Heat source unit and air conditioner

Abstract

Provided is a heat source unit for an air-conditioning device, which suppresses pressure abnormalities in a refrigerant flow path due to the fact that a filled carbon dioxide refrigerant reaches a supercritical state. The heat source unit and the utilization unit are connected to form an air-conditioning device. The heat source unit includes a compressor, a heat source heat exchanger, a first shut-off valve, a second shut-off valve, a refrigerant flow path, and a refrigerant. The refrigerant flow path is a flow path in which the compressor, the heat source heat exchanger, the first shut-off valve, and the second shut-off valve are connected by refrigerant piping. The refrigerant is filled in the refrigerant flow path. The refrigerant is carbon dioxide. The filling amount V1 (kg) of the refrigerant filled in the refrigerant flow path, the volume V2 (L) of the refrigerant flow path, and the design pressure P (MPa) of the refrigerant flow path satisfy the following relationships: V1 * a < = V2 < = V1 * b, a = 0.078 * P2-2.111 * P + 15.771, and b = 0.055 * P2-1.768 * P + 16.144.

Description

Technical Field

[0001] The invention relates to a heat source unit and an air conditioning device. Background Art

[0002] An air conditioner using carbon dioxide as a refrigerant is known. Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-045769) discloses a method for charging a carbon dioxide refrigerant for the purpose of improving the efficiency of the installation work of an air conditioner.

[0003] In order to further improve the efficiency of the installation work of the air conditioner, the following technology is known: the refrigerant is pre-filled into the heat source unit (outdoor unit) at the manufacturing plant, and the heat source unit is connected to the utilization unit (indoor unit) at the installation site to fill the refrigerant into the refrigerant circuit. Summary of the invention Technical problem to be solved by the invention

[0004] When carbon dioxide is used as the refrigerant pre-filled in the outdoor unit, the refrigerant in the refrigerant flow path may become supercritical due to the increase in the outside air temperature. The pressure of the supercritical refrigerant increases rapidly, so pressure abnormality may occur in the refrigerant flow path.

[0005] The present disclosure provides a heat source unit for an air-conditioning device, which suppresses pressure abnormality in a refrigerant flow path caused by supercriticality of a filled carbon dioxide refrigerant. Technical solutions adopted to solve technical problems

[0006] The heat source unit of the first viewpoint is connected to the utilization unit to form an air conditioning device. The heat source unit includes a compressor, a heat source heat exchanger, a first stop valve, a second stop valve, a refrigerant flow path, and a refrigerant. The refrigerant flow path is a flow path formed by connecting the compressor, the heat source heat exchanger, the first stop valve, and the second stop valve through a refrigerant pipe. The refrigerant is filled in the refrigerant flow path. The refrigerant is carbon dioxide.

[0007] The amount of refrigerant filled in the refrigerant flow path V1 (kg), the volume of the refrigerant flow path V2 (L), and the design pressure P (MPa) of the refrigerant flow path satisfy the following relationship: V1×a≤V2≤V1×b a=0.078×P 2 -2.111×P+15.771 b=0.055×P 2 -1.768×P+16.144.

[0008] According to the heat source unit, the occurrence of abnormal pressure in the refrigerant flow path due to the filled carbon dioxide refrigerant becoming supercritical is suppressed.

[0009] The heat source unit according to the second aspect is the heat source unit according to the first aspect, wherein the design pressure P is 10 MPa or more and 14 MPa or less.

[0010] A heat source unit according to a third aspect is the heat source unit according to the first aspect or the second aspect, further comprising a refrigerant storage container for storing a refrigerant.

[0011] The volume V3 (L) of the refrigerant storage container satisfies the following relationship: 0.4×V2≤V3<0.9×V2.

[0012] The heat source unit can store the refrigerant not only in the refrigerant flow path but also in the refrigerant storage container in the refrigerant flow path. Therefore, the volume V2 can be sufficiently ensured to effectively suppress the occurrence of pressure abnormality in the refrigerant flow path.

[0013] The heat source unit of the fourth aspect is a heat source unit according to any one of the first to third aspects, and further includes a flow path switching mechanism and a refrigerant storage container. The flow path switching mechanism switches the direction of the refrigerant flow in the refrigerant flow path. The refrigerant storage container is a container for storing the refrigerant.

[0014] The refrigerant storage container can store not only the charged refrigerant but also the excess refrigerant generated due to the change of the operation load between the cooling operation and the heating operation.

[0015] The air conditioning device of the fifth aspect includes a heat source unit and a utilization unit according to any one of the first to fourth aspects. The utilization unit is connected to the heat source unit via a connecting pipe. The connecting pipe changes its length according to the installation positions of the heat source unit and the utilization unit, and has a first length that does not require additional refrigerant to be filled into the refrigerant circuit, and the refrigerant circuit is formed by connecting the heat source unit and the utilization unit via the connecting pipe. The heat source unit is filled with a refrigerant in an amount corresponding to the required refrigerant amount in the refrigerant circuit when the connecting pipe is the first length.

[0016] The air conditioning device of the sixth aspect includes a heat source unit and a utilization unit according to any one of the first to fourth aspects. The utilization unit is connected to the heat source unit via a connecting pipe. The length of the connecting pipe is changed according to the installation positions of the heat source unit and the utilization unit. The amount of refrigerant filled in the refrigerant flow path of the heat source unit is greater than the required amount of refrigerant in the refrigerant circuit when the connecting pipe is shorter than a predetermined first length, and the refrigerant circuit is formed by connecting the heat source unit and the utilization unit via the connecting pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic configuration diagram of an air-conditioning apparatus 1 including a heat source unit 2 according to the first embodiment. Figure 2 It is the Mollier line diagram of R32. Figure 3 It is the Mollier diagram for carbon dioxide. Figure 4 It is a schematic configuration diagram of an air-conditioning apparatus 1 a including a heat source unit 2 a according to the second embodiment. DETAILED DESCRIPTION

[0018] <First embodiment> (1) Overall structure Figure 1 This is a schematic structural diagram of an air-conditioning device 1 including a heat source unit 2 according to a first embodiment. The air-conditioning device 1 performs a vapor compression refrigeration cycle operation, thereby executing air-conditioning operation (cooling operation and heating operation) in an air-conditioned space such as an indoor space (not shown). The air-conditioning device 1 includes a heat source unit 2, a utilization unit 3, and a first connecting pipe 6 and a second connecting pipe 7 connecting the heat source unit 2 and the utilization unit 3. The heat source unit 2, the utilization unit 3, the connecting pipes 6 and 7 connected to each other constitute a refrigerant circuit 10. The refrigerant filled in the refrigerant circuit 10 is carbon dioxide. In addition, hereinafter, the first connecting pipe 6 and the second connecting pipe 7 are also collectively referred to as connecting pipes 6 and 7.

[0019] The details will be described later, and the refrigerant filled in the refrigerant circuit 10 is filled in the heat source unit 2 at a manufacturing plant, etc. At the installation site of the air-conditioning device 1, etc., the heat source unit 2 and the utilization unit 3 are connected via the connecting pipes 6 and 7, so that the refrigerant filled in the heat source unit 2 is filled in the refrigerant circuit 10.

[0020] (2) Detailed structure (2-1) Utilization Unit The usage unit 3 is installed in the air-conditioned space. The usage unit 3 includes a usage-side refrigerant flow path 30 constituting a part of the refrigerant circuit 10. The usage-side refrigerant flow path 30 includes a usage-side heat exchanger 31.

[0021] (2-1-1) Utilization side heat exchanger The use-side heat exchanger 31 exchanges heat between the refrigerant flowing therein and the air in the air-conditioned space. One end of the use-side heat exchanger 31 is connected to the first connecting pipe 6 via the refrigerant pipe 30a. The other end of the use-side heat exchanger 31 is connected to the second connecting pipe 7 via the refrigerant pipe 30a.

[0022] (2-2) Heat source unit The heat source unit 2 is arranged outside the air-conditioning target space (outdoors, etc.). The heat source unit 2 has a heat source refrigerant flow path 20 constituting a part of the refrigerant circuit 10. The heat source refrigerant flow path 20 includes a compressor 21, a flow path switching mechanism 22, a heat source heat exchanger 23, a heat source expansion mechanism 24, a first stop valve 25, a second stop valve 26, and an accumulator 27. The compressor 21, the flow path switching mechanism 22, the heat source heat exchanger 23, the heat source expansion mechanism 24, the first stop valve 25, the second stop valve 26, and the accumulator 27 are connected to each other via a refrigerant pipe 20a. The heat source refrigerant flow path 20 is an example of a refrigerant flow path.

[0023] (2-2-1) Compressor The compressor 21 sucks the low-pressure refrigerant in the refrigeration cycle from the suction pipe 21a, compresses the refrigerant through a compression mechanism (not shown), and discharges the compressed refrigerant as a high-pressure refrigerant to the discharge pipe 21b. In the present embodiment, the heat source unit 2 has only one compressor 21, but the number of compressors 21 is not limited to one, and may be multiple. The start, stop, and capacity control of the compressor 21 can be performed by a control unit not shown.

[0024] (2-2-2) Flow path switching mechanism The flow switching mechanism 22 switches the flow direction of the refrigerant, thereby changing the state of the refrigerant circuit 10 between the first state and the second state. When the refrigerant circuit 10 is in the first state, the heat source heat exchanger 23 functions as a radiator of the refrigerant, and the use-side heat exchanger 31 functions as an evaporator of the refrigerant. When the refrigerant circuit 10 is in the second state, the heat source heat exchanger 23 functions as an evaporator of the refrigerant, and the use-side heat exchanger 31 functions as a radiator of the refrigerant. The change of the state of the flow switching mechanism 22 can be performed by a control unit (not shown).

[0025] In the present embodiment, the flow path switching mechanism 22 is a four-way reversing valve having four ports P1, P2, P3, and P4. Port P1 is connected to one end of the heat source heat exchanger 23. Port P2 is connected to the discharge pipe 21b of the compressor 21. Port P3 is connected to the storage tank 27. Port P4 is connected to the second stop valve 26. In the first state, port P1 is connected to port P2, and port P3 is connected to port P4. In the second state, port P1 is connected to port P3, and port P2 is connected to port P4.

[0026] The flow path switching mechanism 22 is not limited to the four-way switching valve. For example, the flow path switching mechanism 22 may be configured by combining a plurality of electromagnetic valves and refrigerant pipes so as to switch the flow direction of the refrigerant as described above.

[0027] (2-2-3) Heat source heat exchanger The heat source heat exchanger 23 exchanges heat between the refrigerant flowing therein and the air (heat source air) at the installation location of the heat source unit 2. One end of the heat source heat exchanger 23 is connected to the port P1 of the flow path switching mechanism 22. The other end of the heat source heat exchanger 23 is connected to the heat source expansion mechanism 24.

[0028] (2-2-4) Heat source expansion mechanism The heat source expansion mechanism 24 is controlled by opening to adjust the flow rate of the refrigerant flowing in the heat source refrigerant flow path 20 and reduce the pressure of the refrigerant. One end of the heat source expansion mechanism 24 is connected to the heat source heat exchanger 23. The other end of the heat source expansion mechanism 24 is connected to the first stop valve 25. The opening of the heat source expansion mechanism 24 can be controlled by a control unit (not shown).

[0029] (2-2-5) First stop valve and second stop valve The first stop valve 25 is a valve provided at the connection portion between the heat source refrigerant flow path 20 and the first connecting pipe 6. By closing the first stop valve 25, the flow of the refrigerant between the heat source refrigerant flow path 20 and the first connecting pipe 6 is restricted. The first stop valve 25 is, for example, a valve operated manually. In the present embodiment, the first stop valve 25 is a three-way valve including a service port that can communicate with the outside of the refrigerant circuit 10.

[0030] The second stop valve 26 is a valve provided at the connection portion between the heat source refrigerant flow path 20 and the second connecting pipe 7. By closing the second stop valve 26, the flow of the refrigerant between the heat source refrigerant flow path 20 and the second connecting pipe 7 is restricted. The second stop valve 26 is, for example, a valve operated manually. In the present embodiment, the second stop valve 26 is a three-way valve including a service port that can communicate with the outside of the refrigerant circuit 10.

[0031] The first stop valve 25 and the second on-off valve 26 are closed when shipped from the manufacturing plant, and are opened when the installation work of the air conditioner 1 is completed. After the installation work is completed, the first stop valve 25 and the second stop valve 26 are usually kept open.

[0032] (2-2-6) Storage tank The accumulator 27 is a container for storing excess refrigerant generated in the refrigerant circuit 10 due to changes in the operating load of the utilization unit 3. The accumulator 27 is provided between the port P3 of the flow switching mechanism 22 and the suction pipe 21a of the compressor 21. The accumulator 27 is an example of a refrigerant storage container.

[0033] (2-2-7) Relationship between the amount of refrigerant charged and the volume of the heat source refrigerant flow path The heat source unit 2 is in a single state that is not connected to any of the utilization unit 3 and the connecting pipes 6 and 7, and the refrigerant is filled in the heat source refrigerant flow path 20. The amount of refrigerant filled in the heat source refrigerant flow path 20 is the amount filled in the refrigerant circuit 10 so that the air conditioner 1 can perform the refrigeration cycle operation with the required capacity. More specifically, the filling amount V1 (kg) of the refrigerant filled in the heat source refrigerant flow path 20, the volume V2 (L) of the heat source refrigerant flow path 20, and the design pressure P (MPa) of the heat source refrigerant flow path 20 satisfy the following relationship (Formula 1). (Mathematical formula 1) V1×a≤V2≤V1×b··· (1) a=0.078×P 2 -2.111×P+15.771··· (2) b=0.055×P 2 -1.768×P+16.144··· (3)

[0034] V2, which is the volume of the heat source refrigerant flow path 20, is the volume of the space obtained by connecting the compressor 21, the flow switching mechanism 22, the heat source heat exchanger 23, the heat source expansion mechanism 24, the first stop valve 25, the second stop valve 26 and the storage tank 27 to each other using the refrigerant piping 20a, and sealing it from the outside by the first stop valve 25 and the second stop valve 26.

[0035] In the present embodiment, the design pressure P (MPa) of the heat source refrigerant flow path 20 is 10 MPa to 14 MPa.

[0036] Furthermore, the volume V3 (L) of the accumulator 27 and the volume V2 (L) of the heat-source refrigerant flow path 20 may satisfy the following relationship (Formula 2). (Mathematical formula 2) 0.4×V2≤V3<0.9×V2

[0037] The refrigerant is typically filled into the heat source refrigerant flow path 20 at the manufacturing plant of the heat source unit 2. After the refrigerant is filled, the first stop valve 25 and the second stop valve are set to a closed state, thereby preventing the refrigerant from leaking from the heat source refrigerant flow path 20 after the heat source unit 2 is shipped from the manufacturing plant and before the air conditioning device 1 is installed.

[0038] (2-3) Connecting pipes The connecting pipes 6 and 7 are communicating pipes that connect the heat source refrigerant flow path 20 and the use side refrigerant flow path 30 (in other words, the heat source unit 2 and the use unit 3). The heat source refrigerant flow path 20, the use side refrigerant flow path 30, the first connecting pipe 6, and the second connecting pipe 7 are connected to form a refrigerant circuit 10.

[0039] The length of each of the connecting pipes 6 and 7 is targeted to have an upper limit of about 100 m, and can be arbitrarily changed according to the distance between the heat source unit 2 and the utilization unit 3 and the like.

[0040] (3) Operation of air conditioning system Next, the operation of each part of the air-conditioning apparatus 1 during the air-conditioning operation will be described.

[0041] (3-1) Refrigeration operation During cooling operation, the flow path switching mechanism 22 is controlled to the first state. In addition, the opening degree of the heat source expansion mechanism 24 is controlled according to the load of the utilization side heat exchanger 31 .

[0042] In this state, when the compressor 21 is started, the low-pressure refrigerant in the refrigeration cycle is sucked from the suction pipe 21a of the compressor 21, compressed and discharged from the discharge pipe 21b as a high-pressure refrigerant. The high-pressure refrigerant discharged from the compressor 21 is transported to the heat source heat exchanger 23 via the flow switching mechanism 22, and is cooled by heat exchange with the heat source air. In other words, the heat source heat exchanger 23 acts as a radiator. The high-pressure refrigerant cooled in the heat source heat exchanger 23 is decompressed when passing through the heat source expansion mechanism 24 and becomes a low-pressure gas-liquid two-phase state refrigerant. The low-pressure gas-liquid two-phase state refrigerant is transported to the utilization unit 3 via the first stop valve 25 and the first connecting pipe 6. The refrigerant transported to the utilization unit 3 is heated by heat exchange with the air of the air-conditioned space in the utilization side heat exchanger 31, and as a result, evaporates and becomes a low-pressure refrigerant. In other words, the utilization side heat exchanger 31 acts as an evaporator. The low-pressure refrigerant heated in the use-side heat exchanger 31 is sent to the heat source unit 2 via the second connecting pipe 7, and flows into the accumulator 27 via the second stop valve 26 and the flow switching mechanism 22. The low-pressure refrigerant flowing into the accumulator 27 is sucked into the compressor 21 again.

[0043] (3-2) Heating operation During the heating operation, the flow path switching mechanism 22 is controlled to the second state. In addition, the heat source expansion mechanism 24 is controlled to an opening degree capable of decompressing the refrigerant to a pressure at which the refrigerant can evaporate in the heat source heat exchanger 23 .

[0044] In this state, when the compressor 21 is started, the low-pressure refrigerant in the refrigeration cycle is sucked from the suction pipe 21a of the compressor 21, compressed and discharged from the discharge pipe 21b as a high-pressure refrigerant. The high-pressure refrigerant discharged from the compressor 21 is delivered to the utilization unit 3 via the flow path switching mechanism 22, the second stop valve 26 and the second connecting pipe 7. The high-pressure refrigerant delivered to the utilization unit 3 is cooled by heat exchange with the air of the air-conditioned space in the utilization side heat exchanger 31. In other words, the utilization side heat exchanger 31 functions as a radiator. The high-pressure refrigerant cooled in the utilization side heat exchanger 31 is delivered to the heat source unit 2 via the first connecting pipe 6. After passing through the first stop valve 25, the refrigerant delivered to the heat source unit 2 is decompressed when passing through the heat source expansion mechanism 24 and becomes a low-pressure gas-liquid two-phase refrigerant and flows into the heat source heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant flowing into the heat source heat exchanger 23 is heated by heat exchange with the heat source air, thereby evaporating and becoming a low-pressure refrigerant. In other words, the heat source heat exchanger 23 functions as an evaporator. The low-pressure refrigerant heated in the heat source heat exchanger 23 flows into the storage tank 27 via the flow path switching mechanism 22. The low-pressure refrigerant flowing into the storage tank 27 is sucked into the compressor 21 again.

[0045] (4) Refrigerant filling method Next, a method of charging the refrigerant circuit 10 with the refrigerant during the installation operation of the air-conditioning apparatus 1 will be described.

[0046] The installation work of the air conditioner 1 includes a step of placing the heat source unit 2 and the usage unit 3 at the installation location, and a step of connecting the heat source refrigerant flow path 20 and the usage side refrigerant flow path 30 via the connecting pipes 6 and 7 .

[0047] In the air conditioning apparatus 1, the refrigerant is filled in the heat source refrigerant flow path 20 of the heat source unit 2. Therefore, the refrigerant filled in the heat source unit 2 is sent to the utilization unit 3 through the connection pipes 6 and 7 by connecting the heat source refrigerant flow path 20 and the utilization side refrigerant flow path 30 via the connection pipes 6 and 7, and is filled in the refrigerant circuit 10. In this way, in the installation work of the air conditioning apparatus 1, the refrigerant is filled in the refrigerant circuit 10 by connecting the heat source refrigerant flow path 20 and the utilization side refrigerant flow path 30 via the connection pipes 6 and 7, so that the operation of filling the refrigerant into the refrigerant circuit 10 from the outside is unnecessary. Therefore, according to the air conditioning apparatus 1 including the heat source unit 2, the installation work is efficiently performed.

[0048] (5) Features (5-1) The heat source unit 2 is connected to the utilization unit 3 to form the air conditioning device 1. The heat source unit 2 includes a compressor 21, a heat source heat exchanger 23, a first stop valve 25, a second stop valve 26, a heat source refrigerant flow path 20, and a refrigerant. The heat source refrigerant flow path 20 is a flow path formed by connecting the compressor 21, the heat source heat exchanger 23, the first stop valve 25, and the second stop valve 26 through a refrigerant pipe 20a. The refrigerant is filled in the heat source refrigerant flow path 20. The refrigerant is carbon dioxide.

[0049] The amount V1 (kg) of refrigerant filled in the heat source refrigerant flow path 20, the volume V2 (L) of the heat source refrigerant flow path 20, and the design pressure P (MPa) of the heat source refrigerant flow path 20 satisfy the following relationship (Formula 1). (Mathematical formula 1) V1×a≤V2≤V1×b··· (1) a=0.078×P 2 -2.111×P+15.771··· (2) b=0.055×P 2 -1.768×P+16.144··· (3)

[0050] It is known that the pressure of carbon dioxide refrigerant increases rapidly when it reaches supercriticality compared to other refrigerants. Figure 2 It is the Mollier line diagram of R32. Figure 3 It is the Mollier diagram for carbon dioxide.

[0051] like Figure 2 As shown, R32 in a gas-liquid two-phase state can maintain the gas-liquid two-phase state even at 70°C, and the pressure at this time is about 5.0 MPa, wherein 70°C is the upper limit of the refrigerant temperature that rises in the heat source unit when not in operation due to the generally assumed external air temperature, direct sunlight, etc.

[0052] In contrast, Figure 3 As shown in FIG. 1 , carbon dioxide in a gas-liquid two-phase state reaches supercriticality when it exceeds the critical point CP (critical temperature: about 31.1°C, critical pressure: about 7.38 MPa). For example, supercritical carbon dioxide has a density of 500 kg / m 3In the case of a pressure of about 9 MPa (Pr1) at 40°C, the pressure rises sharply to about 14.9 MPa (Pr2) at 70°C, where 70°C is the upper limit of the refrigerant temperature that rises due to the generally assumed outside air temperature, direct sunlight, etc. Therefore, in the heat source refrigerant flow path 20 filled with carbon dioxide refrigerant, a pressure anomaly may occur in which the pressure of the refrigerant that reaches supercriticality due to the rise in outside air temperature, etc. exceeds the design pressure P of the heat source refrigerant flow path 20, and this may cause damage to various parts constituting the heat source refrigerant flow path 20.

[0053] In the heat source unit 2, the relationship between the filling amount V1 of the refrigerant and the volume V2 of the heat source refrigerant flow path 20 is set based on (Mathematical Formula 1) obtained from the temperature and pressure characteristics of the carbon dioxide refrigerant and the expected temperature range of the refrigerant. Here, the expected temperature range of the refrigerant is 50°C or more and 70°C or less. 50°C is the expected temperature in the summer and the like in a warehouse or the like for storing the heat source unit 2 (for example, the temperature inside the warehouse). In addition, 70°C is the upper limit of the refrigerant temperature that rises due to the outside air temperature, direct sunlight, etc. in a warehouse or the like for storing the heat source unit 2.

[0054] (2) of Mathematical formula 1 calculates the specific volume that suppresses damage of each part constituting the heat source refrigerant flow path 20 at the design pressure P due to pressure increase when the temperature of the refrigerant is 50°C.

[0055] (3) of Mathematical formula 1 calculates the specific volume that suppresses the enlargement of the heat source refrigerant flow path 20 where the volume of the heat source refrigerant flow path 20 at the design pressure P from excessively increasing when the temperature of the refrigerant is 70°C.

[0056] Under any refrigerant quantity V1, when the design pressure P of the heat source refrigerant flow path 20 is arbitrarily selected, the volume V2 of the heat source refrigerant flow path 20 is set to satisfy the volume V1×a calculated on the left side of (1) of mathematical formula 1 and to be less than the volume V1×b calculated on the right side of (1) of mathematical formula 1, thereby suppressing the enlargement of the heat source refrigerant flow path 20 and suppressing the occurrence of pressure abnormalities in the refrigerant flow path caused by the carbon dioxide refrigerant filled in the heat source refrigerant flow path 20 reaching supercriticality.

[0057] Therefore, according to the heat source unit 2, while suppressing the increase in size of the heat source refrigerant flow path 20, the occurrence of pressure abnormality in the refrigerant flow path due to the carbon dioxide refrigerant filling the heat source refrigerant flow path 20 becoming supercritical is suppressed.

[0058] (5-2) The design pressure P is not less than 10 MPa and not more than 14 MPa.

[0059] When the refrigerant pressure is 14 MPa, the point calculated by (2) of equation 1 is Figure 3 The first point Pa is calculated by (3) of Mathematical Formula 1. Figure 3 The second point Pb. When the refrigerant pressure is 10 MPa, the point calculated by (2) of Mathematical Formula 1 is Figure 3 The third point Pc is calculated by equation (3) of formula 1. Figure 3 In addition, the volume V2 of the heat source refrigerant flow path 20 satisfies (1) of the mathematical formula 1, so that the refrigerant filled in the heat source refrigerant flow path 20 is contained in Figure 3 The range is shown by the diagonal shading.

[0060] (5-3) It is preferable that the volume V3 (L) of the accumulator 27 and the volume V2 (L) of the heat source refrigerant flow path 20 satisfy the following relationship (Formula 2). (Mathematical formula 2) 0.4×V2≤V3<0.9×V2

[0061] The heat source unit 2 can store the refrigerant not only in the heat source refrigerant flow path 20 but also in the accumulator 27 in the heat source refrigerant flow path 20 , and thus can sufficiently ensure the volume V2 to effectively suppress the occurrence of pressure abnormality in the refrigerant flow path.

[0062] (5-4) The heat source unit 2 further includes a flow path switching mechanism 22 for switching the direction of flow of the refrigerant in the heat source refrigerant flow path 20 , and a storage tank 27 for storing the refrigerant.

[0063] The accumulator 27 can store not only the charged refrigerant but also the excess refrigerant generated due to the change of the operation load between the cooling operation and the heating operation.

[0064] (6) Modification (6-1) Modification A1 The air-conditioning apparatus 1 may be a multi-type air-conditioning apparatus including one heat source unit 2 and a plurality of utilization units 3 .

[0065] (6-2) Modification A2 The air conditioning device 1 may not include the flow path switching mechanism 22 and may be capable of performing only one of the cooling operation and the heating operation as the air conditioning operation.

[0066] (6-3) Modification A3 The installation operation of the air conditioning device 1 may further include a refrigerant additional charging step after the step of connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7. The refrigerant additional charging step is performed when the length of the connecting pipes 6 and 7 for connecting the heat source unit 2 and the utilization unit 3 is greater than a predetermined first length L1.

[0067] As described above, the heat source refrigerant flow path 20 of the heat source unit 2 is filled with a refrigerant of an amount (hereinafter also referred to as a required refrigerant amount) that is filled into the refrigerant circuit 10 so that the air conditioning device 1 can perform a refrigeration cycle operation of the required capacity. However, in a case where the heat source unit 2 and the utilization unit 3 are arranged at positions separated from each other, it is necessary to use connecting pipes 6 and 7 that are longer than usual to connect the heat source unit 2 and the utilization unit 3. In this case, the capacity of the refrigerant circuit 10 is greater than the initial assumption, and the refrigerant filled into the heat source refrigerant flow path 20 of the heat source unit 2 may be insufficient relative to the required refrigerant amount. For this reason, in the air conditioning device 1 of the variant A3, the maximum length that will not make the refrigerant filled into the heat source refrigerant flow path 20 less than the required refrigerant amount is pre-set to the first length L1. In other words, the length of the connecting pipes 6 and 7 is changed according to the installation position of the heat source unit 2 and the utilization unit 3. The connecting pipes 6 and 7 have a first length L1 as a change in length that does not require additional refrigerant filling to the refrigerant circuit 10, wherein the refrigerant circuit 10 is formed by connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7. The heat source unit 2 is filled with an amount of refrigerant corresponding to the required amount of refrigerant in the refrigerant circuit 10 when the connecting pipes 6 and 7 have the first length L1.

[0068] Thus, a worker or the like who performs the installation work of the air conditioner 1 determines whether the length of the connection pipes 6 and 7 required for the installation work of the air conditioner 1 is equal to or longer than the first length L1.

[0069] When the length of the connecting pipes 6 and 7 is shorter than the first length L1, the refrigerant filled in the heat source refrigerant flow path 20 is larger than the required refrigerant amount, and therefore, the additional refrigerant filling process is not required. Therefore, the additional refrigerant filling process is not performed, and after the process of connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7 is performed, the setting operation is completed. In other words, the filling amount of the refrigerant filled in the heat source refrigerant flow path 20 of the heat source unit 2 is larger than the required refrigerant amount in the refrigerant circuit 10 formed by connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7 when the connecting pipes 6 and 7 are shorter than the first length L1.

[0070] On the other hand, when the length of the connecting pipes 6 and 7 is greater than the first length L1, the refrigerant filled in the heat source refrigerant flow path 20 is less than the required amount of refrigerant, and therefore, an additional refrigerant filling process is required. Therefore, the additional refrigerant filling process is performed, and the amount of refrigerant corresponding to the length of the connecting pipes 6 and 7 is additionally filled into the refrigerant circuit 10. The refrigerant is additionally filled from the service port of the first stop valve 25 or the second stop valve 26, for example.

[0071] When the air conditioner 1 is a paired air conditioner including one heat source unit 2 and one utilization unit 3, the first length L1 is, for example, about 15 m. When the air conditioner 1 is a multi-connected air conditioner including one heat source unit 2 and a plurality of utilization units 3, the first length L1 is, for example, about 30 m to 70 m.

[0072] (6-4) Modification A4 The heat source refrigerant flow path 20 of the heat source unit 2 may further include a receiver for storing excess refrigerant. In this case, V3 includes the volume of the receiver in addition to the volume of the accumulator 27.

[0073] <Second embodiment> (1) Overall structure The heat source unit 2a of the second embodiment will be described with the focus on the differences from the heat source unit 2. The heat source unit 2a is also connected to one or more utilization units 3 using the first connection pipe 6 and the second connection pipe 7 as the heat source unit 2 to form the air conditioning apparatus 1a. Hereinafter, the same or corresponding features as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted. Figure 4 It is a schematic configuration diagram of an air-conditioning apparatus 1 a including a heat source unit 2 a according to the second embodiment.

[0074] The main difference between the heat source unit 2a and the heat source unit 2 is that the heat source unit 2a further includes a refrigerant quantity adjustment unit 28. The refrigerant quantity adjustment unit 28 stores the refrigerant filled in the installation operation of the air-conditioning device 1a, and accumulates the excess refrigerant generated in the refrigerant circuit 10 due to the change in the operating load of the utilization unit 3. The refrigerant quantity adjustment unit 28 is included in the heat source refrigerant flow path 20 of the heat source unit 2a. Therefore, in the heat source unit 2a, a larger amount of refrigerant is filled in the heat source refrigerant flow path 20 than in the heat source unit 2. The refrigerant quantity adjustment unit 28 includes a refrigerant storage container 28a, a pressure regulating valve 28b, a check valve 28c, an electromagnetic valve 28d, and an expansion mechanism 28e.

[0075] (2) Detailed structure (2-1) Refrigerant storage container The refrigerant storage container 28a is a container (tank) that stores at least a portion of the refrigerant filled in the heat source refrigerant flow path 20 and accumulates excess refrigerant generated in the refrigerant circuit 10. The refrigerant storage container 28a has a first port 28aa and a second port 28ab. The refrigerant storage container 28a is an example of a refrigerant storage container.

[0076] The first port 28aa is provided to adjust the pressure inside the refrigerant storage container 28a and is connected to the refrigerant pipe 20a connecting the port P3 of the flow switching mechanism 22 and the accumulator 27 and the discharge pipe 21b of the compressor 21 via the pressure adjustment pipe 20b.

[0077] The second port 28ab is a port through which the refrigerant flows, and is connected to the suction pipe 21a of the compressor 21 via the refrigerant pipe 20a.

[0078] (2-2) Pressure regulating valve The pressure regulating valve 28b is a valve that prevents the pressure of the refrigerant in the refrigerant storage container 28a from becoming too high. The pressure regulating valve 28b is provided in the pressure regulating pipe 20b, and the pressure regulating pipe 20b is connected to the refrigerant pipe 20a that connects the port P3 of the flow path switching mechanism 22 and the accumulator 27. The pressure regulating valve 28b opens when the pressure of the refrigerant in the refrigerant storage container 28a reaches a predetermined value or more, and releases the high-pressure refrigerant to the accumulator 27.

[0079] (2-3) Check valve and solenoid valve The check valve 28c and the solenoid valve 28d are valves used when increasing the pressure of the refrigerant in the refrigerant storage container 28a. The check valve 28c and the solenoid valve 28d are provided in the pressure regulating pipe 20b connected to the discharge pipe 21b of the compressor 21. When the solenoid valve 28d is opened during the operation of the compressor 21, the high-pressure refrigerant discharged from the compressor 21 is transported to the refrigerant storage container 28a. Typically, the solenoid valve 28d is opened when the refrigerant in the refrigerant storage container 28a is filled into the refrigerant circuit 10. The check valve 28c inhibits the refrigerant from flowing from the refrigerant storage container 28a to the discharge pipe 21b of the compressor 21. The opening and closing of the solenoid valve 28d can be performed by a control unit not shown in the figure. In addition, the check valve 28c and the solenoid valve 28d can also be a flow regulating mechanism including an electric valve.

[0080] (2-4) Expansion mechanism The expansion mechanism 28e adjusts the flow rate of the refrigerant flowing through the refrigerant pipe 20a connecting the suction pipe 21a of the compressor 21 and the refrigerant storage container 28a and reduces the pressure of the refrigerant. The opening degree of the expansion mechanism 28e can be controlled by a control unit (not shown).

[0081] (2-5) Relationship between the amount of refrigerant charged and the volume of the heat source refrigerant flow path The heat source unit 2a is also similar to the heat source unit 2, and the refrigerant is filled in the heat source refrigerant flow path 20 in a single state not connected to the utilization unit 3 and any of the connecting pipes 6 and 7. The amount of refrigerant filled in the heat source refrigerant flow path 20 is the amount filled in the refrigerant circuit 10 so that the air conditioning device 1a can perform the refrigeration cycle operation with the required capacity. At this time, the filling amount V1 (kg) of the refrigerant filled in the heat source refrigerant flow path 20, the volume V2 (L) of the heat source refrigerant flow path 20, and the design pressure P (MPa) of the heat source refrigerant flow path 20 satisfy the relationship of the above (Mathematical Formula 1).

[0082] In the heat source unit 2a, V3 includes the volume of the refrigerant storage container 28a in addition to the volume of the accumulator 27. The volume V3 (L) and the volume V2 (L) of the heat source refrigerant flow path 20 satisfy the relationship (Formula 2) described above.

[0083] (3) Operation of air conditioning system In both cooling operation and heating operation, the opening of the expansion mechanism 28e and the electromagnetic valve 28d is controlled to be fully open or nearly fully open when the refrigerant is supplied. The opening of the expansion mechanism 28e and the electromagnetic valve 28d is controlled to be fully closed or nearly fully closed when the refrigerant supply is finished. Thus, the required refrigerant is supplied to the refrigerant circuit 10 of the air-conditioning device 1a. In addition, the refrigerant that is pre-filled in the refrigerant storage container 28a and becomes the excess refrigerant is not supplied to the refrigerant circuit 10 but is stored in the refrigerant storage container 28a.

[0084] The operations of the other parts of the air-conditioning apparatus 1 a during the air-conditioning operation are the same as those of the air-conditioning apparatus 1 , and therefore the description thereof will be omitted.

[0085] (4) Refrigerant filling method The installation operation of the air-conditioning device 1a includes, in addition to the steps of placing the heat source unit 2 and the utilization unit 3 at the installation location respectively and connecting the heat source unit 2 and the utilization unit 3 via the connecting pipes 6 and 7, the step of sending the refrigerant stored in the refrigerant storage container 28a to the refrigerant circuit 10.

[0086] In the process of sending the refrigerant stored in the refrigerant storage container 28a to the refrigerant circuit 10, the openings of the heat source expansion mechanism 24, the electromagnetic valve 28d, and the expansion mechanism 28e are controlled to be fully open or nearly fully open. In this state, when the compressor 21 is started, the high-pressure refrigerant discharged from the compressor 21 passes through the first port 28aa and pushes the refrigerant stored in the refrigerant storage container 28a out from the second port 28ab. As a result, the refrigerant after passing through the expansion mechanism 28e is sucked from the suction pipe 21a of the compressor 21, and is filled in the refrigerant circuit 10. When the compressor 21 stops, this process ends.

[0087] In the air conditioning apparatus 1a, the heat source unit 2a further includes the refrigerant amount adjustment unit 28, and therefore, a larger amount of refrigerant is filled in the heat source refrigerant flow path 20 than in the heat source unit 2. Therefore, according to the air conditioning apparatus 1a including the heat source unit 2a, even when a plurality of utilization units 3 are included, the heat source unit 2a can store a sufficient amount of required refrigerant in the heat source refrigerant flow path 20.

[0088] (5) Features (5-1) The heat source unit 2a is connected to the utilization unit 3 to form the air conditioning device 1a. The heat source unit 2a includes a compressor 21, a heat source heat exchanger 23, a first stop valve 25, a second stop valve 26, a heat source refrigerant flow path 20, and a refrigerant. The heat source refrigerant flow path 20 of the heat source unit 2a is a flow path formed by connecting the compressor 21, the heat source heat exchanger 23, the first stop valve 25, the second stop valve 26, and the refrigerant amount adjustment unit 28 through a refrigerant piping 20a. The refrigerant is filled in the heat source refrigerant flow path 20. The refrigerant is carbon dioxide.

[0089] The filling amount V1 (kg) of the refrigerant filled in the heat source refrigerant flow path 20, the volume V2 (L) of the heat source refrigerant flow path 20, and the design pressure P (MPa) of the heat source refrigerant flow path 20 satisfy the relationship of (Formula 1) above.

[0090] Therefore, according to the heat source unit 2a, while also suppressing an increase in the size of the heat source refrigerant flow path 20, the occurrence of pressure abnormality in the refrigerant flow path due to the filled carbon dioxide refrigerant becoming supercritical is suppressed.

[0091] (5-2) It is preferable that the volume V3 (L) of the accumulator 27 and the refrigerant storage container 28a and the volume V2 (L) of the heat source refrigerant flow path 20 satisfy the relationship of (Formula 3) above.

[0092] The heat source unit 2a can store the refrigerant not only in the heat source refrigerant flow path 20 but also in the storage tank 27 and the refrigerant storage container 28a. Therefore, the volume V2 can be sufficiently ensured to effectively suppress the occurrence of pressure abnormalities in the refrigerant flow path.

[0093] (6) Modification The air-conditioning device 1 a and the heat-source refrigerant flow path 20 may also have the features of the above-described Modifications A1 to A5.

[0094] As mentioned above, although embodiment of this disclosure is described, it should be understood that various changes in form and details can be made without departing from the spirit and scope of this disclosure described in the claims. Explanation of symbols

[0095] 1. 1a Air conditioning device; 2. 2a heat source unit; 3. Utilization unit; 6. First connecting pipe (connecting pipe); 7 second connecting pipe (connecting pipe); 10. Refrigerant circuit; 20 heat source refrigerant flow path (refrigerant flow path); 20a refrigerant piping; 21 compressor; 22 flow path switching mechanism; 23 heat source heat exchanger; 25 first stop valve; 26 second stop valve; 27 Storage tanks (refrigeration storage containers); 28 refrigerant quantity adjustment unit; 28a Refrigerant storage container; L1 first length. Prior art literature Patent Literature

[0096] Patent Document 1: Japanese Patent Application Publication No. 2008-045769

Claims

1. A heat source unit (2, 2a), which is connected to a utilization unit (3) to form an air conditioning device (1, 1a), characterized in that: include: Compressor (21); Heat source heat exchanger (23); A first stop valve (25); A second stop valve (26); A refrigerant flow path (20), wherein the refrigerant flow path is formed by connecting the compressor, the heat source heat exchanger, the first stop valve, and the second stop valve through a refrigerant pipe; as well as The refrigerant filled in the refrigerant flow path, The refrigerant is carbon dioxide, The filling amount V1 (kg) of the refrigerant filled in the refrigerant flow path, the volume V2 (L) of the refrigerant flow path, and the design pressure P (MPa) of the refrigerant flow path satisfy the following relationship: V1×a≤V2≤V1×b a=0.078×P 2 -2.111×P+15.771 b=0.055×P 2 -1.768×P+16.144。 2. The heat source unit according to claim 1, characterized in that The design pressure P is greater than or equal to 10 MPa and less than or equal to 14 MPa.

3. The heat source unit according to claim 1 or 2, characterized in that: The heat source unit further includes a refrigerant storage container (27, 28a) for storing the refrigerant. The volume V3 (L) of the refrigerant storage container satisfies the relationship 0.4×V2≤V3<0.9×V2.

4. The heat source unit according to any one of claims 1 to 3, characterized in that: Also includes: a flow path switching mechanism (22), the flow path switching mechanism switching the direction of flow of the refrigerant in the refrigerant flow path; as well as A refrigerant storage container (27, 28a) stores the refrigerant.

5. An air conditioning device, characterized in that: include: The heat source unit according to any one of claims 1 to 4; as well as The utilization unit is connected to the heat source unit via connecting pipes (6, 7), The length of the connecting pipe is changed according to the installation positions of the heat source unit and the utilization unit. The connecting pipe has a first length (L1) that does not require additional charging of the refrigerant into the refrigerant circuit (10), and the refrigerant circuit is formed by connecting the heat source unit and the utilization unit via the connecting pipe. The heat source unit is filled with the refrigerant in an amount corresponding to a required refrigerant amount in the refrigerant circuit when the connecting pipe has the first length.

6. An air conditioning device, characterized in that: include: The heat source unit according to any one of claims 1 to 4; as well as The utilization unit is connected to the heat source unit via connecting pipes (6, 7), The length of the connecting pipe is changed according to the installation positions of the heat source unit and the utilization unit. The amount of refrigerant filled in the refrigerant flow path of the heat source unit is greater than the required amount of refrigerant in the refrigerant circuit (10) when the connecting pipe is shorter than a predetermined first length (L1), and the refrigerant circuit is formed by connecting the heat source unit and the utilization unit via the connecting pipe.

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