Air conditioning system

Abstract

To restrain a decrease in operation efficiency of an air conditioning system.SOLUTION: An air conditioning system 100 comprises: an outdoor unit 110 comprising a heat source side refrigerant circuit RC1; an indoor unit 120 comprising a utilization side refrigerant circuit RC4; a first communication pipe 11 and a third communication pipe 13 connecting the heat source side refrigerant circuit RC1 and the utilization side refrigerant circuit RC4; an outdoor air treatment part 130A comprising a first auxiliary refrigerant circuit RC21 including an air supply side auxiliary heat exchanger 131 connected to a first branch pipe 14 branching from the first communication pipe 11, and a second branch pipe 15 branching from the third communication pipe 13, and an air supply fan 137 for supplying outdoor air OA passed through the air supply side auxiliary heat exchanger 131, to a first space S11; a first shutoff valve 161 provided in the first branch pipe 14; and a second shutoff valve 162 provided in the second branch pipe 15. A flow of a refrigerant between the heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC21 is shut off by operation of the first shutoff valve 161 and the second shutoff valve 162.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an air conditioning system.

Background Art

[0002] Conventionally, there is known an air conditioning system in which a heat source unit, a plurality of user units, a supply air unit having an auxiliary heat exchanger, and an exhaust air unit having an auxiliary heat exchanger are connected by piping, and each of the units can be individually operated and stopped (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional air conditioning system, when any one of the user unit, the supply air unit, and the exhaust air unit is stopped, refrigerant may accumulate in the refrigerant circuit of the stopped unit, resulting in insufficient refrigerant in the entire system. In the air conditioning system, in order to prevent such a shortage of refrigerant amount, the electric valve that controls the refrigerant amount to each unit is not fully closed when the unit stops, and the refrigerant is circulated in the refrigerant circuit of each unit. Therefore, in the air conditioning system, evaporation, condensation, etc. of the refrigerant occur uselessly in the refrigerant circuit of each stopped unit, leading to a decrease in the operating efficiency of the air conditioning system.

[0005] An object of the present disclosure is to suppress a decrease in the operating efficiency of an air conditioning system.

Means for Solving the Problems

[0006] (1) The air conditioning system of this disclosure is A first unit having a first refrigerant circuit including a compressor and a first heat exchanger, A second unit is located in the first space and has a second refrigerant circuit including a second heat exchanger, Liquid-side piping and gas-side piping connecting the first refrigerant circuit and the second refrigerant circuit, An outside air processing unit having a first auxiliary refrigerant circuit including a first auxiliary heat exchanger connected to a first branch pipe branched from the liquid side piping and a second branch pipe branched from the gas side piping, and an outside air processing unit having an outside air supply fan that supplies outside air that has passed through the first auxiliary heat exchanger to the first space, A first shut-off valve provided in the first branch pipe, A second shut-off valve is provided in the second branch piping, Equipped with, The operation of the first shut-off valve and the second shut-off valve interrupts the flow of refrigerant between the first refrigerant circuit and the first auxiliary refrigerant circuit.

[0007] In the configuration described above, the first and second shut-off valves allow the first auxiliary refrigerant circuit to be completely isolated from the first refrigerant circuit. Therefore, when the outside air processing unit is stopped, evaporation, condensation, etc., of the refrigerant in the first auxiliary refrigerant circuit can be suppressed. This helps to suppress a decrease in the operating efficiency of the air conditioning system.

[0008] (2) Preferably, a temperature sensor for detecting the ambient temperature, The system includes a control unit that operates the air supply fan based on the ambient temperature detected by the temperature sensor, When the first space is being cooled and the outside air temperature falls below a predetermined temperature, The control unit closes the first shut-off valve and the second shut-off valve, and operates the air supply fan. With this configuration, if the outside air temperature falls below a predetermined temperature during cooling of the first space, the refrigerant passing through the first auxiliary heat exchanger is shut off, allowing the first space to be cooled using only the supply air fan.

[0009] (3) Preferably, the third unit is located in a second space different from the first space and further comprises a third refrigerant circuit including a third heat exchanger. The third refrigerant circuit is connected to the first refrigerant circuit by the liquid-side piping and the gas-side piping. With this configuration, during cooling, only the supply air fan can be operated in the first space to perform outside air cooling, while the cooling operation of the third unit can be continued in the second space.

[0010] (4) Preferably, an exhaust processing unit having a second auxiliary refrigerant circuit including a second auxiliary heat exchanger connected to a third branch pipe branched from the liquid side piping and a fourth branch pipe branched from the gas side piping, and an exhaust fan that discharges the air in the first space that has passed through the second auxiliary heat exchanger to the outside, The system further comprises a third shut-off valve provided in the third branch piping, The control unit, If the outside air temperature falls below a predetermined temperature while the first space is being cooled, the third shut-off valve is opened and the exhaust fan is operated. With this configuration, when cooling is performed, if the first space is cooled using outside air and the second space is cooled, the second auxiliary heat exchanger can recover heat from the exhaust of the first space. This allows the air conditioning system to operate efficiently.

[0011] (5) Preferably, a casing that houses the first auxiliary refrigerant circuit, the second auxiliary refrigerant circuit, the supply fan, and the exhaust fan, and has a supply passage through which air passing through the first auxiliary heat exchanger passes, and an exhaust passage through which air passing through the second auxiliary heat exchanger passes, A heat exchange unit that performs heat exchange between the air in the supply air passage before it passes through the first auxiliary heat exchanger and the air in the exhaust passage before it passes through the second auxiliary heat exchanger, To further prepare. According to this configuration, by adopting a form in which the outside air treatment unit, the exhaust gas treatment unit, and the heat exchange unit are housed in one casing, the piping configuration around the outside air treatment unit and the exhaust gas treatment unit can be simplified. Thereby, the connection work of the first refrigerant circuit, the first auxiliary refrigerant circuit, and the second auxiliary refrigerant circuit becomes easy.

[0012] (6) Preferably, the refrigerant is a flammable refrigerant. According to this configuration, when the refrigerant leaks from the outside air treatment unit and the exhaust gas treatment unit, by closing each shut-off valve, the amount of refrigerant leakage from the outside air treatment unit and the exhaust gas treatment unit can be suppressed.

Brief Description of the Drawings

[0013] % [Figure 1] It is a schematic configuration diagram of an air conditioning system according to the first embodiment of the present disclosure. [Figure 2] It is a refrigerant circuit diagram of an air conditioning system according to the first embodiment. [Figure 3] It is a schematic configuration diagram of a heat recovery unit according to the first embodiment. [Figure 4] It is a perspective view of the heat exchange unit. [Figure 5] It is a schematic cross-sectional explanatory view taken along the X-X line of FIG. 3. [Figure 6] It is a schematic cross-sectional explanatory view taken along the Y-Y line of FIG. 3. [Figure 7] It is a control block diagram of an air conditioning system according to the first embodiment. <000,092>[[ID=,4]] [Figure 8] It is a schematic configuration diagram of an air conditioning system according to the second embodiment of the present disclosure. [Figure 9] It is a refrigerant circuit diagram of an air conditioning system according to the second embodiment. [Figure 10] It is a schematic configuration diagram of a heat recovery unit according to the second embodiment. <000,098> [Figure 11] It is a control block diagram of an air conditioning system according to the second embodiment.

Modes for Carrying Out the Invention

[0014] The air conditioning system of this disclosure will be described in detail below with reference to the attached drawings. However, this disclosure is not limited to these examples and is intended to include all modifications within the meaning and scope equivalent to the claims as indicated by the claims.

[0015] Figure 1 shows the overall configuration of an air conditioning system according to the first embodiment of the present disclosure. The air conditioning system 100 shown in Figure 1 is the first embodiment of the air conditioning system of the present disclosure and is installed in buildings, factories, etc. to provide air conditioning for the space to be air-conditioned. The air conditioning system 100 comprises an air conditioner 101 and a refrigerant flow path switching device 140. The air conditioner 101 provides heating and cooling to the space to be air-conditioned by operating a vapor compression type refrigeration cycle. The air conditioner 101 shown in this embodiment uses R32 as the refrigerant. R32 is a refrigerant that is slightly flammable.

[0016] The air conditioning system 100 uses an indoor space S1 formed inside building B as the space to be air-conditioned. Multiple indoor spaces S1 are provided inside building B. In the following description, the first indoor space S1 will be referred to as the first space S11, the second indoor space S1, which is separate from the first space S11, will be referred to as the second space S12, and the space outside building B will be referred to as the outdoor space S2. In this disclosure, the outdoor space S2 is an outdoor space.

[0017] The air conditioner 101 has an outdoor unit 110 as a heat source unit, and an indoor unit 120 and a first heat recovery unit 130 as utilization units. In the air conditioner 101, two or more indoor units 120 and one first heat recovery unit 130 are connected to one outdoor unit 110. The indoor units 120 are connected to the outdoor unit 110 via a refrigerant flow path switching device 140. The air conditioner 101 can freely select cooling operation and heating operation for each indoor unit 120 using the refrigerant flow path switching device 140 to provide air conditioning for the target space. In this embodiment, a so-called cooling / heating-free system air conditioner system 100 is illustrated, but the air conditioner system disclosed herein does not have to be a cooling / heating-free system.

[0018] In the air conditioning system 100, an indoor unit 120 provided for the first space S11 provides air conditioning for the first space S11, and a first heat recovery unit 130 provides ventilation for the first space S11. In the air conditioning system 100, an indoor unit 120 provided for the second space S12 provides air conditioning for the second space S12. The outdoor unit 110 is installed in the outdoor space S2. The first heat recovery unit 130 is installed outside the indoor space S1 inside building B.

[0019] [Outdoor unit configuration] Figure 2 is a refrigerant circuit diagram of the air conditioning system 100. As shown in Figure 1, the outdoor unit 110 is installed outdoors, for example, on the rooftop or balcony of building B, or in an outdoor space S2 such as an underground area. As shown in Figure 2, various devices are arranged inside the outdoor unit 110, and these devices are connected via refrigerant piping to form the heat source side refrigerant circuit RC1. The heat source side refrigerant circuit RC1 is connected to the auxiliary refrigerant circuit RC2 in the first heat recovery unit 130 and the intermediate refrigerant circuit RC3 in the refrigerant flow path switching device 140 via the first connecting pipe 11, the second connecting pipe 12, and the third connecting pipe 13.

[0020] As shown in Figure 2, the heat source side refrigerant circuit RC1 includes a liquid side shut-off valve 21, a gas side first shut-off valve 22, a gas side second shut-off valve 23, an accumulator 24, a compressor 25, a first flow path switching valve 26, a second flow path switching valve 27, a third flow path switching valve 28, an outdoor heat exchanger 30, a first outdoor expansion valve 34, and a second outdoor expansion valve 35. The heat source side refrigerant circuit RC1 is constructed by connecting these components via multiple refrigerant pipes. The outdoor unit 110 houses an outdoor fan 33, a control unit 115 (see Figure 7), and the like.

[0021] The liquid-side shut-off valve 21, the gas-side first shut-off valve 22, and the gas-side second shut-off valve 23 are manual valves that are opened and closed during refrigerant charging, pump-down, etc. One end of the liquid-side shut-off valve 21 is connected to the first connecting pipe 11. The other end of the liquid-side shut-off valve 21 is connected to the refrigerant piping that extends to the first outdoor expansion valve 34 and the second outdoor expansion valve 35. One end of the gas-side first shut-off valve 22 is connected to the second connecting pipe 12. The other end of the gas-side first shut-off valve 22 is connected to the refrigerant piping that extends to the second flow path switching valve 27. One end of the gas-side second shut-off valve 23 is connected to the third connecting pipe 13. The other end of the gas-side second shut-off valve 23 is connected to the refrigerant piping 25c that extends to the accumulator 24.

[0022] The accumulator 24 is a container for temporarily storing the low-pressure refrigerant drawn into the compressor 25 and for separating the gaseous refrigerant from the liquid refrigerant.

[0023] The compressor 25 has a sealed structure that incorporates a compressor motor, and is a positive displacement compressor such as a scroll type or rotary type. The compressor 25 compresses the low-pressure refrigerant drawn in from the suction pipe 25b and then discharges it from the discharge pipe 25a. Refrigerant oil is contained inside the compressor 25. This refrigerant oil may circulate within the refrigerant circuit together with the refrigerant. The outdoor unit 110 in this embodiment is equipped with one compressor 25. However, the outdoor unit 110 may be equipped with two or more compressors 25 connected in parallel.

[0024] The first flow path switching valve 26, the second flow path switching valve 27, and the third flow path switching valve 28 are four-way switching valves. The first flow path switching valve 26, the second flow path switching valve 27, and the third flow path switching valve 28 switch the flow of refrigerant according to the operating status of the air conditioner 101. One of the refrigerant inlets of the first flow path switching valve 26, the second flow path switching valve 27, and the third flow path switching valve 28 is connected to the discharge pipe 25a or a branch pipe extending from the discharge pipe 25a. One of the refrigerant inlets of the first flow path switching valve 26, the second flow path switching valve 27, and the third flow path switching valve 28 is connected to a branch pipe extending from the refrigerant pipe 25c that connects the gas-side second shut-off valve 23 and the accumulator 24. The first flow path switching valve 26, the second flow path switching valve 27, and the third flow path switching valve 28 are configured to block the flow of refrigerant in one refrigerant flow path during operation, and effectively function as three-way valves.

[0025] The outdoor heat exchanger 30 is a cross-fin type or microchannel type heat exchanger. The outdoor heat exchanger 30 includes a first heat exchange section 31 and a second heat exchange section 32. The first heat exchange section 31 is located at the top of the outdoor heat exchanger 30, and the second heat exchange section 32 is located below the first heat exchange section 31.

[0026] The gas-side end of the first heat exchanger 31 is connected to a refrigerant pipe that extends to the third flow path switching valve 28. The liquid-side end of the first heat exchanger 31 is connected to a refrigerant pipe that extends to the first outdoor expansion valve 34.

[0027] The gas-side end of the second heat exchanger 32 is connected to a refrigerant pipe that extends to the first flow path switching valve 26. The liquid-side end of the second heat exchanger 32 is connected to a refrigerant pipe that extends to the second outdoor expansion valve 35.

[0028] The refrigerant passing through the first heat exchange section 31 and the second heat exchange section 32 exchanges heat with the airflow generated by the outdoor fan 33. The outdoor fan 33 is, for example, a propeller fan and is driven by an outdoor fan motor (not shown). The outdoor fan 33 generates an airflow that flows into the outdoor unit 110, passes through the outdoor heat exchanger 30, and flows out of the outdoor unit 110.

[0029] The first outdoor expansion valve 34 and the second outdoor expansion valve 35 are, for example, electrically operated valves whose opening degree can be adjusted. One end of the first outdoor expansion valve 34 is connected to a refrigerant pipe extending from the first heat exchange unit 31. The other end of the first outdoor expansion valve 34 is connected to a refrigerant pipe extending to the liquid side shut-off valve 21.

[0030] One end of the second outdoor expansion valve 35 is connected to the refrigerant piping extending from the second heat exchanger 32. The other end of the second outdoor expansion valve 35 is connected to the refrigerant piping extending to the liquid side shut-off valve 21. The opening degree of the first outdoor expansion valve 34 and the second outdoor expansion valve 35 is adjusted according to the operating conditions, and the refrigerant passing through them is reduced in pressure according to the opening degree.

[0031] The compressor 25, outdoor fan 33, first outdoor expansion valve 34, second outdoor expansion valve 35, first flow path switching valve 26, second flow path switching valve 27, and third flow path switching valve 28 are operated by the control unit 115 (see Figure 7). The control unit 115 of the outdoor unit 110 transmits and receives signals via a communication line to the indoor control unit 54 of the indoor unit 120 (see Figure 7) and the control unit (not shown) of the refrigerant flow path switching device 140.

[0032] [Indoor Unit Configuration] The indoor unit 120 is ceiling-mounted, ceiling-suspended, floor-standing, or wall-mounted. The air conditioning system 100 of this embodiment includes two or more indoor units 120.

[0033] A refrigerant circuit RC4 is provided inside the indoor unit 120. The refrigerant circuit RC4 comprises an indoor expansion valve 51 and an indoor heat exchanger 52. The refrigerant circuit RC4 is configured such that the indoor expansion valve 51 and the indoor heat exchanger 52 are connected by refrigerant piping.

[0034] The indoor unit 120 is equipped with an indoor fan 53 and an indoor control unit 54 (see Figure 7). The indoor expansion valve 51 is an electrically operated valve whose opening degree can be adjusted. One end of the indoor expansion valve 51 is connected to the liquid pipe LP. The other end of the indoor expansion valve 51 is connected to the refrigerant piping that extends to the indoor heat exchanger 52. The indoor expansion valve 51 reduces the pressure of the refrigerant passing through it according to its opening degree.

[0035] The indoor heat exchanger 52 is, for example, a cross-fin type or a microchannel type heat exchanger. The liquid side end of the indoor heat exchanger 52 is connected to the refrigerant piping extending from the indoor expansion valve 51. The gas side end of the indoor heat exchanger 52 is connected to the gas pipe GP. The refrigerant flowing into the indoor heat exchanger 52 exchanges heat with the airflow generated by the indoor fan 53 and is discharged from the indoor heat exchanger 52.

[0036] The indoor fan 53 is, for example, a cross-flow fan or a sirocco fan. The indoor fan 53 is driven by an indoor fan motor (not shown). The indoor fan 53 generates an airflow that flows from the indoor space into the indoor unit 120, passes through the indoor heat exchanger 52, and then flows out back into the indoor space.

[0037] The indoor expansion valve 51 and the indoor fan 53 are operated by the indoor control unit 54 (see Figure 7) of the indoor unit 120. The indoor control unit 54 is connected to the control unit 115 of the outdoor unit 110 and a remote controller (not shown). The indoor control unit 54 drives the indoor fan 53 and the indoor expansion valve 51 based on operating conditions such as the set temperature input to the remote controller.

[0038] [Configuration of refrigerant flow path switching device] As shown in Figures 1 and 2, the refrigerant flow path switching device 140 is installed between the outdoor unit 110 and the multiple indoor units 120. The refrigerant flow path switching device 140 has a casing 141. The refrigerant flow path switching device 140 switches the flow of refrigerant flowing into the outdoor unit 110 and each indoor unit 120. As shown in Figure 2, the casing 141 houses multiple header pipes 55, 56, 57, 58 and multiple switching units 70.

[0039] (Header pipe) As shown in Figure 2, the multiple header pipes 55, 56, 57, and 58 include a first header pipe 55, a second header pipe 56, a third header pipe 57, and a fourth header pipe 58. The first header pipe 55 is connected to the first connecting pipe 11. The second header pipe 56 is connected to the second connecting pipe 12. The third header pipe 57 is connected to the third connecting pipe 13.

[0040] (Switching unit) The refrigerant flow path switching device 140 comprises a plurality of switching units 70. Each switching unit 70 forms an intermediate refrigerant circuit RC3 of the refrigerant flow path switching device 140. Each switching unit 70 is connected to one indoor unit 120. However, it is not necessary for all switching units 70 of the refrigerant flow path switching device 140 to be connected to an indoor unit 120; there may be switching units 70 in the refrigerant flow path switching device 140 that are not connected to an indoor unit 120.

[0041] (Regarding the intermediate refrigerant circuit) The multiple switching units 70 all have the same structure, and the intermediate refrigerant circuit RC3 of each switching unit 70 is equipped with multiple valves EV1, EV2, EV3 and multiple refrigerant pipes.

[0042] In the switching unit 70, the multiple valves EV1, EV2, and EV3 include a first valve EV1, a second valve EV2, and a third valve EV3. These valves EV1, EV2, and EV3 are composed of electrically operated valves with adjustable opening degrees. The second valve EV2 and the third valve EV3 are controlled by a control unit (not shown) to take on one of the following states: fully closed, fully open, or with an adjustable opening degree. The first valve EV1 is controlled by a control unit (not shown) to take on one of the following states: minimum opening degree, fully open, fully closed, or with an adjustable opening degree.

[0043] The switching unit 70 includes a first refrigerant pipe P1 that connects the second header pipe 56 to the first valve EV1. A filter F1 is provided in the middle of the first refrigerant pipe P1. The switching unit 70 also includes a second refrigerant pipe P2. One end of the second refrigerant pipe P2 is connected to the first valve EV1. The switching unit 70 also includes a user-side gas piping 61. One end of the user-side gas piping 61 is connected to the gas pipe GP of the indoor unit 120. The other end of the user-side gas piping 61 is connected to the second valve EV2. The other end of the second refrigerant pipe P2 is connected to the user-side gas piping 61. A filter F2 is provided in the user-side gas piping 61.

[0044] The switching unit 70 is equipped with a third refrigerant pipe P3. One end of the third refrigerant pipe P3 is connected to the second valve EV2. The other end of the third refrigerant pipe P3 is connected to the third header pipe 57. A filter F3 is provided in the middle of the third refrigerant pipe P3.

[0045] The switching unit 70 is equipped with a user-side liquid pipe 62. One end of the user-side liquid pipe 62 is connected to the liquid pipe LP of the indoor unit 120. The other end of the user-side liquid pipe 62 is connected to the subcooled heat exchanger 59. Inside the subcooled heat exchanger 59 are a first heat transfer tube 59a and a second heat transfer tube 59b. The subcooled heat exchanger 59 performs heat exchange between the refrigerant flowing through the first heat transfer tube 59a and the refrigerant flowing through the second heat transfer tube 59b. The other end of the user-side liquid pipe 62 is connected to one end of the first heat transfer tube 59a.

[0046] The switching unit 70 is equipped with a fourth refrigerant pipe P4. One end of the fourth refrigerant pipe P4 is connected to the other end of the first heat transfer tube 59a. The other end of the fourth refrigerant pipe P4 is connected to the first header pipe 55.

[0047] The switching unit 70 includes a fifth refrigerant pipe P5 that branches off from the fourth refrigerant pipe P4. One end of the fifth refrigerant pipe P5 is connected to one end of the third valve EV3. A filter F4 is provided in the middle of the fifth refrigerant pipe P5.

[0048] The switching unit 70 includes a sixth refrigerant pipe P6 and a seventh refrigerant pipe P7. One end of the sixth refrigerant pipe P6 is connected to the third valve EV3. The other end of the sixth refrigerant pipe P6 is connected to one end of the second heat transfer tube 59b of the subcooled heat exchanger 59. One end of the seventh refrigerant pipe P7 is connected to the second heat transfer tube 59b of the subcooled heat exchanger 59. The other end of the seventh refrigerant pipe P7 is connected to the fourth header pipe 58. The fourth header pipe 58 is connected to the third header pipe 57 via a connecting pipe 63.

[0049] Refrigerant flows into the fourth header pipe 58 from the first header pipe 55 via the fourth refrigerant pipe P4, the fifth refrigerant pipe P5, the third valve EV3, the sixth refrigerant pipe P6, the subcooled heat exchanger 59, and the seventh refrigerant pipe P7. Furthermore, the refrigerant that has flowed into the fourth header pipe 58 flows into the third header pipe 57 through the connecting pipe 63.

[0050] [Configuration of the first heat recovery unit] The first heat recovery unit 130 is a device that supplies cooled and heated air (outside air) to the indoor space S1, and ventilates the indoor space S1 while recovering heat from the air (exhaust) discharged from the indoor space S1, and is also called an outside air processing unit. The first heat recovery unit 130 is located outside the indoor space S1 inside building B. The first heat recovery unit 130 is located in the space above the ceiling of the indoor space S1 and is connected to the indoor space S1 and the outdoor space S2 through a duct. In this embodiment, the case in which the first heat recovery unit 130 is located in the space above the ceiling of the indoor space S1 is illustrated, but the first heat recovery unit of this disclosure may be a ceiling-suspended type, a ceiling-embedded type, a floor-standing type, or a wall-mounted type, and may be located in a place other than above the ceiling. As shown in Figures 2 and 3, the first heat recovery unit 130 has an outside air processing unit 130A and an exhaust processing unit 130B, which include an auxiliary refrigerant circuit RC2. The outside air processing unit 130A has an air supply side auxiliary heat exchanger 131 and an air supply fan 137, with the air supply side auxiliary heat exchanger 131 constituting the first auxiliary refrigerant circuit RC21, which is part of the auxiliary refrigerant circuit RC2. The exhaust processing unit 130B has an exhaust side auxiliary heat exchanger 132 and an exhaust fan 138, with the exhaust side auxiliary heat exchanger 132 constituting the second auxiliary refrigerant circuit RC22, which is another part of the auxiliary refrigerant circuit RC2.

[0051] The supply-side auxiliary heat exchanger 131 and the exhaust-side auxiliary heat exchanger 132 are, for example, cross-fin type or microchannel type heat exchangers. The liquid-side end of the supply-side auxiliary heat exchanger 131 is connected to the first connecting pipe 11 via the first branch pipe 14. The gas-side end of the supply-side auxiliary heat exchanger 131 is connected to the third connecting pipe 13 via the second branch pipe 15, or to the second connecting pipe 12 via the second branch pipe 15 and the fifth branch pipe 18. A first electric valve 136a is provided in the middle of the first branch pipe 14.

[0052] One end of the fifth branch pipe 18 is connected to the second branch pipe 15. The other end of the fifth branch pipe 18 is connected to the second connecting pipe 12. The first switching valve 165 is positioned on the third connecting pipe 13 side of the connection point of the fifth branch pipe 18 in the second branch pipe 15. The second switching valve 166 is positioned in the middle of the fifth branch pipe 18.

[0053] The liquid side end of the exhaust-side auxiliary heat exchanger 132 is connected to the first connecting pipe 11 via the third branch pipe 16. The gas side end of the exhaust-side auxiliary heat exchanger 132 is connected to the third connecting pipe 13 via the fourth branch pipe 17, or to the second connecting pipe 12 via the fourth branch pipe 17 and the sixth branch pipe 19. A second electric valve 136b is provided in the middle of the third branch pipe 16.

[0054] One end of the sixth branch pipe 19 is connected to the fourth branch pipe 17. The other end of the sixth branch pipe 19 is connected to the second connecting pipe 12. The third switching valve 167 is positioned on the third connecting pipe 13 side of the connection point of the sixth branch pipe 19 in the fourth branch pipe 17. The fourth switching valve 168 is positioned in the middle of the sixth branch pipe 19.

[0055] The first electric valve 136a is a valve for adjusting the amount of refrigerant passing through the supply-side auxiliary heat exchanger 131. The second electric valve 136b is a valve for adjusting the amount of refrigerant passing through the exhaust-side auxiliary heat exchanger 132. The first electric valve 136a and the second electric valve 136b are electric valves whose opening degree can be adjusted.

[0056] The first auxiliary refrigerant circuit RC21 is connected to the first connecting pipe 11 via the first branch pipe 14, to the third connecting pipe 13 via the second branch pipe 15, and to the second connecting pipe 12 via the second branch pipe 15 and the fifth branch pipe 18. The second auxiliary refrigerant circuit RC22 is connected to the first connecting pipe 11 via the third branch pipe 16, to the third connecting pipe 13 via the fourth branch pipe 17, and to the second connecting pipe 12 via the fourth branch pipe 17 and the sixth branch pipe 19.

[0057] (Intake fan and exhaust fan) The first heat recovery unit 130 is equipped with an air supply fan 137 and an exhaust fan 138. The air supply fan 137 constitutes part of the outside air processing unit 130A, and the exhaust fan 138 constitutes part of the exhaust processing unit 130B. The air supply fan 137 and the exhaust fan 138 are, for example, sirocco fans. The air supply fan 137 is driven by an air supply fan motor (not shown). The air supply fan 137 generates an airflow that flows from the outdoor space S2 (see Figure 1) into the first heat recovery unit 130, passes through the air supply-side auxiliary heat exchanger 131, and then flows out to the first space S11 (see Figure 1). The exhaust fan 138 is driven by an exhaust fan motor (not shown). The exhaust fan 138 generates an airflow that flows from the first space S11 (see Figure 1) into the first heat recovery unit 130, passes through the exhaust-side auxiliary heat exchanger 132, and then flows out to the outdoor space S2 (see Figure 1).

[0058] (Air supply passage and exhaust passage) As shown in Figure 3, the return air intake 157 is used to take in air (return air) RA from the indoor space S1 (see Figure 1) into the casing 150. The return air intake 157 is connected to the indoor space S1 via a duct or the like (not shown). The exhaust outlet 155 is used to discharge the return air RA taken into the casing 150 as exhaust EA to the outdoor space S2 (see Figure 1). The exhaust outlet 155 is connected to the outdoor space S2 via a duct or the like (not shown). The outside air intake 158 is used to take in air (outside air) OA from the outdoor space S2 into the casing 150. The outside air intake 158 is connected to the outdoor space S2 via a duct or the like (not shown). The supply air outlet 156 is used to supply the outside air OA taken into the casing 150 as supply air SA to the indoor space S1. The air supply outlet 156 is connected to the indoor space S1 via a duct or the like (not shown).

[0059] (Heat exchange part) Figure 4 is a perspective view of the heat exchange section. As shown in Figure 4, the heat exchange section 134 in this embodiment is an orthogonal total heat exchanger configured such that the first airflow A1 and the second airflow A2 are substantially perpendicular to each other. This heat exchange section 134 has a partition plate 134a and a partition plate 134b. The partition plate 134a and the partition plate 134b are alternately laminated with an appropriate adhesive. The heat exchange section 134 as a whole is formed in a substantially rectangular prism shape.

[0060] The partition plate 134a has heat transfer and moisture permeability and is formed in a flat plate shape. The partition wall plate 134b is formed in a corrugated plate shape with a continuous, almost triangular cross-section. The partition wall plate 134b forms an air passage between two adjacent partition plates 134a. The partition wall plates 134b are stacked with each plate at a 90-degree angle in the stacking direction (up and down direction in Figure 4) between the partition plates 134a and the partition wall plate 134b. As a result, on either side of a single partition plate 134a, an air supply side passage 134d for passing a first airflow A1 and an exhaust side passage 134c for passing a second airflow A2 are formed perpendicular to each other. Sensible heat and latent heat exchange (total heat exchange) takes place between the air flowing through the exhaust side passage 134c and the air flowing through the air supply side passage 134d via the partition plate 134a, which has heat transfer and moisture permeability. In the air conditioning system 100, the first heat recovery unit 130 recovers heat from the refrigerant flowing through the first auxiliary refrigerant circuit RC21, and the heat exchange unit 134 further recovers heat between the air flowing through the casing 150 (between the return air RA and the outside air OA), thereby further improving the operating efficiency of the air conditioner 101.

[0061] Figure 5 is a schematic cross-sectional diagram along line XX in Figure 3. Figure 6 is a schematic cross-sectional diagram along line YY in Figure 3. As shown in Figures 3, 5, and 6, the first heat recovery unit 130 has a casing 150. The inside of the casing 150 is divided into two regions, the indoor space S1 side and the outdoor space S2 side, by a heat exchange section 134. As shown in Figure 5, an upstream air supply passage 151a is formed inside the casing 150 upstream of the first airflow A1 from the heat exchange section 134, and a downstream air supply passage 151b is formed downstream of the first airflow A1 from the heat exchange section 134. The upstream air supply passage 151a and the downstream air supply passage 151b constitute an air supply passage 151 that connects the indoor space S1 and the outdoor space S2 via the heat exchange section 134.

[0062] As shown in Figure 6, within the casing 150, an upstream exhaust passage 152a is formed upstream of the second airflow A2 beyond the heat exchange section 134, and a downstream exhaust passage 152b is formed downstream of the second airflow A2 beyond the heat exchange section 134. The upstream exhaust passage 152a and the downstream exhaust passage 152b constitute an exhaust passage 152 that connects the indoor space S1 and the outdoor space S2 via the heat exchange section 134.

[0063] As shown in Figures 5 and 6, a partition wall 153 is provided between the downstream air supply passage 151b and the upstream exhaust passage 152a. A partition wall 154 is provided between the upstream air supply passage 151a and the downstream exhaust passage 152b.

[0064] As shown in Figure 5, in the downstream air supply passage 151b, an air supply fan 137 and an air supply auxiliary heat exchanger 131 are located near the air supply outlet 156. When the air supply fan 137 is operated, a first airflow A1 is generated, and outside air OA from the outdoor space S2 passes through the air supply passage 151, undergoes heat exchange with the air supply auxiliary heat exchanger 131, and is supplied to the indoor space S1 as air supply SA. As shown in Figures 2 and 3, the air supply auxiliary heat exchanger 131 exchanges heat (recovers heat) between the refrigerant flowing through the first auxiliary refrigerant circuit RC21 and the air (outside air OA) passing through the air supply passage 151.

[0065] As shown in Figure 6, in the downstream exhaust passage 152b, an exhaust fan 138 and an exhaust-side auxiliary heat exchanger 132 are located near the exhaust outlet 155. When the exhaust fan 138 is operated, a second airflow A2 is generated, and the return air RA from the indoor space S1 passes through the exhaust passage 152, undergoes heat exchange with the exhaust-side auxiliary heat exchanger 132, and is discharged to the outdoor space S2 as exhaust EA. As shown in Figures 2 and 3, the exhaust-side auxiliary heat exchanger 132 performs heat exchange (heat recovery) between the refrigerant flowing through the second auxiliary refrigerant circuit RC22 and the air (exhaust EA) passing through the exhaust passage 152.

[0066] As described above, the first heat recovery unit 130 includes a casing 150 that houses the first auxiliary refrigerant circuit RC21, the second auxiliary refrigerant circuit RC22, the supply fan 137, and the exhaust fan 138, and has a supply passage 151 through which air passing through the supply-side auxiliary heat exchanger 131 passes, and an exhaust passage 152 through which air passing through the exhaust-side auxiliary heat exchanger 132 passes, and a heat exchange section 134 that performs heat exchange between the air in the supply passage 151 before it passes through the supply-side auxiliary heat exchanger 131 and the air in the exhaust passage 152 before it passes through the exhaust-side auxiliary heat exchanger 132. In the air conditioning system 100, by housing the outside air processing section 130A and exhaust processing section 130B and the heat exchange section 134 of the first heat recovery unit 130 in a single casing 150, the piping configuration around the outside air processing section 130A and exhaust processing section 130B can be simplified. This facilitates the connection work between the heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC21 and the second auxiliary refrigerant circuit RC22. In this embodiment, a first heat recovery unit 130 having an outside air processing unit 130A and an exhaust processing unit 130B is illustrated, but the heat recovery unit of this disclosure may have only an outside air processing unit 130A. In this embodiment, a first heat recovery unit 130 in which the outside air processing unit 130A and the exhaust processing unit 130B are housed in a single casing 150 is illustrated, but the heat recovery unit of this disclosure may have the outside air processing unit and the exhaust processing unit separated and be installed in different locations.

[0067] [About the control unit] Figure 7 is a control block diagram of the air conditioning system 100. As shown in Figure 7, the air conditioning system 100 includes a control unit 115. The control unit 115 is a device that controls the operation of the air conditioner 101 and the refrigerant flow path switching device 140, and is composed of a microcomputer equipped with a processor such as a CPU, and memory such as RAM and ROM. The control unit 115 may also be implemented as hardware using an LSI, ASIC, FPGA, etc. The control unit 115 performs predetermined functions by having the processor execute a program installed in memory. The control unit 115 may be provided as part of the air conditioner 101 and integrated with the air conditioner 101, or it may be provided as a separate device separate from the air conditioner 101.

[0068] In this embodiment, the control unit 115 is located in the outdoor unit 110. The control unit 115 is connected to the compressor 25, first flow path switching valve 26, second flow path switching valve 27, third flow path switching valve 28, outdoor fan 33, first outdoor expansion valve 34, second outdoor expansion valve 35, and temperature sensor 116, all of which are built into the outdoor unit 110. The control unit 115 is connected to the indoor expansion valve 51 and indoor fan 53 via the indoor control unit 54 of the indoor unit 120. The control unit 115 is also connected to the first and second electric valves 136a, 136b, supply fan 137, and exhaust fan 138 of the first heat recovery unit 130. The control unit 115 may also be connected to the auxiliary heat exchanger switching valve 133, electric valve 136, supply fan 137, and exhaust fan 138 via the control unit (not shown) of the first heat recovery unit 130. The control unit 115 is connected to the first valve EV1, the second valve EV2, and the third valve EV3 via the control unit (not shown) of the refrigerant flow path switching device 140 (switching unit 70). The control unit 115 is also connected to the first to fourth shut-off valves 161 to 164, the first switching valve 165, and the second switching valve 166. The control unit 115 is also connected to the temperature sensor 116 and the refrigerant sensor 180. The control unit 115 controls the operation of each of the connected parts according to the operating status of the air conditioning system 100.

[0069] [About shut-off valves] As shown in Figures 1 and 2, the air conditioning system 100 has four shut-off valves 161 to 164. Each of the first to fourth shut-off valves 161 to 164 is an electrically operated valve, with the first shut-off valve 161 located in the first branch pipe 14, the second shut-off valve 162 located in the second branch pipe 15, the third shut-off valve 163 located in the third branch pipe 16, and the fourth shut-off valve 164 located in the fourth branch pipe 17.

[0070] In the air conditioning system 100, a refrigerant sensor 180 (see Figure 7) is positioned to detect refrigerant leaking from the first heat recovery unit 130. When the refrigerant sensor 180 detects refrigerant, the control unit 115 activates all shut-off valves 161 to 164. In the air conditioning system 100, when all shut-off valves 161 to 164 are activated, the auxiliary refrigerant circuit RC2 of the first heat recovery unit 130 (first auxiliary refrigerant circuit RC21 and second auxiliary refrigerant circuit RC22) is completely disconnected from the other refrigerant circuits RC1, RC3, and RC4. Therefore, even if a flammable refrigerant (R32 in this embodiment) leaks from the first heat recovery unit 130, the air conditioning system 100 can prevent the amount of refrigerant leaking from the first heat recovery unit 130 from exceeding the amount of refrigerant stored in the auxiliary refrigerant circuit RC2 at that time. The refrigerant sensor 180 may also be provided in the supply air passage 151 and the exhaust air passage 152. In this configuration, if the refrigerant sensor 180 in the air supply passage 151 detects refrigerant, only the shut-off valves 161 and 162 on the air supply passage 151 side may be shut off, and if the refrigerant sensor 180 in the exhaust passage 152 detects refrigerant, only the shut-off valves 163 and 164 on the exhaust passage 152 side may be shut off.

[0071] [Operation of the air conditioning system] The following will explain, with reference to Figure 2, the cases in which the air conditioning system 100 performs cooling on all operating indoor units 120 (hereinafter also referred to as "full cooling operation"), heating on all operating indoor units 120 (hereinafter also referred to as "full heating operation"), cooling on some of the operating indoor units 120 and heating on others (hereinafter also referred to as "mixed cooling and heating operation"), and cooling with outside air using the first heat recovery unit 130 (hereinafter also referred to as "outside air cooling operation").

[0072] (Full air conditioning operation) In full cooling operation, the control unit 115 adjusts each valve as follows: The first valve EV1 of the switching unit 70 is fully closed, the second valve EV2 is fully open, the third valve EV3 is adjusted to its opening degree, the indoor expansion valve 51 is adjusted to its opening degree, and the first and second outdoor expansion valves 34 and 35 are fully open. Each shut-off valve 161 to 164 is fully open, and the first electric valve 136a and the second electric valve 136b are adjusted to their opening degrees. The first flow path switching valve 26 of the outdoor unit 110 is switched to connect the discharge pipe 25a of the compressor 25 to the gas side end of the second heat exchange section 32. The second flow path switching valve 27 is switched to connect the discharge pipe 25a to the second connecting pipe 12. The third flow path switching valve 28 is switched to connect the discharge pipe 25a to the gas side end of the first heat exchange section 31. In the air conditioning system 100 of this disclosure, a high-pressure gaseous refrigerant may flow through the second connecting pipe 12 at all times, so the second flow path switching valve 27 may be omitted. If the second flow path switching valve 27 is provided, the second flow path switching valve 27 can be switched when the first valve EV1 connected to the second connecting pipe 12 is at its minimum opening and there is no need to flow a high-pressure gaseous refrigerant through the second connecting pipe 12, thereby preventing refrigerant from accumulating between the first valve EV1 and the second flow path switching valve 27.

[0073] In the indoor unit 120 while it is stopped, the control unit 115 controls whether it is performing full cooling operation, full heating operation, or mixed cooling and heating operation. In this case, the indoor expansion valve 51 is fully closed, the first valve EV1 corresponding to this indoor unit 120 is set to its minimum opening, and the second valve EV2 and third valve EV3 are fully closed.

[0074] When the compressor 25 is driven, the high-pressure gaseous refrigerant compressed by the compressor 25 flows into the outdoor heat exchanger 30 via the discharge pipe 25a, the first flow path switching valve 26, the third flow path switching valve 28, etc., and condenses. The refrigerant condensed in the outdoor heat exchanger 30 flows into the first connecting pipe 11 via the first and second outdoor expansion valves 34, 35, the liquid side shut-off valve 21, etc.

[0075] The refrigerant flowing into the first connecting pipe 11 flows through the first header pipe 55 of the refrigerant flow path switching device 140 and flows into the fourth refrigerant pipe P4 of each switching unit 70. The refrigerant flowing into the fourth refrigerant pipe P4 flows into the first heat transfer tube 59a of the subcooled heat exchanger 59 and further flows into the indoor unit 120 via the utilization side liquid piping 62.

[0076] The refrigerant flowing into the fourth refrigerant pipe P4 also branches off into the fifth refrigerant pipe P5, where it is depressurized according to the opening degree of the third valve EV3 and flows into the second heat transfer tube 59b of the subcooled heat exchanger 59. In this subcooled heat exchanger 59, heat is exchanged between the refrigerant flowing through the first heat transfer tube 59a and the refrigerant flowing through the second heat transfer tube 59b, and the refrigerant flowing through the first heat transfer tube 59a is subcooled before flowing into the indoor unit 120.

[0077] The refrigerant flowing through the second heat transfer tube 59b of the subcooled heat exchanger 59 flows from the seventh refrigerant tube P7 into the fourth header tube 58, and then through the connecting tube 63 into the third header tube 57. The refrigerant that flows into the indoor unit 120 is depressurized by the indoor expansion valve 51 and then evaporates in the indoor heat exchanger 52.

[0078] In the indoor unit 120, the refrigerant evaporated in the indoor heat exchanger 52 flows from the gas pipe GP into the user-side gas piping 61, mainly passing through the second valve EV2 and into the third header pipe 57. The refrigerant that flows into the third header pipe 57 flows through the third connecting pipe 13 and the gas-side second shut-off valve 23 into the accumulator 24 and is drawn into the compressor 25.

[0079] (Regarding processing by the first heat recovery unit during full cooling operation) Referring to Figure 2, the processing performed by the first heat recovery unit 130 during full cooling operation will be explained. When the air conditioning system 100 is in cooling operation, the first switching valve 165 is opened and the second switching valve 166 is closed. As a result, liquid refrigerant is supplied to the supply air side auxiliary heat exchanger 131 from the first connecting pipe 11 and the first branch pipe 14, and this liquid refrigerant flows into the supply air side auxiliary heat exchanger 131. The liquid refrigerant exchanges heat with the air (outside air OA) in the supply air side auxiliary heat exchanger 131 and evaporates to become a low-pressure gaseous refrigerant. This gaseous refrigerant flows from the second branch pipe 15 to the third connecting pipe 13. In this way, the first heat recovery unit 130 cools the outside air OA and supplies supply air SA to the first space S11 during cooling operation.

[0080] When the air conditioning system 100 is in cooling operation, the third switching valve 167 is closed and the fourth switching valve 168 is opened. As a result, high-pressure gaseous refrigerant is supplied to the exhaust-side auxiliary heat exchanger 132 of the first heat recovery unit 130 from the second connecting pipe 12, the sixth branch pipe 19, and the fourth branch pipe 17, and this gaseous refrigerant flows into the exhaust-side auxiliary heat exchanger 132. The gaseous refrigerant exchanges heat with air (exhaust EA) in the exhaust-side auxiliary heat exchanger 132 and condenses into liquid refrigerant. This liquid refrigerant flows from the third branch pipe 16 to the first connecting pipe 11. In this way, the first heat recovery unit 130 recovers heat from the return air RA while releasing exhaust EA into the outdoor space S2 during cooling operation. Note that the high-pressure gaseous refrigerant flowing to the second connecting pipe 12 via the second flow path switching valve 27 does not flow to the indoor unit 120 because the first valve EV1 is fully closed.

[0081] (Regarding full heating operation) During full heating operation, the control unit 115 adjusts each valve as follows: The first valve EV1 of the switching unit 70 is fully open, the second valve EV2 is fully closed, the third valve EV3 is fully closed, the indoor expansion valve 51 is fully open, and the opening degrees of the first and second outdoor expansion valves 34 and 35 are adjusted. Each shut-off valve 161 to 164 is fully open, and the opening degrees of the first motorized valve 136a and the second motorized valve 136b are adjusted. The first flow path switching valve 26 of the outdoor unit 110 is switched to connect the refrigerant piping 25c to the gas side end of the second heat exchange section 32. The second flow path switching valve 27 is switched to connect the discharge piping 25a to the second connecting pipe 12. The third flow path switching valve 28 is switched to connect the refrigerant piping 25c to the gas side end of the first heat exchange section 31.

[0082] When the compressor 25 is driven, the high-pressure gaseous refrigerant compressed by the compressor 25 flows into the second connecting pipe 12 via the discharge pipe 25a and the second flow path switching valve 27, etc. The refrigerant that flows into the second connecting pipe 12 passes through the second header pipe 56 of the refrigerant flow path switching device 140, the first refrigerant pipe P1 of the switching unit 70, and the first valve EV1, and flows into the gas pipe GP of the indoor unit 120 from the user-side gas pipe 61.

[0083] The refrigerant flowing into the gas pipe GP flows into the indoor heat exchanger 52 of the indoor unit 120 and condenses. The condensed refrigerant passes through the indoor expansion valve 51 and flows into the liquid pipe LP, and into the utilization-side liquid pipe 62 of the switching unit 70. The refrigerant flowing into the utilization-side liquid pipe 62 flows through the subcooling heat exchanger 59 and the fourth refrigerant pipe P4, and then into the first header pipe 55.

[0084] The refrigerant flowing into the first header pipe 55 flows through the first connecting pipe 11 and into the outdoor unit 110, where it is depressurized in the first and second outdoor expansion valves 34 and 35. The depressurized refrigerant evaporates as it passes through the outdoor heat exchanger 30, and flows into the accumulator 24 via the first flow path switching valve 26 and the third flow path switching valve 28, etc., and is drawn into the compressor 25.

[0085] (Regarding processing by the first heat recovery unit during full heating operation) Referring to Figure 2, the processing performed by the first heat recovery unit 130 during full heating operation will be explained. When the air conditioning system 100 is in heating operation, the first switching valve 165 is closed, the second switching valve 166 is opened, the third switching valve 167 is opened, and the fourth switching valve 168 is closed. As a result, high-pressure gaseous refrigerant is supplied to the supply air-side auxiliary heat exchanger 131 from the second connecting pipe 12, the fifth branch pipe 18, and the second branch pipe 15, and this gaseous refrigerant flows into the supply air-side auxiliary heat exchanger 131. The gaseous refrigerant exchanges heat with air (outside air OA) in the supply air-side auxiliary heat exchanger 131 and condenses to become liquid refrigerant. This liquid refrigerant flows from the first branch pipe 14 to the first connecting pipe 11. In this way, the first heat recovery unit 130 heats the outside air OA and supplies supply air SA to the first space S11 during heating operation.

[0086] Liquid refrigerant is supplied to the exhaust-side auxiliary heat exchanger 132 of the first heat recovery unit 130 from the first connecting pipe 11 and the third branch pipe 16, and this liquid refrigerant flows into the exhaust-side auxiliary heat exchanger 132. In the exhaust-side auxiliary heat exchanger 132, the liquid refrigerant exchanges heat with air (exhaust EA) and evaporates to become gaseous refrigerant. This gaseous refrigerant flows from the fourth branch pipe 17 to the third connecting pipe 13. In this way, during heating operation, the first heat recovery unit 130 recovers heat from the return air RA while releasing exhaust EA into the outdoor space S2.

[0087] (Regarding mixed heating and cooling operation) In mixed cooling and heating operation, the control unit 115 adjusts each valve as follows: In the switching unit 70 (hereinafter also referred to as the "cooling-side switching unit 70") corresponding to the indoor unit 120 performing cooling operation (hereinafter also referred to as the "cooling-side indoor unit 120") among the operating indoor units 120, the first valve EV1 is set to the minimum opening, the second valve EV2 is set to fully open, the third valve EV3 is adjusted to its opening degree, and the indoor expansion valve 51 of the cooling-side indoor unit 120 is adjusted to its opening degree. Each shut-off valve 161 to 164 is set to fully open, and the first electric valve 136a and the second electric valve 136b are adjusted to their opening degrees. The first flow path switching valve 26 of the outdoor unit 110 is switched to connect the refrigerant piping 25c to the gas-side end of the second heat exchange section 32. The second flow path switching valve 27 is switched to connect the discharge piping 25a to the second connecting pipe 12. The third flow path switching valve 28 is switched to connect the discharge pipe 25a to the gas side end of the first heat exchange section 31.

[0088] In the switching unit 70 (hereinafter also referred to as the "heating-side switching unit 70") corresponding to the indoor unit 120 performing heating operation among the operating indoor units 120 (hereinafter also referred to as the "heating-side indoor unit 120"), the first valve EV1 is fully open, the second valve EV2 is fully closed, the third valve EV3 is fully closed, the indoor expansion valve 51 of the heating-side indoor unit 120 is fully open, and the opening degree of the first outdoor expansion valve 34 and the second outdoor expansion valve 35 is adjusted. In this embodiment, the indoor unit 120 in the first space S11 (cooling-side indoor unit 120) is in cooling operation, and the indoor unit 120 in the second space S12 (heating-side indoor unit 120) is in heating operation. In this case, in the first heat recovery unit 130 provided for the first space S11, the supply air side auxiliary heat exchanger 131 functions as an evaporator in accordance with the cooling side indoor unit 120 of the first space S11, and the exhaust side auxiliary heat exchanger 132 functions as a condenser.

[0089] When the compressor 25 is driven, a portion of the high-pressure gaseous refrigerant compressed by the compressor 25 flows into the second connecting pipe 12 via the discharge pipe 25a and the second flow path switching valve 27. The remaining portion of the high-pressure gaseous refrigerant compressed by the compressor 25 condenses in the first heat exchange section 31 of the outdoor heat exchanger 30 via the discharge pipe 25a and the third flow path switching valve 28, and a portion flows into the first connecting pipe 11 via the first outdoor expansion valve 34, while the remainder flows into the second outdoor expansion valve 35. The refrigerant condensed in the first heat exchange section 31 evaporates in the second heat exchange section 32 via the second outdoor expansion valve 35, and is drawn into the compressor 25 via the first flow path switching valve 26. In mixed heating and cooling operation, the use of the second heat exchange section 32 is changed according to the balance between the amount of refrigerant condensed and evaporated in the indoor unit 120 and the first heat recovery unit 130. In mixed heating and cooling operation, both the first heat exchange section 31 and the second heat exchange section 32 may function as either a condenser or an evaporator, depending on the balance between the condensation and evaporation rates of the refrigerant in the indoor unit 120 and the first heat recovery unit 130.

[0090] The refrigerant that flows into the second connecting pipe 12 flows into the second header pipe 56 of the refrigerant flow path switching device 140, flows through the first refrigerant pipe P1, the first valve EV1, and the user-side gas piping 61 of the heating-side switching unit 70, and flows into the gas pipe GP.

[0091] The refrigerant flowing into the gas pipe GP condenses in the indoor heat exchanger 52 of the heating-side indoor unit 120. The condensed refrigerant flows from the liquid pipe LP into the utilization-side liquid pipe 62 of the heating-side switching unit 70, through the subcooled heat exchanger 59 and the fourth refrigerant pipe P4, and into the first header pipe 55.

[0092] The refrigerant that flows from the outdoor unit 110 into the first connecting pipe 11 also flows into the first header pipe 55. The refrigerant that flows into the first header pipe 55 flows into the cooling-side indoor unit 120 via the fourth refrigerant pipe P4 of the cooling-side switching unit 70, the subcooling heat exchanger 59, the utilization-side liquid piping 62, and the liquid pipe LP. At this time, the refrigerant that has passed through the subcooling heat exchanger 59 branches off from the fourth refrigerant pipe P4 and flows through the fifth refrigerant pipe P5, where it is subcooled by the refrigerant that has been depressurized by the third valve EV3.

[0093] The refrigerant that flows into the cooling-side indoor unit 120 is depressurized in the indoor expansion valve 51, evaporates in the indoor heat exchanger 52, and cools the room. The evaporated refrigerant flows through the gas pipe GP and into the user-side gas piping 61 of the cooling-side switching unit 70, flows through the second valve EV2 and into the third refrigerant pipe P3 and the third header pipe 57, flows through the third connecting pipe 13 and into the accumulator 24, and is drawn into the compressor 25.

[0094] The first heat recovery unit 130 has an air supply side auxiliary heat exchanger 131 that functions as an evaporator in conjunction with the cooling side indoor unit 120 of the first space S11, cooling the outside air OA and supplying the air supply SA to the first space S11. The first heat recovery unit 130 also has an exhaust side auxiliary heat exchanger 132 that functions as a condenser, recovering heat from the return air RA to evaporate the gaseous refrigerant, and releasing the heated return air RA as exhaust EA into the outdoor space S2.

[0095] (Regarding outside air cooling operation) In the air conditioning system 100, a temperature sensor 116 (see Figure 7) is provided on the outdoor unit 110. The temperature sensor 116 measures the temperature of the air in the outdoor space S2 (outside air temperature T). The temperature sensor 116 may be installed in the outdoor space S2 other than the outdoor unit 110. The control unit 115 determines that outside air cooling operation can be performed for the indoor space S1 when the outside air temperature T falls below a predetermined set temperature TS. The set temperature TS is stored in the control unit 115 in advance. The set temperature TS can be changed by operating the control unit 115.

[0096] Here, we will explain the case where the indoor unit 120 continues cooling in the second space S12, and the first heat recovery unit 130 is operating in outside air cooling mode in the first space S11, with reference to Figure 2. In the air conditioning system 100, when the control unit 115 determines that outside air cooling mode can be performed, it switches the operation of each part as follows.

[0097] Specifically, in the air conditioning system 100, if the outside air temperature T falls below the set temperature TS while the first space S11 is being cooled, the control unit 115 stops the indoor unit 120 and continues ventilation by the first heat recovery unit 130. Furthermore, the control unit 115 closes the first shut-off valve 161 and the second shut-off valve 162 and operates the supply air fan 137. As a result, the air conditioning mode of the first space S11 is switched from normal cooling operation to outside air cooling operation.

[0098] In the air conditioning system 100, the refrigerant passing through the supply-side auxiliary heat exchanger 131 is shut off during outside air cooling operation. Therefore, in the air conditioning system 100, during outside air cooling operation, only the supply air fan 137 can be operated without heat exchange by the supply-side auxiliary heat exchanger 131, thereby enabling efficient operation of the air conditioning system 100. In this embodiment, an example is given in which the air conditioning system 100 automatically performs outside air cooling operation based on the measured value of the outside air temperature T, but the air conditioning system of this disclosure may also be configured to switch to outside air cooling operation manually based on the user's instruction.

[0099] Furthermore, in the air conditioning system 100, during outside air cooling operation, the control unit 115 maintains the third shut-off valve 163 and the fourth shut-off valve 164 in the "open" position to continue supplying refrigerant to the exhaust-side auxiliary heat exchanger 132.

[0100] High-pressure gaseous refrigerant is supplied to the exhaust-side auxiliary heat exchanger 132 of the first heat recovery unit 130 from the second connecting pipe 12 and the fourth branch pipe 17, and this gaseous refrigerant flows into the exhaust-side auxiliary heat exchanger 132. In the exhaust-side auxiliary heat exchanger 132, the gaseous refrigerant exchanges heat with air (exhaust EA) and condenses into liquid refrigerant. This liquid refrigerant flows from the third branch pipe 16 into the first connecting pipe 11. In this way, the first heat recovery unit 130 can continue to recover heat from the return air RA during outside air cooling operation.

[0101] In the air conditioning system 100, outside air cooling operation is performed for the first space S11, and heat can also be recovered from the exhaust EA of the first space S11 by the exhaust-side auxiliary heat exchanger 132. This allows the air conditioning system 100 to be operated even more efficiently. In order to suppress the amount of refrigerant leaking from the first heat recovery unit 130, it is preferable to provide a fourth shut-off valve 164, but the fourth shut-off valve 164 may be omitted in order to realize heat recovery by the exhaust processing unit 130B during outside air cooling. In this embodiment, an air conditioning system 100 using R32, which is slightly flammable, as the refrigerant is exemplified, but the air conditioning system of this disclosure may use a refrigerant that is not flammable.

[0102] The air conditioning system 100 further includes an indoor unit 120 located in a second space S12, which is different from the first space S11. The refrigerant circuit RC4 on the user side of the indoor unit 120 that air-conditions the second space S12 is individually connected to the refrigerant circuit RC1 on the heat source side by a first connecting pipe 11 and a third connecting pipe 13. Therefore, in the air conditioning system 100, during cooling, the first space S11 can be cooled using outside air by the first heat recovery unit 130, while the cooling operation of the indoor unit 120 for the second space S12 can continue.

[0103] [Air conditioning system according to the second embodiment] Figure 8 is a schematic diagram showing the overall configuration of an air conditioning system according to the second embodiment of this disclosure. Figure 9 is a refrigerant circuit diagram of the air conditioning system according to the second embodiment. Figure 10 is a diagram showing the schematic configuration of a heat recovery unit according to the second embodiment. As shown in Figure 8, the air conditioning system 200, which is the second embodiment of this disclosure, comprises an air conditioner 102 and a refrigerant flow path switching device 140. The air conditioning system 200 differs from the air conditioning system 100 according to the first embodiment in that it comprises an air conditioner 102 instead of an air conditioner 101. Note that in Figures 8 to 11, the same reference numerals are used for the same components as those described in Figures 1 to 7, and in the following description, the description of such components will be omitted unless specifically mentioned.

[0104] [Configuration of air conditioner 102] As shown in Figures 8 and 9, the air conditioner 102 has an outdoor unit 110, an indoor unit 120, and a second heat recovery unit 170. In the air conditioner 102, two or more indoor units 120 and one second heat recovery unit 170 are connected to one outdoor unit 110. The air conditioner 102 can freely select cooling operation and heating operation for each indoor unit 120 using a refrigerant flow path switching device 140 to provide air conditioning for the target space. The air conditioner 102 differs from the air conditioner 101 according to the first embodiment in that it has a second heat recovery unit 170 instead of a first heat recovery unit 130.

[0105] [Configuration of the second heat recovery unit] The second heat recovery unit 170 is a device capable of ventilating the indoor space S1 and is located outside the indoor space S1 within the building B. The second heat recovery unit 170 is located in the space above the ceiling of the indoor space S1 and is connected to the indoor space S1 and the outdoor space S2 through a duct. In this embodiment, the case in which the second heat recovery unit 170 is located in the space above the ceiling of the indoor space S1 is illustrated, but the second heat recovery unit of this disclosure may be a ceiling-suspended type, a ceiling-embedded type, a floor-standing type, or a wall-mounted type, and may be located in a place other than above the ceiling. As shown in Figure 10, the second heat recovery unit 170 includes an air supply side auxiliary heat exchanger 131, an exhaust side auxiliary heat exchanger 132, an auxiliary heat exchanger switching valve 133, and a heat exchange section 134. The second heat recovery unit 170 includes an outside air processing section 170A and an exhaust processing section 170B. The outside air processing unit 170A has an air supply side auxiliary heat exchanger 131, and the exhaust processing unit 170B has an exhaust side auxiliary heat exchanger 132. A third auxiliary refrigerant circuit RC5 is provided inside the second heat recovery unit 170. The third auxiliary refrigerant circuit RC5 is configured by connecting the air supply side auxiliary heat exchanger 131, the exhaust side auxiliary heat exchanger 132, and the auxiliary heat exchanger switching valve 133 by auxiliary refrigerant piping 135. The auxiliary refrigerant piping 135 includes a first auxiliary refrigerant pipe 135a, a second auxiliary refrigerant pipe 135b, a third auxiliary refrigerant pipe 135c, a fourth auxiliary refrigerant pipe 135d, and a fifth auxiliary refrigerant pipe 135e.

[0106] One end of the supply-side auxiliary heat exchanger 131 is connected to a third auxiliary refrigerant pipe 135c extending from the auxiliary heat exchanger switching valve 133. The other end of the supply-side auxiliary heat exchanger 131 is connected to one end of the second auxiliary refrigerant pipe 135b. The other end of the second auxiliary refrigerant pipe 135b is connected to one end of the exhaust-side auxiliary heat exchanger 132. An electric valve 139 is provided in the middle of the second auxiliary refrigerant pipe 135b. The electric valve 139 is an electric valve whose opening degree can be adjusted. The other end of the exhaust-side auxiliary heat exchanger 132 is connected to a first auxiliary refrigerant pipe 135a extending from the auxiliary heat exchanger switching valve 133.

[0107] The auxiliary heat exchanger switching valve 133 is a four-way switching valve having four ports, to which the first auxiliary refrigerant pipe 135a, the second auxiliary refrigerant pipe 135b, the fourth auxiliary refrigerant pipe 135d, and the fifth auxiliary refrigerant pipe 135e are connected.

[0108] As shown in Figures 9 and 10, the fourth auxiliary refrigerant pipe 135d is connected to the seventh branch pipe 191, and the fifth auxiliary refrigerant pipe 135e is connected to the eighth branch pipe 192. The auxiliary heat exchanger switching valve 133 switches the flow of refrigerant between the first auxiliary refrigerant pipe 135a, the second auxiliary refrigerant pipe 135b, the fourth auxiliary refrigerant pipe 135d, and the fifth auxiliary refrigerant pipe 135e.

[0109] The third auxiliary refrigerant circuit RC5 is connected to the second connecting pipe 12 on the high-pressure gas side via the seventh branch pipe 191, and also connected to the third connecting pipe 13 on the low-pressure gas side via the eighth branch pipe 192.

[0110] (Configuration of the control unit) Figure 11 is a control block diagram of the air conditioning system 200. As shown in Figure 11, in the air conditioning system 200, the control unit 115 is connected to the compressor 25, first flow path switching valve 26, second flow path switching valve 27, third flow path switching valve 28, outdoor fan 33, first outdoor expansion valve 34, and second outdoor expansion valve 35, all built into the outdoor unit 110. The control unit 115 is connected to the indoor expansion valve 51 and indoor fan 53 via the indoor control unit 54 of the indoor unit 120. The control unit 115 is connected to the auxiliary heat exchanger switching valve 133, electric valve 139, supply fan 137, and exhaust fan 138 of the second heat recovery unit 170. The control unit 115 is connected to the first valve EV1, second valve EV2, and third valve EV3 via a control unit (not shown) of the refrigerant flow path switching device 140 (switching unit 70). The control unit 115 is connected to the fifth shut-off valve 193 and the sixth shut-off valve 194. The control unit 115 is also connected to the temperature sensor 116 and the refrigerant sensor 180. The control unit 115 controls the operation of each of the connected parts according to the operating status of the air conditioning system 200. In addition, the air conditioning system 200 may have a control unit (not shown) in the second heat recovery unit 170, and the control unit 115 may be connected to the auxiliary heat exchanger switching valve 133, the electric valve 139, the supply fan 137, and the exhaust fan 138 via the control unit (not shown) of the second heat recovery unit 170.

[0111] (Regarding outside air cooling operation) In the air conditioning system 200, when performing outside air cooling operation, the indoor unit 120 is stopped while ventilation by the second heat recovery unit 170 continues. Specifically, in the air conditioning system 200, when the first space S11 is being cooled by the indoor unit 120, if the outside air temperature T detected by the temperature sensor 116 becomes lower than the set temperature TS, the control unit 115 closes the fifth shut-off valve 193 and the sixth shut-off valve 194 and operates the supply air fan 137. This allows the air conditioning system 200 to switch the air conditioning of the first space S11 from normal cooling operation to outside air cooling operation.

[0112] As explained above, the air conditioning system 200 shuts off the refrigerant passing through the supply-side auxiliary heat exchanger 131 during outside air cooling operation. Therefore, during outside air cooling operation, the air conditioning system 200 can operate only the supply fan 137 without heat exchange by the supply-side auxiliary heat exchanger 131, thereby enabling efficient operation of the air conditioning system 200.

[0113] The air conditioning system 200 further includes an indoor unit 120 located in a second space S12, which is different from the first space S11. The refrigerant circuit RC4 on the user side of the indoor unit 120 that air-conditions the second space S12 is individually connected to the refrigerant circuit RC1 on the heat source side by a first connecting pipe 11 and a third connecting pipe 13. Therefore, in the air conditioning system 200, during cooling, the first space S11 can be cooled using outside air by the second heat recovery unit 170, while the cooling operation of the indoor unit 120 for the second space S12 can continue.

[0114] (Regarding the accumulation of refrigerant in the second heat recovery unit) Referring to Figure 9, the state of the second heat recovery unit 170 when the air conditioning system 200 is stopped but the fans 137 and 138 of the second heat recovery unit 170 are operating will be described. When cooling operation is performed and there is no need to operate the indoor unit 120 for the second space S12, and outside air cooling operation is performed by the second heat recovery unit 170 for the first space S11, the indoor units 120 for each space S11 and S12 are stopped, but the fans 137 and 138 of the second heat recovery unit 170 are operating. In this case, the accumulation of refrigerant in the second heat recovery unit 170 can be prevented by closing the fifth shut-off valve 193 and the sixth shut-off valve 194.

[0115] (Regarding the operation of the shut-off valve in the event of a refrigerant leak) In the air conditioning system 200, a refrigerant sensor 180 (see Figure 11) is positioned to detect refrigerant leaking from the second heat recovery unit 170. When the refrigerant sensor 180 detects refrigerant, the control unit 115 activates the fifth shut-off valve 193 and the sixth shut-off valve 194. In the air conditioning system 200, when the fifth shut-off valve 193 and the sixth shut-off valve 194 are activated, the third auxiliary refrigerant circuit RC5 of the second heat recovery unit 170 is completely disconnected from the other refrigerant circuits RC1, RC3, and RC4 in the air conditioning system 200. Therefore, even if a flammable refrigerant (R32 in this embodiment) leaks from the second heat recovery unit 170, the air conditioning system 200 can prevent the amount of refrigerant leaking from the second heat recovery unit 170 from exceeding the amount of refrigerant stored in the third auxiliary refrigerant circuit RC5 at that time.

[0116] [Other variations] Each of the air conditioning systems 100 and 200 described above is configured using a cooling / heating-free type air conditioner 101 and 102, but the air conditioning systems of this disclosure may use air conditioners other than the cooling / heating-free type, or may be configured using a cooling / heating switching type heat pump air conditioner.

[0117] [Effects of the Embodiment] The air conditioning system 100 in the first embodiment described above includes an outdoor unit 110 having a heat source side refrigerant circuit RC1 including a compressor 25 and an outdoor heat exchanger 30, an indoor unit 120 located in the first space S11 and having a utilization side refrigerant circuit RC4 including an indoor heat exchanger 52, a liquid side first connecting pipe 11 and a gas side third connecting pipe 13 connecting the heat source side refrigerant circuit RC1 and the utilization side refrigerant circuit RC4, and a branch from the first connecting pipe 11. The air conditioning system 100 includes an outside air processing unit 130A which has a first branch pipe 14 and a second branch pipe 15 branched from a third connecting pipe 13, a first auxiliary refrigerant circuit RC21 including an air supply side auxiliary heat exchanger 131 connected to the second branch pipe 15, an air supply fan 137 that supplies outside air OA that has passed through the air supply side auxiliary heat exchanger 131 to the first space S11, a first shut-off valve 161 provided in the first branch pipe 14, and a second shut-off valve 162 provided in the second branch pipe 15. The air conditioning system 100 shuts off the flow of refrigerant between the heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC21 by the operation of the first shut-off valve 161 and the second shut-off valve 162.

[0118] In the configuration described above, the first shut-off valve 161 and the second shut-off valve 162 can completely disconnect the first auxiliary refrigerant circuit RC21 from the heat source side refrigerant circuit RC1. Therefore, when the outside air processing unit 130A is stopped, evaporation, condensation, etc. of the refrigerant in the first auxiliary refrigerant circuit RC21 can be suppressed, thereby suppressing a decrease in the operating efficiency of the air conditioning system 100.

[0119] The air conditioning system 100 in the first embodiment described above includes a temperature sensor 116 for detecting the outside air temperature and a control unit 115 for operating the supply air fan 137 based on the outside air temperature detected by the temperature sensor 116. When the first space S11 is being cooled and the outside air temperature falls below a predetermined set temperature, the control unit 115 of the air conditioning system 100 closes the first shut-off valve 161 and the second shut-off valve 162 and operates the supply air fan 137. With this configuration, if the outside air temperature falls below a predetermined temperature during cooling of the first space S11, the refrigerant passing through the supply air auxiliary heat exchanger 131 is shut off, allowing only the supply air fan 137 to be operated for cooling of the first space S11 using outside air.

[0120] The air conditioning system 100 in the first embodiment described above further comprises an indoor unit 120 located in a second space S12 different from the first space S11, having a user-side refrigerant circuit RC4 including an indoor heat exchanger 52, the user-side refrigerant circuit RC4 being connected to the heat source-side refrigerant circuit RC1 by a first connecting pipe 11 and a third connecting pipe 13. With this configuration, during cooling, in the first space S11 where the supply air fan 137 is installed, outside air cooling operation is performed using only the supply air fans 137 of the outside air processing units 130A and 170A, while in the second space S12, the cooling operation of the indoor unit 120 can be continued.

[0121] The air conditioning system 100 in the first embodiment described above further includes an exhaust processing unit 130B having a third branch pipe 16 branched from the first connecting pipe 11, a second auxiliary refrigerant circuit RC22 including an exhaust-side auxiliary heat exchanger 132 connected to a fourth branch pipe 17 branched from the third connecting pipe 13, and an exhaust fan 138 that discharges the air from the first space S11 that has passed through the exhaust-side auxiliary heat exchanger 132 to the outside, and a third shut-off valve 163 provided in the third branch pipe 16. In the air conditioning system 100, the control unit 115 opens the third shut-off valve 163 and operates the exhaust fan 138 when the outside air temperature falls below a predetermined temperature during cooling of the first space S11. With this configuration, when cooling is performed, if the first space S11 is cooled with outside air and the second space S12 is cooled, the air conditioning system 100 can be operated efficiently by recovering heat from the exhaust of the first space S11 with the exhaust-side auxiliary heat exchanger 132.

[0122] The air conditioning system 100 in the first embodiment described above further comprises a casing 150 that houses a first auxiliary refrigerant circuit RC21, a second auxiliary refrigerant circuit RC22, an air supply fan 137, and an exhaust fan 138, and has an air supply passage 151 through which air passing through the air supply side auxiliary heat exchanger 131 passes, and an exhaust passage 152 through which air passing through the exhaust side auxiliary heat exchanger 132 passes, and a heat exchange unit 134 that performs heat exchange between the air in the air supply passage 151 before it passes through the air supply side auxiliary heat exchanger 131 and the air in the exhaust passage 152 before it passes through the exhaust side auxiliary heat exchanger 132. With this configuration, the outside air processing unit 130A, the exhaust processing unit 130B, and the heat exchange unit 134 are housed in a single casing 150, which simplifies the piping configuration around the first heat recovery unit 130. This makes it easier to connect the heat source side refrigerant circuit RC1 to the first auxiliary refrigerant circuit RC21 and the second auxiliary refrigerant circuit RC22.

[0123] In the first embodiment described above, the air conditioning system 100 uses a flammable refrigerant (refrigerant R32). With this configuration, if refrigerant leaks from the heat recovery unit, the amount of refrigerant leaking from the first heat recovery unit 130 can be suppressed by closing the first to fourth shut-off valves 161 to 164. [Explanation of Symbols]

[0124] 11: First Liaison Tube 13: Third Liaison Tube 14: First branch pipe 15: Second branch piping 16: Third branch pipe 17: Fourth branch pipe 25: Compressor 30: Outdoor heat exchanger (1st heat exchanger) 52: Indoor heat exchanger (second heat exchanger, third heat exchanger) 100: Air conditioning system (first embodiment) 110: Outdoor unit (Unit 1) 115: Control Unit 116: Temperature sensor 120: Indoor units (Unit 2, Unit 3) 130A: Outdoor air processing unit 130B: Exhaust section 131: Supply side auxiliary heat exchanger (1st auxiliary heat exchanger) 132: Exhaust-side auxiliary heat exchanger (second auxiliary heat exchanger) 134:Heat exchange section 137: Intake fan 138: Exhaust fan 150: Casing 151: Air supply passage 152: Exhaust passage 161: First shut-off valve 162: Second shut-off valve 163: Third shut-off valve RC1: Heat source side refrigerant circuit (first refrigerant circuit) RC21: Supply side auxiliary refrigerant circuit (1st auxiliary refrigerant circuit) RC22: Exhaust-side auxiliary refrigerant circuit (second auxiliary refrigerant circuit) RC4: User-side refrigerant circuit (second refrigerant circuit, third refrigerant circuit) S11: 1st space S12:Second space T: Outside temperature TS: Set temperature (predetermined temperature)

Claims

1. A first unit (110) having a first refrigerant circuit (RC1) including a compressor (25) and a first heat exchanger (30), A second unit (120) is located in the first space (S11) and has a second refrigerant circuit (RC4) including a second heat exchanger (52), Liquid-side piping (11) and gas-side piping (13) connecting the first refrigerant circuit (RC1) and the second refrigerant circuit (RC4), An outside air processing unit (130A) having a first auxiliary refrigerant circuit (RC21) including a first auxiliary heat exchanger (131) connected to a first branch pipe (14) branched from the liquid side pipe (11) and a second branch pipe (15) branched from the gas side pipe (13), and an outside air processing unit (130A) having an outside air supply fan (137) that supplies outside air that has passed through the first auxiliary heat exchanger (131) to the first space (S11), The first shut-off valve (161) is provided in the first branch pipe (14), The second shut-off valve (162) is provided in the second branch pipe (15), A temperature sensor (116) that detects the outside air temperature, A control unit (115) operates the air supply fan (137) based on the outside air temperature detected by the temperature sensor (116), Equipped with, The operation of the first shut-off valve (161) and the second shut-off valve (162) interrupts the flow of refrigerant between the first refrigerant circuit (RC1) and the first auxiliary refrigerant circuit (RC21). When the first space (S11) is being cooled and the outside air temperature (T) falls below a predetermined temperature (TS), An air conditioning system (100) in which the control unit (115) closes the first shut-off valve (161) and the second shut-off valve (162) and operates the supply air fan (137).

2. The system further comprises a third unit (120) located in a second space (S12) different from the first space (S11), and having a third refrigerant circuit (RC4) including a third heat exchanger (52), The air conditioning system (100) according to claim 1, wherein the third refrigerant circuit (RC4) is connected to the first refrigerant circuit (RC1) by the liquid-side piping (11) and the gas-side piping (13).

3. An exhaust processing unit (130B) having a second auxiliary refrigerant circuit (RC22) including a second auxiliary heat exchanger (132) connected to a third branch pipe (16) branched from the liquid side pipe (11) and a fourth branch pipe (17) branched from the gas side pipe (13), and an exhaust fan (138) that discharges the air from the first space (S11) that has passed through the second auxiliary heat exchanger (132) to the outside, The system further comprises a third shut-off valve (163) provided in the third branch pipe (16), The control unit (115) The air conditioning system (100) according to claim 1, wherein if the outside air temperature falls below a predetermined temperature while the first space (S11) is being cooled, the third shut-off valve (163) is opened and the exhaust fan (138) is operated.

4. A casing (150) housing the first auxiliary refrigerant circuit (RC21), the second auxiliary refrigerant circuit (RC22), the supply air fan (137), and the exhaust fan (138), having a supply air passage (151) through which air passing through the first auxiliary heat exchanger (131) passes, and an exhaust passage (152) through which air passing through the second auxiliary heat exchanger (132) passes, A heat exchange unit (134) performs heat exchange between the air in the supply passage (151) before it passes through the first auxiliary heat exchanger (131) and the air in the exhaust passage (152) before it passes through the second auxiliary heat exchanger (132), The air conditioning system (100) according to claim 3, further comprising the above.

5. The air conditioning system (100) according to any one of claims 1 to 4, wherein the refrigerant is a flammable refrigerant.

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