MXPA99004988A - Refrigerant composition - Google Patents

Abstract

A non-azeotropic refrigerant composition having a vapour pressure at -20°C of from 70 to 190 kPa (0.7 to 1.9 bar), at +20°C of from 510 to 630 kPa (5.1 to 6.3 bar) and at +60°C of from 1620 to 1740 kPa (16.2 to 17.4 bar), which composition comprises:(a) 1,1,2,2-tetrafluoroethane (R134), 1,1, 1,2-tetrafluoroethane (R134a), difluoromethoxytrifluoromethane (E125) or a mixture of two or more thereof, in an amount of from 60 to 99%by weight, based on the weight of the composition;(b) from 1 to 10%by weight, based on the weight of the composition, of an unsubstituted hydrocarbon of the formula C nH m in which n is at least 4 and m is at least 2n-2;and, (c) up to 39%by weight, based on the weight of the composition, of a vapour pressure depressant.

Description

REFRIGERANT COMPOSITION Description of the invention The present invention is concerned with a refrigerant composition suitable for use in compression refrigeration. Chlorofluorocarbons (CFCs), such as dichlorodifluoromethane (CFC-12) have traditionally been used as refrigerants for compression refrigeration systems. Refrigeration systems that use CFCs as refrigerants generally use mineral oils to lubricate the compressor. These lubricating mineral oils are also known as naphthalene oils. A lubricating mineral oil is usually a fraction of lubricating oil that has a viscosity index of -300 to 140, which has been removed wax, deasphalted and hydrogenated. The mineral oil may contain up to 15% by weight of an additive such as an antioxidant or a corrosion inhibitor. Normally, it has a kinematic viscosity at a temperature of 40QC of 10 mm2 / leaving at 220 mm2 / second (10 cSt at 220 cSt). In compression refrigeration systems it is desirable that all the lubricant remain in the compressor to ensure that the compressor is properly lubricated. However, in practice, a quantity of lubricant is invariably aspirated into the pipeline REF: 30473 * surrounding the refrigeration cycle. If the lubricant is insoluble in the refrigerant, there is a danger of it separating from the refrigerant and not returning to the compressor. In this case, the compressor is improperly lubricated. Refrigeration systems using CFCs such as CFC-12 generally use mineral lubricating oils because such CFCs are soluble with mineral oils throughout the range of cooling temperatures. However, recent concerns regarding the depletion of the ozone layer by CFCs have led to the restriction of the use of CFCs. CFC-12 has an ozone depletion potential of 0.9, where the ozone depletion potential of trichloromethane is defined as 1. Therefore, alternative refrigerants are required. Perfluorocarbons are not suitable as alternative refrigerants since they have a high global warming potential (G P) and excessive life times in the atmosphere. The GWP is the integrated weather commitment to the climate that promotes the instantaneous release of 1 Kg of refrigerant expressed in relation to that of 1 Kg of carbon dioxide, which is considered to have a GWP of 1. The 1, 1, 1 , 2-tetrafluoroethane (Rl34a) is being widely used as an alternative to chlorofluorocarbon refrigerants. Does not have substantially no potential depletion of the ozone layer. It has a GWP, measured based on an integrated horizon in the 100-year timeframe of approximately 1300. However, the R134a has the disadvantage that it is substantially immiscible with the mineral oil lubricants used in existing refrigeration equipment. In other words, the R134a can not be used by itself in such equipment. Several attempts have been made to find lubricants that can be used with such fluorinated hydrocarbons, such as Rl34a. Several polyester polyols and polyalkylene glycols have been proposed for this purpose. Unfortunately, however, these new lubricants are considerably more expensive than conventional mineral oil lubricants. Also, they are frequently hydroscopic and absorb atmospheric moisture. Clearly, in order to minimize the necessary changes to equipment or operating conditions when CFCs are replaced in compression refrigeration systems with alternative refrigerants, it is desirable to have the possibility to use conventional mineral oils, as used with the CFC. There is therefore a demand for a refrigerant that possesses the desirable characteristics of R134a, but which can be used with lubricants from conventional mineral oil as used with CFCs. The existing refrigerants that can be used with the mineral oil lubricants are invariably deficient in some other aspect. A new refrigerant composition according to the present invention has been devised which has substantially no ozone depletion potential, which is sufficiently compatible with conventional mineral oil lubricants to be used with them and which has an operating performance. equal to or greater than fluorinated hydrocarbons such as R134a and chlorofluorocarbons such as CFC-12. The present invention provides a non-azeotropic refrigerant composition having a vapor pressure at a temperature of -20 ° C of 70 to 190 KPa (0.7 to 1.9 bar), at a temperature of +20 ° C of 510 to 630 KPa (5.1 at 6.3 bar) and at + 60 ° C from 1620 to 1740 KPa (16.2 to 17.4 bar), which composition comprises: (a) 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2- tetrafluoroethane (R134a), difluoromethoxytrifluoromethane (E125) or a mixture of two or more thereof, in an amount of 60 to 99% by weight based on the weight of the composition; (b) from 1 to 10% by weight, based on the weight of the composition, of an unsubstituted hydrocarbon of the formula CnHm in which n is at least 4 and is at least 2n-2; and (c) up to 39% by weight, based on the weight of the composition, of a vapor pressure depressant agent. Normally, a composition is "non-azeotropic", if at any pressure and temperature given the composition of the liquid and the composition of the vapor above the liquid, they are substantially not equal. Thus, any loss of vapor from a non-azeotropic composition will result in a change in the composition of the remaining liquid. In contrast, the loss of steam from an azeotrope does not result in a change in the liquid composition. Preferred non-azeotropic compositions are those in which, after approximately 50% of the composition is separated such as by evaporation or boiling, the difference in the original composition and the remaining composition is more than about 2%, more preferably higher of approximately 10%. Typically, component (a) is present in an amount of 70 to 95%, preferably 80 to 90%, more preferably 82 to 86% by weight based on the composition. Component (b) is an unsubstituted hydrocarbon of formula CnHm, wherein n is at least 4 and m is at least 2n-2. Normally, n is from 4 to 6, preferably 4 or 5. Normally, the hydrocarbon does not replaced does not have triple links. Preferably, the unsubstituted hydrocarbon is saturated except for the single double bond. More preferably, the unsubstituted hydrocarbon is fully saturated. Normally, the unsubstituted hydrocarbon is methylenecyclopropane, 1-butene, cis and trans-2-butene, butane, 2-methylpropane, cyclopentene, cyclopentane, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl -l-butene, 1-pentene, cis and trans-2-pentene, 2-methylbutane, pentane or a mixture of two or more thereof. Preferably, it is cyclobutane, more preferably n-butane (R600) or 2-methyl-propane (R600a). Normally, the unsubstituted hydrocarbon is present in an amount of 1 to 8%, preferably 2 to 6%, more preferably 2 to 5% by weight, based on the composition. The unsubstituted hydrocarbon serves to improve the compatibility of the refrigerant composition of the invention with mineral oil lubricants. Unfortunately, it increases the vapor pressure of the composition of the invention. It can also increase the flammability of the composition of the invention. Thus, component (c) is required in order to reverse the increase in vapor pressure caused by component (b). Component (c) is a vapor pressure depressant agent, that is, a compound capable of decrease the vapor pressure of the refrigerant composition. Normally, the vapor pressure depressant agent is 1, 1-difluoroethane, 1, 1, 1, 2, 2, 3, 3-heptafluoro-propane, 1,1,1,3,3,3-heptafluoropropane, octafluorocyclobutane, 1, 1, 2, 2 pentafluoropropane, 1, 1, 2, 2, 3-pentafluoropropane, etoximetano trifluoro, trifluorometoxipentafluoro-ethane, difluoromethoxypentafluoroethane, trifluoromethoxy-1, 2, 2, 2-tetrafluoroethane, fluorometoxitrifluorometano, di-fluorometoximetano, pentafluoroetoxipentafluoroetano, di-fluorometoxidifluorometano, trifluorometoxi- 2, 2, 2-trifluoroethane, fluoromethoxymethane, difluoromethoxy-1,2,2,2-tetra-fluoroethane, fluoromethoxyfluoromethane, difluoromethoxy-2,2,2-trifluoroethane, methoxy-2,2,2-trifluoroethane, methoxy-1, 1, 2, 2-tetrafluoroethane or a mixture of two or more thereof. Preferably, it is 1,1-difluoroethane (R152a), 1,1,1,2,2,3,3-heptafluoropropane (R227ca), 1, 1, 2, 3, 3, 3-heptafluoropropane (R227ea) , 1, 1, 1, 2, 2-pentafluoropropane (R245cb), octafluorocyclobutane (RC-318) or a mixture of two or more thereof. Component (c) is normally present in an amount of 4 to 29%, preferably 8 to 18%, more preferably 12 to 16% based on the composition. The amount of the vapor pressure depressant depends on the nature and quantity of the components (a) and (b).

If a large amount of the component (b) is present (ie, more than about 5% by weight based on the composition), then a correspondingly greater amount of the component (c) (or of R134) will be required to obtain a pressure of appropriate steam. The amount of component (c), if any, should be such that the composition has a vapor pressure at a temperature of -20 ° C of 70 to 190 KPa, preferably 90 to 190 KPa, more preferably of 120 to 180 KPa, at a temperature of 20 ° C from 510 to 630 KPa, preferably from 530 to 630 KPa, more preferably from 580 to 620 KPa and at a temperature of 60 ° C from 1620 to 1740 KPa, preferably from 1630 to 1720 KPa, more preferably from 1650 to 1700 KPa. This amount can of course be easily determined by systematic experiments. It is particularly preferred that the vapor pressure depressant agent be present in an amount such that the composition has a vapor pressure substantially equal to that of Rl34a. When the vapor pressure depressant agent is present in an amount of more than 20% by weight based on the weight of the composition, it is preferred that the vapor pressure depressant agent comprises two or more compounds, each of which is present in a % by weight or less, based on the weight of the composition. The refrigerant composition of the invention may further comprise component (d), a flammability suppressing agent. Preferably, the composition comprises a flammability suppressing agent when the unsubstituted hydrocarbon (b) is present in an amount greater than about 2% by weight based on the composition. It is particularly preferred that the composition comprises a flammability suppressing agent when the unsubstituted hydrocarbon (b) is present in an amount of about 3% by weight or more based on the composition. Thus, compositions that do not contain a flammability suppressant typically contain less than 3%, for example, 1 to 2% by weight of the hydrocarbon (b) based on the composition. Normally, the flammability suppressant is 1, 1, 1, 2, 2, 3, 3-heptafluoropropane, 1,1,1,2,3,3, 3-heptafluoropropane, octafluorocyclobutane, octafluoropropane, trifluoromethoxytrifluoromethane, difluoro-methoxytrifluoromethane , trifluoromethoxy-pentafluoroethane, di-fluoromethoxy-pentafluoroethane, trifluoromethoxy-1,2,2,2-tetra-fluoroethane or a mixture of two or more thereof. The vapor pressure depressant agent can also function as a flammability suppressing agent. The Vapor pressure depressant agents that also function as flammability suppressive agents include 1, 1, 2, 2, 3, 3-heptafluoropropane (R227ca), 1, 1, 1,2, 3, 3, 3- heptafluoropropane (R227ea), octafluorocyclobutane (RC-318), trifluoromethoxymentafluoroethane (E218), difluoromethoxymentafluoroethane (E227ea) and trifluoromethoxy-1,2,2,2-tetrafluoroethane (E227ca). If component (d) is present, components (c) and (d) are jointly present in an amount of up to 39%, preferably from 4 to 29%, more preferably from 8 to 18%, more preferably from 12 to 16% by weight based on the composition. Normally, when component (d) is present, component (c) is present in an amount of up to 19% by weight, based on the composition and component (d) is present in an amount of up to 20% by weight based on the composition. When the flammability suppressing agent and vapor pressure depressant agent are jointly present in an amount of 20% by weight or more, based on the weight of the composition, it is preferred that no single compound comprised in the suppressive agent of the flammability or the vapor pressure suppressing agent is present in an amount of 20% by weight or more, based on the weight of the composition.

Clearly, any flammability suppressant or vapor pressure depressant used should not return to the refrigerant composition not suitable for use in compression refrigeration. A) Yes, the choice of the vapor pressure depressant agent or the flammability suppressing agent should not be such as to significantly decrease the solubility in the mineral oil lubricants. Normally, the addition of the vapor pressure depressant agent or the flammability suppressing agent does not cause more than 10%, preferably not more than 5%, of a decrease in the solubility of the composition in the mineral oil lubricants . Normally, any flammability suppressant or vapor pressure depressant agent used should have a GWP, measured based on an integrated 100-year time horizon of less than 5,000, preferably less than 4,000, more preferably less than 3,500. In addition, any flammability suppressing agent or vapor pressure depressant agent used should not impart undue toxicity to the refrigerant composition. The occupational exposure limit (OEL) of the refrigerant composition of the invention is normally from 800 to 1000, preferably from 850 to 950 ppm. The flammability suppressing agent and the vapor pressure depressant agent should have substantially no depletion potential of the ozone layer. In addition, the flammability suppressing agent and / or the vapor pressure depressant agent should not unduly decrease the operating performance of the refrigerant composition of the invention. Normally, the cooling capacity of a compression refrigeration apparatus when using the composition of the invention as a refrigerant is not more than 10% less, preferably not more than 5% less, more preferably not less than the cooling capacity of an identical compression refrigeration apparatus operating under identical conditions that it uses as refrigerant CFC-12 or R134a. Normally, the refrigerant composition of the invention does not substantially contain any lubricants such as polyalkylene glycol. Normally, the energy consumption of a compression refrigeration appliance using the composition of the invention as refrigerant is not more than 10% less, preferably not more than 5% less, more preferably or less than the energy consumption of an appliance of identical compression refrigeration that operates under identical conditions that it uses as refrigerant CFC-12 or R134a. The following compositions are particularly preferred: 1) compositions in which component (a) is R134 and / or Rl34a, component (b) is R600 and / or R600a and component (c) is Rl52a, R227ca, R227ea or a mixture of two or more of them; 2) compositions in which component (a) is R134 and / or R134a, component (b) is R600 and / or R600a and component (c) is Rl52a; 3) compositions in which component (a) is R134 and / or R134a, component (b) is R600 and / or R600a and component (c) is R227ca and / or R227ea. Typically, in the refrigerant composition of the present invention, the ratio of the total number of fluorine atoms in the composition to the total number of hydrogen atoms in the composition is desirably at least 1.25: 1, preferably at least 1.5: 1, more preferably at least 2: 1. Normally, the refrigerant composition has a lower flammability limit (LFL) of more than 7% by volume (v / v) in air, preferably, an LFL of more than 14% by volume in air. More preferably, the refrigerant composition is not flammable.

Preferably, the refrigerant composition of the present invention has a vapor pressure substantially equal to that of R134a. R134a has a vapor pressure at a temperature of -20 ° of about 134 KPa (5 pounds / square inch gauge) at a temperature of 20 ° C of about 572 KPa (68 pounds / square inch gauge) and at a temperature of 60 ° C of about 1680 KPa (229 pounds / square inch gauge). Typically, the composition of the invention has a vapor pressure that is not greater than + 60 KPa (0.6 bar), preferably not greater than ± 40 KPa (0.4 bar), that of Rl34a at a temperature between -30 ° C and + 60 ° C. The refrigerant composition of the invention has substantially no ozone consumption potential.

Normally, it has a global warming potential (GWP), measured based on an integrated time horizon of 100 years, less than 2000, preferably less than 1600, more preferably less than 1300. The refrigerant composition of the present invention is preferably used in a domestic refrigeration appliance. Normally, it is used in a compression refrigeration unit that does not contain more than 1 Kg of refrigerant.

The present invention also provides a process for producing refrigeration, comprising the condensation of a composition of the invention and thereafter evaporation of the composition in the vicinity of a body to be cooled. The refrigerant composition of the present invention can be prepared by transferring the individual components by autogenous pressure to a pressure vessel initially evacuated, in order to raise the vapor pressure to room temperature. The quantity of each component can be inspected by weighing the container and the contents before and after transferring it. The refrigerant composition of the present invention is advantageous since it does not consume or deplete the ozone layer, has a low global warming potential (GWP) in relation to CFC-12 or R134a, is compatible with mineral oil lubricants and has operating performance equal to or superior to conventional refrigerants, such as Rl34a and CFC-12. The refrigerant composition of the present invention is compatible with mineral oil lubricants as used with CFC refrigerants. Prior to the present invention it was thought that for a refrigerant and a lubricant to be compatible, the liquid phases should be miscible. However, it has it is now surprisingly found that satisfactory results are obtained if the gaseous refrigerant is at least partially soluble in the liquid lubricant. Although the refrigerant composition in the present invention is not fully miscible with the mineral oil lubricants when they are in their liquid phase, in the gas phase it is partially soluble in the mineral oil. The refrigerant composition of the invention is thus compatible with mineral oil lubricants. The refrigerant composition also has a high operating performance. The refrigeration systems containing the composition of the present invention are up to 10% more efficient than refrigeration systems containing conventional refrigerants. It is surprising that the above advantages are obtained by the refrigerant composition of the present invention, because the refrigerant composition is a mixture of fluorohydrocarbons and hydrocarbons instead of a single compound. Prior to the present invention, it was thought undesirable to use non-azeotropic mixtures as refrigerants since these mixtures show a temperature shift, a temperature shift of a mixture is the absolute value of the difference between the start and end temperatures of the change. of gas / liquid phase by the mixture. It can be measured by determining the difference between the bubble point of the mixture (the temperature at which the liquid mixture begins to boil) and the dew point of a corresponding gas mixture (the temperature at which the gas mixture starts at condense). It was believed that the displacement of the temperature led to variable temperatures in the evaporator of a compression refrigeration system and was considered undesirable here. However, although it is found that the refrigerant compositions of the present invention have up to a temperature shift of 9 ° K when tested in the laboratory, it was surprisingly found that the temperature of an evaporator of a domestic refrigeration system containing the composition The refrigerant of the present invention is substantially constant. The following examples illustrate the invention.

EXAMPLES 1 TO 6 1000 g of refrigerant composition were prepared in each case by mixing together varying amounts of the compounds in a pressure vessel of 1000 cm 3. The amounts of each compound used are shown in Table 1.

TABLE 1 EXAMPLE 7 The vapor pressure of the refrigerant composition of Example 1 was measured at a variable temperature by using a stainless steel cylinder of 300 cm 3 internal volume equipped with a calibrated Bourdon manometer, suspended in a temperature controlled bath, containing a solution of glycol. The temperatures were determined by using a calibrated platinum resistance thermometer. The results are shown in Table 2.

Table 2 EXAMPLE 8 The vapor pressure of the refrigerant composition of Example 2 was measured at variable temperatures in the same manner as in Example 7. The results are shown in Table 3.

EXAMPLE 9 The vapor pressure of the refrigerant composition of Example 6 was measured at variable temperatures in the same manner as in Example 7. The results are shown in Table 4.

EXAMPLE 10 The global warming potentials (GWP) of the compositions of Examples 2 to 6 were calculated on a mass proportion basis, that is, by taking the sum of the products of the global warming potentials of each component of the composition in question with the mass proportion of that component in the composition. Thus, the GWPs of the composition of Example 2 are calculated as follows: The global warming potentials of Rl34a and CFC-12 are provided as comparisons (data taken from BS 4434, 1995). The results are shown in Table 5.

Table 4 TABLE 5 - Comparison of the Global Warming Potential EXAMPLE 11 The cooling rate in a Bauknecht GKC 3333/0 WS Class N freezer having a gross volume of 332 liters and a refrigerant charge of 180 g was measured by using the composition of Example 1 as a refrigerant. The cooling rate in the same domestic freezer was measured by using Rl34a as a refrigerant. Thermocouples were connected to the inlet and outlet of the evaporator coil inside the freezer compartment, also as the compressor discharge line. An additional thermocouple was placed inside the freezer compartment near the thermostat detector. Gauges were fitted to the suction lines and discharge and the power supply to the freezer was passed through a meter of kilo atts hour. Thermocouple temperatures were recorded by a data logger usually at 1 minute intervals. The freezer, loaded in the factory with R134a, was placed in a controlled temperature environment, usually 22 ° C ± 1 ° C and allowed to equilibrate in temperature for at least 24 hours. The freezer and the data logger are turned on and the time is taken to reduce the internal temperature of the freezer to a level at which the cut of the thermostat was determined. The procedure was repeated after replacing the R134a with the composition of example 1. By placing the freezer in a controlled temperature environment it is ensured that the amount of energy that must be separated in each case to reduce the internal temperature by a given amount is approximately equivalent. Accordingly, a comparison of the cooling effect between the two refrigerants can be made. The faster the internal temperature reaches the desired temperature, the greater the cooling effect. The energy consumption taken directly from the atts-hour kilo meter provides a direct comparison of the efficiency of the refrigerant composition of example 1 compared to R134a. The results are shown in Table 6.

EXAMPLE 12 The cooling rate was measured in the same manner as in Example 11, except that the composition of Example 2 was used in place of the composition of Example 1. The results are shown in Table 7.

Table 6 Table 7 EXAMPLE 13 The cooling rate was measured in the same manner as in Example 11, except that the composition of Example 6 was used in place of the composition of Example 1. The results are shown in Table 8.

EXAMPLE 14 The maximum and minimum cabinet temperatures, average evaporator and condenser pressure, average compressor discharge temperature and average freezer energy consumption used in example 11, using the composition of example 2 as a refrigerant, were measured as that the freezer was in operation. Similar measurements were taken with the same freezer when using R134a as a refrigerant. Thermocouples were connected to the inlet and outlet of the evaporator coil inside the freezer compartment as well as to the compressor discharge line. An additional thermocouple was placed inside the freezer compartment near the thermostat detector. Gauges were fitted to the suction and discharge lines and the power supply to the freezer was passed through a kilowatt-hour meter.

Table 8 1:01:59 14.25 1:02:02 -13.96 2:05:05 -18.67 and allowed to reach equilibrium in temperature for at least 24 hours, i The freezer and the data logger were turned on and the performance characteristics specified above were recorded in a period of at least 30 hours. The procedure was repeated after replacing the Rl34a with the composition of example 2. The results are shown in Table 9.

Table 9 - (Ambient Temperature 23 ° C) -J- Duration in the cycle It is noted that, in relation to this date, the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Claims (15)

1. Claims Having described the invention as above, the content of the following claims is claimed as property: 1. A non-azeotropic refrigerant composition having a vapor pressure at a temperature of -20 ° C of 70 to 190 KPa (0.7 to 1.9 bar) ), at + 20 ° C from 510 to 630 KPa (5.1 to 6.3 bar) and at + 60 ° C from 1620 to 1740 KPa (16.2 to 17.4 bar), characterized in that it comprises: (a) 1,1, 2, 2- tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a), difluoromethoxytrifluoromethane (E125) or a mixture of two or more thereof, in an amount of 60 to 99% by weight, based on the weight of the composition; (b) from 1 to 10% by weight, based on the weight of the composition, of an unsubstituted hydrocarbon of formula CnHm in which n is at least 4 and m is at least 2n-2; and (c) up to 39% by weight, based on the weight of the composition, of a vapor pressure depressant agent.
2. 2. A composition according to claim 1, characterized in that component (b) is fully saturated, except for a double bond or is fully saturated.
3. 3. A composition according to claim 1, characterized in that component (b) is methylenecyclopropane, 1-butene, cis and trans-2-butene, butane, 2-methylpropane, cyclopentene, cyclopentane, 2-methyl-1-butene, -methyl-2-butene, 3-methyl-1-butene, 1-pentene, cis and trans-2-pentene, 2-methylbutane, pentane or a mixture of two or more thereof.
4. 4. A composition according to any of the preceding claims, characterized in that the component (c) is 1,1-difluoroethane, 1,1,1,2,2,3,3-heptafluoropropane, 1, 1, 1, 2, 3, 3, 3-heptafluoropropane, octafluorocyclobutane, 1, 1, 1, 2, 2-pentafluoropropane, 1,1,2,2,3-pentafluoropropane, trifluoromethoxymethane, trifluoromethoxy-pentafluoroethane, difluoromethoxypentafluoroethane, trifluoro-methoxy-1,2, 2, 2-tetrafluoroethane, fluoromethoxytrifluoromethane, difluoromethoxymethane, pentafluoroethoxypentafluoroethane, difluoromethoxydifluoromethane, trifluoromethoxy-2,2,2-trifluoroethane, fluoromethoxymethane, difluoromethoxy-1,2,2,2-tetrafluoroethane, fluoromethoxyfluoromethane, difluoromethoxy-2,2,2-trifluoroethane, methoxy-2,2,2,2-trifluoroethane, methoxy-1,2,2,2-tetrafluoroethane or a mixture of two or more thereof.
5. 5. A composition according to any of the preceding claims, characterized in that the component '(a) is present in an amount of 70 to 95% in weight, based on the composition, component (b) is present in an amount of 1 to 8% by weight, based on the composition and component (c) is present in an amount of 4 to 29% by weight in base to the composition.
6. 6. A composition according to any of the preceding claims, characterized in that the component (a) is present in an amount of 80 to 90% by weight, based on the composition, the component (b) is present in an amount of 2 to 6% by weight, based on the composition and component (c) is present in an amount of 8 to 18% by weight, based on the composition. A composition according to any of the preceding claims, characterized in that the component (a) is present in an amount of 82 to 86%, based on the composition, the component (b) is present in an amount of 2 to 5% by weight, based on the composition and component (c) is present in an amount of 12 to 16% by weight, based on the composition. 8. A composition according to any of the preceding claims, characterized in that it further comprises component (d), a flammability suppressing agent. 9. A composition according to claim 8, characterized in that the component (c) is present in an amount of up to 19% by weight, based on to the composition and component (d) is present in an amount of up to 20% by weight based on the composition. 10. A composition according to claim 8 or claim 9, characterized in that the flammability suppressing agent is 1,1,1,2,2,3,3-heptafluoropropane, 1, 1, 1, 2, 3, 3, 3-heptafluoropropane, octafluorocyclobutane, octafluoropropane, trifluoromethoxytrri-fluoromethane, difluoromethoxytrifluoromethane, trifluorome-toxipentafluoroethane, difluoromethoxy-pentafluoroethane, tri-fluoromethoxy-1,2,2,2-tetrafluoroethane or a mixture of two or more thereof. A composition according to any of the preceding claims, characterized in that it has a vapor pressure that is not greater than ± 60 KPa (0.6 bar) of the vapor pressure of R134a at a temperature between -30 ° C and +60 ° C. 12. A composition according to any of the preceding claims, characterized in that the ratio of the total number of fluorine atoms in the composition to the total number of hydrogen atoms in the composition is at least 1.25: 1. 13. A composition according to any of the preceding claims, characterized in that component (a) is R134 and / or Rl34a, component (b) is R600 and / or R600a and component (c) is R152a, R227ca, R227ea or a mixture of two or more thereof. 14. A composition according to any of the preceding claims, characterized in that component (a) is R134 and / or R134a, component (b) is R600 and / or R600a and component (c) is R152a. 15. A composition according to any of claims 1 to 13, characterized in that component (a) is R134 and / or R134a, component (b) is R600 and / or R600a and component (c) is R227ca and / or R227ea. 1g The use of a composition according to any of the preceding claims, characterized in that it is used as a refrigerant in a compression refrigerant apparatus that contains no more than 1 kg of refrigerant. 1
7. 7. A process for producing refrigeration, characterized in that it comprises the condensation of a composition according to any of claims 1 to 15 and thereafter evaporation of the composition in the vicinity of a body to be cooled. 1
8. 8. A compression refrigeration apparatus, characterized in that it contains as a refrigerant a composition according to any of claims 1 to 15.