KR100633731B1 - R12 and r134a substitute mixed refrigerant - Google Patents

Abstract

Provided are a mixture refrigerant for an air conditioner or a freezer which can replace R12 (CFC12, chlorofluorocarbon) or R134a (HFCl134a, hydrochlorofluorocarbon), and a freezing system using the mixture refrigerant. The mixture refrigerant comprises 3-29 wt% of R152a (1,1-difluoroethane); and 71-97 wt% of RE170 (dimethyl ether). The mixture refrigerant has a zero ozone depletion potential (ODP) and a lower global warming potential (GWP) and shows COP and VC similar to those of CFC12 and HFC134a.

Description

Mixed refrigerant for AL12 and AL134A {R12 AND R134a SUBSTITUTE MIXED REFRIGERANT}

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

Explanation of symbols on the main parts of the drawings

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

The present invention relates to a material that can be used as a refrigerant (referred to as R) in a vapor compression refrigeration / air conditioner, that is, 'a mixed refrigerant composed of R152a and dimethyl ether (hereinafter referred to as DME)'. The present invention relates to a mixed refrigerant that can replace R12 (CFC12) or R134a (HFC134a), which has been widely applied to household refrigerators and automobile air conditioners.

Until now, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (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 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 Ozone Depletion Potential (ODP) of CFC12 was as high as 0.9, which is now obsolete in developed countries in accordance with the Montreal Protocol. I'm trying to.

Recently, not only the ozone depletion problem but also the global warming problem began 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 manufacturers use isobutane (hereinafter referred to as R600a) hydrocarbons as refrigerants in most refrigerators instead of CFC12 or HFC134a.

Table 1 shows the environmental indices of some refrigerants.

Refrigerant Ozone Depletion Index (ODP) Global Warming Index (GWP) CFC12 0.9 8,500 HFC134a 0.0 1,300 Propane (R290) 0.0 3 or less DME (RE170) 0.0 3 or less R152a 0.0 140

(*) 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, propane, DME, R152a, and the like 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 CFC12 or HFC134a refrigerants to achieve the desired thermodynamic properties, while at the same time improving efficiency or increasing oil compatibility. To achieve. In this regard, R152a and DME 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). The volumetric capacity (VC) here refers to the refrigeration effect per unit volume, which is a factor of the size of the compressor, which is usually proportional to the vapor pressure and is in kJ / m3. 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) and MP66 (61% R22 / 28% R124 / 11% R152a) are made up 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) composed of HCFC and isobutane. Several companies are also commercializing various 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, the object of the present invention is because the Ozone Depletion Index (ODP) is 0.0 has no effect on the ozone layer in the stratosphere and the global warming index is also better than other alternative refrigerants At the same time, it provides a mixed refrigerant that can be used as an alternative to CFC12 and HFC134a without significantly modifying existing compressors.

The above-described object of the present invention is a two-way muscle azeotropic mixed refrigerant consisting of 3 to 29% by weight of R152a (1,1-difluoroethane) and 71 to 97% by weight of RE170 (dimethyl ether) in a refrigeration / air conditioner mixed refrigerant. Is achieved by.

In addition, the above object of the present invention uses a binary near-air mixture mixed refrigerant consisting of 3 to 29% by weight of R152a (1,1-difluoroethane) and 71 to 97% by weight of RE170 (dimethyl ether), evaporator, condenser, It is also achieved by a refrigeration / air conditioner comprising a compressor, expansion valve.

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 will be described in detail the configuration of the mixed refrigerant for Al 12 and Al 134 a and the refrigeration system using the same according to a preferred embodiment of the present invention.

In the present invention, since the ozone depletion index (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 and HFC134a without significantly modifying the existing compressor. To a mixed refrigerant.

Specifically, the present invention relates to a binary near azeotropic mixed refrigerant composed of R152a (1,1-difluoroethane) and dimethyl ether (DME). The alternative mixed refrigerant proposed by the present invention has an ozone depletion index (ODP) of 0.0 and a significantly lower global warming index (GWP) than other alternative refrigerants, and the coefficient of performance (COP) and volume capacity (VC) of CFC12 and HFC134a. Yields a value close to).

In order to develop an alternative mixed refrigerant, the inventors have created a program that simulates the performance of a refrigeration / air conditioner. 1 is a block diagram of a general refrigeration / air conditioner used in the present invention, and is composed of an evaporator, a condenser, a compressor, an expansion valve, and the like. The program first performed thermodynamic and heat transfer analysis of the components that make up the refrigeration / air conditioner, such as heat exchangers and compressors, and finally developed a complete program that combines all of these. One of the important factors that determine the accuracy of this 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 frozen / air conditioner program.

The inventors have determined that the ozone depletion index (ODP) of the alternative refrigerant for refrigeration / air conditioners must be 0.0 and the global warming potential (GWP) should be as low as possible. R152a (1,1-difluoroethane) and RE170 (dimethyl ether) , DME) can be used to replace the existing CFC12 and HFC134a refrigerant. Since R152a and DME refrigerants have similar vapor pressures, proper mixing of the two refrigerants will provide the user with the desired properties, and the temperature gradient, one of the most important factors in applying mixed refrigerants, can be maintained below 0.2 ° C. 2].

[Table 2] summarizes the results calculated using the computational analysis program under the refrigeration / air conditioner using the conventional CFC12 or HFC134a, showing the performance index of the standard CFC12 and the alternative mixed refrigerant proposed by the present inventors give.

[Performance Comparison of CFC12, HFC134a and Alternative Mixed Refrigerants] Refrigerant Composition (% by weight) COP VC (kJ / ㎥) GTD (℃) T _dis (℃) COP _diff (%) VC _diff (%) GWP R152a DME CFC12 1.55 809 0.0 103.4 8,500 HFC134a 1.50 743 0.0 97.0 -3.2 -8.2 1,300 Inventive Example 1 3 97 1.68 756 0.05 116.14 8.1 -6.6 7.1 Inventive Example 2 5 95 1.68 758 0.08 116.16 8.1 -6.4 9.9 Inventive Example 3 10 90 1.68 763 0.13 116.13 8.3 -5.8 16.7 Inventive Example 4 15 85 1.68 767 0.17 116.11 8.4 -5.2 23.6 Inventive Example 5 20 80 1.69 772 0.17 116.09 8.6 -4.7 30.4 Inventive Example 6 25 75 1.69 775 0.16 116.09 8.8 -4.2 37.3 Inventive Example 7 29 71 1.69 779 0.14 116.10 8.9 -3.8 42.7

※ COP: coefficient of performance (Coefficient of performance, total refrigeration effect / work done on the compressor)

VC: volumetric capacity

GTD: Gliding temperature difference

Tdis: Compressor discharge temperature

COP _diff : Performance factor difference compared to CFC12

VC _diff : Volumetric difference compared to CFC12

GWP: Global Warming Index

As shown in Table 2, it can be seen that the refrigerants of Examples 1 to 7 of the present invention have an 8% higher coefficient of performance and 4% smaller volume capacity than conventional CFC12 or R134a. In addition, since the temperature gradient of the mixed refrigerant is less than 0.2 ℃, it is significantly lower than the temperature gradient of the commercially available mixed refrigerant 7 ℃, there is no problem to use. In addition, the compressor discharge temperature of the refrigerant examples 1-7 of the present invention is also about 13 ° C. higher than the discharge temperature of the CFC12, so there is no problem in using it.

All of the refrigerants of Examples 1-7 of the present invention have an ozone depletion index (ODP) of 0.0 and thus do not destroy the ozone layer at all, and thus are much superior to CFC12 and HFC134a in terms of environmental preservation. In addition, HFC134a has a high global warming index and is regulated under the Kyoto Protocol. Therefore, if a mixed refrigerant is made around refrigerants with a low global warming index, such as R152a or DME, HFC134a may reduce global warming.

For reference, if the composition ratio of R152a in the mixed refrigerant increases, some problems occur. As shown in [Table 2], the global warming index (GWP) increases as the amount of R152a increases, and the global warming index increases to 42.7 when the amount of R152a accounts for 29% by weight. Currently, the European community and the world are trying to use only refrigerants with a GWP of 45-50 or less as long-term environmentally friendly alternative refrigerants. Therefore, in order to satisfy the condition that the global warming index is 45 or less, the composition ratio of R152a of the mixed refrigerant composed of R152a and DME is preferably 29% by weight or less. The mixed refrigerants of Examples 1 to 7 of the present invention correspond to a composition ratio of R152a of 29 wt% or less so as to satisfy the global warming index conditions.

In addition, when the amount of R152a increases, the compatibility between the refrigerant oil and the refrigerant is reduced. This is because the DME and refrigeration oil are much more compatible. In view of this, the smaller the composition of R152a in the case of the R152a / DME mixed refrigerant, the less problems are applied to the actual product.

The reason why the refrigerant and the refrigerant oil are mixed together is to protect the gear of the compressor, which is the center of the air conditioner or the refrigerator. The characteristics required for the refrigeration oil are of course good lubricity, endure at high temperatures, and should not solidify even at low temperatures.

In order to achieve the performance of the refrigeration oil, even when diluted with the refrigerant should not cause a chemical reaction, this can be said to be compatible with the refrigerant. As DME is more compatible with refrigeration oil than R152a, the greater the proportion of DME in mixed refrigerants, the better. Therefore, the mixed refrigerant of Examples 1 to 7 of the present invention was selected that the DME is 71% by weight or more.

In addition, if the composition ratio of R152a is increased in the mixed refrigerant composed of R152a and DME, the production cost of the mixed refrigerant increases. Unlike DME, R152a is an artificial compound, which is 4-5 times more expensive than DME. Therefore, inexpensive refrigerants are essential for the diffusion of environmentally friendly refrigerants. Therefore, from the economic point of view, the smaller the composition ratio of R152a in the mixed refrigerant is, the more advantageous it is.

Since the mixed refrigerant according to the present invention having the above-described structure has an ozone depletion index (ODP) of 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 existing alternative refrigerants, and at the same time without greatly modifying the existing compressor. It can be used as an alternative to CFC12 and HFC134a.

In addition, since the mixed refrigerant of the present invention has a high proportion of DME having excellent compatibility with refrigerator oil, the compatibility of the mixed refrigerant is also excellent.

Since the mixed refrigerant according to the present invention uses more than 70% by weight of DME, the manufacturing cost can be reduced, which is advantageous in spreading the use of environmentally friendly mixed refrigerant.

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.

Claims (2)

A two-dimensional near-air-to-air mixture refrigerant consisting of 3 to 29% by weight of R152a (1,1-difluoroethane) and 71 to 97% by weight of RE170 (dimethyl ether) in a mixed refrigerant for a refrigerator / air conditioner. delete

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