of pipes (55) and downwind row of pipes (56) are composed of a plurality of flattened pipes (52) arranged vertically, and each of the upwind and downwind rows of pipes has an opening (60) formed on one of the long sides of a pair of pipes that serves as an insertion point for the flattened pipes, and a pipe insertion section (61) formed from the opening toward the other long side into which the flattened pipes are inserted, and the flattened pipes are joined to each other in the upwind and downwind rows, wherein the pipe insertion section on the upwind row side and the pipe insertion section on the downwind row side are arranged facing each other, and the upwind row of pipes is divided into an upwind main row (55a) and an upwind auxiliary row (55b), each composed of a plurality of flattened pipes arranged vertically, The downwind row of pipes is divided into a downwind main row (56a) and a downwind auxiliary row (56b), each composed of a plurality of flattened pipes arranged vertically, and when used as an evaporator, the refrigerant flows sequentially from the upwind auxiliary row to the upwind main row, and when used as a condenser, the refrigerant flows sequentially from the upwind main row to the upwind auxiliary row, in a heat exchanger (20).

2. The heat exchanger according to claim 1, wherein the refrigerant is a non-azeotropic mixed refrigerant.

3. The heat exchanger according to claim 1 or 2, further comprising: a first header (23a) communicating with a plurality of flat pipes constituting the upwind main row and a plurality of flat pipes constituting the downwind main row; and a second header (23b) communicating with a plurality of flat pipes constituting the upwind auxiliary row and a plurality of flat pipes constituting the downwind auxiliary row.

4. The heat exchanger according to any one of claims 1 to 3, wherein the heat transfer coefficient of the fins on the downwind side of the pipe row is higher than the heat transfer coefficient of the fins on the upwind side of the pipe row.

5. The heat exchanger according to any one of claims 1 to 4, wherein louvers or slits (59) are formed in the fins on the downwind pipe row side.

6. The heat exchanger according to any one of claims 1 to 5, wherein the fins on the upwind side and the fins on the downwind side are arranged with a gap between them.

7. A refrigeration apparatus (1) comprising a heat exchanger (20) according to any one of claims 1 to 6.

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