Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus includes a heat source unit. The heat source unit includes a heat medium heat exchanger. Refrigerant circulating in a refrigerant circuit and a heat medium, which is a medium different from the refrigerant, exchange heat in the heat medium heat exchanger. The heat source unit supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit. The refrigeration cycle apparatus includes a heat medium circuit in which the heat medium supplied from the heat source unit circulates. The heat medium circuit includes multiple load-side heat exchangers and a switching mechanism configured to switch a distribution state of the heat medium to flow into and out of each of the load-side heat exchangers. The refrigeration cycle apparatus also includes a relay unit storing the switching mechanism therein.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a refrigeration cycle apparatus.BACKGROUND ART

[0002] Hitherto, a refrigeration cycle apparatus including a chiller-type heat source unit is known. The chiller-type heat source unit causes refrigerant circulating within a refrigerant circuit and a heat medium, which is a medium different from the refrigerant, to exchange heat in a heat medium heat exchanger. The heat source unit then supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit. In addition to the chiller-type heat source unit, the refrigeration cycle apparatus also includes a heat medium circuit in which the heat medium supplied from the heat source unit circulates. As the refrigeration cycle apparatus including a chiller-type heat source unit, a refrigeration cycle apparatus including multiple load-side heat exchangers in a heat medium circuit has also been proposed. For example, Patent Literature 1 discloses that a refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers is used as an air-conditioning apparatus as an application example. That is, the refrigeration cycle apparatus disclosed in Patent Literature 1 uses the multiple load-side heat exchangers as an indoor heat exchanger.

[0003] In a known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, a heat medium circuit is configured as follows. The heat medium circuit includes a main pipe that allows a heat medium flowing out of the heat source unit to flow therethrough and returns the heat medium to the heat source unit. Each of the load-side heat exchangers is connected to the main pipe via a branch pipe. The distribution state of the heat medium to flow into and out of each of the load-side heat exchangers is switched by a switching mechanism provided in the branch pipe connected to the corresponding load-side heat exchanger. That is, the switching mechanisms each provided in the branch pipe connected to the corresponding load-side heat exchanger each perform a switching operation to determine whether to allow the heat medium to flow into and out of the corresponding load-side heat exchanger.CITATION LISTPatent Literature

[0004] Patent Literature 1: Japanese Unexamined Patent Application Publication No. H4-214134SUMMARY OF INVENTIONTechnical Problem

[0005] When performing on-site installation of the above-described type of known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, the main pipe of the heat medium circuit is laid to pass by the vicinity of each of the load-side heat exchangers. Each of the load-side heat exchangers is connected to a portion of the main pipe, which is disposed near the load-side heat exchanger, via a branch pipe. Hence, this type of known refrigeration cycle apparatus requires a long main pipe. Additionally, heat mediums flowing through the individual load-side heat exchangers join together and flow through the main pipe. To reduce pressure loss produced by the heat medium flowing through the main pipe, the main pipe needs to be thick. That is, for the above-described type of known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, a long, thick main pipe needs to be installed on-site. It thus takes time to install this type of known refrigeration cycle apparatus on-site.

[0006] The present disclosure has been made to solve the above-described problem. It is an object of the disclosure to provide a refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers that makes it possible to reduce its on-site installation time compared with before.Solution to Problem

[0007] A refrigeration cycle apparatus according to an embodiment of the present disclosure includes a heat source unit. The heat source unit includes a heat medium heat exchanger. Refrigerant circulating in a refrigerant circuit and a heat medium, which is a medium different from the refrigerant, exchange heat in the heat medium heat exchanger. The heat source unit supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit. The refrigeration cycle apparatus includes a heat medium circuit in which the heat medium supplied from the heat source unit circulates. The heat medium circuit includes multiple load-side heat exchangers and a switching mechanism configured to switch a distribution state of the heat medium to flow into and out of each of the load-side heat exchangers. The refrigeration cycle apparatus also includes a relay unit storing the switching mechanism therein.Advantageous Effects of Invention

[0008] In the refrigeration cycle apparatus according to an embodiment of the present disclosure, the pipe to be installed on-site, which is equivalent to the main pipe of a known refrigeration cycle apparatus, is a pipe that connects a heat source unit and a relay unit. In the refrigeration cycle apparatus according to an embodiment of the disclosure, therefore, the pipe to be installed on-site can be made shorter than the main pipe of the known refrigeration cycle apparatus. Hence, the on-site installation time of the refrigeration cycle apparatus according to an embodiment of the disclosure can be reduced compared with before.BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 1 that is operating in a cooling only operation mode.

[0010] FIG. 2 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in a cooling main operation mode.

[0011] FIG. 3 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in a heating only operation mode.

[0012] FIG. 4 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in a heating main operation mode.

[0013] FIG. 5 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 2.

[0014] FIG. 6 is a diagram illustrating an example of the circuit configuration of the refrigeration cycle apparatus according to Embodiment 2.

[0015] FIG. 7 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 3.

[0016] FIG. 8 is a diagram illustrating an example of the circuit configuration of the refrigeration cycle apparatus according to Embodiment 3.

[0017] FIG. 9 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 4.

[0018] FIG. 10 is a diagram illustrating an example of the circuit configuration of the refrigeration cycle apparatus according to Embodiment 4.

[0019] FIG. 11 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 5.DESCRIPTION OF EMBODIMENTS

[0020] An example of a refrigeration cycle apparatus according to an embodiment of the disclosure will be described below with reference to the drawings and other things through illustration of Embodiment 1 through Embodiment 5. In the drawings including FIG. 1, elements designated by the same reference sign are the same element or corresponding elements. This applies to the whole text in Embodiment 1 through Embodiment 5. The refrigeration cycle apparatus according to an embodiment of the disclosure described through illustration of Embodiment 1 through Embodiment 5 is only an example. The refrigeration cycle apparatus of an embodiment of the disclosure is not limited to the modes described in the specification. In Embodiment 1 through Embodiment 5, the refrigeration cycle apparatus of an embodiment of the disclosure is used as an air-conditioning apparatus as an application example.Embodiment 1

[0021] FIG. 1 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 1 that is operating in a cooling only operation mode. The solid-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of refrigerant. The broken-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of a heat medium. In FIGS. 1 through 11, a flow path in the open state is indicated by the corresponding valve or mechanism with a white fill, while a flow path in the closed state is indicated by the corresponding valve or mechanism with a black fill.

[0022] A refrigeration cycle apparatus 200 includes a chiller-type heat source unit 201 and a heat medium circuit 110 in which a heat medium supplied from the heat source unit 201 circulates.

[0023] The heat source unit 201 includes a refrigerant circuit 100 in which refrigerant circulates and a heat medium heat exchanger. In other words, the refrigerant circuit 100 and the heat medium heat exchanger are stored in the heat source unit 201. The heat medium heat exchanger functions as a condenser or an evaporator in the refrigerant circuit 100 and causes the refrigerant circulating in the refrigerant circuit 100 and a heat medium, which is a medium different from the refrigerant, to exchange heat therein. The heat source unit 201 supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit 201.

[0024] The type of refrigerant to circulate in the refrigerant circuit 100 is not limited to a specific type. In one example, the refrigerant to circulate in the refrigerant circuit 100 is olefin-based refrigerant, ethylene-based refrigerant, ethane-based refrigerant, propane, or dimethyl ether. In another example, the refrigerant to circulate in the refrigerant circuit 100 is a mixed refrigerant of at least two of olefin-based refrigerant, ethylene-based refrigerant, ethane-based refrigerant, propane, and dimethyl ether. The olefin-based refrigerant is tetrafluoropropene, for example, such as HFO1234yf and HFO1234ze (E). The ethylene-based refrigerant is difluoroethylene, for example.

[0025] The ethane-based refrigerant is tetrafluoroethane, for example. The type of heat medium to exchange heat with the refrigerant in the heat medium heat exchanger is not limited to a specific type, either. Examples of the heat medium are brine, antifreeze, and water. Brine contains calcium chloride solution, sodium chloride solution, magnesium chloride solution, or ethylene glycol, for example.

[0026] In Embodiment 1, as the heat medium heat exchanger, a first heat medium heat exchanger 1 and a second heat medium heat exchanger 2 are provided. The refrigeration cycle apparatus 200 may include only one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2. That is, the refrigeration cycle apparatus 200 may include only one heat medium heat exchanger. In Embodiment 1, when one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 functions as a condenser, the other one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 can function as an evaporator. That is, the heat source unit 201 of Embodiment 1 can supply a heated heat medium and a cooled heat medium at the same time. Because of this configuration, in Embodiment 1, the refrigerant circuit 100 is configured as follows, for example.

[0027] The refrigerant circuit 100 includes a compressor 14, a first flow switching device 41, a second flow switching device 42, an outdoor heat exchanger 4, a first expansion device 21, a second expansion device 22, a first opening-closing valve 51, a second opening-closing valve 52, a third opening-closing valve 53, and a fourth opening-closing valve 54. The first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 also form part of the refrigerant circuit 100.

[0028] The compressor 14 sucks refrigerant, compresses it into a high-temperature high-pressure state, and discharges the resulting refrigerant. As the compressor 14, a rotary compressor, a scroll compressor, a screw compressor, or a reciprocating compressor, for example, can be used. The refrigerant discharge outlet of the compressor 14 is connected to the first flow switching device 41 and the second flow switching device 42. More specifically, a refrigerant pipe connected to the refrigerant discharge outlet of the compressor 14 branches off at a node a and is divided into two refrigerant pipes. One of the divided refrigerant pipes is connected to the first flow switching device 41, while the other one of the divided refrigerant pipes is connected to the second flow switching device 42. The refrigerant suction inlet of the compressor 14 is also connected to the first flow switching device 41 and the second flow switching device 42. More specifically, the refrigerant pipe connected to the refrigerant suction inlet of the compressor 14 branches off and is divided into two refrigerant pipes. One of the divided refrigerant pipes is connected to the first flow switching device 41, while the other one of the divided refrigerant pipes is connected to the second flow switching device 42.

[0029] The first flow switching device 41 is a four-way valve, for example. The first flow switching device 41 switches a flow regarding whether to allow the refrigerant discharge outlet of the compressor 14 to communicate with the outdoor heat exchanger 4. The first flow switching device 41 also switches a flow regarding whether to allow the refrigerant suction inlet of the compressor 14 to communicate with the outdoor heat exchanger 4. The second flow switching device 42 is a four-way valve, for example.

[0030] The second flow switching device 42 switches a flow regarding whether to allow the refrigerant discharge outlet of the compressor 14 to communicate with the third opening-closing valve 53 and the fourth opening-closing valve 54. The first flow switching device 41 switches a flow regarding whether to allow the refrigerant suction inlet of the compressor 14 to communicate with the third opening-closing valve 53 and the fourth opening-closing valve 54.

[0031] The outdoor heat exchanger 4 functions as an evaporator or a condenser. When the outdoor heat exchanger 4 functions as an evaporator, it performs heat exchange between refrigerant and outdoor air flowing inside to evaporate and gasify the refrigerant. When the outdoor heat exchanger 4 functions as a condenser, it performs heat exchange between refrigerant and outdoor air flowing inside to condense and liquify the refrigerant.

[0032] In Embodiment 1, to enhance the heat exchange between the refrigerant and outdoor air in the outdoor heat exchanger 4, an outdoor fan 5 that sends outdoor air to the outdoor heat exchanger 4 is disposed adjacent to the outdoor heat exchanger 4. The outdoor fan 5 may be constituted by a propeller fan, a line flow fan (registered trademark), or a multiblade centrifugal fan, for example, based on the operating conditions, such as the flow rate and the static pressure of outdoor air to be supplied to the outdoor heat exchanger 4.

[0033] Each of the first expansion device 21 and the second expansion device 22 has a function as a reducing valve or an expansion valve and is used for expanding the refrigerant to reduce the pressure of the refrigerant. Each of the first expansion device 21 and the second expansion device 22 is an electronic expansion valve, for example, that can control the flow rate of refrigerant. The first expansion device 21 and the second expansion device 22 are connected in parallel with the outdoor heat exchanger 4. More specifically, the refrigerant pipe connected to the outdoor heat exchanger 4 branches off at a node b and is divided into two refrigerant pipes. One of the divided refrigerant pipes is connected to the first expansion device 21, while the other one of the divided refrigerant pipes is connected to the second expansion device 22. The first expansion device 21 and the second expansion device 22 are not limited to an electronic expansion valve and may be a mechanical expansion valve using a diaphragm for the pressure receiving part. The first expansion device 21 and the second expansion device 22 may partially be constituted by a capillary tube, for example.

[0034] As discussed above, the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 each functions as a condenser or an evaporator in the refrigerant circuit 100. When the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 function as evaporators, they perform heat exchange between the refrigerant and a heat medium flowing inside to evaporate and gasify the refrigerant. In this case, the heat medium is cooled by the refrigerant. When the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 function as condensers, they perform heat exchange between the refrigerant and a heat medium flowing inside to condense and liquify the refrigerant. In this case, the heat medium is heated by the refrigerant. One end of the refrigerant flow path of the first heat medium heat exchanger 1 is connected to the first expansion device 21. One end of the refrigerant flow path of the second heat medium heat exchanger 2 is connected to the second expansion device 22.

[0035] Each of the first opening-closing valve 51, second opening-closing valve 52, third opening-closing valve 53, and fourth opening-closing valve 54 is a two-way valve, for example, and opens and closes the flow path where the corresponding opening-closing valve is installed. The first opening-closing valve 51 and the third opening-closing valve 53 are connected in parallel with the other end of the refrigerant flow path of the first heat medium heat exchanger 1. The second opening-closing valve 52 and the fourth opening-closing valve 54 are connected in parallel with the other end of the refrigerant flow path of the second heat medium heat exchanger 2. The first opening-closing valve 51 and the second opening-closing valve 52 are connected at a node c to a pipe that connects the refrigerant suction inlet of the compressor 14 and the first flow switching device 41. The third opening-closing valve 53 and the fourth opening-closing valve 54 are connected to the second flow switching device 42.

[0036] As stated above, the heat medium circuit 110 is a circuit in which a heat medium supplied from the heat source unit 201 circulates. That is, the heat medium circuit 110 is a circuit in which a heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger circulates. The heat medium circuit 110 includes multiple load-side heat exchangers and a switching mechanism 70. The switching mechanism 70 switches the distribution state of a heat medium to flow into and out of each of the load-side heat exchangers. The heat medium circuit 110 in Embodiment 1 includes load-side heat exchangers 3a and 3b as the multiple load-side heat exchangers. The switching mechanism 70 thus switches the distribution state of a heat medium to flow into and out of each of the load-side heat exchangers 3a and 3b. As stated above, the refrigeration cycle apparatus 200 according to Embodiment 1 is used as an air-conditioning apparatus. The load-side heat exchangers 3a and 3b are thus used as an indoor heat exchanger that heats or cools indoor air. The load-side heat exchangers 3a and 3b are stored in different heat load units 202 and are installed indoors, which is a space to be air-conditioned.

[0037] Using the refrigeration cycle apparatus 200 as an air-conditioning apparatus is only an application example of the refrigeration cycle apparatus 200. The refrigeration cycle apparatus 200 may be used as a device other than the air-conditioning apparatus. For example, the load-side heat exchangers 3a and 3b may be disposed under the floor and be used for floor heating. In another example, the load-side heat exchangers 3a and 3b may be used as heat exchangers for heating water stored in a hot water storage tank. In another example, the load-side heat exchangers 3a and 3b may be used as heat exchangers for cooling air within a freezer compartment.

[0038] As discussed above, the heat source unit 201 in Embodiment 1 includes the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 as the heat medium heat exchanger. The heat medium circuit 110 in Embodiment 1 thus includes a first circuit 111 that allows a heat medium to pass therethrough and to flow into the first heat medium heat exchanger 1 and a second circuit 112 that allows a heat medium to pass therethrough and to flow into the second heat medium heat exchanger 2. The switching mechanism 70 switches the distribution state of a heat medium flowing out of the first heat medium heat exchanger 1 to flow into each of the load-side heat exchangers. The switching mechanism 70 also switches the distribution state of a heat medium flowing out of the second heat medium heat exchanger 2 to flow into each of the load-side heat exchangers.

[0039] To explain the switching mechanism 70 more specifically, the switching mechanism 70 includes a first flow switching mechanism 71, a second flow switching mechanism 72, a third flow switching mechanism 73, and a fourth flow switching mechanism 74. Each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is a three-way valve, for example. However, they are not limited to a three-way valve and may be constituted by a combination of multiple two-way valves.

[0040] The first flow switching mechanism 71 is connected to the heat medium flow outlet of the first heat medium heat exchanger 1. The first flow switching mechanism 71 is also connected to the inlet of the load-side heat exchanger 3a. The first flow switching mechanism 71 is also connected to a pipe that connects the third flow switching mechanism 73 and the load-side heat exchanger 3b with each other. The first flow switching mechanism 71 allows two of the three connection locations to communicate with the first flow switching mechanism 71.

[0041] The second flow switching mechanism 72 is connected to the heat medium flow inlet of the first heat medium heat exchanger 1. A first pump 6, which will be discussed later, is installed between the second flow switching mechanism 72 and the heat medium flow inlet of the first heat medium heat exchanger 1. It can thus be said that the second flow switching mechanism 72 is connected to the first pump 6. The second flow switching mechanism 72 is also connected to the outlet of the load-side heat exchanger 3a. The second flow switching mechanism 72 is also connected to a pipe that connects the fourth flow switching mechanism 74 and the load-side heat exchanger 3b with each other. The second flow switching mechanism 72 allows two of the three connection locations to communicate with the second flow switching mechanism 72.

[0042] The third flow switching mechanism 73 is connected to the heat medium flow outlet of the second heat medium heat exchanger 2. The third flow switching mechanism 73 is also connected to a pipe that connects the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other. The third flow switching mechanism 73 is also connected to the inlet of the load-side heat exchanger 3b. The third flow switching mechanism 73 allows two of the three connection locations to communicate with the third flow switching mechanism 73.

[0043] The fourth flow switching mechanism 74 is connected to the heat medium flow inlet of the second heat medium heat exchanger 2. A second pump 7, which will be discussed later, is installed between the fourth flow switching mechanism 74 and the heat medium flow inlet of the second heat medium heat exchanger 2. It can thus be said that the fourth flow switching mechanism 74 is connected to the second pump 7. The fourth flow switching mechanism 74 is also connected to a pipe that connects the second flow switching mechanism 72 and the load-side heat exchanger 3a with each other. The fourth flow switching mechanism 74 is also connected to the outlet of the load-side heat exchanger 3b. The fourth flow switching mechanism 74 allows two of the three connection locations to communicate with the fourth flow switching mechanism 74.

[0044] The load-side heat exchanger 3a becomes part of the first circuit 111 when communicating with the first heat medium heat exchanger 1. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3a to communicate with each other also becomes part of the first circuit 111. The pipe that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3a to communicate with each other also becomes part of the first circuit 111. The load-side heat exchanger 3a becomes part of the second circuit 112 when communicating with the second heat medium heat exchanger 2. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3a to communicate with each other also becomes part of the second circuit 112. The pipe that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3a to communicate with each other also becomes part of the second circuit 112.

[0045] Likewise, the load-side heat exchanger 3b becomes part of the first circuit 111 when communicating with the first heat medium heat exchanger 1. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3b to communicate with each other also becomes part of the first circuit 111. The pipe that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3b to communicate with each other also becomes part of the first circuit 111. The load-side heat exchanger 3b becomes part of the second circuit 112 when communicating with the second heat medium heat exchanger 2. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3b to communicate with each other also becomes part of the second circuit 112. The pipe that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3b to communicate with each other also becomes part of the second circuit 112.

[0046] The refrigeration cycle apparatus 200 includes a relay unit 203. The above-described switching mechanism 70 is stored in the relay unit 203. In other words, the refrigeration cycle apparatus 200 includes the relay unit 203 in which the switching mechanism 70 is stored.

[0047] The heat medium circuit 110 in Embodiment 1 includes a pump to circulate a heat medium in the heat medium circuit 110. More specifically, the heat medium circuit 110 includes the first pump 6 disposed in the first circuit 111 and the second pump 7 disposed in the second circuit 112 as the pump. The first pump 6 is disposed at a position in the first circuit 111 at which a heat medium to return to the first heat medium heat exchanger 1 flows. The first pump 6 discharges the heat medium to return to the first heat medium heat exchanger 1. The second pump 7 is disposed at a position in the second circuit 112 at which a heat medium to return to the second heat medium heat exchanger 2 flows. The second pump 7 discharges the heat medium to return to the second heat medium heat exchanger 2. In Embodiment 1, the first pump 6 and the second pump 7 are stored in the relay unit 203.

[0048] The refrigeration cycle apparatus 200 according to Embodiment 1 includes a controller 210 that controls the operating state of the refrigeration cycle apparatus 200. More specifically, the controller 210 starts and stops the compressor 14. The controller 210 may control the rotation speed of the compressor 14 when driving it. This can adjust the amount of refrigerant to be discharged from the compressor 14. The controller 210 also switches the flow path of each of the first flow switching device 41 and the second flow switching device 42. The controller 210 also starts and stops the outdoor fan 5. The controller 210 may control the rotation speed of the outdoor fan 5 when driving it. The controller 210 also controls the opening degree of each of the first expansion device 21 and the second expansion device 22. The controller 210 also controls the open / closed state of each of the first opening-closing valve 51, second opening-closing valve 52, third opening-closing valve 53, and fourth opening-closing valve 54. The controller 210 also switches the flow path of the switching mechanism 70. That is, the controller 210 switches the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74. The controller 210 also starts and stops the first pump 6 and the second pump 7. The controller 210 may control the rotation speed of each of the first pump 6 and the second pump 7 when driving them. This can adjust the amount of refrigerant to be discharged from the first pump 6 and that from the second pump 7.

[0049] The controller 210 configured as described above is constituted by dedicated hardware or a CPU (Central Processing Unit) that executes a program stored in a memory. The CPU may also be called a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a processor.

[0050] If the controller 210 is constituted by dedicated hardware, it is a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), a FPGA (Field-Programmable Gate Array), or a combination thereof, for example. The individual functional units to be implemented by the controller 210 may be implemented by individual hardware units or by one hardware unit.

[0051] If the controller 210 is constituted by a CPU, the individual functions to be executed by the controller 210 are implemented by software, firmware, or a combination thereof. The software and firmware are described as a program and the program is stored in a memory. The CPU reads and executes the program stored in the memory to implement the individual functions of the controller 210. The memory is a volatile or non-volatile semiconductor memory, such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM, for example.

[0052] Some of the functions of the controller 210 may be implemented by dedicated hardware and some of the functions may be implemented by software or firmware. In Embodiment 1, the controller 210 is stored in the heat source unit 201. However, at least part of the controller 210 may be stored in a location other than the heat source unit 201. For example, the configuration of the controller 210 may be distributed over the heat source unit 201 and the relay unit 203 and be stored therein.

[0053] Hitherto, a refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers has been proposed. In such a known refrigeration cycle apparatus, the heat medium circuit is configured as follows. The heat medium circuit includes a main pipe that allows a heat medium flowing out of the heat source unit to flow therethrough and returns the heat medium to the heat source unit. Each of the load-side heat exchangers is connected to the main pipe via a branch pipe. The distribution state of the heat medium to flow into and out of each of the load-side heat exchangers is switched by a switching mechanism provided in the branch pipe connected to the corresponding load-side heat exchanger. That is, the switching mechanisms each provided in the branch pipe connected to the corresponding load-side heat exchanger each perform a switching operation to determine whether to allow the heat medium to flow into or out of the corresponding load-side heat exchanger.

[0054] With the above-described configuration, when performing on-site installation of the above-described type of known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, the main pipe of the heat medium circuit is laid to pass by the vicinity of each of the load-side heat exchangers. Each of the load-side heat exchangers is connected to a portion of the main pipe, which is disposed near the load-side heat exchanger, via the corresponding branch pipe. Hence, this type of known refrigeration cycle apparatus requires a long main pipe. Additionally, heat mediums flowing through the individual load-side heat exchangers join together and flow through the main pipe. To reduce pressure loss produced by the heat medium flowing through the main pipe, the main pipe needs to be thick. That is, for the above-described type of known refrigeration cycle apparatus, a long, thick main pipe needs to be installed on-site.

[0055] It thus takes time to install the above-described type of known refrigeration cycle apparatus on-site. It is also necessary to attach the switching mechanisms one by one on-site to the branch pipes connected to the corresponding load-side heat exchangers. This operation also makes the on-site installation of the refrigeration cycle apparatus time-consuming. Additionally, since the heat medium circuit of the above-described type of known refrigeration cycle apparatus includes a long, thick main tube, it also takes time to purge air from the heat medium circuit when enclosing a heat medium in the heat medium circuit. This operation also makes the on-site installation of the refrigeration cycle apparatus time-consuming. The heat medium circuit of the above-described type of known refrigeration cycle apparatus includes a long, thick main tube, and a large amount of heat medium to be enclosed in the heat medium circuit is thus required.

[0056] In contrast, the on-site installation of the refrigeration cycle apparatus 200 according to Embodiment 1 is performed as follows. The heat source unit 201, the relay unit 203, and the heat load units 202 are installed at predetermined locations. Then, the heat source unit 201 and the relay unit 203 connect to each other with a pipe, and the relay unit 203 and the heat load units 202 connect to each other with a pipe. In the refrigeration cycle apparatus 200 according to Embodiment 1, the pipe, which is equivalent to the main pipe of the heat medium circuit of the known refrigeration cycle apparatus, is the pipe that connects the heat medium heat exchanger and the switching mechanism 70. This means that the pipe that connects the heat source unit 201 and the relay unit 203 in the refrigeration cycle apparatus 200 of Embodiment 1 is part of the pipe equivalent to the main pipe of the known refrigeration cycle apparatus. The remaining portion of the pipe equivalent to the main pipe of the known refrigeration cycle apparatus is stored in the heat source unit 201 and the relay unit 203 in the refrigeration cycle apparatus 200 of Embodiment 1. This means that, when the heat source unit 201 and the relay unit 203 are installed, the installation of the remaining portion of the pipe equivalent to the main pipe of the known refrigeration cycle apparatus is completed at the same time.

[0057] In the refrigeration cycle apparatus 200 of Embodiment 1, therefore, the pipe to be installed on-site, which is equivalent to the main pipe of the known refrigeration cycle apparatus, can be made shorter than the main pipe of the heat medium circuit of the known refrigeration cycle apparatus. Hence, the on-site installation time of the refrigeration cycle apparatus 200 of Embodiment 1 can be reduced compared with before. Additionally, in the refrigeration cycle apparatus 200 of Embodiment 1, when the relay unit 203 is installed, the installation of the switching mechanism 70 is also completed. In this respect, too, the on-site installation time of the refrigeration cycle apparatus 200 of Embodiment 1 can be reduced compared with before. In the refrigeration cycle apparatus 200 of Embodiment 1, the relay unit 203 and the heat load units 202 connect to each other with a pipe, and the pipe equivalent to the main pipe of the known refrigeration cycle apparatus can thus be made shorter. In the refrigeration cycle apparatus 200 of Embodiment 1, since the pipe equivalent to the main pipe of the known refrigeration cycle apparatus can be decreased, the occurrence of pressure loss produced by a heat medium flowing through the pipe can be reduced. This also makes it possible to make the size of the pipe of the refrigeration cycle apparatus 200 of Embodiment 1 smaller than the main pipe of the known refrigeration cycle apparatus. Hence, the time to purge air from the heat medium circuit 110 when enclosing a heat medium in the heat medium circuit 110 can become shorter than before. In this respect, too, the on-site installation time of the refrigeration cycle apparatus 200 of Embodiment 1 can be reduced compared with before. In the refrigeration cycle apparatus 200 of Embodiment 1, since the pipe equivalent to the main pipe of the known refrigeration cycle apparatus can be made shorter and smaller, the amount of heat medium enclosed in the heat medium circuit 110 can also be decreased compared with before.

[0058] Subsequently, the operation of the refrigeration cycle apparatus 200 will be described below by referring to a flow of refrigerant and that of a heat medium. The refrigeration cycle apparatus 200 can operate in the cooling only operation mode, the heating only operation mode, the cooling main operation mode, and the heating main operation mode. The cooling only operation mode is an operation mode in which all the heat load units 202 perform the cooling operation. The heating only operation mode is an operation mode in which all the heat load units 202 perform the heating operation. The cooling main operation mode is an operation mode in which some heat load units 202 perform the cooling operation and some heat load units 202 perform the heating operation and the cooling load is higher than the heating load. The heating main operation mode is an operation mode in which some heat load units 202 perform the cooling operation and some heat load units 202 perform the heating operation and the heating load is higher than the cooling load.Cooling Only Operation Mode

[0059] An explanation will first be given, based on FIG. 1, of the cooling only operation mode executed by the refrigeration cycle apparatus 200. The cooling only operation mode will be explained below with reference to FIG. 1 through illustration of an example in which all the heat load units 202 perform the cooling operation. In other words, FIG. 1 illustrates an example in which a cooling energy load is generated both in the load-side heat exchangers 3a and 3b.

[0060] In the cooling only operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant discharge outlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant suction inlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the second opening-closing valve 52 to be in the open state and sets the third opening-closing valve 53 and the fourth opening-closing valve 54 to be in the closed state. The controller 210 also switches the flow path of the first flow switching mechanism71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other.

[0061] The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0062] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 flows into the outdoor heat exchanger 4, which is functioning as a condenser, via the node a and the first flow switching device 41. The high-temperature high-pressure gas refrigerant is then transformed into high-pressure liquid refrigerant while transferring heat to outdoor air. The high-pressure liquid refrigerant flowing out of the outdoor heat exchanger 4 branches off at the node b and flows into the first expansion device 21 and the second expansion device 22.

[0063] The high-pressure liquid refrigerant flowing into the first expansion device 21 is then expanded to low-temperature low-pressure two-phase gas-liquid refrigerant and flows into the first heat medium heat exchanger 1, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the first heat medium heat exchanger 1 then receives heat from a heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium. Likewise, the high-pressure liquid refrigerant flowing into the second expansion device 22 is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant and flows into the second heat medium heat exchanger 2, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the second heat medium heat exchanger 2 then receives heat from a heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium.

[0064] The low-pressure gas refrigerant flowing out of the first heat medium heat exchanger 1 passes through the first opening-closing valve 51. The low-pressure gas refrigerant flowing out of the second heat medium heat exchanger 2 passes through the second opening-closing valve 52. These low-pressure gas refrigerants pass through the node c and are sucked into the compressor 14 again.

[0065] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0066] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then cooled by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0067] While the refrigeration cycle apparatus 200 is operating in the cooling only operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.Cooling Main Operation Mode

[0068] FIG. 2 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in the cooling main operation mode. The cooling main operation mode will be explained below with reference to FIG. 2 through illustration of an example in which the heat load unit 202 storing the load-side heat exchanger 3a performs the cooling operation and the heat load unit 202 storing the load-side heat exchanger 3b performs the heating operation. In other words, FIG. 2 illustrates an example in which a cooling energy load is generated in the load-side heat exchanger 3a and a heating energy load is generated in the load-side heat exchanger 3b.

[0069] In the cooling main operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant discharge outlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant discharge outlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the fourth opening-closing valve 54 to be in the open state and sets the second opening-closing valve 52 and the third opening-closing valve 53 to be in the closed state. The controller 210 also switches the flow path of the first flow switching mechanism 71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0070] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 branches off at the node a and is divided into the refrigerant to flow into the outdoor heat exchanger 4 via the first flow switching device 41 and into the refrigerant to flow into the second flow switching device 42.

[0071] The high-temperature high-pressure gas refrigerant flowing into the outdoor heat exchanger 4, which is functioning as a condenser, is transformed into high-pressure liquid refrigerant while transferring heat to outdoor air. The high-temperature high-pressure gas refrigerant flowing into the second flow switching device 42 passes through the fourth opening-closing valve 54 and enters the second heat medium heat exchanger 2, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant having entered the second heat medium heat exchanger 2 transfers heat to the heat medium and is transformed into high-pressure liquid refrigerant or high-pressure two-phase gas-liquid refrigerant while heating the heat medium.

[0072] The refrigerant flowing out of the outdoor heat exchanger 4 flows toward the node b. The refrigerant flowing out of the second heat medium heat exchanger 2 passes through the second expansion device 22 and also flows toward the node b. These refrigerants join together at the node b and the joined refrigerant flows into the first expansion device 21. The refrigerant flowing into the first expansion device 21 is then expanded to low-temperature low-pressure two-phase gas-liquid refrigerant and flows into the first heat medium heat exchanger 1, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant then receives heat from a heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium. The low-pressure gas refrigerant flowing out of the first heat medium heat exchanger 1 passes through the first opening-closing valve 51 and is sucked into the compressor 14 again via the node c.

[0073] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0074] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then heated by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0075] While the refrigeration cycle apparatus 200 is operating in the cooling main operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.Heating Only Operation Mode

[0076] FIG. 3 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in the heating only operation mode. The heating only operation mode will be explained below with reference to FIG. 3 through illustration of an example in which all the heat load units 202 perform the heating operation. In other words, FIG. 3 illustrates an example in which a heating energy load is generated both in the load-side heat exchangers 3a and 3b.

[0077] In the heating only operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant suction inlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant discharge outlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the second opening-closing valve 52 to be in the closed state and sets the third opening-closing valve 53 and the fourth opening-closing valve 54 to be in the open state. The controller 210 also switches the flow path of the first flow switching mechanism 71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0078] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 flows into the third opening-closing valve 53 and the fourth opening-closing valve 54 via the second flow switching device 42.

[0079] The high-pressure liquid refrigerant flowing into the third opening-closing valve 53 enters the first heat medium heat exchanger 1, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant flowing into the first heat medium heat exchanger 1 transfers heat to a heat medium and is transformed into high-pressure liquid refrigerant while heating the heat medium. The high-pressure liquid refrigerant flowing out of the first heat medium heat exchanger 1 flows into the first expansion device 21 and is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant. Likewise, the high-pressure liquid refrigerant flowing into the fourth opening-closing valve 54 enters the second heat medium heat exchanger 2, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant flowing into the second heat medium heat exchanger 2 transfers heat to a heat medium and is transformed into high-pressure liquid refrigerant while heating the heat medium. The high-pressure liquid refrigerant flowing out of the second heat medium heat exchanger 2 flows into the second expansion device 22 and is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant.

[0080] The low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the first expansion device 21 and the low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 join together at the node b and the joined refrigerant flows into the outdoor heat exchanger 4, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant then receives heat from outdoor air and is transformed into low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the outdoor heat exchanger 4 passes through the first flow switching device 41 and is sucked into the compressor 14 again.

[0081] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then heated by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0082] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then heated by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0083] While the refrigeration cycle apparatus 200 is operating in the heating only operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.Heating Main Operation Mode

[0084] FIG. 4 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in the heating main operation mode. The heating main operation mode will be explained below with reference to FIG. 4 through illustration of an example in which the heat load unit 202 storing the load-side heat exchanger 3a performs the cooling operation and the heat load unit 202 storing the load-side heat exchanger 3b performs the heating operation. In other words, FIG. 4 illustrates an example in which a cooling energy load is generated in the load-side heat exchanger 3a and a heating energy load is generated in the load-side heat exchanger 3b.

[0085] In the heating main operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant suction inlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant discharge outlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the fourth opening-closing valve 54 to be in the open state and sets the second opening-closing valve 52 and the third opening-closing valve 53 to be in the closed state. The controller 210 also switches the flow path of the first flow switching mechanism 71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0086] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 flows into the fourth opening-closing valve 54 via the second flow switching device 42. The high-pressure liquid refrigerant flowing into the fourth opening-closing valve 54 enters the second heat medium heat exchanger 2, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant flowing into the second heat medium heat exchanger 2 transfers heat to a heat medium and is transformed into high-pressure liquid refrigerant while heating the heat medium. The high-pressure liquid refrigerant flowing out of the second heat medium heat exchanger 2 flows into the second expansion device 22 and is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant.

[0087] The low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 branches off at the node b. Part of the low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 passes through the first expansion device 21 and flows into the first heat medium heat exchanger 1, which is functioning as an evaporator. The remaining part of the low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 flows into the outdoor heat exchanger 4, which is functioning as an evaporator.

[0088] The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the first heat medium heat exchanger 1 receives heat from the heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium. The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the outdoor heat exchanger 4 receives heat from outdoor air and is transformed into low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the heat medium heat exchanger 1 passes through the first opening-closing valve 51 and flows toward the node c. The low-pressure gas refrigerant flowing out of the outdoor heat exchanger 4 passes through the first flow switching device 41 and also flows toward the node c. These low-pressure gas refrigerants then join together at the node c and the joined refrigerant is sucked into the compressor 14 again.

[0089] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0090] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then heated by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0091] While the refrigeration cycle apparatus 200 is operating in the heating main operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.

[0092] As described above, the refrigeration cycle apparatus 200 according to Embodiment 1 includes a heat source unit 201. The heat source unit 201 includes a heat medium heat exchanger in which refrigerant circulating in a refrigerant circuit 100 and a heat medium, which is a medium different from the refrigerant, exchange heat. The heat source unit 201 supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit 201. The refrigeration cycle apparatus 200 also includes a heat medium circuit 110 in which the heat medium supplied from the heat source unit 201 circulates. The heat medium circuit 110 includes multiple load-side heat exchangers and a switching mechanism 70 configured to switch the distribution state of the heat medium to flow into and out of each of the load-side heat exchangers. The refrigeration cycle apparatus 200 also includes a relay unit 203 storing the switching mechanism 70 therein.

[0093] In the refrigeration cycle apparatus 200 configured as described above, the pipe to be installed on-site, which is equivalent to the main pipe of a known refrigeration cycle apparatus, is a pipe that connects the heat source unit and the relay unit. Accordingly, in the refrigeration cycle apparatus 200 configured as described above, the pipe to be installed on-site can be made shorter than the main pipe of the known refrigeration cycle apparatus. The on-site installation time of the refrigeration cycle apparatus 200 can thus be reduced compared with before.Embodiment 2

[0094] By adding a bypass circuit to be discussed in Embodiment 2 to the refrigeration cycle apparatus 200 in Embodiment 1, the reliability of the refrigeration cycle apparatus 200 is improved. Note that points similar to Embodiment 1 will not be described in Embodiment 2 and that elements in Embodiment 2 executing functions similar to those in Embodiment 1 are designated by like reference numerals in Embodiment 1.

[0095] FIGS. 5 and 6 are diagrams illustrating an example of a circuit configuration of the refrigeration cycle apparatus according to Embodiment 2. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling only operation mode. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling main operation mode.

[0096] The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 2 includes a bypass circuit 8. The bypass circuit 8 connects a portion of the first circuit 111 between the first heat medium heat exchanger 1 and the first pump 6 and a portion of the second circuit 112 between the second heat medium heat exchanger 2 and the second pump 7 with each other. In other words, one end of the bypass circuit 8 is connected to the portion of the first circuit 111 between the first heat medium heat exchanger 1 and the first pump 6, while the other end of the bypass circuit 8 is connected to the portion of the second circuit 112 between the second heat medium heat exchanger 2 and the second pump 7. The bypass circuit 8 is stored in the relay unit 203. Hereinafter, the position at which the bypass circuit 8 is connected to the portion of the first circuit 111 between the first heat medium heat exchanger 1 and the first pump 6 will be called a node e.

[0097] While the heat medium heat exchanger is functioning as an evaporator, if the temperature of the refrigerant flowing through the heat medium heat exchanger becomes excessively low, the heat medium may reach the freezing point of water and be frozen within the heat medium heat exchanger. To address this issue, when a preset operating condition is satisfied, the controller 210 of the refrigeration cycle apparatus 200 executes the freeze protection operation to prevent the heat medium from being frozen within the heat medium heat exchanger. The operating condition is, for example, a condition that the temperature of the refrigerant flowing into the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a first preset temperature. The operating condition is, for example, a condition that the temperature of the heat medium flowing out of the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a second preset temperature. The pressure of the refrigerant flowing into the heat medium heat exchanger, which is functioning as an evaporator, and the pressure of the refrigerant flowing out of the heat medium heat exchanger, which is functioning as an evaporator, are correlated with the evaporating temperature of the refrigerant flowing through this heat medium heat exchanger. Hence, as the operating condition, a condition that the pressure of the refrigerant flowing into the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a preset pressure, for example, may be employed. As the operating condition, a condition that the pressure of the refrigerant flowing out of the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a preset pressure, for example, may be employed.

[0098] In one example, the refrigeration cycle apparatus 200 includes a sensor 81, which is a temperature sensor or a pressure sensor, at a position between the first expansion device 21 and the first heat medium heat exchanger 1 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 81, whether the first heat medium heat exchanger 1, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 82, which is a pressure sensor, at a position between the first heat medium heat exchanger 1 and the first opening-closing valve 51 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 82, whether the first heat medium heat exchanger 1, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation.

[0099] In one example, the refrigeration cycle apparatus 200 includes a sensor 83, which is a temperature sensor or a pressure sensor, at a position between the second expansion device 22 and the second heat medium heat exchanger 2 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 83, whether the second heat medium heat exchanger 2, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 84, which is a pressure sensor, at a position between the second heat medium heat exchanger 2 and the second opening-closing valve52 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 84, whether the second heat medium heat exchanger 2, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation.

[0100] In one example, the refrigeration cycle apparatus 200 includes a sensor 85, which is a pressure sensor, at a position between the node c and the suction inlet of the compressor 14 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 85, whether any of the heat medium heat exchangers that is functioning as an evaporator satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 86, which is a temperature sensor, at a position between the first heat medium heat exchanger 1 and the first flow switching mechanism 71 in the heat medium circuit 110. This enables the controller 210 to detect, based on the detection value of the sensor 86, whether the first heat medium heat exchanger 1, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 87, which is a temperature sensor, at a position between the second heat medium heat exchanger 2 and the third flow switching mechanism 73 in the heat medium circuit 110. This enables the controller 210 to detect, based on the detection value of the sensor 87, whether the second heat medium heat exchanger 2, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation.

[0101] It is not essential that the refrigeration cycle apparatus 200 includes all the above-described sensors 81 through 87. Among the sensors 81 through 87, necessary sensors may be selected so that the controller 210 can detect whether the corresponding heat medium heat exchanger satisfies the operating condition.

[0102] Subsequently, the operation of the refrigeration cycle apparatus 200 will be described below by referring to a flow of refrigerant and that of a heat medium. In the following description, the operation of the refrigeration cycle apparatus 200 will be explained through illustration of the freeze protection operation in the cooling only operation mode and that in the cooling main operation mode. The freeze protection operation in the cooling only operation mode and that in the cooling main operation mode will be discussed through illustration of an example in which the first heat medium heat exchanger 1 satisfies the operating condition for performing the freeze protection operation.Freeze Protection Operation in Cooling Only Operation Mode

[0103] In the state in which the refrigeration cycle apparatus 200 is operating in the cooling only operation mode as shown in FIG. 1, if the first heat medium heat exchanger 1 is found to satisfy the operating condition for performing the freeze protection operation, the refrigeration cycle apparatus 200 executes the freeze protection operation as illustrated in FIG. 5.

[0104] The controller 210 sets the second opening-closing valve 52 to be in the closed state. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the load-side heat exchanger 3b communicates with the pipe connecting the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other. The controller 210 may also increase the opening degree of the first expansion device 21 to raise the temperature of the refrigerant to flow into the first heat medium heat exchanger 1. Hereinafter, a portion at which the pipe extending from the third flow switching mechanism 73 is connected to the pipe connecting the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other will be called a node d. Hereinafter, a portion at which the pipe extending from the fourth flow switching mechanism 74 is connected to the pipe connecting the second flow switching mechanism 72 and the load-side heat exchanger 3a with each other will be called a node f.

[0105] In the freeze protection operation in the cooling only operation mode, the flow of refrigerant in the refrigerant circuit 100 is changed from the state in FIG. 1 in the following manner. As a result of the second opening-closing valve 52 being set in the closed state, the flow of the refrigerant to enter the second heat medium heat exchanger 2 is interrupted. That is, the refrigerant does not flow through the second heat medium heat exchanger 2. Other than that, the flow of the refrigerant is similar to that in FIG. 1.

[0106] In the freeze protection operation in the cooling only operation mode, the flow of a heat medium in the heat medium circuit 110 is changed from the state in FIG. 1 in the following manner. As a result of the flow path of the third flow switching mechanism 73 being switched as described above, the flow of the heat medium from the second heat medium heat exchanger 2 into the load-side heat exchanger 3b is interrupted. This prevents the heat medium from flowing through the second heat medium heat exchanger 2. Instead, the heat medium flows from the first heat medium heat exchanger 1 to the load-side heat exchanger 3b.

[0107] This will be described in greater detail. The heat medium discharged from the second pump 7 passes through the bypass circuit 8 and joins the heat medium discharged from the first pump 6 at the node e. The joined heat medium flows into the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then branches off at the node d. Part of the heat medium passing through the first flow switching mechanism 71 flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The remaining heat medium passing through the first flow switching mechanism 71 passes through the second flow switching mechanism 72.

[0108] The heat medium having entered the load-side heat exchanger 3a receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a enters the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6. Meanwhile, the heat medium passing through the second flow switching mechanism 72 flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7.Freeze Protection Operation in Cooling Main Operation Mode

[0109] In the state in which the refrigeration cycle apparatus 200 is operating in the cooling main operation mode as shown in FIG. 2, if the first heat medium heat exchanger 1 is found to satisfy the operating condition for performing the freeze protection operation, the refrigeration cycle apparatus 200 executes the freeze protection operation as illustrated in FIG. 6.

[0110] The controller 210 sets the fourth opening-closing valve 54 to be in the closed state. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the load-side heat exchanger 3b communicates with the pipe connecting the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the second pump 7 communicates with the pipe connecting the second flow switching mechanism 72 and the load-side heat exchanger 3a with each other. The controller 210 may also increase the opening degree of the first expansion device 21 to raise the temperature of the refrigerant to flow into the first heat medium heat exchanger 1.

[0111] In the freeze protection operation in the cooling main operation mode, the flow of refrigerant in the refrigerant circuit 100 is changed from the state in FIG. 2 in the following manner. As a result of the fourth opening-closing valve 54 being set in the closed state, the flow of the refrigerant to enter the second heat medium heat exchanger 2 is interrupted. That is, the refrigerant does not flow through the second heat medium heat exchanger 2. Other than that, the flow of the refrigerant is similar to that in FIG. 2.

[0112] In the freeze protection operation in the cooling main operation mode, the flow of a heat medium in the heat medium circuit 110 is changed from the state in FIG. 2 in the following manner. As a result of the flow path of the third flow switching mechanism 73 being switched as described above, the flow of the heat medium from the second heat medium heat exchanger 2 into the load-side heat exchanger 3b is interrupted. This prevents the heat medium from flowing through the second heat medium heat exchanger 2. As a result of the flow path of the fourth flow switching mechanism 74 being switched as described above, the heat medium does not flow through the load-side heat exchanger 3b, and instead, the heat medium flowing out of the load-side heat exchanger 3a is sucked into the second pump 7.

[0113] This will be described in greater detail. The heat medium discharged from the second pump 7 passes through the bypass circuit 8 and joins the heat medium discharged from the first pump 6 at the node e. The joined heat medium flows into the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium having entered the load-side heat exchanger 3a receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a enters the relay unit 203.

[0114] The heat medium 3a having entered the relay unit 203 branches off at the node f. Part of the heat medium having entered the relay unit 203 passes through the second flow switching mechanism 72 and is sucked into the first pump 6. The remaining heat medium having entered the relay unit 203 passes through the fourth flow switching mechanism 74 and is sucked into the second pump 7.

[0115] As described above, the refrigeration cycle apparatus 200 according to Embodiment 2 includes the bypass circuit 8 and thus achieves the following advantages in addition to those of Embodiment 1.

[0116] When performing the freeze protection operation, while allowing the heat load unit 202 that is performing the cooling operation to continue it, the refrigeration cycle apparatus 200 of Embodiment 2 causes a heat medium discharged from the first pump 6 and that from the second pump 7 to flow through the heat medium heat exchanger that has satisfied the operating condition for performing the freeze protection operation. As a result of the heat medium discharged from the first pump 6 and that from the second pump 7 to flow through this heat medium heat exchanger, the flow rate of the heat medium in this heat medium heat exchanger is increased, thereby making it possible to prevent the heat medium from being frozen in the heat medium heat exchanger. That is, by performing the freeze protection operation, the refrigeration cycle apparatus 200 of Embodiment 2 can prevent the heat medium from being frozen in the heat medium heat exchanger while allowing the heat load unit 202 that is performing the cooling operation to continue it.Embodiment 3

[0117] By adding an opening-closing valve to be discussed in Embodiment 3 to the bypass circuit 8 of the refrigeration cycle apparatus 200 in Embodiment 2, the degradation of the performance of the refrigeration cycle apparatus 200 is suppressed. Note that points similar to Embodiment 1 or 2 will not be described in Embodiment 3 and that elements in Embodiment 3 executing functions similar to those in Embodiment 1 or 2 are designated by like reference numerals in Embodiment 1 or 2.

[0118] FIGS. 7 and 8 are diagrams illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 3. FIG. 7 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling only operation mode. FIG. 8 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling main operation mode.

[0119] The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 3 includes an opening-closing valve 9 that is provided in the bypass circuit 8 to open and close the bypass circuit 8. The open / closed state of the opening-closing valve 9 is controlled by the controller 210.

[0120] The refrigeration cycle apparatus 200 of Embodiment 3 is operated as follows. While the refrigeration cycle apparatus 200 is not performing the freeze protection operation, it sets the opening-closing valve 9 to be in the closed state. While the refrigeration cycle apparatus 200 is performing the freeze protection operation, it sets the opening-closing valve 9 to be in the open state.

[0121] It is now assumed that the refrigeration cycle apparatus 200 including the bypass circuit 8 is operating in the cooling main operation mode or in the heating main operation mode. In other words, it is assumed that the refrigeration cycle apparatus 200 including the bypass circuit 8 is cooling a heat medium in one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 and is heating a heat medium in the other one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2. That is, in the heat medium circuit 110 of the refrigeration cycle apparatus 200, the temperature of the heat medium circulating in the first circuit 111 and that in the second circuit 112 are different from each other. It is also assumed that, in the heat medium circuit 110, the pressure of the heat medium discharged from the first pump 6 provided in the first circuit 111 and that from the second pump 7 provided in the second circuit 112 are different from each other. In such operating conditions, the following phenomenon may occur if the opening-closing valve 9 is not provided in the bypass circuit 8. The heat medium may pass through the bypass circuit 8 and flow from one of the first circuit 111 and the second circuit 112 to the other one of the first circuit 111 and the second circuit 112. This may lead to the degradation of the performance of the refrigeration cycle apparatus 200.

[0122] The refrigeration cycle apparatus 200 of Embodiment 3 can address the above-described issue by setting the opening-closing valve 9 to be in the closed state when it is not performing the freeze protection operation. That is, the refrigeration cycle apparatus 200 of Embodiment 3 can suppress the degradation of the performance, which would be caused by the provision of the bypass circuit 8.Embodiment 4

[0123] By adding an air purge valve to be discussed in Embodiment 4 to the bypass circuit 8 of the refrigeration cycle apparatus 200 in Embodiment 2 or 3, the on-site installation of the refrigeration cycle apparatus 200 is facilitated. Note that points similar to any of Embodiment 1 through Embodiment 3 will not be described in Embodiment 4 and that elements in Embodiment 4 executing functions similar to those in any of Embodiment 1 through Embodiment 3 are designated by like reference numerals in Embodiment 1 through Embodiment 3.

[0124] FIGS. 9 and 10 are diagrams illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 4. FIG. 9 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling only operation mode. FIG. 10 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling main operation mode.

[0125] The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 4 includes an air purge valve 10 provided in the bypass circuit 8. The air purge valve 10 is opened when air purging from the heat medium circuit 110 is performed. The air purge valve 10 is closed at other times. The air purge valve 10 is opened and closed by an operator, for example.

[0126] When performing the on-site installation of the refrigeration cycle apparatus 200, the heat source unit 201, the relay unit 203, and the heat load units 202 are installed at predetermined locations. Then, the heat source unit 201 and the relay unit 203 connect to each other with a pipe, and the relay unit 203 and the heat load units 202 connect to each other with a pipe. A heat medium is then enclosed in the heat medium circuit 110. At this time, it is necessary to purge air from the heat medium circuit 110.

[0127] If the refrigeration cycle apparatus 200 does not include the bypass circuit 8 and the air purge valve 10, air purging from the heat medium circuit 110 is performed in the following manner, for example. The flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is first switched so that the load-side heat exchangers 3a and 3b form the first circuit 111. In other words, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b communicate with the first heat medium heat exchanger 1. Air purging from the first circuit 111 is then carried out. Then, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b form the second circuit 112. In other words, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b communicate with the second heat medium heat exchanger 2. Then, air purging from the second circuit 112 is carried out.

[0128] In contrast, in the heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 4, the first circuit 111 and the second circuit 112 communicate with each other by the bypass circuit 8. With this configuration of the heat medium circuit 110 of the refrigeration cycle apparatus 200 of Embodiment 4, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b form the first circuit 111 or the second circuit 112. In other words, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b communicate with the first heat medium heat exchanger 1 or the second heat medium heat exchanger 2. Then, the air purge valve 10 is opened. As a result, the refrigeration cycle apparatus 200 of Embodiment 4 can purge air from the heat medium circuit 110 at one time without the need to switch the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 again. This facilitates the on-site installation of the refrigeration cycle apparatus 200 of Embodiment 4.Embodiment 5

[0129] The refrigeration cycle apparatus 200 of Embodiment 1 through Embodiment 4 include one heat source unit. That is, the refrigeration cycle apparatus 200 of Embodiment 1 through Embodiment 4 include the heat source unit 201 as the heat source unit. However, the refrigeration cycle apparatus may include multiple heat source units. Note that points similar to any of Embodiment 1 through Embodiment 4 will not be described in Embodiment 5 and that elements in Embodiment 5 executing functions similar to those in any of Embodiment 1 through Embodiment 4 are designated by like reference numerals in Embodiment 1 through Embodiment 4.

[0130] FIG. 11 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 5.

[0131] As the heat source unit, the refrigeration cycle apparatus 200 of Embodiment 5 includes a first heat source unit 201a storing the first heat medium heat exchanger 1 therein and a second heat source unit 201b storing the second heat medium heat exchanger 2 therein.

[0132] The refrigerant circuit 100 stored in the first heat source unit 201a is configured as follows, for example. The compressor 14, the outdoor heat exchanger 4, an expansion device 20, and the first heat medium heat exchanger 1 are connected to each other by a refrigerant pipe in a ring-like shape so as to form the refrigerant circuit 100 stored in the first heat source unit 201a. The expansion device 20 is configured similarly to the first expansion device 21 and the second expansion device 22. That is, the expansion device 20 has a function as a reducing valve or an expansion valve and is used for expanding the refrigerant to reduce the pressure of the refrigerant.

[0133] The refrigerant circuit 100 stored in the first heat source unit 201a includes a flow switching device 40, which is a four-way valve, for example. The flow switching device 40 changes the flow path to switch the heat exchanger to be connected to the refrigerant discharge outlet of the compressor 14 and also to switch the heat exchanger to be connected to the refrigerant suction inlet of the compressor 14. More specifically, by the flow switching device 40, the refrigerant discharge outlet of the compressor 14 is connected to one of the outdoor heat exchanger 4 and the first heat medium heat exchanger 1, while the refrigerant suction inlet of the compressor 14 is connected to the other one of the outdoor heat exchanger 4 and the first heat medium heat exchanger 1. By the provision of the flow switching device 40, the first heat medium heat exchanger 1 can function as a condenser and also as an evaporator.

[0134] The refrigerant circuit 100 stored in the second heat source unit 201b is configured similarly to that stored in the first heat source unit 201a, except that it includes the second heat medium heat exchanger 2 instead of the first heat medium heat exchanger 1.

[0135] The relay unit 203, the heat load units 202, and the heat medium circuit 110 are configured, as in one of Embodiment 1 through Embodiment 4.

[0136] With the heat source unit configured as in Embodiment 5, too, the refrigeration cycle apparatus 200 can obtain the same advantages as those in Embodiment 1 through Embodiment 4.REFERENCE SIGNS LIST1: first heat medium heat exchanger, 2: second heat medium heat exchanger, 3a: load-side heat exchanger, 3b: load-side heat exchanger, 4: outdoor heat exchanger, 5: outdoor fan, 6: first pump, 7: second pump, 8: bypass circuit, 9: opening-closing valve, 10: air purge valve, 14: compressor, 20: expansion device, 21: first expansion device, 22: second expansion device, 40: flow switching device, 41: first flow switching device, 42: second flow switching device, 51: first opening-closing valve, 52: second opening-closing valve, 53: third opening-closing valve, 54: fourth opening-closing valve, 70:

[0138] switching mechanism, 71: first flow switching mechanism, 72: second flow switching mechanism, 73: third flow switching mechanism, 74: fourth flow switching mechanism, 81: sensor, 82: sensor, 83: sensor, 84: sensor, 85: sensor, 86: sensor, 87: sensor, 100: refrigerant circuit, 110: heat medium circuit, 111: first circuit, 112: second circuit, 200: refrigeration cycle apparatus, 201: heat source unit, 201a: first heat source unit, 201b: second heat source unit, 202: heat load unit, 203: relay unit, 210: controller, a: node, b: node, c: node, d: node, e: node, f: node

Examples

embodiment 1

[0021]FIG. 1 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 1 that is operating in a cooling only operation mode. The solid-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of refrigerant. The broken-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of a heat medium. In FIGS. 1 through 11, a flow path in the open state is indicated by the corresponding valve or mechanism with a white fill, while a flow path in the closed state is indicated by the corresponding valve or mechanism with a black fill.

[0022]A refrigeration cycle apparatus 200 includes a chiller-type heat source unit 201 and a heat medium circuit 110 in which a heat medium supplied from the heat source unit 201 circulates.

[0023]The heat source unit 201 includes a refrigerant circuit 100 in which refrigerant circulates and a heat medium he...

embodiment 2

[0094]By adding a bypass circuit to be discussed in Embodiment 2 to the refrigeration cycle apparatus 200 in Embodiment 1, the reliability of the refrigeration cycle apparatus 200 is improved. Note that points similar to Embodiment 1 will not be described in Embodiment 2 and that elements in Embodiment 2 executing functions similar to those in Embodiment 1 are designated by like reference numerals in Embodiment 1.

[0095]FIGS. 5 and 6 are diagrams illustrating an example of a circuit configuration of the refrigeration cycle apparatus according to Embodiment 2. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling only operation mode. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling main operation mode.

[0096]The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 2 in...

embodiment 3

[0117]By adding an opening-closing valve to be discussed in Embodiment 3 to the bypass circuit 8 of the refrigeration cycle apparatus 200 in Embodiment 2, the degradation of the performance of the refrigeration cycle apparatus 200 is suppressed. Note that points similar to Embodiment 1 or 2 will not be described in Embodiment 3 and that elements in Embodiment 3 executing functions similar to those in Embodiment 1 or 2 are designated by like reference numerals in Embodiment 1 or 2.

[0118]FIGS. 7 and 8 are diagrams illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 3. FIG. 7 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling only operation mode. FIG. 8 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling main operation mode.

[0119]The heat medium circuit 1...

TECHNICAL FIELD

[0001] The present disclosure relates to a refrigeration cycle apparatus.BACKGROUND ART

[0002] Hitherto, a refrigeration cycle apparatus including a chiller-type heat source unit is known. The chiller-type heat source unit causes refrigerant circulating within a refrigerant circuit and a heat medium, which is a medium different from the refrigerant, to exchange heat in a heat medium heat exchanger. The heat source unit then supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit. In addition to the chiller-type heat source unit, the refrigeration cycle apparatus also includes a heat medium circuit in which the heat medium supplied from the heat source unit circulates. As the refrigeration cycle apparatus including a chiller-type heat source unit, a refrigeration cycle apparatus including multiple load-side heat exchangers in a heat medium circuit has also been proposed. For example, Patent Literature 1 discloses that a refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers is used as an air-conditioning apparatus as an application example. That is, the refrigeration cycle apparatus disclosed in Patent Literature 1 uses the multiple load-side heat exchangers as an indoor heat exchanger.

[0003] In a known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, a heat medium circuit is configured as follows. The heat medium circuit includes a main pipe that allows a heat medium flowing out of the heat source unit to flow therethrough and returns the heat medium to the heat source unit. Each of the load-side heat exchangers is connected to the main pipe via a branch pipe. The distribution state of the heat medium to flow into and out of each of the load-side heat exchangers is switched by a switching mechanism provided in the branch pipe connected to the corresponding load-side heat exchanger. That is, the switching mechanisms each provided in the branch pipe connected to the corresponding load-side heat exchanger each perform a switching operation to determine whether to allow the heat medium to flow into and out of the corresponding load-side heat exchanger.CITATION LISTPatent Literature

[0004] Patent Literature 1: Japanese Unexamined Patent Application Publication No. H4-214134SUMMARY OF INVENTIONTechnical Problem

[0005] When performing on-site installation of the above-described type of known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, the main pipe of the heat medium circuit is laid to pass by the vicinity of each of the load-side heat exchangers. Each of the load-side heat exchangers is connected to a portion of the main pipe, which is disposed near the load-side heat exchanger, via a branch pipe. Hence, this type of known refrigeration cycle apparatus requires a long main pipe. Additionally, heat mediums flowing through the individual load-side heat exchangers join together and flow through the main pipe. To reduce pressure loss produced by the heat medium flowing through the main pipe, the main pipe needs to be thick. That is, for the above-described type of known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, a long, thick main pipe needs to be installed on-site. It thus takes time to install this type of known refrigeration cycle apparatus on-site.

[0006] The present disclosure has been made to solve the above-described problem. It is an object of the disclosure to provide a refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers that makes it possible to reduce its on-site installation time compared with before.Solution to Problem

[0007] A refrigeration cycle apparatus according to an embodiment of the present disclosure includes a heat source unit. The heat source unit includes a heat medium heat exchanger. Refrigerant circulating in a refrigerant circuit and a heat medium, which is a medium different from the refrigerant, exchange heat in the heat medium heat exchanger. The heat source unit supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit. The refrigeration cycle apparatus includes a heat medium circuit in which the heat medium supplied from the heat source unit circulates. The heat medium circuit includes multiple load-side heat exchangers and a switching mechanism configured to switch a distribution state of the heat medium to flow into and out of each of the load-side heat exchangers. The refrigeration cycle apparatus also includes a relay unit storing the switching mechanism therein.Advantageous Effects of Invention

[0008] In the refrigeration cycle apparatus according to an embodiment of the present disclosure, the pipe to be installed on-site, which is equivalent to the main pipe of a known refrigeration cycle apparatus, is a pipe that connects a heat source unit and a relay unit. In the refrigeration cycle apparatus according to an embodiment of the disclosure, therefore, the pipe to be installed on-site can be made shorter than the main pipe of the known refrigeration cycle apparatus. Hence, the on-site installation time of the refrigeration cycle apparatus according to an embodiment of the disclosure can be reduced compared with before.BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 1 that is operating in a cooling only operation mode.

[0010] FIG. 2 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in a cooling main operation mode.

[0011] FIG. 3 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in a heating only operation mode.

[0012] FIG. 4 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in a heating main operation mode.

[0013] FIG. 5 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 2.

[0014] FIG. 6 is a diagram illustrating an example of the circuit configuration of the refrigeration cycle apparatus according to Embodiment 2.

[0015] FIG. 7 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 3.

[0016] FIG. 8 is a diagram illustrating an example of the circuit configuration of the refrigeration cycle apparatus according to Embodiment 3.

[0017] FIG. 9 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 4.

[0018] FIG. 10 is a diagram illustrating an example of the circuit configuration of the refrigeration cycle apparatus according to Embodiment 4.

[0019] FIG. 11 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 5.DESCRIPTION OF EMBODIMENTS

[0020] An example of a refrigeration cycle apparatus according to an embodiment of the disclosure will be described below with reference to the drawings and other things through illustration of Embodiment 1 through Embodiment 5. In the drawings including FIG. 1, elements designated by the same reference sign are the same element or corresponding elements. This applies to the whole text in Embodiment 1 through Embodiment 5. The refrigeration cycle apparatus according to an embodiment of the disclosure described through illustration of Embodiment 1 through Embodiment 5 is only an example. The refrigeration cycle apparatus of an embodiment of the disclosure is not limited to the modes described in the specification. In Embodiment 1 through Embodiment 5, the refrigeration cycle apparatus of an embodiment of the disclosure is used as an air-conditioning apparatus as an application example.Embodiment 1

[0021] FIG. 1 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 1 that is operating in a cooling only operation mode. The solid-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of refrigerant. The broken-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of a heat medium. In FIGS. 1 through 11, a flow path in the open state is indicated by the corresponding valve or mechanism with a white fill, while a flow path in the closed state is indicated by the corresponding valve or mechanism with a black fill.

[0022] A refrigeration cycle apparatus 200 includes a chiller-type heat source unit 201 and a heat medium circuit 110 in which a heat medium supplied from the heat source unit 201 circulates.

[0023] The heat source unit 201 includes a refrigerant circuit 100 in which refrigerant circulates and a heat medium heat exchanger. In other words, the refrigerant circuit 100 and the heat medium heat exchanger are stored in the heat source unit 201. The heat medium heat exchanger functions as a condenser or an evaporator in the refrigerant circuit 100 and causes the refrigerant circulating in the refrigerant circuit 100 and a heat medium, which is a medium different from the refrigerant, to exchange heat therein. The heat source unit 201 supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit 201.

[0024] The type of refrigerant to circulate in the refrigerant circuit 100 is not limited to a specific type. In one example, the refrigerant to circulate in the refrigerant circuit 100 is olefin-based refrigerant, ethylene-based refrigerant, ethane-based refrigerant, propane, or dimethyl ether. In another example, the refrigerant to circulate in the refrigerant circuit 100 is a mixed refrigerant of at least two of olefin-based refrigerant, ethylene-based refrigerant, ethane-based refrigerant, propane, and dimethyl ether. The olefin-based refrigerant is tetrafluoropropene, for example, such as HFO1234yf and HFO1234ze (E). The ethylene-based refrigerant is difluoroethylene, for example.

[0025] The ethane-based refrigerant is tetrafluoroethane, for example. The type of heat medium to exchange heat with the refrigerant in the heat medium heat exchanger is not limited to a specific type, either. Examples of the heat medium are brine, antifreeze, and water. Brine contains calcium chloride solution, sodium chloride solution, magnesium chloride solution, or ethylene glycol, for example.

[0026] In Embodiment 1, as the heat medium heat exchanger, a first heat medium heat exchanger 1 and a second heat medium heat exchanger 2 are provided. The refrigeration cycle apparatus 200 may include only one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2. That is, the refrigeration cycle apparatus 200 may include only one heat medium heat exchanger. In Embodiment 1, when one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 functions as a condenser, the other one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 can function as an evaporator. That is, the heat source unit 201 of Embodiment 1 can supply a heated heat medium and a cooled heat medium at the same time. Because of this configuration, in Embodiment 1, the refrigerant circuit 100 is configured as follows, for example.

[0027] The refrigerant circuit 100 includes a compressor 14, a first flow switching device 41, a second flow switching device 42, an outdoor heat exchanger 4, a first expansion device 21, a second expansion device 22, a first opening-closing valve 51, a second opening-closing valve 52, a third opening-closing valve 53, and a fourth opening-closing valve 54. The first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 also form part of the refrigerant circuit 100.

[0028] The compressor 14 sucks refrigerant, compresses it into a high-temperature high-pressure state, and discharges the resulting refrigerant. As the compressor 14, a rotary compressor, a scroll compressor, a screw compressor, or a reciprocating compressor, for example, can be used. The refrigerant discharge outlet of the compressor 14 is connected to the first flow switching device 41 and the second flow switching device 42. More specifically, a refrigerant pipe connected to the refrigerant discharge outlet of the compressor 14 branches off at a node a and is divided into two refrigerant pipes. One of the divided refrigerant pipes is connected to the first flow switching device 41, while the other one of the divided refrigerant pipes is connected to the second flow switching device 42. The refrigerant suction inlet of the compressor 14 is also connected to the first flow switching device 41 and the second flow switching device 42. More specifically, the refrigerant pipe connected to the refrigerant suction inlet of the compressor 14 branches off and is divided into two refrigerant pipes. One of the divided refrigerant pipes is connected to the first flow switching device 41, while the other one of the divided refrigerant pipes is connected to the second flow switching device 42.

[0029] The first flow switching device 41 is a four-way valve, for example. The first flow switching device 41 switches a flow regarding whether to allow the refrigerant discharge outlet of the compressor 14 to communicate with the outdoor heat exchanger 4. The first flow switching device 41 also switches a flow regarding whether to allow the refrigerant suction inlet of the compressor 14 to communicate with the outdoor heat exchanger 4. The second flow switching device 42 is a four-way valve, for example.

[0030] The second flow switching device 42 switches a flow regarding whether to allow the refrigerant discharge outlet of the compressor 14 to communicate with the third opening-closing valve 53 and the fourth opening-closing valve 54. The first flow switching device 41 switches a flow regarding whether to allow the refrigerant suction inlet of the compressor 14 to communicate with the third opening-closing valve 53 and the fourth opening-closing valve 54.

[0031] The outdoor heat exchanger 4 functions as an evaporator or a condenser. When the outdoor heat exchanger 4 functions as an evaporator, it performs heat exchange between refrigerant and outdoor air flowing inside to evaporate and gasify the refrigerant. When the outdoor heat exchanger 4 functions as a condenser, it performs heat exchange between refrigerant and outdoor air flowing inside to condense and liquify the refrigerant.

[0032] In Embodiment 1, to enhance the heat exchange between the refrigerant and outdoor air in the outdoor heat exchanger 4, an outdoor fan 5 that sends outdoor air to the outdoor heat exchanger 4 is disposed adjacent to the outdoor heat exchanger 4. The outdoor fan 5 may be constituted by a propeller fan, a line flow fan (registered trademark), or a multiblade centrifugal fan, for example, based on the operating conditions, such as the flow rate and the static pressure of outdoor air to be supplied to the outdoor heat exchanger 4.

[0033] Each of the first expansion device 21 and the second expansion device 22 has a function as a reducing valve or an expansion valve and is used for expanding the refrigerant to reduce the pressure of the refrigerant. Each of the first expansion device 21 and the second expansion device 22 is an electronic expansion valve, for example, that can control the flow rate of refrigerant. The first expansion device 21 and the second expansion device 22 are connected in parallel with the outdoor heat exchanger 4. More specifically, the refrigerant pipe connected to the outdoor heat exchanger 4 branches off at a node b and is divided into two refrigerant pipes. One of the divided refrigerant pipes is connected to the first expansion device 21, while the other one of the divided refrigerant pipes is connected to the second expansion device 22. The first expansion device 21 and the second expansion device 22 are not limited to an electronic expansion valve and may be a mechanical expansion valve using a diaphragm for the pressure receiving part. The first expansion device 21 and the second expansion device 22 may partially be constituted by a capillary tube, for example.

[0034] As discussed above, the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 each functions as a condenser or an evaporator in the refrigerant circuit 100. When the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 function as evaporators, they perform heat exchange between the refrigerant and a heat medium flowing inside to evaporate and gasify the refrigerant. In this case, the heat medium is cooled by the refrigerant. When the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 function as condensers, they perform heat exchange between the refrigerant and a heat medium flowing inside to condense and liquify the refrigerant. In this case, the heat medium is heated by the refrigerant. One end of the refrigerant flow path of the first heat medium heat exchanger 1 is connected to the first expansion device 21. One end of the refrigerant flow path of the second heat medium heat exchanger 2 is connected to the second expansion device 22.

[0035] Each of the first opening-closing valve 51, second opening-closing valve 52, third opening-closing valve 53, and fourth opening-closing valve 54 is a two-way valve, for example, and opens and closes the flow path where the corresponding opening-closing valve is installed. The first opening-closing valve 51 and the third opening-closing valve 53 are connected in parallel with the other end of the refrigerant flow path of the first heat medium heat exchanger 1. The second opening-closing valve 52 and the fourth opening-closing valve 54 are connected in parallel with the other end of the refrigerant flow path of the second heat medium heat exchanger 2. The first opening-closing valve 51 and the second opening-closing valve 52 are connected at a node c to a pipe that connects the refrigerant suction inlet of the compressor 14 and the first flow switching device 41. The third opening-closing valve 53 and the fourth opening-closing valve 54 are connected to the second flow switching device 42.

[0036] As stated above, the heat medium circuit 110 is a circuit in which a heat medium supplied from the heat source unit 201 circulates. That is, the heat medium circuit 110 is a circuit in which a heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger circulates. The heat medium circuit 110 includes multiple load-side heat exchangers and a switching mechanism 70. The switching mechanism 70 switches the distribution state of a heat medium to flow into and out of each of the load-side heat exchangers. The heat medium circuit 110 in Embodiment 1 includes load-side heat exchangers 3a and 3b as the multiple load-side heat exchangers. The switching mechanism 70 thus switches the distribution state of a heat medium to flow into and out of each of the load-side heat exchangers 3a and 3b. As stated above, the refrigeration cycle apparatus 200 according to Embodiment 1 is used as an air-conditioning apparatus. The load-side heat exchangers 3a and 3b are thus used as an indoor heat exchanger that heats or cools indoor air. The load-side heat exchangers 3a and 3b are stored in different heat load units 202 and are installed indoors, which is a space to be air-conditioned.

[0037] Using the refrigeration cycle apparatus 200 as an air-conditioning apparatus is only an application example of the refrigeration cycle apparatus 200. The refrigeration cycle apparatus 200 may be used as a device other than the air-conditioning apparatus. For example, the load-side heat exchangers 3a and 3b may be disposed under the floor and be used for floor heating. In another example, the load-side heat exchangers 3a and 3b may be used as heat exchangers for heating water stored in a hot water storage tank. In another example, the load-side heat exchangers 3a and 3b may be used as heat exchangers for cooling air within a freezer compartment.

[0038] As discussed above, the heat source unit 201 in Embodiment 1 includes the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 as the heat medium heat exchanger. The heat medium circuit 110 in Embodiment 1 thus includes a first circuit 111 that allows a heat medium to pass therethrough and to flow into the first heat medium heat exchanger 1 and a second circuit 112 that allows a heat medium to pass therethrough and to flow into the second heat medium heat exchanger 2. The switching mechanism 70 switches the distribution state of a heat medium flowing out of the first heat medium heat exchanger 1 to flow into each of the load-side heat exchangers. The switching mechanism 70 also switches the distribution state of a heat medium flowing out of the second heat medium heat exchanger 2 to flow into each of the load-side heat exchangers.

[0039] To explain the switching mechanism 70 more specifically, the switching mechanism 70 includes a first flow switching mechanism 71, a second flow switching mechanism 72, a third flow switching mechanism 73, and a fourth flow switching mechanism 74. Each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is a three-way valve, for example. However, they are not limited to a three-way valve and may be constituted by a combination of multiple two-way valves.

[0040] The first flow switching mechanism 71 is connected to the heat medium flow outlet of the first heat medium heat exchanger 1. The first flow switching mechanism 71 is also connected to the inlet of the load-side heat exchanger 3a. The first flow switching mechanism 71 is also connected to a pipe that connects the third flow switching mechanism 73 and the load-side heat exchanger 3b with each other. The first flow switching mechanism 71 allows two of the three connection locations to communicate with the first flow switching mechanism 71.

[0041] The second flow switching mechanism 72 is connected to the heat medium flow inlet of the first heat medium heat exchanger 1. A first pump 6, which will be discussed later, is installed between the second flow switching mechanism 72 and the heat medium flow inlet of the first heat medium heat exchanger 1. It can thus be said that the second flow switching mechanism 72 is connected to the first pump 6. The second flow switching mechanism 72 is also connected to the outlet of the load-side heat exchanger 3a. The second flow switching mechanism 72 is also connected to a pipe that connects the fourth flow switching mechanism 74 and the load-side heat exchanger 3b with each other. The second flow switching mechanism 72 allows two of the three connection locations to communicate with the second flow switching mechanism 72.

[0042] The third flow switching mechanism 73 is connected to the heat medium flow outlet of the second heat medium heat exchanger 2. The third flow switching mechanism 73 is also connected to a pipe that connects the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other. The third flow switching mechanism 73 is also connected to the inlet of the load-side heat exchanger 3b. The third flow switching mechanism 73 allows two of the three connection locations to communicate with the third flow switching mechanism 73.

[0043] The fourth flow switching mechanism 74 is connected to the heat medium flow inlet of the second heat medium heat exchanger 2. A second pump 7, which will be discussed later, is installed between the fourth flow switching mechanism 74 and the heat medium flow inlet of the second heat medium heat exchanger 2. It can thus be said that the fourth flow switching mechanism 74 is connected to the second pump 7. The fourth flow switching mechanism 74 is also connected to a pipe that connects the second flow switching mechanism 72 and the load-side heat exchanger 3a with each other. The fourth flow switching mechanism 74 is also connected to the outlet of the load-side heat exchanger 3b. The fourth flow switching mechanism 74 allows two of the three connection locations to communicate with the fourth flow switching mechanism 74.

[0044] The load-side heat exchanger 3a becomes part of the first circuit 111 when communicating with the first heat medium heat exchanger 1. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3a to communicate with each other also becomes part of the first circuit 111. The pipe that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3a to communicate with each other also becomes part of the first circuit 111. The load-side heat exchanger 3a becomes part of the second circuit 112 when communicating with the second heat medium heat exchanger 2. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3a to communicate with each other also becomes part of the second circuit 112. The pipe that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3a to communicate with each other also becomes part of the second circuit 112.

[0045] Likewise, the load-side heat exchanger 3b becomes part of the first circuit 111 when communicating with the first heat medium heat exchanger 1. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3b to communicate with each other also becomes part of the first circuit 111. The pipe that allows the first heat medium heat exchanger 1 and the load-side heat exchanger 3b to communicate with each other also becomes part of the first circuit 111. The load-side heat exchanger 3b becomes part of the second circuit 112 when communicating with the second heat medium heat exchanger 2. Among the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74, the flow switching mechanism that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3b to communicate with each other also becomes part of the second circuit 112. The pipe that allows the second heat medium heat exchanger 2 and the load-side heat exchanger 3b to communicate with each other also becomes part of the second circuit 112.

[0046] The refrigeration cycle apparatus 200 includes a relay unit 203. The above-described switching mechanism 70 is stored in the relay unit 203. In other words, the refrigeration cycle apparatus 200 includes the relay unit 203 in which the switching mechanism 70 is stored.

[0047] The heat medium circuit 110 in Embodiment 1 includes a pump to circulate a heat medium in the heat medium circuit 110. More specifically, the heat medium circuit 110 includes the first pump 6 disposed in the first circuit 111 and the second pump 7 disposed in the second circuit 112 as the pump. The first pump 6 is disposed at a position in the first circuit 111 at which a heat medium to return to the first heat medium heat exchanger 1 flows. The first pump 6 discharges the heat medium to return to the first heat medium heat exchanger 1. The second pump 7 is disposed at a position in the second circuit 112 at which a heat medium to return to the second heat medium heat exchanger 2 flows. The second pump 7 discharges the heat medium to return to the second heat medium heat exchanger 2. In Embodiment 1, the first pump 6 and the second pump 7 are stored in the relay unit 203.

[0048] The refrigeration cycle apparatus 200 according to Embodiment 1 includes a controller 210 that controls the operating state of the refrigeration cycle apparatus 200. More specifically, the controller 210 starts and stops the compressor 14. The controller 210 may control the rotation speed of the compressor 14 when driving it. This can adjust the amount of refrigerant to be discharged from the compressor 14. The controller 210 also switches the flow path of each of the first flow switching device 41 and the second flow switching device 42. The controller 210 also starts and stops the outdoor fan 5. The controller 210 may control the rotation speed of the outdoor fan 5 when driving it. The controller 210 also controls the opening degree of each of the first expansion device 21 and the second expansion device 22. The controller 210 also controls the open / closed state of each of the first opening-closing valve 51, second opening-closing valve 52, third opening-closing valve 53, and fourth opening-closing valve 54. The controller 210 also switches the flow path of the switching mechanism 70. That is, the controller 210 switches the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74. The controller 210 also starts and stops the first pump 6 and the second pump 7. The controller 210 may control the rotation speed of each of the first pump 6 and the second pump 7 when driving them. This can adjust the amount of refrigerant to be discharged from the first pump 6 and that from the second pump 7.

[0049] The controller 210 configured as described above is constituted by dedicated hardware or a CPU (Central Processing Unit) that executes a program stored in a memory. The CPU may also be called a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a processor.

[0050] If the controller 210 is constituted by dedicated hardware, it is a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), a FPGA (Field-Programmable Gate Array), or a combination thereof, for example. The individual functional units to be implemented by the controller 210 may be implemented by individual hardware units or by one hardware unit.

[0051] If the controller 210 is constituted by a CPU, the individual functions to be executed by the controller 210 are implemented by software, firmware, or a combination thereof. The software and firmware are described as a program and the program is stored in a memory. The CPU reads and executes the program stored in the memory to implement the individual functions of the controller 210. The memory is a volatile or non-volatile semiconductor memory, such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM, for example.

[0052] Some of the functions of the controller 210 may be implemented by dedicated hardware and some of the functions may be implemented by software or firmware. In Embodiment 1, the controller 210 is stored in the heat source unit 201. However, at least part of the controller 210 may be stored in a location other than the heat source unit 201. For example, the configuration of the controller 210 may be distributed over the heat source unit 201 and the relay unit 203 and be stored therein.

[0053] Hitherto, a refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers has been proposed. In such a known refrigeration cycle apparatus, the heat medium circuit is configured as follows. The heat medium circuit includes a main pipe that allows a heat medium flowing out of the heat source unit to flow therethrough and returns the heat medium to the heat source unit. Each of the load-side heat exchangers is connected to the main pipe via a branch pipe. The distribution state of the heat medium to flow into and out of each of the load-side heat exchangers is switched by a switching mechanism provided in the branch pipe connected to the corresponding load-side heat exchanger. That is, the switching mechanisms each provided in the branch pipe connected to the corresponding load-side heat exchanger each perform a switching operation to determine whether to allow the heat medium to flow into or out of the corresponding load-side heat exchanger.

[0054] With the above-described configuration, when performing on-site installation of the above-described type of known refrigeration cycle apparatus including a chiller-type heat source unit and multiple load-side heat exchangers, the main pipe of the heat medium circuit is laid to pass by the vicinity of each of the load-side heat exchangers. Each of the load-side heat exchangers is connected to a portion of the main pipe, which is disposed near the load-side heat exchanger, via the corresponding branch pipe. Hence, this type of known refrigeration cycle apparatus requires a long main pipe. Additionally, heat mediums flowing through the individual load-side heat exchangers join together and flow through the main pipe. To reduce pressure loss produced by the heat medium flowing through the main pipe, the main pipe needs to be thick. That is, for the above-described type of known refrigeration cycle apparatus, a long, thick main pipe needs to be installed on-site.

[0055] It thus takes time to install the above-described type of known refrigeration cycle apparatus on-site. It is also necessary to attach the switching mechanisms one by one on-site to the branch pipes connected to the corresponding load-side heat exchangers. This operation also makes the on-site installation of the refrigeration cycle apparatus time-consuming. Additionally, since the heat medium circuit of the above-described type of known refrigeration cycle apparatus includes a long, thick main tube, it also takes time to purge air from the heat medium circuit when enclosing a heat medium in the heat medium circuit. This operation also makes the on-site installation of the refrigeration cycle apparatus time-consuming. The heat medium circuit of the above-described type of known refrigeration cycle apparatus includes a long, thick main tube, and a large amount of heat medium to be enclosed in the heat medium circuit is thus required.

[0056] In contrast, the on-site installation of the refrigeration cycle apparatus 200 according to Embodiment 1 is performed as follows. The heat source unit 201, the relay unit 203, and the heat load units 202 are installed at predetermined locations. Then, the heat source unit 201 and the relay unit 203 connect to each other with a pipe, and the relay unit 203 and the heat load units 202 connect to each other with a pipe. In the refrigeration cycle apparatus 200 according to Embodiment 1, the pipe, which is equivalent to the main pipe of the heat medium circuit of the known refrigeration cycle apparatus, is the pipe that connects the heat medium heat exchanger and the switching mechanism 70. This means that the pipe that connects the heat source unit 201 and the relay unit 203 in the refrigeration cycle apparatus 200 of Embodiment 1 is part of the pipe equivalent to the main pipe of the known refrigeration cycle apparatus. The remaining portion of the pipe equivalent to the main pipe of the known refrigeration cycle apparatus is stored in the heat source unit 201 and the relay unit 203 in the refrigeration cycle apparatus 200 of Embodiment 1. This means that, when the heat source unit 201 and the relay unit 203 are installed, the installation of the remaining portion of the pipe equivalent to the main pipe of the known refrigeration cycle apparatus is completed at the same time.

[0057] In the refrigeration cycle apparatus 200 of Embodiment 1, therefore, the pipe to be installed on-site, which is equivalent to the main pipe of the known refrigeration cycle apparatus, can be made shorter than the main pipe of the heat medium circuit of the known refrigeration cycle apparatus. Hence, the on-site installation time of the refrigeration cycle apparatus 200 of Embodiment 1 can be reduced compared with before. Additionally, in the refrigeration cycle apparatus 200 of Embodiment 1, when the relay unit 203 is installed, the installation of the switching mechanism 70 is also completed. In this respect, too, the on-site installation time of the refrigeration cycle apparatus 200 of Embodiment 1 can be reduced compared with before. In the refrigeration cycle apparatus 200 of Embodiment 1, the relay unit 203 and the heat load units 202 connect to each other with a pipe, and the pipe equivalent to the main pipe of the known refrigeration cycle apparatus can thus be made shorter. In the refrigeration cycle apparatus 200 of Embodiment 1, since the pipe equivalent to the main pipe of the known refrigeration cycle apparatus can be decreased, the occurrence of pressure loss produced by a heat medium flowing through the pipe can be reduced. This also makes it possible to make the size of the pipe of the refrigeration cycle apparatus 200 of Embodiment 1 smaller than the main pipe of the known refrigeration cycle apparatus. Hence, the time to purge air from the heat medium circuit 110 when enclosing a heat medium in the heat medium circuit 110 can become shorter than before. In this respect, too, the on-site installation time of the refrigeration cycle apparatus 200 of Embodiment 1 can be reduced compared with before. In the refrigeration cycle apparatus 200 of Embodiment 1, since the pipe equivalent to the main pipe of the known refrigeration cycle apparatus can be made shorter and smaller, the amount of heat medium enclosed in the heat medium circuit 110 can also be decreased compared with before.

[0058] Subsequently, the operation of the refrigeration cycle apparatus 200 will be described below by referring to a flow of refrigerant and that of a heat medium. The refrigeration cycle apparatus 200 can operate in the cooling only operation mode, the heating only operation mode, the cooling main operation mode, and the heating main operation mode. The cooling only operation mode is an operation mode in which all the heat load units 202 perform the cooling operation. The heating only operation mode is an operation mode in which all the heat load units 202 perform the heating operation. The cooling main operation mode is an operation mode in which some heat load units 202 perform the cooling operation and some heat load units 202 perform the heating operation and the cooling load is higher than the heating load. The heating main operation mode is an operation mode in which some heat load units 202 perform the cooling operation and some heat load units 202 perform the heating operation and the heating load is higher than the cooling load.Cooling Only Operation Mode

[0059] An explanation will first be given, based on FIG. 1, of the cooling only operation mode executed by the refrigeration cycle apparatus 200. The cooling only operation mode will be explained below with reference to FIG. 1 through illustration of an example in which all the heat load units 202 perform the cooling operation. In other words, FIG. 1 illustrates an example in which a cooling energy load is generated both in the load-side heat exchangers 3a and 3b.

[0060] In the cooling only operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant discharge outlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant suction inlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the second opening-closing valve 52 to be in the open state and sets the third opening-closing valve 53 and the fourth opening-closing valve 54 to be in the closed state. The controller 210 also switches the flow path of the first flow switching mechanism71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other.

[0061] The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0062] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 flows into the outdoor heat exchanger 4, which is functioning as a condenser, via the node a and the first flow switching device 41. The high-temperature high-pressure gas refrigerant is then transformed into high-pressure liquid refrigerant while transferring heat to outdoor air. The high-pressure liquid refrigerant flowing out of the outdoor heat exchanger 4 branches off at the node b and flows into the first expansion device 21 and the second expansion device 22.

[0063] The high-pressure liquid refrigerant flowing into the first expansion device 21 is then expanded to low-temperature low-pressure two-phase gas-liquid refrigerant and flows into the first heat medium heat exchanger 1, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the first heat medium heat exchanger 1 then receives heat from a heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium. Likewise, the high-pressure liquid refrigerant flowing into the second expansion device 22 is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant and flows into the second heat medium heat exchanger 2, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the second heat medium heat exchanger 2 then receives heat from a heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium.

[0064] The low-pressure gas refrigerant flowing out of the first heat medium heat exchanger 1 passes through the first opening-closing valve 51. The low-pressure gas refrigerant flowing out of the second heat medium heat exchanger 2 passes through the second opening-closing valve 52. These low-pressure gas refrigerants pass through the node c and are sucked into the compressor 14 again.

[0065] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0066] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then cooled by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0067] While the refrigeration cycle apparatus 200 is operating in the cooling only operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.Cooling Main Operation Mode

[0068] FIG. 2 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in the cooling main operation mode. The cooling main operation mode will be explained below with reference to FIG. 2 through illustration of an example in which the heat load unit 202 storing the load-side heat exchanger 3a performs the cooling operation and the heat load unit 202 storing the load-side heat exchanger 3b performs the heating operation. In other words, FIG. 2 illustrates an example in which a cooling energy load is generated in the load-side heat exchanger 3a and a heating energy load is generated in the load-side heat exchanger 3b.

[0069] In the cooling main operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant discharge outlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant discharge outlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the fourth opening-closing valve 54 to be in the open state and sets the second opening-closing valve 52 and the third opening-closing valve 53 to be in the closed state. The controller 210 also switches the flow path of the first flow switching mechanism 71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0070] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 branches off at the node a and is divided into the refrigerant to flow into the outdoor heat exchanger 4 via the first flow switching device 41 and into the refrigerant to flow into the second flow switching device 42.

[0071] The high-temperature high-pressure gas refrigerant flowing into the outdoor heat exchanger 4, which is functioning as a condenser, is transformed into high-pressure liquid refrigerant while transferring heat to outdoor air. The high-temperature high-pressure gas refrigerant flowing into the second flow switching device 42 passes through the fourth opening-closing valve 54 and enters the second heat medium heat exchanger 2, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant having entered the second heat medium heat exchanger 2 transfers heat to the heat medium and is transformed into high-pressure liquid refrigerant or high-pressure two-phase gas-liquid refrigerant while heating the heat medium.

[0072] The refrigerant flowing out of the outdoor heat exchanger 4 flows toward the node b. The refrigerant flowing out of the second heat medium heat exchanger 2 passes through the second expansion device 22 and also flows toward the node b. These refrigerants join together at the node b and the joined refrigerant flows into the first expansion device 21. The refrigerant flowing into the first expansion device 21 is then expanded to low-temperature low-pressure two-phase gas-liquid refrigerant and flows into the first heat medium heat exchanger 1, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant then receives heat from a heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium. The low-pressure gas refrigerant flowing out of the first heat medium heat exchanger 1 passes through the first opening-closing valve 51 and is sucked into the compressor 14 again via the node c.

[0073] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0074] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then heated by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0075] While the refrigeration cycle apparatus 200 is operating in the cooling main operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.Heating Only Operation Mode

[0076] FIG. 3 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in the heating only operation mode. The heating only operation mode will be explained below with reference to FIG. 3 through illustration of an example in which all the heat load units 202 perform the heating operation. In other words, FIG. 3 illustrates an example in which a heating energy load is generated both in the load-side heat exchangers 3a and 3b.

[0077] In the heating only operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant suction inlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant discharge outlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the second opening-closing valve 52 to be in the closed state and sets the third opening-closing valve 53 and the fourth opening-closing valve 54 to be in the open state. The controller 210 also switches the flow path of the first flow switching mechanism 71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0078] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 flows into the third opening-closing valve 53 and the fourth opening-closing valve 54 via the second flow switching device 42.

[0079] The high-pressure liquid refrigerant flowing into the third opening-closing valve 53 enters the first heat medium heat exchanger 1, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant flowing into the first heat medium heat exchanger 1 transfers heat to a heat medium and is transformed into high-pressure liquid refrigerant while heating the heat medium. The high-pressure liquid refrigerant flowing out of the first heat medium heat exchanger 1 flows into the first expansion device 21 and is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant. Likewise, the high-pressure liquid refrigerant flowing into the fourth opening-closing valve 54 enters the second heat medium heat exchanger 2, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant flowing into the second heat medium heat exchanger 2 transfers heat to a heat medium and is transformed into high-pressure liquid refrigerant while heating the heat medium. The high-pressure liquid refrigerant flowing out of the second heat medium heat exchanger 2 flows into the second expansion device 22 and is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant.

[0080] The low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the first expansion device 21 and the low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 join together at the node b and the joined refrigerant flows into the outdoor heat exchanger 4, which is functioning as an evaporator. The low-temperature low-pressure two-phase gas-liquid refrigerant then receives heat from outdoor air and is transformed into low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the outdoor heat exchanger 4 passes through the first flow switching device 41 and is sucked into the compressor 14 again.

[0081] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then heated by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0082] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then heated by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0083] While the refrigeration cycle apparatus 200 is operating in the heating only operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.Heating Main Operation Mode

[0084] FIG. 4 is a diagram illustrating a flow of refrigerant and that of a heat medium when the refrigeration cycle apparatus according to Embodiment 1 is operating in the heating main operation mode. The heating main operation mode will be explained below with reference to FIG. 4 through illustration of an example in which the heat load unit 202 storing the load-side heat exchanger 3a performs the cooling operation and the heat load unit 202 storing the load-side heat exchanger 3b performs the heating operation. In other words, FIG. 4 illustrates an example in which a cooling energy load is generated in the load-side heat exchanger 3a and a heating energy load is generated in the load-side heat exchanger 3b.

[0085] In the heating main operation mode, the controller 210 switches the flow path of the first flow switching device 41 so that the refrigerant suction inlet of the compressor 14 communicates with the outdoor heat exchanger 4. The controller 210 also switches the flow path of the second flow switching device 42 so that the refrigerant discharge outlet of the compressor 14 communicates with the third opening-closing valve 53 and the fourth opening-closing valve 54. The controller 210 also sets the first opening-closing valve 51 and the fourth opening-closing valve 54 to be in the open state and sets the second opening-closing valve 52 and the third opening-closing valve 53 to be in the closed state. The controller 210 also switches the flow path of the first flow switching mechanism 71 so that the heat medium flow outlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the second flow switching mechanism 72 so that the heat medium flow inlet of the first heat medium heat exchanger 1 and the load-side heat exchanger 3a communicate with each other. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the heat medium flow outlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the heat medium flow inlet of the second heat medium heat exchanger 2 and the load-side heat exchanger 3b communicate with each other. The controller 210 also starts the compressor 14, first pump 6, second pump 7, and outdoor fan 5.

[0086] When the compressor 14 is driven, the refrigerant flows through the refrigerant circuit 100 in the following manner. The compressor 14 compresses low-temperature low-pressure refrigerant and discharges it as high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 14 flows into the fourth opening-closing valve 54 via the second flow switching device 42. The high-pressure liquid refrigerant flowing into the fourth opening-closing valve 54 enters the second heat medium heat exchanger 2, which is functioning as a condenser. The high-temperature high-pressure gas refrigerant flowing into the second heat medium heat exchanger 2 transfers heat to a heat medium and is transformed into high-pressure liquid refrigerant while heating the heat medium. The high-pressure liquid refrigerant flowing out of the second heat medium heat exchanger 2 flows into the second expansion device 22 and is expanded to low-temperature low-pressure two-phase gas-liquid refrigerant.

[0087] The low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 branches off at the node b. Part of the low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 passes through the first expansion device 21 and flows into the first heat medium heat exchanger 1, which is functioning as an evaporator. The remaining part of the low-temperature low-pressure two-phase gas-liquid refrigerant flowing out of the second expansion device 22 flows into the outdoor heat exchanger 4, which is functioning as an evaporator.

[0088] The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the first heat medium heat exchanger 1 receives heat from the heat medium and is transformed into low-pressure gas refrigerant while cooling the heat medium. The low-temperature low-pressure two-phase gas-liquid refrigerant flowing into the outdoor heat exchanger 4 receives heat from outdoor air and is transformed into low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the heat medium heat exchanger 1 passes through the first opening-closing valve 51 and flows toward the node c. The low-pressure gas refrigerant flowing out of the outdoor heat exchanger 4 passes through the first flow switching device 41 and also flows toward the node c. These low-pressure gas refrigerants then join together at the node c and the joined refrigerant is sucked into the compressor 14 again.

[0089] When the first pump 6 and the second pump 7 are driven, a heat medium flows through the heat medium circuit 110 in the following manner. The heat medium discharged from the first pump 6 flows into the heat source unit 201 and enters the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a flows into the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6 again.

[0090] The heat medium discharged from the second pump 7 flows into the heat source unit 201 and enters the second heat medium heat exchanger 2. The heat medium is then heated by the refrigerant and flows out of the second heat medium heat exchanger 2. The heat medium then flows into the relay unit 203 and passes through the third flow switching mechanism 73. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then transfers heat to indoor air and heats it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7 again.

[0091] While the refrigeration cycle apparatus 200 is operating in the heating main operation mode, the above-described cycle is repeated in the refrigerant circuit 100 and the heat medium circuit 110.

[0092] As described above, the refrigeration cycle apparatus 200 according to Embodiment 1 includes a heat source unit 201. The heat source unit 201 includes a heat medium heat exchanger in which refrigerant circulating in a refrigerant circuit 100 and a heat medium, which is a medium different from the refrigerant, exchange heat. The heat source unit 201 supplies the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to the outside of the heat source unit 201. The refrigeration cycle apparatus 200 also includes a heat medium circuit 110 in which the heat medium supplied from the heat source unit 201 circulates. The heat medium circuit 110 includes multiple load-side heat exchangers and a switching mechanism 70 configured to switch the distribution state of the heat medium to flow into and out of each of the load-side heat exchangers. The refrigeration cycle apparatus 200 also includes a relay unit 203 storing the switching mechanism 70 therein.

[0093] In the refrigeration cycle apparatus 200 configured as described above, the pipe to be installed on-site, which is equivalent to the main pipe of a known refrigeration cycle apparatus, is a pipe that connects the heat source unit and the relay unit. Accordingly, in the refrigeration cycle apparatus 200 configured as described above, the pipe to be installed on-site can be made shorter than the main pipe of the known refrigeration cycle apparatus. The on-site installation time of the refrigeration cycle apparatus 200 can thus be reduced compared with before.Embodiment 2

[0094] By adding a bypass circuit to be discussed in Embodiment 2 to the refrigeration cycle apparatus 200 in Embodiment 1, the reliability of the refrigeration cycle apparatus 200 is improved. Note that points similar to Embodiment 1 will not be described in Embodiment 2 and that elements in Embodiment 2 executing functions similar to those in Embodiment 1 are designated by like reference numerals in Embodiment 1.

[0095] FIGS. 5 and 6 are diagrams illustrating an example of a circuit configuration of the refrigeration cycle apparatus according to Embodiment 2. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling only operation mode. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling main operation mode.

[0096] The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 2 includes a bypass circuit 8. The bypass circuit 8 connects a portion of the first circuit 111 between the first heat medium heat exchanger 1 and the first pump 6 and a portion of the second circuit 112 between the second heat medium heat exchanger 2 and the second pump 7 with each other. In other words, one end of the bypass circuit 8 is connected to the portion of the first circuit 111 between the first heat medium heat exchanger 1 and the first pump 6, while the other end of the bypass circuit 8 is connected to the portion of the second circuit 112 between the second heat medium heat exchanger 2 and the second pump 7. The bypass circuit 8 is stored in the relay unit 203. Hereinafter, the position at which the bypass circuit 8 is connected to the portion of the first circuit 111 between the first heat medium heat exchanger 1 and the first pump 6 will be called a node e.

[0097] While the heat medium heat exchanger is functioning as an evaporator, if the temperature of the refrigerant flowing through the heat medium heat exchanger becomes excessively low, the heat medium may reach the freezing point of water and be frozen within the heat medium heat exchanger. To address this issue, when a preset operating condition is satisfied, the controller 210 of the refrigeration cycle apparatus 200 executes the freeze protection operation to prevent the heat medium from being frozen within the heat medium heat exchanger. The operating condition is, for example, a condition that the temperature of the refrigerant flowing into the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a first preset temperature. The operating condition is, for example, a condition that the temperature of the heat medium flowing out of the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a second preset temperature. The pressure of the refrigerant flowing into the heat medium heat exchanger, which is functioning as an evaporator, and the pressure of the refrigerant flowing out of the heat medium heat exchanger, which is functioning as an evaporator, are correlated with the evaporating temperature of the refrigerant flowing through this heat medium heat exchanger. Hence, as the operating condition, a condition that the pressure of the refrigerant flowing into the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a preset pressure, for example, may be employed. As the operating condition, a condition that the pressure of the refrigerant flowing out of the heat medium heat exchanger, which is functioning as an evaporator, becomes lower than or equal to a preset pressure, for example, may be employed.

[0098] In one example, the refrigeration cycle apparatus 200 includes a sensor 81, which is a temperature sensor or a pressure sensor, at a position between the first expansion device 21 and the first heat medium heat exchanger 1 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 81, whether the first heat medium heat exchanger 1, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 82, which is a pressure sensor, at a position between the first heat medium heat exchanger 1 and the first opening-closing valve 51 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 82, whether the first heat medium heat exchanger 1, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation.

[0099] In one example, the refrigeration cycle apparatus 200 includes a sensor 83, which is a temperature sensor or a pressure sensor, at a position between the second expansion device 22 and the second heat medium heat exchanger 2 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 83, whether the second heat medium heat exchanger 2, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 84, which is a pressure sensor, at a position between the second heat medium heat exchanger 2 and the second opening-closing valve52 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 84, whether the second heat medium heat exchanger 2, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation.

[0100] In one example, the refrigeration cycle apparatus 200 includes a sensor 85, which is a pressure sensor, at a position between the node c and the suction inlet of the compressor 14 in the refrigerant circuit 100. This enables the controller 210 to detect, based on the detection value of the sensor 85, whether any of the heat medium heat exchangers that is functioning as an evaporator satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 86, which is a temperature sensor, at a position between the first heat medium heat exchanger 1 and the first flow switching mechanism 71 in the heat medium circuit 110. This enables the controller 210 to detect, based on the detection value of the sensor 86, whether the first heat medium heat exchanger 1, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation. In one example, the refrigeration cycle apparatus 200 includes a sensor 87, which is a temperature sensor, at a position between the second heat medium heat exchanger 2 and the third flow switching mechanism 73 in the heat medium circuit 110. This enables the controller 210 to detect, based on the detection value of the sensor 87, whether the second heat medium heat exchanger 2, which is functioning as an evaporator, satisfies the operating condition for performing the freeze protection operation.

[0101] It is not essential that the refrigeration cycle apparatus 200 includes all the above-described sensors 81 through 87. Among the sensors 81 through 87, necessary sensors may be selected so that the controller 210 can detect whether the corresponding heat medium heat exchanger satisfies the operating condition.

[0102] Subsequently, the operation of the refrigeration cycle apparatus 200 will be described below by referring to a flow of refrigerant and that of a heat medium. In the following description, the operation of the refrigeration cycle apparatus 200 will be explained through illustration of the freeze protection operation in the cooling only operation mode and that in the cooling main operation mode. The freeze protection operation in the cooling only operation mode and that in the cooling main operation mode will be discussed through illustration of an example in which the first heat medium heat exchanger 1 satisfies the operating condition for performing the freeze protection operation.Freeze Protection Operation in Cooling Only Operation Mode

[0103] In the state in which the refrigeration cycle apparatus 200 is operating in the cooling only operation mode as shown in FIG. 1, if the first heat medium heat exchanger 1 is found to satisfy the operating condition for performing the freeze protection operation, the refrigeration cycle apparatus 200 executes the freeze protection operation as illustrated in FIG. 5.

[0104] The controller 210 sets the second opening-closing valve 52 to be in the closed state. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the load-side heat exchanger 3b communicates with the pipe connecting the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other. The controller 210 may also increase the opening degree of the first expansion device 21 to raise the temperature of the refrigerant to flow into the first heat medium heat exchanger 1. Hereinafter, a portion at which the pipe extending from the third flow switching mechanism 73 is connected to the pipe connecting the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other will be called a node d. Hereinafter, a portion at which the pipe extending from the fourth flow switching mechanism 74 is connected to the pipe connecting the second flow switching mechanism 72 and the load-side heat exchanger 3a with each other will be called a node f.

[0105] In the freeze protection operation in the cooling only operation mode, the flow of refrigerant in the refrigerant circuit 100 is changed from the state in FIG. 1 in the following manner. As a result of the second opening-closing valve 52 being set in the closed state, the flow of the refrigerant to enter the second heat medium heat exchanger 2 is interrupted. That is, the refrigerant does not flow through the second heat medium heat exchanger 2. Other than that, the flow of the refrigerant is similar to that in FIG. 1.

[0106] In the freeze protection operation in the cooling only operation mode, the flow of a heat medium in the heat medium circuit 110 is changed from the state in FIG. 1 in the following manner. As a result of the flow path of the third flow switching mechanism 73 being switched as described above, the flow of the heat medium from the second heat medium heat exchanger 2 into the load-side heat exchanger 3b is interrupted. This prevents the heat medium from flowing through the second heat medium heat exchanger 2. Instead, the heat medium flows from the first heat medium heat exchanger 1 to the load-side heat exchanger 3b.

[0107] This will be described in greater detail. The heat medium discharged from the second pump 7 passes through the bypass circuit 8 and joins the heat medium discharged from the first pump 6 at the node e. The joined heat medium flows into the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then branches off at the node d. Part of the heat medium passing through the first flow switching mechanism 71 flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The remaining heat medium passing through the first flow switching mechanism 71 passes through the second flow switching mechanism 72.

[0108] The heat medium having entered the load-side heat exchanger 3a receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a enters the relay unit 203 and passes through the second flow switching mechanism 72. The heat medium is then sucked into the first pump 6. Meanwhile, the heat medium passing through the second flow switching mechanism 72 flows into the heat load unit 202 and enters the load-side heat exchanger 3b. The heat medium then receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3b flows into the relay unit 203 and passes through the fourth flow switching mechanism 74. The heat medium is then sucked into the second pump 7.Freeze Protection Operation in Cooling Main Operation Mode

[0109] In the state in which the refrigeration cycle apparatus 200 is operating in the cooling main operation mode as shown in FIG. 2, if the first heat medium heat exchanger 1 is found to satisfy the operating condition for performing the freeze protection operation, the refrigeration cycle apparatus 200 executes the freeze protection operation as illustrated in FIG. 6.

[0110] The controller 210 sets the fourth opening-closing valve 54 to be in the closed state. The controller 210 also switches the flow path of the third flow switching mechanism 73 so that the load-side heat exchanger 3b communicates with the pipe connecting the first flow switching mechanism 71 and the load-side heat exchanger 3a with each other. The controller 210 also switches the flow path of the fourth flow switching mechanism 74 so that the second pump 7 communicates with the pipe connecting the second flow switching mechanism 72 and the load-side heat exchanger 3a with each other. The controller 210 may also increase the opening degree of the first expansion device 21 to raise the temperature of the refrigerant to flow into the first heat medium heat exchanger 1.

[0111] In the freeze protection operation in the cooling main operation mode, the flow of refrigerant in the refrigerant circuit 100 is changed from the state in FIG. 2 in the following manner. As a result of the fourth opening-closing valve 54 being set in the closed state, the flow of the refrigerant to enter the second heat medium heat exchanger 2 is interrupted. That is, the refrigerant does not flow through the second heat medium heat exchanger 2. Other than that, the flow of the refrigerant is similar to that in FIG. 2.

[0112] In the freeze protection operation in the cooling main operation mode, the flow of a heat medium in the heat medium circuit 110 is changed from the state in FIG. 2 in the following manner. As a result of the flow path of the third flow switching mechanism 73 being switched as described above, the flow of the heat medium from the second heat medium heat exchanger 2 into the load-side heat exchanger 3b is interrupted. This prevents the heat medium from flowing through the second heat medium heat exchanger 2. As a result of the flow path of the fourth flow switching mechanism 74 being switched as described above, the heat medium does not flow through the load-side heat exchanger 3b, and instead, the heat medium flowing out of the load-side heat exchanger 3a is sucked into the second pump 7.

[0113] This will be described in greater detail. The heat medium discharged from the second pump 7 passes through the bypass circuit 8 and joins the heat medium discharged from the first pump 6 at the node e. The joined heat medium flows into the first heat medium heat exchanger 1. The heat medium is then cooled by the refrigerant and flows out of the first heat medium heat exchanger 1. The heat medium then flows into the relay unit 203 and passes through the first flow switching mechanism 71. The heat medium then flows into the heat load unit 202 and enters the load-side heat exchanger 3a. The heat medium having entered the load-side heat exchanger 3a receives heat from indoor air and cools it. The heat medium flowing out of the load-side heat exchanger 3a enters the relay unit 203.

[0114] The heat medium 3a having entered the relay unit 203 branches off at the node f. Part of the heat medium having entered the relay unit 203 passes through the second flow switching mechanism 72 and is sucked into the first pump 6. The remaining heat medium having entered the relay unit 203 passes through the fourth flow switching mechanism 74 and is sucked into the second pump 7.

[0115] As described above, the refrigeration cycle apparatus 200 according to Embodiment 2 includes the bypass circuit 8 and thus achieves the following advantages in addition to those of Embodiment 1.

[0116] When performing the freeze protection operation, while allowing the heat load unit 202 that is performing the cooling operation to continue it, the refrigeration cycle apparatus 200 of Embodiment 2 causes a heat medium discharged from the first pump 6 and that from the second pump 7 to flow through the heat medium heat exchanger that has satisfied the operating condition for performing the freeze protection operation. As a result of the heat medium discharged from the first pump 6 and that from the second pump 7 to flow through this heat medium heat exchanger, the flow rate of the heat medium in this heat medium heat exchanger is increased, thereby making it possible to prevent the heat medium from being frozen in the heat medium heat exchanger. That is, by performing the freeze protection operation, the refrigeration cycle apparatus 200 of Embodiment 2 can prevent the heat medium from being frozen in the heat medium heat exchanger while allowing the heat load unit 202 that is performing the cooling operation to continue it.Embodiment 3

[0117] By adding an opening-closing valve to be discussed in Embodiment 3 to the bypass circuit 8 of the refrigeration cycle apparatus 200 in Embodiment 2, the degradation of the performance of the refrigeration cycle apparatus 200 is suppressed. Note that points similar to Embodiment 1 or 2 will not be described in Embodiment 3 and that elements in Embodiment 3 executing functions similar to those in Embodiment 1 or 2 are designated by like reference numerals in Embodiment 1 or 2.

[0118] FIGS. 7 and 8 are diagrams illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 3. FIG. 7 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling only operation mode. FIG. 8 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling main operation mode.

[0119] The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 3 includes an opening-closing valve 9 that is provided in the bypass circuit 8 to open and close the bypass circuit 8. The open / closed state of the opening-closing valve 9 is controlled by the controller 210.

[0120] The refrigeration cycle apparatus 200 of Embodiment 3 is operated as follows. While the refrigeration cycle apparatus 200 is not performing the freeze protection operation, it sets the opening-closing valve 9 to be in the closed state. While the refrigeration cycle apparatus 200 is performing the freeze protection operation, it sets the opening-closing valve 9 to be in the open state.

[0121] It is now assumed that the refrigeration cycle apparatus 200 including the bypass circuit 8 is operating in the cooling main operation mode or in the heating main operation mode. In other words, it is assumed that the refrigeration cycle apparatus 200 including the bypass circuit 8 is cooling a heat medium in one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2 and is heating a heat medium in the other one of the first heat medium heat exchanger 1 and the second heat medium heat exchanger 2. That is, in the heat medium circuit 110 of the refrigeration cycle apparatus 200, the temperature of the heat medium circulating in the first circuit 111 and that in the second circuit 112 are different from each other. It is also assumed that, in the heat medium circuit 110, the pressure of the heat medium discharged from the first pump 6 provided in the first circuit 111 and that from the second pump 7 provided in the second circuit 112 are different from each other. In such operating conditions, the following phenomenon may occur if the opening-closing valve 9 is not provided in the bypass circuit 8. The heat medium may pass through the bypass circuit 8 and flow from one of the first circuit 111 and the second circuit 112 to the other one of the first circuit 111 and the second circuit 112. This may lead to the degradation of the performance of the refrigeration cycle apparatus 200.

[0122] The refrigeration cycle apparatus 200 of Embodiment 3 can address the above-described issue by setting the opening-closing valve 9 to be in the closed state when it is not performing the freeze protection operation. That is, the refrigeration cycle apparatus 200 of Embodiment 3 can suppress the degradation of the performance, which would be caused by the provision of the bypass circuit 8.Embodiment 4

[0123] By adding an air purge valve to be discussed in Embodiment 4 to the bypass circuit 8 of the refrigeration cycle apparatus 200 in Embodiment 2 or 3, the on-site installation of the refrigeration cycle apparatus 200 is facilitated. Note that points similar to any of Embodiment 1 through Embodiment 3 will not be described in Embodiment 4 and that elements in Embodiment 4 executing functions similar to those in any of Embodiment 1 through Embodiment 3 are designated by like reference numerals in Embodiment 1 through Embodiment 3.

[0124] FIGS. 9 and 10 are diagrams illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 4. FIG. 9 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling only operation mode. FIG. 10 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling main operation mode.

[0125] The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 4 includes an air purge valve 10 provided in the bypass circuit 8. The air purge valve 10 is opened when air purging from the heat medium circuit 110 is performed. The air purge valve 10 is closed at other times. The air purge valve 10 is opened and closed by an operator, for example.

[0126] When performing the on-site installation of the refrigeration cycle apparatus 200, the heat source unit 201, the relay unit 203, and the heat load units 202 are installed at predetermined locations. Then, the heat source unit 201 and the relay unit 203 connect to each other with a pipe, and the relay unit 203 and the heat load units 202 connect to each other with a pipe. A heat medium is then enclosed in the heat medium circuit 110. At this time, it is necessary to purge air from the heat medium circuit 110.

[0127] If the refrigeration cycle apparatus 200 does not include the bypass circuit 8 and the air purge valve 10, air purging from the heat medium circuit 110 is performed in the following manner, for example. The flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is first switched so that the load-side heat exchangers 3a and 3b form the first circuit 111. In other words, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b communicate with the first heat medium heat exchanger 1. Air purging from the first circuit 111 is then carried out. Then, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b form the second circuit 112. In other words, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b communicate with the second heat medium heat exchanger 2. Then, air purging from the second circuit 112 is carried out.

[0128] In contrast, in the heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 4, the first circuit 111 and the second circuit 112 communicate with each other by the bypass circuit 8. With this configuration of the heat medium circuit 110 of the refrigeration cycle apparatus 200 of Embodiment 4, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b form the first circuit 111 or the second circuit 112. In other words, the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 is switched so that the load-side heat exchangers 3a and 3b communicate with the first heat medium heat exchanger 1 or the second heat medium heat exchanger 2. Then, the air purge valve 10 is opened. As a result, the refrigeration cycle apparatus 200 of Embodiment 4 can purge air from the heat medium circuit 110 at one time without the need to switch the flow path of each of the first flow switching mechanism 71, second flow switching mechanism 72, third flow switching mechanism 73, and fourth flow switching mechanism 74 again. This facilitates the on-site installation of the refrigeration cycle apparatus 200 of Embodiment 4.Embodiment 5

[0129] The refrigeration cycle apparatus 200 of Embodiment 1 through Embodiment 4 include one heat source unit. That is, the refrigeration cycle apparatus 200 of Embodiment 1 through Embodiment 4 include the heat source unit 201 as the heat source unit. However, the refrigeration cycle apparatus may include multiple heat source units. Note that points similar to any of Embodiment 1 through Embodiment 4 will not be described in Embodiment 5 and that elements in Embodiment 5 executing functions similar to those in any of Embodiment 1 through Embodiment 4 are designated by like reference numerals in Embodiment 1 through Embodiment 4.

[0130] FIG. 11 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 5.

[0131] As the heat source unit, the refrigeration cycle apparatus 200 of Embodiment 5 includes a first heat source unit 201a storing the first heat medium heat exchanger 1 therein and a second heat source unit 201b storing the second heat medium heat exchanger 2 therein.

[0132] The refrigerant circuit 100 stored in the first heat source unit 201a is configured as follows, for example. The compressor 14, the outdoor heat exchanger 4, an expansion device 20, and the first heat medium heat exchanger 1 are connected to each other by a refrigerant pipe in a ring-like shape so as to form the refrigerant circuit 100 stored in the first heat source unit 201a. The expansion device 20 is configured similarly to the first expansion device 21 and the second expansion device 22. That is, the expansion device 20 has a function as a reducing valve or an expansion valve and is used for expanding the refrigerant to reduce the pressure of the refrigerant.

[0133] The refrigerant circuit 100 stored in the first heat source unit 201a includes a flow switching device 40, which is a four-way valve, for example. The flow switching device 40 changes the flow path to switch the heat exchanger to be connected to the refrigerant discharge outlet of the compressor 14 and also to switch the heat exchanger to be connected to the refrigerant suction inlet of the compressor 14. More specifically, by the flow switching device 40, the refrigerant discharge outlet of the compressor 14 is connected to one of the outdoor heat exchanger 4 and the first heat medium heat exchanger 1, while the refrigerant suction inlet of the compressor 14 is connected to the other one of the outdoor heat exchanger 4 and the first heat medium heat exchanger 1. By the provision of the flow switching device 40, the first heat medium heat exchanger 1 can function as a condenser and also as an evaporator.

[0134] The refrigerant circuit 100 stored in the second heat source unit 201b is configured similarly to that stored in the first heat source unit 201a, except that it includes the second heat medium heat exchanger 2 instead of the first heat medium heat exchanger 1.

[0135] The relay unit 203, the heat load units 202, and the heat medium circuit 110 are configured, as in one of Embodiment 1 through Embodiment 4.

[0136] With the heat source unit configured as in Embodiment 5, too, the refrigeration cycle apparatus 200 can obtain the same advantages as those in Embodiment 1 through Embodiment 4.REFERENCE SIGNS LIST1: first heat medium heat exchanger, 2: second heat medium heat exchanger, 3a: load-side heat exchanger, 3b: load-side heat exchanger, 4: outdoor heat exchanger, 5: outdoor fan, 6: first pump, 7: second pump, 8: bypass circuit, 9: opening-closing valve, 10: air purge valve, 14: compressor, 20: expansion device, 21: first expansion device, 22: second expansion device, 40: flow switching device, 41: first flow switching device, 42: second flow switching device, 51: first opening-closing valve, 52: second opening-closing valve, 53: third opening-closing valve, 54: fourth opening-closing valve, 70:

[0138] switching mechanism, 71: first flow switching mechanism, 72: second flow switching mechanism, 73: third flow switching mechanism, 74: fourth flow switching mechanism, 81: sensor, 82: sensor, 83: sensor, 84: sensor, 85: sensor, 86: sensor, 87: sensor, 100: refrigerant circuit, 110: heat medium circuit, 111: first circuit, 112: second circuit, 200: refrigeration cycle apparatus, 201: heat source unit, 201a: first heat source unit, 201b: second heat source unit, 202: heat load unit, 203: relay unit, 210: controller, a: node, b: node, c: node, d: node, e: node, f: node

Examples

embodiment 1

[0021]FIG. 1 is a diagram illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 1 that is operating in a cooling only operation mode. The solid-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of refrigerant. The broken-line arrows having the head with a black fill in FIGS. 1 through 11 each indicate a direction of a flow of a heat medium. In FIGS. 1 through 11, a flow path in the open state is indicated by the corresponding valve or mechanism with a white fill, while a flow path in the closed state is indicated by the corresponding valve or mechanism with a black fill.

[0022]A refrigeration cycle apparatus 200 includes a chiller-type heat source unit 201 and a heat medium circuit 110 in which a heat medium supplied from the heat source unit 201 circulates.

[0023]The heat source unit 201 includes a refrigerant circuit 100 in which refrigerant circulates and a heat medium he...

embodiment 2

[0094]By adding a bypass circuit to be discussed in Embodiment 2 to the refrigeration cycle apparatus 200 in Embodiment 1, the reliability of the refrigeration cycle apparatus 200 is improved. Note that points similar to Embodiment 1 will not be described in Embodiment 2 and that elements in Embodiment 2 executing functions similar to those in Embodiment 1 are designated by like reference numerals in Embodiment 1.

[0095]FIGS. 5 and 6 are diagrams illustrating an example of a circuit configuration of the refrigeration cycle apparatus according to Embodiment 2. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling only operation mode. FIG. 5 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing a freeze protection operation in the cooling main operation mode.

[0096]The heat medium circuit 110 of the refrigeration cycle apparatus 200 according to Embodiment 2 in...

embodiment 3

[0117]By adding an opening-closing valve to be discussed in Embodiment 3 to the bypass circuit 8 of the refrigeration cycle apparatus 200 in Embodiment 2, the degradation of the performance of the refrigeration cycle apparatus 200 is suppressed. Note that points similar to Embodiment 1 or 2 will not be described in Embodiment 3 and that elements in Embodiment 3 executing functions similar to those in Embodiment 1 or 2 are designated by like reference numerals in Embodiment 1 or 2.

[0118]FIGS. 7 and 8 are diagrams illustrating an example of the circuit configuration of a refrigeration cycle apparatus according to Embodiment 3. FIG. 7 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling only operation mode. FIG. 8 illustrates the operating state of the refrigeration cycle apparatus 200 that is performing the freeze protection operation in the cooling main operation mode.

[0119]The heat medium circuit 1...

Claims

1. A refrigeration cycle apparatus including a heat source unit, the heat source unit including a heat medium heat exchanger, in which a heat medium, which is a medium different from refrigerant circulating in a refrigerant circuit circulates, and the refrigerant exchange heat with each other, the heat source unit supplying the heat medium having exchanged heat with the refrigerant in the heat medium heat exchanger to outside of the heat source unit, the refrigeration cycle apparatus comprising:the heat medium heat exchanger includes a first heat medium heat exchanger and a second heat medium heat exchanger;a heat medium circuit in which the heat medium supplied from the heat source unit circulates, the heat medium circuit includinga plurality of load-side heat exchangers, anda switching mechanism configured to switch a distribution state of the heat medium to flow into and out of each of the load-side heat exchangers, anda first circuit that allows the heat medium to pass therethrough and to flow into the first heat medium heat exchanger,a second circuit that allows the heat medium to pass therethrough and to flow into the second heat medium heat exchanger;a first pump that is disposed at a position in the first circuit at which the heat medium to enter the first heat medium heat exchanger flows and that discharges the heat medium to enter the first heat medium heat exchanger,a second pump that is disposed at a position in the second circuit at which the heat medium to enter the second heat medium heat exchanger flows and that discharges the heat medium to enter the second heat medium heat exchanger,a bypass circuit that connects a portion of the first circuit between the first heat medium heat exchanger and the first pump and a portion of the second circuit between the second heat medium heat exchanger and the second pump with each other, anda relay unit storing the switching mechanism therein, whereinthe switching mechanism is configured to switch the distribution state of the heat medium flowing out of the first heat medium heat exchanger to flow into each of the load-side heat exchangers and the distribution state of the heat medium flowing out of the second heat medium heat exchanger to flow into each of the load-side heat exchangers.2.-3. (canceled)4. The refrigeration cycle apparatus of claim 1, wherein the heat medium circuit includes an opening-closing valve that is provided in the bypass circuit to open and close the bypass circuit.

5. The refrigeration cycle apparatus of claim 1, wherein the heat medium circuit includes an air purge valve provided in the bypass circuit.

6. The refrigeration cycle apparatus of claim 1, wherein the heat source unit includes a first heat source unit and a second heat source unit, the first heat source unit storing the first heat medium heat exchanger therein, the second heat source unit storing the second heat medium heat exchanger therein.

Images