Air conditioner

Abstract

An air conditioner according to the present invention has a refrigeration cycle including a hermetic compressor in which refrigerator oil is stored, and uses a mixed refrigerant containing a fluoroolefin and propane as a refrigerant. A working medium for a refrigeration cycle, which comprises a refrigerant oil and a mixed refrigerant, has a refrigerant dissolution viscosity in the range of 2-4 mm2 / s under working conditions of a temperature in the range of 28-60 DEG C and an absolute pressure in the range of 2.2-4.3 MPa. As a result, in an air conditioner using a working medium for a refrigeration cycle containing a fluoroolefin, excellent COP can be achieved, and disproportionation reactions of the fluoroolefin can be satisfactorily suppressed.

Description

Technical Field

[0001] The present invention relates to an air conditioner using a refrigeration cycle working medium containing fluoroolefin, and in particular to an air conditioner capable of well suppressing the disproportionation reaction of fluoroolefin. Background Art

[0002] The working medium for the refrigeration cycle is usually composed of a refrigerant and a refrigeration oil (lubricating oil stored in a sealed compressor). HCFC (chlorofluorocarbon) was previously used as a refrigerant, but HCFC has a great impact on the destruction of the ozone layer. Therefore, in recent years, HFC (hydrofluorocarbon) with an ozone depletion potential (ODP) of 0 has been used. Typically, difluoromethane (HFC32, R32) can be cited.

[0003] However, HFC, which is stable as a working medium for refrigeration cycles, has a large global warming potential (GWP) due to its long atmospheric life. Therefore, the use of fluoroolefins with a lower GWP, especially hydrofluoroolefins (HFO), has recently been proposed. As an HFO with a low GWP, high cooling capacity, and performance close to that of the currently widely used R32, for example, 1,1,2-trifluoroethylene (HFO1123) is known.

[0004] Here, low GWP means short atmospheric lifetime, in other words, fluoroolefins are easily chemically decomposed and have low stability. Therefore, it is known that a self-polymerization reaction called disproportionation reaction (hereinafter referred to as disproportionation reaction) is easily generated in fluoroolefins such as HFO1123.

[0005] The disproportionation reaction is easily induced by the heat generated during the use of the working medium for the refrigeration cycle, and the disproportionation reaction is accompanied by a large amount of heat release. Therefore, the disproportionation reaction also occurs in a chain reaction. As a result, a large amount of soot is generated, which may reduce the reliability of the refrigeration cycle system or the compressor constituting the system.

[0006] In a refrigeration system using a working medium for a refrigeration cycle, a coefficient of performance (COP) is known as one of the indicators for evaluating its performance. For example, when a refrigeration system is applied to an air conditioner, the COP is calculated as a ratio of cooling capacity (or cooling and heating capacity) to energy consumption in the refrigeration system.

[0007] In a refrigeration system using HFO as a working medium for a refrigeration cycle, as a technology for improving COP, for example, there are exemplified a refrigerator, a method for manufacturing a refrigerator, and a method for improving COP disclosed in Patent Document 1.

[0008] In the refrigeration system (refrigerating machine) disclosed in Patent Document 1, the working medium for the refrigeration system is not limited to fluoroolefins, and fluorine-containing refrigerants such as HFC and HFO, hydrocarbon refrigerants, ammonia (R717), carbon dioxide (R744) and other natural refrigerants can be used. In Patent Document 1, a mixed refrigerant combining multiple refrigerants is used as a representative refrigerant, and as a working medium for the refrigeration system composed of the mixed refrigerant and refrigeration oil, a 2-4 mm thick refrigerant is used at a temperature of 80°C and an absolute pressure of 3.4 MPa. 2 / s refrigerant with a refrigerant dissolving viscosity.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2017-141974 Summary of the invention

[0012] Problems to be solved by the invention

[0013] However, in the refrigeration system disclosed in Patent Document 1, as described above, the refrigerant is not limited to fluoroolefins, so it is difficult to well suppress the disproportionation reaction of fluoroolefins. In particular, when the refrigeration system is applied to an air conditioner, it is required that when a refrigeration cycle working medium containing fluoroolefins is used, not only a good COP can be achieved, but also the disproportionation reaction of fluoroolefins can be well suppressed.

[0014] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to achieve a good COP and to well suppress the disproportionation reaction of fluoroolefins in an air conditioner using a refrigeration cycle working medium containing fluoroolefins.

[0015] Methods for solving problems

[0016] In order to solve the above-mentioned problems, an air conditioner of the present invention has a refrigeration cycle including a sealed compressor storing refrigeration oil therein, and uses a mixed refrigerant containing fluoroolefin and propane as a refrigerant, and a working medium for the refrigeration cycle consisting of at least the refrigeration oil and the mixed refrigerant has a refrigerant solution viscosity of 2 to 4 mm under working conditions within a temperature range of 28°C to 60°C and an absolute pressure range of 2.2 MPa to 4.3 MPa. 2 / s range.

[0017] According to the above structure, since the refrigerant dissolving viscosity of the working medium for the refrigeration cycle is within the above range, propane in the mixed refrigerant is easily dissolved in the refrigeration oil. Therefore, when the hermetic compressor is stopped, the apparent content of fluoroolefins contained in the mixed refrigerant inside increases. On the contrary, when the hermetic compressor is running, the propane dissolved in the refrigeration oil is released from the refrigeration oil as the temperature rises.

[0018] Therefore, propane, which is relatively easy to burn, is easy to dissolve in the refrigeration oil when the sealed compressor stops. As a result, the apparent content of propane in the mixed refrigerant is reduced. Therefore, even if the mixed refrigerant leaks, the combustion risk can be well reduced. On the other hand, during the operation of the sealed compressor, since propane is freed from the refrigeration oil, the apparent content of propane in the mixed refrigerant increases. Since propane has the effect of inhibiting the disproportionation reaction of fluoroolefins, the disproportionation reaction of fluoroolefins can be well inhibited.

[0019] Furthermore, if the refrigerant dissolving viscosity of the working medium for the refrigeration cycle is within the above range, it is possible to simultaneously suppress the energy consumption of the refrigeration cycle and achieve a good refrigeration capacity. As a result, in an air conditioner using a working medium for the refrigeration cycle containing fluoroolefins, a good COP can be achieved and the disproportionation reaction of fluoroolefins can be well suppressed.

[0020] The above-mentioned object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.

[0021] Effects of the Invention

[0022] In the present invention, the above-described configuration provides the following effects: in an air conditioner using a refrigeration cycle working medium containing fluoroolefin, a good COP can be achieved and the disproportionation reaction of fluoroolefin can be suppressed well. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic piping diagram showing a typical configuration of an air conditioner according to a typical embodiment of the present invention.

[0024] Figure 2 Yes means Figure 1 2 is a cross-sectional view showing a typical structure of a hermetic compressor included in an air conditioner shown in FIG.

[0025] Figure 3 middle, Figure 3 A is a graph showing an example of the relationship between the refrigeration cycle working medium composed of a typical mixed refrigerant and refrigeration oil in this embodiment and the COP of the air conditioner. Figure 3 B stands for composition Figure 3 A is a graph showing the relationship between the compatibility of fluoroolefins and propane, which are representative mixed refrigerants, with refrigerator oil and the temperature. DETAILED DESCRIPTION

[0026] The air conditioner of the present invention has a refrigeration cycle, the refrigeration cycle includes a sealed compressor storing refrigeration oil therein, and a mixed refrigerant containing fluoroolefin and propane is used as a refrigerant, and the working medium for the refrigeration cycle composed of at least the refrigeration oil and the mixed refrigerant has a refrigerant solution viscosity of 2 to 4 mm under working conditions within a temperature range of 28°C to 60°C and an absolute pressure range of 2.2 MPa to 4.3 MPa. 2 / s range.

[0027] According to the above structure, since the refrigerant dissolving viscosity of the working medium for the refrigeration cycle is within the above range, propane in the mixed refrigerant is easily dissolved in the refrigeration oil. Therefore, when the hermetic compressor is stopped, the apparent content of fluoroolefins contained in the mixed refrigerant inside increases. On the contrary, when the hermetic compressor is running, the propane dissolved in the refrigeration oil is released from the refrigeration oil as the temperature rises.

[0028] Therefore, propane, which is relatively easy to burn, is easy to dissolve in the refrigeration oil when the sealed compressor stops. As a result, the apparent content of propane in the mixed refrigerant is reduced. Therefore, even if the mixed refrigerant leaks, the risk of combustion can be well reduced. On the other hand, during the operation of the sealed compressor, since propane is freed from the refrigeration oil, the apparent content of propane in the mixed refrigerant increases. Since propane has the effect of inhibiting the disproportionation reaction of fluoroolefins, the disproportionation reaction of fluoroolefins can be well inhibited.

[0029] Furthermore, if the refrigerant dissolving viscosity of the working medium for the refrigeration cycle is within the above range, it is possible to simultaneously suppress the energy consumption of the refrigeration cycle and achieve a good refrigeration capacity. As a result, in an air conditioner using a working medium for the refrigeration cycle containing fluoroolefins, a good COP can be achieved and the disproportionation reaction of fluoroolefins can be well suppressed.

[0030] In the air conditioner of the above structure, the working medium for the refrigeration cycle can also be in the temperature range of 115°C or less and the absolute pressure range of 1.7MPa to 4.6MPa under the working conditions, and the refrigerant solution viscosity is also in the range of 2 to 4mm. 2 / s within the scope of the structure.

[0031] Furthermore, in the air conditioner having the above-described structure, the temperature range under the above-described operating conditions may be within a range of 55° C. to 115° C.

[0032] In addition, in the air conditioner of the above-mentioned structure, the mixed refrigerant can also adjust its compatibility with the refrigeration oil when the temperature under the working conditions exceeds 115°C so that the ratio of propane in the hermetic compressor to the total mass of fluoroolefins and propane is greater than 20 mass%.

[0033] In addition, in the air conditioner of the above structure, the mixed refrigerant can also adjust its compatibility with the refrigeration oil when the temperature under the working conditions is below 115°C so that the ratio of propane in the hermetic compressor to the total mass of fluoroolefins and propane is less than 20 mass%.

[0034] In the air conditioner having the above configuration, the mixed refrigerant may have a ratio of propane exceeding 20% ​​by mass with respect to the total mass of the fluoroolefin and propane before the mixed refrigerant is sealed in the refrigeration cycle.

[0035] In the air conditioner having the above structure, the fluoroolefin may be at least one selected from the group consisting of 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, and monofluoroethylene.

[0036] In the air conditioner having the above structure, the mixed refrigerant may contain difluoromethane.

[0037] Furthermore, in the air conditioner having the above-described structure, the mixed refrigerant may contain a disproportionation inhibitor.

[0038] In the air conditioner of the above structure, the disproportionation inhibitor may be a saturated hydrocarbon having 2 to 5 carbon atoms (excluding propane) or a halogenated alkane having 1 or 2 carbon atoms (excluding fluoroalkanes in which the halogen atom is substituted only with fluorine).

[0039] Furthermore, in the air conditioner having the above-described structure, the compression mechanism of the sealed compressor may be a rotary structure.

[0040] In the air conditioner having the above-described structure, the sealed compressor may be configured to be frequency-inverter driven.

[0041] Hereinafter, a typical embodiment of the present invention will be described with reference to the accompanying drawings. In addition, in all the drawings below, the same reference numerals are given to the same or corresponding elements, and their repeated descriptions are omitted.

[0042] [Structural example of air conditioner and sealed compressor]

[0043] Figure 1 1 is a schematic diagram showing a representative example of the air conditioner 10 according to the present embodiment. Figure 1 As shown, the air conditioner 10 includes an outdoor unit 11 and an indoor unit 12, and these units 11 and 12 are connected by an inter-unit piping 13. The indoor unit 12 is installed in a space to be air conditioned (as the target space), and the outdoor unit 11 is installed outdoors outside the target space. The inter-unit piping 13 is provided with a piping connection portion 13a and a piping connection portion 13b.

[0044] The air conditioner 10 allows the refrigerant compressed in the outdoor unit 11 to flow between the outdoor unit 11 and the indoor unit 12 to perform air conditioning in the target space provided with the indoor unit 12. The air conditioner 10 can switch between a cooling operation mode for cooling the target space and a heating operation mode for heating the target space.

[0045] The outdoor unit 11 includes a sealed compressor 20, an outdoor heat exchanger 14, an outdoor fan 15, an expansion valve 16, a switching valve 17, and the like. The sealed compressor 20 compresses the refrigeration cycle working medium containing the refrigerant. The outdoor heat exchanger 14 performs heat exchange of the refrigerant outside the target space (outdoors). The outdoor fan 15 delivers outdoor air to the outdoor heat exchanger 14. The expansion valve 16 decompresses the refrigerant to expand it. The switching valve 17 switches to a cooling operation mode or a heating operation mode.

[0046] The indoor unit 12 includes an indoor heat exchanger 18, an indoor fan 19, etc. The indoor heat exchanger 18 performs heat exchange with the refrigerant supplied from the outdoor unit 11 via the inter-unit pipe 13 in the target space. The indoor fan 19 moves the air in the target space (indoors) in the target space.

[0047] The outdoor heat exchanger 14 functions as a condenser in the cooling operation mode and as an evaporator in the heating operation mode. The indoor heat exchanger 18 functions as an evaporator in the cooling operation mode and as a condenser in the heating operation mode. The hermetic compressor 20, the outdoor heat exchanger 14 (condenser or evaporator), the indoor heat exchanger 18 (evaporator or condenser) and the expansion valve 16 are connected in a ring shape through the inter-unit piping 13, thereby forming a refrigeration cycle (refrigerant circuit).

[0048] The air conditioner 10 also includes a control unit. The control unit controls the operation of the sealed compressor 20, controls the opening and / or opening and closing of the expansion valve 16, controls the switching of the flow path of the switching valve 17, and controls the operation and / or stopping of the outdoor fan 15 and the indoor fan 19. In addition, the control unit operates the expansion valve 16 and the switching valve 17 to switch the cooling operation mode and the heating operation mode of the air conditioner 10. In addition, the control unit also controls the operating frequency, operation and / or stopping of the sealed compressor 20, controls the outdoor fan 15 and the indoor fan 19 according to the operation or setting of the operating unit of the air conditioner 10, and air-conditions the target space according to the target temperature.

[0049] exist Figure 1 In the example shown, the thick arrows indicate the flow direction of the refrigerant in the cooling operation mode. In the cooling operation mode of the air conditioner 10, the refrigerant (the working medium for the refrigeration cycle) flows sequentially through the sealed compressor 20, the outdoor heat exchanger 14, the expansion valve 16, the indoor heat exchanger 18, the switching valve 17, and returns to the sealed compressor 20 from the switching valve 17. In addition, the flow direction of the refrigerant in the heating operation mode is Figure 1 In the heating operation mode of the air conditioner 10 , the refrigerant flows through the sealed compressor 20 , the indoor heat exchanger 18 , the expansion valve 16 , the outdoor heat exchanger 14 , the switching valve 17 in sequence, and returns to the sealed compressor 20 from the switching valve 17 .

[0050] The pipe connection part 13a and the pipe connection part 13b of the air conditioner 10 are provided between the outdoor unit 11 and the indoor unit 12 in the inter-unit pipe 13 connected in a ring shape. As these pipe connection parts 13a and 13b, for example, a two-way valve or a three-way valve is used. Thus, the outdoor unit 11 and the indoor unit 12 are connected to each other, and the refrigerant can be circulated. In addition, the pipe connection parts 13a and 13b can be controlled to open and / or open and close manually or by the control of the control unit.

[0051] In addition, there is no particular restriction on the specific structure of each component (sealed compressor 20, outdoor heat exchanger 14, outdoor fan 15, expansion valve 16, switching valve 17, indoor heat exchanger 18, indoor fan 19, inter-unit piping 13, piping connection parts 13a, 13b, etc.) constituting the air conditioner 10, outdoor unit 11, indoor unit 12, and refrigeration cycle (refrigerant circuit), and various known structures can be preferably adopted. In addition, the specific structure of the refrigeration cycle (refrigerant circuit) is not limited to Figure 1 The structural examples shown may include other components or may not include some of the components.

[0052] Below, refer to Figure 2A specific structure of an example of the hermetic compressor 20 of the present invention will be described. Figure 2 2 is a cross-sectional view showing a typical structural example of the hermetic compressor 20 according to the present embodiment. Figure 2 As shown, the hermetic compressor 20 of the present embodiment is a rotary type.

[0053] like Figure 2 As shown, the entire internal space of the sealed container 21 is a discharge pressure atmosphere connected to the discharge pipe 22, and the electric motor 23 and the compression mechanism 30 are accommodated in the sealed container 21. Figure 2 In the example shown, the motor 23 is located in the center of the closed container 21, and the compression mechanism 30 is located in the lower part.

[0054] The motor 23 is composed of a rotor 24 and a stator 25. The stator 25 is arranged on the outer diameter side of the rotor 24 in a manner that a substantially constant gap is maintained with the rotor 24. A crankshaft 26 is fixed to the rotor 24 corresponding to the rotating shaft, and when the motor 23 starts to drive, the rotor 24 rotates, thereby the crankshaft 26 drives the compression mechanism 30. The crankshaft 26 is integrally formed with a crankshaft eccentric portion 27.

[0055] In the present embodiment, the motor 23 is driven by, for example, an inverter drive circuit at a plurality of operating frequencies including an operating frequency exceeding the industrial frequency power supply frequency. Therefore, the hermetic compressor 20 of the present embodiment may also include an inverter circuit so that the motor 23 can be rotationally driven at a plurality of operating speeds. In addition, the specific driving method of the hermetic compressor 20 is not limited to the above-mentioned variable frequency drive. For example, the hermetic compressor 20 can also be driven by a simple on / off control. In addition, in the case where the hermetic compressor 20 is variable frequency driven by an inverter circuit, its operating frequency is not particularly limited.

[0056] The compression mechanism 30 includes a cylinder 31, a rolling piston 32, a vane 33, an upper bearing 34, a lower bearing 35, etc. The cylinder 31, the rolling piston 32, and the vane 33 are sandwiched by the upper bearing 34 and the lower bearing 35, thereby forming a suction chamber 30a and a compression chamber 30b. The crankshaft eccentric portion 27 is accommodated in the cylinder 31, and the rolling piston 32 is rotatably mounted on the crankshaft eccentric portion 27. In the cylinder 31, the vane 33 is provided in contact with the rolling piston 32 to separate the suction chamber 30a and the compression chamber 30b.

[0057] The cylinder 31 is provided with a suction hole 30c adjacent to the suction chamber 30a. The suction liner 36 is inserted into the suction hole 30c. The high-temperature and high-pressure exhaust gas inside the closed container 21 and the low-temperature and low-pressure suction gas inside the suction hole 30c are separated by the suction liner 36. In order to prevent the liquid of the compressor from being compressed, an accumulator 40 is connected to the suction liner 36. The accumulator 40 is connected to the suction outer pipe 37 fixed to the closed container 21 by brazing or welding to separate the gas and liquid of the working medium for the refrigeration cycle in the suction sealed compressor 20.

[0058] Refrigeration oil 50 is stored in the lower part of the sealed container 21. The compression mechanism 30 is always immersed in the refrigeration oil 50. The refrigeration oil 50 sucked up by the crankshaft 26 lubricates the sliding part of the crankshaft eccentric part 27 through the oil supply hole provided on the crankshaft eccentric part 27, and reaches the inner circumference of the rolling piston 32 first.

[0059] A portion of the refrigeration oil 50 reaching the rolling piston 32 lubricates the journal bearing sliding portion of the upper bearing 34 and the lower bearing 35 and is discharged to the outside of the compression mechanism 30. Another portion of the refrigeration oil 50 lubricates the sliding portion of the rolling piston 32 and the upper bearing 34 and the lower bearing 35 and is supplied to the suction chamber 30a and the compression chamber 30b. The refrigeration oil 50 supplied from the back side of the vane 33 lubricates the sliding portion of the vane 33 and is supplied to the suction chamber 30a and the compression chamber 30b.

[0060] The operation of the rotary sealed compressor 20 thus constructed is described. When the motor 23 is energized and its crankshaft 26 rotates, the crankshaft eccentric portion 27 rotates eccentrically in the cylinder 31, and the rolling piston 32 rotates while contacting the vane 33, repeatedly sucking and compressing the refrigerant (working medium for the refrigeration cycle).

[0061] The specific type of the refrigeration oil 50 used in the hermetic compressor 20 is not particularly limited, and a structure in which a lubricating oil known in the field of compressors is used as a base oil and a known additive is contained as necessary can be mentioned.

[0062] The lubricating oil used as the base oil of the refrigerating machine oil 50 can be exemplified by hydrocarbon oils such as mineral oil, olefin polymer, naphthalene compound, alkylbenzene, etc.; ester oils such as monoester, diester, polyol ester, complex ester, etc.; oxygen-containing oils such as ether oils such as polyalkylene glycol, polyvinyl alcohol ether, polyphenylene ether, perfluoroether, etc.; etc., but there is no particular limitation. These base oils may be used alone or in combination of two or more.

[0063] The additives contained in the refrigerating machine oil 50 are not particularly limited, and examples thereof include oiliness agents, sliding property improvers, extreme pressure additives, antioxidants, acid scavengers, metal inert agents, defoaming agents, antiseptics, and dispersants.

[0064] In the present embodiment, the base oil of the refrigerating machine oil 50 preferably has at least one selected from polyol ester, polyalkylene glycol and polyvinyl alcohol ether as the main component, and more preferably has polyester or polyvinyl alcohol ether as the main component. The main component mentioned here means that the total amount (100% by mass) of the base oil in the refrigerating machine oil 50 is 50% by mass or more. In addition, the content of the lubricating base oil in the refrigerating machine oil 50 is not particularly limited, and it can be 80% by mass or more, 90% by mass or more, or 95% by mass or more based on the total amount (100% by mass) of the refrigerating machine oil 50.

[0065] [Refrigerant Configuration Example]

[0066] The refrigerant used in the air conditioner of the present invention is a mixed refrigerant containing fluoroolefin (fluoroolefin) and propane (R290). The specific types of fluoroolefins are not particularly limited, and examples thereof include fluoroethylenes such as 1,1,2-trifluoroethylene (HFO1123), trans-1,2-difluoroethylene (HFO1132(E)), cis-1,2-difluoroethylene (HFO1132(Z)), 1,1-difluoroethylene (HFO1132a), tetrafluoroethylene (FO1114, TFE), and monofluoroethylene (HFO1141); fluoropropylenes such as 1,2,3,3,3-pentafluoropropylene (HFO-1225ye), 2,3,3,3-tetrafluoropropylene (HFO-1234yf), 1,3,3,3-tetrafluoropropylene (HFO-1234ze), 1,2,3,3-tetrafluoropropylene (HFO-1234ye), and 3,3,3-trifluoropropylene (HFO-1243zf); and the like.

[0067] These fluoroolefins may be used alone or in combination of two or more thereof as a refrigerant. Among them, fluoroolefins can be preferably used as a refrigerant, and among these fluoroolefins, 1,1,2-trifluoroethylene (HFO1123) can be particularly preferably used.

[0068] In addition, the mixed refrigerant may contain "other refrigerants" other than fluoroolefins and propane as refrigerants. Representative other refrigerants are not particularly limited, and examples thereof include hydrofluorocarbons (HFCs), saturated hydrocarbons other than propane, and carbon dioxide.

[0069] Specific examples of HFCs include fluoromethanes such as difluoromethane (R32) and trifluoromethane (R23); fluoroethanes such as fluoroethane (R161), 1,1-difluoroethane (R152a), 1,1,1-trifluoroethane (R143a), 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a), pentafluoroethane (R125), difluoroethane, and trifluoroethane; and fluoroethanes such as 1,1,1,3,3-pentafluoropropane (R245f a), 1,1,1,2,3,3-hexafluoropropane (R236ea), 1,1,1,3,3,3-hexafluoropropane (R236fa), 1,1,1,2,3,3,3-heptafluoropropane (R227ea) and other fluoropropanes; 1,1,1,3,3-pentafluorobutane (R365mfc) and other fluorobutanes; 1,1,1,2,3,4,4,5,5,5-decafluoropentane (R4310mee), heptafluorocyclopentane (Rc447ef) and other fluoropentanes; etc.

[0070] Specific examples of the saturated hydrocarbons include ethane, n-propane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), and methylcyclobutane.

[0071] These other refrigerants can be used in one kind only, or in combination of two or more kinds as refrigerants. Among them, R32 (difluoromethane) is typically preferably used. In addition, as described later, saturated hydrocarbons contain saturated hydrocarbons that can be used as disproportionation inhibitors. Therefore, saturated hydrocarbons can be used as other refrigerants and disproportionation inhibitors.

[0072] In addition, the mixed refrigerant may also contain a disproportionation inhibitor for inhibiting the disproportionation reaction of fluoroolefins. There are no particular restrictions on the specific disproportionation inhibitor, and examples thereof include saturated hydrocarbons having 2 to 5 carbon atoms (but excluding propane), or halogenated alkanes having any one of 1 to 4 carbon atoms except for the case where all halogen atoms are fluorine. For the sake of convenience, the saturated hydrocarbons used as the disproportionation inhibitors are referred to as "disproportionation inhibiting alkanes", and the halogenated alkanes used as the disproportionation inhibitors are referred to as "disproportionation inhibiting halogenated alkanes".

[0073] As described above, the disproportionation suppressing alkane used as the disproportionation suppressing alkane in the present invention may be any saturated hydrocarbon (alkane) having 2 to 5 carbon atoms, and specifically, ethane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylpentane), neopentane (2,2-dimethylpropane), methylcyclobutane, etc. These saturated hydrocarbons may be used alone or in combination of two or more thereof.

[0074] These saturated hydrocarbons are gases at room temperature (the boiling points of n-pentane and methylcyclobutane are the highest at about 36°C, and the boiling points of other hydrocarbons are less than 36°C), and can be well mixed as components of mixed refrigerants. Saturated hydrocarbons with more than 6 carbon atoms are liquids at room temperature, so they are difficult to mix as components of mixed refrigerants, and are therefore not preferred.

[0075] In addition, propane, which is a saturated hydrocarbon having 3 carbon atoms, can suppress the disproportionation reaction of fluoroolefins. However, as described above, since propane is the main component of the mixed refrigerant in the present invention, it is not included in the "disproportionation-inhibiting alkane". However, cyclic cyclopropane is different from linear propane (n-propane) which is a component of the mixed refrigerant, and can be used as a disproportionation-inhibiting alkane.

[0076] In addition, methane, a saturated hydrocarbon having 1 carbon atom, is not preferred because of its particularly large global warming potential (GWP). In addition, among saturated hydrocarbons having 2 to 5 carbon atoms, cyclopentane has a boiling point of 49° C. and is liquid at room temperature, but can be used as a disproportionation inhibitor in the present invention.

[0077] In the present invention, the disproportionation-inhibiting halogenated alkane used as the disproportionation inhibitor may be any one having 1 to 4 carbon atoms, except when all halogen atoms are fluorine. More specifically, halogenated methyl halides having 1 carbon atom (halogenated methyl halides), halogenated ethyl halides having 2 carbon atoms (halogenated ethyl halides), halogenated propyl halides having 3 carbon atoms (halogenated propyl halides), halogenated butyl halides having 4 carbon atoms (halogenated butyl halides), and the like can be cited.

[0078] As the disproportionation-inhibiting halogenated alkane, any one of methyl halide, ethyl halide, propyl halide or butyl halide can be used, but two or more of these disproportionation-inhibiting halogenated alkane can also be appropriately selected and used in combination. The selection of two or more mentioned here not only includes the case where two or more disproportionation-inhibiting halogenated alkane with different numbers of carbon atoms are selected (for example, a combination of any methyl halide and any methyl halide), but also includes the case where two or more disproportionation-inhibiting halogenated alkane with the same number of carbon atoms and different types of substituted halogen atoms are selected (for example, a combination of a first ethyl halide and a second ethyl halide different therefrom). In addition, the butyl halide can be a straight-chain structure or a branched structure (i.e., a structure having the same carbon skeleton as isobutane or 2-methylpropane).

[0079] Specifically, the disproportionation-suppressed alkyl halide may have the structure of the following formula (1).

[0080] C p H q X r ……(1)

[0081] However, X in formula (1) is a halogen atom selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), p is an arbitrary integer of 1 or 2, q is an integer greater than 0, and r is an integer greater than 1, the sum of q and r is 2p+2, and when r is greater than 2, X is the same or different type of halogen atom.

[0082] However, disproportionation-reduced halogenated alkanes represented by the above formula (1) are excluded, in which X consists only of F. This is because disproportionation-reduced halogenated alkanes in which X consists only of F are compounds that can be used together with other refrigerant components, but do not substantially function as disproportionation inhibitors.

[0083] In the disproportionation-suppressed halogenated alkane represented by formula (1), as described above, the halogen atom X can be at least one of F, Cl, Br, and I, but is preferably at least I. When the number of carbon atoms is 2 (p=2) and the number of halogen atoms is 2 or more (r≥2), the halogen atom X is preferably at least F and I.

[0084] When the disproportionation-inhibiting halogenated alkane represented by formula (1) contains Cl and / or Br, there is a tendency for the ozone depletion potential (ODP) to increase, so there is a possibility of being limited in terms of availability or operability. In addition, regardless of the type of halogen atom X, the disproportionation-inhibiting halogenated alkane represented by formula (1) also includes compounds with relatively large ozone depletion potential (ODP) or global warming potential (GWP).

[0085] However, in the present invention, even if the relative amount of the disproportionation-inhibiting halogenated hydrocarbon added to the mixed refrigerant is small, the disproportionation reaction of the halogenated hydrocarbon can be effectively inhibited, and the rapid progress of the disproportionation reaction can be alleviated. In addition, even when the disproportionation-inhibiting halogenated hydrocarbon and other disproportionation inhibitors such as disproportionation-inhibiting alkanes are used in combination, the total amount of the disproportionation inhibitor added is much less than the total amount of the mixed refrigerant. Therefore, even if the disproportionation-inhibiting halogenated hydrocarbon with a relatively large ODP or GWP is used, it will not have a significant impact on the environment.

[0086] The disproportionation-inhibiting halogenated alkane represented by formula (1) is not particularly limited, and specifically, examples thereof include: iodomethane (CH3I), diiodomethane (CH2I2), dibromomethane (CH2Br2), bromomethane (CH3Br), dichloromethane (CH2Cl2), chloroiodomethane (CH2ClI), dibromochloromethane (CHBr2Cl), tetraiodomethane (CI4), carbon tetrabromide (CBr4), chlorotribromomethane (CBrCl3), dibromodichloromethane (CBr2Cl2), tribromofluoromethane (CB4), chlorotribromomethane (CBrCl3), dibromodichloromethane (CBr2Cl2), tribromofluoromethane (CB4), chlorotribromomethane (CBrCl3), dibromodichloromethane (CBr2Cl2), tribromofluoromethane (CBr2Cl2), iodomethane (CH3I), dibromodichloromethane (CH3I), dibromofluoromethane (CH3Br), dibromomethane (CH3I), dibromochloromethane (CH3I), dibromofluoro ...chloromethane (CH3 r3F), fluorodiiodomethane (CHFI2), difluorodiiodomethane (CF2I2), dibromodifluoromethane (CBr2F2), trifluoroiodomethane (CF3I), difluoroiodomethane (CHF2I) and other halogenated ethanes; 1,1,1-trifluoro-2-iodoethane (CF3CH2I), monoiodoethane (CH3CH2I), monobromoethane (CH3CH2Br), 1,1,1-triiodoethane (CH3CI3), 1-bromide-2-iodotetrafluoroethane (CF2BrCF2I) and other halogenated ethanes, etc.

[0087] These disproportionation-inhibiting halogenated alkanes may be used alone or in combination of two or more thereof. Among them, in consideration of availability, ODP value, operability, etc., at least one selected from diiodomethane (CH2I2), difluoromethane (CF2I2), trifluoroiodomethane (CF3I), difluoroiodomethane (CHF2I), 1-bromide-2-iodotetrafluoroethane (CF2BrCF2I), and 1,1,1-trifluoro-2-iodoethane (CF3CH2I) can be particularly preferably used.

[0088] As described above, in the present invention, the mixed refrigerant is composed of at least fluoroolefins (fluoroalkanes) and propane (R290), and may contain refrigerants other than these as required, and may also contain a disproportionation inhibitor. In such a mixed refrigerant, the content (content ratio) of fluoroolefins and propane or the content (content ratio) of the disproportionation inhibitor is not particularly limited.

[0089] For example, when the total amount of the mixed refrigerant is 100% by mass, the content of the fluoroolefin may be 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more. In addition, when the total amount of the mixed refrigerant is 100% by mass, the content of the propane may be less than 50% by mass, 40% by mass or less, 30% by mass or less, or 20% by mass or less.

[0090] If the content of fluoroolefin is less than 50% by mass of the total amount of the mixed refrigerant, the content of fluoroolefin in the mixed refrigerant is too low, so that it contains a large amount of propane. Therefore, when the mixed refrigerant is viewed as a whole, the influence of propane, which is flammable, may become stronger. Therefore, in the mixed refrigerant, the advantage of achieving good operability while reducing GWP cannot be fully obtained.

[0091] In the present embodiment, a representative composition of fluoroolefin and propane is a composition in which the content of fluoroolefin is 80% by mass and the content of propane is 20% by mass relative to the total amount of fluoroolefin and propane (total mass 100% by mass). As the fluoroolefin in this case, as shown in the examples (Comparative Examples 1 and 2 and Example 1) described later, for example, 1,1,2-trifluoroethylene (HFO1123) is preferably used.

[0092] In addition, from the viewpoint of better achieving the effect of suppressing the disproportionation reaction, when the total mass of fluoroolefins and propane in the mixed refrigerant is used as the reference, the ratio of propane can be 20% by mass or more. For example, in the representative composition, the ratio of propane to fluoroolefins (HFO1123) is 25% by mass, that is, fluoroolefin: propane = 80:20. In this composition, the mixed refrigerant is composed only of fluoroolefins and propane. At this time, the ratio of propane to the total mass of the mixed refrigerant is 20% by mass / (80% by mass+20% by mass) = 20% by mass or more. Even if the mixed refrigerant contains components other than fluoroolefins and propane, the lower limit of the propane ratio is the same.

[0093] In the case where the mixed refrigerant contains a disproportionation inhibitor, if it is determined that the disproportionation inhibitor is a component constituting the mixed refrigerant, the content of the disproportionation inhibitor may be within a range of 0.1% by mass to 10% by mass relative to the total amount (100% by mass) of the mixed refrigerant. Although it also depends on the specific composition of the mixed refrigerant, if the disproportionation inhibitor is less than 0.1% by mass, the effect of suppressing the disproportionation reaction of fluoroolefins by adding the disproportionation inhibitor is sometimes not very ideal. On the other hand, if the content of the disproportionation inhibitor exceeds 10% by mass, the effect of suppressing the disproportionation reaction equivalent to the amount (content) of the disproportionation inhibitor added may not be obtained.

[0094] The upper limit of the content of the disproportionation inhibitor may be 10% by mass as described above, and may be 9.5% by mass or less, 9.0% by mass or less, 8.5% by mass or less, 5% by mass or less, or 3% by mass or less. In addition, the lower limit of the content of the disproportionation inhibitor may be 0.1% by mass as described above, and may be 0.2% by mass or more, 0.5% by mass or more, 0.8% by mass or more, 1.0% by mass or more, or 1.2% by mass or more.

[0095] In general, impurities contained in the refrigerant used in the air conditioner 10 are often 2 to 3% by mass or less. For example, commercially available HFO1123 is known to have a purity of about 97% by mass and contains less than 3% by mass of the remainder of synthetic raw materials or by-products as impurities.

[0096] Even when added to fluoroolefins at an impurity level (3% by mass or less), the disproportionation inhibitor can effectively inhibit the disproportionation reaction or slow down its progress. Therefore, the amount of the disproportionation inhibitor added cannot necessarily be determined, and the upper limit, lower limit, or amount of the disproportionation inhibitor added in the mixed refrigerant mentioned above are only representative and preferred examples.

[0097] [Working medium for refrigeration cycle]

[0098] In the air conditioner 10 of the present invention, the refrigeration cycle working medium is composed of the refrigeration oil 50 stored in the sealed compressor 20 and the mixed refrigerant. The refrigeration cycle working medium has a refrigerant solution viscosity of 2 to 4 mm under the operating conditions of a temperature range of 28°C to 60°C and an absolute pressure range of 2.2 MPa to 4.3 MPa. 2 For convenience of explanation, this operating condition is referred to as “operating condition 1”.

[0099] The temperature range and pressure range of the operating condition 1 are set from the viewpoint of achieving a good COP (Coefficient of Performance) in the air conditioner 10 .

[0100] Specifically, first, for the upper limits of the temperature range and the pressure range, physical property calculations based on the refrigerant thermal property database software Refprop10 (NIST, National Institute of Standards and Technology, USA) are used, HFO1123 is selected as a representative example of fluoroolefins, and a representative composition of the mixed refrigerant (composed of HFO1123 and R290), i.e., HFO1123:R290=80:20 (mass ratio), is adopted as the calculated values ​​(calculatable range) of the critical temperature and critical pressure in the mixed refrigerant.

[0101] In addition, the lower limits of the temperature range and the pressure range are obtained by theoretical calculation using the Refprop10 to obtain the cooling and heating performance based on the annual energy consumption efficiency. The annual energy consumption efficiency refers to APF (Annual Performance Factor), which indicates the cooling and heating capabilities of the air conditioner 10 per 1kW of power consumption when the air conditioner 10 is in operation according to the specified conditions clearly stated in JIS C9612.

[0102] In addition, the working medium for the refrigeration cycle has a refrigerant solution viscosity of 2 to 4 mm2 under the working conditions of a temperature range of 115°C or less and an absolute pressure range of 1.7 MPa to 4.6 MPa. 2 For the sake of convenience, this operating condition is referred to as "operating condition 2".

[0103] The upper temperature limit in the operating condition 2 is set according to the insulation grade of the insulating paper used in the stator 25 of the electric motor 23 constituting the hermetic compressor 20 .

[0104] In the stator 25, insulating paper is inserted between the magnetic wire and the electromagnetic steel sheet that generate a magnetic field by energizing. The insulation grade and temperature of the insulating paper are described in JIS C 4003 (refer to Table 1 "Heat resistance grade and temperature" described in "4. Heat resistance grade" of JIS C4003). For example, if the heat resistance grade of the insulating paper is Class E, its heat resistance temperature is 120°C.

[0105] Considering the time difference between the temperature of the working medium for the refrigeration cycle and the temperature detection of the stator 25 or heat dissipation, for example, 5K can be set as a safety margin. Therefore, when using E-type insulating paper, the upper limit of the temperature of the working medium for the refrigeration cycle is set to 115°C or less after deducting 5K as a safety margin. If the sealed compressor 20 is operated at a temperature exceeding this upper limit, the insulation between the magnetic wire and the electromagnetic steel sheet may be destroyed, and the possibility of discharge phenomenon at this time increases significantly.

[0106] However, it is selected according to the heat resistance grade of the insulation paper, for example, if it is class B, the heat resistance temperature is 130°C, and if it is class F, the heat resistance temperature is 155°C. Therefore, the temperature threshold (i.e., the upper temperature limit of working condition 2) is selected depending on the heat resistance grade of the insulation paper.

[0107] In addition, the safety margin of the working fluid temperature depends on the distance between the detection unit and the stator or the motor efficiency, so it is not limited to 5K, and can be set to a value between 0 and 20K. However, it is not limited by the heat resistance class setting, and since fluoroolefins are likely to undergo disproportionation reactions, the temperature of the refrigeration cycle working medium cannot exceed 150°C.

[0108] Here, the lower limit value of the temperature range in the operating condition 2 can also be set to 55° C. Therefore, the temperature range in the operating condition 2 can also be set within the range of 55° C. to 115° C.

[0109] The upper limit of the absolute pressure in the operating condition 2 can be set based on the critical pressures of fluoroolefins and propane. Specifically, the critical pressure of HFO1123, a representative fluoroolefin, is 4.54 MPa, and the critical pressure of propane is 4.25 MPa. Based on these critical pressures, the upper limit of the absolute pressure can be set to 4.6 MPa. On the other hand, the lower limit of the absolute pressure in the operating condition 2 can be set based on the evaporation pressure during cooling, which is about 1.7 MPa.

[0110] In the air conditioner 10 of the present invention, at least in the above-mentioned operating condition 1, the refrigerant solution viscosity of the working medium for the refrigeration cycle is 2 to 4 mm 2 / s, and in the above working condition 2, the refrigerant solution viscosity of the working medium of the refrigeration cycle is also in the range of 2 to 4 mm 2 / s range.

[0111] In the sealed compressor 20 included in the air conditioner 10, its sliding part is lubricated by the refrigeration oil 50, but the refrigerant must be able to dissolve in the refrigeration oil 50. Therefore, according to the conditions such as the temperature or pressure of the sealed compressor 20, the refrigerant dissolving viscosity of the refrigeration oil 50 changes. Generally, according to various conditions such as the specific type or composition of the refrigeration oil 50 (the type of base oil, the mixing ratio when using multiple base oils, the type or amount of additives, etc.), the compatibility (solubility) with the refrigerant is different. Therefore, by preferably selecting the viscosity of the specific refrigeration oil 50 used in the sealed compressor 20, and the compatibility of the refrigeration oil 50 with the specific refrigerant used in the refrigeration cycle, the refrigerant dissolving viscosity of the working medium for the refrigeration cycle can be adjusted (set) to a specified range.

[0112] Here, the refrigerant dissolution viscosity of the working medium for the refrigeration cycle is different from the dissolution viscosity measured quasi-statically in an environment where the conditions are strictly managed, such as in a test tube. The working medium for the refrigeration cycle and the refrigeration oil 50 stored in the closed container 21 are violently stirred. In addition, the temperature and pressure also change, so various conditions such as the time delay for the working medium for the refrigeration cycle to dissolve in the refrigeration oil 50 also need to be considered.

[0113] In the present invention, a viscosity sensor is used to measure the refrigerant solution viscosity of the working medium for the refrigeration cycle when the sealed compressor 20 is running. Specifically, for example, a viscosity sensor (product name: SPC501 small viscosity sensor) manufactured by Cambridge Viscosity is installed at the lower part of the sealed container 21. At this time, the sensor part of the viscosity sensor is arranged in a manner of contacting the refrigeration oil 50. Thus, the refrigerant solution viscosity when the sealed compressor 20 is running is measured in real time.

[0114] Figure 3 A is a graph showing an example of the relationship between the refrigeration cycle working medium and the COP of the air conditioner 10 when, for example, HFO1123 is selected as the fluoroolefin, a mixed refrigerant having the above-mentioned representative composition (HFO1123:R290=80:20 (mass ratio)) is used, and a polyol ester is used as the refrigeration oil 50.

[0115] like Figure 3 As shown in A, in the above working condition 1, if the refrigerant solution viscosity of the working medium of the refrigeration cycle is less than 2mm 2 / s, good sliding performance cannot be obtained in the sliding part of the sealed compressor 20, resulting in reduced air conditioning performance and failure to obtain a good COP. On the other hand, in the above-mentioned working condition 1, if the refrigerant solution viscosity of the working medium for the refrigeration cycle exceeds 4 mm 2 / s, the resistance when the working medium of the refrigeration cycle is stirred or the resistance when the closed compressor 20 is started increases, so the energy consumption of the refrigeration cycle also increases, and the air conditioning performance also decreases, and a good COP cannot be obtained.

[0116] On the contrary, in the above working condition 1, if the refrigerant solution viscosity of the working medium of the refrigeration cycle is 2 to 4 mm 2 / s, good sliding performance can be obtained in the sliding part of the hermetic compressor 20, and the increase in resistance during operation can also be suppressed. That is, it is possible to simultaneously suppress the energy consumption of the refrigeration cycle and achieve good refrigeration capacity (good air conditioning performance). As a result, in the air conditioner 10 using fluoroolefin as a refrigerant, a good COP can be achieved, and the disproportionation reaction of fluoroolefin can be well suppressed.

[0117] Furthermore, in the present invention, since the mixed refrigerant contains fluoroolefin and propane, if the refrigerant dissolution viscosity of the working medium for the refrigeration cycle is within the above range, the propane in the mixed refrigerant is easily dissolved in the refrigeration oil 50. This is because, as can be seen from the representative examples of the base oil, the main component of the refrigeration oil 50 has a molecular structure with hydrocarbon as the skeleton.

[0118] That is, the molecular structure of the refrigeration oil 50 is similar to that of R290 (n-propane) which is a hydrocarbon, but the molecules of refrigerants containing fluorine atoms such as fluoroolefins have low similarity to the molecular structure of the refrigeration oil 50. Therefore, R290 is more easily dissolved in the refrigeration oil 50 than fluoroolefins.

[0119] Here, when oxygen-containing oils such as polyol esters and polyvinyl ethers are used as the base oil of the refrigeration oil 50, the polarity of these oxygen-containing oils increases. This is because when the dipole moment, which is the vector sum of bond distances of each bond in a molecule, is large, the polarity of the molecule also increases.

[0120] In the conventional refrigeration cycle, HFC such as R32 (difluoromethane) is used as a refrigerant. Compared with such HFC, the dipole moment of fluoroolefin such as HFO1123 is relatively larger. Therefore, fluoroolefin is more easily dissolved in the refrigeration oil 50 than HFC.

[0121] For example, in the existing refrigeration cycle shown in Patent Document 1, HFC such as R32 or its mixed refrigerant (for example, R410A, a mixed refrigerant of R32 and R125 (pentafluoroethane)) is assumed to be used as the refrigerant. Therefore, even when a mixed refrigerant is used, there is no need to consider the solubility of the various refrigerants in the refrigeration oil 50.

[0122] In contrast, in the present invention, from the viewpoint of using fluoroolefin as the main component of the mixed refrigerant and improving the practicality of fluoroolefin as a refrigerant, propane is used as a secondary component. Fluoroolefin and propane have different solubility in refrigeration oil 50, and propane also has the effect of inhibiting the disproportionation reaction of fluoroolefin. Therefore, considering the difference in solubility, the working medium for the refrigeration cycle was studied and it was independently found that at least in the above-mentioned working condition 1, the refrigerant solution viscosity is adjusted to 2 to 4 mm. 2 / s range.

[0123] In particular, HFC is difficult to dissolve in the refrigeration oil 50 compared to fluoroolefins, so the refrigerant dissolution viscosity in the existing refrigeration cycle working medium cannot be directly applied to the mixed refrigerant with fluoroolefins as the main component. In addition, as mentioned above, fluoroolefins are prone to disproportionation reaction, so it is also necessary to consider how to well suppress the disproportionation reaction. In the present invention, by considering these factors, the above-mentioned working condition 1 and the above-mentioned working condition 2 are independently found, and the range of good refrigerant dissolution viscosity under these working conditions is independently found.

[0124] Therefore, according to the present invention, when the sealed compressor 20 is stopped, propane in the mixed refrigerant is easily dissolved in the refrigeration oil 50, so the apparent content of fluoroolefins contained in the mixed refrigerant in the sealed container 21 increases. On the other hand, during the operation of the sealed compressor 20, the propane dissolved in the refrigeration oil 50 is released from the refrigeration oil 50 as the temperature rises.

[0125] Therefore, propane, which is relatively easy to burn in the refrigerant constituting the mixed refrigerant, is easily dissolved in the refrigeration oil 50 when the hermetic compressor 20 stops. As a result, the apparent content of propane in the mixed refrigerant is reduced. Therefore, even if the mixed refrigerant leaks, the risk of combustion can be well reduced.

[0126] On the other hand, during the operation of the hermetic compressor 20, propane is released from the refrigeration oil 50, so that the apparent propane content of the mixed refrigerant increases. Since propane has the effect of suppressing the disproportionation reaction of fluoroolefins, the disproportionation reaction of fluoroolefins can be suppressed well.

[0127] In the present invention, particularly when the operating condition 2 is used as a reference, the compatibility of the mixed refrigerant with the refrigeration oil 50 can be adjusted to optimize the apparent content ratio of the mixed refrigerant in the sealed compressor 20 (ie, in the sealed container 21).

[0128] Specifically, when the temperature under the above-mentioned working condition 2 exceeds 115°C, it is sufficient to adjust the compatibility of the mixed refrigerant with respect to the refrigeration oil 50 so that the ratio of propane in the sealed compressor 20 (in the sealed container 21) to the total mass of the fluoroolefin and propane is 20% by mass or more. For the sake of convenience, this condition is referred to as "compatibility adjustment condition 1".

[0129] On the other hand, when the temperature under the above-mentioned working condition 2 is 115°C or less (preferably 55°C or more and 115°C or less), the compatibility of the mixed refrigerant with respect to the refrigeration oil 50 is adjusted so that the ratio of propane in the sealed compressor 20 (in the sealed container 21) to the total mass of the fluoroolefin and propane is less than 20% by mass. For the sake of convenience, this condition is referred to as "compatibility adjustment condition 2".

[0130] Under any of the above-mentioned compatibility adjustment conditions 1 and 2, the composition may be such that the ratio of propane to the total mass of the fluoroolefin and propane exceeds 20% by mass before the mixed refrigerant is sealed in the refrigeration cycle. When the mixed refrigerant is sealed in the refrigeration cycle, a part of the mixed refrigerant comes into contact with the refrigeration oil 50, and as described above, propane is easily dissolved in the refrigeration oil 50. Therefore, even in a state where the sealed compressor 20 is not operating, that is, in a state where the refrigeration cycle is not operating, propane gradually dissolves in the refrigeration oil 50. Therefore, it is sufficient to set the lower limit of the propane content and adjust it from the time before the mixed refrigerant is sealed in the refrigeration cycle.

[0131] Reference Figure 3 B explains the compatibility adjustment condition 1 or the compatibility adjustment condition 2 described above. Figure 3 B is a graph showing the relationship between the compatibility of fluoroolefin and propane constituting the mixed refrigerant with the refrigeration oil 50 and the temperature. Figure 3 In B, HFO1123 is shown as a representative fluoroolefin. The solid line curve represents the compatibility of HFO1123, and the dotted line curve represents R290.

[0132] As described above, R290 has a relatively greater compatibility with refrigeration oil 50 than HFO1123. Figure 3 As shown in B, the solid line curve representing the compatibility of HFO1123 is located below the dotted line curve representing the compatibility of R290.

[0133] Here, since the compatibility decreases when the temperature rises, the refrigerant dissolved in the refrigerating machine oil 50 is released from the refrigerating machine oil 50 as the temperature rises. Therefore, the amount of refrigerant circulating in the refrigerating cycle increases as the temperature rises. As described above, R290 has a relatively large compatibility compared to HFO1123, so the ratio of R290 in the mixed refrigerant circulating in the refrigerating cycle increases as the temperature rises.

[0134] In the present invention, the compatibility of the refrigeration oil 50 is adjusted so that when the temperature of the working medium for the refrigeration cycle reaches 115°C, the ratio of R290 in the mixed refrigerant circulating in the refrigeration cycle to the total mass of HFO1123 and R290 is at least 20% by mass. Figure 3 B shows the difference in compatibility of each refrigerant at different temperatures. By adjusting the compatibility in this way, when the temperature of the working medium for the refrigeration cycle reaches 115°C or above, that is, when the compatibility adjustment condition 1 is satisfied, the concentration (ratio) of R290 in the mixed refrigerant increases, so the disproportionation reaction of fluoroolefins can be better suppressed.

[0135] In addition, in the operating range including the temperature range of the working condition 1, that is, the compatibility adjustment condition 2, the ratio of R290 in the mixed refrigerant is at least less than 20% by mass. In this case, if the mixed refrigerant leaks from the sealed compressor 20 to the outside, the concentration (ratio) of R290 is relatively low, so the flammability of the leaked refrigerant can be well suppressed, reducing the risk of combustion.

[0136] [Example]

[0137] The present invention will be described in more detail with reference to the Examples and Comparative Examples, but the present invention is not limited thereto. A person skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention.

[0138] (Experimental system for disproportionation reaction)

[0139] For a sealed pressure-resistant container (stainless steel sealed container TVS-N2 "trade name" manufactured by Pressure Glass Industry Co., Ltd., internal volume 50 mL), a pressure sensor for measuring the internal pressure in the pressure-resistant container (VESVM10-2m "trade name" manufactured by VALCOM Co., Ltd.), a thermocouple for measuring the internal temperature in the pressure-resistant container (PL thermocouple ground PL-18-K-A4-T "trade name" manufactured by Conax Technologies), and a discharge device for generating discharge in the pressure-resistant container are installed.

[0140] A gas cylinder of 1,1,2-trifluoroethylene (HFO1123, manufactured by SynQuest Laboratories, sold by HYDRUS Chemical Co., Ltd., containing 5% limonene (liquid phase) as a stabilizer) as a fluoroolefin was connected in a pressure-adjustable manner. Two mantle heaters (Tube-type mantle heaters P-31 and P-51 manufactured by Tokyo Glass Instruments Co., Ltd. "both trade names") were installed to heat the entire pressure vessel, and a strip heater (flexible strip heater 1m, 200W manufactured by Tokyo Institute of Technology Co., Ltd.) was installed to heat the piping. Thus, an experimental system for disproportionation reaction was constructed.

[0141] (Comparative Example 1)

[0142] In the above experimental system, HFO1123 was introduced into the pressure vessel from a gas cylinder, and propane (R290) was added at 10% by mass of the total mass of the mixed refrigerant (i.e., HFO1123:R290=90:10 by mass ratio). The flammability class of the mixed refrigerant is A2, and the GWP is less than 10.

[0143] In order to induce the disproportionation reaction of HFO1123, a 300 V discharge was generated once using a discharge device at an internal temperature of about 27° C. (300 K), and the occurrence of the disproportionation reaction was confirmed.

[0144] (Comparative Example 2)

[0145] In the above experimental system, HFO1123 was introduced into the pressure vessel from a gas cylinder, and propane was added at 15% by mass of the total mass of the mixed refrigerant (i.e., HFO1123:R290=85:15 by mass ratio). The flammability class of the mixed refrigerant is A2, and the GWP is less than 10.

[0146] In order to induce the disproportionation reaction of HFO1123, 300 V discharge was generated five times by a discharge device at an internal temperature of about 27° C. (300 K), and the occurrence of the disproportionation reaction was confirmed.

[0147] (Example 1)

[0148] In the above experimental system, HFO1123 was introduced into the pressure vessel from a gas cylinder, and propane was added at 20% by mass of the total mass of the mixed refrigerant (i.e., HFO1123:R290=80:20 by mass ratio). The flammability class of the mixed refrigerant is A3, and the GWP is less than 10.

[0149] In order to induce the disproportionation reaction of HFO1123, a 300 V discharge was generated several times using a discharge device at an internal temperature of about 27° C. (300 K), but no disproportionation reaction was observed.

[0150] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining technical methods disclosed in different embodiments or multiple variations are also included in the technical scope of the present invention.

[0151] Based on the above description, many improvements and other embodiments of the present invention are obvious to those skilled in the art. Therefore, the above description should only be interpreted as an example and is provided to show the best mode for implementing the present invention to those skilled in the art. As long as it does not deviate from the spirit of the present invention, the details of its structure and / or function can be changed in substance.

[0152] Industrial Applicability

[0153] The present invention can be widely applied to the field of air conditioners using a mixed refrigerant containing a fluoroolefin such as 1,1,2-trifluoroethylene (HFO1123) and propane (R290).

[0154] Description of Reference Numerals

[0155] 10: Air conditioner

[0156] 11: Outdoor unit

[0157] 12: Indoor unit

[0158] 13: Piping between units

[0159] 13a: Pipe connection

[0160] 13b: Pipe connection

[0161] 14: Outdoor heat exchanger

[0162] 15: Outdoor fan

[0163] 16: Expansion valve

[0164] 17: Switching valve

[0165] 18: Indoor heat exchanger

[0166] 19: Indoor fan

[0167] 20: Hermetic compressor

[0168] 21: Sealed container

[0169] 22: Discharge pipe

[0170] 23: Electric Motor

[0171] 24: Rotor

[0172] 25: Stator

[0173] 26: Crankshaft

[0174] 27: Crankshaft eccentric part

[0175] 30: Compression mechanism

[0176] 30a: Inhalation chamber

[0177] 30b: Compression chamber

[0178] 30c: Suction hole

[0179] 31: Cylinder

[0180] 32: Rolling Piston

[0181] 33: Blade

[0182] 34: Upper bearing

[0183] 35: Lower bearing

[0184] 36: Inhalation of lining

[0185] 37: Suction outer tube

[0186] 40: Accumulator

[0187] 50: Refrigeration oil.

Claims

1. An air conditioner, characterized in that: A refrigeration cycle including a sealed compressor storing refrigeration oil therein, and using a mixed refrigerant containing fluoroolefin and propane as a refrigerant, The working medium for the refrigeration cycle composed of at least the refrigeration oil and the mixed refrigerant has a refrigerant solution viscosity of 2 to 4 mm under working conditions of a temperature range of 28°C to 60°C and an absolute pressure range of 2.2 MPa to 4.3 MPa. 2 / s range.

2. The air conditioner according to claim 1, characterized in that: The working medium for the refrigeration cycle has a refrigerant solution viscosity of 2 to 4 mm under working conditions of a temperature range of 115° C. or less and an absolute pressure range of 1.7 MPa to 4.6 MPa. 2 / s range.

3. The air conditioner according to claim 2, characterized in that: The temperature range under the working conditions is within the range of 55°C to 115°C.

4. The air conditioner according to claim 2, characterized in that: The compatibility of the mixed refrigerant with the refrigeration oil is adjusted so that when the temperature of the mixed refrigerant under the operating condition exceeds 115° C., the ratio of propane in the hermetic compressor to the total mass of fluoroolefin and propane is 20% by mass or more.

5. The air conditioner according to claim 2, characterized in that: The compatibility of the mixed refrigerant with the refrigeration oil is adjusted so that the ratio of propane in the hermetic compressor to the total mass of fluoroolefin and propane is less than 20 mass % when the temperature of the mixed refrigerant under the operating condition is 115° C. or less.

6. The air conditioner according to claim 4 or 5, characterized in that: The mixed refrigerant has a ratio of propane to the total mass of the fluoroolefin and the propane exceeding 20 mass % at the time before the mixed refrigerant is sealed in the refrigeration cycle.

7. The air conditioner according to claim 1, characterized in that: The fluoroolefin is at least one selected from 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, and monofluoroethylene.

8. The air conditioner according to claim 1, characterized in that: The mixed refrigerant further contains difluoromethane.

9. The air conditioner according to claim 1, characterized in that: The mixed refrigerant further contains a disproportionation inhibitor.

10. The air conditioner according to claim 9, characterized in that: The disproportionation inhibitor is a saturated hydrocarbon having 2 to 5 carbon atoms or a halogenated alkane having 1 or 2 carbon atoms, wherein the saturated hydrocarbon does not include propane, and the halogenated alkane does not include a fluoroalkane in which the halogen atom is replaced only by fluorine.

11. The air conditioner according to claim 1, wherein: The compression mechanism of the hermetic compressor is a rotary type.

12. The air conditioner according to claim 1, wherein: The hermetic compressor can be driven by a variable frequency drive.

Images