KR100492171B1 - R502 and r22 substitute mixed refrigerant and refrigeration system using thereof - Google Patents

Abstract

The present invention relates to a mixed refrigerant for replacing R502 and R22 used in a vapor compression refrigerator or an air conditioner and a refrigeration system using the same, and more particularly, to replace an existing refrigeration system without causing ozone layer destruction and global warming. It relates to a mixed refrigerant and a refrigeration system using a combination of propylene, propane, 1,1-difluoroethane, dimethyl ether and isobutane that can be used without. The mixed refrigerant according to a preferred embodiment of the present invention is composed of R1270 (propylene), R290 (propane) and R152a (1,1-difluoroethane).

Description

R502 AND R22 SUBSTITUTE MIXED REFRIGERANT AND REFRIGERATION SYSTEM USING THEREOF}

The present invention is a mixed refrigerant composed of a material that can be used as a refrigerant (referred to as R) in a vapor compression refrigeration / air conditioner, namely, 'propylene and propane and a combination of R152a, dimethyl ether (hereinafter referred to as DME) and isobutane; It is related to the refrigeration system using the same, and more specifically, monochlorofluoromethane which has been widely used in R502 (hereinafter referred to as CFC502), which has been widely used in low temperature freezers and transport refrigerators, and home air conditioners and commercial air conditioners. A mixed refrigerant and refrigeration system can be substituted for CHClF ₂ (hereinafter referred to as R22 or HCFC22).

CFC502 is an azeotropic mixed refrigerant comprising 48.8% monochlorofluoromethane (hereinafter referred to as R22 or HCFC22) and 51.2% chloropentafluoroethane (hereinafter referred to as R115 or CFC115).

Until now, chlorofluorocarbons (hereinafter referred to as CFCs) and hydrochlorofluorocarbons (hereinafter referred to as CFCs) derived from methane or ethane have been mainly used as refrigerants for refrigerators, air conditioners, and heat pumps. CFC502, which has a boiling point of -45.4 ° C and a molecular mass of 111.6kg / kmol, is the most widely used in freezers, transport freezers, supermarket freezers, etc., and has a boiling point of -40.8 ° C and a molecular mass of 86.47kg / for home air conditioners and commercial air conditioners. HCFC22, kmol, has been the most widely used.

Recently, however, the destruction of the stratospheric ozone layer by CFCs and HCFCs has emerged as an important global environmental problem, and the production and consumption of stratospheric ozone-depleting CFCs and HCFCs is regulated by the Montreal Protocol, created in 1987. The CFC502 and HCFC22 have high Ozone Depletion Potential (ODP) of 0.18 and 0.05, respectively, so that in developed countries, they will be fully or fully pursuant to the Montreal Protocol. You are trying to use an alternative refrigerant with.

Recently, not only the ozone depletion problem but also the global warming problem has begun to emerge rapidly, and the 1997 Kyoto Protocol strongly recommends refusing to use HFC refrigerants with high global warming potential (GWP). . Reflecting this trend, European and Japanese refrigerator manufacturing companies use isobutane (hereinafter referred to as R600a) as a refrigerant in almost all refrigerators and produce household air conditioners, heat pumps, low temperature freezers and automobile air conditioners. Some are also trying to use hydrocarbon-based refrigerants with a low global warming index (GWP).

Table 1 shows the environmental indices of some refrigerants.

Environmental Index of Refrigerants Refrigerant Ozone Depletion Index (ODP) Global Warming Index (GWP) CFC12 0.9 8,500 HFC134a 0.0 1,300 HCFC22 0.05 1,700 R407C 0.0 1,370 CFC502 0.18 4,510 R404A 0.0 3,850 HFC125 0.0 3,200 HFC143a 0.0 4,400 HFC152a 0.0 140 Propylene (R1270) 0.0 3 or less Propane (R290) 0.0 3 or less DME (RE170) 0.0 3 or less Isobutane (R600a) 0.0 3 or less

(*) ODP is based on CFC11 as 1.0.

(**) GWP is based on a 100-year carbon dioxide standard of 1.0.

As shown in Table 1, propylene, propane, isobutane, DME, and HFC152a have an ozone depletion index (ODP) of 0.0 and a global warming index (GWP). This is why most countries in the European Union, Japan and Asia now mix refrigerants with an ODP of 0.0 and lower GWP than conventional CFC or HFC refrigerants to achieve the desired thermodynamic properties while at the same time improving efficiency or increasing oil compatibility. To achieve. In this sense, propylene, propane, isobutane, DME, and HFC152a are eligible.

In order for a material to be useful as an alternative to a conventional refrigerant, it must first have a coefficient of performance (COP) similar to that of a conventional refrigerant. The coefficient of performance (COP) refers to the total refrigeration effect compared to the work applied to the compressor, the larger the COP, the better the energy efficiency of the refrigeration / air conditioner. In addition, in order to use the compressor without major modifications, the alternative refrigerant must have a vapor pressure similar to that of the existing refrigerant and ultimately provide a similar volumetric capacity (VC). Here, the volumetric capacity (VC) refers to the refrigeration effect per unit volume, which is a factor indicating the size of the compressor, which is usually proportional to the vapor pressure and is in kJ / m 3. If the replacement refrigerant has a volume capacity similar to that of the existing refrigerant, it is very advantageous for manufacturers to build refrigeration / air conditioning without changing compressors or making major modifications. However, studies to date have shown that in case of replacing the existing refrigerant with pure material, the volume of the replacement refrigerant is different, so it is inevitable to change or largely modify the compressor, and it is difficult to obtain a similar coefficient of performance as the existing refrigerant.

One way to solve this is to use a mixed refrigerant. The characteristics of mixed refrigerants are that they can be formulated so that their coefficients of performance are similar to those of conventional refrigerants, while at the same time providing a volumetric capacity (VC) similar to conventional refrigerants, thereby eliminating the need for major modifications to the compressor. Due to these characteristics, several mixed refrigerants have been proposed as substitutes for CFC502 and HCFC22 in the past few years, but some of them have HCFCs which are prohibited from use in the Montreal Protocol, and thus are not suitable alternatives in the long term.

DuPont, USA, has developed a three-way mixed refrigerant (44% R125 / 52% R143a / 4% R134a) called R404A that does not cause ozone decay, but it is less energy efficient than R502, which may accelerate the indirect effects of global warming. In addition, it is not a suitable substitute in the long term because it consists only of HFCs that restrict its use in the Kyoto Protocol. In addition, the three-way mixed refrigerant R407C (23% R32 / 25% R125 / 52% R134a), developed by DuPont, USA, has a freezing capacity similar to that of the existing HCFC22, but has low energy efficiency and a temperature gradient of about 7 ° C. If there is a leak in the system, there is a disadvantage of separation of the composition. Allied Signal Co., Ltd. has developed and sold two-way mixed refrigerant (50% R32 / 50% R125) called R410A. However, the refrigerant pressure is about 60% higher than the existing HCFC22. Because of this high, the strength of the material used in the condenser must be increased.

The present invention has been made to solve the above problems of the prior art, the object of the present invention is propylene and propane, R152a and dimethyl ether (hereinafter referred to as DME) and isobutane which are substances that do not cause ozone layer destruction and global warming It is to provide a mixed refrigerant and a refrigeration system using the same that can be applied directly to the existing refrigeration system without replacing or remodeling the existing refrigeration system by using the combination in an appropriate composition ratio.

An object of the present invention described above is 1 to 99 parts by weight of R1270 (propylene), 1 to 98 parts by weight of R290 (propane), 1 to 50 parts by weight of R152a (1,1-difluoroethane) in a refrigeration / air conditioner mixed refrigerant. It can be achieved by a mixed refrigerant consisting of negative.

In order to achieve the above object, 1 to 25 parts by weight of R1270 (propylene), 60 to 90 parts by weight of R290 (propane), and 1 to 15 parts by weight of R152a (1,1-difluoroethane) in a mixed refrigerant for a refrigerator / air conditioner It is preferable that it consists of parts.

In order to achieve the above object, 20 to 50 parts by weight of R1270 (propylene), 30 to 50 parts by weight of R290 (propane), and 1 to 40 parts by weight of R152a (1,1-difluoroethane) in a mixed refrigerant for refrigeration / air conditioner It is preferable that it consists of parts.

In order to achieve the above object, in the refrigerant mixture for refrigeration / air conditioner, it is preferably composed of 60 to 90 parts by weight of R1270 (propylene) and 1 to 40 parts by weight of R152a (1,1-difluoroethane).

In order to achieve the above object, it is preferable that 50 to 90 parts by weight of R1270 (propylene) and 1 to 50 parts by weight of R152a (1,1-difluoroethane) in the mixed refrigerant for refrigeration / air conditioner.

In addition, the object of the present invention described above is a mixed refrigerant consisting of 1 to 99 parts by weight of R1270 (propylene), 1 to 98 parts by weight of R290 (propane), and 1 to 50 parts by weight of RE170 (dimethyl ether) in a refrigeration / air conditioner mixed refrigerant. Can also be achieved.

In order to achieve the above object, it is preferable that the mixed refrigerant for refrigeration / air conditioner is composed of 1 to 20 parts by weight of R1270 (propylene), 70 to 80 parts by weight of R290 (propane), and 1 to 20 parts by weight of RE170 (dimethyl ether). .

In order to achieve the above object, it is preferable that the mixed refrigerant for refrigeration / air conditioner is composed of 1 to 70 parts by weight of R1270 (propylene), 10 to 70 parts by weight of R290 (propane), and 10 to 20 parts by weight of RE170 (dimethyl ether). .

In order to achieve the above object, it is preferable that 50 to 90 parts by weight of R1270 (propylene) and 1 to 50 parts by weight of RE170 (dimethyl ether) in a mixed refrigerant for a freezer / air conditioner.

In addition, the object of the present invention described above is a mixed refrigerant composed of 1 to 99 parts by weight of R1270 (propylene), 1 to 98 parts by weight of R290 (propane), and 1 to 20 parts by weight of R600a (isobutane) in a refrigeration / air conditioner mixed refrigerant. Can also be achieved.

In order to achieve the above object, it is preferable that the mixed refrigerant for refrigeration / air conditioner is composed of 20 to 70 parts by weight of R1270 (propylene), 1 to 70 parts by weight of R290 (propane), and 1 to 20 parts by weight of R600a (isobutane). .

In order to achieve the above object, it is preferable that 50 to 80 parts by weight of R1270 (propylene), 10 to 40 parts by weight of R290 (propane), and 1 to 10 parts by weight of R600a (isobutane) in a mixed refrigerant for refrigeration / air conditioner. .

The above object of the present invention can also be achieved by a refrigeration / air conditioner using the mixed refrigerant of claim 1 to claim 12.

Other objects, specific advantages and novel features of the invention will become more apparent from the following detailed description and the preferred embodiments associated with the accompanying drawings.

Hereinafter, with reference to the accompanying drawings it will be described in detail with respect to the configuration of the mixed refrigerant for R502 and R22 and the refrigeration system using the same according to an embodiment of the present invention.

The present invention is composed of a material which can be used as a refrigerant (referred to as R) in a vapor compression refrigeration / air conditioner, namely, 'propylene, propane, R152a, dimethyl ether (hereinafter referred to as DME), and isobutane. Mixed refrigerant and a refrigeration system using the same. More specifically, R502 (hereinafter referred to as CFC502), which has been widely used in low temperature freezers and transport freezers, and monochloro chloride, which has been widely used in domestic air conditioners and commercial air conditioners, The present invention relates to a mixed refrigerant capable of replacing fluoromethane (CHClF ₂ , hereinafter R22 or HCFC22) and a refrigeration system using the same.

The object of the present invention is that since the ODP is 0.0, it does not affect the ozone layer in the stratosphere at all, and the global warming index is also lower than that of other conventional refrigerants, and at the same time, it is an alternative refrigerant of CFC502 and HCFC22 without greatly modifying the existing compressor. It is to provide a mixed refrigerant that can be used.

More specifically, the present invention relates to R1270 (propylene, propylene) and R290 (propane, propane) and R152a (1,1-difluoroethane) and RE170 (dimethyl ether, DME) and R600a (isobutane, Iso-butane). The present invention relates to a mixed refrigerant selectively configured in combination and a refrigeration system using the same. The alternative mixed refrigerant proposed in the present invention has an ozone depletion index (ODP) of 0.0 and a lower global warming index (GWP) than other alternative refrigerants, and the coefficient of performance (COP) and volume capacity (VC) of CFC502 or HCFC22. Yields a value close to

1 is a block diagram of a general refrigeration / air conditioner used in the present invention. As shown in FIG. 1, the refrigeration / air conditioner generally comprises an evaporator, a condenser, a compressor, an expansion valve, and the like.

To develop an alternative mixed refrigerant, the inventors used the CYCLE-D program developed by the National Institute of Standards and Technology, which simulates the performance of a refrigeration / air conditioner. The program conducted thermodynamic and heat transfer analyzes of the components that make up the refrigeration / air conditioner, such as heat exchangers and compressors, and finally used them all in combination. One of the important factors that determine the accuracy of the program is the properties of the refrigerant. In this program, the properties of all refrigerants were calculated using the Carnahan-Starling-De Santis (CSD) state equation, which is the standard in the United States and Japan. The CSD state equation, known as REFPROP, was developed by the National Institute of Standards and Technology and is the most widely used program in leading refrigeration and air conditioning companies, laboratories, and universities worldwide for its proven accuracy and applicability. The actual data was used as input data for the development and execution of the mixed refrigerant and refrigeration / air conditioner.

The inventors have determined that the ozone depletion index (ODP) of alternative refrigerants for refrigeration / air conditioners should be 0.0 and the global warming potential (GWP) should be as low as possible. Therefore, natural refrigerants R1270 (propylene) and R290 (propane, propane) and R152a (1,1-difluoroethane), RE170 (dimethyl ether, DME) and one of R600a (isobutane, Iso-butane) were mixed to replace the existing refrigerant.

[Table 2] shows the results of comparing the performance index of the mixed refrigerant according to the present invention with the performance index of the existing refrigerant calculated by the computerized analysis program by applying the conditions of the refrigeration / air conditioner using the existing CFC502 , [Table 3] shows the results of comparing the performance index of the mixed refrigerant according to the present invention with the performance index of the conventional refrigerant calculated by the computerized analysis program applying the conditions of use of the refrigeration / air conditioner using the existing HCFC22 will be.

[Performance Comparison of CFC502 and Alternative Mixed Refrigerants] Refrigerant Furtherance(%) COP VC (kJ / ㎥) GTD (℃) Tdis (℃) COP _diff (%) VC _diff (%) R1270 R290 R152a RE170 R600a CFC502 1.07 816 0.2 102.7 R404A 0.99 807 0.7 94.7 -7.5 -1.1 Inventive Example 1 60 40 1.35 999 2.6 115.9 26.2 22.4 Inventive Example 2 90 10 1.26 1003 0.1 112.5 17.8 22.9 Inventive Example 3 5 90 5 1.19 781 0.3 101.9 11.2 -4.3 Inventive Example 4 10 85 5 1.20 802 0.5 102.3 12.1 -1.7 Inventive Example 5 25 60 15 1.26 920 0.4 104.1 17.8 12.7 Inventive Example 6 50 50 1.35 786 6.1 121.4 26.2 -3.7 Inventive Example 7 60 40 1.33 842 4.2 119.2 24.3 3.2 Inventive Example 8 90 10 1.26 956 0.2 113.6 17.8 17.2 Inventive Example 9 10 70 20 1.25 823 0.7 104.6 16.8 0.9 Inventive Example 10 10 80 10 1.22 802 0.4 103.1 14.0 -1.7 Inventive Example 11 20 70 10 1.23 837 0.6 104.1 15.0 2.6 Inventive Example 12 70 10 20 1.28 801 6.7 109.8 19.6 -1.8

[Performance Comparison of HCFC22 and Alternative Mixed Refrigerants] Refrigerant Furtherance(%) COP VC (kJ / ㎥) GTD (℃) Tdis (℃) COP _diff (%) VC _diff (%) R1270 R290 R152a RE170 R600a HCFC22 2.88 3565 0.0 98.2 R407C 2.79 3776 6.9 90.6 -3.1 5.9 Inventive Example 13 50 50 2.93 3799 4.7 88.5 1.7 6.6 Inventive Example 14 80 20 2.73 3827 0.3 86.0 -5.2 7.3 Inventive Example 15 90 10 2.68 3847 0.1 85.9 -6.9 7.9 Inventive Example 16 20 40 40 2.84 3823 1.6 83.5 -1.4 7.2 Inventive Example 17 30 30 40 2.84 3865 2.0 83.3 -1.4 8.4 Inventive Example 18 40 50 10 2.67 3588 0.3 82.7 -7.3 0.6 Inventive Example 19 50 40 10 2.67 3651 0.2 83.3 -7.3 2.4 Inventive Example 20 50 50 2.94 3257 6.1 89.7 2.1 -8.6 Inventive Example 21 90 10 2.69 3619 0.2 86.3 -6.6 1.5 Inventive Example 22 10 70 20 2.70 3286 0.7 82.1 -6.2 -7.8 Inventive Example 23 45 40 15 2.70 3515 0.7 83.7 -6.2 -1.4 Inventive Example 24 70 15 15 2.72 3596 0.6 85.4 -5.6 0.9 Inventive Example 25 50 40 10 2.70 3304 4.2 83.1 -6.2 -7.3 Inventive Example 26 80 15 5 2.67 3527 2.0 84.9 -7.3 -1.1

* COP: coefficient of performance (Coefficient of performance, total refrigeration effect / day applied to the compressor)

* VC: Volumetric capacity

* GTD: Grading temperature difference

* T _dis : Compressor discharge temperature

* COP _diff : Performance coefficient difference between CFC502 (Table 2) and HCFC22 (Table 3)

* VC _diff : Volume difference between CFC502 (Table 2) and HCFC22 (Table 3)

Tables 2 and 3 show that the refrigerants of Examples 1 to 26 of the present invention have higher or slightly lower performance coefficients and similar volume capacities than conventional CFC502 or R404A or HCFC22 or R407C. Given that the temperature gradients of various mixed refrigerants currently commercialized are usually less than 7 ° C., the temperature gradients of these mixed refrigerants are smaller than that, so there is no problem in using them. In addition, the compressor discharge temperature of the refrigerant examples 1 to 26 of the present invention is also similar to or slightly higher than CFC502 or HCFC22, so there is no problem in using it.

Since all the refrigerants of Examples 1 to 26 of the present invention have an ozone depletion index (ODP) of 0.0 and do not destroy the ozone layer at all, they are much superior to CFC502 and HCFC22 in terms of environmental conservation. In the case of R404A or R407C, which are alternative refrigerants for CFC502 and HCFC22, they are regulated under the Kyoto Protocol due to their high global warming index. You can also reduce.

For reference, other compositions that deviate from the compositions of the present inventions described above, whether the temperature gradient is too large, the capacity and the efficiency are too low, or the compressor discharge temperature is too high, there is a problem in the actual application to the refrigeration / air conditioner, Look specifically.

[Inventive Examples 1 and 2]

As shown in Examples 1 and 2 of the present invention, when R152a exceeds 40% by weight, the temperature gradient becomes excessively large. In addition, when R1270 exceeds 90, the volume capacity becomes excessively large, which is not preferable.

[Inventive Example 3, 4, 5]

As shown in Examples 3, 4, and 5 of the present invention, when R1270 exceeds 25 in a mixed refrigerant replacing CFC502, R1270 is a material having a high vapor pressure, so that the volume capacity of the mixed refrigerant is excessively larger than that of the conventional refrigerant, so that it is suitable for the existing refrigerant. The designed compressor must be replaced. If R152a exceeds 15, the temperature gradient is increased and the compressor discharge temperature is increased, which is not preferable.

[Inventive Example 6, 7, 8, 20, 21]

As shown in Examples 6, 7, 8, 20 and 21 of the present invention, when RE170 exceeds 50% by weight, the temperature gradient of the mixed refrigerant becomes too large and at the same time the volume capacity becomes too small. Therefore, RE170 is not more than 50% by weight and at the same time R1270 is preferably included in more than 50% by weight in order to have a suitable volume capacity.

[Inventive Examples 9, 10, 11]

As shown in Examples 9, 10 and 11 of the present invention, the temperature gradient is less than 1 when the RE170 is in the range of 10 to 20% by weight, but according to the Examples 6,7 and 8 of the present invention, the temperature gradient is excessive when the RE170 is increased. Since it becomes large, RE170 in the mixed refrigerant containing R1270 and R290 is preferably not more than 20% by weight. In addition, as R1270 increases, the volume capacity increases, so that R1270 must have a volume capacity similar to that of a conventional refrigerant when it does not exceed 20% by weight.

[Inventive Example 12]

As shown in Example 12, when the composition ratio of R600a in the mixed refrigerant consisting of R600a, R1270 and R290 increases, the temperature gradient increases significantly. Therefore, the mixed refrigerant replacing CFC502 is not suitable because the temperature gradient becomes larger than 6.7 ° C when R600a exceeds 20% by weight, as shown in Example 12 of the present invention. In addition, even if the ratio of the remaining R1270 and R290 except for R600a changes, the volumetric capacity of the mixed refrigerant has an appropriate value.

[Inventive Example 13, 14, 15]

As shown in Examples 13, 14 and 15 of the present invention, when R152a exceeds 50% by weight, the temperature gradient becomes excessively large. In addition, the R1270 over 90 is not appropriate because the volume capacity is excessively large and the coefficient of performance is reduced.

[Inventive Examples 16, 17, 18, 19]

As shown in Examples 16, 17, 18 and 19 of the present invention, when R152a exceeds 40% by weight, the temperature gradient becomes large. As R1270 increases, the coefficient of performance decreases, so that R1270 should not exceed 50% by weight to prevent excessive degradation of the coefficient of performance. However, R1270 is preferably 20% by weight or more so that the volume capacity does not become too small.

[Inventive Examples 22, 23, 24]

As shown in Examples 22, 23 and 24 of the present invention, the temperature gradient is less than 1 when RE170 is in the range of 15 to 20% by weight, but according to the Examples 20 and 21 of the present invention, the temperature gradient becomes excessively large when RE170 is increased. Therefore, in the mixed refrigerant containing R1270 and R290, RE170 is preferably not more than 20% by weight. In addition, as shown in Examples 22, 23, and 24 of the present invention, as R1270 increases, the volume capacity increases. R1270 shows an appropriate value of 7096% by volume and a volume capacity of 3596. It is desirable not to exceed%.

[Inventive Examples 25 and 26]

As shown in Examples 25 and 26 of the present invention, when the composition ratio of R600a is increased in the mixed refrigerant consisting of R600a, R1270 and R290, the temperature gradient is greatly increased. Therefore, in the mixed refrigerant replacing HCFC22, as shown in Example 25 of the present invention, it is preferable that the R600a does not exceed 10% by weight. In addition, even if the ratio of the remaining R1270 and R290 except for R600a changes, the volumetric capacity of the mixed refrigerant has an appropriate value.

According to the mixed refrigerant for R502 and R22 and the refrigeration system using the same according to a preferred embodiment of the present invention having the above-described configuration as a material constituting the mixed refrigerant, ozone layer destruction index of 0.0 and very low global warming index of propylene, propane, Since 1,1-difluoroethane, dimethyl ether and isobutane are used, there is a remarkable effect of preventing the global ozone layer destruction and global warming even when the refrigerant is leaked or discarded.

In addition, the mixed refrigerant according to the present invention is mixed with propylene, propane, 1,1-difluoroethane, dimethyl ether and isobutane in an appropriate composition to the refrigerant R502 or R22, which is a refrigerant in which the vapor pressure or volumetric capacity of the mixed refrigerant is conventionally used. Since it is similar, it can be applied directly without replacing the compressor or modifying the existing refrigeration system, thereby reducing the time and economic cost.

In the mixed refrigerant of the present invention, since the temperature gradient is very small by mixing the proper composition, there is almost no change in the refrigerant pressure due to the phase change of the refrigerant, so that the refrigeration system can be used stably, and the separation of the composition during the outflow of the refrigerant is prevented. It works.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

1 is a block diagram of a general refrigeration / air conditioner used in the present invention.

Explanation of symbols on main parts of drawing

Qc: direction of heat flow in the condenser (from refrigerant to air)

Qe: Heat flow direction from the evaporator (air to refrigerant)

TS1: evaporator air inlet temperature, TS7: evaporator air outlet temperature

TS3: condenser air outlet temperature, TS6: condenser air inlet temperature

Evaporator: Compressor: Compressor

Condenser: Condenser, Expansion Valve: Expansion Valve

Claims (13)

A mixed refrigerant comprising 1 to 99 parts by weight of R1270 (propylene), 1 to 98 parts by weight of R290 (propane), and 1 to 50 parts by weight of R152a (1,1-difluoroethane) in a mixed refrigerant for refrigeration / air conditioner. The method of claim 1, A mixed refrigerant consisting of 1 to 25 parts by weight of R1270 (propylene), 60 to 90 parts by weight of R290 (propane), and 1 to 15 parts by weight of R152a (1,1-difluoroethane) in a mixed refrigerant for refrigeration / air conditioner. The method of claim 1, A mixed refrigerant consisting of 20 to 50 parts by weight of R1270 (propylene), 30 to 50 parts by weight of R290 (propane), and 1 to 40 parts by weight of R152a (1,1-difluoroethane) in a mixed refrigerant for refrigeration / air conditioner. delete delete delete delete delete delete delete delete delete A refrigeration / air conditioner using any one of mixed refrigerants selected from claim 1.