Patent Publication Number: US-2021189208-A1

Title: Refrigerant containing carbon dioxide and fluorinated hydrocarbon, use therefor, refrigerating machine provided with same, and operation method for said refrigerating machine

Description:
TECHNICAL FIELD 
     The present disclosure relates to a refrigerant containing a fluorinated hydrocarbon and carbon dioxide, use of the refrigerant, a refrigerating machine containing the refrigerant, and a method for operating the refrigerating machine. 
     BACKGROUND ART 
     R410A, which is a two-component mixed refrigerant of difluoromethane (CH 2 F 2 , HFC-32, and R32) and pentafluoroethane (CF 3 CHF 2 , HFC-125, and R125), and is a pseudo-azeotropic refrigerant, is used in refrigerants for freezing or refrigerating purposes. R410A has a GWP of 2088. 
     In Japan, for example, due to “chlorofluorocarbon law” regulations, refrigerants for condensing units and stationary freezing and refrigerating units must be replaced with refrigerants with a GWP of 1500 or less after the year 2025. Thus, there is demand for the development of novel refrigerants that maintain performance equivalent to that of R410A, while having a low GWP; and a variety of proposals have been reported (PTL 1 to 3). 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: JPH05-500071 
         PTL 2: U.S. Pat. No. 5,783,341 
         PTL 3: U.S. Pat. No. 6,062,061 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     The present inventors conceived that a refrigerant composition that has a refrigerating capacity equivalent to that of R410A and a low GWP, as well as ASHRAE non-flammability, had not yet been developed in the art. They conducted studies and determined the desired properties of an alternative refrigerant for R410A on their own accord. The following are the desired properties: (1) a GWP of 1500 or less, (2) ASHRAE non-flammability, (3) a COP equivalent to that of R410A, and (4) a refrigerating capacity equivalent to that of R410A. An object of the present disclosure is to solve this unique problem. 
     Solution to Problem 
     The present inventors conducted extensive research to solve the problem, and found that a mixed refrigerant that contains at least one fluorinated hydrocarbon selected from the group consisting of R32, R125, 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropene (R1234yf), and 1,3,3,3-tetrafluoro-1-propene (R1234ze), and 1 mass % to 12 mass % of CO 2  (R744) based on the entire refrigerant has the properties described above. 
     After conducting further research based on this finding, the inventors completed the present disclosure. The present disclosure includes the following embodiments. 
     Item 1. 
     A composition comprising a refrigerant,
         the refrigerant comprising CO 2 , R32, R125, and R134a, wherein   when the mass % of CO 2 , R32, R125, and R134a based on their sum in the refrigerant is respectively x, a, b, and c,   coordinates (a,b,c) in a ternary composition diagram in which 2.7≤x≤6.0, and the sum of R32, 8125, and R134a is (100−x) mass % fall within a triangular region surrounded by line segments that connect the following points:
 
point E (−0.0781x 2 +1.8309x+41.926, 1.1194x+19.094, 100−a−b−x),
 
point F (−3x+54.4, −0.3945x+23.17, 100−a−b−x), and
 
point G (−2.0597x+51.853, −2.1514x+27.908, 100−a−b−x),
 
or on the line segments, or
   coordinates (a,b,c) in a ternary composition diagram in which 6.0≤x&lt;9.0, and the sum of R32, R125, and R134a is (100−x) mass % fall within a triangular region surrounded by line segments that connect the following points:
 
point E (x+44.1, 1.0357x+19.593, 100−a−b−x),
 
point F (−3x+54.4, −0.4x+23.2, 100−a−b−x), and
 
point G (−2.1643x+52.493, −2.1x+27.6, 100−a−b−x),
 
or on the line segments.
       

     Item 2. 
     A composition comprising a refrigerant,
         the refrigerant comprising CO 2 , R32, R125, and R134a, wherein   when the mass % of CO 2 , R32, R125, and R134a based on their sum in the refrigerant is respectively x, a, b, and c,   coordinates (a,b,c) in a ternary composition diagram in which 4.0≤x≤6.0, and the sum of R32, R125, and R134a is (100−x) mass % fall within a triangular region surrounded by line segments that connect the following points:
 
point E′ (x+38.6, 1.0468x+17.431, 100−a−b−x),
 
point F (−3x+54.4, −0.3945x+23.17, 100−a−b−x), and
 
point G′ (−2.1903x+51.358, −2.142x+30.148, 100−a−b−x),
 
or on the line segments, or
   coordinates (a,b,c) in a ternary composition diagram in which 6.0≤x&lt;6.1, and the sum of R32, R125, and R134a is (100−x) mass % fall within a triangular region surrounded by line segments that connect the following points:
 
point E′ (x+38.6, 1.0468x+17.431, 100−a−b−x),
 
point F (−3x+54.4, −0.4x+23.2, 100−a−b−x), and
 
point G′ (−2.1903x+51.358, −2.142x+30.148, 100−a−b−x),
 
or on the line segments.
       

     Item 3. 
     A composition comprising a refrigerant,
         the refrigerant comprising 002, R32, R125, and R134a, wherein   when the mass % of CO 2 , R32, R125, and R134a based on their sum in the refrigerant is respectively x, a, b, and c,   coordinates (a,b,c) in a ternary composition diagram in which 8.0≤x&lt;9.0, and the sum of R32, R125, and R134a is (100−x) mass % fall within a quadrangular region surrounded by line segments that connect the following points:
 
point J (−1.1x+51.1, −3.9x+55.5, 100−a−b−x),
 
point K (−0.9x+50.8, −4.3x+57.2, 100−a−b−x),
 
point H (−2.9549x+59.61, −0.391x+25.122, 100−a−b−x), and
 
point I (−2.0451x+54.79, −2x+33.6, 100−a−b−x),
 
or on the line segments.
       

     Item 4. 
     A composition comprising a refrigerant,
         the refrigerant comprising CO 2 , R32, R125, and R134a, wherein   when the mass % of CO 2 , R32, R125, and R134a based on their sum in the refrigerant is respectively x, a, b, and c,   coordinates (a,b,c) in a ternary composition diagram in which 6.7≤x&lt;9.0, and the sum of R32, R125, and R134a is (100−x) mass % fall within a quadrangular region surrounded by line segments that connect the following points:
 
point L (1.4749x 2 −25.374x+147.89, −1.8729x 2 +26.839x−71.649, 100−a−b−x), point M (0.7224x 2 −13.081x+99.713, −0.8328x 2 +9.8572x−5.0599, 100−a−b−x),
 
point H (−2.9549x+59.61, −0.391x+25.122, 100−a−b−x), and
 
point I (−2.0451x+54.79, −2x+33.6, 100−a−b−x),
 
or on the line segments.
       

     Item 5. 
     The composition according to any one of Items 1 to 4, comprising R32, R125, R134a, and CO 2  in a total amount of 99.5 mass % or more based on the entire refrigerant. 
     Item 6. 
     The composition according to any one of Items 1 to 5, comprising a refrigerant oil. 
     Item 7. 
     The composition according to any one of Items 1 to 6, wherein the refrigerant is used as an alternative refrigerant for R410A. 
     Item 8. 
     A refrigerating machine comprising the composition according to any one of Items 1 to 7. 
     Item 9. 
     The refrigerating machine according to Item 8, comprising a heat exchanger in which a flow of the refrigerant and a flow of an external heat medium are in countercurrent flow. 
     Item 10. 
     The refrigerating machine according to Item 8 or 9, comprising a heat-source-side heat exchanger and a user-side heat exchanger, wherein when the user-side heat exchanger functions as an evaporator, the evaporating temperature of the refrigerant is 0° C. or below. 
     Item 11. 
     A refrigerating machine comprising 
     a refrigerant comprising
         at least one fluorinated hydrocarbon selected from the group consisting of difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropene (R1234yf), and 1,3,3,3-tetrafluoro-1-propene (R1234ze), and   carbon dioxide (CO 2 ); and       

     a heat exchanger in which a flow of the refrigerant and a flow of an external heat medium are in countercurrent flow. 
     Item 12. 
     A refrigerating machine comprising 
     a refrigerant comprising
         at least one fluorinated hydrocarbon selected from the group consisting of difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropene (R1234yf), and 1,3,3,3-tetrafluoro-1-propene (R1234ze), and   carbon dioxide (CO 2 );       

     a heat-source-side heat exchanger; and 
     a user-side heat exchanger, wherein when the user-side heat exchanger functions as an evaporator, the evaporating temperature of the refrigerant is 0° C. or below. 
     Advantageous Effects of Invention 
     The refrigerant according to the present disclosure has the following properties, which are typically required in alternative refrigerants for R410A: (1) a GWP of 1500 or less, (2) ASHRAE non-flammability, (3) a COP equivalent to that of R410A, and (4) a refrigerating capacity equivalent to that of R410A. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram that illustrates a device used in a flammability test. 
         FIG. 2  is a schematic view that illustrates examples of countercurrent heat exchangers. 
         FIG. 3  is a schematic view that illustrates examples of countercurrent heat exchangers.  FIG. 3( a )  is a plan view, and  FIG. 3( b )  is a perspective view. 
         FIG. 4  is a schematic view that illustrates an embodiment of refrigerant circuits in the refrigerating machine according to the present disclosure. 
         FIG. 5  is a schematic view that illustrates an example of modified versions of the refrigerant circuit of  FIG. 4 . 
         FIG. 6  is a schematic view that illustrates an example of modified versions of the refrigerant circuit of  FIG. 5 . 
         FIG. 7  is a schematic view that illustrates an example of modified versions of the refrigerant circuit of  FIG. 5 . 
         FIG. 8  is a schematic view that describes off-cycle defrost. 
         FIG. 9  is a schematic view that describes heating defrost. 
         FIG. 10  is a schematic view that describes reverse-cycle hot-gas defrost. 
         FIG. 11  is a schematic view that describes normal-cycle hot-gas defrost. 
         FIG. 12  is a ternary diagram that shows points C, C′, D, and D′ when the concentration of CO 2  is 6 mass %. 
         FIG. 13  is a ternary diagram that shows points A to C when the concentration of CO 2  is 2.7 mass %. 
         FIG. 14  is a ternary diagram that shows points A to G when the concentration of CO 2  is 4 mass %. 
         FIG. 15  is a ternary diagram that shows points A to G when the concentration of CO 2  is 6 mass %. 
         FIG. 16  is a ternary diagram that shows points A to G when the concentration of CO 2  is 8 mass %. 
         FIG. 17  is a ternary diagram that shows points A to G when the concentration of CO 2  is 9 mass %. 
         FIG. 18  is a ternary diagram that shows points A and B, and E′ to G′ when the concentration of CO 2  is 4 mass %. 
         FIG. 19  is a ternary diagram that shows points A and B, and E′ to G′ when the concentration of CO 2  is 5 mass %. 
         FIG. 20  is a ternary diagram that shows points A and B, and E′ to G′ when the concentration of CO 2  is 6 mass %. 
         FIG. 21  is a ternary diagram that shows points A and B, C′ and D′, and H to K when the concentration of CO 2  is 8 mass %. 
         FIG. 22  is a ternary diagram that shows points A and B, C′ and D′, and H to K when the concentration of CO 2  is 9 mass %. 
         FIG. 23  is a ternary diagram that shows points A and B, C′ and D′, H and I, and L and M when the concentration of CO 2  is 6.7 mass %. 
         FIG. 24  is a ternary diagram that shows points A and B, C′ and D′, H and I, and L and M when the concentration of CO 2  is 8 mass %. 
         FIG. 25  is a ternary diagram that shows points A and B, C′ and D′, H and I, and L and M when the concentration of CO 2  is 9 mass %. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Definition of Terms 
     In this specification, the term “refrigerant” includes at least compounds that are specified in ISO817 (International Organization for Standardization), and that are provided 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 provided. Refrigerants are broadly divided into “fluorocarbon-based compounds” and “non-fluorocarbon-based compounds,” in terms of the structure of the compounds. “Fluorocarbon-based compounds” include chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFC), and hydrofluorocarbons (HFC). “Non-fluorocarbon-based compounds” include propane (R290), propylene (R1270), butane (R600), isobutane (R600a), carbon dioxide (R744), and ammonia (R717). 
     In the present specification, the phrase “a composition comprising a refrigerant” includes at least the following: 
     (1) a refrigerant itself (including a mixture of refrigerants);
 
(2) a composition that further comprises other components, and that can be used in obtaining a working fluid for a refrigerating machine by mixing the composition with at least a refrigerant oil, and
 
(3) a working fluid for a refrigerating machine that contains a refrigerant oil.
 
     In the present specification, of these three aspects, the composition in item (2) is referred to as a “refrigerant composition” in order to distinguish it from the refrigerant itself, which includes a mixture of refrigerants. The working fluid for a refrigerating machine in item (3) is referred to as a “refrigerant oil-containing working fluid” in order to distinguish it from the “refrigerant composition.” 
     In this specification, when the term “alternative” is used in the 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 member of the refrigerant 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/or adjustment necessary for replacing the first refrigerant with the second refrigerant is smaller. 
     The term “alternative” also includes the second type of “alternative” that means that equipment designed for operation using the second refrigerant is operated for the same use as the existing use with the first refrigerant, 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 the 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, “non-flammability” in regards to a refrigerant means that a refrigerant is categorized into “Class 1” according to the US ANSI/ASHRAE Standard 34-2013. Specifically, a refrigerant is tested for leakage in storage, transport, and use in accordance with the ANSI/ASHRAE Standard 34-2013 to determine its worst case of fractionation for flammability (WCFF: most flammable formulation); when the WCFF formulation is determined to be non-flammable in the test based on the ASTM 5681-2009 (a standard test method for concentration limits of flammability of chemicals (vapors and gases)), the refrigerant is categorized into Class 1. 
     1. Refrigerant 
     1.1 Refrigerant Component 
     The refrigerant according to the present disclosure is a mixed refrigerant that contains at least one fluorinated hydrocarbon selected from the group consisting of difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropene (R1234yf), and 1,3,3,3-tetrafluoro-1-propene (R1234ze); and carbon dioxide (CO: (R744)). 
     The refrigerant according to the present disclosure has the following desired properties as an alternative refrigerant for R410A: (1) a GWP of 1500 or less, (2) ASHRAE non-flammability, (3) a COP equivalent to that of R410A, and (4) a refrigerating capacity similar to that of R410A. 
     In addition to the properties descried above, the refrigerant according to the present disclosure, due to its temperature glide, can also have effects in improving energy efficiency and/or refrigerating capacity when used in a refrigerating machine equipped with a heat exchanger in which the flow of the refrigerant and the flow of the external heat medium are in countercurrent flow. 
     A refrigerant according to the present disclosure that satisfies the following requirement 1-1 or 1-2 is preferable, because such a refrigerant shows ASHRAE non-flammability, a GWP of 1500 or less, and has a refrigerating capacity similar to that of R410A. Below, the mass % of CO 2 , R32, R125, and R134a based on their sum is respectively referred to as x, a, b, and c. 
     Requirement 1-1 
     In a ternary composition diagram in which 2.7≤x&lt;6.0, and the sum of R32, R125, and R134a is (100−x) mass %, coordinates (a,b,c) fall within a triangular region surrounded by line segments that connect the following points: 
     point E1 (−0.0781x 2 +1.8309x+41.926, 1.1194x+19.094, 100−a−b−x),
 
point F1 (−3x+54.4, −0.3945x+23.17, 100−a−b−x), and
 
point G1 (−2.0597x+51.853, −2.1514x+27.908, 100−a−b−x),
 
or on the line segments.
 
     Requirement 1-2 
     In a ternary composition diagram in which 6.0≤x&lt;9.0, and the sum of R32, R125, and R134a is (100−x) mass %, coordinates (a,b,c) fall within a triangular region surrounded by line segments that connect the following points: 
     point E2 (x+44.1, 1.0357x+19.593, 100−a−b−x),
 
point F2 (−3x+54.4, −0.4x+23.2, 100−a−b−x), and
 
point G2 (−2.1643x+52.493, −2.1x+27.6, 100−a−b−x),
 
or on the line segments.
 
     It is preferable to further consider safety factors in the ASHRAE non-flammability limit, taking into consideration the purity of individual refrigerants during the production process and/or a margin of error during the mixing process. In this regard, for example, it is preferable to change the formulation of the refrigerants so as to include the non-flammable refrigerant R125 in a larger amount based on the ASHRAE non-flammable formulation. For example, a formulation changed so as to include additional “y” mass % of the non-flammable refrigerant R125 based on the ASHRAE non-flammable formulation is referred to as “ASHRAE non-flammability (+y %)” in this specification. 
     A refrigerant according to the present disclosure that satisfies the following requirement 2-1 or 2-2 is preferable, because such a refrigerant has a non-flammable formulation that takes into consideration safety factors based on the ASHRAE non-flammable formulation as described above, a GWP of 1500 or less, and a refrigerating capacity similar to that of R410A. 
     Requirement 2-1 
     In a ternary composition diagram in which 4.0≤x≤6.1, and the sum of R32, R125, and R134a is (100−x) mass %, coordinates (a,b,c) fall within a triangular region surrounded by line segments that connect the following points: 
     point E1′ (x+38.6, 1.0468x+17.431, 100−a−b−x),
 
point F1 (−3x+54.4, −0.3945x+23.17, 100−a−b−x), and
 
point G1′ (−2.1903x+51.358, −2.142x+30.148, 100−a−b−x), or on the line segments.
 
     Requirement 2-2 
     In a ternary composition diagram in which 6.0≤x&lt;6.1, and the sum of R32, R125, and R134a is (100−x) mass %, coordinates (a,b,c) fall within a triangular region surrounded by line segments that connect the following points: 
     point E2′ (x+38.6, 1.0468x+17.431, 100−a−b−x),
 
point F2 (−3x+54.4, −0.4x+23.2, 100−a−b−x), and
 
point G2′ (−2.1903x+51.358, −2.142x+30.148, 100−a−b−x),
 
or on the line segments.
 
     A refrigerant according to the present disclosure that satisfies the following requirement 3 is preferable, because such a refrigerant has a non-flammable formulation that takes into consideration safety factors based on the ASHRAE non-flammable formulation as described above, and shows a GWP of 1500 or less, a refrigerating capacity similar to that of R410A, and a compressor outlet pressure similar to that of R410A. 
     Requirement 3 
     In a ternary composition diagram in which 8.0≤x&lt;9.0, and the sum of R32, R125, and R134a is (100−x) mass %, coordinates (a,b,c) fall within a quadrangular region surrounded by line segments that connect the following points: 
     point J (−1.1x+51.1, −3.9x+55.5, 100−a−b−x),
 
point K (−0.9x+50.8, −4.3x+57.2, 100−a−b−x),
 
point H (−2.9549x+59.61, −0.391x+25.122, 100−a−b−x), and
 
point I (−2.0451x+54.79, −2x+33.6, 100−a−b−x),
 
or on the line segments.
 
     A refrigerant according to the present disclosure that satisfies the following requirement 4 is preferable, because such a refrigerant has a non-flammable formulation that takes into consideration safety factors based on the ASHRAE non-flammable formulation as described above, and shows a GWP of 1500 or less, a refrigerating capacity similar to that of R410A, and a compressor outlet pressure similar to that of R410A. 
     Requirement 4 
     In a ternary composition diagram in which 6.7≤x&lt;9.0, and the sum of R32, R125, and R134a is (100−x) mass %, coordinates (a,b,c) fall within a quadrangular region surrounded by line segments that connect the following points: 
     point L (1.4749x 2 −25.374x+147.89, −1.8729x 2 +26.839x−71.649, 100−a−b−x),
 
point M (0.7224x 2 −13.081x+99.713, −0.8328x 2 +9.8572x−5.0599, 100−a−b−x),
 
point H (−2.9549x+59.61, −0.391x+25.122, 100−a−b−x), and
 
point I (−2.0451x+54.79, −2x+33.6, 100−a−b−x),
 
or on the line segments.
 
     The refrigerant according to the present disclosure may further contain other additional one or more refrigerants and/or unavoidable impurities in addition to R32, R125, R134a, R1234yf, and CO 2 , as long as the properties and effects described above are not impaired. It is preferred that the refrigerant according to the present disclosure contain R32, R125, R134a, R1234yf, and CO 2  in a total amount of 99.5 mass % or more based on the entire refrigerant. In this case, the total amount of other additional one or more refrigerants and unavoidable impurities is 0.5 mass % or less based on the entire refrigerant. The refrigerant contains R32, R125, R134a, R1234yf, and CO 2  in a total amount of more preferably 99.75 mass % or more, and still more preferably 99.9 mass % or more based on the entire refrigerant. 
     Additional refrigerants are not limited, and can be selected from a wide range of refrigerants. A single, or two or more mixed refrigerants may be added as additional refrigerants. 
     1.2 Application 
     The refrigerant according to the present disclosure can be suitably used in (A) a refrigerating machine equipped with a heat exchanger in which the flow of the refrigerant and the flow of the external heat medium are in countercurrent flow; and/or (B) a refrigerating machine equipped with a heat-source-side heat exchanger and a user-side heat exchanger, with the evaporating temperature of the refrigerant being 0° C. or below when the user-side heat exchanger functions as an evaporator. Details of these specific refrigerating machines (A) and (B) are described later. 
     The refrigerant according to the present disclosure is suitable for use as an alternative refrigerant for R410A. 
     2. Refrigerant Composition 
     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 optionally comprise at least one of the following other components. 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 preferred 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 0 to 1 mass %, and more preferably 0 to 0.1 mass %. 
     2.1. Water 
     The refrigerant composition according to the present disclosure may comprise a small amount of water. The water content in the refrigerant composition is preferably 0.1 parts by mass or less, per 100 parts by mass of the refrigerant. A small amount of water contained in the refrigerant composition stabilizes the double bonds in the molecules of unsaturated fluorocarbon compounds that can be present in the refrigerant; and makes it less likely for the unsaturated fluorocarbon compounds to be oxidized, thus increasing the stability of the refrigerant composition. 
     2.2. Tracer 
     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 typically used tracers. 
     Examples of tracers include hydrofluorocarbons, deuterated hydrocarbons, deuterated hydrofluorocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodinated compounds, alcohols, aldehydes, ketones, and nitrous oxide (N 2 O). The tracer is particularly preferably a hydrofluorocarbon or a fluoroether. 
     2.3. Ultraviolet Fluorescent Dye 
     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 typically 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. 
     2.4. Stabilizer 
     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 typically 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 1,4-dioxane. 
     Examples of amines include 2,2,3,3,3-pentafluoropropylamine, and diphenylamine. 
     Examples of stabilizers also include butylhydroxyxylene and benzotriazole. 
     The content of the stabilizer is not limited. Typically, the content of the stabilizer is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 2 parts by mass, per 100 parts by mass of the refrigerant. 
     2.6. Polymerization Inhibitor 
     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 typically used polymerization inhibitors. 
     Examples of polymerization inhibitors include 4-methoxy-1-naphthol, hydroquinone, hydroquinone methyl ether, dimethyl-t-butylphenol, 2,6-di-tert-butyl-p-cresol, and benzotriazole. 
     The content of the polymerization inhibitor is not limited. Typically, the content of the polymerization inhibitor is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 2 parts by mass, per 100 parts by mass of the refrigerant. 
     3. Refrigerant Oil-Containing Working Fluid 
     The refrigerant oil-containing working fluid according to the present disclosure comprises at least the refrigerant or refrigerant composition of the present disclosure, and a refrigerant oil; and is used as a working fluid for a refrigerating machine. Specifically, the refrigerant oil-containing working fluid of the present disclosure is obtained by mixing a refrigerant oil for use in a compressor of a refrigerating machine with the refrigerant or refrigerant composition. The refrigerant oil-containing working fluid typically comprises 10 to 50 mass % of a refrigerant oil. 
     3.1 Refrigerant Oil 
     The composition according to the present disclosure may comprise only one refrigerant oil, or two or more refrigerant oils. 
     The refrigerant oil is not limited, and can be suitably selected from typically used refrigerant oils. When doing so, a refrigerant oil that is superior, for example, in miscibility with the mixture and action of improving the stability of the mixture can be suitably selected, as necessary. 
     The base oil of the refrigerant 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 refrigerant oil may further contain an additive in addition to the base oil. The additive may be at least one member selected from the group consisting of antioxidants, extreme-pressure additives, acid scavengers, oxygen scavengers, copper deactivators, rust inhibitors, oil agents, and antifoaming agents. 
     The refrigerant oil preferably has a kinematic viscosity of 5 to 400 cSt at 40° C., from the standpoint of lubrication. 
     The refrigerant oil-containing working fluid according to the present disclosure may further optionally comprise at least one additive. Examples of additives include the following compatibilizing agent. 
     3.2 Compatibilizing Agent 
     The refrigerant oil-containing working fluid according to the present disclosure may comprise only one compatibilizing agent, or two or more compatibilizing agents. 
     The compatibilizing agent is not limited, and can be suitably selected from typically used compatibilizing agents. 
     Examples of compatibilizing agents include polyoxyalkylene glycol ethers, amides, nitriles, ketones, chlorocarbons, esters, lactones, aryl ethers, fluoroethers, and 1,1,1-trifluoroalkanes. The compatibilizing agent is particularly preferably a polyoxyalkylene glycol ether. 
     3. Refrigerating Machine 
     Below, refrigerating machines according to embodiments of the present disclosure are described with reference to drawings. The use of the refrigerant according to the present disclosure in these refrigerating machines can provide the excellent effects described above. Thus, the refrigerant according to the present disclosure is particularly suitable for use in these refrigerating machines. 
     3.1 Refrigerating Machine (A) 
     A refrigerating machine (A) comprises a countercurrent heat exchanger in which the flow of the refrigerant and the flow of the external heat medium are in countercurrent flow. “Countercurrent” means that the flow of a refrigerant is opposite to the flow of an external heat medium in a heat exchanger (i.e., the refrigerant flows from downstream to upstream in the direction in which the external heat medium flows); and thus differs from concurrent, in which the flow of the refrigerant is in the forward direction of the flow of the external heat medium (the refrigerant flows from upstream to downstream in the direction in which the external heat medium flows). 
     Specifically, when the external heat medium is water, a double-pipe heat exchanger as illustrated in  FIG. 2( a )  may be used as a heat exchanger. For example, the external heat medium is allowed to flow from one side to the other through an inner pipe P 1  of the double pipe (from upstream to downstream in  FIG. 2( a ) , and the refrigerant is allowed to flow through an outer pipe P 2  from the other side to the one side (from downstream to upstream in  FIG. 2( a ) ); this makes the flow of the refrigerant countercurrent with the flow of the external heat medium. When a cylindrical pipe P 3  wound with a spiral pipe P 4  on its outer circumference as illustrated in  FIG. 2( b )  is used as a heat exchanger, the external heat medium is allowed to flow through the cylindrical pipe P 3 , for example, from one side to the other (from upstream to downstream in  FIG. 2( b ) ), and the refrigerant is allowed to flow through the spiral pipe P 4  from the other side to the one side (from downstream to upstream in  FIG. 2( b ) ); this makes the flow of the refrigerant countercurrent with the flow of the external heat medium. Additionally, known heat exchangers in which the refrigerant flows in the direction opposite to the flow of the external heat medium, such as a plate heat exchanger (not shown), are also usable. 
     When the external heat medium is air, a finned tube heat exchanger as illustrated in  FIG. 3  may be used as a heat exchanger. The finned tube heat exchanger comprises a plurality of fins F that are arranged at a predetermined interval, and a heat transfer tube P 5  that appears winding in a planar view. The heat transfer tube P 5  is provided such that multiple straight portions (two portions in  FIG. 3 ) of the heat transfer tube P 5  that are in parallel to each other pass through the plurality of fins F. Of the two ends of the heat transfer tube P 5 , one end serves as an inlet for the refrigerant, and the other serves as an outlet for the refrigerant. Allowing a refrigerant to flow from downstream to upstream as indicated by arrow X in  FIG. 3  in the direction of air flow Y makes the flow of the refrigerant countercurrent with the flow of the external heat medium. 
     The refrigerant according to the present disclosure is a zeotropic composition, and the temperature of the heat medium increases or decreases during isobaric evaporation or condensation. 
     A refrigeration cycle that involves temperature change (temperature glide) during evaporation or condensation is called a “Lorenz cycle.” In a Lorenz cycle, when the evaporator and the condenser that function as a heat exchanger for exchanging heat are of countercurrent type, this decreases the difference in the temperature of the refrigerant between during evaporation and during condensation. However, a difference in temperature sufficiently large to effectively transfer heat is maintained between the refrigerant and the external heat medium, enabling efficient heat exchange. Another advantage of refrigerating machines equipped with a countercurrent heat exchanger is the minimum difference in pressure. Thus, the use of the refrigerant according to the present disclosure in a countercurrent refrigerating machine improves energy efficiency and/or capacity, as compared with the use of the refrigerant in conventional refrigerating machines. 
     3.2 Refrigerating Machine (B) 
     A refrigerating machine (B) comprises a heat-source-side heat exchanger and a user-side heat exchanger, with the evaporating temperature of the refrigerant being 0° C. or below when the user-side heat exchanger functions as an evaporator. The evaporating temperature of the refrigerant can be measured by detecting the temperature of the refrigerant at the outlet of the user-side heat exchanger. The heat exchanger of the refrigerating machine (B) does not have to be of countercurrent type. 
     3.3 A Combination of Refrigerating Machines (A) and (B) 
     In the present disclosure, a refrigerating machine that has the characteristics of both the refrigerating machine (A) and the refrigerating machine (B) may be used. Specifically, a refrigerating machine is usable that comprises a countercurrent heat exchanger in which the flow of the refrigerant and the flow of the external heat medium are in countercurrent flow, with the evaporating temperature of the refrigerant being 0° C. or below when the heat exchanger functions as an evaporator. 
     The refrigerating machine according to the present disclosure can be suitably used as a shipping refrigerating machine provided to shipping containers for overland or marine transport, or as a showcase refrigerating machine provided to refrigerating showcases or freezing showcases installed in shops. 
     3.4 More Detailed Structure of Refrigerating Machine 
     The refrigerating machines (A) and (B) may comprise a refrigerant circuit that includes a compressor, a heat-source-side heat exchanger, an expansion mechanism, and a user-side heat exchanger in this order.  FIG. 4  illustrates an embodiment of the refrigerant circuit in a refrigerating machine  10 . A refrigerant circuit  11  mainly includes a compressor  12 , a heat-source-side heat exchanger  13 , an expansion mechanism  14 , and a user-side heat exchanger  15 ; and is configured such that these devices  12  to  15  and other devices are sequentially connected. The refrigerant circuit  11  uses the mixture of fluorinated hydrocarbons described above as a refrigerant; the refrigerant circulates in the direction of the solid-line arrow in  FIG. 4 . 
     The compressor  12  is a device that compresses a low-pressure gas refrigerant, and ejects a high-temperature high-pressure gas refrigerant; the compressor  12  is installed in a space outside the machine, or in an outdoor space. The high-pressure gas refrigerant ejected from the compressor  12  is supplied to the heat-source-side heat exchanger  13 . 
     The heat-source-side heat exchanger  13  is a device that condenses (liquefies) the high-temperature high-pressure gas refrigerant compressed in the compressor  12 ; and is installed in a space outside the machine, or in an outdoor space. The high-pressure liquid refrigerant ejected from the heat-source-side heat exchanger  13  passes through the expansion mechanism  14 . 
     The expansion mechanism  14  is a device that depressurizes the high-pressure liquid refrigerant that released heat in the heat-source-side heat exchanger  13  to a low pressure in a refrigeration cycle; and is installed in a space inside the machine, or in an indoor space. The expansion mechanism  14  for use may be, for example, an electronic expansion valve; and is preferably a thermostatic expansion valve, as illustrated in  FIG. 5 . A thermostatic expansion valve used as the expansion mechanism  14  enables the detection of the refrigerant temperature after the user-side heat exchanger  15  by a thermostatic cylinder directly connected to the expansion valve, and controls the aperture of the expansion valve based on the detected refrigerant temperature. Thus, for example, when the user-side heat exchanger  15 , an expansion valve, and a thermostatic cylinder are provided inside the user-side unit, control of the expansion valve is completed inside the user-side unit. This eliminates the need for communications in regards to the expansion valve between the heat-source-side unit provided with the heat-source-side heat exchanger  13  and the user-side unit, leading to low costs and reduced work. Note that when a thermostatic expansion valve is used as the expansion mechanism  14 , an electromagnetic valve  17  is provided to the expansion mechanism  14  on the heat-source-side heat exchanger  13  side. The low-pressure liquid refrigerant that has passed through the expansion mechanism  14  is supplied to the user-side heat exchanger  15 . 
     The user-side heat exchanger  15  is a device that evaporates (vaporizes) the low-pressure liquid refrigerant; and is installed in a space inside the machine, or in an indoor space. The low-pressure gas refrigerant ejected from the user-side heat exchanger  15  is supplied to the compressor  12 , and recirculates the refrigerant circuit  11 . 
     In the refrigerating machine, the heat-source-side heat exchanger  13  functions as a condenser, and the user-side heat exchanger  15  functions as an evaporator. 
     In the refrigerating machine (A), two heat exchangers (heat-source-side heat exchanger  13  and user-side heat exchanger  15 ) are of a countercurrent heat exchanger. In  FIGS. 4 and 5 , and  FIGS. 6 to 11 , which are explained below, the heat-source-side heat exchanger  13  is configured as a heat exchanger using water as an external heat medium (e.g., a double-pipe heat exchanger), and the user-side heat exchanger  15  is configured as a heat exchanger using air as an external heat medium (e.g., a finned tube heat exchanger); however, exchangers  13  and  15  are not limited to these exchangers. The heat-source-side heat exchanger  13  may be configured as a heat exchanger using air as an external heat medium, and the user-side heat exchanger  15  may be configured as a heat exchanger using water as an external heat medium. Alternatively, the heat-source-side heat exchanger  13  and the user-side heat exchanger  15  may both be configured as a heat exchanger using air as an external heat medium, or as a heat exchanger using water as an external heat medium. 
     In the refrigerating machine (B), the evaporating temperature of the refrigerant is 0° C. or below when the user-side heat exchanger  15  functions as an evaporator. In the refrigerating machine (B), the heat-source-side heat exchanger  13  and the user-side heat exchanger  15  do not have to be of countercurrent type. 
     In the refrigerating machine  10  configured as described above, the refrigerant circuit  11 , as illustrated in  FIG. 6 , may have a plurality of expansion mechanisms  14  and a plurality of user-side heat exchangers  15  (two for each in  FIG. 6 ) arranged in parallel. 
     In the refrigerating machine  10  configured as described above, the refrigerant circuit  11 , as illustrated in  FIG. 7 , may further comprise a four-way switching valve  18  that switches the flow of the high-temperature high-pressure gas refrigerant compressed by the compressor  12  toward either the heat-source-side heat exchanger  13  or the user-side heat exchanger  15 . The four-way switching valve  18  can switch the operation between the normal-cycle operation, in which the heat-source-side heat exchanger  13  functions as a radiator, while the user-side heat exchanger  15  functions as an evaporator (the direction of the solid-line arrow); and the reverse-cycle operation, in which the heat-source-side heat exchanger  13  functions as an evaporator, while the user-side heat exchanger  15  functions as a radiator (the direction of the dashed-line arrow). 
     In the refrigerating machine  10  configured as described above, when the evaporating temperature of the refrigerant in the user-side heat exchanger  15  (evaporator) reaches 0° C. or below, the user-side heat exchanger  15  (evaporator) may undergo frost formation. Frost formation decreases the heat-exchange efficiency of the user-side heat exchanger  15  (evaporator), increasing the power consumption and/or decreasing the cooling capacity. Thus, it is preferable to remove frost adhered to the user-side heat exchanger  15  (evaporator) by performing a defrosting operation (defrost) under predetermined conditions. 
     The defrosting operation (defrost) may be off-cycle defrost performed by, as illustrated in  FIG. 8 , stopping the operation of the compressor  12 , and then activating a fan  16  without flowing the refrigerant to the user-side heat exchanger  15 . The off-cycle defrost sends an external heat medium to the user-side heat exchanger  15  by the fan  16  to defrost the user-side heat exchanger  15 . The user-side heat exchanger  15  configured with a heat exchanger that uses water as an external heat medium is provided with the fan  16 . 
     The defrosting operation (defrost) may be heating defrost performed by, as illustrated in  FIG. 9 , further adding a heating means  19  for heating the user-side heat exchanger  15  to the refrigerating machine  10 , and activating the heating means  19 . The heating defrost heats the user-side heat exchanger  15  by the heating means  19  to melt the frost adhered to the user-side heat exchanger  15 , thereby defrosting the user-side heat exchanger  15 . Examples of the heating means  19  for use include electric heaters. 
     The defrosting operation (defrost) may be reverse-cycle hot-gas defrost performed by, as illustrated in  FIG. 10 , activating the reverse-cycle operation described above. Activating the reverse-cycle operation supplies the high-temperature high-pressure gas refrigerant compressed by the compressor  12  to the user-side heat exchanger  15  to melt the frost adhered to the user-side heat exchanger  15 , thereby defrosting the user-side heat exchanger  15 . 
     The defrosting operation (defrost) may be normal-cycle hot-gas defrost as illustrated in  FIG. 11 . In  FIG. 11 , the refrigerant circuit  11  is provided with a bypass flow path  20  that is connected to the discharge side of the compressor  12  at one end, and to the inlet side of the user-side heat exchanger  15  at the other end. The normal-cycle hot-gas defrost opens a bypass valve  21 , while circulating the refrigerant, to directly supply the high-temperature high-pressure gas refrigerant compressed by the compressor  12  to the user-side heat exchanger  15  through the bypass flow path  20 . This melts the frost adhered to the user-side heat exchanger  15 , thereby defrosting the user-side heat exchanger  15 . The high-temperature high-pressure gas refrigerant compressed by the compressor  12  may be bypassed after being depressurized through an expansion mechanism  14  at the inlet side of the user-side heat exchanger  15 . 
     The predetermined conditions under which the defrosting operation (defrost) is performed may be configured such that, for example, a temperature sensor (not shown) detects the inflow refrigerant temperature at the user-side heat exchanger  15  and outside air temperature, and, for example, a control unit determines whether frost is formed in the user-side heat exchanger  15  based on these temperatures; and performs the defrosting operation (defrost) triggered by the determination that frost has been formed. 
     4. Method for Operating Refrigerating Machine 
     The method for operating the refrigerating machine according to the present disclosure is a method for operating the refrigerating machine (A) or (B) using the refrigerant according to the present disclosure. 
     Specifically, the method for operating the refrigerating machine according to the present disclosure comprises circulating the refrigerant according to the present disclosure in the refrigerating machine (A) or (B). 
     When the refrigerating machine has the following structure, the method for operating the refrigerating machine according to the present disclosure may comprise switching the operation between the normal-cycle operation and the reverse-cycle operation by the four-way switching valve described below: 
     A refrigerating machine comprising a refrigerant circuit that includes a compressor, a heat-source-side heat exchanger, an expansion mechanism, and a user-side heat exchanger in this order, 
     the refrigerant circuit including a four-way switching valve that switches the flow of a refrigerant compressed by the compressor toward either the heat-source-side heat exchanger or the user-side heat exchanger, 
     the four-way switching valve capable of switching an operation between a normal-cycle operation in which the heat-source-side heat exchanger functions as a radiator while the user-side heat exchanger functions as an evaporator, and a reverse-cycle operation in which the heat-source-side heat exchanger functions as an evaporator while the user-side heat exchanger functions as a radiator. 
     Additionally, the method for operating the refrigerating machine according to the present disclosure may further comprise performing reverse-cycle hot-gas defrost by the reverse-cycle operation. 
     When the refrigerating machine has the following structure, the method for operating the refrigerating machine according to the present disclosure may comprise performing off-cycle defrost by stopping the operation of the compressor described below, and operating the user-side fan described below: 
     A refrigerating machine comprising a refrigerant circuit that includes a compressor, a heat-source-side heat exchanger, an expansion mechanism, and a user-side heat exchanger in this order, 
     the user-side heat exchanger being provided with a user-side fan. 
     When the refrigerating machine has the following structure, the method for operating the refrigerating machine according to the present disclosure may comprise performing heating defrost by heating the user-side heat exchanger with the heating means described below: 
     A refrigerating machine comprising a refrigerant circuit that includes a compressor, a heat-source-side heat exchanger, an expansion mechanism, and a user-side heat exchanger in this order; and further comprising a heating means for heating the user-side heat exchanger. 
     When the refrigerating machine has the following structure, the method for operating the refrigerating machine according to the present disclosure may comprise performing normal-cycle hot-gas defrost by supplying a refrigerant compressed by the compressor to the user-side heat exchanger through the bypass flow path: 
     A refrigerating machine comprising a refrigerant circuit that includes a bypass flow path that is connected to the discharge side of the compressor at one end, and to the inlet side of the user-side heat exchanger at the other end. 
     EXAMPLES 
     Below, the present disclosure is described in more detail with reference to Examples. However, the present disclosure is not limited to the Examples. 
     The following describes a method for identifying an ASHRAE non-flammability limit region in a ternary composition diagram in which when the concentration of CO 2  is 6.0 mass % based on the sum of the concentration of CO 2 , R32, 8125, and R134a taken as 100 mass %, the sum of the concentration of R32, R125, and R134a is 94.0 mass %. 
     To identify the ASHRAE non-flammability limit in a ternary composition diagram, first, the non-flammability limit of a binary mixed refrigerant of a flammable refrigerant (R32) and a non-flammable refrigerant (CO 2 , R134a, and R125) must be determined. In Experiment Example 1, the non-flammability limit of the binary mixed refrigerant was determined. 
     Experiment Example 1 (Non-Flammability Limit of a Binary Mixed Refrigerant Composed of a Flammable Refrigerant (R32) and a Non-Flammable Refrigerant (CO 2 , R134a, R125)) 
     The non-flammability limit of a binary mixed refrigerant was determined with the measurement device and measurement method of the combustion test according to ASTM E681-2009. 
     Specifically, in order to conduct visual observation and video recording of the state of combustion, the spherical glass flask (inner volume: 12 liters) illustrated in  FIG. 1  was used. The upper lid of the glass flask was set to release gas when excessive pressure is applied on the glass flask by combustion. The ignition was initiated by discharge from electrodes held at a height one-third from the bottom. The test conditions are as described below. 
     Test Conditions 
     Test Vessel: 280 mm in diameter, spherical (inner volume: 12 liters) 
     Test Temperature: 60° C.±3° C. 
     Pressure: 101.3 kPa±0.7 kPa
 
Water Content: 0.0088 g±0.0005 g per g of dry air
 
     Mixture Ratio of Binary Refrigerant Composition/Air: per vol %±0.2 vol % 
     Mixing of Binary Refrigerant Composition: ±0.1 mass %
 
Ignition Method: AC discharge, voltage 15 kV, current 30 mA, neon transformer
 
Electrode Interval: 6.4 mm (¼ inch)
 
Spark: 0.4 seconds±0.05 seconds
 
     Determination Criteria: 
     
         
         
           
             In the case in which a flame propagates at a frame angle of 90° or more from around the ignition point=combustion (propagation) 
             In the case in which a flame propagates at a frame angle of less than 90° from around the ignition point=no flame propagation (non-flammable) 
           
         
       
    
     As a result, the mixed refrigerant of a flammable refrigerant R32 and a non-flammable refrigerant R134a exhibited no flame propagation from the point at which R32=43.0 mass®, and R134a=57.0 mass %. This formulation was determined to be a non-flammability limit. Additionally, flame propagation was not observed in a flammable refrigerant R32 and a non-flammable refrigerant R125 from the point at which R32=63.0 mass %, and R125=37.0 mass %; and in a flammable refrigerant R32 and a non-flammable refrigerant CO 2  from the point at which R32=40.0 mass %, and CO 2 =60.0 mass %. These formulations were determined to be non-flammability limits. Table 1 illustrates a summary of the results. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Flammable 
                 Non-Flammable 
               
               
                 Item 
                 Refrigerant 
                 Refrigerant 
               
               
                   
               
             
            
               
                 Combination of Binary Mixed 
                 R32 
                 R134a 
               
               
                 Refrigerant 
                   
                   
               
               
                 Non-Flammability Limit (mass %) 
                 43.0 
                 57.0 
               
               
                 Combination of Binary Mixed 
                 R32 
                 R125 
               
               
                 Refrigerant 
                   
                   
               
               
                 Non-Flammability Limit (mass %) 
                 63.0 
                 37.0 
               
               
                 Combination of Binary Mixed 
                 R32 
                 CO 2   
               
               
                 Refrigerant 
                   
                   
               
               
                 Non-Flammability Limit (mass %) 
                 40.0 
                 60.0 
               
               
                   
               
            
           
         
       
     
     Experiment Example 2 (ASHRAE Non-Flammability Limit when CO 2 =6.0 Mass %) 
     Subsequently, the ASHRAE non-flammability limit when CO 2 =6.0 mass % was determined based on the non-flammability limit of the binary mixed refrigerant determined in Experiment Example 1 by calculation as described below. 
     1) When CO 2 =6.0 Mass %, and R134a=0 Mass % 
     A WCFF formulation for a mixed formulation close to the ASHRAE non-flammability limit was determined by simulating leakage during storage, transport, and use based on the ANSI/ASHRAE34-2013 using the NIST (The National Institute of Standard and Technology) leak and recharge simulation program for refrigerant version 4.0 (REFLEAK 4.0), and calculating it from a leakage simulation at +10° C. or −40° C. from a boiling point during storage, in which combustion is most likely to occur. 
     Table 2 illustrates the results. Whether the calculated WCFF formulation is a non-flammability-limit formulation was investigated in accordance with the following procedure. 
     A converted non-flammable refrigerant concentration of R32 was determined using the following formula. 
       The converted non-flammable refrigerant concentration of R32=the concentration of R125×(63/37)+the concentration of R134a×(43/57)+the concentration of CO 2 ×(40/60)
 
     The release rate at which the value of (the converted non-flammable refrigerant formulation of R32—the refrigerant formulation of R32) is the minimum value indicates the WCFF formulation at its initial value. The initial value at which the value of (the converted non-flammable refrigerant formulation of R32—the refrigerant formulation of R32) was the positive minimum value was determined to be the calculated ASHRAE non-flammability-limit formulation when R134a=0 mass %. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 59.2 
                 34.8 
                 0.0 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Non-Flammability - 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Flammability 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass %% 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0.0 
                 49.68 
                 25.92 
                 0.00 
                 24.40 
                 60.40 
                 10.71 
               
               
                 10.0 
                 53.34 
                 28.45 
                 0.00 
                 18.21 
                 60.58 
                 7.24 
               
               
                 20.0 
                 56.64 
                 30.83 
                 0.00 
                 12.53 
                 60.86 
                 4.22 
               
               
                 30.0 
                 59.29 
                 32.90 
                 0.00 
                 7.81 
                 61.22 
                 1.93 
               
               
                 40.0 
                 61.15 
                 34.53 
                 0.00 
                 4.32 
                 61.68 
                 0.53 
               
               
                 50.0 
                 62.20 
                 35.75 
                 0.00 
                 2.05 
                 62.23 
                 0.03 
                 WCFF 
               
               
                 60.0 
                 62.56 
                 36.64 
                 0.00 
                 0.80 
                 62.92 
                 0.35 
               
               
                 70.0 
                 62.39 
                 37.39 
                 0.00 
                 0.23 
                 63.81 
                 1.43 
               
               
                 80.0 
                 61.73 
                 38.23 
                 0.00 
                 0.04 
                 65.12 
                 3.39 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 59.3 
                 34.7 
                 0.0 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Non-Flammability - 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Flammability 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0.0 
                 49.63 
                 25.76 
                 0.00 
                 24.60 
                 60.27 
                 10.64 
               
               
                 10.0 
                 53.32 
                 28.30 
                 0.00 
                 18.38 
                 60.44 
                 7.12 
               
               
                 20.0 
                 56.64 
                 30.69 
                 0.00 
                 12.67 
                 60.70 
                 4.06 
               
               
                 30.0 
                 59.33 
                 32.77 
                 0.00 
                 7.90 
                 61.06 
                 1.73 
               
               
                 40.0 
                 61.22 
                 34.41 
                 0.00 
                 4.37 
                 61.51 
                 0.29 
               
               
                 50.0 
                 62.29 
                 35.63 
                 0.00 
                 2.08 
                 62.05 
                 −0.24 
                 WCFF 
               
               
                 60.0 
                 62.67 
                 36.53 
                 0.00 
                 0.81 
                 62.73 
                 0.06 
               
               
                 70.0 
                 62.50 
                 37.27 
                 0.00 
                 0.23 
                 63.62 
                 1.12 
               
               
                 80.0 
                 61.85 
                 38.11 
                 0.00 
                 0.04 
                 64.92 
                 3.07 
               
               
                   
               
            
           
         
       
     
     2) When CO 2 =6.0 Mass %, and R134a=25.0 Mass % 
     An ASHRAE non-flammability-limit formulation was determined with R32+R125=69.0 mass %, in the same procedure as described above. Table 3 illustrates the results. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
             
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 46.8 
                 22.2 
                 25.0 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Non-Flammability - 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Flammability 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0.0 
                 44.90 
                 18.92 
                 7.48 
                 28.71 
                 56.99 
                 12.10 
               
               
                 10.0 
                 49.44 
                 21.38 
                 8.86 
                 20.33 
                 56.63 
                 7.20 
               
               
                 20.0 
                 53.34 
                 23.60 
                 10.45 
                 12.60 
                 56.48 
                 3.13 
               
               
                 30.0 
                 55.93 
                 25.25 
                 12.23 
                 6.59 
                 56.61 
                 0.68 
               
               
                 36.0 
                 56.69 
                 25.87 
                 13.39 
                 4.05 
                 56.85 
                 0.17 
                 WCFF 
               
               
                 40.0 
                 56.85 
                 26.13 
                 14.23 
                 2.80 
                 57.09 
                 0.24 
               
               
                 50.0 
                 56.15 
                 26.29 
                 16.66 
                 0.90 
                 57.93 
                 1.78 
               
               
                 60.0 
                 53.99 
                 25.86 
                 19.96 
                 0.20 
                 59.21 
                 5.23 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 46.9 
                 22.1 
                 25.0 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Non-Flammability - 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Flammability 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0.0 
                 44.98 
                 18.83 
                 7.48 
                 28.71 
                 56.85 
                 11.87 
               
               
                 10.0 
                 49.53 
                 21.28 
                 8.85 
                 20.33 
                 56.47 
                 6.94 
               
               
                 20.0 
                 53.45 
                 23.50 
                 10.45 
                 12.60 
                 56.30 
                 2.85 
               
               
                 30.0 
                 56.04 
                 25.14 
                 12.22 
                 6.59 
                 56.42 
                 0.38 
               
               
                 36.0 
                 56.80 
                 25.76 
                 13.39 
                 4.05 
                 56.66 
                 −0.14 
                 WCFF 
               
               
                 40.0 
                 56.96 
                 26.01 
                 14.23 
                 2.79 
                 56.89 
                 −0.08 
               
               
                 50.0 
                 56.27 
                 26.17 
                 16.66 
                 0.90 
                 57.73 
                 1.46 
               
               
                 60.0 
                 54.10 
                 25.74 
                 19.96 
                 0.20 
                 59.01 
                 4.91 
               
               
                   
               
            
           
         
       
     
     3) When CO 2 =6.0 Mass %, and R134a=50.0 Mass % 
     An ASHRAE non-flammability-limit formulation was determined with R32+R125=44 mass %, in the same procedure as described above. Table 4 illustrates the results. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
             
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 34.2 
                 9.8 
                 50.0 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Non-Flammability - 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Flammability 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0 
                 38.37 
                 9.71 
                 17.29 
                 34.63 
                 52.66 
                 14.29 
               
               
                 10 
                 44.09 
                 11.50 
                 21.64 
                 22.76 
                 51.09 
                 7.00 
               
               
                 20 
                 48.58 
                 13.00 
                 26.68 
                 11.73 
                 50.09 
                 1.52 
               
               
                 30 
                 50.06 
                 13.63 
                 30.83 
                 5.48 
                 50.12 
                 0.05 
                 WCFF 
               
               
                 36 
                 50.09 
                 13.69 
                 31.85 
                 4.37 
                 50.26 
                 0.17 
               
               
                 40 
                 48.32 
                 13.49 
                 37.09 
                 1.10 
                 51.68 
                 3.35 
               
               
                 50 
                 44.05 
                 12.63 
                 43.16 
                 0.16 
                 54.17 
                 10.13 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 34.3 
                 9.7 
                 50.0 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Non-Flammability - 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Flammability 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0 
                 38.47 
                 9.61 
                 17.28 
                 34.63 
                 52.50 
                 14.03 
               
               
                 10 
                 44.21 
                 11.39 
                 21.64 
                 22.77 
                 50.89 
                 6.68 
               
               
                 20 
                 48.71 
                 12.87 
                 26.68 
                 11.73 
                 49.87 
                 1.16 
               
               
                 30 
                 50.20 
                 13.49 
                 30.83 
                 5.48 
                 49.88 
                 −0.32 
                 WCFF 
               
               
                 36 
                 50.23 
                 13.55 
                 31.85 
                 4.36 
                 50.02 
                 −0.21 
               
               
                 40 
                 48.46 
                 13.35 
                 37.09 
                 1.09 
                 51.44 
                 2.98 
               
               
                 50 
                 44.18 
                 12.50 
                 43.15 
                 0.16 
                 53.95 
                 9.77 
               
               
                   
               
            
           
         
       
     
     When 4) CO 2 =6.0 Mass %, and R125=0 Mass % 
     An ASHRAE non-flammability-limit formulation was determined under these conditions in the same procedure as described above. Table 5 illustrates the results. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 5 
               
               
                   
                   
               
             
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 24.5 
                 0.0 
                 69.5 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Converted 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Non-Flammability - R32 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0.0 
                 31.89 
                 0.00 
                 28.15 
                 39.96 
                 47.88 
                 15.99 
               
               
                 10.0 
                 38.25 
                 0.00 
                 37.31 
                 24.44 
                 44.44 
                 6.19 
               
               
                 20.0 
                 42.38 
                 0.00 
                 47.63 
                 9.99 
                 42.59 
                 0.21 
               
               
                 22.0 
                 42.60 
                 0.00 
                 49.55 
                 7.85 
                 42.61 
                 0.01 
                 WCFF 
               
               
                 30.0 
                 41.31 
                 0.00 
                 56.31 
                 2.38 
                 44.07 
                 2.76 
               
               
                 40.0 
                 36.21 
                 0.00 
                 63.48 
                 0.31 
                 48.09 
                 11.89 
               
               
                 50.0 
                 29.11 
                 0.00 
                 70.87 
                 0.02 
                 53.48 
                 24.37 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Item 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 R32 
                 R125 
                 R134a 
                 CO 2   
               
               
                   
                   
                 mass % 
                 mass % 
                 mass % 
                 mass % 
               
               
                   
                   
               
               
                   
                 Initial 
                 24.6 
                 0.0 
                 69.4 
                 6.0 
               
               
                   
                 Value 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Converted 
                   
                   
               
               
                   
                   
                   
                   
                   
                 Non-Flammable 
               
               
                   
                   
                   
                   
                   
                 Refrigerant 
                 Non-Flammability - 
               
               
                   
                   
                   
                   
                   
                 Concentration of 
                 Flammability 
               
               
                 Release 
                 R32 
                 R125 
                 R134a 
                 CO 2   
                 R32 
                 (Non-Flammability 
               
               
                 Rate % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 mass % 
                 (Positive)) 
                 Note 
               
               
                   
               
               
                 0.0 
                 31.99 
                 0.00 
                 28.09 
                 39.92 
                 47.81 
                 15.82 
               
               
                 10.0 
                 38.35 
                 0.00 
                 37.22 
                 24.43 
                 44.36 
                 6.01 
               
               
                 20.0 
                 42.50 
                 0.00 
                 47.49 
                 10.01 
                 42.50 
                 0.01 
               
               
                 22.0 
                 42.72 
                 0.00 
                 49.41 
                 7.87 
                 42.52 
                 −0.20 
                 WCFF 
               
               
                 30.0 
                 41.45 
                 0.00 
                 56.16 
                 2.40 
                 43.96 
                 2.52 
               
               
                 40.0 
                 36.36 
                 0.00 
                 63.32 
                 0.32 
                 47.98 
                 11.62 
               
               
                 50.0 
                 29.26 
                 0.00 
                 70.72 
                 0.02 
                 53.36 
                 24.10 
               
               
                   
               
            
           
         
       
     
     The four points determined by examining the calculated ASHRAE non-flammability-limit formulations above are shown in the ternary composition diagram of  FIG. 12 . Because the non-flammability border point at which R134a=25 mass % and the non-flammability border point at which R134a=50 mass % are on the line that connects point C at which R134a=0 mass % and point D at which R125=0 mass %, line segment CD is considered to be a calculated ASHRAE non-flammability border line below. 
     Experiment Example 3 (Verification of Calculated Non-Flammability Limit Obtained in Experiment Example 2 by Combustion Test) 
     A combustion test was performed in accordance with the ASTM E681 described in Experiment Example 1 with the WCFF formulation (R32/R125/R134a/CO 2 )=(62.2/35.8/0/0/2.0) for the formulation (R32/R125/R134a/CO 2 )=(9.2/34.8/0/6.0), and the WCFF formulation (R32/R125/R134a/CO 2 )·(50.1/13.6/30.8/5.5) for the formulation (R32/R125/R134a/CO 2 )=(34.2/9.8/50.0/6.0) as typical examples. In these WCFF formulations, flame propagation was not observed. 
     Thus, the ASHRAE non-flammability limit calculated in Experiment Example 2 on the basis of the non-flammability limit of a binary composition determined in Experiment Example 1 satisfies the ASHRAE non-flammability requirement based on the ANSI/ASHRAE Standard 34-2013. 
     The ASHRAE non-flammability limits shown in  FIGS. 13 to 25  were also determined in the same manner as for the ASHRAE non-flammability limit when CO 2 =6.0 mass %. 
     It is preferable to further consider safety factors in the ASHRAE non-flammability limits determined by calculation as described above, taking into consideration the purity of individual refrigerants during the production process and/or a margin of error during the mixing process. The ASHRAE non-flammability limit line CD was shifted in parallel so that the non-flammable refrigerant R125 was increased by 3.5 mass %. The resulting line segment C′D′ was determined to be the ASHRAE non-flammability limit line that takes safety factors into account. 
     When R32=x mass % and R125=y mass %, for example, line segment CD that connects point C (R32/R125/R134a/CO 2 )·(59.2/34.8/0/6.0) and point D (R32/R125/R134a/CO 2 )·(24.6/0/69.4/6.0) is indicated by y=1.0029x−24.571. Thus, this ASHRAE non-flammability line C′D′ that takes safety factors into account is indicated by y=1.0029x−21.071. 
     Regarding the compositional ratio of CO 2 , R32, 8125, and R134a contained in the mixture, when the concentration of CO 2  is x mass %, the sum of the concentration of R32, R125, and R134a is (100−x) mass %. The compositional ratio of CO 2 , R32, R125, and R134a contained in the mixture can be indicated as a coordinate point in a ternary composition diagram in which the sum of the concentration of R32, R125, and R134a is (100−x). The following explains how to determine a specific coordinate point. The ASHRAE non-flammability limits that take safety factors into account (+3.5%) shown in  FIGS. 13 to 25  were also determined together. 
     The description below is based on different ranges of x. The meaning of points A, B, C, D, E, F, G, C′, D′, E′, G′, H, I, J, K, L, and M is as described below. The concentration of each point was determined in the Examples below, and the value is shown. 
     A: A compositional ratio when GWP is 1500, and the concentration of R134a (mass %) is 0 mass %.
 
B: A compositional ratio when GWP is 1500, and the concentration of R32 (mass %) is 0 mass %
 
C: A compositional ratio on the ASHRAE non-flammability border line, and when the concentration of R134a (mass %) is 0 mass %.
 
D: A compositional ratio on the ASHRAE non-flammability border line, and when the concentration of R125 (mass %) is 0 mass %.
 
E: A point of intersection between line segment AB and line segment CD
 
F: A compositional ratio when GWP is 1500, and the refrigerating capacity relative to that of R410A is 90%.
 
G: A compositional ratio on the ASHRAE non-flammability border line, and when the refrigerating capacity relative to that of R410A is 90%.
 
C′: A compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the concentration of R134a (mass %) is 0 mass %.
 
D′: A compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the concentration of R125 (mass %) is 0 mass %.
 
E′: A point of intersection between line segment AB and line segment C′D′.
 
G′: A compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the refrigerating capacity relative to that of R410A is 90%.
 
H: A compositional ratio when GWP is 1500, and the refrigerating capacity relative to that of R410A is 95%.
 
I: A compositional ratio on the ASHRAE non-flammability border line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as safety factor, and when the refrigerating capacity relative to that of R410A is 95%.
 
J: A compositional ratio when GWP is 1500, and the pressure at the compressor outlet relative to that of R410A is 102.5%.
 
K: A compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the pressure at the compressor outlet relative to that of R410A is 102.5%.
 
L: A compositional ratio when GWP is 1500, and when the pressure at the compressor outlet relative to that of R410A is 100%.
 
M: A compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the pressure at the compressor outlet relative to that of R410A is 100%.
 
     (1) How to Determine Points E, F, G, E′, G′, H, I, J, K, L, and M 
     (1-1) Point E 
     When 6.0 Mass %≤x≤2.7 Mass % 
     When the concentration of CO 2  is 2.7 mass %, point E on a ternary composition diagram in which the sum of the concentration of R32, R125, and 134a is (100−x) mass % is (the concentration of R32 (mass %)/the concentration of R125 (mass %)/the concentration of 134a (mass %))=(46.3/22.1/28.9). 
     When the concentration of R32 is 4.0 mass %, point E on a ternary composition diagram in which the sum of the concentration of R32, R125, and 134a is (100−x) mass % is (the concentration of R32 (mass %)/the concentration of R125 (mass %)/the concentration of 134a (mass %))=(48.0/23.6/24.4). 
     When the concentration of R32 is 6.0 mass %, point E on a ternary composition diagram in which the sum of the concentration of R32, R125, and 134a is (100−x) mass % is (the concentration of R32 (mass %)/the concentration of R125 (mass %)/the concentration of 134a (mass %))=(50.1/25.8/18.1). 
     Thus, when the sum of the concentration of CO 2 , R32, R125, and 134a is 100 mass %, and the concentration of R32 is y mass %, the formula of the regression line determined from these three points plotted on xy coordinates is expressed as y=−0.0781x 2 +1.8309x+41.926. 
     When the concentration of R125 is z mass %, the formula of the regression line determined from these three points plotted on xy coordinates is expressed as z=1.1194x+19.094. 
     Additionally, the concentration of R134a at point E is expressed by (100−the concentration of R32 (mass %)−the concentration of 8125 (mass %)−the concentration of CO 2  (mass %)). 
     As described above, point E (the concentration of R32 (mass %)/the concentration of R125 (mass %)/the concentration of 134a (mass %)) on a ternary composition diagram in which the sum of the concentration of R125, 8125, and R134a is (100−x) is expressed by (−0.0781x+1.8309x+41.926/1.1194x+19.094/100−the concentration of CO 2 −the concentration of R32−the concentration of R125). 
     The same calculation was also performed for the case in which 9.0 mass %≤x≤6.0 mass %. The table below illustrates (the concentration of R32 (mass %)/the concentration of R125 (mass %)/the concentration of 134a (mass %)) according to each concentration range. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Point E 
               
            
           
           
               
               
            
               
                   
                 Item 
               
            
           
           
               
               
               
            
               
                   
                 6.0 ≥ x ≥ 2.7 
                 9.0 ≥ x ≥ 6.0 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 CO 2   
                 2.7 
                 4 
                 6 
                 6 
                 8 
                 9 
               
               
                 R32 
                 46.3 
                 48 
                 50.1 
                 50.1 
                 52.1 
                 53.1 
               
               
                 R125 
                 22.1 
                 23.6 
                 25.3 
                 25.8 
                 27.9 
                 28.9 
               
               
                 R134a 
                 28.9 
                 24.4 
                 18.1 
                 18.1 
                 12 
                 9 
               
            
           
           
               
               
               
            
               
                 CO 2   
                 x 
                 x 
               
               
                 Approximation 
                 −0.0781x2 + 1.8309x + 41.926 
                 x + 44.1 
               
               
                 Formula R32 
               
               
                 Approximation 
                 1.1194x + 19.094 
                 1.0357x + 19.593 
               
               
                 Formula R125 
               
               
                 Approximation 
                 100 − R32 − R125 − CO 2   
                 100 − R32 − R125 − CO 2   
               
               
                 Formula R134a 
               
               
                   
               
            
           
         
       
     
     (1-2) Point F 
     The approximation formulas were determined in the same manner as above, and Table 7 illustrates the results. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Point F 
               
            
           
           
               
               
               
            
               
                 Item 
                 6.0 ≥ x ≥ 2.7 
                 9.0 ≥ x ≥ 6.0 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 CO 2   
                 2.7 
                 4 
                 6 
                 6 
                 8 
                 9 
               
               
                 R32 
                 46.3 
                 42.4 
                 36.4 
                 36.4 
                 30.4 
                 27.4 
               
               
                 R125 
                 22.1 
                 21.6 
                 20.8 
                 20.8 
                 20 
                 19.6 
               
               
                 R134a 
                 28.9 
                 32 
                 36.8 
                 36.8 
                 41.6 
                 44 
               
            
           
           
               
               
               
            
               
                 CO 2   
                 x 
                 x 
               
               
                 Approximation 
                 −3x + 54.4 
                 −3x + 54.4 
               
               
                 Formula R32 
               
               
                 Approximation 
                 −0.3945x + 23.17    
                 −0.4x + 23.2   
               
               
                 Formula R125 
               
               
                 Approximation 
                 100-R32-R125-CO 2   
                 100-R32-R125-CO 2   
               
               
                 Formula R134a 
               
               
                   
               
            
           
         
       
     
     (1-2) Points G, E′, H, J, and L 
     The approximation formulas were determined in the same manner as above, and Tables 8 to 12 illustrate the results. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Point G 
               
            
           
           
               
               
               
            
               
                 Item 
                 6.0 ≥ x ≥ 2.7 
                 9.0 ≥ x ≥ 6.0 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 CO 2   
                 2.7 
                 4 
                 6 
                 6 
                 8 
                 9 
               
               
                 R32 
                 46.3 
                 43.6 
                 39.5 
                 39.5 
                 35.2 
                 33 
               
               
                 R125 
                 22.1 
                 19.3 
                 15 
                 15 
                 10.8 
                 8.7 
               
               
                 R134a 
                 28.9 
                 33.1 
                 39.5 
                 39.5 
                 46 
                 49.3 
               
            
           
           
               
               
               
            
               
                 CO 2   
                 x 
                 x 
               
               
                 Approximation 
                 −2.0597x + 51.853 
                 −2.1643x + 52.493  
               
               
                 Formula R32 
               
               
                 Approximate on 
                 −2.1514x + 27.908 
                 −2.1x + 27.6 
               
               
                 Formula R125 
               
               
                 Approximation 
                 100-R32-R125-CO 2   
                 100-R32-R125-CO 2   
               
               
                 Formula R134a 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Point E′ 
                 Point G′ 
               
            
           
           
               
               
               
               
            
               
                 Item 
                 6.1 ≥ x ≥ 4.0 
                 Item 
                 6.1 ≥ x ≥ 4.0 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 CO 2   
                 4 
                 5 
                 6.1 
                 CO 2   
                 4 
                 5 
                 6.1 
               
               
                 R32 
                 42.6 
                 43.6 
                 44.7 
                 R32 
                 42.6 
                 40.4 
                 38 
               
               
                 R125 
                 21.6 
                 22.7 
                 23.8 
                 R125 
                 21.6 
                 19.4 
                 17.1 
               
               
                 R134a 
                 31.8 
                 28.7 
                 25.5 
                 R134a 
                 31.8 
                 35.2 
                 38.8 
               
            
           
           
               
               
               
               
            
               
                 CO 2   
                 x 
                 CO 2   
                 x 
               
               
                 Approximation 
                 x + 38.6 
                 Approximation 
                 −2.1903x + 51.358 
               
               
                 Formula for 
                   
                 Formula for 
               
               
                 R32 
                   
                 R32 
               
               
                 Approximation 
                 1.0468x + 17.431    
                 Approximation 
                  −2.142x + 30.148 
               
               
                 Formula for 
                   
                 Formula for 
               
               
                 R125 
                   
                 R125 
               
               
                 Approximation 
                 100-R32-R125-CO 2   
                 Approximate on 
                 100-R32-R125-CO 2   
               
               
                 Formula for 
                   
                 Formula for 
               
               
                 R134a 
                   
                 R134a 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                 Point H 
                 Point I 
               
            
           
           
               
               
               
               
            
               
                 Item 
                 9.0 ≥ x ≥ 6.7 
                 Item 
                 9.0 ≥ x ≥ 6.7 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 CO 2   
                 6.7 
                 8 
                 9 
                 CO 2   
                 6.7 
                 8 
                 9 
               
               
                 R32 
                 39.8 
                 36 
                 33 
                 R32 
                 41.1 
                 38.4 
                 36.4 
               
               
                 R125 
                 22.5 
                 22 
                 21.6 
                 R125 
                 20.2 
                 17.6 
                 15.6 
               
               
                 R134a 
                 31 
                 34 
                 36.4 
                 R134a 
                 32 
                 36 
                 39 
               
            
           
           
               
               
               
               
            
               
                 CO 2   
                 x 
                 CO 2   
                 x 
               
               
                 Approximation 
                 −2.9549x + 59.61 
                 Approximation 
                 −2.0451x + 54.79    
               
               
                 Formula for 
                   
                 Formula for 
               
               
                 R32 
                   
                 R32 
               
               
                 Approximation 
                  −0.391x + 25.122 
                 Approximation 
                 −2x + 33.6 
               
               
                 Formula for 
                   
                 Formula for 
               
               
                 R125 
                   
                 R125 
               
               
                 Approximation 
                 100-R32-R125-CO 2   
                 Approximation 
                 100-R32-R125-CO 2   
               
               
                 Formula for 
                   
                 Formula for 
               
               
                 R134a 
                   
                 R134a 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 Point J 
                 Point K 
               
            
           
           
               
               
               
               
            
               
                 Item 
                 9.0 ≥ x ≥ 8.0 
                 Item 
                 9.0 ≥ x ≥ 8.0 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 CO 2   
                 8 
                 9 
                 CO 2   
                 8 
                 9 
               
               
                 R32 
                 42.3 
                 41.2 
                 R32 
                 8 
                 9 
               
               
                 R125 
                 24.3 
                 20.4 
                 R125 
                 43.6 
                 42.7 
               
               
                 R134a 
                 25.4 
                 29.4 
                 R134a 
                 22.8 
                 18.5 
               
            
           
           
               
               
               
               
               
            
               
                 CO 2   
                 x 
                 CO 2   
                 25.6 
                 29.8 
               
            
           
           
               
               
               
               
            
               
                 Approximation 
                 −1.1x + 51.1 
                 Approximation 
                 −0.9x + 50.8 
               
               
                 Formula to R32 
                   
                 Formula for R32 
                   
               
               
                 Approximation 
                 −3.9x + 55.5 
                 Approximation 
                 −4.3x + 57.2 
               
               
                 Formula for R125 
                   
                 Formula for R125 
                   
               
               
                 Approximation 
                 100 − R32 − R125 − CO 2   
                 Approximation 
                 100 − R32 − R125 − CO 2   
               
               
                 Formula for 
                   
                 Formula for 
                   
               
               
                 R134a 
                   
                 R134a 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                 TABLE 12 
               
             
            
               
                   
               
               
                 Point L 
                 Point M 
               
            
           
           
               
               
               
               
            
               
                 Item 
                 9.0 ≥ x ≥ 6.7 
                 Item 
                 9.0 ≥ x ≥ 6.7 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 CO 2   
                 6.7 
                 8 
                 9 
                 CO 2   
                 6.7 
                 8 
                 9 
               
               
                 R32 
                 44.1 
                 39.3 
                 39 
                 R32 
                 44.5 
                 41.3 
                 40.5 
               
               
                 R125 
                 24.1 
                 23.2 
                 18.2 
                 R125 
                 23.6 
                 20.5 
                 16.2 
               
               
                 R134a 
                 25.1 
                 29.5 
                 33.8 
                 R134a 
                 25.2 
                 30.2 
                 34.3 
               
            
           
           
               
               
               
               
            
               
                 CO 2   
                 x 
                 CO 2   
                 x 
               
               
                 Approximation 
                 1.4749x2 − 25.374x + 
                 Approximation 
                 0.7224x2 − 13.081x + 
               
               
                 Formula for 
                 147.89 
                 Formula for 
                 99.713 
               
               
                 R32 
                   
                 R32 
               
               
                 Approximation 
                 −1.8729x2 + 26.839x − 
                 Approximation 
                 −0.8328x2 + 9.8572x − 
               
               
                 Formula for 
                 71.649 
                 Formula for 
                 5.0599 
               
               
                 R125 
                   
                 R125 
               
               
                 Approximation 
                 100-R32-R125-CO 2   
                 Approximation 
                 100-R32-R125-CO 2   
               
               
                 Formula for 
                   
                 Formula for 
               
               
                 R134a 
                   
                 R134a 
               
               
                   
               
            
           
         
       
     
     Examples 1 to 34 and Comparative Examples 1 to 36 
     The GWP of the compositions that contain a mixture of R410A, CO 2 , R32, R125, and R134a was evaluated based on the values in the fourth report of the Intergovernmental Panel on Climate Change (IPCC). The refrigerating capacity of the compositions that contain a mixture of R410A, CO 2 , R32, R125, and R134a were determined by performing theoretical calculation of the refrigeration cycle for each mixed refrigerant by using the Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 9.0) of the National Institute of Science and Technology (NIST), under the following conditions. 
     Evaporating Temperature −10° C. 
     Condensation Temperature 40° C. 
     Superheating Temperature 5K 
     Subcooling Temperature 5K 
     Compressor Efficiency 70% 
     The flammability was determined based on the classification of the ASHRAE flammability. 
     Tables 13 to 22 illustrate the GWP, COP, and refrigerating capacity calculated based on these results. The COP and the refrigerating capacity are indicated by their percentage relative to R410A. 
     The coefficient of performance (COP) was calculated using the following formula. 
       COP=(refrigerating capacity or heating capacity)/power consumption. 
     Table 13 illustrates the case in which CO 2  is contained in an amount of 2.7 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 13 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                   
               
               
                   
                   
                 Example 1 
                 Example 2 
                 Example 3 
                 Example 4 
                 Example 5 
                 Example 1 
               
               
                 Item 
                 Unit 
                 R410A 
                 A 
                 B 
                 C 
                 D 
                 E = F = G 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 50.0 
                 67.5 
                 0.0 
                 60.8 
                 24.1 
                 46.3 
               
               
                 R125 
                 mass % 
                 50.0 
                 29.8 
                 5.2 
                 36.5 
                 0.0 
                 22.1 
               
               
                 R134a 
                 mass % 
                 0.0 
                 0.0 
                 92.2 
                 0.0 
                 73.2 
                 28.9 
               
               
                 CO 2   
                 mass % 
                 0.0 
                 2.7 
                 2.7 
                 2.7 
                 2.7 
                 2 
               
               
                 GWP 
                 — 
                 2088 
                 1500 
                 1500 
                 1688 
                 1209 
                 1500 
               
               
                 COP in Comparison 
                 % 
                 100.0 
                 100.2 
                 103.8 
                 99.9 
                 104.2 
                 101.4 
               
               
                   
                 (relative 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 100.0 
                 109.9 
                 48.1 
                 108.4 
                 65.8 
                 90.2 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 100.0 
                 107.1 
                 51.5 
                 106.8 
                 66.7 
                 89.9 
               
               
                 Compressor Outlet 
                 relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Non- 
                 Flammable 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                 flammable 
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 14 illustrates the case in which CO 2  is contained in an amount of 4.0 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 14 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                   
                   
                   
               
               
                   
                   
                 Example 5 
                 Example 6 
                 Example 7 
                 Example 8 
                 Example 2 
                 Example 3 
                 Example 4 
               
               
                 Item 
                 Unit 
                 A 
                 B 
                 C 
                 D 
                 E 
                 F 
                 G 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 65.9 
                 0.0 
                 60.2 
                 24.5 
                 48.0 
                 42.4 
                 43.6 
               
               
                 R125 
                 mass % 
                 30.1 
                 6.1 
                 35.8 
                 0.0 
                 23.6 
                 21.6 
                 19.3 
               
               
                 R134a 
                 mass % 
                 0.0 
                 89.9 
                 0.0 
                 71.5 
                 24.4 
                 32.0 
                 33.1 
               
               
                 CO 2   
                 mass % 
                 4.0 
                 4.0 
                 4.0 
                 4.0 
                 4.0 
                 4.0 
                 4.0 
               
               
                 GWP 
                 — 
                 1500 
                 1500 
                 1659 
                 1188 
                 1500 
                 1500 
                 1443 
               
               
                 COP in Comparison 
                 % 
                 99.8 
                 103.1 
                 99.4 
                 103.6 
                 100.6 
                 101.0 
                 101.2 
               
               
                   
                 (relative 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 112.1 
                 51.4 
                 110.8 
                 69.1 
                 95.2 
                 90.0 
                 90.0 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 109.7 
                 55.6 
                 109.5 
                 70.4 
                 95.1 
                 90.6 
                 90.2 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Flammable 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 15 illustrates the case in which CO 2  is contained in an amount of 6.0 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 15 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                   
                   
                   
               
               
                   
                   
                 Example 9 
                 Example 10 
                 Example 11 
                 Example 12 
                 Example 5 
                 Example 6 
                 Example 7 
               
               
                 Item 
                 Unit 
                 A 
                 B 
                 C 
                 D 
                 E 
                 F 
                 G 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 63.4 
                 0.0 
                 59.2 
                 24.5 
                 50.1 
                 36.4 
                 39.5 
               
               
                 R125 
                 mass % 
                 30.6 
                 7.5 
                 34.8 
                 0.0 
                 25.8 
                 20.8 
                 15.0 
               
               
                 R134a 
                 mass % 
                 0.0 
                 86.5 
                 0.0 
                 69.5 
                 18.1 
                 36.8 
                 39.5 
               
               
                 CO 2   
                 mass % 
                 6.0 
                 6.0 
                 6.0 
                 6.0 
                 6.0 
                 6.0 
                 6.0 
               
               
                 GWP 
                 — 
                 1500 
                 1500 
                 1618 
                 1159 
                 1500 
                 1500 
                 1357 
               
               
                 COP in Comparison 
                 (relative 
                 99.1 
                 102.3 
                 98.8 
                 102.8 
                 99.6 
                 100.6 
                 100.9 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 115.4 
                 56.5 
                 114.4 
                 73.7 
                 102.6 
                 90.0 
                 90.0 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 113.8 
                 61.8 
                 113.7 
                 75.6 
                 102.9 
                 91.6 
                 90.9 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Flammable 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 16 illustrates the case in which CO 2  is contained in an amount of 8.0 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 16 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                   
                   
                   
               
               
                   
                   
                 Example 13 
                 Example 14 
                 Example 15 
                 Example 16 
                 Example 8 
                 Example 9 
                 Example 10 
               
               
                 Item 
                 Unit 
                 A 
                 B 
                 C 
                 D 
                 E 
                 F 
                 G 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 60.9 
                 0.0 
                 58.1 
                 24.3 
                 52.1 
                 30.4 
                 35.2 
               
               
                 R125 
                 mass % 
                 31.1 
                 8.9 
                 33.9 
                 0.0 
                 27.9 
                 20.0 
                 10.8 
               
               
                 R134a 
                 mass % 
                 0.0 
                 83.1 
                 0.0 
                 67.7 
                 12.0 
                 41.6 
                 46.0 
               
               
                 CO 2   
                 mass % 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
               
               
                 GWP 
                 — 
                 1500 
                 1500 
                 1579 
                 1132 
                 1500 
                 1500 
                 1273 
               
               
                 COP in Comparison 
                 % 
                 98.4 
                 101.7 
                 98.2 
                 102.1 
                 98.6 
                 100.1 
                 100.7 
               
               
                   
                 (relative 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 118.7 
                 61.9 
                 118.1 
                 78.3 
                 110.0 
                 90.0 
                 90.0 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 173.8 
                 100.0 
                 173.8 
                 118.9 
                 163.1 
                 136.6 
                 135.1 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Flammable 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 17 illustrates the case in which CO 2  is contained in an amount of 9.0 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 17 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                   
                   
                   
               
               
                   
                   
                 Example 17 
                 Example 18 
                 Example 19 
                 Example 20 
                 Example 11 
                 Example 12 
                 Example 13 
               
               
                 Item 
                 Unit 
                 A 
                 B 
                 C 
                 D 
                 E 
                 F 
                 G 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 59.7 
                 0.0 
                 57.6 
                 24.3 
                 53.1 
                 27.4 
                 33.0 
               
               
                 R125 
                 mass % 
                 31.3 
                 9.6 
                 33.4 
                 0.0 
                 28.9 
                 19.6 
                 8.7 
               
               
                 R134a 
                 mass % 
                 0.0 
                 81.4 
                 0.0 
                 66.7 
                 9.0 
                 44.0 
                 49.3 
               
               
                 CO 2   
                 mass % 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
               
               
                 GWP 
                 — 
                 1500 
                 1500 
                 1558 
                 1118 
                 1500 
                 1500 
                 1232 
               
               
                 COP in Comparison 
                 % 
                 98.0 
                 101.5 
                 97.9 
                 101.8 
                 98.2 
                 100.0 
                 100.7 
               
               
                   
                 (relative 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 120.4 
                 64.6 
                 119.9 
                 80.7 
                 113.8 
                 90.0 
                 90.0 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 120.0 
                 70.8 
                 120.0 
                 83.2 
                 114.5 
                 93.2 
                 92.0 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Flammable 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 18 illustrates the case in which CO 2  is contained in an amount of 4.0 mass % or 5.0 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 18 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                   
                 Comparative 
                 Comparative 
                   
                   
               
               
                   
                   
                 Example 21 
                 Example 22 
                 Example 14 
                 Example 23 
                 Example 24 
                 Example 15 
                 Example 16 
               
               
                 Item 
                 Unit 
                 C′ 
                 D′ 
                 E′ = G′ 
                 C 
                 D′ 
                 E′ 
                 G′ 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 58.5 
                 21.0 
                 42.6 
                 58.0 
                 20.1 
                 43.6 
                 40.4 
               
               
                 R125 
                 mass % 
                 37.5 
                 0.0 
                 21.6 
                 37.0 
                 0.0 
                 22.7 
                 19.4 
               
               
                 R134a 
                 mass % 
                 0.0 
                 75.0 
                 31.8 
                 0.0 
                 74.9 
                 28.7 
                 35.2 
               
               
                 CO 2   
                 mass % 
                 4.0 
                 4.0 
                 4.0 
                 5.0 
                 5.0 
                 5.0 
                 5.0 
               
               
                 GWP 
                 — 
                 1707 
                 1214 
                 1500 
                 1687 
                 1207 
                 1500 
                 1455 
               
               
                 COP in Comparison 
                 % 
                 99.3 
                 103.7 
                 101.0 
                 99.0 
                 103.3 
                 100.5 
                 100.9 
               
               
                   
                 (relative 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 110.3 
                 66.5 
                 90.2 
                 112.2 
                 68.1 
                 93.8 
                 90.0 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 109.4 
                 68.1 
                 90.7 
                 111.5 
                 70.2 
                 94.5 
                 90.9 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 f1ammabi1ity 
               
               
                   
               
            
           
         
       
     
     Table 19 illustrates the case in which CO 2  is contained in an amount of 6.1 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 19 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                   
                   
                   
               
               
                   
                   
                 Example 25 
                 Example 26 
                 Example 27 
                 Example 28 
                 Example 16 
                 Example 17 
                 Example 18 
               
               
                 Item 
                 Unit 
                 A 
                 B 
                 C′ 
                 D′ 
                 E′ 
                 F 
                 G′ 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 63.3 
                 0.0 
                 57.4 
                 21.0 
                 44.7 
                 36.1 
                 38.0 
               
               
                 R125 
                 mass % 
                 30.6 
                 7.6 
                 36.5 
                 0.0 
                 23.8 
                 20.7 
                 17.1 
               
               
                 R134a 
                 mass % 
                 0.0 
                 86.3 
                 0.0 
                 72.9 
                 25.5 
                 37.1 
                 38.8 
               
               
                 CO 2   
                 mass % 
                 6.1 
                 6.1 
                 6.1 
                 6.1 
                 6.1 
                 6.1 
                 6.1 
               
               
                 GWP 
                 — 
                 1500 
                 1500 
                 1665 
                 1184 
                 1500 
                 1500 
                 1410 
               
               
                 COP in Comparison 
                 % 
                 99.0 
                 102.2 
                 98.7 
                 102.9 
                 99.9 
                 100.5 
                 100.8 
               
               
                   
                 (relative 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 115.5 
                 56.8 
                 114.2 
                 71.4 
                 97.7 
                 90.0 
                 90.0 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 114.0 
                 62.1 
                 113.8 
                 73.7 
                 98.6 
                 91.6 
                 91.2 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Flammable 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 20 illustrates the case in which CO 2  is contained in an amount of 8.0 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 20 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                   
                   
                   
                   
                   
                   
               
               
                   
                   
                 Example 29 
                 Example 30 
                 Example 19 
                 Example 20 
                 Example 21 
                 Example 22 
                 Example 23 
                 Example 24 
               
               
                 Item 
                 Unit 
                 C′ 
                 D′ 
                 H 
                 I 
                 J 
                 K 
                 L 
                 M 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 56.4 
                 20.8 
                 36.0 
                 38.4 
                 42.3 
                 43.6 
                 39.3 
                 41.3 
               
               
                 R125 
                 mass % 
                 35.6 
                 0.0 
                 22.0 
                 17.6 
                 24.3 
                 22.8 
                 23.2 
                 20.5 
               
               
                 R134a 
                 mass % 
                 0.0 
                 71.2 
                 34.0 
                 36.0 
                 25.4 
                 25.6 
                 29.5 
                 30.2 
               
               
                 CO 2   
                 mass % 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
                 8.0 
               
               
                 GWP 
                 — 
                 1627 
                 1159 
                 1500 
                 1390 
                 1500 
                 1458 
                 1500 
                 1428 
               
               
                 COP in Comparison 
                 % 
                 98.1 
                 102.2 
                 99.7 
                 100.0 
                 99.2 
                 99.3 
                 99.4 
                 99.6 
               
               
                   
                 (relative 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 117.7 
                 75.8 
                 95.0 
                 95.0 
                 100.8 
                 101.1 
                 98.0 
                 98.4 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison. 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 117.8 
                 78.5 
                 97.3 
                 96.7 
                 102.5 
                 102.5 
                 100.0 
                 100.0 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 21 illustrates the case in which CO 2  is contained in an amount of 9.0 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 21 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                   
                   
                   
                   
                   
                   
               
               
                   
                   
                 Example 31 
                 Example 32 
                 Example 25 
                 Example 26 
                 Example 27 
                 Example 28 
                 Example 29 
                 Example 30 
               
               
                 Item 
                 Unit 
                 C′ 
                 D′ 
                 H 
                 I 
                 J 
                 K 
                 L 
                 M 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 55.9 
                 20.8 
                 33.0 
                 36.4 
                 38.6 
                 41.2 
                 35.6 
                 39.0 
               
               
                 R125 
                 mass % 
                 35.1 
                 0.0 
                 21.6 
                 15.6 
                 23.6 
                 20.4 
                 22.5 
                 18.2 
               
               
                 R134a 
                 mass % 
                 0.0 
                 70.2 
                 36.4 
                 39.0 
                 28.8 
                 29.4 
                 32.9 
                 33.8 
               
               
                 CO 2   
                 mass % 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
                 9.0 
               
               
                 GWP 
                 — 
                 1606 
                 1144 
                 1500 
                 1349 
                 1500 
                 1413 
                 1500 
                 1384 
               
               
                 COP in Comparison 
                 % 
                 97.8 
                 101.9 
                 99.5 
                 99.9 
                 99.0 
                 99.2 
                 99.3 
                 99.5 
               
               
                   
                 (relative 
               
               
                   
                 to R4.10A) 
               
               
                 Refrigerating 
                 % 
                 119.5 
                 78.2 
                 95.0 
                 95.0 
                 100.1 
                 100.7 
                 97.4 
                 98.1 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 119.9 
                 81.1 
                 97.8 
                 97.1 
                 102.5 
                 102.5 
                 100.0 
                 100.0 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     Table 22 illustrates the case in which CO 2  is contained in an amount of 6.7 mass %. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 22 
               
               
                   
               
               
                   
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                   
                   
                   
                   
               
               
                   
                   
                 Example 33 
                 Example 34 
                 Example 35 
                 Example 36 
                 Example 31 
                 Example 32 
                 Example 33 
                 Example 34 
               
               
                 Item 
                 Unit 
                 A 
                 B 
                 C′ 
                 D′ 
                 H 
                 I 
                 J 
                 K 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 R32 
                 mass % 
                 62.5 
                 0.0 
                 57.1 
                 21.0 
                 39.8 
                 41.1 
                 44.1 
                 44.5 
               
               
                 R125 
                 mass % 
                 30.8 
                 8.0 
                 36.2 
                 0.0 
                 22.5 
                 20.2 
                 24.1 
                 23.6 
               
               
                 R134a 
                 mass % 
                 0.0 
                 85.3 
                 0.0 
                 72.3 
                 31.0 
                 32.0 
                 25.1 
                 25.2 
               
               
                 CO 2   
                 mass % 
                 6.7 
                 6.7 
                 6.7 
                 6.7 
                 6.7 
                 6.7 
                 6.7 
                 6.7 
               
               
                 GWP 
                 — 
                 1500 
                 1500 
                 1652 
                 1176 
                 1500 
                 1442 
                 1500 
                 1487 
               
               
                 COP in Comparison 
                 (relative 
                 98.8 
                 102.1 
                 98.5 
                 102.7 
                 100.0 
                 100.1 
                 99.6 
                 99.7 
               
               
                   
                 to R410A) 
               
               
                 Refrigerating 
                 % 
                 116.5 
                 58.4 
                 115.3 
                 72.8 
                 95.0 
                 95.0 
                 98.9 
                 99.0 
               
               
                 Capacity in 
                 (relative 
               
               
                 Comparison 
                 to R410A) 
               
               
                 Pressure at 
                 % 
                 115.2 
                 63.9 
                 115.1 
                 75.2 
                 96.5 
                 96.2 
                 100.0 
                 100.0 
               
               
                 Compressor Outlet 
                 (relative 
               
               
                 in Comparison 
                 to R410A) 
               
               
                 ASHRAE 
                 — 
                 Flammable 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
                 Non- 
               
               
                 Flammability/Non- 
                   
                   
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
                 flammable 
               
               
                 flammability 
               
               
                   
               
            
           
         
       
     
     DESCRIPTION OF THE REFERENCE SYMBOLS 
     
         
           1 : ignition source 
           2 : sample inlet 
           3 : springs 
           4 : 12-liter glass flask 
           5 : electrodes 
           6 : stirrer 
           7 : insulated chamber 
           10 : refrigerating machine 
           11 : refrigerant circuit 
           12 : compressor 
           13 : heat-source-side heat exchanger 
           14 : expansion mechanism 
           15 : user-side heat exchanger 
           16 : fan 
           17 : electromagnetic valve 
           18 : four-way switching valve 
           19 : heating means 
           20 : bypass flow path 
         A: a compositional ratio when GWP is 1500, and the concentration of R134a (mass %) is 0 mass %. 
         B: a compositional ratio when GWP is 1500, and the concentration of R32 (mass %) is 0 mass %. 
         C: a compositional ratio on the ASHRAE non-flammability border line, when the concentration of R134a (mass %) is 0 mass %. 
         D: a compositional ratio on the ASHRAE non-flammability border line, when the concentration of R125 (mass %) is 0 mass %. 
         E: a point of intersection between line segment AB and line segment CD. 
         F: a compositional ratio when GWP is 1500, and the refrigerating capacity relative to that of R410A is 90%. 
         G: a compositional ratio on the ASHRAE non-flammability border line, when the refrigerating capacity relative to that of R410A is 90%. 
         C′: a compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the concentration of R134a (mass %) is 0 mass %. 
         D′: a compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the concentration of R125 (mass) is 0 mass %. 
         E′: a point of intersection between line segment AB and line segment C′D′. 
         G′: a compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the refrigerating capacity relative to that of R410A is 90%. 
         H: a compositional ratio when GWP is 1500, and the refrigerating capacity relative to that of R410A is 95%. 
         I: a compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the refrigerating capacity relative to that of R410A is 95%. 
         J: a compositional ratio when GWP is 1500, and the pressure at the compressor outlet relative to that of R410A is 102.5%. 
         K: a compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the pressure at the compressor outlet relative to that of R410A is 102.5%. 
         L: a compositional ratio when GWP is 1500, and the pressure at the compressor outlet relative to that of R410A is 100%. 
         M: a compositional ratio on the ASHRAE non-flammability limit line that takes into account 3.5 mass % of the concentration of the non-flammable refrigerant R125 as a safety factor, and when the pressure at the compressor outlet relative to that of R410A is 100%.