KR20140006677A - Composition of refrigerant mixture containing chlorodifluoromethane and tetrafluoroethane - Google Patents

Abstract

The present invention relates to a mixed refrigerant composition comprising chlorodifluoromethane (R22 or HCFC22) and tetrafluoroethane (R134a), more specifically 49 to 51% by weight of chlorofluorocarbon and 49 to 51% by weight of hydrofluorocarbon. It relates to a mixed refrigerant composition, characterized in that the composition. The mixed refrigerant of the present invention may have the effect of reducing power consumption while maintaining the discharge temperature by improving the performance of the conventional HCFC22.

Description

Mixed refrigerant composition comprising chlorodifluoromethane and tetrafluoroethane {COMPOSITION OF REFRIGERANT MIXTURE CONTAINING CHLORODIFLUOROMETHANE AND TETRAFLUOROETHANE}

The present invention relates to a mixed refrigerant composition comprising chlorodifluoromethane (R22 or HCFC22) and tetrafluoroethane (R134a).

Mechanical cooling devices and related heat transfer devices such as heat pumps and air conditioners utilizing cooling liquids are well known in the industrial, commercial and household sectors. Chlorofluorocarbons (CFCs) were developed as refrigerants for these systems in the 1930s. However, the impact of CFCs on the stratospheric ozone layer since the 1980s has been a significant focus of attention. In 1987, many governments signed the Montreal Protocol for Global Environmental Protection, which establishes a fourth timetable to phase out CFC products. Subsequent revisions to these protocols promoted the phase-out of these CFCs and also scheduled the phase-out of HCFCs. Thus, there is a need for non-combustible, non-toxic substitutes to replace these CFCs and HCFCs. In response to this need, an industry has developed for a number of hydrofluorocarbons (HFCs) with zero ozone depletion potentials.

Such as difluoromethane (HFC-32), 1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1,1,2,2-pentafluoroethane (HFC-125a) Hydrofluorocarbons are essentially free of Ozone Depletion Potential (ODP) and, therefore, have been found to be acceptable refrigerants, and in some cases as potential blowing agents in the manufacture of plastic foams, as cleaning solvents, and as propellants for aerosol sprays. .

Meanwhile, in order for a material to be useful as a mixed refrigerant of an existing refrigerant, it must first have a similar coefficient of performance (hereinafter referred to as COP) and an evaporator capacity (hereinafter referred to as QE). Here, the coefficient of performance (COP) means the total refrigeration effect compared to the work applied to the compressor. The larger the COP, the better the energy efficiency of the air conditioner / heat pump. In addition, to use the compressor without major modifications, the mixed refrigerant must have a vapor pressure comparable to that of conventional refrigerants, ultimately providing similar evaporator capacities. The characteristics of mixed refrigerants are that they can be formulated so that their coefficients of performance are comparable to those of conventional refrigerants, while at the same time providing an evaporator capacity (QE) similar to that of conventional refrigerants, thereby eliminating the need for major modifications to the compressor. Because of this property, several mixed refrigerants have been proposed as substitutes for HCFC22 in the last few years (see Korean Patent No. 10-0492172, Korean Patent No. 10-0582453, and Korean Patent No. 10-0696806). However, most conventional mixed refrigerants are energy efficient Since it is lower than R22, the compressor discharge temperature is high, and it is composed of HFCs (hydrofluorinated carbon) which causes global warming, there is a problem that it is difficult to use in the long term in terms of environmental protection and energy conservation.

Representative mixed refrigerants as substitutes for HCFC-22 include HFC-407C and HFC-410A, which are recommended by the American Society of Refrigeration and Air Conditioning (ASHRAE). HFC-407C is a refrigerant composition in which HFC-32 / 125 / 134a is mixed at 23/25/52 wt% and HFC-410A is a refrigerant composition in which HFC-32 / 125 is mixed at 50/50 wt%.

In addition, US Patent No. 5,080,823 is HFC-143a / propane, US Patent No. 5,211,867 is HFC-125 / 143a, US Patent No. 5,234,613 is HFC-32 / propane, US Patent No. 5,236,611 is PFC-218 / HFC-143a , US Patent No. 5,290,466, HFC-32 / 134a / 134, US Patent No. 5,340,490, HFC-23 / CO 2 and HFC-23 / 116 / CO2, US Patent No. 5,403,504, HFC-125 / 32, US Patent 5,429,740 is HFC-23 / 134a, US Pat. No. 5,538,660 is HFC-32 / HFC-134a / FC-41 and HFC-32 / HFC-134a / PFC-218, US Pat. No. 5,643,492 is HFC-32 / A mixed refrigerant composition comprising 125 / 134a is disclosed.

In addition, Japanese Patent Application Laid-Open No. 3-172386, HFC-32 / 125 / 143a, H3-370594, HFC-23 / 125 / 134a, and H3-370593, HFC-23 / 125/32, H3- 170591 is HFC-23 / 143a / 134a, H3-170590 is HFC-125 / 134a / 32, H3-370589 is HFC-23 / 143a / 152a, H3-370588 is HFC-125 / 143a / 134a, flat 3-170585, HFC-32 / 125 / 134a, flat 3-170584, HFC-23 / 134a / 152a, flat 3-170583, HFC-125 / 143a / 32, flat 4-222893 HFC-32 / 125, HF 4-154887 HFC-134 / 152a, H5-117645 HFC-23 / 134a / propane H5-176 / HFC-125 / 134a / propane H6 65561 is HFC-23 / 152a / PFC-218, H6-128872 HFC-32 / PFC-218, H6-620433 HFC-32 / 125 / RC-318, H7-173462 HFC -143a / 125 / 134a / heptane, PFC 8-176537, PFC-218 / RC-270 / HFC-152a, Pyeong 8-151569, Propane / RC-270 / HFC-134a, Pyeong 8-127767 -32 / 134a / RC-318, HFC-32 / 134a / 125 / isobutane for flat 9-25480, HFC-134a / isobutane for flat 9-59611, HFC-32 / 152a for flat 9-208941 / 125 / RC-270, H9-221664 are horns consisting of HFC-125 / 143a / 134a / RC-270 The combined refrigerant composition is disclosed.

And, Korean Patent Publication No. 91-9902 is HFC-23 / 32 / 152a, HFC-23 / 125 / 152a, HFC-32 / 143a / 152a, HFC-125 / 143a / 152a, HFC-32 / 125 / 125a , HFC-23 / 143a / 152a, Korean Patent Publication No. 91-9903 discloses HFC-23 / 32/134, HFC-23 / 32 / 134a, HFC-23 / 125/134, HFC-32 / 125/134, HFC-23 / 143a / 134a, HFC-125 / 143a / 134a, HFC-125 / 143a / 134, Korean Patent Publication No. 96-4485, HFC-32 / 23 / 134a, Korean Patent Publication No. 96-701168 HFC-227ea / HFC-152a, Korean Patent Publication No. 97-704853, discloses a mixed refrigerant composition consisting of HFC-134a / HCFC-124 / butane.

The present inventors have come to invent the mixed refrigerant composition of the present invention to reduce the power consumption while maintaining the discharge temperature in the conventional air conditioner for HCFC22.

An object of the present invention is to provide a mixed refrigerant composition having improved performance over refrigerant chlorodifluoromethane (CHClF 2, hereinafter referred to as R 22 or HCFC 22), which has been widely used in conventional air conditioners or heat pumps.

In order to achieve the above object in one embodiment of the present invention provides a mixed refrigerant composition, characterized in that the composition is composed of 45 to 55% by weight of chlorofluorocarbons and 45 to 55% by weight of hydrofluorocarbons.

In the present invention, the composition may be composed of 50% by weight of chlorofluorocarbon and 50% by weight of hydrofluorocarbon, the chlorofluorocarbon is chlorodifluoromethane, dichlorodifluoromethane, chloro Trifluoromethane, chlorodifluoromethane, 1,1,1,2-tetrafluoro-2,2-dichloroethane, 1,1,1,2,2-pentafluoro-2-chloroethane and 1 It may be characterized in that any one selected from the group consisting of 1,1,2 tetrafluoro-1-chloroethane, the chlorofluorocarbon may be characterized in that chlorodifluoromethane. In addition, the hydrofluorocarbon is difluoromethane (HFC-32), 1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1,1,2,2-pentafluoroethane (HFC-125a) may be any one selected from the group consisting of, the hydrofluorocarbon may be characterized in that 1,1,1,2-tetrafluoroethane (HFC-134a) have. In addition, the mixed refrigerant composition may be composed of 49 to 51% by weight of chlorofluorocarbon and 49 to 51% by weight of hydrofluorocarbon.

"Chlorofluorocarbon" in the present invention includes dichlorofluoromethane (CCl ₂ F ₂ ), among other compounds of similar chemical structure. For example, chlorofluorocarbons are molecules formed of chlorine, fluorine, and carbon atoms and have CC bonds depending on the Cl-C and FC bonds and the number of carbon atoms in the species. As used herein, “fluorocarbon” refers to tetrafluoromethane (CF ₄ ), perfluoroethane (C ₂ F ₆ ), perfluoropropane (C ₃ F ₈ ), perfluoro, among other compounds of similar chemical structure. Robutane (C ₄ F ₁₀ ), perfluoropentane (C ₅ F ₁₂ ), perfluoroethene (C ₂ F ₄ ), perfluoropropene (C ₃ F ₆ ), perfluorobutene (C ₄ F ₈ ), perfluoropentene (C ₅ F ₁₀ ), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), and octafluorocyclobutane (cyclo-C ₄ F ₈ ). Fluorocarbons include molecules formed of fluorine and carbon atoms, and have a CC bond and a CC bond that depends on the number of carbon atoms of the species.

In the present invention, "hydrofluorocarbon" refers to fluoroform (CHF3), pentafluoroethane (C ₂ HF ₅ ), tetrafluoroethane (C ₂ H ₂ F ₄ ), heptafluoro among other compounds of similar chemical structure Lopropanane (C ₃ HF ₇ ), Hexafluoropropane (C ₃ H ₂ F ₆ ), Pentafluoropropane (C ₃ H ₃ F ₅ ), Tetrafluoropropane (C ₃ H ₄ F ₄ ), Nonnafluor Robutane (C ₄ HF ₉ ), Octafluorobutane (C ₄ H ₂ F ₈ ), Undecafluoropentane (C ₅ HF ₁₁ ), Methyl fluoride (CH ₃ F), Difluoromethane (CH ₂ F ₂ ), ethyl fluoride (C ₂ H ₅ F), difluoroethane (C ₂ H ₄ F ₂ ), trifluoroethane (C ₂ H ₃ F ₃ ), difluoroethane (C ₂ H ₂ F ₂ ), trifluoroethene (C ₂ HF ₃ ), fluoroethene (C ₂ H ₃ F), pentafluoropropene (C ₃ HF ₅ ), tetrafluoropropene (C ₃ H ₂ F _4), trifluoromethyl propene _{(C 3 H 3 F 3)} , difluoro-propene _{(C 3 H 4 F 2)} , a heptafluoro-butene (C ₄ HF _7), A four-fluoro-butene (C ₄ H ₂ F ₆₎ and nona-fluoro-pentene and a (C ₅ HF _9). Hydrofluorocarbons are molecules comprising H, F, and C atoms and have CC bonds that depend on the HC and FC bonds and the number of carbon atoms of the species.

Mixed component refrigerants can be used in cooling systems. Embodiments of the mixed component refrigerants described above are particularly useful in low temperature cooling systems that provide refrigeration at temperatures not higher than 283 K (10 ° C.). For example, the embodiments of the mixed component refrigerants described above may be used in low temperature cooling systems that provide refrigeration at temperatures not exceeding 223K (-50 ° C), such as refrigeration temperatures of 100K to 223K (-173 ° C to -50 ° C). Can be useful. In another embodiment, the embodiments of the mixed component refrigerants described above are cryogenic cooling systems that provide refrigeration at temperatures no greater than 90 K (-183 ° C.), such as 4 K to 90 K (-265 ° C. to −183 ° C.) refrigeration temperatures. Can be useful for To achieve the purpose of this publication, "low temperature" is used to mean a temperature not exceeding 283K, "very low temperature" is used to mean a temperature of 90K to 223K, and "cryogenic temperature" means a temperature of 4K to 90K. It is used to For clarity, "cold component" or "cryogenic gas" does not indicate the use of "cold temperature". These terms are independent. The primary advantage of this application is that it can be intended for very low temperature and cryogenic cooling applications. However, it is foreseeable that the advantages of such applications provide advantages in low temperature applications and even heating temperature applications and are included for this reason.

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.

In the present invention, the mixed refrigerant composition is applied to a refrigeration system comprising a compressor, a condenser, an expansion valve, and an evaporator, and compares / reviews the operating pressure, power consumption per hour, discharge temperature, suction temperature, and the like.

When selecting an alternative refrigerant, it is desirable to use a nonflammable non-toxic refrigerant (the acceptable exposure limit is greater than 400 ppm).

Conventional very low temperature systems used flammable components to handle oil. The oil used in a system having a very low temperature using a chlorinated refrigerant has good miscibility with high temperature boiling components that can be liquefied at room temperature when pressurized. Low temperature boiling HFC refrigerants such as R-23 are not miscible with these oils and are not easily liquefied until they reach the low temperature part of the cooling process. This immiscibility causes compressor oil to separate and freeze, resulting in system failure due to blockage of pipes, strainers, valves or throttling devices. Ethane was added to the refrigerant mixture to give miscibility at such low temperatures. Unfortunately, ethane is flammable, can limit the consumer's level of satisfaction, and can add system control requirements, facility requirements and costs. Therefore, it is desirable to remove all combustible components.

In addition, the use of toxic refrigerants may limit the consumer's satisfaction range and add additional system control requirements, equipment requirements and costs. The acceptable exposure limit (PEL) is the maximum or maximum concentration of chemical that an operator can be exposed to under OSHA regulations. In the case of mixed refrigerants, a PEL of less than 400 ppm of any component is considered toxic and threatens the health of individuals who may be exposed to the refrigerant, such as work technicians. Therefore, it is advantageous to use a refrigerant with a PEL of components greater than 400 ppm.

Another requirement is to develop a mixture of refrigerants that do not freeze from the refrigerant mixture. A “freeze” state in a cooling system is when the viscosity becomes very high to the extent that one or more refrigerant components or compressor oil do not solidify or flow. In normal operation of the cooling system, the suction pressure decreases with decreasing temperature. When a freezing condition occurs, the suction pressure drops further, creating positive feedback and further decreasing the temperature, which intensifies the freezing state. What is needed is a method of preventing freezing in mixed refrigerant cooling systems. The usable HFC refrigerant has a higher freezing point temperature than the HCFC and CFC refrigerants to be replaced. Since these refrigerants are rather new and it is not uncommon to use them at very low temperatures, no one has the information to predict the freezing behavior of a mixture of these new refrigerants.

Another problem with the use of fluorinated hydrocarbons (HFC) is that polyolesters (POE) (1998 ASHRAE Refrigeration Handbook, Chapter 7, p. 7.4) can be used with HFC refrigerants because these refrigerants are not miscible in alkylbenzene oils. , American Society of Heating, Refrigeration and Air Conditioning Engineers. Proper oil selection is essential for systems with very low temperatures, because the oil not only lubricates the compressor well, but also does not freeze from the refrigerant at very low temperatures.

Typically, changes in refrigerants in the cooling industry require changes in hardware elements such as compressors or valves. As a result, changes in the refrigerant can result in expensive equipment modifications and consequent shutdowns. What is needed is a method of using existing cooling installations with recently developed HFC mixed refrigerants that can be used with existing hardware and materials. This is further complicated by the fact that very low temperature systems must operate in several different modes. In such a system the starting process is also not simple because many refrigerants are liquid in steady state operation, but gaseous when the system is at room temperature. In addition, in the case of severe changes in operation, such as rapid defrosting, the refrigerant must be properly mixed in order to allow the system to operate without exceeding operating temperature or pressure limits.

The mixed refrigerant having the configuration of the present invention has the effect of reducing the power consumption while maintaining the discharge temperature by improving the performance of the existing HCFC22. In addition, the durability of the compressor can be improved by reducing the failure caused by the high pressure in the summer of the air conditioner using the R22 refrigerant.

1 is a graph showing the power consumption per hour according to the mixed refrigerant composition ratio.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention in more detail and that the scope of the present invention is not limited by these embodiments in accordance with the gist of the present invention .

Example

Example  1. Preparation of mixed refrigerant composition

Chlorodifluoromethane (CHClF 2, hereinafter referred to as R22 or HCFC22) and tetrafluoroethane (C ₂ H ₂ F ₄ , hereinafter R134a) were prepared in a mixed refrigerant having a weight ratio as shown in Table 1 below.

R22 R134a Production Example 1 20 wt% 80 wt% Production Example 2 30 wt% 70 wt% Production Example 3 40 wt% 60 wt% Production Example 4 50 wt% 50 wt% Production Example 5 60 wt% 40 wt% Production Example 6 70 wt% 30 wt% Production Example 7 80 wt% 20 wt% Control group 100 wt% 0 wt%

Example  2. Performance of Mixed Refrigerant Compositions

Using a refrigeration system consisting of a compressor, a condenser, an expansion valve and an evaporator, the performance of the composition prepared in Example 1 (Preparation Examples 1 to 7 and control) was measured and the results are shown in Table 2 below.

Furtherance(%) Operating pressure (kg / cm ² ) Power Consumption per Hour (KW) Discharge temperature (℃) Suction temperature (℃) Temperature range
(℃) R22 R134a Low pressure High pressure Production Example 1 20 80 4.4 18.8 6.64 14 26.5 12.5 Production Example 2 30 70 4.2 18.8 6.6 13.9 26.7 12.8 Production Example 3 40 60 3.5 16.2 5.1 12.2 26.5 14.3 Production Example 4 50 50 3.2 15.5 4.4 12.4 26.6 14.2 Production Example 5 60 40 3.5 16.2 5.1 12.2 26.5 14.3 Production Example 6 70 30 4.2 18.8 6.6 13.9 26.7 12.8 Production Example 7 80 20 4.4 18.8 6.64 14 26.5 12.5 Control group 100 0 4 to 6 16-20 6.2 12.4 26.6 14.2

As shown in Table 2, the mixed refrigerant of Preparation Example 4, which is a mixture of R22 and R134a in a 5: 5 weight ratio, has a low power consumption and a high pressure of the compressor without changing the discharge temperature, and the power consumption is about 1.8 compared to the control. It can be seen that the kw is reduced. That is, when the mixed refrigerant of Preparation Example 4, in which the composition of R22: R134a is 50% by weight: 50% by weight, the power consumption per hour is the lowest compared to the mixed refrigerant having the different composition ratio, showing a significant effect (Fig. 1).

For reference, in other compositions, even if the capacity is too low or the temperature gradient is large, there was a problem in actually applying to the refrigeration / air conditioner.

While the present invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. You will know. In addition, many modifications may be made to adapt a particular situation and material to the teachings of the invention without departing from the essential scope thereof. Accordingly, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention be construed as including all embodiments falling within the scope of the appended claims.

Claims (6)

Mixed refrigerant composition comprising 45 to 55% by weight of chlorofluorocarbons and 45 to 55% by weight of hydrofluorocarbons. The method of claim 1,
A mixed refrigerant composition comprising 50% by weight of chlorofluorocarbons and 50% by weight of hydrofluorocarbons. The method of claim 1,
The chlorofluorocarbons are chlorodifluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, chlorodifluoromethane, 1,1,1,2-tetrafluoro-2,2-dichloroethane, 1, Mixed refrigerant composition, characterized in that any one selected from the group consisting of 1,1,2,2-pentafluoro-2-chloroethane and 1,1,1,2 tetrafluoro-1-chloroethane. The method of claim 1,
The chlorofluorocarbon is mixed refrigerant composition, characterized in that chlorodifluoromethane. The method of claim 1,
The hydrofluorocarbons are difluoromethane (HFC-32), 1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1,1,2,2-pentafluoroethane (HFC Mixed refrigerant composition, characterized in that any one selected from the group consisting of -125a). The method of claim 1,
The hydrofluorocarbon is mixed refrigerant composition, characterized in that 1,1,1,2-tetrafluoroethane (HFC-134a).

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