KR100439278B1 - The composition of refrigerant mixtures for alternating refrigerant r-502 - Google Patents

Abstract

The present invention is Freon-based mixed refrigerant R-502 [R-22 (CHF ₂ Cl) / R-115 (CF ₂ Cl-CF ₃ ) = 48.8 / 51.2 wt% ], To minimize the structural changes of the conventional refrigerator system to provide an environmentally friendly mixed refrigerant composition that can be applied immediately by adjusting the amount of refrigerant. The mixed refrigerant composition of the present invention for replacing the refrigerant R-502 includes propylene (CH ₃ -CH = CH ₂ ), which is a hydrocarbon refrigerant gas of 50 to 80% by weight, and 20 to 50% by weight of hydro based on the total refrigerant composition. Pentafluoroethane (C ₂ HF ₅ ), a fluorocarbon-based refrigerant gas, optionally selected from the group consisting of carbon dioxide (CO ₂ ), trifluoro methyliodine (CF ₃ I), and mixtures thereof In addition, it contains an additive within 5% by weight to improve the flammability of the hydrocarbon-based refrigerant and to compensate for the smooth flow of the refrigerant in the evaporator and the volumetric freezing capacity of the refrigerant.

Description

Mixed refrigerant composition for the replacement of refrigerant R-502 {THE COMPOSITION OF REFRIGERANT MIXTURES FOR ALTERNATING REFRIGERANT R-502}

The present invention minimizes the design change of the refrigerator system using the existing Freon-based mixed refrigerant R-502 [R-22 (CHF ₂ Cl) / R-115 (CF ₂ Cl-CF ₃ ) = 48.8 / 51.2% by weight]] It has excellent volume freezing capability to apply drop-in just by adjusting the amount of refrigerant, and has the same level of R-502 refrigerant and vapor pressure characteristics, and minimizes temperature gradient during evaporation and condensation in the refrigerating cycle. The present invention relates to a refrigerant composition mainly used in environmentally friendly home and industrial refrigerators, having an approximate azeotrope characteristic for promoting the convenience of use and minimizing the impact on the global ozone layer destruction and the global warming index. More specifically, propylene (CH ₃ -CH = CH ₂ ), which is a hydrocarbon refrigerant gas of 50 to 80% by weight, and pentafluoro, which is 20 to 50% by weight of hydrofluorocarbon refrigerant gas, based on the total refrigerant composition. Contains ethane (C ₂ HF ₅ ) and is optionally selected from the group consisting of carbon dioxide (CO ₂ ), trifluoro methyliodine (CF ₃ I) and mixtures thereof, to improve the flammability of hydrocarbon-based refrigerants And a composition of a mixed refrigerant for replacing a freon-based mixed refrigerant R-502, which further contains an additive within 5% by weight for supplementing the smooth flow of the frozen oil in the evaporator and the volume freezing capacity of the refrigerant. .

The refrigeration cycle consists of a compressor, a condenser, an evaporator, an expansion valve, a dryer, an oil separator, a liquid separator, etc. The refrigerator uses the second law of thermodynamics to cause the compressor to perform certain tasks. Its purpose is to absorb heat from a low heat source and transfer it to a high heat source, where the temperature is high. Is compressed by high-pressure and high-pressure gas in the compressor, cooled again in the condenser, and reduced to a high-pressure liquid state through a expansion valve to depressurize and evaporate in the evaporator, thereby circulating inside the freezer cycle. And freeze continuously.

These refrigerants are classified into high temperature, medium temperature, and low temperature according to their use temperature. The low temperature refrigerant has a use temperature of about -35--15 ° C, and a medium temperature of -15-+ 5 ° C. High temperature use is about -10-+ 10 ° C. Refrigerant R-12 (CF ₂ Cl ₂ ) is a representative material for low temperature refrigerants. It has excellent thermodynamic properties and is safe and has been widely used in small and medium sized home refrigerators such as refrigerators. The range of use of the dehumidifier is also increasing. Refrigerant R-22 (CHF ₂ Cl) is a representative material for high temperature refrigerants. It has excellent thermodynamic properties and is safe and is widely used in home and industrial air conditioners. However, the thermodynamic characteristics of refrigerant R-22 under low temperature conditions such as refrigerators and industrial low temperature freezers have the disadvantage that the refrigerant gas temperature on the compressor discharge side increases significantly and the performance and efficiency characteristics decrease as the compression ratio increases. Therefore, refrigerant R-502 is a freon-based double mixed refrigerant made to compensate for this disadvantage of refrigerant R-22 (CHF ₂ Cl) and the specific composition ratio is [R-22 (CHF ₂ Cl) / R-115 (CF ₂ Cl). -CF ₃ ) = 48.8 / 51.2 wt%] and can be used for low temperature compared with refrigerant R-22, and has excellent performance characteristics and easy to use and handle. It has been widely used until the past for a refrigerator.

However, as the refrigerants R-115 and R-22 included in refrigerants R-502 have been found to be the main cause of global ozone depletion and global warming, developed countries that have recognized that global environmental problems are not just limited to some countries but globally In 1987, the Montreal Protocol was enacted to prohibit the use and production of ozone depleting substances under the supervision of the United Nations Environment Program (UNEP). Since the problem of ozone layer destruction is more serious than expected, ozone layer depleting substances such as R-115 and R-22 through the 1990 amendment to London, the fourth meeting of Copenhagen 1992, the Bangkok meeting 1995, the Nairobi practitioners meeting and the Vienna meeting. The regulation was further tightened. In line with these international regulations, research has been conducted on alternative materials that can effectively replace them. Examples include R-404A and ISCEON 89 (Rhodia, France).

R-404A, which is currently being considered as a replacement refrigerant for R-502, is a triple mixed refrigerant [R-125 (C ₂ HF ₅ ) / R-143a (CF ₃ -CH ₃ ) / R-134a (CF _3). -CH ₃ F) = 44/52/4 wt%]. Here, R-404A refrigerant has good performance characteristics but high vapor pressure characteristics of the condensation process, which inevitably changes the design of the existing refrigeration system. However, due to the influence of refrigerant R-143a, the global warming index is 3260 (CO ₂ = 1, 100years), which is very environmentally unfriendly, and also has low solubility with mineral oils, which are commonly used as refrigeration oils. Ester oil or polyalkylene glycol (PAG) oil, which is a special synthetic oil, must be used, and this oil absorbs water indefinitely when exposed to the air, causing fatal damage to the freezer. It is not possible to apply it immediately without major renovation.

On the other hand, ISCEON 89 [Rhodia Co., Ltd.], which is considered for practical use as a replacement refrigerant for R-502, is a pentafluoroethane [R-125 (C ₂ HF ₅ )] and a perfluoropropane [R] as a triple mixed refrigerant. -218 (C ₃ F ₈ )] and propane [R-290 (C ₃ H ₈ )]. The ISCEON 89 refrigerant has improved flammability and good volume freezing capacity, but due to the characteristics of azeotropic mixtures, the temperature gradient appears to be about 2 to 3 ℃ during evaporation and condensation, and the global warming index is 4100 (CO ₂ = 1, 100 years). There is a problem in that it is large and unfriendly. In particular, the pressure in the evaporator and condenser is continuously changed due to the phase change (liquid / gas phase) of the refrigerant generated by the azeotropic mixture, which causes instability of the refrigerator system and facilitates the maintenance of the refrigerant at the manufacturing site. It has a number of fatal disadvantages. In other words, none of them have a characteristic that can be completely replaced immediately by adjusting the amount of refrigerant without changing the design of a refrigerator system using an existing freon refrigerant.

As a substitute for R-502, hydrocarbon-based refrigerants have excellent thermodynamic properties and have a very small characteristic with a global warming index of 3 (CO ₂ = 1, 100yr). Isobutane [CH (CH ₃ ) ₃ ] has good vapor pressure characteristics but low refrigeration capacity per unit volume, and propane (C ₃ H ₈ ) has good refrigeration capacity per unit volume but high vapor pressure characteristics, resulting in refrigeration systems including compressors. The design needs to be changed and there are problems in terms of flammability and explosiveness. Proper mixture of propane (C ₃ H ₈ ) and isobutane improves the volume freezing capacity and performance coefficient, but due to the characteristics of non-azeotropic mixture, the temperature gradient appears to be about 5 ~ 6 ℃ during evaporation and condensation. There is a problem in that.

Meanwhile, according to Korean Patent Registration No. 10-0255477, propane and cyclopentane are used among hydrocarbon refrigerants, and trifluoro methyl iodide (CF ₃ I) is mixed and used as the main refrigerant to suppress the flammability of the hydrocarbon refrigerant. Techniques for using silicone oils to activate the mixture have been proposed. However, trifluoro methyl iodine is mainly used as a fire extinguishing agent to replace Halon-1301 (Hallon-1301, CF ₃ Br), and it is used in a refrigerator, which is an advantage of hydrocarbon refrigerant due to its high price and high molecular weight when used as a main refrigerant. Rather than reducing the amount of refrigerant injected, it increases its consumption. When applied to a freezer, the freezing capacity is reduced, and when it is mixed with hydrocarbon-based refrigerants such as propane and cyclopentane above an appropriate level, the temperature gradient is 2 to 3 in the evaporation and condensation process. It shows the azeotropic mixture properties that appear as large as ℃. These azeotropic mixtures have different performance characteristics even when the refrigerant is injected on the same mass basis according to the phase change (liquid / gas phase) of the refrigerant, and the pressure of the evaporator and condenser components of the refrigerator is continuously changed. It leads to instability, and thus, maintenance of the refrigerant at the manufacturing site becomes very difficult. In addition, the silicone oil used in the patent is always present in the liquid state and circulates in the freezer cycle, thereby lowering the freezing capacity in the evaporator portion of the freezer. It has a fatal effect and strictly limits its usage. In addition, since the refrigerant is separated from the refrigerant when it is stored in the container for a long time after the production of the refrigerant can be expected to have a minimal effect when using the actual refrigerant from the container.

The use of alternative refrigerant materials proposed so far requires a change from design to design of the components of the refrigerator. This design change is costly and waste of resources. Not only is it difficult to effectively apply the existing home and industrial cryogenic freezers using the refrigerant R-502, but the cost of modifying their production equipment is enormous.

Accordingly, an object of the present invention is to replace the R-502 only by adjusting the amount of the refrigerant to minimize the design change of the existing refrigerator system using the R-502 refrigerant, excellent volumetric freezing capacity and performance coefficient, steam pressure characteristics It is excellent, to ensure the reliability and various components of the refrigerator, including the refrigeration oil, to provide an approximate azeotropic mixed refrigerant composition that minimizes the temperature gradient in the evaporation and condensation process.

Another object to be described in the above object and detailed description of the present invention is 50 to 80% by weight of propylene (CH ₃ -CH = CH ₂ ) and 20 to 50% by weight of hydrocarbon-based refrigerant gas In the group containing pentafluoroethane (C ₂ HF ₅ ), a hydrofluorocarbon-based refrigerant gas of, optionally composed of carbon dioxide (CO ₂ ), trifluoro methyliodine (CF ₃ I) and mixtures thereof To provide a mixed refrigerant composition is selected, and further contains an additive within 5% by weight to improve the flammability of the hydrocarbon-based refrigerant and to compensate for the smooth flow of the refrigerant in the evaporator of the refrigerator components and the volume freezing capacity of the refrigerant. Can be achieved.

1 and 2 show the analysis and measurement conditions for the mixed refrigerant using a pressure-enthalpy diagram.

The present invention is an alternative to Freon-based refrigerant R-502, which is the main culprit of ozone layer destruction and global warming, and is environmentally friendly and can be directly applied by adjusting the amount of refrigerant without changing the system design of the refrigerator using the existing R-502 refrigerant. A refrigerant composition is related.

The mixed refrigerant composition for R-502 replacement according to the present invention contains a mixture of refrigerant gas selected from hydrocarbons and refrigerant gas selected from HFCs, and optionally improves flammability of hydrocarbon-based refrigerants. In order to complement the smooth flow of the refrigerant in the evaporator and the volumetric freezing capacity of the refrigerant, an additive selected from the group consisting of carbon dioxide (CO ₂ ), trifluoro methyliodine (CF ₃ I) and mixtures thereof is further added. It contains.

More specifically, the composition of the mixed refrigerant according to the present invention is propylene (CH ₃ -CH = CH ₂ ) which is 50 to 80% by weight of hydrocarbon refrigerant gas and 20 to 50% by weight of hydrofluoric acid based on the total refrigerant composition. Pentafluoroethane (C ₂ HF ₅ ), which is a hydrocarbon-based refrigerant gas.

In order to improve the flammability of the hydrocarbon-based refrigerant and to compensate for the smooth flow of the refrigerant in the evaporator of the refrigerator components and the volume freezing capacity of the refrigerant, the refrigerant composition is carbon dioxide (CO ₂ ), trifluoro methyl iodide ( It is preferred to further contain within 5% by weight of an additive selected from the group consisting of CF ₃ I) and mixtures thereof.

According to an embodiment of the present invention, propylene (CH ₃ -CH = CH ₂ ), which is 69 to 70 wt% of hydrocarbon refrigerant gas, and pentafluoroethane (C, which is 28 to 30 wt% of hydrofluorocarbon refrigerant gas, is used. ₂ HF ₅ ), and a mixed refrigerant composition containing an additive selected from the group consisting of carbon dioxide (CO ₂ ), trifluoro methyliodine (CF ₃ I) and mixtures thereof in an amount of 1 to 2% by weight The most desirable results were provided.

According to another embodiment of the present invention, the carbon dioxide or trifluoromethyl iodine which improves the flammability of the hydrocarbon-based refrigerant gas, the smooth flow of the refrigerant oil in the evaporator and the reinforcement of the volume freezing capacity of the refrigerant may be 5% by weight or more. The mixed refrigerant composition showed non-flammable properties. However, when the content of carbon dioxide or trifluoro methyl ion is excessive, the additive may be added in an amount of 5% by weight or less based on the total mixed refrigerant composition because it may cause a decrease in freezing capacity and an azeotropic property.

According to another embodiment of the present invention, the mixed refrigerant composition of the present invention presented above to replace the R-502 refrigerant has a thermodynamic property which is the most important characteristic as the refrigerant (for example, superior refrigeration compared to the conventional R-502 refrigerant). Its performance and high coefficient of performance (COP) are excellent, its safety is greatly enhanced, and it is environmentally friendly (ie ozone layer destruction index = 0, global warming index = minimization).

According to another embodiment of the present invention, the mixed refrigerant composition of the present invention has a vapor pressure (evaporation / condensation pressure) characteristics of approximately the same as the existing R-502 refrigerant to change the design of the existing refrigerator using the R-502 refrigerant It can be shown that it can be directly dropped-in by adjusting the amount of refrigerant.

According to another embodiment of the present invention, the mixed refrigerant composition of the present invention has a near-azeotropic mixture characteristic that minimizes the occurrence of the temperature gradient of the evaporation / condensation process phase change of the refrigerant generated by the general azeotropic mixture The pressure of the evaporator and condenser due to the (liquid phase / gas phase) was continuously changed to solve the system instability, which facilitated the maintenance of the refrigerant at the manufacturing site.

The preparation of the R-502 replacement mixed refrigerant composition according to the present invention proceeds in the same manner as a conventional mixed refrigerant composition, and is specifically as follows: The air in the sealed container is brought into a full vacuum state using a vacuum pump, It can be achieved by injecting a hydrocarbon-based refrigerant gas and a hydrofluorocarbon-based refrigerant gas sequentially or together in this sealed container and stirring for a predetermined time. If necessary, carbon dioxide (CO ₂ ) or trifluoro methyl iodide (CF ₃ I) is added inside the vessel to improve the flammability of hydrocarbon-based refrigerant gas and to improve the flowability of refrigerant oil and the volumetric freezing capacity of refrigerant in the evaporator. Reinforced refrigerant compositions can be prepared. The finished composition is shipped in a predetermined weight in a gas container attached to the valve. The preparation can be carried out at room temperature.

The mixed refrigerant composition of the present invention has a high coefficient of performance and excellent volume freezing capacity, and thus can be widely used in a refrigerator consisting of a compressor, a condenser, and an expansion valve evaporator. It can also be used in chillers with additional oil separators and liquid separators. In particular, the mixed refrigerant composition of the present invention has a vapor pressure characteristic similar to that of R-502 to minimize the design change of the existing refrigerator system using R-502, reciprocating, rotary, scroll type using R-502 It has the advantage that it can be applied to any existing compressor such as a compressor without changing the system.

The mixed refrigerant composition of the present invention is excellent in compatibility with the refrigeration oil for preventing wear of the compressor and the like. It can be used universally with one or more blended refrigeration oils selected from standard products (ISO VG 10-50) as defined by the International Organization for Standardization (ISO). In particular, mineral oil, which has been most widely used as a refrigerator oil, may be used.

The mixed refrigerant composition of the present invention can also be applied to a heat pump type refrigerator in which heat generated by a condenser in a refrigeration cycle is used for heating, for example, a condenser in a room by cooling air in an outdoor evaporator. It can be applied to heat pump type air conditioner which warms air, that is, cooling and heating.

Hereinafter, the present invention will be described in more detail with reference to Examples, but these Examples are merely illustrative of the present invention, and the scope of the present invention is not limited to these Examples.

Example

Example 1

A mixed refrigerant composition having the composition below was prepared by the method described above.

Example 2

Boiling point, toxicity, flash point using R-502 and R-404A and ISCEON 89 for the purpose of comparison with the specimen prepared in Example 1 (Samples 1 to 5 are named SR-70a to SR-70e). The thermodynamic properties of various refrigerants, including heat transfer rate, latent heat of evaporation, ozone depletion index, and exponential warming index, were measured and the results are shown in Table 2 below.

In Table 2, R-502 can be seen that the ozone layer destruction index and the global warming index is a large environmental target material. R-404A has a problem that the ozone layer destruction index is 0, but the global warming index is large and refrigeration oil does not use mineral oil, and special synthetic oil, ester oil, is used, which makes the manufacturing process complicated and increases the manufacturing cost. ISCEON 89 has zero ozone depletion index, but the global warming index is not environmentally friendly, and the amount of branching is not enough to reduce refrigerant consumption and manufacturing management is difficult due to the characteristics of non-azeotropic mixture.

The mixed refrigerant composition of the present invention (SR-70b, SR-70c, SR-70d) compared to the freon mixed refrigerants (R502, R404A, ISCEON 89) heat transfer characteristics, latent heat of evaporation, ozone layer destruction, global warming effects, etc. This is very good and shows that the molecular weight is small and the refrigerant usage can be reduced.

Example 3

Compared with various refrigerants, the mixed refrigerant (SR-70 Series) of the present invention proposed as an alternative refrigerant of R-502 can immediately replace refrigerant R-502 under conditions such as an industrial air conditioner, a low temperature storage system, and a low temperature freezer. The theoretical cycle characteristics of volume freezing capacity, coefficient of performance, condensation and evaporation pressure, compression ratio, temperature gradient, discharge gas temperature, etc. were analyzed. Standard conditions for the theoretical cycle characteristics analysis are set by the condensation temperature, the evaporation temperature, the supercooling temperature, the superheated gas temperature, and the ambient temperature of the compressor as ASHRAE (HBP, LBP) standard conditions shown in FIGS. 1 and 2.

Refrigerant property calculation program used for theoretical cycle characteristics analysis used the refrigerant properties program (NIST REFPROP 5.1) of the American Society of Refrigeration and Air Conditioning for conventional refrigerants, and calculated the thermodynamic properties of the new mixed refrigerant (SR-70 Series) of the present invention. To do this, the saturation temperature-pressure characteristic is measured using an equilibrium test apparatus, and a new interaction coefficient according to temperature is introduced to minimize the error between the experimental data and the calculated value, and this interaction coefficient and CSD (Carnahan / Starling / DeSantis A program that can calculate the physical properties of the mixed refrigerant of the present invention with additives was developed using state equations and thermodynamic relations.

Based on the 100% volumetric efficiency of the compressor, the analysis results according to the weight ratio mixing ratio are presented in Table 3 and Table 4 using the above-mentioned program.

Referring to Tables 3 and 4 above, the R-404A refrigerant, which is being considered as an alternative to R-502, is very environmentally friendly, with a global warming index of 3260, which is not environmentally friendly. COP) showed a 3.2% decrease in high temperature conditions, the evaporation and condensation pressure characteristics increased by 5.5 ~ 9.5%, and the approximate azeotropic mixture characteristic showed a temperature gradient of 0.3 ~ 0.6 ℃ in the evaporation and condensation process. In the case of ISCEON 89 refrigerants, the global warming index is 4100, which is very environmentally friendly.The volume freezing capacity is better than that of R-502, but the coefficient of performance is lowered by 2.7% under high temperature conditions and the evaporation pressure is 6.3-13.7% Increasingly, it is difficult to apply the refrigerant directly to the existing refrigerator system without changing the design. This leads to instability and makes it difficult to maintain the refrigerant at the manufacturing site.

Meanwhile, the mixed refrigerant of the present invention (SR-70 series) is an environmentally friendly refrigerant having the best global warming index compared to R-502, and has an excellent volume freezing capacity and performance coefficient to reduce electric power consumption, evaporation and condensation. The pressure characteristics are the closest to those of R-502, and show very good approximate azeotropic mixtures with temperature gradients of 0.35 to 0.4 ° C. In addition, the molecular weight is small, the refrigerant injection amount can be reduced by 42 ~ 48%, and mineral oil can be used as the refrigeration oil, and the cost reduction effect can be applied immediately without changing the design of the existing refrigerator system by adjusting the amount of refrigerant.

Example 4

Using the calorimeter test apparatus manufactured using the second refrigerant calorimetry method according to the Korean Industrial Standard (KS B 6365-1987), the performance of various refrigerants using the compressor, the temperature gradient of the evaporation / condensation process, and the compressor discharge gas temperature Was measured, and the results are shown in Tables 5 and 6.

As shown in Table 5 and Table 6, R-404A has excellent refrigerating capacity but high vapor pressure characteristics, resulting in increased consumption input, which significantly reduces the performance coefficient, especially in high temperature operating conditions, and the temperature gradient of evaporative condensation process is 0.5. As it occurs at the level of ℃ ~ 0.7 ℃ exhibited the approximate azeotrope characteristics, it was composed of a mixture of hydrofluorocarbon refrigerants and had to be carried out experiments using special ester oils to ensure compatibility with the refrigeration oil. In the case of ISCEON 89 refrigerants, the freezing capacity and performance coefficient are the same as those of R-502, but the azeotropic mixed refrigerants exhibit a temperature gradient of 2.0 to 2.1 ° C in the evaporation / condensation process. In the case of ISCEON 89 refrigerants, due to the characteristics of azeotropic mixed refrigerants, even if they are injected on the same mass basis according to the phase change (liquid / gas phase) of the refrigerant, the performance characteristics are different. This results in instability of the system, which makes it very difficult to maintain the refrigerant at the manufacturing site. Therefore, azeotrope mixture characteristics that do not generate temperature gradient during evaporation / condensation are very important for mixed refrigerants.

SR-70 Series refrigerants of the present invention exhibited better quality characteristics than R-502 in terms of refrigerating capacity and coefficient of performance, and the temperature gradient test results in the evaporation / condensation process showed that the temperature gradient was 0.2 ℃ to 0.5 ℃. Very good approximate azeotropic mixture properties similar to single refrigerants. In other words, it can be seen that the mixed refrigerant SR-70 Series refrigerant of the present invention, which exhibits excellent freezing capacity and performance coefficient and exhibits an approximate azeotropic mixture, has a condition that can be immediately applied to an existing R-502 refrigerator system.

Example 5

Additive carbon dioxide (CO ₂ ) to 70% by weight of propylene (CH ₃ -CH = CH ₂ ) and 30% by weight of pentafluoroethane (C ₂ HF ₅ ) as a mixed refrigerant composition of the present invention using a calorimeter tester and an equilibrator ) Or the temperature gradient of the evaporation / condensation process according to the mixing ratio was measured while adjusting the mixing ratio of trifluoromethyliodine (CF ₃ I), and the results are shown in Table 7.

As can be seen in Table 7, when the mixing ratio of the additive is less than 5% by weight, the temperature gradient of the evaporation / condensation process showed a very good approximate azeotropic mixture characteristic of 0.5 ° C or less, but as the mixing ratio of the additive increases, the evaporation / The azeotropic mixture showed a large temperature gradient in the condensation process.

Example 6

In order to verify the reliability of the refrigerator system to which the mixed refrigerant composition SR-70 Series of the present invention was applied, a reliability evaluation experiment was performed using a compressor, which is a core part of the refrigerator. This experiment was carried out overload friction test according to the reliability test standard of G.E of USA. The test equipment consists of the integrated condenser / evaporator, blower, expansion valve and capillary, timer, and life control device. This experimental device was manufactured to determine the reliability of the compressor by making harsh experimental conditions in a short time through the suction and discharge pressure of the compressor and the compressor case temperature control. Intake and discharge pressure control is mainly made by adjusting the flow rate of the refrigerant using the expansion valve and the capillary tube, and by controlling the rotational speed of the blower by sensing the surface temperature of the integrated condenser / evaporator to achieve more precise pressure control. In order to minimize the size of the experimental device, the evaporator and condenser were integrated, and the temperature control of the compressor case was performed using a blower. After operating the compressor for a limited period of time, before disassembling the compressor, the frozen oil is collected in a beaker to analyze the total acid number, moisture, and color. Finally, the wear condition of the driving part, flexibility of organic materials, weight and size change were evaluated.

The overload friction test was mainly performed to verify the frictional wear state of the driving part of the compressor, and the test results are shown in Table 8. In particular, the hydrocarbon-based mixed refrigerant composition SR-70 Series of the present invention shows very excellent characteristics due to the low computational value as a result of an overload experiment with mineral oil (refrigerant oil (trade name, 4GSD-T)) as a refrigeration oil. The results were equally good compared to R-502.

Example 7

As a mixed refrigerant composition of the present invention, carbon dioxide (CO ₂ ) or trifluoro as an additive to a mixture consisting of 80% by weight of propylene (CH ₃ -CH = CH ₂ ) and 20% by weight of pentafluoroethane (C ₂ HF ₅ ), respectively The ignition temperature was measured while adjusting the mixing ratio of methyl iodine (CF ₃ I), and the results are shown in Table 9.

As can be seen in Table 9, when the content of the additive is about 1.5 by weight, the flash point of the mixed refrigerant composition was increased by about 2.0 to 3.5%, and when it was 5% by weight, the mixed refrigerant composition was nonflammable. However, if the additive exceeds 5% by weight, the freezing capacity is lowered and exhibits an azeotropic mixture property, so it is preferable to limit the amount used within 5% by weight.

Example 8

The equilibrium experiment apparatus was used to measure the saturation pressure according to the temperature of the mixed refrigerant of the present invention (SR-70 Series). This experimental device is largely composed of a balancer, a tank for recovering refrigerant, and a device for temperature control of the balancer. The balancer is again composed of a balance shell and a magnetic pump. The equilibrium cell has a sight glass attached to the inside of the cell, and the magnetic pump serves to circulate the gas and the liquid refrigerant to easily balance the mixed refrigerant. The balance cell and the magnetic pump are installed in a thermostat, and the thermostat temperature is controlled by an external temperature control device. Silicone oil was used as the heat transfer medium in the thermostat. For equilibrium experiments, the temperature of the thermostat is set first, and the inside of the cycle is vacuumed (1 × 10 ⁻⁵ torr) using a vacuum pump. When the vacuum is obtained and the temperature of the thermostat is set, the mixed refrigerant is injected into the liquid state to be about one third of the equilibrium cell volume. After the refrigerant is injected, the magnetic pump is operated to ensure good mixing and phase equilibrium. When phase equilibrium is achieved after refrigerant injection, measure the saturation pressure according to temperature using temperature and pressure sensor.

The equilibrium test apparatus was used to measure the saturation pressure according to temperature compared to various refrigerants over a temperature range of -40 ° C. to 60 ° C., and the results are shown in Table 10. As can be seen in Table 10 below, the mixed refrigerant SR-70 Series refrigerant of the present invention showed a somewhat higher pressure characteristic than the R-502, but showed a very good pressure characteristic compared to R-404A.

In the case of using the mixed refrigerant according to the present invention, it is possible to replace R-502 refrigerant, which is regulated as a global environmental destruction substance according to the Montreal Protocol, and to adjust the amount of refrigerant without changing the design of the refrigerator system using the existing R-502. It is immediately applicable. Therefore, it is also effective to improve the manufacturing cost of the freezer product by eliminating the need for additional supplementation of the existing freezer production equipment. On the other hand, the function as a refrigerant is summarized as follows: (a) Low evaporation temperature at atmospheric pressure (b) Condensation and evaporation pressure are equivalent to R-502 (c) Excellent latent heat of evaporation (d) Solidification point (E) Excellent volume freezing capacity (f) High critical temperature (g) Compatibility with refrigeration oil (h) Low viscosity and excellent heat transfer characteristics (i) Excellent electrical insulation It does not corrode electrical insulation material (j) It shows non-flammable property by remarkably improving flammability and explosiveness. (K) It is harmless to environment and human body. (L) Designed in refrigerator using existing R-502. It can be applied immediately by adjusting the amount of refrigerant without change.

Claims (4)

a) 50 to 80 wt% hydrocarbon refrigerant gas propylene (CH ₃ -CH = CH ₂ ) and 20 to 50 wt% hydrofluorocarbon refrigerant gas pentafluoroethane (C ₂ HF ₅ ) With mixed refrigerant, b) Additives selected from the group consisting of carbon dioxide, trifluoro methyl iodide and mixtures thereof to improve the flammability of the hydrocarbon-based refrigerant, and to compensate for the smooth flow of the refrigerant and the volume freezing capacity of the refrigerant. It contains in 5 weight% (but does not include 0) with respect to mixed refrigerant, c) R-502 replacement mixed refrigerant composition, characterized in that it has azeotropic properties and is compatible with mineral oil as a refrigeration oil. The pentafluoroethane according to claim 1, wherein the refrigerant composition is propylene (CH ₃ -CH = CH ₂ ), which is 69 to 70% by weight of hydrocarbon refrigerant gas, and 28 to 30% by weight of hydrofluorocarbon refrigerant gas. (C ₂ HF ₅ ) and additives selected from the group consisting of carbon dioxide (CO ₂ ), trifluoro methyliodine (CF ₃ I) and mixtures thereof in an amount of 1 to 2% by weight R-502 replacement mixed refrigerant composition. A refrigeration air conditioner comprising an alternative mixed refrigerant composition of R-502 according to claim 1. delete