KR100499259B1 - R12 substitute mixed refrigerant and refrigeration system using thereof - Google Patents

Abstract

The present invention relates to a mixed refrigerant for replacing R12 used in a vapor compression refrigerator or an air conditioner and a refrigeration system using the same. More specifically, the present invention does not replace an existing refrigeration system without causing ozone layer destruction and global warming. The present invention relates to a mixed refrigerant composed by selectively combining 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, dimethyl ether, and isobutane, and a refrigeration system using the same. Mixed refrigerant according to a preferred embodiment of the present invention is 1 to 78 parts by weight of R134a (1,1,1,2-tetrafluoroethane), 1 to 78 parts by weight of RE170 (dimethyl ether), R600a (isobutane) 21 to It consists of 99 parts by weight.

Description

R12 SUBSTITUTE MIXED REFRIGERANT AND REFRIGERATION SYSTEM USING THEREOF}

The present invention is a material that can be used as a refrigerant (referred to as R) in a vapor compression refrigeration / air conditioner, namely '1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, dimethyl ether (Hereinafter referred to as DME) and isobutane and a mixed refrigerant and a refrigeration system using the same. More specifically, it is a dichlorodifluoromethane (CCl ₂₎ which has been widely applied to household refrigerators and automobile air conditioners. F _2, below relates to a mixed refrigerant, and a refrigeration system using the same which can replace referred to as R12 or CFC12).

Until now, chlorofluorocarbons (hereinafter referred to as CFCs) and hydrochlorofluorocarbons (hereinafter referred to as HCFCs) derived from methane or ethane have been mainly used as refrigerants for refrigerators, air conditioners, and heat pumps. In automotive air conditioners, CFC12 having a boiling point of -29.75 ° C and a molecular mass of 120.93kg / kmol has been 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. CFC12 has a high Ozone Depletion Potential (ODP) of 0.9, which is now obsolete in developed countries in accordance with the Montreal Protocol, and so most countries around the world try to use alternative refrigerants with an ODP of 0.0. Doing.

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 CFC12 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.

In DuPont, USA, MP39 (53% R22 / 34% R124 / 13% R152a), MP66 (61% R22 / 28% R124 / 11% R152a), consisting of HCFC and hydrofluorocarbon (HFC) Has developed and marketed three-way mixed refrigerants. Monroe Air Tech has developed and marketed three-way mixed refrigerants called GHG-X3 (65% R22 / 4% R600a / 31% R142b) consisting of HCFC and isobutane. Several companies are also commercializing a variety of mixed refrigerants. However, most of these refrigerants have an ozone depletion index (ODP) greater than 0.0, which is harmful to the global environment and lower in energy efficiency than CFC12, which may accelerate the indirect effects of global warming. In the long term, it is not a suitable substitute.

The present invention has been made to solve the above problems of the prior art, an object of the present invention is 1,1,1,2-tetrafluoroethane, 1,1-di which is a substance that does not cause ozone layer destruction and global warming By using a combination of fluoroethane, dimethyl ether and isobutane in an appropriate composition ratio to provide a mixed refrigerant and a refrigeration system using the same that can be applied directly without replacing or significantly modifying the existing refrigeration system.

The object of the present invention described above is 1 to 78 parts by weight of R134a (1,1,1,2-tetrafluoroethane), 1 to 78 parts by weight of RE170 (dimethyl ether), and R600a (iso) in a mixed refrigerant for refrigeration / air conditioner. Butane) may be achieved by a mixed refrigerant consisting of 21 to 99 parts by weight.

In order to achieve the above object, 1 to 20 parts by weight of R134a (1,1,1,2-tetrafluoroethane), 60 to 70 parts by weight of RE170 (dimethyl ether), and R600a (iso) in a mixed refrigerant for a refrigerator / air conditioner Butane) is preferably composed of 21 to 30 parts by weight.

The above object of the present invention is a mixed refrigerant consisting of 1 to 99 parts by weight of R134a (1,1,1,2-tetrafluoroethane) and 1 to 99 parts by weight of RE170 (dimethyl ether) in a refrigerant mixture for refrigeration and air conditioning. Can also be achieved.

In addition, the object of the present invention described above is 1 to 98 parts by weight of R152a (1,1-difluoroethane), 1 to 98 parts by weight of RE170 (dimethyl ether), R600a (isobutane) in a refrigerant mixture for refrigeration / air conditioning It can also be achieved by a mixed refrigerant consisting of to 50 parts by weight.

In order to achieve the above object, 1 to 10 parts by weight of R152a (1,1-difluoroethane), 40 to 80 parts by weight of RE170 (dimethyl ether), and 1 to R600a (isobutane) in a mixed refrigerant for a refrigerator / air conditioner It is preferable that it is comprised by 50 weight part.

In addition, the object of the present invention described above is R152a (1,1-difluoroethane) 55-64%, R600a (isobutane) 36-45% or R152a (1,1-difluoro) in a mixed refrigerant for refrigeration / air conditioner Roetan) 76-95%, R600a (isobutane) 5-24% can also be achieved by a mixed refrigerant.

The above object of the present invention is a mixed refrigerant consisting of 60 to 89 parts by weight of R134a (1,1,1,2-tetrafluoroethane) and 11 to 40 parts by weight of R600a (isobutane) in a refrigeration / air conditioner mixed refrigerant. Can also be achieved.

The above object of the present invention can also be achieved by a refrigeration / air conditioner using the mixed refrigerants.

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 R12 replacement refrigerant and the refrigeration system using the same according to a preferred embodiment of the present invention.

The present invention is a material that can be used as a refrigerant (referred to as R) in a vapor compression refrigeration / air conditioner, namely '1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, dimethyl ether And a mixed refrigerant consisting of a selective combination of isobutane and a refrigeration system using the same, and more specifically, to replace dichlorodifluoromethane (CCl ₂ F ₂ ), which has been widely applied to household refrigerators and automobile air conditioners. 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 other alternative refrigerants, and at the same time, it can be used as an alternative refrigerant of CFC12 without greatly modifying the existing compressor. It is to provide a mixed refrigerant and a refrigeration system using the same.

More specifically, the present invention relates to R134a (1,1,1,2-tetrafluoroethane) or R152a (1,1-difluoroethane) and RE170 (dimethyl ether, DME) and R600a (isobutane, Iso-butane). It is related with the mixed refrigerant comprised by combining selectively. 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 is close to the coefficient of performance (COP) and volume capacity (VC) of CFC12. Yields a value.

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 present inventors have determined that the ozone depletion index (ODP) of the alternative refrigerant for refrigeration / air conditioner must be 0.0 and the global warming potential (GWP) should be as low as possible. R134a (1,1,1,2-tetrafluoroethane) R152a (1,1-difluoroethane) and RE170 (dimethyl ether, DME) and R600a (isobutane, Iso-butane) were mixed to replace the existing refrigerant.

[Table 2] shows the performance index of the mixed refrigerant according to the present invention and the mixed refrigerant according to the comparative example calculated by the computational analysis program by applying the use conditions of the conventional CFC12 refrigeration / air conditioner The results are compared with.

[Comparison of the Performance of CFC12 and Alternative Mixed Refrigerants] Refrigerant Furtherance(%) COP VC (kJ / ㎥) GTD (℃) Tdis (℃) COP _diff (%) VC _diff (%) R134a R152a RE170 R600a CFC12 1.55 809 0.0 103.4 HFC134a 100 1.50 743 0.0 97.0 -3.2 -8.2 Inventive Example 1 10 90 1.67 761 0.1 114.8 7.7 -5.9 Inventive Example 2 70 30 1.61 791 0.1 104.4 3.9 -2.2 Inventive Example 3 90 10 1.54 770 0.3 99.7 -0.6 -4.8 Inventive Example 4 10 60 30 1.72 835 0.6 99.5 11.0 3.2 Inventive Example 5 10 70 20 1.71 832 0.3 104.1 10.3 2.8 Inventive Example 6 20 60 20 1.71 849 0.5 102.2 10.3 4.9 Inventive Example 7 20 70 10 1.69 821 0.4 107.6 9.0 1.5 Inventive Example 8 50 50 1.75 781 3.2 93.8 12.9 -3.5 Inventive Example 9 90 10 1.73 827 0.4 110.6 11.6 2.2 Inventive Example 10 10 60 30 1.72 831 0.4 100.9 11.0 2.7 Inventive Example 11 10 40 50 1.73 769 2.2 95.2 11.6 -4.9 Inventive Example 12 10 80 10 1.71 807 0.2 110.6 10.3 -0.2 Inventive Example 13 60 40 1.74 897 5.3 88.0 12.3 10.9 Inventive Example 14 70 30 1.70 952 2.3 87.3 9.7 17.7 Inventive Example 15 90 10 1.60 911 0.6 92.2 3.2 12.6 Comparative Example 1 10 90 1.5 433 5.2 60 - - Comparative Example 2 20 80 1.57 519 8.1 63 - - Comparative Example 3 30 70 1.64 619 9.2 66 - -

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 factor difference compared to CFC12

VC _diff : Volumetric difference compared to CFC12

Table 2 shows that the refrigerants of Examples 1 to 15 of the present invention have higher or similar performance coefficients and similar volume capacities than conventional CFC12 or R134a. In addition, since the temperature gradient of the mixed refrigerants is much smaller than the temperature gradient of the mixed refrigerants currently commercialized, there is no problem in using them. In addition, since the compressor discharge temperature of the refrigerants of Examples 1 to 15 of the present invention is also similar to that of CFC12, there is no problem to use.

Since all the refrigerants of Examples 1 to 15 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 CFC12 in terms of environmental conservation. In addition, R134a, an alternative to CFC12, is regulated under the Kyoto Protocol due to its high global warming potential. Therefore, the use of refrigerants with low global warming potential, such as R152a, DME or Isobutane, reduces the use of HFCs and reduces global warming. You can.

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 Example 1, 2, 3]

As shown in Examples 1, 2, and 3 of the present invention, the mixed refrigerant composed of R134a and RE170 has an appropriate grade coefficient, volume capacity, and temperature gradient at almost all composition ratios of R134a and RE170. However, as the ratio of RE170 increases, the compressor discharge temperature increases, so considering the compressor discharge temperature, it is desirable to reduce the ratio of RE170.

[Inventive Example 4, 5, 6, 7]

As shown in Examples 4, 5, 6, and 7 of the present invention, since the discharge temperature of the compressor increases and the volume capacity decreases as the ratio of RE 170 increases in the mixed refrigerant, the RE 170 is preferably 60 to 70% by weight. When the ratio of R134a increases, the volumetric capacity of the mixed refrigerant increases, so that R134a is preferably 20% by weight or less. Increasing R600a increases the volumetric capacity and lowers the compressor discharge temperature. Therefore, in order for the mixed refrigerant to have an appropriate volume capacity and a compressor discharge temperature, R600a is preferably in the range of 21 to 30% by weight.

[Inventive Examples 8 and 9]

As shown in Examples 8 and 9 of the present invention, when the ratio of R152a increases and the ratio of R600a decreases in the mixed refrigerant composed of R152a and R600a, the temperature gradient decreases and the volumetric capacity increases. Therefore, in order to have a volume capacity similar to that of the existing refrigerant and to minimize the temperature gradient, R152a is preferably included in more than 55% by weight and R600a is less than 45% by weight.

[Inventive Examples 10, 11, 12]

As shown in Examples 10, 11, and 12 of the present invention, the temperature gradient increases as the ratio of R600a increases in the mixed refrigerant, and the volume capacity decreases when it exceeds or falls below 30% by weight of R600a. Therefore, R600a is preferably 50% by weight or less. If the proportion of RE170 in the mixed refrigerant exceeds or exceeds 60% by weight, the volumetric capacity decreases and the compressor discharge temperature increases as the ratio of RE170 increases. Therefore, considering the compressor discharge temperature and volumetric capacity, the ratio of RE170 in the mixed refrigerant is preferably in the range of 40 to 80% by weight. Since the increase in R152a increases the volumetric capacity and increases the compressor discharge temperature, the ratio of R152a in the mixed refrigerant is preferably 10% by weight or less.

[Inventive Examples 13, 14, 15 and Comparative Examples 1, 2, 3]

As shown in Examples 13, 14, 15 and Comparative Examples 1, 2, and 3, in a mixed refrigerant composed of R134a and R600a, when the ratio of R134a is small and the ratio of R600a is large, the volumetric capacity becomes excessively small and the temperature gradient is too large. It is not suitable to grow big. Therefore, it is preferable that R134a is 60 weight% or more and R600a is 40 weight% or less.

It is to be noted that the term "refrigeration system" used throughout the specification of the present invention is used in the meaning of a refrigerator / air conditioner, unless otherwise specified, that both are used in the same meaning.

According to the mixed refrigerant for R12 replacement and the refrigeration system using the same according to a preferred embodiment of the present invention having the above-described configuration, as the material constituting the mixed refrigerant, the ozone layer destruction index is 0.0 and the global warming index is very small 1,1,1, Since 2-tetrafluoroethane, 1,1-difluoroethane, dimethyl ether and isobutane are used, there is a remarkable effect of preventing 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 a mixture of 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, dimethyl ether and isobutane in an appropriate composition, the vapor pressure or volumetric capacity of the mixed refrigerant is Since it is similar to the used R12 refrigerant, 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: Inflator

Claims (8)

delete delete delete A mixed refrigerant consisting of 1 to 98 parts by weight of R152a (1,1-difluoroethane), 1 to 98 parts by weight of RE170 (dimethyl ether), and 1 to 50 parts by weight of R600a (isobutane) in a mixed refrigerant for refrigeration / air conditioner. The method of claim 4, wherein A mixed refrigerant consisting of 1 to 10 parts by weight of R152a (1,1-difluoroethane), 40 to 80 parts by weight of RE170 (dimethyl ether), and 1 to 50 parts by weight of R600a (isobutane) in a mixed refrigerant for a refrigerator / air conditioner. Mixed refrigerants consisting of 55-64% of R152a (1,1-difluoroethane) and 36-45% of R600a (isobutane) in refrigeration / air conditioning refrigerants. A mixed refrigerant comprising R152a (1,1-difluoroethane) 76-89% and R600a (isobutane) 11-24% in a refrigeration / air conditioning mixed refrigerant. A refrigeration / air conditioner using any one of mixed refrigerants selected from claim 4.