Air conditioning device

Abstract

The present invention comprises: a first heating / cooling device and a second heating / cooling device that heat or cool a heat medium; a first heat medium circulation circuit in which the heat medium heated or cooled by heat exchange with the first heating / cooling device circulates through heat medium piping; a second heat medium circulation circuit in which the heat medium heated or cooled by heat exchange with the second heating / cooling device circulates through heat medium piping; a plurality of load-side heat exchangers that exchange heat between air in a space to be air-conditioned and the heat medium; a flow path switching device that switches, for each of the load-side heat exchangers, between connection to the first heat medium circulation circuit side and connection to the second heat medium circulation circuit side; bypass piping that connects heat medium piping on a side where the heat medium flows toward the load-side heat exchanger and heat medium piping on a side where the heat medium returning from the load-side heat exchanger flows; and a heat medium switching device that switches between causing the heat medium to pass through the load-side heat exchanger and causing the heat medium to pass through the bypass piping.

Description

Air conditioner

[0001] The technology of the present disclosure relates to air conditioners. In particular, the present disclosure relates to an air conditioner that performs air conditioning in a space to be air-conditioned by means of circulation of a heat medium different from a refrigerant.

[0002] There is an air conditioner that performs air conditioning by configuring a heat medium circuit for circulating a heat medium including water or brine between a heat source side device and an indoor unit having an indoor heat exchanger to transfer heat. In such an air conditioner, a device that supplies heat to be carried by the heat medium heats or cools the heat medium and carries it, and supplies heat to the indoor unit. The indoor unit heats or cools the air in the air-conditioned space, which is a heat load, with the heat carried by the heat medium to perform air conditioning (see, for example, Patent Document 1).

[0003] Further, there is an air conditioner in which a heat source device is provided with a heating device for heating the heat medium and a cooling device for cooling the heat medium, and the heated heat medium or the cooled heat medium is allowed to pass through a plurality of indoor units respectively, so that individual heating or cooling can be performed. In an air conditioner having such a configuration, by switching the flow paths between the heating device and the cooling device and the indoor unit via a switching device, either the heated heat medium or the cooled heat medium can be selected to pass through the piping between the heat source side device and the indoor unit. The heat source side device can operate efficiently as the entire air conditioner by changing the operation mode based on the supply amounts of the heated heat medium and the cooled heat medium.

[0004] Japanese Unexamined Patent Application Publication No. 2017-053507

[0005] Here, depending on the specifications of the air conditioner, when the operation mode of the air conditioner is changed, the device that heats the heat medium and the device that cools the heat medium may be interchanged. For this reason, for a while after the operation mode is changed, the heated heat medium may be supplied to an indoor unit that is performing cooling operation, or the cooled heat medium may be supplied to an indoor unit that is performing heating operation. When heat media of different temperature ranges are supplied to the indoor units, some indoor units experience a decrease in cooling and heating operation efficiency, which in turn reduces the operation efficiency of the entire air conditioner.

[0006] This disclosure provides an air conditioning system that can suppress the decrease in the overall operating efficiency of the system in order to solve the above-mentioned problems.

[0007] The air conditioning system according to this disclosure includes a first heating / cooling device that heats or cools a heat transfer medium, a second heating / cooling device that cools the heat transfer medium when the first heating / cooling device is heating it, and heats the heat transfer medium when the first heating / cooling device is cooling it, a first heat transfer medium circulation circuit through which the heat transfer medium heated or cooled by heat exchange with the first heating / cooling device circulates through heat transfer pipes, a second heat transfer medium circulation circuit through which the heat transfer medium heated or cooled by heat exchange with the second heating / cooling device circulates through heat transfer pipes, and a heat load The system comprises multiple load-side heat exchangers that exchange heat between the air in the space to be air-conditioned and a heat transfer medium, a flow path switching device that switches each load-side heat exchanger between connecting to the first heat transfer medium circulation circuit or to the second heat transfer medium circulation circuit, a bypass pipe that connects the heat transfer medium piping on the side through which the heat transfer medium flows toward the load-side heat exchanger and the heat transfer medium piping on the side through which the heat transfer medium returns from the load-side heat exchanger, and a heat transfer medium switching device that switches whether the heat transfer medium passes through the load-side heat exchanger or through the bypass pipe.

[0008] According to this disclosure, a load-side heat exchanger equipped with a bypass pipe and a heat transfer medium switching device can block the passage of the heat transfer medium in the bypass pipe by switching the heat transfer medium switching device, thereby preventing the passage of heat transfer mediums with different temperature ranges from being required. This makes it possible to suppress a decrease in the overall operating efficiency of the device.

[0009] This figure shows a schematic of an installation example of the air conditioning system 100 according to Embodiment 1. This figure shows an example of the configuration of the air conditioning system 100 according to Embodiment 1. This figure illustrates an example of the refrigerant flow, etc., in the full cooling operation of the air conditioning system 100 according to Embodiment 1. This figure illustrates an example of the refrigerant flow, etc., in the full heating operation of the air conditioning system 100 according to Embodiment 1. This figure illustrates an example of the refrigerant flow, etc., in the cooling-dominant operation of the air conditioning system 100 according to Embodiment 1. This figure illustrates an example of the refrigerant flow, etc., in the cooling-dominant operation of the air conditioning system 100 according to Embodiment 1. This figure illustrates the operation when switching from cooling-dominant operation to heating-dominant operation of the air conditioning system 100 according to Embodiment 1. This figure illustrates the operation when switching from heating-dominant operation to cooling-dominant operation of the air conditioning system 100 according to Embodiment 1. This figure illustrates the operation when switching from full cooling operation to heating-dominant operation of the air conditioning system 100 according to Embodiment 1. This figure illustrates an example of the configuration of the air conditioning system 100 according to Embodiment 2. This diagram illustrates the operation of switching from cooling-dominant operation to heating-dominant operation in the air conditioning system 100 according to Embodiment 2. This diagram illustrates the operation of switching from heating-dominant operation to cooling-dominant operation in the air conditioning system 100 according to Embodiment 2. This diagram illustrates the operation of switching from full cooling operation to heating-dominant operation in the air conditioning system 100 according to Embodiment 2. This diagram illustrates the operation of switching from full heating operation to cooling-dominant operation in the air conditioning system 100 according to Embodiment 2. This diagram illustrates the control flow in the air conditioning system 100 according to Embodiment 3. This diagram shows an example of the configuration in the air conditioning system 100 according to Embodiment 4.

[0010] The following description of the air conditioning system according to the embodiment will be made with reference to the drawings. In the following drawings, components with the same reference numerals are the same or equivalent and are common to the entire text of the embodiment described below. Also, the size relationships of the components in the drawings may differ from those of the actual components. Furthermore, the forms of the components shown in the entire specification are merely examples and are not limited to the forms described in the specification. In particular, the combinations of components are not limited to the combinations in each embodiment, and components described in other embodiments can be applied to other embodiments. Furthermore, high and low temperatures are not determined in relation to absolute values, but are determined relatively in relation to the state and operation of the device, etc. Also, when there is no need to distinguish or specify multiple similar devices, etc. that are distinguished by subscripts, the subscripts may be omitted. Furthermore, the size relationships of the components in the drawings may differ from those of the actual components.

[0011] Embodiment 1. Figure 1 is a schematic diagram of an installation example of the air conditioning system 100 according to Embodiment 1. Based on Figure 1, an installation example of the air conditioning system 100 according to Embodiment 1 will be described. As shown in Figure 1, the air conditioning system 100 according to Embodiment 1 comprises a heat source unit 1 which is an outdoor unit, a relay unit 2 which is a relay unit, and three load devices 4 (load device 4A, load device 4B, and load device 4C) which are indoor units. The heat source unit 1, the relay unit 2, and each load device 4 are connected by heat transfer fluid piping 301. The heat source unit 1 is installed outdoors, for example, on the roof of a building 200. The relay unit 2 and the load devices 4 are installed indoors, for example, inside a building 200. Here, as shown in Figure 1 and other figures, the air conditioning system 100 according to Embodiment 1 will be described as having a configuration in which the relay unit 2 is connected to three load devices 4, but the number of connected load devices 4 is not limited to three.

[0012] Figure 2 is a diagram showing an example of the configuration of an air conditioning system 100 according to Embodiment 1. Based on Figure 2, the configuration of the equipment and other components of the air conditioning system 100 will be described. The air conditioning system 100 has a first refrigerant circuit 10, a second refrigerant circuit 20, and a heat transfer medium circulation circuit 30. The heat transfer medium circulation circuit 30 has two circuits, a first heat transfer medium circulation circuit 31 and a second heat transfer medium circulation circuit 32, depending on the path of the circulating heat transfer medium. The first refrigerant circuit 10 is a first heating and cooling device that heats or cools the heat transfer medium by a refrigeration cycle, and the second refrigerant circuit 20 is a second heating and cooling device that heats or cools the heat transfer medium. The heat source unit 1 has some of the components that make up the first refrigerant circuit 10 and some of the components that make up the first heat transfer medium circulation circuit 31 and the second heat transfer medium circulation circuit 32. Furthermore, each load device 4 has a load-side heat exchanger 41, which is a component of the heat transfer medium circulation circuit 30.

[0013] The first refrigerant circuit 10 contains, for example, R290, NH ３ The first refrigerant circuit 10 contains a flammable refrigerant such as olefins (R1234yf, R1234ze(E), R1123, R1132(E), etc.). This is because the heat source unit 1 is mainly installed outdoors, and a refrigerant that is flammable but has a small global warming effect is used. On the other hand, the second refrigerant circuit 20 contains a non-flammable or slightly flammable refrigerant such as R410A, R32, olefins, or mixtures of these refrigerants. This is because the relay unit 2 is mainly installed indoors. Here, the refrigerants sealed in the first refrigerant circuit 10 and the refrigerants sealed in the second refrigerant circuit 20 are not limited to the refrigerants mentioned above. For example, refrigerants commonly used in refrigeration cycles today, such as R410A or R32, R290, CO2, etc. ２ NH ３ Olefins, mixtures thereof, and other types of refrigerants may be used. For example, the refrigerant sealed in the second refrigerant circuit 20 may be, with safety in mind, for example, R290, NH ３Flammable refrigerants such as olefins may be sealed inside. Also, the first refrigerant circuit 10, which is installed outdoors, has fewer constraints on installation space than the second refrigerant circuit 20. For this reason, the amount of refrigerant sealed inside the first refrigerant circuit 10 is greater than the amount of refrigerant sealed inside the second refrigerant circuit 20. For example, if the amount of refrigerant sealed inside the second refrigerant circuit 20 is less than 1 kg, which is the standard for using flammable refrigerants indoors, then the amount of refrigerant sealed inside the first refrigerant circuit 10 will be 5 kg or less. As a result, the capacity of the first refrigerant circuit 10 is greater than that of the second refrigerant circuit 20, and the operating efficiency is higher. Therefore, the first refrigerant circuit 10 operates under a higher load from the load device 4 than the second refrigerant circuit 20.

[0014] Furthermore, the heat transfer fluid circulating in the first heat transfer fluid circulation circuit 31 and the second heat transfer fluid circulation circuit 32 can be, for example, brine (antifreeze), water, a mixture of brine and water, or a mixture of water and an additive with high corrosion-preventive properties. In this way, the heat transfer fluids in the first heat transfer fluid circulation circuit 31 and the second heat transfer fluid circulation circuit 32 can be fluids with high safety.

[0015] In the air conditioning system 100 of Embodiment 1, the first heat transfer medium circulation circuit 31 and the second heat transfer medium circulation circuit 32 are provided with a first flow path switching device 312 and a second flow path switching device 322, respectively. The first flow path switching device 312 and the second flow path switching device 322 will be described later. The first heat transfer medium pipe 313 of the heat transfer medium piping 301 is the piping that connects the first heat transfer medium heat exchanger 11, the second heat transfer medium heat exchanger 21, the first pump 311 and the first flow path switching device 312 in the first heat transfer medium circulation circuit 31. The second heat transfer medium pipe 323 of the heat transfer medium piping 301 is the piping that connects the third heat transfer medium heat exchanger 22, the second pump 321 and the second flow path switching device 322 in the second heat transfer medium circulation circuit 32.

[0016] Next, the configuration of the heat source unit 1 will be described. As mentioned above, the heat source unit 1 has a first refrigerant circuit 10 through which the refrigerant circulates. The first refrigerant circuit 10 is a circuit in which a first compressor 12, a first cooling / heating flow path switching valve 13, a heat source side heat exchanger 14, a first expansion mechanism 15, and a first heat transfer medium heat exchanger 11 are sequentially connected by refrigerant piping. Here, the first refrigerant circuit 10 may be a circuit with a configuration that includes other equipment in addition to the equipment described above. Also, some of the equipment described above may be omitted.

[0017] The first compressor 12 is, for example, an inverter compressor. If the first compressor 12 is an inverter compressor, the drive frequency may be arbitrarily changed by, for example, an inverter circuit, thereby changing the refrigerant discharge capacity per unit time. In that case, the operation of the inverter circuit is controlled by the control device 5, which will be described later.

[0018] The first cooling / heating flow path switching valve 13 is, for example, a four-way valve and has the function of switching the flow path of the refrigerant. During cooling operation, the first cooling / heating flow path switching valve 13 switches the refrigerant flow path to connect the refrigerant discharge side of the first compressor 12 to the heat source side heat exchanger 14, and to connect the refrigerant suction side of the first compressor 12 to the first heat transfer medium heat exchanger 11. On the other hand, during heating operation, the first cooling / heating flow path switching valve 13 switches the refrigerant flow path to connect the refrigerant discharge side of the first compressor 12 to the first heat transfer medium heat exchanger 11, and to connect the refrigerant suction side of the first compressor 12 to the heat source side heat exchanger 14. Here, the first cooling / heating flow path switching valve 13 is a four-way valve, but it may also be a valve configured by combining multiple two-way valves or three-way valves.

[0019] The heat source side heat exchanger 14 performs heat exchange between the refrigerant and the outside air. In this embodiment 1, the heat source side heat exchanger 14 functions as an evaporator during heating operation, evaporating and vaporizing the refrigerant. On the other hand, during cooling operation, the heat source side heat exchanger 14 functions as a condenser, condensing and liquefying the refrigerant. The heat source side blower 16 is driven based on instructions from the control device 5, and causes air from outside the heat source unit 1 to pass through the heat source side heat exchanger 14, forming an airflow that flows out from inside the heat source unit 1.

[0020] The first expansion mechanism 15 is a mechanism that depressurizes and expands the refrigerant flowing through the first refrigerant circuit 10. The first expansion mechanism 15 has, for example, an electronic expansion valve whose opening degree can be changed based on instructions from the control device 5. The electronic expansion valve can adjust the flow rate and pressure of the refrigerant passing through it.

[0021] The first heat exchanger 11 is a heat exchanger that performs heat exchange between the heat transfer medium flowing through the first refrigerant circuit 10 and the refrigerant flowing through the first refrigerant circuit 10. The first heat exchanger 11 is part of the flow path of the first refrigerant circuit 10 and the flow path of the first heat transfer medium circulation circuit 31. Therefore, the first heat exchanger 11 is a component of both the first refrigerant circuit 10 and the first heat transfer medium circulation circuit 31. During cooling operation, the first heat exchanger 11 functions as an evaporator, performing heat exchange between the refrigerant flowing out of the first expansion mechanism 15 and the heat transfer medium, evaporating and vaporizing the refrigerant, and cooling the heat transfer medium. On the other hand, during heating operation, the first heat exchanger 11 functions as a condenser, performing heat exchange between the refrigerant flowing in from the first compressor 12 and the heat transfer medium, condensing the refrigerant into a liquefied or gas-liquid two-phase state, and heating the heat transfer medium.

[0022] Furthermore, the first pump 311 is a component of the first heat transfer medium circulation circuit 31. The first pump 311 draws in the heat transfer medium, pressurizes it, and circulates it through the first heat transfer medium circulation circuit 31. Here, the capacity of the first pump 311 to deliver the heat transfer medium under pressurization is changed by a pump inverter drive device (not shown). The pump inverter drive device changes the drive frequency arbitrarily based on instructions from the control device 5, thereby changing the capacity of the first pump 311. In this example, the heat source unit 1 has the first pump 311, but this is not the only option; the relay unit 2 may also have the first pump 311.

[0023] Furthermore, as described above, the relay unit 2 includes the equipment constituting the second refrigerant circuit 20 and some of the equipment constituting the first heat transfer medium circulation circuit 31 and the second heat transfer medium circulation circuit 32. The second refrigerant circuit 20 is a circuit in which the second compressor 23, the second heating / cooling flow path switching valve 24, the second heat transfer medium heat exchanger 21, the second expansion mechanism 25, and the third heat transfer medium heat exchanger 22 are sequentially connected by refrigerant piping. Here, the second refrigerant circuit 20 may be a circuit with a configuration that includes other equipment in addition to the equipment described above. Also, some of the equipment described above may be omitted.

[0024] The second compressor 23 is, for example, an inverter compressor, and basically has the same configuration as the first compressor 12.

[0025] The second cooling / heating flow path switching valve 24 is, for example, a four-way valve, and is basically the same configuration as the first cooling / heating flow path switching valve 13. During cooling operation, the second cooling / heating flow path switching valve 24 switches the refrigerant flow path to connect the refrigerant discharge side of the second compressor 23 to the second heat transfer medium heat exchanger 21, and to connect the refrigerant suction side of the second compressor 23 to the third heat transfer medium heat exchanger 22. On the other hand, during heating operation, the second cooling / heating flow path switching valve 24 switches the refrigerant flow path to connect the refrigerant discharge side of the second compressor 23 to the third heat transfer medium heat exchanger 22, and to connect the refrigerant suction side of the second compressor 23 to the second heat transfer medium heat exchanger 21. Here, the second cooling / heating flow path switching valve 24 is a four-way valve, but it may also be a valve configured by combining multiple two-way valves or three-way valves.

[0026] The second expansion mechanism 25 depressurizes and expands the refrigerant circulating in the second refrigerant circuit 20. Similar to the first expansion mechanism 15, the second expansion mechanism 25 has an electronic expansion valve that can change its opening degree based on instructions from the control device 5, for example.

[0027] The second heat exchanger 21 is a heat exchanger that performs heat exchange between the heat transfer medium flowing through the first heat transfer circulation circuit 31 and the refrigerant flowing through the second refrigerant circuit 20. The second heat exchanger 21 is part of the flow path of the second refrigerant circuit 20 and the flow path of the first heat transfer circulation circuit 31. Therefore, the second heat exchanger 21 is a component of both the second refrigerant circuit 20 and the first heat transfer circulation circuit 31. In particular, when the second heat exchanger 21 functions as a condenser, it is preferable to have a flow path in the second heat exchanger 21 such that the refrigerant circulating in the second refrigerant circuit 20 and the heat transfer medium circulating in the first heat transfer circulation circuit 31 flow in opposite directions. By having the refrigerant circulating in the second refrigerant circuit 20 and the heat transfer medium circulating in the first heat transfer circulation circuit 31 flow in opposite directions, the heat exchange rate in the second heat exchanger 21 can be increased. The second heat transfer fluid heat exchanger 21 functions as a condenser during heating operation, exchanging heat between the refrigerant flowing in from the second compressor 23 and the heat transfer fluid, condensing the refrigerant into a liquefied or gas-liquid two-phase state, and heating the heat transfer fluid. On the other hand, the second heat transfer fluid heat exchanger 21 functions as an evaporator during cooling operation, exchanging heat between the refrigerant flowing out from the second expansion mechanism 25 and the heat transfer fluid, evaporating the refrigerant into a vapor, and cooling the heat transfer fluid.

[0028] The third heat exchanger 22 is a heat exchanger that performs heat exchange between the heat transfer medium flowing through the second heat transfer circulation circuit 32 and the refrigerant flowing through the second refrigerant circuit 20. The third heat exchanger 22 is part of the flow path of the second refrigerant circuit 20 and the flow path of the second heat transfer circulation circuit 32. Therefore, the third heat exchanger 22 is part of the components of the second refrigerant circuit 20 and the second heat transfer circulation circuit 32. In particular, when the third heat exchanger 22 functions as a condenser, it is preferable to have a flow path in the third heat exchanger 22 such that the refrigerant circulating in the second refrigerant circuit 20 and the heat transfer medium circulating in the second heat transfer circulation circuit 32 flow in opposite directions. By having the refrigerant circulating in the second refrigerant circuit 20 and the heat transfer medium circulating in the second heat transfer circulation circuit 32 flow in opposite directions, the heat exchange rate in the third heat exchanger 22 can be increased. The third heat transfer fluid heat exchanger 22 functions as an evaporator during cooling operation, exchanging heat between the refrigerant flowing out from the second expansion mechanism 25 and the heat transfer fluid, evaporating and vaporizing the refrigerant, and cooling the heat transfer fluid. On the other hand, the third heat transfer fluid heat exchanger 22 functions as a condenser during heating operation, exchanging heat between the refrigerant flowing in from the second compressor 23 and the heat transfer fluid, condensing the refrigerant into a liquefied or gas-liquid two-phase state, and heating the heat transfer fluid.

[0029] Furthermore, the second pump 321 is a component of the second heat transfer medium circulation circuit 32. Similar to the first pump 311, the second pump 321 draws in the heat transfer medium, pressurizes it, and circulates it through the second heat transfer medium circulation circuit 32. The second pump 321 also has a pump inverter drive device (not shown).

[0030] The first flow path switching device 312 is, for example, a switching device such as a two-way valve. The first flow path switching device 312 is provided on the inlet and outlet sides of the heat medium of the load-side heat exchanger 41, which will be described later, in the first heat medium circulation circuit 31, and controls the inflow, outflow, or shutoff of the heat medium flowing through the first heat medium circulation circuit 31 to the load device 4. When the first flow path switching device 312 is opened, the equipment of the load device 4 becomes equipment constituting the first heat medium circulation circuit 31, and the heat medium flowing through the first heat medium circulation circuit 31 passes through. The second flow path switching device 322 is, for example, a switching device such as a two-way valve. The second flow path switching device 322 is provided on the inlet and outlet sides of the heat medium of the load-side heat exchanger 41, which will be described later, and controls the inflow, outflow, or shutoff of the heat medium flowing through the second heat medium circulation circuit 32 to the load device 4. When the second flow path switching device 322 is opened, the equipment of the load device 4 becomes equipment constituting the second heat transfer medium circulation circuit 32, and the heat transfer medium flowing through the second heat transfer medium circulation circuit 32 passes through. Here, the first flow path switching device 312 and the second flow path switching device 322 are assumed to be independent devices. However, this is not limited to this. For example, they may be an integrated device that can switch the inflow and outflow of the heat transfer medium in the first flow path switching device 312, the inflow and outflow of the heat transfer medium in the second flow path switching device 322, or the shut-off of the heat transfer medium. Also, although not particularly limited, the first flow path switching device 312 and the second flow path switching device 322 may be devices that can control the opening degree (opening area) of a valve, for example.

[0031] The load devices 4 (load devices 4A, 4B, and 4C) are installed in the room that will be air-conditioned. Each load device 4 has a load-side heat exchanger 41 and a load-side blower 47. In particular, each load device 4 in Embodiment 1 has a bypass pipe 42 and a load-side switching device 43.

[0032] The load-side heat exchanger 41 is, for example, a fin-tube type heat exchanger that performs heat exchange between the indoor air and the heat transfer medium in the space to be air-conditioned. During cooling operation, the load-side heat exchanger 41 cools the space to be air-conditioned by passing a heat transfer medium that is colder than the indoor air, which is the heat load, through the heat transfer tubes of the load-side heat exchanger 41. On the other hand, during heating operation, the load-side heat exchanger 41 warms the space to be air-conditioned by passing a heat transfer medium that is warmer than the indoor air, which is the heat load, through the heat transfer tubes of the load-side heat exchanger 41. Here, for example, the load device 4 may have a flow rate adjustment device (not shown) that adjusts the flow rate of the heat transfer medium flowing into the load-side heat exchanger 41. The load-side blower 47 passes indoor air through the load-side heat exchanger 41 and sends the air that has passed through the load-side heat exchanger 41 into the room.

[0033] The bypass piping 42 is a pipe that bypasses the heat transfer medium that flows into the load device 4, preventing it from passing through the load-side heat exchanger 41, and allows it to flow out of the load device 4. The load-side switching device 43 is a heat transfer medium switching device that switches the flow path so that the heat transfer medium passes through either the bypass piping 42 or the load-side heat exchanger 41. The load-side switching device 43 in Embodiment 1 has a load-side bypass on-off valve 44, a heat exchanger inlet on-off valve 45, and a heat exchanger outlet on-off valve 46. Each on-off valve is a two-way valve that allows the heat transfer medium to pass through when open and blocks the passage of the heat transfer medium when closed. Here, either the heat exchanger inlet on-off valve 45 or the heat exchanger outlet on-off valve 46 may be omitted. Alternatively, the load-side switching device 43 may be configured as a three-way valve, integrating the load-side bypass on-off valve 44, the heat exchanger inlet on-off valve 45, and the heat exchanger outlet on-off valve 46.

[0034] Furthermore, the air conditioning system 100 has various sensors for detecting physical quantities such as temperature. In particular, the air conditioning system 100 has a first heat transfer medium temperature sensor 51 and a second heat transfer medium temperature sensor 52. The first heat transfer medium temperature sensor 51 is installed on the refrigerant outlet side of the first heat transfer medium heat exchanger 11 and detects the temperature of the heat transfer medium heated or cooled by the first heat transfer medium heat exchanger 11, and sends a signal related to the detected temperature to the control device 5. The second heat transfer medium temperature sensor 52 is installed on the refrigerant outlet side of the third heat transfer medium heat exchanger 22 and detects the temperature of the heat transfer medium heated or cooled by the third heat transfer medium heat exchanger 22, and sends a signal related to the detected temperature to the control device 5.

[0035] The control device 5 is a device that performs control processing for the entire air conditioning system 100 by sending instructions to the equipment of the air conditioning system 100. The control device 5 has a control unit 5A and a storage unit 5B. Specifically, the control device 5 controls the drive frequency of each compressor, the switching of each flow path switching device and each on / off valve, the opening degree of each expansion mechanism, the drive frequency of each pump, etc. In particular, the control device 5 performs control processing related to changing the operating mode. Here, it is assumed that the control device 5 also controls the operation of the equipment, even for operations not specifically described. In Embodiment 1, the control device 5 is composed of, for example, a microcomputer with a control arithmetic processing unit such as a CPU (Central Processing Unit), dedicated hardware such as an ASIC or FPGA, or both, as the control unit 5A. The storage unit 5B has, for example, a volatile storage device (not shown) such as a random access memory (RAM) that can temporarily store data and a non-volatile auxiliary storage device (not shown) such as flash memory. The control device 5 can be composed of hardware and software. Control is realized by the hardware executing the software.

[0036] Next, the operating operations performed by the air conditioning system 100 during various operating conditions will be described. The air conditioning system 100 can operate in four operating modes: full cooling mode, full heating mode, cooling-focused mode, and heating-focused mode.

[0037] All-out cooling operation is an operating mode in which all load devices 4 in operation perform cooling. In this mode, load devices 4 are either cooling or stopped. All-out heating operation is an operating mode in which all load devices 4 in operation perform heating. In this mode, load devices 4 are either heating or stopped. Cooling-dominant operation is an operating mode in which both cooling-performing load devices 4 and heating-performing load devices 4 exist simultaneously, and the heat load related to cooling (cooling load) is greater than the heat load related to heating (heating load). In this mode, load devices 4 are either cooling-performing, heating-performing, or stopped. Heating-dominant operation is an operating mode in which both cooling-performing load devices 4 and heating-performing load devices 4 exist simultaneously, and the heating load is greater than the cooling load. In this mode, load devices 4 are either cooling-performing, heating-performing, or stopped.

[0038] <Full Cooling Operation> Figure 3 is a diagram illustrating an example of refrigerant flow during full cooling operation of the air conditioning system 100 according to Embodiment 1. Here, in the flow path switching device and on / off valves shown in Figure 3, valves outlined in white indicate an open state, and valves filled in black indicate a closed state (the same applies to the following figures). When the air conditioning system 100 according to Embodiment 1 performs full cooling operation, the first refrigerant circuit 10 circulates the refrigerant to perform cooling operation, and the second refrigerant circuit 20 stops. In addition, during full cooling operation, the heat transfer medium circulates in the first heat transfer medium circulation circuit 31, and the second heat transfer medium circulation circuit 32 stops. For this reason, the control device 5 opens the first flow path switching device 312 corresponding to the load device 4 that performs cooling operation, and closes the second flow path switching device 322.

[0039] In the first refrigerant circuit 10, the high-temperature, high-pressure gaseous refrigerant discharged from the first compressor 12 flows through the first cooling / heating flow path switching valve 13 to the heat source side heat exchanger 14, where it exchanges heat with the air outside the heat source unit 1 and condenses into a liquid. The condensed liquid refrigerant is depressurized by the first expansion mechanism 15, becoming a low-pressure gas-liquid two-phase refrigerant, which flows to the first heat transfer medium heat exchanger 11, where it exchanges heat with the heat transfer medium flowing through the first heat transfer medium circulation circuit 31 and evaporates into a gas. The gasified refrigerant passes through the first cooling / heating flow path switching valve 13 and is drawn into the first compressor 12.

[0040] On the other hand, in the first heat medium circulation circuit 31, the heat medium sucked by the first pump 311 is pressurized and sent out. When the sent-out heat medium passes through the first heat medium heat exchanger 11, it is cooled by the refrigerant circulating through the first refrigerant circuit 10. The cooled heat medium flows through the relay device 2 to the load-side heat exchanger 41 of the load device 4. Here, the temperature of the cooled heat medium is, for example, 7°C. The load-side heat exchanger 41 exchanges heat between the heat medium and indoor air in an indoor space. Through the heat exchange, the indoor air is cooled, and the heat medium is heated. The temperature of the heated heat medium is, for example, 12°C. The heated heat medium passes through the relay device 2, is sucked and pressurized by the first pump 311, and flows into the first heat medium heat exchanger 11 again.

[0041] <Full Heating Operation> FIG. 4 is a diagram illustrating an example of a refrigerant flow and the like in the full heating operation of the air conditioning apparatus 100 according to Embodiment 1. When the air conditioning apparatus 100 according to Embodiment 1 performs the full heating operation, the first refrigerant circuit 10 circulates refrigerant to perform the heating operation, and the second refrigerant circuit 20 stops. Further, in the full heating operation, the heat medium circulates in the first heat medium circulation circuit 31, and the second heat medium circulation circuit 32 stops. Therefore, the control device 5 opens the first flow path switching device 312 corresponding to the load device 4 performing the heating operation, and closes the second flow path switching device 322.

[0042] In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first cooling / heating flow path switching valve 13 and flows to the first heat medium heat exchanger 11. The refrigerant flowing into the first heat medium heat exchanger 11 exchanges heat with the heat medium flowing through the first heat medium circulation circuit 31, condenses and liquefies, is decompressed by the first expansion mechanism 15 to become a low-pressure gas-liquid two-phase refrigerant, and flows to the heat source-side heat exchanger 14. The gas-liquid two-phase refrigerant flowing into the heat source-side heat exchanger 14 exchanges heat with air outside the heat source device 1, evaporates and gasifies, passes through the first cooling / heating flow path switching valve 13, and is sucked into the first compressor 12.

[0043] Meanwhile, in the first heat transfer medium circulation circuit 31, the first pump 311 pressurizes and sends out the heat transfer medium it has drawn in. The sent-out heat transfer medium passes through the first heat transfer medium heat exchanger 11 and is heated by the refrigerant circulating in the first refrigerant circuit 10. The heated heat transfer medium flows through the relay unit 2 to the load-side heat exchanger 41 of the load device 4. Here, the temperature of the heated heat transfer medium is, for example, 45°C. The load-side heat exchanger 41 exchanges heat between the heat transfer medium and the indoor air in the indoor space. Through heat exchange, the indoor air is heated and the heat transfer medium is cooled. The temperature of the cooled heat transfer medium is, for example, 35°C. The cooled heat transfer medium passes through the relay unit 2, is drawn in and pressurized by the first pump 311, and flows back into the first heat transfer medium heat exchanger 11.

[0044] <Cooling-Focused Operation> Figure 5 is a diagram illustrating an example of refrigerant flow during cooling-focused operation of the air conditioning system 100 according to Embodiment 1. Here, it is explained that load devices 4A and 4C perform cooling operation, and load device 4B performs heating operation. When the air conditioning system 100 according to Embodiment 1 performs cooling-focused operation, the first refrigerant circuit 10 circulates the refrigerant to perform cooling operation, and the second refrigerant circuit 20 circulates the refrigerant to perform heating operation. In addition, during cooling-focused operation, the first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the heated heat transfer medium. For this reason, during cooling-focused operation, the first flow path switching device 312 corresponding to the load device 4 performing cooling operation is opened, and the second flow path switching device 322 is closed. On the other hand, the first flow path switching device 312 corresponding to the load device 4 performing heating operation is closed, and the second flow path switching device 322 is opened.

[0045] In the first refrigerant circuit 10, the high-temperature, high-pressure gaseous refrigerant discharged from the first compressor 12 flows through the first cooling / heating flow path switching valve 13 to the heat source side heat exchanger 14, where it exchanges heat with the air outside the heat source unit 1 and condenses into a liquid. The condensed liquid refrigerant is depressurized by the first expansion mechanism 15, becoming a low-pressure gas-liquid two-phase refrigerant, which flows to the first heat transfer medium heat exchanger 11, where it exchanges heat with the heat transfer medium flowing through the first heat transfer medium circulation circuit 31 and evaporates into a gas. The gasified refrigerant passes through the first cooling / heating flow path switching valve 13 and is drawn into the first compressor 12.

[0046] On the other hand, in the first heat medium circulation circuit 31, the first pump 311 pressurizes and delivers the sucked heat medium. The delivered heat medium passes through the first heat medium heat exchanger 11, is cooled by the refrigerant circulating in the first refrigerant circuit 10, and flows to the load-side heat exchanger 41 of the load device 4. Here, the temperature of the cooled heat medium is, for example, 7°C. The load-side heat exchanger 41 exchanges heat between the heat medium and indoor air in an indoor space. Through the heat exchange, the indoor air is cooled and the heat medium is heated. The temperature of the heated heat medium is, for example, 12°C. The heated heat medium is sucked and pressurized by the first pump 311 via the relay device 2, and flows into the first heat medium heat exchanger 11 again. Here, when passing through the relay device 2, the heat medium is cooled by the second heat medium heat exchanger 21.

[0047] Further, in the second refrigerant circuit 20, the high-temperature and high-pressure gas refrigerant discharged from the second compressor 23 passes through the second cooling / heating flow path switching valve 24 and flows to the third heat medium heat exchanger 22. The refrigerant that has flowed into the third heat medium heat exchanger 22 exchanges heat with the heat medium flowing in the second heat medium circulation circuit 32, condenses and liquefies, is depressurized by the second expansion mechanism 25, becomes a low-pressure gas-liquid two-phase refrigerant, and flows to the second heat medium heat exchanger 21. The gas-liquid two-phase refrigerant that has flowed into the second heat medium heat exchanger 21 exchanges heat with the heat medium flowing in the first heat medium circulation circuit 31, evaporates and gasifies, passes through the second cooling / heating flow path switching valve 24, and is sucked into the second compressor 23.

[0048] On the other hand, in the second heat medium circulation circuit 32, the second pump 321 pressurizes and delivers the sucked heat medium. The delivered heat medium passes through the third heat medium heat exchanger 22, and is heated by the refrigerant circulating in the second refrigerant circuit 20. The heated heat medium flows to the load-side heat exchanger 41 of the load device 4 via the heat medium piping 301. Here, the temperature of the heated heat medium is, for example, 45°C. The load-side heat exchanger 41 exchanges heat between the heat medium and indoor air in an indoor space. Through the heat exchange, the indoor air is heated and the heat medium is cooled. The temperature of the cooled heat medium is, for example, 35°C. The cooled heat medium flows to the relay device 2 via the heat medium piping 301, and flows into the third heat medium heat exchanger 22 again.

[0049] <Heating-focused operation> Figure 6 is a diagram illustrating an example of refrigerant flow during cooling-focused operation of the air conditioning system 100 according to Embodiment 1. Here, it is explained that load devices 4B and 4C perform heating operation, and load device 4A performs cooling operation. When the air conditioning system 100 according to Embodiment 1 performs heating-focused operation, the first refrigerant circuit 10 circulates the refrigerant to perform heating operation, and the second refrigerant circuit 20 circulates the refrigerant to perform cooling operation. In addition, during heating-focused operation, the first heat transfer medium circulation circuit 31 circulates the heated heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the cooled heat transfer medium. For this reason, during heating-focused operation, the first flow path switching device 312 corresponding to the load device 4 performing heating operation is opened, and the second flow path switching device 322 is closed. On the other hand, the first flow path switching device 312 corresponding to the load device 4 performing cooling operation is closed, and the second flow path switching device 322 is opened.

[0050] In the first refrigerant circuit 10, the high-temperature, high-pressure gaseous refrigerant discharged from the first compressor 12 passes through the first cooling / heating flow path switching valve 13 and flows to the first heat transfer medium heat exchanger 11. The refrigerant that flows to the first heat transfer medium heat exchanger 11 exchanges heat with the heat transfer medium flowing through the first heat transfer medium circulation circuit 31, condenses and liquefies, is depressurized by the first expansion mechanism 15 to become a low-pressure gas-liquid two-phase refrigerant, and flows to the heat source side heat exchanger 14. The gas-liquid two-phase refrigerant that flows to the heat source side heat exchanger 14 exchanges heat with the air outside the heat source unit 1, evaporates and becomes a gas, passes through the first cooling / heating flow path switching valve 13 and is drawn into the first compressor 12.

[0051] Meanwhile, in the first heat transfer medium circulation circuit 31, the first pump 311 pressurizes and sends out the heat transfer medium it has drawn in. After passing through the first heat transfer medium heat exchanger 11, the sent-out heat transfer medium is heated by the refrigerant circulating in the first refrigerant circuit 10. The heated heat transfer medium flows through the relay unit 2 to the load-side heat exchanger 41 of the load device 4. Here, the temperature of the heated heat transfer medium is, for example, 45°C. The load-side heat exchanger 41 exchanges heat between the heat transfer medium and the indoor air in the indoor space. Through heat exchange, the indoor air is heated and the heat transfer medium is cooled. The temperature of the cooled heat transfer medium is, for example, 35°C. The cooled heat transfer medium passes through the relay unit 2, is drawn in and pressurized by the first pump 311, and flows back into the first heat transfer medium heat exchanger 11. Here, as it passes through the relay unit 2, the heat transfer medium is heated by the second heat transfer medium heat exchanger 21.

[0052] In the second refrigerant circuit 20, the high-temperature, high-pressure gaseous refrigerant discharged from the second compressor 23 passes through the second heating / cooling flow path switching valve 24 and flows to the second heat transfer medium heat exchanger 21. The refrigerant that flows to the second heat transfer medium heat exchanger 21 exchanges heat with the heat transfer medium flowing through the first heat transfer medium circulation circuit 31, condenses and liquefies, is depressurized by the second expansion mechanism 25 to become a low-pressure gas-liquid two-phase refrigerant, and flows to the third heat transfer medium heat exchanger 22. The gas-liquid two-phase refrigerant that flows to the third heat transfer medium heat exchanger 22 exchanges heat with the heat transfer medium flowing through the second heat transfer medium circulation circuit 32, evaporates and becomes a gas, passes through the second heating / cooling flow path switching valve 24, and is drawn into the second compressor 23.

[0053] Meanwhile, in the second heat transfer medium circulation circuit 32, the heat transfer medium drawn in by the first pump 311 is pressurized and sent out. The sent-out heat transfer medium passes through the third heat transfer medium heat exchanger 22 and is cooled by the refrigerant circulating in the second refrigerant circuit 20. The cooled heat transfer medium flows through the heat transfer medium piping 301 to the load-side heat exchanger 41 of the load device 4. Here, the temperature of the cooled heat transfer medium is, for example, 7°C. The load-side heat exchanger 41 exchanges heat between the heat transfer medium and the indoor air in the indoor space. Through heat exchange, the indoor air is cooled and the heat transfer medium is heated. The temperature of the heated heat transfer medium is, for example, 12°C. The heated heat transfer medium flows through the heat transfer medium piping 301 to the relay unit 2 and flows back into the third heat transfer medium heat exchanger 22.

[0054] Here, depending on the operating state of the air conditioning system 100 according to Embodiment 1, the operating mode may change from full cooling operation to heating-dominant operation, from full heating operation to cooling-dominant operation, from cooling-dominant operation to heating-dominant operation, or from heating-dominant operation to cooling-dominant operation. At this time, the heating operation and cooling operation are swapped in the first refrigerant circuit 10. Also, when the operation changes from cooling-dominant operation to heating-dominant operation or from heating-dominant operation to cooling-dominant operation, the operation of the second refrigerant circuit 20 is also swapped. As a result, the temperature of the heat transfer medium circulating in the first heat transfer medium circulation circuit 31 and the second heat transfer medium circulation circuit 32 also changes.

[0055] In a circuit configuration where the temperature range of the heat transfer medium changes depending on the operating mode, from the time the operating mode is changed until the operation stabilizes, a heat transfer medium with a different temperature target will pass through the load device 4 that continues the same operation. The time from the time the operating mode is changed until the operation stabilizes is, for example, about 10 minutes. Therefore, in the air conditioning system 100 of Embodiment 1, each load device 4 has a bypass pipe 42 and a load-side switching device 43. Then, in the load device 4 through which a heat transfer medium with a different temperature range passes when the operating mode is changed, the load-side switching device 43 is switched so that the heat transfer medium passes through the bypass pipe 42 until the operation stabilizes.

[0056] Figure 7 illustrates the operation of the air conditioning system 100 according to Embodiment 1 when switching from cooling-dominant operation to heating-dominant operation. Here, we will explain the case where, as shown in Figure 7(a), load devices 4A and 4C perform cooling operation and load device 4B performs heating operation, and then, as shown in Figure 7(c), load device 4C changes to heating operation and the air conditioning system 100 switches to heating-dominant operation. Here, as mentioned above, each device operates based on the instructions given by the control device 5. Furthermore, when changing the operating mode, devices that do not require operations such as valve switching will remain in their current state (the same applies hereinafter).

[0057] As shown in Figure 7(a), in each load device 4, during cooling-dominant operation, the load-side switching device 43 closes the load-side bypass on-off valve 44, while the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are open. As mentioned above, during cooling-dominant operation of the air conditioning system 100, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 performs heating operation. Therefore, the first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the heated heat transfer medium.

[0058] When the operation of load device 4C is changed from cooling operation to heating operation, the heating load becomes larger, so the air conditioner 100 changes its operating mode to heating-dominant operation. In heating-dominant operation, the first refrigerant circuit 10 performs heating operation, and the second refrigerant circuit 20 performs cooling operation. As a result, the first heat transfer medium circulation circuit 31 circulates heated heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates cooled heat transfer medium.

[0059] During the change of operating mode, as shown in Figure 7(b), the first flow path switching device 312 corresponding to the load device 4A is closed and the second flow path switching device 322 is opened in the relay unit 2. The load-side bypass on-off valve 44 in the load device 4A is opened, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are closed. This prevents the heat transfer medium flowing through the second heat transfer medium circulation circuit 32, which is heated by the third heat transfer medium heat exchanger 22 during cooling-dominant operation, from flowing to the load-side heat exchanger 41 of the load device 4A. At this time, the load-side blower 47 of the load device 4A continues to operate.

[0060] Furthermore, in the relay unit 2, the first flow path switching device 312 and the second flow path switching device 322 corresponding to the load device 4B are closed. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31, cooled by the first heat transfer medium heat exchanger 11 and the second heat transfer medium heat exchanger 21, from flowing to the load-side heat exchanger 41 of the load device 4B during cooling-focused operation. At this time, the load-side blower 47 of the load device 4B continues to operate. However, as with the load device 4A, the first flow path switching device 312 corresponding to the load device 4B may be opened and the second flow path switching device 322 may be closed. In this case, in the load device 4B, the load-side bypass on-off valve 44 is opened, and the heat exchanger inlet on-off valve 45 and the heat exchanger outlet on-off valve 46 are closed to allow the heat transfer medium to flow through the bypass piping 42.

[0061] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4C is opened, and the second flow path switching device 322 is closed. Also, in the load device 4C, the load-side bypass on-off valve 44 is closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. This causes the heat transfer medium passing through the load-side heat exchanger 41 of the load device 4C to be replaced from a cooled heat transfer medium to a heated heat transfer medium. At this time, the load-side blower 47 of the load device 4C is stopped from operating.

[0062] Then, once the heating-focused operation stabilizes, as shown in Figure 7(c), in the relay unit 2, the first flow path switching device 312 corresponding to the load devices 4 performing heating operation (here, load devices 4B and 4C) is opened, and the second flow path switching device 322 is closed. Also, the first flow path switching device 312 corresponding to the load device 4 performing cooling operation (here, load device 4A) is closed, and the second flow path switching device 322 is opened. Furthermore, in the load-side switching device 43 of each load device 4, the load-side bypass on-off valve 44 is closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. Then, the load-side blowers 47 that were stopped in each load device 4 start to drive. At this time, equipment whose operation does not change remains in its current state. Also, for example, even if the number of load devices 4 increases, the operation of the equipment corresponding to the load devices 4 that continue to operate and the load devices 4 whose operation changes will be the same as described above (the same applies hereinafter).

[0063] Figure 8 illustrates the operation of switching from heating-dominant operation to cooling-dominant operation in the air conditioning system 100 according to Embodiment 1. Here, we will explain the case in which the system switches from heating-dominant operation, where load devices 4B and 4C perform heating operations and load device 4A performs cooling operations, as shown in Figure 8(a), to cooling-dominant operation, as shown in Figure 8(c), by changing load device 4C to cooling operations.

[0064] As shown in Figure 8(a), in each load device 4, during heating-dominant operation, the load-side switching device 43 closes the load-side bypass on-off valve 44, while the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are open. As mentioned above, during heating-dominant operation of the air conditioning system 100, the first refrigerant circuit 10 performs heating operation, and the second refrigerant circuit 20 performs cooling operation. Therefore, the first heat transfer medium circulation circuit 31 circulates the heated heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the cooled heat transfer medium.

[0065] When the load device 4C changes from heating operation to cooling operation, the cooling load becomes larger, so the air conditioning system 100 changes its operating mode to cooling-dominant operation. In cooling-dominant operation, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 performs heating operation. As a result, the first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the heated heat transfer medium.

[0066] During the change of operating mode, as shown in Figure 8(b), the first flow path switching device 312 and the second flow path switching device 322 corresponding to the load device 4A are closed in the relay unit 2. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31, heated by the first heat transfer medium heat exchanger 11 and the second heat transfer medium heat exchanger 21, from flowing to the load-side heat exchanger 41 of the load device 4A during heating-based operation. At this time, the load-side blower 47 of the load device 4A continues to operate. Here, as with the load device 4B described later, the first flow path switching device 312 corresponding to the load device 4A may be opened and the second flow path switching device 322 may be closed. At this time, in the load device 4A, the load-side bypass on-off valve 44 is opened, and the heat exchanger inlet on-off valve 45 and the heat exchanger outlet on-off valve 46 are closed to allow the heat transfer medium to flow through the bypass piping 42.

[0067] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4B is closed, and the second flow path switching device 322 is opened. Then, the load-side bypass on-off valve 44 in the load device 4B is opened, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are closed. This prevents the heat transfer medium of the second heat transfer medium circulation circuit 32, which has been cooled by the third heat transfer medium heat exchanger 22, from flowing to the load-side heat exchanger 41 of the load device 4B during heating-focused operation. At this time, the load-side blower 47 of the load device 4B continues to operate.

[0068] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4C is opened, and the second flow path switching device 322 is closed. Also, in the load device 4C, the load-side bypass on-off valve 44 is closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. This causes the heat transfer medium passing through the load-side heat exchanger 41 of the load device 4C to be replaced from a heated heat transfer medium to a cooled heat transfer medium. At this time, the load-side blower 47 of the load device 4C is stopped from operating.

[0069] Then, once the cooling-focused operation stabilizes, as shown in Figure 8(c), in the relay unit 2, the first flow path switching device 312 corresponding to the load devices 4 performing cooling operation (in this case, load devices 4A and 4C) is opened, and the second flow path switching device 322 is closed. Also, the first flow path switching device 312 corresponding to the load device 4 performing heating operation (in this case, load device 4B) is closed, and the second flow path switching device 322 is opened. Furthermore, in the load-side switching device 43 of each load device 4, the load-side bypass on-off valve 44 is closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. Then, the load-side blowers 47 that were stopped in each load device 4 start to drive. At this time, equipment whose operation does not change remains in its current state.

[0070] Figure 9 illustrates the operation of switching from full cooling operation to heating-dominant operation in the air conditioning system 100 according to Embodiment 1. Here, we will explain the case in which the system switches from full cooling operation, in which all load devices 4 are operating in cooling mode, as shown in Figure 9(a), to heating-dominant operation, as shown in Figure 9(c), when load devices 4B and 4C change to heating mode.

[0071] As shown in Figure 9(a), in each load device 4, during cooling operation, the load-side switching device 43 closes the load-side bypass on-off valve 44, and opens the heat exchanger inlet on-off valve 45 and the heat exchanger outlet on-off valve 46. As mentioned above, during full cooling operation of the air conditioning system 100, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 is stopped. Therefore, the cooled heat transfer medium circulates in the first heat transfer medium circulation circuit 31, and the second heat transfer medium circulation circuit 32 is stopped.

[0072] When the operation of load devices 4B and 4C is changed from cooling operation to heating operation, the heating load increases, so the air conditioner 100 changes its operating mode to heating-dominant operation. In heating-dominant operation, the first refrigerant circuit 10 performs heating operation, and the second refrigerant circuit 20 performs cooling operation. As a result, the first heat transfer medium circulation circuit 31 circulates heated heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates cooled heat transfer medium.

[0073] During the change of operating mode, as shown in Figure 9(b), the first flow path switching device 312 corresponding to the load device 4A is closed and the second flow path switching device 322 is opened in the relay unit 2. The load-side bypass on-off valve 44 in the load device 4A is opened, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are closed. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31 from flowing to the load-side heat exchanger 41 of the load device 4A. At this time, the load-side blower 47 of the load device 4A continues to operate.

[0074] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to load devices 4B and 4C is opened, and the second flow path switching device 322 is closed. In addition, the load-side bypass on-off valves 44 in load devices 4B and 4C are closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. This causes the heat transfer medium passing through the load-side heat exchangers 41 of load devices 4B and 4C to be replaced with the heat transfer medium of the heated first heat transfer medium circulation circuit 31. At this time, the load-side blowers 47 of load devices 4B and 4C continue to operate.

[0075] Then, once the heating-focused operation stabilizes, as shown in Figure 9(c), in the relay unit 2, the first flow path switching device 312 corresponding to the load devices 4 performing heating operation (in this case, load devices 4B and 4C) is opened, and the second flow path switching device 322 is closed. Also, the first flow path switching device 312 corresponding to the load device 4 performing cooling operation (in this case, load device 4A) is closed, and the second flow path switching device 322 is opened. Furthermore, in the load-side switching device 43 of each load device 4, the load-side bypass on-off valve 44 is closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. Then, the load-side blowers 47 that were stopped in each load device 4 start to drive. At this time, equipment whose operation does not change remains in its current state.

[0076] Figure 10 illustrates the operation of switching from full heating operation to cooling-dominant operation in the air conditioning system 100 according to Embodiment 1. Here, we will explain the case in which the system switches from full heating operation, in which all load devices 4 are operating in heating mode, as shown in Figure 10(a), to cooling-dominant operation, as shown in Figure 10(c), when load devices 4A and 4C change to cooling mode.

[0077] As shown in Figure 10(a), in each load device 4, during heating operation, the load-side switching device 43 closes the load-side bypass on-off valve 44, and opens the heat exchanger inlet on-off valve 45 and the heat exchanger outlet on-off valve 46. As mentioned above, during full heating operation of the air conditioning system 100, the first refrigerant circuit 10 performs heating operation, and the second refrigerant circuit 20 is stopped. Therefore, the heated heat transfer medium circulates in the first heat transfer medium circulation circuit 31, and the second heat transfer medium circulation circuit 32 is stopped.

[0078] When the operation of load devices 4A and 4C is changed from heating operation to cooling operation, the cooling load increases, so the air conditioner 100 changes its operating mode to cooling-dominant operation. In cooling-dominant operation, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 performs heating operation. As a result, the first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the heated heat transfer medium.

[0079] During the change of operating mode, as shown in Figure 10(b), in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4B is closed, and the second flow path switching device 322 is opened. Then, the load-side bypass on-off valve 44 in the load device 4B is opened, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are closed. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31 from flowing to the load-side heat exchanger 41 of the load device 4B. At this time, the load-side blower 47 of the load device 4B continues to operate.

[0080] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to load devices 4A and 4C is opened, and the second flow path switching device 322 is closed. In addition, the load-side bypass on-off valves 44 in load devices 4A and 4C are closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. This causes the heat transfer medium passing through the load-side heat exchangers 41 of load devices 4A and 4C to be replaced with the heat transfer medium of the cooled first heat transfer medium circulation circuit 31. At this time, the load-side blowers 47 of load devices 4A and 4C are stopped.

[0081] Then, once the cooling-focused operation stabilizes, as shown in Figure 10(c), in the relay unit 2, the first flow path switching device 312 corresponding to the load devices 4 performing cooling operation (here, load devices 4A and 4C) is opened, and the second flow path switching device 322 is closed. Also, the first flow path switching device 312 corresponding to the load device 4 performing heating operation (here, load device 4B) is closed, and the second flow path switching device 322 is opened. Furthermore, in the load-side switching device 43 of each load device 4, the load-side bypass on-off valve 44 is closed, and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened. Then, the load-side blowers 47 that were stopped in each load device 4 start to drive. At this time, equipment whose operation does not change remains in its current state.

[0082] As described above, the air conditioning system 100 according to Embodiment 1 includes a first refrigerant circuit 10 and a second refrigerant circuit 20 that function as heating and cooling devices. The first refrigerant circuit 10 can heat or cool the heat transfer medium in the first heat transfer medium circulation circuit 31, and the second refrigerant circuit 20 can heat or cool the heat transfer medium in the second heat transfer medium circulation circuit 32. Then, the first flow path switching device 312 and the second flow path switching device 322 pass either the heat transfer medium of the first heat transfer medium circulation circuit 31 or the heat transfer medium of the second heat transfer medium circulation circuit 32 through the load-side heat exchanger 41 of the load device 4, and the transported heat is supplied to a heat load such as room air.

[0083] In this embodiment, the air conditioning system 100 has a bypass pipe 42 and a load-side switching device 43 for each load device 4, and the heat transfer medium is passed through the bypass pipe 42 by switching the load-side switching device 43. Therefore, by changing the operating mode of the air conditioning system 100, the load-side heat exchanger 41 of the load device 4 that continues the same operation can block a heat transfer medium that is in a different temperature range for operation and allow it to pass through the bypass pipe 42, which is a separate flow path. Thus, it is possible to suppress changes in the heat supplied to the air-conditioned space during the change in operating mode and suppress a decrease in the overall operating efficiency of the system.

[0084] Furthermore, in the first embodiment of the air conditioning system 100, each load device 4 has a bypass pipe 42 and a load-side switching device 43, allowing control to be performed in accordance with each load device 4.

[0085] Furthermore, in the first embodiment of the air conditioning system 100, the heat source unit 1 installed outdoors has a first refrigerant circuit 10, and the relay unit 2 installed indoors has a second refrigerant circuit 20. Therefore, since the heat source unit 1 is not subject to as many installation constraints as the relay unit 2, it becomes easier to configure the first refrigerant circuit 10 with equipment that has high heating and cooling capacities.

[0086] Furthermore, the air conditioning system 100 according to Embodiment 1 can perform a full cooling operation mode, a full heating operation mode, a cooling-dominant operation mode, and a heating-dominant operation mode. Therefore, simultaneous cooling and heating operation can be performed efficiently.

[0087] Embodiment 2. Figure 11 shows an example of the configuration of the air conditioning system 100 according to Embodiment 2. In Figure 11, equipment and other items that are denoted by the same reference numerals as in Figure 2, etc., perform the same operations as those described in Embodiment 1, unless otherwise specified. In Embodiment 2, the air conditioning system 100 has a repeater bypass pipe 33 and a repeater-side switching device 34 instead of the bypass pipe 42 and load-side switching device 43 that the load device 4 has in Embodiment 1.

[0088] The relay bypass piping 33 includes a first bypass piping 331 and a second bypass piping 332. The first bypass piping 331 is installed in the first heat transfer medium circulation circuit 31 and is connected between the heat transfer medium piping 301 that is the supply side of the heat transfer medium (hereinafter referred to as the supply side piping) and the heat transfer medium piping 301 that is the return side (hereinafter referred to as the return side piping). The first bypass piping 331 bypasses the heat transfer medium cooled or heated by the first refrigerant circuit 10 from the supply side piping to the return side piping. The second bypass piping 332 is installed in the second heat transfer medium circulation circuit 32 and is connected between the supply side piping and the return side piping of the heat transfer medium, bypassing the heat transfer medium cooled or heated by the second refrigerant circuit 20 from the supply side piping to the return side piping.

[0089] The relay-side switching device 34 (first relay-side switching device 341 and second relay-side switching device 342) is a heat transfer medium switching device that switches the flow path so that the heat transfer medium passes through either the first flow path switching device 312 or the second flow path switching device 322, or the relay bypass piping 33. The first relay-side switching device 341 is installed in the first heat transfer medium circulation circuit 31, and the second relay-side switching device 342 is installed in the second heat transfer medium circulation circuit 32. The relay-side switching device 34 has a relay bypass on / off valve 35, a supply on / off valve 36, and a return on / off valve 37. Specifically, the first relay-side switching device 341 has a first relay bypass on / off valve 351, a first supply on / off valve 361, and a first return on / off valve 371. The second relay-side switching device 342 has a second relay bypass on / off valve 352, a second supply on / off valve 362, and a second return on / off valve 372. Each on-off valve is a two-way valve that allows the heat transfer medium to pass through when open and blocks the passage of the heat transfer medium when closed. Here, either the supply-side on-off valve 36 or the return-side on-off valve 37 may be omitted. Alternatively, the relay bypass on-off valve 35, the supply-side on-off valve 36, and the return-side on-off valve 37 may be integrated by configuring the load-side switching device 43 with a three-way valve.

[0090] The first repeater bypass on / off valve 351 is installed in the first bypass piping 331 and, by opening and closing, controls the passage and blocking of the heat transfer medium in the first bypass piping 331. The second repeater bypass on / off valve 352 is installed in the second bypass piping 332 and, by opening and closing, controls the passage and blocking of the heat transfer medium in the second bypass piping 332.

[0091] The first supply-side shut-off valve 361 is installed in the supply-side piping of the first heat transfer fluid piping 313, and its opening and closing controls the passage and blocking of the heat transfer fluid in the supply-side piping. The second supply-side shut-off valve 362 is installed in the supply-side piping of the second heat transfer fluid piping 323, and its opening and closing controls the passage and blocking of the heat transfer fluid in the supply-side piping.

[0092] The first return valve 371 is installed in the return piping of the first heat transfer fluid piping 313, and its opening and closing controls the passage and blocking of the heat transfer fluid in the return piping. The second return valve 372 is installed in the return piping of the second heat transfer fluid piping 323, and its opening and closing controls the passage and blocking of the heat transfer fluid in the return piping.

[0093] Figure 12 illustrates the operation of switching from cooling-dominant operation to heating-dominant operation in the air conditioning system 100 according to Embodiment 2. Here, we will explain the case where, as shown in Figure 12(a), load devices 4A and 4C perform cooling operation and load device 4B performs heating operation, and then, as shown in Figure 12(c), load device 4C changes to heating operation and the air conditioning system 100 changes to heating-dominant operation.

[0094] As shown in Figure 12(a), during cooling-focused operation, the repeater bypass valves 35 (first repeater bypass valve 351 and second repeater bypass valve 352) in the repeater 2 are closed. On the other hand, the supply valves 36 (first supply valve 361 and second supply valve 362) and return valves 37 (first return valve 371 and second return valve 372) are open. As mentioned above, in cooling-focused operation of the air conditioner 100, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 performs heating operation. The first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the heated heat transfer medium.

[0095] When the operation of load device 4C is changed from cooling operation to heating operation, the heating load becomes larger, so the air conditioner 100 changes its operating mode to heating-dominant operation. In heating-dominant operation, the first refrigerant circuit 10 performs heating operation, and the second refrigerant circuit 20 performs cooling operation. As a result, the first heat transfer medium circulation circuit 31 circulates heated heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates cooled heat transfer medium.

[0096] During the change of operating mode, as shown in Figure 12(b), in the repeater 2, the first repeater bypass on-off valve 351 is opened, and the second supply side on-off valve 362 and the second return side on-off valve 372 are closed. On the other hand, the second repeater bypass on-off valve 352 is opened, and the second supply side on-off valve 362 and the second return side on-off valve 372 are closed.

[0097] Then, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4A is closed, and the second flow path switching device 322 is opened. This prevents the heat transfer medium that flows through the second heat transfer medium circulation circuit 32, which is heated by the third heat transfer medium heat exchanger 22, from flowing to the load-side heat exchanger 41 of the load device 4A during cooling-focused operation. At this time, the load-side blower 47 of the load device 4A continues to operate.

[0098] Furthermore, in the relay unit 2, the first flow path switching device 312 and the second flow path switching device 322 corresponding to the load device 4B are closed. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31, cooled by the first heat transfer medium heat exchanger 11 and the second heat transfer medium heat exchanger 21, from flowing to the load-side heat exchanger 41 of the load device 4B during cooling-focused operation. At this time, the load-side blower 47 of the load device 4B continues to operate. Here, the second flow path switching device 322 corresponding to the load device 4B is closed, but since the second supply-side on-off valve 362 and the second return-side on-off valve 372 are closed in the relay unit 2, the second flow path switching device 322 may be opened.

[0099] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4C is opened, and the second flow path switching device 322 is closed. This causes the heat transfer medium passing through the load-side heat exchanger 41 of the load device 4C to be replaced from a cooled heat transfer medium to a heated heat transfer medium. At this time, the load-side blower 47 of the load device 4C is stopped.

[0100] Once the heating-focused operation stabilizes, as shown in Figure 12(c), the second repeater bypass shut-off valve 352 in the repeater 2 is closed, and the second supply-side shut-off valve 362 and the second return-side shut-off valve 372 are opened. Also, the first flow path switching device 312 corresponding to the load devices 4 performing heating operation (here, load devices 4B and 4C) is opened, and the second flow path switching device 322 is closed. Then, the first flow path switching device 312 corresponding to the load device 4 performing cooling operation (here, load device 4A) is closed, and the second flow path switching device 322 is opened. At this point, the load-side blowers 47 that were stopped in each load device 4 begin to operate. Equipment whose operation does not change remains in its current state.

[0101] Figure 13 illustrates the operation of switching from heating-dominant operation to cooling-dominant operation in the air conditioning system 100 according to Embodiment 2. Here, we will explain the case in which the system switches from heating-dominant operation, where load devices 4B and 4C perform heating operations and load device 4A performs cooling operations, as shown in Figure 13(a), to cooling-dominant operation, as shown in Figure 13(c), by changing load device 4C to cooling operations.

[0102] As shown in Figure 13(a), during heating-focused operation, the relay bypass valves 35 (first relay bypass valve 351 and second relay bypass valve 352) in the relay unit 2 are closed. On the other hand, the supply valves 36 (first supply valve 361 and second supply valve 362) and the return valves 37 (first return valve 371 and second return valve 372) are open. As mentioned above, in heating-focused operation of the air conditioner 100, the first refrigerant circuit 10 performs heating operation, and the second refrigerant circuit 20 performs cooling operation. The first heat transfer medium circulation circuit 31 circulates the heated heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the cooled heat transfer medium.

[0103] When the load device 4C changes from heating operation to cooling operation, the cooling load becomes larger, so the air conditioning system 100 changes its operating mode to cooling-dominant operation. In cooling-dominant operation, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 performs heating operation. As a result, the first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the heated heat transfer medium.

[0104] During the change of operating mode, as shown in Figure 13(b), in the repeater 2, the first repeater bypass on-off valve 351 is opened, and the second supply side on-off valve 362 and the second return side on-off valve 372 are closed. On the other hand, the second repeater bypass on-off valve 352 is opened, and the second supply side on-off valve 362 and the second return side on-off valve 372 are closed.

[0105] Then, in the relay unit 2, the first flow path switching device 312 and the second flow path switching device 322 corresponding to the load device 4A are closed. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31, heated by the first heat transfer medium heat exchanger 11 and the second heat transfer medium heat exchanger 21, from flowing to the load-side heat exchanger 41 of the load device 4A during heating-focused operation. At this time, the load-side blower 47 of the load device 4A continues to operate. Here, the second flow path switching device 322 corresponding to the load device 4A is closed, but since the second supply-side on-off valve 362 and the second return-side on-off valve 372 are closed in the relay unit 2, the second flow path switching device 322 may be opened.

[0106] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4B is closed, and the second flow path switching device 322 is opened. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31, cooled by the first heat transfer medium heat exchanger 11 and the second heat transfer medium heat exchanger 21, from flowing to the load-side heat exchanger 41 of the load device 4B during heating-focused operation. At this time, the load-side blower 47 of the load device 4B continues to operate.

[0107] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4C is opened, and the second flow path switching device 322 is closed. This causes the heat transfer medium passing through the load-side heat exchanger 41 of the load device 4C to be replaced from a heated heat transfer medium to a cooled heat transfer medium. At this time, the load-side blower 47 of the load device 4C is stopped.

[0108] Once the cooling operation stabilizes, as shown in Figure 13(c), the second relay bypass shut-off valve 352 closes, and the second supply side shut-off valve 362 and the second return side shut-off valve 372 open. Also, the first flow path switching device 312 corresponding to the load devices 4 performing cooling operation (here, load devices 4A and 4C) opens, and the second flow path switching device 322 closes. Then, the first flow path switching device 312 corresponding to the load device 4 performing heating operation (here, load device 4B) closes, and the second flow path switching device 322 opens. At this point, the load-side blowers 47 that were stopped at each load device 4 start to drive. Equipment whose operation does not change remains in its current state.

[0109] Figure 14 illustrates the operation of switching from full cooling operation to heating-dominant operation in the air conditioning system 100 according to Embodiment 2. Here, we will explain the case in which the system switches from full cooling operation, in which all load devices 4 are operating in cooling mode, as shown in Figure 14(a), to heating-dominant operation, as shown in Figure 14(c), when load devices 4B and 4C change to heating mode.

[0110] As shown in Figure 14(a), during full cooling operation, the relay bypass valves 35 (first relay bypass valve 351 and second relay bypass valve 352) in the relay unit 2 are closed. On the other hand, the supply valves 36 (first supply valve 361 and second supply valve 362) and the return valves 37 (first return valve 371 and second return valve 372) are open. During full cooling operation of the air conditioning system 100, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 is stopped. The first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 is stopped.

[0111] When the operation of load devices 4B and 4C is changed from cooling operation to heating operation, the heating load increases, so the air conditioner 100 changes its operating mode to heating-dominant operation. In heating-dominant operation, the first refrigerant circuit 10 performs heating operation, and the second refrigerant circuit 20 performs cooling operation. As a result, the first heat transfer medium circulation circuit 31 circulates heated heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates cooled heat transfer medium.

[0112] During the change of operating mode, as shown in Figure 14(b), in the repeater 2, the first repeater bypass on-off valve 351 is opened, and the second supply on-off valve 362 and the second return on-off valve 372 are closed. On the other hand, the second repeater bypass on-off valve 352 is opened, and the second supply on-off valve 362 and the second return on-off valve 372 are closed.

[0113] Then, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4A is closed, and the second flow path switching device 322 is opened. This prevents the heat transfer medium of the second heat transfer medium circulation circuit 32 from flowing to the load-side heat exchanger 41 of the load device 4A. At this time, the load-side blower 47 of the load device 4A continues to operate.

[0114] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to load devices 4B and 4C is opened, and the second flow path switching device 322 is closed. This causes the heat transfer medium passing through the load-side heat exchanger 41 of load devices 4B and 4C to be replaced from a cooled heat transfer medium to a heated heat transfer medium. At this time, the load-side blowers 47 of load devices 4B and 4C are stopped.

[0115] Once the heating-focused operation stabilizes, as shown in Figure 14(c), the second repeater bypass shut-off valve 352 in the repeater 2 is closed, and the second supply-side shut-off valve 362 and the second return-side shut-off valve 372 are opened. Also, the first flow path switching device 312 corresponding to the load devices 4 performing heating operation (here, load devices 4B and 4C) is opened, and the second flow path switching device 322 is closed. Then, the first flow path switching device 312 corresponding to the load device 4 performing cooling operation (here, load device 4A) is closed, and the second flow path switching device 322 is opened. At this point, the load-side blowers 47 that were stopped in each load device 4 begin to operate. Equipment whose operation does not change remains in its current state.

[0116] Figure 15 illustrates the operation of switching from full heating operation to cooling-dominant operation in the air conditioning system 100 according to Embodiment 2. Here, we will explain the case in which the system switches from full heating operation, in which all load devices 4 are operating in heating mode, as shown in Figure 15(a), to cooling-dominant operation, as shown in Figure 15(c), when load devices 4A and 4C change to cooling mode.

[0117] As shown in Figure 15(a), during full heating operation, the relay bypass valves 35 (first relay bypass valve 351 and second relay bypass valve 352) in the relay unit 2 are closed. On the other hand, the supply side valves 36 (first supply side valve 361 and second supply side valve 362) and the return side valves 37 (first return side valve 371 and second return side valve 372) are open.

[0118] When the operation of load devices 4A and 4C is changed from heating operation to cooling operation, the cooling load increases, so the air conditioner 100 changes its operating mode to cooling-dominant operation. In cooling-dominant operation, the first refrigerant circuit 10 performs cooling operation, and the second refrigerant circuit 20 performs heating operation. As a result, the first heat transfer medium circulation circuit 31 circulates the cooled heat transfer medium, and the second heat transfer medium circulation circuit 32 circulates the heated heat transfer medium.

[0119] During the change of operating mode, as shown in Figure 15(b), in the repeater 2, the first repeater bypass on-off valve 351 is opened, and the second supply side on-off valve 362 and the second return side on-off valve 372 are closed. On the other hand, the second repeater bypass on-off valve 352 is opened, and the second supply side on-off valve 362 and the second return side on-off valve 372 are closed.

[0120] Then, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4B is closed, and the second flow path switching device 322 is opened. This prevents the heat transfer medium of the first heat transfer medium circulation circuit 31 from flowing to the load-side heat exchanger 41 of the load device 4B. At this time, the load-side blower 47 of the load device 4B continues to operate.

[0121] Furthermore, in the relay unit 2, the first flow path switching device 312 corresponding to load devices 4A and 4C is opened, and the second flow path switching device 322 is closed. This causes the heat transfer medium passing through the load-side heat exchanger 41 of load devices 4A and 4C to be replaced from a heated heat transfer medium to a cooled heat transfer medium. At this time, the load-side blowers 47 of load devices 4A and 4C are stopped.

[0122] Then, once the cooling-focused operation stabilizes, as shown in Figure 15(c), the second relay bypass shut-off valve 352 closes, and the second supply-side shut-off valve 362 and the second return-side shut-off valve 372 open. Also, the first flow path switching device 312 corresponding to the load devices 4 performing cooling operation (in this case, load devices 4A and 4C) opens, and the second flow path switching device 322 closes. Then, the first flow path switching device 312 corresponding to the load device 4 performing heating operation (in this case, load device 4B) closes, and the second flow path switching device 322 opens. At this point, the load-side blowers 47 that were stopped at each load device 4 begin to operate. At this time, equipment whose operation does not change remains in its current state.

[0123] As described above, the air conditioning system 100 according to Embodiment 2 has a relay unit 2 that includes a relay unit bypass pipe 33 and a relay-side switching device 34. Since it is not necessary to install a flow path switching device in each load device 4, the number of on-off valves constituting the switching device can be reduced.

[0124] Embodiment 3. In Embodiments 1 and 2 described above, the air conditioning system 100 opens and closes a valve, for example, by closing a bypass valve when the operating mode is changed, and then opens the bypass valve when the operation stabilizes. At this time, the method for determining whether the operation of the air conditioning system 100 is stable was not specifically mentioned. Therefore, Embodiment 3 describes an example of determining whether the operation of the air conditioning system 100 is stable. Here, we will describe the case in which the air conditioning system 100 with the configuration described in Embodiment 1 changes its operating mode from cooling-dominant operation to heating-dominant operation.

[0125] Figure 16 is a diagram illustrating the control flow in the air conditioning system 100 according to Embodiment 3. Here, the control device 5 is described as performing decisions and the like. When the operating mode of the air conditioning system 100 is changed, the control device 5 acquires the detected temperatures of the first heat medium temperature sensor 51 and the second heat medium temperature sensor 52 based on the signals sent from them (step S1). Here, the temperature of the heat medium detected by the first heat medium temperature sensor 51 is defined as the first heat medium detection temperature, and the temperature of the heat medium detected by the second heat medium temperature sensor 52 is defined as the second heat medium detection temperature.

[0126] The control device 5 determines whether the first heat transfer medium detection temperature is equal to or greater than a preset heating setting temperature (step S2). Here, the heating setting temperature is, for example, 45°C. If the control device 5 determines that the first heat transfer medium detection temperature is not equal to or greater than the heating setting temperature, it returns to step S1 and continues processing.

[0127] On the other hand, when the control device 5 determines that the temperature of the heat transfer medium is above the heating set temperature, it determines whether the detected temperature of the second heat transfer medium is below the preset cooling set temperature (step S3). Here, the cooling set temperature is, for example, 7°C. When the control device 5 determines that the detected temperature of the second heat transfer medium is not below the cooling set temperature, it returns to step S1 and continues processing.

[0128] On the other hand, when the control device 5 determines that the temperature of the heat transfer medium is below the cooling set temperature, it determines that the heating-dominant operation is stable and switches the various valves (step S4). In the heating-dominant operation, as shown in Figure 7(c) described in Embodiment 1, in the relay unit 2, the first flow path switching device 312 corresponding to the load device 4 performing heating operation is opened and the second flow path switching device 322 is closed. Also, the first flow path switching device 312 corresponding to the load device 4 performing cooling operation is closed and the second flow path switching device 322 is opened. Furthermore, in the load-side switching device 43 of each load device 4, the load-side bypass on-off valve 44 is closed and the heat exchanger inlet-side on-off valve 45 and the heat exchanger outlet-side on-off valve 46 are opened.

[0129] As described above, according to the air conditioning system 100 of Embodiment 3, the control device 5 determines whether the operation has stabilized after changing the operating mode, based on the temperatures detected by the first heat transfer medium temperature sensor 51 and the second heat transfer medium temperature sensor 52. Therefore, the air conditioning system 100 can determine the timing for closing the load-side bypass on / off valve 44 and restarting the passage of the heat transfer medium to the load-side heat exchanger 41 to be at an optimal timing. Here, the control device 5 may perform the processing of step S2 and the processing of step S3 in reverse order.

[0130] Embodiment 4. Figure 17 shows an example of the configuration of the air conditioning system 100 according to Embodiment 4. As shown in Figure 17, the bypass piping 42 and load-side switching device 43 (load-side bypass on / off valve 44, heat exchanger inlet on / off valve 45, and heat exchanger outlet on / off valve 46), which were installed in each load device 4 in Embodiment 1, may be installed in the relay unit 2. Since the relay unit 2 has the bypass piping 42 and load-side switching device 43, there is no need to newly install them in the load device 4, and it can be applied to existing load devices 4 that do not have bypass piping 42, for example. In addition, the distance between the first flow path switching device 312 and the second flow path switching device 322 and the bypass piping 42, etc. is short, so the power to transport the heat transfer medium when bypassing can be saved.

[0131] In the air conditioning system 100 of Embodiment 2, it was described that the first bypass pipe 331 and the first relay-side switching device 341 are installed in the first heat transfer medium circulation circuit 31, but it is not necessary to limit the system to this. By installing the second bypass pipe 332 and the second relay-side switching device 342, it is possible to prevent heat transfer mediums of different temperature ranges from passing through the load device 4 that continues to operate in the same manner, even if the first bypass pipe 331 is not installed on the first heat transfer medium circulation circuit 31 side.

[0132] Furthermore, in the air conditioning system 100 of the third embodiment described above, the temperature of the heat medium heated or cooled in the first heat medium circulation circuit 31 was detected based on a first heat medium temperature sensor 51 installed on the refrigerant outlet side of the first heat medium heat exchanger 11. Also, the temperature of the heat medium heated or cooled in the second heat medium circulation circuit 32 was detected based on a second heat medium temperature sensor 52 installed on the refrigerant outlet side of the third heat medium heat exchanger 22. However, it is not limited to this. Any position that can detect the temperature of the heat medium heated or cooled by the first heat medium heat exchanger 11 and the third heat medium heat exchanger 22 and passing through the load-side heat exchanger 41 is acceptable. For example, a temperature sensor may be installed on the heat medium inflow side of one or more load-side heat exchangers 41 to detect the temperature of the heat medium flowing into one or more load-side heat exchangers 41.

[0133] In Embodiments 1 to 4, the heating and cooling device was a refrigeration cycle device having a refrigerant circuit, but it is not limited to this. It may be composed of other devices capable of heating and cooling.

[0134] In the embodiments described above, an air conditioning system 100 that uses indoor air as a load was explained. However, it is also possible to have a system that can simultaneously heat and cool loads such as water and air in multiple load devices 4, for example, by combining it with a hot water supply system.

[0135] 1 Heat source unit, 2 Repeater unit, 4, 4A, 4B, 4C Load device, 5 Control device, 5A Control unit, 5B Memory unit, 10 First refrigerant circuit, 11 First heat transfer fluid heat exchanger, 12 First compressor, 13 First cooling / heating flow path switching valve, 14 Heat source side heat exchanger, 15 First expansion mechanism, 16 Heat source side blower, 20 Second refrigerant circuit, 21 Second heat transfer fluid heat exchanger, 22 Third heat transfer fluid heat exchanger, 23 Second compressor, 24 Second cooling / heating flow path switching valve, 25 Second expansion mechanism, 30 Heat transfer fluid circulation circuit, 31 First heat transfer fluid circulation circuit, 32 Second heat transfer fluid circulation circuit, 33 Repeater bypass piping, 34 Repeater side switching device, 35 Repeater bypass on / off valve, 36 Supply side on / off valve, 37 Return side on / off valve, 41 Load side heat exchanger, 42 Bypass piping, 43 Load side switching device, 44 Load-side bypass shut-off valve, 45 Heat exchanger inlet-side shut-off valve, 46 Heat exchanger outlet-side shut-off valve, 47 Load-side blower, 51 First heat transfer medium temperature sensor, 52 Second heat transfer medium temperature sensor, 100 Air conditioning system, 200 Building, 301 Heat transfer medium piping, 311 First pump, 312 First flow path switching device, 313 First heat transfer medium piping, 321 Second pump, 322 Second flow path switching device, 323 Second heat transfer medium piping, 331 First bypass piping, 332 Second bypass piping, 341 First relay-side switching device, 342 Second relay-side switching device, 351 First relay bypass shut-off valve, 352 Second relay bypass shut-off valve, 361 First supply-side shut-off valve, 362 Second supply-side shut-off valve, 371 First return-side shut-off valve, 372 Second return-side shut-off valve.

Claims

1. A first heating and cooling device for heating or cooling a heat transfer medium that transports heat; a second heating and cooling device for cooling the heat transfer medium when the first heating and cooling device is heating the heat transfer medium, and heating the heat transfer medium when the first heating and cooling device is cooling the heat transfer medium; a first heat transfer medium circulation circuit through which the heat transfer medium, heated or cooled by heat exchange with the first heating and cooling device, circulates through heat transfer medium piping; a second heat transfer medium circulation circuit through which the heat transfer medium, heated or cooled by heat exchange with the second heating and cooling device, circulates through heat transfer medium piping; a plurality of load-side heat exchangers for heat exchange between the air of the air-conditioned space that is a heat load and the heat transfer medium; a flow path switching device for switching between connecting each of the load-side heat exchangers to the first heat transfer medium circulation circuit side or to the second heat transfer medium circulation circuit side; a bypass pipe connecting the heat transfer medium piping on the side through which the heat transfer medium flows toward the load-side heat exchanger and the heat transfer medium piping on the side through which the heat transfer medium returns from the load-side heat exchanger. An air conditioning system comprising a heat transfer medium switching device that switches between passing the heat transfer medium through the load-side heat exchanger or through the bypass piping.

2. The air conditioning system according to claim 1, wherein the bypass piping and the heat transfer medium switching device are installed between the flow path switching device and the load-side heat exchanger, corresponding to each of the load-side heat exchangers.

3. The air conditioning system according to claim 1, wherein the bypass piping and the heat transfer medium switching device are installed in the heat transfer medium piping that connects at least the second heating and cooling device and the flow path switching device in the second heat transfer medium circulation circuit.

4. An air conditioning system according to any one of claims 1 to 3, comprising: a plurality of load devices, each installed in the space to be air-conditioned and having the load-side heat exchanger; a heat source unit having the first heating and cooling device; and a relay unit having the second heating and cooling device, the bypass piping, the heat transfer medium switching device, and the flow path switching device.

5. An air conditioning system according to any one of claims 1 to 4, comprising: a full heating operation mode in which all load-side heat exchangers that are not in a stopped state heat the air in the space to be air-conditioned; a full cooling operation mode in which all load-side heat exchangers that are not in a stopped state cool the air in the space to be air-conditioned; and among operations in which some of the load-side heat exchangers that are not in a stopped state heat the air in the space to be air-conditioned and the other load-side heat exchangers cool the air in the space to be air-conditioned, a heating-dominant operation mode performed when the heating load is large and a cooling-dominant operation mode performed when the cooling load is large, wherein when changing operation from the cooling-dominant operation mode to the heating-dominant operation mode, from the heating-dominant operation mode to the cooling-dominant operation mode, from the full cooling operation mode to the heating-dominant operation mode, or from the full heating operation mode to the cooling-dominant operation mode, the heat transfer medium switching device is switched so that the heat transfer medium passes through the bypass piping.

6. An air conditioning system according to any one of claims 1 to 5, comprising: a first heat medium temperature sensor for detecting the temperature of the heat medium flowing out of the first heating and cooling device; a second heat medium temperature sensor for detecting the temperature of the heat medium flowing out of the second heating and cooling device; and a control device for performing control, wherein the control device controls the switching of the heat medium switching device to allow the heat medium to pass from the bypass piping to the load-side heat exchanger based on the temperatures detected by the first heat medium temperature sensor and the second heat medium temperature sensor.

7. An air conditioning system according to any one of claims 1 to 6, wherein at least one of the first heating / cooling device and the second heating / cooling device has a heat exchanger for exchanging heat between a refrigerant and the heat transfer medium, and a refrigerant circuit for circulating the refrigerant to heat or cool the heat transfer medium.

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