Refrigeration Cycle Equipment

Abstract

To reduce the quantity of a refrigerant to be encapsulated in a refrigerant circuit when using carbon dioxide as a refrigerant encapsulated in the refrigerant circuit in a refrigeration cycle device constituting the refrigerant circuit by connecting a heat source unit and a utilization unit via a gas refrigerant communication pipe and a liquid refrigerant communication pipe.SOLUTION: In a refrigeration cycle device (1), a refrigerant circuit (7) is constituted by connecting a heat source unit (2) and utilization units (4a and 4b) via a gas refrigerant communication pipe (5) and a liquid refrigerant communication pipe (6). Carbon dioxide is encapsulated as a refrigerant in the refrigerant circuit (7). In the refrigeration cycle device (1), a pipe of which the inner diameter is equal to or smaller than 6.2 mm is used as the gas refrigerant communication pipe (5), and / or a pipe of which the inner diameter is equal to or smaller than 3.6 mm is used as the liquid refrigerant communication pipe (6).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] A refrigeration cycle device in which a heat source unit and a utilization unit are connected via a refrigerant connection pipe to form a refrigerant circuit, and carbon dioxide is used as the refrigerant sealed in the refrigerant circuit. [Background technology]

[0002] Conventionally, there have been air conditioners (refrigeration cycle devices) in which a refrigerant circuit is formed by connecting a heat source unit and a utilization unit via a refrigerant connection pipe. As shown in Patent Document 1 (International Publication No. 2011 / 099063), one such refrigeration cycle device uses carbon dioxide as the refrigerant sealed in the refrigerant circuit. Summary of the Invention [Problem to be solved by the invention]

[0003] When carbon dioxide is used as the refrigerant to be sealed in the refrigerant circuit, adverse effects on the human body (oxygen deficiency, etc.) must be considered. Specifically, safety measures must be taken according to the concentration level of carbon dioxide in the indoor space when the refrigerant leaks from the refrigerant circuit. This tendency is particularly pronounced in refrigeration cycle devices having multiple utilization units, such as multi-air conditioners for buildings, because a large amount of refrigerant is sealed in the refrigerant circuit and if refrigerant leaks from one of the utilization units, all of the refrigerant sealed in the refrigerant circuit may leak into the indoor space corresponding to the utilization unit where the refrigerant leakage occurred.

[0004] For this reason, when carbon dioxide is used as the refrigerant to be charged into the refrigerant circuit, it is preferable to reduce the amount of refrigerant to be charged into the refrigerant circuit. [Means for solving the problem]

[0005] A refrigeration cycle apparatus according to a first aspect is a refrigeration cycle apparatus in which a heat source unit and a utilization unit are connected via a gas refrigerant connection pipe and a liquid refrigerant connection pipe to form a refrigerant circuit, in which the refrigerant sealed in the refrigerant circuit is carbon dioxide, the gas refrigerant connection pipe is a pipe having an inner diameter of 6.2 mm or less, and / or the liquid refrigerant connection pipe is a pipe having an inner diameter of 3.6 mm or less.

[0006] As a result, since pipes with an inner diameter that have not been used as a gas refrigerant connection pipe and / or a liquid refrigerant connection pipe in the past are used, the volume of the gas refrigerant connection pipe and / or the liquid refrigerant connection pipe can be reduced, and the amount of refrigerant sealed in the refrigerant circuit can be reduced.

[0007] The refrigeration cycle device of the second aspect is the refrigeration cycle device of the first aspect, in which a copper pipe (with a quality of 1 / 2H) with a nominal diameter of less than 1 / 4 inch is used as a liquid refrigerant connecting pipe to which a utilization unit with a rated refrigeration capacity of 8.0 kW or less is connected.

[0008] As a result, since a copper pipe with a nominal diameter that has not previously been used as a liquid refrigerant connection pipe is used here, it is possible to increase the size of the copper pipe that can be used as a liquid refrigerant connection pipe, which contributes to the optimization of the liquid refrigerant connection pipe.

[0009] The refrigeration cycle apparatus of the third aspect is the refrigeration cycle apparatus of the first aspect, in which a copper pipe (with a quality of 1 / 2H) having a nominal diameter of 1.5 / 8 inches is used as a liquid refrigerant connecting pipe to which a utilization unit having a rated refrigeration capacity of 8.0 kW or less is connected.

[0010] As a result, since a copper pipe with a nominal diameter that has not previously been used as a liquid refrigerant connection pipe is used here, it is possible to increase the size of the copper pipe that can be used as a liquid refrigerant connection pipe, which contributes to the optimization of the liquid refrigerant connection pipe.

[0011] The refrigeration cycle apparatus of the fourth aspect is the refrigeration cycle apparatus of any one of the first to third aspects, in which a copper pipe (with a quality of 1 / 2H) with a nominal diameter larger than 1 / 4 inch and smaller than 3 / 8 inch is used as a gas refrigerant connecting pipe to which a utilization unit with a rated refrigeration capacity of 4.5 kW or less is connected.

[0012] As a result, since a copper pipe with a nominal diameter that has not been used as a gas refrigerant connection pipe in the past is used here, it is possible to increase the size of the copper pipe that can be used as a gas refrigerant connection pipe, which contributes to the optimization of the gas refrigerant connection pipe.

[0013] The refrigeration cycle apparatus of the fifth aspect is the refrigeration cycle apparatus of any of the first to third aspects, in which a copper pipe (with a 1 / 2H temper) having a nominal diameter of 2.5 / 8 inches is used as a gas refrigerant connecting pipe to which a utilization unit having a rated refrigeration capacity of 4.5 kW or less is connected.

[0014] As a result, since a copper pipe with a nominal diameter that has not been used as a gas refrigerant connection pipe in the past is used here, it is possible to increase the size of the copper pipe that can be used as a gas refrigerant connection pipe, which contributes to the optimization of the gas refrigerant connection pipe.

[0015] The refrigeration cycle apparatus of the sixth aspect is the refrigeration cycle apparatus of the first aspect, in which a copper pipe (with quality O) having a nominal diameter of less than 1 / 4 inch is used as a liquid refrigerant connecting pipe to which a utilization unit having a rated refrigeration capacity of 3.6 kW or less is connected.

[0016] As a result, since copper pipes with nominal diameters that have not previously been used as liquid refrigerant connection pipes are used, the size of copper pipes that can be used as liquid refrigerant connection pipes can be increased, contributing to the optimization of liquid refrigerant connection pipes.

[0017] The refrigeration cycle apparatus of the seventh aspect is the refrigeration cycle apparatus of the first aspect, in which a copper pipe (with quality O) having a nominal diameter of 1.5 / 8 inches is used as a liquid refrigerant connecting pipe to which a utilization unit having a rated refrigeration capacity of 3.6 kW or less is connected.

[0018] As a result, since a copper pipe with a nominal diameter that has not previously been used as a liquid refrigerant connection pipe is used here, it is possible to increase the size of the copper pipe that can be used as a liquid refrigerant connection pipe, which contributes to the optimization of the liquid refrigerant connection pipe.

[0019] The refrigeration cycle apparatus of the eighth aspect is the refrigeration cycle apparatus of any one of the first, sixth and seventh aspects, in which a copper pipe (with quality O) having a nominal diameter larger than 1 / 4 inch and smaller than 3 / 8 inch is used as a gas refrigerant connecting pipe to which a utilization unit having a rated refrigeration capacity of 2.8 kW or less is connected.

[0020] As a result, since a copper pipe with a nominal diameter that has not been used as a gas refrigerant connection pipe in the past is used here, it is possible to increase the size of the copper pipe that can be used as a gas refrigerant connection pipe, which contributes to the optimization of the gas refrigerant connection pipe.

[0021] The refrigeration cycle apparatus of the ninth aspect is the refrigeration cycle apparatus of any one of the first, sixth and seventh aspects, in which a copper pipe (with O quality) having a nominal diameter of 2.5 / 8 inches is used as a gas refrigerant connecting pipe to which a utilization unit having a rated refrigeration capacity of 2.8 kW or less is connected.

[0022] As a result, since a copper pipe with a nominal diameter that has not been used as a gas refrigerant connection pipe in the past is used here, it is possible to increase the size of the copper pipe that can be used as a gas refrigerant connection pipe, which contributes to the optimization of the gas refrigerant connection pipe.

[0023] A refrigeration cycle device according to a tenth aspect is a refrigeration cycle device according to any one of the first to ninth aspects, wherein the gas refrigerant connection pipe and the liquid refrigerant connection pipe are covered on their outer surfaces with a heat-insulating material and the two pipes are bundled together to form a pair of refrigerant connection pipes.

[0024] Here, when connecting the heat source unit and the utilization unit on-site, a pair of refrigerant connection pipes can be used, improving workability.

[0025] The refrigeration cycle apparatus of an eleventh aspect is a refrigeration cycle apparatus according to any one of the first to tenth aspects, in which when a pipe with a nominal diameter of 1.5 / 8 inches is used as a liquid refrigerant communication pipe with a nominal diameter of less than 1 / 4 inch, the pipe end has a different diameter section expanded to a nominal diameter of 1 / 4 inch.

[0026] When the liquid refrigerant connection pipe is long or branches, pipe fittings such as socket pipes and branch pipes are required to connect the pipes. However, the pipe fittings that have been used so far are compatible with pipes with nominal diameters in 1 / 8 inch increments, but are not compatible with pipes with nominal diameters in 0.5 / 8 inch increments.

[0027] Therefore, here, the end of a pipe with a nominal diameter of 1.5 / 8 inches used as a liquid refrigerant connection pipe has a different diameter section expanded to a nominal diameter of 1 / 4 inch (= 2 / 8 inch).

[0028] As a result, even when using a pipe with a nominal diameter of 1.5 / 8 inches as a liquid refrigerant connection pipe with a nominal diameter of less than 1 / 4 inch, it is possible to use pipe fittings that are compatible with pipes with nominal diameters in 1 / 8 inch increments, which has been used traditionally, eliminating the need to prepare pipe fittings that are compatible with pipes with nominal diameters in 0.5 / 8 inch increments, improving ease of installation.

[0029] A refrigeration cycle apparatus according to a twelfth aspect is a refrigeration cycle apparatus according to any one of the first to eleventh aspects, in which when a pipe with a nominal diameter of 2.5 / 8 inches is used as a gas refrigerant communication pipe with a nominal diameter greater than 1 / 4 inch and less than 3 / 8 inch, the pipe end has a different diameter section expanded to a nominal diameter of 3 / 8 inch.

[0030] When the gas refrigerant communication pipe is long or branches, pipe fittings such as socket pipes and branch pipes are required to connect the pipes. However, the pipe fittings that have been used so far are compatible with pipes with nominal diameters in 1 / 8 inch increments, but are not compatible with pipes with nominal diameters in 0.5 / 8 inch increments.

[0031] Therefore, here, the end of a pipe with a nominal diameter of 2.5 / 8 inches used as a gas refrigerant communication pipe has a reduced diameter portion enlarged to a nominal diameter of 3 / 8 inches.

[0032] As a result, even when a pipe with a nominal diameter of 2.5 / 8 inches is used as a gas refrigerant connecting pipe with a nominal diameter larger than 1 / 4 inch and less than 3 / 8 inch, conventional pipe fittings compatible with pipes with nominal diameters in 1 / 8 inch increments can be used, making it unnecessary to prepare pipe fittings compatible with pipes with nominal diameters in 0.5 / 8 inch increments, improving ease of installation. [Brief description of the drawings]

[0033] [Figure 1] 1 is a schematic configuration diagram of an air conditioner as a refrigeration cycle apparatus according to an embodiment of the present disclosure. [Diagram 2] 1 is a table showing the relationship between the rated refrigeration capacity and the pipe diameter of the refrigerant connection pipe when R410A, R32 or carbon dioxide is used as the refrigerant. [Diagram 3] 2 is an explanatory diagram of a refrigerant communication pipe constituting the refrigeration cycle apparatus of FIG. 1 (parts constituting a heat source unit and a utilization unit are not shown). [Figure 4] 1 is a table showing the relationship between the rated refrigeration capacity and the pipe diameter of the refrigerant connecting pipe when the quality of the copper pipe is 1 / 2H or O. [Diagram 5] FIG. 2 is a diagram showing the main parts of a pair of refrigerant communication pipes. [Figure 6] FIG. 4 is a diagram showing a pipe end portion of a refrigerant communication pipe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Hereinafter, the refrigeration cycle device will be described with reference to the drawings.

[0035] (1) Composition <Overall> FIG. 1 is a schematic configuration diagram of an air conditioner 1 as a refrigeration cycle apparatus according to one embodiment of the present disclosure.

[0036] The air conditioner 1 is a device capable of cooling or heating the interior of a building or the like by a vapor compression refrigeration cycle. The air conditioner 1 mainly has a heat source unit 2, utilization units 4a and 4b, and a gas refrigerant connection pipe 5 and a liquid refrigerant connection pipe 6 that connect the heat source unit 2 and the utilization units 4a and 4b. That is, the vapor compression refrigerant circuit 7 of the air conditioner 1 is configured by connecting the heat source unit 2 and the utilization units 4a and 4b via the gas refrigerant connection pipe 5 and the liquid refrigerant connection pipe 6. Carbon dioxide is sealed in the refrigerant circuit 7 as a refrigerant. When carbon dioxide is used as the refrigerant, the refrigerant may become supercritical (a state in which the gas state and the liquid state cannot be distinguished) during the refrigeration cycle, but the names of the parts that constitute the refrigerant circuit 7, including the refrigerant connection pipes 5 and 6, are named using the terms "gas" and "liquid" in the names of the parts, as in the case of using a refrigerant that does not become supercritical during the refrigeration cycle (R410A, R32, etc.).

[0037] <Unit of Use> The utilization units 4a and 4b are installed indoors or the like and constitute a part of the refrigerant circuit 7. The utilization unit 4a mainly has a utilization side expansion mechanism 41a and a utilization heat exchanger 42a. The utilization unit 4b mainly has a utilization side expansion mechanism 41b and a utilization heat exchanger 42b. Here, since the utilization units 4a and 4b have the same configuration, only the configuration of the utilization unit 4a will be described here, and the configuration of the utilization unit 4b will be described with the subscript "b" instead of the subscript "a" indicating each part of the utilization unit 4a, and description of each part will be omitted.

[0038] The utilization side expansion mechanism 41a is a mechanism for decompressing the refrigerant, and an expansion valve is used here. The utilization side expansion mechanism 41a has one end connected to the utilization side heat exchanger 42a and the other end connected to the liquid refrigerant connection pipe 6.

[0039] The utilization side heat exchanger 42a is a heat exchanger that functions as an evaporator or a radiator of the refrigerant. One end of the utilization side heat exchanger 42a is connected to the utilization side expansion mechanism 41a, and the other end is connected to the gas refrigerant communication pipe 5.

[0040] The utilization unit 4a has a utilization side fan 43a for drawing air into the unit and supplying it to the room, thereby enabling heat exchange between the air and the refrigerant flowing through the utilization side heat exchanger 42a.

[0041] <Heat source unit> The heat source unit 2 is installed outdoors or the like, and constitutes a part of the refrigerant circuit 7. The heat source unit 2 mainly has a compressor 21, a switching mechanism 22, a heat source side heat exchanger 23, a heat source side expansion mechanism 25, a subcooling heat exchanger 26, a suction return pipe 27, a liquid side shutoff valve 29, a gas side shutoff valve 30, and an accumulator 31.

[0042] The compressor 21 is a device that compresses a refrigerant. Further, an accumulator 31 that temporarily stores the refrigerant is provided on the suction side of the compressor 21.

[0043] The switching mechanism 22 is a mechanism for switching the direction of the refrigerant flow in the refrigerant circuit 7, and a four-way switching valve is used here. In order to make the heat source side heat exchanger 23 function as a refrigerant radiator and the utilization side heat exchangers 42a, 42b function as refrigerant evaporators during cooling operation, the switching mechanism 22 connects the discharge side of the compressor 21 to one end of the heat source side heat exchanger 23 and connects the suction side of the compressor 21 to the gas side stop valve 30 (see the solid line of the switching mechanism 22 in FIG. 1). In order to make the utilization side heat exchanger 42 function as a refrigerant radiator and the heat source side heat exchanger 23 function as a refrigerant evaporator during heating operation, the switching mechanism 22 connects the discharge side of the compressor 21 to the gas side stop valve 30 and connects the suction side of the compressor 21 to one end of the heat source side heat exchanger 23 (see the dashed line of the switching mechanism 22 in FIG. 1).

[0044] The heat source side heat exchanger 23 is a heat exchanger that functions as a radiator or an evaporator of the refrigerant. 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 25.

[0045] The heat source unit 2 has a heat source side fan 24 for drawing air into the unit and expelling it to the outside, thereby allowing heat exchange to occur between the air and the refrigerant flowing through the heat source side heat exchanger 23.

[0046] The heat source expansion mechanism 25 is a mechanism for decompressing the refrigerant, and an expansion valve is used here. The heat source expansion mechanism 25 has one end connected to the heat source heat exchanger 23 and the other end connected to the subcooling heat exchanger 26.

[0047] The subcooling heat exchanger 26 is a heat exchanger that further cools the refrigerant that has dissipated heat in the heat source side heat exchanger 23. One end of the subcooling heat exchanger 26 is connected to the heat source side expansion mechanism 25, and the other end is connected to the liquid side shutoff valve 29. The refrigerant circuit 7 is provided with a suction return pipe 27 that reduces the pressure of a part of the refrigerant that flows between the other end of the heat source side heat exchanger 23 and the liquid side shutoff valve 29 through the heat source side expansion mechanism 25 and the subcooling heat exchanger 26, and then returns the part to the suction side of the compressor 21. Here, the suction return pipe 27 is provided in the refrigerant circuit 7 so that a part of the refrigerant that flows between the heat source side expansion mechanism 25 and the subcooling heat exchanger 26 is branched from the refrigerant circuit 7 and returned to the suction side of the compressor 21 (more specifically, between the switching mechanism 22 and the accumulator 31). The suction return pipe 27 is provided with a suction return expansion mechanism 28 for reducing the pressure of the refrigerant. Here, an expansion valve is used as the suction return expansion mechanism 28. As a result, a portion of the refrigerant cooled in the heat source side heat exchanger 23 is bypassed to the suction side of the compressor 21 through the suction return pipe 27, and the remainder is cooled in the heat source side heat exchanger 26 by the refrigerant flowing through the suction return pipe 27.

[0048] The liquid-side shutoff valve is a valve to which the liquid refrigerant communication pipe 6 for exchanging refrigerant between the heat source unit 2 and the utilization units 4a, 4b is connected, and is connected to the subcooling heat exchanger .

[0049] The gas-side shutoff valve 30 is a valve to which a gas refrigerant communication pipe 5 for exchanging refrigerant between the heat source unit 2 and the utilization units 4a, 4b is connected, and is connected to a switching mechanism 22.

[0050] <Refrigerant connection pipe> The refrigerant connection pipes 5, 6 are refrigerant pipes that connect the heat source unit 2 and the utilization units 4a, 4b on-site when the air conditioner 1 is constructed.

[0051] The gas refrigerant communication pipe 5 is a refrigerant pipe through which refrigerant flows from the end of the evaporation process to the start of the compression process, or from the end of the compression process to the start of the heat dissipation process, when explained using the compression process, heat dissipation process, and evaporation process of the refrigeration cycle. Here, the gas refrigerant communication pipe 5 connects the gas side stop valve 30 of the heat source unit 2 to the other ends of the user side heat exchangers 42a, 42b of the user units 4a, 4b. The gas refrigerant communication pipe 5 mainly includes a gas refrigerant communication branch pipe 52a connected to the user unit 4a, a gas refrigerant communication branch pipe 52b connected to the user unit 4b, and a gas refrigerant communication main pipe 51 that connects the junction of the gas refrigerant communication branch pipes 52a, 52b to the heat source unit 2.

[0052] The liquid refrigerant communication pipe 6 is a refrigerant pipe through which refrigerant flows from the end of the heat radiation process to the start of the evaporation process, when described using the compression process, heat dissipation process, expansion process, and evaporation process of the refrigeration cycle. Here, the liquid refrigerant communication pipe 6 connects between the liquid side stop valve 29 of the heat source unit 2 and the utilization side expansion mechanisms 41a, 41b of the utilization units 4a, 4b. The liquid refrigerant communication pipe 6 mainly includes a liquid refrigerant communication branch pipe 62a connected to the utilization unit 4a, a liquid refrigerant communication branch pipe 62b connected to the utilization unit 4b, and a liquid refrigerant communication main pipe 61 connecting the junction of the liquid refrigerant communication branch pipes 62a, 62b to the heat source unit 2.

[0053] (2) Operation Next, the operation of the air conditioner 1 will be described with reference to Fig. 1. Note that the operation of the air conditioner 1, such as cooling operation and heating operation, described below, is performed by a control unit (not shown) configured by communication connections between control boards, remote controls, and the like provided in the utilization units 4a and 4b and the heat source unit 2.

[0054] <Cooling operation> During cooling operation, the switching mechanism 22 is in the state shown by the solid line in Figure 1, i.e., 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 gas side shut-off valve 30.

[0055] In this state of the refrigerant circuit 7, low-pressure refrigerant in the refrigeration cycle is sucked into the compressor 21, compressed to the high pressure of the refrigeration cycle, and then discharged from the compressor 21. The high-pressure refrigerant discharged from the compressor 21 is sent to the heat source side heat exchanger 23 via the switching mechanism 22, and dissipates heat by exchanging heat with outdoor air supplied by the heat source side fan 24. The high-pressure refrigerant that has dissipated heat in the heat source side heat exchanger 23 flows into the subcooling heat exchanger 26 via the heat source side expansion mechanism 25, and is cooled by exchanging heat with the refrigerant flowing through the suction return pipe 27. At this time, a part of the high-pressure refrigerant that has dissipated heat in the heat source side heat exchanger 23 is branched off to the suction return pipe 27 and depressurized by the suction return expansion mechanism 28. The refrigerant depressurized in the suction return expansion mechanism 28 is heated in the subcooling heat exchanger 26 by heat exchange with the high-pressure refrigerant flowing through the refrigerant circuit 7, and then returned to the suction side of the compressor 21 (here, between the switching mechanism 22 and the accumulator 31).

[0056] The high-pressure refrigerant cooled in the subcooling heat exchanger 26 is sent to the utilization units 4a, 4b via the liquid-side shutoff valve 29 and the liquid refrigerant connection pipe 6. The high-pressure refrigerant sent to the utilization units 4a, 4b is decompressed by the utilization side expansion mechanisms 41a, 41b to become a low-pressure gas-liquid two-phase refrigerant. The refrigerant decompressed in the utilization side expansion mechanisms 41a, 41b is sent to the utilization side heat exchangers 42a, 42b, where it exchanges heat with indoor air supplied by the utilization side fans 43a, 43b to evaporate. At this time, the indoor air is cooled by exchanging heat with the refrigerant in the utilization side heat exchangers 42a, 42b and sent to the room, thereby cooling the room.

[0057] Then, the low-pressure refrigerant evaporated in the utilization-side heat exchangers 42a, 42b is sent to the heat source unit 2 via the gas refrigerant communication pipe 5. The low-pressure refrigerant sent to the heat source unit 2 passes through the gas shutoff valve 30, the switching mechanism 22, and the accumulator 31, and is sucked back into the compressor 21 together with the refrigerant returned from the suction return pipe 27.

[0058] <Heating operation> During heating operation, the switching mechanism 22 is in the state shown by the dashed line in Figure 1, i.e., the discharge side of the compressor 21 is connected to the gas side shut-off valve 30 and the suction side of the compressor 21 is connected to the heat source side heat exchanger 23.

[0059] In this state of the refrigerant circuit 7, low-pressure refrigerant in the refrigeration cycle is sucked into the compressor 21, compressed to the high pressure of the refrigeration cycle, and then discharged from the compressor 21. The high-pressure refrigerant discharged from the compressor 21 is sent to the utilization units 4a, 4b via the switching mechanism 22, the gas-side shut-off valve 30, and the gas refrigerant communication pipe 5.

[0060] The high-pressure refrigerant sent to the utilization units 4a, 4b exchanges heat with indoor air supplied by utilization fans 43a, 43b in utilization side heat exchangers 42a, 42b and dissipates heat. At this time, the indoor air is heated by heat exchange with the refrigerant in the utilization side heat exchangers 42a, 42b and sent to the room, thereby heating the room. The high-pressure refrigerant that has dissipated heat in the utilization side heat exchangers 42a, 42b is depressurized by the utilization side expansion mechanisms 41a, 41b.

[0061] The refrigerant decompressed in the utilization side expansion mechanisms 41a and 41b is sent to the heat source unit 2 via the liquid refrigerant communication pipe 6. The refrigerant sent to the heat source unit 2 is sent to the heat source side expansion mechanism 25 via the liquid side shutoff valve 29 and the subcooling heat exchanger 26. At this time, the suction return expansion mechanism 28 is closed, so the refrigerant is not branched to the suction return pipe 27. The refrigerant sent to the heat source side expansion mechanism 25 is further decompressed by the heat source side expansion mechanism 25 to become a low-pressure refrigerant in a gas-liquid two-phase state. The refrigerant decompressed in the heat source side expansion mechanism 25 is sent to the heat source side heat exchanger 23, where it exchanges heat with the outdoor air supplied by the heat source side fan 24 and evaporates. The low-pressure refrigerant evaporated in the heat source side heat exchanger 23 is sucked into the compressor 21 again via the switching mechanism 22 and the accumulator 31.

[0062] (3) Selection of refrigerant connection pipe diameter In the air conditioner 1, the refrigerant communication pipes 5, 6 used have various pipe diameters and lengths depending on the refrigeration capacity conditions of the air conditioner 1, the conditions of the installation location, and the like.

[0063] 2, the pipe diameters of the refrigerant connection pipes 5, 6 are selected according to the rated refrigeration capacity of the utilization units 4a, 4b connected to the heat source unit 2. Here, when the refrigeration cycle device is an air conditioner 1, for example, the "rated refrigeration capacity" means a value equivalent to the "rated cooling capacity" or "nominal capacity" of the utilization units 4a, 4b or the heat source unit 2 described in a product catalog or instruction manual.

[0064] The values ​​of the pipe diameters of the refrigerant communication pipes 5 and 6 shown in FIG. 2 indicate the pipe diameters of the refrigerant communication pipes 5 and 6 (i.e., the refrigerant communication branch pipes 52a, 52b, 62a, 62b and the refrigerant communication mother pipes 51 and 61) excluding pipe joints such as the socket pipes 53a and 63a and the branch pipes 54a and 64a for connecting the pipes shown in FIG. 3. Also, here, the values ​​of the pipe diameters are shown when copper pipes (with a 1 / 2H temper) such as phosphorus-deoxidized copper seamless copper pipes are used as the pipe material of the refrigerant communication pipes 5 and 6. Here, "temper" means, for example, the type of temper of the copper pipe specified in JIS H 3300, and "1 / 2H temper" indicates the degree of tensile strength obtained by the work hardening treatment performed during manufacturing. Here, the case where carbon dioxide is used as the refrigerant filled in the refrigerant circuit 7, and the case where R410A, which has been used frequently in the past, and R32, which has recently started to be used, are used as comparative examples. In Fig. 2, the nominal diameter and the inside diameter are shown as the values ​​of the pipe diameter. Here, when carbon dioxide is used, the inside diameter value is shown when the design pressure of the refrigerant connection pipes 5, 6 is set to 12.3 MPa, taking into consideration the high pressure in the refrigeration cycle. However, when carbon dioxide is used, the design pressure of the refrigerant connection pipes 5, 6 may be set to a somewhat higher pressure, such as 13.7 MPa, in which case the pipe wall thickness may increase, resulting in an inside diameter smaller than that shown in Fig. 2.

[0065] According to FIG. 2, a copper pipe with a nominal diameter of less than 1 / 4 inch (outer diameter of 6.35 mm) is used as the liquid refrigerant connection pipe 6 to which the utilization units 4a and 4b with a rated refrigeration capacity of 8.0 kW or less are connected. Specifically, a copper pipe with a nominal diameter of 1.5 / 8 inch (outer diameter of 4.76 mm) is used as the liquid refrigerant connection pipe 6 with a nominal diameter of less than 1 / 4 inch. Here, since a copper pipe with a nominal diameter of 1.5 / 8 inch has an inner diameter of 3.6 mm, this means that a pipe with an inner diameter of 3.6 mm or less is used as the liquid refrigerant connection pipe 6. Note that the "liquid refrigerant connection pipe 6 to which a utilization unit with a rated refrigeration capacity of 8.0 kW or less is connected" does not only mean a liquid refrigerant connection pipe 6 to which only one utilization unit with a rated refrigeration capacity of 8.0 kW or less is connected. When the liquid refrigerant connection pipe 6 branches out and multiple utilization units 4a, 4b are connected to the liquid refrigerant connection pipe 6 as in the configuration in Figure 3, it also means the branched portions (liquid refrigerant connection branch pipes 62a, 62b) of the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b with a rated refrigeration capacity of 8.0 kW or less are connected, and the junction portion (liquid refrigerant connection main pipe 61) of the liquid refrigerant connection pipe 6 where the total rated refrigeration capacity of the multiple utilization units 4a, 4b is 8.0 kW or less. In addition, "using copper pipes with a nominal diameter of less than 1 / 4 inch (1.5 / 8 inches) (inner diameter of 3.6 mm or less) as the liquid refrigerant connection pipe 6" does not only mean using only copper pipes with a nominal diameter of less than 1 / 4 inch (1.5 / 8 inches) (inner diameter of 3.6 mm or less), but also includes the use of copper pipes with a nominal diameter of less than 1 / 4 inch (1.5 / 8 inches) (inner diameter of 3.6 mm or less) and copper pipes with a nominal diameter of 1 / 4 inch or more (larger than 1.5 / 8 inches) (inner diameter larger than 3.6 mm).

[0066] Also, according to FIG. 2, a copper pipe with a nominal diameter of 1 / 4 inch (outer diameter 6.35 mm, inner diameter 5.0 mm) is used as the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b, each of which has a rated refrigeration capacity of more than 8.0 kW and not more than 16.0 kW, are connected.

[0067] 2, a copper pipe with a nominal diameter larger than 1 / 4 inch (outer diameter 6.35 mm) and smaller than 3 / 8 inch (outer diameter 9.52 mm) is used as the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b with a rated refrigeration capacity of larger than 16.0 kW and smaller than 28.0 kW are connected. Specifically, a copper pipe with a nominal diameter of 2.5 / 8 inch (outer diameter 7.94 mm, inner diameter 6.2 mm) is used as the liquid refrigerant connection pipe 6 with a nominal diameter larger than 1 / 4 inch and smaller than 3 / 8 inch.

[0068] According to FIG. 2, a copper pipe with a nominal diameter larger than 1 / 4 inch (outer diameter 6.35 mm) and smaller than 3 / 8 inch (outer diameter 9.52 mm) is used as the gas refrigerant connection pipe 5 to which the utilization units 4a and 4b with a rated refrigeration capacity of 4.5 kW or less are connected. Specifically, a copper pipe with a nominal diameter of 2.5 / 8 inch (outer diameter 7.94 mm) is used as the gas refrigerant connection pipe 5 with a nominal diameter larger than 1 / 4 inch and smaller than 3 / 8 inch. Here, since a copper pipe with a nominal diameter of 2.5 / 8 inch has an inner diameter of 6.2 mm or less, this means that a pipe with an inner diameter of 6.2 mm or less is used as the gas refrigerant connection pipe 5. Note that the "gas refrigerant connection pipe 5 to which a utilization unit with a rated refrigeration capacity of 4.5 kW or less is connected" does not only mean a gas refrigerant connection pipe 6 to which only one utilization unit with a rated refrigeration capacity of 4.5 kW or less is connected. When the gas refrigerant communication pipe 5 branches and multiple utilization units 4a, 4b are connected to the gas refrigerant communication pipe 5 as in the configuration in Figure 3, it also means the branched parts (gas refrigerant communication branch pipes 52a, 52b) of the gas refrigerant communication pipe 5 to which the utilization units 4a, 4b with a rated refrigeration capacity of 4.5 kW or less are connected, and the junction part (gas refrigerant communication main pipe 51) of the gas refrigerant communication pipe 5 where the total rated refrigeration capacity of the multiple utilization units 4a, 4b is 4.5 kW or less. In addition, "using copper pipes with a nominal diameter of more than 1 / 4 inch and less than 3 / 8 inch (2.5 / 8 inch) (inner diameter 6.2 mm or less) as the gas refrigerant connection pipe 5" does not only mean using only copper pipes with a nominal diameter of more than 1 / 4 inch and less than 3 / 8 inch (2.5 / 8 inch) (inner diameter 6.2 mm or less), but also means using copper pipes with a nominal diameter of more than 1 / 4 inch and less than 3 / 8 inch (2.5 / 8 inch) (inner diameter 6.2 mm or less) and copper pipes with a nominal diameter of 3 / 8 inch or more (greater than 2.5 / 8 inch) (inner diameter greater than 6.2 mm).

[0069] Also, according to FIG. 2, a copper pipe with a nominal diameter of 3 / 8 inch (outer diameter 9.52 mm, inner diameter 7.4 mm) is used as the gas refrigerant connection pipe 5 to which the utilization units 4a, 4b, each having a rated refrigeration capacity of more than 4.5 kW and not more than 8.0 kW, are connected.

[0070] Also, according to FIG. 2, a copper pipe with a nominal diameter of 1 / 2 inch (outer diameter 12.70 mm, inner diameter 9.9 mm) is used as the gas refrigerant communication pipe 5 to which the utilization units 4a, 4b, each of which has a rated refrigeration capacity of more than 8.0 kW and not more than 16.0 kW, are connected.

[0071] Also, according to FIG. 2, a copper pipe with a nominal diameter of 5 / 8 inch (outer diameter 15.88 mm, inner diameter 12.3 mm) is used as the gas refrigerant connection pipe 5 to which the utilization units 4a, 4b, each having a rated refrigeration capacity of more than 16.0 kW and not more than 28.0 kW, are connected.

[0072] Also, according to FIG. 2, it can be seen that when carbon dioxide is used, a smaller pipe diameter is selected for the refrigerant connecting pipes 5, 6 compared to when a conventional refrigerant such as R410A or R32 is used at the same rated refrigeration capacity.

[0073] Then, by using the table of pipe diameters of the refrigerant communication pipes 5, 6 shown in FIG. 2, the pipe diameters of the refrigerant communication pipes 5, 6 can be selected as follows.

[0074] For example, if the rated refrigeration capacity of both utilization units 4a, 4b is 2.8 kW, then the gas refrigerant communication branch pipes 52a, 52b are made of copper pipes with a nominal diameter of 2.5 / 8 inches, and the liquid refrigerant communication branch pipes 62a, 62b are made of copper pipes with a nominal diameter of 1.5 / 8 inches. Then, after the utilization units 4a, 4b are joined, the total rated refrigeration capacity becomes 5.6 kW, so that the gas refrigerant communication main pipe 51 is made of copper pipes with a nominal diameter of 3 / 8 inches, and the liquid refrigerant communication main pipe 61 is made of copper pipes with a nominal diameter of 1.5 / 8 inches.

[0075] Furthermore, for example, if the rated refrigeration capacities of both utilization units 4a, 4b are 11.2 kW, then the gas refrigerant communication branch pipes 52a, 52b are made of copper pipes with a nominal diameter of 1 / 2 inch, and the liquid refrigerant communication branch pipes 62a, 62b are made of copper pipes with a nominal diameter of 1 / 4 inch. Then, after the utilization units 4a, 4b are joined, the total rated refrigeration capacity becomes 22.4 kW, so that the gas refrigerant communication main pipe 51 is made of copper pipes with a nominal diameter of 5 / 8 inch, and the liquid refrigerant communication main pipe 61 is made of copper pipes with a nominal diameter of 2.5 / 8 inch.

[0076] Also, for example, if the rated refrigeration capacity of the utilization unit 4a is 2.2 kW and the rated refrigeration capacity of the utilization unit 4b is 9.0 kW, a copper pipe with a nominal diameter of 2.5 / 8 inches is used for the gas refrigerant communication branch pipe 52a, a copper pipe with a nominal diameter of 1 / 2 inch is used for the gas refrigerant communication branch pipe 52b, a copper pipe with a nominal diameter of 1.5 / 8 inches is used for the liquid refrigerant communication branch pipe 62a, and a copper pipe with a nominal diameter of 1 / 4 inch is used for the liquid refrigerant communication branch pipe 62b. Then, after the utilization units 4a, 4b are joined, the total rated refrigeration capacity becomes 11.2 kW, so a copper pipe with a nominal diameter of 1 / 2 inch is used for the gas refrigerant communication mother pipe 51, and a copper pipe with a nominal diameter of 1 / 4 inch is used for the liquid refrigerant communication mother pipe 61.

[0077] (4) Features Next, the features of the air conditioner 1 will be described.

[0078] Here, as described above, in the air conditioning apparatus 1 (refrigeration cycle apparatus) in which the heat source unit 2 and the utilization units 4a, 4b are connected via a gas refrigerant connection pipe 5 and a liquid refrigerant connection pipe 6 to form the refrigerant circuit 7, carbon dioxide is used as the refrigerant sealed in the refrigerant circuit 7, and a pipe with an inner diameter of 6.2 mm or less is used as the gas refrigerant connection pipe 5, and / or a pipe with an inner diameter of 3.6 mm or less is used as the liquid refrigerant connection pipe 6 (see FIG. 2).

[0079] Here, carbon dioxide, which has a higher refrigeration capacity per unit volume than conventional refrigerants (R410A, R32, etc.), is used as the refrigerant, so it is possible to reduce the flow rate of the refrigerant circulating through the refrigerant circuit 7 (refrigerant circulation amount). For this reason, here, pipes with smaller inner diameters than pipes used for conventional refrigerants can be used as the refrigerant connection pipes 5, 6 while preventing the flow path resistance of the refrigerant flowing through the refrigerant connection pipes 5, 6 from becoming excessively large.

[0080] Specifically, with conventional refrigerants, taking into consideration flow path resistance, a pipe with an inner diameter smaller than 11.1 mm is not used as a gas refrigerant connection pipe, and a pipe with an inner diameter smaller than 4.7 mm is not used as a liquid refrigerant connection pipe (see Fig. 2). In contrast, here, as described above, a pipe with an inner diameter too small to be used as a gas refrigerant connection pipe with conventional refrigerants (a pipe with an inner diameter of 6.2 mm or less) is used as the gas refrigerant connection pipe 5, and / or a pipe with an inner diameter too small to be used as a liquid refrigerant connection pipe with conventional refrigerants (a pipe with an inner diameter of 3.6 mm or less) is used as the liquid refrigerant connection pipe 6.

[0081] Thereby, here, the volume of the gas refrigerant communication tube 5 and / or the liquid refrigerant communication tube 6 can be made small, and the amount of refrigerant sealed in the refrigerant circuit 7 can be reduced.

[0082] As described above, a copper pipe (with a quality of 1 / 2H) with a nominal diameter of less than 1 / 4 inch (with an outer diameter of 6.35 mm) is used as the liquid refrigerant connection pipe 6 with an inner diameter of 3.6 mm or less (see FIG. 2). Specifically, a copper pipe (with a quality of 1 / 2H) with a nominal diameter of 1.5 / 8 inch (with an outer diameter of 4.76 mm) is used (see FIG. 2).

[0083] Here, for conventional refrigerants (R410A, R32, etc.), copper pipes with a nominal diameter of less than 1 / 4 inch (here, 1.5 / 8 inch) are not used as liquid refrigerant connection pipes (see FIG. 2). Conventionally used copper pipes for refrigerants have nominal diameters in increments of 1 / 8 inch, such as 1 / 4 (=2 / 8) inch, 3 / 8 inch, 1 / 2 (=4 / 8) inch, 5 / 8 inch, and 3 / 4 (=6 / 8) inch, and nominal diameters in increments of 0.5 / 8 inch are not used. That is, here, copper pipes (classified as 1 / 2H) with a nominal diameter of less than 1 / 4 inch (outer diameter of 6.35 mm) (here, 1.5 / 8 inch), which have an inner diameter of 3.6 mm or less and have not been used conventionally, because the nominal diameter (outer diameter) is too small for use as liquid refrigerant connection pipes, are used as liquid refrigerant connection pipes 6 to which utilization units 4a and 4b with a rated refrigeration capacity of 8.0 kW or less are connected.

[0084] As a result, the volume of the liquid refrigerant connection pipe 6 can be reduced, and the amount of refrigerant sealed in the refrigerant circuit 7 can be reduced. Moreover, because a copper pipe with a nominal diameter that has not been used as a liquid refrigerant connection pipe in the past is used here, the size of the copper pipe that can be used as the liquid refrigerant connection pipe 6 can be increased, which contributes to optimizing the liquid refrigerant connection pipe 6.

[0085] <c> As described above, a copper pipe (with a temper of 1 / 2H) with a nominal diameter larger than 1 / 4 inch (with an outer diameter of 6.35 mm) and smaller than 3 / 8 inch (with an outer diameter of 9.52 mm) is used as the gas refrigerant communication pipe 5 with an inner diameter of 6.2 mm or less (see FIG. 2). Specifically, a copper pipe (with a temper of 1 / 2H) with a nominal diameter of 2.5 / 8 inch (with an outer diameter of 7.94 mm) is used here (see FIG. 2).

[0086] Here, for conventional refrigerants (R410A, R32, etc.), copper pipes with a nominal diameter of less than 1 / 2 inch are not used as the gas refrigerant connection pipe 5 (see FIG. 2). Furthermore, conventionally used copper pipes for refrigerants have nominal diameters in 1 / 8 inch increments, such as 1 / 2 (= 4 / 8) inch, 5 / 8 inch, 3 / 4 (= 6 / 8) inch, 7 / 8 inch, and 1 (= 8 / 8) inch, and nominal diameters in 0.5 / 8 inch increments are not used. That is, here, a copper pipe (classified as 1 / 2H) with a nominal diameter larger than 1 / 4 inch (outer diameter 6.35 mm) and smaller than 3 / 8 inch (outer diameter 9.52 mm) (here, 2.5 / 8 inch) is used as the gas refrigerant connecting pipe 5 to which utilization units 4a, 4b with a rated refrigeration capacity of 4.5 kW or less are connected, the inner diameter being 6.2 mm or less, which is too small for use as a gas refrigerant connecting pipe with conventional refrigerants, and which has not been used conventionally.

[0087] As a result, here, it is possible to reduce the volume of the gas refrigerant connection pipe 5, and to reduce the amount of refrigerant sealed in the refrigerant circuit 7. Moreover, here, because a copper pipe with a nominal diameter that has not conventionally been used as a gas refrigerant connection pipe is used, the size of the copper pipe that can be used as the gas refrigerant connection pipe 5 can be increased, which can contribute to optimizing the gas refrigerant connection pipe 5.

[0088] (5) Variations < / c> In the above embodiment, copper pipes (with a 1 / 2H quality) such as phosphorus-deoxidized copper seamless copper pipes are used as the pipe material for the refrigerant connection pipes 5 and 6 (see FIG. 2). However, there are various qualities of copper pipes, and in addition to "1 / 2H," the qualities used as copper pipes for refrigerants include "H," which has been subjected to work hardening so that its tensile strength is higher than that of "1 / 2H," and "O," which has been annealed without being subjected to work hardening during manufacturing (low tensile strength).

[0089] Therefore, here, as shown in Figure 4, copper pipes of quality O are used as the pipe material for the refrigerant communication pipes 5 and 6. Note that Figure 4 also shows, as a comparative example, a case in which copper pipes of quality 1 / 2H are used.

[0090] According to Fig. 4, a copper pipe with a nominal diameter of less than 1 / 4 inch (outer diameter of 6.35 mm) is used for the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b with a rated refrigeration capacity of 3.6 kW or less are connected. Specifically, a copper pipe with a nominal diameter of 1.5 / 8 inch (outer diameter of 4.7 mm) is used for the liquid refrigerant connection pipe 6 with a nominal diameter of less than 1 / 4 inch. Here, since a copper pipe with a nominal diameter of 1.5 / 8 inch has an inner diameter of 2.8 mm, this means that a pipe with an inner diameter of 3.6 mm or less is used for the liquid refrigerant connection pipe 6, as in the case of a 1 / 2H quality.

[0091] Also, according to FIG. 4, a copper pipe with a nominal diameter of 1 / 4 inch (outer diameter 6.35 mm, inner diameter 3.8 mm) is used as the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b, each of which has a rated refrigeration capacity of more than 3.6 kW and not more than 7.1 kW, are connected.

[0092] 4, a copper pipe with a nominal diameter larger than 1 / 4 inch (outer diameter 6.35 mm) and smaller than 3 / 8 inch (outer diameter 9.52 mm) is used as the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b with a rated refrigeration capacity larger than 7.1 kW and smaller than 14.0 kW are connected. Specifically, a copper pipe with a nominal diameter of 2.5 / 8 inch (outer diameter 7.94 mm, inner diameter 4.8 mm) is used as the liquid refrigerant connection pipe 6 with a nominal diameter larger than 1 / 4 inch and smaller than 3 / 8 inch.

[0093] Also, according to FIG. 4, a copper pipe with a nominal diameter of 3 / 8 inch (outer diameter 9.52 mm, inner diameter 5.8 mm) is used as the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b, each of which has a rated refrigeration capacity of more than 14.0 kW and not more than 22.4 kW, are connected.

[0094] Also, according to FIG. 4, a copper pipe with a nominal diameter of 1 / 2 inch (outer diameter 12.70 mm, inner diameter 7.7 mm) is used as the liquid refrigerant connection pipe 6 to which the utilization units 4a, 4b, whose rated refrigeration capacity is greater than 22.4 kW and less than 28.0 kW, are connected.

[0095] Also, according to Fig. 4, a copper pipe with a nominal diameter larger than 1 / 4 inch (outer diameter 6.35 mm) and smaller than 3 / 8 inch (outer diameter 9.52 mm) is used as the gas refrigerant communication pipe 5 to which the utilization units 4a, 4b with a rated refrigeration capacity of 2.8 kW or less are connected. Specifically, a copper pipe with a nominal diameter of 2.5 / 8 inch (outer diameter 7.94 mm) is used as the gas refrigerant communication pipe 5 with a nominal diameter larger than 1 / 4 inch and smaller than 3 / 8 inch. Here, since a copper pipe with a nominal diameter of 2.5 / 8 inch has an inner diameter of 4.8 mm or less, this means that a pipe with an inner diameter of 6.2 mm or less is used as the gas refrigerant communication pipe 5, as in the case of a 1 / 2H quality.

[0096] 4, a copper pipe with a nominal diameter of 3 / 8 inch (outer diameter 9.52 mm) is used as the gas refrigerant connection pipe 5 to which utilization units 4a, 4b with a rated refrigeration capacity of more than 2.8 kW and not more than 4.5 kW are connected. Here, a copper pipe with a nominal diameter of 3 / 8 inch has an inner diameter of 5.8 mm or less, which means that a pipe with an inner diameter of 6.2 mm or less is used as the gas refrigerant connection pipe 5, as in the case of a 1 / 2H quality.

[0097] Also, according to FIG. 4, a copper pipe with a nominal diameter of 1 / 2 inch (outer diameter 12.70 mm, inner diameter 7.7 mm) is used as the gas refrigerant communication pipe 5 to which the utilization units 4a, 4b, each of which has a rated refrigeration capacity of more than 4.5 kW and not more than 9.0 kW, are connected.

[0098] Also, according to FIG. 4, a copper pipe with a nominal diameter of 5 / 8 inch (outer diameter 15.88 mm, inner diameter 9.7 mm) is used as the gas refrigerant communication pipe 5 to which the utilization units 4a, 4b, each having a rated refrigeration capacity of more than 9.0 kW and not more than 16.0 kW, are connected.

[0099] Also, according to FIG. 4, a copper pipe with a nominal diameter of 3 / 4 inch (outer diameter 19.05 mm, inner diameter 11.7 mm) is used as the gas refrigerant communication pipe 5 to which the utilization units 4a, 4b, each having a rated refrigeration capacity of more than 16.0 kW and not more than 28.0 kW, are connected.

[0100] Also, according to FIG. 4, when using copper pipes of quality O, the inner diameter of the gas refrigerant connecting pipes 5, 6 is selected to be the same as that when using copper pipes of quality 1 / 2H at the same rated refrigerating capacity.

[0101] Then, by using the table of pipe diameters of the refrigerant communication pipes 5, 6 shown in FIG. 4, the pipe diameters of the refrigerant communication pipes 5, 6 when using copper pipes of quality O can be selected as follows.

[0102] For example, if the rated refrigeration capacity of both utilization units 4a, 4b is 2.8 kW, then the gas refrigerant communication branch pipes 52a, 52b are made of copper pipes with a nominal diameter of 2.5 / 8 inches, and the liquid refrigerant communication branch pipes 62a, 62b are made of copper pipes with a nominal diameter of 1.5 / 8 inches. Then, after the utilization units 4a, 4b are joined, the total rated refrigeration capacity becomes 5.6 kW, so that the gas refrigerant communication main pipe 51 is made of copper pipes with a nominal diameter of 1 / 2 inch, and the liquid refrigerant communication main pipe 61 is made of copper pipes with a nominal diameter of 1 / 4 inch.

[0103] Furthermore, for example, if the rated refrigeration capacities of both utilization units 4a, 4b are 11.2 kW, then the gas refrigerant communication branch pipes 52a, 52b are made of copper pipes with a nominal diameter of 5 / 8 inch, and the liquid refrigerant communication branch pipes 62a, 62b are made of copper pipes with a nominal diameter of 2.5 / 8 inch. Then, after the utilization units 4a, 4b are joined, the total rated refrigeration capacity becomes 22.4 kW, so that the gas refrigerant communication main pipe 51 is made of copper pipes with a nominal diameter of 3 / 4 inch, and the liquid refrigerant communication main pipe 61 is made of copper pipes with a nominal diameter of 3 / 8 inch.

[0104] Furthermore, for example, if the rated refrigeration capacity of the utilization unit 4a is 2.2 kW and the rated refrigeration capacity of the utilization unit 4b is 9.0 kW, then a copper pipe with a nominal diameter of 2.5 / 8 inches is used for the gas refrigerant communication branch pipe 52a, a copper pipe with a nominal diameter of 1 / 2 inches is used for the gas refrigerant communication branch pipe 52b, a copper pipe with a nominal diameter of 1.5 / 8 inches is used for the liquid refrigerant communication branch pipe 62a, and a copper pipe with a nominal diameter of 2.5 / 8 inches is used for the liquid refrigerant communication branch pipe 62b. Then, after the utilization units 4a, 4b are joined, the total rated refrigeration capacity becomes 11.2 kW, so a copper pipe with a nominal diameter of 5 / 8 inches is used for the gas refrigerant communication mother pipe 51, and a copper pipe with a nominal diameter of 2.5 / 8 inches is used for the liquid refrigerant communication mother pipe 61.

[0105] Here, as described above, in the air conditioning apparatus 1 (refrigeration cycle apparatus) in which the heat source unit 2 and the utilization units 4a, 4b are connected via a gas refrigerant connection pipe 5 and a liquid refrigerant connection pipe 6 to form the refrigerant circuit 7, as in the case of using copper pipes with a quality of 1 / 2H, the refrigerant sealed in the refrigerant circuit 7 is carbon dioxide, and the gas refrigerant connection pipe 5 is a pipe with an inner diameter of 6.2 mm or less, and / or the liquid refrigerant connection pipe 6 is a pipe with an inner diameter of 3.6 mm or less (see FIG. 4).

[0106] As a result, as in the case of using copper pipes with a quality classification of 1 / 2H, the volume of the gas refrigerant connection pipe 5 and / or the liquid refrigerant connection pipe 6 can be reduced, and the amount of refrigerant sealed in the refrigerant circuit 7 can be reduced.

[0107] As described above, a copper pipe (quality O) with a nominal diameter of less than 1 / 4 inch (outer diameter 6.35 mm) is used as the liquid refrigerant connecting pipe 6 with an inner diameter of 3.6 mm or less, just as in the case of using a copper pipe with a quality of 1 / 2H (see FIG. 4). Specifically, a copper pipe (quality O) with a nominal diameter of 1.5 / 8 inch (outer diameter 4.76 mm) is used here (see FIG. 4). However, unlike the case of using a copper pipe with a quality of 1 / 2H, a copper pipe with this nominal diameter is used as the liquid refrigerant connecting pipe 6 to which utilization units 4a, 4b with a rated refrigeration capacity of 3.6 kW or less are connected.

[0108] As a result, here, as in the case of using copper pipes with a quality of 1 / 2H, the volume of the liquid refrigerant connection pipe 6 can be reduced, and the amount of refrigerant sealed in the refrigerant circuit 7 can be reduced. Moreover, because a copper pipe with a nominal diameter that has not been used as a liquid refrigerant connection pipe in the past is used here, the size of the copper pipe that can be used as the liquid refrigerant connection pipe 6 can be increased, which contributes to optimizing the liquid refrigerant connection pipe 6. In addition, because a copper pipe with a quality of O is used as the liquid refrigerant connection pipe 6 here, it is easier to handle, such as by bending, compared to when using copper pipes with a quality of 1 / 2H, and this improves the ease of construction when connecting the heat source unit 2 and the utilization units 4a, 4b on site.

[0109] As described above, a copper pipe (quality O) with a nominal diameter larger than 1 / 4 inch (outer diameter 6.35 mm) and smaller than 3 / 8 inch (outer diameter 9.52 mm) is used as the gas refrigerant communication pipe 5 with an inner diameter of 6.2 mm or less, in the same manner as when a copper pipe with a quality of 1 / 2H is used (see FIG. 4). Specifically, a copper pipe (quality O) with a nominal diameter of 2.5 / 8 inch (outer diameter 7.94 mm) is used (see FIG. 4). However, unlike when a copper pipe with a quality of 1 / 2H is used, a copper pipe with this nominal diameter is used as the gas refrigerant communication pipe 5 to which utilization units 4a, 4b with a rated refrigeration capacity of 2.8 kW or less are connected.

[0110] As a result, here, as in the case of using copper pipes with a quality of 1 / 2H, the volume of the gas refrigerant connection pipe 5 can be reduced, and the amount of refrigerant sealed in the refrigerant circuit 7 can be reduced. Moreover, here, because a copper pipe with a nominal diameter that has not been used as a gas refrigerant connection pipe in the past is used, the size of the copper pipe that can be used as the gas refrigerant connection pipe 5 can be increased, which contributes to optimizing the gas refrigerant connection pipe 5. In addition, here, because a copper pipe with a quality of O is used as the gas refrigerant connection pipe 5, handling such as bending is easier than when using copper pipes with a quality of 1 / 2H, and workability can be improved when connecting the heat source unit 2 and the utilization units 4a, 4b on site.

[0111] In the above embodiment and modified examples, in order to improve ease of installation when connecting the heat source unit 2 and the utilization units 4a, 4b on site, the gas refrigerant connection pipe 5 and the liquid refrigerant connection pipe 6 may form a pair refrigerant connection pipe 8, as shown in FIG. 5.

[0112] Here, the paired refrigerant connection pipes 8 have a structure in which the outer surfaces of the refrigerant connection pipes 5, 6 are covered with heat insulating materials 9, 10 and both pipes 5, 6 are bundled together. Here, the refrigerant connection pipes 5, 6 are covered with heat insulating materials 9, 10 having a two-layer structure, and the refrigerant connection pipes 5, 6 are bundled together by connecting the outer surfaces of the heat insulating materials 9, 10. Such paired refrigerant connection pipes 8 can be prepared for each rated refrigeration capacity. For example, when copper pipes with a quality of 1 / 2H are used as the refrigerant connection pipes 5, 6 according to the pipe diameter table in FIG. 4, a paired refrigerant connection pipe 8 with a gas refrigerant connection pipe 5 of 2.5 / 8 inches and a liquid refrigerant connection pipe 6 of 1.5 / 8 inches is prepared for a rated refrigeration capacity of 2.2 to 4.5 kW. In addition, a paired refrigerant connection pipe 8 with a gas refrigerant connection pipe 5 of 3 / 8 inch and a liquid refrigerant connection pipe 6 of 1.5 / 8 inch is prepared for a rated refrigeration capacity of 5.6 to 8.0 kW. In addition, a paired refrigerant connection pipe 8 with a gas refrigerant connection pipe 5 of 1 / 2 inch and a liquid refrigerant connection pipe 6 of 1 / 4 inch is prepared for a rated refrigeration capacity of 9.0 to 16.0 kW. In addition, a paired refrigerant connection pipe 8 with a gas refrigerant connection pipe 5 of 5 / 8 inch and a liquid refrigerant connection pipe 6 of 2.5 / 8 inch is prepared for a rated refrigeration capacity of 22.4 to 28.0 kW. Although not described in detail, even when copper pipes of quality O are used as the refrigerant connection pipes 5 and 6, a paired refrigerant connection pipe 8 similar to the case where copper pipes of quality 1 / 2H are used as the refrigerant connection pipes 5 and 6 (however, the applicable range of the rated refrigeration capacity is different) can be prepared.

[0113] As a result, when connecting the heat source unit 2 and the utilization units 4a, 4b on-site, the above-mentioned paired refrigerant connection pipes 8 can be used, improving workability. In particular, since pipes with nominal diameters in 0.5 / 8 inch increments (here, 1.5 / 8 inch and 2.5 / 8 inch) that are not used with conventional refrigerants (R410A, R32, etc.) may be used, preparing paired refrigerant connection pipes 8 including pipes with such nominal diameters is extremely useful for improving workability.

[0114] <c> In the above embodiment and modified examples, when the refrigerant communication pipes 5, 6 are long or branched, pipe joints such as socket pipes 53a, 63a and branch pipes 54a, 64a for connecting the pipes are required as shown in Fig. 3. However, such pipe joints that have been used conventionally are compatible with pipes with nominal diameters in 1 / 8 inch increments, but are not compatible with pipes with nominal diameters in 0.5 / 8 inch increments, such as pipes with nominal diameters of 1.5 / 8 inch and 2.5 / 8 inch (see Fig. 4).

[0115] Therefore, here, as shown in Fig. 6, the pipe end of a pipe with a nominal diameter of 1.5 / 8 inches used as a liquid refrigerant connection pipe 6 with a nominal diameter of less than 1 / 4 inch has a different diameter section 6a enlarged to a nominal diameter of 1 / 4 inch (=2 / 8 inch). Also, as shown in Fig. 6, the pipe end of a pipe with a nominal diameter of 2.5 / 8 inches used as a gas refrigerant connection pipe 5 with a nominal diameter of more than 1 / 4 inch and less than 3 / 8 inch and a liquid refrigerant connection pipe 6 has different diameter sections 5a, 6a enlarged to a nominal diameter of 3 / 8 inch.

[0116] As a result, even when a pipe with a nominal diameter of 1.5 / 8 inches is used as the liquid refrigerant communication pipe 6 with a nominal diameter of less than 1 / 4 inch, conventional pipe joints corresponding to pipes with a nominal diameter in increments of 1 / 8 inch can be used. That is, even when a pipe with a nominal diameter of 1.5 / 8 inches is used as the liquid refrigerant communication branch pipes 62a, 62b and the liquid refrigerant communication mother pipe 61 in FIG. 3, the socket pipe 63a and the branch pipe 64a can be used that correspond to a pipe with a nominal diameter of 1 / 4 inch. Therefore, it is not necessary to prepare pipe joints corresponding to pipes with a nominal diameter in increments of 0.5 / 8 inch, improving workability. Also, even when a pipe with a nominal diameter of 2.5 / 8 inches is used as the gas refrigerant communication pipe 5 and the liquid refrigerant communication pipe 6 with a nominal diameter larger than 1 / 4 inch and less than 3 / 8 inch, conventional pipe joints corresponding to pipes with a nominal diameter in increments of 1 / 8 inch can be used. That is, even if pipes with a nominal diameter of 2.5 / 8 inches are used as the refrigerant communication branch pipes 52a, 52b, 62a, 62b and the refrigerant communication main pipes 51, 61 in Fig. 3, the socket pipes 53a, 63a and branch pipes 54a, 64a can be those corresponding to pipes with a nominal diameter of 3 / 8 inches. This makes it possible to dispense with the need to prepare pipe joints corresponding to pipes with nominal diameters in 0.5 / 8 inch increments, improving ease of installation.

[0117] <d> In the above embodiment and modified example, the refrigeration cycle apparatus is described taking as an example an air conditioner 1 capable of heating and cooling having two utilization units 4a and 4b, but the refrigeration cycle apparatus is not limited to this. For example, the refrigeration cycle apparatus may be an air conditioner dedicated to cooling, or may be an air conditioner having one utilization unit or three or more utilization units.

[0118] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the present disclosure described in the claims. [Industrial Applicability]

[0119] INDUSTRIAL APPLICABILITY The present disclosure is widely applicable to refrigeration cycle devices in which a refrigerant circuit is formed by connecting a heat source unit and a utilization unit via a refrigerant communication pipe, and carbon dioxide is used as the refrigerant sealed in the refrigerant circuit. [Explanation of symbols]

[0120] 1. Air conditioning equipment (refrigeration cycle equipment) 2 Heat source unit 4a, 4b User Unit 5 Gas refrigerant connection pipe 5a Different diameter part 6 Liquid refrigerant connection pipe 6a Different diameter part 7 Refrigerant circuit 8 pairs of refrigerant connecting pipes [Prior art documents] [Patent documents]

[0121] [Patent Document 1] International Publication No. 2011 / 099063< / d> < / c>

Claims

1. A refrigeration cycle device in which a heat source unit (2) and utilization units (4a, 4b) are connected via a gas refrigerant connection pipe (5) and a liquid refrigerant connection pipe (6) to form a refrigerant circuit (7), The refrigerant charged in the refrigerant circuit is carbon dioxide, As the gas refrigerant communication pipe, a pipe having an inner diameter of 6.2 mm or less is used, The gas refrigerant connecting pipe to which the utilization unit having a rated refrigeration capacity of 4.5 kW or less is connected is made of copper pipe having a nominal diameter of 2.5 / 8 inches (1 / 2H quality). Or, The gas refrigerant connecting pipe to which the utilization unit having a rated refrigeration capacity of 2.8 kW or less is connected is made of copper pipe (quality O) having a nominal diameter of 2.5 / 8 inches. Refrigeration cycle device (1).

2. The gas refrigerant communication pipe and the liquid refrigerant communication pipe are covered on their outer surfaces with a heat insulating material, and the two pipes are bundled together to form a pair of refrigerant communication pipes (8). The refrigeration cycle device according to claim 1.

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