WO2024252471A1 - Refrigeration cycle device - Google Patents

Abstract

This refrigeration cycle device is provided with: a heat source machine having a compressor, a heat-source-side heat exchanger, and a first flow path switching device; a high-pressure-side pipe through which a refrigerant flows out from the heat source machine; a low-pressure-side pipe through which the refrigerant flows into and out from the heat source machine; a use-side unit; a heat medium relay unit; a first branch part; a second branch part; and an external heat source circuit that circulates the refrigerant between the heat source machine and the heat medium relay unit without passing the refrigerant through the first branch part and the second branch part. The first branch part is provided with a second flow path switching device that switches connection between a first connection pipe and the high-pressure-side pipe or the low-pressure-side pipe. The first flow path switching device is configured to form, when the heat-source-side heat exchanger functions as a condenser, such connection that the refrigerant flows from a discharge side of the compressor to the high-pressure-side pipe through the heat-source-side heat exchanger and such connection that the refrigerant flows from the low-pressure-side pipe to a suction side of the compressor and to form, when the heat-source-side heat exchanger functions as an evaporator, such connection that the refrigerant flows from the 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 the suction side of the compressor through the heat-source-side heat exchanger. The external heat source circuit is configured to be able to cause the refrigerant to flow between the discharge side or the suction side of the compressor and the heat-source-side heat exchanger via an inter-heat-medium heat exchanger.

Description

Refrigeration Cycle Equipment

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

It has been known that in air conditioning and hot water combined systems that can simultaneously supply cooling loads, heating loads, and hot water loads, including air conditioning and hot water combined systems, the system COP can be improved by balancing the cooling load, heating load, and hot water load (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 by a high-pressure side connection pipe and a low-pressure side connection pipe, and a user side unit including an indoor unit and a hot water heat source circuit. The relay unit has a first distribution section and a second distribution section that are configured so that two connection pipes extending from each user side unit can be selectively connected to the high-pressure side connection pipe or the low-pressure side connection pipe. In Patent Document 1, the first distribution section switches the connection between one connection pipe of each user side unit and the high-pressure side connection pipe or the low-pressure side connection pipe, so that each user side unit can 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 load of multiple user units, improving the efficiency of the entire system.

Furthermore, air conditioning systems that use melted snow water or well water are known from the past (see, for example, Patent Document 2). The snow and ice air conditioning system disclosed in Patent Document 2 comprises an indirect outdoor air cooling machine, a compression refrigeration cooling machine, and a snow and ice air conditioning machine. The snow and ice air conditioning machine uses the cold energy of the snowy mountains 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 cooling machine and the compression refrigeration cooling machine. The snow and ice air conditioning system of Patent Document 2 makes effective use of the cold energy of the snowy mountains, enabling energy-saving operation.

Patent No. 5642085 JP 2018-146221 A

The refrigeration cycle device disclosed in Patent Document 1 can improve the COP by balancing the cooling load, heating load, and hot water load of the user unit, but the heating and cooling capacity required for the load in the corresponding usage situation of the user unit is borne by the heat source unit. Therefore, no further energy saving effect beyond the improvement of the COP of the refrigeration cycle device can be expected.

The snow and ice air conditioning system disclosed in Patent Document 2 can use the cold energy of snowy mountains to reduce the load on the indirect outdoor air cooler and the compression refrigeration cooler, but the refrigerant circuits of the indirect outdoor air cooler, the compression refrigeration cooler, and the snow and ice cooler are 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 load on the two coolers.

This disclosure has been made to solve the problems described above, 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.

The refrigeration cycle device disclosed herein includes a heat source unit having a compressor for compressing a refrigerant, a heat source side heat exchanger, and a first flow path switching device for switching the flow path of the refrigerant, a high-pressure side pipe through which the refrigerant flows out from the heat source unit, a low-pressure side pipe through which the refrigerant flows in and out of the heat source unit, 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 for controlling the flow rate of the refrigerant flowing into the utilization side heat exchanger, a heat medium converter having an inter-heat medium 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 the flow rate of the refrigerant flowing into the inter-heat medium heat exchanger, a first branching section that branches off each of the high-pressure side pipe and the low-pressure side pipe to the utilization side unit, a first branching section that is connected to a first connecting pipe extending from the utilization side unit, a second branching section that is connected to a second connecting pipe extending from the first flow control device, and a heat medium converter that converts the heat from the refrigerant into the heat medium without passing through the first branching section and the second branching section. and an external heat source circuit that circulates the refrigerant between the heat source unit and the heat medium converter. The first branching section includes 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. When the heat source side heat exchanger functions as a condenser, the first flow path switching device connects the refrigerant so that it flows from the discharge side of the compressor through the heat source side heat exchanger to the high-pressure side pipe and 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 first flow path switching device connects 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. The external heat source circuit is configured to allow the refrigerant to flow between the discharge side or suction side of the compressor and the heat source side heat exchanger through the heat medium heat exchanger.

According to the present disclosure, the refrigeration cycle device is configured so that the heat medium converter using an external heat source can be connected to the heat source device via a relay device, and the heat source device and the heat medium converter can be directly connected by an external heat source circuit. Therefore, the refrigeration cycle device can connect the heat medium converter in series to the upstream or downstream side of the heat source side heat exchanger. This allows the refrigeration cycle device to simultaneously perform simultaneous heating and cooling operations and hot water supply operations, and the heat medium converter can function to supplement or replace the capacity of the heat source side heat exchanger. Furthermore, the heat medium converter can be appropriately used depending on the temperature of the external heat source, and the heat medium converter can be used more efficiently as an auxiliary heat source. Since the heat medium converter can supplement part or all of the capacity of the heat source side heat exchanger with the external heat source, the refrigeration cycle device can operate more energy-efficiently than before.

1 is a schematic diagram of a configuration of a refrigeration cycle device 100 according to a first embodiment. 1 is an example of a circuit diagram showing a refrigeration cycle device 100 according to a first embodiment. 3 is an explanatory diagram of a flow of a refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is performing a cooling operation. FIG. FIG. 2 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during cooling operation. 3 is an explanatory diagram of a flow of a refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is performing a cooling operation. FIG. FIG. 2 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during cooling operation. 3 is an explanatory diagram of a flow of a refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is performing a heating operation. FIG. FIG. 4 is a Mollier diagram during heating operation of the refrigeration cycle apparatus 100 according to the first embodiment. 3 is an explanatory diagram of a flow of a refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is performing a heating operation. FIG. FIG. 4 is a Mollier diagram during heating operation of the refrigeration cycle apparatus 100 according to the first embodiment. 3 is an explanatory diagram of a flow of a refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is performing a defrost operation. FIG. FIG. 4 is a Mollier diagram during a defrost operation of the refrigeration cycle apparatus 100 according to the first embodiment. 3 is an explanatory diagram of a flow of a refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is performing a defrost operation. FIG. FIG. 4 is a Mollier diagram during a defrost operation of the refrigeration cycle apparatus 100 according to the first embodiment. 11 is an example of a circuit diagram showing a refrigeration cycle device 200 according to a second embodiment. FIG.

Embodiment 1.
Hereinafter, an embodiment of an air conditioner according to the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a 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 by a low-pressure side pipe 6 and a high-pressure side pipe 7, and a user side unit C connected to the relay unit B by a first connection pipe 40 and a second connection pipe 41. The user side unit C can select a cooling operation, a heating operation, or a hot water supply operation by using a refrigeration cycle. When the refrigeration cycle apparatus 100 includes a plurality of user side units C, each of the plurality of user side units C can freely select one operation mode from the cooling operation, the heating operation, and the hot water supply operation, and can operate. In other words, the refrigeration cycle apparatus 100 can perform a mixed cooling and heating operation in which a cooling operation and a heating operation are performed simultaneously, and further a mixed operation such as a water boiling operation.

The heat source unit A and the relay unit B are connected by low-pressure side piping 6 and high-pressure side piping 7, and the refrigerant compressed by the compressor 1 (see Figure 2) of the heat source unit A is sent to the relay unit B, which 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 piping 40 and the second connection piping 41 are connected to the low-pressure side piping 6 or the high-pressure side piping 7. Figure 1 shows, as an example, a case where the topmost user-side unit C1 is in heating operation, the second-highest user-side unit C2 is in cooling operation, and the third-highest user-side unit C3 is in water-boiling operation.

The user side unit C is, for example, an indoor air conditioner or water heater, and is supplied with refrigerant from the repeater B to perform indoor air conditioning or water heating through a refrigeration cycle. Each user side unit C is connected in series to the repeater B and in parallel with each other. In FIG. 1, three user side units C are connected to the repeater B, but this number is not limited, and two or more user side units C may be installed, or there may be only one. In addition, the user side unit C can be an indoor unit of an air conditioner, a water heater, a refrigerator, etc., and there is no limit to the equipment that can be connected.

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 boiling operation. The operation of each user side unit C is switched by the second flow path switching device 10c (see FIG. 2) provided in the relay unit B.

The heat medium converter D is further 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. The heat medium converter D is also configured to allow the refrigerant to flow in from the relay unit B, like the user unit C. The heat medium converter D is further connected to an external heat source E. The external heat source E and the heat medium converter D are connected by a circuit in which a heat medium different from the refrigerant flowing in 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 has flowed into the heat medium converter D from the heat source unit A via the relay unit B, and to function as a condenser or evaporator by transferring heat or cold from the external heat source E to the refrigerant. The heat medium converter D may be configured to circulate a liquid such as well water from the external heat source E in the heat medium circulation circuit 34 (see FIG. 2), or may be configured to circulate an independent heat medium in the heat medium circulation circuit 34.

In the first embodiment, the heat medium converter 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 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, and energy savings can be achieved for the refrigeration cycle device 100 as a whole.

Furthermore, the refrigeration cycle device 100 can also perform defrost operation of the heat source side heat exchanger 3 by utilizing the heat medium heat exchanger 30. This will be described later.

The external heat source E connected to the heat medium converter D has 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 of 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 the 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. Other examples of the external heat source E include ice and snow, melted snow, etc. The external heat source E can also be unused heat such as heat from river water, exhaust gas from equipment, wastewater, and waste heat generated by equipment. The heat medium, such as water, circulating through the heat medium circulation circuit 34 is heat exchanged with the refrigerant circulating through the heat source unit A, etc., in the heat medium heat exchanger 30 (see FIG. 2).

The heat medium converter D also includes an external heat source circuit 90 that is directly connected to the heat source A by piping without passing through the relay B. This allows the heat source A to use the heat or cold of the external heat source E by using the heat medium converter D. The refrigeration cycle device 100 is capable of directly connecting the compressor 1 and the intermediate heat exchanger 30 to cause the refrigerant to flow. The intermediate heat exchanger 30 can be used as a heat exchanger that supplements or replaces the heat source side heat exchanger 3 that is used as a condenser or evaporator.

In FIG. 1, one heat transfer medium converter D and one external heat source E are installed, but multiple units may be installed. In addition, the external heat source E may use multiple types of heat sources.

Whether the heat medium converter D is used as an evaporator or a condenser is determined based 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 that circulates through the heat source unit A, relay unit B, user unit C, and heat medium converter D. When the temperature of the external heat source E is higher than the evaporation temperature of the refrigerant, the heat medium converter 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 converter 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 converter D should be used as an evaporator, and when a relatively low-temperature external heat source E such as well water, snow and ice, or melted snow is used, the heat medium converter D should be used as a condenser.

The heat medium converter D can switch between using the first connection 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. Switching of operation using the heat medium converter D is performed by the first flow path switching device 2a and the third flow path switching device 2b provided in the heat source unit A and the second flow path switching device 10c provided in the relay unit B (see Figure 2). The first flow path switching devices 2a and 2b provided in the heat source unit A may be collectively referred to as the heat source side flow path switching device 2.

(Circuit configuration of refrigeration cycle device 100)
FIG. 2 is an example of a circuit diagram showing the refrigeration cycle apparatus 100 according to the first embodiment. 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 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 converter D flows in, and is a pipe for returning the refrigerant from the relay unit B to the heat source unit A. In the refrigeration cycle apparatus 100 shown in FIGS. 1 and 2, the relay unit B is provided between the heat source unit A and the user side unit C and the heat medium converter D, but the relay unit B does not need to be provided independently as long as each part constituting the refrigerant circuit, such as the first branch unit 10, of the relay unit B is provided. For example, the first branching section 10, the second branching section 11, the gas-liquid separation device 12, the third flow control device 13, the fourth flow control device 14, the first heat exchanger 17 and the second heat exchanger 16 provided in the relay unit B may each exist independently or may be present within the heat source unit A or other unit.

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. The refrigerant in the high-pressure side branch 10a flows into the user unit C or the heat medium converter D by opening the high-pressure side solenoid valves 9c1, 9c2, and 9d1 provided in the first branch 10. The high-pressure side solenoid valves 9c1, 9c2, and 9d1 may be collectively referred to as the high-pressure side solenoid valves 9.

The low-pressure side pipe 6 is connected to the low-pressure side branch portion 10b of the first branch portion 10 of the relay unit B.
The low-pressure side branch portion 10b receives the refrigerant from the utilization side unit C or the heat medium relay unit D by opening the low-pressure side solenoid valves 8c1, 8c2, and 8d1. The low-pressure side solenoid valves 8c1, 8c2, and 8d1 may be collectively referred to as the low-pressure side solenoid valves 8.

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

The other pipes extending from the user unit C and the heat medium converter D are called second connection pipes 41c1, 41c2, and 41d1. The second connection pipes 41c1, 41c2, and 41d1 are connected to the second branch 11 of the relay unit. The second connection pipes 41c1, 41c2, and 41d1 may be collectively called second connection pipes 41.

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, the refrigerant flows from the second branch section 11 to the user side unit C and the heat medium converter D, respectively, or flows from the user side unit C and the heat medium converter D to the second branch section 11.

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 converter D, and the refrigerant that has passed through the user side unit C or the heat medium converter D flows into the second branch 11.

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 unit C, another heat medium converter 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 unit C or the heat medium converter D. The refrigerant that has passed through the user unit C or the heat medium converter 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.

As described above, the relay unit B switches the connection state of the utilization side unit C or the heat medium converter D by switching the opening and closing of the low pressure side solenoid valve 8 and the high pressure side solenoid valve 9 of the first branch section 10. This switching allows the utilization side heat exchanger 5 of the utilization side unit C and the heat medium converter 30 of the heat medium converter D to switch between functioning as an evaporator or a condenser, respectively.

The first branching section 10 branches the high-pressure side pipe 7 and the low-pressure side pipe 6 for each of the user side units C and the heat medium converters D, and connects them to the first connection pipe 40, which is one of the pipes extending from each of the user side units C and the heat medium converters D. The first branching section 10 controls whether the first connection pipe 40 of the user side units C and the heat medium converters D is connected to the high-pressure side pipe 7 or the low-pressure side pipe 6 by controlling the high-pressure side solenoid valve 9 and the low-pressure side solenoid valve 8 to close one and open the other. The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 of the first branching section 10 may be collectively referred to as the second flow path switching device 10c. The second flow path switching device 10c includes the high-pressure side solenoid valve 9 and the low-pressure side solenoid valve 8 provided for each of the user side units C and the heat medium converters D, but is not limited to this form and may be configured as a three-way valve to which the high-pressure side pipe 7, the low-pressure side pipe, and the first connection pipe 40 are connected, for example.

(Heat source machine A)
The heat source unit A is usually placed in a space such as a rooftop outside a building, and supplies cold or hot heat to the user 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 the 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.

The heat source unit A incorporates a compressor 1, a first flow path switching device 2a 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 path switching device 2a, 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.

The heat source side heat exchanger 3 is connected in series with the first flow control device 22. In addition, in the heat source unit A, a bypass pipe 25 having a second flow control device 26 is connected in parallel with the heat source side heat exchanger 3. The second flow control device 26 can adjust the flow rate to adjust the amount of refrigerant that bypasses the heat source side heat exchanger 3. In FIG. 3, the bypass pipe 25 is directly connected to the discharge side of the compressor 1, but it may also be connected between the first flow path switching device 2a and the third flow path switching device 2b.

Also, 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, and heat exchange with the refrigerant is performed. The outdoor flow control device 3m is, for example, a fan that sends 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. Note that the heat source side heat exchanger 3 may be a water-cooled outdoor heat exchanger or the like as long as the refrigerant exchanges heat with 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. Note that, although the first embodiment illustrates a case in which there is one heat source side heat exchanger 3, multiple heat source side heat exchangers 3 may be provided.

The heat source unit A is also provided with a first connection pipe 60a, a second connection pipe 60b, a check valve 18, a check valve 19, a check valve 20, and a check valve 21. Regardless of the connection direction of the first flow path switching device 2a, the first connection pipe 60a, the second connection 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 from the heat source unit A to the relay unit B via the high-pressure side pipe 7. The first connection pipe 60a, the second connection pipe 60b, the check valve 18, the check valve 19, the check valve 20, and the check valve 21 allow low-pressure refrigerant from the relay unit B to flow into the heat source unit A via the low-pressure side pipe 6.

Compressor 1 draws in the refrigerant and compresses it to a high-temperature, high-pressure state, and is composed of, for example, an inverter compressor with a capacity controllable.

The first flow path switching device 2a switches between the flow of refrigerant during heating operation and the flow of refrigerant during cooling operation. The first flow path switching device 2a 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 the 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. In FIG. 2, the third flow path switching device 2b is connected between the first flow path switching device 2a and the first pipe 27 leading to the heat source side heat exchanger 3. The third flow path switching device 2b is for directly connecting the heat source unit A and the heat medium converter D via the external heat source circuit 90. The third flow path switching device 2b can switch between connecting and disconnecting the heat source unit A and the heat medium converter D. The third flow path switching device 2b and the external heat source circuit 90 will be described later.

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

In the first embodiment, the heat source side heat exchanger 3 exchanges heat between the refrigerant and the outdoor air, evaporating and gasifying the refrigerant or condensing and liquefying the refrigerant. The outdoor flow control device 3m forms an air passage 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. Note that, although the first embodiment illustrates a case in which one heat source side heat exchanger 3 is provided, multiple heat source side heat exchangers 3 may be connected in parallel.

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 the 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 switching device 2a, and allows the 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 connection pipe 60a, and allows the refrigerant discharged from the compressor 1 to flow to the relay unit B during heating operation. The check valve 21 is provided in the second connection pipe 60b, and allows the refrigerant returning from the relay unit B to flow to the suction side of the compressor 1 via the heat source side heat exchanger 3 or the bypass pipe 25 during heating operation.

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

The heat source unit A may also be provided with a discharge pressure gauge 51, a suction pressure gauge 52, a medium 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 medium pressure pressure gauge 53 is provided upstream of the check valve 18 and measures the medium 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. The pressure information and temperature information detected by the discharge pressure gauge 51, the suction pressure gauge 52, the medium pressure pressure gauge 53, and the thermometer 54 are sent to the control device 50 that controls the operation of the refrigeration cycle device 100, and are used to control each actuator.

The first flow 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 freely opened and closed. The first flow 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 to the heat source side heat exchanger 3 during heating operation. The first flow control device 22 is configured so that the flow path resistance changes continuously.

The bypass pipe 25 bypasses the heat source side heat exchanger 3. The second flow control device 26 is provided midway through the bypass pipe 25 and is configured to be freely opened and closed, 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.

(Repeater B)
The relay unit B incorporates a first branching section 10, a second branching 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.

The first branching section 10 branches the refrigerant flowing in the high-pressure side pipe 7 to the user side unit C and the heat medium converter D. The first branching section 10 also merges the refrigerant flowing in the user side unit C and the heat medium converter D and allows it to flow into the low-pressure side pipe 6. The first branching section 10 includes a low-pressure side solenoid valve 8 and a high-pressure side solenoid valve 9 installed in the first connection pipe 40 of the user side unit C and the heat medium converter D. In other words, the first connection pipe 40 of the user side unit C and the heat medium converter D is branched at the first branching section 10, one of which is connected to the low-pressure side pipe 6 via the low-pressure side solenoid valve 8, and the other of which is connected to the high-pressure side pipe 7 via the high-pressure side solenoid valve 9.

The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 are controlled to open and close, so that the first connection pipe 40 of the user side unit C and the heat medium converter D can be switched 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 provided in the relay unit B are collectively referred to as the second flow path switching device 10c. The low-pressure side solenoid valve 8 and the high-pressure side solenoid valve 9 are installed in each pipe where the first connection pipe 40 is branched into two, but they may be configured using, for example, a three-way valve. In other words, other structures may be used as long as the first connection pipe 40 of the user side unit C and the heat medium converter 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 so that the refrigerant does not flow to any of the user side units C and the heat medium converters D.

The second branch section 11 branches the refrigerant flowing in the first bypass pipe 14a to the user unit C and the heat medium converter D. The second branch section 11 also merges the refrigerant flowing in the user unit C and the heat medium converter D and causes it to flow into the second bypass pipe 14b. The second branch section 11 has a junction between the first bypass pipe 14a and the second bypass pipe 14b.

The gas-liquid separator 12 is provided midway through the high-pressure side pipe 7 and separates the refrigerant that flows in through 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.

The first bypass pipe 14a is a pipe that connects the gas-liquid separation device 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 through the first bypass pipe 14a and is configured to be freely opened and closed. The fourth flow control device 15 is provided midway through the second bypass pipe 14b and is configured to be freely opened and closed.

The first heat exchanger 17 exchanges heat between the refrigerant between the gas-liquid separation device 12 and the third flow control device 13 of the first bypass pipe 14a and the refrigerant between the fourth flow control device 15 and the low-pressure side pipe 6 of the second bypass pipe 14b. The second heat exchanger 16 exchanges heat between the refrigerant between the third flow control device 13 and the second branch section 11 of the first bypass pipe 14a and the refrigerant between the fourth flow control device 15 and the first heat exchanger 17 of the second bypass pipe 14b.

(User unit C)
The user side units C are installed at positions where they can supply conditioned air to a space to be air-conditioned, such as a room, and supply cooled air or heated air to the space to be air-conditioned by 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, 5c2 and a first flow control device 4c1, 4c2.

Furthermore, near the user-side heat exchangers 5c1, 5c2, a flow control device 5m is installed to control the flow rate of indoor air, which is a fluid that exchanges heat with the refrigerant. Note that in the first embodiment, an air-cooled user-side heat exchanger is 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, but a water-cooled user-side heat exchanger or the like 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 that moves water is used as the flow control device 5m.

Each of the utilization 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 space to be air-conditioned. The flow control device 5m forms an air path for the air flowing through the utilization 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 utilization side heat exchanger 5c1 or 5c2, and are configured to be freely opened and closed. The first flow control device 4c1 and the first flow control device 4c2 adjust the flow rate of the refrigerant flowing into the utilization side heat exchangers 5c1 and 5c2.

(Heat medium converter D)
The heat medium relay unit D is for supplying heat or cold from an external heat source E to a refrigerant circulating in the refrigeration cycle apparatus 100. The heat medium relay unit D has an intermediate heat exchanger 30 that exchanges heat between the refrigerant circulating in the heat source unit A, the relay unit B, and the user side unit C and a heat medium that carries heat from the external heat source E. The heat medium relay unit D also has a built-in second flow control device 4d1 that controls the flow rate of the refrigerant circulating in the intermediate heat exchanger 30. The second flow control device 4d1 is provided between the second branch section 11 of the relay unit B and the intermediate heat exchanger 30d1, and is configured to be freely opened and closed. The second flow control device 4d1 adjusts the flow rate of the refrigerant flowing into the intermediate heat exchanger 30d1.

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 heat medium-intermediate heat exchanger 30. The heat medium-intermediate heat exchanger 30 is, for example, a plate-type heat exchanger, inside which the refrigerant and heat medium circulate, and the heat or cold of the heat medium is transferred to the refrigerant.

The heat medium converter D is equipped with 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 heat medium-to-heat medium heat exchanger 30. The external heat source temperature sensor 33 detects the temperature of the heat medium flowing out of the heat medium-to-heat medium heat exchanger 30.

(External heat source E)
The external heat source E is, for example, well water, melted snow, ice and snow, geothermal heat, solar light, etc., and the heat medium can be appropriately changed depending on the target heat source. For example, when the external heat source E is well water stored in a large amount in a well underground, the well water is pumped up by a pump 31 to become a heat medium, and is caused to flow into the heat medium heat exchanger 30 by a heat medium circulation circuit 34. The well water exchanges heat with the refrigerant, flows out of the heat medium heat exchanger 30, and its temperature increases. The well water with the increased temperature is returned to the well. The well water serving as the external heat source E is stored in a large amount underground, and even if the water with an increased temperature is returned through the heat medium converter D, the temperature of the external heat source E hardly changes.

The heat medium circulation circuit 34 may be configured to circulate an independent heat medium in the heat medium circulation circuit 34. As shown in FIG. 2, the heat medium circulation circuit 34 may be connected to an external heat exchanger F that exchanges heat between the 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 been heat exchanged in the external heat exchanger F is sent to the heat medium-to-heat medium heat exchanger 30 and is heat exchanged with the refrigerant circulating through the refrigerant circuit of the refrigeration cycle device 100. By configuring in this way, the quality of the heat medium flowing through the heat medium circulation circuit 34 can be maintained, and the durability of the heat medium circulation circuit 34 and the heat medium converter D can be ensured, as opposed to pumping up well water as the heat medium, for example. The configuration of the heat medium circulation circuit 34 may be changed as appropriate depending on what is used as the external heat source E.

When geothermal energy is used as the external heat source E, piping through which a heat medium such as water circulates is extended into the ground, and the geothermal energy is transferred 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, and the heat from the sunlight is transferred to the heat medium. The refrigeration cycle device 100 according to the first embodiment makes effective use of such an external heat source E to achieve energy savings.

(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 2a 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.

The control device 50 controls the opening 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 in which information for determining each control value is stored. The control device 50 may be configured with hardware such as a control circuit that realizes its functions. The control device 50 may 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 a CPU (central processing unit) that executes the software program. In the first embodiment, the control device 50 is provided in the heat source unit A and the relay unit B, but the number of control devices 50 may be one or three or more. The control device 50 may be provided in the user unit C or the heat medium converter D, or may be provided 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 converter D.

(External heat source circuit 90)
As shown in FIG. 1 and FIG. 2, the heat source unit A and the heat medium relay unit D are configured such that the refrigerant flowing out from the heat source unit A is sent directly to the heat medium relay unit D via the external heat source circuit 90, and the refrigerant is transferred to the external The refrigerant is configured to exchange heat between the heat medium having the heat or cold of the heat source E1 and the refrigerant. The refrigerant that has exchanged heat with the external heat source E1 returns to the heat source unit A and is then cooled as described above. The refrigerant is either used in the utilization unit C or sucked into the compressor 1 and compressed and heated again.

The heat source unit A has a third flow path switching device 2b connected between the first flow path switching device 2a and the first pipe 27 connected to the heat source side heat exchanger 3. The third flow path switching device 2b switches between two connection states. In one connection state, the first pipe 27 connected to the heat source side heat exchanger 3 is connected to the first flow path switching device 2a. In the other connection state, the first flow path switching device 2a is connected to the heat source side heat exchanger 3. By switching between these connection states, the third flow path switching device 2b circulates the refrigerant between the heat source unit A and the heat medium converter D or blocks the refrigerant.

When refrigerant is circulated between the heat source unit A and the heat medium converter D via the external heat source circuit 90, the second flow path switching device 10c of the relay unit B cuts off the connection between the first branching section 10 and the heat medium converter D. In other words, at this time, refrigerant is not circulated between the relay unit B and the heat medium converter D.

One pipe 91 of the external heat source circuit 90 connects the third flow path switching device 2b and the second connection pipe 41d1. The other pipe 92 of the external heat source circuit 90 connects the first connection pipe 40d1 and the third flow path switching device 2b. An on-off valve 93 is installed in one pipe 91. The on-off valve 93 closes when refrigerant is not flowing through the external heat source circuit 90, preventing the refrigerant that has flowed into the heat medium converter D via the relay B from flowing into the external heat source circuit 90. There are no limitations on where the on-off valve 93 is installed, so long as it prevents refrigerant from flowing through the external heat source circuit 90.

(Operation Mode of Refrigeration Cycle Apparatus 100)
Next, the operation during various operations performed by the refrigeration cycle apparatus 100 will be described. The operation of the refrigeration cycle apparatus 100 includes cooling operation, heating operation, and defrost operation. The cooling operation includes cooling-dominated operation in which heating operation is performed in some of the user-side units C. The heating operation includes heating-dominated operation in which cooling operation is performed in some of the user-side units C. The defrost operation includes an operation in which the user-side units C are stopped and the heat source-side heat exchanger 3 is defrosted, and an operation in which the user-side units C are operated and the defrost operation is performed.

Cooling operation is an operation mode in which all user side units C are either in cooling operation or stopped. Heating operation is an operation mode in which all user side units C are either in heating operation or stopped. Cooling-dominated operation is an operation mode in which heating or cooling 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.

Table 1 shows the operation of the refrigeration cycle device 100 according to the first embodiment in each operation mode. The control device 50 operates the first flow path switching device 2a, the second flow path switching device 10c, and the third flow path switching device 2b to determine how the refrigerant flows into the heat medium converter D. The heat medium-intermediate heat exchanger 30 of the heat medium converter D basically functions to assist the heat source side heat exchanger 3, so it functions as an evaporator when the heat source side heat exchanger 3 is an evaporator, and as a condenser when the heat source side heat exchanger 3 is a condenser. However, depending on the relationship between the outside air temperature T, the external heat source temperature t, and the freezing threshold temperature f of the heat medium-intermediate heat exchanger 30, which of the heat medium-intermediate heat exchanger 30 and the heat source side heat exchanger 30 that exchanges heat with the heat source side heat exchanger 3, the first flow of the refrigerant is changed.

(Operation condition No. 1: Cooling operation)
FIG. 3 is an explanatory diagram of the flow of the refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is operating in cooling mode. FIG. 3 shows the state of the refrigeration cycle apparatus 100 under the operating condition No. 1 in Table 1. The operating condition No. 1 is a case where the outside air temperature T is higher than the external heat source temperature t. The refrigerant discharged from the compressor 1 is condensed in the heat source side heat exchanger 3, and then condensed in the heat medium heat exchanger 30. This allows the refrigerant to be condensed to a temperature equivalent to the lower temperature of the external heat source E1, ensuring an enthalpy difference between the refrigerant before and after passing through the condenser, and thus improving the cooling capacity. The outside air temperature T is the temperature of the air flowing into the heat source side heat exchanger 3, and is measured by the temperature sensor 3t. The external heat source temperature t is measured by the external heat source temperature sensor 33 installed on the outlet side of the heat medium heat exchanger 30d1 of the heat medium circulation circuit 34 of the heat medium converter D1. However, the external heat source temperature t may be a value measured by an external heat source temperature sensor 32 installed on the inlet side of the heat medium heat exchanger 30d1, or the temperature of the external heat source E itself may be measured and used.

In FIG. 3, the case of cooling operation in which all of the user side units C1 and C2 perform cooling will be described. When cooling operation is performed, the control device 50 switches the first flow path switching device 2a 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. In FIG. 3 and subsequent figures, the closed valves of the second flow path switching device 10c are shown in black.

When the compressor 1 starts operating, 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 heat source side heat exchanger 3 via the first flow path switching device 2a. The third flow path switching device 2b is switched to connect the first flow path switching device 2a and the heat source side heat exchanger 3, and the external heat source circuit 90 is in a blocked state. The refrigerant discharged from the compressor 1 and flowing into the heat source side heat exchanger 3 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 piping 7 and is separated into a liquid refrigerant and a gaseous refrigerant by the gas-liquid separator 12.

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, 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.

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 connection 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 connection 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 by the first flow control devices 4c1, 4c2, expands and reduces its pressure, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant. 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 gas refrigerant.

The low-temperature, low-pressure gaseous refrigerant flowing out of the user-side heat exchangers 5c1 and 5c2 passes through the low-pressure solenoid valves 8c1 and 8c2, respectively, and flows into the low-pressure branch 10b of the first branch 10. The low-temperature, low-pressure gaseous refrigerant that joins in the low-pressure 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 piping 14b, passes through the low-pressure piping 6 and the first flow switching device 2a, and flows into the compressor 1, where it is compressed.

When the heat medium converter D1 is connected to the refrigeration cycle device 100, it is determined whether to connect the heat medium converter D1 to the upstream side or downstream side of the heat source side heat exchanger 3 based on the magnitude relationship between the temperature t of the external heat source E1 and the temperature T flowing into the heat source side heat exchanger 3.

The outside air temperature T is the temperature of the outside air sent to the heat source side heat exchanger 3, and the external heat source temperature t is the temperature of the heat medium circulating in the heat medium circulation circuit 34. In particular, the temperature t1 is the temperature of the heat medium flowing into the heat medium heat exchanger 30d1 of the heat medium converter D1, and the temperature t2 is the temperature of the heat medium flowing into the heat medium heat exchanger 30d2 of the heat medium converter D2. The cooling operation shown in FIG. 3 shows a case where the temperature t of the heat medium is lower than the temperature T of the outside air flowing into the heat source side heat exchanger 3. In addition, in the first embodiment, the temperature t2 of the refrigerant flowing out from the heat medium heat exchanger 30d1 is used as the external heat source temperature t. The temperature T is measured by a temperature sensor 3t installed near the heat source side heat exchanger 3. In addition, the temperature t1 is measured by an external heat source temperature sensor 32 installed upstream of the heat medium heat exchanger 30d1 of the heat medium circulation circuit 34 of the heat medium converter D1. 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 converter D2.

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 into liquid refrigerant and gas refrigerant by the gas-liquid separator 12. The separated gas refrigerant flows into the high-pressure side branch 10a. The high-pressure side solenoid valve 9d1 connected to the heat medium converter D1 is opened, and the low-pressure side solenoid valve 8d1 is closed. The gas refrigerant in the high-pressure side branch 10a flows through the first connection pipe 40d1 into the heat medium heat exchanger 30d1.

The gas refrigerant that flows into the heat medium heat exchanger 30d1 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 and expanded by the second flow control device 4d1, reducing its pressure and becoming a low-temperature, low-pressure, gas-liquid two-phase state. The refrigerant that flows out of the second flow control device 4d1 flows into the second branch section 11, where it is mixed with the refrigerant that has flowed into the second branch section 11 from the gas-liquid separator 12 via the first bypass piping 14a, and flows into the user side units C1 and C2.

As described above, in the cooling operation of the refrigeration cycle device 100, not only the heat source side heat exchanger 3 is used as a condenser, but also the heat medium converter D1 can be used as a condenser. Therefore, in the heat source device A, the output of the outdoor flow control device 3m that blows air to the heat source side heat exchanger 3 can be reduced, or a part of the refrigerant discharged from the compressor 1 can be sent from the bypass pipe 25 to the high pressure side pipe 7. The refrigerant that does not pass through the heat source side heat exchanger 3 but passes through the bypass pipe 25 flows from the gas-liquid separator 12 into the high pressure side branch section 10a, and flows into the intermediate heat exchanger 30d1 and is condensed. In this way, the heat medium converter D1 can complement the capacity of the heat source side heat exchanger 3 by using the external heat source E1.

Also, depending on the capacity of the heat medium converter D1, it is possible to prevent the refrigerant from flowing to the heat source side heat exchanger 3 in the heat source unit A, and to have all the refrigerant flow to the high pressure side pipe 7 via the bypass pipe 25. The high pressure refrigerant is separated into liquid refrigerant and gas refrigerant in the gas-liquid separator 12. The gas refrigerant flows into the heat medium converter D1 via the high pressure side branch section 10a, exchanges heat with the heat medium, and is condensed. The refrigerant that has become a low temperature, high pressure liquid or gas-liquid two-phase refrigerant is then decompressed by the flow control devices 4d1, 4c1, 4c2, flows into the user side heat exchangers 5c1, 5c2, exchanges heat with the indoor air, etc., and expands, thereby cooling the room. In this way, the heat medium converter D1 can also function as a substitute for the heat source side heat exchanger 3 by using the external heat source E1.

In addition, in the cooling operation No. 1 shown in Table 1, since the temperature t of the heat medium circulating through the heat medium relay unit D1 is low, the control unit 50 may control the flow rate of the pump 31 of the heat medium relay unit D1 to be increased. This allows more cold heat from the external heat source E1, which is effective as a heat source that can be used for the condenser, to be utilized. The flow rate of the refrigerant flowing through the heat medium relay unit D1 may also be appropriately adjusted using the high-pressure side solenoid valve 9d1. If the heat source side heat exchanger 3 is not used, the outdoor flow rate control unit 3m may be stopped.

(Function of the refrigeration cycle device 100 in FIG. 3)
4 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during cooling operation. As shown in FIG. 4, 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 use side heat exchanger 5 shown in FIG. 4 may be a single one or a plurality of ones. The heat medium heat exchanger 30 is connected so that the refrigerant from the heat source side heat exchanger 3 flows in, and further cools the refrigerant. The refrigerant condensed in the heat source side heat exchanger 3 and the heat medium heat exchanger 30 is decompressed by the flow control device 4, which is an expander, evaporated in the use side heat exchangers 5 of the use side units C1 and C2, and sucked into the compressor 1. The refrigeration cycle apparatus 100 performs a heat pump cycle by utilizing the heat radiation in the heat source side heat exchanger 3 and the heat medium heat exchanger 30 and the heat absorption in the use side heat exchangers 5c1 and 5c2. In particular, in the refrigeration cycle apparatus 100 shown in FIG. 3, by arranging the heat medium relay unit D1 that utilizes the external heat source E1 having a lower temperature downstream of the heat source side heat exchanger 3, supercooling can be performed to the external heat source temperature t.

Note that in the cooling operation of the refrigeration cycle device 100 shown in FIG. 3, one of the two user side units C1, C2 can also be put into heating operation. For example, when the user side unit C2 in FIG. 3 is put into heating operation, the user side heat exchanger 5c2 functions as a condenser. At this time, the second flow path switching device 10c is controlled so that the low pressure side solenoid valve 8c2 is closed, the high pressure side solenoid valve 9c1 is opened, and the refrigerant from the high pressure side branch section 10a flows into the user side heat exchanger 5c2. In other words, as shown in FIG. 4(b), the user side heat exchanger 5c2 is arranged in parallel with the heat medium heat exchanger 30d1 in the refrigerant circuit.

(Operation condition No. 2: Cooling operation)
Fig. 5 is an explanatory diagram of the flow of the refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is operating in cooling mode. Fig. 5 shows the state of the refrigeration cycle apparatus 100 under the operating condition No. 2 in Table 1. The operating condition No. 2 is a case where the outside air temperature T is lower than the external heat source temperature t. The refrigerant discharged from the compressor 1 is first condensed in the heat medium heat exchanger 30, and then condensed in the heat source side heat exchanger 3. This allows the refrigerant to be condensed to a temperature equivalent to the lower outside air temperature, ensuring an enthalpy difference between the refrigerant before and after passing through the condenser, and thus improving the cooling capacity.

In FIG. 5, as in FIG. 3, a cooling operation in which all of the user side units C1 and C2 perform cooling will be described. At this time, the control device 50 switches the first flow path switching device 2a 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. Note that some of the user side units C1 and C2 can also be put into heating operation. In this case, the low pressure side solenoid valve 8 of the user side unit C performing heating operation is closed, and the high pressure side solenoid valve 9 is opened.

When the compressor 1 starts operating, 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 third flow path switching device 2b via the first flow path switching device 2a. The third flow path switching device 2b is switched to connect the external heat source circuit 90 to the first flow path switching device 2a and the heat source side heat exchanger 3, so that the refrigerant that has flowed through the external heat source circuit 90 flows into the heat source side heat exchanger 3. The refrigerant discharged from the compressor 1 and flowing into the external heat source circuit 90 flows from the piping 91 into the heat medium heat exchanger 30d1, where it is heat exchanged with the heat medium flowing through the heat medium circulation circuit 34, and is cooled while heating the heat medium, becoming a medium-temperature, high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant. The medium-temperature, high-pressure liquid refrigerant or gas-liquid two-phase refrigerant that flows out of the heat medium heat exchanger 30d1 returns to the third flow switching device 2b through the pipe 92, flows into the heat source side heat exchanger 3, and is further condensed. The medium-temperature, high-pressure refrigerant that flows out of the heat source side heat exchanger 3 passes through the high-pressure side pipe 7 and is separated into liquid refrigerant and gaseous refrigerant by the gas-liquid separation device 12. However, in the operating state shown in FIG. 5, the refrigerant that flows into the gas-liquid separation device 12 is condensed in the heat medium heat exchanger 30d1 and the heat source side heat exchanger 3, and is basically a high-pressure, medium-temperature supercooled liquid refrigerant.

The liquid refrigerant separated by the gas-liquid separator 12 flows into the second branch 11, as in the operating state shown in FIG. 3, is decompressed and expanded by the first flow control devices 4c1 and 4c2 of the user side units C1 and C2, is evaporated in the user side heat exchanger 5, returns to the heat source unit A from the low pressure side branch 10b, and is sucked into the low pressure side of the compressor 1.

In the operating state shown in FIG. 5, the low-pressure side solenoid valve 8d1 and the high-pressure side solenoid valve 9d1 of the second flow switching device 10c are closed, and the first branch section 10 and the heat medium relay unit D1 are not connected. The second flow control device 4d1 of the heat medium relay unit D1 is also closed. As a result, the refrigerant that has passed through the relay unit B does not flow into the heat medium relay unit D1.

(Function of the refrigeration cycle device 100 in FIG. 5)
FIG. 6 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during cooling operation. As shown in FIG. 6, 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 use side heat exchanger 5 shown in FIG. 6 may be a single one or a plurality of ones. The heat medium heat exchanger 30 is connected so that the refrigerant from the compressor 1 flows in, and cools the refrigerant. Thereafter, as necessary, the refrigerant flows into the heat source side heat exchanger 3 and is further cooled. The refrigerant condensed in the heat medium heat exchanger 30 and the heat source side heat exchanger 3 is decompressed by the flow control device 4, which is an expander, evaporated in the use side heat exchangers 5 of the use side units C1 and C2, and sucked into the compressor 1. The refrigeration cycle apparatus 100 performs a heat pump cycle by utilizing the heat radiation in the heat source side heat exchanger 3 and the heat medium heat exchanger 30 and the heat absorption in the use side heat exchangers 5c1 and 5c2. In particular, in the refrigeration cycle device 100 shown in Figure 5, the refrigerant is cooled and condensed using an external heat source E that is relatively hotter than the outside air, and the refrigerant is further cooled using the outside air that is relatively cold, thereby supercooling the refrigerant to the outside air temperature T.

Note that in the cooling operation of the refrigeration cycle device 100 shown in FIG. 5, one of the two user side units C1, C2 can also be put into heating operation. For example, when the user side unit C2 in FIG. 5 is put into heating operation, the user side heat exchanger 5c2 functions as a condenser. At this time, the second flow path switching device 10c is controlled so that the low pressure side solenoid valve 8c2 is closed, the high pressure side solenoid valve 9c1 is opened, and the refrigerant from the high pressure side branch section 10a flows into the user side heat exchanger 5c2. In other words, as shown in FIG. 6(b), the user side heat exchanger 5c2 is arranged in series downstream of the heat medium heat exchanger 30d1 and the heat source side heat exchanger 3 in the refrigerant circuit.

(Operation condition No. 3: heating operation)
FIG. 7 is an explanatory diagram of the flow of the refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is in heating operation. FIG. 7 shows the state of the refrigeration cycle apparatus 100 under the operating condition of No. 3 in Table 1. The operating condition of No. 3 is a case where the external heat source temperature t is lower than the freezing threshold temperature f of the intermediate heat exchanger 30d1. The freezing threshold temperature f of the intermediate heat exchanger 30d1 varies depending on the performance of the intermediate heat exchanger 30d1 and is determined by conducting a test. The refrigerant discharged from the compressor 1 is used for heating operation in the user side units C1 and C2, and then flows into the intermediate heat exchanger 30d1 of the intermediate heat medium converter D1 functioning as an evaporator, where it is evaporated, and then returns to the heat source unit A and is further evaporated in the heat source side heat exchanger 3. The refrigeration cycle apparatus 100 can utilize the external heat source E so that freezing does not occur in the heat medium heat exchanger 30d1 by flowing the refrigerant through the heat medium heat exchanger 30d1 before the heat source side heat exchanger 3. In an actual refrigeration cycle, a low pressure loss occurs in which the temperature at the outlet side of the evaporator decreases relative to the inlet side due to the resistance of the pipes, and as shown in the diagram of FIG. 8, the distance between points da and a is inclined downward toward point a. Due to the low pressure loss, the evaporator may frost because a low temperature refrigerant flows through it, but under the operating conditions shown in FIG. 7, even if the temperature t of the external heat source E1 is low, a relatively high temperature refrigerant flows into the heat medium heat exchanger 30d1 first, so that frost formation is suppressed. In addition, the refrigeration cycle apparatus 100 improves the evaporation capacity by making the heat medium heat exchanger 30 function as an evaporator in addition to the heat source side heat exchanger 3.

In FIG. 7, the case of heating operation in which all of the user side units C1 and C2 perform heating will be described. When heating operation is performed, the control device 50 directly connects the first flow path switching device 2a to the high pressure side pipe 7, and switches so that the refrigerant discharged from the compressor 1 flows out from the high pressure side pipe 7. In addition, the high pressure side solenoid valves 9c1 and 9c2 connected to the user side units C1 and C2 are opened, and the low pressure side solenoid valves 8c1 and 8c2 are closed.

When the compressor 1 is operated, 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 high-pressure side branch 10a of the first branch 10 via the first flow switching device 2a and the high-pressure side piping 7. The high-temperature, high-pressure gaseous refrigerant that flows into the high-pressure side branch 10a is branched, passes through the high-pressure side solenoid valves 9c1, 9c2, and flows into the user side heat exchangers 5c1, 5c2. The refrigerant is then cooled while heating the indoor air, becoming a medium-temperature, high-pressure liquid refrigerant.

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. The refrigerant expands and is decompressed in the first flow control devices 4c1, 4c2, becoming a medium-temperature, medium-pressure two-phase gas-liquid refrigerant, which merges at the second branch section 11. The refrigerant that flows into the second branch section 11 flows into the second bypass pipe 14b or the heat medium converter D1.

A portion of the refrigerant that flows into the second branch 11 flows from the second bypass pipe 14b through the fourth flow control device 15 into the low-pressure branch 10b of the first branch 10. In addition, a portion of the refrigerant that flows into the second branch 11 flows into the heat medium converter D1. The refrigerant that flows into the heat medium converter D1 is expanded and decompressed in the second flow control device 4d1 to be medium-temperature and medium-pressure, and then exchanges heat with the heat medium from the external heat source E1 in the heat medium heat exchanger 30d1 to evaporate, becoming a low-temperature, low-pressure gas refrigerant that flows into the low-pressure branch 10b of the first branch 10.

The refrigerant that joins at the low-pressure side branch 10b passes through the low-pressure side piping 6 and flows into the first flow control device 22, where it becomes a low-temperature, low-pressure, two-phase gas-liquid state, and is heated while cooling the outdoor air in the heat source side heat exchanger 3, becoming a low-temperature, low-pressure gaseous refrigerant. Note that if the refrigerant that has entered the low-pressure side 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 side heat exchanger 3.

Also, the entire refrigerant that flows into the second branch section 11 from the user side units C1, C2 performing heating operation may be made to flow into the heat medium converter D1. In this way, the entire amount of refrigerant can be evaporated using the external heat source E1, reducing the load on the heat source side heat exchanger 3 and leading to energy savings. Also, if the entire amount of refrigerant can be sufficiently converted into low-temperature, low-pressure gas refrigerant in the heat medium converter D1, the refrigeration cycle apparatus 100 may not use the outdoor flow control device 3m, or may cause the refrigerant to be drawn into the compressor 1 without using the heat source side heat exchanger 3.

As described above, in the heating operation of the refrigeration cycle device 100, not only the heat source side heat exchanger 3 is used as an evaporator, but also the heat medium converter D1 can be used as an evaporator. 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 flowing through the heat source side heat exchanger 3 can be bypassed and sucked into the compressor 1. The refrigerant that does not pass through the heat source side heat exchanger 3 but passes through the bypass piping 25 flows into the accumulator 29 and is sucked into the compressor 1. In this way, the heat medium converter D1 can complement the capacity of the heat source side heat exchanger 3 by using the external heat source E1.

Also, depending on the capacity of the heat medium relay unit D1, it is possible to prevent the refrigerant from flowing through the heat source side heat exchanger 3 in the heat source unit A, and have all the refrigerant sucked into the compressor 1 through the bypass piping 25. In the heat medium relay unit D1, the refrigerant becomes a low-temperature, low-pressure gas refrigerant, passes through the low-pressure side branching section 10b, passes through the low-pressure side piping 6, passes through the second flow control device 26, passes through the bypass piping 25, and the first flow path switching device 2a, and is sucked into the compressor 1. In FIG. 6, it is preferable that the bypass piping 25 is connected between the first flow path switching device 2a and the third flow path switching device 2b.

(Operation of the refrigeration cycle device 100 in FIG. 7)
FIG. 8 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during heating operation. As shown in FIG. 8, during heating operation, the user side heat exchanger 5 functions as a condenser, and the heat medium heat exchanger 30 and the heat source side heat exchanger 3 function as evaporators. The user side heat exchanger 5 shown in FIG. 8 may be a single one or a plurality of ones. The heat medium heat exchanger 30 is connected before the heat source side heat exchanger 3 so that the refrigerant flows in, and heats the refrigerant. The refrigerant condensed in the user side heat exchanger 5 is decompressed by the flow control device 4, which is an expander, and evaporates in the heat medium converter D and the heat source unit A, and is sucked into the compressor 1. The refrigeration cycle apparatus 100 performs a heat pump cycle by utilizing the heat absorption in the heat source side heat exchanger 3 and the heat medium heat exchanger 30 and the heat release in the user side heat exchangers 5c1 and 5c2. In particular, in the refrigeration cycle apparatus 100 shown in FIG. 8, a heat medium relay unit D1 that utilizes an external heat source E having a temperature lower than the freezing threshold is disposed upstream of the heat source-side heat exchanger 3. This makes it possible to suppress frost formation on the heat medium relay unit D1 and to assist or complement the ability of the heat source-side heat exchanger 3 to function as an evaporator.

Note that in the heating operation of the refrigeration cycle device 100 shown in FIG. 7, one of the two user side units C1, C2 can also be put into cooling operation. For example, when the user side unit C2 in FIG. 7 is put into cooling operation, the user side heat exchanger 5c2 functions as an evaporator. At this time, the second flow path switching device 10c is controlled so that the low pressure side solenoid valve 8c2 is opened, the high pressure side solenoid valve 9c2 is closed, and the refrigerant from the second branch section 11 flows into the user side heat exchanger 5c2 via the flow control device 4c2. In other words, as shown in FIG. 8(b), the user side heat exchanger 5c2 is arranged in parallel with the heat medium heat exchanger 30 in the refrigerant circuit.

(Regarding operation condition No. 4: heating operation)
FIG. 9 is an explanatory diagram of the flow of the refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is in heating operation. FIG. 9 shows the state of the refrigeration cycle apparatus 100 under the operating condition No. 4 in Table 1. The operating condition No. 4 is a case where the external heat source temperature t is higher than the freezing threshold temperature f of the heat medium heat exchanger 30d1. The refrigerant discharged from the compressor 1 is used for heating operation in the user side units C1 and C2, and then flows into the heat source side heat exchanger 3 functioning as an evaporator and is evaporated, and then flows from the third flow switching device 2b into the heat medium heat exchanger 30d1 of the heat medium converter D1 and is further evaporated. As a result, a relatively high temperature refrigerant is caused to flow into the heat source side heat exchanger 3, so that the heat source side heat exchanger 3 is prevented from frosting, and the refrigerant whose temperature has been reduced due to low pressure loss is caused to flow into the heat medium heat exchanger 30 that is not likely to freeze and is evaporated, thereby improving the evaporation capacity of the refrigeration cycle apparatus 100 as a whole.

In FIG. 9, as in FIG. 7, a heating operation in which all of the user side units C1 and C2 perform heating will be described. When heating operation is performed, the control device 50 directly connects the first flow path switching device 2a to the high pressure side piping 7, and switches so that the refrigerant discharged from the compressor 1 flows out from the high pressure side piping 7. In addition, the high pressure side solenoid valves 9c1 and 9c2 connected to the user side units C1 and C2 are opened, and the low pressure side solenoid valves 8c1 and 8c2 are closed.

When the compressor 1 is operated, 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 user side units C1 and C2 from the high-pressure side branch 10a of the first branch 10, as in the case of FIG. 7. The high-temperature, high-pressure gaseous refrigerant that flows into the user side units C1 and C2 is heated while cooling the indoor air, and becomes a medium-temperature, high-pressure liquid or two-phase gas-liquid refrigerant that flows into the second branch 11. The liquid or two-phase gas-liquid refrigerant that flows into the second branch 11 flows into the low-pressure side branch via the second bypass piping 14b and returns to the heat source unit A.

The refrigerant that has returned to the heat source unit A is evaporated in the heat source side heat exchanger 3, and then flows from the third flow path switching device 2b into the external heat source circuit 90 and is sent to the heat medium converter D. In the heat medium converter D, the refrigerant is further evaporated in the heat medium heat exchanger 30d1, returns to the heat source unit A again, and is sucked into the compressor 1 via the first flow path switching device 2a. Note that a part or all of the refrigerant flowing through the heat source side heat exchanger 3 can also be circulated using the bypass piping 25. In FIG. 9, the bypass piping 25 is preferably connected between the heat source side heat exchanger 3 and the third flow path switching device 2b.

In the operating state shown in FIG. 9, the low-pressure side solenoid valve 8d1 and the high-pressure side solenoid valve 9d1 of the second flow path switching device 10c are closed, and the first branch section 10 and the heat medium relay unit D1 are not connected.

(Function of the refrigeration cycle device 100 in FIG. 9)
Fig. 10 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during heating operation. As shown in Fig. 10, during heating operation, the user side heat exchanger 5 functions as a condenser, and the heat medium heat exchanger 30 and the heat source side heat exchanger 3 function as evaporators. The user side heat exchanger 5 shown in Fig. 10 may be a single one or a plurality of ones. The heat medium heat exchanger 30 is connected after the heat source side heat exchanger 3 so that the refrigerant flows in, and heats the refrigerant. The refrigerant condensed in the user side heat exchanger 5 is decompressed by the flow control device 4, which is an expander, and evaporates in the heat medium converter D and the heat source unit A, and is sucked into the compressor 1. The refrigeration cycle apparatus 100 performs a heat pump cycle by utilizing the heat absorption in the heat source side heat exchanger 3 and the heat medium heat exchanger 30 and the heat release in the user side heat exchangers 5c1 and 5c2. 9, an external heat source E having a temperature higher than the freezing threshold is used, and a heat medium relay unit D1 that is free from the risk of freezing is disposed downstream of the heat source-side heat exchanger 3, thereby improving the evaporation capacity while avoiding the risk of freezing due to low-pressure pressure loss. Furthermore, a refrigerant with a relatively high temperature is first allowed to flow into the heat source-side heat exchanger 3, thereby suppressing frost formation on the heat source-side heat exchanger 3.

Note that in the heating operation of the refrigeration cycle device 100 shown in FIG. 9, one of the two user side units C1, C2 can also be put into cooling operation. For example, when the user side unit C2 in FIG. 9 is put into cooling operation, the user side heat exchanger 5c2 functions as an evaporator. At this time, the second flow path switching device 10c is controlled so that the low pressure side solenoid valve 8c2 is opened, the high pressure side solenoid valve 9c2 is closed, and the refrigerant from the second branch section 11 flows into the user side heat exchanger 5c2 via the flow control device 4c2. In other words, as shown in FIG. 10(b), the user side heat exchanger 5c2 is arranged in series with the heat source side heat exchanger 3 and the heat medium heat exchanger 30 in the refrigerant circuit.

(Operation condition No. 5: heating operation)
The operating condition of No. 5 in Table 1 is a case where the external heat source temperature t is lower than the freezing threshold temperature f of the intermediate heat exchanger 30d1. The refrigeration cycle apparatus 100 under the operating condition of No. 5 in Table 1 can also perform a conventional heating operation without using the intermediate heat exchanger 30. At this time, the second flow switching device 10c has the low pressure side solenoid valve 8d1 and the high pressure side solenoid valve 9d1 closed, and the third flow switching device 2b is switched to connect the heat source side heat exchanger 3 and the first flow switching device 2a, and is controlled so that the refrigerant does not flow through the heat medium converter D1. In this way, when the external heat source temperature t is lower than the freezing threshold temperature f of the intermediate heat exchanger 30d1, the refrigeration cycle apparatus 100 can protect the intermediate heat exchanger 30d1 without using it.

(Regarding operating condition No. 6: Defrost operation)
FIG. 11 is an explanatory diagram of the flow of the refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is in defrost operation. FIG. 11 shows the state of the refrigeration cycle apparatus 100 under the operating condition of No. 6 in Table 1. The operating condition of No. 6 is to continue the heating operation of the user side units C1 and C2 while flowing hot gas into the heat source side heat exchanger 3 to perform defrosting. The operating condition of No. 6 is a case where the external heat source temperature t is higher than the freezing threshold temperature f of the heat medium heat exchanger 30d1. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 1 is defrosted by flowing directly into the heat source side heat exchanger 3 from the first flow switching device 2a through the third flow switching device 2b. The refrigerant that has left the heat source side heat exchanger 3 is sent to the user side units C1 and C2, where it is cooled and condensed while heating the indoor air, etc. The refrigerant flowing out of the user side units C2 and C2 joins at the second branching section 11 and flows into the heat medium relay unit D1. In the heat medium relay unit D1, the refrigerant is evaporated by utilizing heat from the external heat source E1. The evaporated refrigerant returns to the heat source unit A via the low pressure side pipe 6, and is drawn into the compressor 1 via the first flow switching device 2a and the accumulator 29.

(Function of the refrigeration cycle device 100 in FIG. 11)
Fig. 12 is a Mollier diagram of the refrigeration cycle apparatus 100 according to the first embodiment during defrost operation. During the defrost operation shown in Fig. 12, the heat source side heat exchanger 3 performing defrosting and the user side heat exchanger 5 performing heating operation function as condensers, and the heat medium heat exchanger 30 functions as an evaporator. The user side heat exchanger 5 shown in Fig. 12 may be a single one or a plurality of heat medium heat exchangers. The heat medium heat exchanger 30 is connected so that the refrigerant flows into the heat source side heat exchanger 3 and the user side units C1 and C2 after the heat source side heat exchanger 3 and heats the refrigerant. As a result, the refrigeration cycle apparatus 100 can perform a defrost operation of the heat source side heat exchanger 3 while continuing the heating operation by using the external heat source E1.

(Regarding operating condition No. 7: Defrost operation)
Fig. 13 is an explanatory diagram of the flow of the refrigerant when the refrigeration cycle apparatus 100 according to the first embodiment is in defrost operation. Fig. 13 shows the state of the refrigeration cycle apparatus 100 under the operating condition No. 7 in Table 1. The operating condition No. 7 is a case where the external heat source temperature t is lower than the freezing threshold temperature f of the heat medium heat exchanger 30d1, and defrosting is performed by flowing hot gas into the heat source side heat exchanger 3 while the heating operation of the user side units C1 and C2 is stopped. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 1 is defrosted by flowing directly into the heat source side heat exchanger 3 through the first flow switching device 2a and the third flow switching device 2b. The refrigerant that has left the heat source side heat exchanger 3 flows into the heat medium relay unit D1 through the gas-liquid separator 12 and the second branching section 11, and is evaporated. The refrigerant that has flowed out of the heat medium relay unit D1 returns to the heat source unit A through the low-pressure side pipe 6, and is then sucked into the compressor 1 through the first flow switching device 2a and the accumulator 29.

(Operation of the refrigeration cycle device 100 in FIG. 13)
Fig. 14 shows a Mollier diagram during defrost operation of the refrigeration cycle apparatus 100 according to the first embodiment. During the defrost operation shown in Fig. 14, only the heat source side heat exchanger 3 performing defrosting functions as a condenser, and the heat medium heat exchanger 30 functions as an evaporator. The heat medium heat exchanger 30 is connected after the heat source side heat exchanger 3 so that the refrigerant flows in, and heats the refrigerant. The refrigeration cycle apparatus 100 can perform the defrost operation of the heat source side heat exchanger 3 in a short time by using the external heat source E1 as an evaporator.

No. 8 in Table 1 is a case where the external heat source temperature t is lower than the freezing threshold temperature f of the heat exchanger 30d1. In this case, no refrigerant flows through the heat exchanger 30d1, and defrost operation is performed only by the compressor 1.

As described above, the refrigeration cycle apparatus 100 according to the first embodiment is configured so that the heat medium converter D1 utilizing the external heat source E can be used to supplement or complement the heat source side heat exchanger 3, and further so that the heat medium converter D1 can be appropriately connected to the upstream side or downstream side of the heat source side heat exchanger 3. This allows the refrigeration cycle apparatus 100 to appropriately use the heat medium converter D1 depending on the temperature of the external heat source E1, and the heat medium converter D1 can be used more efficiently as an auxiliary heat source.

Embodiment 2.
A refrigeration cycle apparatus 200 according to the second embodiment is a case where a plurality of heat medium relay units D1, D2 are provided in the refrigeration cycle apparatus 100 according to the first embodiment. The following mainly describes the differences between the second embodiment and the first embodiment.

FIG. 15 is an example of a circuit diagram showing a refrigeration cycle apparatus 200 according to the second embodiment. The refrigeration cycle apparatus 200 is obtained by adding a heat medium converter D2 to the components of the first embodiment. The heat medium converter D2 is connected to the relay unit B in the same manner as the heat medium converter D1, and is also directly connected to the heat source unit A.

The heat source unit A and the heat medium converters D1 and D2 are connected via an external heat source circuit 90. In the external heat source circuit 90, pipes 91 and 92 extending from the third flow switching device 2b of the heat source unit A branch off and are connected to the heat medium converters D1 and D2, respectively. The pipe 91 is connected to the second connection pipes 41d1 and 41d2, and the pipe 92 is connected to the first connection pipes 40d1 and 40d2, respectively. The pipe 91 is provided with opening and closing valves 94d1 and 94d2 on the branched pipes, respectively, and it is possible to select whether or not to circulate the refrigerant from the heat source unit A to the heat medium heat exchangers 30d1 and 30d2.

In the refrigeration cycle apparatus 200 according to the second embodiment, the two heat medium relay units D1 and D2 can be used in the same way, or one can receive refrigerant directly from the heat source unit A, and the other can receive refrigerant via the relay unit B. When using two external heat sources E1 and E2 with different temperatures, the refrigeration cycle apparatus 200 can use the heat medium relay units D1 and D2 depending on the relationship between the external heat source temperature t and the outside air temperature T or the freezing threshold temperature f. This allows the heat medium relay units D1 and D2 to efficiently assist and complement the capacity of the heat source side heat exchanger 3 as a condenser or evaporator depending on the environment. In the second embodiment, two heat medium relay units D are connected to the refrigeration cycle apparatus 200, but more may be installed.

As shown in FIG. 15, since a plurality of heat medium converters D can be installed in parallel on the relay unit B, a plurality of external heat sources E can be used for the refrigeration cycle device 200. For example, when the refrigeration cycle device 200 performs cooling operation or cooling-dominated operation, the heat source side heat exchanger 3 functions as a condenser, and the heat medium converter D1 using the well water as the external heat source E1 also functions as a condenser, so that the capacity of the heat source side heat exchanger 3 during cooling operation or cooling-dominated operation can be supplemented by the heat medium converter D1. Also, for example, when the refrigeration cycle device 100 performs heating operation or heating-dominated operation, the heat source side heat exchanger 3 functions as an evaporator, and the heat medium converter D2 using the sunlight as the external heat source E2 also functions as an evaporator, so that the capacity of the heat source side heat exchanger 3 during heating operation or heating-dominated operation can be supplemented by the heat medium converter D2.

The refrigeration cycle apparatus 200 according to the second embodiment can appropriately select the operating state of the multiple user side units C from cooling, heating, and water heating operation by switching the connection between the heat source unit A and the user side units C using the second flow path switching device 10c, thereby enabling simultaneous cooling and heating operation. In addition, the refrigeration cycle apparatus 200 can appropriately switch the external heat source E to be used as an auxiliary for the heat source side heat exchanger 3 or as a substitute for the heat source side heat exchanger 3 by switching the connection state with the multiple heat medium converters D using the second flow path switching device 10c.

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 devices 100 and 200, and may be combined with other known technologies. Furthermore, the refrigeration cycle devices 100 and 200 may have parts of their configuration omitted or modified without departing from the gist of the present disclosure. In short, the refrigeration cycle devices 100 and 200 include the range of design modifications and application variations that would normally be made by a person skilled in the art, without departing from the technical concept thereof.

1 compressor, 2 heat source side flow switching device, 2a first flow switching device, 2b third 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, 5 utilization side heat exchanger, 5c1 utilization side heat exchanger, 5c2 utilization side 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, 8d1 low pressure side solenoid valve, 9 high pressure side solenoid valve, 9c1 High pressure side solenoid valve, 9c2 high pressure side solenoid valve, 9d1 high pressure side solenoid valve, 10 first branch, 10a high pressure side branch, 10b low pressure side branch, 10c second flow path switching device, 11 second branch, 12 gas-liquid separation device, 13 third flow control device, 14 fourth 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 second 1 pipe, 29 accumulator, 30 intermediate heat exchanger, 30d1 intermediate heat exchanger, 30d2 intermediate heat exchanger, 31 pump, 32 external heat source temperature sensor, 33 external heat source temperature sensor, 34 heat medium circulation circuit, 40 first connection pipe, 40c1 first connection pipe, 40c2 first connection pipe, 40d1 first connection pipe, 40d2 first connection pipe, 41 second connection pipe, 41c1 second connection pipe, 41c2 second connection pipe, 41d1 second connection pipe, 41d2 second connection pipe, 50 control device, 50a memory, 51 discharge pressure gauge, 52 Suction pressure gauge, 53 medium pressure gauge, 54 thermometer, 60a first connection pipe, 60b second connection pipe, 90 external heat source circuit, 91 pipe, 92 pipe, 93 on-off valve, 94d1 on-off valve, 94d2 on-off valve, 100 refrigeration cycle device, 200 refrigeration cycle device, A heat source device, B relay device, C user unit, C1 user unit, C2 user unit, C3 user unit, D heat medium converter, D1 heat medium converter, D12 heat medium converter, D2 heat medium converter, E external heat source, E1 external heat source, E2 external heat source, F external heat exchanger.

Claims (6)

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 flows out from the heat source unit;
A low-pressure side pipe through which the refrigerant flows in and out of the heat source unit;
a utilization side unit connected to the high pressure side pipe and the low pressure side pipe, the utilization side unit including a first flow control device for controlling a flow rate of the refrigerant flowing through the utilization side heat exchanger;
a 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 each of the high pressure side pipe and the low pressure side pipe to the utilization side unit and is connected to a first connection pipe extending from the utilization side unit;
a second branch portion connected to a second connection pipe extending from the first flow control device;
an external heat source circuit that circulates the refrigerant between the heat source unit and the heat medium converter without passing through the first branch portion and the second branch portion;
The first branch portion is
A second flow path switching device is provided to switch a connection between the first connection pipe and the high pressure side pipe or the low pressure side pipe,
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 through the heat source side heat exchanger to the high pressure side pipe, 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 flow from the discharge side of the compressor to the high pressure side pipe, and the refrigerant is connected to flow from the low pressure side pipe to the suction side of the compressor via the heat source side heat exchanger,
The external heat source circuit includes:
The refrigerant is configured to flow between the discharge side or the suction side of the compressor and the heat source side heat exchanger via the heat medium heat exchanger.
Refrigeration cycle equipment. The heat transfer medium converter comprises:
A first connection pipe connected to the first branch portion;
The second connection pipe extends from the second flow control device and is connected to the second branch portion,
The second flow path switching device is
The heat medium-to-heat medium heat exchanger is configured to function as an auxiliary condenser when the heat source-side heat exchanger functions as a condenser, and the heat medium-to-heat medium heat exchanger is configured to function as an auxiliary evaporator when the heat source-side heat exchanger functions as an evaporator.
The refrigeration cycle device according to claim 1. The heat source machine is
Further comprising a third flow path switching device connected between the first flow path switching device and the heat source side heat exchanger,
The third flow path switching device is
The refrigerant is connected to the external heat source circuit and flows between the compressor and the heat source side heat exchanger, and the refrigerant is switched to flow to the heat medium heat exchanger.
The refrigeration cycle device according to claim 1 or 2. A control device is provided to control the first flow path switching device, the second flow path switching device, and the third flow path switching device.
The control device includes:
When the relationship between the outdoor air temperature T and the external heat source temperature t is t>T during cooling operation, or when the relationship between the freezing threshold temperature f of the heat medium heat exchanger and the external heat source temperature t is t>f during heating operation,
controlling the third flow path switching device to cause the refrigerant to flow through the external heat source circuit;
controlling the second flow switching device to stop the flow of the refrigerant between the first branch portion and the heat medium relay unit;
The refrigeration cycle device according to claim 3. A control device is provided to control the first flow path switching device, the second flow path switching device, and the third flow path switching device.
The control device includes:
When the relationship between the outdoor air temperature T and the external heat source temperature t is t<T during cooling operation, or when the relationship between the freezing threshold temperature f of the heat medium heat exchanger and the external heat source temperature t is t<f during heating operation,
controlling the third flow switching device so as not to cause the refrigerant to flow through the external heat source circuit;
controlling the second flow switching device so as to cause the refrigerant to flow between the first branch portion and the heat medium relay unit;
The refrigeration cycle device according to claim 3 or 4. A control device is provided to control the first flow path switching device, the second flow path switching device, and the third flow path switching device.
The control device includes:
controlling the third flow switching device so as not to cause the refrigerant to flow through the external heat source circuit;
controlling the second flow switching device to stop the flow of the refrigerant between the first branch portion and the heat medium relay unit;
The refrigeration cycle device according to any one of claims 3 to 5.

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