Patent Description:
In recent years, use of refrigerant with a low GWP (hereinafter referred to as low-GWP refrigerant) in air conditioners has been considered from the viewpoint of environmental protection. A dominant example of low-GWP refrigerant is a refrigerant mixture containing <NUM>,<NUM>-difluoroethylene.

However, the related art giving consideration from the aspect of increasing the efficiency of air conditioners using the foregoing refrigerant is rarely found. For example, in the case of applying the foregoing refrigerant to the air conditioner disclosed in <CIT>, there is an issue of how to achieve high efficiency.

Further examples of previously known air conditioners are derivable from <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, as well as <CIT>. However, none of these documents discloses the specific refrigerants defined in the appended independent claim <NUM>.

The above technical problem is solved by means of an air conditioner according to the appended indepenendet claim <NUM>. Distinct embodiments are derivable from the dependent claims.

An air conditioner according to a first aspect of the present invention includes a compressor that is configured to compress a refrigerant mixture containing at least <NUM>,<NUM>-difluoroethylene, a motor that is configured to drive the compressor, and a power conversion device. The power conversion device is connected between an alternating-current (AC) power source and the motor, has a switching element, and is configured to control the switching element such that an output of the motor becomes a target value.

In the air conditioner that uses a refrigerant mixture containing at least <NUM>,<NUM>-difluoroethylene, the motor rotation rate of the compressor can be changed in accordance with an air conditioning load, and thus a high annual performance factor (APF) can be achieved.

Further, in the air conditioner according to the first aspect of the present invention, the refrigerant comprises HFO-<NUM>(E), R32, and R1234yf, wherein.

The refrigerant comprises HFO-<NUM>(E), R32, and R1234yf in a total amount of <NUM> mass% or more based on the entire refrigerant.

In this air conditioner, the motor rotation rate of the compressor can be changed in accordance with an air conditioning load, and thus a high annual performance factor (AFP) can also be achieved when a refrigerant having a sufficiently low GWP, a refrigeration capacity (may also be referred to as a cooling capacity or a capacity) equal to those of R410A and classified with lower flammability (Class <NUM>) in the standard of The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is used.

An air conditioner according to a second aspect of the present invention is the air conditioner according to the first aspect, in which the power conversion device includes a rectifier circuit and a capacitor. The rectifier circuit is configured to rectify an AC voltage of the AC power source. The capacitor is connected in parallel to an output side of the rectifier circuit and is configured to smooth voltage variation caused by switching in the power conversion device.

In this air conditioner, an electrolytic capacitor is not required on the output side of the rectifier circuit, and thus an increase in the size and cost of the circuit is suppressed.

An air conditioner according to a third aspect of the present invention is the air conditioner according to the first aspect or the second aspect, in which the AC power source is a single-phase power source.

An air conditioner according to a fourth aspect of the present invention is the air conditioner according to the first aspect or the second aspect, in which the AC power source is a three-phase power source.

An air conditioner according to a fifth aspect of the present invention is the air conditioner according to the first aspect, in which the power conversion device is an indirect matrix converter including a converter and an inverter. The converter is configured to convert an AC voltage of the AC power source into a direct-current (DC) voltage. The inverter is configured to convert the DC voltage into an AC voltage and to supply the AC voltage to the motor.

This air conditioner is highly efficient and does not require an electrolytic capacitor on the output side of the rectifier circuit, and thus an increase in the size and cost of the circuit is suppressed.

An air conditioner according to a sixth aspect of the present invention is the air conditioner according to the first aspect, in which the power conversion device is a matrix converter that is configured to directly convert an AC voltage of the AC power source into an AC voltage having a predetermined frequency and to supply the AC voltage having the predetermined frequency to the motor.

An air conditioner according to a seventh aspect of the present invention is the air conditioner according to the first aspect, in which the compressor is any one of a scroll compressor, a rotary compressor, a turbo compressor, and a screw compressor.

An air conditioner according to an eighth aspect of the present invention is the air conditioner according to any one of the first aspect to the seventh aspect, in which the motor is a permanent magnet synchronous motor having a rotor including a permanent magnet.

In the present specification, the term "refrigerant" includes at least compounds that are specified in ISO <NUM> (International Organization for Standardization), and that are given a refrigerant number (ASHRAE number) representing the type of refrigerant with "R" at the beginning; and further includes refrigerants that have properties equivalent to those of such refrigerants, even though a refrigerant number is not yet given. Refrigerants are broadly divided into fluorocarbon compounds and non-fluorocarbon compounds in terms of the structure of the compounds. Fluorocarbon compounds include chlorofluorocarbons (CFC), hydro chlorofluorocarbons (HCFC), and hydrofluorocarbons (HFC). Non-fluorocarbon compounds include propane (R290), propylene (R1270), butane (R600), isobutane (R600a), carbon dioxide (R744), ammonia (R717), and the like.

In the present specification, the phrase "composition comprising a refrigerant" at least includes (<NUM>) a refrigerant itself (including a mixture of refrigerants), (<NUM>) a composition that further comprises other components and that can be mixed with at least a refrigeration oil to obtain a working fluid for a refrigerating machine, and (<NUM>) a working fluid for a refrigerating machine containing a refrigeration oil. In the present specification, of these three embodiments, the composition (<NUM>) is referred to as a "refrigerant composition" so as to distinguish it from a refrigerant itself (including a mixture of refrigerants). Further, the working fluid for a refrigerating machine (<NUM>) is referred to as a "refrigeration oil-containing working fluid" so as to distinguish it from the "refrigerant composition.

In the present specification, when the term "alternative" is used in a context in which the first refrigerant is replaced with the second refrigerant, the first type of "alternative" means that equipment designed for operation using the first refrigerant can be operated using the second refrigerant under optimum conditions, optionally with changes of only a few parts (at least one of the following: refrigeration oil, gasket, packing, expansion valve, dryer, and other parts) and equipment adjustment. In other words, this type of alternative means that the same equipment is operated with an alternative refrigerant. Embodiments of this type of "alternative" include "drop-in alternative," "nearly drop-in alternative," and "retrofit," in the order in which the extent of changes and adjustment necessary for replacing the first refrigerant with the second refrigerant is smaller.

The term "alternative" also includes a second type of "alternative," which means that equipment designed for operation using the second refrigerant is operated for the same use as the existing use with the first refrigerant by using the second refrigerant. This type of alternative means that the same use is achieved with an alternative refrigerant.

In the present specification, the term "refrigerating machine" refers to machines in general that draw heat from an object or space to make its temperature lower than the temperature of ambient air, and maintain a low temperature. In other words, refrigerating machines refer to conversion machines that gain energy from the outside to do work, and that perform energy conversion, in order to transfer heat from where the temperature is lower to where the temperature is higher.

In the present specification, a refrigerant having a "WCF lower flammability" means that the most flammable composition (worst case of formulation for flammability: WCF) has a burning velocity of <NUM>/s or less according to the US ANSI/ASHRAE Standard <NUM>-<NUM>. Further, in the present specification, a refrigerant having "ASHRAE lower flammability" means that the burning velocity of WCF is <NUM>/s or less, that the most flammable fraction composition (worst case of fractionation for flammability: WCFF), which is specified by performing a leakage test during storage, shipping, or use based on ANSI/ASHRAE <NUM>-<NUM> using WCF, has a burning velocity of <NUM>/s or less, and that flammability classification according to the US ANSI/ASHRAE Standard <NUM>-<NUM> is determined to classified as be "Class <NUM>.

In the present specification, a refrigerant having an "RCL of x% or more" means that the refrigerant has a refrigerant concentration limit (RCL), calculated in accordance with the US ANSI/ASHRAE Standard <NUM>-<NUM>, of x% or more. RCL refers to a concentration limit in the air in consideration of safety factors. RCL is an index for reducing the risk of acute toxicity, suffocation, and flammability in a closed space where humans are present. RCL is determined in accordance with the ASHRAE Standard. More specifically, RCL is the lowest concentration among the acute toxicity exposure limit (ATEL), the oxygen deprivation limit (ODL), and the flammable concentration limit (FCL), which are respectively calculated in accordance with sections <NUM>. <NUM>, <NUM>. <NUM>, and <NUM>. <NUM> of the ASHRAE Standard.

In the present specification, temperature glide refers to an absolute value of the difference between the initial temperature and the end temperature in the phase change process of a composition containing the refrigerant of the present disclosure in the heat exchanger of a refrigerant system.

Any one of various refrigerants such as refrigerant A, refrigerant B, refrigerant C, refrigerant D, and refrigerant E, details of these refrigerant are to be mentioned later, can be used as the refrigerant.

The refrigerant according to the present disclosure can be preferably used as a working fluid in a refrigerating machine.

The composition according to the present disclosure is suitable for use as an alternative refrigerant for HFC refrigerant such as R410A, R407C and R404 etc, or HCFC refrigerant such as R22 etc..

The refrigerant composition according to the present disclosure comprises at least the refrigerant according to the present disclosure, and can be used for the same use as the refrigerant according to the present disclosure. Moreover, the refrigerant composition according to the present disclosure can be further mixed with at least a refrigeration oil to thereby obtain a working fluid for a refrigerating machine.

The refrigerant composition according to the present disclosure further comprises at least one other component in addition to the refrigerant according to the present disclosure. The refrigerant composition according to the present disclosure may comprise at least one of the following other components, if necessary. As described above, when the refrigerant composition according to the present disclosure is used as a working fluid in a refrigerating machine, it is generally used as a mixture with at least a refrigeration oil. Therefore, it is preferable that the refrigerant composition according to the present disclosure does not substantially comprise a refrigeration oil. Specifically, in the refrigerant composition according to the present disclosure, the content of the refrigeration oil based on the entire refrigerant composition is preferably <NUM> to <NUM> mass%, and more preferably <NUM> to <NUM> mass%.

The refrigerant composition according to the present disclosure may contain a small amount of water. The water content of the refrigerant composition is preferably <NUM> mass% or less based on the entire refrigerant. A small amount of water contained in the refrigerant composition stabilizes double bonds in the molecules of unsaturated fluorocarbon compounds that can be present in the refrigerant, and makes it less likely that the unsaturated fluorocarbon compounds will be oxidized, thus increasing the stability of the refrigerant composition.

A tracer is added to the refrigerant composition according to the present disclosure at a detectable concentration such that when the refrigerant composition has been diluted, contaminated, or undergone other changes, the tracer can trace the changes.

The refrigerant composition according to the present disclosure may comprise a single tracer, or two or more tracers.

The tracer is not limited, and can be suitably selected from commonly used tracers. Preferably, a compound that cannot be an impurity inevitably mixed in the refrigerant of the present disclosure is selected as the tracer.

Examples of tracers include hydrofluorocarbons, hydro chlorofluorocarbons, chlorofluorocarbons, hydrochlorocarbons, fluorocarbons, deuterated hydrocarbons, deuterated hydrofluorocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodinated compounds, alcohols, aldehydes, ketones, and nitrous oxide (N<NUM>O). The tracer is particularly preferably a hydrofluorocarbon, a hydrochlorofluorocarbon, a chlorofluorocarbon, a fluorocarbon, a hydrochlorocarbon, a fluorocarbon, or a fluoroether.

The following compounds are preferable as the tracer.

The tracer compound may be present in the refrigerant composition at a total concentration of about <NUM> parts per million (ppm) to about <NUM> ppm. Preferably, the tracer compound is present in the refrigerant composition at a total concentration of about <NUM> ppm to about <NUM> ppm, and most preferably, the tracer compound is present at a total concentration of about <NUM> ppm to about <NUM> ppm.

The refrigerant composition according to the present disclosure may comprise a single ultraviolet fluorescent dye, or two or more ultraviolet fluorescent dyes.

The ultraviolet fluorescent dye is not limited, and can be suitably selected from commonly used ultraviolet fluorescent dyes.

Examples of ultraviolet fluorescent dyes include naphthalimide, coumarin, anthracene, phenanthrene, xanthene, thioxanthene, naphthoxanthene, fluorescein, and derivatives thereof. The ultraviolet fluorescent dye is particularly preferably either naphthalimide or coumarin, or both.

The refrigerant composition according to the present disclosure may comprise a single stabilizer, or two or more stabilizers.

The stabilizer is not limited, and can be suitably selected from commonly used stabilizers.

Examples of stabilizers include nitro compounds, ethers, and amines.

Examples of nitro compounds include aliphatic nitro compounds, such as nitromethane and nitroethane; and aromatic nitro compounds, such as nitro benzene and nitro styrene.

Examples of ethers include <NUM>,<NUM>-dioxane.

Examples of amines include <NUM>,<NUM>,<NUM>,<NUM>,<NUM>-pentafluoropropylamine and diphenylamine.

Examples of stabilizers also include butylhydroxyxylene and benzotriazole.

The content of the stabilizer is not limited. Generally, the content of the stabilizer is preferably <NUM> to <NUM> mass%, and more preferably <NUM> to <NUM> mass%, based on the entire refrigerant.

The refrigerant composition according to the present disclosure may comprise a single polymerization inhibitor, or two or more polymerization inhibitors.

The polymerization inhibitor is not limited, and can be suitably selected from commonly used polymerization inhibitors.

Examples of polymerization inhibitors include <NUM>-methoxy-<NUM>-naphthol, hydroquinone, hydroquinone methyl ether, dimethyl-t-butylphenol, <NUM>,<NUM>-di-tert-butyl-p-cresol, and benzotriazole.

The content of the polymerization inhibitor is not limited. Generally, the content of the polymerization inhibitor is preferably <NUM> to <NUM> mass%, and more preferably <NUM> to <NUM> mass%, based on the entire refrigerant.

The refrigeration oil-containing working fluid according to the present disclosure comprises at least the refrigerant or refrigerant composition according to the present disclosure and a refrigeration oil, for use as a working fluid in a refrigerating machine. Specifically, the refrigeration oil-containing working fluid according to the present disclosure is obtained by mixing a refrigeration oil used in a compressor of a refrigerating machine with the refrigerant or the refrigerant composition. The refrigeration oil-containing working fluid generally comprises <NUM> to <NUM> mass% of refrigeration oil.

The refrigeration oil is not limited, and can be suitably selected from commonly used refrigeration oils. In this case, refrigeration oils that are superior in the action of increasing the miscibility with the mixture and the stability of the mixture, for example, are suitably selected as necessary.

The base oil of the refrigeration oil is preferably, for example, at least one member selected from the group consisting of polyalkylene glycols (PAG), polyol esters (POE), and polyvinyl ethers (PVE).

The refrigeration oil may further contain additives in addition to the base oil. The additive may be at least one member selected from the group consisting of antioxidants, extreme-pressure agents, acid scavengers, oxygen scavengers, copper deactivators, rust inhibitors, oil agents, and antifoaming agents.

A refrigeration oil with a kinematic viscosity of <NUM> to <NUM> mm2/s (<NUM> to <NUM> cSt) at <NUM> is preferable from the standpoint of lubrication.

The refrigeration oil-containing working fluid according to the present disclosure may further optionally contain at least one additive. Examples of additives include compatibilizing agents described below.

The refrigeration oil-containing working fluid according to the present disclosure may comprise a single compatibilizing agent, or two or more compatibilizing agents.

The compatibilizing agent is not limited, and can be suitably selected from commonly used compatibilizing agents.

Examples of compatibilizing agents include polyoxyalkylene glycol ethers, amides, nitriles, ketones, chlorocarbons, esters, lactones, aryl ethers, fluoroethers, and <NUM>,<NUM>,<NUM>-trifluoroalkanes. The compatibilizing agent is particularly preferably a polyoxyalkylene glycol ether.

Hereinafter, the refrigerants A to E, which are the refrigerants used in the present embodiment, will be described in detail.

In addition, each description of the following refrigerant A, refrigerant B, refrigerant C, refrigerant D, and refrigerant E is each independent. The alphabet which shows a point or a line segment, the number of an Examples, and the number of a comparative examples are all independent of each other among the refrigerant A, the refrigerant B, the refrigerant C, the refrigerant D, and the refrigerant E. For example, the first embodiment of the refrigerant A and the first embodiment of the refrigerant B are different embodiment from each other.

The refrigerant A according to the present disclosure is a mixed refrigerant comprising trans-<NUM>,<NUM>-difluoroethylene (HFO-<NUM>(E)), trifluoroethylene (HFO-<NUM>), and <NUM>,<NUM>,<NUM>,<NUM>-tetrafluoro-<NUM>-propene (R1234yf).

The refrigerant A according to the present disclosure has various properties that are desirable as an R410A-alternative refrigerant, i.e., a refrigerating capacity and a coefficient of performance that are equivalent to those of R410A, and a sufficiently low GWP.

The refrigerant A according to the present disclosure is a composition comprising HFO-<NUM>(E) and R1234yf, and optionally further comprising HFO-<NUM>, and may further satisfy the following requirements. This refrigerant also has various properties desirable as an alternative refrigerant for R410A; i.e., it has a refrigerating capacity and a coefficient of performance that are equivalent to those of R410A, and a sufficiently low GWP.

Preferable refrigerant A is as follows:
When the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum in the refrigerant is respectively represented by x, y, and z, coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments AA', A'B, BD, DC', C'C, CO, and OA that connect the following <NUM> points:.

When the requirements above are satisfied, the refrigerant according to the present disclosure has a refrigerating capacity ratio of <NUM>% or more relative to that of R410A, and a COP of <NUM>% or more relative to that of R410A.

When the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf, based on their sum in the refrigerant A according to the present disclosure is respectively represented by x, y, and z, the refrigerant is preferably a refrigerant wherein coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within a figure surrounded by line segments GI, IA, AA', A'B, BD, DC', C'C, and CG that connect the following <NUM> points:.

When the requirements above are satisfied, the refrigerant A according to the present disclosure has a refrigerating capacity ratio of <NUM>% or more relative to that of R410A, and a COP of <NUM>% or more relative to that of R410A; furthermore, the refrigerant A has a WCF lower flammability according to the ASHRAE Standard (the WCF composition has a burning velocity of <NUM>/s or less).

When the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum in the refrigerant according to the present disclosure is respectively represented by x, y, and z, the refrigerant is preferably a refrigerant wherein coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments JP, PN, NK, KA', A'B, BD, DC', C'C, and CJ that connect the following <NUM> points:.

When the requirements above are satisfied, the refrigerant A according to the present disclosure has a refrigerating capacity ratio of <NUM>% or more relative to that of R410A, and a COP of <NUM>% or more relative to that of R410A; furthermore, the refrigerant exhibits a lower flammability (Class <NUM>) according to the ASHRAE Standard (the WCF composition and the WCFF composition have a burning velocity of <NUM>/s or less).

When the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum in the refrigerant according to the present disclosure is respectively represented by x, y, and z, the refrigerant is preferably a refrigerant wherein coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments JP, PL, LM, MA', A'B, BD, DC', C'C, and CJ that connect the following <NUM> points:.

When the requirements above are satisfied, the refrigerant according to the present disclosure has a refrigerating capacity ratio of <NUM>% or more relative to that of R410A, and a COP of <NUM>% or more relative to that of R410A; furthermore, the refrigerant has an RCL of <NUM>/m<NUM> or more.

When the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum in the refrigerant A according to the present disclosure is respectively represented by x, y, and z, the refrigerant is preferably a refrigerant wherein coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments PL, LM, MA', A'B, BF, FT, and TP that connect the following <NUM> points:.

The refrigerant A according to the present disclosure is preferably a refrigerant wherein when the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum in the refrigerant is respectively represented by x, y, and z, coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments PL, LQ, QR, and RP that connect the following <NUM> points:.

When the requirements above are satisfied, the refrigerant according to the present disclosure has a COP of <NUM>% or more relative to that of R410A, and an RCL of <NUM>/m<NUM> or more, furthermore, the refrigerant has a condensation temperature glide of <NUM> or less.

The refrigerant A according to the present disclosure is preferably a refrigerant wherein when the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum in the refrigerant is respectively represented by x, y, and z, coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments SM, MA', A'B, BF, FT, and TS that connect the following <NUM> points:.

When the requirements above are satisfied, the refrigerant according to the present disclosure has a refrigerating capacity ratio of <NUM>% or more relative to that of R410A, a COP of <NUM>% or more relative to that of R410A, and an RCL of <NUM>/m<NUM> or more furthermore, the refrigerant has a discharge pressure of <NUM>% or more relative to that of R410A.

The refrigerant A according to the present disclosure is preferably a refrigerant wherein when the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum in the refrigerant is respectively represented by x, y, and z, coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments Od, dg, gh, and hO that connect the following <NUM> points:.

When the requirements above are satisfied, the refrigerant according to the present disclosure has a refrigerating capacity ratio of <NUM>% or more relative to that of R410A, and a COP ratio of <NUM>% or more relative to that of R410A.

The refrigerant A according to the present disclosure is preferably a refrigerant wherein.

When the requirements above are satisfied, the refrigerant according to the present disclosure has a refrigerating capacity ratio of <NUM>% or more relative to that of R410A, and a COP ratio of <NUM>% or more relative to that of R410A; furthermore, the refrigerant has a lower flammability (Class <NUM>) according to the ASHRAE Standard.

The refrigerant according to the present disclosure may further comprise other additional refrigerants in addition to HFO-<NUM>(E), HFO-<NUM>, and R1234yf, as long as the above properties and effects are not impaired. In this respect, the refrigerant according to the present disclosure preferably comprises HFO-<NUM>(E), HFO-<NUM>, and R1234yf in a total amount of <NUM> mass% or more, more preferably <NUM> mass% or more, and still more preferably <NUM> mass% or more, based on the entire refrigerant.

The refrigerant according to the present disclosure may comprise HFO-<NUM>(E), HFO-<NUM>, and R1234yf in a total amount of <NUM> mass% or more, <NUM> mass% or more, or <NUM> mass% or more, based on the entire refrigerant.

Additional refrigerants are not particularly limited and can be widely selected. The mixed refrigerant may contain one additional refrigerant, or two or more additional refrigerants.

The present disclosure is described in more detail below with reference to Examples of refrigerant A. However, refrigerant A is not limited to the Examples.

The GWP of R1234yf and a composition consisting of a mixed refrigerant R410A (R32 = <NUM>%/R125 = <NUM>%) was evaluated based on the values stated in the Intergovernmental Panel on Climate Change (IPCC), fourth report. The GWP of HFO-<NUM>(E), which was not stated therein, was assumed to be <NUM> from HFO-1132a (GWP = <NUM> or less) and HFO-<NUM> (GWP = <NUM>, described in <CIT>). The refrigerating capacity of R410A and compositions each comprising a mixture of HFO-<NUM>(E), HFO-<NUM>, and R1234yf was determined by performing theoretical refrigeration cycle calculations for the mixed refrigerants using the National Institute of Science and Technology (NIST) and Reference Fluid Thermodynamic and Transport Properties Database (Refprop <NUM>) under the following conditions.

Further, the RCL of the mixture was calculated with the LFL of HFO-<NUM>(E) being <NUM> vol. %, the LFL of HFO-<NUM> being <NUM> vol. %, and the LFL of R1234yf being <NUM> vol. %, in accordance with the ASHRAE Standard <NUM>-<NUM>.

Tables <NUM> to <NUM> show these values together with the GWP of each mixed refrigerant.

These results indicate that under the condition that the mass% of HFO-<NUM>(E), HFO-<NUM>, and R1234yf based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments AA', A'B, BD, DC', C'C, CO, and OA that connect the following <NUM> points:.

The point on the line segment AA' was determined by obtaining an approximate curve connecting point A, Example <NUM>, and point A' by the least square method.

The point on the line segment A'B was determined by obtaining an approximate curve connecting point A', Example <NUM>, and point B by the least square method.

The point on the line segment DC' was determined by obtaining an approximate curve connecting point D, Example <NUM>, and point C' by the least square method.

The point on the line segment C'C was determined by obtaining an approximate curve connecting point C', Example <NUM>, and point C by the least square method.

Likewise, the results indicate that when coordinates (x,y,z) are within the range of a figure surrounded by line segments AA', A'B, BF, FT, TE, EO, and OA that connect the following <NUM> points:.

The point on the line segment FT was determined by obtaining an approximate curve connecting three points, i.e., points T, E', and F, by the least square method.

The point on the line segment TE was determined by obtaining an approximate curve connecting three points, i.e., points E, R, and T, by the least square method.

The results in Tables <NUM> to <NUM> clearly indicate that in a ternary composition diagram of the mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, and R1234yf in which the sum of these components is <NUM> mass%, a line segment connecting a point (<NUM>, <NUM>, <NUM>) and a point (<NUM>, <NUM>, <NUM>) is the base, the point (<NUM>, <NUM>, <NUM>) is on the left side, and the point (<NUM>, <NUM>, <NUM>) is on the right side, when coordinates (x,y,z) are on or below the line segment LM connecting point L (<NUM>, <NUM>, <NUM>) and point M (<NUM>, <NUM>, <NUM>), the refrigerant has an RCL of <NUM>/m<NUM> or more.

The results in Tables <NUM> to <NUM> clearly indicate that in a ternary composition diagram of the mixed refrigerant of HFO-<NUM>(E), HFO-<NUM> and R1234yf in which their sum is <NUM> mass%, a line segment connecting a point (<NUM>, <NUM>, <NUM>) and a point (<NUM>, <NUM>, <NUM>) is the base, the point (<NUM>, <NUM>, <NUM>) is on the left side, and the point (<NUM>, <NUM>, <NUM>) is on the right side, when coordinates (x,y,z) are on the line segment QR connecting point Q (<NUM>, <NUM>, <NUM>) and point R (<NUM>, <NUM>, <NUM>) or on the left side of the line segment, the refrigerant has a temperature glide of <NUM> or less.

The results in Tables <NUM> to <NUM> clearly indicate that in a ternary composition diagram of the mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, and R1234yf in which their sum is <NUM> mass%, a line segment connecting a point (<NUM>, <NUM>, <NUM>) and a point (<NUM>, <NUM>, <NUM>) is the base, the point (<NUM>, <NUM>, <NUM>) is on the left side, and the point (<NUM>, <NUM>, <NUM>) is on the right side, when coordinates (x,y,z) are on the line segment ST connecting point S (<NUM>, <NUM>, <NUM>) and point T (<NUM>, <NUM>, <NUM>) or on the right side of the line segment, the refrigerant has a discharge pressure of <NUM>% or less relative to that of 410A.

In these compositions, R1234yf contributes to reducing flammability, and suppressing deterioration of polymerization etc. Therefore, the composition preferably contains R1234yf.

Further, the burning velocity of these mixed refrigerants whose mixed formulations were adjusted to WCF concentrations was measured according to the ANSI/ASHRAE Standard <NUM>-<NUM>. Compositions having a burning velocity of <NUM>/s or less were determined to be classified as "Class <NUM> (lower flammability).

A burning velocity test was performed using the apparatus shown in <FIG> in the following manner. In <FIG>, reference numeral <NUM> refers to a sample cell, <NUM> refers to a high-speed camera, <NUM> refers to a xenon lamp, <NUM> refers to a collimating lens, <NUM> refers to a collimating lens, and <NUM> refers to a ring filter. First, the mixed refrigerants used had a purity of <NUM>% or more, and were degassed by repeating a cycle of freezing, pumping, and thawing until no traces of air were observed on the vacuum gauge. The burning velocity was measured by the closed method. The initial temperature was ambient temperature. Ignition was performed by generating an electric spark between the electrodes in the center of a sample cell. The duration of the discharge was <NUM> to <NUM>, and the ignition energy was typically about <NUM> to <NUM> J. The spread of the flame was visualized using schlieren photographs. A cylindrical container (inner diameter: <NUM>, length: <NUM>) equipped with two light transmission acrylic windows was used as the sample cell, and a xenon lamp was used as the light source. Schlieren images of the flame were recorded by a high-speed digital video camera at a frame rate of <NUM> fps and stored on a PC.

Each WCFF concentration was obtained by using the WCF concentration as the initial concentration and performing a leak simulation using NIST Standard Reference Database REFLEAK Version <NUM>.

Tables <NUM> and <NUM> show the results.

The results in Table <NUM> clearly indicate that when a mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, and R1234yf contains HFO-<NUM>(E) in a proportion of <NUM> mass% or less based on their sum, the refrigerant can be determined to have a WCF lower flammability.

The results in Tables <NUM> clearly indicate that in a ternary composition diagram of a mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, and R1234yf in which their sum is <NUM> mass%, and a line segment connecting a point (<NUM>, <NUM>, <NUM>) and a point (<NUM>, <NUM>, <NUM>) is the base,
when coordinates (x,y,z) are on or below the line segments JP, PN, and NK connecting the following <NUM> points:.

The point on the line segment PN was determined by obtaining an approximate curve connecting three points, i.e., points P, L, and N, by the least square method.

The point on the line segment NK was determined by obtaining an approximate curve connecting three points, i.e., points N, N', and K, by the least square method.

The refrigerant B according to the present disclosure is.

The refrigerant B according to the present disclosure has various properties that are desirable as an R410A-alternative refrigerant, i.e., (<NUM>) a coefficient of performance equivalent to that of R410A, (<NUM>) a refrigerating capacity equivalent to that of R410A, (<NUM>) a sufficiently low GWP, and (<NUM>) a lower flammability (Class <NUM>) according to the ASHRAE standard.

When the refrigerant B according to the present disclosure is a mixed refrigerant comprising <NUM> mass% or less of HFO-<NUM>(E), it has WCF lower flammability. When the refrigerant B according to the present disclosure is a composition comprising <NUM>% or less of HFO-<NUM>(E), it has WCF lower flammability and WCFF lower flammability, and is determined to be "Class <NUM>," which is a lower flammable refrigerant according to the ASHRAE standard, and which is further easier to handle.

When the refrigerant B according to the present disclosure comprises <NUM> mass% or more of HFO-<NUM>(E), it becomes superior with a coefficient of performance of <NUM>% or more relative to that of R410A, the polymerization reaction of HFO-<NUM>(E) and/or HFO-<NUM> is further suppressed, and the stability is further improved. When the refrigerant B according to the present disclosure comprises <NUM> mass% or more of HFO-<NUM>(E), it becomes superior with a coefficient of performance of <NUM>% or more relative to that of R410A, the polymerization reaction of HFO-<NUM>(E) and/or HFO-<NUM> is further suppressed, and the stability is further improved.

The refrigerant B according to the present disclosure may further comprise other additional refrigerants in addition to HFO-<NUM>(E) and HFO-<NUM>, as long as the above properties and effects are not impaired. In this respect, the refrigerant according to the present disclosure preferably comprises HFO-<NUM>(E) and HFO-<NUM> in a total amount of <NUM> mass% or more, and more preferably <NUM> mass% or more, based on the entire refrigerant.

Such additional refrigerants are not limited, and can be selected from a wide range of refrigerants. The mixed refrigerant may comprise a single additional refrigerant, or two or more additional refrigerants.

The present disclosure is described in more detail below with reference to Examples of refrigerant B. However, the refrigerant B is not limited to the Examples.

Mixed refrigerants were prepared by mixing HFO-<NUM>(E) and HFO-<NUM> at mass% based on their sum shown in Tables <NUM> and <NUM>.

The GWP of compositions each comprising a mixture of R410A (R32 = <NUM>%/R125 = <NUM>%) was evaluated based on the values stated in the Intergovernmental Panel on Climate Change (IPCC), fourth report. The GWP of HFO-<NUM>(E), which was not stated therein, was assumed to be <NUM> from HFO-1132a (GWP = <NUM> or less) and HFO-<NUM> (GWP = <NUM>, described in <CIT>). The refrigerating capacity of compositions each comprising R410A and a mixture of HFO-<NUM>(E) and HFO-<NUM> was determined by performing theoretical refrigeration cycle calculations for the mixed refrigerants using the National Institute of Science and Technology (NIST) and Reference Fluid Thermodynamic and Transport Properties Database (Refprop <NUM>) under the following conditions.

The composition of each mixture was defined as WCF. A leak simulation was performed using NIST Standard Reference Data Base Refleak Version <NUM> under the conditions of Equipment, Storage, Shipping, Leak, and Recharge according to the ASHRAE Standard <NUM>-<NUM>. The most flammable fraction was defined as WCFF.

Tables <NUM> and <NUM> show GWP, COP, and refrigerating capacity, which were calculated based on these results. The COP and refrigerating capacity are ratios relative to R410A.

The coefficient of performance (COP) was determined by the following formula.

For the flammability, the burning velocity was measured according to the ANSI/ASHRAE Standard <NUM>-<NUM>. Both WCF and WCFF having a burning velocity of <NUM>/s or less were determined to be "Class <NUM> (lower flammability).

A burning velocity test was performed using the apparatus shown in <FIG> in the following manner. First, the mixed refrigerants used had a purity of <NUM>% or more, and were degassed by repeating a cycle of freezing, pumping, and thawing until no traces of air were observed on the vacuum gauge. The burning velocity was measured by the closed method. The initial temperature was ambient temperature. Ignition was performed by generating an electric spark between the electrodes in the center of a sample cell. The duration of the discharge was <NUM> to <NUM>, and the ignition energy was typically about <NUM> to <NUM> J. The spread of the flame was visualized using schlieren photographs. A cylindrical container (inner diameter: <NUM>, length: <NUM>) equipped with two light transmission acrylic windows was used as the sample cell, and a xenon lamp was used as the light source. Schlieren images of the flame were recorded by a high-speed digital video camera at a frame rate of <NUM> fps and stored on a PC.

The compositions each comprising <NUM> mass% to <NUM> mass% of HFO-<NUM>(E) based on the entire composition are stable while having a low GWP (GWP = <NUM>), and they ensure WCF lower flammability. Further, surprisingly, they can ensure performance equivalent to that of R410A. Moreover, compositions each comprising <NUM> mass% to <NUM> mass% of HFO-<NUM>(E) based on the entire composition are stable while having a low GWP (GWP = <NUM>), and they ensure WCFF lower flammability. Further, surprisingly, they can ensure performance equivalent to that of R410A.

The refrigerant C according to the present disclosure is a composition comprising trans-<NUM>,<NUM>-difluoroethylene (HFO-<NUM>(E)), trifluoroethylene (HFO-<NUM>), <NUM>,<NUM>,<NUM>,<NUM>-tetrafluoro-<NUM>-propene (R1234yf), and difluoromethane (R32), and satisfies the following requirements. The refrigerant C according to the present disclosure has various properties that are desirable as an alternative refrigerant for R410A; i.e. it has a coefficient of performance and a refrigerating capacity that are equivalent to those of R410A, and a sufficiently low GWP.

Preferable refrigerant C is as follows:
When the mass% of HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 based on their sum is respectively represented by x, y, z, and a,.

The refrigerant C according to the present disclosure is preferably a refrigerant wherein.

When the refrigerant C according to the present disclosure further contains R32 in addition to HFO-<NUM> (E), HFO-<NUM>, and R1234yf, the refrigerant may be a refrigerant wherein when the mass% of HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 based on their sum is respectively represented by x, y, z, and a,.

The refrigerant C according to the present disclosure may further comprise other additional refrigerants in addition to HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 as long as the above properties and effects are not impaired. In this respect, the refrigerant according to the present disclosure preferably comprises HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 in a total amount of <NUM> mass% or more, more preferably <NUM> mass% or more, and still more preferably <NUM> mass% or more, based on the entire refrigerant.

The refrigerant C according to the present disclosure may comprise HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 in a total amount of <NUM> mass% or more, <NUM> mass% or more, or <NUM> mass% or more, based on the entire refrigerant.

The present disclosure is described in more detail below with reference to Examples of refrigerant C. However, the refrigerant C is not limited to the Examples.

Mixed refrigerants were prepared by mixing HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 at mass% based on their sum shown in Tables <NUM> to <NUM>.

For each of these mixed refrigerants, the COP ratio and the refrigerating capacity ratio relative to those of R410 were obtained. Calculation was conducted under the following conditions.

Tables <NUM> to <NUM> show the resulting values together with the GWP of each mixed refrigerant. The COP and refrigerating capacity are ratios relative to R410A.

The coefficient of performance (COP) was determined by the following formula.

The above results indicate that the refrigerating capacity ratio relative to R410A is <NUM>% or more in the following cases:
When the mass% of HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 based on their sum is respectively represented by x, y, z, and a, in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is (<NUM>-a) mass%, a straight line connecting a point (<NUM>, <NUM>-a, <NUM>) and a point (<NUM>, <NUM>, <NUM>-a) is the base, and the point (<NUM>, <NUM>-a, <NUM>) is on the left side, if <NUM><a≤<NUM>, coordinates (x,y,z) in the ternary composition diagram are on, or on the left side of, a straight line AB that connects point A (<NUM>. 0134a<NUM>-<NUM>. 9681a+<NUM>, <NUM>, -<NUM>. 0134a<NUM>+<NUM>. 9681a+<NUM>) and point B (<NUM>, <NUM>. 0144a<NUM>-<NUM>. 6377a+<NUM>, -<NUM>. 0144a<NUM>+<NUM>. 6377a+<NUM>);.

Actual points having a refrigerating capacity ratio of <NUM>% or more form a curved line that connects point A and point B in <FIG>, and that extends toward the 1234yf side. Accordingly, when coordinates are on, or on the left side of, the straight line AB, the refrigerating capacity ratio relative to R410A is <NUM>% or more.

Similarly, it was also found that in the ternary composition diagram, if <NUM><a≤<NUM>, when coordinates (x,y,z) are on, or on the left side of, a straight line D'C that connects point D' (<NUM>, <NUM>. 0224a<NUM>+<NUM>. 968a+<NUM>, -<NUM>. 0224a<NUM>-<NUM>. 968a+<NUM>) and point C (-<NUM>. 2304a<NUM>-<NUM>. 4062a+<NUM>, <NUM>. 2304a<NUM>-<NUM>. 5938a+<NUM>, <NUM>); or if <NUM><a≤<NUM>, when coordinates are in the entire region, the COP ratio relative to that of R410A is <NUM>% or more.

In <FIG>, the COP ratio of <NUM>% or more forms a curved line CD. In <FIG>, an approximate line formed by connecting three points: point C (<NUM>, <NUM>, <NUM>) and points (<NUM>, <NUM>, <NUM>) (<NUM>, <NUM>, <NUM>) where the COP ratio is <NUM>% when the concentration of R1234yf is <NUM> mass% and <NUM> mass was obtained, and a straight line that connects point C and point D' (<NUM>, <NUM>, <NUM>), which is the intersection of the approximate line and a point where the concentration of HFO-<NUM>(E) is <NUM> mass% was defined as a line segment D'C. In <FIG>, point D'(<NUM>, <NUM>, <NUM>) was similarly obtained from an approximate curve formed by connecting point C (<NUM>, <NUM>, <NUM>) and points (<NUM>, <NUM>, <NUM>) (<NUM>, <NUM>, <NUM>) where the COP ratio is <NUM>%, and a straight line that connects point C and point D' was defined as the straight line D'C.

The composition of each mixture was defined as WCF. A leak simulation was performed using NIST Standard Reference Database REFLEAK Version <NUM> under the conditions of Equipment, Storage, Shipping, Leak, and Recharge according to the ASHRAE Standard <NUM>-<NUM>. The most flammable fraction was defined as WCFF.

For the flammability, the burning velocity was measured according to the ANSI/ASHRAE Standard <NUM>-<NUM>. Both WCF and WCFF having a burning velocity of <NUM>/s or less were determined to be classified as "Class <NUM> (lower flammability).

The results are shown in Tables <NUM> to <NUM>.

The results in Tables <NUM> to <NUM> indicate that the refrigerant has a WCF lower flammability in the following cases:
When the mass% of HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 based on their sum in the mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 is respectively represented by x, y, z, and a, coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is (<NUM>-a) mass% and a straight line connecting a point (<NUM>, <NUM>-a, <NUM>) and a point (<NUM>, <NUM>, <NUM>-a) is the base, if <NUM><a≤<NUM>, coordinates (x,y,z) in the ternary composition diagram are on or below a straight line GI that connects point G (<NUM>. 026a<NUM>-<NUM>. 7478a+<NUM>, -<NUM>. 026a<NUM>+<NUM>. 7478a+<NUM>, <NUM>) and point I (<NUM>. 026a<NUM>-<NUM>. 7478a+<NUM>, <NUM>, -<NUM>. 026a<NUM>+<NUM>. 7478a+<NUM>);
if <NUM><a<_18. <NUM>, coordinates (x,y,z) in the ternary composition diagram are on or below a straight line GI that connects point G (<NUM>. 02a<NUM>-<NUM>. 6013a+<NUM>, -<NUM>. 02a<NUM>+<NUM>. 6013a+<NUM>, <NUM>) and point I (<NUM>. 02a<NUM>-<NUM>. 6013a+<NUM>, <NUM>, -<NUM>. 02a<NUM>+<NUM>. 6013a+<NUM>); if <NUM><a≤<NUM>, coordinates (x,y,z) in the ternary composition diagram are on or below a straight line GI that connects point G (<NUM>. 0135a<NUM>-<NUM>. 4068a+<NUM>, -<NUM>. 0135a<NUM>+<NUM>. 4068a+<NUM>, <NUM>) and point I (<NUM>. 0135a<NUM>-<NUM>. 4068a+<NUM>, <NUM>, -<NUM>. 0135a<NUM>+<NUM>. 4068a+<NUM>); if <NUM><a≤<NUM>, coordinates (x,y,z) in the ternary composition diagram are on or below a straight line GI that connects point G (<NUM>. 0111a<NUM>-<NUM>. 3152a+<NUM>, -<NUM>. 0111a<NUM>+<NUM>. 3152a+<NUM>, <NUM>) and point I (<NUM>. 0111a<NUM>-<NUM>. 3152a+<NUM>, <NUM>, -<NUM>. 0111a<NUM>+<NUM>. 3152a+<NUM>); and if <NUM><a≤<NUM>, coordinates (x,y,z) in the ternary composition diagram are on or below a straight line GI that connects point G (<NUM>. 0061a<NUM>-<NUM>. 9918a+<NUM>, -<NUM>. 0061a<NUM>-<NUM>. 0082a+<NUM>,<NUM>) and point I (<NUM>. 0061a<NUM>-<NUM>. 9918a+<NUM>, <NUM>, -<NUM>. 0061a<NUM>-<NUM>. 0082a+<NUM>).

Three points corresponding to point G (Table <NUM>) and point I (Table <NUM>) were individually obtained in each of the following five ranges by calculation, and their approximate expressions were obtained.

The results in Tables <NUM> to <NUM> indicate that the refrigerant is determined to have a WCFF lower flammability, and the flammability classification according to the ASHRAE Standard is "<NUM> (flammability)" in the following cases:
When the mass% of HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 based on their sum in the mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, R1234yf, and R32 is respectively represented by x, y, z, and a, in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R1234yf is (<NUM>-a) mass% and a straight line connecting a point (<NUM>, <NUM>-a, <NUM>) and a point (<NUM>, <NUM>, <NUM>-a) is the base, if <NUM><a≤<NUM>, coordinates (x,y,z) in the ternary composition diagram are on or below a straight line JK' that connects point J (<NUM>. 0049a<NUM>-<NUM>. 9645a+<NUM>, -<NUM>. 0049a<NUM>-<NUM>. 0355a+<NUM>, <NUM>) and point K'(<NUM>. 0514a<NUM>-<NUM>. 4353a+<NUM>, -<NUM>. 0323a<NUM>+<NUM>. 4122a+<NUM>, -<NUM>. 0191a<NUM>+<NUM>. 0231a+<NUM>); if <NUM><a≤<NUM>, coordinates are on a straight line JK' that connects point J (<NUM>. 0243a<NUM>-<NUM>. 4161a+<NUM>, -<NUM>. 0243a<NUM>+<NUM>. 4161a+<NUM>, <NUM>) and point K'(<NUM>. 0341a<NUM>-<NUM>. 1977a+<NUM>, -<NUM>. 0236a<NUM>+<NUM>. 34a+<NUM>, -<NUM>. 0105a<NUM>+<NUM>. 8577a+<NUM>); if <NUM><a≤<NUM>, coordinates are on or below a straight line JK' that connects point J (<NUM>. 0246a<NUM>-<NUM>. 4476a+<NUM>, -<NUM>. 0246a<NUM>+<NUM>. 4476a+<NUM>, <NUM>) and point K' (<NUM>. 0196a<NUM>-<NUM>. 7863a+<NUM>, -<NUM>. 0079a<NUM>-<NUM>. 1136a+<NUM>, -<NUM>. 0117a<NUM>+<NUM>. 8999a+<NUM>); if <NUM><a≤<NUM>, coordinates are on or below a straight line JK' that connects point J (<NUM>. 0183a<NUM>-<NUM>. 1399a+<NUM>, -<NUM>. 0183a<NUM>+<NUM>. 1399a+<NUM>, <NUM>) and point K' (-<NUM>. 0051a<NUM>+<NUM>. 0929a+<NUM>, <NUM>, <NUM>. 0051a<NUM>-<NUM>. 0929a+<NUM>); and if <NUM><a≤<NUM>, coordinates are on or below a straight line JK' that connects point J (-<NUM>. 0134a<NUM>+<NUM>. 0956a+<NUM>, <NUM>. 0134a<NUM>-<NUM>. 0956a+<NUM>, <NUM>) and point K'(-<NUM>. 892a+<NUM>, <NUM>, <NUM>. 892a+<NUM>).

Actual points having a WCFF lower flammability form a curved line that connects point J and point K' (on the straight line AB) in <FIG> and extends toward the HFO-<NUM>(E) side. Accordingly, when coordinates are on or below the straight line JK', WCFF lower flammability is achieved.

Three points corresponding to point J (Table <NUM>) and point K' (Table <NUM>) were individually obtained in each of the following five ranges by calculation, and their approximate expressions were obtained.

<FIG> show compositions whose R32 content a (mass%) is <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, and <NUM> mass%, respectively.

Points A, B, C, and D' were obtained in the following manner according to approximate calculation.

Point A is a point where the content of HFO-<NUM> is <NUM> mass%, and a refrigerating capacity ratio of <NUM>% relative to that of R410A is achieved. Three points corresponding to point A were obtained in each of the following five ranges by calculation, and their approximate expressions were obtained (Table <NUM>).

Point B is a point where the content of HFO-<NUM>(E) is <NUM> mass%, and a refrigerating capacity ratio of <NUM>% relative to that of R410A is achieved.

Three points corresponding to point B were obtained in each of the following five ranges by calculation, and their approximate expressions were obtained (Table <NUM>).

Point D' is a point where the content of HFO-<NUM>(E) is <NUM> mass%, and a COP ratio of <NUM>% relative to that of R410A is achieved.

Three points corresponding to point D' were obtained in each of the following by calculation, and their approximate expressions were obtained (Table <NUM>).

Point C is a point where the content of R1234yf is <NUM> mass%, and a COP ratio of <NUM>% relative to that of R410A is achieved.

Three points corresponding to point C were obtained in each of the following by calculation, and their approximate expressions were obtained (Table <NUM>).

The refrigerant D according to the present disclosure is a mixed refrigerant comprising trans-<NUM>,<NUM>-difluoroethylene (HFO-<NUM>(E)), difluoromethane (R32), and <NUM>,<NUM>,<NUM>,<NUM>-tetrafluoro-<NUM>-propene (R1234yf).

The refrigerant D according to the present disclosure has various properties that are desirable as an R410A-alternative refrigerant; i.e., a refrigerating capacity equivalent to that of R410A, a sufficiently low GWP, and a lower flammability (Class <NUM>) according to the ASHRAE standard.

The refrigerant D according to the present disclosure is preferably a refrigerant wherein.

The refrigerant D according to the present disclosure is preferably a refrigerant wherein when the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum is respectively represented by x, y, and z, coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments MM', M'N, NV, VG, and GM that connect the following <NUM> points:.

The refrigerant D according to the present invention is a refrigerant wherein.

The refrigerant D according to the present disclosure may further comprise other additional refrigerants in addition to HFO-<NUM>(E), R32, and R1234yf, as long as the above properties and effects are not impaired. In this respect, the refrigerant according to the present disclosure preferably comprises HFO-<NUM>(E), R32, and R1234yf in a total amount of <NUM> mass% or more, more preferably <NUM> mass% or more, and still more preferably <NUM> mass% or more based on the entire refrigerant.

The present disclosure is described in more detail below with reference to Examples of refrigerant D. However, the refrigerant D is not limited to the Examples.

The composition of each mixed refrigerant of HFO-<NUM>(E), R32, and R1234yf was defined as WCF. A leak simulation was performed using the NIST Standard Reference Database REFLEAK Version <NUM> under the conditions of Equipment, Storage, Shipping, Leak, and Recharge according to the ASHRAE Standard <NUM>-<NUM>. The most flammable fraction was defined as WCFF.

A burning velocity test was performed using the apparatus shown in <FIG> in the following manner. First, the mixed refrigerants used had a purity of <NUM>% or more, and were degassed by repeating a cycle of freezing, pumping, and thawing until no traces of air were observed on the vacuum gauge. The burning velocity was measured by the closed method. The initial temperature was ambient temperature. Ignition was performed by generating an electric spark between the electrodes in the center of a sample cell. The duration of the discharge was <NUM> to <NUM>, and the ignition energy was typically about <NUM> to <NUM> J. The spread of the flame was visualized using schlieren photographs. A cylindrical container (inner diameter: <NUM>, length: <NUM>) equipped with two light transmission acrylic windows was used as the sample cell, and a xenon lamp was used as the light source. Schlieren images of the flame were recorded by a high-speed digital video camera at a frame rate of <NUM> fps and stored on a PC. Tables <NUM> to <NUM> show the results.

The results indicate that under the condition that the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in the ternary composition diagram shown in <FIG> in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are on the line segment that connects point I, point J, point K, and point L, or below these line segments, the refrigerant has a WCF lower flammability.

The results also indicate that when coordinates (x,y,z) in the ternary composition diagram shown in <FIG> are on the line segments that connect point M, point M', point W, point J, point N, and point P, or below these line segments, the refrigerant has an ASHRAE lower flammability. Mixed refrigerants were prepared by mixing HFO-<NUM>(E), R32, and R1234yf in amounts (mass%) shown in Tables <NUM> to <NUM> based on the sum of HFO-<NUM>(E), R32, and R1234yf. The coefficient of performance (COP) ratio and the refrigerating capacity ratio relative to R410 of the mixed refrigerants shown in Tables <NUM> to <NUM> were determined. The conditions for calculation were as described below.

The results also indicate that under the condition that the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments IJ, JN, NE, and EI that connect the following <NUM> points:.

The results also indicate that under the condition that the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments MM', M'N, NV, VG, and GM that connect the following <NUM> points:.

The results also indicate that under the condition that the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments ON, NU, and UO that connect the following <NUM> points:.

The results also indicate that under the condition that the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments QR, RT, TL, LK, and KQ that connect the following <NUM> points:.

The results further indicate that under the condition that the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments PS, ST, and TP that connect the following <NUM> points:.

The refrigerant E according to the present disclosure is a mixed refrigerant comprising trans-<NUM>,<NUM>-difluoroethylene (HFO-<NUM>(E)), trifluoroethylene (HFO-<NUM>), and difluoromethane (R32).

The refrigerant E according to the present disclosure has various properties that are desirable as an R410A-alternative refrigerant, i.e., a coefficient of performance equivalent to that of R410A and a sufficiently low GWP.

The refrigerant E according to the present disclosure is preferably a refrigerant wherein.

The refrigerant E according to the present disclosure may further comprise other additional refrigerants in addition to HFO-<NUM>(E), HFO-<NUM>, and R32, as long as the above properties and effects are not impaired. In this respect, the refrigerant according to the present disclosure preferably comprises HFO-<NUM>(E), HFO-<NUM>, and R32 in a total amount of <NUM> mass% or more, more preferably <NUM> mass% or more, and even more preferably <NUM> mass% or more, based on the entire refrigerant.

The present disclosure is described in more detail below with reference to Examples of refrigerant E. However, the refrigerant E is not limited to the Examples.

Mixed refrigerants were prepared by mixing HFO-<NUM>(E), HFO-<NUM>, and R32 at mass% based on their sum shown in Tables <NUM> and <NUM>.

The composition of each mixture was defined as WCF. A leak simulation was performed using National Institute of Science and Technology (NIST) Standard Reference Data Base Refleak Version <NUM> under the conditions for equipment, storage, shipping, leak, and recharge according to the ASHRAE Standard <NUM>-<NUM>. The most flammable fraction was defined as WCFF.

For each mixed refrigerant, the burning velocity was measured according to the ANSI/ASHRAE Standard <NUM>-<NUM>. When the burning velocities of the WCF composition and the WCFF composition are <NUM>/s or less, the flammability of such a refrigerant is classified as Class <NUM> (lower flammability) in the ASHRAE flammability classification.

The results in Table <NUM> indicate that in a ternary composition diagram of a mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, and R32 in which their sum is <NUM> mass%, a line segment connecting a point (<NUM>, <NUM>, <NUM>) and a point (<NUM>, <NUM>, <NUM>) is the base, the point (<NUM>, <NUM>, <NUM>) is on the left side, and the point (<NUM>, <NUM>, <NUM>) is on the right side, when coordinates (x,y,z) are on or below line segments IK and KL that connect the following <NUM> points:.

For the points on the line segment IK, an approximate curve (x=<NUM>. 025z<NUM>-<NUM>. 7429z+<NUM>) was obtained from three points, i.e., I (<NUM>, <NUM>, <NUM>), J (<NUM>, <NUM>, <NUM>), and K (<NUM>, <NUM>, <NUM>) by using the least-square method to determine coordinates
(x=<NUM>. 025z<NUM>-<NUM>. 7429z+<NUM>, y=<NUM>-z-x=-<NUM>. 00922z<NUM>+<NUM>. 2114z+<NUM>, z).

Likewise, for the points on the line segment KL, an approximate curve was determined from three points, i.e., K (<NUM>, <NUM>, <NUM>), Example <NUM> (<NUM>, <NUM>, <NUM>), and L (<NUM>, <NUM>, <NUM>) by using the least-square method to determine coordinates.

The results in Table <NUM> indicate that in a ternary composition diagram of a mixed refrigerant of HFO-<NUM>(E), HFO-<NUM>, and R32 in which their sum is <NUM> mass%, a line segment connecting a point (<NUM>, <NUM>, <NUM>) and a point (<NUM>, <NUM>, <NUM>) is the base, the point (<NUM>, <NUM>, <NUM>) is on the left side, and the point (<NUM>, <NUM>, <NUM>) is on the right side, when coordinates (x,y,z) are on or below line segments MP and PQ that connect the following <NUM> points:.

In the above, the line segment MP is represented by coordinates (<NUM>. 0083z<NUM>-<NUM>. 984z+<NUM>, -<NUM>. 0083z<NUM>-<NUM>. 016z+<NUM>, z), and the line segment PQ is represented by coordinates
(<NUM>. 0135z<NUM>-<NUM>. 9181z+<NUM>, -<NUM>. 0135z<NUM>-<NUM>. 0819z+<NUM>, z).

For the points on the line segment MP, an approximate curve was obtained from three points, i.e., points M, N, and P, by using the least-square method to determine coordinates. For the points on the line segment PQ, an approximate curve was obtained from three points, i.e., points P, U, and Q, by using the least-square method to determine coordinates.

The COP ratio and the refrigerating capacity (which may be referred to as "cooling capacity" or "capacity") ratio relative to those of R410 of the mixed refrigerants were determined. The conditions for calculation were as described below.

The above results indicate that under the condition that the mass% of HFO-<NUM>(E), HFO-<NUM>, and R32 based on their sum is respectively represented by x, y, and z, when coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), HFO-<NUM>, and R32 is <NUM> mass%, a line segment connecting a point (<NUM>, <NUM>, <NUM>) and a point (<NUM>, <NUM>, <NUM>) is the base, and the point (<NUM>, <NUM>, <NUM>) is on the left side are within the range of a figure surrounded by line segments that connect the following <NUM> points:.

The results also indicate that when coordinates (x,y,z) are within the range of a figure surrounded by line segments that connect the following <NUM> points:.

The results also indicate that when coordinates (x,y,z) are on the left side of line segments that connect the following <NUM> points:.

In the above, the line segment CU is represented by coordinates (-<NUM>. 0538z<NUM>+<NUM>. 7888z+<NUM>, <NUM>. 0538z<NUM>-<NUM>. 7888z+<NUM>, z), and the line segment UD is represented by coordinates
(-<NUM>. 4962z<NUM>+<NUM><NUM>. 71z-<NUM>, <NUM>. 4962z<NUM>-<NUM>. 71z+<NUM>, z).

The points on the line segment CU are determined from three points, i.e., point C, Comparative Example <NUM>, and point U, by using the least-square method.

The points on the line segment UD are determined from three points, i.e., point U, Example <NUM>, and point D, by using the least-square method.

In the above, the line segment ET is represented by coordinates (-<NUM>. 0547z<NUM>-<NUM>. 5327z+<NUM>, <NUM>. 0547z<NUM>-<NUM>. 4673z+<NUM>, z), and the line segment TF is represented by coordinates
(-<NUM>. 0982z<NUM>+<NUM>. 9622z+<NUM>, <NUM>. 0982z<NUM>-<NUM>. 9622z+<NUM>, z).

The points on the line segment ET are determined from three points, i.e., point E, Example <NUM>, and point T, by using the least-square method.

The points on the line segment TF are determined from three points, i.e., points T, S, and F, by using the least-square method.

In the above, the line segment GR is represented by coordinates (-<NUM>. 0491z<NUM>-<NUM>. 1544z+<NUM>, <NUM>. 0491z<NUM>+<NUM>. 1544z+<NUM>, z), and the line segment RH is represented by coordinates
(-<NUM>. 3123z<NUM>+<NUM>. 234z+<NUM>, <NUM>. 3123z<NUM>-<NUM>. 234z+<NUM>, z).

The points on the line segment GR are determined from three points, i.e., point G, Example <NUM>, and point R, by using the least-square method.

The points on the line segment RH are determined from three points, i.e., point R, Example <NUM>, and point H, by using the least-square method.

In contrast, as shown in, for example, Comparative Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, when R32 is not contained, the concentrations of HFO-<NUM>(E) and HFO-<NUM>, which have a double bond, become relatively high; this undesirably leads to deterioration, such as decomposition, or polymerization in the refrigerant compound.

<FIG> is a configuration diagram of an air conditioner <NUM> according to a first embodiment of the present disclosure. In <FIG>, the air conditioner <NUM> is constituted by a utilization unit <NUM> and a heat source unit <NUM>.

The air conditioner <NUM> has a refrigerant circuit <NUM> in which a compressor <NUM>, a four-way switching valve <NUM>, a heat-source-side heat exchanger <NUM>, an expansion valve <NUM> serving as a decompression mechanism, and a utilization-side heat exchanger <NUM> are connected in a loop shape by refrigerant pipes.

In this embodiment, the refrigerant circuit <NUM> is filled with refrigerant for performing a vapor compression refrigeration cycle. The refrigerant is a refrigerant mixture containing <NUM>,<NUM>-difluoroethylene, and any one of the above-described refrigerant A to refrigerant E can be used. The refrigerant circuit <NUM> is filled with refrigerating machine oil together with the refrigerant mixture.

In the refrigerant circuit <NUM>, the utilization-side heat exchanger <NUM> belongs to the utilization unit <NUM>. In addition, a utilization-side fan <NUM> is mounted in the utilization unit <NUM>. The utilization-side fan <NUM> generates an air flow to the utilization-side heat exchanger <NUM>.

A utilization-side communicator <NUM> and a utilization-side microcomputer <NUM> are mounted in the utilization unit <NUM>. The utilization-side communicator <NUM> is connected to the utilization-side microcomputer <NUM>.

The utilization-side communicator <NUM> is used by the utilization unit <NUM> to communicate with the heat source unit <NUM>. The utilization-side microcomputer <NUM> is supplied with a control voltage even during a standby state in which the air conditioner <NUM> is not operating. Thus, the utilization-side microcomputer <NUM> is constantly activated.

In the refrigerant circuit <NUM>, the compressor <NUM>, the four-way switching valve <NUM>, the heat-source-side heat exchanger <NUM>, and the expansion valve <NUM> belong to the heat source unit <NUM>. In addition, a heat-source-side fan <NUM> is mounted in the heat source unit <NUM>. The heat-source-side fan <NUM> generates an air flow to the heat-source-side heat exchanger <NUM>.

In addition, a power conversion device <NUM>, a heat-source-side communicator <NUM>, and a heat-source-side microcomputer <NUM> are mounted in the heat source unit <NUM>. The power conversion device <NUM> and the heat-source-side communicator <NUM> are connected to the heat-source-side microcomputer <NUM>.

The power conversion device <NUM> is a circuit for driving a motor <NUM> of the compressor <NUM>. The heat-source-side communicator <NUM> is used by the heat source unit <NUM> to communicate with the utilization unit <NUM>. The heat-source-side microcomputer <NUM> controls the motor <NUM> of the compressor <NUM> via the power conversion device <NUM> and also controls other devices in the heat source unit <NUM> (for example, the heat-source-side fan <NUM>).

<FIG> is a circuit block diagram of the power conversion device <NUM>. In <FIG>, the motor <NUM> of the compressor <NUM> is a three-phase brushless DC motor and includes a stator <NUM> and a rotor <NUM>. The stator <NUM> includes star-connected phase windings Lu, Lv, and Lw of a U-phase, a V-phase, and a W-phase. One ends of the phase windings Lu, Lv, and Lw are respectively connected to phase winding terminals TU, TV, and TW of wiring lines of the U-phase, the V-phase, and the W-phase extending from an inverter <NUM>. The other ends of the phase windings Lu, Lv, and Lw are connected to each other at a terminal TN. These phase windings Lu, Lv, and Lw each generate an induced voltage in accordance with the rotation speed and position of the rotor <NUM> when the rotor <NUM> rotates.

The rotor <NUM> includes a permanent magnet with a plurality of poles, the N-pole and the S-pole, and rotates about a rotation axis with respect to the stator <NUM>.

The power conversion device <NUM> is mounted in the heat source unit <NUM>, as illustrated in <FIG>. The power conversion device <NUM> is constituted by a power source circuit <NUM>, the inverter <NUM>, a gate driving circuit <NUM>, and the heat-source-side microcomputer <NUM>, as illustrated in <FIG>. The power source circuit <NUM> is constituted by a rectifier circuit <NUM> and a capacitor <NUM>.

The rectifier circuit <NUM> has a bridge structure made up of four diodes D1a, D1b, D2a, and D2b. Specifically, the diodes D1a and D1b are connected in series to each other, and the diodes D2a and D2b are connected in series to each other. The cathode terminals of the diodes D1a and D2a are connected to a plus-side terminal of the capacitor <NUM> and function as a positive-side output terminal of the rectifier circuit <NUM>. The anode terminals of the diodes D1b and D2b are connected to a minus-side terminal of the capacitor <NUM> and function as a negative-side output terminal of the rectifier circuit <NUM>.

A node between the diode D1a and the diode D1b is connected to one pole of an alternating-current (AC) power source <NUM>. A node between the diode D2a and the diode D2b is connected to the other pole of the AC power source <NUM>. The rectifier circuit <NUM> rectifies an AC voltage output from the AC power source <NUM> to generate a direct-current (DC) voltage, and supplies the DC voltage to the capacitor <NUM>.

The capacitor <NUM> has one end connected to the positive-side output terminal of the rectifier circuit <NUM> and has the other end connected to the negative-side output terminal of the rectifier circuit <NUM>. The capacitor <NUM> is a small-capacitance capacitor that does not have a large capacitance for smoothing a voltage rectified by the rectifier circuit <NUM>. Hereinafter, a voltage between the terminals of the capacitor <NUM> will be referred to as a DC bus voltage Vdc for the convenience of description.

The DC bus voltage Vdc is applied to the inverter <NUM> connected to the output side of the capacitor <NUM>. In other words, the rectifier circuit <NUM> and the capacitor <NUM> constitute the power source circuit <NUM> for the inverter <NUM>.

The capacitor <NUM> smooths voltage variation caused by switching in the inverter <NUM>. In this embodiment, a film capacitor is adopted as the capacitor <NUM>.

A voltage detector <NUM> is connected to the output side of the capacitor <NUM> and is for detecting the value of a voltage across the capacitor <NUM>, that is, the DC bus voltage Vdc. The voltage detector <NUM> is configured such that, for example, two resistors connected in series to each other are connected in parallel to the capacitor <NUM> and the DC bus voltage Vdc is divided. A voltage value at a node between the two resistors is input to the heat-source-side microcomputer <NUM>.

A current detector <NUM> is connected between the capacitor <NUM> and the inverter <NUM> and to the negative-side output terminal side of the capacitor <NUM>. The current detector <NUM> detects a motor current that flows through the motor <NUM> after the motor <NUM> is activated, as a total value of currents of the three phases.

The current detector <NUM> may be constituted by, for example, an amplifier circuit including a shunt resistor and an operational amplifier that amplifies a voltage across the shunt resistor. The motor current detected by the current detector <NUM> is input to the heat-source-side microcomputer <NUM>.

In the inverter <NUM>, three pairs of upper and lower arms respectively corresponding to the phase windings Lu, Lv, and Lw of the U-phase, the V-phase, and the W-phase of the motor <NUM> are connected in parallel to each other and connected to the output side of the capacitor <NUM>.

In <FIG>, the inverter <NUM> includes a plurality of insulated gate bipolar transistors (IGBTs, hereinafter simply referred to as transistors) Q3a, Q3b, Q4a, Q4b, Q5a, and Q5b, and a plurality of free wheeling diodes D3a, D3b, D4a, D4b, D5a, and D5b.

The transistors Q3a and Q3b are connected in series to each other, the transistors Q4a and Q4b are connected in series to each other, and the transistors Q5a and Q5b are connected in series to each other, to constitute respective upper and lower arms and to form nodes NU, NV, and NW, from which output lines extend toward the phase windings Lu, Lv, and Lw of the corresponding phases.

The diodes D3a to D5b are connected in parallel to the respective transistors Q3a to Q5b such that the collector terminal of the transistor is connected to the cathode terminal of the diode and that the emitter terminal of the transistor is connected to the anode terminal of the diode. The transistor and the diode connected in parallel to each other constitute a switching element.

The inverter <NUM> generates driving voltages SU, SV, and SW for driving the motor <NUM> in response to ON and OFF of the transistors Q3a to Q5b at the timing when the DC bus voltage Vdc is applied from the capacitor <NUM> and when an instruction is provided from the gate driving circuit <NUM>. The driving voltages SU, SV, and SW are respectively output from the node NU between the transistors Q3a and Q3b, the node NV between the transistors Q4a and Q4b, and the node NW between the transistors Q5a and Q5b to the phase windings Lu, Lv, and Lw of the motor <NUM>.

The gate driving circuit <NUM> changes the ON and OFF states of the transistors Q3a to Q5b of the inverter <NUM> on the basis of instruction voltages from the heat-source-side microcomputer <NUM>. Specifically, the gate driving circuit <NUM> generates gate control voltages Gu, Gx, Gv, Gy, Gw, and Gz to be applied to the gates of the respective transistors Q3a to Q5b so that the pulsed driving voltages SU, SV, and SW having a duty determined by the heat-source-side microcomputer <NUM> are output from the inverter <NUM> to the motor <NUM>. The generated gate control voltages Gu, Gx, Gv, Gy, Gw, and Gz are applied to the gate terminals of the respective transistors Q3a to Q5b.

The heat-source-side microcomputer <NUM> is connected to the voltage detector <NUM>, the current detector <NUM>, and the gate driving circuit <NUM>. In this embodiment, the heat-source-side microcomputer <NUM> causes the motor <NUM> to be driven by using a rotor position sensorless method. The driving method is not limited to the rotor position sensorless method, and a sensor method may be used.

The rotor position sensorless method is a method for performing driving by estimating the position and rotation rate of the rotor, performing PI control on the rotation rate, performing PI control on a motor current, and the like, by using various parameters indicating the characteristics of the motor <NUM>, a detection result of the voltage detector <NUM> after the motor <NUM> is activated, a detection result of the current detector <NUM>, and a predetermined formula model about control of the motor <NUM>, and the like. The various parameters indicating the characteristics of the motor <NUM> include a winding resistance, an inductance component, an induced voltage, and the number of poles of the motor <NUM> that is used. For details of rotor position sensorless control, see patent literatures (for example, <CIT>).

<FIG> is a circuit block diagram of a power conversion device <NUM> according to a modification example of the first embodiment. In <FIG>, this modification example is different from the first embodiment in that a rectifier circuit <NUM> for three phases is adopted instead of the rectifier circuit <NUM> for a single phase, to support a three-phase AC power source <NUM> instead of the single-phase AC power source <NUM>.

The rectifier circuit <NUM> has a bridge structure made up of six diodes D0a, D0b, D1a, D1b, D2a, and D2b. Specifically, the diodes D0a and D0b are connected in series to each other, the diodes D1a and D1b are connected in series to each other, and the diodes D2a and D2b are connected in series to each other.

The cathode terminals of the diodes D0a, D1a, and D2a are connected to the plus-side terminal of the capacitor <NUM> and function as a positive-side output terminal of the rectifier circuit <NUM>. The anode terminals of the diodes D0b, D1b, and D2b are connected to the minus-side terminal of the capacitor <NUM> and function as a negative-side output terminal of the rectifier circuit <NUM>.

A node between the diode D0a and the diode D0b is connected to an R-phase output side of the AC power source <NUM>. A node between the diode D1a and the diode D1b is connected to an S-phase output side of the AC power source <NUM>. A node between the diode D2a and the diode D2b is connected to a T-phase output side of the AC power source <NUM>. The rectifier circuit <NUM> rectifies an AC voltage output from the AC power source <NUM> to generate a DC voltage, and supplies the DC voltage to the capacitor <NUM>.

Other than that, the configuration is similar to that of the above-described embodiment, and thus the description thereof is omitted.

<FIG> is a circuit block diagram of a power conversion device 30B mounted in an air conditioner according to a second embodiment of the present disclosure.

In <FIG>, the power conversion device 30B is an indirect matrix converter. The difference from the power conversion device <NUM> according to the first embodiment in <FIG> is that a converter <NUM> is adopted instead of the rectifier circuit <NUM> and that a gate driving circuit <NUM> and a reactor <NUM> are newly added. Other than that, the configuration is similar to that of the first embodiment.

Here, a description will be given of the converter <NUM>, the gate driving circuit <NUM>, and the reactor <NUM>, and a description of the other components is omitted.

In <FIG>, the converter <NUM> includes a plurality of insulated gate bipolar transistors (IGBTs, hereinafter simply referred to as transistors) Q1a, Q1b, Q2a, and Q2b, and a plurality of diodes D1a, D1b, D2a, and D2b.

The transistors Q1a and Q1b are connected in series to each other to constitute upper and lower arms, and a node formed accordingly is connected to one pole of the AC power source <NUM>. The transistors Q2a and Q2b are connected in series to each other to constitute upper and lower arms, and a node formed accordingly is connected to the other pole of the AC power source <NUM>.

The diodes D1a to D2b are connected in parallel to the respective transistors Q1a to Q2b such that the collector terminal of the transistor is connected to the cathode terminal of the diode and that the emitter terminal of the transistor is connected to the anode terminal of the diode. The transistor and the diode connected in parallel to each other constitute a switching element.

In the converter <NUM>, the transistors Q1a to Q2b are turned ON and OFF at the timing when an instruction is provided from the gate driving circuit <NUM>.

The gate driving circuit <NUM> changes the ON and OFF states of the transistors Q1a to Q2b of the converter <NUM> on the basis of instruction voltages from the heat-source-side microcomputer <NUM>. Specifically, the gate driving circuit <NUM> generates pulsed gate control voltages Pq, Pr, Ps, and Pt having a duty determined by the heat-source-side microcomputer <NUM> so as to control a current flowing from the AC power source <NUM> toward the heat source to a predetermined value. The generated gate control voltages Pq, Pr, Ps, and Pt are applied to the gate terminals of the respective transistors Q1a to Q2b.

The reactor <NUM> is connected in series to the AC power source <NUM> between the AC power source <NUM> and the converter <NUM>. Specifically, one end thereof is connected to one pole of the AC power source <NUM>, and the other end thereof is connected to one input terminal of the converter <NUM>.

The heat-source-side microcomputer <NUM> turns ON/OFF the transistors Q1a and Q1b or the transistors Q2a and Q2b of the upper and lower arms of the converter <NUM> to short-circuit/open the transistors for a predetermined time, and controls a current to, for example, a substantially sinusoidal state, thereby improving a power factor of power source input and suppressing harmonic components.

In addition, the heat-source-side microcomputer <NUM> performs cooperative control between the converter and the inverter so as to control a short-circuit period on the basis of a duty ratio of a gate control voltage for controlling the inverter <NUM>.

The air conditioner <NUM> is highly efficient and does not require an electrolytic capacitor on the output side of the converter <NUM>, and thus an increase in the size and cost of the circuit is suppressed.

<FIG> is a circuit block diagram of a power conversion device 130B according to a modification example of the second embodiment. In <FIG>, this modification example is different from the second embodiment in that a converter <NUM> for three phases is adopted instead of the converter <NUM> for a single phase, to support the three-phase AC power source <NUM> instead of the single-phase AC power source <NUM>. In accordance with the change from the converter <NUM> for a single phase to the converter <NUM> for three phases, a gate driving circuit <NUM> is adopted instead of the gate driving circuit <NUM>. Furthermore, reactors <NUM> are connected between the converter <NUM> and the output sides of the respective phases. Capacitors are connected between input-side terminals of the reactors <NUM>. Alternatively, these capacitors may be removed.

The converter <NUM> includes a plurality of insulated gate bipolar transistors (IGBTs, hereinafter simply referred to as transistors) Q0a, Q0b, Q1a, Q1b, Q2a, and Q2b, and a plurality of diodes D0a, D0b, D1a, D1b, D2a, and D2b.

The transistors Q0a and Q0b are connected in series to each other to constitute upper and lower arms, and a node formed accordingly is connected to the R-phase output side of the AC power source <NUM>. The transistors Q1a and Q1b are connected in series to each other to constitute upper and lower arms, and a node formed accordingly is connected to the S-phase output side of the AC power source <NUM>. The transistors Q2a and Q2b are connected in series to each other to constitute upper and lower arms, and a node formed accordingly is connected to the T-phase output side of the AC power source <NUM>.

The diodes D0a to D2b are connected in parallel to the respective transistors Q0a to Q2b such that the collector terminal of the transistor is connected to the cathode terminal of the diode and that the emitter terminal of the transistor is connected to the anode terminal of the diode. The transistor and the diode connected in parallel to each other constitute a switching element.

In the converter <NUM>, the transistors Q<NUM>a to Q2b are turned ON and OFF at the timing when an instruction is provided from the gate driving circuit <NUM>.

The gate driving circuit <NUM> changes the ON and OFF states of the transistors Q0a to Q2b of the converter <NUM> on the basis of instruction voltages from the heat-source-side microcomputer <NUM>. Specifically, the gate driving circuit <NUM> generates pulsed gate control voltages Po, Pp, Pq, Pr, Ps, and Pt having a duty determined by the heat-source-side microcomputer <NUM> so as to control a current flowing from the AC power source <NUM> toward the heat source to a predetermined value. The generated gate control voltages Po, Pp, Pq, Pr, Ps, and Pt are applied to the gate terminals of the respective transistors Q0a to Q2b.

<FIG> is a circuit block diagram of a power conversion device 30C mounted in an air conditioner according to a third embodiment of the present disclosure.

In <FIG>, the power conversion device 30C is a matrix converter <NUM>.

The matrix converter <NUM> is configured by connecting bidirectional switches S1a, S2a, and S3a to one end of input from the AC power source <NUM> and connecting bidirectional switches S1b, S2b, and S3b to the other end.

An intermediate terminal between the bidirectional switch S1a and the bidirectional switch S1b connected in series to each other is connected to one end of the U-phase winding Lu among the three-phase windings of the motor <NUM>. An intermediate terminal between the bidirectional switch S2a and the bidirectional switch S2b connected in series to each other is connected to one end of the V-phase winding Lv among the three-phase windings of the motor <NUM>. An intermediate terminal between the bidirectional switch S3 and the bidirectional switch S3b connected in series to each other is connected to one end of the W-phase winding Lw among the three-phase windings of the motor <NUM>.

AC power input from the AC power source <NUM> is switched by the bidirectional switches S1a to S3b and is converted into AC having a predetermined frequency, thereby being capable of driving the motor <NUM>.

<FIG> is a circuit diagram conceptionally illustrating a bidirectional switch. In <FIG>, the bidirectional switch includes transistors Q61 and Q62, diodes D61 and D62, and terminals Ta and Tb. The transistors Q61 and Q62 are insulated gate bipolar transistors (IGBTs).

The transistor Q61 has an emitter E connected to the terminal Ta, and a collector C connected to the terminal Tb via the diode D61. The collector C is connected to the cathode of the diode D61.

The transistor Q62 has an emitter E connected to the terminal Tb, and a collector C connected to the terminal Ta via the diode D62. The collector C is connected to the cathode of the diode D62. The terminal Ta is connected to an input side, and the terminal Tb is connected to an output side.

Turning ON of the transistor Q61 and turning OFF of the transistor Q62 enables a current to flow from the terminal Tb to the terminal Ta via the diode D61 and the transistor Q61 in this order. At this time, a flow of a current from the terminal Ta to the terminal Tb (backflow) is prevented by the diode D61.

On the other hand, turning OFF of the transistor Q61 and turning ON of the transistor Q62 enables a current to flow from the terminal Ta to the terminal Tb via the diode D62 and the transistor Q62 in this order. At this time, a flow of a current from the terminal Tb to the terminal Ta (backflow) is prevented by the diode D62.

<FIG> is a circuit diagram illustrating an example of a current direction in the matrix converter <NUM>. <FIG> illustrates an example of a path of a current that flows from the AC power source <NUM> via the matrix converter <NUM> to the motor <NUM>. The current flows from one pole of the AC power source <NUM> to the other pole of the AC power source <NUM> via the bidirectional switch S1a, the U-phase winding Lu which is one of the three-phase windings of the motor <NUM>, the W-phase winding Lw, and the bidirectional switch S3b. Accordingly, power is supplied to the motor <NUM> and the motor <NUM> is driven.

<FIG> is a circuit diagram illustrating an example of another current direction in the matrix converter <NUM>. In <FIG>, a current flows from one pole of the AC power source <NUM> to the other pole of the AC power source <NUM> via the bidirectional switch S3a, the W-phase winding Lw which is one of the three-phase windings of the motor <NUM>, the U-phase winding Lu, and the bidirectional switch S1b. Accordingly, power is supplied to the motor <NUM> and the motor <NUM> is driven.

The air conditioner <NUM> is highly efficient and does not require an electrolytic capacitor on the output side of the matrix converter <NUM>, and thus an increase in the size and cost of the circuit is suppressed.

<FIG> is a circuit block diagram of a power conversion device 130C according to a modification example of the third embodiment. In <FIG>, this modification example is different from the third embodiment in that a matrix converter <NUM> for three phases is adopted instead of the matrix converter <NUM> for a single phase, to support the three-phase AC power source <NUM> instead of the single-phase AC power source <NUM>.

It is also a difference that a gate driving circuit <NUM> is adopted instead of a gate driving circuit <NUM> in accordance with the change from the matrix converter <NUM> for a single phase to the matrix converter <NUM> for three phases. Furthermore, reactors L1, L2, and L3 are connected between the matrix converter <NUM> and the output sides of the respective phases.

Predetermined three-phase AC voltages obtained through conversion by bidirectional switches S1a to S3c are supplied to the motor <NUM> via the phase winding terminals TU, TV, and TW. The reactors L1, L2, and L3 are connected to respective input terminals of matrix converter <NUM>. Capacitors C1, C2, and C3 are connected to each other at one ends thereof, and the other ends thereof are connected to output terminals of matrix converter <NUM>.

In the power conversion device 130C, the reactors L1, L2, and L3 are short-circuited via the matrix converter <NUM>, and thereby the energy supplied from the three-phase AC power source <NUM> can be accumulated in the reactors L1, L2, and L3 and the voltages across the capacitors C1, C2, and C3 can be increased. Accordingly, a voltage utilization rate of <NUM> or more can be achieved.

At this time, voltage-type three-phase AC voltages Vr, Vs, and Vt are input to the input terminals of the matrix converter <NUM>, and current-type three-phase AC voltages Vu, Vv, and Vw are output from the output terminals.

In addition, the capacitors C1, C2, and C3 constitute LC filters with the reactors L1, L2, and L3, respectively. Thus, high-frequency components included in voltages output to the output terminals can be reduced, and torque pulsation components and noise generated in the motor <NUM> can be reduced.

Furthermore, compared with an AC-AC conversion circuit including a rectifier circuit and an inverter, the number of switching elements is smaller, and the loss that occurs in the power conversion device 130C can be reduced.

In the power conversion device <NUM>, a clamp circuit <NUM> is connected between the input terminals and the output terminals. Thus, a surge voltage generated between the input terminals and the output terminals of the matrix converter <NUM> through switching of the bidirectional switches S1a to S3c can be absorbed by a capacitor in the clamp circuit <NUM> (see <FIG>).

<FIG> is a circuit diagram of the clamp circuit <NUM>. In <FIG>, the clamp circuit <NUM> has diodes D31a to D36b, a capacitor C37, and terminals <NUM> to <NUM>.

The anode of the diode D31a and the cathode of the diode D31b are connected to the terminal <NUM>. The anode of the diode D32a and the cathode of the diode D32b are connected to the terminal <NUM>. The anode of the diode D33a and the cathode of the diode D33b are connected to the terminal <NUM>.

The cathodes of the diodes D31a, D32a, and D33a are connected to one end of the capacitor C37. The anodes of the diodes D31b, D32b, and D33b are connected to the other end of the capacitor C37.

The anode of the diode D34a and the cathode of the diode D34b are connected to the terminal <NUM>. The anode of the diode D35a and the cathode of the diode D35b are connected to the terminal <NUM>. The anode of the diode D36a and the cathode of the diode D36b are connected to the terminal <NUM>.

The cathodes of the diodes D34a, D35a, and D36a are connected to the one end of the capacitor C37. The anodes of the diodes D34b, D35b, and D36b are connected to the other end of the capacitor C37.

The terminals <NUM>, <NUM>, and <NUM> are connected to the input side of the matrix converter <NUM>, and the terminals <NUM>, <NUM>, and <NUM> are connected to the output side of the matrix converter <NUM>. Because the clamp circuit <NUM> is connected between the input terminals and the output terminals, a surge voltage generated between the input terminals and the output terminals of the matrix converter <NUM> through switching of the bidirectional switches S1a to S3b can be absorbed by the capacitor C37 in the clamp circuit <NUM>.

As described above, the power conversion device 130C is capable of supplying a voltage larger than a power source voltage to the motor <NUM>. Thus, even if the current flowing through the power conversion device 130C and the motor <NUM> is small, a predetermined motor output can be obtained, in other words, only a small current is used. Accordingly, the loss that occurs in the power conversion device 130C and the motor <NUM> can be reduced.

Claim 1:
An air conditioner comprising:
a compressor (<NUM>) that is configured to compress a refrigerant mixture containing at least <NUM>,<NUM>-difluoroethylene;
a motor (<NUM>) that is configured to drive the compressor (<NUM>); and
a power conversion device (<NUM>, <NUM>, 30B, 130B, 30C, 130C) that is connected between an alternating-current (AC) power source and the motor (<NUM>), that has a switching element, and that is configured to control the switching element such that an output of the motor (<NUM>) becomes a target value,
wherein the refrigerant comprises HFO-<NUM>(E), R32, and R1234yf,
characterized in that
when the mass% of HFO-<NUM>(E), R32, and R1234yf based on their sum in the refrigerant is respectively represented by x, y and z, coordinates (x,y,z) in a ternary composition diagram in which the sum of HFO-<NUM>(E), R32, and R1234yf is <NUM> mass% are within the range of a figure surrounded by line segments ON, NU, and UO that connect the following <NUM> points:
point O (<NUM>, <NUM>, <NUM>),
point N (<NUM>, <NUM>, <NUM>), and
point U (<NUM>, <NUM>, <NUM>),
or on these line segments;
the line segment ON is represented by coordinates (<NUM>.0072y<NUM>-<NUM>.6701y+<NUM>, y, -<NUM>.0072y<NUM>-<NUM>.3299y+<NUM>);
the line segment NU is represented by coordinates (<NUM>.0083y<NUM>-<NUM>.7403y+<NUM>, y, -<NUM>.0083y<NUM>+<NUM>.7403y+<NUM>); and
the line segment UO is a straight line, and
the refrigerant comprises HFO-<NUM>(E), R32, and R1234yf in a total amount of <NUM> mass% or more based on the entire refrigerant.