Patent Publication Number: US-2022221202-A1

Title: Heat treatment system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of PCT International Application No. PCT/JP2020/036997, filed on Sep. 29, 2020, which claims priority under 35 U.S.C. 119(a) to Patent Application No. 2019-180815, filed in Japan on Sep. 30, 2019, all of which are hereby expressly incorporated by reference into the present application. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a heat treatment system. 
     BACKGROUND ART 
     As a heat treatment system in the related art, there is a two-stage refrigeration apparatus including a high-temperature side (primary) refrigeration cycle and a low-temperature side (secondary) refrigeration cycle. For example, Patent Document 1 (Japanese Patent Laying Open No. 11-173725) discloses a showcase refrigeration apparatus including an outdoor unit, a cascade unit, and a showcase refrigeration unit. 
     SUMMARY 
     A heat treatment system according to a first aspect includes load side cycles heat-source side cycle and load side cycles load side cycle. The heat-source side cycle and the load side cycle share a cascade heat exchanger. A total number of the heat-source side cycle and the load side cycle is three or more. A first cycle circulates a first refrigerant or heat medium. A second cycle circulates a second refrigerant or heat medium. A third cycle circulates a third refrigerant or heat medium. The first refrigerant or heat medium, the second refrigerant or heat medium, and the third refrigerant or heat medium are different from one another. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration diagram of a heat treatment system according to a first embodiment of the present disclosure. 
         FIG. 2  is a schematic configuration diagram of a heat treatment system according to a second embodiment of the present disclosure. 
         FIG. 3  is a schematic configuration diagram of a heat treatment system according to a third embodiment of the present disclosure. 
         FIG. 4  is a schematic configuration diagram of a heat treatment system according to a fourth embodiment of the present disclosure. 
         FIG. 5  is a schematic configuration diagram of a heat treatment system according to a fifth embodiment of the present disclosure. 
         FIG. 6  is a schematic configuration diagram of a heat treatment system according to a modification of the fifth embodiment of the present disclosure. 
         FIG. 7  is a schematic configuration diagram of a heat treatment system according to a sixth embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A heat treatment system according to an embodiment of the present disclosure will be described with reference to the drawings. 
     (1) First Embodiment 
     (1-1) Overall Configuration 
     A heat treatment system  1  according to one embodiment of the present disclosure includes one or more heat-source side cycles and one or more load side cycles. A total number of the heat-source side cycles and the load side cycles is three or more. The heat-source side cycle is a cycle that generates heat to be supplied to the load side cycle. The load side cycle is a cycle to which the heat required depending on the application is supplied from the heat-source side cycle. 
     As illustrated in  FIG. 1 , the heat treatment system  1  includes a first cycle C 1 , a second cycle C 2 , and a third cycle C 3 . Here, the first cycle C 1  is a heat-source side cycle, and the second and third cycles C 2  and C 3  are load side cycles. The heat-source side cycle and the load side cycle share a first cascade heat exchanger  41  and a second cascade heat exchanger  42 . 
     (1-2) Detailed Configuration 
     (1-2-1) First Cycle 
     The first cycle C 1  circulates a first refrigerant or heat medium. In the present embodiment, the first cycle C 1  is a cycle that circulates the first refrigerant. Specifically, the first cycle C 1  is a vapor-compression refrigeration cycle. The first cycle C 1  is a high-stage refrigeration cycle on a high-temperature side and here is used for an outdoor unit of an air conditioner. A high-pressure refrigerant, here for example R32, is used as the first refrigerant. 
     In the first cycle C 1 , a first compressor  11 , a first condenser  12 , a first expansion valve  13 , an upstream first evaporator  14 , and a downstream second evaporator  15  are sequentially coupled with a refrigerant pipe to form a refrigerant circuit. 
     The first compressor  11  suctions the first refrigerant flowing through the first cycle C 1 , compresses the suctioned first refrigerant into a high-temperature and high-pressure gas refrigerant, and discharges the gas refrigerant. In the present embodiment, the first compressor  11  is a type of compressor that controls the number of rotations using an inverter circuit so as to adjust the discharge amount of the refrigerant. 
     The first condenser  12  exchanges heat between, for example, air or brine and the first refrigerant flowing through the first cycle to condense and liquefy the refrigerant. In the present embodiment, the first condenser  12  exchanges heat between the outside air and the first refrigerant. 
     The first expansion valve  13  is, for example, an electronic expansion valve that decompresses and expands the first refrigerant flowing through the first cycle. 
     The first evaporator  14  evaporates the first refrigerant flowing through the first cycle C 1  by heat exchange. In the present embodiment, the first evaporator  14  includes, for example, a heat transfer tube that passes the first refrigerant flowing through the first cycle C 1  in the first cascade heat exchanger  41 . In the first cascade heat exchanger  41 , heat is exchanged between the first refrigerant flowing through the first evaporator  14  and a second refrigerant flowing through the second cycle C 2 . 
     The first evaporator  15  evaporates the first refrigerant flowing through the first cycle by heat exchange. In the present embodiment, the first evaporator  15  includes, for example, a heat transfer tube that passes the first refrigerant flowing through the first cycle C 1  in the second cascade heat exchanger  42 . In the second cascade heat exchanger  42 , heat is exchanged between the first refrigerant flowing through the first evaporator  14  and a third heat medium flowing through the third cycle C 3 . 
     The heat-source side cycle, which is the first cycle C 1 , is disposed outdoors. For example, a part of the first cycle may be disposed outdoors, but here the entire first cycle C 1  is disposed outdoors. The heat-source side cycle disposed outdoors may use a refrigerant having an RCL smaller than R410A. The refrigerant having an RCL smaller than 410A is, for example, R32. 
     The RCL is a concentration limit in air in consideration of a safety factor and is an index for the purpose of reducing risks of acute toxicity, asphyxiation, and flammability in a confined space where persons are present. The RCL is determined based on ISO 817. Specifically, the RCL is the smallest value among the acute-toxicity exposure limit (ATEL), the oxygen deprivation limit (ODL), and the flammable concentration limit (FCL). 
     (1-2-2) Second Cycle 
     The second cycle C 2  circulates the second refrigerant or heat medium. In the present embodiment, the second cycle C 2  is a cycle that circulates the second refrigerant. Specifically, the second cycle C 2  is a low-stage refrigeration cycle on a low-temperature side and here is used for an indoor unit of an air conditioner. The second refrigerant is different from the first refrigerant. For example, R1234ze is used as the second refrigerant. 
     In the second cycle C 2 , a second expansion valve  21 , a second evaporator  22 , a second compressor  27 , and a second condenser  23  are sequentially coupled with a refrigerant pipe to form a refrigerant circuit. 
     The second expansion valve  21  is, for example, an electronic expansion valve that decompresses and expands the second refrigerant flowing through the second cycle C 2 . 
     The second evaporator  22  evaporates the second refrigerant flowing through the second cycle by heat exchange. In the present embodiment, the second evaporator  22  exchanges heat between the indoor air and the second refrigerant. 
     The second compressor  27  suctions the second refrigerant flowing through the second cycle C 2 , compresses the suctioned second refrigerant into a high-temperature and high-pressure gas refrigerant, and discharges the gas refrigerant. 
     The second condenser  23  condenses the second refrigerant flowing through the second cycle by heat exchange. In the present embodiment, the second condenser  23  includes for example a heat transfer tube that passes the second refrigerant flowing through the second cycle in the first cascade heat exchanger  41 . 
     (1-2-3) Third Cycle 
     The third cycle C 3  circulates the third refrigerant or heat medium. In the present embodiment, the third cycle C 3  is a cycle that circulates the third heat medium. Specifically, the third cycle C 3  is a low-stage refrigeration cycle on a low-temperature side and here is used for a showcase incorporating a showcase freezer unit or refrigerator unit. The third heat medium is different from the first refrigerant and the second refrigerant. For example, CO 2  is used as the third heat medium. 
     In the third cycle C 3 , a third compressor  31 , a third condenser  32 , a third expansion valve  33 , and a third evaporator  34  are sequentially coupled with a pipe to form a heat medium circuit. 
     The third compressor  31  suctions the third heat medium flowing through the third cycle C 3 , compresses the suctioned third heat medium into a high-temperature and high-pressure gas medium, and discharges the gas medium. In the present embodiment, the third compressor  31  is a type of compressor that controls the number of rotations using an inverter circuit so as to adjust the discharge amount of another medium. 
     The third condenser  32  condenses the third heat medium flowing through the third cycle by heat exchange. In the present embodiment, the third condenser  32  includes for example a heat transfer tube that passes the third heat medium flowing through the third cycle C 3  in the second cascade heat exchanger  42 . 
     The third expansion valve  33  is, for example, an electronic expansion valve that decompresses and expands the third heat medium flowing through the third cycle C 3 . 
     The third evaporator  34  evaporates the third heat medium flowing through the third cycle by heat exchange. In the present embodiment, the third evaporator  34  exchanges heat by freezing or refrigerating the inside of the showcase. 
     (1-2-4) Cascade Heat Exchanger 
     The first cycle C 1  and the second cycle C 2  share the first cascade heat exchanger  41 . The first cascade heat exchanger  41  has an integrated combination of the first evaporator  14  and the second condenser  23 . The first cascade heat exchanger  41  exchanges heat between the first refrigerant flowing through the first evaporator  14  and the second refrigerant flowing through the second condenser  23 . 
     The first cycle C 1  and the third cycle C 3  share the second cascade heat exchanger  42 . The second cascade heat exchanger  42  has an integrated combination of the first evaporator and the third condenser  32 . The second cascade heat exchanger  42  exchanges heat between the first refrigerant flowing through the first evaporator  15  and the third heat medium flowing through the third condenser  32 . 
     The first cascade heat exchanger  41  and the second cascade heat exchanger  42  are connected in series. 
     (1-3) Operation of Heat Treatment System 
     Next, an operation of the heat treatment system  1  will be described. 
     First, in the first cycle C 1 , the first refrigerant discharged from the first compressor  11  flows into the first condenser  12  and radiates heat to the outside air and condenses in the first condenser  12 . After the first refrigerant is expanded in the first expansion valve  13 , the first refrigerant absorbs heat from the second refrigerant and evaporates in the first evaporator  14  of the first cascade heat exchanger  41  and further absorbs heat from the third heat medium and evaporates in the first evaporator  15  of the second cascade heat exchanger  42 . Then, the first refrigerant is suctioned into the first compressor  11 . In the first cycle C 1 , the first refrigerant circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process. 
     In the second cycle C 2 , the second refrigerant radiates heat to the first refrigerant and condenses in the second condenser  23  of the first cascade heat exchanger  41 . After the second refrigerant is expanded in the second expansion valve  21 , the second refrigerant absorbs heat from the indoor air and evaporates in the second evaporator  22  and thus cools the indoor air. Then, after the second refrigerant is compressed by the second compressor  27 , the second refrigerant flows into the second condenser  23 . The second refrigerant circulates as described above to repeat a condensation process, an expansion process, an evaporation process, and a compression process and thus cool the inside of the room. 
     In the third cycle C 3 , the third heat medium discharged from the third compressor  31  flows into the third condenser  32  of the second cascade heat exchanger  42  and radiates heat to the first refrigerant and condenses. After the third heat medium is expanded in the third expansion valve  33 , the third heat medium absorbs heat from the showcase and evaporates in the third evaporator  34  to freeze or refrigerate the inside of the showcase. Then, the third heat medium is suctioned into the third compressor  31 . In the third cycle C 3 , the third heat medium circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process and thus freeze or refrigerate the showcase. 
     In the present embodiment, the first cycle C 1  serving as the heat-source side cycle uses a medium-pressure refrigerant or a low-pressure refrigerant having a high critical temperature. The refrigerant in the heat-source side cycle exchanges heat with the second refrigerant in the second cycle C 2  serving as an air cooling cycle and the third heat medium in the third cycle C 3  serving as a freezer cycle or a refrigerator cycle. 
     The above-described “medium-pressure refrigerant” has a condensation temperature of 25° C. and a pressure of more than 0.8 MPa and equal to or less than 1.3 MPa. The above-described “low-pressure refrigerant” has a condensation temperature of 25° C. and a pressure of more than 0.08 MPa and equal to or less than 0.8 MPa. 
     (1-4) Feature 
     In the heat treatment system  1  according to the present embodiment, the first refrigerant or heat medium circulating through the first cycle C 1 , the second refrigerant or heat medium circulating through the second cycle C 2 , and the third refrigerant or heat medium circulating through the third cycle C 3  are different from one another. Three or more media are used in three or more cycles, and therefore an appropriate medium may be used depending on the application of the load side cycle. Here, the first and second cycles C 1  and C 2  use the first and second refrigerants suitable for an air conditioner, and the third cycle C 3  uses the third heat medium suitable for a freezer or refrigerator. 
     In the heat treatment system  1  according to the present embodiment, at least one of the first to third cycles includes a cycle that circulates a refrigerant. The cycle that circulates the refrigerant is a vapor-compression refrigerant cycle. In the heat treatment system  1  according to the present embodiment, a refrigerant for a vapor-compression refrigeration cycle may be used as the refrigerant. 
     In the heat treatment system  1  according to the present embodiment, the heat-source side cycle is disposed outdoors. The heat-source side cycle disposed outdoors uses a refrigerant having an RCL smaller than R410A. 
     In the heat treatment system  1  according to the present embodiment, the heat-source side cycle using the refrigerant having a low RCL is disposed outdoors so that the restriction on the refrigerant to be used may be reduced. Therefore, an appropriate refrigerant may be used in the heat-source side cycle. 
     The above-described “refrigerant concentration limit (RCL)” is defined by ISO 817 (Refrigerants Designation and safety classification). Specifically, the RCL is the smallest value among the acute-toxicity exposure limit (ATEL), the oxygen deprivation limit (ODL), and the flammable concentration limit (FCL). 
     In the heat treatment system  1  according to the present embodiment, the load side cycle includes at least one of a cooling cycle, a freezer cycle, and a refrigerator cycle. The heat-source side cycle uses a medium-pressure refrigerant or a low-pressure refrigerant. 
     In the heat treatment system  1  according to the present embodiment, the heat-source side cycle may use the medium-pressure refrigerant or the low-pressure refrigerant having a high critical temperature. Heat may be exchanged between the refrigerant in the heat-source side cycle and the refrigerant or heat medium in at least one of the cooling cycle, the freezer cycle, and the refrigerator cycle. 
     (1-5) Modification of First Embodiment 
     In the above-described embodiment, the first refrigerant circulates through the first cycle C 1 , the second refrigerant circulates through the second cycle C 2 , and the third heat medium circulates through the third cycle C 3 , but this is not a limitation. For example, different refrigerants may circulate in all of the first to third cycles C 1  to C 3 , or different heat media may circulate in all of the first to third cycles C 1  to C 3 . According to the present modification, a third refrigerant circulates through the third cycle C 3 . Here, a freezer cycle or a refrigerator cycle serving as the third cycle C 3  uses a high-pressure refrigerant as the third refrigerant. The high-pressure refrigerant is, for example, CO 2 . 
     The above-described “high-pressure refrigerant” has a condensation temperature of 25° C. and a pressure of more than 1.3 MPa. 
     According to the present modification, the load side cycle includes at least one of the freezer cycle and the refrigerator cycle, and the freezer cycle and the refrigerator cycle use a high-pressure refrigerant. As the freezer cycle and the refrigerator cycle use a high-pressure refrigerant having a high density in a low-temperature area, a suitable refrigerant may be used depending on a low-temperature application of the third cycle C 3  that is a load side unit. 
     (2) Second Embodiment 
     (2-1) Overall Configuration 
     As illustrated in  FIG. 2 , in a heat treatment system  2  according to the present embodiment, the first cycle C 1  is a low-stage refrigeration cycle on a low-temperature side, and the second and third cycles C 2  and C 3  are high-stage refrigeration cycles on a high-temperature side. Specifically, the first cycle C 1  is a heat-source side cycle forming an outdoor unit of an air conditioner. The second cycle C 2  is an air heating cycle forming an indoor unit of the air conditioner. The third cycle C 3  is a hot-water supply cycle. 
     (2-2) Detailed Configuration 
     In the first cycle C 1 , the first compressor  11 , the upstream first condenser  12 , a downstream first condenser  16 , the first expansion valve  13 , and the first evaporator  14  are sequentially coupled with a refrigerant pipe to form a refrigerant circuit. The first refrigerant circulating through the first cycle C 1 , the first compressor  11 , and the first expansion valve  13  are the same as those in the first embodiment described above. 
     The first condensers  12  and  16  condense the first refrigerant flowing through the first cycle by heat exchange. The upstream first condenser  12  includes, for example, a heat transfer tube that passes the first refrigerant flowing through the first cycle in the first cascade heat exchanger  41 . The downstream first condenser  16  includes, for example, a heat transfer tube that passes the second refrigerant flowing through the second cycle in the second cascade heat exchanger  42 . 
     The first evaporator  14  exchanges heat between, for example, air, brine, or the like and the first refrigerant flowing through the first cycle to evaporate the refrigerant. In the present embodiment, the first evaporator  14  exchanges heat between the outside air and the first refrigerant. 
     In the second cycle C 2 , the second evaporator  22 , the second compressor  27 , the second condenser  23 , and the second expansion valve  21  are sequentially coupled with a refrigerant pipe to form a refrigerant circuit. The second cycle serving as an air heating cycle uses a medium-pressure refrigerant or a low-pressure refrigerant. The medium-pressure refrigerant is, for example, R1234ze(E). The low-pressure refrigerant is, for example, R1234ze(Z). 
     The second evaporator  22  evaporates the second refrigerant flowing through the second cycle C 2  by heat exchange with the first refrigerant. It includes a heat transfer tube that passes the second refrigerant flowing through the second cycle C 2  in the first cascade heat exchanger  41 . 
     The second condenser  23  condenses the second refrigerant flowing through the second cycle C 2  by heat exchange with the indoor air. 
     The third cycle C 3  is a hot water circuit for hot-water supply to generate hot water from water. The third cycle C 3  is a cycle that uses sensible heat in a liquid phase. The heat medium using sensible heat is, for example, water, brine, or the like and here water is used as the third heat medium. 
     In the third cycle C 3 , a circulating pump  35 , a heat absorption unit  36 , and a hot water storage tank  37  are sequentially coupled with a pipe to form a circuit. In the third cycle C 3 , water or hot water circulates so that hot water heated by the heat absorption unit  36  of the second cascade heat exchanger  42  is stored in the hot water storage tank  37 . In order to supply and discharge water to and from the hot water storage tank  37 , the hot water circuit for hot-water supply is coupled to a water supply pipe to the hot water storage tank  37  and a hot water discharge pipe from the hot water storage tank  37 . 
     (2-3) Operation of Heat Treatment System 
     First, in the first cycle C 1 , the first refrigerant discharged from the first compressor  11  radiates heat from the second refrigerant and condenses in the upstream first condenser  12  of the first cascade heat exchanger  41  and further radiates heat from the third heat medium and condenses in the downstream first condenser  16  of the second cascade heat exchanger  42 . Then, after the first refrigerant is expanded in the first expansion valve  13 , the first refrigerant absorbs heat from the outside air and evaporates in the first evaporator  14 . In the first cycle C 1 , the first refrigerant circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process. 
     In the second cycle C 2 , the second refrigerant absorbs heat to the first refrigerant and evaporates in the second evaporator  22  of the first cascade heat exchanger  41 . After the second refrigerant is compressed by the second compressor  27 , the second refrigerant radiates heat from the indoor air and condenses in the second condenser  23  and thus heats the indoor air. Then, after the second refrigerant is expanded in the second expansion valve  21 , the second refrigerant flows into the second evaporator  22 . The second refrigerant circulates as described above to repeat a condensation process, a compression process, an evaporation process, and an expansion process and thus heat the inside of the room. 
     In the third cycle C 3 , the water in the hot water storage tank  37  is supplied by the circulating pump  35  to the heat absorption unit  36  of the second cascade heat exchanger  42 , and the water is heated by absorption of heat from the first refrigerant. The hot water generated by heating returns to the hot water storage tank  37 , and the hot water continuously circulates through the third cycle C 3  until a predetermined heat storage temperature is obtained. 
     (2-4) Feature 
     According to the present embodiment, the air heating cycle and the hot-water supply cycle used for high-temperature applications are applied to the load side cycles. The air heating cycle, which is the second cycle C 2 , uses a medium-pressure refrigerant or a low-pressure refrigerant. As a medium-pressure refrigerant and a low-pressure refrigerant have a high critical temperature, an appropriate medium is used depending on a high-temperature application of the load side cycle according to the present embodiment. 
     In the heat treatment system  2  according to the present embodiment, at least one of the first to third cycles includes a cycle that circulates a heat medium. The cycle that circulates the heat medium is a cycle using sensible heat in a liquid phase. 
     In the heat treatment system  2  according to the present embodiment, the heat medium using sensible heat may be used as the heat medium. 
     (2-5) Modification of Second Embodiment 
     According to the embodiment described above, water is used as a heat medium in the hot-water supply cycle, but this is not a limitation. For example, the load side cycle may include at least one of the air heating cycle and the hot-water supply cycle, and the air heating cycle and the hot-water supply cycle may use a medium-pressure refrigerant or a low-pressure refrigerant. 
     In the heat treatment system according to modification of second embodiment, the medium-pressure refrigerant or the low-pressure refrigerant having a high critical temperature may be used for the heating cycle and the hot-water supply cycle. Therefore, an appropriate refrigerant may be used depending on a high-temperature application of the load side unit. 
     (3) Third Embodiment 
     (3-1) Overall Configuration 
     As illustrated in  FIG. 3 , in a heat treatment system  3  according to the present embodiment, the first cycle C 1  is a high-stage refrigeration cycle on a high-temperature side with respect to the second cycle C 2  and is a low-stage refrigeration cycle on a low-temperature side with respect to the third cycle C 3 . Specifically, the first cycle C 1  is a heat-source side cycle forming an outdoor unit of an air conditioner. The second cycle C 2  is a hot-water supply cycle. The third cycle C 3  is a freezer or refrigerator cycle. 
     (3-2) Detailed Configuration 
     In the first cycle C 1 , the first compressor  11 , the first condenser  12 , an additional expansion valve  17 , an upstream first evaporator  18 , the first expansion valve  13 , and the downstream first evaporator  14  are sequentially coupled with a refrigerant pipe to form a refrigerant circuit. The first refrigerant circulating through the first cycle C 1 , the first compressor  11 , and the first expansion valve  13  are the same as those in the first embodiment described above. 
     The first condenser  12  condenses the first refrigerant flowing through the first cycle C 1  by heat exchange with the second heat medium in the first cascade heat exchanger  41 . The first condenser  12  includes, for example, a heat transfer tube that passes the first refrigerant flowing through the first cycle C 1  in the first cascade heat exchanger  41 . 
     The additional expansion valve  17  is, for example, an electronic expansion valve that decompresses and expands the first refrigerant condensed by the first condenser  12 . 
     The first evaporator  18  evaporates the first refrigerant flowing through the first cycle C 1  by heat exchange with the third heat medium in the second cascade heat exchanger  42 . The first evaporator  18  includes, for example, a heat transfer tube that passes the first refrigerant flowing through the first cycle C 1  in the second cascade heat exchanger  42 . 
     The second cycle C 2  is substantially the same as the third cycle C 3  according to the second embodiment. Specifically, the circulating pump  35 , the heat absorption unit  36 , and the hot water storage tank  37  are coupled in the second cycle C 2 . The heat absorption unit  36  includes, for example, a heat transfer tube that passes the second heat medium flowing through the second cycle C 2  in the first cascade heat exchanger  41 . In the second cycle C 2 , water or hot water circulates so that the hot water heated by the heat absorption unit  36  of the first cascade heat exchanger  41  is stored in the hot water storage tank  37 . 
     The third cycle C 3  is the same as the third cycle C 3  according to the first embodiment. 
     (3-3) Operation of Heat Treatment System 
     First, in the first cycle C 1 , the first refrigerant discharged from the compressor  11  radiates heat from the second refrigerant and condenses in the first condenser  12  of the first cascade heat exchanger  41 . Then, after the first refrigerant is expanded in the additional expansion valve  17 , the first refrigerant absorbs heat from the third heat medium and evaporates in the first condenser  16  of the second cascade heat exchanger  42 . Then, after the first refrigerant is expanded in the first expansion valve  13 , the first refrigerant absorbs heat from the outside air and evaporates in the first evaporator  14 . In the first cycle C 1 , the first refrigerant circulates as described above to repeat a compression process, a condensation process, an expansion process, an evaporation process, an expansion process, and an evaporation process. 
     In the second cycle C 2 , the water in the hot water storage tank  37  is supplied by the circulating pump  35  to the heat absorption unit  36  of the first cascade heat exchanger  41 , and the water is heated by absorption of heat from the first refrigerant. The hot water generated by heating returns to the hot water storage tank  37 , and the hot water continuously circulates through the second cycle C 2  until a predetermined heat storage temperature is obtained. 
     In the third cycle C 3 , the third heat medium discharged from the third compressor  31  flows into the third condenser  32  of the second cascade heat exchanger  42  and radiates heat to the first refrigerant and condenses. After the third heat medium is expanded in the third expansion valve  33 , the third heat medium absorbs heat from the showcase and evaporates in the third evaporator  34  to freeze or refrigerate the inside of the showcase. Then, the third heat medium is suctioned into the third compressor  31 . In the third cycle C 3 , the third heat medium circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process and thus freeze or refrigerate the showcase. 
     (3-4) Feature 
     According to the present embodiment, the cycle used for a high-temperature application and the cycle used for a low-temperature application are applied to the load side cycles. As the first refrigerant or heat medium, the second refrigerant or heat medium, and the third refrigerant or heat medium are different from one another, an appropriate medium may be used depending on the application of each load side cycle. 
     (4) Fourth Embodiment 
     (4-1) Overall Configuration 
     As illustrated in  FIG. 4 , a heat treatment system  4  according to the present embodiment includes a plurality of heat-source side cycles. Specifically, the first and second cycles C 1  and C 2  are heat-source side cycles, and the third cycle C 3  is a load side cycle. Specifically, the first cycle C 1  is a heat-source side cycle forming an outdoor unit of an air conditioner. The second cycle C 2  is a heat-source side cycle using solar heat. The third cycle C 3  is a hot-water supply cycle. 
     (4-2) Detailed Configuration 
     In the first cycle C 1 , the first compressor  11 , the first condenser  12 , the first expansion valve  13 , and the first evaporator  14  are sequentially coupled with a refrigerant pipe to form a refrigerant circuit. The first cycle C 1  according to the fourth embodiment is different from the first cycle C 1  according to the second embodiment in that the downstream first condenser  16  is omitted. Similarly, the first cycle C 1  according to the fourth embodiment is different from the first cycle C 1  according to the third embodiment in that the upstream first evaporator  18  is omitted. 
     In the second cycle C 2 , a circulating pump  51 , a solar heat panel  52 , and a heat radiation unit  53  are coupled. In the second cycle C 2 , the second heat medium heated by the solar heat panel  52  circulates so as to radiate heat in the heat radiation unit  53  of the first cascade heat exchanger  41 . In the second cycle C 2 , for example, CO 2  circulates as the second heat medium. 
     In the third cycle C 3 , the circulating pump  35 , an upstream heat absorption unit  36 , a downstream heat absorption unit  38 , and the hot water storage tank  37  are coupled. In the third cycle C 3 , water or hot water circulates so that the hot water heated by the upstream heat absorption unit  36  of the second cascade heat exchanger  42  and further heated by the downstream heat absorption unit  38  of the first cascade heat exchanger  41  is stored in the hot water storage tank  37 . 
     The first cycle C 1  and the third cycle C 2  share the first cascade heat exchanger  41 . The second cycle C 2  and the third cycle C 3  share the second cascade heat exchanger  42 . 
     (4-3) Operation of Heat Treatment System 
     First, in the first cycle C 1 , the first refrigerant discharged from the compressor  11  radiates heat from the third heat medium and condenses in the first condenser  12  of the first cascade heat exchanger  41 . Then, after the first refrigerant is expanded in the first expansion valve  13 , the first refrigerant absorbs heat from the outside air and evaporates in the first evaporator  14 . In the first cycle C 1 , the first refrigerant circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process. 
     In the second cycle C 2 , the second heat medium heated by the solar heat panel  52  is supplied by the circulating pump  51  to the heat radiation unit  53  of the second cascade heat exchanger  42  and is cooled as the heat is absorbed by the third heat medium. The cooled second heat medium continuously circulates through the second cycle C 2 . 
     In the third cycle C 3 , the water in the hot water storage tank  37  is supplied by the circulating pump  35  to the heat absorption unit  36  of the second cascade heat exchanger  42  and is heated by absorption of heat from the second heat medium. Then, the heated water is supplied to the heat absorption unit  38  of the first cascade heat exchanger  41  and is further heated by absorption of heat from the first heat medium. The hot water generated by heating at two stages returns to the hot water storage tank  37 , and the hot water continuously circulates through the third cycle C 3  until a predetermined heat storage temperature is obtained. 
     (4-4) Feature 
     According to the present embodiment, the first and second cycles C 1  and C 2  are heat-source side cycles, and the first refrigerant or heat medium and the second refrigerant or heat medium are different from each other. Thus, the heat exchanger effectiveness on the heat source side may be improved. 
     (4-5) Modification of Fourth Embodiment 
     In an example described according to the above embodiment, the second cycle C 2  is a cycle where CO 2  circulates as a heat medium, but this is not a limitation. In the present modification, the cycle where the heat medium circulates is a cycle using sensible heat and latent heat. The heat medium using sensible heat and latent heat is, for example, fluorocarbon water (a mixed liquid of fluorocarbon and water). 
     In the heat treatment system according to modification of fourth embodiment, the heat medium using sensible heat and latent heat may be used as the heat medium. 
     (5) Fifth Embodiment 
     (5-1) Overall Configuration 
     As illustrated in  FIG. 5 , a heat treatment system  5  according to a fifth embodiment further includes a cascade unit  40  in the above-described first embodiment. Therefore, the heat treatment system  5  in the present embodiment primarily includes the first cycle C 1 , the second cycle C 2 , the third cycle C 3 , and the cascade unit  40 . 
     The cascade unit  40  includes a secondary cycle where a secondary medium circulates through the first cascade heat exchanger  41 , a third cascade heat exchanger  43 , and the second cascade heat exchanger  42  by a circulating pump  46 . For example, the secondary medium circulating through the secondary cycle may be the same as or different from the first refrigerant or heat medium, the second refrigerant or heat medium, or the third refrigerant or heat medium. 
     (5-2) Detailed Configuration 
     The first cycle C 1  includes the first cascade heat exchanger  41 . The evaporator  14  of the first cycle C 1  evaporates the first refrigerant by heat exchange with the secondary medium flowing through the first cascade heat exchanger  41 . 
     The second cycle C 2  includes the second cascade heat exchanger  42 . The second condenser  23  of the second cycle C 2  condenses the second refrigerant by heat exchange with the secondary medium flowing through the second cascade heat exchanger  42 . 
     The third cycle C 3  includes the third cascade heat exchanger  43 . The condenser  32  of the third cycle C 3  condenses the third refrigerant by heat exchange with the secondary medium flowing through the third cascade heat exchanger  43 . 
     The first cascade heat exchanger  41  includes a heat absorption unit  41   a  and a heat radiation unit  41   b . The heat absorption unit  41   a  is the first evaporator  14  of the first cycle C 1 . In the heat radiation unit  41   b , the secondary medium circulating through the secondary cycle of the cascade unit  40  radiates heat to the first refrigerant. In the first cascade heat exchanger  41 , the first cycle C 1  including the heat absorption unit  41   a  is a heat-source side cycle, and the secondary cycle including the heat radiation unit  41   b  is a load side cycle. 
     The second cascade heat exchanger  42  includes a heat absorption unit  42   a  and a heat radiation unit  42   b . In the heat absorption unit  42   a , the secondary medium circulating through the secondary cycle absorbs heat from the second refrigerant. The heat radiation unit  42   b  is the second condenser  23  of the second cycle C 2 . In the second cascade heat exchanger  42 , the secondary cycle including the heat absorption unit  42   a  is a heat-source side cycle, and the second cycle C 2  including the heat radiation unit  42   b  is a load side cycle. 
     The third cascade heat exchanger  43  includes a heat absorption unit  43   a  and a heat radiation unit  43   b . In the heat absorption unit  43   a , the secondary medium circulating through the secondary cycle absorbs heat from the third heat medium. The heat radiation unit  43   b  is the third condenser  32  of the third cycle C 3 . In the third cascade heat exchanger  43 , the secondary cycle including the heat absorption unit  43   a  is a heat-source side cycle, and the third cycle C 3  including the heat radiation unit  43   b  is a load side cycle. 
     At least a part of the cascade unit  40  is disposed outdoors. Here, at least a portion forming the heat-source side cycle in the cascade unit  40  is disposed outdoors. In the present embodiment, the entire first cascade unit  40  is disposed outdoors. 
     (5-3) Operation of Heat Treatment System 
     In the first cycle C 1 , the first refrigerant discharged from the first compressor  11  flows into the first condenser  12  and radiates heat to the outside air and condenses in the first condenser  12 . After the first refrigerant is expanded in the first expansion valve  13 , the first refrigerant absorbs heat from the secondary medium and evaporates in the first evaporator  14  of the first cascade heat exchanger  41 . Then, the first refrigerant is suctioned into the first compressor  11 . In the first cycle C 1 , the first refrigerant circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process. 
     In the secondary cycle of the cascade unit  40 , the secondary medium radiates heat to the first refrigerant to be cooled in the heat radiation unit  41   b  of the first cascade heat exchanger  41 . The secondary medium absorbs heat from the second refrigerant to be heated in the heat absorption unit  43   a  of the third cascade heat exchanger  43 . Further, the secondary medium absorbs heat from the third heat medium to be heated in the heat absorption unit  42   a  of the second cascade heat exchanger  42 . The heated secondary medium flows into the heat radiation unit  41   b  of the first cascade heat exchanger  41 . In the secondary cycle, the secondary medium circulates as described above to repeat a cooling process and a heating process. 
     In the second cycle C 2 , the second refrigerant radiates heat to the secondary medium and condenses in the second condenser  23  of the second cascade heat exchanger  42 . After the second refrigerant is expanded in the second expansion valve  21 , the second refrigerant absorbs heat from the indoor air and evaporates in the second evaporator  22  and thus cools the indoor air. Then, the second refrigerant flows into the second condenser  23 . The second refrigerant circulates as described above to repeat a condensation process, an expansion process, and an evaporation process and thus cool the inside of the room. 
     In the third cycle C 3 , the third heat medium discharged from the third compressor  31  flows into the third condenser  32  of the third cascade heat exchanger  43  and radiates heat to the secondary medium and condenses. After the third heat medium is expanded in the third expansion valve  33 , the third heat medium absorbs heat from the showcase and evaporates in the third evaporator  34  to freeze or refrigerate the inside of the showcase. Then, the third heat medium is suctioned into the third compressor  31 . In the third cycle C 3 , the third heat medium circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process and thus freeze or refrigerate the showcase. 
     (5-4) Feature 
     The heat treatment system  5  according to the present embodiment further includes the cascade unit  40  including the first to third cascade heat exchangers  41  to  43 . Therefore, heat may be efficiently transferred via the cascade unit  40  from the first cycle C 1  serving as a heat-source side cycle to the second and third cycles C 2  and C 3  serving as load side cycles. 
     At least a part of the cascade unit  40  is disposed outdoors. Therefore, it is possible to reduce the restriction on the refrigerant used for the cascade unit  40  disposed outdoors. 
     (5-5) Modification A of Fifth Embodiment 
     According to the above-described embodiment, the entire cascade unit  40  is disposed outdoors, but this is not a limitation. According to the present modification, the first cascade heat exchanger  41  is disposed outdoors, and the second cascade heat exchanger  42  and the third cascade heat exchanger  43  are disposed indoors. A part of a pipe coupling the first cascade heat exchanger  41  and the second cascade heat exchanger  42  and a part of a pipe coupling the first cascade heat exchanger  41  and the third cascade heat exchanger  43  are disposed outdoors, and the remaining part is disposed indoors. A pipe coupling the second cascade heat exchanger  42  and the third cascade heat exchanger  43  is disposed indoors. As described above, when a part of the cascade unit  40  is disposed indoors, a cutoff valve is provided between an outdoor area and an indoor area in the secondary cycle where the secondary medium flows in the cascade unit  40 . 
     (5-6) Modification B of Fifth Embodiment 
     According to the fifth embodiment described above, the cascade unit  40  includes the secondary cycle where the first to third cascade heat exchangers are connected in series, but this is not a limitation. 
     In a heat treatment system  5   a  according to the present modification, as illustrated in  FIG. 6 , the cascade unit  40  includes the secondary cycle where the second cascade heat exchanger  42  and the third cascade heat exchanger  43  are arranged in parallel. The secondary cycle includes a first secondary cycle S 1  and a second secondary cycle S 2 . 
     Specifically, as the first secondary cycle S 1 , a circuit is configured in which the first cascade heat exchanger  41 , the second cascade heat exchanger  42 , and the circulating pump  46  are coupled with a pipe. As the second secondary cycle S 2 , a circuit is configured in which the first cascade heat exchanger  41 , the third cascade heat exchanger  43 , and the circulating pump  46  are coupled with a pipe. 
     After the secondary medium radiates heat to the first refrigerant to be cooled in the heat radiation unit  41   b  of the first cascade heat exchanger  41 , the secondary medium branches and flows into the heat absorption unit  42   a  of the second cascade heat exchanger  42  and the heat absorption unit  43   a  of the third cascade heat exchanger  43 . The secondary medium heated by absorption of heat from the second refrigerant in the heat absorption unit  42   a  and the secondary medium heated by absorption of heat from the third heat medium in the heat absorption unit  43   a  join together and flow into the heat radiation unit  41   b  of the first cascade heat exchanger  41 . 
     (6) Modification of First to Fifth Embodiments 
     The first to third cycles C 1  to C 3  described according to the above first to fifth embodiments are various cycles for which the total number of the heat-source side cycles and the load side cycles is three. There is no limitation as long as the first refrigerant or heat medium, the second refrigerant or heat medium, and the third refrigerant or heat medium are different from one another, but preferred specific examples are described in Table 1 below. Table 1 describes an application and a refrigerant or heat medium used for the application. In Table 1, a heat medium partially using a latent heat refers to a heat medium using sensible heat and latent heat. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Heat-source 
                 Heat-source 
                 Use-side 
                 Use-side 
                   
               
               
                 side C1 
                 side C2 
                 C2 
                 C3 
                 Application 
               
               
                   
               
             
            
               
                 R32 
                 — 
                 Water 
                 R1234ze 
                 Air conditioning &amp; high-temperature hot- 
               
               
                   
                   
                   
                   
                 water supply 
               
               
                 R32 
                 — 
                 Heat 
                 R1234yf 
                 Air conditioning (latent heat medium) &amp; 
               
               
                   
                   
                 medium 
                   
                 high-temperature hot-water supply 
               
               
                   
                   
                 partially 
               
               
                   
                   
                 using latent 
               
               
                   
                   
                 heat 
               
               
                 R32 
                 — 
                 CO 2   
                 R1234ze 
                 Waterless air conditioning &amp; high- 
               
               
                   
                   
                   
                   
                 temperature hot-water supply 
               
               
                 R32 
                 — 
                 Water 
                 Brine 
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 Water 
                 R404A 
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 Water 
                 R407H 
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 Water 
                 R468A 
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 Water 
                 CO 2   
                 Freezer or refrigerator 
               
               
                 R32 
                 — 
                 R410A 
                 CO 2   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 R466A 
                 CO 2   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 R513A 
                 CO 2   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 R515B 
                 CO 2   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 — 
                 Water 
                 CO 2   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R32 
                 Water 
                 CO 2   
                 — 
                 Use solar heat or exhaust heat as heat 
               
               
                   
                   
                   
                   
                 source 
               
               
                 R32 
                 Heat 
                 CO 2   
                 — 
                 Use solar heat or exhaust heat as heat 
               
               
                   
                 medium 
                   
                   
                 source 
               
               
                   
                 partially 
               
               
                   
                 using latent 
               
               
                   
                 heat 
               
               
                 R454B 
                 — 
                 R1234ze 
                 CO 2   
                 Medium GWP as heat source 
               
               
                   
                   
                   
                   
                 Air conditioning &amp; hot-water supply 
               
               
                 R1234yf 
                 — 
                 Water 
                 CO 2   
                 Low GWP as heat source 
               
               
                   
                   
                   
                   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R1234ze 
                 — 
                 Water 
                 CO 2   
                 Low GWP as heat source 
               
               
                   
                   
                   
                   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R1234ze 
                 CO 2   
                 Water 
                 — 
                 Heat-source side C1 corresponds to low 
               
               
                   
                   
                   
                   
                 outside air 
               
               
                 R1234yf 
                 CO 2   
                 Water 
                 — 
                 Heat-source side C1 corresponds to low 
               
               
                   
                   
                   
                   
                 outside air 
               
               
                 CO 2   
                 R32 
                 Water 
                 — 
                 Heat source corresponds to high outside 
               
               
                   
                   
                   
                   
                 air, supercooling circuit 
               
               
                 CO 2   
                 R1234ze 
                 Water 
                 — 
                 Heat source corresponds to high outside 
               
               
                   
                   
                   
                   
                 air, supercooling circuit 
               
               
                 CO 2   
                 R1234yf 
                 Water 
                 — 
                 Heat source corresponds to high outside 
               
               
                   
                   
                   
                   
                 air, supercooling circuit 
               
               
                 Ammonia 
                 — 
                 Water 
                 CO 2   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                 R290 
                 — 
                 Water 
                 CO 2   
                 Air conditioning &amp; freezer or refrigerator 
               
               
                   
               
            
           
         
       
     
     (7) Sixth Embodiment 
     (7-1) Overall Configuration 
     As illustrated in  FIG. 7 , in a heat treatment system  6  according to a seventh embodiment, the total number of heat-source side cycles and load side cycles is four or more. Here, the heat treatment system  6  includes two heat-source side cycles and three load side cycles. The first cycle C 1  and the second cycle are heat-source side cycles, and the third cycle C 3 , a fourth cycle C 4 , and a fifth cycle C 5  are load side cycles. 
     (7-2) Detailed Configuration 
     The first cycle C 1  is a heat-source side cycle forming an outdoor unit of an air conditioner. The first cycle C 1  includes the first compressor  11 , the first condenser  12  (or the first evaporator  14 ), the first expansion valve  13 , the first evaporator  14  (or the first condenser  12 ), a first accumulator  19 , and a four-way switching valve  20 . The first cycle C 1  circulates, for example, R32. 
     The second cycle C 2  is a heat-source side cycle using solar heat. The second cycle C 2  includes the circulating pump  51 , the solar heat panel  52 , and a heat absorption unit  54 . The second cycle C 2  circulates, for example, CO 2 . 
     The third cycle C 3  is an air cooling or air heating cycle forming an indoor unit of the air conditioner. The third cycle C 3  includes a second expansion valve  21 , the second evaporator  22  (or the second condenser  23 ), the condenser  23  (or the evaporator  22 ), an air cooling expansion valve  24 , a second accumulator  26 , the second compressor  27 , and four-way switching valves  28  and  29 . The third cycle C 3  circulates, for example, R1234yf, R404A, R407H, or R468A. 
     The fourth cycle C 4  is a freezer cycle and a refrigerator cycle. The fourth cycle C 4  includes the third compressor  31 , the third condenser  32 , the third expansion valve  33 , and the third evaporator  34 . The fourth cycle C 4  circulates, for example, CO 2 . 
     The fifth cycle C 5  is a hot-water supply cycle. The fifth cycle C 5  includes the circulating pump  35 , the heat absorption unit  36 , and the hot water storage tank  37 . The fifth cycle C 5  circulates, for example, water. 
     The heat treatment system  6  in the present embodiment includes a plurality of secondary cycles  70 ,  80 , and  90  that directly or indirectly exchanges heat with a plurality of cycles among the first to fifth cycles C 1  to C 5 . 
     The first secondary cycle  70  exchanges heat with the first cycle C 1 , the second cycle C 2 , and the fourth cycle C 4 . The first secondary cycle  70  and the first cycle C 1  share the first cascade heat exchanger  41 . The first secondary cycle  70  and the second cycle C 2  share the second cascade heat exchanger  42 . The first secondary cycle  70  and the fourth cycle C 4  share the third cascade heat exchanger  43 . 
     The first secondary cycle  70  primarily includes the first cascade heat exchanger  41 , the second cascade heat exchanger  42 , the third cascade heat exchanger  43 , a first pipe  71 , a second pipe  72 , a third pipe  73 , an expansion valve  74 , the second accumulator  26 , the second compressor  27 , and the four-way switching valves  28  and  29 . The first pipe  71  couples a coupling portion L 1  and the third cascade heat exchanger  43 . The second pipe  72  couples the third cascade heat exchanger  43  and a coupling portion L 2 . The third pipe  73  couples the third cascade heat exchanger  43  and a coupling portion L 3 . 
     In the first secondary cycle  70 , the third refrigerant flowing through the third cycle C 3  branches and flows at the coupling portion L 1  and joins again at the coupling portion L 3 . Therefore, the secondary medium circulating through the first secondary cycle  70  is the same as the refrigerant circulating through the third cycle C 3 . 
     The second secondary cycle  80  exchanges heat with the first cycle C 1 , the second cycle C 2 , and the third secondary cycle  90  which will be described below. The second secondary cycle  80  and the first cycle C 1  share the first cascade heat exchanger  41 . The second secondary cycle  80  and the second cycle C 2  share the second cascade heat exchanger  42 . The second secondary cycle  80  and the third secondary cycle share a fourth cascade heat exchanger  44 . The second secondary cycle  80  indirectly exchanges heat with the fifth cycle C 5 . 
     The second secondary cycle  80  primarily includes the first cascade heat exchanger  41 , the second cascade heat exchanger  42 , the fourth cascade heat exchanger  44 , a first pipe  81 , a second pipe  82 , a third pipe  83 , an expansion valve  84 , the second accumulator  26 , the second compressor  27 , and the four-way switching valves  28  and  29 . The first pipe  81  couples the coupling portion L 1  and the fourth cascade heat exchanger  44 . The second pipe  82  couples the fourth cascade heat exchanger  44  and the coupling portion L 2 . The third pipe  83  couples the fourth cascade heat exchanger  44  and the coupling portion L 3 . 
     In the second secondary cycle  80 , the third refrigerant flowing through the third cycle C 3  branches and flows at the coupling portion L 3  and joins again at the coupling portion L 1 . Therefore, the secondary medium circulating through the second secondary cycle  80  is the same as the refrigerant circulating through the third cycle C 3 . 
     The third secondary cycle  90  exchanges heat with the fifth cycle C 5  and the second secondary cycle  80 . The third secondary cycle  90  and the second secondary cycle  80  share the fourth cascade heat exchanger  44 . The third secondary cycle  90  and the fifth cycle C 5  share a fifth cascade heat exchanger  45 . 
     The third secondary cycle  90  primarily includes a compressor  91 , the fifth cascade heat exchanger  45 , an expansion valve  93 , and the fourth cascade heat exchanger  44 . 
     The secondary medium circulating through the third secondary cycle  90  is different from the refrigerants circulating through the first to fifth cycles C 1  to C 5  and in the first and second secondary cycles  70  and  80 . The secondary medium circulating through the third secondary cycle  90  is, for example, R1234ze. 
     The cascade unit  40  in the present embodiment includes the first cascade heat exchanger  41 , the second cascade heat exchanger  42 , the accumulator  26 , the second compressor  27 , and the four-way switching valves  28  and  29 . The cascade unit  40  is disposed outdoors. 
     (7-3) Operation of Heat Treatment System 
     (7-3-1) Air Cooling Operation 
     First, an operation of the heat treatment system  6  when an air cooling operation is performed in the third cycle C 3  will be described. During the air cooling operation, the four-way switching valve  20  of the outdoor unit is set to a communication state on the solid line side. During the air cooling operation, the operations of the first to fourth cycles C 1  to C 4  are performed, while the operations of the fifth cycle C 5  and the second and third secondary cycles  80  and  90  are not performed. 
     In the first cycle C 1 , the first refrigerant discharged from the first compressor  11  flows into the first condenser  12  and radiates heat to the outside air and condenses in the first condenser  12 . After the first refrigerant is expanded in the first expansion valve  13 , the first refrigerant absorbs heat from a first secondary medium (the third refrigerant) and evaporates in the first evaporator  14  of the first cascade heat exchanger  41 . Then, the first refrigerant passes through the four-way switching valve  20  and the accumulator  19  and is suctioned into the first compressor  11 . In the first cycle C 1 , the first refrigerant circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process. 
     In the second condenser  23  of the first cascade heat exchanger  41 , the first secondary medium (the third refrigerant) radiates heat to the first refrigerant and condenses. The third refrigerant flows into the third cycle C 3  and the first secondary cycle  70  at the coupling portion L 1 . 
     In the second cycle C 2 , the second heat medium heated by the solar heat panel  52  is supplied by the circulating pump  51  to the heat absorption unit  54  of the second cascade heat exchanger  42 , and heat is absorbed from the first secondary medium (the third refrigerant). The second heat medium continuously circulates through the second cycle C 2 . 
     In the third cycle C 3 , the third refrigerant flows from the coupling portion L 1  toward the second expansion valve  21 , expands in the second expansion valve  21 , and then absorbs heat from the indoor air and evaporates in the second evaporator  22  to cool the indoor air. Then, the third refrigerant is expanded in the air cooling expansion valve  24 , passes through the coupling portion L 2 , and is suctioned into the second compressor  27  via the accumulator  26 . The third refrigerant discharged from the second compressor  27  flows into the second cascade heat exchanger  42  by the four-way switching valve  28 . In a condenser  30  of the second cascade heat exchanger  42 , the third refrigerant radiates heat to the second heat medium of the second cycle C 2  and condenses. Then, the third refrigerant flows into the second condenser  23  of the first cascade heat exchanger  41 . The third refrigerant circulates as described above to repeat a condensation process, an expansion process, and an evaporation process and thus cool the inside of the room. 
     In the first secondary cycle  70 , the third refrigerant (the first secondary medium) passes from the coupling portion L 1  through the first pipe  71 , expands in the expansion valve  74 , and then flows into the third cascade heat exchanger  43 . In the third cascade heat exchanger  43 , the first secondary medium absorbs heat from a fourth heat medium and evaporates. Then, the first secondary medium is expanded in the expansion valve  75 , passes through the second pipe  72 , and joins with the third refrigerant circulating through the third cycle C 3  at the coupling portion L 2 . 
     In the fourth cycle C 4 , the third heat medium discharged from the third compressor  31  flows into the third condenser  32  of the third cascade heat exchanger  43  and radiates heat to the first secondary medium and condenses. After the fourth heat medium is expanded in the third expansion valve  33 , the fourth heat medium absorbs heat from the showcase and evaporates in the third evaporator  34  and thus freeze or refrigerate the inside of the showcase. Then, the fourth heat medium is suctioned into the third compressor  31 . In the third cycle C 3 , the third heat medium circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process and thus freeze or refrigerate the showcase. 
     (7-3-2) Air Heating Operation 
     Next, an operation of the heat treatment system  6  when the air heating operation is performed in the second cycle C 2  will be described. During the air heating operation, the four-way switching valve  20  of the outdoor unit is set to a communication state on the broken line side. During the air heating operation, the operations of the first, third, and fifth cycles C 1 , C 3 , and C 5  are performed, while the operations of the second and fourth cycles C 2  and C 4  and the first secondary cycle  70  are not performed. In the second cycle C 2 , the circulating pump  51  is stopped to interrupt the operation. 
     In the first cycle C 1 , the first refrigerant discharged from the first compressor  11  flows into the first condenser  12  via the four-way switching valve  20 . In the first condenser  12  of the first cascade heat exchanger  41 , the first refrigerant radiates heat from the third refrigerant and condenses. Then, the first refrigerant expands in the first expansion valve  13  and then flows into the first evaporator  14 . In the first evaporator, the first refrigerant absorbs heat from the outside air and evaporates in the first evaporator  14 . In the first cycle C 1 , the first refrigerant circulates as described above to repeat a compression process, a condensation process, an expansion process, and an evaporation process. 
     In the second evaporator  22  of the first cascade heat exchanger  41 , the first secondary medium (the third refrigerant) absorbs heat to the first refrigerant and evaporates. Then, the first secondary medium sequentially passes through the four-way switching valve  28  and the accumulator  26  and is compressed by the second compressor  27 . The compressed first secondary medium passes through the four-way switching valve  29  and flows into the third cycle C 3  and the second secondary cycle  80  at the coupling portion L 3 . 
     In the third cycle C 3 , the third refrigerant flows from the coupling portion L 3  into the second condenser  23 , radiates heat from the indoor air and condenses in the second condenser  23 , and heats the indoor air. Then, after the third refrigerant is expanded in the second expansion valve  21 , the third refrigerant flows into the second evaporator  22  via the coupling portion L 1 . The second refrigerant circulates as described above to repeat a condensation process, an evaporation process, and an expansion process and thus heat the inside of the room. 
     In the second secondary cycle  80 , the second secondary medium (the third refrigerant) flows into the fourth cascade heat exchanger  44  from the coupling portion L 3  via the third pipe  83 . In the fourth cascade heat exchanger  44 , the second secondary medium radiates heat from the third secondary medium circulating through the third secondary cycle  90  and condenses. Then, after the third secondary medium is expanded in the expansion valve  84 , the third secondary medium passes through the first pipe  81  and flows into the second evaporator  22  via the coupling portion L 1 . 
     In the third secondary cycle  90 , the third secondary medium discharged from the compressor  91  radiates heat and condenses in the heat radiation unit  92  of the fifth cascade heat exchanger  45 . After the third secondary medium is expanded in the expansion valve  93 , the third secondary medium absorbs heat from the third secondary medium (the third refrigerant) and evaporates in the heat radiation unit of the fourth cascade heat exchanger  44 . The third secondary medium is suctioned into the compressor  91 . 
     In the fifth cycle C 5 , the water in the hot water storage tank  37  is supplied by the circulating pump  35  to the heat absorption unit  36  of the fifth cascade heat exchanger  45  and is heated by absorption of heat from the third secondary medium. The hot water generated by heating returns to the hot water storage tank  37 , and the hot water continuously circulates through the fifth cycle C 5  until a predetermined heat storage temperature is obtained. 
     (7-4) Feature 
     In the heat treatment system  6  according to the present embodiment, the total number of the heat-source side cycles and the load side cycles is four or more. As described above, the use of four or more media in four or more cycles makes it possible to use an appropriate medium depending on the application of the load side cycle. 
     The present disclosure is not limited as long as three or more different media are used in three or more cycles. Therefore, for example, three or more different media may be used in four or more cycles. 
     For example, the features of the above-described embodiments and modifications may be combined as appropriate. 
     Although the embodiments of the present disclosure have been described above, it is understood that various changes may be made to forms and details without departing from the spirit and scope of the present disclosure described in claims. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  to  6  Heat treatment system 
               11 ,  27 ,  31 ,  91  Compressor 
               12 ,  16 ,  23 ,  30 ,  32  Condenser 
               13 ,  17 ,  21 ,  24 ,  33 ,  74 ,  75 ,  84 ,  93  Expansion valve 
               14 ,  15 ,  18 ,  22 ,  34  Evaporator 
               19 ,  26  First accumulator 
               20 ,  28 ,  29  Four-way switching valve 
               35 ,  46 ,  51  Circulating pump 
               36 ,  38 ,  41   a ,  42   a ,  43   a ,  54  Heat absorption unit 
               37  Hot water storage tank 
               40  Cascade unit 
               41  to  45  Cascade heat exchanger 
               41   b ,  42   b ,  43   b ,  53 ,  92  Heat radiation unit 
               52  Solar heat panel 
               70 ,  80 ,  90 , S 1 , S 2  Secondary cycle 
               71 ,  72 ,  73 ,  81 ,  82 ,  83  Pipe 
             C 1  First cycle 
             C 2  Second cycle 
             C 3  Third cycle 
             C 4  Fourth cycle 
             C 5  Fifth cycle 
           
         
         CITATION LIST PATENT LITERATURE [Patent Document 1] Japanese Patent Laying Open No. 11-173725