WO2010002023A1

WO2010002023A1 - REFRIGERANT COMPOSITION COMPRISING DIFLUOROMETHANE (HFC32), 2,3,3,3-TETRAFLUOROPROPENE (HFO1234yf) AND 1,1,1,2-TETRAFLUOROETHANE (HFC134a)

Info

Publication number: WO2010002023A1
Application number: PCT/JP2009/062252
Authority: WO
Inventors: Tatsumi Tsuchiya; Katsuki Fujiwara; Masahiro Noguchi; Yasufu Yamada
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2008-07-01
Filing date: 2009-06-30
Publication date: 2010-01-07
Anticipated expiration: 2011-01-01
Also published as: WO2010002023A8; TW201014898A

Abstract

The present invention provides a refrigerant composition that is non-flammable in the liquid phase. The present invention further provides a refrigerant composition that is non-flammable, and has low LCCP, a low environmental impact, and a low global warming potential. More specifically the invention provides a refrigerant composition containing difluoromethane (HFC32), 2,3,3,3-tetrafluoropropene (HFO1234yf), and 1,1,1,2-tetrafluoroethane (HFC134a) at a ratio of HFC32/HFO1234yf/HFC134a in a range surrounded by points (0/64/36 mass%), (0/0/100 mass%), and (45/0/55 mass%) in a ternary diagram of a refrigerant composition containing HFC32, HFO1234yf and HFC134, the composition essentially including HFC32 and HFO1234yf

Description

Title of Invention: REFRIGERANT COMPOSITION COMPRISING DIFLUOROMETHMIE (HFC32), 2, 3, 3, 3-TETRAFLUOROPROPENE (HFO1234yf) AND 1,1, 1,2-TETRAFLUOROETHANE (HFC134a)

Technical Field

The present invention relates to a mixed refrigerant composition comprising difluoromethane (HFC32), 2,3,3,3- tetrafluoropropene (HFO1234yf) , and 1,1, 1,2-tetrafluoroethane (HFC134a) for use in refrigeration and air-conditioning systems.

Background Art

With global warming becoming an increasingly serious issue worldwide, the development of environmentally friendly refrigeration and air-conditioning systems has become increasingly important. In addition to having an impact on global warming, refrigerants are greatly involved in the performance of refrigeration and air-conditioning systems. Therefore, refrigerant selection has an important role in reducing carbon dioxide emissions that contribute to global warming.

Recently, a variety of partially fluorinated propenes having a double bond in the molecule and having a lower global warming potential than known chlorofluorocarbon (CFC) , hydrochlorofluorocarbon (HCFC) , and hydrofluorocarbon (HFC) have been proposed.

2,3, 3,3-tetrafluoropropane (HFO1234yf) is one such propene (see for example, Patent Literatures 1 and 2) . However, HFO1234yf is flammable and has the property of igniting at a concentration in air of 6.5 to 12.5 vol.% at 21°C. In addition, this refrigerant has a higher boiling point than HCFC22, which has been conventionally used in stationary air conditioners, and R407C and R410A, which have come into use as alternatives to HCFC22 and are uninvolved in ozone layer depletion. For this reason, the refrigerating capacity cannot be maintained by the use of HFO1234yf alone. In the selection of a refrigerant, a low global warming potential (GWP) of the refrigerant itself is obviously important; however, the energy use efficiency of the system using the refrigerant is equally, or more important. The former is evaluated as a direct environmental impact, and the latter as an indirect environmental impact. LCCP (Life Cycle Climate Performance) has been proposed as an objective index for evaluating direct and indirect impacts (see, for example, Non- Patent Literature 1) . Although LCCP is now widely recognized for use in the comprehensive assessment of refrigerants, there have been no cases where LCCP evaluation has been performed to provide optimal refrigerants .

Citation List Patent Literature

PTL 1: WO 2005/105995

PTL 2: WO 2006/094303

Non-patent Literature

NPL 1: "LIFE CYCLE CLIMATE PERFORMANCE OF SOME APPLICATIONS IN JAPAN", HARUO ONISHI, 15^th Annual Earth Technologies Forum and

Mobile Air Conditioning Summit, April 13-15, 2004 Conference

Proceedings

Summary of Invention Technical Problem

When a refrigerant having a high boiling point is used at a low operating pressure, the vapor compression refrigeration cycle has an insufficient capacity. Therefore, it is necessary to increase the size of the device etc. to ensure the desired cooling or heating capacity, which normally results in a deteriorated indirect impact due to pressure loss. Moreover, when the refrigerant is flammable, the use of a highly safe material in the electrical system is required, and an upper limit is set on the amount of the refrigerant to be charged into an apparatus. An object of the present invention is to provide a o refrigerant composition that is nonflammable, and ensures low LCCP and less burden on the environment.

Solution to Problem The present inventors carried out extensive research to achieve the above object. As a result, the inventors found that in an apparatus that circulates a refrigerant through a compressor to form a refrigeration cycle, when the refrigerant used is a composition containing difluoromethane (HFC32) , 2,3,3,3-tetrafluoropropene (HFO1234yf) , and 1,1,1,2- tetrafluoroethane (HFC134a) at a ratio of HFC32/HFO1234yf/HFCl34a in a range surrounded by points (0/64/36 mass%) , (0/0/100 mass%) , and (45/0/55 mass%) in a ternary diagram of a refrigerant composition containing HFC32, HFO1234yf, and HFC134a (FIG. 1), and when the composition essentially comprises HFC32 and

HFO1234yf, the refrigerant composition is non-flammable. The inventors further found that this refrigerant composition has low LCCP and a low environmental impact.

The inventors further found that when a refrigerant composition contains HFC32, HFO1234yf, and HFC134a at a ratio of HFC32/HFO1234yf/HFC134a in a range surrounded by points (0/64/36 mass%), (0/30.2/69.8 mass%) , and (37.9/10.1/52.0 mass%) in the above ternary diagram, and when the composition essentially comprises HFC32, the composition is non-flammable, and has a GWP (Integration Time Horizon; ITH = 100 yr) of 1,000 or less, low LCCP, and a low environmental impact.

The inventors further found that when a refrigerant composition contains HFC32, HFO1234yf, and HFC134a at a ratio of HFC32/HFO1234yf/HFC134a in a range surrounded by points (0/64/36 mass%), (0/40.7/59.3 mass%) , and (26.1/26.9/47.0 mass%) in the above ternary diagram, and when the composition essentially comprises HFC32, the composition is non-flammable, and has a GWP (ITH = 100 yr) of 850 or less, low LCCP, and a low environmental impact. The inventors further found that when a refrigerant composition charged into a refrigeration system contains HFC32, HFO1234yf, and HFC134a at a ratio of HFC32/HFO1234yf/HFC134a in a range surrounded by points (7/37/56 mass%) , (9/35/56 mass%), (13/24/63 mass%), (10/25/65 mass%) , and (7/27/66 mass%) in the ternary diagram (FIG. 1), the composition remains non-flammable even in the event of a leak in the gas or liquid phase. Furthermore, the composition has a GWP (ITH = 100 yr) of 1,000 or less, low LCCP, and a low environmental impact.

In the above-mentioned ternary diagram (FIG. 1) , for example, the point (26.1/26.9/47.0 mass%) refers to a composition containing 26.1 mass% of HFC32, 26.9 mass% of HFO1234yf, and 47.0 mass% of HFCl34a. The range surrounded by the points in the ternary diagram refers to all possible proportions of the three components that are located on the sides or inside of a polygon, such as a triangle, quadrangle, or pentagon, which is formed by connecting a plurality of points such as three, four or five points as mentioned above.

The present inventors conducted further research based on the above findings, and finally accomplished the present invention.

More specifically, the present invention provides the following nonflammable refrigerant compositions.

Item 1. A refrigerant composition containing difluoromethane (HFC32) , 2, 3, 3, 3-tetrafluoropropene (HFO1234yf) , and 1,1,1,2-tetrafluoroethane (HFCl34a) , the ratio of

HFC32/HFO1234yf/HFC134a being in a range surrounded by points (0/64/36 mass%), (0/0/100 mass%) , and (45/0/55 mass%) in a ternary diagram of a refrigerant composition containing HFC32, HFO1234yf, and HFC134, and the composition essentially comprising HFC32 and HFO1234yf.

Item 2. The refrigerant composition according to item 1 wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (0/64/36 mass%) , (0/30.2/69.8 mass%) , and (37.9/10.1/52.0 mass%) in the ternary diagram, and the composition essentially comprises HFC32. Item 3. The refrigerant composition according to item 1 or 2, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (0/64/36 mass%), (0/40.7/59.3 mass%), and (26.1/26.9/47.0 mass%) in the ternary diagram, and the composition essentially comprises HFC32.

Item 4. The refrigerant composition according to any one of items 1 to 3, wherein the ratio of HFC32/HFO1234yf/HFCl34a is in a range surrounded by points (7/54/39 mass%) , (26/27/47 mass%) , and (7/37/56 mass%) in the ternary diagram. Item 5. The refrigerant composition according to any one of items 1 to 4, wherein the ratio of HFC32/HFO1234yf/HFCl34a is in a range surrounded by points (7/54/39 mass%) , (12/46/42 mass%) , and (7/49/44 mass%) in the ternary diagram.

Item 6. The refrigerant composition according to any one of items 1 to 4, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (18/38/44 rαass%) , (26/27/47 mass%) , and (20/31/49 mass%) in the ternary diagram.

Item 7. The refrigerant composition according to item 1 or 2, wherein the ratio of HFC32/HFO1234yf/HFCl34a is in a range surrounded by points (7/37/56 mass%), (9/35/56 mass%) ,

(13/24/63 mass%) , (10/25/65 mass%) , and (7/27/66 mass%) in the ternary diagram.

Item 8. The refrigerant composition according to item 1 or 2, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (7/37/56 mass%) , (8/36/56 mass%) , (10/32/58 mass%), and (7/34/59 mass%) in the ternary diagram.

Item 9. The refrigerant composition according to any one of items 1 to 8, further comprising a polymerization inhibitor . Item 10. The refrigerant composition according to any one of items 1 to 9, further comprising a drying agent.

Item 11. The refrigerant composition according to any one of items 1 to 10, further comprising a stabilizer.

Item 12. A method of operating a refrigerator, comprising circulating the refrigerant composition of any one of items 1 to 11 through a compressor.

Item 13. A method of producing the refrigerant composition of item 1, comprising mixing difluororαethane (HFC32) , 2,3,3,3-tetrafluoroρropene (HFO1234yf) , and 1,1,1,2- tetrafluoroethane (HFC134a) so that the ratio of

HFC32/HFO1234yf/HFCl34a is in a range surrounded by points (0/64/36 mass%), (0/0/100 mass%) , and (45/10/55 mass%) in a ternary diagram of a refrigerant composition containing HFC32, HFO1234yf and HFC134, and the composition essentially comprises HFC32.

Item 14. A refrigerator comprising a refrigerant composition according to any one of items 1 to 11.

Advantageous Effects of Invention The refrigerant composition of the present invention is non-flammable. Therefore, modification of the system specification, such as use of highly safe members in an apparatus is unnecessary. Furthermore, the refrigerant composition of the invention that has specific components in specific proportions achieves the following effects:

(1) The refrigerant composition of the invention achieves the same or improved cycle performance compared to conventionally available refrigerants such as R407C or R410A when used as a refrigerant for a heat pump apparatus . (2) The refrigerant makes no contribution to ozone layer depletion even when the refrigerant is not completely recovered after use, because its ozone depletion potential (ODP) is zero. (3) The global warming potential (GWP) is less than those of conventionally-used refrigerants such as R407C and R410A. (4) The refrigerant composition is excellent in LCCP evaluation, and its contribution to global warming is as low as, or lower than, that of conventionally available refrigerants such as R407C or R410A, when used as a refrigerant for a heat pump apparatus.

Brief Description of Drawings FIG. 1 is a ternary diagram showing the proportions of HFC32, HFO1234yf, and HFC134a in a refrigerant composition.

FIG. 2 shows the flammable range of a mixed system of HFC32, HFO1234yf, and HFC134a. FIG. 3 schematically illustrates the apparatus used in a flammability test.

Description of Embodiments

The present inventors conducted extensive research on the relationships of the ratio of HFC125, HFO1234yf, and HFC134a to LCCP (Life Cycle Climate Performance) and to flammability. LCCP and flammability were evaluated by the methods described in Test Examples 1 and 2, respectively.

The results of the evaluations revealed the following. When a refrigerant composition (Composition 1) contains HFC32,

HFO1234yf, and HFC134a at a ratio of HFC32/HFO1234yf/HFC134a in a range surrounded by points (0/64/36 mass%) , (0/0/100 mass%) , and (45/0/55 mass%) in a ternary diagram of a refrigerant composition containing HFC32, HFO1234yf and HFC134a (FIG. 1), and when the composition essentially comprises HFC32 and HFO1234yf, the composition is nonflammable, and has low LCCP and a low environmental impact.

In other words, when a refrigerant composition contains HFC32, HFO1234yf and HFC134a at a ratio of HFC32/HFO1234yf/HFC134a (a/b/c mass%) that satisfies the following equations (1) to (3) :

0 < a < 45 (1)

0 < b < (64 - 19 / 45 x a) (2) c = 100 - a - b (3) the composition is non-flammable, and has excellent LCCP and a low environmental impact. Equations (1) to (3) mathematically define the non-flammable region, as supported by the Examples below (see FIG. 1) .

When a refrigerant composition (Composition 2) contains HFC32, HFO1234yf, and HFC134a at a mixing ratio in a range surrounded by points (0/64/36 rnass%) , (0/30.2/69.8 mass%) , and (37.9/10.1/52.0 mass%) in the ternary diagram (FIG. 1), and when the composition essentially comprises HFC32, the composition is non-flammable, and has a GWP (ITH = 100 yr) of 1,000 or less, low LCCP, and a low environmental impact.

In other words, when a refrigerant composition contains HFC32, HFO1234yf and HFCl34a at a ratio of HFC32/HFO1234yf/HFC134a (a/b/c mass%) that satisfies the following equations (4) to (6) : 0 < a <37.9 (4)

((43000 - 755 x a) / 1426) <b < (64 - 19 / 45 x a) (5) c = 100 - a - b (6) , the composition is non-flammable, and has a GWP (ITH = 100 yr) of 1,000 or less, low LCCP, and a low environmental impact. Equations (4) to (6) mathematically define the range surrounded by a non-flammability limit line and GWP (ITH = 100 yr) = 1,000, as supported by the Examples below (see FIG. 1) .

When a refrigerant composition (Composition 3) contains HFC32, HFO1234yf, and HFC134a at a ratio of HFC32/HFO1234yf/HFC134a in a range surrounded by points (0/64/36 mass%), (0/40.7/59.3 mass%) , and (26.1/26.9/47.0 mass%) in the ternary diagram (FIG. 1) , and when the composition essentially comprises HFC32, the composition is non-flammable, and has a GWP (ITH = 100 yr) of 850 or less, excellent LCCP, and a low environmental impact.

In other words, when a refrigerant composition contains HFC32, HFO1234yf, and HFC134a at a ratio of HFC32/HFO1234yf/HFCl34a (a/b/c mass%) that satisfies the following equations (7) to (9) : 0 < a <26.1 (7)

((58000 - 755 x a) / 1426) ≤b < (64 - 19 / 45 x a) (8) c = 100 - a - b (9), the refrigerant composition is non-flammable in the liquid phase, and has a GWP (ITH = 100 yr) of 850 or less, low LCCP, and a low environmental impact. Equations (7) to (9) mathematically define the range surrounded by a non-flammability limit line and GWP

(ITH = 100 yr) = 850, as supported by the Examples below (see FIG.

1).

When a refrigerant composition (Composition 4) contains HFC32, HFO1234yf, and HFC134a at a ratio of

HFC32/HFO1234yf/HFC134a in a range surrounded by points (7/54/39 mass%), (26/27/47 mass%) , and (7/37/56 mass%) in the ternary diagram (FIG. 1) , the composition is non-flammable, and has excellent LCCP and a low environmental impact . Composition 4 has a low GWP and excellent refrigerating capacity. For example, the GWP (ITH = 100 yr) of Composition 4 is about 600 to about 850, and thus not more than half that of R410A (GWP: 2088) or R407C (GWP: 1774) .

Further, when a refrigerant composition (Composition 5) contains HFC32, HFO1234yf, and HFC134a at a ratio of

HFC32/HFO1234yf/HFCl34a in a range surrounded by points (7/54/39 mass%), (12/46/42 mass%) , and (7/49/44 mass%) in the ternary diagram (FIG. 1) , or a refrigerant composition (Composition 6) contains HFC32, HFO1234yf, and HFC134a at a ratio of HFC32/HFO1234yf/HFCl34a in a range surrounded by points (18/38/44 mass%), (26/27/47 mass%) , and (20/31/49 mass%) , such a refrigerant composition achieves particularly excellent effects . The GWP of Composition 5 is equivalent to or less than that of HFC32 (GWP: 675) . When a refrigerant composition (Composition 7) contains

HFC32, HFO1234yf, and HFC134a at a ratio of

HFC32/HFO1234yf/HFC134a in a range surrounded by points (7/37/56 mass%), (9/35/56 mass%) , (13/24/63 mass%) , (10/25/65 mass%) , and

(7/27/66 mass%) in the ternary diagram (FIG. 1) , the composition has excellent LCCP and a low environmental impact, and is nonflammable in the liquid phase and in the corresponding saturated gas phase. Composition 7 has a low GWP and excellent refrigerating capacity. For example, the GWP (ITH = 100 yr) of Composition 7 is about 850 to about 1,000, and is thus not more than half that of R410A (GWP: 2088), and not more than three- fifths that of R407C (GWP: 1774) .

When a refrigerant composition (Composition 8) contains HFC32, HFO1234yf, and HFC134a at a ratio of

HFC32/HFO1234yf/HFC134a in a range surrounded by points (7/37/56 mass%), (8/36/56 mass%) , and (10/32/58 mass%) , and (7/34/59 mass%) in the ternary diagram (FIG. 1) , the composition has particularly remarkable effects .

The refrigerant composition of the present invention is highly stable. If necessary, stabilizers may be added to meet the requirement of high stability under severe conditions. Examples of usable stabilizers include (i) aliphatic nitro compounds such as nitromethane and nitroethane; aromatic nitro compounds such as nitrobenzene and nitrostyrene; (ii) ethers such as 1, 4-dioxane; amines such as 2,2, 3,3, 3-pentafluoropropylamine and diphenylamine; butylhydroxyxylene; benzotriazole; and the like. The stabilizers can be used singly or in a combination of two or more.

The amount of stabilizer used may vary depending on the type of stabilizer used. The amount is not particularly limited, as long as it does not impair the performance of the nonflammable composition. In general, the stabilizer is preferably used in an amount of about 0.01 to about 5 parts by weight, and more preferably about 0.05 to about 2 parts by weight, per 100 parts by weight of the mixture of HFC125, HFO1234yf, and HFCl34a. The composition of the present invention may further contain a polymerization inhibitor. Examples of such polymerization inhibitors include known compounds such as 4- methoxy-1-naphthol, hydroquinone, hydroquinone methyl ether, dimethyl-t-butylphenol, 2, 6-di-tert-butyl-p-cresol, and benzotriazole.

In general, the polymerization inhibitor is preferably used in an amount of about 0.01 to about 5 parts by weight, and more preferably about 0.05 to about 2 parts by weight, per 100 parts by weight of the mixture of HFC32, HFO1234yf, and HFC134a. The composition of the present invention may further contain a drying agent .

The refrigerant composition of the present invention can be circulated through a compressor to form a refrigeration cycle. An apparatus that circulates the refrigerant composition of the invention through a compressor to form a refrigeration cycle can also be provided.

Examples of refrigerating systems that can use the refrigerant composition of the present invention include, but are not limited to, car air conditioners, refrigerating units for automatic vending machines, home and business air conditioners, gas heat pumps (GHP) , electrical heat pumps (EHP) , and the like.

In particular, the refrigerant composition of the invention is effectively used in home and business air conditioners, whose downsizing is required.

Examples

The present invention is described below with reference to Examples. However, the Examples do not limit the scope of the invention.

Test Example 1

Using the HFC32/HFO1234yf/HFC134a compositions shown in

Table 1 as refrigerants (Examples 1 to 13) , a heat pump was operated under the following conditions : cooling rated capacity: 4kW, evaporating temperature of the refrigerant in the evaporator: 1O⁰C, condensing temperature of the refrigerant in the condenser: 45⁰C; cooling intermediate capacity: 2kW, evaporating temperature: 17⁰C, condensing temperature: 42⁰C; heating rated capacity: 5kW, evaporating temperature: 0⁰C, condensing temperature: 42⁰C; heating intermediate capacity: 2.5kW, evaporating temperature:

2°C, condensing temperature: 32°C.

Degrees of superheat and subcool were set to O⁰C in each condition. As Comparative Examples, the heat pump apparatus was operated under the same conditions as above using R410A (Comparative Example 1) and R407C (Comparative Example 2) as refrigerants . The coefficient of performance (COP) was calculated on the basis of the obtained results. The COP, evaporation pressure, and condensation pressure are shown in Table 1. Subsequently, the results were used for calculating the annual power consumption (kWh) in conformity with JRA 4046:2004, and LCCP evaluation has been performed (Table 2) .

The coefficient of performance (COP) and LCCP were determined by the following formulae:

COP = (cooling capacity or heating capacity) / power consumption LCCP = direct impact (kg-CO₂) + indirect impact (kg-CO₂) Direct impact = (leakage during charging at a manufacturing plant) + (annual regular leakage) + (annual irregular leakage) + (leakage during service) + (leakage during disposal)

Indirect impact = (CO₂ emissions during the use of the air conditioning system) + (CO₂ emissions during the production and transportation of the refrigerant)

More specifically, direct and indirect impacts were calculated by the following equations :

Direct impact = GWP x M x (1-α) + GWP_AE X M Indirect impact = N x E x β GWP: global warming potential in terms of CO₂ per kg, (kg- CO₂/kg) , Integration Time Horizon (ITH) : 100 years

GWP_AE: additional GWP caused by release during production, etc. (including those caused by leakage of by-products etc., and indirect release) (kg-CU₂/kg) N: operation period of the system (year) N = 12 M: amount (kg) charged into the system M = 1.3 α: recovery rate during disposal of the system (recovery amount/charge amount) α = 0.6

E: annual power consumption of the system (kWh/year) β: CO₂ emissions necessary for 1 kWh power generation (kg- CO₂/kWh) β=0.378

In Table 3, the values of the global warming contribution CO₂ emission ratio (indirect impact, direct impact, and LLCP) of Examples 1 to 13 and Comparative Example 2 are relative values (ratios) obtained by expressing the indirect impact, direct impact, and LCCP of Examples 1 to 13 and Comparative Example 2, on the basis that the values of Comparative Example 1 (R410A) are considered to be 100.

Regarding LCCP, i.e., an index reflecting direct and indirect impacts of carbon dioxide gas emissions, the results show that the refrigerant of the present invention has a lower LCCP value than R410A and R407C, and has the lowest environmental impact.

Table 1

Table 2

Table 3

Test Example 2

The flammability of the mixed refrigerant of the three components used in the refrigerant composition of the present invention was evaluated by measuring the flammable range using a measuring apparatus according to ASTM E681-2001. FIG. 3 shows the apparatus .

A 12-liter spherical glass flask was used so that the combustion state can be visually observed and photographically recorded. When excessive pressure was generated by combustion, gas was allowed to escape from the upper lid. Ignition was achieved by electric discharge from electrodes disposed at one- third the distance from the bottom.

Test vessel: 280 mm Φ spherical (internal volume: 12 liters)

Test temperature: 60°C ±3°C

Pressure: 101.3 kPa ±0.7 kPa

Water: 0.0088 g per gram of dry air ±0.0005 g Mixing ratio of refrigerant/air: 1 vol.% increments ±0.2 vol.% Refrigerant mixture: ±0.1 mass% Ignition method: AC discharge Electrode spacing: 6.4 mm (1/4 inches)

Spark: 0.4 seconds ±0.05 seconds

Evaluation criteria: When a flame extends at an angle of at 90° or wider from the ignition point, it was evaluated as flammable (propagation).

FIG. 2 shows the flammable range of mixed systems of HFC32/HFO1234yf/HFC134a. The ratio of HFC32/HFO1234yf/HFC134a (a/b/c mass%) on the nonflammability limit line substantially satisfied the relationship defined by the following Equations (10) to (12) :

0 < a <45 (10) b = (64 - 19 / 45 x a) (11) c = 100 - a - b (12) The results show that the HFC32/HFO1234yf/HFC134a mixture used in the refrigerant composition of the present invention is non-flammable, and causes no combustion, even when mixed with air at any ratio.

Industrial Applicability

The mixed refrigerant composition of the present invention contains difluoromethane, 2, 3, 3, 3-tetrafluoropropene, and 1, 1, 1,2-tetrafluoroethane, and can be effectively used in refrigeration and air-conditioning systems. Reference Signs List A: Nonflammability limit line X: Flammable region Y: Nonflammable region 1: Ignition source 2 : Sample inlet 3 : Springs

4: 12-liter glass flask 5 : Electrodes 6: Stirrer

7 : Insulated chamber

Claims

[Claim 1] A refrigerant composition comprising difluoromethane (HFC32), 2,3,3,3-tetrafluoropropene (HFO1234yf) , and 1,1,1,2- tetrafluoroethane (HFC134a) , the ratio of HFC32/HFO1234yf/HFCl34a being in a range surrounded by points (0/64/36 mass%) , (0/0/100 mass%) , and (45/0/55 mass%) in a ternary diagram of a refrigerant composition containing HFC32, HFO1234yf, and HFC134, and the composition essentially comprising HFC32 and HFO1234yf.

[Claim 2] The refrigerant composition according to claim 1, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (0/64/36 mass%) , (0/30.2/69.8 mass%) , and (37.9/10.1/52.0 mass%) in the ternary diagram, and the composition essentially comprises HFC32.

[Claim 3] The refrigerant composition according to claim 1, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (0/64/36 mass%) , (0/40.7/59.3 mass%) , and (26.1/26.9/47.0 mass%) in the ternary diagram, and the composition essentially comprises HFC32.

[Claim 4] The refrigerant composition according to claim 1, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (7/54/39 mass%), (26/27/47 mass%) , and (7/37/56 mass%) in the ternary diagram.

[Claim 5] The refrigerant composition according to claim 1, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (7/54/39 mass%) , (12/46/42 mass%) , and (7/49/44 mass%) in the ternary diagram.

[Claim 6] The refrigerant composition according to claim 1, wherein the ratio of HFC32/HFO1234yf/HFC134a is in a range surrounded by points (18/38/44 mass%) , (26/27/47 mass%) , and (20/31/49 mass%) in the ternary diagram.

[Claim 7] The refrigerant composition according to claim 1, wherein the ratio of HFC32/HFO1234yf/HFCl34a is in a range surrounded by points (7/37/56 mass%) , (9/35/56 mass%) , (13/24/63 rαass%), (10/25/65 mass%), and (7/27/66 mass%) in the ternary diagram.

[Claim 8] The refrigerant composition according to claim 1, wherein the ratio of HFC32/HFO1234yf/HFCl34a is in a range surrounded by points (7/37/56 mass%) , (8/36/56 mass%) , (10/32/58 mass%), and (7/34/59 mass%) in the ternary diagram.

[Claim 9] The refrigerant composition according to claim 1, further comprising a polymerization inhibitor.

[Claim 10] The refrigerant composition according to claim 1, further comprising a drying agent.

[Claim 11] The refrigerant composition according to claim 1, further comprising a stabilizer.

[Claim 12] A method of operating a refrigerator, comprising circulating the refrigerant composition of claim 1 through a compressor.

[Claim 13] A method of producing the refrigerant composition of claim 1, comprising mixing difluoromethane (HFC32) , 2,3,3,3- tetrafluoropropene (HFO1234yf) , and 1, 1, 1, 2-tetrafluoroethane (HFCl34a) so that the ratio of HFC32/HFO1234yf/HFCl34a is in a range surrounded by points (0/64/36 mass%), (0/0/100 mass%) , and (45/0/55 mass%) in a ternary diagram of a refrigerant composition containing HFC32, HFO1234yf and HFC134, and the composition essentially comprises HFC32. [Claim 14] A refrigerator comprising a refrigerant composition according to claim 1.