Air conditioning system

Abstract

An air conditioning system (1) includes: an outdoor unit (110); a plurality of indoor units (120); and a plurality of refrigerant flow path switching devices (130A to 130D) that switch a flow path of refrigerant between the outdoor unit (110) and the plurality of indoor units (120). The lengths of pipes (L1 to L3) are set in such a manner that a value obtained by adding a first value (Ka to Kd) to the lengths of the pipes (L1 to L3) reaches a prescribed upper limit value (Lu) or below, the lengths of the pipes (L1 to L3) being a total of lengths of external pipes (11 to 13, 161 to 163, 151 to 153, 141 to 143) from the outdoor unit (110) to the indoor units (120) connected to the refrigerant flow path switching device (130D) located at the most downstream side, and the first value (Ka to Kd) being determined in accordance with a total of capacities of the indoor units (120) connected to the refrigerant flow path switching devices (130A to 130D).

Description

Technical Field

[0001] This disclosure relates to an air conditioning system. Background Technology

[0002] A refrigerant flow path switching device is known in an air conditioner having an outdoor unit and multiple indoor units, in order to switch between cooling operation and heating operation in each indoor unit respectively (for example, see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-114049 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The piping length from the outdoor unit to the indoor unit via the refrigerant flow path switching device is set such that the sum of a predetermined first value and the piping length is within a predetermined upper limit. This first value is determined taking into account the pressure loss of the refrigerant piping from the refrigerant flow path switching device, and is a relatively long fixed value determined in the case of maximum pressure loss. However, depending on the capacity of the indoor unit, the pressure loss of the refrigerant piping may sometimes be smaller than the aforementioned first value. If the first fixed value is used to set the piping length in such cases, the piping length will be restricted to an excessively short length.

[0008] The purpose of this disclosure is to provide an air conditioning system that allows for a longer piping length from the outdoor unit to the indoor unit.

[0009] Technical solutions adopted to solve technical problems

[0010] (1) The air conditioning system disclosed herein,

[0011] It includes: an outdoor unit; multiple indoor units; and at least one refrigerant flow path switching device, which switches the refrigerant flow path between the outdoor unit and the multiple indoor units.

[0012] The piping length is set in such a way that the value after adding at least a first value to the piping length is below a predetermined upper limit value. The piping length is the sum of the lengths of the external piping from the outdoor unit to the indoor unit via the refrigerant path switching device. The first value is determined based on the total capacity of the indoor units connected to the refrigerant path switching device.

[0013] In an air conditioning system configured in this way, the total length of the external piping from the outdoor unit to the indoor unit can be calculated by subtracting a first value determined based on the capacity of the indoor unit from an upper limit value. Therefore, the smaller the total capacity of the indoor units, the shorter the first value can be, and thus, the longer the piping from the outdoor unit to the indoor unit can be made accordingly.

[0014] (2) Preferably, the air conditioning system includes multiple refrigerant flow path switching devices connected in series.

[0015] The first value corresponding to each of the refrigerant flow path switching devices is determined based on the sum of the capacities of the indoor units connected to the refrigerant flow path switching device and the refrigerant flow path switching devices located downstream of the refrigerant flow path switching device.

[0016] The piping length is the sum of the lengths of the external piping from the outdoor unit to the indoor unit connected to the refrigerant flow path switching device located at the downstream end, i.e., the maximum piping length.

[0017] The upper limit value is the upper limit of the maximum piping length.

[0018] The maximum piping length is set in such a way that the value after adding at least the first value corresponding to the plurality of refrigerant flow path switching devices to the maximum piping length is below the upper limit length.

[0019] With the above structure, the sum of the capacities of the first values ​​corresponding to each refrigerant flow path switching device and the indoor units connected to the refrigerant flow path switching device and the refrigerant flow path switching device located downstream of the refrigerant flow path switching device can be reduced as much as possible. Consequently, the sum of the lengths of the external piping from the outdoor unit to the indoor unit connected to the refrigerant flow path switching device located at the downstream end, i.e., the maximum piping length, can be increased in proportion to the decrease in each first value.

[0020] (3) Preferably, the pipe length is set in such a way that the value after adding the correction length of the branch pipe configured between the outdoor unit and the indoor unit is below the upper limit value.

[0021] With the above structure, branching piping is taken into account when setting the piping length from the outdoor unit to the indoor unit, thereby enabling the piping length to be set to an appropriate value.

[0022] (4) Preferably, the air conditioning system includes multiple refrigerant flow path switching devices connected in series.

[0023] The external piping has connecting piping that connects adjacent refrigerant flow path switching devices to each other.

[0024] The diameter of the connecting piping is set based on the total capacity of the indoor units connected to the refrigerant flow path switching device located downstream of the connecting piping.

[0025] The above structure allows the pipe diameter to be set to an appropriate value. As a result, it can prevent oil from returning during return operation due to an excessively large pipe diameter, and prevent excessive pressure loss due to an excessively small pipe diameter. Attached Figure Description

[0026] Figure 1 This is a structural diagram of an air conditioning system according to one embodiment of the present disclosure.

[0027] Figure 2 This is the refrigerant circuit diagram for an air conditioning system.

[0028] Figure 3 This is a 3D view of the refrigerant flow path switching device.

[0029] Figure 4 This is a piping system diagram showing an example of the connection of a refrigerant flow path switching device in an air conditioning system.

[0030] Figure 5 This is a piping system diagram that illustrates the piping length of the air conditioning system.

[0031] Figure 6 This is a table that illustrates the first value corresponding to the sum of the capabilities of multiple indoor units.

[0032] Figure 7 This is a piping system diagram showing another connection example of a refrigerant flow path switching device in an air conditioning system. Detailed Implementation

[0033] The air conditioning system of this disclosure will now be described in detail with reference to the accompanying drawings. Furthermore, this disclosure is not limited to these examples, but is intended to include all modifications expressed in and equivalent to those in the claims.

[0034] Figure 1 This is a structural diagram of an air conditioning system according to one embodiment of the present disclosure.

[0035] An air conditioning system 100 is installed in buildings, factories, etc., to achieve air conditioning of the target space. The air conditioning system 100 includes an air conditioner 101 and a refrigerant flow path switching device 130. The air conditioner 101 cools and heats the target space by performing a vapor compression refrigeration cycle.

[0036] Air conditioner 101 includes an outdoor unit 110 serving as a heat source unit and an indoor unit 120 serving as a utilization unit. Multiple indoor units 120 are connected to one outdoor unit 110 via a refrigerant path switching device 130. Air conditioner 101 can freely select between cooling and heating operation for each indoor unit 120 via the refrigerant path switching device 130.

[0037] [Structure of the outdoor unit]

[0038] Figure 2 This is the refrigerant circuit diagram for an air conditioning system.

[0039] Outdoor unit 110 may be located outdoors or underground, such as on the roof or balcony of a building.

[0040] The outdoor unit 110 includes a gas-side first shut-off valve 21, a gas-side second shut-off valve 22, a liquid-side shut-off valve 23, a storage tank 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, an outdoor fan 33, a first outdoor expansion valve 34, and a second outdoor expansion valve 35. The outdoor heat exchanger 30 includes a first heat exchange section 31 and a second heat exchange section 32. The outdoor unit 110 is connected to the refrigerant flow path switching device 130 via a liquid connecting pipe 11, a suction gas connecting pipe 12, and a high- and low-pressure gas connecting pipe 13.

[0041] [Structure of the Indoor Unit]

[0042] The indoor unit 120 can be ceiling-embedded, ceiling-suspended, floor-standing, or wall-mounted. The air conditioning system 100 of this embodiment includes, for example, four indoor units 120. Each indoor unit 120 includes an indoor expansion valve 51, an indoor heat exchanger 52, an indoor fan 53, a liquid pipe LP, and a gas pipe GP.

[0043] [Structure of the refrigerant flow path switching device]

[0044] A refrigerant flow path switching device 130 is disposed between the outdoor unit 110 and multiple indoor units 120. The refrigerant flow path switching device 130 switches the refrigerant flow path between the outdoor unit 110 and the multiple indoor units 120.

[0045] Figure 3 This is a 3D diagram of a refrigerant flow path switching device. (For example...) Figure 2 and Figure 3 As shown, the refrigerant flow path switching device 130 includes a housing 131, a control box 132, multiple manifolds (refrigerant piping) 55, 56, 57, and multiple switching units 70. The multiple manifolds 55, 56, 57 include a first manifold 55, a second manifold 56, and a third manifold 57.

[0046] The refrigerant flow path switching device 130 of this embodiment includes four switching units 70. Each switching unit 70 is connected to one indoor unit 120. Therefore, the refrigerant flow path switching device 130 of this embodiment can connect four indoor units 120. However, the refrigerant flow path switching device 130 may also include two, three, or five or more switching units 70, and is not limited to four switching units 70.

[0047] The multiple switching units 70 each include a first valve EV1, a second valve EV2, a first refrigerant pipe P1, a third refrigerant pipe P3, a fourth refrigerant pipe P4, a gas piping 61 on the utilization side, and a liquid piping 62 on the utilization side. Each switching unit 70 adjusts the opening degree of the first valve EV1 and the second valve EV2, thereby switching the flow of refrigerant.

[0048] The switching unit 70 includes: a plurality of first branch pipes 71 branching from the first manifold 55; a plurality of second branch pipes 72 branching from the second manifold 56; and a plurality of third branch pipes 73 branching from the third manifold 57. The first branch pipes 71 are composed of a first refrigerant pipe P1, a third refrigerant pipe P3, and a utilization-side gas piping 61. The second branch pipes 72 are composed of a fourth refrigerant pipe P4 and a utilization-side gas piping 61. The third branch pipes 73 are composed of utilization-side liquid piping 62.

[0049] [The operation of the air conditioning system]

[0050] The following is for reference Figure 2 The following describes the following scenarios: cooling all operating indoor units 120 via the air conditioning system 100 (hereinafter also referred to as "full cooling operation"), heating all operating indoor units 120 via the air conditioning system 100 (hereinafter also referred to as "full heating operation"), and cooling some of the operating indoor units 120 while heating the rest (hereinafter also referred to as "mixed cooling and heating operation").

[0051] (Fully refrigerated operation)

[0052] During full cooling operation, the first valve EV1 of the switching unit 70 is set to fully open. The second valve EV2 is set to fully open. During the shutdown process, in the indoor unit 120, even if it is in full cooling operation, full heating operation, or mixed cooling and heating operation, the first valve EV1 corresponding to the indoor unit 120 is set to the minimum opening, and the second valve EV2 is set to fully closed.

[0053] When the compressor 25 is driven, the high-pressure gaseous refrigerant compressed by the compressor 25 flows into the outdoor heat exchanger 30 and condenses through the first flow path switching valve 26 and the third flow path switching valve 28. The refrigerant condensed in the outdoor heat exchanger 30 flows into the liquid connecting pipe 11 through the first outdoor expansion valve 34, the second outdoor expansion valve 35, the liquid side shut-off valve 23, etc.

[0054] The refrigerant flowing into the liquid connecting pipe 11 flows through the third manifold 57 of the refrigerant flow path switching device 130, and then through the liquid piping 62 on the utilization side of each switching unit 70 to flow into the indoor unit 120. The refrigerant flowing into the indoor unit 120 evaporates in the indoor heat exchanger 52 after being depressurized by the indoor expansion valve 51.

[0055] In the indoor unit 120, the refrigerant evaporated in the indoor heat exchanger 52 flows from the gas pipe GP into the utilization side gas pipe 61, mainly through the second valve EV2 and into the second manifold 56.

[0056] The refrigerant flowing into the second manifold 56 flows into the outdoor unit 110 via the intake gas connection pipe 12 and is drawn into the compressor 25.

[0057] The refrigerant flowing into the utilization side gas pipe 61 also passes through the first valve EV1 and flows into the first manifold 55. The refrigerant (low-pressure gas refrigerant) flowing into the first manifold 55 passes through the high and low pressure gas connecting pipe 13, and is drawn into the compressor 25 via the second flow path switching valve 27 and the storage tank 24.

[0058] (Regarding full heating operation)

[0059] During full heating operation, the first valve EV1 of the switching unit 70 is set to fully open, and the second valve EV2 is set to fully closed. When the compressor 25 is driven, the high-pressure gaseous refrigerant compressed by the compressor 25 flows into the high-low pressure gas connecting pipe 13 via the second flow path switching valve 27, etc. The refrigerant flowing into the high-low pressure gas connecting pipe 13 passes through the first manifold 55 of the refrigerant flow path switching device 130, 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 utilization side gas piping 61.

[0060] 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 in the liquid pipe LP, and flows into the third manifold 57 via the utilization side liquid piping 62 of the switching unit 70.

[0061] The refrigerant flowing into the third manifold 57 flows in the liquid connecting pipe 11 and into the outdoor unit 110, where it is depressurized in the first outdoor expansion valve 34 and the second outdoor expansion valve 35. The depressurized refrigerant evaporates as it passes through the outdoor heat exchanger 30 and is then drawn into the compressor 25 via the first flow path switching valve 26 and the third flow path switching valve 28.

[0062] (Regarding the combined operation of cooling and heating)

[0063] In the switching unit 70 (hereinafter also called the "cooling-side switching unit 70") corresponding to the indoor unit 120 that is operating and performing cooling (hereinafter also called the "cooling-side indoor unit 120"), the first valve EV1 is set to the minimum opening. The second valve EV2 is set to fully open.

[0064] In the switching unit 70 (hereinafter also referred to as the "heating-side switching unit 70") corresponding to the indoor unit 120 that is in operation and is in heating mode, the first valve EV1 is set to fully open. The second valve EV2 is set to fully closed.

[0065] When the compressor 25 is driven, a portion of the high-pressure gaseous refrigerant compressed by the compressor 25 flows into the high-low pressure gas connecting pipe 13 via the second flow path switching valve 27. Another 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 third flow path switching valve 28, and flows into the liquid connecting pipe 11 via the first outdoor expansion valve 34. 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.

[0066] The refrigerant flowing into the high and low pressure gas connecting pipe 13 flows into the first manifold 55 of the refrigerant flow path switching device 130, flows in the first refrigerant pipe P1, the first valve EV1, and the utilization side gas piping 61 of the heating side switching unit 70, and flows into the gas pipe GP.

[0067] 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 then flows from the liquid pipe LP through the utilization-side liquid piping 62 of the heating-side switching unit 70 into the third manifold 57.

[0068] The refrigerant flowing from the outdoor unit 110 into the liquid connecting pipe 11 also flows into the third manifold 57. The refrigerant flowing into the third manifold 57 flows into the cooling-side indoor unit 120 through the utilization-side liquid piping 62 and liquid pipe LP of the cooling-side switching unit 70.

[0069] The refrigerant flowing into the cooling-side indoor unit 120 is depressurized in the indoor expansion valve 51 and evaporates in the indoor heat exchanger 52 to cool the room.

[0070] After evaporation, the refrigerant flows through the gas pipe GP and into the utilization side gas pipe 61 of the refrigeration side switching unit 70. It then flows through the second valve EV2 into the fourth refrigerant pipe P4 and the second manifold 56, and flows in the suction gas connecting pipe 12 and is drawn into the compressor 25.

[0071] [Connection example of a refrigerant flow path switching device]

[0072] Figure 4 This is a piping system diagram showing an example of the connection of a refrigerant flow path switching device in an air conditioning system.

[0073] The air conditioning system 100 of this embodiment includes a first refrigerant flow path switching device group G1 and a second refrigerant flow path switching device group G2. The first refrigerant flow path switching device group G1 and the second refrigerant flow path switching device group G2 each include multiple (…). Figure 4 The middle section contains four refrigerant flow path switching devices 130.

[0074] The first refrigerant flow path switching device group G1 includes refrigerant flow path switching devices 130A, 130B, 130C, and 130D connected in series. The first manifolds 55, second manifolds 56, and third manifolds 57 of adjacent refrigerant flow path switching devices 130A and 130B, 130B and 130C, and 130C and 130D are respectively connected to each other via first connecting pipes (external pipes) 141, 142, and 143.

[0075] The upstream ends of the first manifold 55, the second manifold 56, and the third manifold 57 of the refrigerant flow path switching device 130A, located at the very upstream end, are respectively connected to one end of the first local piping (external piping) 151, 152, and 153. The other ends of the first local piping 151, 152, and 153 are respectively connected via the first branch piping (external piping) 161, 162, and 163 to the high and low pressure gas connecting pipe 13, the suction gas connecting pipe 12, and the liquid connecting pipe 11, which are external piping extending from the outdoor unit 110. Thus, the refrigerant flow path switching devices 130A to 130D are connected in series with respect to the outdoor unit 110.

[0076] The downstream ends of the first manifold 55, the second manifold 56, and the third manifold 57 of the refrigerant flow path switching device 130D located at the downstream end are connected to and blocked by blocking pipes 172, 173, and 173.

[0077] The second refrigerant flow path switching device group G2 includes, for example, refrigerant flow path switching devices 130E, 130F, and 130G connected in series; and a refrigerant flow path switching device 130H that branches off downstream of refrigerant flow path switching device 130E and is connected in parallel with refrigerant flow path switching device 130F.

[0078] Adjacent refrigerant flow path switching devices 130E and 130F, 130F and 130G in one direction, their respective first manifolds 55, second manifolds 56, and third manifolds 57 are interconnected via second connecting pipes (external pipes) 144, 145, and 146.

[0079] The upstream ends of the first manifold 55, the second manifold 56, and the third manifold 57 of the refrigerant flow path switching device 130E, located at one end of the arrangement direction, are respectively connected to one end of the second local piping (external piping) 154, 155, and 156. The other ends of the second local piping 154, 155, and 156 are respectively connected to the high and low pressure gas connecting pipe 13, the suction gas connecting pipe 12, and the liquid connecting pipe 11 extending from the outdoor unit 110 via the first branch pipes 161, 162, and 163. Thus, the refrigerant flow path switching devices 130E to 130G are connected in series with respect to the outdoor unit 110.

[0080] The upstream ends of the first manifold 55, second manifold 56, and third manifold 57 of the refrigerant flow path switching device 130H, which are arranged separately from the arrangement direction, are respectively connected to one end of a third local piping (external piping) 157, 158, and 159. The other ends of the third local piping 157, 158, and 159 are connected to second branch piping (external piping) 164, 165, and 166, which are located at the center of the second local piping 154, 155, and 156 along the length direction between the refrigerant flow path switching device 130E and the refrigerant flow path switching device 130F. Thus, the refrigerant flow path switching devices 130E and 130H are connected in series with respect to the outdoor unit 110.

[0081] The downstream ends of the first manifold 55, the second manifold 56, and the third manifold 57 of the refrigerant flow path switching device 130G and the refrigerant flow path switching device 130H, which are located at the downstream end, are connected to the blocking pipes 172, 173, and 173 and are blocked.

[0082] [Piping length setting]

[0083] (First refrigerant flow path switching device group)

[0084] Figure 5This is a piping system diagram illustrating the piping length of the air conditioning system. Piping length refers to the total length of the external piping from the outdoor unit 110 through the refrigerant flow path switching device 130 to the indoor unit 120. For example... Figure 4 and Figure 5 As shown, in the refrigerant flow path switching devices 130A to 130D connected in series in the first refrigerant flow path switching device group G1, the maximum piping length L1 is the piping length from the outdoor unit 110 through the high and low pressure gas connecting pipe 13 to the indoor unit 120 connected to each refrigerant flow path switching device 130A to 130D. The maximum piping length L1 can be calculated by the following formula (1).

[0085] L1=L11+L12+(L13×3)···(1)

[0086] L11 is the length of the high-low pressure gas connecting pipe 13. L12 is the length of the first local piping 151. L13 is the length of the first connecting piping 141.

[0087] The maximum piping length L2 of the refrigerant flow path switching devices 130A to 130D connected in series, from the outdoor unit 110 through the suction gas connecting pipe 12 to the indoor unit 120 connected to each refrigerant flow path switching device 130A to 130D, is the piping length from the outdoor unit 110 through the suction gas connecting pipe 12 to each indoor unit 120 connected to the refrigerant flow path switching device 130D located at the downstream end. The maximum piping length L2 can be calculated by the following formula (2).

[0088] L2=L21+L22+(L23×3)···(2)

[0089] L21 is the length of the intake gas connecting pipe 12. L22 is the length of the first local piping 152. L23 is the length of the first connecting piping 142.

[0090] The maximum piping length L3 of the refrigerant flow path switching devices 130A to 130D connected in series, from the outdoor unit 110 through the liquid connecting pipe 11 to the indoor unit 120 connected to each refrigerant flow path switching device 130A to 130D, is the piping length from the outdoor unit 110 through the liquid connecting pipe 11 to each indoor unit 120 connected to the refrigerant flow path switching device 130D located at the downstream end. The maximum piping length L3 can be calculated by the following formula (3).

[0091] L3=L31+L32+(L33×3)···(3)

[0092] L31 is the length of the liquid connecting pipe 11. L32 is the length of the first local piping 153. L33 is the length of the first connecting piping 143.

[0093] The maximum piping lengths L1, L2, and L3 are set to be below the specified upper limit. At this time, considering the first branch piping 161, 162, and 163 between the outdoor unit 110 and each indoor unit 120 connected to the refrigerant flow path switching device 130D, and each manifold 55, 56, and 57 of the refrigerant flow path switching devices 130A to 130D, the maximum piping lengths L1, L2, and L3 are set in accordance with the following formulas (4), (5), and (6).

[0094] L1+J11+Ka+Kb+Kc+Kd+Md≤Lu···(4)

[0095] L2+J12+Ka+Kb+Kc+Kd+Md≤Lu···(5)

[0096] L3+J13+Ka+Kb+Kc+Kd+Md≤Lu···(6)

[0097] J11, J12, and J13 are the corrected lengths determined taking into account the first branch pipes 161, 162, and 163 configured between the outdoor unit 110 and the refrigerant flow path switching device 130D. In this embodiment, J11, J12, and J13 are determined to be fixed values ​​(e.g., 0.5m) taking into account the pressure loss of each of the first branch pipes 161, 162, and 163.

[0098] Lu is a value determined by specifications, etc., and is the upper limit (upper limit value) of the maximum piping length from the outdoor unit 110 to the indoor unit 120 connected to the refrigerant flow path switching device 130 located in series. For example, Lu is set to 120m.

[0099] Ka is a shared value for the lengths of the first manifold 55, the second manifold 56, and the third manifold 57, which are respectively used as refrigerant flow path switching devices 130A. Ka is determined taking into account the pressure losses of the aforementioned manifolds 55 to 57. Specifically, Ka is set as a first value determined based on the sum of the capacities of the plurality of indoor units 120 connected to the refrigerant flow path switching devices 130A and the refrigerant flow path switching devices 130B, 130C, and 130D located downstream of it.

[0100] Kb is a shared value representing the lengths of the first manifold 55, the second manifold 56, and the third manifold 57, which are respectively used as refrigerant flow path switching devices 130B. Kb is determined taking into account the pressure losses of the aforementioned manifolds 55 to 57. Specifically, Kb is set as a first value determined based on the sum of the capacities of the plurality of indoor units 120 connected to the refrigerant flow path switching devices 130B and the refrigerant flow path switching devices 130C and 130D located downstream of it.

[0101] Kc is a shared value for the lengths of the first manifold 55, the second manifold 56, and the third manifold 57, which are respectively used as refrigerant flow path switching devices 130C. Kc is determined taking into account the pressure loss of the aforementioned manifolds 55 to 57. Specifically, Kc is set as a first value determined based on the sum of the capacities of the plurality of indoor units 120 connected to the refrigerant flow path switching device 130C and the refrigerant flow path switching device 130D located downstream of it.

[0102] Kd is a shared value for the lengths of the first manifold 55, the second manifold 56, and the third manifold 57, which are respectively used as the refrigerant flow path switching device 130D. Kb is determined taking into account the pressure loss of the aforementioned manifolds 55 to 57. Specifically, Kd is set as a first value determined based on the sum of the capacities of the multiple indoor units 120 connected to the refrigerant flow path switching device 130D.

[0103] Md is a shared value for the lengths of the first branch pipe 71, the second branch pipe 72, and the third branch pipe 73, which are respectively used as the refrigerant flow path switching device 130D. Md is set as a second value that is fixed (e.g., 4.3m) taking into account the pressure loss of the aforementioned branch pipes 71 to 73.

[0104] Figure 6 This is a table that illustrates the first value corresponding to the sum of the capabilities of multiple indoor units. Figure 6 In this context, the capacity of indoor unit 120 is used as the basis for determining the overall capacity (capacity) of indoor unit 120. The smaller the sum of the capacities (capabilities) of indoor unit 120, the smaller the first value represents. Based on Figure 6 The table is used to determine the first values ​​Ka, Kb, Kc, and Kd. In addition, as a capability of the indoor unit 120, besides the capacity of the indoor unit 120, the power consumption of the indoor unit 120 can also be used.

[0105] In this embodiment, among the refrigerant flow path switching devices 130A to 130D connected in series in the first refrigerant flow path switching device group G1, the refrigerant flow path switching device located further downstream has a smaller total capacity of the indoor unit 120 connected to this device and the refrigerant flow path switching device located downstream of it. Therefore, the first values ​​Ka, Kb, Kc, and Kd corresponding to the refrigerant flow path switching devices 130A to 130D are determined to be values ​​that gradually decrease in sequence.

[0106] For example, when the capacity of each indoor unit 120 connected to the refrigerant flow path switching device 130A to 130C is set to 3.5 kW, and the capacity of each indoor unit 120 connected to the refrigerant flow path switching device 130D is set to 7.0 kW, the first values ​​Ka, Kb, Kc, and Kd corresponding to the refrigerant flow path switching devices 130A to 130D are determined as follows.

[0107] The first value Ka corresponding to the refrigerant flow path switching device 130A is determined to be a value corresponding to the sum of the capacities of the sixteen indoor units 120 connected to the refrigerant flow path switching devices 130A to 130D. The sum of the aforementioned capacities, 70.0 kW (=3.5×12+7.0×4), is... Figure 6 The table meets the criteria of "above 67.4 and less than 85.0", therefore the first value Ka is determined to be 4.3m.

[0108] The first value Kb corresponding to the refrigerant flow path switching device 130B is determined to be a value corresponding to the sum of the capacities of the twelve indoor units 120 connected to the refrigerant flow path switching devices 130B to 130D. The sum of the aforementioned capacities, 56.0 kW (=3.5×8+7.0×4), is... Figure 6 The table meets the criteria of "above 47.5 and less than 67.4", therefore the first value Kb is determined to be 2.2m.

[0109] The first value Kc corresponding to the refrigerant flow path switching device 130C is determined to be a value corresponding to the sum of the capacities of the eight indoor units 120 connected to the refrigerant flow path switching devices 130C to 130D. The sum of the aforementioned capacities, 42.0 kW (=3.5×4+7.0×4), is... Figure 6 The table meets the criteria of "above 32.5 and less than 47.5", therefore the first value Kc is determined to be 1.6m.

[0110] The first value Kd corresponding to the refrigerant flow path switching device 130D is determined to be a value corresponding to the sum of the capacities of the four indoor units 120 connected to the refrigerant flow path switching device 130D. As the sum of the aforementioned capacities, 28.0 kW (=7.0 × 4), in Figure 6The table meets the criteria of "above 21.0 and less than 32.5", therefore the first value Kd is determined to be 0.7m.

[0111] (Second refrigerant flow path switching device group)

[0112] like Figure 4 and Figure 5 As shown, in the refrigerant flow path switching devices 130E to 130G connected in series in the second refrigerant flow path switching device group G2, the maximum piping lengths L4, L5, and L6 from the outdoor unit 110 through the high and low pressure gas connecting pipe 13, the suction gas connecting pipe 12, and the liquid connecting pipe 11 to each indoor unit 120 connected to the refrigerant flow path switching device 130G located at the downstream side are set using the same calculation formula as the aforementioned maximum piping lengths L1, L2, and L3.

[0113] In the refrigerant flow path switching devices 130E and 130H connected in series in the second refrigerant flow path switching device group G2, the piping lengths from the outdoor unit 110 through the high and low pressure gas connecting pipe 13, the suction gas connecting pipe 12, and the liquid connecting pipe 11 to each indoor unit 120 connected to the refrigerant flow path switching device 130H located at the downstream side, i.e., the maximum piping lengths L7, L8, and L9, are also set using the same calculation formula as the aforementioned maximum piping lengths L1, L2, and L3.

[0114] However, when setting the maximum piping lengths L4 to L9, the first value Ke of the lengths of each manifold 55, 56, and 57 used as the refrigerant flow path switching device 130E is determined based on the sum of the capacities of the multiple indoor units 120 that are respectively connected to the refrigerant flow path switching device 130E and all refrigerant flow path switching devices 130F, 130G, and 130H located downstream of it.

[0115] [Setting the pipe diameter for connecting piping]

[0116] (First refrigerant flow path switching device group)

[0117] like Figure 4 and Figure 5 As shown, in the first refrigerant flow path switching device group G1, the diameter of each of the first connecting pipes 141, 142, and 143, which connect the refrigerant flow path switching devices 130A to 130D in series, is set according to the sum of the capacities of the multiple indoor units 120 connected to the refrigerant flow path switching device 130 located further downstream than the first connecting pipes 141, 142, and 143.

[0118] Specifically, the pipe diameters d11, d12, and d13 of the first connecting pipes 141, 142, and 143 that connect adjacent refrigerant flow path switching devices 130A and 130B to each other are set based on the sum of the capacities of multiple indoor units 120 that are connected to refrigerant flow path switching devices 130B, 130C, and 130D located further downstream than the first connecting pipes 141, 142, and 143.

[0119] The pipe diameters d14, d15, and d16 of the first connecting pipes 141, 142, and 143 that connect adjacent refrigerant flow path switching devices 130B and 130C to each other are set based on the sum of the capacities of multiple indoor units 120 that are respectively connected to refrigerant flow path switching devices 130C and 130D located further downstream than the first connecting pipes 141, 142, and 143.

[0120] The pipe diameters d17, d18, and d19 of the first connecting pipes 141, 142, and 143 that connect adjacent refrigerant flow path switching devices 130C and 130D to each other are set based on the sum of the capacities of multiple indoor units 120 connected to the refrigerant flow path switching device 130D located further downstream than the first connecting pipes 141, 142, and 143.

[0121] In this embodiment, when determining the pipe diameters d11 to d13, d14 to d16, and d17 to d19 respectively, the capacity of the indoor unit 120 is used, for example, as the capacity of the indoor unit 120. The smaller the sum of the capacities (capabilities) of the indoor units 120, the smaller the values ​​of the pipe diameters d11 to d13, d14 to d16, and d17 to d19 are determined. In addition to the capacity of the indoor unit 120, the power consumption of the indoor unit 120 can also be used as the capacity.

[0122] In the refrigerant flow path switching devices 130A to 130D connected in series, the refrigerant flow path switching device located further downstream has a smaller total capacity of the indoor units 120 connected to this device and the refrigerant flow path switching devices located downstream of it. Therefore, the pipe diameters d14 to d16 are determined to be smaller values ​​compared to the pipe diameters d11 to d13, and the pipe diameters d17 to d19 are determined to be smaller values ​​compared to the pipe diameters d14 to d16.

[0123] (Second refrigerant flow path switching device group)

[0124] In the second refrigerant flow path switching device group G2, the pipe diameters d21 to d23 and d24 to d26 of the second connecting pipes 144, 145, and 146, which are connected in series with the refrigerant flow path switching devices 130E to 130G, are set in the same way as the pipe diameters d11 to d13, d14 to d16, and d17 to d19 mentioned above.

[0125] [Effects of the Implementation Method]

[0126] According to the air conditioning system 1 of this embodiment, by subtracting the first values ​​Ka to Kd from the upper limit length Lu value using the above formulas (4) to (6), the maximum piping lengths L1 to L3 corresponding to the multiple refrigerant flow path switching devices 130A to 130D connected in series can be obtained. The first values ​​Ka, Kb, Kc, and Kd are determined based on the sum of the capacities of the indoor units 120 connected to the corresponding refrigerant flow path switching devices 130A, 130B, 130C, 130D and the refrigerant flow path switching devices 130B to 130D, 130C to 130D, 130D located downstream of them. Therefore, the first values ​​Ka, Kb, Kc, and Kd are determined to be more appropriate piping lengths, thereby increasing the maximum piping lengths L1 to L3 compared to the case where the first values ​​are set as fixed values ​​that are permissible even if the capacity of the downstream connected indoor units is at its maximum.

[0127] The maximum piping lengths L4 to L6 corresponding to the multiple refrigerant flow path switching devices 130E to 130G connected in series, and the maximum piping lengths L7 to L9 corresponding to the multiple refrigerant flow path switching devices 130E and 130H connected in series, can also be lengthened in the same way as the maximum piping lengths L1 to L3.

[0128] As shown in equations (4) to (6) above, the maximum piping lengths L1 to L3 corresponding to the multiple refrigerant flow path switching devices 130A to 130D connected in series are set to a value below the upper limit Lu after adding correction lengths J11 to J13 to the maximum piping lengths L1 to L3. The correction lengths J11 to J13 take into account the pressure loss of the first branch piping 161 to 163. Thus, the maximum piping lengths L1 to L3 can be set to appropriate values.

[0129] The maximum piping lengths L4 to L6 corresponding to the multiple refrigerant flow path switching devices 130E to 130G connected in series, and the maximum piping lengths L7 to L9 corresponding to the multiple refrigerant flow path switching devices 130E and 130H connected in series, can also be set to appropriate values ​​in the same way as the maximum piping lengths L1 to L3.

[0130] In the series-connected refrigerant flow path switching devices 130A to 130D, the pipe diameters d11 to d13, d14 to d16, and d17 to d19 of the first connecting pipes 141 to 143 that connect adjacent refrigerant flow path switching devices 130 to each other are set based on the sum of the capacities of the indoor units 120 connected to the refrigerant flow path switching devices 130 located further downstream than the first connecting pipes 141 to 143. Therefore, the pipe diameters d11 to d13, d14 to d16, and d17 to d19 of the first connecting pipes 141 to 143 can be set to appropriate values. As a result, it can suppress the inability of oil to return during oil return operation caused by excessively large pipe diameters d11~d13, d14~d16, d17~d19, and the increased pressure loss caused by excessively small pipe diameters d11~d13, d14~d16, d17~d19.

[0131] The pipe diameters d21-d23 and d24-d26 of the second connecting pipes 144-146 are the same as those of the pipe diameters d11-d13 of the first connecting pipes 141-143, which can suppress the inability of oil to return and the increase of pressure loss during oil return operation.

[0132] [Another connection example of a refrigerant flow path switching device]

[0133] Figure 7 This is a piping system diagram showing another connection example of a refrigerant flow path switching device in an air conditioning system.

[0134] Figure 7 In the air conditioning system 100, a refrigerant flow path switching device 130 (hereinafter referred to as "refrigerant flow path switching device 130I") is connected to the outdoor unit 110.

[0135] The upstream ends of the first manifold 55, the second manifold 56, and the third manifold 57 of the refrigerant flow path switching device 130I are respectively connected to one end of the fourth local piping (external piping) 181, 182, and 183. The other ends of the fourth local piping 181, 182, and 183 are directly connected to the high and low pressure gas connecting pipe 13, the suction gas connecting pipe 12, and the liquid connecting pipe 11 extending from the outdoor unit 110, respectively. The downstream ends of the first manifold 55, the second manifold 56, and the third manifold 57 of the refrigerant flow path switching device 130I are connected to and blocked by sealing piping 172, 173, and 173.

[0136] The piping length L110 from the outdoor unit 110 through the high and low pressure gas connecting pipe 13 to each indoor unit 120 connected to the refrigerant flow path switching device 130I can be calculated by the following formula (7).

[0137] L110=L11+L111 ···(7)

[0138] L11 is the length of the high and low pressure gas connecting pipe 13. L111 is the length of the fourth local piping 181.

[0139] The piping length L120 from the outdoor unit 110 through the intake gas connecting pipe 12 to each indoor unit 120 connected to the refrigerant flow path switching device 130I can be calculated by the following formula (8).

[0140] L120=L21+L121 ···(8)

[0141] L21 is the length of the intake gas connecting pipe 12. L121 is the length of the fourth local piping 182.

[0142] The piping length L130 from the outdoor unit 110 through the liquid connecting pipe 11 to each indoor unit 120 connected to the refrigerant flow path switching device 130I can be calculated by the following formula (9).

[0143] L130=L31+L131 ···(9)

[0144] L31 is the length of liquid connecting pipe 11. L131 is the length of fourth local piping 183.

[0145] The lengths of each pipe, L110, L120, and L130, are set to be below the upper limit value Lu. At this time, considering the manifolds 55, 56, and 57 of the refrigerant flow path switching device 130I, the lengths of each pipe, L110, L120, and L130, are set to satisfy the following equations (10), (11), and (12), respectively.

[0146] L110+Ki+Mi≤Lu ···(10)

[0147] L120+Ki+Mi≤Lu ···(11)

[0148] L130+Ki+Mi≤Lu ···(12)

[0149] Ki is a shared value for the lengths of the first manifold 55, the second manifold 56, and the third manifold 57, which are respectively used as the refrigerant flow path switching device 130I. Ki is determined taking into account the pressure loss of the aforementioned manifolds 55 to 57. Specifically, Ki is set as a first value determined based on the sum of the capacities of the plurality of indoor units 120 connected to the refrigerant flow path switching device 130I.

[0150] Mi is a shared value for the lengths of the first branch pipe 71, the second branch pipe 72, and the third branch pipe 73, which are respectively used as the refrigerant flow path switching device 130I. Mi is set as a second value that is fixed (e.g., 4.3m) taking into account the pressure loss of the aforementioned branch pipes 71 to 73.

[0151] based on Figure 6 The table is used to determine the first value Ki. For example, when the capacity of each indoor unit 120 connected to the refrigerant flow path switching device 130I is set to 3.5 kW, the first value Ki is determined to be a value corresponding to the sum of the capacities of the four indoor units 120. As the sum of the aforementioned capacities, 14.0 kW (=3.5×4), in Figure 6 The table meets the condition of "less than 21.0", therefore the first value Ki is determined to be 0.4m.

[0152] according to Figure 7 In the air conditioning system 1, by subtracting the first value Ki from the upper limit length Lu value using the above formulas (10) to (12), the pipe lengths L110, L120, and L130 corresponding to the refrigerant flow path switching device 130I can be determined. Therefore, the first value Ki can be set to be smaller as the sum of the capacities of the indoor units 120 connected to the refrigerant flow path switching device 130I is smaller. Thus, the pipe lengths L110, L120, and L130 can be lengthened accordingly to the amount by which the first value Ki decreases.

[0153] [Other variations]

[0154] This disclosure is not limited to the foregoing embodiments, and various modifications can be made within the scope of the claims.

[0155] For example, Figure 4 The air conditioning system 100 includes two refrigerant flow path switching device groups G1 and G2, but may also include three or more refrigerant flow path switching device groups.

[0156] Figure 4 and Figure 5 In the piping system, the maximum piping length is set such that the value obtained by adding a first value, a second value, and the correction length of branch pipes 161 to 166 to the maximum piping length is below the upper limit value. However, it is sufficient to set the maximum piping length such that the value obtained by adding the first value to the maximum piping length is below the upper limit value. Similarly, in Figure 7 In the piping system, the piping length is set such that the value after adding a first value and a second value to the piping length is below the upper limit value. However, it is sufficient to set the piping length such that the value after adding the first value to the piping length is below the upper limit value.

[0157] Figure 4 and Figure 5 In the piping system, the first value corresponding to the refrigerant piping (manifolds 55-57) of the refrigerant flow path switching device 130 is determined based on the sum of the capacities of all indoor units 120 connected to all refrigerant flow path switching devices 130 located downstream of the refrigerant flow path switching device 130, but it can also be determined based on the sum of the capacities of indoor units 120 connected to a portion of the refrigerant flow path switching devices 130 located downstream of the aforementioned device.

[0158] Symbol Explanation

[0159] 1. Air conditioning system

[0160] 11. Liquid connecting pipe (external piping)

[0161] 12. Inhalation gas connecting pipe (external piping)

[0162] 13 High and low pressure gas connecting pipes (external piping)

[0163] 110 Outdoor Unit

[0164] 120 indoor units

[0165] 130 Refrigerant Flow Path Switching Device

[0166] 141-143 First connecting piping (external piping)

[0167] 144-146 Second connecting piping (external piping)

[0168] 151-153 First local piping (external piping)

[0169] 154-156 Second local piping (external piping)

[0170] 157-159 Third local piping (external piping)

[0171] 161-163 First branch piping (external piping, branch piping)

[0172] 164-166 Second branch piping (external piping, branch piping)

[0173] 181-183 Fourth local piping (external piping)

[0174] d11~d19, d21~d26 piping diameter

[0175] J11~J13, J21~J23 Correction Length

[0176] Ka~Ki, Ke first value

[0177] Maximum piping lengths from L1 to L9

[0178] L110, L120, L130 piping length

[0179] Lu upper limit length (maximum value).

Claims

1. An air conditioning system, include: Outdoor unit (110); multiple indoor units (120); And at least one refrigerant flow path switching device (130), said refrigerant flow path switching device (130) switching the refrigerant flow path between the outdoor unit (110) and the plurality of indoor units (120), characterized in that, The piping length is set in such a way that the value after adding at least a first value to the piping length is below a predetermined upper limit value. The piping length is the sum of the lengths of the external piping (11-13, 141-146, 151-159, 161-166, 181-183) from the outdoor unit (110) through the refrigerant flow path switching device (130) to the indoor unit (120). The first value is determined based on the total capacity of the indoor unit (120) connected to the refrigerant flow path switching device (130).

2. The air conditioning system according to claim 1, characterized in that, Includes multiple refrigerant flow path switching devices (130) connected in series. The first value corresponding to each of the refrigerant flow path switching devices (130) is determined based on the sum of the capacities of the indoor units (120) connected to the refrigerant flow path switching device (130) and the refrigerant flow path switching devices (130) located downstream of the refrigerant flow path switching device (130). The piping length is the sum of the lengths of the external piping (11-13, 141-146, 151-159, 161-166) from the outdoor unit (110) to the indoor unit (120) connected to the refrigerant flow path switching device (130) located at the downstream end, which is the maximum piping length. The upper limit value is the upper limit of the maximum piping length. The maximum piping length is set in such a way that the value after adding at least the first value corresponding to the plurality of refrigerant flow path switching devices (130) to the maximum piping length reaches below the upper limit length.

3. The air conditioning system according to claim 1 or 2, characterized in that, The pipe length is set in such a way that the value of the pipe length, after taking into account the corrected length of the branch pipes (161-166) configured between the outdoor unit (110) and the indoor unit (120), is below the upper limit value.

4. The air conditioning system according to claim 1 or 2, characterized in that, Includes multiple refrigerant flow path switching devices (130) connected in series. The external piping (11-13, 141-146, 151-159, 161-166, 181-183) has connecting piping (141-146) that connects adjacent refrigerant flow path switching devices (130) to each other. The diameter of the connecting pipes (141-146) is set based on the total capacity of the indoor unit (120) connected to the refrigerant flow path switching device (130) located downstream of the connecting pipes (141-146).

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