Refrigeration cycle apparatus

Abstract

A non-azeotropic refrigerant mixture is handled.SOLUTION: The refrigeration cycle device 100 includes a bridge circuit 40. In the bridge circuit 40, the advancing direction of the refrigerant R is the same in both the cold heat utilization operation and the hot heat utilization operation. The bridge circuit 40 includes a first flow path AB, a second flow path BC, a third flow path DC, and a fourth flow path AD, and a first check valve 41, a second check valve 42, a third check valve 43, and a fourth check valve 44 provided in the respective flow paths. The flow path resistance of the fourth flow path AD is larger than the flow path resistance of the first flow path AB, or the flow path resistance of the third flow path DC is larger than the flow path resistance of the second flow path BC.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a refrigeration cycle device having a heat exchanger that handles a non-azeotropic refrigerant mixture, in which a counterflow is realized in which the non-azeotropic refrigerant mixture and air flow in opposite directions. [Background technology]

[0002] The refrigeration cycle apparatus disclosed in Patent Document 1 (JP 2009-222362 A) has a bridge circuit. Such a bridge circuit may be installed in a refrigeration cycle apparatus that uses a non-azeotropic refrigerant mixture. In this case, the bridge circuit functions to always keep the direction of flow of the refrigerant flowing through the heat source heat exchanger the same regardless of whether the refrigeration cycle apparatus is operating in cold energy utilization mode or hot energy utilization mode, thereby realizing counterflow in the heat source heat exchanger. Summary of the Invention [Problem to be solved by the invention]

[0003] A check valve is installed in the bridge circuit to maintain the same refrigerant flow direction. However, if the amount of refrigerant circulating in the refrigeration cycle system decreases, the refrigerant pressure difference between both ends of the check valve may become small. In this case, depending on the structure of the check valve, it may not open or close properly, which may impair the function of the bridge circuit to handle non-azeotropic refrigerant mixtures. [Means for solving the problem]

[0004] A refrigeration cycle device according to a first aspect includes a compressor, an expansion valve, a four-way switching valve, a first heat exchanger, a second heat exchanger, and a bridge circuit. The compressor compresses a refrigerant. The expansion valve decompresses the refrigerant. The four-way switching valve switches between a first operation and a second operation. The first heat exchanger has a refrigerant inlet and a refrigerant outlet. The first heat exchanger functions as a condenser in the first operation and as an evaporator in the second operation. The second heat exchanger functions as an evaporator in the first operation and as a condenser in the second operation. The bridge circuit allows the refrigerant to flow into the first heat exchanger at the refrigerant inlet and out of the first heat exchanger at the refrigerant outlet in both the first operation and the second operation.

[0005] The bridge circuit has a first node, a second node, a third node, a fourth node, a first flow path, a second flow path, a third flow path, a fourth flow path, a first check valve, a second check valve, a third check valve, and a fourth check valve.

[0006] The first flow path extends from the first node to the second node. The second flow path extends from the second node to the third node. The third flow path extends from the fourth node to the third node. The fourth flow path extends from the first node to the fourth node. The first check valve allows refrigerant to flow from the first node to the second node. The second check valve allows refrigerant to flow from the second node to the third node. The third check valve allows refrigerant to flow from the fourth node to the third node. The fourth check valve allows refrigerant to flow from the first node to the fourth node.

[0007] The first node is connected to the refrigerant outlet. The second node is connected to the compressor via a four-way valve. The third node is connected to the refrigerant inlet. The fourth node is connected to the expansion valve.

[0008] The flow path resistance of the fourth flow path is greater than the flow path resistance of the first flow path, or the flow path resistance of the third flow path is greater than the flow path resistance of the second flow path.

[0009] With this configuration, the flow path resistance of the third flow path or the fourth flow path is large. Therefore, even if the third check valve or the fourth check valve operates imperfectly due to, for example, a small amount of refrigerant circulating, the flow path resistance of the third flow path increases the pressure difference between the refrigerant on both ends of the fourth check valve, and the flow path resistance of the fourth flow path increases the pressure difference between the refrigerant on both ends of the third check valve, making it unlikely that the third check valve or the fourth check valve will malfunction.

[0010] A refrigeration cycle device of a second aspect is the refrigeration cycle device of the first aspect, wherein the flow path cross-sectional area of ​​the fourth flow path is smaller than the flow path cross-sectional area of ​​the first flow path, or the flow path cross-sectional area of ​​the third flow path is smaller than the flow path cross-sectional area of ​​the second flow path.

[0011] According to this configuration, the cross-sectional area of ​​the third flow path or the fourth flow path is small, which makes it possible to increase the flow resistance of the third flow path or the fourth flow path, making it less likely that the third check valve or the fourth check valve will malfunction.

[0012] A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first or second aspect, wherein the cross-sectional area of ​​the third flow path is smaller than the cross-sectional area of ​​the second flow path.

[0013] According to this configuration, the cross-sectional area of ​​the third flow path is small, which makes it possible to increase the flow resistance of the third flow path, making it less likely that the third check valve will malfunction.

[0014] A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to any one of the first aspect to the third aspect, wherein the cross-sectional area of ​​the fourth flow path is smaller than the cross-sectional area of ​​the first flow path.

[0015] According to this configuration, the flow path cross-sectional area of ​​the fourth flow path is small, which makes it possible to increase the flow path resistance of the fourth flow path, making it less likely that the fourth check valve will malfunction.

[0016] A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to any one of the first aspect to the fourth aspect, wherein the cross-sectional area of ​​the third flow path is smaller than 55% of the cross-sectional area of ​​the second flow path.

[0017] According to this configuration, the flow path cross-sectional area of ​​the third flow path is smaller than 55% of the flow path cross-sectional area of ​​the second flow path, which allows the flow path resistance of the third flow path to be significantly increased, thereby efficiently suppressing malfunction of the third check valve.

[0018] A refrigeration cycle apparatus according to a sixth aspect is the refrigeration cycle apparatus according to any one of the first aspect to the fifth aspect, wherein the cross-sectional area of ​​the fourth flow path is smaller than 55% of the cross-sectional area of ​​the first flow path.

[0019] According to this configuration, the flow path cross-sectional area of ​​the fourth flow path is smaller than 55% of the flow path cross-sectional area of ​​the first flow path, which allows the flow path resistance of the fourth flow path to be significantly increased, thereby efficiently suppressing malfunction of the fourth check valve.

[0020] A refrigeration cycle apparatus according to a seventh aspect is the refrigeration cycle apparatus according to any one of the first aspect to the sixth aspect, wherein the first heat exchanger is a heat source heat exchanger and the second heat exchanger is a utilization heat exchanger.

[0021] According to this configuration, the first heat exchanger is a heat source heat exchanger, and therefore, in the heat source heat exchanger, a counterflow can be realized in which the refrigerant and the air flow in opposite directions.

[0022] A refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to any one of the first aspect to the sixth aspect, wherein the first heat exchanger is a utilization heat exchanger and the second heat exchanger is a heat source heat exchanger.

[0023] According to this configuration, the first heat exchanger is a utilization heat exchanger, and therefore, in the utilization heat exchanger, a counterflow can be realized in which the refrigerant and the air flow in opposite directions.

[0024] A ninth aspect of the present invention is the refrigeration cycle device of any one of the first aspect to the eighth aspect, wherein the refrigerant is a non-azeotropic refrigerant mixture.

[0025] In this configuration, even in a case where the refrigerant is a non-azeotropic refrigerant mixture, the bridge circuit allows the refrigerant and air to flow in opposite directions regardless of the operating mode, thereby suppressing performance degradation of the refrigeration cycle device.

[0026] A refrigeration cycle device of a tenth aspect is the refrigeration cycle device of any one of the first aspect to the ninth aspect, wherein in the first operation or the second operation, the minimum value that the refrigerant circulation amount in the refrigeration cycle device can take is smaller than 35.00 kg / h.

[0027] With this configuration, even in cases where a small minimum value of the refrigerant circulation rate can cause the third or fourth check valve to operate imperfectly, the flow path resistance of the third or fourth flow path is large, so that malfunction of the third or fourth check valve can be suppressed. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic diagram showing the configuration of a refrigeration cycle device 100 according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a heat source heat exchanger 13. [Figure 3] 2 is a schematic diagram showing the configuration of a heat exchanger body 60. FIG. [Figure 4] 2 is a schematic diagram showing counterflows of refrigerant R and airflow AF in heat source heat exchanger 13. FIG. [Figure 5] 2 is a schematic diagram showing the operation of the refrigeration cycle device 100 in cold energy utilization operation. FIG. [Figure 6] FIG. 1 is a schematic diagram showing the operation of the refrigeration cycle device 100 in a heat utilization operation. [Figure 7] 10 is a graph showing temperature changes of refrigerant R and airflow AF during cold energy utilization operation. [Figure 8] 10 is a graph showing temperature changes of the refrigerant R and the airflow AF during the heat utilization operation. [Figure 9] 4 is a cross-sectional view showing the structure of a check valve 47. FIG. [Figure 10]FIG. 10 is a schematic diagram showing the configuration of a refrigeration cycle device 100A according to a second embodiment. [Figure 11] FIG. 10 is a schematic diagram showing the configuration of a refrigeration cycle device 100B according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] First Embodiment (1) Overall structure FIG. 1 shows the configuration of a refrigeration cycle apparatus 100 according to a first embodiment. The refrigeration cycle apparatus 100 provides a user with cold heat or hot heat obtained from a heat source by circulating a refrigerant R. The refrigeration cycle apparatus 100 provides a user with cold heat in a cold-heat utilization operation. The refrigeration cycle apparatus 100 provides a user with cold heat in a hot-heat utilization operation. The refrigeration cycle apparatus 100 can be configured in the form of an air conditioner, a refrigerator, a freezer, a water heater, a floor heating apparatus, or the like. When the refrigeration cycle apparatus 100 is an air conditioner, the cold-heat utilization operation and the hot-heat utilization operation correspond to cooling operation and heating operation, respectively. The refrigeration cycle apparatus 100 includes a heat source unit 10, a utilization unit 20, and a communication piping group 30.

[0030] (2) Detailed configuration (2-1) Refrigerant R Refrigerant R is a non-azeotropic refrigerant mixture. A non-azeotropic refrigerant mixture is a refrigerant made by mixing multiple refrigerant components with different boiling points. An example of refrigerant R is R454C. R454C is a mixture of R32 and R1234yf.

[0031] Non-azeotropic refrigerant mixtures exhibit significant temperature glide. Temperature glide is the range of temperature change that refrigerant R exhibits during the evaporation or condensation process. When a non-azeotropic refrigerant mixture evaporates, the low-boiling point component evaporates first, followed by the high-boiling point component. When a non-azeotropic refrigerant mixture condenses, the high-boiling point component condenses first, followed by the low-boiling point component. The existence of such multiple boiling points causes a large temperature glide.

[0032] (2-2) Heat source unit 10 The heat source unit 10 obtains cold or hot heat from air, which is a heat source. The heat source unit 10 includes a compressor 11, a four-way switching valve 12, a heat source heat exchanger 13, a heat source fan 14, a bridge circuit 40, a heat source expansion valve 15, an accumulator 16, a liquid shut-off valve 17, and a gas shut-off valve 18.

[0033] (2-2-1) Compressor 11 The compressor 11 has a suction pipe 11a and a discharge pipe 11b. The compressor 11 draws in the refrigerant R in a low-pressure gas state through the suction pipe 11a, compresses the refrigerant R, and discharges the refrigerant R in a high-pressure gas state from the discharge pipe 11b.

[0034] (2-2-2) Four-way switching valve 12 The four-way switching valve 12 switches between cold energy utilization operation and hot energy utilization operation by switching the direction of flow of the refrigerant R. When cold energy utilization operation is performed, the four-way switching valve 12 realizes the connection shown by the solid lines in Figure 1 and causes the refrigerant R to flow in the direction shown by the arrow CO. When hot energy utilization operation is performed, the four-way switching valve 12 realizes the connection shown by the dashed lines in Figure 1 and causes the refrigerant R to flow in the direction shown by the arrow HO.

[0035] (2-2-3) Heat source heat exchanger 13 and heat source fan 14 (2-2-3-1) Function The heat source heat exchanger 13 exchanges heat between the air, which is a heat source, and the refrigerant R, thereby causing the refrigerant R to acquire cold or hot heat. When cold heat utilization operation is performed, the heat source heat exchanger 13 functions as a condenser or radiator of the refrigerant R, causing the refrigerant R to acquire cold heat. When hot heat utilization operation is performed, the heat source heat exchanger 13 functions as an evaporator or heat absorber of the refrigerant R, causing the refrigerant R to acquire hot heat.

[0036] The heat source heat exchanger 13 has a refrigerant inlet 13a and a refrigerant outlet 13b. The refrigerant R enters the heat source heat exchanger 13 at the refrigerant inlet 13a and exits the heat source heat exchanger 13 at the refrigerant outlet 13b. The heat source fan 14 generates an airflow that passes through the heat source heat exchanger 13, thereby promoting heat exchange between the air and the refrigerant R. Note that, hereinafter, the term "condenser" includes use as a heat radiator that does not involve a phase change of the refrigerant R, and the term "evaporator" can include use as a heat absorber that does not involve a phase change of the refrigerant R.

[0037] (2-2-3-2) Structure 2 shows the structure of the heat source heat exchanger 13. The heat source heat exchanger 13 has a refrigerant inlet 13a and a refrigerant outlet 13b, as well as a flow divider 50, a heat exchanger body 60, and a flow confluence .

[0038] The flow divider 50 has a flow divider body 51 to which the pipe constituting the refrigerant inlet 13a is connected, and multiple branch pipes 56 extending from the flow divider body 51. The flow divider body 51 has one inlet 53 and multiple outlets 54. The refrigerant inlet 13a is connected to the inlet 53. The multiple branch pipes 56 are connected to the respective outlets 54. The refrigerant R flowing into the refrigerant inlet 13a is branched into the multiple branch pipes 56.

[0039] The heat exchanger body 60 is a portion where heat exchange between the refrigerant R and air occurs. The heat exchanger body 60 has a plurality of refrigerant paths 61 through which the refrigerant R flows. The plurality of refrigerant paths 61 include a lowest path 61L arranged at the lowest height and a highest path 61H arranged at the highest height. Each refrigerant path 61 has a refrigerant path inlet 62 and a refrigerant path outlet 63. The plurality of refrigerant path inlets 62 are each connected to the branch pipe 56.

[0040] The confluence 70 has a plurality of confluence pipes 75 and a confluence main body 76. Each confluence pipe 75 connects one refrigerant path outlet 63 to the confluence main body 76. The confluence main body 76 has an outlet pipe connection part 77 to which a pipe constituting the refrigerant outlet 13b is connected. The confluence 70 confluences the refrigerant R received from the plurality of refrigerant paths 61 and discharges it to the refrigerant outlet 13b.

[0041] 3 shows the configuration of the heat exchanger body 60. The heat exchanger body 60 has a plurality of heat transfer tubes 65 and a plurality of fins 67. Each heat transfer tube 65 is inserted into the through holes of all of the fins 67. The ends of two adjacent heat transfer tubes 65 are connected by a U-shaped tube 66. One refrigerant path 61 is made up of a plurality of heat transfer tubes 65 and a plurality of U-shaped tubes 66.

[0042] (2-2-3-3)Countercurrent 4 schematically shows the counterflow realized in the heat source heat exchanger 13 and the heat source fan 14. Counterflow means that the flow direction of the refrigerant R is opposite to the flow direction of the airflow AF. Realizing a counterflow in the heat source heat exchanger 13 is important for exchanging heat with the refrigerant R having a large temperature glide.

[0043] The refrigerant R flows into the heat source heat exchanger 13 through the refrigerant inlet 13a, is split by the flow splitter 50, passes through multiple refrigerant paths 61, joins at the flow junction 70, and exits the heat source heat exchanger 13 through the refrigerant outlet 13b. Each refrigerant path 61 has multiple heat transfer tubes 65, including heat transfer tubes 65 arranged in a first row L1 on the fin front end 671 side of the heat source heat exchanger 13 and heat transfer tubes 65 arranged in a second row L2 on the fin rear end 672 side. After flowing through the refrigerant inlet 13a, the refrigerant R always first passes through the heat transfer tubes 65 in the first row L1, then passes through the heat transfer tubes 65 in the second row L2, and finally exits through the refrigerant outlet 13b. In other words, the refrigerant R flows from the fin front end 671 side to the fin rear end 672 side.

[0044] In contrast, the airflow AF generated by the heat source fan 14 passes between adjacent fins 67 while proceeding from the fin rear end 672 side to the fin front end 671 side.

[0045] (2-2-4) Bridge circuit 40 Returning to FIG. 1 , the bridge circuit 40 is intended to ensure that the refrigerant R and the airflow AF always flow countercurrently in the heat source heat exchanger 13. In a refrigerant circuit without the bridge circuit 40, the direction of the refrigerant R flowing through the heat exchanger is reversed each time the cold heat utilization operation and the hot heat utilization operation are switched. In the refrigeration cycle device 100 of this embodiment, the bridge circuit 40 keeps the flow direction of the refrigerant R in the heat source heat exchanger 13 constant regardless of whether the cold heat utilization operation or the hot heat utilization operation is being performed. Thanks to the bridge circuit 40, regardless of whether the flow direction of the refrigerant R is the arrow CO or the arrow HO, the refrigerant R always enters the heat source heat exchanger 13 at the refrigerant inlet 13a and always exits the heat source heat exchanger 13 at the refrigerant outlet 13b.

[0046] The bridge circuit 40 has a first node A, a second node B, a third node C, and a fourth node D. The first node A is connected to the refrigerant outlet 13b. The second node B is connected to the compressor 11 via the four-way switching valve 12. The third node C is connected to the refrigerant inlet 13a. The fourth node D is connected to the heat source expansion valve 15.

[0047] Furthermore, the bridge circuit 40 has a first flow path AB extending from the first node A to the second node B, a second flow path BC extending from the second node B to the third node C, a third flow path DC extending from the fourth node D to the third node C, and a fourth flow path AD extending from the first node A to the fourth node D.

[0048] The bridge circuit 40 includes a first check valve 41, a second check valve 42, a third check valve 43, and a fourth check valve 44. These check valves maintain the same flow direction of the refrigerant R in the flow paths in which they are installed, preventing backflow of the refrigerant R. The first check valve 41 is provided in the first flow path AB and allows the refrigerant R to flow only in the direction from the first node A to the second node B. The second check valve 42 is provided in the second flow path BC and allows the refrigerant R to flow only in the direction from the second node B to the third node C. The third check valve 43 is provided in the third flow path DC and allows the refrigerant R to flow only in the direction from the fourth node D to the third node C. The fourth check valve 44 is provided in the fourth flow path AD and allows the refrigerant R to flow only in the direction from the first node A to the fourth node D.

[0049] (2-2-5) Heat source expansion valve 15 The heat source expansion valve 15 reduces the pressure of the refrigerant R. The heat source expansion valve 15 is configured as an electric valve whose opening size can be adjusted. When the opening size of the heat source expansion valve 15 is set small, the amount of refrigerant R that can pass through the heat source expansion valve 15 decreases, and the pressure of the refrigerant R after passing through the heat source expansion valve 15 decreases.

[0050] (2-2-6) Accumulator 16 Accumulator 16 allows only the gas component to pass through by storing only the liquid component contained in refrigerant R. Accumulator 16 is connected to suction pipe 11a of compressor 11, and prevents the liquid component of refrigerant R from damaging compressor 11.

[0051] (2-2-7) Liquid shutoff valve 17 and gas shutoff valve 18 The liquid shutoff valve 17 and the gas shutoff valve 18 are used to manually shut off the movement of the refrigerant R. The liquid shutoff valve 17 and the gas shutoff valve 18 are manually opened and closed by an installer of the refrigeration cycle apparatus 100.

[0052] (2-3) Usage unit 20 The utilization unit 20 provides the user with the cold or hot heat obtained from the heat source by the heat source unit 10. The utilization unit 20 has a utilization heat exchanger 23 and a utilization fan 24.

[0053] (2-3-1) Utilized heat exchanger 23 The utilization heat exchanger 23 provides cold or hot heat to the user by exchanging heat with the refrigerant R, such as the air in the user's environment or water used by the user. When performing cold heat utilization operation, the utilization heat exchanger 23 functions as an evaporator of the refrigerant R and provides cold heat to the user. When performing hot heat utilization operation, the utilization heat exchanger 23 functions as a condenser of the refrigerant R and provides hot heat to the user. As mentioned above, the term "condenser" here includes use as a heat radiator that does not involve a phase change of the refrigerant R, and the term "evaporator" can include use as a heat absorber that does not involve a phase change of the refrigerant R.

[0054] (2-3-2) 24 fans in use The utilization fan 24 is provided when a user utilizes cold or hot heat via air. The utilization fan 24 promotes heat exchange between the air and the refrigerant R by generating an air flow that passes through the utilization heat exchanger 23.

[0055] (2-4) Connecting piping group 30 The communication pipe group 30 connects the heat source unit 10 and the utilization unit 20, thereby forming a circulation path for the refrigerant R. The communication pipe group 30 has a liquid communication pipe 31 and a gas communication pipe 32. The liquid communication pipe 31 allows refrigerant R to pass mainly in a liquid state or a two-phase gas-liquid state. The liquid communication pipe 31 connects the liquid stop valve 17 and the utilization heat exchanger 23. The gas communication pipe 32 allows refrigerant R to pass mainly in a high-pressure gas state or a low-pressure gas state. The gas communication pipe 32 connects the gas stop valve 18 and the utilization heat exchanger 23.

[0056] (3) Overall operation (3-1)Cold heat utilization operation 5 shows the operation of the refrigeration cycle apparatus 100 in cold energy utilization operation. The four-way switching valve 12 realizes the connections shown in this figure, and causes the refrigerant R to flow in the direction indicated by the arrow CO.

[0057] The compressor 11 draws refrigerant R in a low-pressure gas state through the suction pipe 11a and discharges refrigerant R in a high-pressure gas state through the discharge pipe 11b. The refrigerant R in the high-pressure gas state passes through the four-way switching valve 12 and reaches the second node B of the bridge circuit 40. The refrigerant R then passes through the second check valve 42 and reaches the third node C. The refrigerant R then enters the heat-source heat exchanger 13 through the refrigerant inlet 13a. The heat-source heat exchanger 13 condenses the refrigerant R using the cold energy of the air to generate refrigerant R in a high-pressure liquid state. The refrigerant R in the high-pressure liquid state leaves the heat-source heat exchanger 13 through the refrigerant outlet 13b and then reaches the first node A. The refrigerant R then passes through the fourth check valve 44 and reaches the fourth node D. The refrigerant R in the high-pressure liquid state is then decompressed by the heat-source expansion valve 15 and becomes refrigerant R in a gas-liquid two-phase state. The refrigerant R then passes through the liquid shut-off valve 17 and the liquid connection pipe 31, and reaches the utilization heat exchanger 23. The utilization heat exchanger 23 evaporates the refrigerant R in a gas-liquid two-phase state, thereby providing the cold carried by the refrigerant R to the user and generating low-pressure gaseous refrigerant R. The refrigerant R then passes through the gas connection pipe 32, the gas shut-off valve 18, the four-way switching valve 12, and the accumulator 16 in this order, and is then drawn into the compressor 11 through the suction pipe 11a.

[0058] (3-2) Heat utilization operation 6 shows the operation of the refrigeration cycle apparatus 100 in the heat utilization operation. The four-way switching valve 12 realizes the connections shown in this figure, and causes the refrigerant R to flow in the direction indicated by the arrow HO.

[0059] The compressor 11 draws refrigerant R in a low-pressure gas state through the suction pipe 11a and discharges refrigerant R in a high-pressure gas state through the discharge pipe 11b. The high-pressure gas state refrigerant R passes through the four-way switching valve 12, the gas stop valve 18, and the gas connection pipe 32 in this order, and reaches the utilization heat exchanger 23. The utilization heat exchanger 23 condenses the high-pressure gas state refrigerant R to provide the heat carried by the refrigerant R to the user and generate high-pressure liquid state refrigerant R. The refrigerant R then passes through the liquid connection pipe 31 and the liquid stop valve 17, and reaches the heat-source expansion valve 15. The high-pressure liquid state refrigerant R is then decompressed in the heat-source expansion valve 15, becoming refrigerant R in a gas-liquid two-phase state. The refrigerant R then passes through the fourth node D, the third check valve 43, and the third node C in this order. The refrigerant R then enters the heat-source heat exchanger 13 at the refrigerant inlet 13a. The heat source heat exchanger 13 generates low-pressure gaseous refrigerant R by evaporating the refrigerant R using the heat of the air. The low-pressure gaseous refrigerant R exits the heat source heat exchanger 13 from a refrigerant outlet 13b and then reaches the first node A. The refrigerant R then passes through the first check valve 41 and reaches the second node B. The refrigerant R then passes through the four-way switching valve 12 and the accumulator 16 in this order, and is then drawn into the compressor 11 through the suction pipe 11a.

[0060] (3-3) Effect of counterflow in the heat source heat exchanger 13 7 and 8 show examples of temperature changes of the refrigerant R and the airflow AF in the heat source heat exchanger 13. The horizontal axis indicates the position y in the y direction. y1 is the position of the fin rear end 672, and y2 is the position of the fin front end 671. The vertical axis indicates the temperature T of the refrigerant R and the airflow AF. The values ​​of the temperature T shown in the figures are merely examples.

[0061] Figure 7 shows the temperature change during cold energy utilization operation. This figure assumes that the heat source heat exchanger 13 realizes counterflow of the refrigerant R and the airflow AF. The airflow AF travels from position y1 of the fin rear end 672 to position y2 of the fin front end 671. In contrast, the refrigerant R travels from position y2 of the fin front end 671 to position y1 of the fin rear end 672.

[0062] The heat source heat exchanger 13 functions as a condenser. In the heat source heat exchanger 13, the refrigerant R loses heat to the air flow AF. Therefore, the temperature of the refrigerant R decreases as the refrigerant R moves from position y2 to position y1. Because the air flow AF receives heat from the refrigerant R, the temperature of the air flow AF increases as the air flow AF moves from position y1 to position y2.

[0063] The temperature difference ΔT1 between the refrigerant R and the airflow AF at the position y1 and the temperature difference ΔT2 between the refrigerant R and the airflow AF at the position y2 are both sufficiently large, so that heat transfer from the refrigerant R to the airflow AF is carried out smoothly throughout the entire heat source heat exchanger 13.

[0064] 8 shows the temperature change during the heat utilization operation. The heat source heat exchanger 13 functions as an evaporator. In the heat source heat exchanger 13, the refrigerant R receives heat from the air flow AF, so that the temperature of the air flow AF decreases as the air flow AF moves from position y1 to position y2.

[0065] The refrigerant R receives heat from the airflow AF. Therefore, the temperature of the refrigerant R increases as the refrigerant R moves through the heat source heat exchanger 13. In this figure, two types of temperature changes of the refrigerant R are shown.

[0066] Arrows Rn indicate temperature changes in the comparative example. In the comparative example, it is assumed that the bridge circuit 40 is not present in the refrigerant circuit and the refrigerant R flows in the opposite direction to that in the cold energy utilization operation. At this time, the refrigerant R flows from position y1 at the rear end 672 of the fin to position y2 at the front end 671 of the fin, similar to the airflow AF.

[0067] Arrow Rc indicates the temperature change in the heat source heat exchanger 13 of this embodiment. The refrigerant circuit has a bridge circuit 40, and a counterflow similar to that in cold energy utilization operation is realized in the heat source heat exchanger 13. At this time, the refrigerant R flows in the opposite direction to the airflow AF, from position y2 at the fin front end 671 to position y1 at the fin rear end 672.

[0068] In the comparative example indicated by arrow Rn, the temperature difference ΔT3 between the refrigerant R and the airflow AF at position y1 is significantly different from the temperature difference ΔT4 between the refrigerant R and the airflow AF at position y2. The temperature difference ΔT4 is not large enough. This indicates that heat transfer from the airflow AF to the refrigerant R may be hindered near the fin front ends 671.

[0069] On the other hand, in this embodiment indicated by arrow Rc, the temperature difference ΔT5 between the refrigerant R and the airflow AF at position y1 and the temperature difference ΔT6 between the refrigerant R and the airflow AF at position y2 are both sufficiently large. Therefore, it can be understood that heat is transferred from the airflow AF to the refrigerant R without any hindrance throughout the entire heat-source heat exchanger 13 according to this embodiment.

[0070] When using a refrigerant R with a large temperature glide, such as a non-azeotropic refrigerant mixture, it is difficult to ensure a sufficient temperature difference between the refrigerant R and the airflow AF at the outlet of the heat exchanger. If a small temperature difference such as ΔT4 occurs, the heat exchange performance of the heat source heat exchanger 13 deteriorates. This problem can be solved by installing a bridge circuit 40 to ensure that the refrigerant R and the airflow AF always flow countercurrently in the heat source heat exchanger 13.

[0071] (3-4) Circulation volume of refrigerant R The circulation rate of the refrigerant R in the refrigeration cycle apparatus 100 varies depending on the operating conditions, fluctuating between a minimum value and a maximum value. In the refrigeration cycle apparatus 100, the circulation rate of the refrigerant R may be significantly small. In both the cold heat utilization operation and the hot heat utilization operation, the minimum value of the circulation rate of the refrigerant R in the refrigeration cycle apparatus 100 is smaller than 35.00 kg / h.

[0072] (4) Detailed structure of bridge circuit 40 (4-1) Check valve 9 shows the detailed structure of the check valve 47 used in the bridge circuit 40. The check valve 47 is a first check valve 41, a second check valve 42, a third check valve 43, or a fourth check valve 44. The check valve 47 is installed in a pipe P that forms a flow path such as a first flow path AB, a second flow path BC, a third flow path DC, or a fourth flow path AD.

[0073] The check valve 47 has a guide member 471, a valve element 472, a valve seat 473, and a seal member 474. The guide member 471 is cylindrical and guides the valve element 472. An outlet 471a is provided in the guide member 471. The valve element 472 is movable within the guide member 471 and has a valve portion 472a and blade portions 472b. The blade portions 472b stabilize the valve portion 472a by contacting the inner circumferential surface of the guide member 471. The valve seat 473 closes the flow path by contacting the valve portion 472a. The valve seat 473 has an inlet 473a. The seal member 474 seals the gap between the check valve 47 and the piping P.

[0074] When the pressure of refrigerant R at inlet 473a is greater than the pressure of refrigerant R at outlet 471a, check valve 47 opens the flow path and allows refrigerant R to pass. When the pressure of refrigerant R at inlet 473a is less than the pressure of refrigerant R at outlet 471a, valve element 472 moves toward valve seat 473, causing check valve 47 to close the flow path and block the refrigerant R. In order to close check valve 47, valve portion 472a needs to be pressed against valve seat 473 with a certain amount of force. To do this, the pressure difference of refrigerant R between inlet 473a and outlet 471a needs to be greater than a predetermined value. If a sufficient pressure difference of refrigerant R is not obtained, check valve 47 will not close completely, and refrigerant R may pass between inlet 473a and outlet 471a.

[0075] (4-2) Flow path 1 are set to have different flow path resistances. Specifically, the flow path resistance of the fourth flow path AD is set to be greater than the flow path resistance of the first flow path AB, or the flow path resistance of the third flow path DC is set to be greater than the flow path resistance of the second flow path BC. Preferably, the flow path resistance of the fourth flow path AD is set to be greater than the flow path resistance of the first flow path AB, and the flow path resistance of the third flow path DC is set to be greater than the flow path resistance of the second flow path BC.

[0076] The difference in flow path resistance is realized by the difference in flow path cross-sectional area. The first flow path AB, the second flow path BC, the third flow path DC, and the fourth flow path AD are set to have different flow path cross-sectional areas. Specifically, the flow path cross-sectional area of ​​the fourth flow path AD is set to be smaller than the flow path cross-sectional area of ​​the first flow path AB, or the flow path cross-sectional area of ​​the third flow path DC is set to be smaller than the flow path cross-sectional area of ​​the second flow path BC. For example, the flow path cross-sectional area of ​​the fourth flow path AD is set to be smaller than 55% of the flow path cross-sectional area of ​​the first flow path AB, or the flow path cross-sectional area of ​​the third flow path DC is set to be smaller than 55% of the flow path cross-sectional area of ​​the second flow path BC.

[0077] Preferably, the cross-sectional area of ​​the fourth flow path AD is smaller than the cross-sectional area of ​​the first flow path AB, and the cross-sectional area of ​​the third flow path DC is smaller than the cross-sectional area of ​​the second flow path BC.

[0078] In order to reduce the cross-sectional area of ​​any of the first flow path AB, the second flow path BC, the third flow path DC, and the fourth flow path AD, the diameter of the pipe P constituting the flow path shown in FIG. 9 may be reduced. Alternatively, to reduce the cross-sectional area of ​​the flow path, the flow path may be configured using a solenoid valve or a capillary. For example, by installing an electric valve capable of adjusting the opening size in the flow path, the cross-sectional area of ​​the flow path can be reduced by electrical control. Alternatively, the cross-sectional area of ​​the flow path can be reduced by installing a capillary in the flow path or by configuring the flow path itself using a capillary.

[0079] (5) Check valve not closing properly (5-1) Failure of the fourth check valve 44 to close The fourth check valve 44 is required to be closed during the hot heat utilization operation. Both ends of the fourth check valve 44 are the first node A and the fourth node D. As shown in FIG. 6, during the hot heat utilization operation, the first node A contains refrigerant R in a low-pressure gas state, and the fourth node D contains refrigerant R in a two-phase gas-liquid state. The two-phase gas-liquid refrigerant R contains both gas and liquid components, which makes the operation of the fourth check valve 44 unstable. For this reason, the fourth check valve 44 is likely to close incompletely.

[0080] If leakage of refrigerant R occurs at the fourth check valve 44 that should be closed, the refrigerant R in a gas-liquid two-phase state leaks from the fourth node D to the first node A. The refrigerant R in a gas-liquid two-phase state contains a liquid component and therefore has a high density. Therefore, the mass of the refrigerant R leaking through the fourth check valve 44 becomes large.

[0081] Thus, malfunction of the fourth check valve 44 during the heat utilization operation can have a significant adverse effect on the operation of the refrigerant circuit.

[0082] (5-2) Failure of the third check valve 43 to close The third check valve 43 is required to be closed during cold energy utilization operation. Both ends of the third check valve 43 are a third node C and a fourth node D. As shown in Fig. 5, during cold energy utilization operation, refrigerant R in a high-pressure gas state is present at the third node C, and refrigerant R in a high-pressure liquid state is present at the fourth node D. Because refrigerant R in a gas-liquid two-phase state is not present at both ends of the third check valve 43, the risk of unstable closure of the third check valve 43 is not as great as that of the fourth check valve 44 during hot energy utilization operation.

[0083] If leakage of refrigerant R occurs at the third check valve 43 that should be closed, the refrigerant R in a high-pressure gas state will leak from the third node C to the fourth node D. The refrigerant R in a gas state has a low density. Therefore, the mass of the refrigerant R leaking through the third check valve 43 will be small.

[0084] Thus, it can be said that the possibility of malfunction of the third check valve 43 occurring during cold energy utilization operation is relatively low, and that the adverse effect on the operation of the refrigerant circuit is not that great.

[0085] (5-3) Failure of the second check valve 42 to close The second check valve 42 is required to be closed during hot heat utilization operation. The two ends of the second check valve 42 are the second node B and the third node C. As shown in FIG. 6, during hot heat utilization operation, the refrigerant R in a low-pressure gas state is present at the second node B, and the refrigerant R in a two-phase gas-liquid state is present at the third node C. The refrigerant R in a two-phase gas-liquid state contains both gas and liquid components, which makes the operation of the second check valve 42 unstable. For this reason, the second check valve 42 is likely to close incompletely.

[0086] If leakage of refrigerant R occurs at the second check valve 42 that should be closed, the refrigerant R in a gas-liquid two-phase state will leak from the third node C to the second node B. The refrigerant R in a gas-liquid two-phase state contains a liquid component and therefore has a high density. As a result, a large amount of refrigerant R flows back through the second check valve 42.

[0087] Thus, malfunction of the second check valve 42 during the heat utilization operation can have a significant adverse effect on the operation of the refrigerant circuit.

[0088] (5-4) Failure of the first check valve 41 to close The first check valve 41 is required to be closed during cold energy utilization operation. Both ends of the first check valve 41 are a first node A and a second node B. As shown in Fig. 5, during cold energy utilization operation, refrigerant R in a high-pressure liquid state is present at the first node A, and refrigerant R in a high-pressure gas state is present at the second node B. Because refrigerant R in a gas-liquid two-phase state is not present at both ends of the first check valve 41, the risk of unstable closure of the first check valve 41 is not as great as that of the fourth check valve 44 during hot energy utilization operation.

[0089] If leakage of refrigerant R occurs at the first check valve 41 that should be closed, the refrigerant R in a high-pressure gas state will leak from the second node B to the first node A. The refrigerant R in a gas state has a low density. Therefore, the mass of the refrigerant R flowing backward through the first check valve 41 is small.

[0090] As described above, the possibility of malfunction of the first check valve 41 occurring during cold energy utilization operation is relatively low, and the adverse effect on the operation of the refrigerant circuit is not so great.

[0091] (6) Features (6-1) (6-1-1) Setting flow resistance In the bridge circuit 40, the cross-sectional area of ​​the third flow path DC or the fourth flow path AD is small. Preferably, the cross-sectional area of ​​the third flow path DC is smaller than 55% of the cross-sectional area of ​​the second flow path BC, or the cross-sectional area of ​​the fourth flow path AD is smaller than 55% of the cross-sectional area of ​​the first flow path AB.

[0092] As a result, the flow path resistance of the third flow path DC or the fourth flow path AD is set to be large.

[0093] (6-1-2) Effect of increasing the flow resistance of the third flow path DC Increasing the flow path resistance of the third flow path DC makes it possible to increase the pressure difference of the refrigerant R across the fourth check valve 44, which should be closed, during the hot heat utilization operation shown in Fig. 6. This is because the pressure difference across the fourth check valve 44 is not only the pressure difference across the heat source heat exchanger 13, but also the significant pressure difference that appears across the third flow path DC. Therefore, during the hot heat utilization operation, the fourth check valve 44 arranged in the fourth flow path AD can be closed more firmly.

[0094] Similarly, by increasing the flow resistance of the first flow path AB, the pressure difference of the refrigerant R across the second check valve 42 that should be closed can be increased, thereby making it possible to more firmly close the second check valve 42 during the hot energy utilization operation. However, the second flow path BC having the second check valve 42 plays a role in supplying all of the refrigerant R discharged from the compressor 11 to the subsequent refrigerant circuit during the cold energy utilization operation shown in FIG. 5. Therefore, increasing the flow resistance of the first flow path AB may result in a deterioration in the performance of the entire refrigerant circuit. For this reason, in this embodiment, the flow resistance of the first flow path AB is not increased.

[0095] On the other hand, if an adverse effect of increasing the flow path resistance of the third flow path DC occurs, such that the pressure of the refrigerant R at the third node C becomes too low during the heat utilization operation shown in Fig. 6, it is possible to alleviate the drop in pressure at the third node C by adjusting the opening of the heat source expansion valve 15 slightly larger. For the above reasons, increasing the flow path resistance of the third flow path DC takes priority over increasing the flow path resistance of the first flow path AB.

[0096] (6-1-3) Effect of increasing the flow resistance of the fourth flow path AD Increasing the flow path resistance of the fourth flow path AD can increase the pressure difference of the refrigerant R across the third check valve 43, which should be closed, during the cold energy utilization operation shown in Fig. 5. This is because the pressure difference across the third check valve 43 is not only the pressure difference across the heat source heat exchanger 13, but also the significant pressure difference across the fourth flow path AD. Therefore, during the cold energy utilization operation, the third check valve 43 arranged in the third flow path DC can be closed more firmly.

[0097] As mentioned above, although the possibility of the third check valve 43 failing to close is relatively low and the adverse effect on the operation of the refrigerant circuit is not particularly large, taking measures to ensure that the third check valve 43 closes is useful in reducing malfunctions of the refrigeration cycle device 100.

[0098] Similarly, by increasing the flow resistance of the second flow path BC, the pressure difference of the refrigerant R between both ends of the first check valve 41 that should be closed can be increased, thereby making it possible to more firmly close the first check valve 41 during the cold heat utilization operation. However, the first flow path AB including the first check valve 41 plays a role in guiding all of the refrigerant R sent from the preceding refrigerant circuit to the compressor 11 during the hot heat utilization operation shown in FIG. 6. Therefore, increasing the flow resistance of the second flow path BC may result in a deterioration in the performance of the entire refrigerant circuit. For this reason, in this embodiment, the flow resistance of the second flow path BC is not increased.

[0099] On the other hand, if an adverse effect of increasing the flow path resistance of the fourth flow path AD is that the pressure of the refrigerant R at the fourth node D becomes too low during the cold energy utilization operation shown in Fig. 5, it is possible to mitigate the pressure drop in the refrigerant circuit downstream of the heat source expansion valve 15 by adjusting the opening of the heat source expansion valve 15 slightly larger. For the above reasons, increasing the flow path resistance of the fourth flow path AD takes priority over increasing the flow path resistance of the second flow path BC.

[0100] (6-2) A bridge circuit 40 is provided to always keep the direction of the refrigerant R the same in the heat source heat exchanger 13. Therefore, in the heat source heat exchanger 13, a counterflow can be realized in which the refrigerant R and the airflow AF flow in opposite directions.

[0101] (6-3) The refrigerant R is a non-azeotropic refrigerant mixture having a large temperature glide. For example, the refrigerant R is R454C, which is a mixture of R32 and R1234yf. Even in this case, the bridge circuit 40 allows the refrigerant R and the airflow AF to flow in opposite directions, regardless of whether the operation is cold energy utilization operation or hot energy utilization operation, thereby suppressing performance degradation of the refrigeration cycle apparatus 100.

[0102] (6-4) In the cold heat utilization operation or the hot heat utilization operation, the minimum value that the circulation rate of the refrigerant R in the refrigeration cycle apparatus 100 can assume is smaller than 35.00 kg / h. Therefore, a small minimum value of the circulation rate of the refrigerant R can cause incomplete operation of the third check valve 43 or the fourth check valve 44. Even in this case, since the flow path resistance of the third flow path DC or the fourth flow path AD is large, malfunction of the third check valve 43 or the fourth check valve 44 can be suppressed.

[0103] (7) Variations (7-1) In the above-described embodiment, the flow path resistance or the flow path cross-sectional area is determined so that the flow path resistance of the fourth flow path AD is greater than the flow path resistance of the first flow path AB, or the flow path resistance of the third flow path DC is greater than the flow path resistance of the second flow path BC. Alternatively, the flow path resistance may be determined so that the flow path resistance of the fourth flow path AD is greater than the flow path resistance of the second flow path BC, or the flow path resistance of the third flow path DC is greater than the flow path resistance of the first flow path AB.

[0104] Furthermore, the flow path cross-sectional area may be determined so that the flow path cross-sectional area of ​​the fourth flow path AD is smaller than the flow path cross-sectional area of ​​the second flow path BC, or the flow path cross-sectional area of ​​the third flow path DC is smaller than the flow path cross-sectional area of ​​the first flow path AB.

[0105] Furthermore, the flow path cross-sectional area may be determined so that the flow path cross-sectional area of ​​the third flow path DC is smaller than 55% of the flow path cross-sectional area of ​​the first flow path AB, or the flow path cross-sectional area of ​​the fourth flow path AD is smaller than 55% of the flow path cross-sectional area of ​​the second flow path BC.

[0106] (7-2) The refrigeration cycle apparatus 100 according to the above-described embodiment has one heat source unit 10 and one utilization unit 20. Alternatively, the refrigeration cycle apparatus 100 may have one heat source unit 10 and a plurality of utilization units 20. Furthermore, the refrigeration cycle apparatus 100 may have a plurality of heat source units 10.

[0107] Second Embodiment (1) Overall structure 10 shows the configuration of a refrigeration cycle apparatus 100A according to the second embodiment. The refrigeration cycle apparatus 100A differs from the refrigeration cycle apparatus 100 according to the first embodiment in that the heat source unit 10 does not have a bridge circuit 40, and the utilization unit 20 has a bridge circuit 80.

[0108] (2) Detailed configuration The refrigeration cycle apparatus 100A includes a utilization heat exchanger 23 and a bridge circuit 80.

[0109] (2-1) Utilization heat exchanger 23 and utilization fan 24 Unlike the first embodiment, the utilization heat exchanger 23 has a refrigerant inlet 23a and a refrigerant outlet 23b. The refrigerant R enters the utilization heat exchanger 23 at the refrigerant inlet 23a and exits the utilization heat exchanger 23 at the refrigerant outlet 23b. The utilization fan 24 generates an airflow AF that passes through the utilization heat exchanger 23, thereby promoting heat exchange between the air and the refrigerant R.

[0110] (2-2) Bridge circuit 80 The bridge circuit 80 keeps the direction of travel of the refrigerant R constant in the utilization heat exchanger 23. Due to the function of the bridge circuit 80, regardless of whether the direction of travel of the refrigerant R is the arrow CO or the arrow HO, the refrigerant R always enters the utilization heat exchanger 23 at the refrigerant inlet 23a and always exits the utilization heat exchanger 23 at the refrigerant outlet 23b.

[0111] The bridge circuit 80 has a first node A', a second node B', a third node C', and a fourth node D'. The first node A' is connected to the refrigerant outlet 23b. The second node B' is connected to the compressor 11 via the four-way switching valve 12. The third node C' is connected to the refrigerant inlet 23a. The fourth node D' is connected to the heat source expansion valve 15.

[0112] Furthermore, the bridge circuit 80 has a first flow path A'B' extending from the first node A' to the second node B', a second flow path B'C' extending from the second node B' to the third node C', a third flow path D'C' extending from the fourth node D' to the third node C', and a fourth flow path A'D' extending from the first node A' to the fourth node D'.

[0113] The bridge circuit 80 includes a first check valve 81, a second check valve 82, a third check valve 83, and a fourth check valve 84. These check valves maintain the same flow direction of the refrigerant R in the flow paths in which they are installed, preventing backflow of the refrigerant R. The first check valve 41 is provided in the first flow path A'B' and allows the refrigerant R to flow only in the direction from the first node A' to the second node B'. The second check valve 42 is provided in the second flow path B'C' and allows the refrigerant R to flow only in the direction from the second node B' to the third node C'. The third check valve 43 is provided in the third flow path D'C' and allows the refrigerant R to flow only in the direction from the fourth node D' to the third node C'. The fourth check valve 44 is provided in the fourth flow path A'D' and allows the refrigerant R to flow only in the direction from the first node A' to the fourth node D'.

[0114] (3) Features A bridge circuit 80 is provided so that the direction of the refrigerant R in the utilization heat exchanger 23 is always the same. Therefore, in the utilization heat exchanger 23, a counterflow can be realized in which the refrigerant R and the airflow AF flow in opposite directions.

[0115] (4) Variations The modified example of the first embodiment may be applied to this embodiment.

[0116] Third Embodiment (1) Overall structure 11 shows the configuration of a refrigeration cycle apparatus 100B according to the third embodiment. The refrigeration cycle apparatus 100B differs from the refrigeration cycle apparatus 100 according to the first embodiment and the refrigeration cycle apparatus 100A according to the second embodiment in that the heat source unit 10 and the utilization unit 20 have a bridge circuit 40 and a bridge circuit 80, respectively. The configurations of the bridge circuit 40 and the bridge circuit 80 are the same as those of the first embodiment or the second embodiment.

[0117] (2) Features A bridge circuit 40 and a bridge circuit 80 are provided so that the flow direction of the refrigerant R is always the same in the heat source heat exchanger 13 and the utilization heat exchanger 23, respectively. Therefore, in both the heat source heat exchanger 13 and the utilization heat exchanger 23, a counterflow can be realized in which the flow directions of the refrigerant R and the airflow AF are opposite to each other.

[0118] (3) Variations The modified examples of the first embodiment or the second embodiment may be applied to this embodiment.

[0119] <Conclusion> Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0120] 10: Heat source unit 11: Compressor 12: Four-way switching valve 13:Heat source heat exchanger (1st heat exchanger / 2nd heat exchanger) 13a: Refrigerant inlet 13b: Refrigerant outlet 14: Heat source fan 15: Heat source expansion valve (expansion valve) 20: Usage unit 23: Heat exchanger used (second heat exchanger / first heat exchanger) 23a: Refrigerant inlet 23b: Refrigerant outlet 24: Fans in use 30: Connecting piping group 40, 80: Bridge circuit 41, 81: First check valve 42, 82: Second check valve 43, 83: Third check valve 44, 84: 4th check valve 47: Check valve 50: Flow divider 60: Heat exchanger body 70: Combiner 100, 100A, 100B: Refrigeration cycle device A, A': First node B, B': Second node C, C': Third node D, D': 4th node AB, A'B': First flow path BC, B'C': Second flow path DC, D'C': Third flow path AD, A'D': 4th flow path R: Refrigerant AF: Air flow [Prior art documents] [Patent documents]

[0121] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-222362

Claims

1. a compressor (11) for compressing a refrigerant (R); an expansion valve (15) for reducing the pressure of the refrigerant; a four-way switching valve (12) for switching between a first operation and a second operation; a first heat exchanger (13) having a refrigerant inlet (13a) and a refrigerant outlet (13b), functioning as a condenser in the first operation and as an evaporator in the second operation; a second heat exchanger (23) that functions as an evaporator in the first operation and as a condenser in the second operation; a bridge circuit (40) for flowing the refrigerant into the first heat exchanger at the refrigerant inlet and out of the first heat exchanger at the refrigerant outlet in both the first operation and the second operation; A refrigeration cycle device (100) comprising: The bridge circuit includes: a first node (A), a second node (B), a third node (C); a fourth node (D), a first flow path (AB) extending from the first node (A) to the second node (B); a second flow path (BC) extending from the second node (B) to the third node (C); a third flow path (DC) extending from the fourth node (D) to the third node (C); a fourth flow path (AD) extending from the first node (A) to the fourth node (D); a first check valve (41) for allowing the refrigerant to flow from the first node (A) to the second node (B); a second check valve (42) for allowing the refrigerant to flow from the second node (B) to the third node (C); a third check valve (43) for allowing the refrigerant to flow from the fourth node (D) to the third node (C); and a fourth check valve (44) for allowing the refrigerant to flow from the first node (A) to the fourth node (D); and The first node (A) is connected to the refrigerant outlet (13b), The second node (B) is connected to the compressor (11) via the four-way switching valve (12), The third node (C) is connected to the refrigerant inlet (13a), The fourth node (D) is connected to the expansion valve (15), The flow path resistance of the fourth flow path (AD) is greater than the flow path resistance of the first flow path (AB), or the flow path resistance of the third flow path (DC) is greater than the flow path resistance of the second flow path (BC). A refrigeration cycle device (100).

2. a flow path cross-sectional area of ​​the fourth flow path (AD) is smaller than a flow path cross-sectional area of ​​the first flow path (AB), or a flow path cross-sectional area of ​​the third flow path (DC) is smaller than a flow path cross-sectional area of ​​the second flow path (BC); The refrigeration cycle device according to claim 1.

3. A flow path cross-sectional area of ​​the third flow path (DC) is smaller than a flow path cross-sectional area of ​​the second flow path (BC). The refrigeration cycle device according to claim 1.

4. a flow path cross-sectional area of ​​the fourth flow path (AD) is smaller than a flow path cross-sectional area of ​​the first flow path (AB); The refrigeration cycle device according to claim 3.

5. a flow path cross-sectional area of ​​the third flow path (DC) is smaller than 55% of a flow path cross-sectional area of ​​the second flow path (BC); The refrigeration cycle device according to claim 3.

6. The cross-sectional area of ​​the fourth flow path (AD) is smaller than 55% of the cross-sectional area of ​​the first flow path (AB). The refrigeration cycle device according to claim 4.

7. The first heat exchanger is a heat source heat exchanger (13), and the second heat exchanger is a utilization heat exchanger (23). The refrigeration cycle device according to any one of claims 1 to 6.

8. The first heat exchanger is a utilization heat exchanger (23), and the second heat exchanger is a heat source heat exchanger (13). The refrigeration cycle device according to any one of claims 1 to 6.

9. The refrigerant is a non-azeotropic refrigerant mixture. The refrigeration cycle device according to any one of claims 1 to 6.

10. In the first operation or the second operation, the minimum value that the circulation amount of the refrigerant in the refrigeration cycle device can take is smaller than 35.00 kg / h. The refrigeration cycle device according to any one of claims 1 to 6.

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