Refrigeration cycle device

Abstract

This refrigeration cycle device comprises a refrigerant circuit in which a compressor, a flow path switching device, a first heat exchanger, a throttle device, and a second heat exchanger are connected by refrigerant piping, and through which a refrigerant circulates. The first heat exchanger comprises: a plurality of flat tubes disposed side by side in the horizontal direction with intervals therebetween and extending in the vertical direction, and through which the refrigerant flows; an upper header that is provided above the plurality of flat tubes such that upper end parts of the plurality of flat tubes each protrude into the upper header, and that has formed therein a refrigerant inflow port; and a lower header that is provided below the plurality of flat tubes and has formed therein a refrigerant outflow port. The flow path switching device is configured to cause the refrigerant to flow into the refrigerant inflow port and cause the refrigerant to flow out of the refrigerant outflow port when the first heat exchanger functions either as an evaporator or as a condenser.

Description

Refrigeration cycle equipment

[0001] The present disclosure relates to a refrigeration cycle device including a heat exchanger having a plurality of flat tubes.

[0002] BACKGROUND ART Conventionally, a refrigeration cycle apparatus provided with a heat exchanger having improved refrigerant distribution performance has been proposed (see, for example, Patent Document 1).

[0003] The heat exchanger of Patent Document 1 includes a heat exchange element having a plurality of flat tubes arranged at intervals in the horizontal direction, an upper header provided at the upper end of the heat exchange element, and a lower header provided at the lower end of the heat exchange element. The heat exchanger also includes a partition plate provided inside at least one of the upper header and the lower header, which divides the heat exchange element into a plurality of horizontal regions. The partition plates are arranged so that each region is in counterflow with the adjacent region, and the cross-sectional area of ​​each region decreases from the upstream side to the downstream side of the refrigerant flow when functioning as a condenser.

[0004] According to this heat exchanger, by reducing the flow path cross-sectional area of ​​each region from the upstream to the downstream of the refrigerant flow when functioning as a condenser, it is possible to suppress a decrease in flow rate even if the liquid phase of the refrigerant increases, thereby suppressing stagnation of the liquid phase of the refrigerant and improving refrigerant distribution performance.

[0005] International Publication No. 2021 / 234958

[0006] However, the heat exchanger of Patent Document 1 has a partition plate provided inside the header, which increases pressure loss inside the header. Furthermore, if a partition plate is not provided inside the header, when the heat exchanger functions as an evaporator and a two-phase gas-liquid refrigerant flows in through an inlet formed at one end of the header, the liquid phase of the refrigerant will be biased toward the other end of the header due to inertia, resulting in a problem of poor distribution performance.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a refrigeration cycle device that improves refrigerant distribution performance while suppressing pressure loss in a heat exchanger.

[0008] The refrigeration cycle device of the present disclosure comprises a refrigerant circuit in which a compressor, a flow path switching device, a first heat exchanger, a throttling device, and a second heat exchanger are connected by refrigerant piping and through which a refrigerant circulates, and the first heat exchanger comprises a plurality of flat tubes arranged in parallel horizontally at intervals and extending vertically, through which the refrigerant flows, an upper header provided above the plurality of flat tubes so that the upper ends of the plurality of flat tubes each protrude inward, and having a refrigerant inlet formed therein, and a lower header provided below the plurality of flat tubes and having a refrigerant outlet formed therein, and the flow path switching device is configured to allow the refrigerant to flow into the refrigerant inlet and to flow out from the refrigerant outlet, both when the first heat exchanger functions as an evaporator and when it functions as a condenser.

[0009] In the refrigeration cycle apparatus according to the present disclosure, the flow path switching device is configured to allow refrigerant to flow into the refrigerant inlet and out of the refrigerant outlet, whether the first heat exchanger functions as an evaporator or a condenser. Therefore, when the first heat exchanger functions as an evaporator, a two-phase refrigerant flows into the upper header. However, the liquid refrigerant collides with the upper ends of the flat tubes, weakening the inertial force. This improves refrigerant distribution performance even without a partition plate inside the header. As a result, refrigerant distribution performance can be improved while suppressing pressure loss in the heat exchanger.

[0010] 1 is a refrigerant circuit diagram showing a refrigeration cycle apparatus including a heat exchanger according to embodiment 1. FIG. 2 is a front view schematically showing a refrigerant flow when the heat exchanger according to embodiment 1 functions as an evaporator. FIG. 3 is a front view schematically showing a refrigerant flow and a flow path switching device when the heat exchanger according to embodiment 2 functions as an evaporator. FIG. 4 is a front view schematically showing a refrigerant flow and a flow path switching device when the heat exchanger according to embodiment 3 functions as an evaporator. FIG. 5 is a front view schematically showing a refrigerant flow and a flow path switching device when the heat exchanger according to embodiment 4 functions as an evaporator. FIG. 6 is a perspective view schematically showing a refrigerant flow when the heat exchanger according to embodiment 5 functions as an evaporator. FIG. 7 is a perspective view showing a heat exchanger according to embodiment 6.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the embodiments described below. Furthermore, the size relationships between components in the drawings may differ from those in reality. Furthermore, in the following description, terms indicating directions, such as "upper," "lower," "right," "left," "front," and "rear," are used as appropriate to facilitate understanding, but these terms are for explanatory purposes and do not limit the embodiments. Furthermore, in the embodiments, "upper," "lower," "right," "left," "front," and "rear" are used when viewing the heat exchanger from the front.

[0012] Embodiment 1. <Configuration of refrigeration cycle apparatus 100> Fig. 1 is a refrigerant circuit diagram showing a refrigeration cycle apparatus 100 including a heat exchanger 30 according to embodiment 1. Note that solid arrows in Fig. 1 indicate the refrigerant flow during cooling operation, and dashed arrows in Fig. 1 indicate the refrigerant flow during heating operation.

[0013] First, a refrigeration cycle apparatus 100 including a heat exchanger 30 will be described with reference to Figure 1. In the first embodiment, an air conditioner is illustrated as the refrigeration cycle apparatus 100, but the refrigeration cycle apparatus 100 is used for refrigeration or air conditioning purposes, such as refrigerators, freezers, vending machines, air conditioners, refrigeration systems, and water heaters. Note that the refrigerant circuit 110 shown in the figure is merely an example, and the configuration of the circuit elements is not limited to the contents described in the embodiment, and can be modified as appropriate within the scope of the technology related to the embodiment.

[0014] The heat exchanger 30 according to the first embodiment is mounted on the outdoor unit 10 of a refrigeration cycle apparatus 100 that includes an outdoor unit 10 and an indoor unit 20. The outdoor unit 10 includes a compressor 11, a flow path switching device 40, and a heat exchanger 30 (hereinafter also referred to as a first heat exchanger). The indoor unit 20 includes an expansion device 21 and an indoor heat exchanger 22 (hereinafter also referred to as a second heat exchanger).

[0015] The refrigeration cycle apparatus 100 includes a refrigerant circuit 110 in which a refrigerant circulates, in which a compressor 11, a flow path switching device 40, a heat exchanger 30, a throttling device 21, and an indoor heat exchanger 22 are sequentially connected by refrigerant piping. The refrigeration cycle apparatus 100 can perform both cooling and heating operations by switching the flow path switching device 40.

[0016] The compressor 11 draws in a low-temperature, low-pressure refrigerant, compresses the drawn 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 refrigeration per unit time, is controlled by changing the operating frequency.

[0017] The flow path switching device 40 is composed of two four-way valves 41, 42, and switches between cooling operation and heating operation by switching the direction of refrigerant flow through these valves. During cooling operation, the flow path switching device 40 switches the two four-way valves 41, 42 to the states shown by solid lines in Fig. 1, connecting the discharge side of the compressor 11 to the heat exchanger 30. During heating operation, the flow path switching device 40 switches the two four-way valves 41, 42 to the states shown by dashed lines in Fig. 1, connecting the discharge side of the compressor 11 to the indoor heat exchanger 22.

[0018] The heat exchanger 30 exchanges heat between the outdoor air and the refrigerant. During cooling operation, the heat exchanger 30 functions as a condenser that radiates heat from the refrigerant to the outdoor air to condense the refrigerant. During heating operation, the heat exchanger 30 evaporates the refrigerant and cools the outdoor air with the heat of vaporization.

[0019] The expansion device 21 is, for example, an electronic expansion valve that can adjust the opening of the expansion valve, and by adjusting the opening, the pressure of the heat exchanger 30 or the refrigerant flowing into the heat exchanger 30 is controlled. In the first embodiment, the expansion device 21 is provided in the outdoor unit 10, but it may also be provided in the indoor unit 20, and the installation location is not limited.

[0020] The indoor heat exchanger 22 exchanges heat between the indoor air and the refrigerant. During cooling operation, the indoor heat exchanger 22 functions as an evaporator that evaporates the refrigerant and cools the outdoor air with the heat of vaporization. During heating operation, the indoor heat exchanger 22 functions as a condenser that radiates heat from the refrigerant to the outdoor air to condense the refrigerant.

[0021] Next, the flow of the refrigerant during each operation of the refrigeration cycle apparatus 100 will be described with reference to FIG.

[0022] <Cooling Operation> The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the heat exchanger 30 via the four-way valves 41, 42 of the flow switching device 40. The high-temperature, high-pressure gas refrigerant that has flowed into the heat exchanger 30 exchanges heat with outdoor air taken in by a fan (not shown), condenses while releasing heat, and becomes a low-temperature, high-pressure liquid refrigerant, which flows out of the heat exchanger 30. The low-temperature, high-pressure liquid refrigerant that has flowed out of the heat exchanger 30 flows into the expansion device 21 via the four-way valve 42 of the flow switching device 40, is decompressed by the expansion device 21, and becomes a low-temperature, low-pressure two-phase gas-liquid refrigerant that flows into the indoor heat exchanger 22. The low-temperature, low-pressure two-phase gas-liquid refrigerant that has flowed into the indoor heat exchanger 22 exchanges heat with indoor air taken in by the indoor fan (not shown), evaporates while absorbing heat, cools the indoor air, and flows out of the indoor heat exchanger 22 as a low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant flowing out from the indoor heat exchanger 22 is drawn into the compressor 11 via the four-way valve 41 of the flow path switching device 40, and becomes high-temperature, high-pressure gas refrigerant again.

[0023] <Heating Operation> The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 22 via the four-way valve 41 of the flow switching device 40. The high-temperature, high-pressure gas refrigerant that has flowed into the indoor heat exchanger 22 exchanges heat with indoor air taken in by an indoor fan (not shown) and condenses while releasing heat, heating the indoor air and becoming a low-temperature, high-pressure liquid refrigerant that flows out of the indoor heat exchanger 22. The low-temperature, high-pressure liquid refrigerant that has flowed out of the indoor heat exchanger 22 flows into the expansion device 21, where it is decompressed to become a low-temperature, low-pressure two-phase gas-liquid refrigerant, and flows into the heat exchanger 30 via the four-way valve 42 of the flow switching device 40. The low-temperature, low-pressure two-phase gas-liquid refrigerant that has flowed into the heat exchanger 30 exchanges heat with the outdoor air taken in by the fan (not shown), evaporating while absorbing heat, and becoming a low-temperature, low-pressure gas refrigerant that flows out of the heat exchanger 30. The low-temperature, low-pressure gas refrigerant flowing out of the heat exchanger 30 is drawn into the compressor 11 via the four-way valves 42 and 41 of the flow path switching device 40, and becomes high-temperature, high-pressure gas refrigerant again.

[0024] 2 is a front view schematically illustrating the flow of refrigerant when the heat exchanger 30 according to the first embodiment functions as an evaporator. The arrows in FIG. 2 indicate the flow of refrigerant.

[0025] As shown in FIG. 2 , the heat exchanger 30 includes a plurality of flat tubes 31 and a plurality of fins 32. The flat tubes 31 have a flat shape and are formed with a plurality of flow paths (not shown) arranged in a row through which a refrigerant flows. The flat tubes 31 are spaced apart and arranged in parallel in a horizontal direction (left-right direction in FIG. 2 ), which is perpendicular to the airflow direction, so that air generated by a fan (not shown) can flow through them. The refrigerant flows vertically through the tubes extending in a vertical direction (up-down direction in FIG. 2 ). The fins 32 are connected between adjacent flat tubes 31 and transfer heat to the flat tubes 31. The fins 32 improve the heat exchange efficiency between the air and the refrigerant, and are, for example, corrugated fins. However, the present invention is not limited to this. Because heat exchange between the air and the refrigerant occurs on the surfaces of the flat tubes 31, the fins 32 may be omitted.

[0026] An upper header 33 extending in the horizontal direction is provided at the upper ends 31 a of the flat tubes 31. The upper ends 31 a of the flat tubes 31 are directly inserted into the upper header 33. A lower header 34 extending in the horizontal direction is provided at the lower ends 31 b of the flat tubes 31. The lower ends 31 b of the flat tubes 31 are directly inserted into the lower header 34. Note that hereinafter, when there is no need to distinguish between the upper header 33 and the lower header 34, they will be referred to as headers.

[0027] A refrigerant inlet 33a is formed at one longitudinal (horizontal) end of the upper header 33, and an inlet pipe 35 is provided at the refrigerant inlet 33a. A refrigerant outlet 34a is formed at one longitudinal (horizontal) end of the lower header 34, and an outlet pipe 36 is provided at the refrigerant outlet 34a. The heat exchanger 30 is connected to a refrigerant circuit 110 of the refrigeration cycle apparatus 100 via the inlet pipe 35 and the outlet pipe 36.

[0028] The flat tubes 31, the fins 32, the lower header 34, and the upper header 33 are all made of aluminum, for example, and are joined by brazing.

[0029] The flow path switching device 40 is configured so that the refrigerant flows in through the refrigerant inlet 33a of the upper header 33 of the heat exchanger 30 and flows out through the refrigerant outlet 34a of the lower header 34, whether the refrigeration cycle apparatus 100 is in cooling operation or heating operation. In other words, the flow path switching device 40 is configured so that the refrigerant flows into the refrigerant inlet 33a and flows out through the refrigerant outlet 34a, whether the heat exchanger 30 functions as an evaporator or a condenser.

[0030] As shown in FIG. 2 , the upper ends 31 a of the flat tubes 31 each protrude upward from the bottom of the upper header 33 and are positioned in the upper distribution space 33 c within the upper header 33. Therefore, when the heat exchanger 30 functions as an evaporator, the liquid-phase LR of the gas-liquid two-phase refrigerant collides with the upper ends 31 a before the refrigerant flowing from the refrigerant inlet 33 a into the upper distribution space 33 c is distributed to the flat tubes 31, weakening the inertial force. After colliding with the upper ends 31 a, only the portion of the liquid-phase LR of the gas-liquid two-phase refrigerant that overcomes the upper ends 31 a passes above the upper ends 31 a and flows to the rear side (the side opposite the refrigerant inlet 33 a). Therefore, the inertial force of the refrigerant flowing from the refrigerant inlet 33 a into the upper distribution space 33 c prevents the liquid-phase LR of the gas-liquid two-phase refrigerant from flowing toward the rear and being distributed excessively toward the rear, thereby improving refrigerant distribution performance. Furthermore, because no partition plate is provided inside the header, pressure loss within the header is reduced.

[0031] Furthermore, when the heat exchanger 30 functions as a condenser, the refrigerant flows in through the refrigerant inlet 33a and flows out through the refrigerant outlet 34a, causing the refrigerant flow inside the flat tubes 31 to become a downward flow, and the liquid film formed inside the flat tubes 31 becomes thinner due to the influence of gravity, thereby improving heat transfer performance.

[0032] As described above, whether the heat exchanger 30 functions as an evaporator or a condenser, by configuring the heat exchanger 30 so that the refrigerant flows into the refrigerant inlet 33a and flows out from the refrigerant outlet 34a, the refrigerant distribution performance can be improved, pressure loss inside the header can be suppressed, and heat transfer performance can be improved.

[0033] As described above, the refrigeration cycle apparatus 100 according to the first embodiment includes a refrigerant circuit 110 in which the compressor 11, the flow path switching device 40, the first heat exchanger, the throttling device 21, and the second heat exchanger are connected by refrigerant piping, and in which the refrigerant circulates. The first heat exchanger includes a plurality of flat tubes 31 arranged in parallel horizontally at intervals, with the refrigerant flowing through the tubes extending in the vertical direction, an upper header 33 provided at the top of the plurality of flat tubes 31 so that the upper ends 31a of the plurality of flat tubes 31 protrude inward, and having a refrigerant inlet 33a formed therein, and a lower header 34 provided at the bottom of the plurality of flat tubes 31 and having a refrigerant outlet 34a formed therein. The flow path switching device 40 is configured to allow the refrigerant to flow into the refrigerant inlet 33a and to flow out from the refrigerant outlet 34a, whether the first heat exchanger functions as an evaporator or a condenser.

[0034] In the refrigeration cycle apparatus 100 according to the first embodiment, the flow path switching device 40 is configured to allow refrigerant to flow into the refrigerant inlet 33a and flow out of the refrigerant outlet 34a, regardless of whether the first heat exchanger functions as an evaporator or a condenser. Therefore, when the first heat exchanger functions as an evaporator, a gas-liquid two-phase refrigerant flows into the upper header 33. However, the liquid-phase refrigerant (LR) collides with the upper ends 31a of the flat tubes 31, weakening the inertial force. This improves distribution performance even without a partition plate inside the header. As a result, refrigerant distribution performance can be improved while suppressing pressure loss in the first heat exchanger.

[0035] Second Embodiment A second embodiment will be described below, but explanations of parts that overlap with those of the first embodiment will be omitted, and parts that are the same as or equivalent to those of the first embodiment will be given the same reference numerals.

[0036] 3 is a front view schematically illustrating the refrigerant flow and the flow path switching device 40 when the heat exchanger 30 according to the second embodiment functions as an evaporator. In FIG. 3, thin solid arrows and thick solid arrows indicate the refrigerant flow during cooling operation, and dashed arrows and thick solid arrows indicate the refrigerant flow during heating operation.

[0037] 3 , the flow path switching device 40 according to the second embodiment is configured with three on-off valves 43, 44, and 45, which are opened and closed to switch between cooling operation and heating operation. During cooling operation, the on-off valves 43 and 45 are closed and the on-off valve 44 is opened, connecting the discharge side of the compressor 11 to the plurality of heat exchangers 30. During heating operation, the flow path switching device 40 is configured with the on-off valves 43 and 45 open and the on-off valve 44 is closed, connecting the discharge side of the compressor 11 to the indoor heat exchanger 22.

[0038] As described above, by configuring the flow path switching device 40 with three on-off valves 43, 44, and 45, the flow path switching device 40 can be configured at a lower cost than in embodiment 1, in which the flow path switching device 40 is configured with two four-way valves 41 and 42.

[0039] As described above, in the refrigeration cycle apparatus 100 according to the second embodiment, the flow path switching device 40 includes the three on-off valves 43 , 44 , and 45 .

[0040] According to the refrigeration cycle device 100 of embodiment 2, by configuring the flow path switching device 40 with three on-off valves 43, 44, and 45, the flow path switching device 40 can be configured at a lower cost than in embodiment 1, in which the flow path switching device 40 is configured with two four-way valves 41 and 42.

[0041] Third Embodiment Hereinafter, a third embodiment will be described, but explanations of parts that overlap with those of the first and second embodiments will be omitted, and parts that are the same as or equivalent to those of the first and second embodiments will be denoted by the same reference numerals.

[0042] 4 is a front view schematically illustrating the refrigerant flow and the flow path switching device 40 when the heat exchanger 30 according to the third embodiment functions as an evaporator. Note that the thin solid arrows and thick solid arrows in FIG. 4 indicate the refrigerant flow during cooling operation, and the dashed arrows and thick solid arrows indicate the refrigerant flow during heating operation.

[0043] 4 , the flow path switching device 40 according to the third embodiment is composed of one on-off valve 46 and two check valves 47, 48, and switches between cooling operation and heating operation by opening and closing the on-off valve 46. During cooling operation, the on-off valve 46 is switched to a closed state, connecting the discharge side of the compressor 11 to the heat exchanger 30. During heating operation, the on-off valve 46 is switched to an open state, connecting the discharge side of the compressor 11 to the indoor heat exchanger 22.

[0044] As described above, by configuring the flow path switching device 40 with one on-off valve 46 and two check valves 47 and 48, the flow path switching device 40 can be configured at a lower cost than in embodiment 1, which is configured with two four-way valves 41 and 42.

[0045] As described above, in the refrigeration cycle apparatus 100 according to the third embodiment, the flow path switching device 40 includes one on-off valve 46 and two check valves 47 and 48 .

[0046] According to the refrigeration cycle device 100 of embodiment 3, the flow path switching device 40 is configured with one on-off valve 46 and two check valves 47, 48, so that the flow path switching device 40 can be configured at a lower cost than in embodiment 1, in which the flow path switching device 40 is configured with two four-way valves 41, 42.

[0047] Fourth Embodiment A fourth embodiment will be described below, but explanations of parts that overlap with those of the first to third embodiments will be omitted, and parts that are the same as or equivalent to those of the first to third embodiments will be given the same reference numerals.

[0048] 5 is a front view schematically illustrating the refrigerant flow and the flow path switching device 40 when the heat exchanger 30 according to the fourth embodiment functions as an evaporator. In FIG. 5, thin solid arrows and thick solid arrows indicate the refrigerant flow during cooling operation, and dashed arrows and thick solid arrows indicate the refrigerant flow during heating operation.

[0049] As shown in FIG. 5 , the flow path switching device 40 according to the fourth embodiment is configured with two on-off valves 49, 50 and one flow rate adjustment valve 51, and switches between cooling and heating operation by opening and closing these valves. The refrigeration cycle apparatus 100 according to the fourth embodiment also includes multiple (two in the fourth embodiment) heat exchangers 30, which are connected in parallel. During cooling operation, the flow path switching device 40 switches the on-off valve 49 and the flow rate adjustment valve 51 to a closed state and the on-off valve 45 to an open state, thereby connecting the discharge side of the compressor 11 to the multiple heat exchangers 30. During heating operation, the flow path switching device 40 switches the on-off valve 49 and the flow rate adjustment valve 51 to an open state and the on-off valve 50 to a closed state, thereby connecting the discharge side of the compressor 11 to the indoor heat exchanger 22. While the flow path switching device 40 according to the fourth embodiment is configured with two on-off valves 49, 50 and one flow rate adjustment valve 51, the configuration is not limited thereto. The two on-off valves 49 and 50 may be flow rate adjusting valves, and the flow path switching device 40 only needs to be equipped with at least one flow rate adjusting valve.

[0050] As described above, by configuring the flow path switching device 40 to include at least one flow control valve 51, the flow control valve 51 can adjust the refrigerant flow rate through the multiple heat exchangers 30 connected in parallel to match the thermal load of the heat exchangers 30.

[0051] As described above, in the refrigeration cycle apparatus 100 according to the fourth embodiment, the flow path switching device 40 includes at least one flow rate adjustment valve 51 .

[0052] According to the refrigeration cycle device 100 of embodiment 4, the flow path switching device 40 is configured to include at least one flow control valve 51, so that the flow control valve 51 can adjust the refrigerant flow rate through the multiple heat exchangers 30 connected in parallel in accordance with the thermal load of the heat exchangers 30.

[0053] Fifth Embodiment Hereinafter, a fifth embodiment will be described, but explanations of parts that overlap with those of the first to fourth embodiments will be omitted, and parts that are the same as or equivalent to those of the first to fourth embodiments will be given the same reference numerals.

[0054] Fig. 6 is a perspective view schematically illustrating the flow of refrigerant when heat exchanger 30 according to embodiment 5 functions as an evaporator. In Fig. 6, dashed arrows indicate the refrigerant flow, and hollow arrows indicate the air flow direction.

[0055] As shown in Fig. 6, the refrigeration cycle apparatus 100 according to the fifth embodiment includes a plurality of heat exchangers 30A, 30B (two in the fifth embodiment) spaced apart in the air flow direction. The refrigerant outlet 34Aa of the lower header 34A of one of the adjacent heat exchangers 30A, 30B is connected to the refrigerant inlet 33Ba of the upper header 33B of the other heat exchanger 30B by a connecting pipe 60. Similarly, when the refrigeration cycle apparatus 100 includes three or more heat exchangers 30 spaced apart in the air flow direction, the refrigerant outlet 34a of the lower header 34 of one of the adjacent heat exchangers 30 is connected to the refrigerant inlet 33a of the upper header 33 of the other heat exchanger 30 by the connecting pipe 60. In other words, the plurality of heat exchangers 30 are connected in series.

[0056] As described above, by connecting a plurality of heat exchangers 30 in series, it is possible to improve the refrigerant distribution performance when the plurality of heat exchangers 30 function as evaporators.

[0057] As described above, in the refrigeration cycle device 100 according to embodiment 5, a plurality of first heat exchangers are provided at intervals in the air flow direction, and of two first heat exchangers adjacent to each other in the air flow direction, the refrigerant outlet 34a of the lower header 34 of one of the first heat exchangers is connected to the refrigerant inlet 33a of the upper header 33 of the other first heat exchanger by a connecting pipe 60.

[0058] According to the refrigeration cycle device 100 of embodiment 5, by configuring multiple first heat exchangers to be connected in series, the refrigerant distribution performance can be improved when multiple first heat exchangers function as evaporators.

[0059] Sixth Embodiment A sixth embodiment will be described below, but explanations of parts that overlap with those of the first to fifth embodiments will be omitted, and parts that are the same as or equivalent to those of the first to fifth embodiments will be given the same reference numerals.

[0060] 7 is a perspective view showing a heat exchanger 30 according to a sixth embodiment. As shown in FIG. 7 , the heat exchanger 30 according to the sixth embodiment has an L-shape in plan view, and L-bend portions 38, 39 are provided in the upper header 33 and the lower header 34. By providing the L-bend portions 38, 39 in the upper header 33 and the lower header 34 in this manner, refrigerant distribution performance can be improved by agitating the refrigerant at the upper ends 31 a of the flat tubes 31, thereby preventing deviation of the liquid refrigerant due to centrifugal force at the L-bend portion 38 of the upper header 33. Furthermore, since there is no need to additionally install a distribution improvement structure inside the header, L-bend processing of the header is easy.

[0061] As described above, in the refrigeration cycle apparatus 100 according to the sixth embodiment, the first heat exchanger has an L-shape in plan view.

[0062] According to the refrigeration cycle apparatus 100 of the sixth embodiment, the uneven distribution of the liquid refrigerant caused by centrifugal force at the L-bend portion 38 of the upper header 33 can be improved by stirring the refrigerant at the upper ends 31 a of the flat tubes 31. Furthermore, since there is no need to additionally install a distribution improvement structure inside the header, it is easy to perform L-bending processing on the header.

[0063] Seventh Embodiment Hereinafter, a seventh embodiment will be described, but explanations of parts that overlap with those of the first to sixth embodiments will be omitted, and parts that are the same as or equivalent to those of the first to sixth embodiments will be given the same reference numerals.

[0064] In the seventh embodiment, the refrigerant flowing through the refrigerant circuit 110 is a single refrigerant selected from R1234yf, R1234ze, and R290. Use of such a refrigerant is expected to improve performance by improving distribution of mixed refrigerants and low-boiling-point refrigerants, which are prone to performance degradation in the heat exchanger 30. Note that low-boiling-point refrigerants have low vapor density and high flow velocity, which increases the influence of inertia force, thereby significantly improving refrigerant distribution performance.

[0065] As described above, in the refrigeration cycle apparatus 100 according to the seventh embodiment, the refrigerant is a single refrigerant selected from R1234yf, R1234ze, and R290.

[0066] According to the refrigeration cycle apparatus 100 of the seventh embodiment, by using the above-mentioned refrigerant, it is possible to expect performance improvement due to improved distribution of mixed refrigerants and low-boiling-point refrigerants, which are prone to performance degradation in the heat exchanger 30. Note that low-boiling-point refrigerants have low vapor density and high flow velocity, which increases the influence of inertial force, and therefore the effect of improving refrigerant distribution performance can be increased.

[0067] Eighth Embodiment An eighth embodiment will be described below, but explanations of parts that overlap with those of the first to seventh embodiments will be omitted, and parts that are the same as or equivalent to those of the first to seventh embodiments will be given the same reference numerals.

[0068] In the eighth embodiment, the refrigerant flowing through the refrigerant circuit 110 is a mixed refrigerant of two or more of R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, R459A, R474A, and R479A. By using the above refrigerant, the effect of improving the performance by improving the refrigerant distribution performance can be enhanced, since the mixed refrigerant causes concentration variations due to poor distribution.

[0069] As described above, in the refrigeration cycle apparatus 100 according to the eighth embodiment, the refrigerant is a mixed refrigerant of two or more of R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, R459A, R474A, and R479A.

[0070] According to the refrigeration cycle device 100 of embodiment 8, by using the above-mentioned refrigerant, the effect of improving the performance by improving the distribution performance of the refrigerant can be enhanced, since concentration variations occur in mixed refrigerants due to deterioration of distribution.

[0071] Ninth Embodiment A ninth embodiment will be described below, but explanations of parts that overlap with those of the first to eighth embodiments will be omitted, and parts that are the same as or equivalent to those of the first to eighth embodiments will be given the same reference numerals.

[0072] In the ninth embodiment, the refrigerant flowing through the refrigerant circuit 110 is a mixed refrigerant of two or more of R1234yf, R1234ze, and R290, a mixed refrigerant of any of these with another refrigerant, a mixed refrigerant including R1132(E), or a mixed refrigerant including R1123. By using the above refrigerant, the effect of improving the refrigerant distribution performance can be enhanced because the low-boiling-point refrigerant has a low vapor density and a high flow velocity, which increases the influence of inertia. Furthermore, because poor distribution of the mixed refrigerant causes concentration variations, the effect of improving the refrigerant distribution performance can be enhanced.

[0073] As described above, in the refrigeration cycle apparatus 100 according to the ninth embodiment, the refrigerant is a mixed refrigerant of two or more of R1234yf, R1234ze, and R290, or a mixed refrigerant of any of these with another refrigerant, a mixed refrigerant containing R1132(E), or a mixed refrigerant containing R1123.

[0074] According to the refrigeration cycle apparatus 100 of the ninth embodiment, by using the above-mentioned refrigerant, the effect of inertia is increased due to the low vapor density and high flow velocity of the low-boiling-point refrigerant, and therefore the improvement in refrigerant distribution performance can be enhanced. Furthermore, since the concentration of a mixed refrigerant varies due to poor distribution, the improvement in refrigerant distribution performance can be enhanced.

[0075] REFERENCE SIGNS LIST 10 Outdoor unit, 11 Compressor, 20 Indoor unit, 21 Throttle device, 22 Indoor heat exchanger, 30 Heat exchanger, 30A Heat exchanger, 30B Heat exchanger, 31 Flat tube, 31A Flat tube, 31B Flat tube, 31a Upper end, 31b Lower end, 32 Fin, 33 Upper header, 33Aa Refrigerant inlet, 33B Upper header, 33Ba Refrigerant inlet, 33a Refrigerant inlet, 33c Upper distribution space, 34 Lower header, 34A Lower header, 34Aa Refrigerant outlet, 34B Lower header, 34Ba Refrigerant inlet, 34a Refrigerant outlet, 35 Inlet pipe, 36 Outlet pipe, 38 L-bend portion, 39 L-bend portion, 40 Flow path switching device, 41 Four-way valve, 42 Four-way valve, 43 On-off valve, 44 On-off valve, 45 On-off valve, 46 On-off valve, 47 Check valve, 48 Check valve, 49 On-off valve, 50 On-off valve, 51 Flow rate adjustment valve, 60 Connecting pipe, 100 Refrigeration cycle device, 110 Refrigerant circuit.

Claims

1. A refrigeration cycle apparatus comprising a refrigerant circuit in which a refrigerant circulates, in which a compressor, a flow path switching device, a first heat exchanger, a throttling device, and a second heat exchanger are connected by refrigerant piping, wherein the first heat exchanger comprises: a plurality of flat tubes arranged horizontally in parallel at intervals and extending vertically, through which the refrigerant flows; an upper header provided above the plurality of flat tubes so that the upper ends of the plurality of flat tubes protrude inward, and having a refrigerant inlet; and a lower header provided below the plurality of flat tubes and having a refrigerant outlet, wherein the flow path switching device is configured to allow the refrigerant to flow into the refrigerant inlet and to flow out from the refrigerant outlet, both when the first heat exchanger functions as an evaporator and when it functions as a condenser.

2. The refrigeration cycle apparatus according to claim 1, wherein the flow path switching device is provided with three on-off valves.

3. The refrigeration cycle apparatus according to claim 1, wherein the flow path switching device comprises two on-off valves and one check valve.

4. The refrigeration cycle apparatus according to claim 1, wherein the flow path switching device comprises at least one flow rate adjustment valve.

5. A refrigeration cycle device according to any one of claims 1 to 4, comprising a plurality of the first heat exchangers spaced apart in the air flow direction, and wherein of two of the first heat exchangers adjacent to each other in the air flow direction, the refrigerant outlet of the lower header of one of the first heat exchangers is connected to the refrigerant inlet of the upper header of the other of the first heat exchangers by a connecting pipe.

6. The refrigeration cycle device according to any one of claims 1 to 5, wherein the first heat exchanger has an L-shape in plan view.

7. The refrigeration cycle device according to any one of claims 1 to 6, wherein the refrigerant is a single refrigerant selected from the group consisting of R1234yf, R1234ze, and R290.

8. The refrigeration cycle device according to any one of claims 1 to 6, wherein the refrigerant is a mixed refrigerant of two or more of R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, R459A, R474A, and R479A.

9. The refrigeration cycle device according to any one of claims 1 to 8, wherein the refrigerant is a mixed refrigerant of two or more of R1234yf, R1234ze, and R290, or a mixed refrigerant of any of these with another refrigerant, a mixed refrigerant containing R1132(E), or a mixed refrigerant containing R1123.

Images