Heat source unit and air conditioner

Abstract

To propose a heat source unit of an air conditioner capable of suppressing occurrence of pressure abnormality in a refrigerant flow path due to a filled carbon dioxide refrigerant becoming supercritical.SOLUTION: A heat source unit is connected to a utilization unit, and constitutes an air conditioner. The heat source unit comprises a compressor, a heat source heat exchanger, a first closing valve, a second closing 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 closing valve, and the second closing valve are connected by refrigerant pipes. The refrigerant is filled in the refrigerant flow path. The refrigerant is carbon dioxide. An amount V1 (kg) of the refrigerant filled in the refrigerant flow path, a volume V2 (L) of the refrigerant flow path, and a design pressure P (MPa) of the refrigerant flow path satisfy the following relations: V1×a≤V2≤V1×b; a=0.078×P2-2.111×P+15.771; b=0.055×P2-1.768×P+16.144.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Air conditioners that use carbon dioxide as a refrigerant are known. Patent Document 1 (JP Patent Publication 2008-045769 A) discloses a method for filling the air conditioner with carbon dioxide refrigerant, with the aim of improving the efficiency of installation work for the air conditioner.

[0003] In order to further improve the efficiency of air conditioning system installation work, a technique is known in which the heat source unit (outdoor unit) is pre-filled with refrigerant at the manufacturing factory, and then the heat source unit and utilization unit (indoor unit) are connected at the installation site to fill the refrigerant into the refrigerant circuit. Summary of the Invention [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 passage may become supercritical due to an increase in the outdoor air temperature. The pressure of the refrigerant that becomes supercritical increases rapidly, which may cause pressure abnormalities in the refrigerant flow passage.

[0005] The present disclosure proposes a heat source unit for an air conditioner that suppresses the occurrence of pressure abnormalities in a refrigerant flow path caused by the filled carbon dioxide refrigerant becoming supercritical. [Means for solving the problem]

[0006] A heat source unit of a first aspect is connected to a utilization unit to constitute an air conditioner. 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 flow path is filled with the refrigerant. 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 of the refrigerant flow path P (MPa) satisfy the following relationship.

[0008] 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 According to this heat source unit, the occurrence of pressure abnormalities in the refrigerant flow passages caused by the filled carbon dioxide refrigerant becoming supercritical is suppressed.

[0009] A heat source unit according to a second aspect is the heat source unit according to the first aspect, in which the design pressure P is not less than 10 MPa and not more than 14 MPa.

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

[0011] The volume V3(L) of the refrigerant storage container satisfies the following relationship.

[0012] 0.4×V2≦V3<0.9×V2 Since the heat source unit can store refrigerant not only in the refrigerant flow path but also in the refrigerant storage container, the volume V2 can be sufficiently secured and pressure abnormalities in the refrigerant flow path can be effectively suppressed.

[0013] A heat source unit according to a fourth aspect is the heat source unit according to any one of the first aspect to the third aspect, further comprising a flow path switching mechanism and a refrigerant storage container. The flow path switching mechanism switches the direction in which the refrigerant flows in the refrigerant flow path. The refrigerant storage container is a container that stores the refrigerant.

[0014] The refrigerant storage container can store not only the filled refrigerant, but also excess refrigerant that occurs due to fluctuations in operating load between cooling operation and heating operation, etc.

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

[0016] An air conditioning apparatus according to a sixth aspect includes a heat source unit according to any one of the first to fourth aspects, and a utilization unit. The utilization unit is connected to the heat source unit via a connection pipe. The length of the connection 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 amount of refrigerant required in the refrigerant circuit formed by connecting the heat source unit and the utilization unit via the connection pipe when the connection pipe is shorter than a predetermined first length. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic configuration diagram of an air conditioner 1 equipped with a heat source unit 2 according to a first embodiment. [Diagram 2] Mollier diagram of R32. [Diagram 3] Mollier diagram of carbon dioxide. [Figure 4] FIG. 11 is a schematic configuration diagram of an air conditioner 1a equipped with a heat source unit 2a according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] First Embodiment (1) Overall structure FIG. 1 is a schematic diagram of an air conditioner 1 including a heat source unit 2 according to a first embodiment. The air conditioner 1 performs a vapor compression refrigeration cycle operation and performs air conditioning operation (cooling operation and heating operation) in a space to be air-conditioned (not shown), such as a room. The air conditioner 1 includes one heat source unit 2, one utilization unit 3, and a first connection pipe 6 and a second connection pipe 7 that connect the heat source unit 2 and the utilization unit 3. The heat source unit 2, the utilization unit 3, and the connection pipes 6 and 7, which are connected to each other, constitute a refrigerant circuit 10. The refrigerant filled in the refrigerant circuit 10 is carbon dioxide. In the following description, the first connection pipe 6 and the second connection pipe 7 are also collectively referred to as the connection pipes 6 and 7.

[0019] Although details will be described later, the refrigerant to be filled into the refrigerant circuit 10 is filled into the heat source unit 2 at a manufacturing factory or the like. At the installation site of the air conditioning device 1, the heat source unit 2 and the utilization unit 3 are connected via connection pipes 6 and 7, so that the refrigerant that has filled the heat source unit 2 is filled into the refrigerant circuit 10.

[0020] (2) Detailed configuration (2-1) Usage unit The utilization unit 3 is installed in a space to be air-conditioned. The utilization unit 3 has a utilization side refrigerant flow path 30 which constitutes a part of the refrigerant circuit 10. The utilization side refrigerant flow path 30 includes a utilization side heat exchanger 31.

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

[0022] (2-2) Heat source unit The heat source unit 2 is installed outside the space to be air-conditioned (outdoors, etc.). The heat source unit 2 has a heat source refrigerant flow path 20 that constitutes 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 shut-off valve 25, a second shut-off 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 shut-off valve 25, the second shut-off 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 draws in low-pressure refrigerant in the refrigeration cycle from the suction pipe 21a, compresses the refrigerant with a compression mechanism (not shown), and discharges the compressed refrigerant as high-pressure refrigerant to the discharge pipe 21b. In this 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 path switching mechanism 22 switches the flow direction of the refrigerant, and changes the state of the refrigerant circuit 10 between a first state and a second state. When the refrigerant circuit 10 is in the first state, the heat source heat exchanger 23 functions as a refrigerant radiator, and the utilization side heat exchanger 31 functions as a refrigerant evaporator. When the refrigerant circuit 10 is in the second state, the heat source heat exchanger 23 functions as a refrigerant evaporator, and the utilization side heat exchanger 31 functions as a refrigerant radiator. The state of the flow path switching mechanism 22 can be changed by a control unit (not shown).

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

[0026] The flow path switching mechanism 22 is not limited to a four-way switching valve. For example, the flow path switching mechanism 22 may be configured by combining a plurality of solenoid valves and refrigerant pipes so as to realize switching of 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 opening degree of the heat source expansion mechanism 24 is controlled to adjust the flow rate of the refrigerant flowing through the heat source refrigerant flow path 20 and to 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 a first stop valve 25. The opening degree of the heat source expansion mechanism 24 can be controlled by a control unit (not shown).

[0029] (2-2-5) First and second shutoff valves The first shut-off valve 25 is a valve provided at the connection portion between the heat source refrigerant flow path 20 and the first connecting pipe 6. When the first shut-off valve 25 is closed, the flow of refrigerant between the heat source refrigerant flow path 20 and the first connecting pipe 6 is restricted. The first shut-off valve 25 is, for example, a valve that is manually operated. In this embodiment, the first shut-off 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 shut-off valve 26 is a valve provided at the connection portion between the heat source refrigerant flow path 20 and the second connecting pipe 7. When the second shut-off valve 26 is closed, the flow of refrigerant between the heat source refrigerant flow path 20 and the second connecting pipe 7 is restricted. The second shut-off valve 26 is, for example, a valve that is manually operated. In this embodiment, the second shut-off 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 shut-off valve 25 and the second shut-off valve 26 are closed when shipped from the manufacturing factory, and are opened when installation work of the air conditioning apparatus 1 is completed. After installation work is completed, the first shut-off valve 25 and the second shut-off valve 26 are usually maintained in the open state.

[0032] (2-2-6) Accumulator The accumulator 27 is a container that stores excess refrigerant generated in the refrigerant circuit 10 in response to fluctuations in the operating load of the utilization unit 3, etc. The accumulator 27 is provided between the port P3 of the flow path 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 refrigerant charge amount and heat source refrigerant flow path volume The heat source unit 2 is in a standalone state, not connected to any of the utilization units 3 or the connecting pipes 6, 7, and 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 an amount that, when filled in the refrigerant circuit 10, allows the air conditioning apparatus 1 to perform refrigeration cycle operation with the required capacity. More specifically, the filling amount V1 (kg) of refrigerant filled in the heat source refrigerant flow path 20 satisfies the following relationship (Equation 1) between 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.

[0034] (Number 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) The volume V2 of the heat source refrigerant flow path 20 is the volume of the space in which the compressor 21, flow path switching mechanism 22, heat source heat exchanger 23, heat source expansion mechanism 24, first shut-off valve 25, second shut-off valve 26, and accumulator 27 are connected to each other using refrigerant piping 20a, and which is blocked from the outside by the first shut-off valve 25 and the second shut-off valve 26.

[0035] In this embodiment, the design pressure P (MPa) of the heat source refrigerant passage 20 is equal to or greater than 10 MPa and equal to or less than 14 MPa.

[0036] Furthermore, the volume V3(L) of the accumulator 27 and the volume V2(L) of the heat-source refrigerant passage 20 may satisfy the relationship of the following equation (2).

[0037] (Number 2) 0.4×V2≦V3<0.9×V2 The refrigerant is typically charged into the heat source refrigerant flow path 20 at a manufacturing factory for the heat source unit 2. By closing the first shutoff valve 25 and the second shutoff valve after the refrigerant is charged, leakage of the refrigerant from the heat source refrigerant flow path 20 is suppressed from the time the heat source unit 2 is shipped from the manufacturing factory until the air conditioning device 1 is installed.

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

[0039] The length of each of the connection pipes 6, 7 is changed arbitrarily depending on the distance between the heat source unit 2 and the utilization unit 3, etc., with an upper limit of approximately 100 m.

[0040] (3) Air conditioner operation Next, the operation of each part of the air conditioner 1 during air conditioning operation will be described.

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

[0042] In this state, when the compressor 21 starts, the low-pressure refrigerant in the refrigeration cycle is sucked in through 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 sent to the heat source heat exchanger 23 via the flow path switching mechanism 22, and is cooled by heat exchange with the heat source air. In other words, the heat source heat exchanger 23 functions 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 refrigerant in a gas-liquid two-phase state. The low-pressure refrigerant in a gas-liquid two-phase state is sent to the utilization unit 3 via the first stop valve 25 and the first connection pipe 6. The refrigerant sent to the utilization unit 3 is heated by heat exchange with the air in the space to be air-conditioned 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 functions as an evaporator. The low-pressure refrigerant heated in the utilization-side heat exchanger 31 is sent to the heat source unit 2 via the second connection pipe 7, and flows into the accumulator 27 via the second shutoff valve 26 and the flow path switching mechanism 22. The low-pressure refrigerant that has flowed into the accumulator 27 is sucked into the compressor 21 again.

[0043] (3-2) Heating operation During heating operation, the flow path switching mechanism 22 is controlled to the second state. Also, the heat source expansion mechanism 24 is controlled to an opening degree that can reduce the pressure to a level at which the refrigerant can be evaporated in the heat source heat exchanger 23.

[0044] In this state, when the compressor 21 starts, the low-pressure refrigerant in the refrigeration cycle is sucked in through 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 sent to the utilization unit 3 via the flow path switching mechanism 22, the second shutoff valve 26, and the second connection pipe 7. The high-pressure refrigerant sent to the utilization unit 3 is cooled by heat exchange with the air in the space to be air-conditioned 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 sent to the heat source unit 2 via the first connection pipe 6. The refrigerant sent to the heat source unit 2 passes through the first shutoff valve 25, and is decompressed when passing through the heat source expansion mechanism 24, becoming a low-pressure refrigerant in a gas-liquid two-phase state, and flows into the heat source heat exchanger 23. The low-pressure refrigerant in a gas-liquid two-phase state that flows into the heat source heat exchanger 23 is heated through heat exchange with the heat source air and evaporates to become a low-pressure refrigerant. In other words, the heat source heat exchanger 23 functions as an evaporator. The low-pressure refrigerant heated by the heat source heat exchanger 23 flows into the accumulator 27 via the flow path switching mechanism 22. The low-pressure refrigerant that flows into the accumulator 27 is sucked into the compressor 21 again.

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

[0046] The installation work of the air conditioning apparatus 1 includes a process of installing the heat source unit 2 and the utilization unit 3 at their respective installation locations, and a process of connecting the heat source refrigerant flow path 20 and the utilization side refrigerant flow path 30 via the connection pipes 6,7.

[0047] In the air conditioning apparatus 1, the heat source refrigerant flow path 20 of the heat source unit 2 is filled with refrigerant, and the heat source refrigerant flow path 20 and the utilization side refrigerant flow path 30 are connected via the connection pipes 6, 7, so that the refrigerant filled in the heat source unit 2 is sent to the utilization unit 3 through the connection pipes 6, 7, thereby filling the refrigerant circuit 10. In this way, during the installation work of the air conditioning apparatus 1, the heat source refrigerant flow path 20 and the utilization side refrigerant flow path 30 are connected via the connection pipes 6, 7, so that the refrigerant is filled in the refrigerant circuit 10, and therefore there is no need to fill the refrigerant circuit 10 with refrigerant from the outside. Therefore, the installation work can be carried out efficiently according to the air conditioning apparatus 1 equipped with the heat source unit 2.

[0048] (5) Features (5-1) The heat source unit 2 is connected to the utilization unit 3 to constitute the air conditioner 1. The heat source unit 2 includes a compressor 21, a heat source heat exchanger 23, a first shut-off valve 25, a second shut-off valve 26, a heat source refrigerant flow path 20, and a refrigerant. The heat source refrigerant flow path 20 is a flow path in which the compressor 21, the heat source heat exchanger 23, the first shut-off valve 25, and the second shut-off valve 26 are connected by 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 passage 20, the volume V2 (L) of the heat source refrigerant passage 20, and the design pressure P (MPa) of the heat source refrigerant passage 20 satisfy the relationship of the following (Equation 1).

[0050] (Number 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) It is known that carbon dioxide refrigerant has a steeper increase in pressure when it becomes supercritical than other refrigerants. Figure 2 shows the Mollier diagram of R32. Figure 3 shows the Mollier diagram of carbon dioxide.

[0051] As shown in Figure 2, R32 in a two-phase gas-liquid state can maintain this state even at 70°C, the upper limit of the refrigerant temperature that is normally expected in a heat source unit when it is not in operation, due to factors such as the outside air temperature and direct sunlight, and the pressure at this time is approximately 5.0 MPa.

[0052] In contrast, as shown in FIG. 3, carbon dioxide in a gas-liquid two-phase state becomes supercritical when it exceeds the critical point CP (critical temperature: about 31.1°C, critical pressure: about 7.38MPa). Supercritical carbon dioxide has a density of, for example, 500 kg / m 3 In this case, the pressure, which was about 9 MPa (Pr1) at 40°C, rapidly rises to about 14.9 MPa (Pr2) at 70°C, which is the upper limit of the refrigerant temperature that is normally expected to rise due to the outside air temperature, direct sunlight, etc. For this reason, in the heat-source refrigerant flow path 20 filled with carbon dioxide refrigerant, a pressure abnormality occurs in which the pressure of the refrigerant that has become supercritical due to an increase in the outside air temperature, etc., exceeds the design pressure P of the heat-source refrigerant flow path 20, which may cause damage to each component of the heat-source refrigerant flow path 20.

[0053] In the heat source unit 2, the relationship between the refrigerant charge amount V1 and the volume V2 of the heat source refrigerant flow path 20 is set based on (Mathematical formula 1) obtained from the characteristics between the temperature and pressure of the carbon dioxide refrigerant and the assumed temperature range of the refrigerant. Here, the assumed temperature range of the refrigerant is 50°C or higher and 70°C or lower. 50°C is the temperature assumed in summer, etc. in a warehouse or other location where the heat source unit 2 is stored (for example, the temperature inside the warehouse). Also, 70°C is the upper limit of the refrigerant temperature that can rise due to the outside air temperature, direct sunlight, etc. in the warehouse or other location where the heat source unit 2 is stored.

[0054] Equation 1 (2) determines the specific volume at which each part constituting the heat-source refrigerant flow path 20 at the design pressure P is prevented from being damaged by a pressure rise when the refrigerant temperature is 50°C.

[0055] Equation 1 (3) determines the specific volume that prevents the heat source refrigerant passage 20 from becoming larger than necessary when the volume of the heat source refrigerant passage 20 at the design pressure P is increased when the refrigerant temperature is 70°C.

[0056] When the design pressure P of the heat source refrigerant flow path 20 is arbitrarily selected for an arbitrary refrigerant amount V1, the volume V2 of the heat source refrigerant flow path 20 is set to be greater than or equal to the volume V1×a calculated on the left side of equation 1 (1) and less than or equal to the volume V1×b calculated on the right side of equation 1 (1), thereby 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 becoming supercritical, while suppressing the increase in size of the heat source refrigerant flow path 20.

[0057] Therefore, the heat source unit 2 suppresses 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 becoming supercritical, while preventing the heat source refrigerant flow path 20 from becoming too large.

[0058] (5-2) The design pressure P is 10 MPa or more and 14 MPa or less.

[0059] When the refrigerant pressure becomes 14 MPa, the point calculated by (2) of formula 1 becomes the first point Pa in Fig. 3, and the point calculated by (3) of formula 1 becomes the second point Pb in Fig. 3. When the refrigerant pressure becomes 10 MPa, the point calculated by (2) of formula 1 becomes the third point Pc in Fig. 3, and the point calculated by (3) of formula 1 becomes the fourth point Pd in ​​Fig. 3. When the volume V2 of the heat source-refrigerant flow path 20 satisfies (1) of formula 1, the refrigerant filled in the heat source-refrigerant flow path 20 is included in the range indicated by the diagonal hatching in Fig. 3.

[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 passage 20 satisfy the following relationship (Mathematical Expression 2).

[0061] (Number 2) 0.4×V2≦V3<0.9×V2 Since the heat source unit 2 can store 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, the volume V2 can be sufficiently secured and pressure abnormalities in the refrigerant flow path can be effectively suppressed.

[0062] (5-4) The heat source unit 2 further includes a flow path switching mechanism 22 that switches the direction in which the refrigerant flows in the heat source-refrigerant flow path 20, and an accumulator 27 that stores the refrigerant.

[0063] The accumulator 27 can store not only the filled refrigerant but also surplus refrigerant generated due to fluctuations in the operating load between the cooling operation and the heating operation, etc.

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

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

[0066] (6-3) Modification A3 The installation work of the air conditioning apparatus 1 may further include a step of additionally charging a refrigerant after the step of connecting the heat source unit 2 and the utilization unit 3 via the connection pipes 6, 7. The additional charging step of a refrigerant is performed when the length of the connection pipes 6, 7 used to connect the heat source unit 2 and the utilization unit 3 is equal to or longer 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 an amount of refrigerant that allows the air conditioner 1 to perform a refrigeration cycle operation with a required capacity by filling the refrigerant circuit 10 (hereinafter, also referred to as a required refrigerant amount). However, when the heat source unit 2 and the utilization unit 3 are disposed at positions distant from each other, it becomes necessary to connect the heat source unit 2 and the utilization unit 3 using the connection pipes 6, 7 that are longer than usual. In such a case, the capacity of the refrigerant circuit 10 becomes larger than initially expected, and the refrigerant filled in the heat source refrigerant flow path 20 of the heat source unit 2 may be insufficient for the required refrigerant amount. Therefore, in the air conditioner 1 according to the modification A3, the maximum length at which the refrigerant filled in the heat source refrigerant flow path 20 does not become less than the required refrigerant amount is preset as the first length L1. In other words, the length of the connection pipes 6, 7 is changed according to the installation positions of the heat source unit 2 and the utilization unit 3. The connecting pipes 6, 7 have a first length L1 as one of their length variations, which does not require additional charging of refrigerant into the refrigerant circuit 10 formed by connecting the heat source unit 2 and the utilization units 3 via the connecting pipes 6, 7. The heat source unit 2 is filled with an amount of refrigerant corresponding to the amount of refrigerant required in the refrigerant circuit 10 when the connecting pipes 6, 7 have the first length L1.

[0068] This allows a worker or the like performing the installation work of the air conditioner 1 to determine whether or not the length of the connection pipes 6, 7 required for the installation work of the air conditioner 1 is equal to or greater than the first length L1.

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

[0070] On the other hand, when the length of the connecting pipes 6, 7 is equal to or longer than the first length L1, the amount of refrigerant filled in the heat source refrigerant flow path 20 is insufficient for the required amount of refrigerant, and therefore a refrigerant additional charging step is required. Therefore, a refrigerant additional charging step is performed, and an amount of refrigerant according to the length of the connecting pipes 6, 7 is additionally charged into the refrigerant circuit 10. The refrigerant is additionally charged from the service port of the first shutoff valve 25 or the second shutoff valve 26, for example.

[0071] When the air conditioning apparatus 1 is a pair-type air conditioning apparatus equipped with one heat source unit 2 and one utilization unit 3, the first length L1 is, for example, about 15 m. When the air conditioning apparatus 1 is a multi-type air conditioning apparatus equipped with one heat source unit 2 and multiple 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 that stores surplus 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 A heat source unit 2a according to the second embodiment will be described, focusing on the differences from the heat source unit 2. Like the heat source unit 2, the heat source unit 2a is connected to one or more utilization units 3 using a first connection pipe 6 and a second connection pipe 7 to constitute an air conditioner 1a. Below, features that are the same as or correspond to those in the first embodiment are given the same reference numerals and description thereof is omitted. Fig. 4 is a schematic diagram of an air conditioner 1a equipped with a heat source unit 2a 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 amount adjustment unit 28. The refrigerant amount adjustment unit 28 stores the refrigerant filled during the installation work of the air conditioning device 1a, and also stores surplus refrigerant generated in the refrigerant circuit 10 depending on fluctuations in the operating load of the utilization unit 3, etc. The refrigerant amount adjustment unit 28 is included in the heat source refrigerant flow path 20 of the heat source unit 2a. As a result, in the heat source unit 2a, more refrigerant is filled in the heat source refrigerant flow path 20 than in the heat source unit 2. The refrigerant amount adjustment unit 28 has a refrigerant storage container 28a, a pressure adjustment valve 28b, a check valve 28c, a solenoid valve 28d, and an expansion mechanism 28e.

[0075] (2) Detailed configuration (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 also stores 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 a port provided to adjust the pressure inside the refrigerant storage container 28a. The first port 28aa is connected to the refrigerant pipe 20a connecting the port P3 of the flow path switching mechanism 22 and the accumulator 27, and to 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 a suction pipe 21a of the compressor 21 via a 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 a pressure regulating pipe 20b that 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 or exceeds a predetermined value, and releases the high-pressure refrigerant to the accumulator 27.

[0079] (2-3) Check valves and solenoid valves 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 adjustment pipe 20b connected to the discharge pipe 21b of the compressor 21. When the solenoid valve 28d is opened during operation of the compressor 21, the high-pressure refrigerant discharged from the compressor 21 is sent to the refrigerant storage container 28a. The solenoid valve 28d is typically opened when the refrigerant in the refrigerant storage container 28a is filled into the refrigerant circuit 10. The check valve 28c prevents the refrigerant from flowing from the refrigerant storage container 28a to the discharge pipe 21b of the compressor 21. The solenoid valve 28d can be opened and closed by a control unit (not shown). The check valve 28c and the solenoid valve 28d may be a flow rate adjustment mechanism including an electric valve.

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

[0081] (2-5) Relationship between refrigerant charge amount and heat source refrigerant flow path volume Like the heat source unit 2, the heat source unit 2a is in a standalone state, not connected to any of the utilization units 3 or the connection pipes 6 and 7, and 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 an amount that allows the air conditioner 1a to perform refrigeration cycle operation with the required capacity by filling the refrigerant circuit 10. At this time, the filling amount V1 (kg) of refrigerant filled in the heat source refrigerant flow path 20 satisfies the relationship of the above-mentioned (Equation 1) between 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.

[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. V3(L) and the volume V2(L) of the heat source refrigerant flow path 20 satisfy the relationship of the above-mentioned (Equation 2).

[0083] (3) Air conditioner operation In both cooling operation and heating operation, the opening of the expansion mechanism 28e and the solenoid valve 28d is controlled to be fully open or nearly fully open when the refrigerant supply is completed. The opening of the expansion mechanism 28e and the solenoid valve 28d is controlled to be fully closed or nearly fully closed when the refrigerant supply is completed. In this way, the necessary refrigerant is supplied into the refrigerant circuit 10 of the air conditioner 1a. Furthermore, of the refrigerant that was previously filled in the refrigerant storage container 28a, any surplus refrigerant is stored in the refrigerant storage container 28a without being supplied to the refrigerant circuit 10.

[0084] The operation of each other part of the air conditioner 1a during air conditioning operation is similar to that of the air conditioner 1, so description thereof will be omitted.

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

[0086] In the process in which the refrigerant stored in the refrigerant storage container 28a is sent to the refrigerant circuit 10, the openings of the heat source expansion mechanism 24, the solenoid valve 28d, and the expansion mechanism 28e are controlled to be fully open or nearly fully open. When the compressor 21 starts in this state, 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 of the second port 28ab. As a result, the refrigerant that has passed through the expansion mechanism 28e is sucked through the suction pipe 21a of the compressor 21, thereby filling 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 a refrigerant amount adjuster 28, so more refrigerant is filled into the heat source refrigerant flow path 20 compared to the heat source unit 2. For this reason, according to the air conditioning apparatus 1a equipped with the heat source unit 2a, even when multiple utilization units 3 are provided, the heat source unit 2a can sufficiently store the required amount of 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 constitute the air conditioner 1a. The heat source unit 2a includes a compressor 21, a heat source heat exchanger 23, a first shutoff valve 25, a second shutoff 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 in which the compressor 21, the heat source heat exchanger 23, the first shutoff valve 25, the second shutoff valve 26, and the refrigerant amount adjustment unit 28 are connected by a refrigerant pipe 20a. The refrigerant is filled in the heat source refrigerant flow path 20. The refrigerant is carbon dioxide.

[0089] 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 relationship of the above-mentioned (Equation 1).

[0090] Therefore, the heat source unit 2a also prevents the heat-source refrigerant flow path 20 from becoming large, while also preventing the occurrence of pressure abnormalities in the refrigerant flow path caused by the filled carbon dioxide refrigerant becoming supercritical.

[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 the above-mentioned (Equation 3).

[0092] The heat source unit 2a can store refrigerant not only in the heat source refrigerant flow path 20 but also in the accumulator 27 and the refrigerant storage container 28a in the heat source refrigerant flow path 20, thereby ensuring sufficient volume V2 and effectively suppressing the occurrence of pressure abnormalities in the refrigerant flow path.

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

[0094] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure described in the claims. [Explanation of symbols]

[0095] 1, 1a: Air conditioning equipment 2, 2a: Heat source unit 3: Unit of use 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 shutoff valve 26: Second shutoff valve 27: Accumulator (refrigerant storage container) 28: Refrigerant amount adjustment section 28a: Refrigerant storage container L1: First length [Prior art documents] [Patent documents]

[0096] [Patent Document 1] JP 2008-045769 A

Claims

1. A heat source unit (2, 2a) that is connected to a utilization unit (3) and constitutes an air conditioning device (1, 1a), A compressor (21); A heat source heat exchanger (23); A first shutoff valve (25); A second shutoff valve (26); a refrigerant flow path (20) in which the compressor, the heat source heat exchanger, the first shut-off valve, and the second shut-off valve are connected by a refrigerant piping; A refrigerant filled in the refrigerant flow path; Equipped with The refrigerant is Carbon dioxide, The 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 are expressed as follows: 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 Satisfy the relationship Heat source unit.

2. The design pressure P is 10 MPa or more and 14 MPa or less; The heat source unit according to claim 1 .

3. Further comprising a refrigerant storage container (27, 28a) for storing the refrigerant, The volume V3 (L) of the refrigerant storage container is 0.4×V2≦V3<0.9×V2, Satisfy the relationship The heat source unit according to claim 1 .

4. a flow path switching mechanism (22) that switches the direction in which the refrigerant flows in the refrigerant flow path; A refrigerant storage container (27, 28a) for storing the refrigerant; Further comprising: The heat source unit according to claim 1 .

5. The heat source unit according to any one of claims 1 to 4, The utilization unit is connected to the heat source unit via a connection pipe (6, 7); Equipped with The connecting pipe is The length is changed depending on the installation positions of the heat source unit and the utilization unit, a first length (L1) that does not require additional charging of the refrigerant into a refrigerant circuit (10) formed by connecting the heat source unit and the utilization unit via the connection pipe; The heat source unit is The refrigerant is filled in an amount corresponding to a required amount of refrigerant in the refrigerant circuit when the connection pipe has the first length. Air conditioning equipment.

6. The heat source unit according to any one of claims 1 to 4, The utilization unit is connected to the heat source unit via a connection pipe (6, 7); Equipped with The connecting pipe is The length is changed depending on 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 the amount of refrigerant required in a refrigerant circuit (10) formed by connecting the heat source unit and the utilization unit via the connecting pipe when the connecting pipe is shorter than a predetermined first length (L1), Air conditioning equipment.

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