GB2566381A

GB2566381A - Refrigeration cycle system

Info

Publication number: GB2566381A
Application number: GB1818994.4A
Authority: GB
Inventors: Arii Yusuke; Ikeda Takashi; Sata Hiroshi; Ishikawa Tomotaka
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-07-04
Filing date: 2016-07-04
Publication date: 2019-03-13
Anticipated expiration: 2036-07-04
Also published as: GB201818994D0; GB2566381B; JPWO2018008053A1; WO2018008053A1; JP6615345B2

Abstract

A refrigeration cycle system, provided with: a dual refrigeration cycle having a high temperature-side circuit, in which a first compressor, a first heat exchanger, a condenser, a first expansion valve, and a cascade heat exchanger are connected by refrigerant piping, and a low temperature-side circuit in which a second compressor, a second heat exchanger, the cascade heat exchanger, a second expansion valve, and an evaporator are connected by refrigerant piping, the low temperature-side circuit exchanging heat with the high temperature-side circuit in the cascade heat exchanger; and a waste heat recovery circuit in which the first heat exchanger and the second heat exchanger are connected by piping, the waste heat recovery circuit channeling a heat medium. The waste heat recovery circuit has a first channel for channeling the heat medium from the first heat exchanger to the second heat exchanger, a second channel for channeling the heat medium from the second heat exchanger to the first heat exchanger, and a channel-switching device for switching between the first channel and the second channel.

Description

DESCRIPTION

Title of Invention

REFRIGERATION CYCLE SYSTEM

Technical Field [0001]

The present invention relates to a refrigeration cycle system that effectively utilizes exhausted heat in a refrigeration apparatus including a dual refrigeration cycle.

Background Art [0002]

Some conventional heat pump apparatuses using a dual refrigeration cycle allow heat exchange with refrigerant in a lower-order circuit and refrigerant in a higher-order circuit to supply heated water (for example, see Patent Literature 1). Furthermore, some conventional refrigeration cycle apparatuses switch between recovering only sensible heat and recovering sensible heat and condensation heat to satisfy both the heat amount of recovered exhausted heat and the coefficient of performance (COP) of a refrigeration apparatus (for example, see Patent Literature 2). In Patent Literature 2, a plurality of switching valves of a refrigeration cycle are opened and closed depending on the high-low relationship of the condensing temperature of refrigerant and water temperature, so that flow paths through which refrigerant flows can be switched.

[0003]

Furthermore, to address global warming issues, refrigerant with a low global warming potential (GWP) has been paid attention to. For example, an R744 (CO2) refrigerant is a non-toxic refrigerant with a GWP of 1. Consequently, the R744 (CO2) refrigerant has been regarded as a refrigerant that can contribute to global warming prevention, in place of an HFC refrigerant such as R404A with a GWP of about 4,000 or R410A with a GWP of about 2,000. In contrast, the pressure of the R744 (CO2) refrigerant during operation is high, and its safety has to be taken into account. Furthermore, for use of the R744 (CO2) refrigerant, the pressure resistance strength of refrigerant pipes and individual components of the refrigeration cycle needs to be increased. Consequently, a high manufacturing cost may be required compared to a case of conventional HFC refrigerant or other types of refrigerant, and installation and construction may not be easy. To solve the above problem, there is a method for allowing heat exchange with a high-pressure portion of a refrigeration cycle using R744 (CO2) and a low-pressure portion of a different refrigeration cycle to reduce the use pressure of R744 (CO2). With the use of such a dual refrigeration cycle, a safe and inexpensive refrigeration apparatus with an excellent environmental friendliness can be achieved.

Citation List

Patent Literature [0004]

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2012-52767

Patent Literature 2: Japanese Patent No. 5921777 Summary of Invention

Technical Problem [0005]

A main purpose of systems utilizing exhausted heat discharged from a refrigeration apparatus is to cause a refrigeration apparatus to cool items. Consequently, the amount of heat that can be utilized as exhausted heat increases or decreases depending on refrigeration capacity. Furthermore, for example, the temperature characteristics of refrigerant are different between a refrigeration purpose and a freezing purpose, and the temperature and pressure of refrigerant vary depending on the ambient temperature or other conditions of the refrigeration apparatus. Consequently, although the heat pump apparatus described in Patent Literature 1 is specialized in supply of heated water, in the case of a system prioritizing a refrigeration apparatus, the amount of recoverable heat and efficiency vary depending on the refrigeration capacity, purpose, ambient temperature of the refrigeration apparatus, or other conditions.

[0006]

An object of the present invention is to provide a refrigeration cycle system that is capable of recovering exhausted heat efficiently from a refrigeration apparatus using a dual refrigeration cycle.

Solution to Problem [0007]

A refrigeration cycle system according to an embodiment of the present invention includes a dual refrigeration cycle including a higher-order circuit in which a first compressor, a first heat exchanger, a condenser, a first expansion valve, and a cascade heat exchanger are connected by refrigerant pipes, and a lower-order circuit in which a second compressor, a second heat exchanger, the cascade heat exchanger, a second expansion valve, and an evaporator are connected by refrigerant pipes, the lower-order circuit allowing heat exchange with the higher-order circuit in the cascade heat exchanger; and an exhausted heat recovery circuit in which the first heat exchanger and the second heat exchanger are connected by pipes, a heat medium flowing in the exhausted heat recovery circuit. The exhausted heat recovery circuit includes a first flow path allowing the heat medium to flow from the first heat exchanger to the second heat exchanger, a second flow path allowing the heat medium to flow from the second heat exchanger to the first heat exchanger, and a flow switching device configured to select either one of the first flow path and the second flow path.

Advantageous Effects of Invention [0008]

With a refrigeration cycle system according to an embodiment of the present invention, which one of the refrigerant in the higher-order circuit and the refrigerant in the lower-order circuit a heat medium is to be first subjected to heat exchange with can be switched, and consequently, efficient recovery of exhausted heat can be achieved depending on various operation conditions.

Brief Description of Drawings [0009] [Fig. 1] Fig. 1 is a circuit diagram of a refrigeration cycle system according to Embodiment 1.

[Fig. 2] Fig. 2 is a block diagram of a controller of the refrigeration cycle system according to Embodiment 1.

[Fig. 3] Fig. 3 includes P-H diagrams of the refrigeration cycle system according to Embodiment 1.

[Fig. 4] Fig. 4 illustrates images of heat exchange between water and refrigerant in counter flow and parallel flow.

[Fig. 5] Fig. 5 illustrates an image of heat exchange between water and refrigerant in the case where heat is sequentially exchanged through two refrigeration cycles.

[Fig. 6] Fig. 6 is a solenoid valve operation table for the refrigeration cycle system according to Embodiment 1.

[Fig. 7] Fig. 7 is a circuit diagram of a refrigeration cycle system according to Embodiment 2.

[Fig. 8] Fig. 8 is a circuit diagram of a refrigeration cycle system according to

Embodiment 3.

[Fig. 9] Fig. 9 is a circuit diagram of a refrigeration cycle system according to

Embodiment 4.

Description of Embodiments [0010]

Embodiment 1

Fig. 1 is a circuit diagram of a refrigeration cycle system according to Embodiment 1. A refrigeration cycle system 500 includes a heat source unit 100, a load device (indoor unit) 200 installed in a cooling target space, an exhausted heat recovery device 300, and other devices. The refrigeration cycle system 500 includes a dual refrigeration cycle 510 that includes a higher-order circuit 511 filled with refrigerant and a lower-order circuit 512 filled with refrigerant, and an exhausted heat recovery circuit 520 filled with a heat medium. An exhausted heat recovery method for causing the exhausted heat recovery circuit 520 to recover exhausted heat from the dual refrigeration cycle 510 constituting a part of a refrigeration apparatus so that heated water can be generated will be explained below with an example in which R744 (CO2) is used as refrigerant and water is used as a heat medium.

[0011]

In the higher-order circuit 511, at least a first compressor 121, a first heat exchanger 124, a condenser 122, a first expansion valve 123, and a cascade heat exchanger 101 are connected by refrigerant pipes. In the lower-order circuit 512, at least a second compressor 111, a second heat exchanger 113, the cascade heat exchanger 101, a second expansion valve 201, and an evaporator 202 are connected by refrigerant pipes. In the exhausted heat recovery circuit 520, the first heat exchanger 124 and the second heat exchanger 113 are connected by pipes. [0012]

For example, the entire higher-order circuit 511 and part of the lower-order circuit 512 are mounted in the heat source unit 100. In the higher-order circuit 511, refrigerant is compressed into high-temperature high-pressure gas refrigerant by the first compressor 121. At the first heat exchanger 124, the gas refrigerant discharged from the first compressor 121 is subjected to heat exchange with a heat medium in the exhausted heat recovery circuit 520. The refrigerant that has passed through the first heat exchanger 124 is further subjected to heat exchange at the condenser 122, heat is removed from the refrigerant, and the refrigerant turns into high-pressure liquid refrigerant or turns into a high-pressure two-phase state of liquid refrigerant and gas refrigerant. The condenser 122 may allow heat exchange with air using a heat exchanger or heat exchange with water. The refrigerant that has flowed out of the condenser 122 is decompressed into a low-temperature low-pressure two-phase state of liquid refrigerant and gas refrigerant by the first expansion valve 123. At the cascade heat exchanger 101, the refrigerant that has been decompressed into the two-phase state by the first expansion valve 123 is subjected to heat exchange with refrigerant in the lower-order circuit 512, receives heat, turns into low-pressure gas refrigerant, and returns to the compressor again.

[0013]

In the lower-order circuit 512, refrigerant is compressed into high-temperature high-pressure gas refrigerant by the second compressor 111, as in the higher-order circuit 511. At the second heat exchanger 113, the gas refrigerant discharged from the second compressor 111 is subjected to heat exchange with a heat medium in the exhausted heat recovery circuit 520. At the cascade heat exchanger 101, the refrigerant that has passed through the second heat exchanger is subjected to heat exchange with refrigerant in the higher-order circuit 511, condenses, and turns into high-pressure liquid refrigerant or turns into a high-pressure two-phase state of liquid refrigerant and gas refrigerant. The refrigerant that has condensed, flowed out of the cascade heat exchanger 101, and come out of the heat source unit 100 passes through a refrigerant pipe and enters the load device 200.

[0014]

The load device 200 is a unit cooler or other devices installed in, for example, a showcase, a refrigerator, or a freezer in a supermarket, and is used to cool foodstuff or other items. The remaining part of the lower-order circuit 512, such as the second expansion valve 201 and the evaporator 202, is mounted in the load device 200. High-pressure refrigerant that has entered the load device 200 is decompressed into a low-temperature low-pressure two-phase state of liquid refrigerant and gas refrigerant by the second expansion valve 201. The low-temperature low-pressure refrigerant that has passed through the second expansion valve 201 evaporates at the evaporator 202, turns into low-pressure gas refrigerant, passes through a refrigerant pipe again, and returns to the second compressor 111 of the heat source unit 100.

[0015]

In the exhausted heat recovery device 300, a heat medium is caused to circulate by motive power of a sending device 320, such as a pump. A circuit in which a heat medium is sent out through a circuit outlet of the exhausted heat recovery circuit 520 and supplied through a circuit inlet of the exhausted heat recovery circuit 520 again may be configured as a one-through type or a circulation heating type. The heat medium supplied to the exhausted heat recovery circuit 520 by the sending device 320 passes through pipes, flows into the first heat exchanger 124 and the second heat exchanger 113 that are mounted in the heat source unit 100, and receives heat by heat exchange with refrigerant. Thus, heated water is generated. The heated water generated at the exhausted heat recovery device 300 by recovering exhausted heat from the dual refrigeration cycle 510 is used as, for example, a heat source for heating for a living space or other types of processing. [0016]

The exhausted heat recovery circuit 520 includes a plurality of flow paths through which a heat medium passes and a flow switching device for selecting one or more of flow paths. In Embodiment 1, a case where a flow switching device includes a plurality of solenoid valves 301 to 306 for opening and closing flow paths will be explained.

[0017]

The plurality of solenoid valves 301 to 306 each open and close itself to select one or more of flow paths, so that a direction in which a heat medium flows can be controlled. The heat medium supplied through the circuit inlet to the exhausted heat recovery circuit 520 passes through flow paths selected by the plurality of solenoid valves 301 to 306, passes through the circuit outlet, and is sent out of the exhausted heat recovery circuit 520. First, the exhausted heat recovery circuit 520 includes a first flow path and a second flow path that each allow a heat medium to pass through both the first heat exchanger 124 and the second heat exchanger 113. The first flow path allows a heat medium to flow from the first heat exchanger 124 to the second heat exchanger 113. The second flow path allows a heat medium to flow from the second heat exchanger 113 to the first heat exchanger 124. Furthermore, the exhausted heat recovery circuit 520 also includes a first bypass flow path and a second bypass flow path that each allow a heat medium to pass through a corresponding one of the first heat exchanger 124 and the second heat exchanger 113. The first bypass flow path allows a heat medium to flow through the first heat exchanger 124 and bypass the second heat exchanger 113. The second bypass flow path allows a heat medium to flow through the second heat exchanger 113 and bypass the first heat exchanger 124.

[0018]

Next, a specific circuit configuration of the exhausted heat recovery circuit 520 will be explained. As illustrated in Fig. 1, a pipe through which a heat medium flows branches out into two pipes at a point P1 placed downstream of the circuit inlet. One of the pipes that branches off at the point P1 is connected to the first heat exchanger 124, and the other branch pipe is connected to the second heat exchanger 113. The solenoid valve 301 is provided at a pipe that connects the point P1 to the first heat exchanger 124, and the solenoid valve 302 is provided at the pipe that connects the point P1 to the second heat exchanger 113. Furthermore, a pipe extending from the first heat exchanger 124 and a pipe extending from the second heat exchanger 113 meet at a point P2 placed upstream of the circuit outlet. The solenoid valve 306 is provided at a pipe that connects the first heat exchanger 124 to the point P2, and the solenoid valve 305 is provided at a pipe that connects the second heat exchanger 113 to the point P2. At the first heat exchanger 124, the heat medium and the refrigerant in the higher-order circuit 511 have a counter flow relationship. At the second heat exchanger 113, the heat medium and the refrigerant in the lower-order circuit 512 have a counter flow relationship. Furthermore, a point P4 at a pipe between the first heat exchanger 124 and the solenoid valve 306 and a point P3 at a pipe between the second heat exchanger 113 and the solenoid valve 302 are connected by a first branch pipe B1, and the solenoid valve 303 is provided at the first branch pipe B1. Furthermore, a point P6 at a pipe between the first heat exchanger 124 and the solenoid valve 301 and a point P5 at a pipe between the second heat exchanger 113 and the solenoid valve 305 are connected by a second branch pipe B2, and the solenoid valve 304 is provided at the second branch pipe B2.

[0019]

The plurality of solenoid valves 301 to 306 switch the states of the exhausted heat recovery circuit 520 in such a manner that one or more of the first flow path, the second flow path, the first bypass flow path, and the second bypass flow path are opened. All the solenoid valves 301 to 306 may be closed so that exhausted heat is not recovered.

[0020]

The refrigeration cycle system 500 further includes a sensor group including a plurality of pressure sensors and a plurality of temperature sensors. Specifically, a first discharge temperature sensor 127 and a pressure sensor 126 are provided to the discharge portion of the first compressor 121. The first discharge temperature sensor 127 measures a first discharge temperature of refrigerant discharged from the first compressor 121, and the pressure sensor 126 measures the gas pressure of discharged gas. Furthermore, a pressure sensor 125 is provided to the suction portion of the first compressor 121. The pressure sensor 125 measures the gas pressure of suction to be gas sucked into the first compressor 121. A second discharge temperature sensor 116 and a pressure sensor 115 are provided to the discharge portion of the second compressor 111. The second discharge temperature sensor 116 measures a second discharge temperature of refrigerant discharged from the second compressor 111, and the pressure sensor 115 measures the gas pressure of discharged gas. Furthermore, a pressure sensor 114 is provided to the suction portion of the second compressor 111. The pressure sensor 114 measures the gas pressure of suction gas to be sucked into the second compressor 111. Furthermore, an inlet temperature sensor 308 is provided to the circuit inlet of the exhausted heat recovery circuit 520, and an outlet temperature sensor 307 is provided to the circuit outlet of the exhausted heat recovery circuit 520. The inlet temperature sensor 308 measures the inlet temperature of a heat medium supplied to the exhausted heat recovery circuit 520, and the outlet temperature sensor 307 measures the outlet temperature of a heat medium sent out from the exhausted heat recovery circuit 520. The sensor group including the plurality of pressure sensors 114, 115, 125, and 126, the first discharge temperature sensor 127, the second discharge temperature sensor 116, the inlet temperature sensor 308, the outlet temperature sensor 307, and other sensors not illustrated in drawings are connected to the controller 400 by wires or other communication units.

[0021]

Fig. 2 is a block diagram illustrating a controller of the refrigeration cycle system according to Embodiment 1. The controller 400 is, for example, a microcomputer and includes a memory unit 401, a calculation unit 402, an operation control unit 403, and other units.

[0022]

Various configurations may be considered for the load device 200 connected to the heat source unit 100. Thus, the controller 400 does not control each actuator mounted in the load device 200.

[0023]

The memory unit 401 is, for example, a memory such as a ROM. Setting information, the rotation frequency of the first compressor 121, the rotation frequency of the second compressor 111, and the rotation frequency of a fan provided to the condenser 122 that are associated with temperature, pressure, and other factors, control information on the opening degree of the first expansion valve 123, and other types of information are stored in the memory unit 401. Furthermore, for example, a solenoid valve operation table in which the high-low relationship of the measured inlet temperature, the first discharge temperature, and the second discharge temperature and control information on the solenoid valves 301 to 306 are associated with each other is stored in the memory unit 401. In addition to the control information on the solenoid valves 301 to 306, control information on the sending device 320 may further be stored in association in the solenoid valve operation table.

[0024]

The calculation unit 402 is, for example, a CPU (Central Processing Unit) or other units and performs calculation. The calculation unit 402 calculates set values or other values of individual devices on a circuit, on the basis of setting information, information stored in the memory unit 401, information acquired from the sensor group, and other types of information, in accordance with an instruction from the operation control unit 403. Set values of individual devices represent, for example, the rotation frequency of the first compressor 121, the rotation frequency of the second compressor 111, the rotation frequency of the fan provided to the condenser 122, and other values.

[0025]

The operation control unit 403 controls operation of the refrigeration cycle system 500 on the basis of information acquired from the sensor group, setting information input by a user using a remote controller or other devices, and other types of information. At this time, for example, the operation control unit 403 may acquire control information by referring to the memory unit 401 and cause the calculation unit 402 to calculate set values to be set for devices on individual circuits on the basis of the control information. Specifically, during operation of the heat source unit 100, the operation control unit 403 adjusts the operation rotation frequencies of the first compressor 121, the fan of the condenser 122, and the second compressor 111. Furthermore, the operation control unit 403 controls the exhausted heat recovery circuit 520 on the basis of the measured inlet temperature, the first discharge temperature, and the second discharge temperature. Specifically, the operation control unit 403 controls opening and closing of each of the solenoid valves 301 to 306, the activation and deactivation of the sending device 320, and other operations. [0026]

Next, an example of control, by the controller 400, for the first compressor 121, the second compressor 111, and the fan provided to the condenser 122 will be explained. The control described below is merely an example, and for operations in a case where an abnormality occurs or other cases, control may not be performed as described below.

[0027]

The controller 400 controls the rotation frequency of the second compressor 111 of the lower-order circuit 512 in such a manner that the low pressure (evaporating temperature) of the lower-order circuit 512 measured by the pressure sensor 114 is constant. Specifically, in the case where the low pressure of the lower-order circuit 512 increases, the rotation frequency of the second compressor 111 increases. In the case where the low pressure of the lower-order circuit 512 decreases, the rotation frequency of the second compressor 111 decreases. With this operation, the low pressure of the lower-order circuit 512 is maintained constant. The low pressure of the lower-order circuit 512 varies depending on the load in a space cooled by the load device 200. For example, in the case where many items are present in a cooling target space and the load is high, the low pressure of the lower-order circuit 512 increases. In contrast, in the case where the load is low, the low pressure decreases.

[0028]

As in the control of the lower-order circuit 512, the controller 400 controls the rotation frequency of the first compressor 121 of the higher-order circuit 511 in such a manner that the low pressure (evaporating temperature) of the higher-order circuit 511 measured by the pressure sensor 125 is constant. The low pressure of the higher-order circuit 511 varies depending on the amount of condensation required at the lower-order circuit 512. In the case where the load in the cooling target space is high, the rotation frequency of the second compressor 111 increases. Consequently, the amount of condensation required at the lower-order circuit 512 increases, and the rotation frequency of the first compressor 121 in the higher-order circuit 511 thus increases. Furthermore, the rotation frequency of the first compressor 121 of the higher-order circuit 511 varies depending on variations in the outside air temperature or other parameters.

[0029]

In the case where the condenser 122 of the higher-order circuit 511 is an aircooled type, the controller 400 controls the rotation frequency of the fan provided to the condenser 122 depending on the condensing temperature. Specifically, in a case where the outside air temperature is high or other cases, the condensing temperature increases, and the rotation frequency of the fan thus increases. In contrast, in the case where the outside air temperature is low or other cases, the condensing temperature decreases, and the rotation frequency of the fan thus decreases.

[0030]

Fig. 3 includes P-H diagrams of the refrigeration cycle system according to Embodiment 1. Typically in P-H diagrams, the horizontal axis represents enthalpy, and the vertical axis represents pressure. In Fig. 3, however, for simplification, the vertical axis represents saturation temperature of refrigerant. Part (a) of Fig. 3 is a P-H diagram of the dual refrigeration cycle 510. Points denoted by numbers 1 to 8 are provided in the diagram. Operations at the individual points will be explained below. [0031]

In Part (a) of Fig. 3, transition from 1 to 4 represents operations in the lowerorder circuit 512. The transition from 1 to 2 represents a step of compressing refrigerant performed by the second compressor 111. The pressure of the refrigerant increases in the transition from 1 to 2, and enthalpy increases due to motive power of the second compressor 111. The transition from 2 to 3 represents a step of condensation in the cascade heat exchanger 101. High-temperature high-pressure gas refrigerant compressed by the second compressor 111 condenses in the cascade heat exchanger 101. In the cascade heat exchanger 101, although the pressure of the refrigerant decreases only slightly, the refrigerant condenses and transfers heat to the higher-order circuit 511. Consequently, the enthalpy decreases. The transition from 3 to 4 represents a step of decompression in the second expansion valve 201 of the load device 200. The refrigerant is decompressed by the second expansion valve 201, and the pressure is thus reduced. However, the enthalpy does not change. The transition from 4 to 1 represents a step of evaporation performed by the evaporator 202 of the load device 200. In the evaporation step, the refrigerant receives heat from the outside and evaporates in the evaporator 202. At this time, the pressure of the refrigerant does not change. However, the refrigerant receives heat and enthalpy thus increases.

[0032]

Transition from 5 to 8 represents operations in the higher-order circuit 511 and changes in the pressure and enthalpy. As in the cycle of the lower-order circuit 512, the transition from 5 to 6 represents a step of compression in the first compressor

121, the transition from 6 to 7 represents a step of condensation in the condenser

122, the transition from 7 to 8 represents a step of decompression in the first expansion valve 123, and the transition from 8 to 5 represents a step of evaporation in the cascade heat exchanger 101.

[0033]

The form of a P-H diagram varies depending on the operation state of the dual refrigeration cycle 510. Part (b) of Fig. 3 represents changes in a P-H diagram for the case where the ambient temperature around the condenser 122 of the higherorder circuit 511 of the heat source unit 100 increases. A case where the condenser 122 is an air-cooled type will be explained. When the ambient temperature around the condenser 122 increases, the pressure (high pressure) increases in the transition from 6 to 7. That is, compared to Part (a), the value on the vertical axis in the transition from 6 to 7 is high in Part (b). When the high pressure of the higher-order circuit 511 increases, the temperature of refrigerant at the point denoted by 6, that is, the discharge temperature of the first compressor 121, increases.

[0034]

Part (c) of Fig. 3 represents an example of a case where the pressure of the lower-order circuit 512 decreases. The state in which the low pressure of the lowerorder circuit 512 decreases represents, for example, a case where the purpose for use of the load device 200 changes from a refrigeration purpose to a freezing purpose, and is correlated with a state in which the temperature in a cooling target space decreases. As illustrated in Part (c), when the low pressure of the lower-order circuit 512 decreases, the value on the vertical axis in the transition from 4 to 1 decreases, compared to Part (a). When the low pressure of the lower-order circuit 512 decreases, the temperature of refrigerant at the point denoted by 1, that is, the discharge temperature of the second compressor 111, increases.

[0035]

As described above, there is a tendency in which the discharge temperature of the first compressor 121 increases when the condensing temperature of the higherorder circuit 511 increases, whereas the discharge temperature of the second compressor 111 increases when the evaporating temperature of the lower-order circuit 512 decreases. At this time, the calculation unit 402 calculates the rotation frequency of the first compressor 121 in such a manner that the evaporating temperature of the higher-order circuit 511 and the condensing temperature of the lower-order circuit 512 are constant under any conditions, and the operation control unit 403 operates the first compressor 121 at the calculated rotation frequency. [0036]

Some or all of the amount of heat transmitted from the lower-order circuit 512 to the higher-order circuit 511 in the cascade heat exchanger 101 (transition from 2 to 3) is given to a heat medium in the second heat exchanger 113. Furthermore, some or all of the amount of heat subjected to heat exchange with air in the condenser 122 of the higher-order circuit 511 (transition from 6 to 7) is given to a heat medium in the first heat exchanger 124. As described above, in the refrigeration cycle system 500, the amount of heat is given from refrigerant to a heat medium in each of the first heat exchanger 124 and the second heat exchanger 113, so that exhausted heat can be recovered. To recover a large amount of exhausted heat, the amount of heat given to a heat medium in the transition from 2 to 3 or the transition from 6 to 7 is only required to be increased.

[0037]

Fig. 4 illustrates images of heat exchange between water and refrigerant in counter flow and parallel flow. Part (a) of Fig. 4 illustrates a heat exchange image for the case where refrigerant and a heat medium flow in counter directions. Part (b) of Fig. 4 illustrates a heat exchange image for the case where refrigerant and water flow in parallel directions. Furthermore, below each of the images, variations in the temperatures of refrigerant and a heat medium are illustrated. In both the Parts (a) and (b), the temperature of refrigerant is high at the inlet of a heat exchanger and decreases as closer to the outlet, whereas the temperature of a heat medium is low at the inlet of the heat exchanger and increases as closer to the outlet. However, a difference in temperature between refrigerant and a heat medium is substantially constant in the case of the counter flow illustrated in Part (a), whereas a difference in temperature between refrigerant and a heat medium is large on the inlet portion and small on the outlet portion in the case of the parallel flow illustrated in Part (b). Consequently, compared to the parallel flow illustrated in Part (b), heat of refrigerant can be transmitted to a heat medium efficiently in the case of the counter flow illustrated in Part (a).

[0038]

Fig. 5 is an image of heat exchange between water and refrigerant for a case where heat is sequentially exchanged through two refrigeration cycles. A heat medium is subjected to heat exchange with refrigerant A in a heat exchanger and then further subjected to heat exchange with refrigerant B in a different heat exchanger. Consequently, compared to a case where heat is exchanged with refrigerant in a single refrigeration cycle, a heat medium is supplied at a high hot water supply temperature. As illustrated in Fig. 5, in the case where the temperature of the refrigerant B at the inlet of the corresponding heat exchanger is higher than the temperature of the refrigerant A at the inlet of the corresponding heat exchanger, a large amount of heat can be supplied to a heat medium.

[0039]

Thus, to allow heat exchange between refrigerant and a heat medium in a heat exchanger and effectively obtain the amount of heat, the refrigerant and the heat medium are required to have a counter flow relationship as illustrated in Fig. 4. In addition, to obtain heat from two refrigeration cycles, the inlet temperature of the refrigerant B that is subjected to heat exchange later is required to be higher than the inlet temperature of the refrigerant A that is subjected to heat exchange earlier, as illustrated in Fig. 5.

[0040]

The higher-order circuit 511, the lower-order circuit 512, the exhausted heat recovery circuit 520, the pressure of refrigerant, changes in enthalpy, and a method for recovering exhausted heat have been explained above. Control with which the above features are taken into account will be explained below.

[0041]

Fig. 6 is a solenoid valve operation table for the refrigeration cycle system according to Embodiment 1. The operation control unit 403 acquires information on the first discharge temperature from the first discharge temperature sensor 127, information on the second discharge temperature from the second discharge temperature sensor 116, and information on the inlet temperature from the inlet temperature sensor 308. By referring to the memory unit 401, the operation control unit 403 also acquires control information on the solenoid valves 301 to 306 depending on the high-low relationship of the first discharge temperature, the second discharge temperature, and the inlet temperature, and opens and closes the solenoid valves 301 to 306 on the basis of the control information. As illustrated in Fig. 6, there are six patterns of the high-low relationship of the measured temperatures. Patterns a to f will be explained below. As described above, by referring to the memory unit 401, the operation control unit 403 causes the calculation unit 402 to calculate set values, and controls each of the rotation frequencies of the first compressor 121, the second compressor 111, the fan provided to the condenser 122, and other devices.

[0042]

In the pattern a, temperature decreases in the order of the first discharge temperature, the second discharge temperature, and the inlet temperature. In the case of the pattern a, the operation control unit 403 causes the flow switching device to achieve the second flow path state. That is, the solenoid valves 302, 304, and 306 are opened, and the other solenoid valves 301, 303, and 305 are closed. With such control, a heat medium that has entered the exhausted heat recovery device 300 first flows into the second heat exchanger 113 to be subjected to heat exchange with refrigerant, passes through the second branch pipe B2, flows into the first heat exchanger 124 to be subjected to heat exchange with refrigerant in the first heat exchanger 124, and exits the exhausted heat recovery device 300. [0043]

In the pattern b, temperature decreases in the order of the first discharge temperature, the inlet temperature, and the second discharge temperature. In the case of the pattern b, the operation control unit 403 causes the flow switching device to achieve the first bypass flow path state. That is, the solenoid valves 301 and 306 are opened, and the other solenoid valves 302 to 305 are closed. In the pattern b, the temperature of a heat medium flowing into the exhausted heat recovery device 300 is higher than the second discharge temperature. Consequently, when heat is exchanged with refrigerant in the lower-order circuit 512, the temperature of the heat medium decreases. Thus, the heat medium that has entered the exhausted heat recovery device 300 flows from the point P1 to the first heat exchanger 124, is subjected to heat exchange with refrigerant in the first heat exchanger 124, and then exits the exhausted heat recovery device 300.

[0044]

In the pattern c, temperature decreases in the order of the second discharge temperature, the first discharge temperature, and the inlet temperature. In the case of the pattern c, the operation control unit 403 causes the flow switching device to achieve the first flow path state. That is, the solenoid valves 301, 303, and 305 are opened, and the other solenoid valves 302, 304, and 306 are closed. With such control, a heat medium that has entered the exhausted heat recovery device 300 passes through the point P1, flows to the first heat exchanger 124, flows into the first heat exchanger 124 to be subjected to heat exchange with refrigerant. Subsequently, the heat medium passes through the first branch pipe B1, flows into the second heat exchanger 113, is subjected to heat exchange with refrigerant in the lower-order circuit 512, and exits the exhausted heat recovery device 300. [0045]

In the pattern d, temperature decreases in the order of the second discharge temperature, the inlet temperature, and the first discharge temperature. In the case of the pattern d, the operation control unit 403 causes the flow switching device to achieve the second bypass flow path state. That is, the solenoid valves 302 and 305 are opened, and the other solenoid valves 301, 303, 304, and 306 are closed. As in the pattern b, the temperature of a heat medium entering the exhausted heat recovery device 300 is higher than the first discharge temperature. Consequently, when heat is exchanged with refrigerant in the higher-order circuit 511, the temperature of the heat medium decreases. Thus, the heat medium that has entered the exhausted heat recovery device 300 flows into the second heat exchanger 113, is subjected to heat exchange with refrigerant in the lower-order circuit 512, then flows from the point P5 to the point P2, and exits the exhausted heat recovery device 300.

[0046]

In the pattern e, temperature decreases in the order of the inlet temperature, the first discharge temperature, and the second discharge temperature. Furthermore, in the pattern f, temperature decreases in the order of the inlet temperature, the second discharge temperature, and the first discharge temperature. In the case of the pattern e or the pattern f, the operation control unit 403 causes all the solenoid valves 301 to 306 in the exhausted heat recovery circuit 520 to be closed. That is, in the pattern e or the pattern f, the temperature of refrigerant is lower than the temperature of water, and exhausted heat cannot thus be recovered from the dual refrigeration cycle 510. Consequently, a configuration is provided in which the exhausted heat recovery circuit 520 is closed so that a heat medium does not flow to the first heat exchanger 124 or the second heat exchanger 113.

[0047]

As described above, in Embodiment 1, the refrigeration cycle system 500 includes the dual refrigeration cycle 510 that includes the higher-order circuit 511 in which the first compressor 121, the first heat exchanger 124, the condenser 122, the first expansion valve 123, and the cascade heat exchanger 101 are connected by refrigerant pipes, and the lower-order circuit 512 in which the second compressor 111, the second heat exchanger 113, the cascade heat exchanger 101, the second expansion valve 201, and the evaporator 202 are connected by refrigerant pipes, the lower-order circuit 512 allowing heat exchange with the higher-order circuit 511 in the cascade heat exchanger 101; and the exhausted heat recovery circuit 520 in which the first heat exchanger 124 and the second heat exchanger 113 are connected by pipes, a heat medium flowing in the exhausted heat recovery circuit 520. The 520 exhausted heat recovery circuit includes a first flow path that allows a heat medium to flow from the first heat exchanger 124 to the second heat exchanger 113, a second flow path that allows a heat medium to flow from the second heat exchanger 113 to the first heat exchanger 124, and a flow switching device that selects either one of the first flow path and the second flow path.

[0048]

With this configuration, the refrigeration cycle system 500 is able to switch which one of refrigerant in the higher-order circuit and refrigerant in the lower-order circuit a heat medium that has flowed into the exhausted heat recovery circuit 520 is to be first subjected to heat exchange with. Consequently, by switching the circuits depending on the operation state of the refrigeration apparatus, exhausted heat can be recovered efficiently. Furthermore, the amount of recovered heat is utilized through a heat medium, and energy saving can thus be achieved.

[0049]

Furthermore, the exhausted heat recovery circuit 520 also includes the first bypass flow path that allows a heat medium to flow to the first heat exchanger 124 and bypass the second heat exchanger 113, and the second bypass flow path that allows a heat medium to flow to the second heat exchanger 113 and bypass the first heat exchanger 124. The flow switching device selects one or more of the first flow path, the second flow path, the first bypass flow path, and the second bypass flow path.

[0050]

With this configuration, the exhausted heat recovery circuit 520 includes the first bypass flow path and the second bypass flow path that each allow a heat medium to pass a corresponding one of the heat exchangers, in addition to the two flow paths that allow heat exchange in different orders. Consequently, the refrigeration cycle system 500 is able to select a suitable flow path depending on the operation state or other conditions, and further efficient recovery of exhausted heat can be achieved.

[0051]

Furthermore, the refrigeration cycle system 500 further includes the first discharge temperature sensor 127 that measures the first discharge temperature of refrigerant discharged from the first compressor 121; the second discharge temperature sensor 116 that measures the second discharge temperature of refrigerant discharged from the second compressor 111; the inlet temperature sensor 308 that measures the inlet temperature of the heat medium that has flowed into the exhausted heat recovery circuit 520 and has not been subjected to heat exchange; and the controller 400 that controls the flow switching device on the basis of the inlet temperature measured by the inlet temperature sensor 308, the first discharge temperature measured by the first discharge temperature sensor 127, and the second discharge temperature measured by the second discharge temperature sensor 116. With this configuration, the refrigeration cycle system 500 is able to use, for selecting one or more of flow paths, information on the measured inlet temperature, the first discharge temperature, and the second discharge temperature, and efficient recovery of exhausted heat can thus be achieved.

[0052]

Furthermore, in the case where the inlet temperature is lower than the first discharge temperature and the second discharge temperature and the first discharge temperature is higher than the second discharge temperature, the controller 400 causes the flow switching device to select the second flow path. In the case where the inlet temperature is lower than the first discharge temperature and the second discharge temperature and the first discharge temperature is lower than the second discharge temperature, the controller 400 causes the flow switching device to select the first flow path.

[0053]

With this configuration, the controller 400 determines a case where heated water can be generated, and causes a heat medium to flow through a flow path with which exhausted heat can be recovered efficiently. Consequently, the refrigeration cycle system 500 is able to achieve a high hot water supply temperature. [0054]

Furthermore, in the case where the inlet temperature is lower than the first discharge temperature and higher than the second discharge temperature, the controller 400 causes the flow switching device to select the first bypass flow path. In the case where the inlet temperature is higher than the first discharge temperature and lower than the second discharge temperature, the controller 400 causes the flow switching device to select the second bypass flow path. With this configuration, the controller 400 determines a case where heated water can be generated, and is able to cause a heat medium to flow only to a heat exchanger that is able to recover exhausted heat.

[0055]

Furthermore, the flow switching device includes the plurality of solenoid valves 301 to 306 for opening and closing flow paths. With this configuration, a plurality of flow paths can each be selected by a combination of opening and closing states of the plurality of solenoid valves 301 to 306.

[0056]

Furthermore, in at least one of the first heat exchanger 124 and the second heat exchanger 113 that is provided downstream, a heat medium and refrigerant flow in counter directions. In Embodiment 1, pipes are connected in such a manner that refrigerant and a heat medium flow in counter directions in both the first heat exchanger 124 and the second heat exchanger 113. Consequently, as illustrated in Fig. 5, the refrigeration cycle system 500 can achieve a high hot water supply temperature, compared to a case where refrigerant and a heat medium flow in parallel directions.

[0057]

Embodiment 2

Fig. 7 is a circuit diagram of a refrigeration cycle system according to Embodiment 2. The basic configuration of the dual refrigeration cycle 510 is the same as that in Fig. 1, and parts having the same configuration will be referred to with the same reference signs, and explanation for these parts will be omitted. In Embodiment 1, the flow switching device includes the plurality of solenoid valves 301 to 306. In Embodiment 2, a case where the flow switching device includes a fourway valve 309 and flow paths for a heat medium are controlled in a simplified manner will be explained. The four-way valve 309 is mounted in the exhausted heat recovery device 300, and the connection state of ports is controlled by the controller 400. Specifically, the controller 400 switches settings of the four-way valve 309 depending on the high-low relationship of the measured first discharge temperature of the higher-order circuit 511 and the measured second discharge temperature of the lower-order circuit 512.

[0058]

The four-way valve 309 is provided at pipes of a circuit, ports of the four-way valve 309 are each connected to a corresponding one of a circuit inlet, the first heat exchanger 124, the second heat exchanger 113, and a circuit outlet. In the first heat exchanger 124, the inlet portion of refrigerant is connected to the four-way valve 309 of the exhausted heat recovery circuit 520 via a pipe, and the outlet portion of refrigerant is connected to the second heat exchanger via a pipe. Furthermore, in the second heat exchanger, the inlet portion of refrigerant is connected to the fourway valve 309 of the exhausted heat recovery circuit 520 via a pipe, and the outlet portion of refrigerant is connected to the first heat exchanger via a pipe. With such a circuit configuration, as in Embodiment 1, the exhausted heat recovery circuit 520 is able to include the first flow path and the second flow path separated by the four-way valve 309 and select either one of the first flow path and the second flow path. [0059]

In the case where the first discharge temperature is higher than the second discharge temperature, the operation control unit 403 causes the four-way valve 309 to achieve the second flow path state. That is, as indicated by broken arrows in Fig. 7, a heat medium that has entered the exhausted heat recovery circuit 520 through the circuit inlet is first subjected to heat exchange with refrigerant in the second heat exchanger 113, and then subjected to heat exchange with refrigerant in the first heat exchanger 124. Subsequently, the heat medium passes through the circuit outlet, and exits the exhausted heat recovery circuit 520. At this time, in the second heat exchanger 113 in which heat is exchanged first, refrigerant and a heat medium flow in parallel directions. Consequently, compared to the circuit configuration in Embodiment 1, the recovery efficiency of heat exchange decreases. However, because the heat medium first passes through the second heat exchanger 113, there is still a large temperature difference between refrigerant and the heat medium, and a reduction in the recovery efficiency of exhausted heat can be reduced. Furthermore, in the first heat exchanger 124, refrigerant and a heat medium flow in counter directions. Consequently, the exhausted heat recovery circuit 520 is able to recover exhausted heat efficiently from the higher-order circuit 511.

[0060]

In contrast, in the case where the first discharge temperature is lower than the second discharge temperature, the operation control unit 403 causes the four-way valve 309 to achieve the first flow path state. That is, as illustrated in solid arrows in Fig. 7, a heat medium that has entered the exhausted heat recovery circuit 520 through the circuit inlet is first subjected to heat exchange with refrigerant in the first heat exchanger 124, and then subjected to heat exchange with refrigerant in the second heat exchanger 113. Subsequently, the heat medium passes through the circuit outlet and exits the exhausted heat recovery circuit 520. At this time, refrigerant and the heat medium flow in parallel directions in the first heat exchanger 124 where heat is exchanged first, and refrigerant and the heat medium flow in counter directions in the second heat exchanger 113 where heat is exchanged next. [0061]

In the case where both the first discharge temperature and the second discharge temperature are lower than the inlet temperature of a heat medium, exhausted heat cannot be recovered. Consequently, as in Embodiment 1, the operation control unit 403 may further acquire information on the inlet temperature from the inlet temperature sensor 308, and in the case where the inlet temperature is higher than both the first discharge temperature and the second discharge temperature, for example, the operation control unit 403 may stop the operation of the sending device 320. Furthermore, the flow switching device may include a plurality of four-way valves or other devices. The plurality of four-way valves may be configured to select one or more of the first flow path, the second flow path, the first bypass flow path, and the second bypass flow path, as in Embodiment 1.

[0062]

As described above, in Embodiment 2, the refrigeration cycle system 500 includes the dual refrigeration cycle 510 that includes the higher-order circuit 511 and the lower-order circuit 512; and the exhausted heat recovery circuit 520 that includes the first flow path, the second flow path, and the flow switching device. With this configuration, as in Embodiment 1, the refrigeration cycle system 500 is able to switch which one of refrigerant in the higher-order circuit and refrigerant in the lower-order circuit a heat medium that has flowed into the exhausted heat recovery circuit 520 is to be first subjected to heat exchange with. Consequently, by switching the circuits depending on the operation state of the refrigeration apparatus, exhausted heat can be recovered efficiently. Furthermore, the amount of recovered heat is utilized through a heat medium, and energy saving can thus be achieved.

[0063]

Furthermore, the flow switching device includes the four-way valve 309. With this configuration, with the use of the four-way valve 309 instead of the six solenoid valves 301 to 306, recovery of exhausted heat can be achieved inexpensively and efficiently.

[0064]

Furthermore, the refrigeration cycle system 500 further includes the sending device 320 that supplies the heat medium to the exhausted heat recovery circuit 520. With this configuration, even in the case where flow paths for a heat medium are separated by the single four-way valve 309, control of supply of a heat medium to the exhausted heat recovery circuit 520 can also be achieved, in addition to selection between the first flow path and the second flow path.

[0065]

Furthermore, the refrigeration cycle system 500 further includes the controller

400 that causes the operation of the sending device 320 to stop in the case where the inlet temperature measured by the inlet temperature sensor 308 is higher than the first discharge temperature measured by the first discharge temperature sensor 127 and the second discharge temperature measured by the second discharge temperature sensor 116.

[0066]

With this configuration, even with the circuit including the four-way valve 309, for example, corresponding to the patterns e and f in Embodiment 1, supply of a heat medium to the exhausted heat recovery circuit 520 can be stopped, so that a decrease in the temperature of the heat medium can be avoided.

[0067]

Furthermore, a heat medium and refrigerant flow in counter directions in at least one of the first heat exchanger 124 and the second heat exchanger 113 that is provided downstream.

[0068]

With this configuration, a heat medium and refrigerant flow in counter directions in a heat exchanger through which a heat medium passes later. Consequently, even in the case where there is a small difference in temperature between the heat medium and the refrigerant, efficient heat exchange can be achieved. In the case where the four-way valve 309 is used, a heat medium and refrigerant flow in parallel directions in a heat exchanger in which heat is exchanged first. Consequently, although the heat exchange rate is lower than that in the configuration of Embodiment 1, there is still a large difference in temperature between the refrigerant and the heat medium in a heat exchanger through which a heat medium passes earlier, and a reduction in the exhausted heat recovery efficiency can be reduced.

[0069] Embodiment 3

Fig. 8 is a circuit diagram of a refrigeration cycle system according to

Embodiment 3. In Fig. 8, the basic configuration of the exhausted heat recovery device 300 and the load device 200 is the same as that in Fig. 1. In Fig. 8, a modification of the circuit configuration of the heat source unit 100 is illustrated.

Parts having the same configuration as those in Fig. 1 will be referred to with the same reference signs, and explanation for these parts will be omitted.

[0070]

First, the circuit configuration of the dual refrigeration cycle 510 according to Embodiment 3 will be explained. The higher-order circuit 511 further includes a first bypass circuit C1 to bypass the condenser 122. The first bypass circuit C1 branches off from a refrigerant pipe between the first heat exchanger 124 and the condenser 122 and meets a refrigerant pipe between the condenser 122 and the first expansion valve 123. A solenoid valve 128a is provided at the refrigerant pipe of the first bypass circuit C1, and the solenoid valve 128a opens and closes a flow path that allows a heat medium to flow in the first bypass circuit C1. Furthermore, a solenoid valve 128b is provided at a refrigerant pipe of a main circuit of the higher-order circuit including the condenser 122 and between a point from which the first bypass circuit C1 branches off and a point at which the first bypass circuit C1 meets the main circuit. The solenoid valve 128b opens and closes a flow path that allows a heat medium to flow in the condenser 122. During a normal operation, the solenoid valve 128a is closed, and the solenoid valve 128b is opened, so that a heat medium passes through the condenser 122.

[0071]

Furthermore, in the lower-order circuit 512, an air-heat exchanger 112 that allows heat exchange between air and refrigerant is connected between the second heat exchanger 113 and the cascade heat exchanger 101. The lower-order circuit 512 further includes a second bypass circuit C2 that bypasses the air-heat exchanger 112. The second bypass circuit C2 branches off from a refrigerant pipe between the second heat exchanger and the air-heat exchanger 112 and meets a refrigerant pipe between the air-heat exchanger 112 and the cascade heat exchanger 101. A solenoid valve 117a is provided at the refrigerant pipe of the second bypass circuit C2, and the solenoid valve 117a opens and closes a flow path that allows a heat medium to flow in the second bypass circuit C2. Furthermore, a solenoid valve 117b is provided at a refrigerant pipe of a main circuit of the lower-order circuit including the air-heat exchanger 112 and between a point from which the second bypass circuit C2 branches off and a point at which the second bypass circuit C2 meets the main circuit. The solenoid valve 117b opens and closes a flow path that allows a heat medium to flow in the air-heat exchanger 112. During a normal operation, the solenoid valve 117a is closed, and the solenoid valve 117b is opened, so that a heat medium passes through the air-heat exchanger 112.

[0072]

Furthermore, the sensor group further includes a first refrigerant temperature sensor 129, a second refrigerant temperature sensor 118, and an outside air temperature sensor 130. The first refrigerant temperature sensor 129 is placed at a position where the first bypass circuit C1 and the refrigerant pipe connected to the outlet portion of the condenser 122 meet again, and measures the temperature of refrigerant at its installed position (first refrigerant temperature). The second refrigerant temperature sensor 118 is placed at a position where the second bypass circuit C2 and the refrigerant pipe connected to the outlet portion of the air-heat exchanger 112 meet again, and measures the temperature of refrigerant at its installed position (second refrigerant temperature). The outside air temperature sensor 130 may be placed at any position. However, for example, the outside air temperature sensor 130 is installed at the condenser 122 to measure the outside air temperature.

[0073]

The solenoid valves 128a and 128b of the higher-order circuit 511, the solenoid valves 117a and 117b of the lower-order circuit 512, the first refrigerant temperature sensor 129, the second refrigerant temperature sensor 118, and the outside air temperature sensor 130 are each connected to the controller 400 in such a manner that they can each communicate with the controller 400. The controller 400 further acquires the first refrigerant temperature, the second refrigerant temperature, the outside air temperature, and other types of information, and controls the flow of refrigerant by opening and closing each of the solenoid valves 128a, 128b, 117a, and 117b on the basis of the acquired temperature information.

[0074]

An operation of the refrigeration cycle system 500 according to Embodiment 3 will be explained. In the higher-order circuit 511, when the amount of heat exchange between refrigerant and a heat medium at the first heat exchanger 124 increases, the amount of heat exchange at the condenser 122 decreases. The amount of heat exchange at the first heat exchanger 124 depends on, for example, the size of the first heat exchanger 124, the inlet temperature of a heat medium, and other factors. In the case where the amount of heat exchange at the first heat exchanger 124 is large, refrigerant flowing in the higher-order circuit 511 condenses inside the first heat exchanger 124. At this time, the amount of heat exchange required at the condenser 122 decreases, and consequently, the controller 400 reduces the rotation frequency of the fan provided to the condenser 122 or stops the operation of the fan in the case where heat exchange at the condenser 122 is completely unnecessary. At the condenser 122, the refrigerant condenses into a liquid state or a two-phase state of liquid and gas. The density of liquid refrigerant is higher than that of gas refrigerant. Consequently, in the liquid state or the two-phase state, the amount of refrigerant remaining in the condenser 122 increases. In contrast, the higher-order circuit 511 is a closed circuit with a uniform amount of refrigerant. Consequently, in spite of almost no amount of heat exchange at the condenser 122, the amount of refrigerant remaining in the condenser 122 increases, and there may be a shortage of refrigerant in the higher-order circuit 511.

[0075]

In the case where refrigerant condenses at the first heat exchanger 124 and almost no heat is exchanged in the condenser 122, the controller 400 causes refrigerant to flow to the first bypass circuit C1 and bypass the condenser 122. With this operation, a shortage of refrigerant in the higher-order circuit 511 can be resolved.

[0076]

To determine whether or not refrigerant condenses at the first heat exchanger

124, the controller 400 acquires information on the outside air temperature from the outside air temperature sensor 130 and the first refrigerant temperature from the first refrigerant temperature sensor 129. Normally, in a state in which heat is exchanged between refrigerant and air in the condenser 122, the first refrigerant temperature is always equal to or higher than the temperature of air. Consequently, for example, in the case where the acquired first refrigerant temperature is lower than the outside air temperature, that is, in the case where the temperature of refrigerant exiting the condenser 122 is decreased to the outside air temperature or below, the controller 400 determines that the refrigerant condenses at the first heat exchanger 124. In the case where it is determined that refrigerant condenses, the operation control unit 403 opens the solenoid valve 128a and closes the solenoid valve 128b, so that the refrigerant is allowed to flow to the first bypass circuit C1. In contrast, in the case where refrigerant does not condense, the operation control unit 403 closes the solenoid valve 128a and opens the solenoid valve 128b, as in a normal operation, so that the refrigerant is allowed to flow to the condenser 122. In the case where the first refrigerant temperature is lower than the outside air temperature by an amount corresponding to a set temperature amount (for example, 3 degrees Celsius), the controller 400 may determine that refrigerant condenses at the first heat exchanger 124.

[0077]

Furthermore, when the outside air temperature is higher than the water temperature at the inlet of the exhausted heat recovery device 300, the condensing temperature of the higher-order circuit 511 for the case where a large amount of heat is exchanged at the first heat exchanger 124 is lower than that for the case where refrigerant is subjected to heat exchange only at the condenser 122. Consequently, the entire power consumption of the refrigeration cycle system 500 can be decreased. Furthermore, as illustrated in the P-H diagram of Fig. 3, when the amount of heat exchange at the first heat exchanger 124 is large, a large amount of heat can be supplied to a heat medium in the transition from 6 to 7. Consequently, the amount of recoverable exhausted heat can be increased.

[0078]

In contrast, the air-heat exchanger 112 is provided in the lower-order circuit 512, and heat is exchanged between refrigerant and air at the air-heat exchanger 112. Consequently, the amount of heat exchanged between the higher-order circuit 511 and the lower-order circuit 512 can be reduced in the cascade heat exchanger 101. However, for example, when the temperature of a heat medium is lower than the outside air temperature, the temperature of refrigerant can be decreased more by allowing heat exchange only at the second heat exchanger 113 than by allowing heat exchange between refrigerant and air at the air-heat exchanger 112.

[0079]

The controller 400 determines whether or not the temperature of a heat medium is lower than the outside air temperature. In the case where the temperature of a heat medium is lower than the outside air temperature, the controller 400 causes the refrigerant to flow to the second bypass circuit C2 and bypass the airheat exchanger 112, so that an increase in the temperature of the refrigerant can be avoided.

[0080]

Specifically, as with the higher-order circuit 511, the controller 400 acquires the outside air temperature from the outside air temperature sensor 130 and the second refrigerant temperature from the second refrigerant temperature sensor 118. Next, for example, by comparing the acquired outside air temperature with the acquired second refrigerant temperature, the controller 400 determines whether or not the temperature of a heat medium is lower than the outside air temperature. In the case where the second refrigerant temperature is lower than the outside air temperature, the operation control unit 403 opens the solenoid valve 117a and closes the solenoid valve 117b. At this time, the refrigerant flows to the second bypass circuit C2 and bypasses the air-heat exchanger 112. In contrast, in the case where the second refrigerant temperature is higher than the outside air temperature, the operation control unit 403 closes the solenoid valve 117a and opens the solenoid valve 117b, as in the normal operation. At this time, the refrigerant flows to the air-heat exchanger 112. In the case where the second refrigerant temperature is lower than the outside air temperature by an amount corresponding to a set temperature amount (for example, 3 degrees Celsius), the controller 400 may determine that the temperature of a heat medium is lower than the outside air temperature.

[0081]

As described above, in Embodiment 3, the refrigeration cycle system 500 includes the dual refrigeration cycle 510 that includes the higher-order circuit 511 and the lower-order circuit 512; and the exhausted heat recovery circuit 520 that includes the first flow path, the second flow path, and the flow switching device. With this configuration, as in Embodiment 1, the refrigeration cycle system 500 is able to switch which one of refrigerant in the higher-order circuit and refrigerant in the lower-order circuit a heat medium that has flowed into the exhausted heat recovery circuit 520 is to be first subjected to heat exchange with. Consequently, by switching the circuits depending on the operation state of the refrigeration apparatus, exhausted heat can be recovered efficiently. Furthermore, the amount of recovered heat is utilized through a heat medium, and energy saving can thus be achieved.

[0082]

Furthermore, the higher-order circuit 511 includes the first bypass circuit C1 to bypass the condenser 122. With this configuration, refrigerant in the higher-order circuit 511 that has exited the first heat exchanger 124 is allowed to flow bypassing the condenser 122 without being subjected to heat exchange at the condenser 122. [0083]

Furthermore, the refrigeration cycle system 500 further includes the outside air temperature sensor 130 that measures outside air temperature; the first refrigerant temperature sensor 129 that is provided to a position where the first bypass circuit C1 and the outlet portion of the condenser 122 meet, the first refrigerant temperature sensor 129 measuring the first refrigerant temperature; and the controller 400 that causes refrigerant to bypass the condenser 122 and flow to the first bypass circuit C1 in the case where the first refrigerant temperature measured by the first refrigerant temperature sensor 129 is lower than the outside air temperature measured by the outside air temperature sensor 130.

[0084]

With this configuration, in the case where refrigerant condenses at the first heat exchanger 124 and almost no heat is exchanged at the condenser 122, the controller 400 is able to reduce the amount of refrigerant remaining in the condenser 122, by causing the refrigerant to flow to the first bypass circuit C1. Consequently, a shortage of the amount of circulating refrigerant is resolved, the power consumption can be reduced by the closed circuit, and efficient recovery of exhausted heat can be achieved.

[0085]

Furthermore, the lower-order circuit 512 further includes the air-heat exchanger 112 connected between the second heat exchanger 113 and the cascade heat exchanger 101, and the air-heat exchanger 112 allows heat exchange between air and the refrigerant. With this configuration, heat of the refrigerant is removed in the air-heat exchanger 112, and consequently, the amount of heat subjected to heat exchange with the refrigerant in the higher-order circuit and the refrigerant in the lower-order circuit refrigerant in the cascade heat exchanger 101 is reduced.

[0086]

Furthermore, the lower-order circuit 512 includes the second bypass circuit C2 to bypass the air-heat exchanger 112. With this configuration, the refrigerant in the lower-order circuit 512 that has exited the second heat exchanger 113 is allowed to flow bypassing the air-heat exchanger 112 without being subjected to heat exchange at the air-heat exchanger 112.

[0087]

Furthermore, the refrigeration cycle system 500 further includes the outside air temperature sensor 130 that measures outside air temperature; the second refrigerant temperature sensor 118 that is provided to a position where the second bypass circuit C2 and the outlet portion of the air-heat exchanger 112 meet and measures the second refrigerant temperature; and the controller 400 that causes refrigerant to bypass the air-heat exchanger 112 and flow to the second bypass circuit C2 in the case where the second refrigerant temperature measured by the second refrigerant temperature sensor 118 is lower than the outside air temperature measured by the outside air temperature sensor 130.

[0088]

With this configuration, for example, in the case where the outside air temperature is high, refrigerant is subjected to heat exchange only at the second heat exchanger 113. Consequently, reception of heat from the outside air with high temperature and a resultant increase in the temperature of the refrigerant can be avoided. Consequently, also with a configuration in which the air-heat exchanger 112 is added, the function of the refrigeration apparatus is prioritized, and efficient recovery of exhausted heat can be achieved.

[0089]

Embodiment 4

Fig. 9 is a circuit diagram of a refrigeration cycle system according to Embodiment 4. In Fig. 9, the basic configuration of the exhausted heat recovery device 300 and the load device 200 is the same as that in Fig. 1. However, in Embodiment 4, a circuit for reducing power consumption and increasing the amount of recovered exhausted heat, and other components are added to the heat source unit 100. Parts having the same configuration as those in Fig. 1 will be referred to with the same reference signs, and explanation for these parts will be omitted. [0090]

In the lower-order circuit 512, a third heat exchanger 102 is connected between the evaporator 202 and the second compressor 111. The third heat exchanger 102 allows heat exchange between liquid refrigerant that has exited the condenser 122 of the higher-order circuit 511 and gas refrigerant that is to enter the second compressor 111 of the lower-order circuit 512.

[0091]

Furthermore, the dual refrigeration cycle 510 includes a branch circuit C3 that branches off from a refrigerant pipe connected to the outlet portion of the condenser

122, passes through the third heat exchanger 102, and meets a refrigerant pipe between the outlet portion of the condenser 122 and the first expansion valve 123.

Furthermore, a solenoid valve 131a is provided at a refrigerant pipe between the condenser 122 and the first expansion valve 123, and the solenoid valve 131a opens and closes a flow path that allows refrigerant to flow through the outlet of the condenser 122 to the first expansion valve 123. A solenoid valve 131 b is provided at the branch circuit C3, and the solenoid valve 131b opens and closes a flow path that allows refrigerant in a high-pressure portion of the refrigeration cycle to flow to the branch circuit C3. During a normal operation, the solenoid valve 131a is opened, and the solenoid valve 131b is closed, so that the refrigerant flows in the main circuit of the higher-order circuit.

[0092]

The sensor group further includes a third refrigerant temperature sensor 132 and a suction temperature sensor 119. The third refrigerant temperature sensor 132 is provided to the outlet portion of the condenser 122 and measures the temperature of refrigerant at its installed position (third refrigerant temperature). The suction temperature sensor 119 is provided between the third heat exchanger 102 and the second compressor 111 and measures the suction temperature of refrigerant to be sucked into the second compressor.

[0093]

The solenoid valves 131a and 131b, the third refrigerant temperature sensor 132, and the suction temperature sensor 119 are connected to the controller 400 in such a manner that they can each communicate with the controller 400. [0094]

Control performed by the controller 400 will be explained. The controller 400 first acquires information on the third refrigerant temperature from the third refrigerant temperature sensor 132 and information on the suction temperature of the second compressor 111 from the suction temperature sensor 119. Next, the controller 400 determines whether or not the acquired third refrigerant temperature is higher than the suction temperature. In the case where it is determined that the third refrigerant temperature is higher than the suction temperature, the controller 400 closes the solenoid valve 131a, and opens the solenoid valve 131b, so that refrigerant that has flowed out of the condenser 122 is allowed to flow to the branch circuit C3. At this time, the refrigerant that has flowed into the branch circuit C3 is subjected to heat exchange at the third heat exchanger 102. Subsequently, the refrigerant returns to the main circuit of the higher-order circuit, and flows to the refrigerant pipe at which the first expansion valve 123 is provided.

[0095]

When the refrigerant in the higher-order circuit 511 passes through the branch circuit C3, the suction temperature of the second compressor 111 in the lower-order circuit 512 increases, and the temperature of the refrigerant in the condenser 122 of the higher-order circuit 511 decreases. Furthermore, when the suction temperature of the lower-order circuit 512 increases, the discharge temperature of the second compressor 111 of the lower-order circuit 512 also increases.

[0096]

As described above, in Embodiment 4, the refrigeration cycle system 500 includes the dual refrigeration cycle 510 that includes the higher-order circuit 511 and the lower-order circuit 512; and the exhausted heat recovery circuit 520 that includes the first flow path, the second flow path, and the flow switching device. With this configuration, as in Embodiment 1, the refrigeration cycle system 500 is able to switch which one of refrigerant in the higher-order circuit and refrigerant in the lower-order circuit a heat medium that has flowed into the exhausted heat recovery circuit 520 is to be first subjected to heat exchange with. Consequently, by switching the circuits depending on the operation state of the refrigeration apparatus, exhausted heat can be recovered efficiently. Furthermore, the amount of recovered heat is utilized through a heat medium, and energy saving can thus be achieved.

[0097]

Furthermore, the lower-order circuit 512 further includes the third heat exchanger 102 connected between the evaporator 202 and the second compressor 111, and the third heat exchanger 102 allows heat exchange between the refrigerant in the higher-order circuit 511 and the refrigerant in the lower-order circuit 512. The dual refrigeration cycle 510 further includes the branch circuit C3 that branches off from a refrigerant pipe connected to the outlet portion of the condenser 122, passes through the third heat exchanger 102, and meets a refrigerant pipe between the outlet portion of the condenser 122 and the first expansion valve 123.

[0098]

With this configuration, the refrigerant in the higher-order circuit 511 that has exited the condenser 122 flows to the branch circuit C3, and the suction temperature of the lower-order circuit 512 increases. Furthermore, together with the increase in the suction temperature, the second discharge temperature of the lower-order circuit 512 increases, and the amount of recovered exhausted heat thus increases. [0099]

Furthermore, the refrigeration cycle system 500 further includes the third refrigerant temperature sensor 132 that measures the third refrigerant temperature at the outlet portion of the condenser 122; the suction temperature sensor 119 that measures the suction temperature of the refrigerant to be sucked into the second compressor 111; and the controller 400 that causes the refrigerant that has flowed out of the condenser 122 to flow to the branch circuit C3 in the case where the third refrigerant temperature measured by the third refrigerant temperature sensor 132 is higher than the suction temperature measured by the suction temperature sensor 119.

[0100]

With this configuration, the controller 400 is able to cause refrigerant to flow to the branch circuit C3, so that the suction temperature of the lower-order circuit 512 can be increased, and the temperature of the refrigerant in the higher-order circuit 511 can be affected by the degree of subcooling. The suction temperature of the second compressor 111 is typically higher than the evaporating temperature by about 5 degrees Celsius to 10 degrees Celsius, and the degree of superheat is ensured. However, even in the case where the lower-order circuit 512 is in a liquid back state for some reason, causing the refrigerant in the higher-order circuit to flow to the branch circuit C3 increases the suction temperature, and inflow of liquid refrigerant to the second compressor 111 is reduced. For example, in the case where the temperature of the refrigerant is about the same as the evaporating temperature and the degree of superheat is not ensured, the branch circuit C3 can avoid breakdown of the second compressor 111. In contrast, the liquid refrigerant at the higher-order circuit 511 is cooled down, and the degree of subcooling of the refrigerant that is to enter the first expansion valve 123 increases. When the degree of subcooling of the refrigerant that is to enter the first expansion valve 123 increases, the point denoted by 7 in Fig. 3 is shifted to the left. Consequently, a difference in the enthalpy between inlet and outlet of the cascade heat exchanger 101, that is, the length of the transition from 8 to 5 in Fig. 3, increases, and the refrigeration capacity is thus improved. With this configuration, the refrigeration cycle system 500 is able to reduce the rotation frequency of the first compressor 121, and power consumption can thus be reduced.

[0101]

Embodiments of the present invention are not limited to the foregoing embodiments, and various changes may be made to the present invention. For example, a case where a heat medium is water has been explained above. However, brine or other types of liquid may be used as a heat medium. Furthermore, a case where refrigerant in the higher-order circuit 511 and the lowerorder circuit 512 is R744 (CO2) has been explained above. However, refrigerant of other types may be used. For example, HFC or HFO refrigerant may be used. [0102]

Furthermore, in the patterns e and f, the controller 400 performs control in such a manner that all of the plurality of solenoid valves 301 to 306 are closed so that a heat medium does not flow to the exhausted heat recovery circuit 520. However, instead of closing the plurality of solenoid valves 301 to 306, the operation of the sending device 320 may be stopped.

[0103]

Furthermore, for example, in Fig. 1, a state in which the heat source unit 100, the exhausted heat recovery device 300, and the controller 400 are accommodated in different casings is illustrated. However, the heat source unit 100, the exhausted heat recovery device 300, and the controller 400 may be accommodated in the same casing.

[0104]

Furthermore, a case where the outside air temperature sensor 130 is provided to the condenser 122 of the higher-order circuit 511 has been explained above. However, the outside air temperature sensor 130 may be placed at any place as long as the outside air temperature sensor 130 is able to measure the outside air temperature correctly. Furthermore, each of the condenser 122 and the air-heat exchanger 112 includes a bypass circuit. However, only one of the condenser 122 and the air-heat exchanger 112 may include a bypass circuit. Furthermore, the controller 400 may select one or more of flow paths using a single three-way valve, in place of the two solenoid valves 128a and 128b. Furthermore, in a similar manner, a single three-way valve may be substituted for the two solenoid valves 117a and 117b of the lower-order circuit 512.

Reference Signs List [0105]

100: heat source unit, 101: cascade heat exchanger, 102: third heat exchanger, 111: second compressor, 112: air-heat exchanger, 113: second heat exchanger, 114: pressure sensor, 115: pressure sensor, 116: second discharge temperature sensor, 117a, 117b: solenoid valve, 118: second refrigerant temperature sensor, 119: suction temperature sensor, 121: first compressor, 122: condenser, 123: first expansion valve, 124: first heat exchanger, 125: pressure sensor, 126: pressure sensor, 127: first discharge temperature sensor, 128a, 128b: solenoid valve, 129: first refrigerant temperature sensor, 130: outside air temperature sensor, 131a, 131b: solenoid valve, 132: third refrigerant temperature sensor, 200: load device, 201: second expansion valve, 202: evaporator, 300: exhausted heat recovery device, 301 to 306: solenoid valve, 307: outlet temperature sensor, 308: inlet temperature sensor, 309: four-way valve, 320: sending device, 400: controller, 401: memory unit, 402: calculation unit, 403: operation control unit, 500: refrigeration cycle system, 510: dual refrigeration cycle, 511: higher-order circuit, 512: lower-order circuit, 520: exhausted heat recovery circuit, B1: first branch pipe, B2: second branch pipe, C1: first bypass circuit, C2: second bypass circuit, C3: branch circuit, P1 to P6: point

Claims

CLAIMS [Claim 1]

A refrigeration cycle system comprising:

a dual refrigeration cycle including a higher-order circuit in which a first compressor, a first heat exchanger, a condenser, a first expansion valve, and a cascade heat exchanger are connected by refrigerant pipes, and a lower-order circuit in which a second compressor, a second heat exchanger, the cascade heat exchanger, a second expansion valve, and an evaporator are connected by refrigerant pipes, the lower-order circuit allowing heat exchange with the higher-order circuit in the cascade heat exchanger; and an exhausted heat recovery circuit in which the first heat exchanger and the second heat exchanger are connected by pipes, a heat medium flowing in the exhausted heat recovery circuit, the exhausted heat recovery circuit including a first flow path allowing the heat medium to flow from the first heat exchanger to the second heat exchanger, a second flow path allowing the heat medium to flow from the second heat exchanger to the first heat exchanger, and a flow switching device configured to select either one of the first flow path and the second flow path.
[Claim 2]

The refrigeration cycle system of claim 1, wherein the exhausted heat recovery circuit further includes a first bypass flow path allowing the heat medium to flow to the first heat exchanger and bypass the second heat exchanger, and a second bypass flow path allowing the heat medium to flow to the second heat exchanger and bypass the first heat exchanger, and wherein the flow switching device is configured to select one or more of the first flow path, the second flow path, the first bypass flow path, and the second bypass flow path.
[Claim 3]

The refrigeration cycle system of claim 1 or 2, further comprising:

a first discharge temperature sensor configured to measure a first discharge temperature of refrigerant discharged from the first compressor;

a second discharge temperature sensor configured to measure a second discharge temperature of refrigerant discharged from the second compressor;

an inlet temperature sensor configured to measure an inlet temperature of the heat medium having flowed into the exhausted heat recovery circuit and has not been subjected to heat exchange; and a controller configured to control the flow switching device on a basis of the inlet temperature measured by the inlet temperature sensor, the first discharge temperature measured by the first discharge temperature sensor, and the second discharge temperature measured by the second discharge temperature sensor. [Claim 4]

The refrigeration cycle system of claim 3, wherein, in a case where the inlet temperature is lower than the first discharge temperature and the second discharge temperature and the first discharge temperature is higher than the second discharge temperature, the controller is configured to cause the flow switching device to select the second flow path, and wherein, in a case where the inlet temperature is lower than the first discharge temperature and the second discharge temperature and the first discharge temperature is lower than the second discharge temperature, the controller is configured to cause the flow switching device to select the first flow path.

[Claim 5]

The refrigeration cycle system of claim 3 as dependent on claim 2 or of claim 4 as dependent on claim 2, wherein, in a case where the inlet temperature is lower than the first discharge temperature and higher than the second discharge temperature, the controller is configured to cause the flow switching device to select the first bypass flow path, and wherein, in a case where the inlet temperature is higher than the first discharge temperature and lower than the second discharge temperature, the controller is configured to cause the flow switching device to select the second bypass flow path. [Claim 6]

The refrigeration cycle system of any one of claims 1 to 5, wherein the flow switching device includes a plurality of solenoid valves each configured to open and close a corresponding one of flow paths.

[Claim 7]

The refrigeration cycle system of any one of claims 1 to 5, wherein the flow switching device includes a four-way valve.

[Claim 8]

The refrigeration cycle system of any one of claims 1 to 7, wherein the higherorder circuit includes a first bypass circuit to bypass the condenser.

[Claim 9]

The refrigeration cycle system of claim 8, further comprising:

an outside air temperature sensor configured to measure an outside air temperature;

a first refrigerant temperature sensor provided to a position where the first bypass circuit and an outlet portion of the condenser meet, the first refrigerant temperature sensor being configured to measure a first refrigerant temperature; and a controller configured to cause the refrigerant to bypass the condenser and flow to the first bypass circuit in a case where the first refrigerant temperature measured by the first refrigerant temperature sensor is lower than the outside air temperature measured by the outside air temperature sensor.

[Claim 10]

The refrigeration cycle system of any one of claims 1 to 9, wherein the lowerorder circuit further includes an air-heat exchanger connected between the second heat exchanger and the cascade heat exchanger, the air-heat exchanger allowing heat exchange between air and the refrigerant.

[Claim 11]

The refrigeration cycle system of claim 10, wherein the lower-order circuit includes a second bypass circuit to bypass the air-heat exchanger.

[Claim 12]

The refrigeration cycle system of claim 11, further comprising:

an outside air temperature sensor configured to measure an outside air temperature;

a second refrigerant temperature sensor provided to a position where the second bypass circuit and an outlet portion of the air-heat exchanger meet, the second refrigerant temperature sensor being configured to measure a second refrigerant temperature; and a controller configured to cause the refrigerant to bypass the air-heat exchanger and flow to the second bypass circuit in a case where the second refrigerant temperature measured by the second refrigerant temperature sensor is lower than the outside air temperature measured by the outside air temperature sensor.

[Claim 13]

The refrigeration cycle system of any one of claims 1 to 12, wherein the lower-order circuit further includes a third heat exchanger connected between the evaporator and the second compressor, the third heat exchanger allowing heat exchange between the refrigerant in the higher-order circuit and the refrigerant in the lower-order circuit, and wherein the dual refrigeration cycle further includes a branch circuit branching off from a refrigerant pipe connected to an outlet portion of the condenser, passing through the third heat exchanger, and meeting a refrigerant pipe between the outlet portion of the condenser and the first expansion valve.

[Claim 14]

The refrigeration cycle system of claim 13, further comprising:

a third refrigerant temperature sensor configured to measure a third refrigerant temperature at the outlet portion of the condenser;

a suction temperature sensor configured to measure a suction temperature of the refrigerant to be sucked into the second compressor; and a controller configured to cause the refrigerant having flowed out of the condenser to flow to the branch circuit in a case where the third refrigerant temperature measured by the third refrigerant temperature sensor is higher than the suction temperature measured by the suction temperature sensor.

[Claim 15]

The refrigeration cycle system of any one of claims 1 to 14, further comprising a sending device configured to supply the heat medium to the exhausted heat recovery circuit.

[Claim 16]

The refrigeration cycle system of claim 15 as dependent on claim 3, further comprising a controller configured to cause an operation of the sending device to stop in a case where the inlet temperature measured by the inlet temperature sensor is higher than the first discharge temperature measured by the first discharge temperature sensor and the second discharge temperature measured by the second discharge temperature sensor.

[Claim 17]

The refrigeration cycle system of any one of claims 1 to 16, wherein, in at least one of the first heat exchanger and the second heat exchanger that is provided downstream, the heat medium and the refrigerant flow in counter directions.