JP2008032275A - Air conditioner - Google Patents

Abstract

In a separate type air conditioner that uses carbon dioxide as a refrigerant enclosed in a refrigerant circuit, an increase in the consumption of airtight gas used in an airtight test performed in the field work is suppressed, and the field work is performed. The workability of is made difficult to be impaired.
SOLUTION: Refrigerant communication pipes 6 and 7 constituting an air conditioner 1 have a pipe outer diameter of 12.7 mm or less when the rated cooling capacity is 11.2 kW or more and 14.0 kW or less. When the cooling capacity is greater than 14.0 kW and less than or equal to 22.4 kW, the outer diameter of the tube is less than 15.9 mm. When the rated cooling capacity is greater than 22.4 kW and less than or equal to 35.5 kW, the tube is used. When the outer diameter is 19.1 mm or less and the rated cooling capacity is greater than 35.5 kW and 45.0 kW or less, the pipe outer diameter is 22.2 mm or less, and the rated cooling capacity is 45. In the case of larger than 0.0 kW and smaller than or equal to 56.0 kW, a tube having an outer diameter of 25.4 mm or smaller is used.
[Selection] Figure 2

Description

  The present invention relates to an air conditioner, and more particularly to a separate air conditioner configured by connecting a heat source unit and a utilization unit via a refrigerant communication pipe.

  Conventionally, there is a separate air conditioner configured by connecting a heat source unit and a utilization unit via a refrigerant communication pipe. In such a separate type air conditioner, on-site construction is performed according to the following procedure.

  First, a heat source unit and a utilization unit are installed, and a refrigerant communication pipe is constructed to constitute a refrigerant circuit. Then, after the refrigerant circuit is configured, an airtight test is performed on a portion (hereinafter, referred to as an airtight test target portion) that is an object of an airtight test of the refrigerant circuit including the refrigerant communication tube using nitrogen gas. And after completion | finish of an airtight test, the nitrogen gas enclosed with the airtight test object part is discharged | emitted outside. Then, after the nitrogen gas is discharged, at least the airtight test target part is evacuated. Then, after the evacuation is completed, a predetermined amount of refrigerant is filled in the refrigerant circuit by additionally filling the refrigerant according to the volume of the refrigerant communication tube or by filling the refrigerant circuit with the refrigerant preliminarily sealed in the heat source unit. The refrigerant will be filled.

Note that the nitrogen gas used in the above-described airtight test is usually supplied from the nitrogen cylinder to the airtight test target portion, and the pressure is increased to the airtight test pressure. For this reason, in the separate type air conditioner, a nitrogen cylinder is prepared according to the volume of the airtight test target portion of the refrigerant circuit including the refrigerant communication pipe.
JP 10-197112 A

  In the separate air conditioner as described above, an HCFC refrigerant such as R22 and an HFC refrigerant such as R407C are often used as the refrigerant sealed in the refrigerant circuit. However, from the viewpoint of environmental problems, the use of natural refrigerants that have a small impact on the environment is also being investigated for separate air conditioners, and the use of carbon dioxide that is nonflammable and nontoxic is particularly promising. ing.

  However, in the separate type air conditioner, when carbon dioxide is used as the refrigerant sealed in the refrigerant circuit, the pressure on the high pressure side in the refrigeration cycle is about 10 MPa, so compared to the case where R22 or R407C is used. The design pressure of the equipment and piping constituting the refrigerant circuit becomes very high. As a result, the airtight test pressure in the airtight test performed at the site of the air conditioner also increases, so the consumption of nitrogen gas used in the airtight test increases, and the nitrogen gas to the airtight test target part increases. It will take time for the supply work and the workability of the local construction will be impaired. In particular, in an air conditioner with a large apparatus capacity such as a multi-type air conditioner in which a plurality of utilization units are connected to one or a plurality of heat source units, a larger amount of nitrogen gas is required. Since a large number of nitrogen cylinders are required and it takes time to replace these nitrogen cylinders, the tendency of the workability of field construction to be impaired becomes remarkable.

  An object of the present invention is to suppress an increase in the consumption of airtight gas used in an airtight test performed in the field work in a separate type air conditioner that uses carbon dioxide as a refrigerant sealed in a refrigerant circuit. This is to make it difficult for the workability of the local construction to be impaired.

  An air conditioner according to a first aspect of the present invention includes one or more heat source units, one or more utilization units, and a refrigerant communication tube that constitutes a refrigerant circuit by connecting the heat source units and the utilization units. In the refrigerant circuit, carbon dioxide is sealed as the refrigerant, and when the rated cooling capacity is 11.2 kW or more and 14.0 kW or less, the refrigerant communication pipe has an outer diameter of 12.7 mm or less. Things are used.

  An air conditioner according to a second aspect of the present invention includes one or more heat source units, one or more utilization units, and a refrigerant communication tube that constitutes a refrigerant circuit by connecting the heat source units and the utilization units. In the refrigerant circuit, carbon dioxide is sealed as a refrigerant, and when the rated cooling capacity is larger than 14.0 kW and equal to or less than 22.4 kW, the outer diameter of the pipe is 15.9 mm as the refrigerant communication pipe. The following are used:

  An air conditioner according to a third aspect of the present invention includes one or more heat source units, one or more utilization units, and a refrigerant communication tube that constitutes a refrigerant circuit by connecting the heat source units and the utilization units. In the refrigerant circuit, carbon dioxide is sealed as a refrigerant, and when the rated cooling capacity is larger than 22.4 kW and not more than 35.5 kW, the outer diameter of the pipe is 19.1 mm as the refrigerant communication pipe. The following are used:

  An air conditioner according to a fourth aspect of the present invention includes one or more heat source units, one or more utilization units, and a refrigerant communication tube that constitutes a refrigerant circuit by connecting the heat source units and the utilization units. In the refrigerant circuit, carbon dioxide is sealed as a refrigerant, and when the rated cooling capacity is greater than 35.5 kW and equal to or less than 45.0 kW, the outer diameter of the pipe is 22.2 mm as the refrigerant communication pipe. The following are used:

  An air conditioner according to a fifth aspect of the present invention includes one or more heat source units, one or more utilization units, and a refrigerant communication tube that constitutes a refrigerant circuit by connecting the heat source units and the utilization units. In the refrigerant circuit, carbon dioxide is enclosed as a refrigerant, and when the rated cooling capacity is larger than 45.0 kW and not more than 56.0 kW, the outer diameter of the pipe is 25.4 mm as the refrigerant communication pipe. The following are used:

  In this air conditioner, carbon dioxide is used as the refrigerant sealed in the refrigerant circuit, and the pressure on the high pressure side in the refrigeration cycle is about 10 MPa. Therefore, the refrigerant is saturated at a lower pressure than carbon dioxide such as R22. Compared to the case of using a refrigerant having pressure characteristics (that is, characteristics having a high boiling point), it is possible to suppress the performance degradation due to the pressure loss of the refrigerant circulating in the refrigerant circuit. Therefore, in this air conditioner, the volume of the refrigerant communication tube can be made as small as possible by reducing the diameter of the refrigerant communication tube within a range where the performance degradation due to pressure loss does not become excessive. Specifically, as described above, when the rated cooling capacity of the air conditioner is 11.2 kW or more and 14.0 kW or less, a refrigerant communication pipe having a pipe outer diameter of 12.7 mm or less is used. Therefore, when the rated cooling capacity of this air conditioner is 14.0 kW or more and 22.4 kW or less, this air conditioner can be used by using a refrigerant communication tube having an outer diameter of 15.9 mm or less. When the rated cooling capacity of the air conditioner is 22.4 kW or more and 35.5 kW or less, a refrigerant communication pipe having an outer diameter of 19.1 mm or less is used, so that the rated cooling capacity of the air conditioner is 35. In the case of 5 kW or more and 45.0 kW or less, the rated cooling capacity of the air conditioner is 45.0 kW or more and 56.0 kW or less by using a refrigerant communication tube having an outer diameter of 22.2 mm or less. In some cases, by using a refrigerant communication pipe having an outer diameter of 25.4 mm or less, the volume of the refrigerant communication pipe can be reduced from 1/3 to 1/4 compared with the case where R22 is used as the refrigerant. Can be about.

  As a result, in this air conditioner, the consumption pressure of airtight gas such as nitrogen gas used in the airtightness test is increased despite the fact that the design pressure of the refrigerant communication pipe is increased by using carbon dioxide as the refrigerant. It is possible to suppress the workability of the local construction.

  Here, the rated cooling capacity refers to the cooling capacity called under the condition of a rated frequency of 60 Hz in an air conditioner equipped with a compressor driven by a constant speed motor, and is a compression driven by an inverter motor. In an air conditioner equipped with an air conditioner, it refers to the cooling capacity referred to under the condition of the maximum frequency during cooling operation.

  An air conditioner according to a sixth aspect is the air conditioner according to any of the first to fifth aspects, wherein the heat source unit can cool the compressor and the refrigerant compressed in the compressor. The heat source side heat exchanger and an auxiliary cooler capable of further cooling the refrigerant cooled in the heat source side heat exchanger.

  Since this air conditioner has an auxiliary cooler that can further cool the refrigerant cooled in the heat source side heat exchanger, the performance is improved by cooling the refrigerant sent to the utilization unit. As a result, it is possible to further reduce the performance degradation caused by reducing the diameter of the refrigerant communication pipe.

  An air conditioner according to a seventh aspect is the air conditioner according to the sixth aspect, wherein the refrigerant communication tube is a first refrigerant communication tube capable of sending the refrigerant cooled in the auxiliary cooler to the utilization unit. And a second refrigerant communication pipe capable of sending the refrigerant from the utilization unit to the heat source unit. The heat source unit is an auxiliary unit capable of depressurizing a part of the refrigerant flowing from the compressor to the first refrigerant communication pipe through the heat source side heat exchanger and the auxiliary cooler, and then returning it to the suction side of the compressor. It has a refrigerant circuit. The auxiliary cooler is a heat exchanger that uses the refrigerant flowing through the auxiliary refrigerant circuit as a cooling source.

  In this air conditioner, since the refrigerant flowing through the auxiliary refrigerant circuit is used as a cooling source for the auxiliary cooler, the refrigerant flowing through the refrigerant circuit is reduced by reducing the flow rate of the refrigerant flowing through the first and second refrigerant communication pipes. The pressure loss can be reduced, and this can further reduce the performance degradation caused by reducing the diameter of the refrigerant communication pipe.

  An air conditioner according to an eighth aspect is the air conditioner according to the seventh aspect, wherein the refrigerant cooled in the heat source side heat exchanger is further cooled by 20 ° C. or more in the auxiliary cooler.

  In this air conditioner, since the refrigerant cooled in the heat source side heat exchanger is further cooled by 20 ° C. or more in the auxiliary cooler, the effect of improving the performance and reducing the pressure loss can be surely obtained. .

  As described above, according to the present invention, the following effects can be obtained.

  In the first to fifth inventions, although carbon dioxide is used as the refrigerant, the consumption pressure of the airtight gas such as nitrogen gas used in the airtight test is increased even though the design pressure of the refrigerant communication pipe is increased. It is possible to suppress the workability of the local construction.

  In 6th and 7th invention, the performance fall resulting from making the pipe diameter of a refrigerant | coolant communication pipe small can be made hard to produce further.

  In the eighth aspect of the invention, the effects of improving performance and reducing pressure loss can be obtained with certainty.

  Hereinafter, embodiments of an air-conditioning apparatus according to the present invention will be described based on the drawings.

(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 is an apparatus used for air conditioning in a room such as a building by performing a vapor compression refrigeration cycle operation. In the present embodiment, the air conditioner 1 connects one heat source unit 2, a plurality (two in this embodiment) of usage units 4 and 5, and the heat source unit 2 and the usage units 4 and 5. A first refrigerant communication pipe 6 and a second refrigerant communication pipe 7 are provided as refrigerant communication pipes. That is, the vapor compression refrigerant circuit 10 and the auxiliary refrigerant circuit 61 (described later) of the air-conditioning apparatus 1 of the present embodiment are connected to the heat source unit 2, the utilization units 4 and 5, and the refrigerant communication pipes 6 and 7. It is a separate type air conditioner configured by the above. Carbon dioxide is sealed as a refrigerant in the refrigerant circuit 10 and the auxiliary refrigerant circuit 61, and after being compressed, cooled, depressurized, and evaporated to a pressure exceeding the critical pressure of the refrigerant, as will be described later. The refrigerating cycle operation of being compressed again is performed.

<Usage unit>
The usage units 4 and 5 are installed in the ceiling of the room by being embedded or suspended, or are installed on the wall surface of the room by wall hanging, etc. Connected to space. The utilization units 4 and 5 are connected to the heat source unit 2 via the refrigerant communication tubes 6 and 7 and constitute a part of the refrigerant circuit 10.

  Next, the configuration of the usage units 4 and 5 will be described. Since the usage unit 4 and the usage unit 5 have the same configuration, only the configuration of the usage unit 4 will be described here, and the configuration of the usage unit 5 is the 40th number indicating each part of the usage unit 4. The reference numerals in the 50s are attached instead of the reference numerals, and description of each part is omitted.

  The usage unit 4 mainly has a usage-side refrigerant circuit 10a (in the usage unit 5, the usage-side refrigerant circuit 10b) that constitutes a part of the refrigerant circuit 10. The use side refrigerant circuit 10 a mainly includes a use side expansion mechanism 41 and a use heat exchanger 42.

  The use side expansion mechanism 41 is a mechanism for decompressing the refrigerant. In this embodiment, the use side expansion mechanism 41 is provided at one end of the use side heat exchanger 42 in order to adjust the flow rate of the refrigerant flowing in the use side refrigerant circuit 10a. It is a connected electric expansion valve. One end of the use side expansion mechanism 41 is connected to the use side heat exchanger 42, and the other end is connected to the first refrigerant communication pipe 6. The use side expansion mechanism 41 is not limited to the electric expansion valve, and may be any as long as it has a function of decompressing the refrigerant.

  The use side heat exchanger 42 is a heat exchanger that functions as a refrigerant heater or cooler. One end of the utilization heat exchanger 42 is connected to the utilization side expansion mechanism 41, and the other end is connected to the second refrigerant communication pipe 7.

  In the present embodiment, the usage unit 4 includes a usage-side fan 43 for sucking indoor air into the unit and supplying it to the room again, and the indoor air and the refrigerant flowing through the usage-side heat exchanger 42 are used. Heat exchange is possible. The use side fan 43 is rotationally driven by a fan motor 43a.

  Further, the usage unit 4 includes a usage-side control unit 44 that controls the operation of each unit constituting the usage unit 4. The usage-side control unit 44 includes a microcomputer, a memory, and the like provided for controlling the usage unit 4, and a remote controller (not shown) for operating the usage unit 4 individually. Control signals and the like can be exchanged between them, and control signals and the like can be exchanged with the heat source unit 2 via the transmission line 8a.

<Heat source unit>
The heat source unit 2 is installed outside and connected to the usage units 4 and 5 via the refrigerant communication pipes 6 and 7, and constitutes a refrigerant circuit 10 between the usage units 4 and 5.

  Next, the configuration of the heat source unit 2 will be described. The heat source unit 2 mainly has a heat source side refrigerant circuit 10 c that constitutes a part of the refrigerant circuit 10. The heat source side refrigerant circuit 10c mainly includes a compressor 21, a switching mechanism 22, a heat source side heat exchanger 23, a heat source side expansion mechanism 24, an auxiliary cooler 25, a first closing valve 26, and a second closing valve 26. And a closing valve 27.

  In this embodiment, the compressor 21 is a hermetic compressor driven by a compressor drive motor 21a. In the present embodiment, the number of the compressors 21 is only one. However, the present invention is not limited to this, and two or more compressors may be connected in parallel according to the number of units used. . Further, an accumulator 28 is provided on the suction side of the compressor 21 in the heat source side refrigerant circuit 10c. The accumulator 28 is connected between the switching mechanism 22 and the compressor 21 and is a container capable of storing surplus refrigerant generated in the refrigerant circuit 10 in accordance with fluctuations in the operating load of the utilization units 4 and 5. It is.

  The switching mechanism 22 is a mechanism for switching the flow direction of the refrigerant in the refrigerant circuit 10, and uses the heat source side heat exchanger 23 as a refrigerant cooler compressed by the compressor 21 during cooling operation. In order for the side heat exchangers 42 and 52 to function as a heater for the refrigerant cooled in the heat source side heat exchanger 23 and the auxiliary cooler 25, the discharge side of the compressor 21 and one end of the heat source side heat exchanger 23 are connected to each other. In addition, the suction side of the compressor 21 and the second closing valve 27 are connected (see the solid line of the switching mechanism 22 in FIG. 1), and the use side heat exchangers 42 and 52 are compressed by the compressor 21 during heating operation. In order to cause the heat source side heat exchanger 23 to function as a refrigerant heater cooled in the use side heat exchangers 42 and 52, the discharge side of the compressor 21 and the second closing valve 27 and It is possible to connect the one end of the suction side and the heat source-side heat exchanger 23 of the compressor 21 as well as continue (see dashed switching mechanism 22 in FIG. 1). In the present embodiment, the switching mechanism 22 is a four-way switching valve connected to the suction side of the compressor 21, the discharge side of the compressor 21, the heat source side heat exchanger 23, and the second closing valve 27. The switching mechanism 22 is not limited to the four-way switching valve, and is configured to have a function of switching the refrigerant flow direction as described above, for example, by combining a plurality of electromagnetic valves. There may be.

  The heat source side heat exchanger 23 is a heat exchanger that functions as a refrigerant cooler or a heater. One end of the heat source side heat exchanger 23 is connected to the switching mechanism 22, and the other end is connected to the heat source side expansion mechanism 24.

  The heat source unit 2 has a heat source side fan 29 for sucking outdoor air into the unit and discharging it outside the room again. The heat source side fan 29 can exchange heat between the outdoor air and the refrigerant flowing through the heat source side heat exchanger 23. The heat source side fan 29 is rotationally driven by a fan motor 29a. Note that the heat source of the heat source side heat exchanger 23 is not limited to outdoor air, and may be another heat medium such as water.

  The heat source side expansion mechanism 24 is a mechanism for decompressing the refrigerant. In the present embodiment, the other end of the heat source side heat exchanger 23 is used to adjust the flow rate of the refrigerant flowing in the heat source side refrigerant circuit 10c. It is an electric expansion valve connected to. The heat source side expansion mechanism 24 has one end connected to the heat source side heat exchanger 23 and the other end connected to the auxiliary cooler 25. The heat source side expansion mechanism 24 is not limited to the electric expansion valve, and may be any one having a function of depressurizing the refrigerant. The heat source side refrigerant circuit 10c is provided with a check mechanism 30 so as to bypass the heat source side expansion mechanism 24. The check mechanism 30 is a mechanism that allows the refrigerant flow in one direction and blocks the refrigerant flow in the reverse direction. In the present embodiment, the check mechanism 30 changes from the heat source side heat exchanger 23 to the auxiliary cooler 25. The check valve is provided so as to block the refrigerant flow from the auxiliary cooler 25 to the heat source side heat exchanger 23 while allowing the refrigerant to flow.

  The auxiliary cooler 25 is a heat exchanger that can further cool the refrigerant cooled in the heat source side heat exchanger 23. The auxiliary cooler 25 has one end connected to the heat source side heat exchanger 23 and the other end connected to the first closing valve 26. In the present embodiment, the auxiliary cooler 25 is a double-pipe heat exchanger. . Further, in the heat source side refrigerant circuit 10c, a part of the refrigerant flowing from the compressor 21 to the first closing valve 26 through the heat source side heat exchanger 23 and the auxiliary cooler 25 is decompressed, and then the suction side of the compressor 21 is provided. An auxiliary refrigerant circuit 61 that can be returned to is provided. In the present embodiment, the auxiliary refrigerant circuit 61 branches a part of the refrigerant flowing between the heat source side expansion mechanism 24 and the auxiliary cooler 25 from the refrigerant circuit 10 so as to suck the compressor 21 (more specifically, And between the switching mechanism 22 and the accumulator 28). The auxiliary refrigerant circuit 61 is branched from a position between the heat source side expansion mechanism 24 and the auxiliary cooler 25 and reaches the inlet of the auxiliary cooler 25 on the auxiliary cooling circuit 61 side. A junction circuit 61 b that joins from the outlet on the cooling circuit 61 side to a position between the switching mechanism 22 and the accumulator 28 is provided. An auxiliary expansion mechanism 62 is provided in the branch circuit 61a. The auxiliary expansion mechanism 62 is a mechanism for decompressing the refrigerant, and is an electric expansion valve provided for adjusting the flow rate of the refrigerant flowing through the auxiliary refrigerant circuit 61 in the present embodiment. Thereby, a part of the refrigerant cooled in the heat source side heat exchanger 23 is bypassed to the suction side of the compressor 21 by the auxiliary refrigerant circuit 61, and the refrigerant flowing through the auxiliary refrigerant circuit 61 in the auxiliary cooler 25. It is further cooled by using as a cooling source.

  The first closing valve 26 is a valve to which the first refrigerant communication pipe 6 for exchanging refrigerant between the heat source unit 2 and the utilization units 4 and 5 is connected, and is connected to the auxiliary cooler 25. The second closing valve 27 is a valve to which the second refrigerant communication pipe 7 for exchanging refrigerant between the heat source unit 2 and the utilization units 4 and 5 is connected, and is connected to the switching mechanism 22. Here, the first and second closing valves 26 and 27 are three-way valves provided with service ports that can communicate with the outside of the refrigerant circuit 10.

  The heat source unit 2 is provided with various sensors. Specifically, when the heat source side heat exchanger 23 is caused to function as a refrigerant cooler in the heat source unit 2, the heat source side heat exchange that detects the refrigerant temperature Tco is provided at the outlet of the heat source side heat exchanger 23. A vessel temperature sensor 31 is provided. When the auxiliary cooler 25 is caused to function as a cooler that further cools the refrigerant cooled in the heat source side heat exchanger 23, an auxiliary that detects the refrigerant temperature Tsc is provided at the outlet of the auxiliary cooler 25 on the refrigerant circuit 10 side. A cooler temperature sensor 32 is provided. In the present embodiment, the heat source side heat exchanger temperature sensor 31 and the auxiliary cooler temperature sensor 32 are composed of thermistors. In addition, the heat source unit 2 includes a heat source side control unit 33 that controls the operation of each unit constituting the heat source unit 2. The heat source side control unit 33 includes a microcomputer, a memory, and the like provided for controlling the heat source unit 2, and is transmitted between the use side control units 44 and 54 of the use units 4 and 5. Control signals and the like can be exchanged via the line 8a.

<Refrigerant communication pipe>
The refrigerant communication pipes 6 and 7 are refrigerant pipes that are constructed on site when the air conditioner 1 is installed at the installation location. The first refrigerant communication pipe 6 is a junction pipe connecting the branch pipes 6a and 6b connected to the respective usage units 4 and 5 and a portion where the branch pipe 6a and the branch pipe 6b merge with the first closing valve 26. 6c. The second refrigerant communication pipe 7 is a junction pipe connecting the branch pipes 7a and 7b connected to the respective use units 4 and 5 and a portion where the branch pipe 7a and the branch pipe 7b merge with the second closing valve 27. 7c. And the total amount of the refrigerant | coolant exchanged between the utilization units 4 and 5 and the heat source unit 2 flows into the junction pipes 6c and 7c. That is, when each of the refrigerant communication pipes 6 and 7 is connected to a single heat source unit 2 as in the present embodiment, a plurality of usage units 4 and 5 and Each has a joining pipe 6c, 7c that is a part through which the entire amount of refrigerant exchanged with the heat source unit 2 flows, and exchange of refrigerant between the plurality of usage units 4, 5 and the heat source unit 2 is as follows: Except for the parts close to the use units 4 and 5, the operation is generally performed by the junction pipes 6c and 7c. In addition, unlike this embodiment, when one utilization unit is connected to one heat source unit, each refrigerant | coolant communication pipe | tube is only by the part corresponded to the merge pipes 6c and 7c in this embodiment. The refrigerant is exchanged between the use unit and the heat source unit. In addition, when one utilization unit is connected to a plurality of heat source units, each refrigerant communication tube has a plurality of heat sources corresponding to the branch pipes 6a, 6b, 7a, 7b in the present embodiment. In addition to being provided for branching between the units, the parts corresponding to the junction pipes 6c and 7c in the present embodiment are provided so as to connect the parts corresponding to these branch pipes and the utilization unit. The refrigerant is exchanged between the utilization unit and the heat source unit by the portion corresponding to the joining pipes 6c and 7c in the embodiment. Furthermore, when a plurality of utilization units are connected to a plurality of heat source units, each refrigerant communication pipe has a plurality of portions corresponding to the branch pipes 6a, 6b, 7a, 7b in the present embodiment. Provided for branching between units and for branching between multiple heat source units, and connecting between the part corresponding to the branch pipe on the heat source unit side and the part corresponding to the branch pipe on the use unit side Thus, portions corresponding to the junction pipes 6c and 7c in the present embodiment are provided, and the exchange of refrigerant between the utilization unit and the heat source unit is substantially performed by the portions corresponding to the junction pipes 6c and 7c in the present embodiment. Will be made.

  As described above, these refrigerant communication pipes 6 and 7 have various pipe diameters and lengths depending on the apparatus capacity conditions and the installation site conditions determined by the combination of the utilization unit and the heat source unit. Will be.

  And in this embodiment, as FIG. 2 shows, the pipe diameter of the refrigerant | coolant communication pipes 6 and 7 is selected according to a rated cooling capability. Here, the rated cooling capacity refers to the cooling capacity called under the condition of a rated frequency of 60 Hz when the compressor drive motor 21a is a constant speed motor, and when the compressor drive motor 21a is an inverter motor. Means the cooling capacity referred to under the condition of the maximum frequency during cooling operation. The value of the diameter of the first refrigerant communication pipe 6 shown in FIG. 2 is the first refrigerant communication pipe excluding members such as pipe joints for connecting the branch pipes 6a, 6b and the merge pipe 6c. 6 (that is, the maximum value of the pipe diameter of the merge pipe 6c), and the branch pipes 6a and 6b are refrigerant pipes having a pipe diameter smaller than that shown in FIG. Is done. Further, the value of the diameter of the second refrigerant communication pipe 7 shown in FIG. 2 is the second refrigerant communication pipe excluding members such as pipe joints for connecting the branch pipes 7a and 7b and the merge pipe 7c. 7 (that is, the maximum value of the pipe diameter of the merge pipe 7c), and the branch pipes 7a and 7b are refrigerant pipes having a pipe diameter smaller than the pipe diameter shown in FIG. Is used. In FIG. 2, the outer diameter D and the inner diameter d are shown as the tube diameter values. Among these, the inner diameter d takes into consideration the refrigerant pressure (about 10 MPa) on the high pressure side in the refrigeration cycle operation. The values of the tube diameter excluding the tube thickness when the design pressure of the refrigerant communication tubes 6 and 7 is set to 12 MPa are shown. The reason why the pipe diameter value of the second refrigerant communication pipe 7 is larger than the pipe diameter value of the first refrigerant communication pipe 6 is that during the cooling operation, the second refrigerant communication pipe 7 has a low pressure ( This is because a gas state refrigerant of about 4 MPa flows. For this reason, the refrigerant | coolant communication pipes 6 and 7 of the air conditioning apparatus 1 use the refrigerant | coolant pipe | tube which has a pipe diameter below the pipe diameter value of the 2nd refrigerant | coolant communication pipe | tube 7 shown by FIG. FIG. 2 is a table showing the relationship between the rated cooling capacity and the diameters of the refrigerant communication pipes 6 and 7. Both of the refrigerant communication pipes 6 and 7 are phosphorus-deoxidized copper seamless copper pipes (JIS C1220T). -1 / 2H) is used.

  Thereby, when the rated cooling capacity of the air conditioner 1 is 11.2 kW or less, the pipe outer diameter D is 12.7 mm or less (or the pipe inner diameter d is 10.4 mm as the refrigerant communication pipes 6 and 7 as a whole. The following is used. More specifically, the first refrigerant communication pipe 6 has a pipe outer diameter D of 6.35 mm (or a pipe inner diameter d of 5.15 mm or less). As the second refrigerant communication pipe 7, a pipe having a pipe outer diameter D of 12.7 mm or less (or a pipe inner diameter d of 10.4 mm or less) is used.

  When the rated cooling capacity of the air conditioner 1 is 11.2 kW or more and 14.0 kW or less, the refrigerant communication pipes 6 and 7 as a whole have a pipe outer diameter D of 12.7 mm or less (or a pipe inner diameter d of 10.4 mm or less), more specifically, the first refrigerant communication tube 6 has a tube outer diameter D of 7.94 mm (or a tube inner diameter d of 6.44 mm or less). For the second refrigerant communication pipe 7, a pipe having a pipe outer diameter D of 12.7 mm or less (or a pipe inner diameter d of 10.4 mm or less) is used.

  When the rated cooling capacity of the air conditioner 1 is greater than 14.0 kW and 16.0 kW or less, the refrigerant communication tubes 6 and 7 as a whole have a tube outer diameter D of 15.9 mm or less (or a tube inner diameter). d is 13.0 mm or less). More specifically, the first refrigerant communication tube 6 has a tube outer diameter D of 7.94 mm (or a tube inner diameter d of 6.44 mm). The following is used, and the second refrigerant communication pipe 7 has a pipe outer diameter D of 15.9 mm or less (or a pipe inner diameter d of 13.0 mm or less).

  Further, when the rated cooling capacity of the air conditioner 1 is greater than 16.0 kW and 22.4 kW or less, the refrigerant communication tubes 6 and 7 as a whole have a tube outer diameter D of 15.9 mm or less (or a tube inner diameter). d is 13.0 mm or less). More specifically, the first refrigerant communication tube 6 has a tube outer diameter D of 9.52 mm (or a tube inner diameter d of 7.72 mm). The following is used, and the second refrigerant communication pipe 7 has a pipe outer diameter D of 15.9 mm or less (or a pipe inner diameter d of 13.0 mm or less).

  When the rated cooling capacity of the air conditioner 1 is greater than 22.4 kW and equal to or less than 28.0 kW, the refrigerant communication tubes 6 and 7 as a whole have a tube outer diameter D of 19.1 mm or less (or a tube inner diameter). d is 15.6 mm or less). More specifically, the first refrigerant communication tube 6 has a tube outer diameter D of 9.52 mm (or a tube inner diameter d of 7.72 mm). The following is used, and the second refrigerant communication pipe 7 is one having a pipe outer diameter D of 19.1 mm or less (or a pipe inner diameter d of 15.6 mm or less).

  When the rated cooling capacity of the air conditioner 1 is greater than 28.0 kW and 35.5 kW or less, the outer diameter D of the refrigerant communication tubes 6 and 7 as a whole is 19.1 mm or less (or the inner diameter of the tube). d is 15.6 mm or less). More specifically, the first refrigerant communication tube 6 has a tube outer diameter D of 12.7 mm (or a tube inner diameter d of 10.4 mm). The following is used, and the second refrigerant communication pipe 7 is one having a pipe outer diameter D of 19.1 mm or less (or a pipe inner diameter d of 15.6 mm or less).

  When the rated cooling capacity of the air conditioner 1 is greater than 35.5 kW and equal to or less than 45.0 kW, the refrigerant communication tubes 6 and 7 as a whole have a tube outer diameter D of 22.2 mm or less (or a tube inner diameter). d is 18.2 mm or less). More specifically, the first refrigerant communication tube 6 has a tube outer diameter D of 12.7 mm (or a tube inner diameter d of 10.4 mm). The following is used, and the second refrigerant communication tube 7 is one having a tube outer diameter D of 22.2 mm or less (or a tube inner diameter d of 18.2 mm or less).

  When the rated cooling capacity of the air conditioner 1 is greater than 45.0 kW and 56.0 kW or less, the refrigerant communication pipes 6 and 7 as a whole have a pipe outer diameter D of 25.4 mm or less (or pipe inner diameter). d is 20.8 mm or less). More specifically, the first refrigerant communication tube 6 has a tube outer diameter D of 12.7 mm (or a tube inner diameter d of 10.4 mm). The following is used, and the second refrigerant communication tube 7 has a tube outer diameter D of 25.4 mm or less (or a tube inner diameter d of 20.8 mm or less).

  As described above, the use side refrigerant circuits 10 a and 10 b, the heat source side refrigerant circuit 10 c, and the refrigerant communication pipes 6 and 7 are connected, and the auxiliary refrigerant circuit 61 and the refrigerant circuit 10 are configured. And the air conditioning apparatus 1 of this embodiment is various operation | movement of the air conditioning apparatus 1 by the transmission line 8a which connects between utilization side control part 44,54, the heat source side control part 33, and control part 33,44,54. A control unit 8 is configured as control means for performing control. As shown in FIG. 3, the control unit 8 is connected so as to receive detection signals of the various sensors 31 and 32, and various devices and valves 21, 22, and 24 based on these detection signals and the like. , 29, 41, 43, 51, 53, 62 can be controlled. Here, FIG. 3 is a control block diagram of the air conditioner 1.

(2) Field work of air conditioner Next, the field work of the air conditioner 1 will be described.

<Equipment installation (refrigerant circuit configuration)>
First, the use units 4 and 5 and the heat source unit 2 are installed at the installation location, the refrigerant communication pipes 6 and 7 are installed, connected to the use units 4 and 5 and the heat source unit 2, and the refrigerant circuit 10 of the air conditioner 1 is installed. Constitute. Here, the shutoff valves 26 and 27 of the heat source unit 2 are closed, and the heat source side refrigerant circuit 10c and the refrigerant communication pipes 6 and 7 are not in communication with each other. In addition, carbon dioxide as a refrigerant is enclosed in the heat source side refrigerant circuit 10c of the heat source unit 2 in advance.

<Airtight test>
After the refrigerant circuit 10 of the air conditioner 1 is configured, an airtight test of the refrigerant communication tubes 6 and 7 is performed. In addition, when the utilization units 4 and 5 and the refrigerant | coolant communication pipes 6 and 7 are connected, the airtight test of the refrigerant | coolant communication pipes 6 and 7 is performed in the state which the utilization units 4 and 5 connected.

  First, nitrogen gas as an airtight gas is supplied to the airtight test target portion of the refrigerant circuit 10 including the refrigerant communication pipes 6 and 7 to raise the airtight test target portion to the airtight test pressure. In the present embodiment, the nitrogen gas is supplied by connecting the nitrogen cylinder 9 to the service port of the second closing valve 27 as shown in FIG. The place where the nitrogen cylinder 9 is connected is not limited to the service port of the second closing valve 27, but may be the service port of the first closing valve 26, or a separate charge port is provided in the refrigerant communication pipes 6 and 7. If so, a nitrogen cylinder 9 may be connected to this charge port. Then, after stopping the supply of nitrogen gas, it is confirmed that the airtight test pressure is maintained for a predetermined test time for the airtight test target portion. FIG. 4 is a refrigerant circuit diagram showing a state in which a nitrogen cylinder is connected in the airtight test.

  Here, in the air conditioner 1, as described above, carbon dioxide is used as the refrigerant, and the pressure on the high pressure side in the refrigeration cycle becomes a pressure exceeding the critical pressure (about 10 MPa). The design pressure of the equipment and piping of the refrigerant circuit 10 and the auxiliary refrigerant circuit 61 through which the refrigerant of the side pressure flows is set to a higher pressure, and accordingly, the airtight test pressure is also set to a high pressure according to the design pressure. Has been. In this embodiment, the design pressure on the high pressure side of the refrigerant circuit 10 and the auxiliary refrigerant circuit 61 is set to 12 MPa, and the airtight test target portion including the refrigerant communication pipes 6 and 7 includes the high pressure side in the refrigeration cycle. Since the refrigerant of pressure flows, the airtight test pressure is also set to 12 MPa, which is the same as the design pressure on the high pressure side. For this reason, compared with the case where R22 or R407C is used as a refrigerant, the consumption of nitrogen gas used in the airtight test tends to increase.

  However, in this embodiment, as shown in FIGS. 2 and 5, the pipe diameters of the refrigerant communication pipes 6 and 7 are selected so as to be smaller than when R22 or R407C is used as the refrigerant. Therefore, although the design pressure of the refrigerant communication pipes 6 and 7 is increased by using carbon dioxide as a refrigerant, an increase in consumption of nitrogen gas in the airtight test is suppressed.

  Specifically, for the refrigerant communication pipes 6 and 7, if a refrigerant pipe having the same pipe inner diameter d as that when R22 is used as the refrigerant is used, as shown in FIG. However, when the rated cooling capacity is in the range of 11.2 kW to 56.0 kW, the length of the refrigerant communication pipes 6 and 7 is generally used. 3 to 7 and a large number of pipes as in the refrigerant communication pipes 6 and 7 of this embodiment (that is, as shown in FIG. 2). As shown in FIG. 6, the volume V1 of the refrigerant communication pipes 6 and 7 is set to R22 as the refrigerant (the volume of the refrigerant communication pipes 6 and 7 in this case is set to the volume V2). ) To about 1/3 to 1/4 It can be as becomes, as a result, the use number of nitrogen cylinder, rated cooling capacity in the range of 11.2KW～56.0KW, can be reduced to two to three fibers per 100m refrigerant communication pipe. As a result, an increase in the amount of nitrogen gas consumed in the airtight test can be suppressed, and an increase in labor for replacing the nitrogen cylinders can be suppressed as much as possible. Moreover, since the weight of the refrigerant communication pipes 6 and 7 themselves can be reduced, it is possible to contribute to a reduction in material cost of the refrigerant communication pipes 6 and 7. FIG. 5 is a table showing the relationship between the rated cooling capacity and the diameter of the refrigerant communication pipe when R22 is used as the refrigerant. FIG. 6 is a table comparing the case where the refrigerant communication tube according to the present invention is used and the case where the refrigerant tube having the same pipe inner diameter is used as the refrigerant communication tube when R22 is used as the refrigerant.

<Airtight gas release>
After the airtight test is completed, in order to reduce the pressure in the airtight test target part, nitrogen gas in the airtight test target part is released into the atmosphere. Here, in the atmospheric discharge operation, in order to prevent the intrusion of air from the outside of the refrigerant circuit 10, the pressure in the airtight test target portion including the refrigerant communication tubes 6 and 7 is reduced until the pressure becomes slightly higher than the atmospheric pressure. is doing.

<Evacuation>
After the release of the nitrogen gas, in order to completely remove the nitrogen gas from the target portion of the hermetic test, a vacuum pump is connected to the service ports of the closing valves 26 and 27, etc. Vacuum the part.

<Refrigerant filling>
After the evacuation is completed, the operation of filling the refrigerant circuit 10 as a whole with the refrigerant sealed in the heat source side refrigerant circuit 10c by opening the closing valves 26 and 27 is performed. Further, as in the case where the refrigerant communication pipes 6 and 7 have a long pipe length or the like, when only the refrigerant quantity preliminarily sealed in the heat source side refrigerant circuit 10c is not sufficient for the refrigerant circuit 10 as a whole, The operation of additionally filling the refrigerant from the outside is performed by connecting a refrigerant cylinder to the service port of the closure valves 26 and 27 or the like before or after the operation of opening the closure valves 26 and 27 described above.

(3) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 of this embodiment is demonstrated.

<Cooling operation>
During the cooling operation, the switching mechanism 22 is in the state indicated by the solid line in FIG. 1, that is, the discharge side of the compressor 21 is connected to the heat source side heat exchanger 23, and the suction side of the compressor 21 is connected to the second closing valve 27. Connected. The heat source side expansion mechanism 24 is fully closed. The closing valves 26 and 27 are opened. The opening degree of each use side expansion mechanism 41, 51 is adjusted according to the load of the use side heat exchangers 42, 52. Further, the auxiliary expansion mechanism 62 has a refrigerant temperature Tsc at the outlet on the refrigerant circuit 10 side of the auxiliary cooler 25 that is 20 ° C. or higher than the refrigerant temperature Tco at the outlet of the heat source side heat exchanger 23 that functions as a refrigerant cooler. The opening degree is adjusted to be lower. The opening degree control of the auxiliary expansion mechanism 62 can be performed by using various operation state quantities of the refrigerant circuit 10 and the auxiliary refrigerant circuit 61. In the present embodiment, the heat source that detects the temperature Tco is used. The temperature difference ΔT is obtained by subtracting the value of Tsc from the value of Tco using the side heat exchanger temperature sensor 31 and the auxiliary cooler temperature sensor 32 that detects the temperature Tsc, and the temperature difference ΔT is less than 20 ° C. In such a case, control for increasing the opening degree of the auxiliary expansion mechanism 62 is performed.

  When the compressor 21, the heat source side fan 29, and the use side fans 43 and 53 are started in the state of the refrigerant circuit 10 and the auxiliary refrigerant circuit 61, the low-pressure (about 4 MPa) refrigerant is sucked into the compressor 21 and the critical pressure is reached. The refrigerant is compressed to a pressure exceeding 10 to become a high-pressure (about 10 MPa) refrigerant. Thereafter, the high-pressure refrigerant is sent to the heat source side heat exchanger 23 via the switching mechanism 22 and is cooled by exchanging heat with outdoor air supplied by the heat source side fan 29. Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 23 passes through the check mechanism 30, flows into the auxiliary cooler 25, and performs heat exchange with the refrigerant flowing through the auxiliary refrigerant circuit 61, and further 20 ° C. Cooled above. At this time, a part of the high-pressure refrigerant cooled in the heat source side heat exchanger 23 is branched to the auxiliary refrigerant circuit 61, decompressed by the auxiliary expansion mechanism 62, and then returned to the suction side of the compressor 21. The refrigerant flowing from the outlet of the auxiliary expansion mechanism 62 of the auxiliary refrigerant circuit 61 toward the suction side of the compressor 21 exchanges heat with the high-pressure refrigerant flowing through the refrigerant circuit 10 when passing through the auxiliary cooler 25. Go and be heated.

  The high-pressure refrigerant cooled in the auxiliary cooler 25 is sent to the use units 4 and 5 via the first closing valve 26 and the first refrigerant communication pipe 6. The high-pressure refrigerant sent to the use units 4 and 5 is decompressed by the use-side expansion mechanisms 41 and 51 to become a low-pressure gas-liquid two-phase refrigerant and sent to the use-side heat exchangers 42 and 52. In each of the use side heat exchangers 42 and 52, heat is exchanged with room air to be heated to evaporate into a low-pressure refrigerant.

  The low-pressure refrigerant heated in the use side heat exchangers 42 and 52 is sent to the heat source unit 2 via the second refrigerant communication pipe 7, and then accumulated via the second closing valve 27 and the switching mechanism 22. 28 flows in. Then, the low-pressure refrigerant that has flowed into the accumulator 28 is again sucked into the compressor 21.

<Heating operation>
During the heating operation, the switching mechanism 22 is in the state indicated by the broken line in FIG. 1, that is, the discharge side of the compressor 21 is connected to the second closing valve 27, and the suction side of the compressor 21 is connected to the heat source side heat exchanger 23. Connected. The opening degree of the heat source side expansion mechanism 24 is adjusted to reduce the pressure to a pressure at which the refrigerant can be evaporated in the heat source side heat exchanger 23. Moreover, the 1st closing valve 26 and the 2nd closing valve 27 are made into the open state. The use-side expansion mechanisms 41 and 51 are adjusted in opening according to the loads on the use-side heat exchangers 42 and 52. The auxiliary expansion mechanism 62 is closed.

  When the compressor 21, the heat source side fan 29, and the use side fans 43 and 53 are started in the state of the refrigerant circuit 10 and the auxiliary refrigerant circuit 61, the low-pressure (about 4 MPa) refrigerant is sucked into the compressor 21 and the critical pressure is reached. The refrigerant is compressed to a pressure exceeding 10 to become a high-pressure (about 10 MPa) refrigerant. The high-pressure refrigerant is sent to the use units 4 and 5 via the switching mechanism 22, the second closing valve 27 and the second refrigerant communication pipe 7.

  The high-pressure refrigerant sent to the usage units 4 and 5 is cooled by exchanging heat with room air in the usage-side heat exchangers 42 and 52, and then passes through the usage-side expansion mechanisms 41 and 51. At that time, the pressure is reduced according to the opening degree of each of the use side expansion mechanisms 41 and 51.

  The refrigerant that has passed through the use side expansion mechanisms 41 and 51 is sent to the heat source unit 2 via the first refrigerant communication pipe 6, and passes through the first closing valve 26, the auxiliary cooler 25, and the heat source side expansion mechanism 24. After the pressure is further reduced, the heat flows into the heat source side heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant that has flowed into the heat source side heat exchanger 23 evaporates by heat exchange with the outdoor air supplied by the heat source side fan 29 to become a low pressure refrigerant. Then, it flows into the accumulator 24 via the switching mechanism 22. Then, the low-pressure refrigerant that has flowed into the accumulator 24 is again sucked into the compressor 21.

  The operation control in the cooling operation and the heating operation as described above is performed by the control unit 8 (more specifically, the use side control units 44 and 54, the heat source side control unit 33, and the control units 33 and 44, which function as operation control means. The transmission line 8a) connecting the 54.

(4) Features of the air conditioner The air conditioner 1 of the present embodiment has the following features.

(A)
In the air conditioner 1 of the present embodiment, carbon dioxide is used as the refrigerant sealed in the refrigerant circuit 10 and the auxiliary refrigerant circuit 61, and the pressure on the high pressure side in the refrigeration cycle is about 10 MPa. Compared to the case of using a refrigerant having a saturation pressure characteristic lower than that of carbon dioxide such as R22 (that is, a characteristic having a high boiling point), it is possible to suppress the performance deterioration due to the pressure loss of the refrigerant circulating in the refrigerant circuit 10. become. Therefore, in this air conditioner 1, the volume of the refrigerant communication pipes 6 and 7 can be reduced as much as possible by reducing the diameter of the refrigerant communication pipes 6 and 7 within a range in which the performance degradation due to pressure loss does not become excessive. .

  Specifically, when the rated cooling capacity is 11.2 kW or more and 14.0 kW or less, the refrigerant communication pipes 6 and 7 as a whole have a pipe outer diameter D of 12.7 mm or less (pipe inner diameter d of 10.4 mm or less). When the rated cooling capacity is greater than 14.0 kW and 22.4 kW or less, the refrigerant communication tubes 6 and 7 as a whole have a tube outer diameter D of 15.9 mm or less (the tube inner diameter d is 13). When the rated cooling capacity is larger than 22.4 kW and smaller than or equal to 35.5 kW, the outer diameter D of the refrigerant communication tubes 6 and 7 as a whole is smaller than or equal to 19.1 mm (pipe). When the rated cooling capacity is greater than 35.5 kW and 45.0 kW or less, the outer diameter D of the refrigerant communication tubes 6 and 7 as a whole is 22. 2 mm or less (tube inner diameter d is 18. When the rated cooling capacity is greater than 45.0 kW and 56.0 kW or less, the outer diameter D of the refrigerant communication pipes 6 and 7 is 25.4 mm or less (the inner diameter of the pipe). By using a tube having d of 25.4 mm or less, the volume of the refrigerant communication pipes 6 and 7 can be reduced to about 1/3 to 1/4 compared with the case where R22 is used as the refrigerant.

  Thereby, in this air conditioner 1, the consumption of airtight gas such as nitrogen gas used in the airtightness test is increased despite the fact that the design pressure of the refrigerant communication pipes 6 and 7 is increased by using carbon dioxide as the refrigerant. The increase in the amount can be suppressed, and the workability of the local construction can be made difficult to be impaired.

(B)
In the air conditioner 1 of this embodiment, since the auxiliary cooler 25 capable of further cooling the refrigerant cooled in the heat source side heat exchanger 23 is provided, the refrigerant sent to the utilization units 4 and 5 is cooled. As a result, the performance can be improved, thereby making it possible to further reduce the performance degradation caused by reducing the diameters of the refrigerant communication pipes 6 and 7.

  Moreover, since the refrigerant flowing through the auxiliary refrigerant circuit 61 is used as a cooling source for the auxiliary cooler 25, the flow rate of the refrigerant flowing through the first and second refrigerant communication pipes 6 and 7 is reduced, and the inside of the refrigerant circuit 10 is reduced. The pressure loss of the circulating refrigerant can be reduced, thereby making it possible to further reduce the performance degradation caused by reducing the diameter of the refrigerant communication pipes 6 and 7.

  In particular, in the air conditioner 1 of the present embodiment, the refrigerant cooled in the heat source side heat exchanger 23 is further cooled by 20 ° C. or more in the auxiliary cooler 25, so that the performance is improved and the pressure loss is reduced. The effect can be obtained reliably.

(5) Modified Example In the above-described embodiment, the auxiliary refrigerant circuit 61 in which the refrigerant as the cooling source of the auxiliary cooler 25 flows passes a part of the refrigerant flowing between the heat source side expansion mechanism 24 and the auxiliary cooler 25. Although it is provided so as to be branched from the refrigerant circuit 10 and returned to the suction side of the compressor 21, a refrigerant capable of further cooling the refrigerant cooled in the heat source side heat exchanger 23 can be supplied. In addition, since it is sufficient that the flow rate of the refrigerant flowing through the first and second refrigerant communication pipes 6 and 7 can be reduced, as illustrated in FIG. 7, a gap between the heat source side heat exchanger 23 and the heat source side expansion mechanism 24 is provided. A part of the flowing refrigerant may be branched from the refrigerant circuit 10 and returned to the suction side of the compressor 21.

  Further, as shown in FIG. 8, the auxiliary refrigerant circuit 61 branches a part of the refrigerant flowing between the auxiliary cooler 25 and the first closing valve 26 from the refrigerant circuit 10 to the suction side of the compressor 21. It may be provided to return.

  In this case, the processing flow rate of the refrigerant flowing through the refrigerant circuit 10 side of the auxiliary cooler 25 is increased as compared with the above-described embodiment, but not only in the heat source side heat exchanger 23 but also in the auxiliary cooler 25. The refrigerant flowing on the refrigerant circuit 10 side of the auxiliary cooler 25 can be cooled using the cooled refrigerant.

  Further, as shown in FIG. 9, the auxiliary refrigerant circuit 61 may be provided to branch a part of the refrigerant flowing in the heat source side heat exchanger 23 and return it to the suction side of the compressor 21.

  In this case, since the processing flow rate of the refrigerant in the heat source side heat exchanger 23 on the downstream side of the connection portion of the auxiliary refrigerant circuit 61 is reduced, the heat source side heat exchange on the downstream side of the connection portion of the auxiliary refrigerant circuit 61 is reduced. Cooling of the refrigerant in the vessel 23 can be promoted.

(6) Other Embodiments While the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments and can be changed without departing from the scope of the invention. It is.

  By using the present invention, in a separate type air conditioner that uses carbon dioxide as a refrigerant enclosed in a refrigerant circuit, an increase in the consumption of airtight gas used in an airtight test performed at the time of on-site construction can be reduced. It is possible to suppress the workability of the local construction.

1 is a schematic refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention. It is a table | surface which shows the relationship between the rated cooling capability in this invention, and the pipe diameter of a refrigerant | coolant connecting pipe. It is a control block diagram of an air conditioning apparatus. It is a refrigerant circuit figure which shows the state in which the nitrogen cylinder was connected in the airtight test. It is a table | surface which shows the relationship between the rated cooling capability at the time of using R22 as a refrigerant | coolant, and the pipe diameter of a refrigerant | coolant connecting pipe. It is the table | surface which compared the case where the refrigerant | coolant communication pipe | tube in this invention is used, and the case where the refrigerant | coolant pipe | tube of the same pipe | tube internal diameter is used as a refrigerant | coolant communication pipe | tube when using R22 as a refrigerant | coolant. It is a schematic refrigerant circuit figure of the air conditioning apparatus concerning the modification of this invention. It is a schematic refrigerant circuit figure of the air conditioning apparatus concerning the modification of this invention. It is a schematic refrigerant circuit figure of the air conditioning apparatus concerning the modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Heat source unit 4, 5 Use unit 6, 7 Refrigerant communication pipe 10 Refrigerant circuit 21 Compressor 23 Heat source side heat exchanger 25 Auxiliary cooler 61 Auxiliary refrigerant circuit

Claims (8)

One or more heat source units (2);
One or more usage units (4, 5);
A refrigerant communication pipe (6, 7) constituting a refrigerant circuit (10) by connecting the heat source unit and the utilization unit;
In the refrigerant circuit, carbon dioxide is sealed as a refrigerant,
When the rated cooling capacity is 11.2 kW or more and 14.0 kW or less, a pipe having a pipe diameter of 12.7 mm or less is used as the refrigerant communication pipe.
Air conditioner (1). One or more heat source units (2);
One or more usage units (4, 5);
A refrigerant communication pipe (6, 7) constituting a refrigerant circuit (10) by connecting the heat source unit and the utilization unit;
In the refrigerant circuit, carbon dioxide is sealed as a refrigerant,
When the rated cooling capacity is greater than 14.0 kW and 22.4 kW or less, the refrigerant communication tube having a tube diameter of 15.9 mm or less is used.
Air conditioner (1). One or more heat source units (2);
One or more usage units (4, 5);
A refrigerant communication pipe (6, 7) constituting a refrigerant circuit (10) by connecting the heat source unit and the utilization unit;
In the refrigerant circuit, carbon dioxide is sealed as a refrigerant,
When the rated cooling capacity is greater than 22.4 kW and 35.5 kW or less, a pipe having an outer diameter of 19.1 mm or less is used as the refrigerant communication tube.
Air conditioner (1). One or more heat source units (2);
One or more usage units (4, 5);
A refrigerant communication pipe (6, 7) constituting a refrigerant circuit (10) by connecting the heat source unit and the utilization unit;
In the refrigerant circuit, carbon dioxide is sealed as a refrigerant,
When the rated cooling capacity is greater than 35.5 kW and 45.0 kW or less, a pipe having an outer diameter of 22.2 mm or less is used as the refrigerant communication pipe.
Air conditioner (1). One or more heat source units (2);
One or more usage units (4, 5);
A refrigerant communication pipe (6, 7) constituting a refrigerant circuit (10) by connecting the heat source unit and the utilization unit;
In the refrigerant circuit, carbon dioxide is sealed as a refrigerant,
When the rated cooling capacity is greater than 45.0 kW and 56.0 kW or less, a pipe having an outer diameter of 25.4 mm or less is used as the refrigerant communication pipe.
Air conditioner (1). The heat source unit (2) was cooled in the compressor (21), the heat source side heat exchanger (23) capable of cooling the refrigerant compressed in the compressor, and the heat source side heat exchanger. An auxiliary cooler (25) capable of further cooling the refrigerant,
The air conditioner (1) according to any one of claims 1 to 5. The refrigerant communication pipe includes a first refrigerant communication pipe (6) capable of sending the refrigerant cooled in the auxiliary cooler (25) to the utilization units (4, 5), and the utilization unit to the heat source unit. A second refrigerant communication pipe (7) capable of sending the refrigerant to (2),
The heat source unit depressurizes part of the refrigerant flowing from the compressor (21) to the first refrigerant communication pipe through the heat source side heat exchanger (23) and the auxiliary cooler (25). It has an auxiliary refrigerant circuit (61) that can be returned to the suction side of the compressor later,
The auxiliary cooler is a heat exchanger that uses a refrigerant flowing through the auxiliary refrigerant circuit as a cooling source.
The air conditioner (1) according to claim 6.   The air conditioner (1) according to claim 7, wherein the refrigerant cooled in the heat source side heat exchanger (23) is further cooled by 20 ° C or more in the auxiliary cooler (25).

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