Refrigeration cycle device

Abstract

This refrigeration cycle device is provided with: a heat source machine having a compressor that compresses a refrigerant, a heat-source-side heat exchanger, and a first flow path switching device that switches a flow path of the refrigerant; a high-pressure-side pipe; a low-pressure-side pipe; a use-side unit connected to the high-pressure-side pipe and the low-pressure-side pipe and having a use-side heat exchanger and a first flow rate control device; a heat medium relay unit connected to the high-pressure-side pipe and the low-pressure-side pipe and having a second flow rate control device and an inter-heat-medium heat exchanger that exchanges heat between the refrigerant and a heat medium that carries heat from an external heat source; a first branch part connected to a first connection pipe extending from each of the use-side unit and the heat medium relay unit; and a second branch part connected to a second connection pipe extending from each of the use-side unit and the heat medium relay unit. The present invention is configured to form, when the heat-source-side heat exchanger functions as an evaporator, such connection that the refrigerant flows from a discharge side of the compressor to the high-pressure-side pipe and such connection that the refrigerant flows from the low-pressure-side pipe to a suction side of the compressor through the heat-source-side heat exchanger. The first branch part is provided with a second flow path switching device that switches the connection between the first connection pipe and the high-pressure-side pipe or the low-pressure-side pipe. The second flow path switching device is configured such that the inter-heat-medium heat exchanger can function as an auxiliary condenser when the heat-source-side heat exchanger functions as a condenser and the inter-heat-medium heat exchanger can function as an auxiliary evaporator when the heat-source-side heat exchanger functions as an evaporator.

Description

Refrigeration Cycle Equipment

[0001] The present disclosure relates to a refrigeration cycle device capable of multiple operations such as cooling operation, heating operation, and hot water supply operation, and in particular to a refrigeration cycle device that can reduce the load on a heat source-side heat exchanger by using unused heat as a heat source.

[0002] It has been known for some time that in combined air conditioning and hot water supply systems capable of simultaneously supplying cooling, heating, and hot water loads, balancing the cooling, heating, and hot water loads improves the system COP (see, for example, Patent Document 1). The refrigeration cycle device disclosed in Patent Document 1 includes a heat source unit, a relay unit connected to the heat source unit via a high-pressure connection pipe and a low-pressure connection pipe, and user units including an indoor unit and a hot water heat source circuit. The relay unit has a first distribution section and a second distribution section configured to selectively connect two connection pipes extending from each user unit to the high-pressure connection pipe or the low-pressure connection pipe. In Patent Document 1, the first distribution section switches the connection between one of the connection pipes of each user unit and the high-pressure connection pipe or the low-pressure connection pipe, allowing each user unit to individually perform heating operation, cooling operation, or hot water supply operation. The refrigeration cycle device of Patent Document 1 balances the cooling load, heating load, and hot water supply load of a plurality of user-side units, thereby improving the efficiency of the entire system.

[0003] Air conditioning systems that use melted snow water or well water are also known (see, for example, Patent Document 2). The snow and ice air conditioning system disclosed in Patent Document 2 includes an indirect outdoor air cooler, a compression refrigeration cooler, and a snow and ice cooler. The snow and ice cooler uses the cold energy of a snowy mountain to cool a refrigerant, which then cools the outdoor air supplied to the heat exchangers on the heat source side of the indirect outdoor air cooler and the compression refrigeration cooler. The snow and ice air conditioning system of Patent Document 2 makes effective use of the cold energy of a snowy mountain, enabling energy-saving operation.

[0004] Japanese Patent No. 5642085 Japanese Patent Application Laid-Open No. 2018-146221

[0005] The refrigeration cycle device disclosed in Patent Document 1 can improve COP by balancing the cooling load, heating load, and hot water supply load of the user unit, but the cooling / heating capacity required for the load in the usage situation of the user unit is borne by the heat source unit, so further energy-saving effects beyond the improvement of the COP of the refrigeration cycle device cannot be expected.

[0006] Furthermore, the snow and ice air conditioning system disclosed in Patent Document 2 can reduce the load on the indirect outdoor air cooler and the compression refrigeration cooler by using the cold energy from snowy mountains, but the refrigerant circuits of the indirect outdoor air cooler, the compression refrigeration cooler, and the snow and ice cooler are all independent. The snow and ice cooler supplies cooled outdoor air to the sensible heat exchanger of the indirect outdoor air cooler and the condenser of the compression refrigeration cooler, and the refrigerant circuits of the indirect outdoor air cooler and the compression refrigeration cooler are also independent, making it difficult to improve the efficiency of the entire system by balancing the loads of the two coolers.

[0007] The present disclosure has been made to solve the above-mentioned problems, and provides a refrigeration cycle device that improves COP by balancing the load between each user unit and enables energy-saving operation of the entire system by utilizing an external heat source.

[0008] The refrigeration cycle device according to the present disclosure includes a heat source machine having a compressor that compresses a refrigerant, a heat source side heat exchanger, and a first flow switching device that switches a flow path of the refrigerant; a high-pressure side pipe through which the refrigerant flowing out from the heat source machine flows; a low-pressure side pipe through which the refrigerant flowing into the heat source machine flows; a utilization side unit connected to the high-pressure side pipe and the low-pressure side pipe and having a utilization side heat exchanger and a first flow control device that controls the flow rate of the refrigerant flowing to the utilization side heat exchanger; and a utilization side unit connected to the high-pressure side pipe and the low-pressure side pipe. a heat medium relay unit including an intermediate heat exchanger for exchanging heat between the refrigerant and a heat medium carrying heat from an external heat source, and a second flow control device for controlling a flow rate of the refrigerant flowing through the intermediate heat exchanger; a first branch section for branching the high-pressure side pipe and the low-pressure side pipe to the user side unit and the heat medium relay unit, respectively, the first branch section being connected to first connecting pipes extending from the user side unit and the heat medium relay unit, and the second branch section being connected to second connecting pipes extending from the user side unit and the heat medium relay unit, respectively; and a second branching section connected to the first connecting pipe and the high-pressure side pipe, the first flow path switching device being configured to connect the refrigerant so that it flows from the discharge side of the compressor to the high-pressure side pipe via the heat source side heat exchanger and from the low-pressure side pipe to the suction side of the compressor when the heat source side heat exchanger functions as a condenser, and to connect the refrigerant so that it flows from the discharge side of the compressor to the high-pressure side pipe and from the low-pressure side pipe to the suction side of the compressor via the heat source side heat exchanger when the heat source side heat exchanger functions as an evaporator. The first branching section is provided with a second flow path switching device that switches the connection between the first connecting pipe and the high-pressure side pipe or the low-pressure side pipe, and the second flow path switching device being configured to enable the intermediate heat exchanger to function as an auxiliary condenser when the heat source side heat exchanger functions as a condenser, and to enable the intermediate heat exchanger to function as an auxiliary evaporator when the heat source side heat exchanger functions as an evaporator.

[0009] According to the present disclosure, simultaneous heating and cooling operation and hot water supply operation can be performed simultaneously by switching the connection of each utilization unit and the heat source-side heat exchanger of the heat medium converter using the first branch section and the second branch section, and the heat medium converter can function to supplement the capacity of the heat source-side heat exchanger. Since the heat medium converter is configured to exchange heat with the refrigerant of the refrigeration cycle device using an external heat source, such as well water or geothermal heat, and part or all of the capacity of the heat source-side heat exchanger can be supplemented by the external heat source, the refrigeration cycle device can operate more energy-efficiently than conventional refrigeration cycle devices.

[0010] 1 is a schematic diagram of a configuration of a refrigeration cycle apparatus 100 according to Embodiment 1. FIG. 2 is an example of a circuit diagram showing the refrigeration cycle apparatus 100 according to Embodiment 1. FIG. 3 is an explanatory diagram of a refrigerant flow when the refrigeration cycle apparatus 100 according to Embodiment 1 is performing cooling operation. FIG. 4 is a diagram showing the usage states of heat medium relay units D1 and D2 based on temperatures T, t1, and t2 of each part of the refrigeration cycle apparatus 100 according to Embodiment 1. FIG. 5 is an explanatory diagram of a refrigerant flow when the refrigeration cycle apparatus 100 according to Embodiment 1 is performing cooling-dominated operation. FIG. 6 is an explanatory diagram of a refrigerant flow when the refrigeration cycle apparatus 100 according to Embodiment 1 is performing heating operation. FIG. 7 is an explanatory diagram of a refrigerant flow when the refrigeration cycle apparatus 100 according to Embodiment 1 is performing heating-dominated operation. FIG. 8 is a flowchart showing the operation of the refrigeration cycle apparatus 100 according to Embodiment 1. FIG. 9 is a Mollier diagram of the refrigeration cycle apparatus 100 according to Embodiment 1 during cooling operation. FIG. 10 is a Mollier diagram of the refrigeration cycle apparatus 100 according to Embodiment 1 during cooling operation. 1 is a Mollier diagram of the refrigeration cycle apparatus 100 according to embodiment 1 during heating operation. FIG. 2 is a Mollier diagram of the refrigeration cycle apparatus 100 according to embodiment 1 during heating-dominated operation. FIG. 3 is an example of a circuit diagram showing a refrigeration cycle apparatus 200 according to embodiment 2. FIG. 4 is a Mollier diagram of the refrigeration cycle apparatus 200 according to embodiment 2 during cooling operation. FIG. 4 is an example of a circuit diagram showing the refrigeration cycle apparatus 200 according to embodiment 2. FIG. 5 is a Mollier diagram of the refrigeration cycle apparatus 200 according to embodiment 2 during cooling operation. FIG. 5 is an example of a circuit diagram showing the refrigeration cycle apparatus 200 according to embodiment 2. FIG. 6 is a Mollier diagram of the refrigeration cycle apparatus 200 according to embodiment 2 during heating operation. FIG. 6 is an example of a circuit diagram showing the refrigeration cycle apparatus 200 according to embodiment 2. FIG. 7 is a Mollier diagram of the refrigeration cycle apparatus 200 according to embodiment 2 during heating-dominated operation.

[0011] Embodiment 1. An embodiment of an air conditioning apparatus according to the present disclosure will now be described with reference to the drawings. FIG. 1 is a schematic diagram of the configuration of a refrigeration cycle apparatus 100 according to embodiment 1. As shown in FIG. 1, the refrigeration cycle apparatus 100 includes a heat source unit A, a relay unit B connected to the heat source unit A via a low-pressure side pipe 6 and a high-pressure side pipe 7, and a user unit C connected to the relay unit B via a first connection pipe 40 and a second connection pipe 41. The user unit C can select cooling operation, heating operation, or hot water supply operation by utilizing a refrigeration cycle. When the refrigeration cycle apparatus 100 includes multiple user units C, each of the multiple user units C can freely select and operate in one of the following operating modes: cooling operation, heating operation, or hot water supply operation. In other words, the refrigeration cycle apparatus 100 is capable of mixed cooling and heating operation, in which cooling operation and heating operation are performed simultaneously, as well as mixed operation in which water heating operation is also performed.

[0012] The heat source unit A and the relay unit B are connected by a low-pressure side pipe 6 and a high-pressure side pipe 7, and are configured so that refrigerant compressed by a compressor 1 (see Figure 2) provided in the heat source unit A is sent to the relay unit B, which then distributes the refrigerant to each user-side unit C. The operating state of each user-side unit C is changed depending on whether the first connection pipe 40 and the second connection pipe 41 are connected to the low-pressure side pipe 6 or the high-pressure side pipe 7. Figure 1 shows, as an example, a case where the top user-side unit C1 is in heating operation, the second user-side unit C2 from the top is in cooling operation, and the third user-side unit C3 from the top is in water-heating operation.

[0013] The user-side units C are, for example, indoor air conditioners or water heaters, which are supplied with refrigerant from the relay unit B and use a refrigeration cycle to perform indoor air conditioning or water heating. Each user-side unit C is connected in series to the relay unit B and in parallel with each other. In FIG. 1, three user-side units C are connected to the relay unit B, but this number is not limited, and two or more user-side units C may be installed, or even just one. Furthermore, the user-side unit C can be an indoor unit of an air conditioner, a water heater, a refrigerator, or the like, and there are no restrictions on the equipment that can be connected.

[0014] When the user-side unit C is directly connected to the low-pressure side pipe 6, the user-side heat exchanger 5 (see FIG. 2) functions as an evaporator and performs cooling operation, and when it is directly connected to the high-pressure side pipe 7, the user-side heat exchanger 5 functions as a condenser and performs heating operation or water-heating operation. The operation of each user-side unit C is switched by a second flow path switching device 10c (see FIG. 2) provided in the relay device B.

[0015] A heat medium converter D is also connected to the relay unit B. The heat medium converter D is connected to the relay unit B in a circuit configuration similar to that of the user unit C. Like the user unit C, the heat medium converter D also receives a refrigerant from the relay unit B. The heat medium converter D is also connected to an external heat source E. The external heat source E and the heat medium converter D are connected by a circuit through which a heat medium different from the refrigerant flowing from the relay unit B circulates. The heat medium converter D is configured to exchange heat between the heat medium having heat from the external heat source E and the refrigerant that flows into the heat medium converter D from the heat source unit A via the relay unit B, and to transfer heat or cold from the external heat source E to the refrigerant, thereby functioning as a condenser or evaporator. The heat medium converter D may be configured to circulate a liquid such as well water contained in the external heat source E through the heat medium circulation circuit 34 (see FIG. 2 ), or may be configured to circulate an independent heat medium through the heat medium circulation circuit 34.

[0016] In particular, in the first embodiment, the heat medium relay unit D functions to assist the heat source-side heat exchanger 3 (see FIG. 2 ) of the heat source unit A, and can function as a condenser when the heat source-side heat exchanger 3 functions as a condenser, and can function as an evaporator when the heat source-side heat exchanger 3 functions as an evaporator. This allows the heat source-side heat exchanger 3 to operate with reduced heat exchange capacity by the amount of use of the external heat source E, thereby achieving energy savings in the refrigeration cycle apparatus 100 as a whole.

[0017] The external heat source E connected to the heat medium converter D is a source of heat or cold, such as well water, geothermal heat, or sunlight. The heat medium converter D is a device that transfers the heat or cold from the external heat source E to a refrigerant via a heat medium. When the external heat source E is well water, the well water is pumped up and circulated as a heat medium through a heat medium circulation circuit 34 (see FIG. 2 ). When geothermal heat is used as the external heat source E, a heat medium such as water heated by geothermal heat circulates through the heat medium circulation circuit 34. When sunlight is used as the external heat source E, a heat medium such as water heated by sunlight circulates through the heat medium circulation circuit 34. Alternatively, snow or melted snow may be used as the external heat source E. Alternatively, unused heat such as heat from river water, exhaust gas from equipment, wastewater, or waste heat generated by equipment may be used as the external heat source E. The heat medium such as water circulating through the heat medium circulation circuit 34 exchanges heat with the refrigerant circulating through the heat source unit A and the like in the intermediate heat exchanger 30 (see FIG. 2).

[0018] 1, a plurality of heat transfer units D and a plurality of external heat sources E are installed, but a single number may be used. Also, the external heat source E may be a combination of a plurality of types of heat sources.

[0019] Whether the heat medium relay unit D is used as an evaporator or a condenser depends on whether the temperature of the external heat source E is high or low based on the evaporation temperature and condensation temperature of the refrigerant in the refrigeration cycle circulating through the heat source unit A, the relay unit B, the user unit C, and the heat medium relay unit D. When the temperature of the external heat source E is higher than the evaporation temperature of the refrigerant, the heat medium relay unit D is used as an evaporator, and when the temperature of the external heat source E is lower than the condensation temperature of the refrigerant, the heat medium relay unit D is used as a condenser. In general, when a relatively high-temperature external heat source E such as geothermal energy or sunlight is used, the heat medium relay unit D is used as an evaporator, and when a relatively low-temperature external heat source E such as well water, snow, or melted snow is used, the heat medium relay unit D is used as a condenser.

[0020] The heat medium relay unit D switches between using the first connecting pipe 40 as an evaporator by directly connecting it to the low-pressure side pipe 6 and using it as a condenser by directly connecting it to the high-pressure side pipe 7, depending on the temperature of the external heat source E. The switching of operation using the heat medium relay unit D is performed by a second flow path switching device 10c (see FIG. 2) provided in the relay unit B. FIG. 1 shows, as an example, a case where the topmost user side unit C1 is operating in heating mode, the second-highest user side unit C2 is operating in cooling mode, and the third-highest user side unit is operating in water heating mode.

[0021] 2 is an example of a circuit diagram showing the refrigeration cycle apparatus 100 according to Embodiment 1. The heat source unit A and the relay unit B are connected by a low-pressure side pipe 6 and a high-pressure side pipe 7. The high-pressure side pipe 7 is a pipe through which the high-pressure refrigerant compressed by the compressor 1 flows out, either directly or via the heat source side heat exchanger 3. The low-pressure side pipe 6 is a pipe through which the low-pressure refrigerant that has passed through the user side unit C or the heat medium relay unit D flows in, and is a pipe for returning the refrigerant from the relay unit B to the heat source unit A.

[0022] The refrigerant in the high-pressure side pipe 7 flows into the high-pressure side branch 10a of the first branch 10 of the relay unit B. By opening the high-pressure side solenoid valves 9c1, 9c2, 9d1, and 9d2 provided in the first branch 10, the refrigerant in the high-pressure side branch 10a flows into the user side unit C or the heat medium relay unit D. The high-pressure side solenoid valves 9c1, 9c2, 9d1, and 9d2 may be collectively referred to as the high-pressure side solenoid valves 9.

[0023] The low-pressure side pipe 6 is connected to a low-pressure side branch 10b of the first branch 10 of the relay unit B. Refrigerant flows into the low-pressure side branch 10b from the user side unit C or the heat medium relay unit D by opening low-pressure side solenoid valves 8c1, 8c2, 8d1, and 8d2. The low-pressure side solenoid valves 8c1, 8c2, 8d1, and 8d2 may be collectively referred to as low-pressure side solenoid valves 8.

[0024] The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 are connected to first connection pipes 40c1, 40c2, 40d1, and 40d2, which are pipes extending from the user side unit C and the heat medium relay unit D, respectively. The first connection pipes 40c1, 40c2, 40d1, and 40d2 may be collectively referred to as first connection pipes 40.

[0025] The other pipes extending from the user side unit C and the heat medium relay unit D are referred to as second connection pipes 41c1, 41c2, 41d1, and 41d2. The second connection pipes 41c1, 41c2, 41d1, and 41d2 are connected to the second branch section 11 of the relay unit. The second connection pipes 41c1, 41c2, 41d1, and 41d2 may be collectively referred to as second connection pipes 41.

[0026] By switching the low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 of the first branch section 10 between open and closed states, the refrigerant can be switched between flowing into the user-side unit C and the heat medium converter D from the second branch section 11 and flowing out from the user-side unit C and the heat medium converter D to the second branch section 11.

[0027] For example, when the high-pressure side solenoid valve 9 is open and the low-pressure side solenoid valve 8 is closed, the refrigerant flows from the high-pressure side branch 10a connected to the high-pressure side pipe 7 through the high-pressure side solenoid valve 9 into the user side unit C or the heat medium relay unit D, and the refrigerant that has passed through the user side unit C or the heat medium relay unit D flows into the second branch 11.

[0028] For example, when the high-pressure side solenoid valve 9 is closed and the low-pressure side solenoid valve 8 is opened, refrigerant that has passed through another user-side unit C, another heat medium relay unit D, or refrigerant that has been separated from the high-pressure side piping 7 by the gas-liquid separator 12 and passed through the first heat exchanger 17 and the second heat exchanger 16 flows from the second branch 11 into the user-side unit C or the heat medium relay unit D. The refrigerant that has passed through the user-side unit C or the heat medium relay unit D passes through the low-pressure side solenoid valve 8 and flows from the low-pressure side branch 10b into the low-pressure side piping 6. The first heat exchanger 17 and the second heat exchanger 16 are sometimes referred to as internal heat exchangers.

[0029] As described above, the relay unit B switches the connection state of the user unit C or the relay unit D by switching the open / close states of the low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 of the first branch section 10. This switching switches whether the user-side heat exchanger 5 of the user unit C and the intermediate heat exchanger 30 of the relay unit D function as an evaporator or a condenser, respectively.

[0030] The first branching section 10 branches the high-pressure side pipe 7 and the low-pressure side pipe 6 for each of the user units C and the heat medium relay units D, and connects them to a first connecting pipe 40, which is one of the pipes extending from each of the user units C and the heat medium relay units D. The first branching section 10 controls whether the first connecting pipes 40 of the user units C and the heat medium relay units D are connected to the high-pressure side pipe 7 or the low-pressure side pipe 6 by closing one of the high-pressure side solenoid valve 9 and the low-pressure side solenoid valve 8 and opening the other. The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 of the first branching section 10 are sometimes collectively referred to as a second flow path switching device 10c. The second flow path switching device 10c includes a high-pressure side solenoid valve 9 and a low-pressure side solenoid valve 8, respectively, but is not limited to this configuration. For example, the second flow path switching device 10c may be configured as a three-way valve to which the high-pressure side pipe 7, the low-pressure side pipe, and the first connecting pipe 40 are connected.

[0031] (Heat source unit A) The heat source unit A is usually placed in a space outside a building such as a rooftop, and supplies cold or hot heat to the user side units C1 and C2 via the relay unit B. The heat source unit A is not limited to being placed outdoors, and may be placed in an enclosed space such as a machine room with a ventilation opening. The heat source unit A may also be placed inside a building if waste heat can be exhausted to the outside of the building through an exhaust duct. Furthermore, the heat source unit A may be placed inside a building as a water-cooled outdoor unit.

[0032] The heat source unit A incorporates a compressor 1, a first flow switching device 2 that switches the refrigerant flow direction of the heat source unit A, a heat source side heat exchanger 3, and an accumulator 29. The compressor 1, the first flow switching device 2, the heat source side heat exchanger 3, and the accumulator 29 are connected by a low pressure side pipe 6 and a high pressure side pipe 7.

[0033] The heat source side heat exchanger 3 is connected in series with the first flow rate control device 22. In addition, in the heat source unit A, a bypass pipe 25 having a second flow rate control device 26 is connected in parallel with the heat source side heat exchanger 3. The second flow rate control device 26 can adjust the flow rate to adjust the amount of refrigerant that bypasses the heat source side heat exchanger 3.

[0034] An outdoor flow control device 3m is installed near the heat source-side heat exchanger 3 to control the flow rate of a fluid, such as outdoor air. In the first embodiment, the outdoor air is sent to the heat source-side heat exchanger 3 by the outdoor flow control device 3m, where it exchanges heat with the refrigerant. The outdoor flow control device 3m is, for example, a fan that sends the outdoor air to the heat source-side heat exchanger 3. In the first embodiment, an air-cooled outdoor heat exchanger is used as an example of the heat source-side heat exchanger 3, and an outdoor fan is used as an example of the outdoor flow control device 3m. The heat source-side heat exchanger 3 may be a water-cooled outdoor heat exchanger or the like, as long as it exchanges heat between the refrigerant and another fluid. In this case, a pump is used as the outdoor flow control device 3m. A heat medium, such as outdoor air, that exchanges heat with the refrigerant in the heat source-side heat exchanger 3 may be referred to as a heat source heat medium. Although the first embodiment illustrates an example in which one heat source-side heat exchanger 3 is provided, multiple heat source-side heat exchangers may be provided.

[0035] The heat source unit A is also provided with a first connecting pipe 60a, a second connecting pipe 60b, a check valve 18, a check valve 19, a check valve 20, and a check valve 21. The first connecting pipe 60a, the second connecting pipe 60b, the check valve 18, the check valve 19, the check valve 20, and the check valve 21 allow high-pressure refrigerant to flow out of the heat source unit A through the high-pressure side pipe 7, regardless of the connection direction of the first flow path switching device 2. The first connecting pipe 60a, the second connecting pipe 60b, the check valve 18, the check valve 19, the check valve 20, and the check valve 21 allow low-pressure refrigerant to flow into the heat source unit A through the low-pressure side pipe 6.

[0036] The compressor 1 draws in a refrigerant and compresses it to a high-temperature and high-pressure state, and is configured, for example, by a capacity-controllable inverter compressor.

[0037] The first flow switching device 2 switches the refrigerant flow between heating operation and cooling operation. The first flow switching device 2 switches between two connection states. In one connection state, the first pipe 27 and the bypass pipe 25 are connected to the discharge side of the compressor 1, and the low-pressure side pipe 6 is connected to an accumulator 29 provided on the suction side of the compressor 1. The first pipe 27 is installed in parallel with the bypass pipe 25 and is a pipe leading to the heat source-side heat exchanger 3. In the other connection state, the first pipe 27 and the bypass pipe 25 are connected to the accumulator 29 provided on the suction side of the compressor 1, and the discharge side of the compressor 1 is directly connected to the high-pressure side pipe 7.

[0038] The first flow path switching device 2 is illustrated as a four-way switching valve. By switching the flow path of the first flow path switching device 2, the heat source side heat exchanger 3 functions as an evaporator during heating operation and as a condenser or a radiator during cooling operation.

[0039] In the first embodiment, the heat source-side heat exchanger 3 exchanges heat between the refrigerant and outdoor air, evaporating the refrigerant to gasify it or condensing it to liquefy it. The outdoor flow rate control device 3m forms an air path for the air flowing to the heat source-side heat exchanger 3. The accumulator 29 is provided on the suction side of the compressor 1 and stores surplus refrigerant due to differences between heating and cooling operations or surplus refrigerant due to transient changes in operation. Although the first embodiment illustrates the case where one heat source-side heat exchanger 3 is provided, multiple heat source-side heat exchangers 3 may be connected in parallel.

[0040] The check valve 18 is connected to the high-pressure side pipe 7 between the heat source side heat exchanger 3 and the relay unit B, and allows refrigerant to flow only in the direction from the heat source unit A to the relay unit B. The check valve 19 is provided in the low-pressure side pipe 6 between the relay unit B and the first flow path switching device 2, and allows refrigerant to flow only in the direction from the relay unit B to the heat source unit A. The check valve 20 is provided in the first connecting pipe 60a, and allows refrigerant discharged from the compressor 1 to circulate to the relay unit B during heating operation. The check valve 21 is provided in the second connecting pipe 60b, and allows refrigerant returning from the relay unit B to circulate to the suction side of the compressor 1 via the heat source side heat exchanger 3 or the bypass pipe 25 during heating operation.

[0041] The first connection pipe 60a connects, within the heat source unit A, the low-pressure side pipe 6 between the first flow path switching device 2 and the check valve 19 and the high-pressure side pipe 7 between the check valve 18 and the relay unit B. The second connection pipe 60b connects, within the heat source unit A, the low-pressure side pipe 6 between the check valve 19 and the relay unit B and the high-pressure side pipe 7 between the heat source-side heat exchanger 3 and the check valve 18.

[0042] The heat source unit A may also be provided with a discharge pressure gauge 51, a suction pressure gauge 52, an intermediate-pressure pressure gauge 53, and a thermometer 54. The discharge pressure gauge 51 is provided on the discharge side of the compressor 1 and measures the pressure of the refrigerant discharged from the compressor 1. The suction pressure gauge 52 is provided on the suction side of the compressor 1 and measures the pressure of the refrigerant sucked into the compressor 1. The intermediate-pressure pressure gauge 53 is provided upstream of the check valve 18 and measures the intermediate pressure, which is the pressure of the refrigerant upstream of the check valve 18. The thermometer 54 is provided on the discharge side of the compressor 1 and measures the temperature of the refrigerant discharged from the compressor 1. Pressure information and temperature information detected by the discharge pressure gauge 51, the suction pressure gauge 52, the intermediate-pressure pressure gauge 53, and the thermometer 54 are sent to the control device 50 that controls the operation of the refrigeration cycle apparatus 100, and are used to control the actuators.

[0043] The first flow rate control device 22 is connected in series to the heat source side heat exchanger 3, and is provided between the check valves 21 and 18 and the heat source side heat exchanger 3, and is configured to be able to open and close freely. The first flow rate control device 22 adjusts the flow rate of refrigerant flowing from the heat source side heat exchanger 3 to the check valve 18 during cooling operation, and adjusts the flow rate of refrigerant flowing from the check valve 21 into the heat source side heat exchanger 3 during heating operation. The first flow rate control device 22 is configured so that the flow path resistance changes continuously.

[0044] The bypass pipe 25 bypasses the heat source-side heat exchanger 3. The second flow control device 26 is provided midway along the bypass pipe 25, is configured to be freely openable and closable, and controls the flow rate of the refrigerant flowing through the bypass pipe 25. The second flow control device 26 adjusts the flow rate of the refrigerant flowing into the heat source-side heat exchanger 3. The second flow control device 26 is configured so that the flow path resistance changes continuously.

[0045] (Relay unit B) The relay unit B incorporates a first branch section 10, a second branch section 11, a gas-liquid separator 12, a first bypass pipe 14a, a second bypass pipe 14b, a third flow control device 13, a fourth flow control device 15, a first heat exchanger 17, a second heat exchanger 16, and a control device 50. The control device 50 has the same configuration and function as the control device 50 of the heat source unit A.

[0046] The first branch section 10 branches the refrigerant flowing through the high-pressure side pipe 7 toward the user unit C and the heat medium relay unit D. The first branch section 10 also merges the refrigerant flowing through the user unit C and the heat medium relay unit D and causes the refrigerant to flow into the low-pressure side pipe 6. The first branch section 10 includes a low-pressure side solenoid valve 8 and a high-pressure side solenoid valve 9 installed on first connecting pipes 40 of the user unit C and the heat medium relay unit D. In other words, the first connecting pipes 40 of the user unit C and the heat medium relay unit D are branched at the first branch section 10, one branch connected to the low-pressure side pipe 6 via the low-pressure side solenoid valve 8 and the other branch connected to the high-pressure side pipe 7 via the high-pressure side solenoid valve 9.

[0047] The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 are controlled to open and close, thereby switching the first connecting pipe 40 of the user side unit C and the heat medium relay unit D to either the low-pressure side pipe 6 or the high-pressure side pipe 7. The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 provided in the relay unit B are collectively referred to as a second flow path switching device 10c. The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 are installed on each of the two pipes where the first connecting pipe 40 branches, but they may also be configured using, for example, a three-way valve. That is, other structures may be used as long as the first connecting pipe 40 of the user side unit C and the heat medium relay unit D is configured to connect to either the low-pressure side pipe 6 or the high-pressure side pipe 7. The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 are preferably configured to be closed to prevent refrigerant from flowing through any of the user side units C and the heat medium relay units D.

[0048] The second branch section 11 branches the refrigerant flowing through the first bypass pipe 14a toward the user unit C and the heat medium relay unit D. The second branch section 11 also merges the refrigerant flowing through the user unit C and the heat medium relay unit D and causes the refrigerant to flow into the second bypass pipe 14b. The second branch section 11 has a junction where the first bypass pipe 14a and the second bypass pipe 14b meet.

[0049] The gas-liquid separator 12 is provided midway along the high-pressure side pipe 7, and separates the refrigerant that has flowed in via the high-pressure side pipe 7 into gas and liquid. The gas phase portion separated by the gas-liquid separator 12 flows to the first branch section 10, and the liquid phase portion separated by the gas-liquid separator 12 flows to the second branch section 11.

[0050] The first bypass pipe 14a is a pipe that connects the gas-liquid separator 12 and the second branch 11 in the relay unit B. The second bypass pipe 14b is a pipe that connects the second branch 11 and the low-pressure side pipe 6 in the relay unit B. The third flow control device 13 is provided midway along the first bypass pipe 14a and is configured to be able to open and close freely. The fourth flow control device 15 is provided midway along the second bypass pipe 14b and is configured to be able to open and close freely.

[0051] The first heat exchanger 17 exchanges heat between the refrigerant in the first bypass pipe 14a between the gas-liquid separator 12 and the third flow control device 13 and the refrigerant in the second bypass pipe 14b between the fourth flow control device 15 and the low-pressure side pipe 6. The second heat exchanger 16 exchanges heat between the refrigerant in the first bypass pipe 14a between the third flow control device 13 and the second branch portion 11 and the refrigerant in the second bypass pipe 14b between the fourth flow control device 15 and the first heat exchanger 17.

[0052] (User-side unit C) The user-side units C are installed at positions where they can supply conditioned air to the space to be air-conditioned, such as a room, and supply cooled air or heated air to the space to be air-conditioned using cold or hot heat from the heat source unit A supplied via the relay unit B. The user-side units C1 and C2 each have a built-in user-side heat exchanger 5c1 or 5c2 and a first flow control device 4c1 or 4c2.

[0053] In addition, a flow control device 5m is installed near the user-side heat exchangers 5c1, 5c2 to control the flow rate of indoor air, which is a fluid that exchanges heat with the refrigerant. In the first embodiment, air-cooled user-side heat exchangers are used as an example of the user-side heat exchangers 5c1, 5c2, and an indoor fan is used as an example of the flow control device 5m. However, a water-cooled user-side heat exchanger or other type may be used as long as the refrigerant exchanges heat with another fluid. Furthermore, when a water heater is used as the user-side unit C, the user-side heat exchanger 5 may be a water heat exchanger that exchanges heat between water and the refrigerant. In this case, a pump is used as the flow control device 5m.

[0054] Each of the use-side heat exchangers 5c1 and 5c2 exchanges heat between the air supplied from the flow control device 5m and the refrigerant to generate heated air or cooled air to be supplied to the air-conditioned space. The flow control device 5m forms an air path for the air flowing to the use-side heat exchangers 5c1 and 5c2. The first flow control devices 4c1 and 4c2 are provided between the second branching section 11 of the relay unit B and the use-side heat exchanger 5c1 or 5c2 and are configured to be able to open and close freely. The first flow control devices 4c1 and 4c2 adjust the flow rates of the refrigerant flowing into the use-side heat exchangers 5c1 and 5c2.

[0055] (Heat medium relay unit D) The heat medium relay unit D supplies heat or cold from the external heat source E to the refrigerant circulating in the refrigeration cycle apparatus 100. The heat medium relay unit D has built-in intermediate heat exchangers 30 that exchange heat between the refrigerant circulating in the heat source unit A, the relay unit B, and the user side units C and a heat medium that carries heat from the external heat source E, and second flow control devices 4d1 and 4d2 that control the flow rate of the refrigerant circulating in the intermediate heat exchanger 30. The second flow control devices 4d1 and 4d2 are provided between the second branch unit 11 of the relay unit B and the intermediate heat exchanger 30d1 or 30d2, and are configured to be freely openable and closable. The second flow control devices 4d1 and 4d2 adjust the flow rates of refrigerant flowing into the intermediate heat exchangers 30d1 and 30d2.

[0056] The heat medium is circulated through the heat medium circulation circuit 34 by the pump 31 and sent from the external heat source E to the intermediate heat exchanger 30. The intermediate heat exchanger 30 is, for example, a plate-type heat exchanger, and the refrigerant and the heat medium circulate inside, and the heat or cold of the heat medium is transferred to the refrigerant.

[0057] The heat medium relay unit D includes external heat source temperature sensors 32 and 33. The external heat source temperature sensor 32 detects the temperature of the heat medium flowing into the intermediate heat exchanger 30. The external heat source temperature sensor 33 detects the temperature of the heat medium flowing out of the intermediate heat exchanger 30. Of the multiple heat medium relay units D, those connected to external heat sources E with different temperatures may be referred to as a first heat medium relay unit and a second heat medium relay unit, respectively.

[0058] (External Heat Source E) The external heat source E is, for example, well water, melted snow, ice and snow, geothermal heat, or sunlight, and the heat medium can be changed appropriately depending on the target heat source. For example, if the external heat source E is well water stored in large quantities in an underground well, the well water is pumped up by a pump 31 to serve as a heat medium and is then introduced into the intermediate heat exchanger 30 by a heat medium circulation circuit 34. The well water exchanges heat with the refrigerant, flows out of the intermediate heat exchanger 30, and its temperature increases. The well water with its increased temperature is returned to the well. The well water that serves as the external heat source E is stored in large quantities underground, and even if its temperature increases after passing through the heat medium converter D and the water is returned, the temperature of the external heat source E remains almost unchanged.

[0059] The heat medium circulation circuit 34 may be configured to circulate an independent heat medium therein. As shown in FIG. 2 , the heat medium circulation circuit 34 may be connected to an external heat exchanger F that exchanges heat between an external heat source E and the heat medium flowing through the heat medium circulation circuit 34. The external heat exchanger F exchanges heat between the heat medium and the external heat source E. The heat medium that has exchanged heat in the external heat exchanger F is sent to the heat medium-to-heat medium heat exchanger 30 and exchanges heat with the refrigerant circulating through the refrigeration cycle apparatus 100. This configuration maintains the quality of the heat medium flowing through the heat medium circulation circuit 34, and ensures the durability of the heat medium circulation circuit 34 and the heat medium converter D, compared to, for example, pumping well water as the heat medium. The configuration of the heat medium circulation circuit 34 may be changed as appropriate depending on the external heat source E.

[0060] Furthermore, when geothermal energy is used as the external heat source E, piping through which a heat medium such as water circulates is extended underground to transfer the geothermal energy to the heat medium. When sunlight is used as the external heat source E, piping through which a heat medium such as water circulates is connected to a solar water heater or the like to transfer heat from the sunlight to the heat medium. The refrigeration cycle apparatus 100 according to the first embodiment effectively utilizes such an external heat source E to achieve energy savings.

[0061] 2 , multiple heat medium relay units D1, D2 can be installed in parallel on the relay unit B, allowing multiple external heat sources E to be used for the refrigeration cycle apparatus 100. For example, when the refrigeration cycle apparatus 100 is in cooling operation or cooling-dominated operation, the heat source-side heat exchanger 3 functions as a condenser, and the heat medium relay unit D1 using well water as the external heat source E1 also functions as a condenser, thereby allowing the heat medium relay unit D1 to supplement the capacity of the heat source-side heat exchanger 3 during cooling operation or cooling-dominated operation. Furthermore, when the refrigeration cycle apparatus 100 is in heating operation or heating-dominated operation, the heat source-side heat exchanger 3 functions as an evaporator, and the heat medium relay unit D2 using sunlight as the external heat source E2 also functions as an evaporator, allowing the heat medium relay unit D2 to supplement the capacity of the heat source-side heat exchanger 3 during heating operation or heating-dominated operation.

[0062] The refrigeration cycle apparatus 100 according to the first embodiment enables simultaneous cooling and heating operation by appropriately selecting the operating state of the plurality of use-side units C from cooling, heating, and hot water heating operation by switching the connection between the heat source unit A and the use-side units C using the second flow switching device 10c. In addition, the refrigeration cycle apparatus 100 can appropriately switch the external heat source E to be used as an auxiliary for or a substitute for the heat source-side heat exchanger 3 by switching the connection state with the plurality of heat medium relay units D using the second flow switching device 10c.

[0063] (Control device 50) The refrigeration cycle apparatus 100 is provided with a control device 50. The control device 50 controls actuators and the like based on refrigerant pressure information, refrigerant and heat medium temperature information, outdoor temperature information, indoor temperature information, and the like detected by each sensor provided in the refrigeration cycle apparatus 100. For example, the control device 50 controls driving of the compressor 1, switching between the first flow path switching device 2 and the second flow path switching device 10c, driving of the fan motor of the outdoor flow control device 3m, driving of the fan motor of the flow control device 5m, and the pump 31 that sends the heat medium to the heat source side heat exchanger 3.

[0064] The control device 50 controls the opening degrees of the first flow control device 22, the second flow control device 26, the third flow control device 13, and the fourth flow control device 15. The control device 50 includes a memory 50a that stores information for determining each control value. The control device 50 may be configured with hardware such as a control circuit that realizes its functions. The control device 50 may also be configured with a software program stored in a storage unit such as a semiconductor memory and a computing device such as a microcomputer or CPU (Central Processing Unit) that executes the software program. Although the first embodiment illustrates a case in which the control device 50 is provided in the heat source unit A and the relay unit B, the number of control devices 50 may be one or three or more. The control device 50 may also be installed in the user unit C or the heat medium relay unit D, or may be installed as a separate unit in a location other than the heat source unit A, the relay unit B, the user unit C, and the heat medium relay unit D.

[0065] (Operation Modes) Next, a description will be given of various operation modes performed by the refrigeration cycle apparatus 100. The operation modes of the refrigeration cycle apparatus 100 include cooling operation, heating operation, cooling-dominated operation, and heating-dominated operation.

[0066] Cooling operation is an operation mode in which all of the user-side units C are in cooling operation or stopped. Heating operation is an operation mode in which all of the user-side units C are in heating operation or stopped. Cooling-dominated operation is an operation mode in which cooling or heating can be selected for each indoor unit, and the cooling load is greater than the heating load. Cooling-dominated operation is an operation mode in which the heat-source-side heat exchanger 3 is connected to the discharge side of the compressor 1 and acts as a condenser. Heating-dominated operation is an operation mode in which heating or cooling can be selected for each indoor unit, and the heating load is greater than the cooling load. Heating-dominated operation is an operation mode in which the heat-source-side heat exchanger 3 is connected to the suction side of the compressor 1 and acts as an evaporator.

[0067] (Cooling operation) Figure 3 is an explanatory diagram of the flow of refrigerant when the refrigeration cycle apparatus 100 according to embodiment 1 is operating in cooling mode. The case of cooling mode, in which all of the user-side units C1 and C2 perform cooling, will be described. When cooling mode is performed, the control device 50 switches the first flow path switching device 2 so that the refrigerant discharged from the compressor 1 flows to the heat-source-side heat exchanger 3. In addition, the low-pressure side solenoid valves 8c1 and 8c2 connected to the user-side units C1 and C2 are opened, and the high-pressure side solenoid valves 9c1 and 9c2 are closed.

[0068] In this state, operation of the compressor 1 is started. The low-temperature, low-pressure gaseous refrigerant is compressed by the compressor 1 and discharged as high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3 via the first flow switching device 2. At this time, the refrigerant is cooled while heating the outdoor air, and becomes a medium-temperature, high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant. The medium-temperature, high-pressure refrigerant flowing out of the heat-source-side heat exchanger 3 passes through the high-pressure-side pipe 7 and is separated in the gas-liquid separator 12.

[0069] The liquid refrigerant separated by the gas-liquid separator 12 passes through the first bypass pipe 14a, exchanges heat with the refrigerant flowing through the second bypass pipe 14b in the first heat exchanger 17, then passes through the third flow control device 13, exchanges heat with the refrigerant flowing through the second bypass pipe 14b in the second heat exchanger 16, is cooled, and flows into the second branch section 11.

[0070] A portion of the refrigerant that flows into the second branch 11 is bypassed to the second bypass piping 14b, and the remainder flows into the second connecting piping 41c1, 41c2 of the user-side units C1, C2. The high-pressure liquid or gas-liquid two-phase refrigerant branched at the second branch 11 flows through the second connecting piping 41c1, 41c2 and flows into the first flow control devices 4c1, 4c2 of the user-side units C1, C2. The high-pressure liquid refrigerant is then throttled and expanded by the first flow control devices 4c1, 4c2, reducing its pressure and becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant. The refrigerant changes in the first flow control devices 4c1, 4c2 under constant enthalpy. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows out of the first flow control devices 4c1, 4c2 flows into the user-side heat exchangers 5c1, 5c2. The refrigerant is then heated while cooling the indoor air, becoming a low-temperature, low-pressure, gaseous refrigerant.

[0071] The low-temperature, low-pressure gaseous refrigerant flowing out from the user-side heat exchangers 5c1, 5c2 passes through the low-pressure-side solenoid valves 8c1, 8c2, respectively, and flows into the low-pressure-side branch 10b of the first branch 10. The low-temperature, low-pressure gaseous refrigerant that joins in the low-pressure-side branch 10b also joins with the low-temperature, low-pressure gaseous refrigerant that has been heated in the first heat exchanger 17 and the second heat exchanger 16 of the second bypass pipe 14b, passes through the low-pressure-side pipe 6 and the first flow switching device 2, flows into the compressor 1, and is compressed.

[0072] When the heat medium relay units D1, D2 are connected to the refrigeration cycle apparatus 100, whether to use the heat medium relay units D1, D2 is determined based on the magnitude relationship between the temperatures t1, t2 of the external heat sources E1, E2 and the temperature T of the heat source-side heat exchanger 3. The external heat source temperature sensor 32 that measures the temperatures t1, t2 of the external heat sources E1, E2 may be referred to as a first external heat source temperature sensor when installed in one of the heat medium relay units D1, D2, and as a second external heat source temperature sensor when installed in the other.

[0073] 4 is a diagram showing the operating states of the heat medium relay units D1 and D2 based on temperatures T, t1, and t2 of the components of the refrigeration cycle apparatus 100 according to the first embodiment. Temperature T is the temperature of outside air sent to the heat source-side heat exchanger 3. Temperature t1 is the temperature of the heat medium flowing into the intermediate heat exchanger 30d1 of the heat medium relay unit D1. Temperature t2 is the temperature of the heat medium flowing into the intermediate heat exchanger 30d2 of the heat medium relay unit D2. When the refrigeration cycle apparatus 100 is performing cooling operation, the heat medium relay units D1 and D2 are used when the heat medium temperatures t1 and t2 are lower than the temperature T of the outside air flowing into the heat source-side heat exchanger 3. Temperature T is measured by a temperature sensor 3t installed near the heat source-side heat exchanger 3. Temperature t1 is measured by an external heat source temperature sensor 32 installed upstream of the intermediate heat exchanger 30d1 in the heat medium circuit 34 of the heat medium relay unit D1. The temperature t2 is measured by an external heat source temperature sensor 32 installed upstream of the intermediate heat exchanger 30d2 in the heat medium circulation circuit 34 of the heat medium relay unit D2.

[0074] As an example, Fig. 3 shows the refrigerant flow in the cases of No. 1 and No. 2 in Fig. 4. In the states of No. 1 and No. 2 in Fig. 4, the temperatures t1 and t2 of the heat medium are lower than the temperature T of the outside air flowing into the heat source side heat exchanger 3. In this case, the refrigeration cycle apparatus 100 uses both the heat medium relay units D1 and D2 to assist the heat source side heat exchanger 3, which serves as a condenser.

[0075] The medium-temperature, high-pressure liquid refrigerant flowing out of the heat source-side heat exchanger 3 passes through the high-pressure-side pipe 7 and is separated in the gas-liquid separator 12. The separated gas refrigerant flows into the high-pressure-side branch 10a. The high-pressure-side solenoid valves 9d1, 9d2 connected to the heat medium relay units D1, D2 are opened, and the low-pressure-side solenoid valves 8d1, 8d2 are closed. The gas refrigerant in the high-pressure-side branch 10a flows through the first connecting pipes 40d1, 40d2 and into the intermediate heat exchangers 30d1, 30d2.

[0076] The gas refrigerant that flows into the heat medium-intermediate heat exchangers 30d1, 30d2 is condensed by heat exchange with the low-temperature heat medium, becoming a high-pressure, low-temperature liquid or gas-liquid two-phase refrigerant. The high-pressure, low-temperature refrigerant is throttled by the second flow control devices 4d1, 4d2, expanding and reducing its pressure, becoming a low-temperature, low-pressure, gas-liquid two-phase refrigerant. The refrigerant that flows out of the second flow control devices 4d1, 4d2 flows into the second branch section 11, where it is mixed with the refrigerant that flows into the second branch section 11 from the gas-liquid separator 12 via the first bypass pipe 14a, and then flows into the user-side units C1, C2.

[0077] In particular, in the state No. 1 in Figure 4, when comparing the temperature t1 of the heat medium circulating through the heat medium relay unit D1 with the temperature t2 of the heat medium circulating through the heat medium relay unit D2, the temperature t1 of the heat medium circulating through the heat medium relay unit D1 is higher. In other words, the temperature relationship is T > t1 > t2. In this case, the control device 50 controls the pump 31 so that more heat medium circulates through the intermediate heat exchanger 30d2 of the heat medium relay unit D2, which has a lower heat medium temperature. Alternatively, the control device 50 may adjust the second flow control device 4d2 to increase the amount of refrigerant sent to the heat medium relay unit D2.

[0078] As described above, during cooling operation of the refrigeration cycle apparatus 100, not only the heat source-side heat exchanger 3 is used as a condenser, but also the heat medium relay units D1 and D2 can be used as condensers. Therefore, in the heat source unit A, the output of the outdoor flow control device 3m that sends air to the heat source-side heat exchanger 3 can be reduced, or part of the refrigerant discharged from the compressor 1 can be sent from the bypass piping 25 to the high-pressure piping 7. The refrigerant that passes through the bypass piping 25 without passing through the heat source-side heat exchanger 3 flows from the gas-liquid separator 12 into the high-pressure branch section 10a and into the intermediate heat exchangers 30d1 and 30d2 where it is condensed. In this way, the heat medium relay units D1 and D2 can supplement the capacity of the heat source-side heat exchanger 3 by using the external heat sources E1 and E2.

[0079] Depending on the capacity of the heat medium relay units D1, D2, the heat source unit A may be configured so that no refrigerant flows through the heat source-side heat exchanger 3 and all of the refrigerant flows through the bypass pipe 25 to the high-pressure-side pipe 7. The high-pressure refrigerant is separated into liquid and gas refrigerant in the gas-liquid separator 12. The gas refrigerant flows through the high-pressure branch 10a into the heat medium relay units D1, D2, where it exchanges heat with the heat medium and is condensed. The low-temperature, high-pressure liquid or gas-liquid two-phase refrigerant is then decompressed by the flow control devices 4d1, 4d2, 4c1, 4c2 and flows into the user-side heat exchangers 5c1, 5c2, where it exchanges heat with the indoor air and expands, thereby cooling the room. In this way, the heat medium relay units D1, D2 can function as a substitute for the heat source-side heat exchanger 3 by utilizing the external heat sources E1, E2.

[0080] In cooling operation in the state No. 1 shown in FIG. 4 , the temperature t2 of the heat medium circulating through the heat medium relay unit D2 is the lowest, so the control device 50 maximizes the flow rate of the pump 31 of the heat medium relay unit D2, making it greater than the flow rate of the pump 31 of the heat medium relay unit D1. This maximizes the use of cold energy from the external heat source E2, which is an effective heat source for the condenser. The flow rates of the refrigerant flowing through the heat medium relay units D1 and D2 can also be appropriately adjusted using the high-pressure side solenoid valves 9d1 and 9d2. When the heat-source-side heat exchanger 3 is not in use, the outdoor flow rate control device 3m may be shut down.

[0081] 4, the temperatures t1 and t2 of the heat medium circulating through the heat medium relay units D1 and D2 are both lower than the outside air temperature T, but the temperature t1 of the heat medium circulating through the heat medium relay unit D1 is lower than the temperature t2 of the heat medium circulating through the heat medium relay unit D2. When multiple heat medium relay units D1 and D2 are used, it is advisable to increase the flow rate of the pump 31 of the heat medium relay unit D connected to the external heat source E with a lower temperature during cooling operation, thereby enhancing the condenser capacity of the heat medium relay unit D.

[0082] 4 , one of the temperatures t1 and t2 of the heat medium circulating through the heat medium relay units D1 and D2 is lower than the outside air temperature T, but the other is higher than the temperature T. In such a case, only the heat medium relay unit D1 or D2 through which the heat medium circulates at a temperature lower than the outside air temperature T is used, and in the heat medium relay unit D1 or D2 through which the heat medium circulates at a temperature higher than the outside air temperature T, the refrigerant is prevented from circulating by closing both the low-pressure side solenoid valve 8d and the high-pressure side solenoid valve 9d or by closing the second flow control device 4d.

[0083] In states No. 4 and No. 6 shown in Fig. 4, both temperatures t1 and t2 of the heat medium circulating through the heat medium relay units D1 and D2 are higher than the outside air temperature T. In this case, the refrigeration cycle apparatus 100 operates without using the heat medium relay unit D1 or D2 and without relying on the external heat source E.

[0084] When a plurality of heat medium relay units D are connected to the refrigeration cycle apparatus 100, the heat medium relay unit D in which the temperature of the circulating heat medium is lower than the temperature T of the outside air flowing into the heat source-side heat exchanger 3 is used in cooling operation, as shown in Fig. 4. In the first embodiment, the refrigeration cycle apparatus 100 is illustrated as an example in which two heat medium relay units D are connected to the relay unit B, but more heat medium relay units D may be connected. The number of the plurality of heat medium relay units D through which the refrigerant circulates can be adjusted as appropriate depending on the capacity of the heat source-side heat exchanger 3 and the amount of heat required for the user-side unit C.

[0085] (Cooling-Dominated Operation) FIG. 5 is an explanatory diagram of the refrigerant flow when the refrigeration cycle apparatus 100 according to the first embodiment is operating in cooling-dominated mode. Here, as an example of cooling-dominated mode, a case in which the user-side unit C1 is performing cooling and the user-side unit C2 is performing heating will be described. The user-side unit C1, in which the user-side heat exchanger 5c1 functions as an evaporator, may be referred to as the first unit, and the user-side unit C2, in which the user-side heat exchanger 5c2 functions as a condenser, may be referred to as the second unit. The cooling-dominated operation is an operating mode in which cooling or heating can be selected for each indoor unit, and the cooling load is greater than the heating load. The cooling-dominated operation is an operating mode in which the heat-source-side heat exchanger 3 is connected to the discharge side of the compressor 1 and functions as a condenser. In this case, the control device 50 switches the first flow switching device 2 so that the refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3, as in the cooling operation.

[0086] In this state, the compressor 1 is operated, and the low-temperature, low-pressure gaseous refrigerant is compressed by the compressor 1 and discharged as high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3 via the first flow switching device 2. Alternatively, some or all of the gaseous refrigerant discharged from the compressor 1 may pass through the bypass piping 25. In this case, the heat amount required for heating may be secured by the refrigerant passing through the bypass piping 25, or the refrigerant may be condensed in the heat-source-side heat exchanger 3, leaving the heat amount required for heating. The refrigerant that has passed through the heat-source-side heat exchanger 3 and the bypass piping 25 is in a medium-temperature, high-pressure gas-liquid two-phase state.

[0087] The medium-temperature, high-pressure two-phase gas-liquid refrigerant passes through the high-pressure side pipe 7 and flows into the gas-liquid separation device 12. The gas-liquid separation device 12 separates the refrigerant into gaseous and liquid refrigerants. The gaseous refrigerant separated in the gas-liquid separation device 12 flows from the high-pressure side branch 10a of the first branch 10 through the high-pressure side solenoid valve 9c2 into the user-side heat exchanger 5c2 that performs heating. The refrigerant is then cooled while heating the indoor air, and becomes a medium-temperature, high-pressure liquid refrigerant. The refrigerant flowing out of the user-side heat exchanger 5c2 that performs heating passes through the first flow control device 4c2 and flows into the second branch 11.

[0088] On the other hand, the liquid refrigerant separated by the gas-liquid separator 12 flows into the first heat exchanger 17 and is cooled by heat exchange with the low-pressure refrigerant flowing through the second bypass pipe 14b. The refrigerant flowing out of the first heat exchanger 17 passes through the third flow control device 13 and the second heat exchanger 16 and flows into the second branch section 11.

[0089] A portion of the liquid refrigerant that joins at the second branch 11 is bypassed to the second bypass pipe 14b, and the remainder flows into the first flow control device 4c1 provided in the user-side unit C1 that performs cooling. The high-pressure liquid refrigerant is throttled and expanded by the first flow control device 4c1, reducing its pressure and becoming a low-temperature, low-pressure, gas-liquid two-phase refrigerant. The change in the refrigerant at the first flow control device 4c1 is carried out under a constant enthalpy.

[0090] The low-temperature, low-pressure refrigerant in a gas-liquid two-phase state that flows out of the first flow control device 4c1 flows into the user-side heat exchanger 5c1, which performs cooling. The refrigerant is heated while cooling the indoor air, and becomes a low-temperature, low-pressure gaseous refrigerant. The low-temperature, low-pressure gaseous refrigerant that flows out of the user-side heat exchanger 5c1 passes through the low-pressure-side solenoid valve 8c1 and flows into the low-pressure-side branch section 10b. The low-temperature, low-pressure gaseous refrigerant that flows into the low-pressure-side branch section 10b via the user-side heat exchanger 5c1 merges with the low-temperature, low-pressure gaseous refrigerant that has been heated in the first heat exchanger 17 and the second heat exchanger 16 of the second bypass pipe 14b, passes through the low-pressure-side pipe 6 and the first flow switching device 2, and flows into the compressor 1, where it is compressed.

[0091] In cooling-dominated operation, as in cooling operation, when the heat medium relay units D1 and D2 are connected to the refrigeration cycle apparatus 100, it is determined whether to use the heat medium relay units D1 and D2 based on the magnitude relationship between the temperatures t1 and t2 of the external heat sources E1 and E2 and the temperature T of the water flowing into the heat source-side heat exchanger 3.

[0092] As shown in Fig. 4, in cooling-dominated operation, similarly to cooling operation, the heat medium relay units D1 and D2 are used when the heat medium temperatures t1 and t2 are lower than the temperature T of the outside air flowing into the heat source-side heat exchanger 3. In refrigerant-dominated operation, the heat medium relay units D1 and D2 are used in the same way as in cooling operation.

[0093] Fig. 5 shows, as an example, the refrigerant flows in the cases of No. 1 and No. 2 in Fig. 4. The flow rates of the pumps 31 of the relay units D1 and D2 are adjusted in the same manner as in cooling operation, as shown in Fig. 4. The relay units D1 and D2 can appropriately control whether or not to circulate the refrigerant by operating the low-pressure side solenoid valves 8d1 and 8d2, the high-pressure side solenoid valves 9d1 and 9d2, and the second flow control devices 4d1 and 4d2.

[0094] 6 is an explanatory diagram of the flow of refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is in heating operation. A case will be described in which both the user side units C1 and C2 are attempting to perform heating. When the heating operation is performed, the control device 50 switches the first flow path switching device 2 so that the refrigerant discharged from the compressor 1 flows directly into the high-pressure side pipe 7 and the first branch portion 10.

[0095] In this state, compressor 1 is operated, and the low-temperature, low-pressure gaseous refrigerant is compressed by compressor 1 and discharged as high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant discharged from compressor 1 flows into high-pressure side branch section 10a of first branch section 10 via first flow switching device 2 and high-pressure side piping 7. The high-temperature, high-pressure gaseous refrigerant that has flowed into high-pressure side branch section 10a is branched, passes through high-pressure side solenoid valves 9c1, 9c2, and flows into user-side heat exchangers 5c1, 5c2. The refrigerant is then heated while cooling the indoor air, and becomes a medium-temperature, high-pressure liquid refrigerant.

[0096] The medium-temperature, high-pressure liquid refrigerant flowing out of the user-side heat exchangers 5c1, 5c2 flows into the first flow control devices 4c1, 4c2, where it is expanded and decompressed to become a medium-temperature, medium-pressure, two-phase gas-liquid refrigerant, which then joins at the second branch section 11. The refrigerant that has flowed into the second branch section 11 flows into the second bypass pipe 14b or the heat medium relay units D1, D2.

[0097] A portion of the refrigerant that has flowed into the second branch section 11 passes through the second bypass pipe 14b and the fourth flow control device 15 and flows into the low-pressure branch section 10b of the first branch section 10. In addition, a portion of the refrigerant that has flowed into the second branch section 11 flows into the relay units D1 and D2. The refrigerant that has flowed into the relay units D1 and D2 is expanded and decompressed to medium-temperature and medium-pressure in the second flow control devices 4d1 and 4d2, and then evaporates through heat exchange with the heat medium from the external heat sources E1 and E2 in the intermediate heat exchangers 30d1 and 30d2, becoming a low-temperature, low-pressure gas refrigerant that flows into the low-pressure branch section 10b of the first branch section 10.

[0098] The refrigerant that joins at the low-pressure branch 10b passes through the low-pressure piping 6 and flows into the first flow control device 22, where it becomes a low-temperature, low-pressure, two-phase gas-liquid refrigerant, and is heated while cooling the outdoor air in the heat source heat exchanger 3, becoming a low-temperature, low-pressure gaseous refrigerant. Note that if the refrigerant that has entered the low-pressure piping 6 has become a sufficiently low-temperature, low-pressure gaseous refrigerant, it may be sent to the suction side of the compressor 1 via the bypass piping 25 without passing through the heat source heat exchanger 3.

[0099] Alternatively, the entire refrigerant flowing into the second branch section 11 from the user-side units C1, C2 operating in heating mode may be directed to the heat medium relay units D1, D2. This allows the entire refrigerant to be evaporated using the external heat sources E1, E2, reducing the load on the heat-source-side heat exchanger 3 and leading to energy savings. If the entire refrigerant has been converted into a sufficiently low-temperature, low-pressure gas refrigerant in the heat medium relay units D1, D2, the refrigeration cycle apparatus 100 may draw the refrigerant into the compressor 1 without using the outdoor flow rate control device 3m or the heat-source-side heat exchanger 3.

[0100] FIG. 6 shows, as an example, the refrigerant flows for the cases No. 4 and No. 6 in FIG. 4 . In the state of No. 4 in FIG. 4 , the temperatures t1 and t2 of the heat medium circulating through the heat medium relay unit D1 are higher than the temperature T of the outside air flowing into the heat source-side heat exchanger 3. Comparing the temperature t1 of the heat medium circulating through the heat medium relay unit D1 with the temperature t2 of the heat medium circulating through the heat medium relay unit D2, the temperature t1 of the heat medium circulating through the heat medium relay unit D1 is higher. In other words, the temperature relationship is t1 > t2 > T. In this case, the control device 50 controls the pump 31 so that more heat medium circulates through the intermediate heat exchanger 30d1 of the heat medium relay unit D1, which has the higher heat medium temperature. Alternatively, the control device 50 may adjust the second flow control device 4d1 to increase the amount of refrigerant sent to the heat medium relay unit D1.

[0101] In the heating operation in the state No. 4 shown in FIG. 4 , the temperature t1 of the heat medium circulating through the heat medium relay unit D1 is the highest, so the control device 50 maximizes the flow rate of the pump 31 of the heat medium relay unit D1, making it greater than the flow rate of the pump 31 of the heat medium relay unit D2. This allows the refrigeration cycle apparatus 100 to utilize as much heat as possible from the external heat source E1, which is an effective heat source for use in the evaporator. The flow rates of the refrigerant flowing through the heat medium relay units D1 and D2 can also be appropriately adjusted using the high-pressure side solenoid valves 9d1 and 9d2. When the system is in a state where refrigerant can be drawn into the compressor 1 without using the heat source-side heat exchanger 3, the outdoor flow rate control device 3m may be stopped.

[0102] In the heating operation in the state No. 6 shown in Fig. 4, the relationship among the outside air temperature T, the temperature t1 of the heat medium circulating through the heat medium relay unit D1, and the temperature t2 of the heat medium circulating through the heat medium relay unit D2 is t2 > t1 > T. In the heating operation in the state No. 6, the temperature t2 of the heat medium circulating through the heat medium relay unit D2 is the highest, so the control device 50 maximizes the flow rate of the pump 31 of the heat medium relay unit D2, making it greater than the flow rate of the pump 31 of the heat medium relay unit D1. In this way, when the refrigeration cycle apparatus 100 uses multiple heat medium relay units D1 and D2, it is preferable to increase the flow rate of the pump 31 of the heat medium relay unit D connected to the external heat source E with a higher temperature in the heating operation to enhance the evaporator capacity of the heat medium relay unit D.

[0103] In the states No. 3 and No. 5 shown in Fig. 4, one of the temperatures t1 and t2 of the heat medium circulating through the heat medium relay units D1 and D2 is higher than the outside air temperature T, but the other is lower than the temperature T. In such a case, only the heat medium relay unit D1 or D2 through which the heat medium circulates at a temperature higher than the outside air temperature T is used, and in the heat medium relay unit D1 or D2 through which the heat medium circulates at a temperature lower than the outside air temperature T, the refrigerant is prevented from circulating by closing both the low-pressure side solenoid valve 8d and the high-pressure side solenoid valve 9d or by closing the second flow control device 4d.

[0104] In the states No. 1 and No. 2 shown in Fig. 4, both temperatures t1 and t2 of the heat medium circulating through the heat medium relay units D1 and D2 are lower than the outside air temperature T. In this case, the refrigeration cycle apparatus 100 operates without using the heat medium relay unit D1 or D2 and without relying on the external heat source E.

[0105] When a plurality of heat medium relay units D are connected to the refrigeration cycle apparatus 100, the heating operation uses the heat medium relay unit D in which the temperatures t1 and t2 of the circulating heat medium are higher than the temperature T of the outside air flowing into the heat source-side heat exchanger 3, as shown in Fig. 4. In the first embodiment, the refrigeration cycle apparatus 100 has two heat medium relay units D connected to the relay unit B, but more heat medium relay units D may be connected. The number of the plurality of heat medium relay units D through which the refrigerant circulates can be adjusted as appropriate depending on the capacity of the heat source-side heat exchanger 3 and the amount of heat required for the user-side unit C.

[0106] (Heating-dominant operation) FIG. 7 is an explanatory diagram of the refrigerant flow when the refrigeration cycle apparatus 100 according to the first embodiment is in heating-dominant operation. Here, as an example of the heating-dominant operation, a case where the user-side unit C1 is in heating operation and the user-side unit C2 is in cooling operation as shown in FIG. 7 will be described. The heating-dominant operation is an operation mode in which heating or cooling can be selected for each indoor unit, and the heating load is greater than the cooling load. The heating-dominant operation is an operation mode in which the heat-source-side heat exchanger 3 is connected to the suction side of the compressor 1 and functions as an evaporator. In this case, the control device 50 switches the first flow path switching device 2 so that the refrigerant discharged from the compressor 1 flows directly into the high-pressure side pipe 7 and the first branch 10, as in the heating operation.

[0107] In this case, the control device 50 switches the first flow path switching device 2 so that the refrigerant discharged from the compressor 1 flows into the first branch portion 10. In addition, the low-pressure side solenoid valve 8c1 connected to the utilization side unit C1 is closed, and the high-pressure side solenoid valve 9c1 is opened.

[0108] In this state, the compressor 1 is operated, and the low-temperature, low-pressure gaseous refrigerant is compressed by the compressor 1 and discharged as a high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 1 flows into the high-pressure side pipe 7 via the first flow switching device 2.

[0109] The medium-temperature, high-pressure two-phase gas-liquid refrigerant passes through the high-pressure side pipe 7 and flows into the gas-liquid separation device 12, where it is separated into gaseous refrigerant and liquid refrigerant. The gaseous refrigerant separated in the gas-liquid separation device 12 flows from the high-pressure side branch 10a of the first branch 10 through the high-pressure side solenoid valve 9c1 into the user-side heat exchanger 5c1 that performs heating. The refrigerant is then cooled while heating the indoor air, and becomes a medium-temperature, high-pressure liquid refrigerant. The refrigerant flowing out of the user-side heat exchanger 5c1 that performs heating passes through the first flow control device 4c1 and flows into the second branch 11.

[0110] Meanwhile, the liquid refrigerant separated in the gas-liquid separator 12 flows into the first bypass pipe 14a and is cooled by exchanging heat with the low-pressure refrigerant flowing through the second bypass pipe 14b in the first heat exchanger 17. The refrigerant flowing out of the first heat exchanger 17 passes through the third flow control device 13 and the second heat exchanger 16 and flows into the second branch section 11.

[0111] After passing through the first bypass pipe 14a or the user-side unit C1 where the two refrigerants join at the second branch 11, a portion of the refrigerant is bypassed to the second bypass pipe 14b, and the remainder flows into the first flow control device 4c2 provided in the user-side unit C2 that performs cooling. The refrigerant that flows into the user-side unit C2 is throttled and expanded by the first flow control device 4c2, reducing its pressure and becoming a low-temperature, low-pressure, gas-liquid two-phase state. The change in the refrigerant in the first flow control device 4c2 occurs under a constant enthalpy.

[0112] The low-temperature, low-pressure refrigerant in a gas-liquid two-phase state that flows out of the first flow control device 4c2 flows into the user-side heat exchanger 5c2, which performs cooling. The refrigerant is heated while cooling the indoor air, and becomes a low-temperature, low-pressure gaseous refrigerant. The low-temperature, low-pressure gaseous refrigerant that flows out of the user-side heat exchanger 5c1 passes through the low-pressure-side solenoid valve 8c2 and flows into the low-pressure-side branch 10b. The low-temperature, low-pressure gaseous refrigerant that flows into the low-pressure-side branch 10b merges with the low-temperature, low-pressure gaseous refrigerant that has been heated in the first heat exchanger 17 and the second heat exchanger 16 of the second bypass piping 14b, passes through the low-pressure piping 6, passes through the heat source-side heat exchanger 3 or the bypass piping 25, and flows into the compressor 1, where it is compressed.

[0113] In the heating-dominant operation, as in the heating operation, when the heat medium relay units D1 and D2 are connected to the refrigeration cycle apparatus 100, it is determined whether to use the heat medium relay units D1 and D2 based on the magnitude relationship between the temperatures t1 and t2 of the external heat sources E1 and E2 and the temperature T of the water flowing into the heat source-side heat exchanger 3.

[0114] 4, even in heating-dominated operation, the heat medium relay units D1 and D2 are used when the temperatures t1 and t2 of the heat medium are higher than the temperature T of the outside air flowing into the heat source-side heat exchanger 3. In heating-dominated operation, the heat medium relay units D1 and D2 are used in the same way as in heating operation.

[0115] Fig. 7 shows, as an example, the refrigerant flows in the cases of No. 4 and No. 6 in Fig. 4. The flow rates of the pumps 31 of the relay units D1 and D2 are adjusted in the same manner as in the heating operation, as shown in Fig. 4. The relay units D1 and D2 can appropriately control whether to refrigerate by operating the low-pressure side solenoid valve 8d, the high-pressure side solenoid valve 9d, and the second flow control device 4d.

[0116] (Control of the Refrigeration Cycle Apparatus 100) Fig. 8 is a flowchart showing the operation of the refrigeration cycle apparatus 100 according to the first embodiment. Here, a control flow for determining the state in which the heat medium relay unit D is to be operated during the operation of the refrigeration cycle apparatus 100 will be described. As shown in Fig. 8, when the refrigeration cycle apparatus 100 is operating, the operation mode of the refrigeration cycle apparatus 100 is first confirmed. Because the heat medium relay unit D assists the heat source side heat exchanger 3, it is sufficient to first confirm whether the heat source side heat exchanger 3 is operating as a condenser or an evaporator. In step A1, the control device 50 determines whether the operation mode is cooling and cooling-dominant operation (step A2) or heating and heating-dominant operation (step A7).

[0117] Next, the control device 50 acquires the temperature T of the outside air or another heat medium flowing into the heat source-side heat exchanger 3, and the temperatures t1 and t2 of the heat medium flowing into the intermediate heat exchanger 30 of the heat medium relay unit D (steps A3 and A8). The temperature T of the outside air or another heat medium flowing into the heat source-side heat exchanger 3 is temperature data measured by, for example, a temperature sensor 3t. The temperatures t1 and t2 of the heat medium flowing into the intermediate heat exchanger 30 of the heat medium relay unit D are temperature data measured by, for example, an external heat source temperature sensor 32 in the heat medium circulation circuit 34 at which the heat medium flows into the intermediate heat exchanger 30.

[0118] When the refrigeration cycle apparatus 100 is in cooling operation or cooling-dominant operation (step A2), the control device 50 compares the measurement results of the temperature T of the heat source-side temperature sensor and the temperatures t1 and t2 of the heat medium converter temperature sensors (step A3), and determines whether the condition T > t1, t2 is satisfied (step A4).

[0119] The control device 50 controls the heat medium relay units D that satisfy the above condition T > t1, t2 to operate as condensers (step A5). For the heat medium relay units D that satisfy the condition, the control device 50 operates the second flow switching device 10c to control the refrigerant to be sent and also controls the flow rate of the heat medium circulation circuit 34. The control to adjust the flow rate of the heat medium circulation circuit 34 may, for example, be performed by comparing the temperatures measured by the external heat source temperature sensor 32 located upstream of the intermediate heat exchanger 30 with those measured by the external heat source temperature sensor 33 located downstream, and increasing the flow rate of the pump 31 when the difference between the measured temperatures is greater than a predetermined value.

[0120] The control device 50 also controls the heat medium relay unit D that does not satisfy the above conditions T > t1 and t2 so that heat exchange between the refrigerant and the heat medium does not occur (step A6). The control device 50 operates the second flow switching device 10c to prevent refrigerant from flowing into the heat medium relay unit D that does not satisfy the conditions. The control device 50 also stops the pump 31 of the heat medium circulation circuit 34 of the heat medium relay unit D that does not satisfy the conditions. However, even if the conditions T > t1 and t2 are not satisfied, if the capacity of the heat source side heat exchanger 3 is insufficient, the heat medium relay unit D that does not satisfy the conditions T > t1 and t2 may be used. That is, if there is a heat medium relay unit D that does not satisfy the conditions T > t1 and t2 (No in step A4), the control device 50 determines whether the heat source side heat exchanger 3 has sufficient capacity as a condenser (step A11). If the capacity of the heat source side heat exchanger 3 is insufficient (Yes in step A11), the control device 50 may control the heat medium relay unit D that does not satisfy the conditions to be used (step A12).

[0121] When the refrigeration cycle apparatus 100 is in heating operation or heating-dominant operation (step A7), the control device 50 compares the measurement results of the temperature T of the heat source-side temperature sensor and the temperatures t1 and t2 of the heat medium converter temperature sensors (step A8) and determines whether the condition T<t1, t2 is satisfied (step A9).

[0122] The control device 50 controls the heat medium relay units D that satisfy the above condition T<t1, t2 to operate as evaporators (step A10). For the heat medium relay units D that satisfy the condition, the control device 50 operates the second flow switching device 10c to control the refrigerant to be sent and also controls the flow rate of the heat medium circulation circuit 34. The control to adjust the flow rate of the heat medium circulation circuit 34 may, for example, be performed by comparing the temperatures measured by the external heat source temperature sensor 32 located upstream of the intermediate heat exchanger 30 with those measured by the external heat source temperature sensor 33 located downstream, and increasing the flow rate of the pump 31 when the difference between the measured temperatures is greater than a predetermined value.

[0123] Furthermore, the control device 50 basically controls the relay units D that do not satisfy the above condition T<t1, t2 so as not to perform heat exchange between the refrigerant and the heat medium (step A6). However, even if the condition T>t1, t2 is not satisfied, if the capacity of the heat source side heat exchanger 3 is insufficient, the relay units D that do not satisfy the condition T>t1, t2 may be used (steps A11 and A12). This is the same as in the cooling operation and cooling-dominant operation.

[0124] In steps A4 and A9, if there are multiple relay units D that meet the conditions, the temperatures t1 and t2 of the heat medium circulating through the relay units D may be compared, and the flow rate of the circulating heat medium may be controlled as shown in Fig. 4. Alternatively, the flow rate of the refrigerant flowing into the relay unit D may be adjusted according to the temperatures t1 and t2 of the heat medium circulating through the relay unit D.

[0125] (Operation of the Refrigeration Cycle Apparatus 100) As described above, the refrigeration cycle apparatus 100 according to the first embodiment can operate in four modes, namely, cooling operation, cooling-dominated operation, heating operation, and heating-dominated operation, using the user-side units C. The refrigeration cycle apparatus 100 has a plurality of user-side units C, and each user-side heat exchanger 5 can be used as a condenser or an evaporator, enabling simultaneous cooling and heating operation. The refrigeration cycle apparatus 100 also includes a heat medium relay unit D, which can be used as a condenser or an evaporator by switching the refrigerant flow path in the same way as the user-side units C, and can be used to supplement or complement the heat-source-side heat exchanger 3.

[0126] 9 and 10 are Mollier diagrams of the refrigeration cycle apparatus 100 according to the first embodiment during cooling operation. As shown in Fig. 9 , during cooling operation, the heat source-side heat exchanger 3 functions as a condenser, and the use-side heat exchanger 5 of the use-side unit C functions as an evaporator. The number of use-side heat exchangers 5 shown in Fig. 9 is not limited to one, and multiple use-side heat exchangers may be used. The refrigerant condensed in the heat source-side heat exchanger 3 is decompressed by a flow control device 4, which is an expander, or the like, and evaporates in the use-side heat exchangers 5 of the use-side units C1 and C2, and is then drawn into the compressor 1. The refrigeration cycle apparatus 100 operates in a heat pump cycle by utilizing heat radiation in the heat source-side heat exchanger 3 and heat absorption in the use-side heat exchangers 5c1 and 5c2.

[0127] The Mollier diagram in FIG. 10 shows the state of the refrigeration cycle apparatus 100 shown in FIG. 3 , in which the intermediate heat exchangers 30d1 and 30d2 are directly connected to the heat source-side heat exchanger 3. As a result, the intermediate heat exchangers 30d1 and 30d2 function as auxiliary condensers and function as a single condenser together with the heat source-side heat exchanger 3. The intermediate heat exchangers 30d1 and 30d2 are connected in parallel, but they may also be connected in series. In this case, a refrigerant pipe may be provided that flows from the relay unit D1 to the relay unit D2. Specifically, a path may be provided that allows the refrigerant to flow from the second connecting pipe 41d1 of the relay unit D1 to the first connecting pipe 40d2 of the relay unit D2 in FIG. 3 . This allows the relay units D1 and D2 to more efficiently subcool the refrigerant.

[0128] Fig. 11 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during cooling-dominated operation. The Mollier diagram in Fig. 11 illustrates the state of the refrigeration cycle apparatus 100 illustrated in Fig. 5, in which the intermediate heat exchangers 30d1 and 30d2 and the use-side heat exchanger 5c2 operating in heating mode are connected in series to the heat-source-side heat exchanger 3 and function as a condenser. The intermediate heat exchangers 30d1 and 30d2 and the use-side heat exchanger 5c2 operating in heating mode are connected in parallel with each other. The intermediate heat exchangers 30d1 and 30d2 and the use-side heat exchanger 5c2 operating in heating mode may also be connected in series. In this case, it is preferable to provide refrigerant piping that allows refrigerant to circulate between the use-side unit C2 and the heat medium relay units D1 and D2.

[0129] 12 and 13 are Mollier diagrams of the refrigeration cycle apparatus 100 according to Embodiment 1 during heating operation. As shown in Fig. 12, during heating operation, the use-side heat exchangers 5c1 and 5c2 function as condensers, and the heat-source-side heat exchanger 3 functions as an evaporator. The number of use-side heat exchangers 5 shown in Fig. 12 is not limited to multiple, and may be single. The refrigerant condensed in the use-side heat exchangers 5 of the use-side units C1 and C2 is decompressed in the expanders, evaporated in the heat-source-side heat exchanger 3, and drawn into the compressor 1. The refrigeration cycle of the refrigeration cycle apparatus 100 is performed by heat radiation in the use-side heat exchangers 5c1 and 5c2 and heat absorption in the heat-source-side heat exchanger 3.

[0130] The Mollier diagram shown in FIG. 13 illustrates the state of the refrigeration cycle apparatus 100 shown in FIG. 6 , in which the user-side heat exchangers 5c1 and 5c2 are directly connected to the discharge side (high-pressure side) of the compressor 1. As a result, the user-side heat exchangers 5c1 and 5c2 function as condensers, performing heating operation. The refrigerant flowing out of the user-side heat exchangers 5c1 and 5c2 is decompressed by the first flow control devices 4c1 and 4c2 and flows into the intermediate heat exchangers 30d1 and 30d2. The intermediate heat exchangers 30d1 and 30d2 are connected in series with the heat source-side heat exchanger 3 and function as an evaporator together with the heat source-side heat exchanger 3. Although the intermediate heat exchangers 30d1 and 30d2 are connected in parallel, they may also be connected in series. In this case, it is preferable to provide a refrigerant pipe flowing from the heat medium relay unit D1 to the heat medium relay unit D2. This allows the refrigerant to be superheated more efficiently using the heat medium relay units D1 and D2.

[0131] FIG. 14 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during heating-dominated operation. The Mollier diagram shown in FIG. 14 illustrates the state of the refrigeration cycle apparatus 100 shown in FIG. 7 , in which the discharge side of the compressor 1 is directly connected to the use-side heat exchanger 5c1 that is performing heating operation. The use-side heat exchanger 5c1 functions as a condenser and cools the refrigerant while heating the indoor air. The refrigerant that flows out of the use-side heat exchanger 5c1 is decompressed in an expander and flows into the use-side heat exchanger 5c2 that is performing cooling operation and the intermediate heat exchangers 30d1 and 30d2. The use-side heat exchanger 5c2 and the intermediate heat exchangers 30d1 and 30d2 are directly connected to the heat-source-side heat exchanger 3. As a result, the intermediate heat exchangers 30d1 and 30d2 function as auxiliary evaporators and function as an evaporator together with the heat-source-side heat exchanger 3.

[0132] The refrigeration cycle apparatus 100 according to the first embodiment can improve the efficiency of the entire system by balancing the cooling load of the user-side unit C with the heating load and hot water supply load, and can also balance the load of the user-side unit C with the load of the heat source unit A by supplying heat from the external heat source E to assist the heat source-side heat exchanger 3. The refrigeration cycle apparatus 100 can reduce the load of the heat source unit A by supplying heat from the external heat source E, thereby achieving energy savings overall.

[0133] Embodiment 2 A refrigeration cycle apparatus 200 according to Embodiment 2 is configured by changing the connection of the plurality of heat medium relay units D1, D2 of the refrigeration cycle apparatus 100 according to Embodiment 1. The following description will focus on the differences between Embodiment 2 and Embodiment 1.

[0134] In the refrigeration cycle apparatus 100 according to the first embodiment, a configuration has been described in which a plurality of heat medium relay units D1 and D2 are connected in parallel to each other in the refrigerant circuit. However, in the refrigeration cycle apparatus 200 according to the second embodiment, a plurality of heat medium relay units D1 and D2 are configured to be connected in series to each other.

[0135] 15 is an example of a circuit diagram showing a refrigeration cycle apparatus 200 according to Embodiment 2. The refrigeration cycle apparatus 200 is configured such that, of two heat medium relay units D1 and D2, refrigerant that has passed through one heat medium relay unit D1 further passes through the other heat medium relay unit D2. Specifically, the refrigeration cycle apparatus 200 has a connection pipe 71 that connects the second connection pipe 41d1 of one heat medium relay unit D1 to the first connection pipe 40d2 of the other heat medium relay unit D2. The second connection pipe 41d1 is provided with, for example, a three-way valve 70.

[0136] 15 shows the refrigeration cycle apparatus 200 in cooling operation. The refrigeration cycle apparatus 200 is configured such that, during cooling operation, the refrigerant flowing from the high-pressure branch 10a of the first branch 10 into the relay unit D1 passes through the connecting pipe 71 and flows into the relay unit D2. The refrigerant flowing from the intermediate heat exchanger 30d1 of the relay unit D1 through the three-way valve 70 and the connecting pipe 71 and then passes through the relay unit D2, flows into the second branch 11. The refrigerant flowing into the second branch 11 flows into the user side units C1 and C2 and is evaporated, similar to the cooling operation in the first embodiment.

[0137] Fig. 16 is a Mollier diagram of the refrigeration cycle apparatus 200 during cooling operation according to Embodiment 2. The refrigeration cycle apparatus 200 shown in Fig. 15 is connected so that refrigerant from the heat source side heat exchanger 3 flows into the intermediate heat exchangers 30d1 and 30d2 via the first branch section 10, and the intermediate heat exchangers 30d1 and 30d2 are connected in series with each other. As a result, the intermediate heat exchangers 30d1 and 30d2 function as auxiliary condensers and function together with the heat source side heat exchanger 3 as if they were a single condenser.

[0138] (Cooling-dominated operation) Fig. 17 is an example of a circuit diagram showing the refrigeration cycle apparatus 200 according to the second embodiment. Fig. 17 shows a case where the refrigeration cycle apparatus 200 is operating in cooling-dominated operation. Even in cooling-dominated operation, the refrigeration cycle apparatus 200 is configured so that the refrigerant that has passed through the relay unit D1 passes through the connecting pipe 71 and flows into the relay unit D2. The refrigerant that has passed from the relay unit D1 through the three-way valve 70 and the connecting pipe 71 and then passes through the relay unit D2 flows into the second branch section 11. As in the cooling operation according to the first embodiment, the refrigerant that has flowed into the second branch section 11 merges with the refrigerant condensed in the user-side unit C2, flows into the user-side unit C1, and is evaporated.

[0139] Fig. 18 is a Mollier diagram during cooling operation of the refrigeration cycle apparatus 200 according to Embodiment 2. In the refrigeration cycle apparatus 200 shown in Fig. 17, the intermediate heat exchangers 30d1 and 30d2 are connected in series with each other, and the use-side heat exchanger 5c2 performing heating operation is connected in parallel to the intermediate heat exchangers 30d1 and 30d2. The intermediate heat exchangers 30d1 and 30d2 and the use-side heat exchanger 5c2 are connected so that the refrigerant from the heat-source-side heat exchanger 3 flows into them via the first branch portion 10, and each of them functions as a condenser.

[0140] (Heating Operation) FIG. 19 is an example of a circuit diagram showing a refrigeration cycle apparatus 200 according to Embodiment 2. FIG. 19 illustrates the refrigeration cycle apparatus 200 in heating operation. The refrigeration cycle apparatus 200 is configured such that, during heating operation, refrigerant passing through the relay unit D2 passes through the connecting pipe 71 and flows into the relay unit D1. The refrigerant that flows into the user units C1 and C2 from the high-pressure branch 10a of the first branch 10 is condensed and flows into the second branch 11. The refrigerant that flows into the second branch 11 flows into the relay units D1 and D2 and is evaporated, similar to the heating operation according to Embodiment 1. Specifically, the refrigerant flows from the second branch 11 into the relay unit D2, passes through the connecting pipe 71 and the three-way valve 70, passes through the relay unit D1, and flows into the low-pressure branch 10b of the first branch 10.

[0141] Fig. 20 is a Mollier diagram of the refrigeration cycle apparatus 200 according to the second embodiment during heating operation. In the refrigeration cycle apparatus 200 shown in Fig. 19, the use-side heat exchangers 5c1 and 5c2 are connected so that the refrigerant flowing out from the discharge side (high-pressure side) of the compressor 1 flows into the use-side heat exchangers 5c1 and 5c2 via the high-pressure-side branch 10a. As a result, the use-side heat exchangers 5c1 and 5c2 function as condensers, and the use-side units C1 and C2 perform heating operation. The refrigerant flowing out of the use-side heat exchangers 5c1 and 5c2 is decompressed by the first flow control devices 4c1 and 4c2 and flows into the second branch 11. The refrigerant flowing into the second branch 11 first flows into the intermediate heat exchanger 30d2 and then flows into the intermediate heat exchanger 30d1. 19 is configured such that the refrigerant that has passed through the intermediate heat exchangers 30d1 and 30d2 passes through the low-pressure side branch portion 10b and flows into the heat source side heat exchanger 3, and the intermediate heat exchangers 30d1 and 30d2 are connected in series. The intermediate heat exchangers 30d1 and 30d2 serve as auxiliary evaporators, and function together with the heat source side heat exchanger 3 as if they were a single evaporator.

[0142] (Heating-Dominated Operation) FIG. 21 is an example of a circuit diagram showing a refrigeration cycle apparatus 200 according to Embodiment 2. FIG. 21 illustrates a case in which the refrigeration cycle apparatus 200 is operating in heating-dominated operation. Even in heating-dominated operation, the refrigeration cycle apparatus 200 is configured so that the refrigerant passing through the relay unit D2 passes through the connecting pipe 71 and flows into the relay unit D1. In heating-dominated operation, the refrigerant flowing from the high-pressure branch 10a of the first branch 10 into the user-side unit C1 operating in heating mode is condensed and flows into the second branch 11. Similar to the heating-dominated operation in Embodiment 1, the refrigerant flowing into the second branch 11 flows into the user-side unit C2 and the relay units D1 and D2 operating in cooling mode and evaporates. Specifically, the refrigerant flows from the second branch 11 into the user-side unit C2 and the relay unit D2. The refrigerant that has flowed into the relay unit D2 passes through the connecting pipe 71 and the three-way valve 70 and then through the relay unit D1, and flows into the low-pressure branch 10b of the first branch 10.

[0143] Fig. 22 is a Mollier diagram of the refrigeration cycle apparatus 200 according to Embodiment 2 during heating-dominated operation. In the refrigeration cycle apparatus 200 shown in Fig. 22, the intermediate heat exchangers 30d1 and 30d2 are connected in series with each other, and the use-side heat exchanger 5c2 in cooling operation is connected in parallel to the intermediate heat exchangers 30d1 and 30d2. The intermediate heat exchangers 30d1 and 30d2 and the use-side heat exchanger 5c2 are each connected in series with the heat-source-side heat exchanger 3 and function as evaporators. The intermediate heat exchangers 30d1 and 30d2 serve as auxiliary evaporators and function together with the heat-source-side heat exchanger 3 as if they were a single evaporator.

[0144] Although not shown in Figures 15 and 17, the refrigeration cycle apparatus 200 may further include a connecting pipe connecting the second connecting pipe 41d2 of one relay unit D2 to the first connecting pipe 40d1 of the other relay unit D2 so that the refrigerant flows from the relay unit D2 to the relay unit D1. Similarly, in Figures 19 and 21, the refrigeration cycle apparatus 200 may further include a connecting pipe connecting the second connecting pipe 41d2 of one relay unit D1 to the first connecting pipe 40d1 of the other relay unit D2 so that the refrigerant flows from the relay unit D1 to the relay unit D2. This allows the order of the intermediate heat exchangers 30d1 and 30d2 that cool or heat the refrigerant to be reversed in the Mollier diagrams shown in Figures 16, 18, 20, and 22. The control device 50 may control the order in which the refrigerant flows through the intermediate heat exchangers 30d1 and 30d2 in accordance with the temperatures of the external heat sources E1 and E2, for example.

[0145] 15, 17, 19, and 21, the two heat medium relay units D1 and D2 are connected using a three-way valve 70 and a connecting pipe 71, but this is not limiting. The refrigerant circuit may have a different structure as long as the refrigerant flows sequentially through the two heat medium relay units D1 and D2. For example, the three-way valve 70 may be realized by combining valves and connecting pipes of other structures. The refrigerant circuit connecting the heat medium relay units D1 and D2 may be provided inside or outside the relay unit B.

[0146] As described above, the first and second embodiments of the present disclosure have been described. However, the first and second embodiments are merely examples of the refrigeration cycle apparatuses 100 and 200, and may be combined with other known technologies. Furthermore, the configurations of the refrigeration cycle apparatuses 100 and 200 may be partially omitted or modified without departing from the spirit and scope of the present disclosure. In short, the refrigeration cycle apparatuses 100 and 200 include design modifications and application variations that are normally made by a person skilled in the art, without departing from the technical concept thereof.

[0147] REFERENCE SIGNS LIST 1 Compressor, 2 First flow switching device, 3 Heat source side heat exchanger, 3m Outdoor flow control device, 3t Temperature sensor, 4 Flow control device, 4c1 (first) flow control device, 4c2 (first) flow control device, 4d1 (second) flow control device, 4d2 (second) flow control device, 5 Use side heat exchanger, 5c1 Use side heat exchanger, 5c2 Use side heat exchanger, 5d1 Heat medium heat exchanger, 5m Flow control device, 6 Low pressure side piping, 7 High pressure side piping, 8 Low pressure side solenoid valve, 8c1 Low pressure side solenoid valve, 8c2 Low pressure side solenoid valve, 8d Low pressure side solenoid valve, 8d1 Low pressure side solenoid valve, 8d2 Low pressure side solenoid valve, 9 High pressure side solenoid valve, 9c1 High pressure side solenoid valve, 9c2 High pressure side solenoid valve, 9d High pressure side solenoid valve, 9d1 High pressure side solenoid valve, 9d2 High-pressure side solenoid valve, 10 First branch section, 10a High-pressure side branch section, 10b Low-pressure side branch section, 10c Second flow path switching device, 11 Second branch section, 12 Gas-liquid separator, 13 Third flow control device, 14a First bypass piping, 14b Second bypass piping, 15 Fourth flow control device, 16 Second heat exchanger, 17 First heat exchanger, 18 Check valve, 19 Check valve, 20 Check valve, 21 Check valve, 22 First flow control device, 25 Bypass piping, 26 Second flow control device, 27 First piping, 29 Accumulator, 30 Inter-heat medium heat exchanger, 30d1 Inter-heat medium heat exchanger, 30d2 Inter-heat medium heat exchanger, 31 Pump, 32 External heat source temperature sensor, 33 External heat source temperature sensor, 34 Heat medium circulation circuit, 40 First connecting piping, 40c1 First connecting pipe, 40c2 First connecting pipe, 40d1 First connecting pipe, 40d2 First connecting pipe, 41 Second connecting pipe, 41c1 Second connecting pipe, 41c2 Second connecting pipe, 41d1 Second connecting pipe, 41d2 First connecting pipe, 50 Control device, 50a Memory, 51 Discharge pressure gauge, 52 Suction pressure gauge, 53 Medium pressure gauge, 54 Thermometer, 60a First connecting pipe, 60b Second connecting pipe, 70 Three-way valve, 71 Connecting pipe, 100 Refrigeration cycle device, 200 Refrigeration cycle device, A Heat source device, B Relay device, C Use side unit, C1 Use side unit, C2 Use side unit, C3 Use side unit, D Heat medium converter, D1 Heat medium converter, D2 Heat medium converter, E External heat source, E1 External heat source, E2 External heat source, T Temperature, t1 Temperature, t2 temperature.

Claims

1. a heat source unit including a compressor that compresses a refrigerant, a heat source side heat exchanger, and a first flow path switching device that switches a flow path of the refrigerant; a high-pressure side pipe through which the refrigerant flowing out from the heat source device flows; a low-pressure side pipe through which the refrigerant flows into the heat source device; a utilization side unit connected to the high-pressure side pipe and the low-pressure side pipe, the utilization side unit including a utilization side heat exchanger and a first flow control device for controlling a flow rate of the refrigerant flowing through the utilization side heat exchanger; a heat medium converter connected to the high-pressure side pipe and the low-pressure side pipe, the heat medium converter including an intermediate heat exchanger for exchanging heat between the refrigerant and a heat medium carrying heat from an external heat source, and a second flow rate control device for controlling a flow rate of the refrigerant flowing through the intermediate heat exchanger; a first branching section that branches the high-pressure side pipe and the low-pressure side pipe to the user side unit and the heat medium relay unit, respectively, and that is connected to a first connecting pipe extending from the user side unit and the heat medium relay unit, respectively; a second branch portion connected to second connection pipes extending from the user side unit and the heat medium relay unit, The first flow path switching device is When the heat source side heat exchanger functions as a condenser, the refrigerant is connected so as to flow from the discharge side of the compressor to the high-pressure side pipe via the heat source side heat exchanger, and the refrigerant is connected so as to flow from the low-pressure side pipe to the suction side of the compressor, When the heat source side heat exchanger functions as an evaporator, the refrigerant is connected to the high-pressure side pipe from the discharge side of the compressor, and the refrigerant is connected to the suction side of the compressor from the low-pressure side pipe via the heat source side heat exchanger, The first branch portion is a second flow path switching device that switches the connection between the first connection pipe and the high-pressure side pipe or the low-pressure side pipe; The second flow path switching device is the intermediate heat exchanger is configured to function as an auxiliary condenser when the heat source side heat exchanger functions as a condenser, and the intermediate heat exchanger is configured to function as an auxiliary evaporator when the heat source side heat exchanger functions as an evaporator, The heat transfer medium converter comprises: a heat medium circulation circuit connected between the intermediate heat exchanger and the external heat source so that the heat medium circulates between them; a pump that circulates the heat medium, the heat source device includes a heat source-side temperature sensor that detects a temperature of the heat source heat medium that exchanges heat with the refrigerant in the heat source-side heat exchanger, the heat transfer device includes an external heat source temperature sensor for detecting a temperature of the external heat source; The heat exchanger further includes a control device that varies the heat exchange capacity of the heat source side heat exchanger and the intermediate heat exchanger, the control device compares the temperatures detected by the heat source-side temperature sensor and the external heat source temperature sensor, and varies the capacities of the heat source-side heat exchanger and the heat medium-to-heat medium heat exchanger based on the magnitude relationship of the temperatures.

2. The second flow path switching device is When the utilization side heat exchanger functions as a condenser, the first connection pipe is connected to the high-pressure side pipe, When the utilization side heat exchanger functions as an evaporator, the first connection pipe is connected to the low pressure side pipe, When the heat source side heat exchanger functions as a condenser, the first connection pipe and the high-pressure side pipe of the heat medium relay machine are connected to each other, The refrigeration cycle apparatus according to claim 1 , wherein when the heat source side heat exchanger functions as an evaporator, the first connection pipe of the heat medium relay machine is connected to the low-pressure side pipe.

3. The user unit comprises: The refrigeration cycle device according to claim 1 or 2, comprising: a first unit in which the utilization side heat exchanger functions as an evaporator; and a second unit in which the utilization side heat exchanger functions as a condenser.

4. The control device When the heat source side heat exchanger functions as a condenser and the temperature t of the external heat source temperature sensor is compared with the temperature T of the heat source side temperature sensor, if T<t, The refrigeration cycle apparatus according to claim 1 , wherein the second flow path switching device is controlled so that the refrigerant is not supplied to the heat medium relay unit.

5. The control device When the heat source side heat exchanger functions as a condenser and the temperature t of the external heat source temperature sensor is compared with the temperature T of the heat source side temperature sensor, if t<T, The refrigeration cycle apparatus according to claim 1 , wherein the second flow path switching device is controlled so that the high-pressure side pipe and the first connection pipe of the heat medium relay machine are connected to each other.

6. The control device When the heat source side heat exchanger functions as an evaporator and the temperature t of the external heat source temperature sensor is compared with the temperature T of the heat source side temperature sensor, if t<T, The refrigeration cycle apparatus according to claim 1 , wherein the second flow path switching device is controlled so that the refrigerant is not supplied to the heat medium relay unit.

7. The control device When the heat source side heat exchanger functions as an evaporator and the temperature t of the external heat source temperature sensor is compared with the temperature T of the heat source side temperature sensor, if T<t, The refrigeration cycle apparatus according to claim 1 , wherein the second flow path switching device is controlled so that the low-pressure side pipe and the first connection pipe of the heat medium relay machine are connected to each other.

8. The heat transfer medium converter comprises: a first relay unit and a second relay unit connected to the external heat sources having different temperatures, 8. The refrigeration cycle apparatus according to claim 1, further comprising a connection pipe configured to send the refrigerant from the second connection pipe of the first heat medium relay machine to the first connection pipe of the second heat medium relay machine.

9. The heat transfer medium converter comprises: a first relay unit and a second relay unit connected to the external heat sources having different temperatures, The first heat medium relay unit is a first external heat source temperature sensor for detecting a temperature of the external heat source; The second heat transfer medium relay unit is The refrigeration cycle apparatus according to claim 1 , further comprising a second external heat source temperature sensor that detects the temperature of the external heat source.

10. The control device When the heat source side heat exchanger functions as a condenser, and when the temperature t1 of the first external heat source temperature sensor, the temperature t2 of the second external heat source temperature sensor, and the temperature T of the heat source side temperature sensor are compared, if t1<T<t2, 10. The refrigeration cycle apparatus according to claim 9, wherein the second flow path switching device is controlled so as not to supply the refrigerant to the second heat medium relay unit and so as to connect the high-pressure side pipe and the first connection pipe of the first heat medium relay unit.

11. The control device When the heat source side heat exchanger functions as an evaporator, and when the temperature t1 of the first external heat source temperature sensor, the temperature t2 of the second external heat source temperature sensor, and the temperature T of the heat source side temperature sensor are compared, if t1<T<t2, 10. The refrigeration cycle apparatus according to claim 9, wherein the second flow path switching device is controlled so as not to supply the refrigerant to the first heat medium relay unit and so as to connect the low-pressure side pipe and the first connection pipe of the second heat medium relay unit.

12. The control device When the heat source side heat exchanger functions as a condenser, and when the temperature t1 of the first external heat source temperature sensor, the temperature t2 of the second external heat source temperature sensor, and the temperature T of the heat source side temperature sensor are compared, in the case where t1<t2<T, controlling the second flow switching device so that the high-pressure side pipe is connected to the first connecting pipes of the first relay unit and the second relay unit; The refrigeration cycle apparatus according to claim 9, wherein a flow rate of the pump of the first heat medium relay unit is controlled to be greater than that of the second heat medium relay unit.

13. The control device When the heat source side heat exchanger functions as an evaporator, and when the temperature t1 of the first external heat source temperature sensor, the temperature t2 of the second external heat source temperature sensor, and the temperature T of the heat source side temperature sensor are compared, in the case of T<t1<t2, controlling the second flow switching device so that the low-pressure side pipe is connected to the first connecting pipes of the first relay unit and the second relay unit; The refrigeration cycle apparatus according to claim 9, wherein a flow rate of the pump of the first heat medium relay unit is controlled to be greater than that of the second heat medium relay unit.

14. The second branch portion is The refrigerant is configured to be able to flow through each of the high-pressure side piping and the low-pressure side piping via a flow control device and an internal heat exchanger. The refrigeration cycle device according to any one of claims 1, 2, 4 to 7, or 9 to 13.