Air conditioning system

Abstract

To reduce the number of changeover valves and suppress the number of man-hours required for work for connecting refrigerant piping and the changeover valves in an air conditioning system including a heat recovery auxiliary heat exchanger.SOLUTION: An air conditioning system 100 includes: an outdoor unit 110 having a heat source side refrigerant circuit RC1; a plurality of indoor units 120 each having an indoor heat exchanger 52; switching units 70 each having an intermediate refrigerant circuit RC3; and a first heat recovery unit 130 having a first auxiliary refrigerant circuit RC2 including an air supply side auxiliary heat exchanger 131 and an air exhaust side auxiliary heat exchanger 132. The heat source side refrigerant circuit RC1 and the intermediate refrigerant circuit RC3 are connected by a first communication pipe 11 in which a liquid refrigerant flows, a second communication pipe 12 in which a high-pressure gas refrigerant flows and a third communication pipe 13 in which a low-pressure gas refrigerant flows. The heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC2 are connected by the second communication pipe 12 and the third communication pipe 13 via an auxiliary heat exchanger changeover valve 133.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, there has been known an air conditioning system in which a heat source unit, a plurality of user-side units, an air supply unit having an auxiliary heat exchanger, and an exhaust unit having an auxiliary heat exchanger are connected by piping, and the air conditioning system enables simultaneous use of a user-side unit operating in cooling mode and a user-side unit operating in heating mode (so-called heat pump free system) (see, for example, Patent Document 1). In the air conditioning system described in Patent Document 1, one of the auxiliary heat exchangers is used as an evaporator, and the other auxiliary heat exchanger is used as a condenser, and heat is recovered from the supply air and the exhaust air by each auxiliary heat exchanger.

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, many switching valves are used to control the flow of refrigerant to each auxiliary heat exchanger. For this reason, in the air conditioning system, there are problems that the cost of the switching valves becomes high and the work of connecting the heat source unit and the user-side unit via the switching valves becomes complicated.

[0005] An object of the present disclosure is to reduce the number of switching valves and suppress the man-hours required for connecting the refrigerant piping and the switching valves in an air conditioning system provided with an auxiliary heat exchanger for heat recovery.

Means for Solving the Problems

[0006] (1) The air conditioning system of the present disclosure includes a first unit having a first refrigerant circuit including a compressor and a first heat exchanger, a second unit disposed in a first space and having a second heat exchanger, a third unit having a third heat exchanger, an intermediate unit having an intermediate refrigerant circuit for individually functioning the second heat exchanger and the third heat exchanger as an evaporator or a condenser, a first auxiliary refrigerant circuit including a first auxiliary heat exchanger and a second auxiliary heat exchanger connected in series with the first auxiliary heat exchanger via a refrigerant pipe, a first air supply fan for supplying outside air passing through the first auxiliary heat exchanger to the first space, a first exhaust fan for discharging the air in the first space passing through the second auxiliary heat exchanger to the outside, and a first switching valve for switching the flow of the refrigerant in the first auxiliary refrigerant circuit, and a first heat recovery unit having the same, and is provided with the first refrigerant circuit and the intermediate refrigerant circuit are connected by a first communication pipe through which a liquid refrigerant flows, a second communication pipe through which a high-pressure gas refrigerant flows, and a third communication pipe through which a low-pressure gas refrigerant flows, the first refrigerant circuit and the first auxiliary refrigerant circuit are connected by the second communication pipe and the third communication pipe via the first switching valve.

[0007] In the above configuration, the first unit and the first heat recovery unit can be connected by the second communication pipe and the third communication pipe via the first switching valve. Thereby, for an air conditioning system provided with the first heat recovery unit including the first auxiliary heat exchanger and the second auxiliary heat exchanger, the number of switching valves can be reduced, and the man-hours required for connecting the first refrigerant circuit and the first auxiliary refrigerant circuit can be suppressed.

[0008] (2) Preferably, a casing that houses the first auxiliary refrigerant circuit, the first air supply fan, and the first exhaust fan, and forms an air 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 air supply passage before passing through the first auxiliary heat exchanger and the air in the exhaust passage before passing through the second auxiliary heat exchanger is further provided. According to this configuration, by adopting a form in which the first heat recovery unit including the heat exchange unit is housed in one casing, the piping configuration around the first heat recovery unit can be simplified, and thereby, the connection work between the first refrigerant circuit and the first auxiliary refrigerant circuit becomes easier.

[0009] (3) Preferably, the first heat recovery unit has a casing, the first auxiliary refrigerant circuit and the first switching valve are housed in the casing. According to this configuration, by adopting a form in which the first heat recovery unit is housed in one casing, the piping configuration around the first heat recovery unit can be simplified, and thereby, the connection work between the first refrigerant circuit and the first auxiliary refrigerant circuit becomes easier.

[0010] (4) Preferably, the refrigerant is a flammable refrigerant, a shut-off valve provided between the first switching valve and the second connecting pipe and between the first switching valve and the third connecting pipe is further provided. According to this configuration, the leakage amount of the flammable refrigerant from the first heat recovery unit can be suppressed.

[0011] (5) Preferably, the third unit is arranged in a second space different from the first space, a second auxiliary refrigerant circuit having a third auxiliary heat exchanger and a fourth auxiliary heat exchanger connected in series with the third auxiliary heat exchanger via a refrigerant pipe, a second air supply fan that supplies outside air that has passed through the third auxiliary heat exchanger to the second space, a second exhaust fan that discharges the air in the second space that has passed through the fourth auxiliary heat exchanger to the outside, and a second switching valve that switches the flow of the refrigerant in the second auxiliary refrigerant circuit are further provided, the first refrigerant circuit and the second auxiliary refrigerant circuit are connected by the second connecting pipe and the third connecting pipe via the second switching valve. According to this configuration, in the case of including a plurality of heat recovery units including an auxiliary heat exchanger for heat recovery, it is possible to reduce the number of switching valves and suppress the man-hours required for connecting the first refrigerant circuit and each auxiliary refrigerant circuit.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0013] Hereinafter, the air conditioning system of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to these examples, and is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0014] FIG. 1 is a schematic diagram showing the overall configuration of an air conditioning system according to a first embodiment of the present disclosure. The air conditioning system 100 according to the first embodiment of the present disclosure is installed in a building, a factory, or the like to achieve air conditioning of a space to be air-conditioned. The air conditioning system 100 includes an air conditioner 101 and a refrigerant flow path switching device 140. The air conditioner 101 cools and heats the space to be air-conditioned by performing a vapor compression refrigeration cycle operation. The air conditioner 101 shown in this embodiment uses R32 as the refrigerant. Note that R32 is a refrigerant having slight flammability. The air conditioner of the present disclosure may be configured to use a refrigerant other than R32.

[0015] The air conditioning system 100 uses the indoor space S1 formed inside the building B as the space to be air-conditioned. A plurality of indoor spaces S1 are provided inside the building B. In the following description, the first indoor space S1 is referred to as the first space S11, the second indoor space S1 different from the first space S11 is referred to as the second space S12, and the space outside the building B is referred to as the outdoor space S2. The outdoor space S2 in the present disclosure is an outdoor space.

[0016] The air conditioner 101 includes an outdoor unit 110 as a heat source side unit, an indoor unit 120 as a utilization side unit, and a first heat recovery unit 130. 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 unit 120 is connected to the outdoor unit 110 via the refrigerant flow path switching device 140. The air conditioner 101 can freely select a cooling operation and a heating operation for each indoor unit 120 by the refrigerant flow path switching device 140 to perform air conditioning of the target space.

[0017] In the air conditioning system 100, the indoor unit 120 provided for the first space S11 can perform air conditioning of the first space S11 and ventilation of the first space S11 by the first heat recovery unit 130. In the air conditioning system 100, the indoor unit 120 provided for the second space S12 can perform air conditioning of 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 the building B.

[0018] [Configuration of Outdoor Unit] FIG. 2 is a refrigerant circuit diagram of the air conditioning system 100. As shown in FIG. 1, the outdoor unit 110 is installed in an outdoor area such as the roof or veranda of the building B or in an outdoor space S2 such as underground. As shown in FIG. 2, various devices are arranged in the outdoor unit 110, and these devices are connected via refrigerant pipes to form a heat source side refrigerant circuit RC1. The heat source side refrigerant circuit RC1 is connected to a first auxiliary refrigerant circuit RC2 in the first heat recovery unit 130 and an intermediate refrigerant circuit RC3 in the refrigerant flow path switching device 140 via a first connection pipe 11, a second connection pipe 12, and a third connection pipe 13.

[0019] As shown in FIG. 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 configured by connecting these devices via a plurality of refrigerant pipes. In the outdoor unit 110, an outdoor fan 33, a control unit 115 (see FIG. 7), etc. are arranged.

[0020] The liquid-side shutoff valve 21, the gas-side first shutoff valve 22, and the gas-side second shutoff valve 23 are manual valves that are opened and closed during refrigerant filling, pump-down, etc. One end of the liquid-side shutoff valve 21 is connected to the first connecting pipe 11. The other end of the liquid-side shutoff valve 21 is connected to a refrigerant pipe that extends to the first outdoor expansion valve 34 and the second outdoor expansion valve 35. One end of the gas-side first shutoff valve 22 is connected to the second connecting pipe 12. The other end of the gas-side first shutoff valve 22 is connected to a refrigerant pipe that extends to the second flow path switching valve 27. One end of the gas-side second shutoff valve 23 is connected to the third connecting pipe 13. The other end of the gas-side second shutoff valve 23 is connected to a refrigerant pipe 25c that extends to the accumulator 24.

[0021] The accumulator 24 is a container for temporarily storing the low-pressure refrigerant sucked into the compressor 25 and separating the gas refrigerant and the liquid refrigerant.

[0022] The compressor 25 has a hermetic structure incorporating a compressor motor and is, for example, a positive displacement compressor such as a scroll type or a rotary type. The compressor 25 compresses the low-pressure refrigerant sucked 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 in the refrigerant circuit together with the refrigerant. The outdoor unit 110 of the present embodiment includes one compressor 25. However, the outdoor unit 110 may include two or more compressors 25 connected in parallel.

[0023] 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 the refrigerant according to the operating conditions of the air conditioner 101. One refrigerant inlet 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 refrigerant inlet 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 connecting the gas-side second closing 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 such that the flow of the refrigerant in one refrigerant flow path is blocked during operation, and in fact, function as three-way valves.

[0024] 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 part 31 and a second heat exchange part 32. The first heat exchange part 31 is provided at the upper part of the outdoor heat exchanger 30, and the second heat exchange part 32 is provided at a lower part than the first heat exchange part 31.

[0025] The gas-side end of the first heat exchange part 31 is connected to a refrigerant pipe extending to the third flow path switching valve 28. The liquid-side end of the first heat exchange part 31 is connected to a refrigerant pipe extending to the first outdoor expansion valve 34.

[0026] The gas-side end of the second heat exchange part 32 is connected to a refrigerant pipe extending to the first flow path switching valve 26. The liquid-side end of the second heat exchange part 32 is connected to a refrigerant pipe extending to the second outdoor expansion valve 35.

[0027] The refrigerant passing through the first heat exchange part 31 and the second heat exchange part 32 exchanges heat with the air flow 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 air flow that flows into the outdoor unit 110, passes through the outdoor heat exchanger 30, and flows out of the outdoor unit 110.

[0028] The first outdoor expansion valve 34 and the second outdoor expansion valve 35 are, for example, motor-operated valves whose opening degrees can be adjusted. One end of the first outdoor expansion valve 34 is connected to a refrigerant pipe extending from the first heat exchange section 31. The other end of the first outdoor expansion valve 34 is connected to a refrigerant pipe extending to the liquid-side shutoff valve 21.

[0029] One end of the second outdoor expansion valve 35 is connected to a refrigerant pipe extending from the second heat exchange section 32. The other end of the second outdoor expansion valve 35 is connected to a refrigerant pipe extending to the liquid-side shutoff valve 21. The first outdoor expansion valve 34 and the second outdoor expansion valve 35 have their opening degrees adjusted according to the operating conditions, and decompress the refrigerant passing through them according to their opening degrees.

[0030] The compressor 25, the outdoor fan 33, the first outdoor expansion valve 34, the second outdoor expansion valve 35, the first flow path switching valve 26, the second flow path switching valve 27, and the third flow path switching valve 28 are operationally controlled by a control unit 115 (see FIG. 7). The control unit 115 of the outdoor unit 110 transmits and receives signals to and from the indoor control unit 54 (see FIG. 7) of the indoor unit 120 and a control unit (not shown) of the refrigerant flow path switching device 140 via a communication line.

[0031] [Configuration of Indoor Unit] The indoor unit 120 is a ceiling-embedded type, ceiling-suspended type, floor-standing type, or wall-mounted type. The air conditioning system 100 of the present embodiment includes two or more indoor units 120.

[0032] A user-side refrigerant circuit RC4 is provided inside the indoor unit 120. The user-side refrigerant circuit RC4 includes an indoor expansion valve 51 and an indoor heat exchanger 52. The user-side refrigerant circuit RC4 is configured by connecting the indoor expansion valve 51 and the indoor heat exchanger 52 with a refrigerant pipe.

[0033] The indoor unit 120 is provided with an indoor fan 53 and an indoor control unit 54 (see FIG. 7). The indoor expansion valve 51 is an electric valve whose opening 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 a refrigerant pipe extending 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.

[0034] The indoor heat exchanger 52 is, for example, a cross-fin type or micro-channel type heat exchanger. The liquid side end of the indoor heat exchanger 52 is connected to a refrigerant pipe 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 air flow generated by the indoor fan 53 and is discharged from the indoor heat exchanger 52.

[0035] 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 air flow that flows from the indoor space S1 into the indoor unit 120, passes through the indoor heat exchanger 52, and then flows out into the indoor space S1.

[0036] The indoor expansion valve 51 and the indoor fan 53 are operationally controlled by the indoor control unit 54 (see FIG. 7) of the indoor unit 120. The control unit 115 of the outdoor unit 110 and a remote controller (not shown) are connected to the indoor control unit 54. The indoor control unit 54 drives the indoor fan 53 and the indoor expansion valve 51 based on the operating conditions such as the set temperature input from the remote controller.

[0037] [Configuration of Refrigerant Flow Path Switching Device] As shown in FIGS. 1 and 2, the refrigerant flow path switching device 140 is provided between the outdoor unit 110 and a plurality of 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 the refrigerant flowing into the outdoor unit 110 and each indoor unit 120. As shown in FIG. 2, a plurality of header pipes 55, 56, 57, 58 and a plurality of switching units 70 are accommodated in the casing 141.

[0038] (Header pipe) As shown in FIG. 2, the plurality of header pipes 55, 56, 57, 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 communication pipe 11. The second header pipe 56 is connected to the second communication pipe 12. The third header pipe 57 is connected to the third communication pipe 13.

[0039] (Switching unit) The refrigerant flow path switching device 140 includes a plurality of switching units 70. Each switching unit 70 forms an intermediate refrigerant circuit RC3 of the refrigerant flow path switching device 140. One indoor unit 120 is connected to each switching unit 70. However, it is not necessary for all the switching units 70 of the refrigerant flow path switching device 140 to be connected to the indoor units 120, and there may be a switching unit 70 to which the indoor unit 120 is not connected in the refrigerant flow path switching device 140.

[0040] (Regarding the intermediate refrigerant circuit) The plurality of switching units 70 all have the same structure, and the intermediate refrigerant circuit RC3 of each switching unit 70 includes a plurality of valves EV1, EV2, EV3 and a plurality of refrigerant pipes.

[0041] In the switching unit 70, the plurality of valves EV1, EV2, EV3 include a first valve EV1, a second valve EV2, and a third valve EV3. These valves EV1, EV2, EV3 are constituted by motor-operated valves whose opening degrees can be adjusted. The second valve EV2 and the third valve EV3 are operationally controlled by a control unit (not shown) so as to take any one of a fully closed state, a fully open state, and an opening degree adjustment state. The first valve EV1 is operationally controlled by a control unit (not shown) so as to take any one of a minimum opening state, a fully open state, a fully closed state, and an opening degree adjustment state.

[0042] The switching unit 70 includes a first refrigerant pipe P1 that connects the second header pipe 56 and the first valve EV1. A filter F1 is provided in the middle of the first refrigerant pipe P1. The switching unit 70 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 includes a user-side gas pipe 61. One end of the user-side gas pipe 61 is connected to the gas pipe GP of the indoor unit 120. The other end of the user-side gas pipe 61 is connected to the second valve EV2. The other end of the second refrigerant pipe P2 is connected to the user-side gas pipe 61. A filter F2 is provided in the user-side gas pipe 61.

[0043] The switching unit 70 includes 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.

[0044] The switching unit 70 includes 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 subcooling heat exchanger 59. Inside the subcooling heat exchanger 59, a first heat transfer pipe 59a and a second heat transfer pipe 59b are provided. The subcooling heat exchanger 59 performs heat exchange between the refrigerant flowing through the first heat transfer pipe 59a and the refrigerant flowing through the second heat transfer pipe 59b. The other end of the user-side liquid pipe 62 is connected to one end of the first heat transfer pipe 59a.

[0045] The switching unit 70 includes a fourth refrigerant pipe P4. One end of the fourth refrigerant pipe P4 is connected to the other end of the first heat transfer pipe 59a. The other end of the fourth refrigerant pipe P4 is connected to the first header pipe 55.

[0046] The switching unit 70 includes a fifth refrigerant pipe P5 that branches from the middle of 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.

[0047] 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 pipe 59b of the subcooling heat exchanger 59. One end of the seventh refrigerant pipe P7 is connected to the second heat transfer pipe 59b of the subcooling 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.

[0048] Refrigerant flows into the fourth header pipe 58 from the first header pipe 55 through the fourth refrigerant pipe P4, the fifth refrigerant pipe P5, the third valve EV3, the sixth refrigerant pipe P6, the subcooling heat exchanger 59, and the seventh refrigerant pipe P7. Further, the refrigerant that has flowed into the fourth header pipe 58 flows into the third header pipe 57 through the connecting pipe 63.

[0049] [Configuration of the First Heat Recovery Unit] The first heat recovery unit 130 is a device that can supply air (outdoor air) that has been cooled and heated to the indoor space S1, recover heat from the air (exhaust air) discharged from the indoor space S1, and ventilate the indoor space S1, and is also referred to as an outdoor air treatment unit. The first heat recovery unit 130 is disposed outside the indoor space S1 inside the building B. The first heat recovery unit 130 is disposed 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 ducts. In the present embodiment, the case where the first heat recovery unit 130 is disposed in the space above the ceiling of the indoor space S1 is illustrated. However, the first heat recovery unit of the present disclosure may be a ceiling suspension type, a ceiling embedding type, a floor placement type, or a wall hanging type, and may be disposed at a location other than above the ceiling. As shown in FIGS. 2 and 3, the first heat recovery unit 130 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 unit 134. A first auxiliary refrigerant circuit RC2 is provided in the first heat recovery unit 130. The first auxiliary refrigerant circuit RC2 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 an auxiliary refrigerant pipe 135. The auxiliary refrigerant pipe 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.

[0050] The air supply side auxiliary heat exchanger 131 and the exhaust side auxiliary heat exchanger 132 are, for example, heat exchangers of a cross fin type or a microchannel type. One end of the air supply side auxiliary heat exchanger 131 is connected to a first auxiliary refrigerant pipe 135c extending from the auxiliary heat exchanger switching valve 133. The other end of the air supply side auxiliary heat exchanger 131 is connected to one end of a 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 136 is provided in the middle of the second auxiliary refrigerant pipe 135b. The electric valve 136 is an electric valve capable of adjusting the opening degree. The other end of the exhaust side auxiliary heat exchanger 132 is connected to a third auxiliary refrigerant pipe 135a extending from the auxiliary heat exchanger switching valve 133.

[0051] The switching valve 133 for the auxiliary heat exchanger is a four-way switching valve having four ports, and 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 to each port. The fourth auxiliary refrigerant pipe 135d is connected to the first branch pipe 14, and the fifth auxiliary refrigerant pipe 135e is connected to the second branch pipe 15. The switching valve 133 for the auxiliary heat exchanger switches the flow of the refrigerant among 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.

[0052] The first auxiliary refrigerant circuit RC2 is connected to the second connecting pipe 12 via the first branch pipe 14 and is connected to the third connecting pipe 13 via the second branch pipe 15. In other words, the first auxiliary refrigerant circuit RC2 of the first heat recovery unit 130 is connected to the heat source side refrigerant circuit RC1 of the outdoor unit 110 without passing through the refrigerant flow path switching device 140.

[0053] (Supply air fan and exhaust air fan) An air supply fan 137 and an exhaust fan 138 are disposed in the first heat recovery unit 130. 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 air flow that flows from the outdoor space S2 (see FIG. 1) into the first heat recovery unit 130, passes through the supply air side auxiliary heat exchanger 131, and then flows out into the indoor space S1 (see FIG. 1). The exhaust fan 138 is driven by an exhaust fan motor (not shown). The exhaust fan 138 generates an air flow that flows from the indoor space S1 (see FIG. 1) into the first heat recovery unit 130, passes through the exhaust air side auxiliary heat exchanger 132, and then flows out into the outdoor space S2 (see FIG. 1).

[0054] (Configuration of supply air passage and exhaust air passage) As shown in FIG. 3, the return air intake 157 is used to take in air (return air RA) from the indoor space S1 (see FIG. 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 to the outdoor space S2 (see FIG. 1) as exhaust air EA. 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 to the indoor space S1 as supply air SA. The supply air outlet 156 is connected to the indoor space S1 via a duct or the like (not shown).

[0055] (Heat exchange section) FIG. 4 is a perspective view of the heat exchange section. As shown in FIG. 4, the heat exchange section 134 in the present embodiment is a cross-flow type total heat exchanger configured such that the first air flow A1 and the second air flow A2 are substantially orthogonal. This heat exchange section 134 has a partition plate 134a and a partition wall plate 134b. The partition plate 134a and the partition wall plate 134b are alternately laminated with an appropriate adhesive. The heat exchange section 134 is formed in a substantially quadrangular prism shape as a whole.

[0056] The partition plate 134a has heat conductivity and moisture permeability and is formed in a flat plate shape. The partition wall plate 134b is formed in a corrugated plate shape in which substantially triangular cross-sections are continuously formed. The partition wall plate 134b forms an air passage between two adjacent partition plates 134a. The partition wall plates 134b are laminated at 90-degree angles for each sheet in the lamination direction of the partition plates 134a and the partition wall plates 134b (the vertical direction in FIG. 4). As a result, an air supply side passage 134d for passing the first air flow A1 and an exhaust side passage 134c for passing the second air flow A2 are formed orthogonally to each other on both sides of one partition plate 134a. The air flowing through the exhaust side passage 134c and the air flowing through the air supply side passage 134d exchange sensible heat and latent heat (total heat exchange) through the partition plate 134a having heat conductivity and moisture permeability. In the air conditioning system 100, the first heat recovery unit 130 recovers heat with the refrigerant flowing through the first auxiliary refrigerant circuit RC2, 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), so that the operating efficiency of the air conditioner 101 can be further improved.

[0057] FIG. 5 is a schematic cross-sectional explanatory view taken along the line X-X of FIG. 3. FIG. 6 is a schematic cross-sectional explanatory view taken along the line Y-Y of FIG. 3. As shown in FIGS. 3, 5, and 6, the first heat recovery unit 130 has a casing 150. The inside of the casing 150 is partitioned into two regions, an indoor space S1 side and an outdoor space S2 side (see FIG. 1), by the heat exchange unit 134. As shown in FIG. 5, an upstream air supply passage 151a is formed in the casing 150 on the upstream side of the first air flow A1 with respect to the heat exchange unit 134, and a downstream air supply passage 151b is formed on the downstream side of the first air flow A1 with respect to the heat exchange unit 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 unit 134.

[0058] As shown in Fig. 6, an upstream exhaust passage 152a is formed inside the casing 150 on the upstream side of the second air flow A2 with respect to the heat exchange section 134, and a downstream exhaust passage 152b is formed on the downstream side of the second air flow A2 with respect to the heat exchange section 134. The upstream exhaust passage 152a and the downstream exhaust passage 152b constitute an exhaust passage 152 that communicates the indoor space S1 and the outdoor space S2 via the heat exchange section 134.

[0059] As shown in Figs. 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.

[0060] As shown in Fig. 5, in the downstream air supply passage 151b, an air supply fan 137 and an air supply side auxiliary heat exchanger 131 are arranged near the air supply outlet 156. When the air supply fan 137 is operated, a first air flow A1 is generated, and the outside air OA in the outdoor space S2 passes through the air supply passage 151, is heat-exchanged by the air supply side auxiliary heat exchanger 131, and is supplied to the indoor space S1 as the supply air SA. As shown in Figs. 2 and 3, the air supply side auxiliary heat exchanger 131 performs heat exchange (heat recovery) between the refrigerant flowing through the first auxiliary refrigerant circuit RC2 and the air (outside air OA) passing through the air supply passage 151.

[0061] As shown in Fig. 6, in the downstream exhaust passage 152b, an exhaust fan 138 and an exhaust side auxiliary heat exchanger 132 are arranged near the exhaust outlet 155. When the exhaust fan 138 is operated, a second air flow A2 is generated, and the return air RA from the indoor space S1 passes through the exhaust passage 152, is heat-exchanged by the exhaust side auxiliary heat exchanger 132, and is discharged to the outdoor space S2 as the exhaust EA. As shown in Figs. 2 and 3, the exhaust side auxiliary heat exchanger 132 performs heat exchange (heat recovery) between the refrigerant flowing through the first auxiliary refrigerant circuit RC2 and the air (exhaust EA) passing through the exhaust passage 152.

[0062] The first heat recovery unit 130 shown in this embodiment has an air supply side auxiliary heat exchanger 131 and an exhaust side auxiliary heat exchanger 132. However, the heat recovery unit of the present disclosure may be provided with only the auxiliary heat exchanger on the air supply side. The first heat recovery unit 130 shown in this embodiment has a heat exchange section 134. However, the heat recovery unit of the present disclosure may omit the heat exchange section. In this embodiment, the first heat recovery unit 130 in which the air supply side auxiliary heat exchanger 131 and the exhaust side auxiliary heat exchanger 132 are housed in the casing 150 is illustrated. However, in the heat recovery unit of the present disclosure, the auxiliary heat exchangers on the air supply side and the exhaust side may not be housed in the casing. In this embodiment, the first heat recovery unit 130 in which the air supply side auxiliary heat exchanger 131 and the exhaust side auxiliary heat exchanger 132 are housed in one casing 150 is illustrated. However, in the heat recovery unit of the present disclosure, the auxiliary heat exchangers on the air supply side and the exhaust side may be separated and configured to be installable at different positions, respectively.

[0063] As described above, in the air conditioning system 100, in order to connect the first auxiliary refrigerant circuit RC2 of the first heat recovery unit 130 to the heat source side refrigerant circuit RC1, for example, it is not necessary to pass through a device provided with a large number of switching valves such as the refrigerant flow path switching device 140. The first auxiliary refrigerant circuit RC2, the second connection pipe 12, and the third connection pipe 13 can be easily connected via the switching valve 133 for the auxiliary heat exchanger.

[0064] [Regarding the control unit] FIG. 7 is a control block diagram of the air conditioning system 100. As shown in FIG. 7, the air conditioning system 100 includes a control unit 115. The control unit 115 is a device that controls the operations of the air conditioner 101 and the refrigerant flow path switching device 140, and is configured by, for example, a microcomputer including a processor such as a CPU and memories such as a RAM and a ROM. The control unit 115 may be realized as hardware using an LSI, an ASIC, an FPGA, etc. The control unit 115 exhibits a predetermined function when the processor executes a program installed in the memory. Note that the control unit 115 may be provided integrally with the air conditioner 101 as a part of the air conditioner 101, or may be provided separately as a device separate from the air conditioner 101.

[0065] The control unit 115 of the present embodiment is provided in the outdoor unit 110. The control unit 115 is connected to 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 fan 33, a first outdoor expansion valve 34, and a second outdoor expansion valve 35 built in the outdoor unit 110. The control unit 115 is connected to an indoor expansion valve 51 and an indoor fan 53 via the indoor control unit 54 of the indoor unit 120. The control unit 115 is connected to a switching valve 133 for an auxiliary heat exchanger, an electric valve 136, an air supply fan 137, and an exhaust fan 138 of the first heat recovery unit 130. Note that the control unit 115 may be connected to the switching valve 133 for an auxiliary heat exchanger, the electric valve 136, the air supply fan 137, and the exhaust fan 138 via a control unit (not shown) of the first heat recovery unit 130. The control unit 115 is connected to a first valve EV1, a second valve EV2, and a 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 a first shutoff valve 161 and a second shutoff valve 162. The control unit 115 controls the operations of the above-described respective units connected thereto according to the operating state of the air conditioning system 100.

[0066] [Regarding the shutoff valve] As shown in FIGS. 1 and 2, the air conditioning system 100 has a first shut-off valve 161 and a second shut-off valve 162. The first shut-off valve 161 and the second shut-off valve 162 are electric valves. The first shut-off valve 161 is arranged in the first branch pipe 14, and the second shut-off valve 162 is arranged in the second branch pipe 15. The operations of the first shut-off valve 161 and the second shut-off valve 162 are controlled by the control unit 115. A refrigerant sensor 180 (see FIG. 7) is connected to the control unit 115.

[0067] In the air conditioning system 100, the refrigerant sensor 180 (see FIG. 7) is arranged at a position where it can detect the refrigerant leaked from the first heat recovery unit 130. When the refrigerant sensor 180 detects the refrigerant, the control unit 115 operates the first shut-off valve 161 and the second shut-off valve 162. In the air conditioning system 100, when the first shut-off valve 161 and the second shut-off valve 162 operate, the first auxiliary refrigerant circuit RC2 of the first heat recovery unit 130 is completely separated from the other refrigerant circuits RC1, RC3, RC4 in the air conditioning system 100. For this reason, in the air conditioning system 100, even if a combustible refrigerant (R32 in this embodiment) leaks from the first heat recovery unit 130, it is possible to suppress the leakage of the refrigerant from the first heat recovery unit 130 beyond the amount of refrigerant stored in the first auxiliary refrigerant circuit RC2 at that time. Note that when a non-combustible refrigerant is used in the air conditioning system of the present disclosure, the first and second shut-off valves and the refrigerant sensor may be omitted.

[0068] [Operation of the air conditioning system] Hereinafter, with reference to FIG. 2, the cases where all the operating indoor units 120 perform cooling (hereinafter also referred to as "full cooling operation"), all the operating indoor units 120 perform heating (hereinafter also referred to as "full heating operation"), and some of the operating indoor units 120 perform cooling and the others perform heating (hereinafter also referred to as "cooling and heating mixed operation") by the air conditioning system 100 will be described.

[0069] (Full cooling operation) In the full cooling operation, each valve is adjusted as follows by the control unit 115. The first valve EV1 of the switching unit 70 is fully closed, the second valve EV2 is fully open, the third valve EV3 has its opening degree adjusted, the indoor expansion valve 51 has its opening degree adjusted, the first and second outdoor expansion valves 34, 35 are fully open, and the first and second shut-off valves 161, 162 are fully open. The first flow path switching valve 26 of the outdoor unit 110 is switched so as to connect the discharge pipe 25a of the compressor 25 and the gas side end of the second heat exchanger 32. The second flow path switching valve 27 is switched so as to connect the discharge pipe 25a and the second communication pipe 12. The third flow path switching valve 28 is switched so as to connect the discharge pipe 25a and the gas side end of the first heat exchanger 31.

[0070] In the stopped indoor unit 120, the indoor expansion valve 51 is fully closed by the control unit 115, the first valve EV1 corresponding to this indoor unit 120 is set to the minimum opening degree, and the second valve EV2 and the third valve EV3 are fully closed, regardless of whether full cooling operation, full heating operation, or cooling and heating mixed operation is performed.

[0071] When the compressor 25 is driven, the high-pressure gas refrigerant compressed by the compressor 25 flows into the outdoor heat exchanger 30 through 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 communication pipe 11 through the first and second outdoor expansion valves 34, 35, the liquid side shut-off valve 21, etc.

[0072] The refrigerant flowing into the first communication pipe 11 flows through the first header pipe 55 of the refrigerant flow path switching device 140 and 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 pipe 59a of the subcooling heat exchanger 59 and further flows into the indoor unit 120 through the utilization side liquid pipe 62.

[0073] The refrigerant flowing into the fourth refrigerant pipe P4 also branches and flows into the fifth refrigerant pipe P5, is depressurized according to the opening degree of the third valve EV3, and flows into the second heat transfer pipe 59b of the subcooling heat exchanger 59. In this subcooling heat exchanger 59, heat exchange occurs between the refrigerant flowing through the first heat transfer pipe 59a and the refrigerant flowing through the second heat transfer pipe 59b, and the refrigerant flowing through the first heat transfer pipe 59a is subcooled and flows into the indoor unit 120.

[0074] The refrigerant flowing through the second heat transfer pipe 59b of the subcooling heat exchanger 59 flows into the fourth header pipe 58 from the seventh refrigerant pipe P7, and flows into the third header pipe 57 through the connecting pipe 63. The refrigerant flowing into the indoor unit 120 evaporates in the indoor heat exchanger 52 after being depressurized by the indoor expansion valve 51.

[0075] In the indoor unit 120, the refrigerant evaporated in the indoor heat exchanger 52 flows into the utilization-side gas pipe 61 from the gas pipe GP, mainly passes through the second valve EV2, and flows into the third header pipe 57. The refrigerant flowing into the third header pipe 57 flows into the accumulator 24 through the third connecting pipe 13 and the gas-side second shut-off valve 23, and is sucked into the compressor 25.

[0076] (Regarding the treatment by the first heat recovery unit during the cooling operation) When the air conditioning system 100 is in the cooling operation, the control unit 115 switches the auxiliary heat exchanger switching valve 133 so that the first auxiliary refrigerant pipe 135a and the fourth auxiliary refrigerant pipe 135d are connected, and the third auxiliary refrigerant pipe 135c and the fifth auxiliary refrigerant pipe 135e are connected (see FIG. 3). High-pressure gas 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 first branch pipe 14, and the gas refrigerant flows into the exhaust-side auxiliary heat exchanger 132 from the first auxiliary refrigerant pipe 135a. At this time, by adjusting the opening degree of the electric valve 136 by the control unit 115, the amount of the refrigerant flowing into the exhaust-side auxiliary heat exchanger 132 is adjusted, and the pressure of the refrigerant is reduced. The gas refrigerant exchanges heat with air (exhaust EA) in the exhaust-side auxiliary heat exchanger 132 and is condensed into liquid refrigerant. This liquid refrigerant is supplied to the intake-side auxiliary heat exchanger 131 via the second auxiliary refrigerant pipe 135b. The liquid refrigerant exchanges heat with air (outdoor air OA) in the intake-side auxiliary heat exchanger 131 and is evaporated into low-pressure gas refrigerant. This low-pressure gas refrigerant is returned to the third connecting pipe 13 via the second branch pipe 15. The first heat recovery unit 130 thus cools the outdoor air OA and supplies it to the first space S11 during the cooling operation. The high-pressure gas refrigerant flowing through the second connecting pipe 12 via the second flow path switching valve 27 does not flow into the indoor unit 120 because the first valve EV1 is fully closed.

[0077] (Regarding the full heating operation) In the full heating operation, the control unit 115 adjusts each valve as follows. The first valve EV1 of the switching unit 70 is fully opened, the second valve EV2 is fully closed, the third valve EV3 is fully closed, the indoor expansion valve 51 is fully opened, the opening degrees of the first and second outdoor expansion valves 34, 35 are adjusted, and the first and second shut-off valves 161, 162 are fully opened. The first flow path switching valve 26 of the outdoor unit 110 is switched to connect the refrigerant pipe 25c and the gas-side end of the second heat exchange unit 32. The second flow path switching valve 27 is switched to connect the discharge pipe 25a and the second connecting pipe 12. The third flow path switching valve 28 is switched to connect the refrigerant pipe 25c and the gas-side end of the first heat exchange unit 31.

[0078] When the compressor 25 is driven, the high-pressure gas refrigerant compressed by the compressor 25 flows into the second connecting pipe 12 through the discharge pipe 25a, the second flow path switching valve 27, and the like. The refrigerant flowing into the second connecting pipe 12 passes through the first valve EV1 via the second header pipe 56 of the refrigerant flow path switching device 140 and the first refrigerant pipe P1 of the switching unit 70, and flows into the gas pipe GP of the indoor unit 120 from the utilization side gas pipe 61.

[0079] 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, flows through the liquid pipe LP, and flows into the utilization side liquid pipe 62 of the switching unit 70. The refrigerant flowing into the utilization side liquid pipe 62 flows into the first header pipe 55 via the subcooling heat exchanger 59 and the fourth refrigerant pipe P4.

[0080] The refrigerant flowing into the first header pipe 55 flows through the first connecting pipe 11 and into the outdoor unit 110, and is depressurized at the first and second outdoor expansion valves 34, 35. The depressurized refrigerant evaporates when passing through the outdoor heat exchanger 30, flows through the first flow path switching valve 26, the third flow path switching valve 28, and the like, flows into the accumulator 24, and is sucked into the compressor 25.

[0081] (Regarding the treatment by the first heat recovery unit during heating operation) When the air conditioning system 100 is in the heating operation, the auxiliary heat exchanger switching valve 133 is switched by the control unit 115, so that the third auxiliary refrigerant pipe 135c and the fourth auxiliary refrigerant pipe 135d are connected, and the first auxiliary refrigerant pipe 135a and the fifth auxiliary refrigerant pipe 135e are connected (see FIG. 3). High-pressure gas refrigerant is supplied to the air supply side auxiliary heat exchanger 131 of the first heat recovery unit 130 from the second communication pipe 12 and the first branch pipe 14, and the gas refrigerant flows into the air supply side auxiliary heat exchanger 131 from the fourth auxiliary refrigerant pipe 135d and the third auxiliary refrigerant pipe 135c. At this time, by adjusting the opening degree of the electric valve 136 by the control unit 115, the amount of the refrigerant flowing into the air supply side auxiliary heat exchanger 131 is adjusted, and the pressure of the refrigerant is reduced. The gas refrigerant exchanges heat with air (outdoor air OA) in the air supply side auxiliary heat exchanger 131 and is condensed into a liquid refrigerant. The liquid refrigerant is supplied to the exhaust side auxiliary heat exchanger 132 via the second auxiliary refrigerant pipe 135b, and exchanges heat with air (exhaust EA) in the exhaust side auxiliary heat exchanger 132 and is evaporated into a low-pressure gas refrigerant. This low-pressure gas refrigerant is returned to the third communication pipe 13 via the first auxiliary refrigerant pipe 135a, the fifth auxiliary refrigerant pipe 135e, and the second branch pipe 15. In this way, the first heat recovery unit 130 heats the outdoor air OA and supplies it to the first space S11 during the heating operation.

[0082] (Heating and cooling mixed operation) In the cooling / heating mixed operation, each valve is adjusted as follows by the control unit 115. Among the operating indoor units 120, in the switching unit 70 (hereinafter also referred to as the "cooling-side switching unit 70") corresponding to the indoor unit 120 that performs the cooling operation (hereinafter also referred to as the "cooling-side indoor unit 120"), the first valve EV1 is set to the minimum opening degree, the second valve EV2 is set to the fully open state, the third valve EV3 has its opening degree adjusted, the indoor expansion valve 51 of the cooling-side indoor unit 120 has its opening degree adjusted, and the first and second shut-off valves 161 and 162 are set to the fully open state. The first flow path switching valve 26 of the outdoor unit 110 is switched so as to connect the refrigerant pipe 25c and the gas-side end of the second heat exchanger 32. The second flow path switching valve 27 is switched so as to connect the discharge pipe 25a and the second connection pipe 12. The third flow path switching valve 28 is switched so as to connect the discharge pipe 25a and the gas-side end of the first heat exchanger 31.

[0083] Among the operating indoor units 120, in the switching unit 70 (hereinafter also referred to as the "heating-side switching unit 70") corresponding to the indoor unit 120 that performs the heating operation (hereinafter also referred to as the "heating-side indoor unit 120"), the first valve EV1 is set to the fully open state, the second valve EV2 is set to the fully closed state, the third valve EV3 is set to the fully closed state, the indoor expansion valve 51 of the heating-side indoor unit 120 is set to the fully open state, and the first outdoor expansion valve 34 and the second outdoor expansion valve 35 have their opening degrees adjusted. In this embodiment, the indoor unit 120 (cooling-side indoor unit 120) in the first space S11 is operated in the cooling mode, and the indoor unit 120 (heating-side indoor unit 120) in the second space S12 is operated in the heating mode. 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 in the first space S11, and the exhaust-air side auxiliary heat exchanger 132 functions as a condenser.

[0084] When the compressor 25 is driven, a part of the high-pressure gas refrigerant compressed by the compressor 25 flows into the second connecting pipe 12 through the discharge pipe 25a and the second flow path switching valve 27. Another part of the high-pressure gas refrigerant compressed by the compressor 25 is condensed in the first heat exchange part 31 of the outdoor heat exchanger 30 through the discharge pipe 25a and the third flow path switching valve 28. A part of it flows into the first connecting pipe 11 through the first outdoor expansion valve 34, and the rest flows into the second outdoor expansion valve 35. The refrigerant condensed in the first heat exchange part 31 evaporates in the second heat exchange part 32 through the second outdoor expansion valve 35 and is sucked into the compressor 25 through the first flow path switching valve 26. In the cooling and heating mixed operation, the usage of the second heat exchange part 32 is changed according to the balance between the condensation amount and evaporation amount of the refrigerant in the indoor unit 120 and the first heat recovery unit 130. In the cooling and heating mixed operation, both the first heat exchange part 31 and the second heat exchange part 32 function as a condenser or an evaporator according to the balance between the condensation amount and evaporation amount of the refrigerant in the indoor unit 120 and the first heat recovery unit 130.

[0085] The refrigerant flowing 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 utilization side gas pipe 61 of the heating side switching unit 70, and flows into the gas pipe GP.

[0086] 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, flows through the subcooling heat exchanger 59 and the fourth refrigerant pipe P4, and flows into the first header pipe 55.

[0087] The refrigerant flowing into the first connecting pipe 11 from the outdoor unit 110 also flows into the first header pipe 55. The refrigerant flowing into the first header pipe 55 flows into the cooling side indoor unit 120 through the fourth refrigerant pipe P4, the subcooling heat exchanger 59, the utilization side liquid pipe 62, and the liquid pipe LP of the cooling side switching unit 70. At this time, the refrigerant passing through the subcooling heat exchanger 59 branches from the fourth refrigerant pipe P4, flows through the fifth refrigerant pipe P5, and is subcooled by the refrigerant decompressed by the third valve EV3.

[0088] The refrigerant flowing into the indoor unit 120 on the cooling side is depressurized by the indoor expansion valve 51, evaporates in the indoor heat exchanger 52, and cools the interior of the room. The evaporated refrigerant flows through the gas pipe GP, enters the utilization-side gas pipe 61 of the cooling-side switching unit 70, flows into the third refrigerant pipe P3 and the third header pipe 57 through the second valve EV2, flows through the third connecting pipe 13, enters the accumulator 24, and is sucked into the compressor 25.

[0089] The first heat recovery unit 130 has the supply-side auxiliary heat exchanger 131 functioning as an evaporator in accordance with the indoor unit 120 on the cooling side of the first space S11, cools the outside air OA, and supplies the supply air SA to the indoor space S11. The first heat recovery unit 130 has the exhaust-side auxiliary heat exchanger 132 functioning as a condenser, recovers heat from the return air RA to evaporate the gas refrigerant, and discharges the heated return air RA as the exhaust air EA to the outdoor space S2.

[0090] [Air conditioning system according to the second embodiment] FIG. 8 is a schematic diagram showing the overall configuration of the air conditioning system according to the second embodiment of the present disclosure. FIG. 9 is a refrigerant circuit diagram of the air conditioning system according to the second embodiment. FIG. 10 is a control block diagram of the air conditioning system according to the second embodiment. As shown in FIG. 8, the air conditioning system 200 according to the second embodiment of the present disclosure includes an air conditioner 102 and a refrigerant flow path switching device 140. In FIGS. 8 to 10, the same components as those described in FIGS. 1 to 7 are denoted by the same reference numerals, and in the following description, the description of the components denoted by the same reference numerals will be omitted unless otherwise specified.

[0091] As shown in FIGS. 8 and 9, the air conditioner 102 includes an outdoor unit 110 as a heat source side unit, an indoor unit 120 as a utilization side unit, a first heat recovery unit 130, and a second heat recovery unit 170. The air conditioner 101 of the present embodiment has two or more indoor units 120 and two heat recovery units 130 and 170 connected to one outdoor unit 110. In other words, the air conditioner 102 has an additional second heat recovery unit 170 compared to the air conditioner 101 described above. That is, the air conditioning system 200 according to the second embodiment is different from the air conditioning system 100 according to the first embodiment in that it has a second heat recovery unit 170.

[0092] In the air conditioning system 200 of the present embodiment, the indoor unit 120 performs air conditioning of the first space S11, and the first heat recovery unit 130 performs ventilation of the first space S11. Further, in the air conditioning system 200, the indoor unit 120 performs air conditioning of the second space S12, and the second heat recovery unit 170 performs ventilation of the second space S12.

[0093] [Configuration of the Second Heat Recovery Unit] As shown in FIGS. 8 and 9, the air conditioning system 200 of the present embodiment includes a first heat recovery unit 130 and a second heat recovery unit 170. The first heat recovery unit 130 and the second heat recovery unit 170 have a common configuration (they are the same unit).

[0094] The second heat recovery unit 170 is a device for ventilating the second space S12, and has an auxiliary refrigerant circuit having a supply air side auxiliary heat exchanger 131 and an exhaust air side auxiliary heat exchanger 132 connected in series with the supply air side auxiliary heat exchanger 131 via an auxiliary refrigerant pipe 135. In the following description, the auxiliary refrigerant circuit in the second heat recovery unit 170 is referred to as a second auxiliary refrigerant circuit RC5, and is distinguished from the first auxiliary refrigerant circuit RC2 in the first heat recovery unit 130.

[0095] The second heat recovery unit 170 includes a second supply air fan 137 that supplies outside air OA that has passed through the supply air side auxiliary heat exchanger 131 to the second space S12, and a second exhaust air fan 138 that discharges the air (return air RA) in the second space S12 that has passed through the exhaust air side auxiliary heat exchanger 132 to the outside. The air conditioning system 200 includes an auxiliary heat exchanger switching valve 133 that switches the flow of the refrigerant in the second auxiliary refrigerant circuit RC5.

[0096] The auxiliary heat exchanger switching valve 133 (see FIG. 3) of the second heat recovery unit 170 is a four-way switching valve having four ports, and 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 to each port. As shown in FIG. 9, the fourth auxiliary refrigerant pipe 135d (see FIG. 3) is connected to the third branch pipe 16, and the fifth auxiliary refrigerant pipe 135e (see FIG. 3) is connected to the fourth branch pipe 17.

[0097] The second auxiliary refrigerant circuit RC5 is connected to the second connecting pipe 12 via the third branch pipe 16 and is connected to the third connecting pipe 13 via the fourth branch pipe 17. In other words, the second auxiliary refrigerant circuit RC5 of the second heat recovery unit 170 is connected to the heat source side refrigerant circuit RC1 of the outdoor unit 110 without passing through the refrigerant flow path switching device 140.

[0098] In the air conditioning system 200, the heat source side refrigerant circuit RC1 and the second auxiliary refrigerant circuit RC5 are connected by the second connecting pipe 12 and the third connecting pipe 13 via the third and fourth branch pipes 16, 17 and the auxiliary heat exchanger switching valve 133.

[0099] As described above, in the air conditioning system 200, even when the first heat recovery unit 130 and the second heat recovery unit 170 are provided, each heat recovery unit 130, 170 and the second connecting pipe 12 and the third connecting pipe 13 can be easily connected via the respective auxiliary heat exchanger switching valves 133, 133.

[0100] The air conditioning system 200 has a third shut-off valve 163 and a fourth shut-off valve 164. The third shut-off valve 163 and the fourth shut-off valve 164 are electric valves. The third shut-off valve 163 is arranged in the third branch pipe 16, and the third shut-off valve 163 is arranged in the fourth branch pipe 17. The third shut-off valve 163 and the fourth shut-off valve 164 are connected to the control unit 115 and are operationally controlled by the control unit 115.

[0101] In the air conditioning system 200, a refrigerant sensor 180 (see FIG. 10) is arranged at a position where it can detect the refrigerant leaking from the first heat recovery unit 130 and the second heat recovery unit 170. The control unit 115 is connected to the refrigerant sensor 180, and when the refrigerant sensor 180 detects the refrigerant, it activates and closes each of the shut-off valves 161, 162, 163, 164.

[0102] In the air conditioning system 200, when the third shut-off valve 163 and the fourth shut-off valve 164 are activated, the second auxiliary refrigerant circuit RC5 is disconnected from each of the other refrigerant circuits RC1, RC2, RC3, RC4 in the air conditioning system 200. Therefore, in the air conditioning system 200, even if the refrigerant leaks from the second heat recovery unit 170, it is possible to suppress the refrigerant from leaking out of the second heat recovery unit 170 beyond the amount of refrigerant stored in the second auxiliary refrigerant circuit RC5 at that time.

[0103] [Operation and Effect of the Embodiment] In the air conditioning systems 100 and 200 in the above-described first and second embodiments, 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 disposed in the first space S11 and having an indoor heat exchanger 52, an indoor unit 120 disposed in the second space S12 and having an indoor heat exchanger 52, and a refrigerant flow path switching device 140 having an intermediate refrigerant circuit RC3 for individually functioning each indoor heat exchanger 52 as an evaporator or a condenser. Each of the air conditioning systems 100 and 200 includes a first auxiliary refrigerant circuit RC2 including an air supply side auxiliary heat exchanger 131 and an exhaust side auxiliary heat exchanger 132 connected in series with the air supply side auxiliary heat exchanger 131 via an auxiliary refrigerant pipe 135, an air supply fan 137 for supplying outside air that has passed through the air supply side auxiliary heat exchanger 131 to the first space S11, an exhaust fan 138 for discharging the air in the first space S11 that has passed through the exhaust side auxiliary heat exchanger 132 to the outside, and an auxiliary heat exchanger switching valve 133 for switching the flow of the refrigerant in the first auxiliary refrigerant circuit RC2. Each of the air conditioning systems 100 and 200 is provided with a first heat recovery unit 130. In each of the air conditioning systems 100 and 200, the heat source side refrigerant circuit RC1 and the intermediate refrigerant circuit RC3 are connected by a first communication pipe 11 through which a liquid refrigerant flows, a second communication pipe 12 through which a high-pressure gas refrigerant flows, and a third communication pipe 13 through which a low-pressure gas refrigerant flows, and the heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC2 are connected by the second communication pipe 12 and the third communication pipe 13 via the auxiliary heat exchanger switching valve 133.

[0104] With the above configuration, the outdoor unit 110 and the first heat recovery unit 130 can be connected by the second communication pipe 12 and the third communication pipe 13 via the auxiliary heat exchanger switching valve 133. Thereby, for the air conditioning systems 100 and 200 provided with the first heat recovery unit 130 including the air supply side auxiliary heat exchanger 131 and the exhaust side auxiliary heat exchanger 132, the number of switching valves can be reduced, and the man-hours required for connecting the heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC2 can be suppressed.

[0105] In the configuration as described above, based on the balance between the evaporator capacity and the condenser capacity of the entire air conditioning systems 100 and 200, by only controlling the flow of the refrigerant in the first auxiliary refrigerant circuit RC2 with the switching valve 133 for the auxiliary heat exchanger, the first heat recovery unit 130 can efficiently perform heat recovery. As a result, it becomes possible to efficiently operate the air conditioning systems 100 and 200.

[0106] Each of the air conditioning systems 100 and 200 in the first and second embodiments described above includes a casing 150 that houses the first auxiliary refrigerant circuit RC2, the supply air fan 137, and the exhaust air fan 138, and forms an air supply passage 151 through which air passing through the supply air side auxiliary heat exchanger 131 flows, and an exhaust passage 152 through which air passing through the exhaust air side auxiliary heat exchanger 132 flows, and a heat exchange section 134 that performs heat exchange between the air in the air supply passage 151 before passing through the supply air side auxiliary heat exchanger 131 and the air in the exhaust passage 152 before passing through the exhaust air side auxiliary heat exchanger 132. According to this configuration, by adopting a form in which the first heat recovery unit 130 including the heat exchange section 134 is housed in one casing 150, the piping configuration around the first heat recovery unit 130 can be simplified. As a result, the connection work between the heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC2 becomes easier.

[0107] In each of the air conditioning systems 100 and 200 in the first and second embodiments described above, the first heat recovery unit 130 has a casing 150, and the first auxiliary refrigerant circuit RC2 and the switching valve 133 for the auxiliary heat exchanger are housed in the casing 150. According to this configuration, by adopting a form in which the first heat recovery unit 130 is housed in one casing 150, the piping configuration around the first heat recovery unit 130 can be simplified, and as a result, the connection work between the heat source side refrigerant circuit RC1 and the first auxiliary refrigerant circuit RC2 becomes easier.

[0108] In each of the air conditioning systems 100 and 200 in the above-described first and second embodiments, the refrigerant used is a flammable refrigerant, and each shut-off valve 161 to 164 provided between the auxiliary heat exchanger switching valve 133 and the second connecting pipe 12 and between the auxiliary heat exchanger switching valve 133 and the third connecting pipe 13 is further provided. According to this configuration, the leakage amount of the flammable refrigerant from the first heat recovery units 130 and 170 can be suppressed.

[0109] In the air conditioning system 200 in the above-described second embodiment, the indoor unit 120 is disposed in a second space S12 different from the first space S11. The air conditioning system 200 further includes a second auxiliary refrigerant circuit RC5 having an air supply side auxiliary heat exchanger 131 and an exhaust side auxiliary heat exchanger 132 connected in series with the air supply side auxiliary heat exchanger 131 via an auxiliary refrigerant pipe 135, an air supply fan 137 that supplies outside air that has passed through the air supply side auxiliary heat exchanger 131 to the second space S12, an exhaust fan 138 that discharges the air in the second space S12 that has passed through the exhaust side auxiliary heat exchanger 132 to the outside, and an auxiliary heat exchanger switching valve 133 that switches the flow of the refrigerant in the second auxiliary refrigerant circuit RC5. The air conditioning system 200 has a second heat recovery unit 170. The heat source side refrigerant circuit RC1 and the second auxiliary refrigerant circuit RC5 are connected by a second connecting pipe 12 and a third connecting pipe 13 via an auxiliary heat exchanger switching valve 133. According to this configuration, in the case of including a plurality of heat recovery units (the first heat recovery unit 130 and the second heat recovery unit 170) including an auxiliary heat exchanger for heat recovery, the number of switching valves can be reduced, and the man-hours required for connecting the heat source side refrigerant circuit RC1 and each of the auxiliary refrigerant circuits RC2 and RC5 can be suppressed.

Explanation of Reference Numerals

[0110] 11: First connecting pipe 12: Second connecting pipe 13: Third connecting pipe 25: Compressor 30: Outdoor heat exchanger (first heat exchanger) 52: Indoor heat exchanger (second heat exchanger, third heat exchanger) 70: Switching Unit (Intermediate Unit) 100: Air Conditioning System (First Embodiment) 110: Outdoor Unit (First Unit) 120: Indoor Unit (Second Unit) 130: First Heat Recovery Unit 131: Supply Air Side Auxiliary Heat Exchanger (First Auxiliary Heat Exchanger) 132: Exhaust Air Side Auxiliary Heat Exchanger (Second Auxiliary Heat Exchanger) 133: Switching Valve for Auxiliary Heat Exchanger (First Switching Valve, Second Switching Valve) 134: Heat Exchange Section 135: Auxiliary Refrigerant Pipe (Refrigerant Pipe) 137: Supply Air Fan (First Supply Air Fan, Second Supply Air Fan) 138: Exhaust Air Fan (First Exhaust Air Fan, Second Exhaust Air Fan) 150: Casing 151: Supply Air Passage 152: Exhaust Air Passage 161: First Shutoff Valve (Shutoff Valve) 162: Second Shutoff Valve (Shutoff Valve) 170: Second Heat Recovery Unit 200: Air Conditioning System (Second Embodiment) RC1: Heat Source Side Refrigerant Circuit (First Refrigerant Circuit) RC2: First Auxiliary Refrigerant Circuit RC3: Intermediate Refrigerant Circuit RC5: Second Auxiliary Refrigerant Circuit S11: First Space S12: Second Space

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) disposed in a first space (S11) and having a second heat exchanger (52); A third unit (120) having a third heat exchanger (52); An intermediate unit (70) having an intermediate refrigerant circuit (RC3) for causing one of the second heat exchanger (52) and the third heat exchanger (52) to function as an evaporator and the other to function as a condenser; A first auxiliary refrigerant circuit (RC2) including a first auxiliary heat exchanger (131) and a second auxiliary heat exchanger (132) connected in series with the first auxiliary heat exchanger (131) via a refrigerant pipe (135), and refrigerant flowing inside the first auxiliary heat exchanger (131) and the second auxiliary heat exchanger (132); A first air supply fan (137) for supplying outside air passing through the first auxiliary heat exchanger (131) to the first space (S11), a first exhaust fan (138) for discharging air in the first space (S11) passing through the second auxiliary heat exchanger (132) to the outside (S2), a first switching valve (133) for switching the flow of refrigerant in the first auxiliary refrigerant circuit (RC2), and a casing (150), and a first heat recovery unit (130) in which the first auxiliary refrigerant circuit (RC2) and the first switching valve (133) are housed in the casing (150); Comprising: The first refrigerant circuit (RC1) and the intermediate refrigerant circuit (RC3) are connected by a first connection pipe (11) through which liquid refrigerant flows, a second connection pipe (12) through which high-pressure gas refrigerant flows, and a third connection pipe (13) through which low-pressure gas refrigerant flows; The first refrigerant circuit (RC1) and the first auxiliary refrigerant circuit (RC2) are connected by the second connection pipe (12) and the third connection pipe (13) via the first switching valve (133). An air conditioning system (100, 200).

2. A casing (150) that houses the first auxiliary refrigerant circuit (RC2), the first intake fan (137), and the first exhaust fan (138), and that forms an intake passage (151) through which air passing through the first auxiliary heat exchanger (131) flows, and an exhaust passage (152) through which air passing through the second auxiliary heat exchanger (132) flows. The air conditioning system (100, 200) according to claim 1, further comprising a heat exchange section (134) that performs heat exchange between the air in the intake passage (151) before passing through the first auxiliary heat exchanger (131) and the air in the exhaust passage (152) before passing through the second auxiliary heat exchanger (132).

3. The refrigerant is a flammable refrigerant. The air conditioning system (100, 200) according to claim 1 or claim 2, further comprising shut-off valves (161, 162) provided between the first switching valve (133) and the second connecting pipe (12), and between the first switching valve (133) and the third connecting pipe (13).

4. The third unit (120) is disposed in a second space (S12) different from the first space (S11). A second auxiliary refrigerant circuit (RC5) having a third auxiliary heat exchanger (131) and a fourth auxiliary heat exchanger (132) connected in series with the third auxiliary heat exchanger (131) via a refrigerant pipe (135); a second intake fan (137) that supplies outside air that has passed through the third auxiliary heat exchanger (131) to the second space (S12); a second exhaust fan (138) that discharges the air in the second space (S12) that has passed through the fourth auxiliary heat exchanger (132) to the outside; and a second switching valve (133) that switches the flow of the refrigerant in the second auxiliary refrigerant circuit (RC5). The air conditioning system (200) according to any one of claims 1 to 3, wherein the first refrigerant circuit (RC1) and the second auxiliary refrigerant circuit (RC5) are connected by the second connecting pipe (12) and the third connecting pipe (13) via the second switching valve (133).

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